CIRP ANNALS 1999
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STC A |
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Learning force control for position controlled robotic manipulator
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B. Qiao, J.Y. Zhu (1), Z.X. Wei
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STC A, 48/1/1999, P.1
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Keywords: Robotic manipulator, Force control, Learning |
Abstract : This paper presents a learning force control framework for position
controlled robotic manipulators. A learning mechanism is established to
compensate the uncertainties regarding stiffness of constraint
environment in an iterative manner. A target impedance model is
specified and its reference trajectory is generated according to on-line
data of force feedback and position. The target impedance model is
driven by force error to produce a command position, by tracking the
commanded position the end-effector of manipulator will follow the
unknown constraint surface while tracking a desired interaction force.
Computer simulations based on a three linked planar robotic manipulator
show that contact force can be effectively controlled as the operations
are repeated.
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Development of a closed-loop controlled reflow soldering process
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P.P. Conway, S.M. Hyslop, D.J. Williams (2)
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STC A, 48/1/1999, P.5
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Keywords: Soldering, Control, Joining |
Abstract : The assembly of electronics using surface mount technology is in
constant change because of the reduction of the feature size of
components that must be assembled. Ideally design for manufacture and
process optimisation would be applied to bring processes under control.
Unfortunately this approach is not possible because of the wide
variation of physical and material properties critical to manufacturing
encountered in practice. Consequently we have created the Adaptive
Intelligent Bellow (A.I.R.) process using feedback from a line scanning
infra red sensor. This paper presents the key features of this novel
closed loop processing machine and the challenges addressed in its creation.
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Automated assembly of lightweight automotive components
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K. Feldmann (1), B. Müller, T. Haselmann
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STC A, 48/1/1999, P.9
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Keywords: Assembly, Control, Handling |
Abstract : The assembly of large lightweight components indicates a high rate of
manual assembly operations. For a higher degree of automation the
Institute of Manufacturing Automation and Production Systems develops
systems for complete-assembly. The aim of complete-assembly of large
components is to reduce the number of process steps. Failure-tolerant
assembly systems are used to detect deviations of process influencing
parameters and react independently to them. Both concepts are designed
to create robust, shortened process sequences to reduce the costs of
production and to improve quality.
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Computer-aided visual inspection in assembly
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M. Lanzetta, M. Santochi (1), G. Tantussi
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STC A, 48/1/1999, P.13
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Keywords: Assembly, Visual inspection, Image analysis algorithm |
Abstract : Some of the more critical aspects for the diffusion of vision systems in
assembly plants are the skill required for the system set-up, the
definition of algorithms and the programming phase. In this paper a new
methodology is proposed to reduce the implementation time and cost by
means of a computer-aided system working off-line. The designed system
named CAVIS (Computer Aided Visual Inspection System) integrates several
modules as product and algorithm databases, expert system for decision
support, CAD modeller to generate synthetic images and software design.
Some of the modules are still at a development stage. The output are the
vision devices configuration and the inspection software. CAVIS has been
tested on an industrial application for error detection in assembly: a
new general-purpose algorithm for visual inspection is presented and
results are discussed. The main features of the algorithm are suitable
with the described approach: easy programming, unnecessary vision
operator's experience, and off-line preliminary estimation of parameters.
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Generation of optimized assembly sequences using genetic algorithms
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G. Dini (2), F. Failli, B. Lazzerini, F. Marcelloni
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STC A, 48/1/1999, P.17
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Keywords: Assembly planning, Sequencing, Genetic algorithm |
Abstract : This paper describes a method based on genetic algorithms for the
generation and the evaluation of assembly sequences. Genetic algorithms
are here used to drastically reduce the high computational time, usually
necessary to evaluate the best assembly sequences, owing to
'combinatorial explosion' phenomena. The generation of optimized
sequences is performed using an appropriate fitness function which takes
into account simultaneously the geometrical constraints, the
minimization of gripper changes and object orientations, and the
possibility of grouping similar assembly operations (screwing, pressing,
etc.). The paper also presents the chromosome structure used in the
system, the genetic operators and, finally, a meaningful example of
application.
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Agent-based approach for assembly control
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G. Seliger (2), D. Krützfeldt
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STC A, 48/1/1999, P.21
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Keywords: Assembly, Co-operative manufacturing, Agent theory |
Abstract : In manufacturing, fluctuations in production occur along the
value-adding chain due to changes in customer orders or process
failures. In the heterogeneous environment of supplier and customer
relations assembly integrates material flows. Assembly is therefore
highly susceptible to fluctuations in supply. In order to avoid delays
due to parts in short supply, or long queues, the supplier and
transportation agency must be an integral part of assembly control. In
this paper, an agent-based approach is introduced to achieve a smooth
balance between supply, transport and assembly. Agents act according to
a predetermined set of rules and know which other agents to turn to when
fluctuations in production occur. The assembly of motor-cars is taken as
an example to illustrate this approach.
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Assembly process and assembly control development - a holistic and consistent approach
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G. Reinhart (2), R. Cuiper
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STC A, 48/1/1999, P.25
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Keywords: Assembly, Computer Aided Planning (CAP), Controlling |
Abstract : Simultaneous engineering usually covers the integration of design and
planning during product development. Yet there is still a gap between
the planning and the subsequent implementation of assembly systems. This
article describes an approach to the consistent integration of assembly
systems planning into the control system of a real assembly facility
within the same environment. The control mechanism developed can be used
to simulate manufacturing cells for validation purposes as well as to
communicate with real assembly fixtures and equipment.
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STC C |
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A new method for chatter detection in turning
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I. Grabec (2), J. Gradisek, E. Govekar
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STC C, 48/1/1999, P.29
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Keywords: Turning, Chatter |
Abstract : A new method for detection of chatter onset is developed based on
characterization of changes in process dynamics. Its performance is
demonstrated by the experiments with turning in which the transition to
chatter is caused by variation of cutting depth. The signal of cutting
force is characterized by the normalized coarsegrained entropy rate
whose value exhibits a drastic drop at the onset of chatter. For the
purpose of automatic on-line chatter detection a characteristic value of
coarse-grained entropy rate is determined which is rather insensitive to
variation of cutting conditions.
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The effects of cutting tool thermal conductivity on tool-chip contact length and cyclic chip formation in machining with grooved tools
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A.K. Balaji, G. Sreeram, I.S. Jawahir (2), E. Lenz (1)
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STC C, 48/1/1999, P.33
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Keywords: Machining, Tool thermal conductivity, Chip formation |
Abstract : This paper presents an experimental analysis of the effects of cutting
tool thermal conductivity on machining performance of grooved tools. A
new methodology for defining the tool-chip contact length in grooved
tools is proposed. Performance of uncoated carbide grooved tools tested
under a range of thermal conductivities (3292 W/m deg.K) are correlated
with the variations of cyclic cutting forces, developed chip length,
chip thickness and chip breaking patterns. The thickness of the retarded
zone and the grain elongation orientation in the chip are measured along
the curled chip and their strong influence on the chip formation process
is shown.
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Dynamic interrogation of a basic cutting process
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J.R. Pratt, M.A. Davies (2), C.J. Evans (2), M.D. Kennedy
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STC C, 48/1/1999, P.39
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Keywords: Vibration, Modeling, Turning |
Abstract : A dynamic cutting fixture based on the test rig pioneered by Peters et
al. has been developed to aid investigations of cutting process
dynamics. This active fixture consists of a flexure-based tool holder
with a single dominant modal direction, two voice-coil type actuators
for excitation and control, sensors for measuring tool displacement and
acceleration, and analog electronics for feedback control of the
structural dynamics. The sensing and actuation features of this fixture
are exploited to identify model parameters and to examine the transition
from stable cutting to chatter by comparing experiment to theory and
simulation.
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A fluid dynamic analysis model of the ultra-precision cutting mechanism
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K.B. Kwon, D.W. Cho, S.J. Lee, C.N. Chu (2)
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STC C, 48/1/1999, P.43
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Keywords: Ultra-precision machining, Cutting force, Specific energy |
Abstract : The technology required for ultra-precision machining of non-ferrous
metals is relatively well established, owing to significant improvements
in the performance of the hardware used. However, no satisfactory
analytical model has been developed for very small cutting depths of
this process, demonstrating that the physics of the ultra-precision
machining process are not well understood. This paper presents the
development of an ultra-precision cutting model based on fluid mechanics
that considers not only cutting tool geometry, including the cutting
edge radius, but also the effect of elastic rebound at the flank face.
This is the first time that a fluid dynamic model has been used to
predict the effect of a cutting edge, its size effect, and the cutting
forces during ultra-precision cutting. This model can also be used to
provide estimates of the chip curling radius and tool-chip contact length.
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Determination of convective cooling conditions in turning
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L. Kops (1), M. Arenson
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STC C, 48/1/1999, P.47
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Keywords: Turning, Workpiece, Cooling |
Abstract : The convective heat transfer coefficients, necessary for modelling of
the thermoelastic behaviour of a workpiece, were determined directly for
turning conditions on a lathe, in air and in coolant. A model of a
cylindrical workpiece with convective boundaries was solved for
temperature distribution using a Control Volume Finite Difference code.
An iterative optimization procedure matched the computer prediction with
the experimental temperature measurements to within less than 1 oC
average difference,. The values of heat transfer coefficient determined
for various cooling zones on the workpiece, including the chuck zone and
the heat transfer coefficient distribution in the impinging coolant
zone, were validated through the cutting experiments. The results are
illustrated through the comparison of computed and experimental cooling
curves. Presented methodology can be applied to obtain the heat transfer
coefficient values for cooling in other conditions, and to establish a
convection data bank needed to predict the effect of thermal expansion
of a workpiece on resulting accuracy in turning.
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The effect of tool flank wear on the heat transfer, thermal damage and cutting mechanics in finish hard turning
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J.Y. Wang, C.R. Liu / K.K. Wang (1)
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STC C, 48/1/1999, P.53
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Keywords: Hard turning, Flank wear, Heat transfer |
Abstract : Tool flank wear is a major cause of thermal damage in the machined
surface layer in finish hard machining. A new methodology is developed
to provide the knowledge needed for understanding the heat transfer
regarding the formation of the thermal damage and the cutting mechanics.
The methodology consists of a thermal model based on Green's function
and a microstructure-based method using orthogonal hard turning. The
coupling of the interface boundary conditions due to chip formation and
flank wear is resolved using the proposed microstructure-based method,
which is a departure from the conventionally incorrect approaches based
on the assumption of constant chip formation. By incorporating the
microstructure-based method with the thermal model, heat generated, heat
partition, and the shear forces at the tool-chip and tool-work
interfaces can be determined. Interface temperatures that are extremely
difficult to be measured are obtained. The results quantitatively
explain how the heat transfer and chip formation are altered as the tool
flank is progressively worn.
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Surface integrity generated by precision hard turning
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Y. Matsumoto, F. Hashimoto (2), G. Lahoti (1)
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STC C, 48/1/1999, P.59
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Keywords: Cutting, Residual stress, Hard turning |
Abstract : Rolling contact fatigue tests were conducted to find the effect of
precision hard turning. The tests showed that hard turning provides as
good a fatigue performance as grinding. Hard turning produces
compressive residual stresses in a deep subsurface, which contribute to
a long fatigue life. The effect of cutting parameters on residual stress
was investigated in order to find why deep residual stresses are
created. It was determined that the tool edge geometry is the dominant
factor deciding the residual stress profile.
