CIRP ANNALS 1995
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STC A |
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Assembly planning software
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S. Grewal, p. Tran, A. Bhaskare / L. Farmer (1)
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STC A, 44/1/1995, P.1
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Keywords: Assembling, Planning, Computer Aided Planning (CAP) |
Abstract : A research programme at the CAIRO has led to the development of a
professional software package for assembly system design and management.
This product is now being trialed in various manufacturing organisations
The research activity focused on part attributes for assembly, the
generic assembly tasks involved, the issue of precedence in assembly,
the equipment requirements, the assembly times, and the line balancing
for single and mixed model productions This paper presents an overview
of this development.
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Estimation of production rate in flexible assembly systems
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H. Makino (1), M. Tominaga
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STC A, 44/1/1995, P.7
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Keywords: Assembly Machine, Flexibility, Productivity |
Abstract : Production planning of a new product starts from the estimation of the
production volume per month or per year. The construction of the
standardized flexible assembly systems should be designed to satisfy the
required cycle time. Because a flexible assembly system consists of
several sub-systems such as feeding, transport, assembly and transfer
ones, the total cycle time of the whole system depends upon the cycle
times and repeating numbers of each operation. In this report the cycle
time and the consequent production rate are estimated for typical
flexible assembly systems. Each factor affecting the results is discussed.
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Grouping of used products or cellular recycling systems
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C. Hentschel, G. Seliger (2), E. Zussman / E. Lenz (1)
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STC A, 44/1/1995, P.11
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Keywords: Group Technology, Fuzzy, Disassembly |
Abstract : This paper presents an approach to recycling system planning for used
products at their end-of-life phase We focused on the design of cellular
recycling systems by using group technology. Current approaches employ
design and process attributes for group formation in manufacturing. The
recycling process of a product, however, is characterized by
uncertainties due to usage influences on the product. We introduce in
this paper usage attributes in addition to those mentioned above. In
order to consider the usage attributes, fuzzy-set theory is applied. The
approach is illustrated by designing a cellular system for the recycling
of Cathode Ray Tubes (CRT) from used monitors and TV sets.
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A process model for elastomer-metal-pressfits
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S. Neu, G. Seliger (2)
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STC A, 44/1/1995, P.15
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Keywords: Assembling, Modelling, Press |
Abstract : This paper describes an analytical and numerical process model for
elastomer-metal-pressfits. Based on the mathematical description of the
fitting process, methods and experiments to identify the values of
relevant process parameters are presented. Linear independence of
process parameters is checked by statistical comparison. Besides
analytical process description, numerical methods like Boundary Element
Methods (BEM) are used. Sliding friction coefficients for a number of
elastomer-metal-pressfits are examined experimentally. The results of
the examination of all parameters and the general applicability of the
model are discussed using the example of an elastomer-metal absorbing
spring.
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Direct soldering of electronic components on molded devices
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K. Feldmann (1), M. Gerhard
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STC A, 44/1/1995, P.19
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Keywords: Soldering, Electronic, Quality assurance |
Abstract : Using the great potential of the three-dimensional Molded Interconnect
Devices (3-D MID) necessitates the adaption of the conventional
soldering methods in electronic assembly. The different characteristics
of the soldering technology determine the suitability of various
engineering thermoplastics as substrate material. So several
investigations on application of different thermoplastic materials have
been carried out. Furthermore, the geometric design of the molded
carriers and the impact on the temperature distribution on the board
during the soldering process will be discussed and the possibilities and
the limitations of conventional soldering equipment will be shown.
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A cooperative assembly system using two manipulators with precise positioning devices
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T. Arai (2), H. Osumi, T. Fukuoka, K. Moriyama
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STC A, 44/1/1995, P.23
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Keywords: Assembly, Cooperative Control, Robots |
Abstract : This paper proposes an assembly system with double industrial
manipulators. Each manipulator consists of precise and coarse
positioning devices. Compliance is introduced to accommodate positioning
errors between the double manipulators. A cooperative control scheme for
the two manipulators is studied. The results of experiments verify the
effectiveness of the proposed scheme. This system is well suited for
assembly of large-sized parts.
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STC C |
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Analysis of three dimensional burr formation in oblique cutting
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M. Hashimura, K. Ueda (2), D.A. Dornfeld (2), K. Manabe
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STC C, 44/1/1995, P.27
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Keywords: Burr Formation Analysis, Cutting, Finite Element Method (FEM) |
Abstract : The results of cutting experiments and computer simulation of oblique
cutting conducted in order to understand three dimensional burr
formation and the effect of the tool inclination angle are presented.
Cutting experiments were carried out in a scanning electron microscope
with a micro machining device. Two types of burr were observed: exit
burr on the exit edge of the workpiece and side burr on the side of the
workpiece. The exit burr in oblique cutting was smaller than in
orthogonal cutting, while the side burr in oblique cutting was larger
than its orthogonal counterpart. A three dimensional finite element
method program was also developed to predict three dimensional burr
formation. The simulation showed good qualitative agreement with
experimental data on both burr shape and cutting forces.
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Ultrasonic elliptical vibration cutting
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T. Moriwaki (1), E. Shamoto
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STC C, 44/1/1995, P.31
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Keywords: Cutting, Ultrasonic Vibration, Ultraprecision Cutting |
Abstract : A new cutting method named ultrasonic elliptical vibration cutting is
proposed and applied to cutting of metals by utilizing a new vibrator to
vibrate the cutting tool elliptically at ultrasonic frequency. It is
confirmed experimentally that the cutting performance, in terms of the
cutting force and the chip thickness, is improved significantly by
applying the elliptical vibration to the cutting tool. The experimental
results prove that the method can be applied to practical ultraprecision
cutting of metals.
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High speed milling of dies and moulds. Cutting conditions and technology
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H. Schulz (1), St. Hock
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STC C, 44/1/1995, P.35
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Keywords: Milling, Tool, Wear |
Abstract : Due to the high feed rates, high speed milling (hsm) provides a great
potential of rationalization for machining free formed surfaces like
dies and moulds. The knowledge of the cutting conditions is decisive for
tool life and workpiece quality. By machining with ball end mills,
unfavourable cutting conditions can be avoided by using a tilt angle.
This paper gives a report on a geometrical model to describe the cutting
process by using ball end mills with a tilt angle. Based on this
theoretical model, wear process and optimized cutting conditions for
high speed milling of free formed surfaces can be determined. Practical
experiments confirm the model.
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An improved model of the chip thickness in milling
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S.A. Spiewak (2)
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STC C, 44/1/1995, P.39
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Keywords: Cutting, Milling, Predictive Maintenance |
Abstract : A new class of comprehensive models proposed in this paper integrates
and expands essential features of previously developed analytical and
numerical models The employed systematic modeling methodology
facilitates a stepwise and orderly increase of the model's
sophistication until the desirable level of performance is achieved.
Application of the developed class of models can lead to substantial
improvement of the speed, accuracy and reliability of monitoring and
control applied to the machine, tool and cutting process. The accuracy
of representative models is compared under realistic machining conditions.
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Computer-aided predictive cutting model for forces in face milling allowing for tooth run-out
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E.J.A. Armarego (1), J. Wang, N.P. Deshpanede
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STC C, 44/1/1995, P.43
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Keywords: Modelling, Milling, Cutting |
Abstract : In this paper the development of a predictive cutting model and software
module for the average and fluctuating force components, torque and
power in Face milling operations is outlined and discussed. The model,
which is based on the mechanics of cutting approach and incorporates the
many tool and cut process variables as well as the inevitable tooth
run-out, has been assessed by numerical simulation and experimental
testing. The model has been verified qualitatively and quantitatively
and has highlighted the importance of the tooth run-out on the force
fluctuations. This work provides a further step towards establishing
machining on a sound scientific, predictive and quantitative basis.
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A new parametric approach for the assessment of comprehensive tool-wear in coated grooved tools
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I.S. Jawahir (2), P.X. Li, R. Ghosh, E.L. Exner
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STC C, 44/1/1995, P.49
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Keywords: Tool, Machining, Wear |
Abstract : This paper presents a new methodology for evaluating tool-wear in
grooved tool inserts, based on experimental analysis of chip flow
Machining experiments using high speed filming techniques and scanning
electron microscopy reveal the strong influence of chip-grove parameters
on tool-wear. Four different grooved tool inserts, each with four
different coatings, are tested under a wide range of cutting conditions
A new tool life relationship, including the effects of chip groove
parameters and tool coatings, has been developed and validated for a
range of machining conditions on steel 1037M work material.
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Improvement of tool life through variable feed milling of Inconel 600
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M. Balazinski, V. Songméné / L. Kops (1)
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STC C, 44/1/1995, P.55
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Keywords: Feed, Tool, Wear |
Abstract : A new approach for improving the cutting tool life by varying the feed
throughout the cutting process has been developed at Ecole Polylechnique
de Montreal. This paper presents the study leading to the selection of
the optimal feed variation parameters for the face milling of Inconel
600. The experimental results indicate that the most influential factors
are the amplitude and duration of each feed variation step. A ten
percent sinusoidal feed variation cycle about the optimal feed, with
five seconds incremental steps, increases the cutting tool life by a
minimum of 30 percent. The comparison was based on a constant material
removal rate.
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Real-time tool breakage monitoring for NC milling process
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J.M. Lee (1), D.K. Choi, J. Kim, C.N. Chu
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STC C, 44/1/1995, P.59
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Keywords: Milling, Fracturing, Detecting |
Abstract : This paper presents real-time tool breakage detection in NC milling
process by monitoring cutting force. Cutting force was indirectly
measured by the feed drive AC motor current. Modeling of the feed drive
system and calibration with a tool dynamometer show that the sensitivity
of the feed drive motor current is sufficient to characterize tool
breakage. AR 1 model with tool-runout is used to determine tool
breakage. 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.
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The energy quanta and the entropy - New parameters for identification of the machining processes
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J. Peklenik (1), S. Dolinsek
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STC C, 44/1/1995, P.63
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Keywords: Identification, Energy Quanta, Entropy |
Abstract : The contribution presents some new findings in search for a more
comprehensive description of the machining processes, such as turning,
milling and drilling. The experimentally determined power spectra of the
input, transformation and output energy are used for computing the
energy quanta and the entropy of the processes. It is shown, that the
change of the entropy allows to explain some of the process behaviours.
By introducing the energy quanta, as a derivative of the energy power
spectra, a new parameter has been confirmed which contributes to better
understanding of the machining process physics.
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On a thermo-mechanical model of shear instability in machining
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Z.B. Hou, R. Komanduri (1)
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STC C, 44/1/1995, P.69
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Keywords: Machining, Cutting, Shear |
Abstract : Shear instability was observed experimentally in machining some of the
difficult-to-machine materials, such as hardened alloy steels, titanium
alloys, and nickelbase superalloys yielding cyclic chips. Recht in 1964
developed a classical model of catastrophic shear instability in
machining. In this investigation, based on the analysis of cyclic chip
formation in machining, possible sources of heat (including preheating
effects by these heat sources) contributing toward the temperature rise
in the shear band were identified. The temperature rise was calculated
using Jaeger's classical solutions of stationary and moving heat
sources. Recht's original catastrophic shear instability model for shear
localization was extended by predicting analytically the conditions for
the onset of shear localization.
