THE INTERNATIONAL ACADEMY FOR PRODUCTION ENGINEERING
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CIRP ANNALS 1996 |
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STC A |
| Modularity: the basis for product and factory reengineering |
| G. Erixon, A. von Yxkull, A. Arnström (2) |
| STC A, 45/1/1996, P.1 |
| Keywords: Assembling, Module, Methodology |
|
Abstract : "Products in the Product" (Modules) and "Factories in the Factory"
(Assembly Module Workshops) has proved to be an excellent basis for
continuous product renewal and concurrent development of the
manufacturing system. Modularity based on the use of "module drivers"
enables the set up of independent assembly units for each module that
can be precisely adapted to the requirements of the actual module. This
paper presents a proven methodology for product and factory
reengineering using the concept of "module drivers". The methodology
consists of 5 design steps, from the clarification of customer
requirements to the design of each module and the concurrent development
of the assembly system. |
| Robust assembly processes as a means of achieving systemability |
| G. Reinhart, R. Lindermaier, R. Gräser, B. Eich / J. Milberg (1) |
| STC A, 45/1/1996, P.7 |
| Keywords: Assembly Machine, Processability, Optimization |
|
Abstract : The operating economy of automated assembly plants is directly related
to their yield of OK parts. A hitherto unutilised opportunity for
optimization consists in minimizing the scattering in the performance
and fault characteristics of an assembly system. The key to this
optimization is robust processes which can be created with the aid of
various measures. Such measures include avoiding or compensating for
variable parameters. or reducing and restructuring process chains.
Reference data such as processability or the new system ability indices
serve as a basis for assessing the robustness of assembly processes and
in particular the complex interplay between them. It thus becomes
possible to analyse factors influencing the boosts the efficiency
assembly process and system, and to visualise them. By way of
information feed back, control circuits which of existing assembly
processes and process chains, and which are of use in the planning of
new plants, can be built up. |
| Solving technical problems in assembly system's design |
| H. Bley, U. Seel / K.G. Günther (1) |
| STC A, 45/1/1996, P.11 |
| Keywords: Problem Solving, CAP, Feature |
|
Abstract : The design of an assembly system leads to very difficult technical
problems in which technological, functional and economical aspects must
be considered. The designer's experience represents a crucial portion of
the information which has to be made available. Another part of the
needed information is contained in the product design, and part of it is
provided by suppliers of assembly system components. Problem solving
based on information incorporated in assembly features will be
demonstrated using problems encountered in an existing assembly system.
The characterisation of features related to assembly is a research topic
at the Saarland University. Preliminary results of a contribution to
feature-based CAD-systems will be presented. |
| Construction and start-up of complex assembly systems |
| H.-P. Wiendahl (1), J. M. Thies, K. Zeugträger |
| STC A, 45/1/1996, P.17 |
| Keywords: Plant Construction Management, Information Feedback, Problem Solving |
|
Abstract : The construction of production systems is determined by a high technical
and organizational complexity. Methods for Project Management help to
handle the organizational tasks. However the site itself is often a more
or less isolated place with only relatively little information exchanged
with the headquarters. In consequence much valuable experience
knowledge, especially technical knowledge of the late project phases -
start-up and tuning - is lost. In contrast to this, an ascertainment and
documentation of problems could be used for future technical and
organizational enhancements of the production system or the company's
processes. This knowledge could be supplemented by operating data and in
this way also help to improve the production and maintenance management
of the following operating phase. The following described methods are
designed to close this gap between project management and production
management to help both the system manufacturer and the system operator. |
| Automated sewing of textiles with different contours |
| T. Gottschalk, G. Seliger (2) |
| STC A, 45/1/1996, P.23 |
| Keywords: Automated Assembling, Kinematic, Process Modelling |
|
Abstract : To achieve a three-dimensional form of clothing a sophisticated joining
of pieces of fabrics is required. Different lengths and contours have
to be fit. A planning system has been realised to achieve the
geometrical adaptation with respect to the different material properties
of fabrics. Today, only a highly skilled seamstress can operate sewing
machines to fulfil these requirements.
This paper presents an approach for flexible automation of sewing
processes. The distribution of stitching points for planning the seam
paths of the pieces to he sewn are calculated based on experimentally
investigated fabric properties. The movement commands for fabric
transport are calculated from the task requirements for sewing. Finally,
a roller feeding device for sewing gently curved pieces has been
realised to demonstrate the effectiveness of this approach. |
| Development of spherical ultrasonic motor |
| S. Toyama / A. Kobayashi (1) |
| STC A, 45/1/1996, P.27 |
| Keywords: Actuator, Ultrasonic, Motion Study |
|
Abstract : We have successfully developed a new type of spherical motor with two
degree of freedom by ultrasonic vibration; it has Ø 445 mm rotor; the
maximum speed is 30 rpm; the maximum output torque reaches 0.7 kgf cm;
the maximum positioning error is less than 0.3 mm. It has very small and
simple structure and has good controllability. We can expect to apply
this motor to robotic manipulator's joints, machine vision systems,
assembling machines, laser cutting tools and many fields. |
| Micro SCARA robot as universal adaptive compliant wrist |
| D. Milutinovic / V.R. Milacic (1) |
| STC A, 45/1/1996, P.31 |
| Keywords: Robotic Assembling, Robotic Mechanism, Compliance Center |
|
Abstract : The newly developed robotic mechanism based on well-known SCARA concept
uses two eccentrically positioned rotating discs instead of two joined
links. The paper analyzes the capabilities and advantages of the use of
this mechanism in the realization of micro SCARA robot as an additional
adaptive compliant wrist to standard robot configurations for assembly
tasks. The prototype of a universal passive adaptive compliant wrist was
developed at this stage. The performance around its true compliance
center obtained under precisely determined conditions proved successful. |
| ASPEN: Computer-aided assembly sequence planning and evaluation system based on predetermined time standard |
| S. Kanai, H. Takahashi, H. Makino (1) |
| STC A, 45/1/1996, P.35 |
| Keywords: Assembling, Sequencing, Computer Aided Planning |
|
Abstract : The purpose of this research is to objectively evaluate the differences
among the feasible assembly sequences. For this purpose, a
computer-aided Assembly Sequence Planning and Evaluation system (ASPEN)
was developed. ASPEN automatically searches all geometrically feasible
sequences by decomposing solid models of a product. ASPEN also chooses
an optimum sequence with the least operating time. MTM (Methods Time
Measurement) and DFA (Boothroyd's Design For Assembly) which are kinds
of predetermined time standards are used to explicitly evaluate the
differences of operating time among feasible sequences. The calculation
of the operating time based on the data obtained from the sequence
planning is discussed. The proposed evaluation method is verified
through an experiment on actual assembling work. |
| An automatic process planning system for block assembly in shipbuilding |
| K.K. Cho (1), S.H. Lee, D.S. Chung |
| STC A, 45/1/1996, P.41 |
| Keywords: CAPP, Assembly |
|
Abstract : Block assembly in shipbuilding is mainly concerned with cutting and
welding operations to construct a block. A block is composed of several
steel plates and sections with various sizes and shapes. Process
planning for block assembly is to generate cutting and bending operation
plans, assembly processes and sequences, and welding operation plans to
construct a block. This paper deals with the development of an automatic
process planning system for block assembly in shipbuilding. Part
assembly graph that is a semantic network type of representation scheme
for block structure is proposed and used to represent block information.
The approaches adopted are case-based reasoning for block assembly
process planning and rule-based reasoning for process planning of
cutting and welding operations. The prototype system has been
implemented and verified using real blocks in the block assembly shop. |
| Managing multiple product variants in assembly control with a fuzzy Petri-Net approach |
| W. Eversheim (1), T. Hack |
| STC A, 45/1/1996, P.45 |
| Keywords: Schedulling, Fuzzy Constraints, Flexibility |
|
Abstract : Companies with make-to-order businesses are facing increasingly dynamic
movements within their sales markets. This leads to a growing variety of
products and a demand for higher flexibility in order processing.
Different logistical goals, process flexibility and fuzzy-expressed
dimensions as well as short-term changes due to rush-orders or
disturbances, have to be considered within this multiple product variant
environment. This paper describes how these controversial requirements
can be appropriately represented within a scheduling model, by applying
a fuzzy Petri-net approach. All in all, control personnel can be
efficiently supported. The described model and methods are verified
within an industrial application. |
| Probabilistic reactive disassembly planning |
| D. Geiger, E. Zussman / E. Lenz (1) |
| STC A, 45/1/1996, P.49 |
| Keywords: Disassembly, Planning, Statistical |
|
Abstract : A paradigm for reactive disassembly planning is developed which combines
prior information about the disassembly task encoded in a predictive
plan as well as measurements collected during the process in order to
select the current most promising disassembly operation. Planning relies
on a probabilistic inference mechanism which employs a Bayesian Network.
It integrates perception and action and uses the dependencies among
various parts of a product to propagate uncertainty regarding their
condition as sensed during the disassembly process. Our methodology
allows a computerized assessment of an End-Of-Life value of a product
which will enable manufacturers to combine design principles that take
into account environmental considerations at minimum cost during the
design cycle. The approach is demonstrated by a case study. |
STC C |
| An analytical model for cyclic chip formation in 2-D machining with chip breaking |
| X.D. Fang, I.S. Jawahir (2) |
| STC C, 45/1/1996, P.53 |
| Keywords: Chip Breaking, Machining, Predicting Model |
|
Abstract : This paper presents a new analytical model /for /2-D machining involving
a cyclic chip formation process due to chip breaking. This model
includes a chip/work contact force at the free-end of the curled chip
which contributes to the development of a bending moment in the chip.
Chip breaking occurs when the bending moment and the corresponding chip
strain reach maximum. The model provides a predictive capability for
forces acting on the chip, bending moment, chip thickness, chip
velocity, tool-chip contact length, shear angle, friction angle, etc.
for a given set of input conditions such as the work material, cutting
conditions. tool rake angle and chip-work friction conditions. Oxley's
machining theory was used for predicting the work material shear flow
stress at the shear plane. The present work provides a deeper insight
into the chip breaking process in machining. |
| A general mechanics and dynamics model for helical end mills |
| Y. Altintas (2), P. Lee |
| STC C, 45/1/1996, P.59 |
| Keywords: Milling, Forces, Chatter |
|
Abstract : The mechanics and dynamics of helical end milling processes are
integrated to a general model. The chip removal geometry is evaluated by
considering the true kinematics of the operation and chatter vibrations.
The cutting forces are predicted by transforming shear angle, shear
stress and friction angle stored in an orthogonal cutting data base to
local oblique edge segments along the helical flutes. The general model
allows prediction of cutting forces, vibrations, dimensional surface
errors and chatter stability lobes for a class of helical end mills. The
model is verified experimentally on cylindrical and ball end mills with
complex helix geometry. |
| Predictive force models for point thinned and circular centre edge twist drill designs |
| E.J.A. Armarego (1), H. Zhao |
| STC C, 45/1/1996, P.65 |
| Keywords: Force Modelling, Drilling, Cutting |
|
Abstract : The geometry and specification of point thinned general purpose and
facet point drills as well as the patented `circular centre edge' twist
drill design are studied and used to develop predictive mechanics of
cutting models for the thrusts and torques for these drill designs. It
is shown that the three designs involve point thinning, to improve the
rake angle and cutting action at the chisel edge, with the circular
centre edge drill being a variation of the point thinned facet point
drill. The predictive models have been numerically and experimentally
tested. While these drill designs substantially reduce the thrust force
when compared to unthinned drills the difference in the forces for the
three designs are minimal when compared on a fair basis. The importance
of geometry and force modelling in assessing drill designs is
highlighted in this work. |
| A model for chip formation during machining of hardened steel |
| M.A. Elbestawi (1), A.K. Srivastava, T.I. El-Wardany |
| STC C, 45/1/1996, P.71 |
| Keywords: Hard Turning, Strain Energy Density, Chip Formation, Crack |
|
Abstract : Saw-toothed chips are formed during machining of hardened steel (H_R
,s60-63). This paper presents a new analytical approach for modelling
the chip formation mechanism in hard-turning. It has been observed that
the chip formation starts with initiation of a crack at the free surface
of the workpiece which further propagates towards the cutting edge of
the tool. The crack soon ceases to grow at a point where severe plastic
deformation of the material exists under higher level of compressive
stresses. The chip segment caught up between the tool rake face and the
crack is pushed out while the material in the plastic region just below
the base of the crack is displaced along the tool rake face thus forming
saw-toothed chips. The direction of crack initiation and propagation are
predicted using the surface layer energy/strain energy density
criterion. The maximum value of surface layer energy, Y,,,,,,, can be
used to evaluate the angle of crack initiation while the strain energy
density criterion predicts the corresponding crack propagation angle.