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Temperature measurement of CBN tool in turning of high hardness steel
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T. Ueda, M. Al Huda, K. Yamada, K. Nakayama / H. Kudo (1)
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STC C, 48/1/1999, P.63
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Keywords: Turning, Temperature, Cubic boron nitride (CBN) |
Abstract : The temperature at the tool flank, which has an effect on the tool life
and on the machined surface integrity, is measured using a two-color
pyrometer with a fused fiber coupler. This pyrometer makes it possible
to measure the temperature of a very small object without emissivity
affecting the results. A CBN tool is used as the cutting tool. A high
carbon chromium bearing steel, a chromium molybdenum steel and a
quenched carbon steel are used as work materials. The temperature of the
tool is highly affected by the cutting speed, but the influence of the
depth of cut and the feed rate is not so great. In the cutting of the
high carbon chromium bearing steel, the temperature is 800 °C at a
cutting speed of 100 m/min and increases with the increase of cutting
speed, reaching 950 °C at 300 m/min. There is a close relation between
the tool temperature and the hardness of the work material. The
influence of cutting speed on tool wear is considerable.
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Orientation effects in nanometric cutting of single crystal materials: an MD simulation approach
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R. Komanduri (1), N. Chandrasekaran, L.M. Raff
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STC C, 48/1/1999, P.67
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Keywords: Simulation, Single crystal, Cutting |
Abstract : Molecular Dynamics (MD) simulations of nanometric cutting on single
crystal aluminum were conducted to investigate the nature of the chip
formation process with crystal orientation. Extensive dislocation
generation ahead of the tool in the workmaterial was found principally
along, normal to, along and normal to, or at -- 45 deg. or -- 60 deg. to
the cutting direction depending on the specific orientation and
direction of cutting. These differences in the dislocation motion
observed here for the first time lead to significant variations in the
nature of plastic deformation ahead of the tool and consequent variation
in the magnitude of the forces, force ratio, specific energy, and
subsurface deformation.
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Drilling burr formation in Titanium alloy, Ti-6AI-4V
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D.A. Dornfeld (1), J.S. Kim, L.J. Chen, J. Hewson, H. Dechaw
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STC C, 48/1/1999, P.73
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Keywords: Titanium, Drilling, Burr |
Abstract : Titanium alloy (Ti-6AI-4V) plates were drilled to investigate the
effects of tool geometry as well as process conditions on the drilling
burr formation. Drilling was done with solid carbide tools with and
without coolant and high speed cobalt drills without coolant. Four
distinct burr types were observed. During dry cutting, a "rolled back"
type burr was observed at high feed rates and cutting speeds and is
believed to be due to thermal effects. A "ring" type burr was observed
when drilling with coolant. While cutting conditions had little effect
on the burr sizes formed, drill geometry (helix angle, split point vs.
helical point, lip relief angle and point angle) affected burr thickness
and height.
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Machinability of graphitic Metal Matrix Composites as a function of reinforcing particles
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V. Songmene, M. Balazinski (2)
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STC C, 48/1/1999, P.77
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Keywords: Composite, Machining, Wear |
Abstract : Aluminum Metal Matrix Composites (MMCs) reinforced with ceramic
particles have been developed for high wear resistance applications such
as cylinder liners and brakes as a replacement for gray cast iron.
Ceramic particles in an aluminum matrix improve its wear resistance
property, but also cause high abrasive wear on cutting tools, which
results in poor tool life and inconsistent part quality. A new family of
MMCs (GrA-Ni(D) consisting of an aluminum matrix reinforced with
nickel-coated graphite particles and SiC or AI203 particles was recently
developed. This paper presents the results of machining tests conducted
to assess the machinability of the new graphitic ceramic reinforced
MMCs. It was found that graphitic aluminum MMC reinforced with alumina
is easier to machine than those reinforced with both SiC and graphite or
SiC particles only. The incorporation of graphite into these composites
and the variation of hard particle content improve their machinability.
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Crack initiation in machining monocrystalline silicon
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T. Inamura, S. Shimada (2), N. Takezawa, N. Ikawa (1)
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STC C, 48/1/1999, P.81
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Keywords: Machining, Brittle material, Computer simulation |
Abstract : Based on the discussion in which the defect as a source of cracks must
be created during cutting a silicon monocrystal, the renormalization
group molecular dynamics has been proposed to simulate the defect
initiation process. The method can be applied to a model of micrometer
size, which is necessary to bring about brittle mode cutting, and yet
permit the observations of the defect initiation process of an atomic
size. The result of the simulation shows that a microcrack-like defect
can be initiated during cutting through the interaction between a local
static stress distribution and global dynamic stress associated with
acoustic waves.
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STC Dn |
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Development of DVD for the next generation by axiomatic approach
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S.W. Cha, K.K. Cho (1)
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STC Dn, 48/1/1999, P.85
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Keywords: Axiom, Performance, Digital-Versatile-Disk |
Abstract : DVD(Digital Versatile Disk) is a media for data storage device for high
density and high speed information processing. Therefore higher
rotational speed and better accuracy in optical pick-up are required
compared with the existing devices. These functional requirements must
be satisfied in order for DVD to keep its status as the high capacity
data storage device.
This paper first evaluates the currently developed DVD, and also
provides methods to improve the current design using an Axiomatic
Approach which is an excellent tool in deriving a new design as well as
evaluating an existing one.
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Managing design knowledge : active document system
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S. Ha, G. Pahng, M. Chang, S. Park, H.M. Rho (2)
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STC Dn, 48/1/1999, P.89
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Keywords: Design information, Knowledge management, Product function deployment |
Abstract : Sharing design knowledge within a company is critical to retain market
competitiveness, especially when the company develops a family of
products. The goal of this study is to develop a Web-based design
knowledge management system, named Active Document System, that helps
designers retrieve critical design information promptly. In order to
manage unstructured knowledge such as design know-how systematically,
Active Document System classifies design knowledge in accordance with
product functions as well as product structures.
This paper explains Active Document System and a method to deploy the
product function. The concept is implemented and applied to the
management of design knowledge for the refrigerator design process.
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An information modelling framework for product families to support mass customization manufacturing
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J. Jiao, M.M. Tseng (2)
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STC Dn, 48/1/1999, P.93
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Keywords: Engineering Design, Product Family, Modeling |
Abstract : Developing product families has been recognized as an effective means to
support Mass Customization Manufacturing (MCM). A Product Family
Architecture (PFA) resembles the underpinning logic of assisting
customers to converge to what a firm can deliver in terms of its
capabilities and capacities. The representation of a PFA is essential
for managing variety effectively across the entire product realization
process encompassing sales, marketing, design, and manufacturing. This
paper proposes a generic PFA representation in terms of representing
multiple views of product families in a single context, using one
generic variety representation structure for different views to minimize
data redundancy, and generating specifications of individual product
variants for different business functions coherently. Accordingly, an
information modeling framework for product families is developed based
on a combination of elements of semantic relationships with the
object-oriented data model. An application of the proposed framework is
demonstrated for power supply products. Also reported is a prototypical
implementation using KAPPA-PC`'.
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Utilizing image processing techniques for 3D reconstruction of laser-scanned data
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A. Fischer (2), A. Manor
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STC Dn, 48/1/1999, P.99
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Keywords: Reverse Engineering, Image Processing, Surface Reconstruction |
Abstract : In Reverse Engineering, laser scanners are commonly used since they can
sample 3D data fast and very accurately relative to other systems. Laser
scanner systems, however, yield an enormous amount of irregular and
scattered digitized point data that requires intensive processing in
order to reconstruct the surface of the object. It appears that
combining 3D scanned data with 2D intensity images can significantly
improve the reconstruction process. This paper proposes a new adaptive
reconstruction method that integrates information from a CCD camera with
scanned laser data. The method is based on: (a) Detecting a 3D boundary
of the parametric base surface. (b) Adaptively reconstructing a
parametric base surface with a non-self-intersecting grid. (c)
Calculating the parameterization of the 3D sampled points. (d) Fitting
the surface by applying a least square (LSQ) approximation method with
boundary constraints. The feasibility of the parameterization algorithm
is demonstrated on sculptured free objects.
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A new concept for the design and the manufacturing of free-form surfaces: the Machining Surface
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E. Duc, C. Lartigue, C. Tournier, p. Bourdet (1)
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STC Dn, 48/1/1999, P.103
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Keywords: Design Intents, Geometric Modeling, Free-Form Machining |
Abstract : This paper deals with a modeling method of free-form surfaces based on
the new concept of the machining surface. The machining surface is built
so that design intents and manufacturing requirements are ensured and so
that it completely defines the tool movement necessary to produce a
part. Therefore, approximations appearing during the elaboration process
(CAD modeling, tool path calculation and free-form machining) are
minimized. The concept of the machining surface described here relies on
an analysis of the process quality.
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Diverse aspects of tolerancing on an integrated design context
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S. Tichkiewitch (2), D. Brissaud
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STC Dn, 48/1/1999, P.107
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Keywords: Integrated Design, Product model,Tolerancing |
Abstract : During design, tolerancing is typically a distributed activity in order
to respect the clearances of the functional specifications, the
capabilities of the manufacturing processes, the possibilities of the
assembly process and to increase the time to failure in service. We show
how a product model used in an integrated design system is able to take
into account the specificities of the tolerancing. This model permits to
specify the relations between the different views.
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Analysis and validation of 3D laser sensor scanning process
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A. Bernard, M. Véron (1)
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STC Dn, 48/1/1999, P.111
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Keywords: Scanning process simulation, Inspection, Optimization |
Abstract : This paper presents research results [1] performed on automating the
digitizing process of a complex part using a precision 3D laser sensor.
Operations that perform digitizing are largely manual leading to data
redundancies or missing points. In addition, the time taken for part
digitizing immobilizes the machine reducing its overall optimization.
A new method to automatically scan a well-known part is presented. After
introducing the digitizing environment, an analysis of the critical
steps in the procedure is described. The acquisition procedure is
introduced and adapted by CAD software to simulate and validate 3D
laser-scanning paths.
Additional procedures, still under study, are described for the
automation of data generation of the laser scanning process.
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STC E |
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Reverse simulation of die-sinking EDM
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M. Kunieda (2), W. Kowaguchi, T. Takita
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STC E, 48/1/1999, P.115
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Keywords: Die-sinking EDM, Reverse simulation, Tool electrode wear |
Abstract : This research aims to develop a simulation method for die-sinking EDM to
solve the inverse problem of obtaining the appropriate tool electrode
shape for achieving the desired final workpiece shape. In the reverse
simulation method developed, the same algorithm as that used in forward
simulation is adopted. The workpiece is however fed towards the tool
electrode in the direction opposite to forward simulation, and the
values for the depth of the layers removed from the tool electrode and
workpiece surface per pulse discharge are the reverse of forward
simulation. The algorithm is a simple repetition of the procedure
comprised of: 1) determining the next discharge location, 2) removing
the tool and workpiece electrodes, 3) distributing the debris particles,
and 4) feeding the tool electrode.
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Integration of rapid prototyping and electroforming for tooling application
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B. Yang, M.C. Leu (2)
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STC E, 48/1/1999, P.119
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Keywords: Rapid prototyping, Tooling, Mold |
Abstract : Solid freeform fabrication integrated with electroforming as a novel
process for the generation of metal molds and EDM electrodes is
presented in this paper. A part built by stereolithography is metalized
by electroless plating and then placed in an electroplating solution
where metal is deposited upon the part by electrolysis. After the
desired thickness of metal has been reached, the part is removed from
the metal shell by heating. The shell is then backed with other
materials to form a mold cavity or an EDM electrode. The accuracy of the
formed mold cavity or EDM electrode influenced by materials and process
parameters is discussed.
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Effect of flushing and electrode material on die sinking EDM
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P.M. Lonardo (1), A.A. Bruzzone
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STC E, 48/1/1999, P.123
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Keywords: Die-sinking EDM, Surface quality, Productivity |
Abstract : The most important parameters of EDM are the removal rate, the electrode
wear, accuracy and surface texture. In this paper the influence of
electrode material, flushing, electrode dimension, depth of cut and
planetary motion on EDM performance is discussed.
