CIRP ANNALS 1997
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STC A |
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Stream-of-variation theory for automotive body assembly
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S.J. Hu / Y. Koren (1)
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STC A, 46/1/1997, P.1
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Keywords: Assembly, Dimension, Quality Assurance |
Abstract : Manufacturing systems usually consist of processes and machines in a
multi-leveled hierarchy. As a result, dimensional variation in the final
product is accumulated as the product moves along the manufacturing
system. This paper discusses the prediction and diagnosis of dimensional
variation in a multi-leveled automotive body assembly system. By
combining engineering structural models with statistical analysis, the
evolution of the variability and stiffness characteristics of sheet
metal parts is studied in terms of assembly configurations, i.e., serial
or parallel. The diagnosability of serial and parallel assembly systems
is evaluated. These results are integrated with correlation clustering
to form a complete diagnostic strategy. Predicting and diagnosing
variation in a multi-leveled manufacturing system constitute the two
aspects of what we call the "Stream-of-Variation Theory."
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Growth into miniaturization - flexible micro-assembly automation
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G. Reinhart, M. Höhn / J. Milberg (1)
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STC A, 46/1/1997, P.7
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Keywords: Assembling, Automation, Micro-Handling |
Abstract : The particular problems which occur during the assembly of miniaturized
components result from their small dimensions.. their high sensitivity
to damage and the micron-range precision required in the assembly
process. Examples are provided to illustrate strategies for flexible
micro-assembly automation: the implementation of new, problem-oriented
assembly techniques and components and the optimization of conventional
handling systems. The accuracy attainable by an automated micro-assembly
system depends decisively on the ability to compensate for inevitable
handling tolerances. Active as well as passive techniques for
compensating tolerances during micro-assembly have been examined and
their operating limits will be described. The precision assembly of a
modern radio-controlled wrist watch will serve as an example of
developments in assembly modules.
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Co-operation of man and robot assembly - an evaluation of an industrial flexible assembly system
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P. Holmstedt, L. Martensson, A. Arnström (2)
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STC A, 46/1/1997, P.11
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Keywords: Automation, Assembly Machine, Human |
Abstract : In 1986 a totally new concept for flexible automatic assembly cells was
launched within the research team "Assembly group", IVF/KTH, Department
of Manufacturing Systems. A prototype, Mark II , was built and tested in
the laboratory, and the industrial version, Mark II F, was installed in
a company in 1991, where it carried out the automatic assembly of air
motors for handheld tools.
After five operational years, the system has been evaluated from a
technical and human-factors point of view. The paper will discuss the
whole development process, from the initial conceptual idea spawned by
the university research group, to the experiences gathered by management
and personnel of the system.
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Assembly by non-grasping manipulation
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T. Arai (1), J. Ota, Y. Aiyama
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STC A, 46/1/1997, P.15
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Keywords: Assembly Machine, Manipulator, Holonic System |
Abstract : This paper deals with assembly and transportation of /non-grasping
manipulations, /especially releasing. In releasing, a robot makes a part
slide away on a plane. It has both advantages and disadvantages.
Learning control using visual feedback is introduced so as to
accommodate the uncertainty of the manipulation and environment.
Experiments verifies that releasing is potent to construct a flexible
transportation system. The research makes assembly more dexterous and
flexible enough to make a Holonic Manufacturing System.
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STC C |
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Predictive cutting model for forces and power in self-propelled rotary tool turning operations
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E.J.A. Armarego (1), R.K. Katta
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STC C, 46/1/1997, P.19
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Keywords: rotary tool turning, cutting models, predictive force modelling |
Abstract : A predictive model for the three force components and power in the
ingenious self-propelled rotary tool turning operations is presented and
experimentally verified for both TiN coated and uncoated carbide tools.
The model based on the 'unified mechanics of cutting approach' and the
fundamental rotary tool cutting processes reported earlier incorporates
all the tool and cut variables. It is shown that this operation can be
represented by a number of equivalent 'classical' oblique cutting
elements of positive and negative inclination angles about an equivalent
'classical' orthogonal cutting element which controls the rotary tool
speed and whose location is at the point where the torque on the rotary
tool is zero for a frictionless tool spindle axis. The model predictions
have encompassed and confirmed the few reported experimental trends
noted in the literature and shown that the TiN coating only marginally
reduces the power but with larger reductions in the radial and feed
force components. The importance of modelling complex practical
machining operations is highlighted in this work.
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On the dynamics of chip formation in machinig hard metals
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M.A. Davies, T.J. Burns, C.J. Evans (2)
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STC C, 46/1/1997, P.25
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Keywords: cutting, chip formation, modelling |
Abstract : The results of orthogonal cutting tests on electroplated
nickel-phosphorus (15%37; phosphorus) and AISI 52100 bearing steel are
presented and compared. For both materials, chips become segmented at
relatively low cutting speeds (0.3 m/s to 2 m/s) due to the onset of an
oscillation in the material flow that is manifested in the repetitive
formation of localised shear bands. The average spacing between the
shear bands increases monotonically with cutting speed and
asymptotically approaches a limiting value that is determined by the
cutting conditions and the properties of the material being cut. The
similarity in the behaviour of the two materials (which have
significantly different microstructure) and the regularity of the shear
band pattern observed in the chips provides strong evidence for a
continuum mechanics model of the process. A simplified one-dimensional
thermo-mechanical model of a continuous, homogeneous material being
sheared by an impinging rigid wedge is developed to explain the observed
behaviour. Numerical simulations of this model show that at low wedge
speeds, material deformation reaches a thermo-mechanical equilibrium,
in which material flow is homogenous and the stress, strain-rate and
temperature fields reach a steady state behaviour that is constant in
time (when viewed from a tool-fixed reference frame). As the wedge speed
is increased, the stress, strain-rate and temperature fields become
oscillatory, and the material flow becomes inhomogenous. As the speed of
the wedge is increased further, the material shows repetitive shear
localisation, with the distance between shear zones increasing
montonically to some limiting value, as was observed in experiments.
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Brittle/ductile transition phenomena observed in computer simulations of machining defect-free monocrystalline silicon
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T. Inamura, S. Shimada (2), N. Takezawa, N. Nakahara
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STC C, 46/1/1997, P.31
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Keywords: cutting, brittle ductile transition,simulation |
Abstract : By using renormalized molecular dynamics (RMD) proposed by the authors,
computer simulations of machining defect-free monocrystal silicon of
various sizes have been carried out to investigate crack initiation
process. The results show that a defect-free monocrystal silicon can be
machined in ductile mode to any scale in an absolute vacuum but exhibits
brittle-ductile transition depending on the scale of machining under
normal atmosphere. In this paper, detailed mechanism of the process of
crack initiation is discribed together with the discussion of micro
dynamics on why ductile mode machining is always possible either in
small scale or in case of f.c.c. metals.
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Continuous flank wear measurement of turning tools by integrated micro-thermocouple
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C. Barlier, C. Lescalier / A. Moisan (1)
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STC C, 46/1/1997, P.35
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Keywords: cutting tool, flank wear, temperature |
Abstract : This paper deals with a study of the correlation between wear and
temperature in metal cutting. A thermocouple is implanted into the
carbide insert of a turning tcol. The evolution of the temperature
signal at the tool/workpiece interface nearest to the cutting edge is
displayed continuously. The application of the analytical model of
Kitagawa and al., related to a thermal approach of the cutting
phenomenon, allows the establishment of an analytical model for the
temperature measured by the probe depending on the flank wear. The model
is verified by tests at constant sliding speed on carbon steel.
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Nanocoatings on cutting tools for dry machining
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F.M. Kustas, L.I. Fehrenbacher, R. Komanduri (1)
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STC C, 46/1/1997, P.39
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Keywords: coatings, tool, machining |
Abstract : Novel material systems for coatings on cutting tools, towards
accomplishing clean manufacturing, i.e. without the use of a cutting
fluid, are presented. They involve use of multilayer nanocoating
architectures of carbide/metal or solid lubricant/metal on cemented
carbide tools by physical vapor deposition (PVD) process, namely,
magnetron sputtering. By providing numerous (literally hundreds of
layers) alternate nanolayers of hard and tough, hard and hard, or solid
lubricating and tough materials, it is possible to take advantage of the
unique properties of nanostructures, namely, higher hardness, higher
strength, higher modulus, higher wear resistance, higher fracture
toughness, higher chemical stability, and reduced friction than their
counterparts where the coating layer thickness is in the micrometer
range. Various features of these coatings are discussed from the point
of view of their application in dry machining.
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A new advanced ceramic for dry machining
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N. Narutaki (2), Y. Yamane, S. Tashima, H. Kuroki
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STC C, 46/1/1997, P.43
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Keywords: ceramic, tool, machining |
Abstract : Concerns toward safety of the work environment as well as the
environment in general are compelling industry to adopt 'green' or 'dry'
machining, i. e. without the use of any cutting fluid. Since, some of
the benefits of the cutting fluids are not going to be available in dry
machining, need exists for the development of a more refractory,
tougher, chemically wear resistant, and hard cutting tool materials. In
this paper, the synthesis and evaluation of a new alumina ceramic tool
material using very pure (99.99%37;) and submicron grain size (0.22 µm)
alumina powder with practically no binder sintered at low temperature
(1230°C) (i.e. without the need for HIP'ing) are presented. This
material is found to be stronger and harder than conventional HIP'ed
alumina ceramic. The new alumina ceramic was found to be more wear
resistant and fracture resistant (against both mechanical and thermal
shock) than conventional alumina in dry turning and milling of gray cast
iron and S45C carbon steel.
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A sensor integrated tool for cutting force monitoring
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M. Santochi (1), G. Dini (2), G. Tantussi, M. Beghini
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STC C, 46/1/1997, P.49
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Keywords: tool condition monitoring, turning, cutting force measurement |
Abstract : This paper describes the development of a new concept of cutting tools
using strain gages for the measurement of forces in turning operations.
The basic idea is the integration of the sensor within the tool shank,
in order to obtain a system which is easy to use, easy to install and
capable of transmitting data to the CNC through wireless equipment. In
particular, the output signal of the measurement bridge is amplified and
sent to an external data acquisition system by infra-red transmission.
The present paper reports the design principles and the results of some
machining tests illustrating the behaviour of the tool in different
cutting conditions.
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In-process monitoring method for machining environment based on simultaneous multiphenomena sensing
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H. Shinno, H. Hashizumz / H. Sato (1)
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STC C, 46/1/1997, P.53
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Keywords: cutting, in-process monitoring, multifunctional sensor |
Abstract : The successful implementation of intelligent manufacturing systems
requires in-process monitoring of the machining environment. The
monitoring system should be capable of extracting multifaceted
information about the environment. However, most current systems are
based on single phenomenon monitoring, so their effectiveness is quite
limited. In this paper, a new multifunctional in-process monitoring
method has been proposed. This method, based on simultaneous
multiphenomena sensing, can monitor multidimensional responses
simultaneously. Through experiment and simulation, it has been verified
that the method is effective and applicable to monitoring in a machining
environment.
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High speed milling of dies and molds in their hardened state
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M.A. Elbestawi (1), L. Cheng, E. Becze, T.I. El-Wardany
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STC C, 46/1/1997, P.57
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Keywords: milling, dies and mold, cubic boron nitride (CBN) |
Abstract : This paper presents an experimental investigation of high speed milling
of dies and molds. Several critical issues involved with the high speed
milling of H13 tool steel of hardness up to 55 HR., have been studied
and explained from a detailed analysis of experimental observations. The
experiments were performed using several grades of PCBN ball-nose end
mills with various edge preparations. The effect of different process
parameters on the tool performance and the surface finish produced was
also investigated. The cutting parameters involved were; cutting speeds
in the range of 220 to 1320 m/min, feed variation from 0.0254 to 0.1
mm/tooth, axial depth of cut from 0.625 up to 2 mm, and radial width of
cut of 0.254 mm. During the preliminary experimental investigation, the
tilt angle was kept constant at 10 degrees. Several tests were conducted
to study the effect of the different tool path directions on the cutting
tool performance. Dry and wet cutting conditions were used and the
effect of coolant on the tool life was also determined. The optimum
cutting conditions have been specified based on the modes of tool
failure, tool life and surface integrity produced.