Here, the process of chip formation is considered to be a mixed mode
crack problem of Mode I and Mode II. The theoretical predictions are
verified by the resultant chip contours obtained experimentally. The
predictions made are shown to be in good agreement with those measured
experimentally. |
| On chip morphology, tool wear and cutting mechanics in finish hard turning |
| M.A. Davies, Y.S. Chou, C.J. Evans (2) |
| STC C, 45/1/1996, P.77 |
| Keywords: Cubic Boron Nitride (CBN), Tool Wear, Chip Formation |
|
Abstract : Topography of surfaces produced in finish hard turning using cubic boron
nitride (CBN) tools is affected by a large number of factors including
tool wear and the mechanics of the chip formation process. This paper
shows first that tool wear rates are affected by interactions between
the work material and the binder phase of the CBN tool. For finish hard
turning, low CBN content, ceramic binder tools give longer lives and
better finish than high CBN content metallic binder tools. For low CBN
tools, wear rate is directly related to the microstructure of the work
material and to the CBN grain size. SEM studies suggest that chip
morphology is independent of work material microstructure, but varies
with tool wear. Orthogonal cutting tests show that, above a critical
speed, segmented chips are formed by catastrophic localized shear and
that chip segmentation spacing may be reflected in a modulation of the
machined surface. Segment spacing is a function of depth of cut, rake
angle, and surface speed, approaching a limiting value with speed.
Specific cutting energies decrease with speed, also approaching an
asymptote. A simple mechanical model gives reasonable predictions of
segment spacing along the original surface, although a full
thermo-plastic model will be required to account for other aspects of
the chip formation process. |
| Towards active chip control |
| P.K. Venuvinod (2), A. Djordjevich |
| STC C, 45/1/1996, P.83 |
| Keywords: Chip, Sensor, Control |
|
Abstract : Current reliance on chip formers with fixed geometries suffers from
limitations on the work materials and cutting conditions. This paper
examines the feasibility of the hitherto unexplored concept of active
chip control. An actuator with two degrees of freedom, utilizing an
obstruction type chip former, and based on Nakayama's assertion that the
position and orientation of the line of separation of the chip from the
tool rake determines the chip form, has yielded encouraging results.
Stable clusters of chip forms under varying cutting conditions have been
obtained through appropriate geometric transformations of the control
variables. Experimental work on a variety of sensors has identified chip
form sensing through the use of electrostatic induction, optical fibers,
and infra-red cameras to be amongst the most promising. |
| Machinability improvement of steels at high cutting speeds. Study of tool-work material interaction |
| J.C. Hamman, V. Grolleau, F. Le Maître (1) |
| STC C, 45/1/1996, P.87 |
| Keywords: Tool Geometry, Simulation, Free Machining Steels |
|
Abstract : Special metallurgical treatments after deoxidation of free machining
steels allows further improvement in the machinability of these
materials using higher cutting speeds.
However, the consequences of these treatments on chip flow and tool-work
material interactions are not clear as the influence of tool geometry on
such treatments is not known. Despite the above, such information is
needed to optimize the tools in the context of high speed machining
development.This paper presents a comparison between some conclusions
found in literature survey concerning the influence of these treatments
and experimental facts observed in low carbon free cutting steels and
structural free machining steels. These experimental observations are
completed by a numerical simulation of chip formation. |
| On-line prediction of the tool-life |
| A. Novak (1), H. Wiklund |
| STC C, 45/1/1996, P.93 |
| Keywords: Tool Life, Machinability, Statistical Analysis |
|
Abstract : The paper presents a new approach improving the reliability of on-line
prediction of tool-life without the need of pre-process data. The
ambition has been to develop a robust monitoring strategy feasible for
practical implementation on a CNC lathe. The tool-life is related to a
selected critical point on the tool wear curve. Applied multisensing is
based on the cutting force ratio correlated with in-process measurement
of the flank wear by a vision system. The acquired process data are
evaluated and handled by means of the modified and combined statistical
methods. Initial cut is used to monitor the process and to evaluate the
model parameters when critical conditions are simultaneously supervised
by an additional monitoring method. The process model development,
reference value setting and tool-life prediction have been automated as
machine tool control features. Traditional tool condition monitoring
'can be improved by the reduced need of pre-process reference or
machinability data, no need of calibrating procedures and, by early
prediction of the tool-life with uncertainty of about 15%37; after 1.5-2.0
minutes of cutting. The efficiency and flexibility of the developed
method has been verified by several machinability tests performed under
various machining conditions but for the same work material. |
| An in-process direct monitoring method for milling tool failures using a laser sensor |
| O. Ryabov, K. Mori, N. Kasashima / K. Uehara (1) |
| STC C, 45/1/1996, P.97 |
| Keywords: On-line Monitoring, Tool Failure, Laser Sensor |
|
Abstract : An in-process tool geometry measurement system for milling has been
developed using a commercially available laser displacement sensor. The
system reconstructs and displays the 3-D image of a milling tool and
evaluates the tool geometric failures via a hybrid laser sensor
measurement method which uses displacement and intensity techniques
simultaneously. The system is designed to compensate for interruptions
in the laser path brought about by chips and coolant drops present under
actual cutting conditions. In experimental tests, the reconstructed 3-D
geometrical tool image and the intensity measurements enabled us to
detect the size and the location of chipped part and to determine the
length of the flank wear to an accuracy of 40 µm. |
| Energy conversion in cutting and grinding |
| M.C. Shaw (1) |
| STC C, 45/1/1996, P.101 |
| Keywords: Energy, Cutting, Grinding |
|
Abstract : There are similarities and differences with regard to energy conversion
in cutting and grinding. In both cases practically all of the energy
ends up as heat. However, there are major differences in the dispersion
of the heat in the two cases. There are two regimes of grinding
depending on the undeformed chip size involved and each of these is
associated with a different mode of chip formation. This paper discusses
the conversion and transport of energy in cutting and grinding in
fundamental terms. |
STC Dn |
| The missing element in design for manufacture |
| T. Lenau, L. Alting (1) |
| STC Dn, 45/1/1996, P.105 |
| Keywords: Design, Producability, Integrated |
|
Abstract : Most work on design for manufacture (DFM) concentrates on the analysis
part of the design work. but support of synthesis activities has much
less attention. Particularly the early selection of processes and
materials needs further research. The paper will describe a systematic
method for selection of manufacturing processes and materials as well as
the Designers Manufacturing Inspirator - a computer based tool that
inspires the designer to examine materials/processes unknown to him or
her. An important research question is here the information modelling
based on empirical investigations. |
| Design for disassembly and the environment |
| T. Harjula, B. Rapoza, W.A. Knight (2), G. Boothroyd (1) |
| STC Dn, 45/1/1996, P.109 |
| Keywords: Design, Disassembly, Environmental |
|
Abstract : The financial and environmental consequences of disassembly and
recycling at the end of a product's life are studied. Analyses of a
small coffee maker and some large domestic appliances are presented. It
is shown that redesign proposals resulting from Design for Assembly
analysis are compatible with Design for Disassembly and that significant
improvements are achievable. It is also shown that optimization of the
disassembly sequence is important in order to maximize any financial
benefits, but that to minimize environmental impact considerations
additional to Design for Disassembly should be taken into account.
Criteria to determine the point at which disassembly should cease are
discussed. |
| Feedback of manufacturing experience for DFM design rules |
| R. Barton, Y.S. Joo, I. Ham (1) |
| STC Dn, 45/1/1996, P.115 |
| Keywords: Manufacturing, Feedback, Information, Management, Electronic, Circuit |
|
Abstract : In many manufacturing areas, design rules are used to assist in design
for manufacturing. These rules are often specific and formal, yet they
are usually developed in an ad-hoc manner by design committees and/or
design software vendors. This work describes a database architecture and
a statistical modeling methodology that enable the formal capture of
manufacturing experience as new or revised design rules. The method uses
pass/fail or other quality data from the firm's own manufacturing
experience to update design limits or to introduce new design rules. |
| Intuitive physical-based CAD system for designing of sculptured surfaces |
| P. Kagan, A. Fischer, M. Shpitalni (1) |
| STC Dn, 45/1/1996, P.121 |
| Keywords: Computer Aided Design, Surface, Force |
|
Abstract : The geometrical model for sculptured and highly curved objects is
complex and not trivial. Designing such surfaces is therefore difficult
if the pure mathematical approach is taken. More natural and intuitive
techniques are sought to facilitate the design process. In this paper,
an intuitive CAD system for design of sculptured surfaces is introduced.
The/ /method/ /is based upon simulating the behavior of curves and
surfaces under applied forces. The use of forces makes the system
intuitive because it is based or our everyday experience. The B-sline
formulation is used both to actually solve the physical model and to
represent the geometric model Thus, conversions are eliminated,
calculations are accelerated, and interactive operation is maintained.