An experimental analysis was carried out on a Cr, Mo, V steel for die
casting by using both copper and graphite electrodes. Roughing and
finishing operations were considered, by adopting for each condition the
parameters commonly recommended in industrial production.
The observed results show the importance of electrode material,
injection flushing and geometry of cutting on removal rate, electrode
wear and surface quality.
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Typical metrology of micro-hole arrays made in stainless steel foils by two-stage micro-EDM
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D.M. Allen (2), H.J.A. Almond, J.S. Bhogal, A.E. Green, P.M. Logan, X.X. Huang
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STC E, 48/1/1999, P.127
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Keywords: Micro-EDM, Metrology, Bore Surface Quality |
Abstract : Two-stage micro-EDM utilises one machine to fabricate electrodes and a
second machine to manufacture holes. The diameter and taper of a hole
are dependent on the accuracy of the electrode fabrication which has now
been quantified. The accuracy of hole positioning has also been measured
using commercial equipment in a novel application. The surface roughness
and uniformity of the internal surfaces of the holes (typically 50 ~im
in diameter) have been examined using a novel method not involving
cross-sectioning. Random surface microcracks appear to be
metallurgy-dependent, not process related.
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Micro-ultrasonic machining by the application of workpiece vibration
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K. Egashira, T. Masuzawa (1)
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STC E, 48/1/1999, P.131
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Keywords: Ultrasonic machining, Micromachining, Workpiece vibration |
Abstract : A new method for microultrasonic machining (MUSM) has been developed. In
order to obtain high-precision tool rotation, the spindle mechanism
employed in micro-EDM machines was introduced. Since the mechanism does
not allow the vibration of tools, the workpiece was vibrated during
machining. Using this setup, we have succeeded in machining microholes
as small as 5Nm in diameter in quartz glass and silicon. In this
machining range, high tool wear posed a problem. To solve this problem,
a sintered diamond (SD) tool was tested and was proven to be effective.
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Ultrasonic machining : an analytical and experimental study on contour machining based on neural network
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Y. Benkirane, D. Kremer, A. Moisan (1)
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STC E, 48/1/1999, P.135
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Keywords: Ultrasonic Machining, Neural Network, Performance |
Abstract : Ultrasonic machining is a process used to machine brittle and hard
materials (glass, quartz, ceramic). The material is removed by the
abrasion and erosion caused by particle agitation and pressure variation
within the abrasive fluid. Much work has already been done on the
process: the effects of parameters on performance have been described,
but restricted to sinking or drilling.
This paper concerns the study of contour machining using a 3 axis
numerical control machine. In order to understand its principles and to
be able to predict the material removal rate for modelling and
simulation of the process, an experimental and analytical work is being
carried out.
Plans of experiments have made it possible to get the performance of the
process, characterized by the removal rate and surface quality. The
effects of the main parameters have been studied using two statistical
methods. They show an advantage for the neural network one, which gives
a more precise prediction of the removal rate compared with the Taguchi
method. Moreover the proposed approach seems to be well adapted to the
modelling of multi parameters processes.
|
|
Improvement of electrochemical machining accuracy by using orbital electrode movement
|
|
K.P. Rajurkar (2), D. Zhu
|
|
STC E, 48/1/1999, P.139
|
|
Keywords: Electro-chemical machining, Accuracy, Improvement |
Abstract : The improvement of machining accuracy of electrochemical machining (ECM)
continues to be a major challenge for user industries. This study
focuses on the development of a precision ECM process by using an
eccentric orbital anode movement with traditional ECM. The feasibility
of the proposed process has been experimentally verified. Theoretical
and experimental analyses indicate that orbital ECM distributes the
electrolyte flow more uniformly and hence leads to a significant
reduction in the flow field disrupting phenomena that adversely affect
machining accuracy. The proposed method has been found to offer
substantial gains in the accuracy and the uniformity of machined components.
|
|
The effect of pad wear on the chemical mechanical polishing of silicon wafers
|
|
G. Byrne (1), B. Mullany, p. Young
|
|
STC E, 48/1/1999, P.143
|
|
Keywords: Chemical Mechanical Polishing, FEM, Wear |
Abstract : The Chemical Mechanical Polishing process planarises wafers with a high
degree of success, however wear on the polishing pad causes the
planarisation rate and the post-process planarity to deteriorate. To
date, there has been no method of predicting the effect of this wear on
the wafer planarity. Using finite element models of the process for new
and worn pads the wafer stress distribution on the wafer surface can be
predicted. Equating high stresses to high material removal rates these
models predict that the process should become `centre slow' as the pad
wears. This correlates well with experimental data.
|
|
A non-invasive solidification sensor for metal casting
|
|
J.H. Chun (2), M.M. Hytros, I.M. Jureidini, N. Saka, R.C. Lanza / N.P. Suh (1)
|
|
STC E, 48/1/1999, P.147
|
|
Keywords: On-line Sensor, Casting, Real Time |
Abstract : A non-invasive sensor based on high-energy x-ray computed tomography has
been developed for monitoring the progression of solidification in metal
casting. The sensor comprised a 6 MeV linear accelerator and a
128-channel CdW04 detector array. Laboratory experiments were performed
on cylindrical castings of pure aluminum and its alloys. The sensor
produced a series of time-lapse images showing the movement of the
liquid/solid interface during solidification. The solidification front
was imaged every two minutes with a planar spatial resolution of 1.6 mm
and a contrast sensitivity of 1.5%37;. The tomography results agreed well
with those obtained by thermocouple measurements.
|
|
Investigation on multi-layer direct metal laser sintering of 316 L stainless steel powder beds
|
|
W. O'Neill, C.J. Sutcliffe, R. Morgan, A. Landsborough, K.K.B. Hon (2)
|
|
STC E, 48/1/1999, P.151
|
|
Keywords: Laser Sintering, Metal, Powder |
Abstract : Research and development of laser based sintering technology has
occurred at a rapid pace since its invention in the 1980s'. A wide range
of materials have been developed including polymers, metals and
ceramics. The ultimate goal for this technology is to provide
manufacturing industries with fast and flexible means of producing parts
that are truly functional. Step by step this active research area is
leading towards rapid manufacturing solutions which will be
significantly different from the rather limited rapid prototyping
solutions of today. In processing metallic materials, porosity is still
a major problem although a number of notable solutions such as
infiltration with low melting point alloys or direct fusing with binary
powder mixtures have been proposed. Neither of these solutions allows
one to build components without compromising part strength and
functionality. A process route is required that will allow solid parts
to be built from a single powder component without requiring time
consuming downstream processes. The surface quality must be consistent
with those attainable by modern machining techniques. To this end, the
present work examines the feasibility of using low energy high peak
power laser pulses from a Q-switched Nd:YAG laser to melt stainless
steel powder fractions whilst examining the melt displacement and the
effects of rapid vaporisation of the powder layer.
|
|
An experimental and numerical study on the influence of not uniform beam energy distribution in laser steel hardening
|
|
L.M. Galantucci, L. Tricarico / G. Perotti (1)
|
|
STC E, 48/1/1999, P.155
|
|
Keywords: Laser, Hardening, Modelling |
Abstract : In this work the influence of the beam not-uniform energy distribution,
typical of new sources such as diode lasers, was investigated in the
laser hardening of carbon steels. A transient numerical model, based on
the Finite Element Method, was implemented in order to analyse the
process in these particular conditions, and to provide a tool for the
off line design and simulation of the treatment.
An experimental set up was prepared to have beam characteristics similar
to those that will be offered when high power diode lasers will be
available for industrial applications: an elliptical beam with a not
uniform energy distribution was obtained operating with an integrator
mirror on a CO2 CW laser. The heat treatment was performed with various
parallel beam tracks, also by experimenting different degrees of
overlapping; the numerical results were compared with the
microstructures and the measured micro-hardness obtained on the specimens.
The study shows that the FEM simulation can give prediction in good
agreement with the experimental observation, considering how the
microstructures and the obtainable hardness are influenced by the beam.
|
|
On-line process control used in the laser welding of metal sheet lightweigth structural panels
|
|
G. Ricciardi (2), M. Cantello (2), F. Mariotti, p. Castelli, M. Penasa
|
|
STC E, 48/1/1999, P.159
|
|
Keywords: Laser, Welding, Quality assurance |
Abstract : Lightweight Structural Panels (LPS) made out of multilayer thin metal
sheets are innovative materials which allow high structural performances
combined with low weight and low material cost. Among the possible
configurations a new option defined Cellular and Stratified lamination
(C&S) makes use of a double corrugated core joined to external skins
which leads to isotropic performance. Double corrugation creates a grid
of bumps which have to be welded to the external flat skins.
Nd:YAG laser spot welding was selected to reduce distortion. Since C&S
structural performance is affected by spot weld strength, a process
control based on plasma emission during laser processing was developed.
The system described in the paper allows continuous monitoring of the
weld quality, highlights the unrecoverable defecs, and modulates laser
parameters in order to compensate efficiency decay and assure product
quality.
|
|
Theoretical and experimental investigation of pulsed laser cutting
|
|
H. Kaebernick (2), D. Bicleanu, M. Brandt
|
|
STC E, 48/1/1999, P.163
|
|
Keywords: Cutting, Laser, Modelling |
Abstract : A three-dimensional analytical model of pulsed laser cutting has been
developed, particularly aimed at predicting the quality of cut under
various cutting conditions. The model is based on infinitesimal point
heat sources, representing the effect of the laser beam on the surfaces
inside the cutting zone, and it includes the contribution of the oxygen
reaction to the heating of the metal. Experiments with an NdYAG-Laser,
cutting mild and stainless steel, were carried out to verify the
predicted cutting results for various speeds, powers and pulse
characteristics.
|
STC F |
|
CAOT - A computer aided optimization tool applied on metal forming processes
|
|
R. Kopp (2), S. Posielek
|
|
STC F, 48/1/1999, P.167
|
|
Keywords: Optimization, FEM, Computer aided planning |
Abstract : The high demand of simulations for process optimization and the large
computational effort for practice relevant examples require a new basic
approach for optimization concept. This led to the development of the
parallel organized optimization model CAOT. The new system reduces, as a
result of the parallel organization, the high simulation times and
accelerates therewith the complete optimization process. The open
architecture allows the application of diverse optimization algorithms,
as well as a direct coupling to any simulation program. Miscellaneous
metal forming processes can be handled and optimized under consideration
of component properties and die loading.
|
|
Product development support for suppliers of forgings
|
|
E. Doege (1), M. Muckelbauer, M. Michael
|
|
STC F, 48/1/1999, P.171
|
|
Keywords: Hot forming, Product development, CAD |
Abstract : This paper describes software tools which were developed at the
Institute for Metal Forming and Metal Forming Machine Tools at the
University of Hanover, Germany (IFUM) as add-ons for the CAD system
Pro/ENGINEER. The software tools support the entire forging design
process from the rough design to the finished part. It is now possible
to use information on the functionality of the product for forging
design instead of technical drawings or conventional CAD models. The
described approach supports the migration of the product development
from the customer to the supplier. The use of FEM for the load
simulation and the PRINZ simulation tool (also developed by IFUM), which
calculates and visualizes the material flow during the forming process,
are also described.
|
|
An intelligent computation approach to process planning in multiple-step cold forging
|
|
R. Teti (2), A. Langella, D. D'Addona
|
|
STC F, 48/1/1999, P.175
|
|
Keywords: Cold Forging, Process Planning, Neural Networks |
Abstract : An intelligent computation approach to time and cost reduction in
process planning of cold forging operations is illustrated. The problem
taken into consideration is the generation of optimized working
sequences in the fabrication of multi-diameter shafts through
multiple-step cold forging. A supervised learning neural network
paradigm was employed in order to identify the technologically feasible
working sequences to be considered for process planning decision making.