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Optimization of tangential tool shift in gear hobbing
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K.D. Bouzakis (1), A. Antoniadis
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STC C, 44/1/1995, P.75
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Keywords: Hobbing, Gear, Wear, Optimization |
Abstract : Gear hobbing is an efficient method of gear manufacturing. Due to the
fact that during the cutting process, every hob tooth always cuts in the
same generating position, where the formed chip has different geometry,
the resulting tool wear is not uniform on any particular hob tooth. In
order to overcome this problem, the hob is shifted tangentially after a
certain number of cuts. The optimum selection of the shift displacement
and the number of gears (shift amount), after which the hob has to be
shifted, leads to a uniform tool wear and consequently increases the
amount of the hobbed gears per tool regrinding, until the maximum
permitted tool wear is reached. In the present paper, an experimentally
verified computational procedure is presented, which enables the
determination of optimum values for the shift displacement and for the
corresponding shift amount, by considering the wear behaviour of the hob
teeth in the individual generating positions.
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Mathematical model for the establishment of the materials machinability
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S. Enache (1), E. Strajescu, C. Opran, C. Minciu, M. Zamfirache
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STC C, 44/1/1995, P.79
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Keywords: Machinability, Mathematical Model, Titanium Alloys |
Abstract : This paper presents a new mathematical model for the establishment of
the partial and global machinability. The model is basal on the
evaluation criteria of the material's machinability and permits the
establishment of the best material, who can be utilised from the point
of view of the machinability. Also, it permits the establishment of the
machining condition regarding cutting process, at wich the machinability
is optimal from the point of view of the productivity and of the
economic efficiency. Are shown, the results of the experimental
researches in the case of titanium alloys cutting with turning tools.
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STC Dn |
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Computer-aided optimal design strategy of power transmission systems
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B. Kaftanoglu (1), E. Ulugül, N. Carkoglu
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STC Dn, 44/1/1995, P.83
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Keywords: CAD, Design, Optimization |
Abstract : A mechanical power transmission system consists of mainly shafts, gears
and bearings, where each machine element can be optimally designed.
However in a power transmission system each design variable such as
pitch diameters of gear and diameters of bearings have certain
constraints. These constraints effect the design of the other member
like the shaft. A design strategy is developed for the optimal
integrated design of a mechanical power transmission system including
the constraints of each member and with the view to satisfy a global
optimum for the system.
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Light robot arm based on inflatable structure
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N. Salomonski, M. Shoham (2), G. Grossman
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STC Dn, 44/1/1995, P.87
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Keywords: Robot, Flexible, Mechanism |
Abstract : This paper deals with a new kind of mechanical structure for robotic arm
based on elements made of thin, inflatable shells. This approach offers
the advantage of increasing the strength-to-weight ratio of the robot.
Moreover, it allows compact packaging and ease of robot deployment,
critical in hard-to-reach spaces, where volume and weight are of utmost
importance. In addition, the robot is safer due to less damage in case
of collision. At this work we test the feasibility of using that new
kind of mechanical structure to a practical implementation, by
simulation and by operative experiment.
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An intelligent object oriented approach to the design and assembly of press tools
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H.S. Ismail, K.K.B. Hon (2), K. Huang
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STC Dn, 44/1/1995, P.91
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Keywords: Design, Expert Systems, Object Orientation |
Abstract : In recent years, research communities and industries have started to
develop knowledge-based tooling design systems to tackle the common
difficulties that most companies have. The most widely used strategy is
accommodating the know-how into an expert system and linking it with a
CAD system This paper describes the structure and operation of a
prototype intelligent system for progressive die design and
manufacturing. The system is developed using X Window C programs to
create the interface linking the CAD package, AutoCAD, and the expert
system shell, Kappa. AutoCAD is used for the input of the piece part
geometry, creating the temporary drawings and final design drawings of
the tool parts and assembly. Kappa is used to create the knowledge base,
the databases of the standard tool parts, and the menu system for
entering design data. C programs are also used for some intensive
computations, for example, calculating the best material utilisation.
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Guaranteeing manufacturability of CSG operations
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W.A.H. De Vries, F.L.M. Delbressine, A.C.H. Van Der Wolf (1)
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STC Dn, 44/1/1995, P.97
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Keywords: Modelling, Computer Aided Design (CAD), Computer Aided Process Planning (CAPP) |
Abstract : The paper deals with the integration of design, process planning and
manufacturing using Constructive Solid Geometry (CSG) design operations.
This integration is achieved by mapping CSG design operations onto
manufacturing operations. The mapping is realised such that the
manufacturability of the current design can be guaranteed while
designing and that a right-first-time production can be realised.
Especially the mapping of the CSG operator "unite two solids" onto the
material removal manufacturing technique milling will be dealt with
extensively in this paper. The chosen approach is described and
explained using an example.
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An interaction mechanism for 3D object-oriented feature-based models in interactive design and simulation
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A. Fischer, K.K. Wang (1)
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STC Dn, 44/1/1995, P.101
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Keywords: Feature, Object Oriented Programming, CIM |
Abstract : In engineering applications such as interactive design and simulation,
some of the main object manipulations include feature interaction.
Today's CAD systems provide object oriented structures which can
explicitly represent functional and geometrical interactions among
features. However, conventional interaction algorithms for manipulating
these structures cannot cope with non-geometrical information such as
feature functionality. Interaction among features plays an essential
role in defining functionality. In this paper, a new method is described
which focuses on implementation of an interaction mechanism for design
and simulation. Two interaction categories are handled: (1) neighbouring
interaction, which is primarily geometrical (blending and trimming) and
(2) functional interaction (machining). Since most interactions are
performed in a sub-domain rather than in the entire domain, the
advantage of the locality property is considered in both cases.
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On the support of design process management in integrated design environment
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W.J. Zhang, C.A. Van Luttervelt (1)
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STC Dn, 44/1/1995, P.105
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Keywords: Design Process, Management, Computer-Aided Design |
Abstract : The computer-aided design process management is noticed as an
intelligent feature of modern integrated CADCAM systems. This paper
addresses this problem in the context of developing an integrated
software environment for designing and manufacturing of mechanical
systems. Emphasis is placed on the discussion of the design process
management concepts and computer (or data) model which structures and
represents various kinds of design process related information An
experimental implementation for CADCAM of compound cam mechanisms has
been made, which gives verification of the idea.
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Active data driven design using dynamic product models
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D.S. Domazet, F.N. Choong, D. Sng, N.C. Ho, S.C.Y. Lu (2)
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STC Dn, 44/1/1995, P.109
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Keywords: Product Development, Product Modelling, Concurrent Engineering |
Abstract : In this paper a new approach to event-driven product design is proposed.
It is based on active data of dynamic product models. The dynamic
product model contains ECA (Event-Condition-Action) rules that trigger
execution of tasks or propagate updates to the product data. When
certain states of the product design are reached, new design tasks are
initiated or a new product model state is automatically reached as the
result of a design change propagation. This approach is very suitable
for concurrent engineering where the order of design tasks can not be
specified in advance. Dynamic product models are stored in an
object-oriented database system accessible by all concurrent engineering
participants through a software layer that manages the ECA rules. Syntax
for the ECA rules and their use in driving concurrent engineering are
proposed in this paper.
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Representing background information for product description to support product development process
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F. Kimura (2), H. Suzuki
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STC Dn, 44/1/1995, P.113
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Keywords: Design, Product Development, Product Modelling |
Abstract : This paper describes an attempt to capture and to represent product
information, which is used for generating product definition, but is not
explicitly represented in product description. In this paper, such
information is called background information. It includes requirements,
specifications, assumptions, constraints, decision history,
trial-and-error processes, and "rationale" in general. It plays an
important role by providing information about underlying reasoning for
product development. The information is to be captured by interaction
with practical design processes, and to be represented by a structural
framework based on an object oriented approach.
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Facility model for life cycle maintenance system
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S. Takata (2), H. Hiraoka, H. Asama, N. Yamaoka, D. Saito
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STC Dn, 44/1/1995, P.117
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Keywords: Computer Models, Maintenance, LifeCycle |
Abstract : For bringing out full capabilities of manufacturing facilities, various
maintenance activities are necessary throughout the facility life cycle
from design to the end of its life We have been proposing the necessity
of a support system for achieving efficient and consistent life cycle
facility management based on a facility model In this paper, the
structure of the facility model is presented. The model can represent
the hierarchical structure of facilities. It also provides flexible
means to represent various technical information relevant to the
facility management. The effectiveness of the model is shown by a
deterioration evaluation system of the facility.
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Actual conceptual design process for an intelligent machining center
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Y. Hatamura, T. Nagao (2), M. Mitsuishi, M. Nakao
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STC Dn, 44/1/1995, P.123
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Keywords: Conceptual Design Process, Intelligent Machining Center |
Abstract : The conceptual process in design proceeds in the order "Performance
Mechanism Structure;" and advances through "Application and Evaluation"
in what may be thought of as a conceptual development spiral. In actual
designs, these spirals are repeated and the process proceeds in the
order "Conceptual sketch- Plan drawing-Final plan drawing." Progress in
the conceptual process corresponds to equivalent progress in the detail
design operation. "Eight design principles for machines" and "Six design
principles for intelligent manufacturing systems" are proposed. By using
these principles, a fundamental structure for intelligent manufacturing
systems is established and applied to the design of an intelligent
machining center that has been built and tested. Testing and evaluation
of the machining center that was developed verified the validity and the
effectiveness of the proposed concepts.
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A proposal to a product modelling language to support conceptual design
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K. Andersson, p. Makkonen, J.G. Persson (2)
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STC Dn, 44/1/1995, P.129
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Keywords: Conceptual Design, Design Language, Mechanisms |
Abstract : Computer aid for conceptual design has so far only been available for
some specialized domains. The main reason for this is that conceptual
design work is a very complex process that is difficult to represent in
computer models. One approach to support this type of design work is the
CANDLE modeling language which enables the use of engineering
terminology for modeling early design work. This paper describes a
further development of the CANDLE modeling language in order to support
the early design phases of mechanisms and manipulator systems. This can
be accomplished by expanding the basic taxonomies of engineering
terminology with physical and solution principles that are specific for
design of mechanisms and manipulator systems.
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A new interface for conceptual design based on object reconstruction from a single freehand sketch
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H. Lipson, M. Shpitalni (1)
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STC Dn, 44/1/1995, P.133
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Keywords: CAD, Conceptual Design, Interface |
Abstract : A new system has been developed for improving user interaction with CAD
systems, particularly in the conceptual design stage. The system is
based on interactive, part-by-part formation of a geometrical model
using freehand sketching. A single 2D inaccurate projection is entered
in the form of a line drawing. The system analyzes and interprets the
input and then reconstructs a 3D model of the object most likely to be
represented by the sketch. This 3D model can be further manipulated or
modified, and more parts can be sketched. This approach provides a
fluent and intuitive tool for conceptual design. In the paper, the
proposed system is presented and the basic ideas are discussed and
exemplified.
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Conceptual Modelling for Industrial Design
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F.-L. Krause, J. Lüddemann, A. Striepe
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STC Dn, 44/1/1995, P.137
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Keywords: Conceptual Product Design, Interactive Industrial Design System, Geometric Modelling |
Abstract : Conceptual product data in packages, digital mock-ups or layout plans
are the basis for designing the shape of a product. A system approach is
presented which allows for the incorporation of these restrictive data
in an appropriate manner for computer-aided styling tasks. The highly
interactive and easy-to-use system components support the abstraction,
modification and verification of conceptual data for preparation as well
as the creative and intuitive modelling of three dimensional shapes.
Characteristic of the new modelling approach is the strong analogy with
the traditional, still predominant clay modelling process in the field
of industrial design.
