applied metal forming including fem...

APPLIED METAL FORMINGIncluding FEM Analysis

Applied Metal Forming: Including FEM Analysis describes metalforming theory and how experimental techniques can be used tostudy metal forming operations with great accuracy. For each primaryclass of processes, such as forging, rolling, extrusion, wiredrawing, andsheet-metal forming, it explains how finite element analysis (FEA) canbe applied with great precision to characterize the forming conditionsand in this way optimize the processes. FEA has made it possible tobuild realistic FEM models of most metal forming processes, includ-ing complex three-dimensional forming operations, in which complexproducts are shaped by complex dies. Thus, using FEA, it is now pos-sible to visualize any metal forming process and to study strain, stress,and other forming conditions inside the parts being manufactured asthey develop throughout the process.

Henry S. Valberg is a professor in the Department of Engineering Sci-ence and Materials at the Norwegian University of Science and Tech-nology (NTNU). He began his professional career as a metallurgist atthe Royal Norwegian Air Force (LFK), and continued it at A/S NorskJernverk, Mo i Rana, and then as a research scientist at SINTEF, Divi-sion of Materials and Processes, before joining the Norwegian Instituteof Technology (NTH) as a senior lecturer in 1984 and full professor in1994. He was a visiting professor at Denmark’s Technical Universityin 1997–1998. Professor Valberg’s main fields of research are materi-als, metal forming, experimental deformation analysis, and FEA. Hiswork covers all the main metal forming processes, including forging,rolling, extrusion, drawing, and sheet-metal forming. He is the authorof more than 60 refereed journal articles and has supervised numerousgraduate students. Professor Valberg is currently a research managerin a project run by three Norwegian forging companies.

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Cambridge University Press978-0-521-51823-9 - Applied Metal Forming: Including Fem AnalysisHenry S. ValbergFrontmatterMore information

http://www.cambridge.org/9780521518239

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Applied Metal Forming

INCLUDING FEM ANALYSIS

Henry S. ValbergNorwegian University of Science and Technology






cambridge university pressCambridge, New York, Melbourne, Madrid, Cape Town, Singapore,Sao Paulo, Delhi, Dubai, Tokyo

Cambridge University Press32 Avenue of the Americas, New York, NY 10013-2473, USA

www.cambridge.orgInformation on this title: www.cambridge.org/9780521518239

c© Henry S. Valberg 2010

This publication is in copyright. Subject to statutory exceptionand to the provisions of relevant collective licensing agreements,no reproduction of any part may take place without the writtenpermission of Cambridge University Press.

First published 2010

Printed in the United States of America

A catalog record for this publication is available from the British Library.

Library of Congress Cataloging in Publication data

Valberg, Henry S., 1950–Applied metal forming : including FEM analysis / Henry S. Valberg.

p. cm.Includes bibliographical references and index.ISBN 978-0-521-51823-9 (hardback)1. Metal work – Mathematics. 2. Metal products – Mathematical models.3. Metal stamping – Mathematics. 4. Finite element method. I. Title.TS213.V25 2010671.3 – dc22 2009013702

ISBN 978-0-521-51823-9 Hardback

Additional resources for this publication at www.cambridge.org/valberg

Cambridge University Press has no responsibility for thepersistence or accuracy of URLs for external or third-party InternetWeb sites referred to in this publication and does not guarantee thatany content on such Web sites is, or will remain, accurate orappropriate.






Contents

Preface page vii

1 Characteristics of Metal Forming . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

2 Important Metal Forming Processes . . . . . . . . . . . . . . . . . . . . . . . . . 18

3 FEA of Metal Forming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

4 Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

5 Reduction and Proportions of the Plastic Zone . . . . . . . . . . . . . . . . . 77

6 Deformations from the Velocity Field . . . . . . . . . . . . . . . . . . . . . . . . 84

7 Technological Tests and Physical Simulation . . . . . . . . . . . . . . . . . . . 92

8 Flow Stress Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115

9 Formability and Workability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127

10 Friction and Friction Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139

11 Thermal Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159

12 Experimental Metal Flow Analysis . . . . . . . . . . . . . . . . . . . . . . . . . 181

13 Theoretical Methods of Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . 204

14 Finite Element Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219

15 FEA of Technological Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 242

16 Forging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 268

17 FEA of Forging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 285

v






vi Contents

18 Extrusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 320

19 FEA of Extrusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 347

20 Rolling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 365

21 FEA of Rolling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 376

22 Drawing of Wire, Profiles, and Tubes . . . . . . . . . . . . . . . . . . . . . . . . 395

23 FEA of Wiredrawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 414

24 Sheet-Metal Forming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 435

25 FEA of Sheet-Metal Forming (Available atwww.cambridge.org/valberg) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Index 453






