Mechanics of Sheet Metal Forming 2E



Elsevier Science | ISBN 0 7506 5300 0 | ENGLISH | PDF | 228 PAGES | 2.21 MB

Introduction
The first edition of this book was published a decade ago; the Preface stated the objective in the following way.
In this book, the theory of engineering plasticity is applied to the elements of common sheet metal forming processes. Bending, stretching and drawing of simple shapes are analysed, as are certain processes for forming thin-walled tubing. Where possible, the limits governing each process are identified and this entails a detailed study of tensile instability in thin sheet.
To the authors’ knowledge, this is the first text in English to gather together the mechanics of sheet forming in this manner. It does, however, draw on the earlier work of, for example, Swift, Sachs, Fukui, Johnson, Mellor and Backofen although it is not intended as a research monograph nor does it indicate the sources of the models. It is intended for the student and the practitioner although it is hoped that it will also be of interest to the researcher. This second edition keeps to the original aim, but the book has been entirely rewritten to accommodate changes in the field and to overcome some earlier deficiencies. Professor Hu joined the authors and assisted in this revision. Worked examples and new problems (with sample solutions) have been added as well as new sections including one on hydroforming. Some of the original topics have been omitted or given in an abbreviated form in appendices. In recent years, enormous progress has been made in the analysis of forming of complex shapes using finite element methods; many engineers are now using these systems to analyse forming of intricate sheet metal parts. There is, however, a wide gulf between the statement of the basic laws governing deformation in sheet metal and the application of large modelling packages. This book is aimed directly at this middle ground. At the one end, it assumes a knowledge of statics, stress, strain and models of elastic deformation as contained in the usual strength of materials courses in an engineering degree program. At the other end, it stops short of finite element analysis and develops what may be called ‘mechanics models’ of the basic sheet forming operations. These models are in many respects similar to the familiar strength of materials models for bending, torsion etc., in that they are applied to simple shapes, are approximate and often contain simplifying assumptions that have been shown by experience to be reasonable. This approach has proved helpful to engineers entering the sheet metal field. They are confronted
with an industry that appears to be based entirely on rules and practical experience and they require some assistance to see how their engineering training can be applied to the design of tooling and to the solution of problems in the stamping plant. Experienced sheet metal engineers also find the approach useful in conceptual design, in making quick calculations in the course of more extensive design work, and in interpreting and understanding the finite element simulation results. Nevertheless, users of these models should be aware of the assumptions and limitations of these approximate models as real sheet metal designs can be much more complex than what is captured by the models. The order in which topics are presented has been revised. It now follows a pattern developed by the authors for courses given at graduate level in the universities and to sheet metal engineers and mechanical metallurgists in industry and particularly in the automotive field. The aim is to bring students as quickly as possible to the point where they can analyse simple cases of common processes such as the forming of a section in a typical stamping. To assist in tutorial work in these courses, worked examples are given in the text as well as exercises at the end of each chapter. Detailed solutions of the exercises are given at the end of the text. The possibility of setting interesting problems is greatly increased by the familiarity of students with computer tools such as spread sheets. Although not part of this book, it is possible to go further and develop animated models of processes such as bending, drawing and stamping in which students can investigate the effect of changing variables such as friction or material properties. At least one package of this kind is available through Professor Duncan and Professor Hu. Many students and colleagues have assisted the authors in this effort to develop a sound and uncomplicated base for education and the application of engineering in sheet metal forming. It is impossible to list all of these, but it is hoped that they will be aware of the authors’ appreciation. The authors do, however, express particular thanks to several who have given invaluable help and advice, namely, A.G. Atkins, W.F. Hosford, F. Wang, J. Camelio and the late R. Sowerby. In addition, others have provided comment and encouragement in the final preparation of the manuscript, particularly M. Dingle and R. Andersson; the authors thank them and also the editorial staff at Butterworth- Heinemann.

Download