bk97pub2 table of content

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a guide to precision sheet metal bending

Steve D. Benson

PRESS BRAKETECHNOLOGY

Society of Manufacturing Engineers

D b Mi hi



Copyright © 1997 Society of Manufacturing Engineers

987654321

All rights reserved, including those of translation. This book, or parts

thereof, may not be reproduced in any form or by any means, including

photocopying, recording, or microfilming, or by an information storage

and retrieval system, without written permission from the copyright

owners.

No liability is assumed by the publishers with respect to the 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.

No responsibility is assumed by the publisher for any injury and/or

damage to persons or property as a matter of product liability, due to

negligence or otherwise, or from any use or operation of any methods,

products, instructions, or ideas contained in the material herein.

Library of Congress Catalog Card Number: 96-070755

International Standard Book Number: 0-87263-483-3

Additional copies may be obtained by contacting:

Society of Manufacturing Engineers

Customer Service

One SME Drive

Dearborn, MI 48121

1-800-733-4763

SME staff who participated in producing this book:

Larry Binstock, Senior Editor

Rosemary Csizmadia, Operations Administrator

Frances Kania, Production Assistant

Judy Munro, Manager, Graphic Services

Dorothy Wylo, Production Assistant

Cover photo courtesy of The LVD Corporation



ABOUT

THE SOCIETY OF MANUFACTURING

ENGINEERS

Founded in 1932, the Society of Manufacturing Engineers (SME) is a nonprofit professional society dedicated to the advancement of scien-

tific knowledge in the field of manufacturing engineering. By providing

direction for the evolution of manufacturing, SME has earned an inter-

national reputation for leadership in manufacturing technology.

Among its activities, SME produces and distributes a vast array of

literature focusing on state-of-the-art, as well as traditional manufac-

turing techniques. Press Brake Technology, a Guide to Precision Sheet

Metal Bending, is a product of this ambitious publishing effort, which

includes books, periodicals, videotapes, and an on-line data service.For a catalog of SME publications, call 1-800-733-4763.



This book is dedicated to my wife, Patricia, for the countless hours

she spent proofreading this work, which would not have been possible

without her. Thank you!



Contents

Preface .................................................................................................. xiii

Chapter 1—The Machine ............................................................ 1

The History and the Machines............................... 1

Chapter 2—Types of Bends ..................................................... 11

Three Types ......................................................... 11

Chapter 3—Tools of the Trade .................................................. 15

Precision Tools of Sheet Metal ............................ 15

Chapter 4—The Controllers ..................................................... 25

The Modes .......................................................... 25Terminology ......................................................... 33

Chapter 5—Safety Tips ............................................................. 35Machine Setup .................................................... 35Operational Safety ............................................... 36General Safety Tips .............................................38

Chapter 6—General Mathematics ............................................ 41

Integers ............................................................... 41

Chapter 7—Trigonometry (Right Angle) ................................. 45

Chapter 8—Bend Functions..................................................... 53

Bend Charts ........................................................53Terminology......................................................... 54

Working with Sharp Bends.................................. 59Working with ISTM .............................................. 65Working Bend Deductions

for Bends Over 90° ......................................... 66

Chapter 9—Flat Pattern Development .................................... 67



Chapter 11—Notching .............................................................. 87

Four Types ........................................................... 87

Chapter 12—Program Writing .................................................. 91

Saving Programs ................................................. 91

Chapter 13—The Tooling .......................................................... 95

Springback .......................................................... 95

Factors Affecting Springback ............................... 96

Chapter 14—The Punches...................................................... 101Types of Punches .............................................. 101

Chapter 15—The Dies ............................................................. 109

Die Width Selection ........................................... 109

Profound Radius Bends .................................... 119

Chapter 16—Special Purpose Tooling ................................... 129

Bottom Bending ................................................. 129Coining .............................................................. 131

Chapter 17—Acute Angle Bends ........................................... 133

Punch Radii ....................................................... 134

Chapter 18—Hemming and Seaming .................................... 137

Chapter 19—Offset Tooling ................................................... 141

Two Styles ......................................................... 141

Chapter 20—Urethane Tooling ............................................... 151

Advantages and Disadvantages ........................ 151

Terms ................................................................ 152

Characteristics .................................................. 152

Working Parameters .......................................... 154

Chapter 21—Machine Operations.......................................... 161Machine Setups ................................................ 161



Chapter 22—Creative Solutions for Common Problems..... 171

Window Punches .............................................. 171

Form Gussets.................................................... 176Carrying a Bend or Creative Die Spacing .......... 177

Forming Wraps .................................................. 178

Squaring the Stops............................................ 179

Chapter 23—Gaging................................................................ 181

Side Gaging ......................................................181

Chapter 24—Pin Gaging ......................................................... 185What is Pin Gaging?..........................................185

Chapter 25—Deep Box Forming ............................................ 189

Chapter 26—Related Equipment ........................................... 193

Slip Roller .......................................................... 193

Chapter 27—The Leaf Brake .................................................. 205

Composition of the Leaf Brake .......................... 205

Index.................................................................................................... 209



PREFACE

In the 20 odd years that I have been in the precision sheet metal

trade, I have never found any comprehensive information regarding press

brake operations.

Sure, there were sales brochures and an occasional magazine article,

but never could I find a complete text. That void gave me the motivation

to write this book.Over the years I collected and saved every bit of information I found

on the subject of press brakes. That, coupled with 20 plus years of expe-

rience, gave me the knowledge I try to impart here. I truly hope this

work becomes the comprehensive text for press brake operators of the

future, as well as those who work in the field today.

Many different people and organizations over the last 100 years have

developed the information that I present in this text. To them I am

truly indebted. I also thank Larry Binstock and SME who took a chance

on me and published this work.Thank you all.

Steve D. Benson

Salem, Oregon



To order call

1-800-733-4763

or visit

www.sme.org/store

and search on book title

http://www.sme.org/store

http://www.sme.org/store

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