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Burr formation in drilling miniature holes
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J.M. Stein, D.A. Dornfeld (1)
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STC C, 46/1/1997, P.63
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Keywords: burr, formation, drilling |
Abstract : The exit burrs in the drilling of precision miniature holes of diameters
less than 1 mm are of interest. The burrs from these processes can be
difficult to remove. This paper describes the results of a study on the
burr formation in drilling miniature holes. Most existing studies focus
on holes in the 3 mm to 12 mm size range. This data is not transferable
to smaller diameter holes. We report here on the study of burr height,
thickness and geometry observed in the drilling of 0.91 mm diameter
through holes in stainless steel 304L. The sensitivity of feed, speed
and-drill wear as well as the exit surface geometry (i.e. for
intersecting holes) was determined. A proposal for using the drilling
burr data as part of a process planning methodology for burr control is
presented.
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STC Dn |
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Co-operative design, manufacturing and assembly of complex products
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G. Seliger (2), H. Karl, H. Weber
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STC Dn, 46/1/1997, P.67
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Keywords: co-operative, design, assembly |
Abstract : As customer requirements rise and time to market shrinks the need for
global sourcing of development, manufacturing, and assembly capacity
increases.
This paper presents a method far integrating design and manufacturing
engineers from different companies into a virtual value-adding team. The
method is based on network theory using circuits to describe the flow of
information originating from customer requirements. These circuits
sustain the context of specific activities to the overall task during
requirements analysis, design, and system integration. A blackboard
model based on the combination of these circuits together with design
structure matrices visualizes and guides the course of action curing a
product development project. T his blackboard enables international
development consortia to work jointly on new products and processes in a
selforganized manner with limited effort for project management.
The design of a public transport system serves as an example to
illustrate this method.
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An integrated modular design methodology for life-cycle engineering
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P. Gu, M. Hashemian, S. Sosale / E. Rivin (1)
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STC Dn, 46/1/1997, P.71
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Keywords: design, module, methodology |
Abstract : Modular design seeks to develop products with distinct detachable
modules for rapid product development, easy recycling, possible reuse of
long-lasting modules, efficient upgrading, reconfiguration and other
life cycle engineering objectives. However, each objective may require a
different modularization. In this paper, we present an integrated
modular design methodology for achieving multiple objectives. The
methodology identifies the factors related to the objectives, relates
these factors to design components through interaction analysis, and
clusters components into modules using a genetic algorithm based
technique. A case study is included to illustrate the methodology and
the algorithms.
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Design of systems
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N.P. Suh (1)
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STC Dn, 46/1/1997, P.75
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Keywords: design, axioms, system |
Abstract : Engineering projects, including those 'n manufacturing, involve systems
from design to construction to operation. The most important aspect is
design since system performance depends on the quality of design
Mechanical systems design is complicated by difficulties in modeling,
interplay of hardware and software, lack of scale-up rules, and the
inclusion of human operators. Traditionally, systems have been designed
based on know-how and trial-and-error, however, this empiricism can lead
to costly mistakes. In this paper, a rational means of designing systems
based on axiomatic design is discussed. It presents the procedure for
systems design and a representation technique for system architecture.
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Methodology and product model for integrated design using a multiviews system
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S. Tichkiewitch, M. Véron (1)
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STC Dn, 46/1/1997, P.81
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Keywords: design, integration, product |
Abstract : A methodology of integrated design is presented, based on the
co-operative work between the partners of the life-cycle of the product.
A product model, which is a link between a knowledge model and a data
model, accommodates specific decisions of each participant in a
multi-view system. Two exchange modes are available to the users : a
formal one is the standard network between computers and gives access to
a common product database and an informal one that uses a multi-media
network in order to permit dialogue between participants. The prototype
of such a design modeller is realized with an object oriented language.
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Automatic reasoning for design under geometrical constraints
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M. Shpitalni (1), H. Lipson
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STC Dn, 46/1/1997, P.85
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Keywords: CAD, conceptual design, geometry constraint |
Abstract : Parametric design is very stable but requires a predefined dimensioning
and ordering scheme, thus limiting flexibility and precluding sketch
input. Variational geometry design, while general and flexible,
necessitates intensive use of numerical solvers to solve many
simultaneous nonlinear equations. Frequently the solvers cannot solve
these equations. A new system, based on an original theory for automatic
constraint analysis, has been developed for solving sets of
two-dimensional geometric constraints in product design. The proposed
system offers the flexibility of variational based design along with the
stability of parametric design. The solution strategy is based upon
breaking down the problem into a sequence of construction steps. When no
sequential construction is found, auxiliary geometrical constructions
are automatically generated based on rules for relocating constraints.
Thus, an apparently simultaneous constraint set is converted into a set
that can be constructed sequentially by decomposing strongly connected
components of the original constraint graph. This new approach has been
implemented in a system for designing sheet metal parts.
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A model fusion approach to support negotiations during complex engineering systems design
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S.C.Y. Lu (2), D. Li, J. Cheng, C.L. Wu
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STC Dn, 46/1/1997, P.89
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Keywords: modeling, system, design |
Abstract : Computer models have been playing important roles in modern design,
particularly at the component and subsystem levels. As competition
increases, the challenge of design has shifted from individual
components to overall systems. Alternative paradigms, different models
and new approaches for using these models are needed to support system
designs. This paper presents a "Model Fusion" approach to enable a new
paradigm which views engineering design as a collaborative negotiation
process. The "Model Fusion" approach fuses (or integrates) separate
design and analysis models into a cohesive set of hierarchical empirical
models to allow for explicit trade-off between competing modeling
objectives, AIMS (Adaptive and Interactive Modeling System), an
integrated empirical modeling tool with multiple learning and
decomposition algorithms, is used to implement the "Model Fusion"
approach. A real world application example of engine combustion chamber
design, drawn from the automotive industry, is included to demonstrate
the paradigm, approach, application and impact of this research.
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Enhanced rapid prototyping for faster product development processes
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F.-L. Krause (2), M. Ciesla, Ch. Stiel, A. Ulbrich
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STC Dn, 46/1/1997, P.93
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Keywords: design, rapid prototyping, CAPP |
Abstract : Rapid Prototyping (RP) is useful in the fast production of physical
prototypes and therefore constitutes a key element in the optimization
and abbreviation of product development processes. To increase the
accuracy and decrease the fabrication time of prototypes, an RP-Toolkit
was developed supporting the overall CAPP process. The RP-Toolkit
provides functional modules for repair of surfaces, technological
planning of various RP processes as well as mechanisms for realization
of STEP-based process chains. An essential aspect is the user-driven
definition and adaptation of technological parameters to meet prototype
requirements. Improvements in prototype quality are gained by use of
process-specific production strategies. The build time of prototypes can
be reduced using functions for adaptive slicing of precise BREP models.
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Modeling in reverse engineering for injection molding analysis of 3D thin objects
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A. Fischer (2), A. Smolin
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STC Dn, 46/1/1997, P.97
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Keywords: reverse engineering, molding, modelling |
Abstract : Reconstructing a 3D sampled object into a computerized model is an
essential part of reverse engineering. Applications such as casting and
injection molding, however, also require a more abstract mid-surface
representation for analysis. Reconstructing a mid-surface from a thin
object is known to be difficult and time consuming. In this paper, a
reverse engineering method is proposed for simultaneously reconstructing
a 3D object and its mid-surface. The object and the mid-surface models
are created so that their mutual relations enable subsequent
interactions between design and analysis, needed according to simulation
results. The stages in modeling the reverse engineering object and its
mid-surface are: (1) sampling and filtering points through a data
reduction algorithm; (2) recognizing dominant pairs of boundaries; (3)
parametrizing object boundaries and finding parametric correlations
between them, according to mid-surface definition; and (4)
reconstructing a 3D object and its mid-surface. Error analysis, results
and examples will be demonstrated.
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Allocation of geometric tolerances : new criterion and methodology
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A.O. Nassef, H.A. ElMaraghy (1)
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STC Dn, 46/1/1997, P.101
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Keywords: design, tolerancing, optimization |
Abstract : This paper presents a new approach to the synthesis of geometric
tolerances in the design process. In the published literature minimum
cost has been the main criterion for tolerance allocation. Although this
is satisfactory for dimensional tolerances, extending it to geometric
tolerances presents a major drawback. The reason is that for each
feature the number of combinations of tolerance types is large This
paper presents a novel approach to the tolerance allocation problem that
consists of 2 steps: (i) the manufacturing processes that minimize the
production cost are chosen, then (ii) the types and magnitudes of
geometric tolerances are optimized using genetic algorithms to reduce
the probability of rejecting good parts or accepting bad parts during
inspection, where a bad part is a one which will cause a violation of
the assembly functional requirements.
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Cost decision support in product design
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A. Liebers, H.J.J. Kals (1)
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STC Dn, 46/1/1997, P.107
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Keywords: cost estimating, design |
Abstract : The constraints addressed in decision making during product design,
process planning and production planning determine the admissible
solution space for the manufacture of products. The solution space
determines largely the costs that are incurred in the production
process, in order to be able to make economically sound decisions,
costing data support must be integrated into the decision making
processes. Regarding product design, the designer must be supplied with
transparent costing data, that is ready for direct application. In this
paper a functional architecture for costing data support during product
design, as well as a corresponding data structure are presented.
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STC E |
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High-pressure water peening-a new mechanical surface strengthening process
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H.K. Tönshoff (1), F. Kroos, C. Marzenell
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STC E, 46/1/1997, P.113
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Keywords: water peening, residual stress, fatigue strength |
Abstract : Water peening with pressures up to 100 MPa has been developed as a new
mechanical surface strengthening process. The high-frequent impact of
water drops on the surface of steel components causes local plastic
deformation. As a result, high compressive residual stresses are induced
in the surface-near layers. The special characteristic is that surface
roughness and topography show only negligible modifications, so water
peening can be used as a finishing process_ Due to the beneficial
modifications in the surface-near material, fatigue strength
significantly increases. The water jet's high geometrical accessibility
predestines this new process for treatment of complex geometries.
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Temperature of work materials irradiated with CO2 laser
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T. Ueda, K. Yamada, K. Nakayama (1)
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STC E, 46/1/1997, P.117
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Keywords: laser beam machining, temperature, measurement |
Abstract : Temperature of a workpiece irradiated with CO_2 , pulse laser, which is
one of the most important factors for deciding the suitable conditions.
In the cleavage cutting of brittle materials and the forming of sheet
metals, is investigated experimentally and theoretically. The surface
temperature is measured by a new type of Infrared Radiation Pyrometer
using a fused fiber coupler. This pyrometer makes it possible to measure
the flush temperature of a very small object without emissivity
influencing the results. The temperature distribution in the surface
layer of the workpiece is calculated numerically using FEM. The energy
absorptivity of the workpiece is obtained by comparing the experimental
results with the calculated ones.
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High performance hydraulic valves welded by laser
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M. Cantello (2), L. Bonello, G. Fontana, Z. Li
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STC E, 46/1/1997, P.123
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Keywords: laser beam machining, welding, quality assurance |
Abstract : The Hydraulic valves require a high precision in dimension tolerance and
absence of any defects for the high stress levels involved in the
services of these components. A laser welding technique for the
fabrication of hydraulic valves is presented, in which the butt welds
joining AIS1304L to AIS112L13 were performed in such a way as to control
solidification cracking and microfissuring. Metallurgical analyses
revealed that both solidification cracking in the fusion zone and
microfissuring in the heat-affect zone result from S, Pb, P contained in
AIS112L13. A 0.12 mm off-set of the laser beam towards AIS1304L and an
impingement angle of 15° with respect to the fit-up face of butt joints
can produce sound welds on hydraulic valves made of 0.9 mm thick
AIS1304L and AIS112L13. Tests on mechanical properties of the hydraulic
valves revealed goodstrength, welds, high repeatability, and
reliability of welding parameters adopted. A high accuracy seam tracking
sensor, coupled with an on-line monitoring system, has been developed
for process control and quality assurance.
