Table Of ContentAdvanced Manufacturing
Springer-Verlag London Ltd.
Other titZes published in this series:
A Systems Approach to AMT Deployment
D.R. Towill andl. Cherrington (Eds)
Human-Intelligence-Based Manufacturing
Y. Ito (Ed.)
Intelligent Manufacturing: Programming Environments for CIM
w.A. Gruver and I.C. Boudreaux (Eds)
Automatic Supervision in Manufacturing
M. SzaJarczyk (Ed.)
Modern Manufacturing
M.B. Zaremba and B. Prasad (Eds)
Advanced Fixture Design for FMS
A. Y.G. Nee, K. Whybrew and A. Senthil kumar
Intelligent Quality Systems
D. T. Pham and E. OztemeZ
Computer-Assisted Management and Control ofManufacturing Systems
S.G. TzaJestas (Ed.)
The Organisation ofIntegrated Product Development
V. Paashuis
Advance Manufacturing: Decision, Control and Information Technology
S.G. TzaJestas (Ed.)
A.Y.C. Nee, S.K. Ong and Y.G. Wang (Eds)
Computer Applications in
Near Net-Shape Operations
With 243 Figures
, Springer
A. Y.e. Nee, PhD
S.K. Dng. PhO
Mechanical & Production Engineering Department,
National University ofSingapore, 10 Kent Ridge Crescent, Singapore 119260
Y.G. Wang, PhD
Huazhong UniversityofScience & Technology,
11-602, West Second #zone Wuhan, Hubei, 430074, PR China
Series Editor
Professor Duc Truong Pham, PhD, DEog. CEng. FIEE
UniversityofWales Cardiff, Schaol ofEngineering, Systems Division,
P.D. Box 917, CardiffCF2 lXH, UK
ISBN 978-1-4471-1159-7
Briti$h Library Cataloguing in Publication Dala
A calalogue rerord for this book is available from the British Library
Library of Congress Cataloging-in-Publication Data
Computer applications in neu nel-shapeoperations I A.Y.C. Nee, S.K.
Ong, and Y.G. Wang (e&.).
p. cm. - (Advanced manufacturingseries)
Indudes bibliographical references and indu.
ISBN 918-1-4471- 1159-7 ISBN 978-1-4471 -0547-3 (eBook)
DOI 10.1007/978-1-4471-0547-3
I. Near nelshape (melalwork) - Automation. 2. CADfCAM syslems..
I. Nee, A.Y.C. (Andrew Yeh Chru), 1948- . 11. Ong, S. K.,
1969- . III.Wang,Y.G., 1938- . IV.Series:Advanced
manufacturing series (Springer-Verlag)
TS213.C66 1999 99-35688
671.3-de21 elF
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C Springer-Verlag London 1999
Originally published by Springer-Verlag London Limited in 1999
Soflto,'cr rtprint oflhe harc.Jto,·er Ist ec.Jition 1999
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Foreword
Having edited "Journal of Materials Processing Technology" (previously entitled
"Journal of Mechanical Working Technology") for close on 25 years, I have seen
the many dramatic changes that have occurred in the materials processing field.
Long gone are the days when the only "materials processing" carried out was
virtually the forming of conventional metals and alloys, and when the development
of a new product or process in a great number of cases called for several months of
repetitive trial-and-error,' with many (mostly intuition- or experience-based)
expensive and time-consuming modifications being made to the dies, until success
was achieved. Even when a 'successful' product was formed, its mechanical
properties, in terms of springback and dimensional accuracy, thickness variations,
residual stresses, surface finish, etc., remained to be determined. Bulk-forming
operations usually required expensive machining to be carried out on the product to
impart the required dimensional accuracy and surface fmish.
Over the years, the experience-based craft of metal forming has given way to
the science of materials processing. With the use of the computer, forming
operations can be simulated with accuracy, to determine the best forming route and
the associated forming loads and die stresses, and to predict the mechanical
properties of the formed product, even down to its surface texture. The accuracy of
the products has increased remarkably, with research now being undertaken into the
allowances to be made in the manufacture of dies to compensate for the effect of
their elastic distortion on the dimensions of the product. The blanking operation
now extends down to such small size components as the lead frames of ICs, having
sub-millimeter widths, requiring previously unheard of accuracy of the alignment of
the punch and the die, and requiring the use of the fme-blanking process. Of
tremendous interest internationally is near net-shape forming, where components
can be produced of high dimensional accuracy, requiring no further operations to be
performed upon them before being put into service.
It is with great pleasure therefore, to see the present new book written by
A.Y.C. Nee, S.K. Ong and Y.G. Wang, covering as it does all the latest
developments over the whole field of materials processing, under the generic title
"Near Net-Shape Operations". That the authors are admirably qualified to write
such a book is beyond question, judging from their great many published works in
the areas concerned. The book is not overly academic, but considers the industrially-
relevant aspects of the work, and provides many examples of application of the
vi _________________________ Foreword
techniques and systems involved for the benefit of the reader.
