FUNDAMENTALS OF HYDROFORMING. Harjinder Singh. Society of Manufacturing Engineers

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1 FUNDAMENTALS OF HYDROFORMING Harjinder Singh Society of Manufacturing Engineers Association for Forming B Fabricating Technologies of the Society of Manufacturing Engineerr

2 Copyright by the Society of Manufacturing Engineers All rights reserved, including those of translation. This book, or parts thereof, may not be reproduced by any means, including photocopying, recording or microfilming, or by any information storage and retrieval system, without permission in writing of the copyright owners. No liability is assumed by the publisher with respect to use of information contained herein. While every precaution has been taken in the preparation of this book, the publisher assumes no responsibility for errors or omissions. Publication of any data in this book does not constitute a recommendation or endorsement of any patent, proprietary right, or product that may be involved. Library of Congress Catalog Card Number: International Standard Book Number: Additional copies may be obtained by contacting: Society of Manufacturing Engineers Customer Service One SME Drive, P.O. Box 930 Dearborn, Michigan Cover photo courtesy of Schuler Hydroforming, Inc. Printed in the United States of America

3 I am dedicating this book to my family. My wife Surinder, daughter Kiran, and sons Ravi and Sukhi. Thank you Sukhi for the very useful patent search that you conducted.

ACKNOWLEDGMENTS While researching the material for the book one day, I had a number of papers and other publications spread around on the living room floor, along with high-lighted sections and my

4 ACKNOWLEDGMENTS While researching the material for the book one day, I had a number of papers and other publications spread around on the living room floor, along with high-lighted sections and my rough notes. My daughter Kiran walked into the room and asked if I was plagiarizing other people s work. I had an interesting discussion with her on the difference between research and plagiarism. I want to take this opportunity to thank everybody in the hydroforming industry who makes the effort to publish their work. You may see a glimpse of your work in this book. I have tried to acknowledge all my sources at the end of each chapter and in the bibliography section. If your name is missing, please rest assured it was not intentional. I personally have benefited immensely from the published works of Prof. Fritz Dohmann of University of Paderborn (Germany), Blair Longhouse of Vari-Form, Dr. Charles Bruggemann and Shanjay Shah of General Motors Corp., Lawrence Oldacre of Eagle Precision Technologies, and Paul Brownback of D.A. Stuart Company. Additionally I would like to express my gratitude to the following for their contribution: The reviewers of this book prior to publication, for their valuable advice: Dr. Charles J. Bruggemann, Group Manager, Principal Engineer Body Structure Center, Advanced Manufacturing, General Motors Corp.; Prof. Xin Wu, Department of Mechanical Engineering, Wayne State University, Detroit, Michigan; Steven Lotspaih, Project Leader, Hydroforming Development, Tower Automotive; and Gary Webb, President, Hydrodynamic Technologies, Inc. Hydrodynamic Technologies, Inc. for their tremendous support and permission to use valuable material, and their hydroforming team for their constructive input, advice, and acting as sounding boards for nearly all of the material contained in this book. vi i

5 viii Fundamentals of Hydroforming The Society of Manufacturing Engineers (SME) for editing and publishing this book. In particular Phil Mitchell, Senior Editor, for constant encouragement and providing what it took to keep me motivated. I want to particularly thank my engineering mentors and colleagues Graham Foster and Brian Swan from my first job at Linread Ltd. I also want to express my appreciation for the time I spent at BL Technology, Ltd. with Alan Ancliff and Dave Dickinson; at Hawtal Whiting, h c with Nigel Rock and John Packwood; and at Hydrodynamic Technologies, Inc. with Ralf Ropper, Kathy Price, Tom Price, Gary Webb, Jim Brown, Joe Jakubik, Jim Shadwell, Suk- Je Lee, Kevin Webb, and Kim Spencer. It is my sincere hope and expectation that this book will serve its readers well. Any suggestions and comments are welcomed. I can be contacted at: Hydrodynamic Technologies, Inc. 30 W. Silverdome Industrial Park Pontiac, MI hsinghahdt-@.corn - Harjinder Singh July 1,2003