The process planner can then select the appropriate solution according
to his experience or resort to further methods of detailed analysis
(e.g. FEM analysis), with the advantage of applying time consuming
numerical investigations only to a small number of cases suggested by
the intelligent computing system. Neural network training and testing
allowed to verify the system performance in classifying working sequence
feasibility and its computational speed in providing technologically
acceptable working sequences for process planner consideration.
|
|
Experiments and computational modelling of metal injection molding for forming small parts
|
|
J.-C. Gelin (1), T. Barriere, M. Dutilly
|
|
STC F, 48/1/1999, P.179
|
|
Keywords: Powder injection molding, Finite element method, Simulation |
Abstract : The metal injection molding process is mainly used for manufacturing
small metallic components with complex shapes. The process includes four
stages and the present study is concentrated on the injection and the
densification ones. A multiple cavities mold has been designed and
realized that permits to characterize the effects of injection
parameters on the final results in terms of shape and integrity. A
mechanical model and a set of numerical simulations have been carried
out that enhance the experimental results and that allow to access to
the influence of the main process parameters. Finally it is shown that
computational modeling could be used to help the process designer to
produce accurate parts.
|
|
Material response to continuously varying rate of straining during hot forging operations
|
|
P.F. Bariani (1), T. Dal Negro
|
|
STC F, 48/1/1999, P.183
|
|
Keywords: Hot forging, Strain rate, Flow stress |
Abstract : The analysis of hot bulk forming operations reveals that strain rate and
temperature at the different material points often vary in a wide range
during deformation.
The effects on material rheology of continuous variations of process
parameters are investigated through physical simulation experiments.
They accurately reproduce on steel samples the mechanical and thermal
events occurring during representative forging operations.
The material response exhibited by the material under varying process
conditions is compared with that derived from conventional
constant-strain-rate and iso-thermal tests as well as with the flow
stress calculated by FEM. The discrepancies demonstrate the inadequacy
of conventional flowstress equations.
|
|
Computer simulation and control of microstructure and mechanical properties in hot forging
|
|
Z. Wang, T. Ishikawa, N. Yukawa, A. Kono, Y. Tozawa (1)
|
|
STC F, 48/1/1999, P.187
|
|
Keywords: Hot forging, Property prediction, FEM |
Abstract : An analytical procedure for predicting the microstructure and mechanical
properties of forged microalloyed steels is presented. Empirical
relationships between recrystallized grain size, temperature and strain
as well as the relationship between austenite grain size and ferrite
grain size are obtained. These relations are expressed as an incremental
formula and incorporated into thermo-coupled FEM code. By applying this
analysis to practical multiple stage hot forging of range companions or
automotive parts made of microalloyed steel, the microstructure and
hardness of forged parts can be predicted. The results of these
predictions are in good agreement with the experimental results. The
simulation is used to investigate the thermo-mechanical processes for
forging functional parts with partially fine grain and high hardness.
|
|
Microstructure and mechanics interaction in the modelling of hot rolling of rods
|
|
P. Pauskar, R. Shivpuri (2)
|
|
STC F, 48/1/1999, P.191
|
|
Keywords: Hot rolling, Flow stress, Microstructure |
Abstract : During hot metal working, strain, strain rate, temperature,
microstructure and chemistry along with associated metallurgical
phenomena such as strain hardening, dynamic recovery and
recrystallization are known to have a significant effect on the flow
stress of the metal. Simple flow stress models such as the power law
were found to be inadequate for the accurate prediction of !cads and
metal flow using numerical simulation. In this study, a microstructure
dependent flow stress model was developed by performing uniaxial
compression tests on the Gleeble test machine. This model was
implemented, using a computationally efficient procedure, into the
finite element method based metal flow simulation model for hot rolling.
Reasonably good agreements were obtained in comparing predicted roiling
loads and rod geometry with those measured on a multi-pass production mill.
|
|
Application of a decision making method to improve an industrial hot extrusion forging process
|
|
A. Barcellona, L. Cannizzaro (2), D. Antonelli
|
|
STC F, 48/1/1999, P.195
|
|
Keywords: Hot forging, FEM, Sensitivity analysis |
Abstract : Success of a bulk forming process is significantly affected by several
operative parameters, such as dies and workpiece temperature, friction
factor, preformed dimensions and its initial positioning. In the paper
the hot extrusion forging of an half shaft of a two stroke motorcycle
engine has been investigated. The combined effect of the most influent
operative parameters has been determined by means of a consistent
factorial plan. A sensitivity analysis was performed using an advanced
numerical finite element code as a powerful CAE tool able to assist the
analyst in the design of the process. The geometry of the part has
allowed a combined 2D-3D numerical analysis; in fact, the influence of
some parameters has required a full 3D analysis very expensive in terms
of numerical computations.
|
|
Linear motor drive CNC press using learning control
|
|
T. Nakagawa (1), T. Higuchi, R. Sato, M. Sogabe
|
|
STC F, 48/1/1999, P.199
|
|
Keywords: Metal stamping, CNC, Noise reduction |
Abstract : A mechanical press drivers directly by a linear motor, which is mainly
used for feeding machine tool tables, has been developed for the first
time and its performance in blanking and sheet metal forming confirmed.
By incorporating a learning control system, a very high accuracy level
(±54m) of the bottom dead point can be achieved in blanking operations.
Other advantages such as CNC ram stroke motion control and very low
noise level in blanking were also confirmed. Interesting applications of
the linear motor can also be looked forward in pressuring devices.
|
|
A basic study of the influence of surface topography on mechanisms of liquid lubrication in metal forming
|
|
C.G. Sorensen, J.I. Bech, J.L. Andreasen, N. Bay (1), U. Engel, T. Neudecker
|
|
STC F, 48/1/1999, P.203
|
|
Keywords: Lubrication mechanisms, Metal forming, Surface topography |
Abstract : Applying a transparent tool technique the tool/workpiece interface in
plane strip drawing of aluminium is studied. The strips are provided
with macroscopic lubricant pockets, and the compression and eventual
escape of trapped lubricant by the mechanisms Micro Plasto HydroDynamic
Lubrication (MPHDL) and Micro Plasto HydroStatic Lubrication (MPHSL) is
observed and quantified experimentally with respect to the lubricant
pocket parameters, shape, volume, and angle to the edge. The two
mechanisms have proved to depend very differently upon these parameters.
The level at which the hydrostatic pressure is stabilised is shown to be
independent of the volume of a pocket and the MPHDL mechanism is
therefore solely dependent on the angle to the edge, which is shown both
experimentally and theoretically by a fluid mechanic analysis. For the
MPHSL mechanism a dependency of the volume is observed.
|
|
Formability of non-symmetric aluminum panel drawing using active drawbeads
|
|
R. Li, K.J. Weinmann (1)
|
|
STC F, 48/1/1999, P.209
|
|
Keywords: Aluminum Sheet, Drawbeads, Formability |
Abstract : Aluminum is expected to gain popularity as material for the bodies of
the next generation of lighter and more fuel-efficient vehicles.
However, its lower formability compared with that of steel tends to
create considerable problems. A controllable restraining force caused by
adjusting the penetration of drawbeads can improve the formability of
aluminum. The paper describes a spatial and temporal FE model for the
analysis of this technique, especially in non-symmetric panel forming.
Comparison of the results of numerical simulations with the
corresponding experimental results shows that the predictions of strain
distribution on the panel are in excellent agreement. Furthermore, FLD
analysis indicates that the active drawbead concept is beneficial to the
formability of AI 6111-T4.
|
|
Rotary blanking
|
|
H. Hoffmann, M. Schweitzer / J. Milberg (1)
|
|
STC F, 48/1/1999, P.213
|
|
Keywords: Blanking, Rotary, Kinematic |
Abstract : Rotary blanking is a method of blanking and punching with rotating tools
whereby the cutting tools are fixed to a pair of rollers performing a
continuous blanking operation on a strip of sheet metal. The purpose of
this paper is to outline the determining conditions under which the
rotary blanking process takes place and to discuss advantages,
restrictions, applications and optimization of this technology.
|
|
New possibilities for improved bending of vibration damping laminated steel sheets
|
|
M. Kleiner (2), V. Hellinger
|
|
STC F, 48/1/1999, P.217
|
|
Keywords: Bending, Vibration damping sheets, Springback |
Abstract : Bending of vibration damping laminated sheet metal has been presenting
serious difficulties arising from time dependent material springback,
undesired deformation of the long bending legs, and separation of the
steel sheets. New methods of improving the bending behaviour of steel
sheets have been established as a consequence from experiments and
investigations on the viscoelastic-plastic core layer of composites.
Considerable improvement will be obtained by the selective use of
temperature fields in connection with heated bending tools. A following
heat treatment will significantly reduce the delayed springback time
which has been up to two weeks at room temperature so far.
|
|
A method for deep drawing with multiple elastomer membranes
|
|
F. Vollertsen, R. Breede, K. Lange (1)
|
|
STC F, 48/1/1999, P.221
|
|
Keywords: Deep drawing, Flexible tooling, Tribology |
Abstract : A deep drawing technique is introduced where sheet metal is formed
between a rigid punch and a flexible tool component made of multiple
elastomer membranes. For this process the punch force is determined,
using a fundamental analytical model. During the drawing process a
relative movement and therefore friction forces between the membranes
and the sheet metal are assumed. These effects were investigated in
special strip drawing tests. The results are used in FEM-calculations to
determine the membrane deformation caused by friction and to simulate
the drawing process of a cylindrical part. Furthermore, a comparison
between deep drawing methods with a single membrane and using multiple
membranes is described, using a model for the membrane deformation.
|
|
Determination of the forming limit diagrams using image analysis by the corelation method
|
|
P. Vacher, A. Haddad, R. Arrieux (2)
|
|
STC F, 48/1/1999, P.227
|
|
Keywords: Strain measurement, Image analysis, Forming limit diagrams |
Abstract : This paper deals with a new method of strain measurement applied to the
experimental determination of the forming limit diagrams of thin steel
sheets. This method uses the correlation technique to determine the
displacement field between two images taken on the same area of the
sample at two different strain levels.
The strains are calculated from this field. The range of strains
determined between two images may be very wide. This allows to compare
the initial image to one before the sample fracture or two successive
images during the straining. This method shows that the strain
localization may occur early during the forming process and so the onset
of localized necking is not a sudden phenomenon. A method is proposed to
draw the forming limit diagrams for necking.
|
|
Optimal blankholder force path in sheet metal forming processes : an AI based design procedure
|
|
R. Di Lorenzo, L. Fratini, F. Micari (2)
|
|
STC F, 48/1/1999, P.231
|
|
Keywords: Deep drawing, Process design, Optimization |
Abstract : Blankholder force plays a fundamental role in the deep drawing process
mechanics since it controls, by friction, the material flow into the die
cavity. The availability of computer controlled hydraulic presses in the
industries promoted a new research field focused on the definition of
optimal BHF histories, function of the punch displacement; such studies
were aimed to the determination of the so called "process window", i.e.
the BHF path which permits to obtain the maximum height sound component
avoiding both wrinkling and tearing. In the paper a design procedure is
proposed in order to determine the optimal BHF path in an axisymmetric
deep drawing process: in particular, a closed-loop control system based
on the fuzzy reasoning has been set up and interfaced with a FEM code.