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STC E |
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Pulsed laser materials processing, ND-YAG versus CO2 lasers
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F.O. Olsen / L. Alting (1)
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STC E, 44/1/1995, P.141
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Keywords: Laser, Welding, Cutting |
Abstract : Pulsed laser materials processing is widely applied in fine cutting,
welding and hole drilling. In this paper pulsable C02-lasers and
ND-YAG-lasers are compared for pulsed laser cutting, welding and hole
drilling. In laser cutting the performance of a superpulsed C02-laser in
Aluminium cutting is described and compared to typical ND-YAG-laser
cutting data. In pulsed laser welding, experimental investigations in
welding AISI 316 stainless steel, where hot cracking sensitivity has
been addressed, applying a ND-YAG laser and a superpulsed C0_2 -laser,
will be described. Finally metal, polymer and ceramics laser drilling
applying different C0_2 -lasers will be described and compared to
ND-YAG-laser performance.
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About the application of fuzzy controllers in high-performance die-sinking EDM machines
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M. Boccadoro, D.F. Dauw (2)
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STC E, 44/1/1995, P.147
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Keywords: EDM, Die Sinking, Fuzzy control |
Abstract : The paper deals with the problematics of die-sinking optimization and
control systems As it is known, Electric Discharge Machining is partly
stochastic in nature In the past, various optimization control
algorithms have been developed and implemented to improve the overall
performance of EDM die sinkers. AGIE has introduced Adaptive Control
Optimization (ACO) algorithms as well as Adaptive Control Constraint
(ACC) regulators To satisfy the customers requirements even better, new
techniques have been studied, and the use of fuzzy controllers is now
reality In the paper, a description of fuzzy controllers is given, its
principles and results on commercial EDM AGIE die sinkers It is proven
that in comparison with traditional controllers, fuzzy regulators are
definitely well suited in an EDM environment.
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Recent developments in laser system tehnology for welding applications
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P. Hoffmann / M. Geiger (1)
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STC E, 44/1/1995, P.151
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Keywords: Laser, Welding, Quality Assurance |
Abstract : Further spreading of laser welding technology essentially needs an
improvement of the reliability of the welding systems and an enlargement
of applicability even at complicated workpiece structures. With this
paper measures are proposed in order to meet these goals:
- stabilization of the laser source by a closed loop control of the
laser power
- optimization of the laser beam guiding and forming by use of Adaptive
Optics.
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Benchmarking of rapid prototyping techniques in terms of dimensional accuracy and surface finish
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R. Ippolito (1), L. Iuliano, A. Gatto
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STC E, 44/1/1995, P.157
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Keywords: Rapid Prototyping, Accuracy, Roughness |
Abstract : Dimensional accuracy and surface finish are the cornerstone of Rapid
Prototyping (RP) especially if the models will be used for the
production of tools as mould or EDM electrodes. The paper deals with the
development, manufacture and testing of benchmark to investigate
dimensional accuracy and surface finish. A new technique of checking the
machine quality of a RP workpiece according to the ANSI-ISO standards
is presented. Moreover the surface of RP model were observed by SEM
microscope.
|
|
Surface modification of steel by a small diameter plasma arc
|
|
T. Miyazaki, S. Yoshioka, T. Kimura, A. Komatsu, N. Kinoshita (1)
|
|
STC E, 44/1/1995, P.161
|
|
Keywords: Plasma, Hardening, Alloy |
Abstract : A plasma arc, which is produced through a small diameter nozzle, is
applied to surface modification of steel. The nozzle diameters are 0.2
and 0.3 mm; the arc diameter is so small that the power density is of
the order of 10^6 W/cm2. This is applicable to small area surface
modifications. In case of surface hardening due to self-quenching,
Vickers hardness of 1000 is obtained for AISI 1045; melting does not
occur. In case of alloying with SIC particles, Vickers hardness of 1200
is obtained for AISI 1010; furthermore, the wear resistivity is
increased by a factor of several tens.
|
|
Electrode wear process in electrical discharge machining
|
|
N. Mohri, M. Suzuki, M. Furuya, N. Saito / A. Kobayashi (1)
|
|
STC E, 44/1/1995, P.165
|
|
Keywords: Electrical Discharge Machining, Electrode, Wear |
Abstract : This paper deals with a synthetic consideration of electrode wear
phenomena in electrical discharge machining. Time dependence of an
electrode shape was observed through on-the-machine measurement. While
the electrode wears at the edge portion in the beginning of machining,
it grows at the flat portion in the longitudinal direction. In the
stationary state of machining, the wear rate of an electrode is affected
by the materials of work piece. Taking account of the precipitation of
turbostratic, carbon on the electrode, the presence of catalyst in the
work piece material is considered. The turbostratic carbon on the
surface of electrode prevents the electrode from spark erosion in EDM.
|
|
Study of the white layer of a surface machined by die sinking Electro Discharge Machining
|
|
J.P. Kruth (1), L. Steven, L. Froyen, B. Lauwers
|
|
STC E, 44/1/1995, P.169
|
|
Keywords: Electro Discharge Machining (EDM), Surface Integrity |
Abstract : Electro discharge machining (EDM) causes a white layer at the surface of
a workpiece. The research work, described in this paper, aims to acquire
a profound knowledge of this layer. The influence of workpiece material,
electrode material and type of dielectric on the composition and the
metallographic phases of the white layer is discussed.
The measurements yield that the use of an oil dielectric increases the
carbon content in the white layer. A water dielectric on the other hand,
causes a decarbonisation. The carbon in the white layer machined in an
oil dielectric appears as iron carbides (Fe3C) in columnar, dendritic
structures. This is a result of the very rapid re-solidification of the
molten material. In between the carbide dendrites, rest austenite and
also some ferrite can be found.
|
|
Modular method for microparts machining and assembly with self-alignment
|
|
H.H. Langen, T. Masuzawa (1), M. Fujino
|
|
STC E, 44/1/1995, P.173
|
|
Keywords: EDM, Micromachining, Assemblies |
Abstract : A low-cost prototype has been developed for modular machining and
assembly of 3D microparts with self-alignment Microparts and/or their
microtools were machined and temporarily stored in a mini-worktable of a
MMA (modular machining assembly) unit where further machining and/or
(sub)assembly techniques were applied WEDG (wire electrodischarge
grinding), micro-EDM and reverse micro-EDM were used for material
machining, and additionally enabled automatic microparts alignment for
further assembly purposes Ultrasonic vibration was applied during
(micro)parts assembly. The machining and assembly of a micropipe and
macrocylinder combination is given as a fabrication example.
|
|
Modelling and monitoring interelectrode gap in pulse electrochemical machining
|
|
K.P. Rajurkar, B. Wei, J. Kozak, J.A. McGeough (1)
|
|
STC E, 44/1/1995, P.177
|
|
Keywords: Electrochemical Machining, Modelling, Accuracy |
Abstract : Pulse electrochemical machining (PECM) provides an economical and
effective method for machining high strength, heat resistant materials
into complex shapes such as turbine blades of titanium alloys. The
dimensional accuracy of PECM can be improved if a small interelectrode
gap is maintained. This paper presents an interelectrode gap model for
estimating machining parameters for the minimum gap size under the limit
of electrolyte boiling A specially-built PECM cell and a high speed data
acquisition system are used to acquire the pulse current signal for
developing a non-line monitoring strategy. A stochastic analysis of the
current signal indicates a linear correlation between the gap size and
the variance of the filtered current signal. An on-line monitoring
system based on this correlation is proposed for the PECM process.
|
|
On-line monitoring of the solidification front in metal casting
|
|
J.H. Chun, R.C. Lanza, N. Saka, M.M. Hytros / N.P. Suh (1)
|
|
STC E, 44/1/1995, P.181
|
|
Keywords: Casting, Control, Sensor |
Abstract : In the continuous and semi-continuous casting of metals and alloys, the
shape and location of the solidification front greatly affect the
quality of castings. Yet, there is no real-time sensor available to the
casting industry for monitoring the solidification front. A recently
invented three-dimensional imaging technique for tracking the
liquid/solid interface in the solidifying casting is presented. Issues
involved in the application of the technique to the feedback control of
continuous casting processes are also addressed.
|
STC F |
|
Some applications of the Barlat 1991 yield criterion
|
|
F.A.C.M. Habraken, J.H. Dautzenberg (2)
|
|
STC F, 44/1/1995, P.185
|
|
Keywords: Aluminium, Yield, Anisotropy |
Abstract : Nowadays the accuracy of (FEM) analyses of forming processes is to a
large extent determined by the assumption of realistic constitutive
equations for the description of the material and its interface with
tooling/ Concerning aluminium alloys there are reasons for attention to
the first topic these alloys often show significant anisotropy and in
general have the reputation of being troublesome in analyses of forming
processes. Through some applications, it will be shown that a yield
criterion proposed by Bbarlat t al. (1991) gives good results. Last
criterion is based on the generally accepted framework of a yield
surface and associative flow. It thereby preserves simple operational use.
|
|
The inverse approach for the determination of constitutive equations in metal forming
|
|
J.C. Gelin (1), O. Ghouati
|
|
STC F, 44/1/1995, P.189
|
|
Keywords: Identification, Material, Finite Element Method |
Abstract : An inverse identification method for material parameters estimation is
proposed in this paper. This method allows an accurate identification by
avoiding the usual assumptions made in order to convert experimental
measures into constitutive variables. A sensitivity analysis is
developed to evaluate the effect of parameters variations on the
material response. This analysis is based on a direct differentiation
method allowing an accurate sensitivity determination with a low
computational cost compared to a finite difference method.
This inverse identification procedure is applied to the determination of
the viscoplastic behaviour of aluminium alloys in hot working using both
the plane strain compression test and the axisymmetric compression test.
The results obtained with both tests are the same.
|
|
An explicit model for the thermal-mechanical analysis of hot metal forming processes
|
|
F. Micari (2), L. Fratini, N. Alberti (1)
|
|
STC F, 44/1/1995, P.193
|
|
Keywords: Hot, Forming, FEM |
Abstract : In the paper the authors propose a new finite element code for the
coupled thermal-mechanical analysis of hot metal forming processes. As
regards the mechanical problem, an explicit algorithm based on the
solution of the dynamic equilibrium equation and an explicit time
integration scheme is used, while the heat transfer analysis is based on
the solution of the thermal equilibrium equations; in order to put the
thermal problem in an explicit linear form a three level scheme has been
employed for the discretization of the time variable. The model is based
on a staggered procedure, in which the mechanical and the thermal
analysis are carried out with respect to different time horizons; in
fact while the analysis of the mechanical problem is performed
increasing the velocity of the process, as it is usual when an explicit
formulation is used, such an artifice cannot be accepted for the thermal
problem which is strongly time dependent.
|
|
Fractal geometry used for the characterisation of sheet surfaces
|
|
E. Doege (1), B. Laackman, B. Kischnick
|
|
STC F, 44/1/1995, P.197
|
|
Keywords: Sheet Metal, Surface, Friction |
Abstract : Common technical roughness parameters are not able to characterise
technical surfaces clearly. Only the specification of additional
parameters may allow a statement about the surface character. Based on
the Weierstiraß-Mandelbrot function a fractal model for the
characterisation of surface profiles was developed. Only two parameters
are needed to distinguish different surfaces. Thereby a surface profile
is measured by means of a surface profiler. To find a suitable fractal
description for a given surface, the power spectra of the function and
the empirical data are used. Afterwards the empirical power spectrum is
interpreted as the power spectrum of a Weierstiraß-Mandelbrot fractal
function with fractal parameters to be determined. Additionally this
technique also allows the qualitative reconstruction of a previously
measured profile.
Series of measurements using the materials X5 CrNi 1810, St12 03, and
A/Mg3 proved the model to be well applicable to sheet surfaces.