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Experimental study of the basic process mechanism for direct selective laser sintering of low-melting metallic powder
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Y.A. Song / W. König (1)
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STC E, 46/1/1997, P.127
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Keywords: rapid prototyping, laser, sintering |
Abstract : Due to the still limited mechanical properties of the materials which
can be processed using industrially available rapid prototyping
techniques, work is currently being undertaken to develop methods of
manufacturing metallic prototypes directly. This paper reports on the
process development of Selective Laser Sintering (SLS) for direct
sintering of bronze as a low-melting metallic powder on a laboratory
test facility. The experimental investigations with single spots, lines
and layers on the powder bed indicate successful direct sintering of
bronze powder without polymer binder or preheating. Besides the process
parameters such as laser beam power, scanning speed and hatching
distance, material parameters such as particle size distribution exert
an influence on the melting behavior and should, therefore, be
considered in terms of further process development.
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Development of a droplet-based manufacturing process for freeform-fabrication
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C.A. Chen, J.H. Chun / G. Sohlenius (1)
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STC E, 46/1/1997, P.131
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Keywords: rapid prototyping, deposition, processing |
Abstract : Droplet-Based Manufacturing processes are now widely used in many
industrial applications, including spray forming and rapid prototyping.
Application of these processes to freeform fabrication, however, has
been greatly hampered by the lack of accurate control over droplet
generation and droplet deposition. In order to overcome such
shortcomings, a high-precision, uniform-droplet deposition process has
been developed. This paper presents the design rationale for the process
and its use to determine a key process parameter: the in-flight droplet
liquid fraction.
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Fabricating metal objects using layer manufacturing technology and powder metallurgy science
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J. Bakkelund, R. Karlsen, OE. Björke (1)
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STC E, 46/1/1997, P.135
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Keywords: rapid prototyping, sintering, metal |
Abstract : In order to produce metal objects using Layer Manufacturing Technology,
a new fabricating method is introduced by the authors. The layers in the
new layer manufacturing process are generated by attracting metal powder
to a charged photoreceptor under the influence of an electrostatic
field, whereupon they are deposited one by one on a building table.
After each deposit operation the layer of loose powder is consolidated
using simultaneous pressure and sintering. This paper studies the layer
generation system and the consolidation system, and investigate the
results from these two systems. The present work proves that the new
layer manufacturing process has the potential to become a manufacturing
system capable of direct fabrication of objects in metal.
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Forced discharge dispersion by dot-matrix method
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N. Mohri (2), K. Furutani, K. Shirai, T. Enami
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STC E, 46/1/1997, P.139
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Keywords: electrical discharge machining (EDM), surface, servomechanism |
Abstract : The quality of the surface machined by electrical discharge machining
(EDM) depends on the degree of discharge dispersion. In this paper a
dot-matrix EDM with scanning motion is proposed in order to realize
rapid prototyping by EDM and to control the discharge position in real
machining. The machining process by the dot-matrix method is similar to
the printing motion with a dot impact printer. The developed machining
unit has six electrode feeding devices each of which controls the
position of a thin wire electrode independently by inchworm mechanism
with piezoelectric actuators. Discharge current is supplied to each wire
electrode also independently in order to realize complete discharge
dispersion. 3 dimensional shape with crack-less surface is machined by
scanning motion of the unit.
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Electrical discharge machining in gas
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M. Kunieda, M. Yoshida / N. Taniguchi (1)
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STC E, 46/1/1997, P.143
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|
Keywords: EDM in gas, die sinking, oxygen gas, oxidation, tool electrode wear, tool path |
Abstract : In this paper, we show that electrical discharge machining (EDM) can be
achieved in gas. With the help of a high-pressure gas flow supplied
through a thin-walled pipe electrode, the molten workpiece material can
be removed and flushed out of the working gap without being reattached
to the electrode surfaces. The greatest advantage of this technique is
that the tool electrode wear ratio is almost zero for any pulse
duration. Hence a 3D shape can be machined very precisely using a
special NC tool path which can supply a uniform high-velocity air flow
over the working gap. Furthermore, the material removal rate is improved
as the concentration of oxygen in air is increased, due to oxidation of
the electrode materials.
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WEDM adaptive control with a multiple input model for identification of workpiece height
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K.P. Rajurkar (2), W.M. Wang, W.S. Zhao
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STC E, 46/1/1997, P.147
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|
Keywords: wire EDM, adaptative control, identification |
Abstract : The variation in power density during wire electrical discharge
machining (WEDM) results in reduced productivity and wire rupture. This
paper presents a WEDM adaptive control system that optimizes on-line the
sparking frequency by estimating the workpiece height with a new
multiple input model. This model describes the dynamic and stochastic
relationships between average gap feedback voltage and spark frequency
and machine table feed rate. Extensive experiments have been carried out
to verify the new model. The proposed system correctly identifies the
workpiece height and avoids the sudden rise in the estimated height
found in existing system.
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Micro-linear motion bearing produced by anisotropic etching of silicon
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N. Moronuki, Y. Furukawa (2)
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STC E, 46/1/1997, P.151
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|
Keywords: micro-linear bearing, anisotropic etching, friction |
Abstract : This paper demonstrates the applicability of silicon anisotropic etching
to the production of linear motion bearing. Machining accuracy of this
etching depends not on the copying rule but the crystal regularity. As a
result, accurate shapes such as V-grooves can be machined without
precise control. The etched V-grooves are applied to the linear bearing
system whose slider size is of the order of sub-millimeters and its
stroke is about 3mm. First, the geometrical accuracy is evaluated. Then,
the slider is driven by an actuator and the frictional force was
measured. The coefficient of friction exceeds 3 in this case. Finally,
the possibility of larger scale and more precise application is discussed.
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Magnetic dispersion of micro particles using magnetic fluid - application to texturing process for magnetic rigid disk -
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N. Umehara, K. Kato, K. Suzuki / A. Kobayashi (1)
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STC E, 46/1/1997, P.155
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|
Keywords: roughness control, micro plastic deformation, aluminium alloy |
Abstract : In order to make well-arranged asperities on Al-alloy substrates of
magnetic rigid disk as a texturing process, a new texturing method using
magnetic fluid and magnetic field was developed, and its fundamental
properties were shown. By applying magnetic field and normal load to the
magnetic fluid including 4 ?m SiO_2 micro particles in the gap between
the Al-alloy substrate and the glass plate, well-arranged micro
particles were indented to the substrate and then made well-arranged
asperities. It is concluded that magnetic field controlled the density
of micro particles and the distance between micro particles well.
|
STC F |
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Determination of the r-value using automatic tensile test equipment
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J. Danckert (2), K.B. Nielsen
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STC F, 46/1/1997, P.159
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|
Keywords: uniaxial tensile test, sheet metal, anisotropy |
Abstract : When the r-value of sheet material is determined using automatic tensile
test equipment, it is required by the norms that compensation for the
elastic strains is made. In Stahl-Eisen Prüfblatt 1126 a compensation
method is suggested:, however it is believed that this method is wrong.
The paper proposes a compensation method and it is verified
experimentally, that the proposed method yields a r-value which is
almost identical to the r-value obtained from measurements carried out
on the tensile test specimen in unloaded conditions.
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|
New model of flow stress under cold forming conditions
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P. Huml (1), D. Zonghai, Y. Wei
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STC F, 46/1/1997, P.163
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|
Keywords: cold rolling, wire drawing, cold forging |
Abstract : Prediction of flow stress under forming conditions is commonly based on
an explicit formulation of the flow stress mode': The flow stress is in
this case expressed as a function of strain, strain rate, temperature,
more seldom or structure. Such formulations make it difficult to predict
the flow stress under forming conditions for different strain paths and
also wren the strain rate and/or temperature varies during the deformation.
This paper is aimed at describing a new model of strain hardening
applied in metal forming analysis. This model allows better prediction
of flow stress under cold forming conditions. The application of the
incrementally formulated flow stress mode' is exemplified for prediction
of met 3' flow. loads and temperature distribution -n cold forming
processes.
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|
Springback evaluation in fully 3-D sheet metal forming processes
|
|
F. Micari (2), A. Forcellese, L. Fratini, F. Gabrielli, N. Alberti (1)
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|
STC F, 46/1/1997, P.167
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|
Keywords: springback, bending, FEM |
Abstract : In the modern manufacturing industries the knowledge and proper control
of the sheet metal springback after forming is a fundamental aspect in
the achievement of near net shape stamped parts. In this paper an
effective springback prediction in some fully three-dimensional stamping
processes is carried out. Such a prediction is based on a combined
approach in which an explicit finite element code has been employed to
simulate the forming phase while a traditional implicit procedure has
been used to analyse the springback phase. The results obtained have
been compared with a set of experimental tests and an excellent
correlation between the predicted and experimental data has been found.
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|
New developments for the qualification of technical surfaces in forming processes
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|
M. Geiger (1), U. Engel, M. Pfestorf
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|
STC F, 46/1/1997, P.171
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|
Keywords: topography, rolling, forming |
Abstract : In modern sheet metal forming, blank topographies are characterized by
various quite different and rather sophisticated structures. This is due
to the various deterministic or semi-deterministic methods of surface
texturing produced by skinpass rolling. The conventional surface
parameters determined from profile data are not capable of
characterizing such surfaces, in particular with respect to their
functional behavior. Thus, there is a strong demand for the development
of new parameters which can only be determined via the measurement of
area. With special respect to the application of deterministically
textured topographies in metal forming, appropriate 3d surface
parameters can be derived from the mechanical rheological model recently
developed at the Institute of Manufacturing Technology. These are the
maximum ratio of closed void area and the closed void volume, both of
which result from a special evaluation of the bearing ratio curves.
Industrial applications show that these parameters can be related to the
functionality of the surface and hence may be regarded as very suitable
for the characterization and qualification of complex surface structures.
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|
Topography deformation of sheet metal during the forming process and its influence on friction
|
|
D. Schmoeckel (1), M. Prier, J. Staeves
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|
STC F, 46/1/1997, P.175
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|
Keywords: shit metal forming, tribology, topography |
Abstract : The potential offered by modern texturing technologies for sheet metal
cannot be fully used due to the fact that the characteristics of
topographies optimised for tribological conditions are unknown. Besides
experimental examinations, the development of new topographies requires
an understanding of the basic phenomena of topography. Simulation of
the material deformation occurring in the topography during the forming
process using 3D finite element models provides results that cannot be
obtained by measuring techniques. The simulation is complemented by
measuring the topography before and after the forming process. Based on
these results, optimised topographies and new 3D roughness parameters
for the characterisation of their tribological properties are achieved.
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|
Effect of glass lubricant behavior on the surface quality of extrudates in glass lubricated hot extrusion
|
|
D. Damodaran, R. Shivpuri (2)
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|
STC F, 46/1/1997, P.179
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|
Keywords: hot extrusion, glass lubrification, surface quality |
Abstract : In glass lubricated hot extrusion, the behavior cf the glass lubricant
is quite sensitive to process conditions and die design. The use of
improper conditions can lead to surface defects. The typical thickness
of the glass film is very small (? 40 microns), making measurement
difficult and numerical analysis of lubricant behavior impractical. A
mathematical model for glass lubrication is presented which enables an
analysis of the effects of processing conditions on the thickness, flow
stability and supply of lubricant over the stroke of the extrusion
press. Correlations are drawn between predictions of lubricant thickness
and flow stability and experimental observations of extrudate surface
quality. Thus, this model can be used in the determination of optimum
operating conditions for glass lubricated hot extrusion.