The determined BHF path has been experimentally verified assessing the
effectiveness of the proposed approach.
|
|
Analysis tool for roll forming of sheet metal strips by the finite element method
|
|
N. Kim, S.I. Oh (1)
|
|
STC F, 48/1/1999, P.235
|
|
Keywords: Roll forming, Computer simulation, Finite element method |
Abstract : A computational method based on the three-dimensional finite element
method is developed for the deformation analysis of roll forming
process. The method approximates the process as a kinematically steady
state deformation of strip. For industrial usefulness of the simulation
method, several rolls with arbitrary shapes in one stand can be
considered. The shapes and the thickness distributions of strip after
roll forming were examined by comparing computation results with
experiments. It is concluded that the tool is useful enough to predict
the process. The overall simulation method was integrated into a
software package to help the industrial roll-pass design.
|
|
Net shape approach for sintering process of graded laminated powder materials using finite element simulation
|
|
K.I. Mori, K. Osakada (1)
|
|
STC F, 48/1/1999, P.239
|
|
Keywords: Sintering, Near net shape, FEM |
Abstract : A net shape approach for sintering of graded laminated powder compacts
using finite element simulation is proposed. This approach is composed
of shape optimisation and fracture prediction in the sintering. In the
shape optimisation, the geometry of the compact for producing a flat one
of the sintered product is determined using the finite element
simulation in order to minimise the difference from the flat shape. On
the other hand, the occurrence of sintering fracture is predicted from a
difference in volumetric strain between non-uniform and uniform
shrinkages calculated by the simulation. The difference in volumetric
strain represents average hydrostatic stress during the sintering. For
the simulation of the sintering process, a viscoplastic finite element
method calculating viscoplastic deformation generated by the difference
of shrinkage is employed. The predicted shapes of the compacts are
available to actual sintering operations. The effectiveness of the
present approach is demonstrated in sintering of circular graded
compacts consisting of zirconia and alumina powders.
|
STC G |
|
Surface grinding machine with linear-motor-driven table system : development and performance test
|
|
I. Inasaki (1)
|
|
STC G, 48/1/1999, P.243
|
|
Keywords: Grinding, Linear motor, Speed-stroke grinding |
Abstract : In order to fully exploit the advantages of speed-stroke surface
grinding characterized by high workpiece speed with small depth of cut,
a grinding machine with a linear-motor-driven table system was
developed. The maximum table speed and acceleration achieved were 60
m/min and 1,0 G, respectively. The paper describes the results of a
performance test of the machine during the idling phase and a
speed-stroke grinding test. These tests confirmed that the developed
surface grinding machine was able to meet the intended design
specification in terms of grinding force and ground surface quality.
|
|
Temperatures and energy partition for grinding with vitrified CBN wheels
|
|
C. Guo, Y. Wu, V. Varghese, S. Malkin (1)
|
|
STC G, 48/1/1999, P.247
|
|
Keywords: Grinding, Cubic boron nitride (CBN), Temperature |
Abstract : An investigation is reported of the temperatures and energy partition
for grinding with vitrified CBN wheels. Temperature distributions were
measured in the subsurface of hardened bearing steel workpieces using an
embedded thermocouple during grinding with a water soluble fluid at
specific removal rates from 5 to 60 mm 2/s. The energy partition to the
workpiece and heat flux distribution within the grinding zone were
estimated using temperature matching and inverse heat transfer analyses.
In all cases, the maximum grinding zone temperature rise was less than
120°C. The energy partition to the workpiece was found to be only 4.0 to
8.5%37;. Such low energy partitions are consistent with a thermal model
which takes into account conduction to the workpiece, conduction to the
abrasive grains, and cooling of the workpiece by the fluid at the
grinding zone.
|
|
Model of grinding thermal damage for precision gear materials
|
|
J.E. Mayer, Jr (2), G. Purushothaman, S. Gopalakrishnan
|
|
STC G, 48/1/1999, P.251
|
|
Keywords: Grinding, Thermal damage, Gear steels |
Abstract : Thermal damage, specifcally burn, in carburized and hardened precision
gear steels caused by grinding was investigated. Excessive grinding
temperatures cause grinding burn and result in excessive scrappage. AISI
9310 and X53 gear steels, used in helicopters and tilt-rotor aircraft,
respectively, were prepared and heat-treated by a production partner.
Grinding tests were conducted on these steels. Nital etching was used to
detect grinding burn. Models were established to predict onset of
thermal damage for AISI 9310 and X53 steels based on specific grinding
energy determined from grinding force measurements. The models were
compared to results published for other steels.
|
|
Grind-hardening: a comprehensive view
|
|
T. Brockhoff / E. Brinksmeier (1)
|
|
STC G, 48/1/1999, P.255
|
|
Keywords: Grinding, Surface hardening, Hardness penetration depth |
Abstract : The invention of advanced grinding processes enabling the surface
hardening of steel parts was described for the first time in 1994 [1].
In such operations, named grind-hardening the dissipated heat in
grinding is utilized to induce martensitic phase transformations in the
surface layer of components. A grinding process then becomes a heat
treatment operation like induction or flame hardening. The fundamentals
of this new process, which had been developed up to first industrial
applications, will be illustrated in this paper. Especially the impact
of different grinding parameters on the structure and the achievable
hardness penetration depth are discussed in detail.
|
|
Optimization of the dynamic behavior of grinding wheels for grinding of hard and brittle materials using the finite element method
|
|
G. Warnecke (2), C. Barth
|
|
STC G, 48/1/1999, P.261
|
|
Keywords: Grinding wheel, Dynamic property, Finite element method |
Abstract : In grinding of hard and brittle materials such as advanced ceramics or
hard metal, process behavior and work result are closely connected with
material removal mechanisms. Material removal mechanisms are determined
by complex interactions between material properties, geometry of the
grits, the kinematics of grit engagements and the mechanical and thermal
.loads acting on workpiece and tool due to energy transformation in the
grinding process. Experimental investigations of surface grinding
processes show that material removal mechanisms are also influenced by
dynamic conditions in the contact zone. These dynamic conditions, that
are not chatter vibrations, can have both a positive and negative
influence on surface quality, process forces and wear of the grinding
wheel. For a given machine tool and workpiece the dynamic contact zone
conditions can be optimized by the dynamic properties of the hub of the
grinding wheel. For analyzing the dynamic contact zone conditions based
on the behavior of the grinding wheel the finite element method is used.
By means of these analyses the dynamic properties of grinding wheels can
be adapted to meet the requirements of a determined grinding process
with regard to tool wear, surface roughness of the workpiece and process
forces.
|
|
ECD (Electrochemical in-process Controlled Dressing), a new method for grinding of modern high-performance cutting materials to highest quality
|
|
D. Kramer, F. Rehsteiner (1) / B. Schumacher (1)
|
|
STC G, 48/1/1999, P.265
|
|
Keywords: Grinding, In-process dressing, Electrochemical dressing |
Abstract : The steadily increasing demand for cutting tools with high wear
resistance coupled with an adequate toughness has led to the development
of new cutting materials that are extremely difficult to machine by
conventional grinding techniques: Cermets, Ceramics, PcBN, PCD. A new
method of in-process dressing of metal bonded diamond grinding tools by
a controlled electrochemical process, called ECD, opens up completely
new ways.of grinding these materials. As a result not only the quality
of the ground pieces is strongly improved but also an economical
application of multi-layered, metal bonded diamond grinding wheels to
the machining of modern cutting materials is achieved, which would be
impossible otherwise. This new method has been applied successfully on
an actual insert grinding machine.
|
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Vacuum-preloaded hydrostatic shoe for centerless grinding
|
|
Y. Yang, B. Zhang (2), J. Wang
|
|
STC G, 48/1/1999, P.269
|
|
Keywords: Centerless grinding, Hydrostatic shoe, Out-of-roundness error |
Abstract : An innovative workpiece support, vacuum-preloaded hydrostatic shoe, is
developed for lobing and chatter suppression in centerless grinding. The
hydrostatic shoe applies vacuum-preloading to a hydrostatic bearing so
as to provide a workpiece support of non-contact, good damping and high
stiffness. The paper presents stability analysis and simulation results
to demonstrate the effectiveness of the hydrostatic shoe in lobing and
chatter control. Grinding experiments are conducted on bearing raceways
to confirm the simulation results. The hydrostatic shoe is demonstrated
to be superior to conventional contact shoes. Under the same grinding
conditions, the hydrostatic shoe results in 42%37; less out-of-roundness
error over the conventional shoes.
|
|
Development of a resinoid diamond wire containing metal powder for slicing a silicon ingot
|
|
T. Enomoto, Y. Shimazaki, Y. Tani (2), M. Suzuki, Y. Kanda
|
|
STC G, 48/1/1999, P.273
|
|
Keywords: Wire sawing, Silicon grinding, Metal powder |
Abstract : Loose-abrasive wire sawing widely employed for slicing silicon ingots
has problems of dirty working environment and inefficiency.
Fixed-abrasive wires, namely electroplated diamond wires and resinoid
diamond wires, have been developed to overcome these problems. Resinoid
diamond wires, which can be produced at a lower cost, can be put to
practical use, but they have a low breaking twist strength. In this
study, metal powder is added to the resinoid bond to strengthen it. A
series of experiments revealed that the breaking twist strength, heat
resistance, tool wear resistance, and slicing efficiency of this wire
are significantly improved.
|
|
Ultraprecision surface grinding of chemical vapor deposited silicon carbide for X-ray mirrors using resinoid-bonded diamond wheels
|
|
Y. Namba, H. Kobayashi, H. Suzuki, K. Yamashita / N. Taniguchi (1)
|
|
STC G, 48/1/1999, P.277
|
|
Keywords: Ultra-precision surface grinding, X-ray mirror, Silicon carbide |
Abstract : Chemical Vapor Deposited Silicon Carbide (CVD-SiC) on sintered silicon
carbide has been ground by the ultraprecision surface grinder having a
glass-ceramic spindle of extremely-iew thermal expansion with various
cup-type resinoid-bonded diamond wheels for getting high-brightness
synchrotron radiation mirrors. The surface roughness depends upon the
average grain size of a wheel, feed per wheel revolution and degree of
cutting edge wear. A very smooth surface of 0.266nm rms was obtained by
ultraprecision grinding without polishing. A high specular reflectivity
of 88.7°io at 0.834nm in wavelength was obtained on the ground surface
at the grazing incident angle of 0.7-0.95 degree, parallel to the
grinding direction.
|
|
Influence of kinematics on the face grinding process on lapping machines
|
|
E. Uhlmann, T. Ardelt / G. Spur (1)
|
|
STC G, 48/1/1999, P.281
|
|
Keywords: Grinding, Lapping machine, Ceramics |
Abstract : The substitution of many lapping processes by face grinding on lapping
machines offers a new field of application for the kinematic model of
relative motions in lapping. The selection of path types and velocities
between parts and grinding wheels does not, as in lapping, primarily
serve to avoid the profile wear of the wheels. Rather, the process
development and thus, the part quality are directly influenced. Ceramic
parts are used as an example to illustrate the improvement in
performance made possible by the analysis of machining kinematics.
|
|
Warp in high precision cutt-off grinding of Al2O3-TiC ceramic thin plate
|
|
Y. Ohbuchi, T. Matsuo (1), N. Ueda
|
|
STC G, 48/1/1999, P.285
|
|
Keywords: Grinding, Abrasive cut-off, Quality assurance |
Abstract : High precision cut-off grinding has been carried out on A1_2 0_3 -TiC
ceramic thin plates with metal bond thin diamond wheels. The warp of the
cut-part as well as the flatness of work surface, i.e, deflection of
wheel, was precisely measured and thus, the warp generation mechanism
was analyzed and the optimum slicing condition was investigated.
