THE INTERNATIONAL ACADEMY FOR PRODUCTION ENGINEERING
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CIRP ANNALS 1994 |
GO TO STC: A C Dn E F G M O P S Cross-STC |
STC A |
| A reconfigurable assembly cell for mechanical products |
| F. Giusti (1), M. Santochi (1), G. Dini (2), A. Arioti |
| STC A, 43/1/1994, P.1 |
| Keywords: Automated Assembling, Flexible Assembly Machine |
|
Abstract : This paper describes the main structural characteristics and the
performance of an assembly cell able to accomplish an automated
reconfiguration in function of the mechanical product to be assembled.
This cell is composed by three baseplates, a pneumatic screwing unit, a
hydraulic press and other devices for the complete automation of the
assembly operations. The handling functions are performed by a six-axes
robot. Particular emphasis has been given to the development of
interchangeable fixtures, based on modular elements, which can be easily
manipulated by the robot's arm and placed on the workstations of the
cell in order to locate, clamp and assembly the product.Finally, some
experimental tests concerning the assembly of two products and the
capability of a robotized reconfiguration of the system are described. |
| Knowledge of selecting assembly cell components and its distribution to CAD and an expert system for processing |
| H. Bley, S. Dietz, N. Roth (2), G. Zintl |
| STC A, 43/1/1994, P.5 |
| Keywords: CAPP, Data Acquisition, CAD |
|
Abstract : During planning an assembly cell, either mechanized or manually driven,
knowledge describing the necessities of assembly operations and the
capabilities of the future equipment is essential. This domain is
analyzed, structured and transformed in order to be processed by an
appropriate software system. With this the devices are characterized and
selected referring to the specific process demands derived from a
product analysis. Geometrical and technological data are to be
considered by available software (such as CAD) or specially developed
modules. The extension of the CAD system in combination with an expert
system improves the efficiency of the planning process as well as the
reliability of its result. |
| Disassembly oriented assessment methodology to support design for recycling |
| E. Zussman, A. Kriwet, G. Seliger (2) |
| STC A, 43/1/1994, P.9 |
| Keywords: Disassembling, Assessment, Environment |
|
Abstract : This paper describes an assessment methodology to support product design
for the "end-of-life" phase. It is based on the assessment of feasible
options for disassembling a product and applying recycling processes to
its components and subassemblies. The methodology balances the future
effort to be invested in recycling processes with the future benefit
regainable by reduction of dumping fees and sale of recovered materials,
components and subassemblies. It identifies the optimal recycling
strategy for a given product with respect to multiple economical and
environmental objectives of the designer. The assessment aids the
designer by allowing him to compare design alternatives and identify
weak spots of the design. The methodology is illustrated by assessing
alternative future scenarios for the recycling of a washing machine
subassembly. |
| Analytical and experimental research on assembly systems for molded interconnection devices (3D-MID) |
| K. Feldmann (2), A. Brand |
| STC A, 43/1/1994, P.15 |
| Keywords: Flexible Assembling, Electronic Production, Process Control |
|
Abstract : The integration of mechanical and electronic functions into three
dimensional circuit boards leads to innovative areas of application and
possibilities. This obviously is a topical challenge for development of
adapted assembly and soldering processes. To solve these problems.
analytical and experimental research work is going on with emphasis on
mounting SMD's on inclined planes and solderability on thermoplastic
devices. Therefore the alternatives of using industrial robots and
enlarged SMD-machines are investigated, with the objective to develop
new problem orientated Assembly Systems. |
| A methodology for part feeder design |
| M.Y. Yeong, W. De Vries (2) |
| STC A, 43/1/1994, P.19 |
| Keywords: Assembly, Design, Parts Feeding |
|
Abstract : A design methodology is presented encompassing the selection,
configuration and parametric aspects of parts feeder design. Utilizing
analytical. numerical and design tools, the methodology serves as a
framework from the initial conceptual stages of design to the design
iterations necessary to optimize the design. A case study illustrates
this methodology. |
| Automatic determination of bending sequence in sheet metal products |
| M. Shpitalni (1), D. Saddan |
| STC A, 43/1/1994, P.23 |
| Keywords: CAPP, Sheetmetal, Bending |
|
Abstract : The bending stage is the most complex and critical stage in
manufacturing sheet metal products. Moreover, the automatic
determination of the herding sequence is essential within the framework
of process planning. Basic examination of the problem immediately
reveals that the determination of the bending sequence is a
combinatorial problem. Furthermore, it is coupled with the problem of
selection of the bending tools. In this paper, the problem of automatic
tool selection and bending sequence determination is formulated as a
graph search problem. Heuristics, reduction techniques and search
methods based on the A-star search algorithm were used to accelerate the
solution. The results are superior to previously published results. |
| Vibration assisted engagement for parts mating |
| M.C. Leu (2), Z. Katz (1) |
| STC A, 43/1/1994, P.27 |
| Keywords: Mating, Vibration |
|
Abstract : Mating of parts in automated assembly can be assisted by introducing a
vibration to one of the mating parts when engagement does not occur. In
this paper we will present an analytical and experimental investigation
of vibration-assisted parts mating process. In the analysis we will
determine the parameters of vibration, including increment of amplitude
and number cf cycles, as functions cf the parameters that represent the
positional uncertainty and tolerance of the assembly system, for
ensuring engagement success. We will also describe the experiments that
we perform to validate our analysis and to generate further knowledge
contributing to the understanding of this assembly process. |
| Interconnection of insulated fine wire for PCB |
| T. Arai (2), T. Kawana |
| STC A, 43/1/1994, P.31 |
| Keywords: Bonding, Wiring, Polymer |
|
Abstract : High density assembly of PCB (Printed Circuit Board) is essential to
small-size electronic devices. This paper reports on the interconnection
of insulated fine wires of 20-100 micrometer diameters. Three new
techniques are discussed: first, the thermal decomposition of high
polymer is evaluated quantitatively; second, conditions for solid-state
bonding of copper is studied using recrystallization growth rate
equation and temperature simulation by FEM; lastly the current control
unit for micro resistance bonding is developed. An interconnection
machine has been developed, which decomposes high polymer insulation of
wires by a CO2 laser and bond them without thermal damage of PCB. |
STC C |
| Study on elliptical vibration cutting |
| E. Shamoto, T. Moriwaki (1) |
| STC C, 43/1/1994, P.35 |
| Keywords: Vibration, Cutting, Chip |
|
Abstract : The paper presents a new cutting method named "Elliptical Vibration
Cutting". Synchronized two-directional vibration is applied to the
cutting edge in the plane including the cutting direction and the chip
flow direction. The chip formed is mainly pulled out by the tool while
the tool moves in the chip flow direction, and then the tool is restored
to the cutting point without cutting in each cycle of the vibration.
Orthogonal cutting experiments of copper are carried out within a
scanning electron microscope, and it is observed that the chip thickness
and the cutting force are reduced remarkably by applying the method
proposed. |
| Effect of crystallographic orientation on cutting forces and surface quality in diamond cutting of single crystal |
| Z.J. Yuan (1), W.B. Lee, Y.X. Yao, M. Zhou |
| STC C, 43/1/1994, P.39 |
| Keywords: Crystallographic Orientation, Single Crystal, Cutting Force |
|
Abstract : As the depth of cut in ultraprecision machining is usually less than the
average grain size of a polycrystalline aggregate, cutting is performed
within a grain. Single crystals are known to be highly anisotropic in
their physical and mechanical properties. In this paper, the effect of
crystallographic orientation of the substrate material on cutting forces
and surface quality in diamond cutting of single crystal copper and
aluminium has been studied. Experimental results show that the
crystallographic orientation of the workpiece material exerts a large
influence on the cutting force and surface roughness. The
crystallographic nature of cutting force variation was analyzed based on
a microplasticity model. Analytical results compare well with the
experimental data. Measures for minimizing the cutting force variation
and hence improving the machined surface quality were discussed. |
| Aspects of surface generation in orthogonal ultraprecision machining |
| D.A. Lucca, Y.W. Seo, R.L. Rhorer / R.R. Donaldson (1) |
| STC C, 43/1/1994, P.43 |
| Keywords: Cutting, Surfaces, Ultra-Precision Machining |
|
Abstract : The depth of the plastically deformed layer at the workpiece surface
which resulted in the orthogonal ultraprecision machining of Cu over the
range of uncut chip thicknesses of 0.01-10 µm was investigated. Two
tools with the same nominal geometry but with differing edge geometries
were used to machine both Te-Cu and fine grain Cu . Tool edge geometries
were characterized by atomic force microscopy, taking into account the
AFM cantilever tip radius. Magnitudes of the measured depths appear to
be consistent with values reported in the literature and those arrived
at by simple analyses. |
| On a possible mechanism of shear deformation in nanoscale cutting |
| T. Inamura, N. Takezawa, Y. Kumaki, T. Sata (1) |
| STC C, 43/1/1994, P.47 |
| Keywords: Simulation, Micromachining, Cutting |
|
Abstract : Based on the method of transformation from an atomic model to a
corresponding continuum model, the stress and strain distributions in
nanoscale cutting have been evaluated. The results show that a workpiece
is subjected to concentrated compressive and shear train at the primary
shear zone, though the area along the rake face of the tool is strained
tensilely. The results also show that the interior of the workpiece is,
however, exposed to high, almost constant, compressive stress. A
possible mechanism of these different stress and strain distributions is
discussed as well as its interpretation on a macroscale. |
| Structure of micromachined surface simulated by molecular dynamics analysis |
| S. Shimada, N. Ikawa (1), H. Tanaka, J. Uchikoshi |
| STC C, 43/1/1994, P.51 |
| Keywords: Cutting, Micromachining, Simulation |
|
Abstract : Using molecular dynamics computer simulation, a feasibility study is
made for the quest of ultimate quality of machined surface attainable in
diamond microcutting of copper with a fine cutting edge under
hypothetically perfect machine motion. Based on the analyses, the
surface generation. process and microstructure of worksurface are well
understood from atomistic point of view. In cutting of monocrystalline
copper, the worksurface which is free from residual distortion can be
obtained and ultimate surface roughness is estimated to be less than 1
nm. In cutting of polycrystalline cooper, nanometrically distorted layer
inevitably remains on worksurface. However, the ultimate surface
roughness is estimated to be at the same level as that of
monocrystalline copper. |
| Distribution of cutting tool contact loads along rake and flank surface |
| V. Ostafiev (1), D. Ostafiev, K. Mukhmudov |
| STC C, 43/1/1994, P.55 |
| Keywords: Curve Generation, Contacts, Loads |
|
Abstract : The distribution of contact loads along race and flank surfaces is
determined by integration of geometrical and physical parameters of
cutting process. The chip formation model has been proposed as trapezium
shape lamellar structure formation process. This model has described
chip curves, its contact length and contact loads distribution taking
into account both plastic and elastic chip deformation. The contact
loads distribution on the flank surface has calculated in connection
with contact loads value on rake surface. The obtained results are in a
good agreement with experiments. |
| Effects of drill vibrations on cutting forces an torque |
| D.M. Rincon, A. Galip Ulsoy / B. Kaftanoglu (1) |
| STC C, 43/1/1994, P.59 |
| Keywords: Cutting, Drilling, Vibrations |
|
Abstract : Drill bit vibrations can have an adverse affect on drilling performance
resulting in lobed holes, burr formation and tool breakage. An
analytical model for predicting torque, thrust and radial forces in
drilling has been developed. The model includes the effects of the drill
hit transverse deflections which lead to variations from the mean values
in the cutting forces. Simulations for a drill, exhibiting increasing
elliptical translational motion due to drill vibrations, indicate a
significant increase in the ranges of the torque and thrust while
maintaining essentially constant mean values. The same qualitative
trends are also observed experimentally. The model, when drill
vibrations are negligible, reduces to previous models for predicting the