CAD/CAMICAE/CNCIFMCIIPDIFEM, expert systems, etc are all introduced and
explained, and examples given of their application in all of the relevant areas of near
net-shape forming, such as: sheet metal forming; stamping, blanking and fme
blanking; progressive stamping; bending; nibbling; punch and tool selection; die,
punch and ejector design and construction; wire EDM and its programming; bulk
metal forming; design of dies; calculation of forming loads; injection moulding;
wire-frame, surface and solid modelling; the design of plastic injection moulds; flow
simulation; cooling simulation; information transfer; tool path generation; etc. The
chapters on FEM and CNC are particularly expansive, and should be required
reading for all those, whether student, teacher or industrialist, working or
researching in these areas.
I congratulate the authors on having produced this splendid new book.
F.W. Travis
Preface
The proposal to write this book originated when Professor Y.G. Wang from the
Huazhong University of Science & Technology (HUST), PR China visited the
Department of Mechanical & Production Engineering, National University of
Singapore (NUS) in 1995. In search of a joint collaboration, Professor Wang and
Professor Nee suggested that since both universities had done a good amount of
work in the application of computer techniques to the design, simulation and
analysis of near net-shape operations, a book to detail the research findings would
be very appropriate.
We started with a thorough search on the availability of such a book and were
soon convinced that such a book did not exist. Although there were many articles
written on similar topics, it will be useful to group them under one cover. Since the
book was planned to cover many topics, it would not have been possible for both of
us to write all of them on our own. Therefore it was suggested that researchers from
both universities would be approached as contributors to the different chapters of
this book.
Planning continued for a year, but unfortunately Professor Nee was appointed
Dean of Faculty of Engineering from 1995 to 1998 and this slowed down the
progress of the book tremendously. Fortunately, a young faculty, Dr S.K. Ong
joined the department and she was most dedicated in assisting the compilation and
editorial work of this book. The authors must also thank Professor Duc Truong
Pham, the Series Editor and Mr Nicholas Pinfield of Springer-Verlag for their kind
patience in waiting for more than three years for this manuscript to be ready.
We intend this book to be of interest to researchers, graduate students and
practising engineers involved in the design, simulation and analysis of near net-
shape operations. We gratefully acknowledge the published information of many
distinguished researchers worldwide who had laid the foundation of this book. We
have included some of their contributions either in references or bibliography. We
would also like to thank many graduate students of the two universities who had
contributed to both the theoretical and experimental investigations of near net-shape
operations over the last decade.
The authors are most grateful to Professor F.W. Travis, the Chief Editor of the
Journal of Materials Processing Technology, for his kind and informative Foreword
to this book.
A.Y.C. Nee
National University o/Singapore
S.K. Ong
National University o/Singapore
Y.G. Wang
Huazhong University o/Science and Technology
Contents
List of Abbreviations xv
List of Authors xvii
1 Introduction to near net-shape operations 1
S.K. Ong and A.Y.C. Nee
1.1 Introduction ................................................................. 1
1.2 Classification of near net-shape operations .................. ........... 2
1.2.1 Sheet metal forming............ ...... ........................... 2
1.2.2 Massive (bulk) metal forming processes......... ... .......... 3
1.2.3 Injection moulding...... ...... ...... ...... ...... ...... ...... ..... 4
1.2.4 Machines for near net-shape operations ...... ...... .......... 4
1.3 Near net-shape operations: past, present and future .............. , ..... 5
Bibliography... ... ... ... ... ... ... ... ... ... ... ... ... ...... ... ... ... ... ... ...... ... .. ..... 5
2 CAD/CAM for sheet metal forming and related processes 7
Z.G. Li, N.F. Choong, K.H. See Toh, H.T. Loh and A.Y.C. Nee
2.1 Introduction and basic techniques ....................................... .. 7
2.1.1 Feature modelling of stampings ............................... . 7
2.1.2 Application of expert systems to stamping die design .... . 13
2.2 Optimisation of blank layout ............................................ .. 17
2.2.1 Mathematical description of blank layout .................. .. 18
2.2.2 The polygon method .......................................... .. 20
2.2.3 The height function method .................................. .. 21
2.3 Fine blanking ............................................................... . 26
2.3.1 Characteristics of the fme blanking process ................ .. 26
2.3.2 Application of the fme blanking process .................... . 27
2.3.3 CAD/CAM of fine blanking dies ............................ .. 27
2.4 Progressive stamping ....................................................... 34
2.4.1 Software architecture of the system .......................... . 35
2.4.2 Strip layout ... '" ................................................. . 36
2.4.3 Construction design of progressive dies .................... .. 42
x ________________________________________________ CONTENTS
2.5 An overview of a flat patterning and bending simulation system 49
2.5.1 Design input module ........................................... . 49
2.5.2 Flat pattern development module ............................. . 50
2.5.3 Bending simulation module ................................... . 50