6 CONTENTS Chapter 1 Introduction to Hydroforming 1 The Basic Process 1 History of Tube Hydroforming to through the Present 10 The Future of Hydroforming 14 Chapter 2 Tube Hydroforming 19 Hydroforming Terminology 1 9 Low-Pressure Hydroforming 2 1 High-pressure Hydroforming 23 Multipressure Hydroforming 23 Hydrobulge Hydroforming 24 Bellows Forming 27 Chapter 3 Sheet Metal Hydroforming 29 Hydroforming with a Membrane Diaphragm 29 Hydromechanical Deep Drawing 31 Hydraulic Stretch Forming 32 Combined Deep Drawing and Stretch Forming 32 Double-Blank Hydroforming 33 Chapter 4 Advantages of Hydroforming 37 Hydroforming versus Stamping 3 7 Advantages of Tubular Hydroforming 38 Engine Cradle 39 Radiator Support Structure 42 Exhaust Y Joint 42 Oven-Door Handle 43 Advantages of Sheet Metal Hydroforming 44 ix

7 X Fundamentals of Hydroforming Chapter 5 Product Design Guidelines 45 Design Guidelines for Structural Members 46 Design Procedure 47 Establishing Packaging Space 47 Construct Centerline along Member Length 48 Establish Sections along Length 49 Blend Sections to Form Surfaces 52 Calculate Forming Pressure and Press Tonnage and Material Thinning due to Bending 52 Guidelines for Expansion with Axial Feeding 57 Guidelines for Branched and Axially Symmetric Components Product Design Guidelines for Sheet Metal Hydroforming 63 Chapter 6 Methods of Assembly 67 Welding 68 MIG Welding 68 Design Guidelines for MIG Welding Spot Welding 71 Laser Welding 73 Threaded-Fasteners Chapter 7 Hydropiercing Holes and Slots 77 Design Considerations 77 Hydropiercing Inward 78 Punch-Force Calculation 80 Surface Deformation around a Hole 81 Slug Management 83 Hydropiercing Outward 84 Backup Punch-Force Calculation 84 Minimum Fluid Pressure for Outward Piercing Hole Shape, Size, and Location 85 Other Methods of Forming Holes and Slots 86 Laser Cutting 87 Flow Drilling 88 Conventional Punching 90 Milling and Drilling 90 85

8 Contents xi Chapter 8 Materials Selection 91 Materials Suitable for Hydroforming 91 Material Properties 93 Tensile Testing 94 Material Elastic Range 96 Plastic Range 98 Strain Hardening 101 Plastic-Strain Ratio 102 Grid-Circle Analysis 104 Forming-Limit Diagrams 106 Material-Property Rules of Thumb 108 Chapter 9 Tube Selection 109 Tube Choices 109 Seamless Tube 110 ERWTube 113 Drawn-Over-Mandrel Tube 1 17 Roll- and Press-Formed Tubular Blanks 1 17 Extruded Tubular Sections 1 18 Other Requirements 12 1 Chapter 10 Priorand Post Operations * 127 Tube Bending 128 Hydrobending 128 Rota y-draw Bending 129 Design Guidelines for Draw Bending 131 Pre-forming 134 Tube-End Swagging 136 Heat Treatment 136 Lubrication 13 7 Tube-End Preparation 139 Tube Bending 139 Hydroforming System Fluid 140 Hydroforming Operation 1 40 End Trimming 142 Saw Cutting 143 Shearing 144 Laser Cutting 144 Assembly Methods 147