mean torque and thrust in drilling. The mean drilling torque and thrust
values predicted are in good agreement with experimental data and with
previously published models. |
| Modifications of the cutting edge geometry and chip formation in milling |
| R. Wertheim (1), A. Satran, A. Ber (1) |
| STC C, 43/1/1994, P.63 |
| Keywords: Milling, Chip Formation, Tool Geometry |
|
Abstract : The research describes the development of milling inserts with new
cutting-edge geometries, three-dimensional chipformer configurations,
and non-straight and non-continuous cutting edges. The investigation can
lead to optimization of the cutting edge and the rake and clearance
faces while improving tool life, accuracy, surface quality and chip
flow. Results with molded chipformers, helical cutting edges and
constant rake and clearance angles are discussed. The geometries include
continuous helical and non-continuous, serrated cutting edges for chip
splitting and improved force distribution. Higher machining stability,
lower forces and improved chip formation can be achieved. With the
serrated edge, the chip splits depending on feed and machining
direction. Measured chip thickness is larger than the calculated one
while chip length is smaller. |
| Selective transfer built-up layer displacement in high speed machining. Consequencies on tool wear and cutting forces |
| J.C. Hamann, F. Le Maître (1), D. Guillot |
| STC C, 43/1/1994, P.69 |
| Keywords: Cutting, High Speed Machining, Force |
|
Abstract : The appearance and stability of the selective transfer built up layer
(BUL) is studied from a mechanical point of view by its effects on
cutting forces in the turning of two austenitic stainless steels with
improved machinability. We point out that a displacement of the stable
BUL from the face to the flank of the tool as the cutting speed
increases enables to keep an acceptable tool life in high speed cutting
conditions providing that the tool geometry is appropriate. |
| Cutting temperatures evaluation in ceramic tools : experimental tests, numerical analysis and S.E.M. observations |
| S. Lo Casto, E. Lo Valvo, E. Lucchini, S. Maschio, M. Piacentini, V.F. Ruisi / P. Lonardo (1) |
| STC C, 43/1/1994, P.73 |
| Keywords: Cutting Temperatures, Ceramic Tools, SEM |
|
Abstract : The authors propose a multiple approach for the evaluation of cutting
temperatures in ceramic tools. The first approach was the experimental
evaluation of equitemperature lines, obtained in three-dimensional
cutting by employing constant melting point powders scattered on planes
parallel to rake face. In the second approach, a numerical finite
element analysis was performed. At this step the determination of the
percentage of total heat produced in the operation that flows into the
tool was considered and, consequently. the temperature distribution
within the whole volume of the insert. Finally, the examination of the
crater zone with SEM microscopy confirmed the temperature levels as
previous estimated. |
| Characterization of manufacturing processes based upon acoustic emission analysis by neural networks |
| I. Grabec, E. Kuljanic (1) |
| STC C, 43/1/1994, P.77 |
| Keywords: Manufacturing, Neural Network, Acoustic |
|
Abstract : This article describes the application of a Gaussian neural network for
the monitoring of manufacturing processes. The network memory is formed
by a self-organized learning process which is stimulated by a
multi-component input comprised of acoustic emission (AE) signals and
process parameters. By using a trained memory and a non-parametric,
multi-dimensional regression the process parameters are associatively
estimated from AE signals alone. In this article the on-line estimation
of surface roughness during grinding, and the classification of tool
sharpness in a drilling process are described. The dynamical forecasting
of the AE signal generated in drilling is also demonstrated. |
| Real time tool breakage monitoring for NC turning and drilling |
| J.M. Lee (1), D.K. Choi, C.N. Chu |
| STC C, 43/1/1994, P.81 |
| Keywords: Acoustic Emission, Cutting Forces, Fracture |
|
Abstract : This paper presents real-time tool breakage detection by sensor fusion
concept of an acoustic emission sensor and a built-in force sensor in
turning and drilling processes. Miniature piezoelectric force sensors
were inserted in the tool turret housing of an NC lathe and in an
auxiliary mounting plate of a machining center. These built-in sensors
are economical and do not disturb machining operations. When a tool
breaks, a burst type AE signal is followed by a significant drop of
cutting force in turning or thrust force in drilling. The AE burst
signal was used to trigger cutting force (thrust force) inspection. The
algorithm was implemented on a Digital Signal Processing (DSP) board for
real-time tool breakage monitoring. Experimental works showed an
excellent real-time monitoring capability of the proposed tool breakage
detection system. |
| In-process prediction and prevention of the breakage of small diameter drills based on theoretical analysis |
| T. Nagao (2), Y. Hatamura, M. Mitsuishi |
| STC C, 43/1/1994, P.85 |
| Keywords: Drilling, Breaking, Predictive Maintenance |
|
Abstract : The in-process prediction and prevention of the breakage of small
diameter drills has been investigated. A series of drilling tests has
been carried out with newly developed torque-thrust sensors. It has been
determined that it is possible to predict and prevent drill breakage by
monitoring the torque and the thrust, since these force components rise
suddenly and exceed threshold values just before the breakage. To
determine the appropriate threshold values, the stress due to the
torque, the stability of drill motion and the temperature rise at the
drill tip have been analyzed theoretically. From these calculations, the
maximum shear stress in the drill, the combinations of angular velocity
and thrust values which lead to instability and an expression for the
temperature rise at the drill tip have been obtained. |
| Wear characteristics of cermet cutting tools |
| H.K. Tönshoff (1), H.G. Wobker, C. Cassel |
| STC C, 43/1/1994, P.89 |
| Keywords: Cermet, Wear |
|
Abstract : Turning tests were carried out with different cermet grades and
workpiece materials. Real production processes with permanently
changing mechanical and thermal loads were simulated by cut-in/cut-off
cycles. The wear behaviour of cermets used in cyclic cutting is not
governed by the same laws as in continuous cutting. This is due to the
effect that in cyclic cutting the tool life depends both on the wear
rate and the occurence of cracks and microchipping. The cracks are
caused by the alternating thermal load. This was proved by corresponding
simulations with a laser device. As the occurence of microchipping is
more or less accidental, the reliability of the wear behaviour decreases
with increasing frequency of load cycles. Furthermore, the influence of
cermet compound, tool geometry, workpiece material and coolant on the
wear behaviour was investigated. Worn cutting tips as well as annealed
cermet/steel-sandwiches were analysed with regard to the chemical
interaction between tool material and workpiece material. |
| Turn-milling of hardened steel - An alternative to turning |
| H. Schulz (1), T. Kneisel |
| STC C, 43/1/1994, P.93 |
| Keywords: Turn-Milling, Hard Cutting, CBN |
|
Abstract : Turn-milling with parallel axes is a relatively new method for precision
machining of rotationally symmetrical workpieces. Here the kinematic
conditions and their influence on the design of tools and the choice of
technological parameters are shown. Using CBN while cutting hardened
steel (> 62 HRC) a tool life is achievable which clearly exceeds that of
the hard-turning process. Surface qualities beneath R_Z < 2 ?m can be
achieved. |
| Relation between process energy and tool wear when turning hardfacing alloys |
| K. Weinert / L. Cronjäger (1) |
| STC C, 43/1/1994, P.97 |
| Keywords: Turning, Plasma, Wear |
|
Abstract : When turning weld deposited cobalt-based alloys with PCBN-tools, there
exists an optimum of cutting speed concerning the tool wear. The amount
of this cutting speed depends on the cutting conditions. In the
succession of continuous cut, machining with unsteady depth of cut, and
intermittent cut, the cutting speed optimum increases from 90 m/min up
to 330 m/Min. Using a plasma arc to heat up the workpiece in front of
the tool, the minimum of tool wear can be shifted to lower cutting
speeds. Together with the minima of flank wear, minima of the total
cutting force occur. Compared to conventional machining, the total
cutting force can be reduced. |
| Chip Flow and notch wear mechanisms during the machining of high austenitic stainless steels |
| H. Chandrasekaran (2), J.O. Johansson |
| STC C, 43/1/1994, P.101 |
| Keywords: Turning, Wear, Stainless Steel |
|
Abstract : Notch wear at the depth of cut line is a serious problem during the
machining of high-austenitic stainless steels. The mechanism of such
notch wear was investigated through special step-turning tests involving
four high austenitic stainless steels with cemented carbide tool. Chip
studies and micro-hardness measurement of work material at the chip flow
region, alone with SEM studies were carried out to elucidate the role of
work hardening and chip flow upon wear. These clearly showed severe
localised shear and chip side flow and its strong adhesive interaction
with the tool material in the notch region. The critical initiation of
the notch seems to he related to factors such as, transverse stress and
temperature distribution and chemical interaction. Subsequent progress
of notch was often through the interaction of the localised shear region
of the chap and the exposed binder phase o£ the tool. Direct evidence
between the strain hardening index of the work materials and the level
of notch wear was also observed. |
STC Dn |
| Application of the theory of inventive problem solving to design and manufacturing systems |
| V.R. Fey, E.I. Rivin (1), I.M. Vertkin |
| STC Dn, 43/1/1994, P.107 |
| Keywords: Design Algorithm, System Development |
|
Abstract : The paper presents basics of a little known in the West algorithmic
system for solving engineering problems developed by G. S. Altshuller
and his school in the former USSR. The algorithmic system provides a
powerful tool for solving conceptual design problems. It is based on the
formulated Laws of Evolution of Engineering Systems and consists of
three subsystems: the Algorithm for Inventive Problem Solving, the
Standard Solutions to Inventive Problems, and the Database of Physical,
Chemical, and Geometrical Effects. Several examples of application of
this system for obtaining non-obvious solutions to real life engineering
problems are described. |
| Basic layout design with multiple-layered decision making and transit evaluation |
| H. Shinno, Y. Ito (2), H. Tadano |
| STC Dn, 43/1/1994, P.111 |
| Keywords: Design, Decision Making, Machine Tool |
|
Abstract : In the design procedure, mature designers always analyze and synthesize
various requirements and conduct necessary information processing so as
to have the moss suitable result. In order to rationally automatize such
a synthetic procedure, it is necessary to effectively transplant the
information processing function of the designer into a computer system.
Thus, in this paper, a novel decision making methodology has been
proposed to establish a future intelligent CAD system for the basic
layout. The proposed methodology is based on the multiple-layered
decision making with the transit evaluation function, and its validity
has also been verified through case studies on the design of a main
spindle system in machine tools. |
| An interactive refinement methodology for early stage exploration of design space during system design |
| S.Y. Reddy, S.C.Y. Lu (2) |
| STC Dn, 43/1/1994, P.115 |
| Keywords: System Design, Computer-Aided Design, Concurrent Engineering |
|
Abstract : The design of large engineering systems requires the quick exploration
of design space. Though simulation models have been used to support
optimal design of individual subsystems, similar approaches cannot be
used for system design, because of the difficulties in using the
disparate simulation models for different subsystems and perspectives
together, in addition to the ensuing excessive computational
requirements. This paper presents a methodology for system design,
called Hierarchical and Interactive Decision Refinement (HIDER), which
combines machine learning based adaptive modeling, multiple-objective
optimization, and interactive refinement techniques to provide decision
support for quickly exploring the design space. The paper also presents
results from the application of HIDER to the system design of a wheel
loader. In this example, complex simulation models for cycle time
analysis and stability analysis are used for the design of the wheel
loader simultaneously from these two perspectives. |
| An integrated modeling environment using the metamodel |
| H. Yoshikawa (1), T. Tomiyama, T. Kiriyama, Y. Umeda |
| STC Dn, 43/1/1994, P.121 |
| Keywords: Computer Aided Design, Modelling, Knowledge Based System |
|
Abstract : One of the central issues of intelligent CAD is building a modelling
mechanism that deals with multiple models. The basis on which a model is
built, which we call ontology, may vary over domains of modelling,
abstraction and approximation levels, and granularities. This paper
discusses integration of design object models over multiple ontologies.