Grinding forces were measured for discussing the warp. Also, the effect
of V-shaped guide groove for depressing the deflection was studied. It
is evident that the warp of workpiece and the wheel deflection largely
depend on grinding type and pre-processing conditions. The high feed
cut-off grinding is most effective for restraining the deflection, and
the use of a V-shaped groove is a useful way to depress the deflection.
|
STC M |
|
Nanometer positioning of a linear motor-driven ultraprecision aerostatic table system with electrorheological fluid dampers
|
|
H. Shinno, H. Hashizume / H. Sato (1)
|
|
STC M, 48/1/1999, P.289
|
|
Keywords: Nanotechnology, Ultra-precision machine, Nano-positioning |
Abstract : With the ever increasing demand for higher accuracy and higher
productivity in the world-wide manufacturing environment, ultraprecision
table positioning technology is urgently required. In order to establish
an ultraprecision technology of nanometer accuracy capability, it is
important to develop ultraprecision table systems based on new design
concepts. In this study, therefore, a linear motor-driven ultraprecision
aerostatic table system equipped with electrorheological fluid dampers
is described, with proven nanometer positioning accuracy.
|
|
The effect of drawbar force on metal removal rate in milling
|
|
S. Smith (2), T.P. Jacobs, J. Halley
|
|
STC M, 48/1/1999, P.293
|
|
Keywords: Milling, Metal removal rate, Dynamic stiffness |
Abstract : The metal removal rate in milling is often limited by the tool-spindle
dynamics. Higher stiffness and damping as seen at the tool tip allow
higher metal removal rates. While increasing the drawbar force leads to
greater static stiffness in the tool-spindle interface, dynamic
measurements indicate that higher drawbar forces also diminish the
damping. Whether higher drawbar force is beneficial for stable metal
removal depends on whether the gain in stiffness is greater than the
loss in damping. This paper presents test-stand measurements of
stiffness and damping for tool holder - spindle interfaces at various
drawbar forces, and similar measurements in spindles.
|
|
Spindle and toolsystems with high damping
|
|
M. Weck (1), N. Hennes, M. Krell
|
|
STC M, 48/1/1999, P.297
|
|
Keywords: Metal cutting, Chatter vibration, Damping system |
Abstract : Today's machine tool spindles are generally designed in rolling bearings
to achieve high rotational speeds. However, the damping capacity of
these elements is much lower than that of hydrostatic or hydrodynamic
bearings. Low system damping quite often causes chatter vibrations
during the metal cutting process. The use of tools with a long overhang
often leads to dynamic instability.
Placing the rolling bearings in a hydrostatic arrangement promises an
increase of damping with unchanged capability of high rotational speed.
By the use of passive damping elements, integrated in the tool holding
fixture, the dynamic behaviour of the spindle / tool system can be
optimized. Material substitution as well as geometric shape optimization
leads to increased dynamic stability of boring bars.
|
|
Advantages and characteristics of a dynamic feed axis with ball screw drive and driven nut
|
|
H. Weule (1), T. Frank
|
|
STC M, 48/1/1999, P.303
|
|
Keywords: Feed-drive, Optimization, Machine tools |
Abstract : This paper describes the advantages and characteristics of a Dynamic
feed axis with bail screw drive and driven nut in comparison with the
conventional electromechanical drive. In contrast to the classical drive
the ball screw leadscrew is rigidly located at both ends and the nut is
driven by a servomotor. The investigation considers two drive variants:
the indirect drive with a standard servomotor driving the nut via a
toothed belt and the direct drive with a hollow shaft servomotor. The
feed system developed at the Institute for Machine Tools and Production
Science at the University (TH) of Karlsruhe opens up new prospects for
the development of new dynamic machine generations with traverse speed
up to 120 m/min and acceleration up to 45 m/s . In addition to the high
acceleration and traverse speed, the development program also has the
objective of optimised transmission behaviour of the feed kinematic
system with positional control. The design features and operating
characteristics achieved with the innovative test device are described.
|
|
A self-tuning controller for digitally controlled electromechanical servo drives in machine tools
|
|
G. Pritschow (1), J. Bretschneider
|
|
STC M, 48/1/1999, P.307
|
|
Keywords: Control design, Drive, Machine Tool |
Abstract : The authors present a new paradigm for a self-tuning controller applied
to servo-drives in machine tools. To facilitate controller tuning,
measured data from the drive instead of a dynamic model are utilised.
Using a set of user-defined dynamic performance criteria, a numerical
optimisation process tunes the controller parameters. The conventional
procedure of successive optimisation of the cascade controller from the
inner to the outer loop is deliberately avoided, thus allowing all
variable controller parameters to be simultaneously tuned. Thus this
self-tuning concept can be applied to a wide variety of servo-control
paradigms. This paper presents the results achieved in practice with
this self-tuning controller strategy.
|
|
Design of a precision, agile line boring station
|
|
Y. Koren (1), Z.J. Pasek, p. Szuba
|
|
STC M, 48/1/1999, P.313
|
|
Keywords: Machine Tool, Cutting, Control |
Abstract : This paper describes a new agile line boring station for machining of
long bores in automotive applications, e.g. crank and camshaft bores in
engine blocks. The machine includes a "smart" lire boring tool with an
on-line compensation mechanism, relying on sensing and intelligence
built into the tool itself, for real-time correction of the boring
process. To supplement the advantages provided by the "smart" tool, a
prototype agile line boring machine was developed as a joint effort
between the University of Michigan and Lamb Technicon, a machine tool
builder. The design integrates multiple new concepts of mechanical
structure of the machine with an intelligent controller.
|
|
Machinery fault diagnosis and prognosis: applications of advanced signal processing techniques
|
|
J. Suh, S.R.T. Kumara (1), S.P. Mysore
|
|
STC M, 48/1/1999, P.317
|
|
Keywords: Machine, Monitoring, Intelligent system |
Abstract : Machinery health prediction based on process models and/or process
parameters is an important function in automated manufacturing set-ups.
Sensor data is collected and used to indirectly model the equipment. Due
to the short response times required it is important to investigate
robust sensor data representation schemes. Traditional Fourier Analysis
is not sufficient to preserve the information in both frequency and time
domains. In this paper we describe the use of wavelets, both continuous
and discrete, for equipment diagnosis and prognosis. We detail
wavelet-based techniques for gear fault diagnosis and prognosis.
|
|
Dynamic influence on workpiece quality in high speed milling
|
|
U. Heisel (2), A. Feinauer
|
|
STC M, 48/1/1999, P.321
|
|
Keywords: High speed machining, Dynamic parameter, Workpiece quality |
Abstract : The high speed milling process places completely new demands on the
dynamic behaviour of machining centres. This paper describes the causes
of vibrations in high speed milling. It includes a quantification of
vibrations due to imbalances, accelerations and cutting forces. The
effects on the quality of workpieces are simulated by a dynamic model of
the machine. Therefore, also the mechanical structure and the axis
control system are taken into account. The results of the simulation are
verified by some cutting examinations. To improve the quality of
workpieces suggestions are made to avoid vibrations or to compensate the
effects on vibrations due to imbalance.
|
|
Experimental and computer aided analysis of high-speed spindle assembly behaviour
|
|
M. Zeljkovic, R. Gatalo / M. Kalajdzic (1)
|
|
STC M, 48/1/1999, P.325
|
|
Keywords: Machine Tool, Spindle, Experimentation |
Abstract : A methodology of experimental identification of machine tool spindle
assembly behaviour has been developed at the Institute for Production
Engineering in Novi Sad. The methodology allows analysis of the spindle
assembly in terms of static, dynamic and thermal behaviour. This
methodology is applied to high-speed machine tool spindle assembly
analysis. To increase reliability of experimental results, the
methodology is combined with computer aided modeling of static and
dynamic behaviour, using software packages based on the finite elements
method (I-DEAS, ALGOR, SAP-90, VRETENO). Special attention has been paid
to the influence of the used bearing arrangement on the spindle assembly
behaviour.
|
|
Development of an intelligent design system for embodiment design of machine tools
|
|
M-W. Park, J-H. Cha, J-H. Park, M. Kang (2)
|
|
STC M, 48/1/1999, P.329
|
|
Keywords: Design system, Machine Tool, Knowledge-based system |
Abstract : An intelligent software system which can support efficiently and
systematically machine tool design by utilizing design knowledge is
described in this paper. The process of embodiment design of a machining
center was modelled, represented by IDEFO, and embedded in the system. A
hybrid type inference engine has been introduced so that the system can
effectively deal with knowledge represented in diversified forms. The
design system was developed on the basis of object-oriented programming,
and has been coded into one software system which can be ported on
Windows NT.
|
|
Development and study of a new kind of 3-DOF tripod
|
|
G.Q. Cai (2), M. Hu, C. Guo, B. Li, Q.M. Wang
|
|
STC M, 48/1/1999, P.333
|
|
Keywords: Parallel machine tool, Kinematics, Dynamics |
Abstract : A novel 3-DOF parallel machine tool based on a tripod mechanism has been
developed and studied. The main aspects of its structure, kinematics,
workspace, parameter design, error analysis and force analysis are
introduced. Through theoretical analyses and operation tests, it shows
some distinctive advantages, such as high ratio of force-to-weight,
simple structure and simple kinematic equations, large workspace with no
kinematic coupling and no singularity configuration. The unique
performance of the tripod machine tool provides a high potential and a
very good prospect for its practical implementation in manufacturing
industry.
|
|
A new parallel mechanism machine tool capable of five-face machining
|
|
J. Kim, F.C. Park, J.M. Lee (1)
|
|
STC M, 48/1/1999, P.337
|
|
Keywords: Machine Tool, Parallel mechanism, Rapid machining |
Abstract : This paper introduces a new parallel mechanism machine tool that can
machine the top surface and four lateral surfaces of a prismatic
workpiece with one setup. No B-axis motion is necessary. Five-axis
simultaneous machining can be executed in any workspace. This machine is
based on a new parallel mechanism, Eclipse, which was invented by the
authors. The Eclipse allows the spindle of the machine tool to tilt to
90 degrees from the vertical posture, and also to sweep the lateral
surfaces of the workpiece over 360 degrees. This paper presents the
overall structure, the detailed design aspects, and the performance
evaluation of the new parallel mechanism machine tool.
|
|
Closed-form resolution scheme of the direct kinematics of parallel link systems based on redundant sensory information
|
|
P.B. Petrovic, V.R. Milacic (1)
|
|
STC M, 48/1/1999, P.341
|
|
Keywords: Parallel kinematic structure, Kinematic transformation, |
Abstract : Non-numerical resolution
In this paper, the direct kinematics transformation in parallel link
systems, based on redundant sensing approach is addressed. The redundant
sensory information is provided by additional position sensors,
connected directly to the parallel structure in a parallel manner.
Optimization of position and the number of redundant sensors is
performed by a proposed Geometrical-Structure-Partitioning Method. The
efficiency of the method is verified by two examples - type 3-3 and 6-3
spatial structures, where only one redundant sensor is identified as
sufficient for unique closed-form solution of the direct kinematics problem.
|
|
Putting parallel kinematics machines (PKM) to productive work
|
|
F. Rehsteiner (1), R. Neugebauer, S. Spiewak (2), F. Wieland
|
|
STC M, 48/1/1999, P.345
|
|
Keywords: Parallel machines, Hexapod, Specification |
Abstract : It is embarrassing to observe that out of the rapidly growing number of
PKMs hardly any are doing productive work in industry while most of them
stay in University labs. The paper deals with two aspects of this
problem. First, the results of discussions with industrial partners,
both users and manufacturers, are presented. The main result is to
improve communication between developers and users. In the second part,
ways are suggested on how to convert these ideas into successful
products. The viability of this approach is demonstrated by the
successful cooperation between a PKM manufacturer and a potential user.
|
|
Fundamental comparison of the use of serial and parallel kinematics for machine tools
|
|
J. Tlusty (1), J. Ziegert, S. Ridgeway
|
|
STC M, 48/1/1999, P.351
|
|
Keywords: Hexapod, Machining, Stiffness |
Abstract : Classical cartesian kinematics Machining Center (MC) structures are
compared with parallel kinematics hexapods (HX) structures from the
point of view of workspace, stiffness, accuracy, acceleration ability,
and motion dynamics for use as high speed milling machines. Concrete
stiffness values are used as achievable. It is concluded that variable
strut length HX are fundamentally inferior to the MC and cannot
practically be used as high speed milling machines. The constant strut
length HX offer larger workspace and higher strut stiffness and may
produce characteristics comparable to MC in particular designs.