Preface

Finite element analysis (FEA) has currently been developed into an efficient, user-friendly tool for investigation of metal forming processes. At the same time, cheap,efficient computers have been developed that allow simulation of metal forming tobe done by use of the finite element method (FEM), within reasonable times. Thisrecent development is, as this book will show, about to revolutionize the art of metalforming.

This technology has made it possible to build realistic FEM models of perhapsany metal forming process, including complex three-dimensional forming opera-tions, in which complex products are shaped by means of complex dies. Thus, byFEA, it is now possible to visualize any metal forming process on the computerscreen and to study strain, stress, and other important forming conditions inside theworkpiece, as they develop throughout the duration of the process. Because of this,FEA has also become an important industrial tool in connection with developmentand design of new metal forming processes.

However, in spite of this development, there is still need for classical theory asa tool for providing knowledge about forming. For a person to be able to utilize thenew FEA technology and to evaluate the results obtained in FEA, it is required thathe or she have deep insight into the theory of metal forming.

In order to establish correct FEM models, it is still required to investigate metalforming by means of experiments performed in the laboratory or on industrialequipment. Without some experimentation, it is difficult to know what informationshould be fed into the FEM model, and to what extent a simulation is precise. Ifinput data to the model is wrong, the usefulness of FEA may be limited.

Throughout his career, the author of this book has done much work to developnew visioplasticity methods for the study of metal flow in metal forming. In thisway, a new advanced grid pattern technique has been developed, which allows stripepatterns to be made in the interior of a workpiece and ring patterns to be addedonto its surface, to be shaped later by metal forming. These techniques are useful inthat they allow precise characterization of metal flow, inside and on the surface of aworkpiece.

vii






viii Preface

The book describes metal forming theory briefly and explains how experimen-tal techniques can be used to study the forming conditions of metal forming oper-ations with great accuracy. In addition, it is shown for each of the main classes ofmetal forming processes – forging, rolling, extrusion, wiredrawing, and sheet-metalforming – how FEA can be applied precisely to characterize forming conditions inthese operations, and in this way optimize the processes.

Examples are provided throughout the book to illustrate how theory, experi-ments, and FEA in combination can be used to calculate and characterize the con-ditions in a forming process. In each chapter, a number of illustrative problems areprovided. A solution manual will be provided separately.

The chapters dealing with FEA have been written so that it is not requiredfor the reader to apply a FEM program. Simulation results are presented, and thereader will gain experience in evaluation of postprocessing data from FEM models.However, the best situation for the reader will, of course, be if he or she has accessto a FEM simulation program and hence can rerun or modify some of the FEMmodels presented in the book.

The book is applicable on both the undergraduate and graduate levels in uni-versities and should also be useful for the metal-former working in industry.

In addition to the book’s printed content, additional materials have been madeavailable on the Web site www.cambridge.org/valberg. A full chapter on FEA ofsheet-metal is available for free review or download. Also available are color repre-sentations of many of the book figures designed to enhance the reader’s understand-ing. In the gray-scale figures, letters have been used to indicate color distribution asfollows: R = red, Y = yellow, G = green, LB = light blue, B = blue.

I would like to thank Dr. Dirk Nolte and Dr. Rama Krishna Uyyuru, who haveread through the manuscript and proposed improvements. Thanks are also due tomy current and former students, most of them on the master’s level, who haveworked with the topics covered by the book. I would also like to thank my homeuniversity (NTNU) for providing financial support for two sabbaticals. The FEApart of the book could not have been realized without this support.

Finally, I would like to express thanks to my wife, Beate Linge, for her patienceduring the time required for writing this book.

Trondheim, January 25, 2010






APPLIED METAL FORMING






applied metal forming including fem...

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