The system gnaws a family of curves (or surfaces) from which the user
can choose. Results and examples are demonstrated. |
| A unified approach to freeform and regular feature modeling |
| H.K. Tönshoff (1), J.C. Aurich, M. Ehrmann, N. d'Agostino |
| STC Dn, 45/1/1996, P.125 |
| Keywords: Computer Aided Design (CAD), Free-form Feature, Sculptured |
|
Abstract : Surfaces
Feature based design for objects with prismatic or conic geometry - also
called regular geometry - has proven to be a valuable tool for the
designer. Typical examples for design features are slots, pockets,
borings or chamfers. Recent research has addressed the use of freeform
features in the design of sculptured surfaces. Here, dedicated surface
modeling systems and specialized surface models have been used for
geometry representation resulting in a separation from existing feature
modelers which typically use a solid modeler as a geometry engine. This
paper presents a method for the integration of freeform and regular
features within one data structure. |
| Data fitting using dual kriging and genetic algorithms |
| A. Limaiem, A. Nassef, H.A. ElMaraghy (1) |
| STC Dn, 45/1/1996, P.129 |
| Keywords: Reverse Engineering, Optimization, Geometric Modelling |
|
Abstract : This paper presents a new method for data fitting based on the use of
dual kriging for curve and surface fitting and genetic algorithms for
optimizing the the model parameters. Classical dual kriging methodology,
has been adapted to data fitting problems. Genetic algorithms have been
used to choose the optimum set of model parameters in order to globally
minimize the average deviation of the data points from the kriging
model. The computation time required for this method is much shorter
than those required by other methods. The obtained model is very simple
and very small deviation values are observed. It has been tested and
validated using actual scanned data. |
| Decision making and software tools for product development based on axiomatic design theory |
| V. Harutunian, M. Nordlund, D. Tate, N.P. Suh (1) |
| STC Dn, 45/1/1996, P.135 |
| Keywords: Design, Axioms, Software |
|
Abstract : A software tool based on axiomatic design is being developed. Axiomatic
Design (AD) provides a framework to describe design objects and a set of
axioms to evaluate relations between intended functions (FR's) and means
by which they are achieved (DPs). AD analysis can be performed for
engineering change orders (ECO) and field support systems with the
capability for organizational learning. The software effort attempts to
enhance the engineering CAD environment through the documentation of
design rational based on AD and the implementation of AD matrices to
evaluate design decisions and provide the proper development sequence. |
| Modelling information in design background for product development support |
| H. Suzuki, F. Kimura (1), B. Moser, T. Yamada |
| STC Dn, 45/1/1996, P.141 |
| Keywords: Design, CAD, Product Modelling |
|
Abstract : In design environment various kinds of information are generated and
used. However most of the information which is generated during product
development process, but is not explicitly used in production, is not
represented and stored in a useful manner. An approach is proposed for
capturing and representing design background information (DBI) to
support product development. Based on the evaluation of the prototype
system, two issues are discussed in this paper. One is the importance of
inclusion of DBI concept to product data management systems, and the
other is how to link DBI with engineering simulations. |
| Planning and multi-criteria optimization of design processes |
| F.-L. Krause (2), F. Golm |
| STC Dn, 45/1/1996, P.145 |
| Keywords: Design, Optimization, Resources |
|
Abstract : Proceeding from the assumption that in the future an intensified
re-engineering of business processes in the area of product development
will be necessary, the deployment of powerful tools in this area
appropriate. An approach is presented providing the support for the
restructuring and optimization of business processes surpassing the
functional scope of commercially available tools. The approach sets the
further goal of employing the business models generated to perform a
multi-criteria process optimization as well. This optimization is to be
performed in an automated fashion under end-user control based on a
process-related system of key-figures. |
| Design of a manufacturing resource info-system |
| T. Kjellberg (2), M. Bohlin |
| STC Dn, 45/1/1996, P.149 |
| Keywords: Information System, Manufacturing Resource, Design |
|
Abstract : Manufacturing resources will be modelled in computer in the future.
Standards as STEP and future enhancements of STEP will play an important
role. Documentation of manufacturing resources will be distributed to
customers in the form of active models in computer. This will give new
possibilities for developing more advanced applications for planning
etc. in manufacturing. It will influence the design of manufacturing
resource info-systems. The design of manufacturing info-system must
fulfil a number of requirements like; it should be easily maintained and
updated with new resources, new product generations should be easily and
directly introduced, planning applications etc. should be easy to update
and exchange. |
| Design for mass customization |
| M.M. Tseng, X.J. Jiao / M.E. Merchant (1) |
| STC Dn, 45/1/1996, P.153 |
| Keywords: Design, Product, Repeatability |
|
Abstract : Mass customization has recently received a significant amount of
attention by the business community. However, the engineering approach
to produce an increasing variety of customers' requirements without a
corresponding increase in cost has not been well developed. In this
paper, we propose a design approach to mass customization (DFMC) that is
based on the belief that mass customization can be effectively achieved
through design, in particular during the conceptual design and
preliminary development stages. The core of DFMC is to develop a mass
customization oriented product family architecture (PFA) with a meta
level design process integration as an unified product creation and
delivery process model. The formulation of PFA enables the optimization
of reusability/commonality in both product design and process selection
from the product family perspective. It also provides a basis to
facilitate the front end configuration in order to fulfil the individual
requirements of customers. This paper reports the proposed approach with
an example of mass customization of power supply products. |
| Integrated simulation of manufacturing processes in CAD systems - Ideas and concepts |
| B. Scholz-Reiter, M. Kleiner / G. Spur (1) |
| STC Dn, 45/1/1996, P.157 |
| Keywords: CAD, Bending, Extrusion |
|
Abstract : Integration of design and computation in CAD systems is a major effort
of research. In this paper we describe an approach which for example
beside common calculation of strength allows the designer to take into
account influences of the considered manufacturing process e.g. the
considerable residual stress of bent extrusions resulting from the
bending process. Part properties influenced by the intended
manufacturing can be controlled continuously during the design process.
The results of simulation influence the modification of the geometric
design directly. Vice versa geometric data can be input for calculation
without transformation.. |
| A relation based product model suited for integrating design and manufacturing |
| A.J. Van der Net, W.A.H. de Vries, F.L.M. Delbressine (2), A.C.H. Van der Wolf (1) |
| STC Dn, 45/1/1996, P.161 |
| Keywords: Product Modelling, Tolerancing, Computer Integrated Manufacturing |
|
Abstract : In this paper a model of the design process is proposed, based on
manufacturable design transformations. The product model enables
manufacturability checking while designing. The model is based on
relations between geometrical entities, with a tolerance model as an
inseparable part. When performing for instance assembly analysis,
creating numerical code for a machining centre, or command code for a
Co-ordinate Measuring Machine, the product description is interpreted
for implications in those specific applications. The authors demonstrate
a method to reason with tolerances in several stages in design and
manufacturing. A typical example is used to illustrate the method. |
| Potentials of structural optimization systems in product development |
| M. Weck (1), J. Asbeck, A. Büssenschütt |
| STC Dn, 45/1/1996, P.165 |
| Keywords: Computer Aided Design, Finite-Element-Method, Optimisation |
|
Abstract : The quality of structural optimisation in product design depends on the
intuitively selected initial geometry and is a result of the designer's
experience. The improvement in weight reduction or stiffness gain, which
is within reach by current optimisation systems, can only be modest.
Topology optimisation, however, needs only few boundary conditions for
generating a complete preliminary geometry automatically. This rough
design can be used as the basic shape for further optimisation
strategies, e.g. shape optimisation. So the target should be the
integration of topology and shape optimisation in a CAD-System in order
to produce a tool which supports the complete design process. This
contribution deals with several applications of an integrated topology
and shape optimisation system. |
STC E |
| Analysis of ultrasonic-aided laser drilling using finite element method |
| T.M. Yue, T.W. Chan, H.C. Man, W.S. Lau (1) |
| STC E, 45/1/1996, P.169 |
| Keywords: Finite Element Method (FEM), Laser Beam Machining (LBM), Ultrasonic |
|
Abstract : Previously, a novel Ultrasonic-Aided Laser (UAL) drilling technique has
been developed to raise the performance of traditional laser drilling
method, as well as to improve the overall quality of the "machined"
hole. In this connection, a theoretical model using Finite element
method (FEM) has now been developed to determine the shape of UAL
drilled holes and the thickness of the re-cast layer. In addition, the
temperature profile of the hole during UAL processing can be established
and from which the size of the re-cast layer can be determined.
Experimental results show good agreement with the theoretical predictions. |
| Laser welding of superalloys for the manufacturing of aeroengine components |
| M. Cantello (2), G. Ricciardi (2), S.L. Gobbi |
| STC E, 45/1/1996, P.173 |
| Keywords: Welding, Lasers, Metallurgy |
|
Abstract : The paper describes the welding of inconel Superalloy using high power
CO2 and Nd YAG lasers, to be adopted in the manufacturing of aeroengine
and power plant components. The metallurgy related to the NbC and the
Delta phase at grain boundaries, consequent to the typical 10.000 °KIs
rapid cooling of the fusion zone, has been investigated using the
scanning and transmission electron microscopes Microfissures free welds
were achieved in the annealed state with grain sizes of ASTM 10 or
finer. Real scale aeroengine components prototypes have been produced
out of 0 3 - 1 - 3 5 and 8 mm metal thickness. |
| New developments in surface technology: laser alloying using Mo/VC and Mn |
| F. Klocke (2), L. Rozsnoki, T. Celiker |
| STC E, 45/1/1996, P.179 |
| Keywords: Surface, Wear, Laser-Alloying |
|
Abstract : Laser beam alloying of forging and diecasting tools with additional
materials has proved in industry its ability to modify the chemical
composition and thereby the properties of the surface layers. This
results in a manifold increase in tool life. Relying on this knowledge,
new surface layers for tools and components were systematically
developed. For example, the additional alloying with molybdenum (Mo) and
vanadium carbide (VC) significantly increases the tool hardness
retention, high temperature-hardness, and hot wear resistance. By
alloying with manganese (Mn), it is possible to improve the wear
properties of surface layers for components that undergo heavy impact
load. This contribution will contain the scientific and fundamental
characteristics of surface layers produced in this manner, as well as
their analysis with regards to operational properties. |
| Basic powder metallurgical aspects in selective metal powder sintering |
| J.P. Kruth (1), B. Van der Schueren,J.E. Bonse, B. Morren |
| STC E, 45/1/1996, P.183 |
| Keywords: Rapid Prototyping, Sintering, Laser |
|
Abstract : A recent evolution in Rapid Prototyping is the direct production of
metal parts. The main bottle necks are part accuracy and appropriate
material properties. This paper describes the approach of selective
metal powder sintering (SMS) where liquid phase sintering actions as the
basic binding mechanism between individual metal particles. The merits
and drawbacks of this approach are highlighted from metallographic point
of view. Next, a few material combinations, which have been
experimentally verified, will be described from point of view of
performance in the SMS process. Simultaneously, solutions for problems
related to this performance are proposed and discussed. |
| The selective laser sintering of polycarbonate |
| M. Berzins, T.H.C. Childs (2), G.R. Ryder |
| STC E, 45/1/1996, P.187 |
| Keywords: Rapid prototyping, Sintering, Thermal Modelling |
|
Abstract : This paper investigates thermal modelling of the selective laser
sintering process for amorphous polycarbonate powders. The aim is to
develop a simulation for process accuracy and control which are key
areas of development for the new layer manufacturing rapid prototyping
technologies. A state-of-the-art adaptive mesh 2D finite difference code
is used simultaneously to consider heating and sintering and its results
compared with a classical moving heat source model and with experiments.