|
STC O |
|
Simulation based analysis of complex production systems with methods of nonlinear dynamics
|
|
H.P. Wiendahl (1), H. Scheffczyk
|
|
STC O, 48/1/1999, P.357
|
|
Keywords: Production process, Methods, Analysis |
Abstract : The most recent, and probably the most discussed approach in connection
with systems complexity, has been the attempt to apply the results of
chaos research to production systems. But the question concerning the
amount and quality of data necessary to analyze manufacturing systems
with methods of non-linear dynamics is still to be answered. To get
further knowledge in analyzing data from manufacturing systems with
methods of nonlinear dynamics, simulation experiments are made. The
interaction and evolution of dynamic system parameters are visualized in
a phase space. Although human imagination is restricted to three
dimensions, it is possible to analyze higher dimensional phase spaces by
modern computation. The aim is to discover laws which describe the
behavior of the system as a whole.
|
|
A petri net technique for batch delivery time estimation
|
|
P. Xirouchakis, D. Kiritsis, C. Gunther, J.-G. Persson (2)
|
|
STC O, 48/1/1999, P.361
|
|
Keywords: CAPP, Cost, Petri net |
Abstract : The problem under consideration is delivery time and cost estimation in
batch manufacturing of mechanical parts. We consider non-linear process
planning with explicit resource modeling. We present a two-level Petri
net class which are high level nets extended with time that allow the
interleaving of transitions. They consist of a system net modeling the
job shop layout (including the machines) and token nets modeling the
jobs and setups. We calculate the optimum delivery time and associated
cost of a batch of one type of mechanical workpiece together with the
associated resources.
|
|
Object-oriented design of a modular scheduling architecture
|
|
P. Brandimarte / R. Levi (1)
|
|
STC O, 48/1/1999, P.365
|
|
Keywords: Production scheduling, Object-oriented programming, Conceptual modelling |
Abstract : The importance of finite-capacity schedulers is increasing, with respect
to the widespread MRP packages, due to their ability to model the shop
floor more accurately. However, this very advantage may turn into a
disadvantage, since it is quite difficult to devise a high-quality
general purpose scheduler able to cope with the technological
peculiarities of different production environments. Furthermore, a
detailed schedule is prone to disruptions due to the uncertainty
affecting the shop floor. Hence, we need both a modular approach to
devise and assemble local schedulers and a way to link predictive and
real time scheduling. To cope with both requirements, we propose a
scheduling approach based on a generalization of the well-known shifting
bottleneck method. The scheme is based on the coordination of local
schedulers by a general scheme, such that the knowledge needed to cope
with technological peculiarities is locally confined. The aim of the
coordination mechanism is to generate a set of local due dates .which
can be used as targets to drive real time dispatching.
|
|
A genetic algorithm based approach for scheduling of dual-resource constrainded manufacturing systems
|
|
H. ElMaraghy (1), V. Patel, I.B. Abdallah
|
|
STC O, 48/1/1999, P.369
|
|
Keywords: Scheduling, Manufacturing systems, Genetic algorithms |
Abstract : This paper presents a scheduling approach, based on Genetic Algorithms
(GA), developed to address the scheduling problem in manufacturing
systems constrained by both machines and workers. The GA algorithm
utilizes a new chromosome representation, which takes into account
machine and worker assignments to jobs. A study was conducted, using the
proposed scheduling method, to compare the performance of six
dispatching rules with respect to eight performance measures for two
different shop characteristics, i) dual-resources (machines and workers)
constrained shop and ii) single-resource constrained shop (machines
only). An example is used for illustration. The results indicate that
the dispatching rule which works best for a single-resource constrained
shop is not necessarily the best rule for a dual-resources constrained
system. Furthermore, it is shown that the most suitable dispatching rule
depends on the selected performance criteria and the characteristics of
the manufacturing system.
|
|
Architectural design of neural network hardware for job shop scheduling
|
|
P. B. Luh, X. Zhao, L.S. Thakur, K.-H. Chen, T.-D. Chiueh, S.-C. Chang / J.M. Shyu (1)
|
|
STC O, 48/1/1999, P.373
|
|
Keywords: Job shop scheduling, Neural network, Hardware design |
Abstract : By combining neural network optimization ideas with "Lagrangian
relaxation" for constraint handling, a novel Lagrangian relaxation
neural network (LRNN) has recently been developed for job shop
scheduling. This paper is to explore architectural design issues for the
hardware implementation of such neural networks. A digital circuitry
with a micro-controller and an optimization chip is designed, where a
parallel architecture and a pipeline architecture are explored for the
optimization chip. Simulation results show that the LRNN hardware will
provide near-optimal solutions for practical job shop scheduling
problems. It is estimated that the parallel architecture will obtain one
order of magnitude speed gain, and the pipeline architecture will obtain
two orders speed gain as compared with the currently used method.
|
|
An emergent synthetic approach to supply networks
|
|
K. Ueda (1), J. Vaario, T. Takeshita, I. Hatono
|
|
STC O, 48/1/1999, P.377
|
|
Keywords: Manufacturing, Synthesis, Interactive system simulation |
Abstract : To deal with complex supply networks a new approach based on emergent
synthesis is proposed. The approach is demonstrated and studied under
simulation. The simulation model consists of customer, dealer, producer,
supplier, and product elements. The emergence of products and supply
networks by the customers' preference can be observed as a global
behavior resulting from the local interactions between these elements.
The possibility to experiment with various management strategies by
interactive functions of the simulator is also discussed. The user can
carry out several scenarios and observe whether the product succeeds on
the market and how the supply networks change.
|
|
A reference scenario for IMS strategic design
|
|
G. Perrone, S. Noto La Diega (1)
|
|
STC O, 48/1/1999, P.381
|
|
Keywords: IMS design, Programming models, Genetic algorithms |
Abstract : Today is fully acknowledged that manufacturing is a formidable
competitive weapon. The strength of such a weapon is essentially defined
during the first step of the design phase called strategic design.
During this phase, in fact, the principal characteristics of the
manufacturing systems are to be defined taking into account the
competitive environment and the competition strategy. Classical
analytical models for IMS design often neglect this aspect and, perhaps,
this is one of the causes of IMS failure. The paper proposes a set of
analytical models for strategic IMS design; they have been classified
into four classes, each one pursuing a determined set of objectives,
providing, in this way, a general reference framework for IMS designers.
|
|
Information management in process planning
|
|
D. Lutters, T.C. Wijnker, H.J.J. Kals (1)
|
|
STC O, 48/1/1999, P.385
|
|
Keywords: Information management, Integration, Design and process planning |
Abstract : A recently proposed reference model indicates the use of structured
information as the basis for the control of design and manufacturing
processes. The model is used as a basis to describe the integration of
design and process planning. A differentiation is made between macro-
and micro process planning.
Macro process planning employs production method knowledge and context
information to evaluate candidate production methods. Decisions in this
respect are already relevant in the design stage. In working in the
opposite direction, method knowledge can be applied to generate geometry
and to supply material information. This enables both the completion of
abstract features and the selection of production methods for the less
functional, roughly defined parts of a product, ultimately resulting in
a fully specified design. This approach is primarily based on
Information Management.
|
|
Maintenance data management system
|
|
S. Takata (2), Y. Inoue, T. Kohda, H. Hiraoka, H. Asama
|
|
STC O, 48/1/1999, P.389
|
|
Keywords: Maintenance data management, Failure analysis, Knowledge based system |
Abstract : For the effective management of manufacturing facilities throughout
their life cycle, it is important to collect maintenance data and make
use of them for operation and maintenance planning or design of new
machines. However, it is seldom that the maintenance data are properly
recorded and utilized in a systematic way. To solve these problems, we
have proposed a maintenance data management system. In this paper, two
major modules of the system are discussed. The first one is a
malfunction data collection system which can navigate users to input
malfunction cases in a proper format. The second one is a feedback data
generation system which induces common causes implied in the malfunction
cases by means of the attribute-oriented induction algorithm. An
experimental system is applied to malfunction cases of machine tools for
demonstrating its effectiveness.
|
|
Life cycle design - a route to the sustainable industrial culture ?
|
|
M. Hauschild, H. Wenzel, L. Alting (1)
|
|
STC O, 48/1/1999, P.393
|
|
Keywords: Life cycle design, Environmental performance, Sustainable industrial culture |
Abstract : In the attempt to reorient Society's development in a more sustainable
direction attention is focused on the environmental impact of products
and systems over their entire life cycle, but how can the environmental
life cycle perspective be introduced into the design of new solutions
and how much can be obtained through life cycle design? The authors'
experience with integration of environmental considerations in product
development is presented, ranging from the detailed interactive approach
of the EDIP-method through various simplified approaches. The potential
for environmental improvements is reviewed and the overall question of
to what extent life cycle design is a route to the sustainable
industrial culture is discussed.
|
|
Variation modelling for a sheet stretch forming manufacturing system
|
|
R. Suri, K. Otto / G. Boothroyd (1)
|
|
STC O, 48/1/1999, P.397
|
|
Keywords: Stretch forming, Variation, Modelling |
Abstract : A system-level model of variation propagation in a sheet stretch forming
manufacturing system is developed and explored. The system model is
composed of sub-models of heat treatment. including quenching and
natural aging, and stretch forming. Both the nominal and variation
predictions of the model are compared to measured production data.
Factors in the system which are most sensitive to variation are
identified, and a variation reduction strategy is discussed. This
strategy lead to a 30°i; reduction in part strain variation on the
factory floor.
|
|
Aggregate product and process modelling for the welding of complex fabrications
|
|
P.G. Maropoulos / J. Crookall (1)
|
|
STC O, 48/1/1999, P.401
|
|
Keywords: Process planning, Design manufacturing integration, Welding |
Abstract : The integration of design with manufacturing planning has been the
subject of numerous investigations over the past two decades. Whilst a
lot has been achieved, most of the research relates to the detailed
design stages. Of primary importance are the early design stages when
there is a plethora of options available for product configuration and
manufacturing process selection. This paper describes the aggregate
product and process modelling methods which are developed to facilitate
the integration of early design stages with process planning. The
application of aggregate methods for complex fabrications is described
together with results from testing using industrial data.
|
|
Algorithms for the design verification and automatic process planning for bent sheet metal parts
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J. Duflou, J.P. Kruth (1), D. Van Oudheusden
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STC O, 48/1/1999, P.405
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Keywords: CAPP, Sheet metal, Bending |
Abstract : Sheet metal bending processes require detailed process planning in order
to eliminate infeasible set-ups or avoidable ergonomically demanding
manipulation requirements. In this paper it is demonstrated how the
complexity of a bend sequencing task can be handled by means of an
efficient reduction of the search field through well-chosen
representation schemes and the identification of geometric constraints.
The expertise established by experienced process planners was integrated
in search algorithms based on precedence constraint solving and dynamic
branch-and-bound techniques. A case study is used to illustrate these
procedures. Additionally, the characteristics of a dedicated collision
detection algorithm, developed for fast sequence verification during
search procedures, are outlined.
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Networked manufacturing with reality sensation for technology transfer
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M. Mitsuishi, T. Nagao (1)
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STC O, 48/1/1999, P.409
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Keywords: Open-architecture CNC manufacturing system, In-process monitoring, Man-machine system |
Abstract : This paper describes a networked remote manufacturing system with
reality transmission capability for simultaneous technology transfer.
The technologies presented in the paper can be used to establish a
remote operation and monitoring function as an advanced user interface.
The system consists of an open-architecture CNC controller, sensors to
monitor the machining state, mechanical fuses to prevent overloads,
apparatuses to present visual, auditory, force and tactile information
to the user interface, and an input device to operate a machine tool. In
the experiment, visual, force, auditory and tactile information were
successfully presented to operate the system remotely using multi-axis
force information.