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|
Flow simulation of semi-solid forging by FEM
|
|
N. Kim, J.H. Yoon, D. Li, S.I. Oh (1)
|
|
STC F, 46/1/1997, P.183
|
|
Keywords: semi-solid forging, simulation, flow stress |
Abstract : The flow behaviour of semi-solid material is outlined and discussed. A
representation of flow stress for AI-2024 in the semi-scud state and a
numerical algorithm for updating the solid fraction during forging are
proposed. Flow simulation by the finite element method in closed die
forging to fabricate an automobile part has been performed and compared
with experimental results. The information obtained from the simulation
results are utilized in designing the preforms.
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|
Simulation of metal flow and fracture-applications in orthogonal cutting, blanking and cold extrusion
|
|
E. Ceretti, E. Taupin, T. Altan (1)
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|
STC F, 46/1/1997, P.187
|
|
Keywords: finite element method, plasticity, fracture |
Abstract : This paper summarizes the work done or, the prediction of the ductile
fracture initiation and propagation in plastic deformation processes. A
commercial finite element code has been modified and fracture criteria
have been implemented for the study of material separation. In
particular, ductile fracture is simulated by deleting the mesh elements.
Cracking starts when the element damage value reaches the "critical
value", determined by experiments. The program has been tested on
several plastic processes, such as orthogonal cutting, blanking and cold
direct extrusion. The predictions show a good correlation with
experimental results in terms of crack propagation and capability to
predict internal defects.
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|
Analysis and design of multi-blow hammer forging processes by the explicit dynamic finite element method
|
|
D.Y. Yang (2), Y.H. Yoo
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|
STC F, 46/1/1997, P.191
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|
Keywords: hammer forging, process analysis, dynamic FEM |
Abstract : In the present work the numerical simulations of multi-blow hammer
forging, as a high-velocity impact deformation phenomenon, are
described. The explicit time integration finite element method is used
to compute the workpiece deformation. The effects of strain hardening,
strain rate hardening and thermal softening are considered. Through the
simulation of copper blow test, the developed program has been verified.
As an industrial example, multi-blow forging of a turbine blade using
counterblow hammer has been simulated. Through the simulation of turbine
blade forging, it has been shown that the developed explicit finite
element program can be successfully applied to simulation of other
practical industrial parts.
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|
Numerical analysis of cross shear plate rolling
|
|
W. Zhang, N. Bay (1)
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|
STC F, 46/1/1997, P.195
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|
Keywords: rolling, shear zone, numerical analysis |
Abstract : The rolling process is widely applied for industrial production of metal
plates. In conventional plate rolling the two work rolls are rotating at
the same peripheral speed. By introducing a specific difference in the
speed of the two work rolls, cross shear rolling is introduced forming a
central shear zone between the forward and backward slip zones in the
deformation zone thus lowering the rolling load. A numerical analysis of
the cross shear rolling process is carried out based on the slab method
adopting Wanheim and Bay's general friction model. The pressure
distribution along the contact arc in the roll gap, the position and the
size of the shear zone and the rolling load are calculated. Experimental
results are presented verifying the calculations. The numerical analysis
facilitates a better understanding of the mechanics in cross shear plate
rolling.
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|
Experimental and finite element analysis of capabilities and limits of a combined pneumatic and mechanical deep drawing process
|
|
M. Kleiner, A. Gartzke, R. Kolleck / E. Von Finckenstein (1)
|
|
STC F, 46/1/1997, P.201
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|
Keywords: deep drawing, pneumatic forming, process analysis |
Abstract : In the last ten years various forming processes with working medium -
like hydraulic counter-pressure deep drawing (also known as
hydromechanical deep drawing) or hydroforming - are more and more used
for different applications especially in the automotive industry.
Recently another process was proposed: the so-called pneumomechanical
deep drawing combines a preforming, which uses a gaseous working medium
like air, carbon dioxide or nitrogen, with a deep drawing in the same,
specially designed tool system. The paper presents research work on
process and tools as well as on their application to sheet metal
forming. Process capabilities and limits are analysed through forming
experiments, strain measurements based on an optical system and through
corresponding finite element calculations.
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|
Pulsating blankholder forces in the deep draw processes
|
|
K. Siegert (2), M. Ziegler
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|
STC F, 46/1/1997, P.205
|
|
Keywords: deep drawing |
Abstract : In this paper the effects of pulsating blankholder forces in deep draw
processes for sheet metal parts are discussed. Areas with and without
tangential compressive stresses in draw part flanges, which are located
between the binders, are discussed separately. Areas without tangential
compressive stresses can be simulated by a special friction strip-draw
test using a pulsating normal force ( representing the blankholder force
). Investigations using this equipment show that by pulsating
blankholder forces it is possible to avoid galling and to reduce the
friction force. Areas with tangential compressive stresses can be
simulated by deep drawing axisymmetric cups using a pulsating
blankholder force. Investigations with this equipment show that without
increasing the danger of wrinkling the friction forces can be reduced by
pulsating blankholder forces. This enlarges the gap between the
wrinkling- and the fracture-border for the blankholder force over the
stroke.
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|
Precision forging of spline by flashless die forging with axially driven die
|
|
K. Osakada (1), X. Wang, S. Hanami
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|
STC F, 46/1/1997, P.209
|
|
Keywords: cold forging, spline, forming pressure |
Abstract : In cold forging, a high, forming pressure is required to fill the billet
material into the corners of the die cavity due to the high flow stress
of the steels. To reduce the forming pressure, a method employing an
axially driven die is proposed. In this method, the die is moved in the
axial direction while the billet material is squeezed by the punch. The
corners cf the die cavity are filled easily by the help of the
frictional force over the billet-die interface. The effectiveness of
this method for precision forging of a spline is examined by model
experiments. The results show that the forming pressure is significantly
reduced compared with the conventional closed die forging or the
floating die method.
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|
Optimized kinematics of mechanical presses with non-circular gears
|
|
E. Doege (1), M. Hindersmann
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|
STC F, 46/1/1997, P.213
|
|
Keywords: press, gear, kinematics |
Abstract : The quality of parts manufactured using metal forming operations depends
to a large degree on the kinematics of the press ram. Non-circular
gears with a rotational-angle-dependent speed ratio in the press drive
mechanism offer a new way to obtain those stroke-time behaviours we aim
at as an optimum for the various metal forming operations in terms of
manufacturing. The paper explains the principle using a prototype press
which was built by the Institute for Metal Forming and Metal Forming
Machine Tools at Hanover University. It will present the kinematics as
well as the forces and torques that occur in the prototype. Furthermore,
the paper demonstrates using one example of deep drawing and one of
forging that the press drive mechanism with non-circular gears may be
used advantageously for virtually all metal forming operations.
|
STC G |
|
Improving workpiece roundness through centerless grinding cycle planning
|
|
S.S. Zhou, G.C. Petrosky / R. Lindsay (1)
|
|
STC G, 46/1/1997, P.217
|
|
Keywords: centerless grinding, process simulation, cycle optimization |
Abstract : In centerless grinding, achievable workpiece roundness is directly
related to the cycle length selected for the grinding process. This
paper proposes a systematic approach to minimize workpiece roundness
error by optimizing the cycle length. In the paper, the transient
characteristics of the rounding process is first investigated. It was
found that minimum workpiece roundness error can be obtained when the
initial roundness error is effectively suppressed but the lobing pattern
is not yet fully developed on the workpiece surface. Then, a computer
simulation method is introduced to optimize the grinding cycle length in
terms of minimum workpiece roundness error for both plunge and
through-feed centerless grinding processes. The concept of an average
growth rate is introduced to assess the lobing stability in through-feed
centerless grinding.
|
|
Grinding at very low speeds
|
|
E. Brinksmeier (2), C. Schneider
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|
STC G, 46/1/1997, P.223
|
|
Keywords: gear finishing, grinding process, modelling |
Abstract : In recent years a new method for hard gear finishing that produces a
favourable surface texture and possibly allows gear correction was
introduced. Material removal by the shave-grinding or gear honing
process is the result of a rolling and sliding movement between the
geared workpiece surface and the abrasive grits bonded in a resin,
vitrified or metal tool matrix, shaped similar to an internal gear
wheel. A laboratory set-up based on a grinding process with speeds
between 0.3 m/s and 3 mls was designed in order to investigate
fundamental process behaviour and to compare the knowledge gained with
conventional grinding processes. Moreover recommendations for
improvement of the shave-grinding process could be derived.
|
|
Heat flux distribution and energy partition in creep-feed grinding
|
|
N.K. Kim, C. Guo, S. Malkin (1)
|
|
STC G, 46/1/1997, P.227
|
|
Keywords: grinding, temperature, energy partition |
Abstract : This paper is concerned with the heat flux distribution and energy
partition to the workpiece for creep-feed grinding. From measurements of
transient grinding temperatures in the workpiece sub-surface using an
embedded thermocouple, the overall energy partition was estimated from
moving heat source theory as e ? 3.0%37; for down grinding and e ^? 4.5%37;
for up grinding. An inverse heat transfer analysis was subsequently
applied to calculate the heat flux and cooling distributions on the
workpiece surface from the measured temperatures. Energy partition
values from the inverse analysis were consistent with the results from
moving heat source theory. The higher energy partition for up grinding
may be attributed to thermal incompatibility at the grinding zone.
Creep-feed down grinding should provide a more favorable thermal
situation than up grinding.
|
|
An intelligent multi-agent approach for selection of grinding conditions
|
|
W.B. Rowe (1), Y. Li, X. Chen, B. Mills
|
|
STC G, 46/1/1997, P.233
|
|
Keywords: grinding, artificial intelligence, selection |
Abstract : The advantages of a multi-agent approach are presented for the selection
of grinding conditions. The agents consist of case based reasoning,
neural network reasoning and rule based reasoning. Case based reasoning
is employed as the main problem-solving agent to select combinations of
the grinding wheel and values of control parameters. Rule based
reasoning is employed where relevant data are not available in the case
base. A neural network is employed to select a grinding wheel if
required. The operator makes the final decision about the wheel or the
values of control parameters. The multi-agent approach combines the
strengths of the different agents employed, to generate hybrid solutions
and overcomes the limitations of any single approach. A blackboard
method was used as the means of integrating the multi-agent system. The
system works as expected and demonstrates the potential of using
artificial intelligence for selection of grinding conditions, as well
as the capability to develop a powerful database by learning from
experience.
|
|
The use of an efficient and intuitive tool for the dynamic modelling of grinding processes
|
|
J. Vinolas, J. Biera, J. Nieto, J.I. Llorente / J. Vigneau (1)
|
|
STC G, 46/1/1997, P.239
|
|
Keywords: modelling, grinding, chatter |
Abstract : This paper presents, step-by-step, the capabilities that a
general-purpose simulation environment, such as Simulink/Matlab,
provides for an intuitive and efficient modelling of grinding processes.