The analysis shows that the change of material thermal properties with
temperature and particularly with position as densification takes place
must be included for accurate prediction of both densification and of
the phenomenon known as 'bonus z'. The work forms a basis for moving to
a 3D simulation. |
| Marking of computer keyboards by means of excimer lasers |
| G. Ricciardi (2), M. Cantello (2),G. Savant Aira |
| STC E, 45/1/1996, P.191 |
| Keywords: Excimer Laser, Processing, Plastic |
|
Abstract : An excimer laser-based technique for marking computer keyboards has been
developed with the aim of achieving high speed and flexibility on the
production line and of avoiding the use of toxic solutions for printing
and varnishing. The marking process was developed by investigating
contrast and depth of colour change as a function of laser parameters as
well as of polymer composition. The laser-printed symbols on various
optimised polymeric materials (polystyrene, PC, ABS), both dark and
light grey, passed all computer keyboard standards tests This article
also describes the prototype system developed for industrial pilot
production. |
| Molecular beam epitaxy (MBE) as an ultra precision machining process |
| Y. Furukawa (2), A. Kakuta |
| STC E, 45/1/1996, P.197 |
| Keywords: Ultra-Precision Machining, PVD, Silicon Surface Machining |
|
Abstract : The present paper has clarified a possibility to apply a Molecular Beam
Epitaxy (MBE) to generate a geometrically flat and crystallography
aligned surface. The method is often used to /prepare /new
semi-conductive materials, however, the mechanism how a geometric
surface for mechanical use is built up by a deposition of molecules is
not known. Taking a homo-epitaxial case as an example, silicon molecular
beam was deposited onto a single crystallized silicon substrate, and
that process was investigated by the help of RHEED, vacuum gauge, etc. A
newly obtained surface had a roughness in the order of 2nm and a better
crystalline than that of substrates. |
| Assisting electrode method for machining insulating ceramics |
| N. Mohri (2), Y. Fukuzawa, T. Tani, N. Saito, K. Furutani |
| STC E, 45/1/1996, P.201 |
| Keywords: Electrical Discharge Machining, Ceramic, Conductivity |
|
Abstract : This paper deals with a new method of machining insulating ceramics by
EDM. In this method, a metal plate or metal mesh is arranged on the
surface of ceramic insulator as an assisting electrode. The ceramics can
be machined very easily with a copper electrode in sinking EDM or with
brass wire electrode in WEDM using kerosene as working fluid. Electrical
conductive compounds involving cracked carbon from working oil are
generated on the surface of the ceramics. It keeps electrical
conductivity on the surface of the work piece during the machining. Some
examples of machined products with this method are presented. The
mechanism of the machining of insulating ceramics is discussed with the
principle in the surface modification technique by EDM which has been
developed in recent years. |
STC F |
| Direct observation of micro contact behaviour at the interface between tool and workpiece in lubricated upsetting |
| A. Azushima, S. Yoneyama, T. Yamaguchi, H. Kudo (1) |
| STC F, 45/1/1996, P.205 |
| Keywords: Tribology, Lubricant, Upsetting |
|
Abstract : The trapping behavior of liquid lubricant and contact behavior of
asperities during upsetting at the workpiece-tool interface are observed
directly by means of a compression subpress which is equipped with a
transparent die made of quartz, a microscope with a CCD camera and a
video system. The experiments are carried out using cylindrical
specimens of commercially pure aluminum and liquid lubricants having
several viscosities. It is observed that at the beginning of upsetting,
the lubricant is trapped between the tool and the workpiece, and then
the asperities generated with surface roughening during plastic bulk
deformation are flattened by the flat tool. From this observation, the
change in the fraction of real contact area with reduction in height is
measured by an image processor. |
| Validation of frictional studies by double cup extrusion tests in cold-forming |
| A. Barcellona, L. Cannizzaro (2), A. Forcellese, F. Gabrielli |
| STC F, 45/1/1996, P.211 |
| Keywords: Friction Tests, Forming, Finite Element method |
|
Abstract : Studies on frictional conditions in cold-forming have shown that, for a
given lubricant, friction factor values are strongly affected by the
test method. In the present paper, different cold-forging processes of
an aluminium alloy, are modelled by a FEM numerical code using the m
values obtained by both the double cup extrusion and ring compression
tests. It appears that the m values given by the ring tests can be
effectively used in the simulation of upsetting processes, while the m
values derived by the double cup extrusion tests are more appropriate
for predictions in extrusion and closed-die forging operations. |
| A numerical model for cold welding of metals |
| W. Zhang, N. Bay (1) |
| STC F, 45/1/1996, P.215 |
| Keywords: Cold welding, Numerical Modelling, Bond Strength |
|
Abstract : Based on experimental investigations of cold welding of different metal
combinations applying various surface preparation methods,, the
understanding of the mechanisms of bond formation !n cold welding has
been improved by introducing two parameters representing the properties
of surface layers at the weld interface. Accordingly, the general model
for bond strength in cold welding earlier developed by Bay has been
extended and modified The new model presented in this paper simulates
the whole cold welding process including the deformation of base metals
and the establishment of welds bonding similar as well as dissimilar
metals. The calculated bond strengths are verified by comparing with
experimental measurements. |
| Process time reduction by means of integrated casting and rolling |
| R. Kopp / E. Doege (1) |
| STC F, 45/1/1996, P.221 |
| Keywords: Process Time Reduction, Casting Rolling, Modelling |
|
Abstract : The paper discusses the pros and cons of a process shortening in terms
of effectiveness and flexibility. A combined casting/metal-forming
process offers great potential for process shortening. This is
documented in detail for the case of the double-roller technique of
steel strip manufacture. The interlinking of casting and forming
provides an integrated analysis of the liquid phase, the solidification
process and the directlylinked forming operation which follows
solidification. The paper describes various models and their application
for the analysis of the process cycle and the resulting properties of
the product. Close attention is also given to determining the high
temperature yield stress and the heat transmission coefficient for this
ultra-high temperature forming process. |
| A study of dynamic recrystallization during hot rolling of microalloyed steels |
| J. Biglou, J.G. Lenard (1) |
| STC F, 45/1/1996, P.227 |
| Keywords: Hot Rolling, Metallurgy |
|
Abstract : One of the objectives of the steel industry is to control the
thermal-mechanical treatment to create small ferrite grains, which when
nucleating from dynamically recrystallized and conditioned austenite may
be as small as 3µm. While several hypotheses have been put forward
concerning the occurrence of dynamic recrystallization during the
process of hot flat rolling of microalloyed steels, no direct proof has
yet been provided. The accumulation of strains during strip rolling is
possibly responsible for the recrystallization mechanism. In the present
project multi-stage hot torsion and compression tests are attempted to
confirm whether the softening, observed after the third stand in a hot
strip mill, may be caused by metadynamic recrystallization. |
| Determination of the material properties of an anisotropic metal wire |
| B. Carlsson, p. Huml (1) |
| STC F, 45/1/1996, P.231 |
| Keywords: Anisotropy, Wire, Test |
|
Abstract : The material properties of cold- drawn wire are not the same in the
drawing direction as in the radial direction, due to texture
development. The anisotropy usually remains in the material after
annealing and has therefore an effect on subsequent forming operations.
This article describes a practical way of determining the parameters in
the Hill anisotropic yield criterion for a thin wire by the means of
compression tests and inverse simulation. |
| Characterization of three dimensional metal flow in extrusion process |
| M. Kiuchi (1), J. Yanagimoto, M. Victor |
| STC F, 45/1/1996, P.235 |
| Keywords: Extrusion, Die Design, FEM |
|
Abstract : This paper presents a rigid- plastic FEM code and describes its
application to flow simulation during extrusion with aims to obtain
knowledges and information usable for eliminating geometrical defects of
products. The effects of some variables like the aspect ratio of
product's cross section, the bearing length and the position of die
opening on the metal flow are studied. Results on the average extrusion
pressure and the metal flow characteristics in terms of the velocity
distribution profiles in the bearing section and the streamline patterns
are presented. From them it is possible to predict the geometric defects
of the product and find out the method to reduce them by modification of
the die geometry, e.g., bearing length. The extrusion simulation of
rectangular and angle sections is chosen to show the applicability. |
| Analysis and design of industrial hot extrusion process through square dies for manufacturing complicated Al alloy profiles |
| D.Y. Yang (2), Y.S. Kang |
| STC F, 45/1/1996, P.239 |
| Keywords: Hot Forming, Extrusion, FEM |
|
Abstract : In the analysis and design of hot square die extrusion processes,
non-steady state analysis together with temperature analysis is
recommended. In the present work, non-steady state analysis are carried
out for hot square die extrusion of some typical industrial profiles by
using the rigid-viscoplastic arbitrary Lagrangian-Eulerian (ALE) finite
element method. Since flow guide and die lands play important roles in
controlling the metal flow in the industrial practice, the related
analyses are carried out and the effects of die land and flow guide are
discussed. In order to estimate the variation of die land length, a
scheme has been developed. The scheme is applied to extrusion of
L-section without any axis of symmetry. The calculated configuration of
die land is compared with the industrial design. As an effective tool
for prediction of die wear, a wear map in introduced and demonstrated
through the examples. |
| TEUBA: A simple 3D formulation for modelling forging using the upper bound method |
| J.M. Pitt-Francis, A. Bowyer, A. Bramley (1) |
| STC F, 45/1/1996, P.245 |
| Keywords: Forging, Modelling, Upper-Bound |
|
Abstract : A method for modelling perfectly plastic metal flow within the forging
process, using the well-known upper-bound energy formulation, is
presented. The domain of the metal is described by a tetrahedral mech,
in which the velocity field is piecewise linear. It is shown that this
formulation is significantly faster than existing finite element models,
and hence can be used for early validation.
The formulation can be reversed readily and an algorithm is discussed
which allows nodes to detach from the die surface in an order which
optimizes the similarity of the reverse process to user-specified shapes. |
| Wear in hot and warm forging: design and validation of a new laboratory test |
| P. Bariani (2), G.A. Berti, L. d'Angelo, R. Guggia |
| STC F, 45/1/1996, P.249 |
| Keywords: Hot-Forging, Wear, Test |
|
Abstract : A simulative wear test for hot and warm forging tools is presented which
has been developed by the Authors with the twofold purpose of (i)
verifying the applicability cf wear micro-mechanical models in
simulation of hot and warm bulk metal forming operations using FEM codes
and (ii) evaluating wear parameters by an inverse numerical technique.
In its simple configuration, the test embodies many of the tribosytems
encountered in industrial forging operations and relevant tool wear and
failure mechanisms, such as abrasion, thermal fatigue as well as
permanent deformation of tool surface.
The paper focuses on the design of the test configuration and the
description of testing and measuring apparatuses, including those for
temperatures and heat transfer coefficient determination. Validation of
the test through test runs and determination of wear profile on tools
end the paper. |
| A method to predict the on set of necking in numerical simulation of deep drawing operations |
| R. Arrieux (2), M. Brunet, p. Vacher, T. Nguyen Nhat |
| STC F, 45/1/1996, P.255 |
| Keywords: Deep Drawing, Simulation, Anisotropy |
|
Abstract : For an anisotropic material, the principal strain directions may not
coincide with the orthotropic axes during a forming operation.