The key idea is the use of meta level model about relationships among
models. The meta-level model, which we call the metamodel, is used for
reasoning about how models should he generated and modified so that
consistency among them can be maintained. The use of the metamodel is
illustrated by an example of modelling a hydrofoil. |
| Conceptual graphs in CAD |
| O.W. Salomons, F. Van Slooten, G.W.F. De Koning, F.J.A.M. Van Houten (2), H.J.J. Kals (1) |
| STC Dn, 43/1/1994, P.125 |
| Keywords: CAD, CAPP, Features |
|
Abstract : This paper elaborates on the use of conceptual graphs in a prototype of
a computer based support system for re-design. Re-design support
involves the modelling of assemblies and components. The requirements of
the components to be modelled are a compromise between the functioning
of the assembly and the manufacturability of the individual components.
Conceptual graphs provide for an elegant way of representing both
functioning and manufacturing aspects. In the prototype system,
conceptual graphs are used for representing and defining assemblies,
components and features as well as the relations between these entities.
Constraints, such as kinematic, tolerance and manufacturing constraints
are also represented using conceptual graphs. |
| Application of constraint propagation in part family modelling |
| M. Mäntylä, K. Lagus, T. Laakko / G. Sohlenius (1) |
| STC Dn, 43/1/1994, P.129 |
| Keywords: Computer Aided Design (CAD), Knowledge Based Systems, Constraints |
|
Abstract : The paper describes the use of an incremental constraint propagation
technique for feature-based modelling of group technological part
families. The constraint representation is based on a multigraph where
nodes represent constrained variables and multiarcs the various
constraints. Through the variables, the multigraph is integrated with a
LISP frame based feature representation. A constraint specification
language for representing constraint types in feature and part family
definitions is also discussed. The system has been implemented in the
context of the EXTDesign feature based modelling system developed at the
Helsinki University of Technology. The work is considered a contribution
to computer-aided design methodology. |
| 3-D interacting manufacturing feature recognition |
| S.R.T. Kumara (2), C.Y. Kao, M.G. Gallagher, R. Kasturi |
| STC Dn, 43/1/1994, P.133 |
| Keywords: Manufacturing Feature Recognition, CAD/CAM, Neural Network |
|
Abstract : Automatic recognition of machining features such as slots, holes and
pockets is one of the major tasks of CAD/CAM. This research proposes the
super relation graph (SRG) method for extracting shape features. The
nodes of the SRG represent the faces in depressions, the links represent
either super-concavity or face-to-face relationships which are generated
from a set of new definitions of relationships between two faces.
Hypotheses are generated from a combination of graph-based and neural
network approaches. These hypotheses are verified using computational
geometry techniques. The SRG method is implemented in an object oriented
paradigm and the results obtained are proved to be better than the ones
generated from most of the prominent existing methods. |
| Application of fuzzy set theory to set-up planning |
| S.K. Ong, A.Y.C. Nee (1) |
| STC Dn, 43/1/1994, P.137 |
| Keywords: Computer Automated Process Planning, Jigs and Fixtures, Fuzzy Set Theory |
|
Abstract : Computer-aided process planning and computer-aided fixture planning have
been widely researched in the last two decades. Most of these
computer-aided systems are, however, either dealing only with process
planning or fixture design. This paper advocates set-up planning as a
link between these two functions. A set-up planning system for the
machining of prismatic parts on a 3axis vertical machining centre is
proposed. This system formulates set-up plans based on the initial,
intermediate and final states of a part. The system uses the fuzzy set
representation, along with production rules and object representation.
This hybrid representation scheme aptly depicts the inexact
relationships among features required on a final part, and with those
currently present on the part. These inexact relationships, which
greatly affect set-up planning, are manifestations of the various
process and fixture planning constraints in the system. The
consideration of these features' relationships together with the
intermediate states of a part, allow the system to plan forward without
the need to backtrack. Through this representation, the set-up planning
problem is formulated using the fuzzy set theory. Using this approach,
the proposed system is able to generate set-ups that fulfil the process
and fixture planning requirements that are commonly practised by
experienced planners. |
| Configuration and dimensional synthesis in mechanical design : an application for planar mechanisms |
| P. Makkonen, J.G. Persson (2) |
| STC Dn, 43/1/1994, P.145 |
| Keywords: Design, Synthesis, Mechanism Optimisation |
|
Abstract : An approach to synthesis of mechanical systems in the conceptual and
dimensional phase is done by combining topological and dimensional
design with graph theory. The topological synthesis is done in two
parts. First, part and joint number synthesis is done from the Grübler
equation. The synthesis is continued by a grammatical approach. The
theory of generative grammar has been applied to mechanisms, and by
using this approach, a "grammar of mechanisms" has been formulated. The
level of grammar is specified and grammatical rules have been derived
from the constraint equations. An example of topological synthesis of
mechanisms utilising the developed grammar is presented. Finally, the
dimensional synthesis of the mechanism topologies is done utilising
non-linear programming (the gradient method) with addition of a
penalty-function to avoid discontinuities. |
| Distribute product design |
| F.L. Krause (2), T. Kiesewetter, S. Kramer |
| STC Dn, 43/1/1994, P.149 |
| Keywords: Concurrent Engineering, Product Design, Project Management |
|
Abstract : Distribution of design tasks is a measure to accelerate the product
design process. In a distributed design environment based on broadband
communication network it is feasable to split the design task into
functional and shape related subtasks. Under the supervision of a
project management system the design tasks can be worked out in parallel
and independently. The product model of the design system can include
information about design space, design constraints and connections to
other design subtasks. |
| The utilization of hypermedia based information systems for developing recyclable products and for disassembly planning |
| D. Spath / H. Weule (1) |
| STC Dn, 43/1/1994, P.153 |
| Keywords: Product Design, Disassembling, Information Systems |
|
Abstract : When products are considered in the context of their overall life-cycle,
there is an increased requirement fo; information on the various
life-phases involved. Information on disposal options determines the
product design concept, and conversely the product design parameters
affect the degree of rationalization achievable in disassembly. The
resultant need to provide ecologically relevant product data both for
development engineers and for disassembly planners in the context of the
specific requirements concerned entails the necessity of using
computer-aided information systems.
This paper presents an information concept of this kind for supporting
development engineers in implementing recyclable product designs, plus a
procedure for planning and supporting manual disassembly. In
methodological terms, systematized approaches are employed for design
evaluation and procedures for qualification-oriented disassembly
planning. Initial software developments are indicated for practical
applications based on Hypermedia. |
| Challenges in product strategy, product planning and technology development for product life cycle design |
| V.A. Tipnis (2) |
| STC Dn, 43/1/1994, P.157 |
| Keywords: Product Strategy and Planning, Environmental Impact, Technology Development |
|
Abstract : The growing emphasis on design for sustainability requires that the
harmful side effects to workers, users, and local and global natural
ecosystems must be minimized by reducing the rate of material and energy
consumptions that lead to the harmful side effects. As corporations face
stricter regulations on emissions, effluents, and solid waste disposal,
they are forced to develop technologies for disassembly,
re-manufacturing, and recycling as well as for higher energy efficiency
products and processes. The challenge of design for sustainability has,
therefore, forced corporate product strategists and product development
planners to address the following series of questions: How to formulate
a competitive product strategy for environmentally-safe product life
cycle design? What should be the product life cycle? How long? Should
the product be 'sold' or 'leased'? How to set correct competitive
targets for product function, features, performance. quality and
reliability? How should the product realization process be organized to
ensure designed-in' quality into products without missing the product
introduction target timing or target cost?
Environmentally-safe product life cycle design requires the product
design and manufacturing expertise at the stage of the product strategy
formulation itself. A methodology for the formulation of competitive
product strategy is presented as a starting point for design for
sustainability. |
| Linear and geometric accuracies from layer manufacturing |
| T.H.C. Childs (2), N.P. Juster |
| STC Dn, 43/1/1994, P.163 |
| Keywords: Concurrent Engineering, Inspection, Manufacturing Processes |
|
Abstract : A benchmark component has been designed to test the geometrical
capabilities of the photo-polymerisation, selective laser sintering,
laminated object manufacturing and fused deposition modelling layer
manufacturing rapid prototyping processes. It assesses not only linear
accuracies but geometric tolerances, repeatability, resolution limits
and the ability to create manufacturing features such as fillets and
draft angles.
Repeatability measurements on the benchmark show that the layer
manufacturing technologies rank differently in the small scale (less
than 5mm), the medium scale (20 to 25mm) and the large scale (up to
250mm). The superiority of the photo-polymerisation processes in the
small scale is lost at medium and large scales. Measurement ranges are
mainly from 0.05 to 0.5mm. |
STC E |
| Linear shaped YAG laser beam with uniform power density distribution applied to machining of ceramics |
| T. Miyazaki, Y. Tanaka, T. Tokunaga / N. Kinoshita (1) |
| STC E, 43/1/1994, P.167 |
| Keywords: Laser Beam Machining, Ceramics |
|
Abstract : A single mode YAG laser beam is transformed into a linear beam of
uniform power density distribution, which is shaped through a shaping
mask, a convex lens and a cylindrical lens. The mask eliminates the
surrounding part of the beam with low power density and generates the
uniform density distribution. The convex lens converges the beam and
generates a high power density beam. The cylindrical lens transforms the
circular beam into the linear shaped beam.
A ditch with sharp edge can be obtained by scanning the shaped beam; the
ditch depth can he controlled by varying the focusing position of the
beam. This optical system is applied to produce profiles of saw blade
and notch in ceramics with numerical control systems for the workpiece. |
| Laser material interaction : absorption coefficient in welding and surface treatment |
| G. Ricciardi (2), M. Cantello |
| STC E, 43/1/1994, P.171 |
| Keywords: Laser, Welding, Surface Treatment |
|
Abstract : Efficient energy coupling between beam and material is fundamental for
any effective application of laser technology. Qualitative &
quantitative experimental assessments on laser radiation absorption
phenomena during moth high power density (welding) and low power density
operations (surface treatments) are providing useful information on
process energy balance in order to achieve a deeper understanding of the
absorption mechanism, and to collect a wide amount of data, a starting
point for any consistent modelling of results. |
| Ultrasonic-aided laser drilling of aluminium-based metal matrix composites |
| W.S. Lau (1), T.M. Yue, M. Wang |
| STC E, 43/1/1994, P.177 |
| Keywords: Ultrasonic, Laser Beam Machining, Composite |
|
Abstract : In pulsed Nd:YAG laser drilling of aluminum-based metal matrix
composites (MMCs), it is well known that there are problems of limited
maximum depth-of-drill, non-cylindrical hole profile and the presence of
excessive re-cast material which are associated with the conventional
process. A novel combined ultrasonic-laser machining technique has been
developed to improve the overall quality of laser drilled holes. It has
been proven that this ultrasonic-aided laser machining technique not
only increase the depth-of-drill, but also improves the quality of the
hole. A mathematical model is proposed to describe the shape of the
machined hole. |
| Magnetic abrasive finishing of rollers |
| M. Fox, K. Agrawal, T. Shinmura, R. Komanduri (1) |
| STC E, 43/1/1994, P.181 |
| Keywords: Superfinishing, Roller, Polishing |
|
Abstract : Advanced ceramics, such as silicon nitride are increasingly being
considered for structural applications, such as ceramic bearings for
high speed spindles. The requirements of high finish and accuracy and
minimal surface defects, such as cracks, combined with the difficulty of
finishing them by conventional methods of grinding and polishing cost
effectively, necessitated the investigation of alternate manufacturing
technologies. Magnetic field assisted polishing is one such technology
which is capable of generating (a) very high finish and accuracy, (b)
very little or no surface damage, such as microcracks to the components
during the finishing operation due to extremely low level of forces, and
(c) the finishing operation can be significantly faster than by
conventional techniques due to the possibility of using higher spindle
speeds. In this paper, this technique will be briefly reviewed followed
by an experimental investigation of the application of this technology
for finishing of stainless steel (non-magnetic) rollers to simulate
non-magnetic silicon nitride. Surface finish (Ra) of the order of 10 nm
can be obtained. Some of the parameters of the process that effect the
finish and material removal rate are discussed. |
| Magnetic fluid grinding - A new technique for finishing advanced ceramics |
| N. Umehara / S. Kalpakjian (1) |
| STC E, 43/1/1994, P.185 |
| Keywords: Polishing, Ceramics, Ferromagnetic Materials |
|
Abstract : Most advanced ceramics are finished by conventional grinding followed by
polishing. However, due to the brittle nature of these materials. the
grinding process introduces surface defects, such as cracks which can
significantly reduce the strength and reliability of the parts in
service. Also expensive diamond abrasives and long polishing times add
significantly to the cost of manufacture.
