In sheet metal forming, a sheet blank that has a simple shape is plastically formed between tools (or dies) to obtain a part with relatively complex geometry with desired tolerances and properties. Sheet metal forming processes usually produce little scrap and generate the final part geometry in a very short time, usually in one stroke or a few strokes of a press. As a result, sheet forming offers potential savings in energy and material, especially in medium and large production quantities, where tool costs can be easily amortized.
The ever-increasing costs of material, energy and manpower require that sheet metal forming processes and tooling be designed and developed with minimum amount of trial and error with shortest possible lead times. Therefore, to remain competitive, the cost-effective application of computer-aided technologies, i.e. CAD, CAM, CAE, and especially finite element analysis (FEA), computer-based simulation is an absolute necessity. Thus, process modeling using FEA has been discussed in all appropriate chapters.
The practical and efficient use of these technologies requires a thorough knowledge of the principle variables of the sheet metal forming processes and their interactions. These variables include:
the flow behavior and formability of the formed sheet material under processing conditions;
die geometry, materials and coatings;
friction and lubrication;
the mechanics of deformation, i.e. strains, stresses and forces;
characteristics of the sheet metal forming presses and tooling;
geometry, tolerances, surface finish and mechanical properties of the formed parts, and
the effects of the process on the environment.
These topics are addressed in two companion volumes Sheet Metal Forming—Fundamentals and Sheet Metal Forming—Processes and Applications. Principles are described, and major emphasis is placed on the latest developments on the design of sheet forming operations, equipment and tooling.
In Sheet Metal Forming—Fundamentals, the role of sheet metal forming in manufacturing has been introduced in Chapter 1. Chapter 2 gives the classification and description of sheet metal forming operations. The fundamentals of plastic deformation, i.e. metal flow, flow stress of materials, testing methods to determine flow stress and formability are discussed in Chapters 3, 4, and 5. Chapters 6 and 7 cover the significant process variables materials and friction. The introduction to deep drawing is discussed in Chapter 8. Chapters 9, 10, 11, and 12 discuss the characteristics and operations of various sheet metal forming presses (hydraulic, mechanical, servo-drive) and cushion systems.
In Sheet Metal Forming—Processes and Applications, Chapters 1 and 2 cover blanking, and bending. Process modeling and its applications are discussed in Chapter 3 as well as in several other chapters, where appropriate. Chapter 4 reviews progressive and transfer die forming. Relatively new technologies, i.e. warm forming, forming of advanced high strength steels (AHSS) and hot stamping are discussed in Chapters 5, 6, and 7, respectively. Processes that are related to sheet forming such as sheet and tube hydroforming, roll forming, and high velocity forming are covered in Chapters 8, 9, 10, and 11. Special sheet forming operations spinning, incremental forming and mechanical joining are discussed in Chapters 12, 13, and 14. Sensors and die materials are critical for practical application of sheet forming technology and they are discussed in Chapters 15 and 16.
The preparation of this book was possible through extensive efforts by many friends, associates and students of the editors who authored and co-authored many of the chapters. We would like to thank them all for their very valuable contributions.
We would like to thank Ms. Linda Anastasi, Administrative Assistant of the Center for Precision Forming (CPF), who revised the chapters several times, Mr. Xi Yang and Manan Shah at CPF who assisted in the editing of some chapters and Mr. Doug Dragoo of Cincinnati Inc. who reviewed Chapter 15 on Bending and made valuable suggestions. We would also like to thank our families, who offered us enormous support and encouragement throughout the preparation of this book.
Finally, we would like to gratefully acknowledge the financial support from member companies of CPF and especially from the National Science Foundation (NSF) that helped us summarize the results of sheet metal forming research, conducted over the years at The Ohio State University.
Center for Precision Forming (CPF)
The Ohio State University
Institut für Umformtechnik und Leichtbau (IUL)
Technische Universität Dortmund, Germany