In this paper we describe a numerical method to determine the forming
limit stress surface of a sheet metal for off axes solicitations. This
method is based on Marciniak's model. Experimental comparisons show the
good accuracy of this theoretical model. Then the stress surface so
determined is introduced in a finite element calculation software in
order to detect numericaly the necking occurence during the simulation
of the drawing of a square cup. The results so got are in good agreement
with experimental data. |
| Prediction of ductile fractures occurrence in deep drawing of square boxes |
| F. Micari (2), L. Fratini, S. Lo Casto, N. Alberti (1) |
| STC F, 45/1/1996, P.259 |
| Keywords: Deep Drawing, Formability, Damage |
|
Abstract : The authors propose a new approach for the prediction of tearing in the
deep drawing process of square boxes. Such an approach is based on a
damage mechanics formulation and in particular on the yield condition
for damaging materials proposed by Tvergaard and Needleman and on a
strain controlled nucleation model. The flow rule associated to the
yield condition is introduced in a finite element explicit formulation
founded on the solution of the dynamic equilibrium equation and on an
explicit time integration scheme. By this way the developed model allows
to calculate the void volume fraction value during the deep drawing
process of square boxes and consequently to predict the insurgence of
tearing by comparing the maximum achieved void volume fraction with the
value corresponding to the coalescence of microvoids. The obtained
results have been used to construct a particular type of a- master curve
and their goodness has been confirmed by means of a set of experimental
tests. |
| Polycrystal plasticity: Application to earing in cup drawing |
| L. Anand (2), S. Balasubramanian |
| STC F, 45/1/1996, P.263 |
| Keywords: Plasticity, Texture, Earing |
|
Abstract : Constitutive equations and computational procedures which are capable of
modeling the initial and evolving anisotropy in ductile metallic
materials due to the evolution of crystallographic texture are used to
simulate the formation of earing defects during cup-drawing of
face-centered cubic materials. Comparison of the results of the
numerical simulations against existing experimental results on earing in
single crystalline sheets and in previously rolled polycrystalline
sheets show that the predictions of the number of ears and their
positions are in excellent agreement with the experiments. |
| Friction studies in sheet metal forming based on a unique die shoulder force transducer |
| K.J. Weinmann (2), S.K. Kernosky |
| STC F, 45/1/1996, P.269 |
| Keywords: Drawing, Sheet Metal, Friction |
|
Abstract : A transducer developed for measuring tension in metal strip as it moves
over the die shoulder was used to conduct friction studies. The portion
of the transducer simulating the die shoulder is cylindric and mounts in
the body on a pair of bearings. Incorporated into the design is a means
to selectively lock the die shoulder. Strip tension measurements from
tests with the die shoulder locked and unlocked are necessary before
friction information is extracted. The transducer is used in a forming
die simulator with a controlled drawbead to evaluate how drawbead
penetration speed influences die shoulder friction. |
| CNC - controlled segmented stretch forming process |
| K. Siegert (2), K.-J. Fann, A. Rennet |
| STC F, 45/1/1996, P.273 |
| Keywords: Flexible Manucturing System, Strecht Forming, Sheet Metal |
|
Abstract : A new developed stretch forming process, with several CNC-controlled two
axis grippers positioned around the punch, allows to predict the final
strength of a convex shaped sheet metal part. Outgoing from the wanted
strength over the part and the flow curve of the sheet metal, the moving
paths /of /the different grippers are calculated by a FEM simulation /of
/the forming process. These paths are corrected by data describing the
elastic behavior of the grippers. Then, the corrected data are through
DNC sent to the stretch forming machine. Experimental work shows that
this new flexible manufacturing system works well. |
| Fundamentals on the manufacturing of sheet metal micro parts |
| M. Geiger (1), F. Vollertsen, R. Kals |
| STC F, 45/1/1996, P.277 |
| Keywords: Sheet Metal Forming, Miniaturization, Process Analysis |
|
Abstract : The miniaturization of components and therefore the downscaling of metal
forming processes, as it can be observed today especially in the field
of electronics production, is closely connected with changes in the
relative contribution of those parameters which determine the forming
result, like for example the microstructural features of the workpiece
material and the roughness of workpiece and tool. In this paper some
basic considerations are pointed out concerning bending - both laser
bending and mechanical air bending - and punching. The importance of the
geometrical and the material parameters for the micro metal forming
process are pointed out using theoretical, both numerical and
analytical, as well as experimental results. From these results some
preconditions are deduced which are a basis for guidelines for sheet
metal forming processes in the field of smallest workpiece dimensions. |
STC G |
| Utilization of grinding heat as a new heat treatment process |
| E. Brinksmeier (2), T. Brockhoff |
| STC G, 45/1/1996, P.283 |
| Keywords: Grinding, Surface Hardening, Heat Treatment Process |
|
Abstract : In the past many scientists investigated the heat dissipation in
grinding and the resulting influences on the surface integrity of the
workpieces. Under abusive grinding conditions the formation of a
heat-affected zone was observed which damaged the ground surface of
hardened steels. The aim of this paper is to introduce a new surface
heat treatment process, namely by making use of the heat flux generated
in grinding. In this case the grinding conditions have to be optimized
to induce martensitic phase transformations in the surface layers of
annealed or tempered steels, such as it is achieved by other surface
strengthening processes. The fundamentals of this new heat treatment
method called /grind-hardening /are given in this paper. |
| On-line optimization for internal plunge grinding |
| G. Xiao, S. Malkin (1) |
| STC G, 45/1/1996, P.287 |
| Keywords: Grinding, Optimization, Adaptative Control |
|
Abstract : An on-line optimization system was developed for cylindrical plunge
grinding to minimize production time while ensuring part quality
requirements. The system is capable of optimizing the grinding and
dressing parameters in response to in-process and post-process
measurements which characterize the process and update the process
model. As compared with the previous system, the present one encompasses
a more complete set of realistic constraints, considers time dependent
behavior, and also optimizes the dressing interval. The system has been
implemented on an instrumented internal grinder in the laboratory and in
actual production. |
| Cooling characteristics of cutting grain in grinding |
| T. Ueda, M. Sato, K. Nakayama (1) |
| STC G, 45/1/1996, P.293 |
| Keywords: Grinding, Temperature, Measurement |
|
Abstract : The temperature of a cutting grain when cutting has been completed is
investigated experimentally and theoretically. As the model of the
cutting grain, a conical tool of ceramic is used. The temperature of the
grain at various times after cutting is measured using an infrared
radiation pyrometer with an optical fiber. The cooling process of the
cutting grain during air cutting is analyzed by reference to
unsteady-state heat transfer theory. The cooling of the grain is
extremely rapid, that is, the temperature of the grain decreases to one
fourth of the maximum temperature in 1 ms after cutting. The maximum
temperature of the cutting grain reached at the end of cutting is
estimated to be the melting point of the work material. |
| A simplified approach to control of thermal damage in grinding |
| W.B. Rowe (1), M.N. Morgan, S.C.E. Black, B. Mills |
| STC G, 45/1/1996, P.299 |
| Keywords: Grinding, Burn, CBN |
|
Abstract : The critical factors for the control of thermal damage in grinding at
conventional workspeeds have been established with reference to
experimental and previously published work. For ferrous materials,
significant damage occurs above a maximum workpiece background
temperature of 475°C. It is also known that the energy entering the
workpiece is reduced due to conduction into the grinding wheel. It has
been found that the partitioning of energy between the grinding wheel
and the workpiece remains approximately constant. However, the overall
partition ratio to the workpiece, which takes account of energy transfer
to the chips as well as energy transfer to the wheel, is variable. The
effective thermal properties of the grinding wheel may be established
by correlating theory with grinding experiments. An effective
coefficient for the temperature equation can be obtained corresponding
to the use of the geometric contact length in the equation. Using these
conclusions, a simplified approach has been developed for control of
thermal damage. |
| Modelling and optimization of vibratory finishing process |
| F. Hashimoto / D.B. DeBra (1) |
| STC G, 45/1/1996, P.303 |
| Keywords: Vibratory Finishing, Barrel, Modelling |
|
Abstract : Vibratory finishing has been employed for final finishing of products,
because of the capability of the finishing consistency with lower cost.
However, it has taken the trial and error method to find a proper
process set-up due to the fact that the fundamentals of vibratory
finishing have not been established yet. This paper describes the
fundamental principles of vibratory finishing and proposes the
mathematical modelling which makes the prediction of surface roughness
and stock removal possible. The validity of the modelling is discussed
with experimental results, and an algorithm to design an optimum process
of vibratory finishing is proposed. |
| Removal rate and surface roughness in high-precision lapping of Mn-Zn ferrite |
| M. Touge, T. Matsuo (1) |
| STC G, 45/1/1996, P.307 |
| Keywords: Lapping, Roughness, Atomic Force Microscopy (AFM) |
|
Abstract : This paper describes the effect of the motion of diamond grains on
material removal rate as well as surface roughness during lapping of
Mn-Zn polycrystalline ferrite using a Sn lapping plate and 0.5 - 2.0 µm
diamond abrasives. The diamond grains during lapping can be classified
into fixed and loose grains, where `.he grains fixed on the lapping
plate (fixed grains) can be observed by SEM. It is evident that among a
large number of experimental parameters, the pitch size of the grooves
on the lapping plate generated by facing operation has a significant
effect on the removal rate. This effect can be accounted for by the
number of loose grains calculated under various pitch sizes. The average
removal rate with fixed and loose grains is about 2.7 times higher than
that with only fixed grains, and from this result it is known that
during lapping, the work material can be removed mainly by loose grains.
It is also evident from AFM images that the lapped surface
characteristic by only fixed grains differs very much from that by fixed
and loose grains. |
| Integrated planarization technique with consistency in abrasive machining for advanced semiconductor chip fabrication |
| H. Jeong, H. Ohmori, T. Karaki Doy, T. Nakagawa (1) |
| STC G, 45/1/1996, P.311 |
| Keywords: Abrasive Machining, Integrated Planning, Pattern Topography |
|
Abstract : This paper proposes the establishment of a new integrated planarization
technique using ultrafine abrasive machining for application to advanced
semiconductor chip fabrication. The main features implemented are
integrated planarization for the silicon substrate, blanket films of
oxide and wafers with pattern topography. Planarization concepts were
brought out for these wafers with different shape and material. The
authors tried to apply not only loose-abrasive methods such as chemical
mechanical polishing (CMP), but also bonded abrasive methods such as
ductile mode grinding using ultrafine abrasives. New developments in the
proposed ultrafine machining processes were presented. Finally the use
of planarization machining techniques appropriate for each kind of wafer
produced good planar surface respectively. |
| Development of melamine-bonded diamond wheels with high porosity for smooth and mirror finishing of die materials |
| T. Semba, Y. Tani (2), H. Sato (1) |
| STC G, 45/1/1996, P.315 |
| Keywords: Diamond Wheel, Mirror Finishing, Die Material |
|
Abstract : Diamond wheels with fine grains and pore structures were newly developed
for smoothing and mirror-polishing of die materials. Diamond grains were
bonded firmly by melamine resin to prevent the decrease of machining
efficiency due to grain sinking within the bond materials. Also, highly
foamed structures were developed to increase the flexibility of the
wheel, and to induce active self-dressing by increasing contact pressure
between the wheel and work surfaces. It was confirmed that flexibility
equal to that of a conventional PVA-bonded wheel could be achieved by
increasing the porosity to over 75 %37;. Also, it was confirmed that swarf
loading of the wheel could be prevented completely and excellent
grinding performance assisted by active self-dressing could be derived
by increasing the porosity to over 75 %37;. |
| A process model for robotic cup grinding |
| W. Persoons, p. Vanherck (1) |
| STC G, 45/1/1996, P.319 |
| Keywords: Robotic Deburring, Grinding, Process Model |
|
Abstract : Robotic heavy-duty deburring is often performed with special shaped
grinding cups which allow for rapid material removal, but with secondary
concern on surface quality. The cups are not dressed and wear
constantly. Little research data is available on this grinding process.
The paper presents the results of an extensive study to model this
grinding process and presents a new, simple and fundamental process
model relating the material removal rate to such factors as the contact
force and the grinding angle. The test set-up, consisting of a hydraulic
force controlled robot and the Taguchi method to minimise the number of
tests, is described. Additionally, a dynamic model to predict the ground
profile in the presence of burrs, is presented. Based on the process
model, a strategy is proposed for the robotic deburring of small burrs
as well as for large burrs with a force controlled grinding cup. |
| Enhancing abrasive waterjet cutting of ceramics by head oscillation techniques |
| E. Siores, W.C.K. Wong, L. Chen, J.G. Wager (1) |
| STC G, 45/1/1996, P.327 |
| Keywords: Abrasive Waterjet, Head Oscillation, Ceramics |
|
Abstract : Abrasive Water Jet (AWJ) cutting technology can provide very effective
means for shape cutting of ceramics, but the slow cutting speed needs to
be improved without compromising cutting quality. In this paper,
experimental techniques based on statistical design principles and
theoretical investigations were conducted to optimise and predict the
AWJ cutting process applicable to ceramics. The new cutting head
oscillation technique applied to the cutting process produced superior
results and showed that the smooth zone depth increased by more than 30%37;
with oscillation as compared to that without oscillation and both
striation drag angle and frequency in the striation zone decreased. |
| An investigation of the AE signals in the lapping process |
| Y.P. Chang, M. Hashimura, D.A. Dornfeld (2) |
| STC G, 45/1/1996, P.331 |
| Keywords: Lapping, Material Removal Rate, Acoustic Emission Monitoring |
|
Abstract : The material removal mechanisms in lapping processes were studied. The
concepts of brittle vs. ductile machining and two-body vs. three-body
abrasion were used to classify the lapping mechanisms. The transition of
the lapping states between different mechanisms over time was
investigated as well. An acoustic emission (AE) setup was evaluated for
in-process material removal rate (MRR) monitoring. |
| Raw acoustic emission signal analysis of grinding processes |
| J. Webster, W.P. Dong, R. Lindsay (1) |
| STC G, 45/1/1996, P.335 |
| Keywords: Grinding, Acoustic Emission, Monitoring |
|
Abstract : As a different approach to most acoustic emission (AE) research in
grinding, this paper focus on analyzing the raw AE signal instead of
root-mean-square signal (RMS). Transitional characteristics of the raw
AE signal during wheel/workpiece contact in a variety of grinding
processes are discussed. Frequency analysis of the raw AE signal is
carried out based on knowing the frequency response of the sensor
employed. An assessment of the AE RMS technique with different
integration time constants is conducted in order to determine
appropriate ones for future production applications. |
| On the relationship between setup parameters and lobing behaviour in centerless grinding |
| S.S. Zhou, J.R. Gartner, T.D. Howes (1) |
| STC G, 45/1/1996, P.341 |
| Keywords: Centerless Grinding, Process Stability, Roundness |
|
Abstract : Lobing may cause significant workpiece roundness error in centerless
grinding. This paper investigates the relationship between the process
setup parameters and lobing behavior, and provides general guidelines
for selecting proper setup parameters to minimize the lobing effect. In
the paper, lobing behavior is characterized by the wave growth rate
boundaries and characteristic root distribution of the lobing loop. For
a given process setup (K,a,?), overall lobing stability of the grinding
process is evaluated by using the wave growth rate boundaries. It was
found that the characteristic root distribution of the lobing loop is
periodic, and the periodicity is determined by the peak wave frequencies
and crossing wave frequencies. This leads to the development of a
nominal stability diagram for workpiece center-height angle selection.