Investigations were carried out in order to verify the influence of
parameters relevant for sheet metal forming on the fractal model.
|
|
Evaluation of temperature and heat transfer conditions at the metal forming interface
|
|
W. Nshama, J. Jeswiet (2)
|
|
STC F, 44/1/1995, P.201
|
|
Keywords: Forming, Heat Transfer |
Abstract : This work is part of an on-going study of the physics of the
die-workpiece interface in metal forming. An experimental investigation
has been conducted on the temperatures at the interface in metal
forming. This work differs from others in that the temperatures are
measured directly at the die-workpiece interface. The raison d'être for
this work is the experimental data from these measurements can be used
to derive accurate heat transfer coefficients (thermal resistances). For
the experiments in this work two flat platens were used as dies with
both hot and cold solid cylindrical billets. The results indicate that
this method can provide a reliable means of predicting the contact
resistance.
|
|
Low-speed mixed lubrication of metal forming processes
|
|
W.R.D. Wilson / S. Kalpakjian (1)
|
|
STC F, 44/1/1995, P.205
|
|
Keywords: Tribology, Lubrication, Metal Forming |
Abstract : In the mixed lubrication regime, part of the interface load is carried
by asperity contact and part by the pressurized lubricant in surface
valleys. Under high-speed conditions, the lubricant is pressurized by
wedge action in the inlet zone which lies upstream of the work zone.
However, even under low speed conditions, where the inlet zone is
inactive, significant lubricant pressures can be generated by wedge
action in the work zone. The wedge is due to the reduction in average
film thickness created by progressive asperity flattening as plastic
deformation proceeds.
|
|
Direct observation of contact behaviour to interprete the pressure dependence of the coefficient of friction in sheet metal forming
|
|
A. Azushima / H. Kudo (1)
|
|
STC F, 44/1/1995, P.209
|
|
Keywords: Drawing, Friction, Lubrication |
Abstract : In a previous work, for the determination of the relationship between
coefficient of friction and contact pressure to be used in the numerical
process simulation, the author found experimentally that the coefficient
was constant in the lower pressure range, whilst over 0.3 s , it
decreased with increasing pressure. In the present work, a flat tool
drawing apparatus which consists of a transparent die of quartz, a
microscope with a CCD camera and a video system is developed to observe
in situ the contact behaviour at the interface directly. Thus, the lower
average pressure regime is characterized by isolated contact zones,
while the higher pressure regime by oil pockets and oil permeation into
the contact zone Based on this lubricant mechanism, the above
relationship can be qualitatively interpreted.
|
|
Tribology during hot, flat rolling of steels
|
|
P. Munther, J.G. Lenard (1)
|
|
STC F, 44/1/1995, P.213
|
|
Keywords: Friction, Rolling, Metal |
Abstract : Tribology, defined to include the transfer of heat and forces at the
surface of contact, is studied. The parameters affecting hot tribology
are presented and discussed. An optical technique is used to monitor the
forward slip during hot rolling, in air, of low carbon steel slabs. The
forward slip is then related to the coefficient of friction by a finite
element method. While previously published data indicate that the
coefficient of friction increases, decreases, reaches a plateau before
falling or remains steady with increasing temperatures, the current
results clearly show that m decreases with temperature and increases
with load. The coefficient of heat transfer is also strongly dependent
on the process parameters. The data is used to shed new light on roll wear.
|
|
A new friction and lubrication test for cold forging
|
|
N. Bay (2), O. Wibom, J. Aa. Nielsen
|
|
STC F, 44/1/1995, P.217
|
|
Keywords: Forming, Friction, Lubrication |
Abstract : This paper presents a new friction and lubrication test for cold forging
The test allows controlled variation of the surface expansion in the
range 0-2000%37;, the tool temperature in the range 20-270°C and the
sliding length between 0 and infinite. Friction is decreasing with
increasing temperature in the range 30-150°C. Above this temperature
range friction increases. As regards lubricant performance Lubrication
Limit Curves (LLC) are plotted in a sliding length-surface enlargement
diagram with the tool temperature as a parameter. Larger tool
temperature implies lower acceptable surface expansion and sliding length.
|
|
FEM simulation of hot forging with dynamic recovery process
|
|
S.I. Oh (2), S.H. Im
|
|
STC F, 44/1/1995, P.223
|
|
Keywords: Finite Element Method, Forming |
Abstract : In metal deformation at elevated temperature, the strain hardening
produced by the deformation tends to counteracted by dynamic recovery,
and strain cannot be a proper variable to represent flow stress under
this condition. In order to take into account the dynamic recovery
process, constitutive equation should include a state variable which
represents the internal microstructure. In this paper, FEM formulation
has been established to accommodated the dynamic recovery process. Then
non-isothermal simple compression processes by mechanical press and
hammer were simulated. The results were compared to those by the
conventional flow stress representation.
|
|
Preform design for forging rotationally symmetric parts
|
|
F.H. Osman, A.N. Bramley (1)
|
|
STC F, 44/1/1995, P.227
|
|
Keywords: Forging, Upper Bound, Simulation |
Abstract : This paper describes an upper bound modelling based technique to design
preforms for forging of rotationally symmetric parts. A reversing
algorithm which results in improved metal flow in the final stages of
filling the cavity is applied to the precision forging of bevel gears.
The predicted preform has a simple rotationally symmetrical profile
which accommodates the simultaneous filling of the gear teeth.
Experimental results show that the preform designed by this technique
requires less energy in the final stages of the forging.
|
|
Life estimation of extrusion dies
|
|
A.E. Tekkaya, A. Sonsöz / K. Lange (1)
|
|
STC F, 44/1/1995, P.231
|
|
Keywords: Fatigue-Crack, Extrusion-Dies |
Abstract : The fatigue behaviour of cold extrusion dies is investigated The
effective stress intensity factor at different locations of the die
inlet of a typical axisymmetric extrusion die has been calculated by the
finite element code method Applying the Paris/Erdo?an fatigue law to
this calculated data, the crack growth has been simulated. From the
crack-growth-rate the life of the extrusion die has been estimated. The
agreement with the experimental results is satisfactory within the
limits of experimental uncertainties. Furthermore, the experimentally
observed behaviour of the crack growth, i. e stable-instable-stable
growth with final fracture, is simulated perfectly.
|
|
Axial-radial forming of tubular components
|
|
D. Schmoeckel (1), F.D. Speck
|
|
STC F, 44/1/1995, P.235
|
|
Keywords: Process, Simulation, Tube |
Abstract : The axial-radial forming process was developed at the Technical
University of Darmstadt, combining elements of upsetting and rotary
swaging. The process permits to produce defined thickness increases on
tubular components, such as required for instance for the bearing seats
of a transmission shaft. Axial-radial forming is performed on a modified
rotary swaging machine additionally equipped with an upsetting unit and
a heating station. The principle of the process will be presented and
examples for the application potential will be shown. Parallely to the
experimental research the process has been simulated with the
finite-elements method.
|
|
Computerized numerical simulation of roll-forming process
|
|
M. Kiuchi (1), K. Abe, T. Onodera
|
|
STC F, 44/1/1995, P.239
|
|
Keywords: Roll, Forming, Simulation |
Abstract : A computerized numerical simulation system for mid roll-forming was
developed. It was applied to various roll-forming processes of ERW
(electric resistance welded) pipes, light gauge section steels,
deck-plates and others. Through simulations, effects of pass-schedule,
geometry and position of roll, dimension of product and mechanical
properties of metal sheet on deformation features of metal sheet at
every forming stage, stress and strain occurring in it, roll separating
force, roll driving torque and dimensional accuracy of product were
clarified. The system is now being used for design and prediction of
desirable profiles of forming rolls, roll positions and other operation
factors. It is also being successfully used to design pass-schedules for
newly requested products.
|
|
Controlled FEM simulation for determining history of blank holding force in deep drawing
|
|
K. Osakada (1), C.C. Wang, K.I. Mori
|
|
STC F, 44/1/1995, P.243
|
|
Keywords: Deep Drawing, Finite Element Method (FEM), Control |
Abstract : To fully utilize the recent deep drawing machines with variable blank
holding force, a method for determining an optimal history of the blank
holding force is proposed. In this approach, a proper force which does
not cause wrinkling and localized thinning is searched for at each
deformation step by the finite element method. The result is supplied to
the actual drawing machine. The effectiveness of the present method is
demonstrated by the experiments of axisymmetric deep drawing with the so
obtained history of blank holding force for aluminium sheets.
|
|
Control of blank holder force to eliminate wrinkling and fracture in deep drawing rectangular parts
|
|
M. Ahmetoglu, T.R. Broek, G. Kinzel, T. Altan (1)
|
|
STC F, 44/1/1995, P.247
|
|
Keywords: Deep Drawing, Wrinkling, Fracture |
Abstract : The predominant failure modes In stamping of sheet metal parts (deep
drawing and stretch forming) are wrinkling and fracture. In many cases
these defects may be eliminated by appropriate control of the Blank
Holding Force (BHF). This paper summarizes the results of a recent study
on the formability of rectangular parts from aluminum alloy 2008-T4.
Wrinkling and fracture limits have been determined and BHF control
methods have been developed to eliminate defects, improve part quality,
and increase the draw depth.
|
|
Closed loop control system for blankholderforces in deep drawing
|
|
K. Siegert (2), E. Dannenmann, S. Wagner, A. Galaiko
|
|
STC F, 44/1/1995, P.251
|
|
Keywords: Forming Press, Hydraulic Equipment, Control System |
Abstract : When drawing non-axissymmetric sheet metal parts it is necessary to
control the flow of material between the lower and upper binder in such
a manner that prevents the occurrence of both tears and wrinkles in the
drawn part. One possibility for the control of the material flow is
through the deliberate adjustment of the normal forces. If one can
measure the flow-in of the material in the die as a function of punch
penetration with a special sensor, and if this information can be used
to produce an average empirical desired flow-in curve, then with the
implementation of modern hydraulic drawing facilities in the press table
and/or the implementation of special dies with hydraulically supported
segmented binders it is possible to build a closed-loop control system
which allows for the automatic response of the drawing facilities or the
hydraulic systems of the drawing die in light of changing friction
conditions.
|
|
Investigation into manufacturing of very long cups by hydromechanical deep drawing and ironing with controlled radial pressure
|
|
D.Y. Yang (2), J.B. Kim, D.W. Lee
|
|
STC F, 44/1/1995, P.255
|
|
Keywords: Deep Drawing, Finite Element Method, Ironing |
Abstract : High-quality cups of deep drawing ratio of more than four cannot be
simply drawn by conventional drawing and redrawing process. In the
present study, after the first deep drawing process, subsequent
hydromechanical reverse redrawing with controlled radial pressure and
final ironing to control the thickness and outer surface appearance are
employed. In order to increase the deep drawing ratio much more than
four, the radial pressure is controlled independently of the chamber
pressure and thus an optimum forming condition can be found by varying
the radial pressure. The final ironing process ensures the fine surface
quality as well as improved deep drawing ratio without inducing any
forming defect such as slight puckering and surface waviness. The
process has been subject to finite element analysis by using the
rigid-plastic material modeling considering all the frictional
conditions induced by the hydrostatic pressure. The comparison of the
computation with the experiment has shown that the finite element
modeling can be conveniently employed for the design of the process with
reliability from the viewpoint of formability.