To address these concerns, a new polishing technique, known as magnetic
fluid grinding, was developed that uses controlled low level force
during polishing. The process is found to produce more accurate surfaces
at significantly less time than conventional polishing. The paper
presents the principles of this technique, design of magnetic fluid
grinding cell, salient features of the process, and results of finishing
balls, rollers, and plates using his technique. |
| A combined electrical machining process for micronozzle fabrication |
| T. Masuzawa (2), C.L. Kuo, M. Fujino |
| STC E, 43/1/1994, P.189 |
| Keywords: Electrical Machining, Micro-Machining, Hole |
|
Abstract : Smaller diameters are required for various types of precision nozzles.
However, the accuracy of nozzle holes is a problem in mechanical
machining processes and the choice of inner shapes is limited. A
combined process with EDM, ECM and electroforming is proposed for the
production of nozzles with small diameters and various inner shapes.
Nozzle holes with the diameters of 6-100 micrometers were successfully
produced with good concentricity to the outer profile. Some technical
characteristics of the process were also investigated. |
| High precision wire-EDM by on-line wire positioning control |
| D.F. Dauw (2), I. Beltrami |
| STC E, 43/1/1994, P.193 |
| Keywords: Wire EDM, Accuracy, Precision |
|
Abstract : The paper deals with a technical realization to improve the Wire EDM
accuracy. The system which is readily available on commercial wire EDM
machines is based on the on-line tracking and control of the wire
position. The deviation of the wire position relative to the programmed
wire path position is continuously measured and corrections are being
made during the machine cutting. This technique allows to cut complex
shapes, arc paths and contours at a much faster cutting speed as
compared to conventional wire EDM machines. Practical examples are
discussed and the economical relevance is emphasized. |
| WEDM identification and adaptive control for variable height components |
| K.P. Rajurkar, W.M. Wang, J.A. Mc Geough (1) |
| STC E, 43/1/1994, P.199 |
| Keywords: Physical and Chemical Machining, Wire EDM, Adaptive Control |
|
Abstract : Wire rupture in wire EDM is caused by high temperature due to high power
density determined by discharge frequency and workpiece height. This
paper reports a new WEDM adaptive control system that monitors and
controls the spark frequency according to the on-line identified
workpiece height. The workpiece height is estimated by using a
non-linear discrete model relating cutting speed with spark frequency.
This system controls the spark frequency at optimal levels to avoid wire
rupture and to maintain the maximum productivity. The error of the
workpiece height identification is 1 mm and the response to changes in
workpiece height is 1 second. |
| On-the-machine measurement in EDM process by a calibration system with polyhedra |
| N. Mohri, H. Takezawa, N. Saito / K. Osakada (1) |
| STC E, 43/1/1994, P.203 |
| Keywords: Electrical Discharge Machining, Measuring Instruments, Calibration |
|
Abstract : In order to realize electrical discharge machining (EDM) with high
precision, it. is necessary to take into account of the change of the
shape of electrode and workpiece with machining time. This paper deals
with on-the-machine measurement of an electrode and a workpiece in
electrical discharge machining (EDM). A newly developed calibration
system with polyhedra is installed on the machine. The probe can he
detached from the machine in machining stage and it is attached to the
machine in measuring stage at any attitude according to the portion
being measured. The position of the edge of a measuring probe is
determined with the equations of planes on the polyhedron. This paper
describes the principle of calibration method and the change of complex
shape of in electrode and a workpiece measured in the process of machining. |
STC F |
| Prediction of ductile fractures in metal forming processes : an approach based on the damage mechanics |
| N. Alberti (1), A. Barcellona, L. Cannizzaro (2), F. Micari (2) |
| STC F, 43/1/1994, P.207 |
| Keywords: Failure, Forging, Damage |
|
Abstract : The Authors propose a new approach for the prediction of ductile
fractures in bulk metal forming processes: the approach is based on a
numerical analysis able to take into account damage occurrence and
evolution in constitutive equations. The model supplies the distribution
of the void volume fraction in the workpiece during the deformation
path: consequently, the comparison to a critical value, determined by
means of a simple tension test, allows to predict the growth of defects.
The proposed approach has been applied to the drawing process: the
numerical results have been compared with a set of experimental tests
showing a good predictive capability of the model. |
| Formability of rapid solidification processed hypereutectic Al-Si alloys |
| F.A.C.M. Habraken, J.H. Dautzenberg (2) |
| STC F, 43/1/1994, P.211 |
| Keywords: Forming, Ductility, Aluminium |
|
Abstract : Rapid Solidification Processing (RSP) offers significant advantages when
applied to hypereutectic aluminium-silicon alloys: If compared to cast
Al-Si alloys, higher strength levels, lower thermal expansion and
increased wear resistance can be obtained. The materials studied are
Al19Si5Fe, Al18Si5Fe2Ni, Al17Si3.5Cu2Ni and Al22Si3.5Cu2.5Ni (wt. %37;)
made by the 'Melt Spun Ribbons'-process and Al25Si5Fe2Ni produced by
spray-deposition.
At this moment, these materials are applied in e.g. pistons for high
performance engines. For economical use in mass-production, these
materials have to be formed into their (semi-) final shape. This
formability is subject of the paper. It gives an overview of this
property for a variety of forming conditions, ranging from extrusion to
sheet metal forming. The formability of the materials is quantified. A
comparison with conventional materials is made and various formed parts
are shown. |
| Extended capabilities in metal forming processes by a new interdisciplinary FEM-code |
| M. Herrmann / M. Geiger (1) |
| STC F, 43/1/1994, P.215 |
| Keywords: Forming, Process Modelling, Finite Element Method |
|
Abstract : The design and implementation of a new software system within a joint
interdisciplinary project was initiated to offer new, extended
capabilities in the field of nonlinear finite element analyses.
Flexibility, portability and expandability are important qualities of
the new software system. Modern relational database software was
introduced as an interface to the environment and as a material data
base. A technique of handling thermomechanically coupled problems with
independent FEM meshes is presented. A new method to model
history-dependent interface behaviour based upon the surface
representation by segments has been implemented. |
| Application of the slab-finite element method for improvement of rolled bar surface quality |
| K. Sawamiphakdi, G.D. Lahoti (2) |
| STC F, 43/1/1994, P.219 |
| Keywords: Bar, Finite Element Method, Rolling |
|
Abstract : This paper presents a methodology to improve bar surface quality by
using the slab-finite element method. The improper design of roll
geometries and roll pass sequences may lead to underfilled or overfilled
conditions in the finished bars. The analysis was conducted using the
special purpose slab-finite element program TASKS with some
modifications. The parametric analysis was performed by using several
roll geometries. The potential roll geometry to produce an excellent bar
surface quality was selected for an in-plant trial and excellent bar
surface quality was consistently obtained. |
| Optimization of a cooling system : The cooling of pilgered seamless tubes |
| W.E. Carscallen, J. Jeswiet (2), P.H. Oosthuizen |
| STC F, 43/1/1994, P.223 |
| Keywords: Cooling, Rolling, Pilgering |
|
Abstract : This paper describes the design of a cooling system for Pilger Rolling.
The design changed a turbulent flow regime (a mist) to a laminar one
with an improved method of delivery. Also, the new design led to
production improvements and increased capabilities in the company; for
instance: increased production rates [10-20%37;], with an increase in
quality; extended tool life [mandrel and rollers], hence less downtime
and increased productivity; increased consistency in the product, hence
less quality problems and rework; significant improvements in the
production environment - cleaner air in the factory. |
| Investigation into nonsteady-state three-dimensional extrusion of a trocoïdal helical gear by the rigid-plastic finite element method |
| D.Y. Yang / K. Lange (1) |
| STC F, 43/1/1994, P.229 |
| Keywords: Forming, Extrusion, Finite Element Method |
|
Abstract : In metal forming, there are problems with recurrent geometric
characteristics and without explicitly prescribed boundary conditions.