Also, general guidelines for minimizing the lobing effect are
introduced. The effectiveness of these guidelines is discussed
analytically and experimentally verified. |
| Grinding process simulation based on the wheel topography measurement |
| I. Inasaki (1) |
| STC G, 45/1/1996, P.347 |
| Keywords: Grinding, Simulation, Topography |
|
Abstract : The establishment of a reliable model for the grinding process is a key
issue in predicting process performance. In this study a method, based
on the optical profilometry, t o represent grinding wheel surface
characteristics i s proposed. Considering the wheel topography
information, a computer simulation of the grinding process i s performed
t o predict the ground surface roughness and the grinding force. A
characteristic feature of the simulation method is that the chip removal
process of each individual cutting edge is simulated based on the
relative motion between the grinding wheel and the workpiece. |
| Improvement of form accuracy in axisymmetrical grinding by considering the form generation mechanism |
| T. Enomoto, Y. Shimazaki, Y. Tani (2), T. Sata (1) |
| STC G, 45/1/1996, P.351 |
| Keywords: Precision Grinding, Form Accuracy, Removal Mechanism |
|
Abstract : Countermeasures are proposed to overcome the problem that, in grinding
an axisymmetrical surface, the surface profile concavely deviates from
the ideal profile. By experimentally investigating the form generation
mechanism, it was found that tine grindability deteriorated on the
outward surface owing to direct contact between the wheel bond and the
workpiece. Using a hard bonded wheel improved form accuracy, and
traversing the wheel outward from the workpiece center achieved both
high form accuracy of less than 120 nm p-v and good roughness ranging
from 20 to 40 nm Ry. |
STC M |
| Constrained predictive control for motor drives |
| D. Dumur (2), P. Boucher (2), A.U. Ehrlinger |
| STC M, 45/1/1996, P.355 |
| Keywords: Control, Machine Tools, Drives |
|
Abstract : Generalized predictive control (G.P.C.) is an efficient strategy for
machine tools applications. However, high performance may require the
consideration of constraints on the system. This paper presents a
modified version of G.P.C., called C.R.H.P.C. (Constrained Receding
Horizon Predictive Control), which imposes constraints on the final
output values, so that the output matches the reference over a further
constraint range. An important result is that theorems guarantee stable
closed loop behaviour for particular sets of tuning parameters. This
method applied to the velocity control of a motor drive proves that an
effective definition of constraints enables better results for severe
conditions of use. |
| High-response XY stage system driven by in-parallel linear motors |
| Y. Tomita, K. Makino, M. Sugimine / N. Taniguchi (1) |
| STC M, 45/1/1996, P.359 |
| Keywords: Servomechanism, Electrical Actuator, Position Control |
|
Abstract : We present our newly developed high-response XY stage system driven by
in-parallel linear motors. Briefly described are operational principles,
associated mechanical and control system design based on analysis of
stage dynamics, and typical results of system performance experiments.
Stepping motion with high-response and accurate positioning was
obtained by incorporating a force disturbance observer and
jerk-continuous trajectory generation into a conventional control
system operated under PID and acceleration feed-forward compensation.
Measurements of stage stepping motion demonstrate a highly suitable
design, e.g., in response to 2.54-mm step-motion command, positioning
error was reduced to ±10 µm in just 37 ms. |
| Design and optimization of fast axis feed drives using nonlinear stability analysis |
| O. Zirn, S. Weikert, F. Rehsteiner (1) |
| STC M, 45/1/1996, P.363 |
| Keywords: Feed Drive, Optimization, High-speed Machining |
|
Abstract : Direct drives and ball screw drives are the most promising feed drive
systems for high speed machining. For optimum performance the drives and
the feedback control system must be exploited to their physical limits.
Thus, input saturation of the feed drives becomes a very important
design parameter. A new design method based on a nonlinear stability
analysis has been developed to take this into account. The improvements
regarding machine tool design and the selection of suitable drive
systems made possible by this method are shown and discussed. |
| On the influence of the velocity gain factor on the path deviation |
| G. Pritschow (1) |
| STC M, 45/1/1996, P.367 |
| Keywords: Path Deviation, Position Control, Velocity Gain factor |
|
Abstract : The velocity gain factor k_v of a position controller decisively
determines the lag as well as the dynamic accuracy of a machine tool.
The lag is well defined by the k_v factor. There is however, a lack of
literature with a sound interpretation of the relationship between the
k_v factor and path deviation. Thus this paper concerns itself with the
influence of the k_v factor on the path accuracy, on the disturbance
behaviour of position axes and on the behaviour of a cross-coupled
controller. For comparison. the effects of prefilter technology are also
taken into consideration. |
| A practical machining condition determination strategy using multi-axis force information |
| M. Mitsuishi, T. Nagao (2), T. Ohta, H. Okabe |
| STC M, 45/1/1996, P.373 |
| Keywords: Machining, Chatter, Force Information |
|
Abstract : A manufacturing system which integrates a machining center with a
multi-axis force sensor and real-time controller, CAD system and
data-base was developed to realize high precision and high efficiency
autonomously. To realize highly efficient machining while maintaining a
stable cutting state, both a real-time adaptive control function and
learning capability were implemented. Learning behavior was obtained
by storing the actual state of the system in the form of an
experimentally-determined stability lobe diagram. Efficient machining
conditions, including the detailed tool path, were dynamically realized
by regenerating the tool path periodically. Experimental results showed
the effectiveness of the system. |
| Real-time open control architectures and system performance |
| Y. Koren (1), Z.J. Pasek, A. Galip Ulsoy (2) |
| STC M, 45/1/1996, P.377 |
| Keywords: Control, Machining, Real Time |
|
Abstract : This paper analyzes the effect of control architectures and
communication networks on a manufacturing system's performance in terms
of part precision and productivity; the network bandwidth requirement
for a distributed control system is also included. The objective is to
design the system such that the control and communications (both
hardware and software) would not be the limiting factors in system
performance. For simplicity we analyze the performance of a machining
center control system. The base-line for comparison is a conventional
computerized numerical controlled (CNC) with discrete event
management/adaptive system. |
| Toward virtual engineering in machine-tool design |
| G. Bianchi, F. Paolucci, p. Van den Braembussche / F. Jovane (1) |
| STC M, 45/1/1996, P.381 |
| Keywords: Integrated Computer Aided Design, Machine Tool, Simulation |
|
Abstract : An integrated modeling technique for high speed machine tool design is
proposed. The model contains a description of the structure, derived
from a Finite Element. Model via modal reduction, compliant guideways
with static and dynamic friction, and a continuous or discrete time
controller. This modeling tool permits designers to evaluate, during the
first stages of design, how the mechanical structure and control
contribute to the dynamic behavior of the machine, estimating, for
example, the dynamic compliance at the tool, the lost motion due to
friction and the tracking error during acceleration. |
| Development of machine components with controllable dynamic behaviour |
| J. Peklenik (1), J. Jurkovic |
| STC M, 45/1/1996, P.385 |
| Keywords: Composite, Structure, Control |
|
Abstract : The paper reports on the development of composite materials suitable for
machine tool modules. Several combinations of materials, geometric
forms, dimensions and gluing techniques have been used for producing the
basic elements - the composite plate structures (CPS). The investigation
is focused into determining the static and dynamic properties of
CPS-boxes, in particular, the ratios between the stiffness and weight,
the resonance damping, the ratios of the resonance stiffness and mass
for the CPS and conventional test boxes. |
| Machine tool design requirements for high speed machining |
| U. Heisel (2), M. Gringel |
| STC M, 45/1/1996, P.389 |
| Keywords: High Speed Machining, Machine Tool Design, Kinematic |
|
Abstract : The high speed machining process requests completely new demands for the
mechanism of such processing equipment, as due to the process, path
speeds exceeding 50 m/min can be achieved. In this field, potential
capacities of manufacturing processes require a dynamic behaviour ten
times higher than conventional machine tools and increased accuracy.
This can be solved by the systematical evaluation of suitable machine
kinematics, by the application of linear direct drives with high
k,-factors as well as by mass reduction of the axis through light weight
components of sheet metal. |
| Techniques for the use of long slender end mills in high-speed milling |
| J. Tlusty (1), S. Smith, W.R. Winfough |
| STC M, 45/1/1996, P.393 |
| Keywords: End Milling, High Speed Machining, Technique |
|
Abstract : This paper presents two techniques using end mills in high-speed
milling. In the first, the top speed and power of the spindle are
accepted as fixed, and the structural dynamics are manipulated by
adjusting the tool length so as to take advantage of stability lobe
effects. Sometimes, lengthening the tool improves the metal removal
rate. The second technique permits the machining of parts with very thin
ribs. Tools with relieved shanks are used to avoid increases in axial
depth of cut associated with forced vibration of the rib. Photographs of
parts made with and without such tooling are shown. |
| Development of an intelligent face grinding machine to fabricate ultra-flat surfaces on thin, brittle substrates |
| M. Nakao, Y. Hatamura (2) |
| STC M, 45/1/1996, P.397 |
| Keywords: Intelligent Control, Face Grinding Machine, Conceptual design |
|
Abstract : Information processing devices require thin and brittle substrates with
surface flatness in the order of 0.1 ,u m per 200 x 200 mm. To realize
such ultra-flatness, we designed, fabricated, and evaluated an
"intelligent face grinding machine". The machine is a vertical spindle
face grinding machine which we newly constructed to have higher rigidity
and thermal insensitiveness for passive reduction in tool positioning
error. In addition, an active knowledge-based control system with
sensors, computers and actuators further reduces the deviation. We
verified that the machine produces flatness of 0.5 _p m per 200 x 200 mm
on ceramic, glass and silicon substrates. |
| Ultraprecision 3-D micromachining of glass |
| Y. Takeuchi (2), K. Sawada, T. Sata (1) |
| STC M, 45/1/1996, P.401 |
| Keywords: Ultra Precision, Micromachining, Brittle Materials |
|
Abstract : It has been theoretically and experimentally confirmed that brittle
materials can be machined in the ductile mode under the certain small
depth of cut. However, it is extremely difficult to obtain tiny 3D
workpiece shapes of brittle materials with high surface accuracy. The
study deals with the ultraprecision 3D micromachining of glass workpiece
by means of a lathe-type ultraprecision milling machine and pseudo ball
end mills. As a result, it is possible to obtain a glass mask of 1 mm in
diameter with the surface roughness of 50 nm. |
| Robotic deburring of small series of castings |
| W. Persoons, H. Van Brussel (1) |
| STC M, 45/1/1996, P.405 |
| Keywords: Deburring, Off-line Robot Programming, Force Control |
|
Abstract : Robotic cleaning of castings is currently limited to large series of
parts with small burrs. The costs for fixtures and clamping and for
online programming of the robot largely exceed the potential savings of
using robots for small series. Less expensive fixtures only add to the
positioning uncertainties by which the use of online programmed robots
becomes prohibitive.