|
|
Reduction of the residual stresses in a deep drawn cup by modifying the draw die profile
|
|
J. Danckert (2)
|
|
STC F, 44/1/1995, P.259
|
|
Keywords: Deep Drawing, Residual Stress, FEM |
Abstract : Cylindrical deep drawing has been simulated using the FEM-code Dyna2D
and has been analysed experimentally. The FEM simulations show that the
residual stresses in the cup wall are mainly caused by the unbending of
the material when the material leaves the draw die profile. FEM
simulations show that by modifying the draw die profile in such a way
that the unbending occurs gradually instead of instantaneously as in
conventional deep drawing, a substantial reduction of the residual
stresses can be achieved. The modified draw die profile also leads to a
substantial improvement in the dimensional accuracy of the deep drawn
cup. The experimental findings are in close agreement with the results
obtained using FEM.
|
STC G |
|
Subsurface evaluation of ground ceramics
|
|
B. Zhang, T.D. Howes (2)
|
|
STC G, 44/1/1995, P.263
|
|
Keywords: Ceramics, Grinding, Damage, Diamond |
Abstract : Subsurface damage evaluations are performed using a combination of
scanning electron microscopy and damage inspection techniques on silicon
nitride, alumina, and silicon carbide ground by diamond wheels with
various grit sizes. Two forms of subsurface damage are identified,
material pulverization in the superficial layer forming a powder regime
and void generation in the subsurface layer. Both forms of damage are
assessed and characterized with respect to type of workpiece material
and grit size of grinding wheel. The penetration depth of subsurface
damage is shown to be predictable using an analytical model.
|
|
Energy partition to the workpiece for grinding of ceramics
|
|
B. Zhu, C. Guo, J.E. Sunderland, S. Malkin (1)
|
|
STC G, 44/1/1995, P.267
|
|
Keywords: Grinding, Ceramic, Temperature |
Abstract : An investigation is reported of the energy partition to the workpiece
for grinding of silicon nitride with diamond wheels The energy input to
the workpiece was obtained by measuring the temperature response in the
subsurface using a two-color infrared detector and matching the results
to analytically computed values Temperature measurements obtained with a
two-color detector should be independent of the emissivity of the
workpiece material, which is an important advantage over a single-color
detector. Measured temperature responses were in good agreement with
analytical predictions for a moving heat source with a triangular
distribution at the grinding zone. It was found that about 16 to 24%37; of
the energy is transported as heat to the workpiece for wet grinding and
59%37; for dry grinding.
|
|
Chipping in high-precision slot grinding of Mn-Zn ferrite
|
|
Y. Ohbuchi, T. Matsuo (1), M. Sakata
|
|
STC G, 44/1/1995, P.273
|
|
Keywords: Grinding, Electronic Ceramic, Micro-Fracturing |
Abstract : High-precision slot grinding was carried out on Mn-Zn ferrites to
investigate the chipping mechanism and optimum slotting condition by
measuring the chipping size at the slotted edges. The slot grinding was
performed using a high-precision slicing machine with an air spindle and
different type of 2mm wide diamond wheels. The size (width, length) of
all chippings was measured by a specially designed form tracer with a
knife edge pickup. Grinding forces were also measured. It is evident
that chipping size depends on removal per grain and some ductile
fracture modes are observed at lower removal rate ranges. Therefore,
chipping size can be reduced largely by decreasing removal per grain.
|
|
Effect of grinding parameters on surface finish of ground ceramics
|
|
J.E. Mayer (2), G.P. Fang
|
|
STC G, 44/1/1995, P.279
|
|
Keywords: Grinding, Ceramics, Surface Finish |
Abstract : Experimental research has been conducted into the effect of grinding
parameters on surface finish 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 relationships
between surface finish and the grinding parameters of grit sae, grit
depth of cut, surface scallop height, chip cross-sectional area, and
theoretical cutting edge spacing are explored. Two unique relationships
appear to exist between surface finish and chip cross-sectional area;
one below chip cross-sectional area of 0.1 pm' and another above this
value. The relationship between surface finish and theoretical cutting
edge spacing shows the best fit for all test data.
|
|
Basics of process parameter selection in grinding of advanced ceramics
|
|
G. Warnecke, U. Rosenberger / J. Milberg (1)
|
|
STC G, 44/1/1995, P.283
|
|
Keywords: Ceramic, Grinding |
Abstract : The operational properties and the performance of components consisting
of advanced ceramic materials, for example silicon carbide and silicon
nitride, are mainly influenced by processing technology and process
conditions. In grinding operations grain engagement and process
kinematics determine the resulting surface topography as well as the
degree of potential rim defects. The modelling of grain engagement and
the computation of uncut chip thickness describe suitable ranges for
process parameters resulting in minimized subsurface damages of the
ceramic part. By means of single grain diamond scratch tests the
limiting uncut chip thickness at the transition between plastic
deformation of workpiece material and the occurrence of brittle
microchippings during chip removal is evaluated. Based on theoretical
models and experimental investigations a contribution to practical
applications in grinding of advanced ceramics is explained.
|
|
Analysis of mirror surface generation of hard and brittle materials by ELID (Electrolytic In-Process Dressing) - Grinding with superfine grain metallic bond wheels
|
|
H. Ohmori, T. Nakagawa (1)
|
|
STC G, 44/1/1995, P.287
|
|
Keywords: Damage, Dressing, Grinding, Removal Mechanism |
Abstract : Mirror surface grinding operators were conducted by using ultrafine
grain metallic bond wheels with electrolytic in-process dressing (ELID)
Workpieces of hard and brittle materials, such as monocrystalline
silicon, glass, and ceramic, were ground. Wheel abrasive grains used
mainly were diamond of several microns down to sub-microns Ground
surface roughness versus grit size was shown. SEM and AFM were adapted
to analyze ground mirror surface generation, and surface topographies
due to grit size were compared. Subsurface damage was evaluated through
X-ray, angle-polish and step-etching. High surface accuracy, good
surface finish, and low subsurface damage were all successfully
achieved. The advantage of a constant in-feed pressure in ultrafine
grinding was shown, and Ra of several angstroms was achieved.
|
|
Porous fine CBN stones for high removal rate superfinishing
|
|
Y. Onchi, N. Ikawa (1), S. Shimada (2), N. Matsumori
|
|
STC G, 44/1/1995, P.291
|
|
Keywords: Superfinishing, Cubic Boron Nitride, Porosity |
Abstract : For obtaining better finish comparative to that by But aluminum oxide
stones, recommendation is made for the use of finer CBN stone. In order
to prevent possible loading on the working surface of fine CBN stones, a
porous structure is proposed The porous stone is composed of fine CBN
grain and vitrified bond in which art dispersed intrinsic residual pores
and extra pores the diameters of which are one to an order of magnitude
as large as grain size for easier chip flow. By the use of appropriate
stones under proper cutting condition, fine superfinishing with higher
stock removal rate and much longer tool life are achieved than that by
conventional aluminum oxide stones.
|
|
Investigation of surface integrity by molecular dynamics simulation
|
|
R. Rentsch, I. Inasaki (1)
|
|
STC G, 44/1/1995, P.295
|
|
Keywords: Abrasion, Surface, Simulation |
Abstract : Difficulties in measurements at the abrasive/work contact when machining
materials, as well as in determining the integrity of machined surfaces,
have led to an increased attention in Molecular Dynamics (MD) simulation
as it can provide a more detailed insight in the process and the
machined surface. By means of MD simulation, the possibility ho
investigate the influence of abrasive processes on the integrity of
machined surfaces will be discussed. The surface integrity will be
described in terms of dislocation building, surface roughness, residual
stresses, and crack initiation in particular. For the first time, it was
possible to simulate crack initiation in indention on brittle materials.
|
|
Characterization of dressing processes by determination of the collision number of the abrasive grits
|
|
E. Brinksmeier (2), M. Cinar
|
|
STC G, 44/1/1995, P.299
|
|
Keywords: Dressing, Grinding, Cubic Boron Nitride (CBN) |
Abstract : A mathematical model is developed to determine his collision number
between the diamond grits of a rotating dresser and his grits of a CBN
grinding wheel. This model considers the kinematical influences of the
dressing process and the specifications of both tools. A collision
number i_d is defined which takes into account the specifications of the
CBN wheel and the diamond dressing tool and also the overlap factor U_d
and the speed ratio q_d during dressing. Comparisons between theoretical
calculations and practical investigators show that the active surface
topography of the grinding wheel after dressing strongly depends on his
collision number i_d.
|
|
Appropriate conditioning strategies increase the performance capabilities of vitrified-bond CBN grinding wheels
|
|
F. Klocke, W. König (1)
|
|
STC G, 44/1/1995, P.305
|
|
Keywords: Cubic Boron Nitride (CBN), Dressing, Grinding |
Abstract : A considerable improvement in the performance of grinding wheels can be
achieved by means of ultra-hard abrasive materials, such as cubic boron
nitride (CBN) A growing range of applications can be noted in particular
for vitrified-bonded CBN grinding wheels An essential criterion for an
efficient CBN grinding process is suitable conditioning of the grinding
wheel. Investigations were carried out into various truing and dressing
proves providing a broad range of variation for the preparation of
vitrified-bonded grinding wheels. On the basis of there investigators,
strategies and parameters for conditioning operations are discussed win
the aim of establishing appropriate process contemptuous.
|
|
CBN grinding with small wheels
|
|
H.K. Tönshoff (1), H.G. Wobker, G. Brunner
|
|
STC G, 44/1/1995, P.311
|
|
Keywords: Cubic Boron Nitride (CBN), Residual Stresses, Temperatures |
Abstract : Vitrified bonded CBN wheels have proved their benefits in industry
mainly in internal grinding processes The present paper describes a
strategy for an economical application of CBN in external grinding, with
an adapted CBN technology employing small wheel diameters to reduce the
initial costs. Compared to conventional grinding with an adapted CBN
grinding strategy tool life, productivity, workpiece roughness and
residual stress state of the workpiece can be improved significantly.
However, even with CBN thermal damage of the workpiece surface can
occur. In order to avoid thermal damage of the workpieces and to exploit
the potential of CBN a temperature model to predict residual stresses of
the workpiece surface based on the grinding parameters is developed.
|
|
Grinding assisted by Nd : YAG lasers
|
|
E. Westkämper (2)
|
|
STC G, 44/1/1995, P.317
|
|
Keywords: Grinding, Conditioning, Laser |
Abstract : High-performance lasers can be actively used to assist grinding and
conditioning (truing, dressing and cleaning) processes, and for an
integrated heat treatment. The advantages of laser-assisted conditioning
are the force-bee working principle and no necessity of expensive
conditioning tools. In laser-assisted grinding, the workpiece area is
heated directly before the grinding wheel is engaging, thus reducing the
temperature gradient as well as surface layer damage. Moreover, the
method permits high stock removal rates. This paper deals with the
fundamentals of this method and presents a number of results from laser
assisted conditioning of resin-bonded CBN grinding wheels as well as
from laser-assisted machining of metal and ceramic components.
|
|
Model of gear grinding process
|
|
B.W. Kruszynski / L. Nawara (1)
|
|
STC G, 44/1/1995, P.321
|
|
Keywords: Grinding, Gear, Thermal |
Abstract : The mathematical model of a generating gear grinding process is
presented in the paper Detailed analysis of the creation of the tooth
profile resulted in evaluation of the shape of a material layer being
removed in a particular generating stroke of a grinding wheel and
consequently in calculation of grinding forces, power density
distribution on a wheel/workpiece interface and in calculation of
temperature distribution in gear tooth during grinding This in turn may
be utilised to predict such surface integrity parameters as residual
stress, micro-hardness distribution, burns or cracks.