In such problems, so-called recurrent boundary conditions must be
introduced. The present study deals with non-steady-state
three-dimensional finite element analysis for extrusion of a trocoidal
helical gear through a curved die. The boundary-directed remeshing
scheme based on the modular remeshing technique is developed to reduce
the errors arising in fitting old and new mesh systems. The computed
extrusion pressure in reaching the near steady-state loading stage is
compared with the results of the experiment and the steady-state
analysis. The three-dimensional deformed pattern involving warping at
the extruded end due to torsional deformation mode is demonstrated. |
| Finite element analysis of three-dimensional metal flow in cold and hot forming processes |
| W.T. Wu, G.J. Li, J.P. Tang / T. Altan (1) |
| STC F, 43/1/1994, P.235 |
| Keywords: FEM Simulation, Cold and Hot Forming |
|
Abstract : Two-dimensional FEM (Finite Element Method) codes capable of solving
axisymmetric and plane strain industrial forming problems, are widely
and routinely used in the metal forming industry. In most practical
cases, however, to solve 3D problems, the engineers must handle them in
a 2D manner, which is only an approximation. To deal with 3D real world
problems more accurately, a 3D-FEM code was recently developed. In this
paper, the current capabilities and features of this 3D code are briefly
described with examples and by comparing, whenever possible, the
numerical predictions with experimental measurements. Future work will
include the development of a 3D automatic mesh generator, a more
efficient computational method, and a more user friendly post-processor. |
| FE-simulation of the precision forging process of bevel gears |
| E. Doege (1), H. Nägele |
| STC F, 43/1/1994, P.241 |
| Keywords: Forging, Bevel Gear, Finite-Element Method |
|
Abstract : Up to date high precision parts like bevel gears are manufactured by
warm or hot forging with a subsequent cold calibration for the
determination of the exact geometry. At the IFUM a precision forging
technology has been developed for the manufacturing of bevel gears
whereby the cold calibration operation of the workpieces can be
eliminated, which leads to considerable costsavings. With the aid of
the Finite-Element Method forging processes can be simulated
realistically, thus reducing the number of necessary experiments. This
paper presents the results of the FE-analysis of the manufacturing
process and the comparison with experimental results. |
| A new method to design blockers |
| S.I. Oh (2), S.M. Yoon |
| STC F, 43/1/1994, P.245 |
| Keywords: Metal Forming, Die Design, Digital Filter |
|
Abstract : This paper investigates a new method to design blocker geometry in
rib-web type closed die forging. By examining various forging and
blocker geometries, it was found that blocker geometry can be generated
by eliminating high frequency mode from finisher geometry. In order to
formalize the procedure, low pass filters, which can convert finisher to
blocker geometry, are proposed. Also discrete Fourier transform is used
for computational efficiency. The blocker geometry designed by the
present method are compared with the one by an experienced designer. The
blocker geometries are also validated by using FEM simulation. Present
results shows that the frequency approach may offer a promising method
to design blocker automatically. |
| The residual stress distribution in the wall of a deep drawn and ironed cup determined experimentally and by FEM |
| J. Danckert (2) |
| STC F, 43/1/1994, P.249 |
| Keywords: Deep Drawing, Residual Stress, FEM |
|
Abstract : A two stage axisymmetric deep drawing process followed by ironing of the
cup wall has been simulated with the explicit FEM code LS-Dyna2D. The
results show that thee ironing process causes a drastic change in the
residual stress distribution; the residual stresses are lowered and a
much more favourable distribution with regard to fatigue and stress
corrosion is obtained. The FEM results cornpare favourably with
experimental results. |
| Forming limits in hydromechanical deep drawing |
| N. Bay (2), S.S. Jensen, M.P. Malberg, S. Grauslund |
| STC F, 43/1/1994, P.253 |
| Keywords: Hydromechanical Deep Drawing, Forming Limits |
|
Abstract : A systematic approach predicting the possibility of forming complex
shapes in hydromechanical deep has been developed The method is based on
knowledge about the limiting curve of drawing-in of the flange caused by
fracture, adopting different initial drawing ratios, when drawing
circular, cylindrical cups. This limiting curve is called the master
curve. Using geometrical considerations the curve representing
drawing-in of the flange in hydromechanical deep drawing of a complex
shape is constructed and compared with the master curve. Successful
predictions of the possibility of forming or fracture in drawing stepped
and control cups in stainless steel were obtained. |
| Development of a computer-controlled drawbead simulator for sheet metal forming |
| K.J. Weinmann (2), J.R. Michler, V.D. Rao, A.R. Kashani |
| STC F, 43/1/1994, P.257 |
| Keywords: Sheet Metal Forming, Tooling, Computer Control |
|
Abstract : A multiple-action hydraulic sheet metal strip drawing test device has
been constructed for the purpose of studying the effectiveness of
feedback controls in sheet metal forming. The apparatus simulates the
flow of sheet metal in the blankholder and over the die shoulder during
the stamping of sheet metal panels. Its special features consist of the
ability to adjust both blankholder force and drawbead penetration while
the strip is being drawn. A force transducer was developed to measure
the forces in the sheet on either side of the die shoulder.
Measurements from this unique transducer determine both the drawbead
restraining force in the simulator and friction between the sheet and
the die shoulder. Data demonstrating the capabilities of the equipment
are presented. |
| Improving workpiece quality in swivel bending with new tools and a 2-D tool path |
| E. Von Finckenstein (1), L. Kessler, M. Kleiner, G. Reil, R. Schilling, R. Warstat |
| STC F, 43/1/1994, P.263 |
| Keywords: Bending, Tools, Simulation |
|
Abstract : Swivel bending has become a widely used industrial forming process for
larger bent part. By a new tool construction the movement of the tool
relative to the sheet can be minimized, which leads to a better surface
of the sheet and a better surface of the bending line. A 2-D controlled
tool path of the Swivel clamp, whore the control data come from a
process simulation, can improve the quality of the workpiece as well.
Both improvements of the forming process are shown with experimental and
simulation results. |
| Compensation of tilting and horizontal displacement of upper die, relative to the lower die at out of center forming load by a closed loop control system |
| K. Siegert / D. Schmoeckel (1) |
| STC F, 43/1/1994, P.267 |
| Keywords: Forming Press, Hydraulic Equipment, Control System |
|
Abstract : This paper presents a new method of compensation, including a closed
loop control system for the tilting and horizontal displacement of the
ram. At the Institute for Metal Forming at the University of Stuttgart,
a floating clamping plate, attached to the ram by hydraulic cylinders,
was developed. This clamping plate can be horizontally and vertically
positioned by a closed loop control system using proportional valves. By
experimental research, done with a hydraulic 4000 kN single acting
press, it was shown that compensation of the tilting and horizontal
displacement of the upper die relative to the lower die is possible. |
| A new method to detect solid fractions of mushy/semi-solid metals and alloys |
| M. Kiuchi (1), S. Sugiyama |
| STC F, 43/1/1994, P.271 |
| Keywords: Forming, Metal, Semi-Solid |
|
Abstract : A new method to detect so-called solid fractions of mushy or semi-solid
metals and alloys is proposed.
Firstly, the relationships between electric resistance ( or electric
potential difference ) and temperature in the range from solid-line to
liquid-line are measured with respect to binary alloys and
multi-component alloys. Secondly, the relationships between solid
fractions of mush or semi-solid binary alloys and their temperatures are
obtained by referring their equilibrium phase diagrams.
By combining both results, the unified relationship between normalized
electric potential difference and solid fraction is obtained for all of
the tested binary alloys. This relationship is used to determine the
solid fractions of multi-component alloys from their measured normalized
electric potential differences. The assumed values are verified by the
rapid solidification method. |
| Deterministic injection molding for quality plastic parts manufacturing |
| K. Yamazaki (2), K. Shoda, M. Fujikawa |
| STC F, 43/1/1994, P.275 |
| Keywords: Injection Molding Machine, Quality Control, High Precision Injection |
|
Abstract : The paper deals with a study on the injection molding system for
manufacturing high quality plastic products. The problems of the
conventional in-line screw injection machine were analytically and
experimentally studied. To solve problems, a new injection machine with
the mechatronics control system was designed and developed. The
developed system features a sim_p lified pre-plasticating type mechanism
with new control system using full-software closed loop servo control
with neuro-fuzzy control. The developed system demonstrated an excellent
stability by which a product can be manufactured with very consistent
quality and accuracy for long time without human operator intervention. |
STC G |
| Heat affected zones in grinding steel |
| M.C. Shaw (1), A. Vynas |
| STC G, 43/1/1994, P.279 |
| Keywords: Grinding, Surface Damage, Thermal Damage |
|
Abstract : Two well known forms of metallurgical damage of ground surfaces involve
untempered and overtempered martensite. Both of these forms of
metallurgical damage involve martensitic transformations. This paper
reviews the nature of such transformations and the special
characteristics that pertain in grinding where the time at temperature
before quenching is unusually short. |
| Analytical and experimental investigation of burn-out in creep-feed grinding |
| C. Guo, S. Malkin (1) |
| STC G, 43/1/1994, P.283 |
| Keywords: Grinding, Thermal, Creep |
|
Abstract : Creep-feed grinding operations require a copious fluid flow for cooling
at the grinding zone. Cooling effectiveness in creep-feed grinding
depends upon a critical burn-out limit beyond which fluid film boiling
occurs, cooling becomes ineffective, and the temperature rises
catastrophically. In the present paper, a thermal analysis is presented
to predict the burn-out heat flux limit at a critical temperature for
Film boiling. The thermal model considers the transient workpiece and
fluid temperatures during a grinding pass and the energy partition to
the workpiece. Measurements of the burn-out heat flux are found to be in
good agreement with theoretical predictions over a wide range of
creep-feed grinding conditions. |
| A general thermal model for grinding with slotted or segmented wheel |
| H.W. Zheng (1), H. Gao |
| STC G, 43/1/1994, P.287 |
| Keywords: Grinding, Thermal Model, Temperature |
|
Abstract : Grinding with shined or segmented wheel as one of affective ways to
reduce grinding thermal damage, has keen utilized in many fiend. In this
paper two thermal models for periphery grinding with slotted wheel and
vertical spindle face grinding with segmented wheel are established
respectively in order to choose the slotting or segmental parameters
more reasonable and predict grinding temperature. Further more a general
thermal modal is developed which not only unifies the above theoretical
models but also contains the J-C..Jaeger's and Des.Ruisseaux's thermal
models. Experimental results are also given to verify the models
developed in this paper. |
| Dimensional characterization of grinding wheel surface through acoustic emission |
| J.F. Gomes De Oliveira, D.A. Dornfeld (2), B. Winter |
| STC G, 43/1/1994, P.291 |
| Keywords: Grinding, Grinding Wheel Measurement, Acoustic Emission |
|
Abstract : An approach is proposed for measuring the grinding wheel geometric
characteristics by using the dressing tool as a touch probe and the
acoustic emission level generated in the contact as a trigger for the
dimensional measurement. The interaction between the dressing tool and
the grinding wheel is experimentally studied. Three interaction levels
are observed: turbulence, elastic and brittle. In the elastic contact
the grinding wheel surface is not damaged by the dressing tool. This
condition is investigated based in the topographic characteristics of
the interacting surfaces. The analysis shows that it is possible to
measure grinding wheel characteristics using this system. |
| An approach to monitoring of the grinding process using acoustic emission (AE) technique |
| W. Hundt, D. Leuenberger, F.H. Rehsteiner, p. Gygax (1) |
| STC G, 43/1/1994, P.295 |
| Keywords: Monitoring, Acoustic Emission, Grinding |
|
Abstract : For optimization and control of the grinding process it is necessary to
monitor the process state and the wear state of the grinding wheel. In a
European project for this purpose AE was measured during the process and
analyzed in a frequency range up to 3.5 MHz. Single grain experiments
showed different wear phenomena to be readily distinguishable by their
individual AE signature at these frequencies. The high grain contact
frequency of a real process. however, produces strongly overlapping AE
signals. A strategy was developed to separate and describe several
different AE sources. Their correlation to physical events is the object
of further research. |
| Acoustic emission for process control and monitoring of surface integrity during grinding |
| J.A. Webster, I.D.Marinescu, R.T. Bennet / R. Lindsay (1) |
| STC G, 43/1/1994, P.299 |
| Keywords: Acoustic Emission, Grinding, Surface Integrity |
|
Abstract : This study suggests that acoustic emission sensing may be a useful tool
for controlling the grinding process, and the following observations can
be made: fluid coupling to the grinding zone is easy to implement and is
effective; AE is superior to force for detecting wheel/work contact at
start of cycle:: using RMS signal processing may result in the loss of
important surface cracking and contact data; most AE sensors distort the
signal from the process but deconvolution can restore the signal; normal
force/AE ratio shows a good correlation with cross-lay surface roughness. |
| Material removal mechanisms in grinding ceramics |
| B. Zhang, T. Howes (2) |
| STC G, 43/1/1994, P.305 |
| Keywords: Grinding, Ceramics, Mechanism |
|
Abstract : This paper discusses material-removal mechanisms in grinding of ceramics
using single-point diamonds and diamond wheels. The ground lavers were
analyzed using_ SEM, FLM and other inspection methods. Material
pulverization was discovered on the surface layer of ground ceramics. A
powder regime was observed which appeared to result from pulverization,
which was the dominant material-removal mechanism as long as depth of
cut was smaller than a critical value. Material flowed sideways in
single-point grinding, forming pile-ups on both sides of a groove. The
size of the powder regime and the coefficient of pile-up were measured
in various grinding conditions. |
| Effect of grit depth of cut on strength of ground ceramics |
| J.E. Mayer Jr., G.P. Fang / R.L. Kegg (1) |
| STC G, 43/1/1994, P.309 |
| Keywords: Grinding, Ceramics, Strength |
|
Abstract : Experimental research has been conducted into the effect of grit depth
of cut on the flexural strength of ground hot pressed silicon nitride.