The paper presents a robotic deburring system for small series of
heavy-duty castings with large burrs and risers. Strategies are
presented to cope with large burrs and with the allowed large position
uncertainty of the casting. CAD data of the nominal castings is used to
program the robot offline, resulting in reduced programming time. Active
force control is used for burr detection and for coping with
uncertainties in the casting position. The test set-up consists of an
offline-programmed, hydraulic, force-controlled robot and an example of
the cleaning of a gray iron casting of a heavy-duty crank case for a
truck is presented. |
| Artificial intelligence tools in diagnostics of machine tool drives |
| J. Jedrzejewski (1), W. Kwasny |
| STC M, 45/1/1996, P.411 |
| Keywords: Artificial Intelligence, Diagnostics, Machine Tool |
|
Abstract : Diagnostics of machine tool drives aided with an expert system and
neural network and allowing for a variety of drive conditions and
diagnostic signals is discussed. An actual solution is presented of a
drive self-diagnosing system consisting in on-line temperature- and
power-based monitoring supplemented by detailed off-line diagnostics
backed by Al tools and knowledge bases and invoked in need only. The
detailed diagnostics is based on power and acoustic noise measurements
and involves data base propagation, a customized diagnosing algorithm, a
mechanism of automatic inferring using fuzzy logic procedures and
simulation of the inferring mechanism by a neural network. The
exposition is completed by a working example of drive diagnostics
application in a machining centre. |
STC O |
| Towards a new model of sustainable production : ManuFuturing |
| C. Boër (2), F. Jovane (1) |
| STC O, 45/1/1996, P.415 |
| Keywords: Integrated Production Systems, Virtual Factory Network, Sustainable Production |
|
Abstract : Mutations of the context : economy, society, technology ; call for
continuous changes of products and related processes. Industry response
must range from strategic to tactic horizons. The growing importance of
environment and social aspects has lead to the emergence of the life
cycle concept and to Sustainable Industrial Production. The
Products-Processes life cycle matrix must then change to respond to
mutations of the context. It may follow a stepwise path combining
innovation (new generations) and evolution (within a generation). An
appropriate system is required: the Virtual Factory. It "produces" and
"maintains" new generations. The combination of a Virtual Factory and a
Physical Factory, is the Self-Innovating Factory (SIF). Because of
products-process complexity, networks, made up of "physical factories",
are emerging. To respond to context changes, appropriate, Virtual
Factories networks should be implemented. The integration of both
networks would lead to the Self-Innovating Extended Factory (SEIF),
capable of responding to context changes, as required by Sustainable
Production Paradigm. The model described has been named MANUFUTURING.
The main phases to implement and some of the methods and tools to
support it, have been described. The model has been adopted by an
industrial group to develop its next generation of manufacturing systems. |
| An integrated approach to the design of cellular manufacturing |
| H. Kaebernick, M. Bazargan-Lari / G. Arndt (1) |
| STC O, 45/1/1996, P.421 |
| Keywords: Manufacturing, Cellular, Layout |
|
Abstract : The realisation of benefits expected from Cellular Manufacturing (CM)
largely depends on how effective the three phases of the design have
been performed, namely parts/machine grouping, the layout of machines
within cells, and the layout of cells on the shop floor. These phases
have been studied and addressed by both practitioners and researchers
separately with little or no feedback from one phase to another. The
multi-criteria model presented in this paper attempts to address and
evaluate the impact of each phase on the other phases, and in particular
on the overall performance of the CM, by generating alternative
efficient designs. The performance of the model is demonstrated by
applying it to an example and to the implementation of CM in a
white-goods manufacturing company. |
| Reengineering production systems: the Royal Netherlands Naval dockyard |
| W.H.M. Zijm / H.J.J. Kals (1) |
| STC O, 45/1/1996, P.427 |
| Keywords: Engineering, Production System, Maintenance |
|
Abstract : Reengineering production systems in an attempt to meet tight cost,
quality and leadtime standards has received considerable attention in
the last decade. In this paper, we discuss the reengineering process
at the Royal Netherlands Naval Dockyard. The process starts with a
characterisation and a careful analysis of the production system and the
set of objectives to be pursued. Next, a new production management
structure is defined after which supporting planning and control systems
are designed and a number of organisational changes are carried through.
In this way, the Dockyard may combine high technological capabilities
with an excellent logistic performance. |
| A market approach to holonic manufacturing |
| A. Markus, T. Kis, J. Vancza, L. Monostori (2) |
| STC O, 45/1/1996, P.433 |
| Keywords: Holonic Manufacturing, Dynamic Schedulling, Artificial Intelligence |
|
Abstract : The concept of holonic manufacturing is based on the cooperation of
autonomous, functionally complete entities with diverse, often
conflicting goals. The paper introduces a market mechanism for
coordinating the activities of intelligent agents that pursue their own
interest by operating under bounded rationality in a changing, hardly
predictable environment. The market model is used for solving dynamic
order processing and scheduling problems: conflicts between local
scheduling agents are resolved by negotiating and bargaining on simple
common terms of tasks, due dates and prices. |
| An approach to holonic components in control of machine tools |
| A. Bengoa, S. Gluch, H.J. Jacobs / R. Bueno (1) |
| STC O, 45/1/1996, P.437 |
| Keywords: Holonic, Control (CNC), Computer Automated Process Planning (CAPP) |
|
Abstract : This paper describes a first step in transfer of machine tools to
HOLONIC MACHINING UNITS (HMU). The solution proposed is based on
dynamic, NC-internal self-planning of cutting conditions. Supposing this
approach, real time adaption of the required machining time to the
available time budget can be carried out. In this way the autonomous HMU
is able to survive disturbances without any reaction on
job-shop-control. Cooperation of machine tools with the same properties
to fulfil an order is possible, too. The first soft- and hardware
implementation of holonic behaviour within a machine tool's CNC is
represented by the so-called Optimizing Controller. |
| Continuous flow models of manufacturing systems: a review |
| P. Brandimarte, A. Sharifnia, B.F. Von Turkovich (1) |
| STC O, 45/1/1996, P.441 |
| Keywords: Optimization, Modelling, Production Control |
|
Abstract : Production scheduling approaches in discrete manufacturing environments
must cope with discrete material flows subject to different constraints
in order to obtain a good solution. Despite the huge amount of
literature on machine scheduling, most commercial schedulers take a
myopic approach based on priority rules. Among the reasons behind this
gap there are issues related to the complexity of optimized scheduling
methods and the vulnerability to schedule disruptions. In the paper we
review some approaches aimed at bridging the gap between optimization
models and real time control. Such models are based on an approximation
of the discrete material flow with a continuous flow. We review
stochastic control models for repetitive production and mixed-integer
programming models for batch manufacturing. |
| Modelling and analysis of heterarchical manufacturing systems using discontinuous differential equations |
| V.V. Prabhu, N.A. Duffie (2) |
| STC O, 45/1/1996, P.445 |
| Keywords: Manufacturing, System, Control |
|
Abstract : Heterarchical manufacturing systems with distributed arrival time
control provide robustness by adapting to disturbances in real time
without explicit notification and compensation. Part processing
discontinuously couples entities in these systems and makes their
behavior highly nonlinear. Discontinuous differential equations that
model the dynamics of a multitude of highly distributed part arrival
time controllers can be solved using a method due to Filippov, resulting
in closed-form equations that characterize system dynamics and
convergence. The global performance of the distributed arrival time
control is found to compare favorably with dispatching rules currently
used in industry. |
| Model driven configuration and information sharing in concurrent engineering |
| R.H. Weston (2) |
| STC O, 45/1/1996, P.449 |
| Keywords: Modelling, Co-ordination, Integrated Computer Aided Manufacturing |
|
Abstract : Interim research findings are described concerned with:
- consolidating and developing modelling methods and tools, which
support the design and implementation of integrated systems.
- identifying requirements for modelling `resources', to support the
engineering of manufacturing enterprises.
The research is funded jointly by the CDP committee of EPSRC and UK
industry and is being advanced in conjunction with a consortium of
manufacturing user organisations and their software and system suppliers. |
| Hierarchical part planning strategy for environmentally-conscious machining |
| P. Sheng, M. Srinivasan / G. Chryssolouris (1) |
| STC O, 45/1/1996, P.455 |
| Keywords: Machining, Environmental, Planning |
|
Abstract : Integration of environmental considerations into the part planning
process occurs at two levels: microplanning (intra-feature) and
macroplanning (feature interaction). Microplanning involves the
selection of processes, parameters, tooling and catalysts to generate a
single geometric feature. Macroplanning involves feature interactions
under resource constraints which may have significant consequences in
energy and waste generation, including precedence relationships between
features and clustering among common setups, tooling and catalysts. This
paper presents an overview of a hierarchical part planning strategy for
environmentally conscious machining. A case study of a machined
component will be developed to illustrate feature interaction issues.
The robustness of process planning under uncertainty in environmental
impact evaluation will also be addressed. |
| A collaborative scheduling system for make-to-order manufacturing |
| K.I. Lee (2), M. Kang, J.H. Park |
| STC O, 45/1/1996, P.461 |
| Keywords: Production Control, Job Shop, Co-operative Scheduling |
|
Abstract : In the make-to-order manufacturing industry, the details about the
product specification become gradually known in phases from development,
design, and process planning. This makes the production scheduling less
accurate, and causes the operations schedule to be revised frequently
during the manufacturing. To reconfigure the existing schedule, the
monitoring data collected from the shop floor are essential. A
collaborative scheduling system for the job shop has been developed to
manage the job processing effectively. The system adopts presumptive,
predictive and reactive scheduling methods. Each method is built into a
module which performs scheduling based on the different data, and
collaborates with other modules. The scheduling system is interfaced to
a machine monitoring and data collection system. The experience of the
implemented system in a factory is encouraging. |
| A new hybrid method for part-family development |
| W. Massberg (1), R. Künzel |
| STC O, 45/1/1996, P.465 |
| Keywords: Group Technology, Part-family Development, Statistical Analysis |
|
Abstract : While rationalization measures used to concentrate on technological
improvements.. organizational and structural approaches are becoming
more and more important. On the one hand companies can be forced to
restructure their production areas into group-technology based
manufacturing concepts. On the other hand enterprises can also be
obliged to estimate their potential for the outsourcing of manufacturing
tasks in order to establish common outside suppliers together with
suitable partner companies. For all these tasks the development of
suitable part-families can be considered as the essential means to ease
the restructuring processes or to support the required decision taking.