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STC P |
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Results of the CIRP-form intercomparison 1996-1998
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O. Jusko, J.G. Salsbury, H. Kunzmann (1)
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STC P, 48/1/1999, P.413
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Keywords: Form-measurement, CMM, Cooperative project |
Abstract : Between 1996 and 1998, an international form intercomparison was
completed. Among the 19 participants, there were 3 from industry, 9 from
universities, and 7 from national metrology institutes. The artifacts
under test included a ring, a plug, and three spheres of different
materials. The measurement tasks included roundness, straightness, and
parallelism. The participants were allowed to choose the type of
measuring instrument, and therefore the results include measurements
from both classical spindlebased form testers and also coordinate
measuring machines (CMMs). For all the measurements, the participants
were instructed to estimate their measurement uncertainty. The closeness
in agreement between the results of the various participants depended on
the measurement task, the assessment parameters, and the instrument type
used.
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Design for a compact high-accuracy CMM
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G.N. Peggs (2), A.J. Lewis, S. Oldfield
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STC P, 48/1/1999, P.417
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Keywords: Coordinate measuring machine, Laser interferometry, Miniaturisation |
Abstract : The trend towards miniaturisation in manufacturing has led to a
requirement for a coordinate measuring machine (CMM) capable of
measuring tiny features on small components. A compact CMM has been
designed and built which has a working volume of a cube of side 50 mm,
and a measurement uncertainty estimated to be 50 nm. The machine
utilises a self-calibrated solid cube to provide a geometrical reference
that is transferred into the CMM by means of a combination of three,
mutually orthogonal, mirrors, six laser interferometers and three dual
axis autocollimators. In situ measurement of the mirrors' flatness and
orthogonality and redundancy of measurement are used to minimise
systematic uncertainties. This paper describes the design of the CMM and
an overview of the theoretical uncertainty analysis.
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Development of the nano-CMM probe based on laser trapping technology
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Y. Takaya, S. Takahashi, T. Miyoshi, K. Saito (2)
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STC P, 48/1/1999, P.421
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Keywords: Optical measurement, Micro-machine, CMM probe |
Abstract : The 3D nano-position sensing probe serves as an important technology in
the development of the nano-CMM used in microfabrication systems. This
paper discusses the laser trapping probe whose principle is based on the
dynamic properties of optically trapped particles and the Linnik
microscope interferometer. Its potentials as a nano-CMM probe were
investigated in fundamental experiments. Single-beam gradient-force
optical traps of silica particles in air were successfully demonstrated
by using an object lens with N.A. of 0.80. Positional detection accuracy
of 30nm was also confirmed through measurements of fringe changes with
the shifts of the probe sphere.
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Evaluation of CMM uncertainty through Monte Carlo simulations
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A. Balsamo (2), M. Di Ciommo, R. Mugno, B.I. Rebaglia, E. Ricci, R. Grella
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STC P, 48/1/1999, P.425
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Keywords: CMM, Measurement uncertainty, Simulation |
Abstract : In recent years there has been an increasing interest in suitable
techniques for evaluating the uncertainties of measurement values
yielded by CMMs. Among others, simulation techniques appear to suit the
versatility of CMMs and to keep the CMM user involvement to a minimum.
The paper outlines the Monte Carlo-based technique under development at
the IMGC and illustrates its modular approach which enables a separate
treatment of the various uncertainty sources. The importance of
measurement correlation is pointed out and a medium-complexity example
is given in the case of geometrical errors.
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Error compensation in CNC turning solely from dimensional measurements of previously machined parts
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Z.Q. Liu, P.K. Venuvinod (1)
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STC P, 48/1/1999, P.429
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Keywords: Error compensation, Measurement, Computer numerical control (CNC) |
Abstract : Inadequate shop floor friendliness is a major reason why traditional
software based error compensation approaches have failed to be accepted
by industry. This paper develops a compensation approach that relies
solely on post-process and on-machine measurements of parts previously
machined on the same machine. The approach is based on a new method of
error decomposition and a simple model of machine deflections induced by
the cutting force. The approach is verified by independent measurements
of the various model parameters. It is also shown that the machine tool
can be made to act as its own dynamometer.
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Testing the contouring performance in 6 degrees of freedom
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W. Knapp (2), S. Weikert
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STC P, 48/1/1999, P.433
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Keywords: Machine Tool, Contouring performance, Measuring instrument |
Abstract : The performance of linear axes is often tested on the basis of one
set-up per one or two directions of deviations from a NC path. With the
application of multi-axes machining the contouring performance in more
than two degrees of freedom is of interest.
The paper describes a measuring instrument to check the contouring
performance of a machine tool in the six degrees of freedom. The three
translations and the three rotations of the relative movement between
tool side and workpiece side are measured simultaneously.
Results of first measurements are presented and discussed.
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'Ductile mode' machining of commercial PZT ceramics
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P.A. Beltrao, A.E. Gee, J. Corbett (2), R.W. Whatmore
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STC P, 48/1/1999, P.437
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Keywords: Ceramic, Ductile transition, Precision machining |
Abstract : A wide range of products rely on the high-precision fabrication of
piece-parts using PZT ceramics. These include ultrasonic medical imaging
transducers, ink jet printing heads, etc. Not only is precision
important, but also the degree of sub-surface damage needs to be
minimised because this is known to compromise performance by engendering
depoling. It also leads to in-service problems due to ageing caused by
the movement of damage-induced domain walls and cracks. A fundamental
machinability investigation was undertaken, commencing with quasi-static
and ruling tests, prior to performing diamond turning and grinding
experiments. This research has helped in the understanding of the PZT
ceramic mechanical and electrical characteristics when machined and also
is being used to build up an optimised machining process model.
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Ultraprecision diamond cutting of hardened steel by applying elliptical vibration cutting
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E. Shamoto, T. Moriwaki (1)
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STC P, 48/1/1999, P.441
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Keywords: Ultra-precision cutting, Steel, Vibration cutting |
Abstract : Elliptical vibration cutting, which has been proposed by the authors, is
applied to ultraprecision diamond cutting of hardened steel in the
present research. Since steel cannot be cut by the ordinary cutting
method with a diamond cutting tool due to excessive tool wear,
performance of the elliptical vibration cutting is examined in
comparison with the conventional vibration cutting. The experimental
results show that the proposed method has superior performance, i.e. low
cutting force, high quality surface finish and long tool life. Based on
these advantages, the elliptical vibration cutting is successfully
applied to ultraprecision cutting of hardened steel, such as
ultraprecision turning of a spherical die and a flexible micro
structure, and ultraprecision micro grooving.
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Sensor systems for industrial applications under water
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H.K. Tönshoff (1), U. Kruse, H.-J. Mahner
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STC P, 48/1/1999, P.445
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Keywords: Robotic, Distance measurement, Under water |
Abstract : For applications of robots in industrial underwater environments sensor
systems are required to identify the observed scene and to determine the
position of the tool-center-point (TCP) of robots. A laser radar for
guidance of a mobile underwater vehicle is based on a different
absorption distance measurement method, which calculates the distance by
the different attenuation behaviour of water at two different laserlight
wavelengths. Therefore, scattering and attenuation processes in water
have to be incorporated. An ultrasonic measurement system is built as a
trilateration system. It consists of piezo-actuators and uses a
time-of-flight method combined with a phase-shift measurement. Thus it
is possible to identify the exact position and orientation of the
actuator of an underwater robot with a very high accuracy.
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STC S |
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Recent developments in hardness testing and their implications for standardisation
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T.J. Bell, E.G. Thwaite (1)
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STC S, 48/1/1999, P.449
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Keywords: Hardness, Testing, Standardisation |
Abstract : This paper discusses two current developments in the field of hardness
testing. Recent proposals for the Rockwell C scale should make it
possible for a `Unified' Rockwell scale with agreement between National
Standards Laboratories within 0.1 HRC. The need for better understanding
of the Ultra Micro Indentation Test, where force and penetration are
recorded simultaneously, will also be discussed. Difficulties in
standardisation of this technique are exacerbated by metrological
problems, a diversity of terminology and numerous variations to the method.
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Investigation of surface formation process of silicon molecular beam epitaxy by atomic force microscopy
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Y. Furukawa (1), A. Kaneko
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STC S, 48/1/1999, P.453
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Keywords: Physical vapor deposition, Ultra-precision machining, Atomic force microscopy |
Abstract : Evaporated Silicon molecules are epitaxially grown on (100), (111) and
(110) oriented single crystalline Si substrates by MBE, and their
molecular level surface formation processes are observed by both AFM and
RHEED. In the case of growth on (100) and (110) at 800°C, the surface
was covered with many nuclei at first, then, they began to combine
together. In the case of (111) at 800°C, giant steps were formed at
first and subsequent growth changed the length and edge shape of steps;
however, the steps themselves could never be eliminated. It is now
proposed that the molecular level surface formation model be adapted to
take these experimental results into consideration.
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An optical surface texture sensor suitable for integration into a coordinate measuring machine
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C. Bradley, J. Jeswiet (1)
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STC S, 48/1/1999, P.459
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Keywords: Sensor, Texture, Surface |
Abstract : A fiber optic sensor system is described for non-contact measurement of
surface texture. The sensor employs a fiber optic guide and lens
arrangement that forms an interferometric cavity between the lens front
face and the surface. Changes in the surface topography are manifested
as phase changes between the light reflected from the surface and the
front face of the lens. An electronic control and data acquisition
system converts the phase change into a voltage signal proportional to
surface topography. The sensor performance is evaluated against stylus
profilometer results and comparison of the amplitude parameter, Ra,
shows good agreement.
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Surface topography characterization using an atomic force microscope mounted on a coordinate measuring machine
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L. De Chiffre (2), H.N. Hansen, N. Kofod
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STC S, 48/1/1999, P.463
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Keywords: Surface topography, Atomic force microscopy (AFM), Coordinate measuring machine (CMM) |
Abstract : The paper describes the construction, testing and use of an integrated
system for topographic characterization of fine surfaces on parts having
relatively big dimensions. An atomic force microscope (AFM) was mounted
on a manual three-coordinate measuring machine (CMM) achieving free
positioning of the AFM probe in space. This means that the limited
measuring range of the AFM (40 pm x 40 pm x 2.7 pm) can be extended by
positioning the AFM probe using the movements of the CMM axes (400 mm x
100 mm x 75 mm). Evaluation of the background noise by determining the
Sa value of an optical flat gave values in the order of 1 nm. The
positioning repeatability of the two horizontal axes of the CMM was
determined to ±1 pm. Sets of four 20 pm x 20 pm areas were traced on
flat objects, combining the data into single 40 pm x 40 pm areas, and
comparing the roughness values to those for the same areas traced in
single scans of 40 pm x 40 pm. The results show that surface mapping on
industrial surfaces is possible using the Least Mean Square alignment
provided by the AFM software.
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Requirements for the application of speckle correlation techniques to on-line inspection of surface roughness
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G. Goch (2), J. Peters, p. Lehmann, H. Liu
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STC S, 48/1/1999, P.467
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Keywords: Roughness, Scatter, Optical Sensor |
Abstract : Conventional surface roughness measurements using profilometric
instruments (either mechanical or optical) are standardized and
extensively applied in industry. However, these techniques are not
suitable to an on-line inspection of industrial machining processes. If
an optically rough surface leading to a diffuse scattering is
illuminated by coherent light, a speckle pattern occurs showing a
granular spatial intensity distribution of the scattered light. In
general, the averaged intensity distribution depends on the distribution
of the local surface slopes. However, if two speckle patterns at
different laser wavelengths are compared via correlation techniques, a
measure of the root-mean-square (rms) roughness (Rq) can be obtained,
based on certain statistical assumptions. This paper contributes to the
application of speckle correlation techniques to the inspection of
machined surfaces. Surface statistics dependent on the manufacturing
processes are checked. Optical arrangements of a measuring device are
introduced. Furthermore, results showing the limits of speckle
correlation are presented.
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