2.5.4 System details ................................................... . 51
2.5.5 Implementation of bending simulation module ............ . 57
2.6 CNC punching and nibbling .............................................. . 64
2.6.1 Computer-based system for CNC nibbling .................. . 64
2.6.2 Punch libraries ................................................... . 65
2.6.3 Profile classification ............................................ . 66
2.6.4 Punch selection and optimisation ............................. . 67
2.6.5 An approach to automatic tool selection ..................... . 68
2.6.6 A case study ..................................................... . 74
2.7 Die construction design ................................................... . 76
2.7.1 Design of die and punch ........................................ . 76
2.7.2 Layout of ejectors ............................................... . 79
2.8 NC programming of wire EDM .......................................... . 84
2.8.1 Process consideration for NC programming of wire EDM
84
2.8.2 Geometric computation ....................................... .. 85
2.8.3 NC programming procedure for wire EDM ................. . 88
References ............................................................................. . 91
Bibliography ........................................................................... . 92
3 CAD/CAM for massive (bulk) metal forming 95
J.e. Xia
3.1 Introduction ................................................................. 95
3.2 Cold upsetting ............................................................... 97
3.2.1 Determination of operations and sequences... ... ............ 97
3.2.2 Calculation of process parameters....................... ..... 103
3.2.3 Design of dies cavities, general parts and combined dies 109
3.2.4 The BNC CAD system ... ... ... ...... ......... ... ...... ... ...... 114
3.3 Closed-die forging. .. .. . ... . . . . .. . . . .. . . . . ... ... .. . . .. . .. ... . .. . . . .... . . .... 116
3.3.1 Selection and calculation of bars ............ ........... ... .... 116
3.3.2 Determination of operations and sequences .................. 118
3.3.3 Calculation offorging load and stress................ ......... 126
3.3.4 Design of dies... ... ......... ...... ...... ... ...... ... ... ........ ... 131
3.3.5 Program flowchart and description................. ........... 140
References .............................................................................. 144
4 CAD/CAE/CAM for injection moulding 145
D.Q. Li and X.G. Ye
4.1 Introduction...... ... ... ...... ...... ... ... ...... ... ............ ...... ........ 145
4.1.1 Brief history of development......... ................. ........ 145
CONTENTS xi
4.1.2 Technological characteristics... ............................. ... 146
4.2 Graphic input and geometry construction of injection moulded
products ...................................................................... 148
4.2.1 Wire-frame modelling .................................... ....... 148
4.2.2 Surface modelling ... ... ... ...... ... ... ... ... ... ... ...... ........ 149
4.2.3 Solid modelling. .. ... ... ... ... ... .. . ... ... ... ... . .. ... . ..... ... .. 150
4.3 CAD for construction design of plastic injection moulds ............. 151
4.3.1 Program flowchart ................................. .............. 151
4.3.2 Standard mould base design... ... ...... ... ...... ... ........ .... 152
4.3.3 Cavity and core design ... ... ... ... ... ... ...... ... ............... 155
4.3.4 Runner bar design ... ... ...... ... ... ... ... ... ... ... .......... .... 156
4.4 Flow simulation of plastic injection moulding ... ... ... ... ... ....... .... 159
4.4.1 One-dimensional flow analysis... ...... ... ... ... ... ..... .. . ... 159
4.4.2 Two-dimensional flow analysis... ...... ... ... ... ... ........ ... 164
4.4.3 Three-dimensional flow analysis... ... ... ... ...... . .. ... .... ... 165
4.5 Cooling simula~on of plastic injection moulding ...... ... ... .......... 169
4.5.1 One-dimensional cooling analysis... ... ... ... ... ... ... ........ 169
4.5.2 Two-dimensional cooling analysis ............................. 171
4.5.3 Three-dimensional cooling analysis ... ... ... ... ... ..... ....... 174
4.6 CAM for plastic injection moulds................................. ....... 176
4.6.1 Integrated CAD/CAM system..................... ...... ....... 177
4.6.2 Information transfer from CAD to CAM............... ...... 178
4.6.3 Tool path generation in 2-D NC ... ... ... ... ... ... ... .......... 180
4.6.4 Manufacturing for 3-D core and cavity ... ... ... ... ... ........ 182
4.7 CAD/CAE/CAM system for plastic injection moulding......... ..... 184
4.7.1 System configuration... ... . .. .. . . .. ... . .. ... ... ... . .. .. . . . ...... 184
4.7.2 CAD software functions ... ...... ...... ... ... ............ ........ 185
4.7.3 CAE software functions...... ... ... . .. ... ... ... ... ... ... ....... 185
4.7.4 CAM software functions ... ... ... ...... ... ... ... ... ............. 186
Bibliography...... ... ... ... ... ... ... ...... ... ... ... ... ... ... ............ ... ... ... ... .... 186
5 FEM applications in near net-shape operations 187
J.e. Xia, S.J. Li and V.X. Ding
5.1 Introduction ................................................................ . 187
5.2 FEM applications and developments in near net-shape operations 188
5.2.1 New algorithms for automatic triangular mesh generation
188
5.2.2 New algorithms for mesh rezoning in FEM simulation ... . 195
5.2.3 Algorithms for generating isogram in FEM ................. . 199
5.2.4 Calculation of rigid regions using rigid-plastic FEM ...... . 203
5.3 FEM applications in massive (bulk) metal forming processes ...... . 206
5.3.1 Simulation of rigid-plastic finite element of radial
extrusion process ............................................... . 206