Accordingly this paper presents a new hybrid method for part-family
development. which is based on a combination of a modified
COSINE-classifier-network (hierarchical analysis) and the
FUZZY-clustering procedures (non-hierarchical analysis). Such an
efficient procedure involves obtaining a fast classification result,
which contains more transparent planning information dealing with a
large amount of workpieces. |
| Multi objectives approach for process plan selection in IMS environment |
| S. Noto La Diega (1), G. Perrone, M. Piancentini |
| STC O, 45/1/1996, P.471 |
| Keywords: Process Plan, Integrated Manufacturing System, Fuzzy Programming Model |
|
Abstract : In Integrated Manufacturing Systems (IMS) evaluating the most suitable
process plan is a very complex task. Technology, quality, production and
market requirements are objectives to be pursued in the selection
process, subject to the constraints due to the several part types
simultaneously manufactured. The paper proposes a new approach to the
process planning selection, based on a possibilistic fuzzy programming
model in order to face the vagueness coming from the formalization of
the objectives and constraints in the selection problem. |
| Generation of modified cutting condition using neural network for an operation planning system |
| M.W. Park, H.M. Rho (2), B.T. Park |
| STC O, 45/1/1996, P.475 |
| Keywords: CAPP, Cutting Condition, Neural Network |
|
Abstract : For the rational scheduling of production in discrete machining shop,
standard time needs to be estimated correctly. The estimation depends on
the accuracy of cutting condition. Machinists usually make modifications
to recommended cutting conditions suggested by process planner in order
to satisfy requirements for individual operation. The systematization
of/ /the modification procedure by using neural network methodology is
proposed in this paper. Also. other key functions of the operation
planning system for prismatic components which includes the module for
cutting condition are briefly described. The results of operation
planning are demonstrated with an example part. |
STC P |
| Towards instrument-oriented calibration of CMMs |
| A. Balsamo (2), M. Di Ciommo, R. Mugno, S. Sartori (1) |
| STC P, 45/1/1996, P.479 |
| Keywords: CMM, Calibration, Uncertainty |
|
Abstract : The calibration of CMMs has become a more and more important matter of
investigation and discussion stimulated by the increasing demand of
calibration in manufacturing. CMM errors are very complex to describe in
simple terms suitable to be stated in a calibration certificate; even
more complex is the evaluation of uncertainties of these errors and of
their combination. This paper proposes a methodology which enables a
simple representation of CMM errors in terms of scale factors, and of
their uncertainties in terms of binomials, intended to meet the
requirements of brevity and simplicity of a calibration certificate. A
numerical example is given of the actual calibration result of a CMM. |
| Accuracy limitations of fast mechanical probing |
| W.P. van Vliet, P.H. Schellekens (2) |
| STC P, 45/1/1996, P.483 |
| Keywords: Mechanical Probe System, Impact Damage, Dynamic Error |
|
Abstract : Although dynamic errors of CMMs are getting more attention now, still
little is published about the dynamic disturbances acting on mechanical
probe systems. The process of mechanical probing is subject to dynamic
influences, even at generally accepted low measurement velocities. It
will be shown that due to the nature of the mechanical probing
principle, impact forces are much higher than measurement forces and can
result in considerable damage of workpiece surfaces. Further it is
proved that the relation between the position of the probe tip and the
workpiece position during impact cannot be determined unambiguously due
to bouncing, irrespective of the probe construction. Consequently
measurement accuracy can be lost, depending on the principle of
probing. Analysis shows that this bouncing effect cannot be avoided
during probing and therefore should be taken into account to improve
probe performance. Measurement results obtained with two different probe
systems will be presented to illustrate those impact phenomena. Based on
these results recommendations for probe system design are given in order
to speed-up probe operation without degradation of probe performance. |
| A multi channel diode-laser-interferometer for displacement measurements on a CMM |
| A. Abou-Zeid, K.-H. Bechstein, C. Enghave / H. Kunzmann (1) |
| STC P, 45/1/1996, P.489 |
| Keywords: Laser, Measurement, Multi-Interferometry |
|
Abstract : The increasing demands in the manufacturing measuring technique
concerning the accuracy of the production components and the precision
of the manufacturing measuring progress make it necessary to find a
precise and rapid measuring method that can be integrated into the
production machine. The use of laser diodes in the measuring technique
has advantages as well as disadvantages. This paper describes the setup,
performance and testing of a Fabry Perot Interferometer-stabilized diode
laser (FPI) as a light source in an interferometer as well as a
transportable lambdameter, and a weather station for calibration of the
laser wavelength in air. For length measurements in two axis on a
coordinate measuring machine, a two-axis multi function laser
interferometer using the FPI-stabilized diode laser was developed and
tested under respectively laboratory and workshop conditions. |
| Measurement uncertainty limit of a video probe in coordinate metrology |
| S.W. Kim / P.A. Mc Keown (1) |
| STC P, 45/1/1996, P.493 |
| Keywords: CMM, Inspection, Vision |
|
Abstract : Video probes are increasingly used in recent industrial applications of
coordinate measuring machines, since they are found more efficient than
conventional bail-tip probes especially in inspecting small-sized
features of complex shapes. However, no thorough investigation has yet
been accomplished to comprehend the measuring capabilities of video
probes. In this paper, analytical and experimental approaches are made
to explore how the measuring uncertainty limit of video probes is
determined by major design parameters related to imaging optics,
coherence of illumination, and edge detection algorithms using a CCD
array. Finally an exemplary optimal design is discussed to demonstrate
that an ultraprecision measurement of 0.01 µm uncertainty can be
practically achieved. |
| Micro-machined profile measurement by means of optical inverse scattering phase method |
| T. Miyoshi, Y. Takaya, K. Saito (2) |
| STC P, 45/1/1996, P.497 |
| Keywords: Optical Measurement, Ultra-Precision, Micro-Profile |
|
Abstract : A new optical measuring method based on the inverse scattering phase
retrieval is presented in this paper, which will be able to be applied
to in-process measurement of micro-machined surface profile with an
accuracy of nanometer order. In order to verify the validity of the
proposed method, first, computer simulations of reconstruction of the
different fine groove models are performed. Second, the inverse
scattering phase construction system is developed and the measurements
of the symmetric and non-symmetric fine triangular grooves which is
micro-machined by ultra precision diamond turning are carried out.
Consequently, it is found that the proposed measurement method is
effective for reconstructing the profile of a submicrometer size
workpiece without scanning a probe or a stylus. |
| A twist-roller friction drive for nanometer positioning: a simplified design using ball bearings |
| H. Mizumoto, S. Arii, A. Yoshimoto, T. Shimizu, N. Ikawa (1) |
| STC P, 45/1/1996, P.501 |
| Keywords: Nanotechnology, Precision Machine, Position Accuracy |
|
Abstract : The authors have reported in a previous paper that the twist-roller
friction drive can realize subnanometer positioning resolution.
However, a structural difficulty of the device is that hydrostatic
bearings are used to support the twist-rollers. The present paper
describes how the structure of the twist-roller friction drive can be
simplified by using ball bearings to support the twist-rollers. Even
with this simplification, the experiments showed that the positioning
resolution is less than one nanometer. The paper concludes that the
twist-roller friction drive /of /ball bearing type facilitates the
manufacture /of /a nanometer positioning system which can be used in a
clean environment, and can take the place of the ball screw or capstan
friction drive. |
| Ultraprecision feed system based on walking drive |
| T. Moriwaki (1), E. Shamoto |
| STC P, 45/1/1996, P.505 |
| Keywords: Ultra-Precision Feed, Actuator, Control |
|
Abstract : A new ultraprecision feed drive system has been developed based on a
driving mechanism named walking drive. The feed system utilizes sets of
clamping and feeding units driven by piezoelectric actuators, which are
activated repeatedly with certain phase shifts just like the walking
motion of animals, The characteristic features of the system are
continuous and smooth motion for the whole stroke of the guide, fine
resolution down to nm order and high stiffness in the feed direction.
The paper presents the mechanism of the feed system developed, the
control method of the system and some experimental results. |
STC S |
| On material removal mechanisms in finishing of advanced ceramics and glasses |
| R. Komanduri (1) |
| STC S, 45/1/1996, P.509 |
| Keywords: Ceramic, Finishing, Mechanism |
|
Abstract : Fundamental considerations on the interactions between the abrasive and
the work material as well as the micromechanisms of material removal and
surface generation process in finishing of advanced ceramics and glasses
are addressed. In developing plausible mechanisms, an attempt is made to
delineate the failure mechanisms operable in polycrystalline ceramics
and glasses versus metals. This is necessary because of the significant
differences in the nature of bonding, restrictions on the extent of
plastic deformation (including the number of independent slip systems
required), microstructure, tribochemistry, and, flaws generated during
processing of these materials and their consequent effect on the failure
mechanisms associated. |
| Scale-sensitive fractal analysis of turned surfaces |
| C. Brown, W.A. Johnsen, R.M. Butland / J. Bryan (1) |
| STC S, 45/1/1996, P.515 |
| Keywords: Machined Surface Texture, Topographic Analysis, Surface Roughness |
|
Abstract : Scale-sensitive analyses using length-scale relations, which have been
developed from fractal geometry (coastline, compass or Richardson
methods), are applied to a series of turned surfaces with a range of
feeds per revolution. This length-scale analysis method calculates the
apparent lengths of profiles as a function of the scales of measurement.
The profiles are acquired by conventional, stylus profiling. It is shown
that this length-scale method can be used to identify the periodic
components of profiles and that it is able to distinguish changes in the
character of the surface roughness as a function of scale. |
| Subsurface damage distribution in ultraprecision machined CdS |
| D.A. Lucca (2), C.J. Maggiore, R.L. Rhorer |
| STC S, 45/1/1996, P.519 |
| Keywords: Surfaces, Ultra-precision Machining, Subsurface Damage |
|
Abstract : The extent and distribution of the subsurface damage in ultraprecision
machined CdS was examined by the use of ion channeling using glancing
angle detector positioning to provide enhanced depth resolution. Single
crystal (0001) oriented CdS was diamond turned over the range of depths
of cut of 0.1 - 10 µm, and subsurface lattice disorder was examined for
regions cut parallel to, and 30 degrees off, a preferred cleavage plane.
Damage depths for the crystals machined along a preferred cleavage plane
were found to be consistently larger than those machined 30 degrees off
the plane. |
| Investigation on the surface topography in polishing using atomic force microscopy |
| L. De Chiffre (2), H.N. Hansen, A. Bronstein |
| STC S, 45/1/1996, P.523 |
| Keywords: Polishing Process, Surface topography Analysis, Atomic Force Microscopy (AFM) |
|
Abstract : An investigation was carried out on the surface topography generation in
polishing. Hardened tool steel specimens were polished using different
parameters and the surface topography was examined using an Atomic Force
Microscope (AFM). Measurements using AFM were initially compared to
measurements obtained with a stylus instrument and with an optical
profilometer. Contour plots were produced and a number of
three-dimensional roughness parameters calculated for each surface. A
statistical analysis of the results pointed out the most critical
parameter with respect to all roughness parameters, for the material and
hardness considered in this investigation, to be the grain size. The
process parameters polishing cloth, lubricant, speed and pressure were
found to have varying statistical significance with respect to the
different roughness parameters. The roughness parameters Sa and Sk were
found to be good indicators of the effect of varying the process
parameters. An investigation was subsequently carried out on the surface
topography generation as a function of the polishing time, for different
grain sizes. Good reproducibility of the roughness parameters was found
in two different specimens series. Most of the parameters' decrease
takes place during the first 100-200 seconds of polishing. |
| Function-oriented lapping and polishing of ceramic rolling elements through characterization of the workpiece surface |
| E. Westkämper (1), H.-W. Hoffmeister |
| STC S, 45/1/1996, P.529 |
| Keywords: Lapping, Ceramic, Roughness Parameter |
|
Abstract : Ceramic materials are exceptionally well suited for highly loaded
functional surfaces. Their brittleness, however, requires exact
knowledge of those cuttig conditions ensuring compliance with the
requested function since the surface topography is of decisive
importance for the later functional behaviour. On the example of lapping
and polishing of ceramic rolling elements, the relationship between
surface topography and rolling wear is demonstrated. A comparison of
conventional and newly developed roughness parameters for evaluating the
rolling wear shows that descriptive wear models can only be built up
with new roughness parameters. First results obtained with a new
roughness parameter are presented. |