Wheel grit size and machine parameters of wheel depth of cut and
workspeed in surface grinding have been investigated. The results
indicate that the primary factors which control the strength of ground
ceramics are grind direction and the grit depth of cut. The findings
point the way to grinding conditions to achieve maximum strength
grinding of ceramics and to maximum specific material removal rates at
these conditions. Additionally, the most appropriate method for
computing the wheel grit depth of cut was identified. |
| On performance of brazed single-layer CBN wheel |
| A.K. Chattopadhyay (2), H.E. Hintermann (1) |
| STC G, 43/1/1994, P.313 |
| Keywords: Grinding, CBN, Loading |
|
Abstract : In brazed single layer CBN wheel, high grit exposure but with strong
grit-bond adhesion is known to be the most distinguished feature The
present investigation has, however, revealed that in spite of having a
large grit protrusion, the consistency of performance of such a wheel
may be affected by the manner how the density as well as the uniformity
of grit distribution are regulated in the monolayer configuration. This
is particularly true when a chip accommodation problem leading to wheel
loading exists. Experiments with monolayer CBN wheel varying in grit
density and under various grinding conditions have further revealed that
pre-brazing placement and fixation of CBN grit on the tool substrate
with an even distribution and adequate inter-grit spacing may remarkably
enhance the flexibility of application of a high protrusion single-layer
CBN wheel. |
| Development of highly homogeneous pellets applying electrophoretic deposition of ultrafine abrasives for nanometer grinding |
| J. Ikeno, Y. Tani, H. Sato (1) |
| STC G, 43/1/1994, P.319 |
| Keywords: Grinding Wheel, Abrasives, Mirror |
|
Abstract : This paper is concerned with how to fabricate highly homogeneous pellets
for nanometer in grinding. The realization of a. minute grain depth of
cut is an important feature for obtaining a smooth surface by grinding.
Hence i is profitable to apply a grinding wheel composed of ultrafine
abrasives of diameters of 10 to 20s. T ^-, .P, grinding wheel with
suitable bonding strength brings about grain-sized self-sharpening in a
grinding process. Hence it can prevent the occurrence of swarf loading
and grain dulling which weaken the grinding ability. As a result, the
highly homogeneous grinding ti feel earl yield a smooth surface of less
than 10nm,p-v for both hard and brittle materials. Ultrafine abrasives
which are negatively charged can be deposited uniformly on an anode 'Dy
applying electrophoretic deposition. Hence a homogeneous ultrafine
grinding wheel can be fabricated by applying this technique. |
| Generation of parabolic and toroidal surfaces on silicon and silicon based compounds using diamond cup grinding wheels |
| Z. Zhong, V.C. Venkatesh (1) |
| STC G, 43/1/1994, P.323 |
| Keywords: Diamond Grinding, Aspheric Optical Surfaces, Silicon |
|
Abstract : This paper presents the methods and experimental results using diamond
cup wheels and CNC machining centers for grinding parabolic and toroidal
surfaces made of Si and SiC, the former for use as a thermal imaging
lens and the latter for synchrotron radiation facilities. Generation of
aspheric surfaces, by zonal material removal, on Si using cup grinding
wheels and a 5-axis machining center was investigated. Theoretical and
experimental investigation of the grinding and material parameters that
influence ductile grinding are discussed. Ductile grinding is possible
with wheels having small grit size and with proper combination of feed
and unit normal load; a resinoid bonded wheel promotes this more easily
than a metal bonded wheel, though at the expense of profile accuracy.
Profile analysis, surface integrity, and examination of grinding swarf
using digital imaging are discussed. Also, generation of toroidal
surfaces on SiC using metal-bonded cup wheels, a 3-axis machining center
and a micro-displacement table with piezoelectric actuators was studied.
Toroidal SiC mirrors were ground with good shape accuracy, mirror
finish, and low surface roughness. The time consumed in the process is
very short. The machines used are inexpensive and not specially designed
for ultra-precision grinding. |
| Molecular dynamics simulation for abrasive processes |
| R. Rentsch, I. Inasaki (1) |
| STC G, 43/1/1994, P.327 |
| Keywords: Micro-Machining, Abrasion, Simulation |
|
Abstract : Until today several applications of Molecular Dynamics in mechanical
engineering fields have been carried-out, focusing on the simulation of
indentation tests or cutting processes. In this paper the application of
Molecular Dynamics for Abrasive Processes is discussed and the first
results from simulations are presented which are targeting on the
pileup phenomenon in abrasive machining. Particularly the differences
and necessities in contrast to the simulation of cutting processes are
taken into account. Some principal problems and components of the model
representation as well as applied techniques in indentation and cutting
simulations are discussed in more detail. Finally new methods to improve
the model representation and to enhance the calculation speed for large
models are given. |
STC M |
| Comparison of limit surface approach with other approaches in fixture planning with friction |
| S.H. Lee, K.K. Cho (2) |
| STC M, 43/1/1994, P.331 |
| Keywords: Fixture Planning, Limit Surface, Force Torque Space |
|
Abstract : A fixture planning module is being developed as part of a computational
system for concurrent product and process design. In general, three
kinds of constraints such as geometric, kinematic, force constraints are
considered to provide an appropriate fixturing for a given machining
process. Since many fixture arrangements rely on friction to hold a
part, the ability to reason about faction is an important component of
fixture planning. Limit surface in force/moment space are introduced as
a convenient formalism to check whether parts will slip and to help in
specifying clamping forces. In this paper, the use of limit surfaces
obtained either by scanning over the space of possible motions or by
Minkowski sums is compared with other four approaches to establishing
the relationships among applied forces and moments and the corresponding
direction of sliding motion. Since the other approaches in the
literature have only been applied to planar examples, the discussion in
this paper will he confined to the case of a planar pressure distribution. |
| Vibrations and surface generation in slab milling |
| U. Heisel / J. Milberg (1) |
| STC M, 43/1/1994, P.337 |
| Keywords: Machine Tools, Dynamic, Surface Generation |
|
Abstract : In slab milling the quality of the machined surface is directly
influenced by the dynamic behaviour of the machine tool. In addition to
the cycloidical microgrooves, the dynamic relative motion between the
workpiece and tool is superimposed on the machined surface. In general
these vibrations cannot be directly identified by investigating the
machined surface. By the application of a special purpose milling
cutter, microgrooves are generated which are identifiable and from which
the relative motions in the cutting zone can be determined by surface
topography measurement. It is shown how the groove structure is produced
as a function of the kinematics of the process and the relative motions
in the zone of cutting. An example based on experimental investigation
is used to illustrate the procedure used to determine these relative
motions based on analysis of the workpiece surface. |
| New concept of machining by means of 6-axis control |
| Y. Takeuchi (2), M. Sato, H. Suzuki |
| STC M, 43/1/1994, P.341 |
| Keywords: Machining Center, Control, Grooving |
|
Abstract : The study deals with a new machining concept by making use of 6-axis
control. 6-axis control implies that a cutting tool allows three
rotational movements for positioning as well as three translational
ones. A 6-axis control machining center equipped with a main spindle
capable of tool orientation in addition to conventional 5-axis control
structure is developed. A non-rotational cutting tool is mounted at the
main spindle to carry out the 6-axis control machining, which allows a
variety of machining possibilities. In the study, a control software for
grooving with an asymmetric cross section is presented together with
experimental cutting results. |
| New interface machine/tool : hollow shank |
| M. Weck (1), I. Schubert |
| STC M, 43/1/1994, P.345 |
| Keywords: Interfaces, Tools, High Speed Machining |
|
Abstract : The 7124-taper shank no longer complies to the demands of today's
manufacturing technology. Therefore, together with tool and machine tool
manufacturers and end users, the WZL at the RWTH Aachen developed a new
interface between machine tool and tool, the hollow shank. This paper
describes the possibilities and applicational limitations of the new
interface, which became a DIN-Standard in 1993, with regard to the
maximal permissible rotational speed, the possible bending and torsion
moments and the stiffness and accuracy. |
| A hierarchical open architecture CNC system for machine tools |
| Y. Altintas (2), W.K. Munasinghe |
| STC M, 43/1/1994, P.349 |
| Keywords: CNC Design, Adaptive Control, Tool, Monitoring |
|
Abstract : This paper presents a hierarchical open architecture multi-processor CNC
design for machine tools. The system's primary bus accommodates the
computer modules which look after the user interface, machining process
control and monitoring tasks. The secondary bus of a high performance
CNC module is used for communication with dedicated micro-controller
based drive control modules. There is an open flow of position, feed and
machining commands and states between CNC master, machining process
control and monitoring modules in the system. Sample test results for
parallel implementation of NC tool path control, adaptive cutting force
control and tool breakage detection are shown to illustrate the openness
of the designed system for intelligent machining operations. |
| To accurately control the speed of motion along parameterized space curves. Principle and application of a new algorithm in CAM/CNC and robotics |
| G. Yu / G.N. Levy (1) |
| STC M, 43/1/1994, P.355 |
| Keywords: Machines, CAM/CNC, Speed Control |
|
Abstract : To accurately control the speed of motion along parameterized space
curves is a common requirement in CAM/CNC, robotics and computer
animation. Because of the usually non-linear relationship between the
parameterizing variable and the arc length, it is very difficult to find
an accurate specification for a given speed profile along a
parameterized curve. The current solutions are unsatisfactory. In this
paper we describe the principle of a new algorithm and the algorithm
itself, without a brief mathematical derivation of the algorithm, by
which the relative deviation of the approximated speed from the desired
speed for any given speed profile along any parameterized space curve is
ensured to be smaller than a given tolerance. In addition, the use of
the algorithm in practice is simple and no extensive calculation is
required. |
| Design and control of robot with flexibilities |
| W.H. Elmaraghy, H.A. ElMaraghy (1), A. Zaki, A. Massoud |
| STC M, 43/1/1994, P.359 |
| Keywords: Robots, Control, Design, Flexibility |
|
Abstract : Industrial and special robots are used increasingly in applications
requiring fast motions and high accuracy, while manipulating large
payloads. Joints and links flexibility limit the performance of such
robots by introducing resonant frequencies in the range of the control
bandwidth. Two robots were designed and built to better understand the
dynamics and demonstrate the control of such robots under challenging
operating conditions. One of the robots is a 3D anthropomorphic robot
with two flexible links, and the other is a two link planar robot with
changeable, built-in joint flexibility. Robust and adaptive control
algorithms have been demonstrated. The experimental results illustrate
the difference between various control algorithms in meeting the
required goals. |
| New predictive solutions to very high speed machining |
| D. Dumur (2), P. Boucher (2) |
| STC M, 43/1/1994, P.363 |
| Keywords: Machine Tools, CNC, Control System |
|
Abstract : Improving performances of machine-tools can be achieved with predictive
control laws instead of classical P.I.D. controllers. Previous studies
dealing with Generalized Predictive Control (G.P C.) have proved that a
better efficiency is possible. coupled to a simple implementation due to
autotuning procedures. However, the limitations of these techniques may
be reached with strong specifications of very high speed machining. This
paper presents new gradual solutions to the cascade control of C.N.C,
machines with very severe objectives. First a multirate predictive
algorithm, attractive to benefit of the different dynamics of the loops,
can be considered as a positive answer to an increase of rapidity, thus
a decrease of the sampling period, only of possible use if a cascade
structure is required. The second solution develops, in case of very
Small sampling periods, a version of G.P.C. using the delta operator
instead of the time shift operator, to avoid oversampling and
sensitivity to the accuracy of the transfer function coefficients. The
possibilities of these two versions are analysed on an experimental
benchmark and compares to results obtained with "classical" G.P.C.