Some experimental results, which confirm the model, are also presented
in the paper.
|
|
Thermal behaviour of cutting grain in grinding
|
|
T. Ueda, M. Sato, T. Sugita, K. Nakayama (1)
|
|
STC G, 44/1/1995, P.325
|
|
Keywords: Grinding, Temperatures, Measurements |
Abstract : Temperature at the interface between the cutting grain and a workpiece
is measured using a two-color pyrometer with a fused fiber coupler. For
the cutting grain, a conical tool of translucent alumina is used. The
infrared rays radiated from the interface and transmitted through the
conical tool are accepted by a fused fiber coupler and led to two
infrared detectors of different spectral sensitivity. The temperature
increases rapidly and reaches a saturated value after a short time
(about 0.1 ms). The saturated temperature measured increases with the
increase in the cutting speed up to the melting point of the work material.
|
|
Experimental investigation of heat transfer in grinding
|
|
W.B. Rowe (1), S.C.E. Black, B. Mills, H.S. Qi, M.N. Morgan
|
|
STC G, 44/1/1995, P.329
|
|
Keywords: Grinding, Temperature, Damage |
Abstract : New findings are presented for temperatures, heat flux distribution and
the implications for workpiece damage and partition ratio. Workpiece
temperatures were measured using a 25 mm single pole thermocouple
assembly. It was found that the critical temperature for the onset of
temper colours for ferrous materials lies within the range 450 to 500
deg. C. Measured temperature distributions in the contact zone compared
best with theory assuming a square law heat flux. The effective contact
length for vitrified CBN and alumina wheels was confirmed to be greater
than the geometric value. Substantially lower partition ratios were
found with CBN compared to alumina.
|
|
Grinding fluid application system design
|
|
J.A. Webster, C.L. Cui, R.B. Mindek / R.P. Lindsay (1)
|
|
STC G, 44/1/1995, P.333
|
|
Keywords: Grinding, Fluid, Design |
Abstract : Coolant application in grinding processes is becoming more important as
stock removal rates are increased and higher quality is demanded. This
study has analyzed the limitations of current application systems and
used fluid mechanics to develop flow conditioners to compensate for
bends in pipes. New nozzle designs are presented that give long coherent
jets, up to 45 m/s, maximizing the application of fluid into the
grinding zone. The influence of nozzle position, jet velocity, and
distance from the grinding zone is presented. A 26.596 increase in wheel
life as a result of coolant application optimization during grinding of
an aerospace component is reported.
|
|
Semi-ductile grinding and polishing of ophtalmic aspherics and spherics
|
|
Z. Zhong, V.C. Venkatesh (1)
|
|
STC G, 44/1/1995, P.339
|
|
Keywords: Ductile-Grinding, Polishing, Brittle Materials |
Abstract : Ductile grinding yields surfaces whose precision is far beyond that
expected of ophthalmic requirements. This process requires machine tools
and cutting tools that are manufactured to sub micron tolerances and
which require clean rooms, thus making its cost prohibitive. While
fracture mode grinding, followed by lapping and polishing have been
successful, this paper presents results of semi-ductile grinding that is
followed by reduced polishing time without an intervening lapping
operation. Using conventional CNC machining centres and/or dedicated
machines, silicon, germanium and glass were ground by metal bonded
and/or diamond bonded diamond wheels followed by conventional polishing
techniques.
|
|
Precision finishing
|
|
M.C. Shaw (1)
|
|
STC G, 44/1/1995, P.343
|
|
Keywords: Grinding, Cutting, Nanotechnology |
Abstract : The ultraprecision diamond grinding (UPDG) of hard brittle materials
such as glass involves two important characteristics: unusually high
values of effective negative rake angle and high ratios of radial to
tangential components of mean force per grit. Reasons are given why the
mean normal force per grit is a useful criterion relative to subsurface
damage. Also discussed is why the term ductile machining for the related
process - single point diamond turning (SPDT) is misleading.
|
STC M |
|
Kinematics, frictional characteristics and wear reduction by PVD coating on ball screw drives
|
|
D. Spath, J. Rosum, A. Haberkern / H. Weule (1)
|
|
STC M, 44/1/1995, P.349
|
|
Keywords: Coating, Kinematic, Tribology |
Abstract : As the kinematic knowledge gained from roller bearings cannot be applied
to the ball screw drive, a separate description of the velocities in the
pitch points is required. This makes it possible to indicate the
friction components (rolling, bore and sliding friction) and the
resulting wear mechanisms. The specific measures for wear reduction are
derived from these. It is experimentally proven how PAD coatings
optimized in accordance with this approach improve the frictional and
wearing characteristic. The use of PAD coated ball screw drives allows
reduction of idle times in machine tools by increasing the rapid
traverse speeds.
|
|
Effect of low friction guideways and leadscrew flexibility on dynamics of high speed feed machines
|
|
Y.C. Chen, J. Tlusty (1)
|
|
STC M, 44/1/1995, P.353
|
|
Keywords: Path Errors, Feedforward Control |
Abstract : Rolling type as well as hydrostatic guideways generate very little
damping in the direction of the feed motion. The ballscrew/nut
flexibility driving a mass of a table, as a spring-mass system attached
to the servodrive spoils both the transient response to the NC command
and the response of the driven mass to the cutting force. The
improvements obtainable by various measures including feedforward,
accelerometric feedback and tuned damper are discussed.
|
|
Analytical prediction of stability lobes in milling
|
|
Y. Altintas (2), E. Budak
|
|
STC M, 44/1/1995, P.357
|
|
Keywords: Chatter, Stability, Milling |
Abstract : A new method for the analytical prediction of stability lobes in milling
is presented. The stability model requires transfer functions of the
structure at the cutter - workpiece contact zone, static cutting force
coefficients, radial immersion and the number of teeth on the cutter.
Time varying dynamic cutting force coefficients are approximated by
their Fourier series components, and the chatter free axial depth of
cuts and spindle speeds are calculated directly from the proposed set of
linear analytic expressions without any digital iteration. Analytically
predicted stability lobes are compared with the lobes generated by time
domain and other numerical methods available in the literature.
|
|
A fuzzy variable structure adaptive control design for robot manipulators
|
|
D.B. Zhao, J.Y. Zhu (1)
|
|
STC M, 44/1/1995, P.363
|
|
Keywords: Robotic Manipulators, Fuzzy Logic, Optimization |
Abstract : The increasing demand on robotic system performance leads to the use of
advanced control strategies. This paper proposes a method of nonlinear
feedback control introducing fuzzy inference into variable structure
adaptive control for the nonlinear robot manipulator systems. The fuzzy
inference is introduced to treat the nonlinearities of the control
systems. The fuzzy logic control approach enhances the proposed variable
structure adaptive control since it gives robust property against system
uncertainties and external disturbances, and also expert's experience
can be added into the controller in parallel. The controller is an
intelligent one. An automated design technique to numerically optimize
membership functions for the fuzzy controller is discussed. In addition,
the method is capable of handling the chattering problem inherent to
variable structure control simply and effectively. A simulation study of
a robot manipulator with three degrees of freedom is presented to
demonstrate these features of the method.
|
|
Development of ultra-precision machining center with close-loop structure and its control
|
|
K. Sawada, Y. Takeuchi (2), T. Sata (1)
|
|
STC M, 44/1/1995, P.369
|
|
Keywords: Ultra-Precision, Milling Machine, Stiffness |
Abstract : A high stiffness is required to reduce the relative displacement between
workpiece and cutting tool due to the cutting force even for
ultra-precision machine tools. Thus, a lathe-type ultra-precision
milling machine was designed with a pseudo ball endmill as a cutting
tool. The study deals with the further improvement of stiffness by
upgrading the milling machine to that with a closed-loop structure.
Thus, two constraint axes are employed to form the closed-loop
structure, and are able to move in cooperation with X and Z-axis
movements. The effect of the closed-loop structure is confirmed
experimentally as well as with FEM analysis.
|
|
A strategy for the compensation of errors in five-axis machining
|
|
S.C. Veldhuis, M.A. Elbestawi (1)
|
|
STC M, 44/1/1995, P.373
|
|
Keywords: Machining, Thermal, Compensation |
Abstract : This paper outlines a strategy for error compensation in five-axis
machining. The strategy uses a neural network model for compensation of
errors due to changes in temperature and axis motion. Long term errors
due to wear will be addressed with an adaptive approach. A method based
on the analysis of the neural network weights is used for selecting the
most relevant thermocouple inputs. Preliminary results show the strategy
to be capable of holding the error to within 0.020 mm in the Z direction
and 0.002° in the q_x direction. Similar results are obtained during a
cutting test.
|
|
Five-axis surface interpolators
|
|
Y. Koren (1), R.S. Lin
|
|
STC M, 44/1/1995, P.379
|
|
Keywords: Numerical Control, Interpolator, Machine Tools |
Abstract : A new interpolator architecture for surface machining on five-axis CNC
machines was developed and tested This interpolator can handle quid: and
precise production of both convex surfaces by using endmills and ruled
surfaces by using flank-mills The main ideas are (1) Decomposing the
surface into curves, (2) continuously maintaining the cutter axis
perpendicular to convex surfaces (end mills) or parallel to ruled
surfaces (flank mills) by calculating corresponding axial reference
positions at each sampling period of his interpolator This real-time
approach produces smoother surfaces and requires substantially less
machining time compared to conventional off-line approaches.
|
|
Toolholder spindle interfaces for CNC machine tools
|
|
J. Agapiou, E. Rivin (1), C. Xie
|
|
STC M, 44/1/1995, P.383
|
|
Keywords: High-Speed Machining, Interfaces, Tools |
Abstract : The paper describes designs and tests of two novel tool holder/spin die
interfaces. Interface WSU-1 provides improved axial and radial accuracy,
higher stiffness, insensitivity to high rpm, and the potential for being
used without keys, while being compatible with standard 7/24 spindles
and toolholders. lnterface WSU-2 is an inexpensive modification of the
standard 7/24 interface with improved axial accuracy and stiffness
characteristics. Cutting tests have confirmed the advantages of these
interfaces.
|
|
OPERA - A new approach to robot programming
|
|
M. Weck (1), R. Dammertz
|
|
STC M, 44/1/1995, P.389
|
|
Keywords: Manufacturing, Robotic, Programming |
Abstract : This paper presents a new, graphical approach to the definition of
complex robot program structures, based on a task description by means
of flowcharts. Thus the PC-based OPERA system relieves the user as far
as possible from learning a programming language and simplifies a better
structuring of robot programs. Parameters for statements and procedure
calls are defined within dialog boxes. As the program code is generated
automatically, different robot languages are no problem for the user.