9 xii Fundamentals of Hydroforming Chapter 1 1 Process Computer Simulation 149 Advantages of Simulation 149 Hydroforming Process Steps 150 Tube-Forming Simulation 152 Tube-Bending Simulation 153 Pre-Forming Simulation 157 Hydroforming Simulation 158 Hydroforming Tool and Press Assessment 161 Exhaust-Component Case Study 163 Hydroforming Option Hydroforming Option Comparison of Actual and Predicted Results 166 Process-Simulation Conclusions 168 Chapter 12 Hydroforming System Equipment 171 System Overview 171 Hydroforming Equipment 173 Hydroforming Hydraulic Systems 177 Hydroforming Process Control 177 Chapter 13 Tubular Hydroforming Tool Design 183 Required Design Data 183 Process Steps 184 Prototype Tools 185 Production Tools 187 Die-Design Steps 188 Step 1: Establish die-tip angles and split line 190 Step 2: Build suitable addenda 191 Step 3: Design component layout 191 Step 4: Complete fool layout and design 192 Step 5: Design forfeuid management 193 Tube-End Sealing 193 Sealing Method Sealing Method Sealing Method Sealing-Force Calculation 197 Bibliography 201 Index 207

10 P R E FAC E Low cost, low mass, improved structural performance, and improved quality very rarely come together in a single manufacturing process. With proper product and process design, all these benefits are possible with the hydroforming process. The overall requirements for successful implementation of the hydroforming process are fully discussed in this book. It also covers the history and fundamentals of the hydroforming process, with comprehensive guidelines for product design, selection of suitable materials, computer simulation of the hydroforming process, and an introduction to hydroforming tool design. The book is intended for product designers, manufacturing engineers, and companies who want to implement hydroforming. Its objective is to provide technical information on the hydroforming process in one easy-to-follow source. I wrote this book with the sincere hope it will benefit the hydroforming industry worldwide. The significant weight savings and improved structural performance, especially when applied to automotive structures, will have considerable beneficial impact on the environment and occupant safety. xiii

About The Society of Manufacturing Engineers (SME) The Society of Manufacturing Engineers is the world s leading professional society supporting manufacturing education.

11 About The Society of Manufacturing Engineers (SME) The Society of Manufacturing Engineers is the world s leading professional society supporting manufacturing education. Through its member programs, publications, expositions, and professional development resources, SME promotes an increased awareness of manufacturing engineering and helps keep manufacturing professionals up to date on leading trends and technologies. Headquartered in Michigan, SME influences more than half a million manufacturing engineers and executives annually. The Society has members in 70 countries and is supported by a network of hundreds of chapters worldwide. Visit us at About AFFT/SM E The Association for Forming & Fabricating Technologies of SME (AFFT/SME) focuses on the technologies and processes that efficiently make pgoducts from metal sheet, coil, plate,-tube, or pipe stock. Typical industries served are automotive, off-highway, aerospace, defense, appliance, furniture, and consumer electronics products. Core processes include general pressworking-stamping, drawing, forming, bending, and shearing, for example-as well as the fabricating technologies of punching, cutting, sawing, welding, and others. Many AFFTSME members are manufacturing, tool, or process engineers specializing in keeping production forming or fabricating technologies current for their companies; general stamping, fabricating, welding, and assembly managers responsible for overseeing plant operations; and owners, partners, proprietors, and other company officials of relevant job shops. AFFT/SME membership allows such people to more quickly identify innovations that can lower costs while increasing product quality and yield. The AFFT/SME community also fosters learning among members to better manage their businesses and interact with customers, suppliers, and industry partners. xv

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User's Guide to. Rapid Prototyping. Todd Grimm. Society of Manufacturing Engineers. Association of SME. Dearborn, Michigan

User's Guide to. Rapid Prototyping. Todd Grimm. Society of Manufacturing Engineers. Association of SME. Dearborn, Michigan User's Guide to Rapid Prototyping Todd Grimm Society of Manufacturing Engineers Rapid Prototyping Association of SME Dearborn, Michigan Copyright 2004 Society of Manufacturing Engineers 987654321 All rights