Starting from a revision of the different approaches which can be found
in the technical literature the paper begins with the well-known
block-diagram first presented by Snoeys. Next, the paper shows how this
block-diagram is incorporated into the Simulink environment and how the
different parameters for the simulation are introduced in the model
(machine, grinding wheel and process parameters). Special attention is
paid to the fact that nonlinear phenomena can easily be included.
|
|
Model based AE-monitoring of the grinding process
|
|
W. Hundt, F. Kuster, F. Rehsteiner (1)
|
|
STC G, 46/1/1997, P.243
|
|
Keywords: grinding, monitoring, model |
Abstract : A kinematic model of single edge cutting action in grinding has been
developed. The model describes the force pulse created by chip formation
at the cutting edge. This pulse is assumed to excite acoustic emission
(AE) signals. The typical values of its features (risetime, width,
amplitude) determine the requirements for the measurement equipment. AE
was measured on the workpiece during grinding and was analysed in the
frequency range between 70 kHz and 3.5 MHz. A suitable signal analysis
strategy was developed to extract meaningful information from the AE
signal using frequency domain feature extraction. The comparison of
model and measurement output allows the identification of model
parameters. The parameter values give a description of the grinding
wheel state and the process state.
|
|
High-precision surface grinding of ceramics with superfine grain diamond cup wheels
|
|
T. Matsuo (1), M. Touge, H. Yamada.
|
|
STC G, 46/1/1997, P.249
|
|
Keywords: grinding, ceramic, ductile transition |
Abstract : High-precision surface grinding has been performed on the Si_3 N_4 , and
AI_2 C_3 -TiC ceramics and Mn-Zn Ferrite using an ultra-precision
surface grinder and very fine grain diamond cup wheels, where the
maximum depth of cut was 2 µm and the maximum through feed rate being
100 mm/min. The surface roughness and percent brittle mode area were
measured using an atomic force microscopy (AFM). These characteristics
were discussed by a parameter "Smax" defined as Smax = µ a /v,/ v_s (µ :
/successive cutting edge spacing, a : depth of cut, v, : through feed
rate, v, : wheel speed). With decreasing grain size from #1200 to
#16000, the surface roughness Rmax decreases to 20 to 30 nm. Similarly,
a remarkable reduction in percent brittle mode area is seen by changing
grain size. The effect of dressing stone on the ground surface was also
investigated using 3D wheel surface topography.
|
|
Surface roughness generation mechanism of ultraprecision grinding of optical materials with a cup-typed resinoid-bonded diamond wheel
|
|
Y. Namba, M. Shiokawa, J. Yu / N. Ikawa (1)
|
|
STC G, 46/1/1997, P.253
|
|
Keywords: grinding, roughness, surface |
Abstract : Super-smooth optical glass surfaces have been obtained by grinding using
an ultraprecision surface grinder and a cup-type resinoid-bonded diamond
wheel without any polishing. This paper deals with some mechanisms of
surface roughness generation for brittle materials in ductile mode
grinding. The shape of the contact area between a cup-type diamond wheel
and sample in ultraprecision grinding has been measured with an optical
profiler. The shape is affected by the grain size of the diamond powder,
feed rate, and grinding time. Surface roughness can be estimated by a
simple surface generation model where the inner edge angles of the wheel
and feed rate determine the surface roughness in the ductile mode. The
inner edge angles are affected by various grinding conditions.
|
|
Forces and specific energy in superfinishing of hardened steel
|
|
S.H. Chang, S. Balasubrahanya, S.Chandrasekar, T.N. Farris, F. Hashimoto / M.C. Shaw (1)
|
|
STC G, 46/1/1997, P.257
|
|
Keywords: superfinishing, force measurement, hardened steel |
Abstract : A piezoelectric force transducer has been adapted and used to measure
the forces acting on the abrasive stone during superfinishing of
hardened steels. The sensor has a sufficiently high natural frequency
and resolution to measure both the average and oscillatory forces to
within 10 milli-Newton. By combining measurements of forces and material
removal rates, specific energy and force ratio have been estimated.
Several characteristics of the superfinishing process are shown to be
well reflected in the force signature, and these are highlighted and
explained in fundamental terms. The force transducer is shown to offer
many possibilities for studying the mechanics of superfinishing in
considerable detail.
|
|
Utilization of electrolyzing non-linearity in precision grinding with ELID (Electrolytic in-process dressing) for fabrication of hard material components
|
|
H. Ohmori, T. Nakagawa (1)
|
|
STC G, 46/1/1997, P.261
|
|
Keywords: grinding performance, in-process dressing, electrode oxidation |
Abstract : Investigations were conducted on metallic wheel bond oxidation as the
anode in ELID and non-linearity conditions to study electrolytic
dressing characteristics and ELID-grinding performances by combining the
three elements: 1)metallic wheel bond, 2)power supply, and 3)grinding
fluid. The possibility of controlling non-linearity conditions when
these three elements are combined was demonstrated. and each selected
combination showed optimum performances in terms of efficiency,
stability, accuracy, and grinding ratio. ELID was also successfully
applied to coarse grit wheels. Several attempts to apply ELID rough
grinding for the efficient and precision fabrication of structural
components of hard materials such as ceramics and hard metals were also
carried out.
|
STC M |
|
A force controlled clamping element for intelligent fixturing
|
|
M.A. Mannan (2), J.P. Sollie
|
|
STC M, 46/1/1997, P.265
|
|
Keywords: force control, intelligent clamping, workpiece deformation |
Abstract : This paper deals with the design of a force-controlled clamping element
to be applied for intelligent fixturing with the aim to minimise
workpiece deformation and distortion under a machining operation. An
electro-mechanically controlled clamp is designed, fabricated and
tested. Test results have shown that the designed, system is capable of
controlling clamping force with an accuracy of +/- 1 N over the full
range of 700 N with rather fast response time of 200 msec.
|
|
An open-architecture CNC CAD-CAM machining system with data-base sharing and mutual information feedback
|
|
M. Mitsuishi, T. Nagao (1), H. Okabe, M. Hashiguchi, K.Tanaka
|
|
STC M, 46/1/1997, P.269
|
|
Keywords: chatter, learning control, integrated computer aided manufacturing |
Abstract : The authors have developed a highly efficient machining system which
maintains a stable machining state through the use of multi-axis force
information. The system has capabilities for cutting state monitoring,
adaptive control and learning. This paper presents the following items
based on our previous discussions: (a) implementation of machine tools
with open-architecture CNCs, (b) efficient stability lobe acquisition
methods as a practical data-base, and (c) data-base sharing methods
among different machine tools. Experimental results showed the
effectiveness of the proposed methods.
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utonomously proficient CNC controller for high performance machine tools based on an open architecture concept
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K. Yamazaki (2), Y. Hanaki, M. Mori, K. Tezuka
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STC M, 46/1/1997, P.275
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Keywords: intelligent CNC, open CNC, automatic machining |
Abstract : The paper deals with the new controller for the high performance CNC
machine tools. The controller proposed is referred to as "TRUE-CNC."
"TRUE" means Transparent, Transportable and Transplantable, Revivable,
User-reconfigurable, and Evolving. TRUE-CNC allows the operator to
achieve the maximum productivity and highest possible quality of the
machined parts in a given environment with autonomous capturing of the
machining operation proficiency. The TRUE-CNC controller provides
intelligent functions for less-skilled operator to run the high
performance machine tools as if a skilled operator does. The concept and
design aspects of the system architecture and the algorithms for
functions developed for the TRUECNC are described in the paper.
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Intelligent strategy of force and position parallel control for a robot
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Y.H. Yin, J.Y. Zhu (1), Z.X. Wei
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STC M, 46/1/1997, P.279
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Keywords: robotics, intelligent force control, fuzzy neural network |
Abstract : In the paper, an intelligent strategy of force and position parallel
control is firstly and systematically presented based on intelligent
theories such as large scale system, fuzzy theory and neural networks.
The force control hierarchical system is built. Under the consideration
of friction, the dynamic tangent and normal equations are determined.
Fuzzy hierarchical coordination and neural parallel control are
implemented. Some experimental research has been carried out on an Adept
Three robot manipulator. The results prove that the intelligent strategy
is effective and feasible.
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Thermal behavior of industrial robots and possibilities for error compensation
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U. Heisel (2), F. Richter, K.H. Wurst
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STC M, 46/1/1997, P.283
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Keywords: industrial robot, thermal displacement, compensation method |
Abstract : The fundamental differences between the kinematics of SCARA-, six-axes-
and portal robots as well as tripod and hexapod machines are also
reflected in their varying thermal behaviour. This paper describes the
sequential investigation of the thermal behaviour of industrial robots
with a standardized experimental setup It includes a comparison of the
results for the different robot types as well as conclusions regarding
improvement possibilities in robot design. There are also suggestions
for the compensation of errors due to thermal effects and for a
correction of the spatial position of the tool center point (TCP).
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Volumetric error analysis of a stewart platform based machine tool
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A.J. Patel, K.F. Ehmann (2)
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STC M, 46/1/1997, P.287
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Keywords: error analysis, accuracy analysis, error sensitivity |
Abstract : Striving for greater accuracy, some machine tool manufacturers are
developing parallel structures for the next generation machine tool.
Therefore, tools are needed to analyze the effect error sources have on
this type of structure. A model of a Stewart Platform based machine tool
is developed that provides the framework for inclusion of all relevant
error sources. An error analysis is presented based on an error model
formed through differentiation of the kinematic equations, and a
sensitivity analysis is given as a design tool for tolerance allocation
during manufacture. Finally, automated error analysis software is
demonstrated that graphically depicts position and orientation errors
along tool paths and throughout the workspace.
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Systematic design of hexapods and other parallel link systems
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G. Pritschow (1), K.-H. Wurst
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STC M, 46/1/1997, P.291
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Keywords: machines, design, hexapod |
Abstract : During the last 30 years, a variety of different parallel kinematic
links which are based on the known Stewart platform have been proposed
and which are all inventive ideas. All existing machines. however. share
the common characteristic that motion is generated either by length
modification, positioning of the base points or by a combination of
both. This contribution describes a systematic procedure for the design
of parallel kinematic link mechanisms which comprises a great variety of
possibilities.
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Design and kinematics of a parallel manipulator for manufacturing
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Q.Y. Wang, H. Zou, M.Y. Zhao, Q.M. Li / H.W. Zheng (1)
|
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STC M, 46/1/1997, P.297
|
|
Keywords: parallel manipulator, mechanism design, kinematics analysis |
Abstract : This paper presents a new model of parallel manipulator for
manufacturing, whose mechanism comes from the general Stewart platform
which has the advantages of high rigidity and high load capacity. A
scheme of the link mechanism is also proposed to make the link structure
very simple. The mechanism parameters are optimized by workspace
analysis of the parallel mechanism. With the view of kinematics
equivalence between parallel mechanism and serial mechanism, /by way /of
hypothesis serial mechanism and branch hypothesis serial mechanism, an
efficient kinematics algorithm has been developed. The problem, derived
motion produced by the link structure, has also been solved conveniently.
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Rigid XY theta table for ultraprecision machine tool driven by means of walking drive
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E. Shamoto, T. Moriwaki (1)
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STC M, 46/1/1997, P.301
|
|
Keywords: feed table, ultraprecision machine tool, piezoelectric actuator |
Abstract : The present paper presents a new method to feed an XY table for ultraprecision machine tools by utilizing piezoelectric actuators, which is based on principle of Walking Drive. The table supported and driven by six pairs of the feed and support actuators. The device does not require any conventional guide methods, and the rigidity is high especially in the feed direction. A control algorithm is also proposed in the present research so that the feed velocity and direction can be controlled in real time. The simple control algorithm automatically generates the complicated voltage patterns to be applied to the actuators to generate any given motion. The present feed method for the XY table is expected to have various advantages for ultraprecision machine tools such as high positioning resolution, high rigidity, smooth motion and long stroke.
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Application of electrorheological fluid dampers to machine tool elements
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T. Aoyama, I. Inasaki (1)
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STC M, 46/1/1997, P.309
|
|
Keywords: bearing, damping, improvement |
Abstract : Electrorheological fluids (ERF) are colloidal suspension whose apparent
viscosity is variable in response to the strength of an electric field.
In this paper, the application of electrorheological fluids to machine
tool elements is proposed. The dynamic characteristics of machine tool
table systems with linear motion rolling element bearings are improved
by using an ERF film damper. A high damping force can be induced by
increasing the ERF viscosity when the table is being moved during
machining and the viscosity can be reduced when the table is being moved
rapidly so providing less viscous drag. The performance of the
hydrostatic bearing can be controlled by using ERF instead of hydraulic
oil. The bearing clearance and load carrying capacity can be controlled
by adjusting the intensity of the applied electric field.