algorithms. |
| Accurate motion controller design based on an extended pole placement method and a disturbance observer |
| H. Van Brussel (1), C.H. Chen, J. Swevers |
| STC M, 43/1/1994, P.367 |
| Keywords: Automation, Continuous Path Control, Algorithms |
|
Abstract : The paper describes an innovative integrated design method for accurate
tracking in motion control applications, in the presence of external
disturbances like friction, cutting forces, etc. First, an extended pole
placement method is developed to design feedforward controllers for
applications with known future input commands, like in feeddrives for
machine tools. It results in a noncausal reference model with a low-pass
characteristic with selectable bandwidth and zero phase shift. A new
feedback design approach, based on a state and disturbance observer is
introduced. A loop transfer recovery procedure tunes the observer gains
to compromise optimally between performance and robustness. |
| Stochastic modeling and on-line adaptive control of cutting forces in turning |
| L. Harder, M. Nicolescu / B. Lindström |
| STC M, 43/1/1994, P.373 |
| Keywords: Cutting Forces, Real-Time Identification, Adaptive Control |
|
Abstract : This paper presents the development of a new parameter-adaptive control
system for on-line cutting force control in turning. The control system
adjusts the feedrate in-process in order to compensate for the varying
machinability of the cutting process. Since the machining system
-consisting of the cutting process and the machine tool structure - is a
system with time-variable dynamics, it is necessary for the control
system also to identify the process parameters and adapt the regulator
correspondingly in real-time in order to avoid instability problems. The
system presented in this paper is based upon stochastic modeling,
recursive identification and pole-assignment design. The paper includes
a theoretical analysis, and the applicability of the system is
demonstrated by experimental test results. |
STC O |
| Random manufacturing system : a new concept of manufacturing systems for production to order |
| K. Iwata (1), M. Onosato, M. Koike |
| STC O, 43/1/1994, P.379 |
| Keywords: Optimization, Flexible Manufacturing System, Decision Making |
|
Abstract : Manufacturing systems are now required to have a capability to cope with
the changes of manufacturing conditions and to carry out efficient
production continuously. The concept of Random Manufacturing System
(RMS) is proposed in order to realize flexible and adaptive production
for dynamically-changing orders. RMS consists of machine agents each of
which can decides its own schedule. The operation of RMS is carried out
according to the tender-based decision making. In this paper; the basic
concept, architecture, and operation procedure of RMS are introduced,
and methods for improving RMS performance and two simulation systems are
explained. |
| Workflow modelling for advanced manufacturing concepts |
| H. Rozenfeld, A.F. Rentes / W. König (1) |
| STC O, 43/1/1994, P.385 |
| Keywords: Integration Methodology, Modelling, Work Flow |
|
Abstract : This paper proposes a metamodel based on CIM-OSA principles representing
the enterprise operation. It leads to workflows constructs through a
meta data base derivation. lt is proposed also a methodology for
manufacturing integration. It supports a business process reengineering
allowing workflow modelling. In this context a software tool for
enterprise modelling was developed. So it is possible to get a better
understanding of business process. supplying subsidies for [SO 9000. for
supporting system benchmarking and other applications. |
| Decentral production scheduling of assembly systems with genetic algorithm |
| H.P. Wiendahl (1), R. Garlichs |
| STC O, 43/1/1994, P.389 |
| Keywords: Production Scheduling, Monitoring, Genetic Algorithm |
|
Abstract : In todays companies the shifting of functions from central divisions to
the production areas leads to new requirements in the field of
production planning. Flexible planning systems using algorithms which
are adapted to the needs and the objectives of the different production
areas are necessary to fulfill these new demands. Therefore a
graphical-oriented decision support system for the decentral production
scheduling of assembly systems is presented. The scheduling algorithm of
this system is a genetic algorithm. |
| Cellular manufacturing in highly specialised supply industries |
| R. Rössle, R. Züst / B. Schumacher (1) |
| STC O, 43/1/1994, P.397 |
| Keywords: Cellular Manufacturing, Group Technology, Order Processing |
|
Abstract : Cellular Manufacturing describes the realisation of new product oriented
organisational structures. Traditional Methods of Group Technology are
often unsuitable to receive such structures if parts have to be
manufactured based upon customers orders and design. These methods are
based upon static aspects. "Make-to-Order" suppliers are highly
determined by dynamical aspects. The variety of products is continuously
changing, the behaviour of such manufacturing systems is effected by a
large diversity of customer orders and customers demands. This paper
presents an approach to Cellular manufacturing based on dynamical
aspects. A model using external effects is proposed. These are the
System of Objectives, the Variety of Orders and the Variety of Products. |
| Engineering a dialogue between Science and Society |
| J. Peters (1) |
| STC O, 43/1/1994, P.401 |
| Keywords: Human, Engineering, Society |
|
Abstract : Engineering and technology stay as a permanent "closed loop" between
Science and Society. This regenerative process can become unstable when
unbalances take place between the different elements. In particular
present economic situation calls for a far-going disconnection between
human labor and machine work, provided the goods produced by the
machines are honestly redistributed within the global human society.
The notion of profit also must be reconsidered in all its dimensions as
well as the manufacturing system as such which has been subjected to a
profound change due to the impact of the information technology upon the
closed system mentioned above. |
| Zero-defect manufacturing by means of a learning supervision of process chains |
| E. Westkämper / H.J. Warnecke (1) |
| STC O, 43/1/1994, P.405 |
| Keywords: Optimization, Quality Assurance, Modelling |
|
Abstract : Highly productive and low-stock or "just-in-time" manufacturing systems
require safe manufacturing also in the process chain. Starting from a
systematic analysis of defects and their causes in single-product and
series production, a method has been developed enabling the supervision
of quality in the process chain as well as its optimization by means of
a learning management system.
For this, quality data collected are evaluated and represented in
mathematical process models. From these data, logic patterns are derived
by means of cluster analyses or statistical analyses, which provide
information on the causes and the assessment of nonconformities. Based
on this and with the help of high-performance parallel computing, it has
become possible to realize zero-defect manufacturing in process chains
by means of a knowledge and neuronal-network-based learning system. |
| A systematic method for renewal of production technology |
| A. Bilberg, L. Alting (1) |
| STC O, 43/1/1994, P.409 |
| Keywords: Optimization, Logistic, Productivity |
|
Abstract : Productivity is important for all manufacturing companies, but even so
many fail to utilize their resources due to poor management.
organization, planning, layout etc.
A study carried out at 10 Danish companies reveals that a large
improvement potential exists. The paper will discuss the results of this
studio and will present a systematic method for productivity
improvement. In all companies more than 10%37; productivity improvement has
been obtained through more effective layouts, logistics policies, better
organization, application of information technology etc. The conclusion
in most cases is that a minor non-expensive change can have a major
effect on the overall performance of the companies. The method combines
traditional business tools with the newest research tools, such as
simulation and monitoring aiming at setting diagnosis, generating plan
of actions and demonstrating the consequences before the improvements
are implemented. |
| Efficient automated geometric feature recognition through feature coding |
| P.K. Venuvinod, C.F. Yuen / E. Merchant (1) |
| STC O, 43/1/1994, P.413 |
| Keywords: Feature Recognition, Feature Coding, Process Planning |
|
Abstract : Automated geometric feature recognition (GFR) is a commonly encountered
task in the creation of any process planning or design for manufacturing
software, This paper describes a new method based on feature coding for
automated GFR. An enhanced winged edge data structure including surface
type labels and a Multi-Attributed Adjacency Matrix (MAAM) is generated
from the CAD model of the given object. The MAAM fully captures the
topology and coarse geometry of the object for the purposes of GFR. A
simple algorithmic method extracts each feature from the object-MAAM.
the feature-MAAM is then processed to generate 'a unique code which is
recognised and interpreted by matching it with entries in a Feature
Database. The method is significantly superior to previous GFR methods
in terms of computational efficiency and the reduced need to invoke
expert rules. Unlike previous methods. the system car handle objects
with plane, cylindrical as well as other analytically definable curved
faces and can recognise both simple and complex features i.e. those
formed by interactions amongst simple features. |
| Computer aided process planning techniques for complicated aircraft structural parts |
| J.K. Li (2), Z.H. Huang, H. Shen |
| STC O, 43/1/1994, P.417 |
| Keywords: Optimization, Computer Automated Process Planning (CAPP), Expert System |
|
Abstract : Since the complexity of the aircraft structural parts, which are key
parts to be machined in aircraft production, they can not be involved by
any existing CAPP system. This paper deals with the techniques used for
the development of a CAPP system for aircraft frames, ribs and beams.
Integrate with a CAD system, this CAPP system inputs part information
from the CAD outputs and transforms them into feature data by the aid of
part coding. A 6- orientation, hierarchical and frame structure is used
for the description of part features and their connections. Process
planning decisions are made by an expert system according to structural
and technological features of parts. Process documents are automatically
generated including a part sketch in each operation. |
| Tolerancing and sheet bending in small batch part manufacturing |
| L.J. De Vin, A.H. Streêm, H.J.J. Kals (1) |
| STC O, 43/1/1994, P.421 |
| Keywords: Tolerancing, Sheetmetal, CAPP |
|
Abstract : Tolerances indicate geometrical limits between which a component is
expected to perform its function adequately. They are used for instance
for set-up selection in process planning and for inspection. Tolerances
must be accounted for in sequencing and positioning procedures for
bending of sheet metal parts. In bending, the shape of a part changes
not only locally, but globally as well. Therefore, sheet metal part
manufacturing presents some specific problems as regards reasoning about
tolerances. The paper focuses on the interpretation and conversion of
tolerances as part of a sequencing procedure for bending to be used in
an integrated CAPP system. |
| A new approach of group technology part families optimization |
| K.K. Hon (2), H. Chi |
| STC O, 43/1/1994, P.425 |
| Keywords: Manufacturing Systems, Group Technology, Genetic Algorithms |
|
Abstract : The key question of forming a group technology (GT) based manufacturing
system has attracted numerous attempts in applying various optimization
techniques. This paper presents a new approach of optimizing GT part
family formation by genetic algorithm (GA) which is based on the
principles of natural selection. A genetic algorithm model combining a
coding design, a penalty factor and a scaling operation wan developed
for this purpose. Results generated from four case examples, and
comparisons with three other heuristic methods demonstrated that the
genetic algorithm approach provides a powerful and effective numerical
tool for the optimization of GT part-families. |
| Information modelling for technology oriented tool selection |
| W. Eversheim (1), M. Lenhart, B. Katzy |
| STC O, 43/1/1994, P.429 |
| Keywords: Feature, Cutting Tool, Information Modelling |
|
Abstract : Based on the feature approach a new method for selection and
configuration of tools is developed for turning, drilling and milling
operations. This method takes into account mainly technology factors
besides the workpiece geometry and the process strategy. Selection rules
are developed and transformed into real tool parameters according to the
new standardization aspects on tool characteristics.