Based on this approach OPERA offers various functions to add user
defined procedure libraries as well as new robot control statements. New
functions can be integrated like standard statements. They are
graphically represented by user defined icons and even new dialog boxes
can be included. Features for debugging and the generation of
application specific user interfaces complete OPERA to a structure
oriented programming tool, addressing the needs of end users as well as
those of application specialists.
|
|
Intelligent integrated diagnostics : development of the diagnostics system for on-line quality control of powder injection molding
|
|
S.R.T. Kumara (2), J.W. Lee
|
|
STC M, 44/1/1995, P.393
|
|
Keywords: Powder Injection Molding, Fault Diagnosis, Causality Network |
Abstract : In this research the authors propose an integrated intelligent
diagnostics scheme for the on-line quality control of the Powder
Injection Molding (PIM) process. In specific, this paper concentrates on
the computational methodologies related to the process diagnostics A
causality network model and its underlying mathematics to represent the
domain and case specific diagnostic knowledge of PIM process are
discussed. Alternatives of hypothetical explanations to the product
defects am generated by network conversion technique and abductive
reasoning. Diagnostic solutions ere generated by applying verification
criteria for the hypotheses. The effectiveness of the proposed
methodologies are verified by testing real-life problems.
|
STC O |
|
A modelling and simulation architecture or virtual manufacturing systems
|
|
K. Iwata (1), M. Onosato, K. Teramoto, S. Osaki
|
|
STC O, 44/1/1995, P.399
|
|
Keywords: Manufacturing, Modelling, Simulation |
Abstract : Virtual manufacturing systems are integrated computer models that
represent the precise and whole structure of manufacturing systems and
simulate their physical and logical behavior in operation Since each
virtual manufacturing system is an aggregation of various computer
hardware and software, it is necessary to develop a system architecture
which defines functional components required for modelling and
simulation, interfaces between components, virtual-real interactions,
and system infrastructure This paper deals with a modelling and
simulation architecture for virtual manufacturing systems for the
practical development and describes a method of modelling and simulation
for distributed simulation of virtual manufacturing systems.
|
|
A methodology for an integrated design and process planning based on a concurrent engineering reference model
|
|
W. Eversheim (1), H. Ozengeld, W. Bochtler, R. Graessler
|
|
STC O, 44/1/1995, P.403
|
|
Keywords: Concurrent, Engineering, Methodology |
Abstract : Based on Concurrent Engineering approaches a reference model and a
methodology have been developed which support the integration of design
and process planning The reference model consists of four partial models
These are the activity model, the information model, the object model as
well as the model of integration methods. Using activity, information
and object model, the methodology enables a concurrent processing of
design and process planning activities considering different objects of
a product. Furthermore, the methodology supple an early transmission of
information to following activities and a feedback of information to
previous activities within the process chain of design and process
planning making use of the model of integration methods.
|
|
Order control by a hierarchical, self-organizing computer system
|
|
H. Bley, J. Jostock, K. Rech / K.G. Günther (1)
|
|
STC O, 44/1/1995, P.407
|
|
Keywords: Production, Logistics, Scheduling, CAPP |
Abstract : Job processing on the typical shop floor is normally influenced by
technical or organizational dependent disturbances. Due to growing
efforts to meet the customers' demands with respect to short notice
changes to orders (product variants and delivery dates), MRP-systems and
subordinate shop floor control systems such as scheduling systems have
to deal with these disturbances. This forms the basis for a new approach
to order control systems implementing cascaded control loops starting
with customers' orders and regarding the aspects of real-time
rescheduling, process plan alternatives as well as simulating the
impacts on future machining and delivery shop order sequences. Reactions
to disturbances are offered by a knowledge-based module. This paper
describes a concept to help solve the problems encountered by the
subcontractor. This concept is based upon a hierarchically organized
distributed computer network enabled to reorganize itself in case of a
computer or interface failure.
|
|
An evaluation system of order acceptability under consideration of machine loading in die manufacturing
|
|
M.S. Lee, H.M. Rho (2), M.J. Kang
|
|
STC O, 44/1/1995, P.413
|
|
Keywords: Die, Order Evaluation, Machine Loading |
Abstract : In die manufacturing factories, orders are often accepted without
reasonable evaluation. This incurs difficulties to generate an
appropriate production schedule. By exploring some characteristics of
die manufacturing, this paper proposes heuristic method for quick order
acceptance evaluation which considers of both real and potential loads
at the order evaluation phase. This method is implemented into a quick
order evaluation system as a part of the integrated production
management system, and can perform the order evaluation quickly by
comparing all the standard operation times for main parts of a die set
with available capacity of machines.
|
|
Machining economics in FMS by a fuzzy approach
|
|
S. Noto la Diega (2), A. Passannanti, G. Perrone
|
|
STC O, 44/1/1995, P.417
|
|
Keywords: Cost Analysis, FMS, Fuzzy Optimization |
Abstract : In a conventional manufacturing system, cutting parameters have to be
fixed in order to pursue the economical and productive target related to
each cutting operation. In a Flexible Manufacturing System (FMS), as a
consequence of the unbalanced workload due to the mutual interaction
among the shared resources, the optimization of each operation does not
allow the optimum of the global production system to be reached. A fuzzy
programming model is developed in this paper in order to select cutting
speeds of the operations in the production plan as a satisfying
compromise solution between single operation and the integrated system
targets.
|
|
Application of control theory for production logistics - Results of a joint project
|
|
G. Pritschow (1), H.P. Wiendahl (1)
|
|
STC O, 44/1/1995, P.421
|
|
Keywords: Production Logistics, Control, Modelling |
Abstract : The area of production logistics has become a key issue for the success
of a company in increasingly dynamic and competitive markets. For a
better reaction to short term market changes and disturbances of the
production process a transition from a static to a dynamic view, from an
open to a closed-loop controlled system is necessary. Control theory
based models have been developed allowing the prediction of control
parameters and the logistic behaviour of closed control loops in quality
and quantity. Studies of the dynamic properties of closed control loops
reveal potentials for a better compliance with the logistic objectives.
|
|
Modelling and analysis of non-linear dynamics in autonomous heterarchical manufacturing systems control
|
|
V.V. Prabhu, N.A. Duffie (2)
|
|
STC O, 44/1/1995, P.425
|
|
Keywords: Manufacturing, System, Control |
Abstract : Heterarchical architectures characterized by fully distributed control
and cooperation among loosely-coupled autonomous entities have been
proposed for controlling automated manufacturing systems. A non-linear,
control-theoretic analytical model is developed in this paper to
represent the dynamical behavior of closed-loop distributed controllers
in autonomous part-driven heterarchical systems The model and the
control law introduced for adjusting arrival times of parts to be
processed allows the dynamics of these highly distributed, highly
non-linear control systems to be analyzed Analytical and numerical
results are used to validated the model and illustrate robustness to
uncertainties such as new part arrivals and machine failures of the
fully distributed, heterarchical system control.
|
|
The integration of process planning and shop floor scheduling in small batch part manufacturing
|
|
W.H.M. Zijm / H.J.J. Kals (1)
|
|
STC O, 44/1/1995, P.429
|
|
Keywords: Scheduling, Process Planning, Critical Path Method |
Abstract : In this paper we explore possibilities to cut manufacturing leadtimes
and to improve delivery performance in a small batch part manufacturing
shop by integrating prowls planning and shop floor scheduling Using a
set of initial process plans (one for each order in the shop), we
exploit a resource decomposition procedure to determine schedules to
determine schedules which minimize the maximum lateness, given these
process plans. If the resulting schedule is still unsatisfactory, a
critical path analysis is performed to select jobs as candidates for
alternative process plans. In this way, an excellent due date
performance can be achieved, with a minimum of process planning and
scheduling effort.
|
|
Multi objective process planning in environmentallyconscious manufacturing : a feature based approach
|
|
P. Sheng, M. Srinivasan / S. Kobayashi (1)
|
|
STC O, 44/1/1995, P.433
|
|
Keywords: Machining, Environment |
Abstract : Environmental factors have become important in manufacturing planning
due to governmental regulations and a growing preference for "green"
products. However, planning decisions must also consider traditional
dimensions such as production rate and quality. Major issues for
environmentally-conscious planning are (1) comparative assessment of
waste stream and (2) computational complexity of evaluating multiple
processing alternatives. Environmental impact of dissimilar waste
streams is analyzed through a scoring system which evaluates factors
such as toxicity, carcenogenesis, irritation, flammability, and
reactivity. Complexity of processing alternatives is reduced through a
feature-based approach, where the component environmental impact is
decomposed into "micro" analysis of individual features and "macro"
analysis of feature interactions.
|
|
Autonomous process planning with real-time machining forproductive sculptured surface manufacturing based on automatic recognition of geometric features
|
|
K. Yamazaki (2), Y. Kawahara, J.C. Jeng, H. Aoyama
|
|
STC O, 44/1/1995, P.439
|
|
Keywords: Sculpture Surface Manufacturing, Process Planning |
Abstract : The paper deals with a study on technologies to enhance the
manufacturing productivity of a product consisting of sculptured
surfaces. A process planning system coupled with real time machining is
proposed such that the productive machining plan and tool motion can
automatically be generated once available resources and machining
know-how are given for the metal cutting-EDM mixed environment. The
system proposed consists of geometry feature recognition, cutting mode
and tool selection, real time tool path generation with adaptive
feedrate generation using concurrent real time machining simulation. The
system was prototyped to verify the feasibility. Successful results were
obtained.
|
|
Determination of the optimum tool set for a given batch of turned components
|
|
J.H. Zhang, S. Hinduja (2)
|
|
STC O, 44/1/1995, P.445
|
|
Keywords: Optimum, Tool, Batch, Balancing |
Abstract : This paper describes a procedure to determine the optimum tool set for a
batch of turned components, the optimisation criterion being either the
minimum machining cost or minimum number of machine stoppages or a
combination of both. A too-operation-cost table is constructed wherein
the costs of machining an operation with individual tools are stored and
the optimum tool set is obtained by searching this table exhaustively
The wear rate of each tool is adjusted so that it machines an integral
number of components, to reduce the machine stoppages, tool wear rates
of the leading and shadowing tools are further adjusted so that tool
changes are synchronised The factors considered in the optimisation
include the number of turret positions, batch size and performance of
individual and sister tools. To demonstrate the system, tool sets have
been determined for a turned component for different optimisation criteria.
|
|
Future direct manufacturing of metal parts with free form fabrication
|
|
L.A. Killander, G. Sohlenius (1)
|
|
STC O, 44/1/1995, P.451
|
|
Keywords: Laser Sintering, Free Form Fabrication, TIPS |
Abstract : In this paper manufacturing of metal parts with Free Foam Fabrication
FFF is discussed. Thoughts and ideas has been inspired by the Theory of
Inventive Problem Solving TIPS. Principles and effects based on work by
Altshuller has been combined with knowledge on FFF. The time frame has
been limited to what is likely to be achieved within the next two years
Some promising ideas are the introduction of vibration and the use of
multi phase materials.
|
STC P |
|
Atomic-scale precision motion control stage (The Angstrom stage)
|
|
M. Holmes, D. Trumper, R. Hocken (1)
|
|
STC P, 44/1/1995, P.455
|
|
Keywords: Precision Motion Control |
Abstract : This paper describes a magnetically-suspended six-degree-of-freedom
precision motion control stage with sub-nanometer positioning stability
inside a 100 mm cube of travel. This stage utilizes multiple
electromagnetic actuators and capacitance probes to provide control
forces and position feedback respectively. The suspended platen (3 kg
mass) is floated in oil to enhance the performance of the magnetic
bearings. The stage has been designed for use as a sample positioning
stage for scanning-tunneling microscopy. We present images obtained by
scanning-tunneling microscopy which show that the positioning noise of
the stage is below 0.2 nm peak-to-peak over 5 seconds. These data
demonstrate the utility of this stage as a new concept for precision
motion control.
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A 3D probe for measuring small blind holes
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G.X. Zhang (1), S.M. Yang
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STC P, 44/1/1995, P.461
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Keywords: Measurements, Probe, Compensation |
Abstract : A 3-D probe for measuring the diameter and form errors at any particular
section for small blind holes or slots with diameter or width down to
0.2 mm and depth to diameter ratio up to 20 was developed. Since optical
methods are difficult to use for measuring the diameter of blind hole at
any cross section, a method with mechanical stylus was used. The stylus
is treated as an elastic element and a theory of elastic transmission
was developed. The stylus can be introduced to small holes automatically
and the deflection of the measuring stylus is compensated. Experiments
show that the accuracy is better than l mm.