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Construction of an integrated manufacturing system for 3-D micro structure - concept, design and realization -
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Y. Hatamura (2), M. Nakao, T. Sato
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STC M, 46/1/1997, P.313
|
|
Keywords: micro-manufacturing, micro-assembling, integrated system |
Abstract : An integrated manufacturing system for 3D microstructures was
conceptualized, designed, and actually built. The system realized 3D
shaping using a fast atom beam etching under rotation of workpieces, and
3D assembly using a concentric manipulator under observation of a
multi-view scanning electron microscope. Through its demonstration of
3D micro manufacturing, it was clarified : Knowledge about conventional
machine manufacturing is useful even in micro-manufacturing : The
knowledge could be applied under new functions of zero reaction force 3D
shaping, constant monitoring and on-one-table operating : An image
based control proved effective for the integrated micro-manufacturing
systems.
|
|
Development of a high-performance deep-hole laser-guided tboring tool - guiding charasteristics -
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A. Katsuki, H. Onikura, T. Sajima, M. Rikimaru / H. Kudo (1)
|
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STC M, 46/1/1997, P.319
|
|
Keywords: boring, laser, adaptive control |
Abstract : A laser- guided BTA tool using piezoelectric actuators was developed to
prevent hole deviation. Three kinds of experiments were conducted to
examine the performance of this tool using a duralumin workpiece with a
prebored hole. The first experiment was performed to examine the
conditions of the hole deviation in normal deep hole boring. The second
was to examine whether the tool could go straight through without
shifting toward a thin wall on one side of the workpiece. The third was
to examine whether the tool could go straight through without advancing
along an obliquely prebored hole. The results showed that the tool could
be guided to go straight through despite the disturbances.
|
|
Milling simulation for process optimization in the field of die and mold manufacturing
|
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K. Weinert (2), A. Enselmann, J. Friedhoff
|
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STC M, 46/1/1997, P.325
|
|
Keywords: process optimisation, milling simolation, sculptured surfaces |
Abstract : When milling sculptured surfaces the major problems are the limited
precision due to milling-cutter deflections caused by the cutting force
and a unsatisfactory process reliability. One method for improving
surface quality while maintaining high process reliability is the
computer-based engagement analysis and feed-rate adaptation. The aim of
the feed-rate adaptation is to avoid intolerably high tool loads as they
occur while semi-finishing sculptured surfaces. The method developed
uses an efficient, volume model to simulate the cutting process. The
calculation of the optimal feed-rate takes the main technological
aspects of 3-axis milling into account. The efficiency of the approach
developed is demonstrated with a practical example.
|
|
Manufacturing on demand in production networks
|
|
E. Westkämper (1)
|
|
STC M, 46/1/1997, P.329
|
|
Keywords: flexibility, manufacturing requirements planning (MRP), fractals |
Abstract : In order to increase their competitiveness, companies optimize their
production by outsourcing and integration of the most efficient
suppliers. On the other hand, they try to fulfil specific requirements
by extreme customer orientation and manufacturing on demand. This leads
to new organizational procedures and manufacturing systems. Their
characteristics are: autonomous manufacturing cells, fractal units,
adaptive systems, dynamic and agile management, self-optimization and
self-control, customer-specific order management, communication
networks. Particularly "manufacturing on demand" and the order
management in production networks require new methods. This paper deals
with the management of networks with virtual elements and a new method
for MRP which is based on the principles of dynamic integration between
fractal units in production networks (agents) and includes learning
methods for time and cost improvement.
|
STC O |
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Virtual manufacturing systems as advanced information infrastructure for integrating manufacturing resources and activities
|
|
K. Iwata (1), M. Onosato, K. Teramoto, S. Osaki
|
|
STC O, 46/1/1997, P.335
|
|
Keywords: visual, manufacturing, system, information, technology, integration |
Abstract : Advanced information technology such as computer networking and 3D
graphics is now forcing industrial companies to change their
manufacturing systems to information-oriented ones. The authors propose
an new approach to an advanced information infrastructure with
manufacturing semantics by using virtual manufacturing systems. Virtual
manufacturing systems have much potential to integrate manufacturing
resources and activities distributed in computer networks. The paper
also describes how virtual manufacturing systems will be applied to
applications as the informational kernel with open architecture in
advanced manufacturing systems.
|
|
The project management process in manufacturing systems engineering
|
|
U. Ekmark, J. Nelson/ / N. Martensson (1)
|
|
STC O, 46/1/1997, P.339
|
|
Keywords: system, engineering, management |
Abstract : Manufacturing systems engineering is characterized by increased
technological complexity, requiring co-operation by many different
experts. The management of this process is often carried out in an ad
hoc manner, However, co-ordination is very important, and has a major
influence on lead-time as well as quality of the resulting manufacturing
system. This paper argues for conscious and a continuous improvement of
the corporate knowledge and ability for managing multidisciplinary teams
of specialists. Based on studies of a number of engineering projects a
methodology is proposed, integrating management models and methods with
those used within manufacturing systems engineering.
|
|
Modelling of biological manufacturing systems for dynamic reconfiguration
|
|
K. Ueda (2), J. Vaario, K.H. Ohkura
|
|
STC O, 46/1/1997, P.343
|
|
Keywords: manufacturing systems, dynamic environment, genetic information |
Abstract : The concept of Biological Manufacturing Systems (BMS) aims at dealing
with dynamic changes in external and internal environments in product
life cycle from planning to disposal, based on biologically-inspired
ideas such as self-growth, self-organization, adaptation and evolution.
This paper describes modelling of BMS at a floor level and focuses on
system reconfiguration. Computer simulation using the principle of
self-organization shows that the proposed BMS model indicates adaptive
behavior to the changes in products demands due to external environment
and malfunction of manufacturing cells as an internal environment, and
it provides the possibility of dynamic reconfiguration of manufacturing
systems.
|
|
Virtual manufacturing system : a test-bed of engineering activities
|
|
K.I. Lee (2), S.D. Noh
|
|
STC O, 46/1/1997, P.347
|
|
Keywords: virtual, manufacturing, engineering, planning and control |
Abstract : Virtual manufacturing system is an integrated computer based model which
represents the physical and logical schema and the behavior of real
manufacturing systems. In this paper, a prototype of a Virtual
Manufacturing system is developed using an expert system shell and a
database management system on Internet, and various manufacturing
strategies are examined by it. Workflow modeling of a Virtual
Manufacturing system is performed, and a manufacturing/product database
is constructed. Also, Virtual factory and its functions for engineering
activities including order processing, design, planning, scheduling,
control and verification are implemented and integrated. Finally, real
time scheduling using the multi-pass strategy, on-line process planning
and production control system are applied. The experiences of this
integration are satisfactory to propose the Virtual Manufacturing system
as a good test-bed for diverse engineering activities in manufacturing.
|
|
Life-cycle-modelling as an instrument for life-cycle-engineering
|
|
R. Züst (2), G. Caduff / B. Schumacher (1)
|
|
STC O, 46/1/1997, P.351
|
|
Keywords: modelling, environmental impact, optimization |
Abstract : Environmental impact is largely determined in the planning and
development phases of a company's activities, products and services.
This "planned" impact becomes visible later in the manufacture, use and
disposal stages. In order to achieve an effective and efficient
improvement in environmental performance, appropriate measures must thus
be taken during the planning stage. A suitable instrument for early
recognition of ecological and economic effects is, for example,
modelling. In the following, two life cycle phases, both modelled during
the course of research projects, are discussed.
|
|
An analytical method for integrating environmental & traditional design considerations
|
|
P. Jackson, D. Wallace / R. Kegg (1)
|
|
STC O, 46/1/1997, P.355
|
|
Keywords: integrated product design, environment, modelling |
Abstract : Designing products for reduced environmental impact and improved
performance requires that a diverse range of characteristics be
considered. Such tradeoffs require a practicable method for combining
specialized tools into an integrated analytical system. The paper
describes how an integrated design tool can be constructed from modules
which correspond to different aspects of the problem, such as geometry,
materials and mathematical subproblems. An electronics housing design
example (subject to electromagnetic, heat transfer, environmental and
cost considerations) illustrates the use of the design methodology. The
tool is then used to demonstrate the ability to investigate and
understand interactions between different design goals.
|
|
Distributed simulation applied to production systems
|
|
H. Bley, C.C. Wuttke / W. Massberg (1)
|
|
STC O, 46/1/1997, P.361
|
|
Keywords: production systems, simulation, optimization |
Abstract : To run nowadays production systems in an optimized way complex and time
consuming models are helpful especially if an isolated analysis of
subsystems is not possible. Operating problems like scheduling and
resource requirement planning need short processing times while
strategic problems lead to a large number of solutions to be evaluated.
This paper proposes the problems to be solved and a modeling and
simulation architecture that allows the use of distributed computer
resources and databases. The approach of separated modeling and
simulation allows a better performance. By a distinct example it is
shown how this approach can be used for the optimization of storage
using the eventdriven material flow simulation.
|
|
Agent-based control of self-organized production systems
|
|
H.-P. Wiendahl (1), V. Ahrens
|
|
STC O, 46/1/1997, P.365
|
|
Keywords: production control, scheduling, group technology |
Abstract : The organization of production is getting more complex. This problem is
today being tackled by dividing large systems in small ones and letting
these act autonomously. Their mutual interdepencies, however, remain.
This is why planning and controlling manufacturing systems will in the
future be a matter of getting autonomous subsystems to co-operate
voluntarily. We will suggest market rules. One approach used to this end
is the agent theory. It is suitable as a modelling and simulation tool
for research aims and as a basis for the construction of software tools
which are able to support distributed manufacturing processes.
|
|
combined multicriteria approach for cellular manufacturing layout
|
|
M.H. Elwany, A.B. Khairy (2), M.G. Abou-Ali, N.A. Harraz
|
|
STC O, 46/1/1997, P.369
|
|
Keywords: layout, cellular, decision making |
Abstract : In cellular manufacturing, the inter-cell layout phase is frequently
affected by multiple qualitative and/or quantitative criteria. This
paper presents a computer system developed to handle the two aspects
individually or collectively. The system operates in tandem mode,
combining a knowledge base with an improvement algorithm. The knowledge
base generates a layout based on a set of rules, this layout is seeded
optionally to an improvement Simulated Annealing global optimization
algorithm to find a better configuration for the situation. The
verification process is carried out by consulting the system a
reasonable number of times using different boundary conditions. Results
from consultations are included to illustrate the system's performance
and capabilities.
|
|
A collaborative control system for mass customization manufacturing
|
|
M.M. Tseng, M. Lei, C.J. Su / M.E. Merchant (1)
|
|
STC O, 46/1/1997, P.373
|
|
Keywords: agile, co-operative scheduling, flexible manufacturing |
Abstract : Mass Customization aims at producing customized products to meet
individual customer's needs with mass production efficiency. The advent
of this /new /mode of manufacturing introduces a different set of
requirements on system control for manufacturing operations. The
implications include the drastic increase of varieties, very small batch
size, random arrival of orders, and wide spread of due dates. In
addition, there are also factors such as similarity among tools,
production plans and product designs. If properly utilized, that can
help to reduce the complexities of the control systems. In order to
develop a new type of control and coordination system to support mass
customization, a heterogeneous coordination mechanism is developed. A
price mechanism with the construct of intelligent agents in a
market-like environment is investigated to fulfill the requirements.
|
|
A human factors framework for analysis of an assembly work
|
|
A. Kjellberg (2), L. Moestam
|
|
STC O, 46/1/1997, P.377
|
|
Keywords: human factors, learning, assembling |
Abstract : Manual assembly work can be classified in terms of degrees of freedom.
In car manufacturing "bounded work" means work at the moving assembly
line. "Free work" is arranged in separate work stations for teams
working with functional modules. The human factor characteristics of the
different work types can be described by a three factor framework:
Activation, Predictability and Freedom of Action. These three key
factors are based on well-established and heavily researched theories.
By analysing each, and their interdependence, with the different job
assignments we have got a new qualitative description based on
quantitative data. These data can be used for the balancing of
process-oriented work rotation. work enlargement and work enrichment.