The planning functions are integrated into an object oriented
engineering database. In this context the required resource models and
the STEP (Standard for the exchange of Product Model Data) based
information models are explained. The potentials of the implementation
are discussed in regard to rationalization targets. |
| Optimal tool selection based on genetic algorithm in a geometric cutting simulation |
| Y. Mizugaki, M. Hao, M. Sakamoto / H. Makino (1) |
| STC O, 43/1/1994, P.433 |
| Keywords: Optimization, CAM, Tooling |
|
Abstract : This paper presents new methods of offset surface generation and milling
tool selection. Firstly the calculation of a workpiece's area cut by a
tool is done by detecting contact points between the tool and the
workpiece in a lattice space model. Secondly the tool selection is made
by Genetic Algorithm to minimize the total machining time and the uncut
area. A tool set is coded as a binary hit string. It is assumed the
tools would be used in the descent order of radius and cut their
corresponding area as entirely as possible. Simulations and conclusions
are briefly described. |
| Computer-aided constrained optimization analyses and strategies for multipass helical tooth milling operations |
| E.J.A. Armarego (1), A.J.R. Smith, J. Wang |
| STC O, 43/1/1994, P.437 |
| Keywords: Milling Optimization Strategies, Multipass Milling Optimization, Machining Optimization Software |
|
Abstract : The development of computer-aided constrained optimization analyses and
strategies for multipass peripheral and end-milling operations are
outlined and discussed. The constrained optimization is based on
criteria typified by the maximum production rate and includes a range of
practical constraints of relevance to rough milling such as the machine
tool limiting power, torque, feed force and feed-speed boundaries. It is
shown that a combination of mathematical optimization analyses and
limited use of numerical search techniques provides clearly defined
computer-aided strategies which guarantee the final global optimum
solutions. Simulation studies have verified the software and
demonstrated the superiority of multipass over single pass. |
| Optimisation and dynamic adaptation of the cutter inclination during five axis milling of sculptured surface |
| J.P. Kruth (1), P. Klewais |
| STC O, 43/1/1994, P.443 |
| Keywords: Milling, Tool Path, Sculptured Surfaces |
|
Abstract : Five axis milling allows to machine free form surfaces with cylindrical
or toric cutters instead of ball nose cutter. This drastically reduces
the machining time. Commercial CAM modules however require the
NC-programmer to specify the appropriate inclination of the tool with
respect to the work piece surface normal. This is difficult especially
for complex parts with varying surface curvature. This paper presents
five axis CAM software which varies the tool inclination during the tool
path generation, in order to achieve the best combination of scallop
height, workpiece accuracy, surface roughness and machining cost.
Machining time to produce some free form workpieces, given a maximum
scallop height, could be reduced by 50%37;. |
| Optimization of the process parameters of injection molding with neural network application in a process simulation environment |
| G.H. Choi, K.D. Lee, N. Chang, S.G. Kim (2) |
| STC O, 43/1/1994, P.449 |
| Keywords: Injection Molding, Neural Networks, Simulation |
|
Abstract : The process parameters of injection molding have been set by human
operators based on their experience iteratively. Even with the
sophisticated CAE software tools, at present time, the interpretation
of the analysis results and the subsequent process parameter adjustment
are being done based on the human expertise. A learning system has been
developed to generate an optimum set of process parameters at the design
stage with a minimum number of CAE simulation runs. |
STC P |
| Angle interferometer cross axis errors |
| J. Bryan (1), D.L. Carter, S.L. Thompson |
| STC P, 43/1/1994, P.453 |
| Keywords: Metrology, Angular Measurements, Calibration |
|
Abstract : Summary: Angle interferometers are commonly used to measure surface
plate flatness. An error can exist when the centerline of the double
comer cube mirror assembly is not square to the surface plate and the
guide bar for the mirror sled is curved. Typical errors can be one to
two microns per meter.
A similar error can exist in the calibration of rotary tables when the
centerline of the double comer cube mirror assembly is not square to the
axes of rotation of the angle calibrator and the calibrator axis is not
parallel to the rotary table axis. Commercial double corner cube
assemblies typically have non-parallelism errors of ten milli-radians
between their centerlines and their sides and similar values for
non-squareness between their centerlines and end surfaces. The authors
have developed a simple method for measuring s these errors and
correcting them by remachining the reference surfaces. |
| Improving the accuracy of angle measurement system with optical grating |
| G.X. Zhang (1), C.H. Wang, Z. Li |
| STC P, 43/1/1994, P.457 |
| Keywords: Precision Engineering, Angular Measurements, Optical Gratings |
|
Abstract : A new angle measurement system with optical grating is presented in the
paper. Its distinguishing features are: (1) Gratings having sine
function transmissivity are used as the index gratings. The harmonic
errors of the Moire fringes are greatly reduced. (2) Errors caused by
zero offsets, inequality in amplitude and nonorthogonality in phase of
two Moire fringe signals are corrected by real time software error
correction. (3) Four unequally spaced reading heads are used to
eliminate the errors caused by the graduation error of optical grating
and error motions of the spindle. The experimental device gives an
accuracy about 0.2 arcseconds. |
| Development of an optical hole-diameter measuring instrument |
| H. Onikura, Y. Kuwabara, T. Nakamura, T. Sajima, Y. Imaseki, A. Katsuki / A. Kobayashi (1) |
| STC P, 43/1/1994, P.461 |
| Keywords: Optical Measuring Instrument, Hole, Accuracy |
|
Abstract : An optical hole-diameter measuring instrument has been developed. The
instrument, which consists of two laser diodes, a photo sensitive
detector, two condenser lenses and some mirrors, is intended to measure,
based on trigonometry, the distances to the hole wall on two sides
alternately. The fundamental analysis and experiment showed that it was
possible to measure the distances to the object having not only a
mirror-like plane surface but also a rough cylindrical surface, Using
the instrument, which was manufactured on trial, it was found that the
hole-diameter between 9.5 and 11.0 mm could be measured within accuracy
of 23 ?m. |
| Task specific gauge for the inspection of coordinate measuring machines |
| T. Pfeifer / G. Spur (1) |
| STC P, 43/1/1994, P.465 |
| Keywords: Bevel Gear, Calibration, CMM-Uncertainty |
|
Abstract : Coordinate measuring machines (CMMs) frequently are used for measuring
tasks at bevel gears even though probing at inclined tooth profiles
causes enormous length measuring uncertainties. In order to analyse
these faults on principle a master bevel -ear can be used, which however
is very difficult to manufacture and to calibrate in a sufficient
accuracy. Therefore a task specific gauge consisting of basic geometric
elements has been developed, which can he calibrated with smallest
uncertainties. After the tested CMM has probed a grid of defined
measuring points, the maximum quality of bevel gears to be measured can
he assessed. |
| Design of a fast, short stroke hydraulic actuator |
| H.D. Tran, D.B. De Bra (1) |
| STC P, 43/1/1994, P.469 |
| Keywords: Ultra-Precision, Hydraulic Actuator, Non-Circular Cutting |
|
Abstract : We developed a fast, short stroke hydraulic actuator, suitable for
toolpost actuation, for spindle motion error correction or for
non-circular cutting. The actuator has a throw of 180 ?m at 2 MPa. The
dynamic response is limited by the hydraulic resonance (? 20,000 rad/s).
The choice of servovalve and feedback design govern the dynamic
response. It shows rise times of better than 25 ms, with accuracies
suitable for ultraprecision machining. In a facing operation, a surface
finish of better than 25 nm R_a was achieved, and for noncircular
cutting, about 40 nm R_a . |
STC S |
| Advantages and industrial applications of three-dimensional surface roughness analysis |
| L. De Chiffre (2), S. Christiansen, S. Skade |
| STC S, 43/1/1994, P.473 |
| Keywords: Surface Roughness, Digital Analysis, Industrial Applications |
|
Abstract : Based on more than a decade's work with digital surface roughness
analysis techniques, this paper describes the advantages as well as the
range of application of three-dimensional surface roughness analysis.
Conventional as well as optical equipment is used for surface mapping,
and a number of specially developed software packages perform the data
processing, including three-dimensional surface filtering and
computation of three-dimensional parameters to describe selected
functional aspects of surface topography. Several cases of industrial
applications are referred, ranging from seal leakage to die wear and
human skin diseases. |
| Grinding mode identification by means of surface characterization |
| H. Trumpold (1), M. Hattori, C. Sutsumi, C. Melzer |
| STC S, 43/1/1994, P.479 |
| Keywords: Surface, Ceramic, Ductile Transition |
|
Abstract : A new method was developed to characterize ground ceramic surfaces. The
method is based on the evaluation of planar areas caused by ductile mode
conditions. The necessary three-dimensional topography data of the
surfaces were obtained by SEM. Applying the evaluation method, surfaces
ground by the two opposite grinding modes, ductile grinding and brittle
fracture grinding, can be distinguished. Moreover, the percentage of
ductile regime ground surface in mixed mode surfaces can be determined.
The method was verified using ceramic samples of different material,
machined applying different mesh numbers of grinding wheel and increase
of depth of cut respectively. |
| A generalized model of the surface generation process in metal cutting |
| K.F. Ehmann (2), M.S. Hong |
| STC S, 43/1/1994, P.483 |
| Keywords: Surface, Generating, Machining |
|
Abstract : Machined surfaces are generated by a variety of processes. each of which
produces a surface with its own characteristic topography. A method for
the prediction of the topography of the generated surfaces has been
developed based on general models of the machine tool's kinematics and a
generalized model of deterministic and non-deterministic cutting tool
geometries. The model termed the surface-shaping system accounts for not
only the nominal or global motions of the machine but also takes into
account errors during machining such as tool runout, machine deformation
and vibration, as well as higher order motions. Based on the surface
shaping system model a computer simulation system has been developed
which facilitates the 3D graphical representation and evaluation of the
topography of the generated surface. |
| Contractless surface measurement with a new acoustic sensor |
| G. Goch, R. Volk / H. Kunzmann (1) |
| STC S, 43/1/1994, P.487 |
| Keywords: Surface, Acoustic Sensor, Contact-Free |
|
Abstract : A standard diamond tip fixed to a micromechanical tuning fork (,32 kHz)
is guided by piezo-electric actuators in a controlled distance of about
100 nm along the inspected surface. The small acoustic fork oscillation
(constantly excited) is (mainly) damped by the air gap between diamond
tip and surface. Thus, constant output signal of the high-C oscillatory
circuit indicates that the tip traces the surface roughness in a
constant distance. First results carried out at roughness standards, map
the profiles obtained mechanically. Difficult materials like laquers,
glasses, ceramics were investigated. |
| The minimum coefficient of friction : what is it ? |
| N.P. Suh (1), M. Mosleh |
| STC S, 43/1/1994, P.491 |
| Keywords: Friction, Surface Engineering, Tribology |
|
Abstract : For many decades, researchers have widely believed that the frictional
force is mainly due to adhesion, an assertion that has not been
supported by experimental results. On the contrary, it has been shown
that much of the frictional force between dry sliding surfaces in a
typical engineering application is due to mechanical interactions. In
this paper, a means of reducing the contribution of mechanical effects
on friction through surface engineering is presented. Friction
coefficient as low as 0.05 between dry sliding surfaces has been
achieved when the mechanical interactions are eliminated. This result
has been achieved based on a hypothetical model of an ideal surface for
low friction. Model experiments were done using a hard smooth surface
coated with a sub-micron thick elastomer layer. Such low friction in
engineering systems without lubricants can have a major impact on the
design of many precision machine components. |
| Measurement of surface roughnesses and topography at nanometer levels by diffuse X-ray scattering |
| D.K. Bowen, M. Wormington / P.A. McKeown (1) |
| STC S, 43/1/1994, P.497 |
| Keywords: Nanotechnology, Surface, Roughness |
|
Abstract : Instrumentation for diffuse X-ray scattering has recently been improved
to the point at which measurements may be made in a laboratory
instrument in times that are competitive with stylus instruments for
areal scans on high-quality surfaces. Theoretical models have also been
implemented with efficient algorithms that permit rapid extraction of
surface roughness, spatial bandwidth and correlation length from the
data. The method is non-contacting, does not depend on detailed
knowledge of optical constants, and gives information on roughnesses
between 0.05 and 5 nm, on correlation lengths from sub-nanometre to tens
of micrometres and on fractal dimensions between 2 and 2.95. The Xray
method is compared to atomic-force microscopy, and is shown to give
similar results for a specimen measurable by each technique, but also to
have greater speed and vastly reduced data acquisition requirements when
averaged data are sought. The X-ray methods have a lower cut-off length
and are both non-contacting and non-destructive. An application to
high-quality Zerodur surfaces is shown. |