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Development of high-speed and high-accuracy straightness measurement of a granite base of a CMM
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Y. Tani, K. Katsuki, H. Sato (1), Y. Kamimura
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STC P, 44/1/1995, P.465
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Keywords: CMM, Optical Measurement, Straightness |
Abstract : The flatness of a granite base affects the volumetric accuracy of a
probe in a CMM. Therefore a new optical straightness measurement with
high speed and high accuracy is proposed in thus paper. High speed was
attained by gliding the measurement head over the granite surface
through the action of an aerostatic bearing pad. High accuracy was
obtained by measuring the position of a laser beam on photodetectors.
The straightness was estimated in terms of the vertical displacement and
the integrated inclination of the slider, and the latter coincided well
with the value measured using an electric level.
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Assessment of dynamic errors of CMMs for fast probing
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W.G. Weekers, P.H.J. Schellekens (2)
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STC P, 44/1/1995, P.469
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Keywords: CMMs, Dynamic, Error |
Abstract : Due to the demand for shorter cycle times of measurement tasks, fast
probing at CMMs becomes more important and the influence of dynamic
errors of CMMs will increase. This paper presents an assessment of
dynamic errors due to carriage motion. Based on the analysis of the
dynamic errors of a specific CMM a practical approach was chosen. In
this approach the major joint defections due to accelerations are
measured with position sensors. Possibilities for estimating other joint
defections by analytical modelling of CMM components are discussed.
Using a kinematic model of a CMM, the influences of the measured and
estimated joint defections on the probe position are calculated. A
description of a measurement setup for one axis of a CMM is given to
illustrate the approach. The results show that measurement and
estimation for at least pad of the dynamic errors is possible.
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Effects of arbitrary coefficients of CMM error maps on probe qualification
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A. Balsamo (2)
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STC P, 44/1/1995, P.475
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Keywords: CMM, Multi-Stylus |
Abstract : For a consistent definition of the geometrical error functions of a CMM
some of their low-order parameters must be set arbitrarily. When a
multiple stylus configuration is not used for the measurement of the
error parameters, the available information is not complete and
compensation errors may be generated by a subsequent use of multiple
styli. However, these errors can be avoided by taking some precautions
in the probe qualification. The theoretical as well as experimental
importance of this is pointed out, and the consequences in the probe
qualification and in the simulation of CMMs (virtual CMMs) are discussed.
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Results of international comparison of ball plate measurements in CIRP and WECC
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H. Kunzmann (1), E. Trapet, F. Wäldele
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STC P, 44/1/1995, P.479
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Keywords: Coordinate Measuring Machines (CMM), Calibration, Inspection |
Abstract : A comparison was conducted for the calibration of commercially available
ball plates. Twenty six metrology laboratories from fifteen countries
participated with a total of thirty eight individual measurements. The
method of measurement was strictly prescribed and the results were
evaluated by the PTB as the reference laboratory in comparison to the
reference values. The measurements showed a high degree of conformity of
about 2*10^-6 in over 60%37; of all cases. In 30%37; evident problems which
can easily be overcome were the reasons for less good results. The ball
plates showed sufficient dimensional stability overtime of about l*10^-6
per year (m the worst case) Findings resulting from the
inter-comparison suggest ways to improve the stability of ball plates by
better design details.
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On-line failure detection in face milling using discrete wavelet transform
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N. Kasashima, K. Mori, G. Herrera Ruiz / N. Taniguchi (1)
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STC P, 44/1/1995, P.483
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Keywords: Monitoring, Milling, Diagnostic Routine |
Abstract : This paper describes an application of the Discrete Wavelet Transform
(DWT) to detecting tool failures in face milling operations. The wavelet
transform uses an analyzing wavelet function which is localized in both
frequency and time to detect subtle time localized small changes in the
input signals. In this paper, the DWT is used to detect tool failures
such as small chipping and breakage of an insert tip including
eccentricity of the tool rotation center. The results indicate that the
DWT can extract tool failures with much greater sensitivity than the FIT
even when the amount of chipping is very small. In addition, the DWT
enables the analyst to determine which insert tip failed, since it
yields time localized signal information. On-line diagnosis of tool
failures are demonstrated in both simulated and actual cutting force
signals by using simple pattern recognition technique.
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Nanometer measurement of silicon wafer srface texture based on Fraunhofer diffraction pattern
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T. Miyoshi, Y. Takaya, K. Saito (2)
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STC P, 44/1/1995, P.489
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Keywords: Surface Texture, Ultra-Precision, Optical Measurement |
Abstract : A new optical measuring method which can be applied to in-process
measurement of surface defects as well as microroughness of ultra-fine
finished surfaces with an accuracy of nanometer order is presented in
this paper. The principle of our method is based on the Fraunhofer
diffraction theory taking account of Gaussian laser beam propagation.
The feasibility of the proposed optical method is verified by
measurements of the ultra-fine polished silicon wafer surfaces.
Consequently, the Fraunhofer diffraction method makes it possible to not
only measure microroughness of less than 1 nm Rrms, but also detect
distinctively micro-scratches, pinholes and particles.
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Generalized aspects of multiple-wave length techniques in optical metrology
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T. Pfeifer (2), R. Tutsch, J. Evertz, G. Weres
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STC P, 44/1/1995, P.493
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Keywords: Metrology, Optical Measuring Instruments, Dimensional Measurement |
Abstract : Various optical measurement techniques are based on mathematical
equations that have a common formal structure. A characteristic feature
of a so-called fundamental interferometric equation of this nature is
the limitation imposed on the unambiguous measurement range by the
periodicity of the trigonometric functions. Back at the end of the 19th
century, Michelson developed the concept of multiple-wavelength
interferometry in an effort to overcome this problem. Nowadays, the
availability of powerful microcomputers permits generalized multiple
wavelength techniques to be used in a wide variety of fields of
application including optical shop testing, fringe projection
profilometry and TV holography. The basic concept and new developments
are discussed in this paper, giving examples of current applications.
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The shadow Moiré method applied to 3D model copying
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A. Del Taglia, A. Paolucci / M. Santochi (1)
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STC P, 44/1/1995, P.497
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Keywords: Dimensional Measurement, Image Processing, Moiré Pattern |
Abstract : The paper-deals with the problem of testing, measuring, or copying JD
shapes from a physical object using a digital elaboration based on a
telecamera image. Utilising the shadow moire method, light and dark
interference fringes are created on the image of the object end each
fringe relates to a well defined depth; this information, together with
the image plane measurement, fan be used to obtain a complete 3D shape
model reconstruction
Descriptions of the principal problems encountered and the solutions
adopted are discussed. Problems include a need to improve poor
resolution and precision resulting from off-the-shell instrumentation,
as well as difficulties related to the automatic hinge analyses and to
the creation of a mathematical model to be imported in a CAD system
However, considering that only commercially available and low cost
instrumentation has been used, the method, though not feasible for all
applications, produces a satisfactory overall performance
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Metrological limitations of optical probing techniques for dimensional measurements
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L. De Chiffre (2), H.N. Hansen
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STC P, 44/1/1995, P.501
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Keywords: Dimensional Metrology, Optical Probe, Accuracy |
Abstract : Based on experimental results from a series of investigations, this
paper deals with the metrological limitations of optical probing
techniques in the field of dimensional metrology. The optical probing
systems considered herein comprise an optical coordinate measuring
machine, an experimental optical roundness tester and an optical
measuring station for dimensions which is under development for
integration in a production line. In all these cases, a single
measurement micrometer accuracy is required but hard to achieve. The
influences from sensor, optical system, illumination, object,
background, and mechanical system, are evaluated. Guidelines are
suggested which can be used to optimize the accuracy in measuring
situations.
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STC S |
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Application of the filter with dynamically controlled transmission band in surface texture analysis
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T. Klimczak (2), Z. Handzel-Powierza
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STC S, 44/1/1995, P.505
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Keywords: Surface, Roughness, Filter |
Abstract : In some issues of engineering surfaces characterization it is necessary
to separate topographical features of surface. If we are dealing with
multi-scale features of surface topography conventional surface
filtering techniques are limited. The paper presents method of
controlling of filter transmission band over the data space. The method
used originally in image processing was adopted for identification and
localization of topographical features on engineering surfaces. This
method of filtering allows for proper separation of features of
different scales which, for its different functional meaning, should be
analyzed separately. The method applied to three-dimensional
topographical data demonstrates its usefulness in preparing data for
pattern analysis of surface features such as grooves, contact spots,
lay, defects etc.
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Analysis of machined surfaces through diffraction patterns and neural networks
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P.M. Lonardo (1), A.A. Bruzzone, A.M. Lonardo
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STC S, 44/1/1995, P.509
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Keywords: Surface, Diffraction, Neural Network |
Abstract : The analysis of diffraction patterns obtained from machined surfaces can
be used to characterise the microgeometry and, consequently, the
production process. Unfortunately, the analysis applied to real surfaces
is rather complex. In this paper a new approach based on the technique
of the neural networks is proposed to recognise turned surfaces.
The diffraction images are acquired and the distributions of the light
intensity are used as inputs to the networks. The ability of supervised
networks of classifying the surfaces according to the received training
is assessed
With unsupervised networks a classification of the surfaces in quality
levels is performed.
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Assessment of subsurface damage in ultraprecision machined CdS by ion channeling
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D.A. Lucca, R.L. Rhorer,C. Maggiore, Y.W. Seo / R.R. Donaldson (1)
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STC S, 44/1/1995, P.513
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Keywords: Cutting, Surfaces, Ultra-Precision Machining |
Abstract : The depth of the subsurface damaged layer in ultraprecision machined CdS
was examined by studying the interaction of energetic ions with the
workpiece surface Single crystal (0001) oriented CdS was diamond turned
at depths of cut of 01 and 1 25 mm, and subsurface lattice disorder was
examined for regions cut parallel to, and 30 degrees off, a preferred
cleavage plane. The energy spectrum of 2 MeV ^4 He^+ ions backscattered
from the crystal surface was used to obtain a depth of the disorder
Results were compared to there obtained for chemo-mechanically and
hydroplane polished surfaces.
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Roughness parameters of surfaces by atomic force microscopy
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K. Carneiro, C.P. Jensen, J.F. Jorgensen, J. Garnoes / P.A. McKeown (1)
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STC S, 44/1/1995, P.517
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Keywords: 3D Surface Topography, Roughness, Atomic Force Microscopy |
Abstract : We present a standardized measurement report for surfaces investigated
by scanning probe microscopy (SPM), which include twenty
three-dimensional roughness parameters to characterize the surface
topography. The examples are some polished copper samples and the scan
size is 5 um x 5 mm. Some of the parameters are generalizations of
two-dimensional standards, and some are three-dimensional parameters
normally used at larger scan sizes (mm x mm). Furthermore, there are
some newly developed parameters extracted from Fourier analysis that
reflect the directionality of surface texture. The parameters are
discussed and it is shown that not all parameters are giving
meaningfully information on um-range scans.
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Brittle-Ductile transition phenomena in microindention and micromachining
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S. Shimada (2), T. Inamura, N. Takezawa, H. Ohmori, T. Sata (1), N. Ikawa (1)
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STC S, 44/1/1995, P.523
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Keywords: Micro Machining, Ductile Transition, Brittle Material |
Abstract : A generalized hypothesis for the brittle to ductile transition in
micromachining and microindentation of brittle materials is proposed By
the hypothesis, complicated transition phenomena observed in practical
machining processes are well explained Experimental results on
microturning, ELID grinding of monocrystalline Si and LiNb03 support the
applicability of the hypothesis Microindentation testing is shown to
evaluate the intrinsic ductility and critical scale of machining for
ductile mode machining To analyze the machining prowssin extremely small
scale, molecular dynamics computer simulations of microindentation and
cutting are made on a defect-free surface These results suggest that any
material, in spite of their ductility, can be machined in ductile mode
under the sufficiently small scale of machining.
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