With the use of this methodology a design of work tasks can be made that
is both good for the individual worker and results in maximum
utilisation of the total resources.
|
|
Development of the new human-conscious automobile assembly plant
|
|
A. Niimi, T. Sata (1), K. Shiramizu, T. Matsuura, N. Hisada
|
|
STC O, 46/1/1997, P.381
|
|
Keywords: assembling, load, man-machine system |
Abstract : We developed an automobile assembly plant that places greater
consideration on human beings. In order to achieve this, we reorganized
work assignments based on vehicle function. Next, we improved worker
satisfaction by enhancing the self-governing nature of work groups. Work
loads were reduced by developing a method for quantifying physiological
workloads of assembly jobs. Whenever automated equipment was introduced,
we installed machines that work as team members with workers. Finally,
we implemented various improvements in the overall work environment. As
a result, we successfully designed a human-conscious plant with
substantial improvements in productivity and quality.
|
|
Case based evaluation of potential deterioration for facility life-cycle management
|
|
S. Takata (2), H. Shiono, H. Hiraoka, H. Asama
|
|
STC O, 46/1/1997, P.385
|
|
Keywords: maintenance, deterioration, expert system |
Abstract : Providing appropriate maintenance is essential to achieve effective
production. For planning proper maintenance strategy, it is necessary to
know potential deterioration of the facility which may lead to various
problems. In this paper, we propose a case based approach to the
evaluation of potential deterioration modes. Deterioration cases are
represented in terms of the deterioration process in which basic
deterioration mechanisms are combined. Algorithm for the qualitative
evaluation of deterioration of the specified part of the facility is
proposed. Propagation of effects of deterioration to other parts of the
facility is also discussed. Effectiveness of the method is demonstrated
using an experimental system.
|
|
A decision support system for ship maintenance capacity planning
|
|
R.J. de Boer, W.H.M. Zijm (2)
|
|
STC O, 46/1/1997, P.391
|
|
Keywords: maintenance, computer aided planning, scheduling |
Abstract : In this paper. the basic framework and algorithms of a decision support
system are discussed, which enhance process and capacity planning at a
large repair shop. The research is strongly motivated by experiences in
a project carried out at a dockyard, which performs repair, overhaul and
modification programs for various classes of navy ships. We outline the
basic requirements placed upon order acceptance, process planning and
capacity scheduling for large maintenance projects. In subsequent
sections a number of procedures and algorithms to deal with these
requirements, in particular a procedure for workload-based capacity
planning, a database system to support process planning are developed,
as well as a resource-constrained project scheduling system to support
work planning at a more detailed level. The system has been designed to
support decision making at the Navy Dockyard in particular, however, we
believe that, due to its generic structure, it is applicable to a wide
range of project-based manufacturing and maintenance environments.
|
|
Near optimal scheduling of manufacturing systems with presence of batch machines, setup requirements
|
|
P.B. Luh, J.H. Wang, J.L. Wang, R.N. Tomastik, T.D. Howes (1)
|
|
STC O, 46/1/1997, P.397
|
|
Keywords: scheduling, batch processing, setup requirement |
Abstract : Scheduling is a key factor for manufacturing productivity. Effective
scheduling can improve on-time delivery, reduce inventory, cut lead
time, and improve machine utilization. This study was motivated by the
design and implementation of a scheduling system for a helicopter part
production cell. The manufacturing is characterized by the presence of
batch machines that can process multiple parts simultaneously, and the
presence of machines requiring significant setup times. A novel
mathematical optimization model with a separable structure is presented,
and a solution methodology based on a combination of Lagrangian
relaxation, dynamic programming, and heuristics is developed. Numerical
results demonstrate that the method can generate near optimal schedules
with quantifiable quality within a reasonable amount of computation time
on a personal computer.
|
|
Reuse of control software for manufacturing systems
|
|
J.I. Llorente, M.I. Sarachaga, A. Burgos, J. Vinolas / R. Bueno (1)
|
|
STC O, 46/1/1997, P.403
|
|
Keywords: manufacturing system, software, control |
Abstract : The paper here presented focuses on the application of software reuse to
the development of manufacturing system control. It puts forward a
methodology which includes the precise tools for the development,
implementation and maintenance of such a kind of software. This
methodology is the result of previous experiences and it combines two
complementary methodologies: Synthesis and Reboot. The former places
emphasis on the domain engineering, and the latter complements it thanks
to its bottom-up approach to reuse, and the metrics for the software
components. A practical implementation is also described, in which other
software engineering concepts have been applied.
|
|
Interactive programmable feature recognisor
|
|
P. Gibson, H.S. Ismail, M. Sabin, K.K.B. Hon (2)
|
|
STC O, 46/1/1997, P.407
|
|
Keywords: feature, recognition, object-oriented programming |
Abstract : This paper describes the structure and operation of a prototype feature
recognition system programmed in the 'C++' language providing the user
with the means of describing the required features interactively. The
system was developed for use as both a Windows and a UNIX based
application using a derivative of EXPRESS as the feature description
language. At present the system can accept entity descriptions from CAD
systems in the form of DXF files through a DXF translator. The paper
provides a brief review of the current research in feature recognition
and discusses the implementation of a set of methods for optimising the
recognition process.
|
|
A method for tooling configuration in integrated manufacturing systems
|
|
T. Tolio, B. Colosimo, Q. Semeraro / F. Jovane (1)
|
|
STC O, 46/1/1997, P.411
|
|
Keywords: integrated, manufacturing, system, tooling, design, modelling |
Abstract : Tooling configuration deeply affects the performance of Integrated
Manufacturing Systems both in terms of flexibility and productivity. The
literature on tooling configuration is extremely scarce and due to the
lack of formal methods oversizing is a common practice which leads to
high investments in tools.
The paper presents a method for tooling configuration that is aimed at
tool investment minimization under the constraint of a given system
productivity. The method is applicable to real case situation involving
hundreds of different tool types. The paper reports on the performance
of the method under a set of cases based on a real system.
|
|
Integration of operator's experience into NC-manufacturing
|
|
H. Schulz (1), D. Spath (2)
|
|
STC O, 46/1/1997, P.415
|
|
Keywords: computer aided manufacturing (CAM), computer numerical control (CNC), manufacturing feature |
Abstract : The existing program interface of numeric controls according to ISO 6983
(DIN 66025) has serious lacks regarding information volume and content,
transparency and data exchange. Therefore, program adaptation can hardly
be carried out down at the shop floor. Consequently, the manufacturing
experience of the operator cannot be used. In order to solve this
problem, a new manufacturing-feature-oriented method of description for
drilling and milling processes has been developed. The machining job is
described by manufacturing features, which represent the material volume
that has to be removed. Each manufacturing feature is assigned to
manufacturing steps, that contain necessary manufacturing parameters,
e.g. way of method, tools, strategy and cutting parameters.
|
|
A verification program for 5-axis NC machining with general APT tools
|
|
M.C. Leu (2), L. Wang, D. Blackmore
|
|
STC O, 46/1/1997, P.419
|
|
Keywords: |
Abstract :
|
|
Evolutionary design of fuzzy-logic controllers for manufacturing systems
|
|
B. Porter, N.N. Zadeh / A. Chisholm (1)
|
|
STC O, 46/1/1997, P.425
|
|
Keywords: automation, fuzzy logic, production control |
Abstract : In industrial automation, fuzzy-logic controllers can be used to
minimise work-in-progress, production surplus, and production backlog.
The methodology presented it this paper for the design of such
controllers for manufacturing systems involves the use of evolution
strategies rather than genet c algorithms. This evolutionary procedure
is illustrated by designing a fuzzy-logic controller for a non-reentrant
manufacturing system incorporating two machines and producing a single
part-type. It is indicated that, in this case, the evolutionary design
procedure is approximately ten times faster than that involved in the
analogous genetic design procedure.
|
|
Determination of optimal parting directions in plastic injection mold design
|
|
A.Y.C. Nee (1), M.W. Fu, J.Y.H. Fuh, K.S. Lee, Y.F. Zhang
|
|
STC O, 46/1/1997, P.429
|
|
Keywords: injection, molding, CAD |
Abstract : Automatic recognition and extraction of undercut features is e
bottleneck in computer-aided injection mold design. The number of
undercuts and their locations affect the parting directions and
surfaces, side-core mechanism, sliders and lifters design, and the
overall structure of a mold. In this paper, a methodology is proposed
for the recognition and extraction of undercuts based on their
geometrical characteristics and topological relationships of the molded
parts. With the developed software, undercuts can be classified and
recognized automatically from a 3-D model of a molded part. In order to
define the undercut criteria clearly, a new classification method is
presented. Since most of the injection molded parts consist of curved
surfaces and free-formed surfaces, recognition and extraction of these
surfaces are also introduced. After all the undercuts are extracted, the
optimal parting direction is chosen based on the proposed criterion of
considering the number of possible undercuts and their corresponding
undercut volumes. From the case studies on several industrial parts, the
methodology developed is found to be efficient in determining the
optimal parting direction of injection molded parts.
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Feedrate optimization of ball end milling considering local shape features
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C.N. Chu (2), S.Y. Kim, B.H. Kim, J.M. Lee (1)
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STC O, 46/1/1997, P.433
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Keywords: code, feature, feed |
Abstract : In ball end milling of free form surfaces, static and dynamic cutting
characteristics change dramatically for different local shape features.
Local shape features are classified as plain, upward ramp, downward
ramp, contour, convex corner and concave corner. Data base for stable
cutting conditions of zinc base alloy was established through various
experiments with different local shape features. Feed rate optimization
program, Opticode, was developed from the relationship between optimal
feed rate and local shape feature. In Opticode, local features are
recognized by comparing NC codes of neighboring points. The developed
program was applied to automobile prototype production dies.
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STC P |
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Twin-probe vibroscanning method for dimensional measurement of microholes
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T. Masuzawa (1), B.J. Kim, C. Bergaud, M. Fujino
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STC P, 46/1/1997, P.437
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Keywords: measurement, dimension, microhole |
Abstract : We present a new twin-probe vibroscanning method for measuring the
inside profile of microholes in electrically nonconductive materials.
Instead of the single cantilever probe used in the conventional
vibroscanning method, a probe with two elements in electrical contact is
used to detect the surface. Following a feasibility test with a
macroscale prototype device, the measurement of microholes was realized
using a silicon-based microprobe.
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A multi-point method for spindle error motion measurement
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G.X. Zhang (1), Y.H. Zhang, S.M. Yang, Z. Li.
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STC P, 46/1/1997, P.441
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Keywords: measurement, spindle error, multi-point method |
Abstract : A multi-point method for spindle error motion measurement is proposed in
the paper. The radial error motion of the spindle is measured by 4
probes, where as the axial and tilt ones by 5 probes. Roundness error
and flatness error of the specimens used for measuring the spindle error
motions are separated and have little effect on the accuracy of spindle
error motion measurement. For assuring high accuracy of measurements
techniques for determining the actual angular positions of the probes
and hardware of measuring system have been also developed. The proposed
method can be used for real-time spindle error motion measurement with
sub-micron accuracy.
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Linear-motor-levitated stage for photolithography
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W.J. Kim, D.L. Trumper / J.B. Bryan (1)
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STC P, 46/1/1997, P.447
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Keywords: mechatronic, precision, actuator |
Abstract : This paper presents a linear-motor-levitated stage with large planar
motion capability. This positioning system is the first capable of
providing all the motions required for photolithography in semiconductor
manufacturing with only a single moving part. The single moving part
generates all six-degree-of-freedom (6-DOF) motions required for
focusing and alignment, and large two-dimensional motions (50 ^ * 50 mm)
for positioning. Four linear permanent-magnet motors produce suspension
forces to support the moving part (5.58 kg) as well as driving forces.
The stage is to have tens-of-nanometer position stability and the design
can be readily scaled to accommodate 12-inch wafers in the next
generation of photolithography. The prototype stage is being levitated
in initial testing.
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Ductile regime cutting of brittle materials using a flying tool under negative pressure
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Y. Kamimura, H. Yamaguchi, Y. Tani (2)
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STC P, 46/1/1997, P.451
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Keywords: precision cutting, ductile transition, brittle materials |
Abstract : The importance of ductile regime cutting has been emphasized in the
production of large-diameter optics and semiconductor substrates over
the last ten years. However the available technology has not yet been
implemented in industry. The reason is that cutting technology based on
the motion-copying principle is too sensitive for error motions of a
machine tool to maintain the actual depth of cut stably below the
critical depth. A new cutting technology using a flying tool under
negative pressure has been developed. In this technology, a flying tool
glides over a workpiece surface while maintaining a small height like a
negative-pressure slider of a magnetic disc drive. Using the tool
system, ductile regime cutting of optical glass and monocrystalline
silicon was examined, and a mirror-surface finish with no cracks was
achieved on a face lathe having a 0.1 p m order of error motion.
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Micromachined thin film mirror array for reflective light modulation
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S.G. Kim (2), K.H. Hwang, Y.J. Choi, Y.K. Min, J.M. Bae
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STC P, 46/1/1997, P.455
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Keywords: micromachining, mirror, piezoelectricity |
Abstract : Actuated Mirror Array (AMA) is a new reflective type light modulator
that uses micromachined thin film piezoelectric actuators in conjunction
with 300.000 micro mirrors of 100 ?m by 100 ?m size. A mirror array
module consists of the active matrix, where the image signal voltages
are applied, and the cantilever beams, which are actuated by the applied
signal voltages, on top of the active matrix. Since the tilting of the
mirror pixel defines the gray scale or the light beam on the screen, the
300.000 mirror pixels should have initial positions as uniform as
possible. A novel support anchor design for the micromachined cantilever
beams is developed to provide uniform initial deflection of the
cantilever. By implementing a secondary support to the anchor of the
cantilever beam, the initial deflection can be reduced to 35%37;.
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Stitching interferometry for the measurement of aspheric surfaces
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Y.J. Fan, K.G. Struik, P.C. Mulders (2), C.H.F. Velzel
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STC P, 46/1/1997, P.459
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Keywords: interferometry, aspheric optical surface, measurement |
Abstract : In this paper, we describe the progress being made in the development of
stitching interferometry for measuring curved surfaces with large
aspheric departures. Stitching interferometry is an extension of
conventional interferometry by making a series of submeasurements and
then stitching the surface segments together to obtain an entire
reconstructed surface. We have implemented it by modifying a phase
shifting interferometer with a mechanical manipulator for shifting
and/or rotating the workpieces under test precisely. An outline
summarising the principles and the algorithms developed, to correct the
aberrations introduced by the misalignment of the submeasurements and
the misregistration of the individual data sets, is presented. The
technique offers considerable potential applications for testing
precision surfaces with large aspheric departures.
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Results of the CIRP-Euromet intercomparison of ball plate-based techniques for determining CMM parametric errors
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Vanherck (1),A. Balsamo (2), M. Franke, E. Trapet, F. Wäldele, L. De Jonge, P
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STC P, 46/1/1997, P.463
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Keywords: co-operative project, coordinate measuring machine (CMM), software error compensation |
Abstract : The general scheme and the results of the intercomparison are presented.
The techniques compared are reviewed and the advantages of using ball
plates to determine CMM parametric errors are illustrated. The
experimental procedures as well as the data reductions are covered by
the comparison. The results show the potential of the compared
techniques. and that they are essentially equivalent in their
capabilities of predicting and compensating for CMM geometrical errors.
Improvements in the scheme are recommended for future intercomparisons
and extensions to other participants.
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A combined optical and mechanical reference artefact for coordinate measuring machines
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H.N. Hansen, L. De Chiffre (2)
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STC P, 46/1/1997, P.467
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Keywords: coordinate measuring machine (CMM), optical probe, calibration |
Abstract : The calibration of CMMs using calibrated ball plates or hole plates is a
well established technique. In the case of CMMs equipped with optical
sensors based upon CCD cameras a series of artefacts based upon
chromium-on-glass structures have been proposed. Calibration of these
artefacts can not be performed using the reversal method which can be
used for ball or hole plates. A new two-dimensional artefact based upon
mechanical elements has been developed allowing both optical and
mechanical probing and calibration. This artefact combines in one piece
the possibilities of performance verification of both optical and
mechanical CMMs. The mechanical elements have been manufactured with
form errors less than 3 pm and using a special surface preparation that
makes optical CNC-measurements non-problematic. Reproducibilities better
than 0.5 pm have been obtained in optical probing. Calibration of the
artefact can be carried out using reversal methods using both optical
and mechanical probing.
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Part form errors predicted from machine tool performance measurements
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R.G. Wilhelm, N. Srinivasan, F. Farabaugh / R. Hocken (1)
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STC P, 46/1/1997, P.471
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Keywords: machining, metrology, tolerancing |
Abstract : Machine tool performance testing, as defined by ISC 230 and ANSI B5,54.
has been successfully used to maintain and improve the accuracy and
repeatability of production-level machine tools. In this study, a
controlled series of experiments have been used to test the efficacy of
these performance tests in the prediction of part form errors. Results
are shown for flatness, squareness. position. and profile tolerances.
The experimental results suggest that standard machine tool performance
tests can also be used to predict the "best-case" tolerances that can
be achieved for particular part features.
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Swept envelopes of cutting tools in integrated machine and workpiece error budgeting
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D. Frey, K. Otto, W. Pflager / R. Donaldson (1)
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STC P, 46/1/1997, P.475
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Keywords: error budgeting, geometric modeling, machining |
Abstract : This paper presents closed form equations for calculating discrete
points on the surface of a machined part given the shape and the motion
function of the cutting tool. This permits rapid calculation of the
effect of machine tool geometric errors on the shape of the machined
part. A valve grinding machine serves as an example application of the
equations. The proper profile of the grinding wheel is derived based on
the desired profile of the valve. The model is also used to estimate
acceptable magnitudes of errors in the machine based on desired par;
tolerances.
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Development of a traceable laser based displacement calibration system with nanometer accuracy
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S.F.C.L. Wetzels, P.H.J. Schellekens (2)
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STC P, 46/1/1997, P.481
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Keywords: displacement calibration, laser measuring instrument |
Abstract : High precision sensors become increasingly sensitive due to the use of
advanced measuring principles and construction techniques. Traceable
accuracy though can only be achieved via calibration. Based on a
Fabry-Perot interferometer we have developed a calibration set-up for
high precision displacement sensors that allows calibrations over a
range of 300 um with an uncertainty of about 0.5 nm. The resolution is
smaller than 0.1 nm.
The resonance frequency of the Fabry-Perot cavity is tracked by a slave
laser. Its frequency is measured against a standard laser. By using the
well known relation between the resonance frequency and the displacement
of the cavity mirror the frequency data can be compared with the readout
of the sensor which is connected to the moving mirror.
By locking the slave laser to successive resonances of the cavity the
calibration range is not limited by the tuning range of the laser.
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STC S |
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Subsurface lattice disorder in polished II-VI semiconductors
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D.A. Lucca (2), C.J. Maggiore
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STC S, 46/1/1997, P.485
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Keywords: surface, polishing, subsurface damage |
Abstract : The near surface lattice disorder created by polishing of II-VI
semiconductors has been examined. Ion channeling was used to quantify
the subsurface damage in single crystal (0001) oriented CdS and (100)
oriented ZnSe. Surfaces prepared by both mechanical and chemo-mechanical
polishing were examined. Both total amount of lattice disorder and
damage depth were found to be significantly higher for ZnSe when
compared to CdS. Investigation of the presence of damage beyond that
identified by the backscattered surface peak for the mechanical polished
ZnSe surfaces was made by study of the rate of dechanneling with depth
below the surface.
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Surface integrity of AlSi9 machined with PCD cutting tool
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G. Byrne (1), J. Barry, p. Young
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STC S, 46/1/1997, P.489
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Keywords: surface integrity, machining |
Abstract : Economic and environmental pressures have lead to the need to replace
manufacturing processes characterised by the use of undefined cutting
edges with those which use a defined cutting edge (e.g. replace honing
with boring). Fundamental to the achievement of this goal is the ability
to generate the surface integrity characteristics of current undefined
cutting edge finishing operations using single point machining
processes. In this paper, the surface integrity of an Aluminium Silicon
Alloy, AlSi9, whose surface has been generated by external cylindrical
turning under dry cutting conditions with Polycrystalline Diamond
cutting tools is examined. For a range of cutting speeds, feeds and
depths cf cut, measurements of cutting force, topography of the machined
surface micro-hardness and work hardening backed up with
optical/electron microscopy were undertaken, Good replication of the
tool profile on the machined surface was found to exist, with no
evidence of work-hardening. The main surface defect observed was small
craters or pits, and these have been directly associated with the
microstructure of the alloy.
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Influence of processing conditions and reinforcement on the surface quality of finish machined aluminium alloy matrix composites
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H. Chandrasekaran (2), J.O. Johansson
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STC S, 46/1/1997, P.493
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Keywords: grinding, surface, composites |
Abstract : Fibre/particle reinforced aluminium alloy matrix composites appear to
have a good future as candidate material for engineering components.
However, their machinability is poor and surface quality is not
established. The influence of finishing operation (mainly grinding) upon
the surface quality of some experimental aluminium alloy matrix
composite materials manufactured by different methods was systematically
investigated. These materials contained different type, size and amount
of hard reinforcements. Surface quality was evaluated and the relative
influence of processing and reinforcement was mapped using profilometry
and scanning electron microscopy (SEM). In most instances surface damage
in terms of particle/fibre pull out and cavity formation, detrimental in
applications involving friction and corrosion, was observed.
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A comparison of topographic characterization parameters in grinding
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A.J. Terry, C.A. Brown (2)
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STC S, 46/1/1997, P.497
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|
Keywords: surface roughness, statistical test, grinding |
Abstract : Parameters for characterizing topographies and a method of selecting
these parameters are investigated. Conventional and scale-sensitive
fractal parameters are tested for cross-correlations, ability to
differentiate process variables and ability to relate grinding wheel
topography with ground surface topography. Surfaces were ground using
different wheels, dress leads and removal rates. Profiles were acquired
by contact stylus profiling parallel and perpendicular to the grinding
direction on the grinding wheels and the ground surfaces. The
conventional height parameters tend to be more cross-correlated than the
spacing and fractal parameters. No parameters in this study could
differentiate the process variables or could relate wheel and workpiece
topographies in all situations. The waviness height (Wt; was the best
for differentiating process variables, and a scale-sensitive
fractal-based parameter, the smooth-rough crossover (SRC), was best at
relating workpiece and wheel topographies.
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A new speckle-interferometric approach to measure the 3D-shape-measurement of discontinuous free form surfaces
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T. Pfeifer (2), J. Evertz, H. Mischo
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STC S, 46/1/1997, P.501
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Keywords: metrology, optical measurement technique, optical measuring instrument |
Abstract : In Electronic Speckle Pattern Interferometry (ESPI) the introduction of
sc-called translation and multiple-wavelength-techniques enable the user
to collect data relating to a 3D-topography within a short space of
time. While smooth surfaces may be measured using standard approaches,
the investigation of shapes with discontinuities demands more advanced
techniques. Various methods have been studied at the IPT. Our results
demonstrate that by transfering the concept of Coded Light Sectioning to
an ESPI translation-technique in a generalised form, a wide variety of
free forms, particularly those with large discontinuities can be
measured with high levels of resolution and accuracy. The paper
describes this new approach and presents various examples of current
applications.
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On mirror surfaces obtained with and without polishing
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V.C. Venkatesh (1), F. Fang, W.K. Chee
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STC S, 46/1/1997, P.505
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Keywords: mirror surfaces, scratching, ultra-precision machining |
Abstract : Mirror surfaces were created by turning and/or grinding various
materials: silicon, glass (pyrex and BK7), aluminum & Si alloy, and
zinc selenide, some unpolished and others polished. The mirror surfaces
were assessed by two novel techniques, one by measuring lightness (a
measure of their reflectivity), and the other by scratching with a
coni-cylinderical diamond (fully, symmetrical), as against the
traditional Vickers diamond indentor that has two alternate cutting
edges (face or wedge). By using an AFM to section the scratch, the pile
up (double or single) was observed and SEM confirmed the nature of the
scratch whether it was ductile or brittle. Results show that polishing
improves the mirror surface however good the initial surface may be.
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