Computer AidedDesign andManufacturing

K. Lalit NarayanK. Mallikarjuna RaoM.M.M. Sarcar

COMPUTER AIDED DESIGN AND MANUFACTURING

ComputerAidedDesign and Manufacturing

K. LALIT NARAYANAssociate ProfessorDepartment of Mechanical EngineeringSir C.R.R. College of EngineeringEluru

K. MALLIKARJUNA RAO, Ph.D.HeadDepartment of Mechanical EngineeringJNTU College of EngineeringKakinada

M.M.M. SARCAR, Ph.D.ProfessorDepartment of Mechanical EngineeringA.U. College of EngineeringAndhra UniversityVisakhapatnam

New Delhi-1100012008

COMPUTER AIDED DESIGN AND MANUFACTURINGK. Lalit Narayan, K. Mallikarjuna Rao and M.M.M. Sarcar

© 2008 by PHI Learning Private Limited, Delhi. All rights reserved. No part of this book may be reproduced in any form, by mimeograph or any other means, without permission in writing from the publisher.

ISBN-978-81-203-3342-0

The export rights of this book are vested solely with the publisher.

Second Printing … … July, 2013

Published by Asoke K. Ghosh, PHI Learning Private Limited, Rimjhim House, 111, Patparganj Industrial Estate, Delhi-110092 and Printed by Mohan Makhijani at Rekha Printers Private Limited, New Delhi-110020.

Foreword xxiiiPreface xxvAcknowledgements xxix

Part I CAD—Fundamentals of Design, Computers and Controllers

1. FUNDAMENTALS OF CAD 3–191.1 Introduction 31.2 The CAD System—Definition 31.3 Reasons for Implementing CAD 41.4 Design Process 4

1.4.1 Shigley Model 51.4.2 Pahl and Beitz Model 61.4.3 Ohsuga Model 81.4.4 Earle Model 9

1.5 Application of Computers in Design 141.5.1 Geometric Modelling 141.5.2 Engineering Analysis 151.5.3 Design Review and Evaluation 161.5.4 Automated Drafting 16

1.6 Benefits of Computer Aided Design 171.7 Creating the Manufacturing Database 18Review Questions 19

2. COMPUTER SYSTEMS 20–392.1 Introduction 202.2 Hardware Components 20

2.2.1 Central Processing Unit 202.2.2 Memory 222.2.3 Memory—ROM and RAM 24

CONTENTS

v

vi Contents

2.3 Mass Storage Devices 262.4 Input/Output Devices 292.5 Programming Languages 332.6 Operating System 352.7 System Configuration 36Review Questions 39

Part II CAD—Hardware and Software Components

3. USE OF COMPUTERS IN CAD/CAM SYSTEM 43–723.1 Introduction 433.2 Microcomputer Based Systems 44

3.2.1 Overview of Microcomputer Systems 453.2.2 Microcomputer Instructions 48

3.3 Minicomputer Based Systems 493.3.1 Minicomputer Instructions 50

3.4 Mainframe-based Systems 513.5 Supercomputers 53

3.5.1 Defining a Supercomputer 533.5.2 Why do We Need Supercomputers? 553.5.3 How do Supercomputers Achieve Their Speed? 583.5.4 Applications of Supercomputers 59

3.6 Programmable Logic Controller 613.6.1 Components of a PLC 623.6.2 Open PLC Systems 633.6.3 The IEC 1131-3 Programming Standard 64

3.7 Manufacturing and Assembly Processes 693.8 Advantages and Disadvantages of PLC 69Review Questions 72

4. CAD SYSTEM HARDWARE 73–914.1 Introduction 734.2 The Design Workstation 744.3 Graphics Terminal 74

4.3.1 Image Generation in Computer Graphics 744.4 Graphics Terminals for CAD 76

4.4.1 Directed Beam Refresh Tube (DBRT) 764.4.2 Direct View Storage Tube (DVST) 774.4.3 Raster Scan Terminals (Digital TV) 77

4.5 Graphics Input Devices 784.5.1 Cursor Control Devices 794.5.2 Digitizers 824.5.3 Keyboard Terminals 82

Contents vii

4.6 Graphics Output Devices 834.6.1 Pen Plotters 834.6.2 Hardcopy Unit 854.6.3 Electrostatic Plotters 864.6.4 Computer-Output-to-Microfilm (COM) Units 86

4.7 Modes of Operation 874.7.1 Hard Copy Mode 874.7.2 On-line Mode 874.7.3 Off-line Mode 884.7.4 Remote Mode 88

4.8 CAD System Configuration 88Review Questions 90

5. CAD SYSTEM SOFTWARE 92–116Introduction 925.1 Graphics Software 93

5.1.1 The Software Configuration of a Graphics System 945.2 Functions of a Graphics Package 95

5.2.1 Generation of Graphic Elements 955.2.2 Transformations 965.2.3 Display Control and Windowing Functions 965.2.4 Segmenting Functions 965.2.5 User Input Functions 97

5.3 Constructing the Geometry 975.3.1 The Use of Graphics Elements 975.3.2 Defining the Graphic Elements 985.3.3 Editing the Geometry 99

5.4 Operating System 1005.5 Software Modules 101

5.5.1 Operating System Module 1015.5.2 Graphics Module 1015.5.3 Applications Module 1015.5.4 Programming Module 1025.5.5 Communications Module 102

5.6 Graphics Standards 1025.7 Standards for Graphics Programming 102

5.7.1 Features of GKS 1035.7.2 GKS-3D 1035.7.3 Programmers Hierarchical Interactive Graphics Standard (PHIGS) 1035.7.4 Initial Graphics Exchange Specification (IGES) Graphics Standard 104

5.8 Product Data Based Format 1065.9 Standard for the Exchange of Product Model Data (STEP) 1075.10 Drawing Exchange Format (DXF) 1115.11 DMIS 112

viii Contents

5.12 Parasolid 1125.12.1 Modelling Functionalities of Parasolid 1135.12.2 Applications 114

5.13 ACIS 1155.13.1 ACIS Architecture 115

Review Questions 116

6. PRINCIPLES OF INTERACTIVE COMPUTER GRAPHICS 117–140Introduction 1176.1 Graphic Primitives 118

6.1.1 Point Plotting 1186.1.2 Drawing of Lines 118

6.2 Line Drawing Algorithms 1196.2.1 DDA Algorithm 1206.2.3 Bresenham’s Line Algorithm 1216.2.4 Bresenham’s Line-Drawing Algorithm for |m| < 1 123

6.3 Bresenham’s Circle Algorithm 1246.3.1 Properties of Circles 124

6.4 Ellipse-Generating Algorithms 1266.5 Scan Conversion 1286.6 Rendering 130

6.6.1 Rasterizing Polygons 1316.6.2 Hidden Surface Elimination 132

6.7 Z-buffer Algorithm 1336.7.1 Scan Line Z-buffer Algorithm 133

6.8 Antialiasing 1346.8.1 Super Sampling or Post Filtering 1346.8.2 Area Sampling or Prefiltering 1356.8.3 Pixel Phasing 1356.8.4 Stochastic Sampling 135

6.9 Reflection 1356.10 Shading 138

6.10.1 Gouraud Shading 1386.10.2 Phong Shading 139

Review Questions 140

7. TRANSFORMATION SYSTEMS 141–156Introduction 1417.1 Transformation Principles 1417.2 Two-Dimensional Geometric Transformations 141

7.2.1 Scaling 1427.2.2 Translation 1427.2.3 Rotation 143

Contents ix

7.3 Three-dimensional Geometric Transformations 1447.3.1 Scaling 1457.3.2 Translation 1457.3.3 Rotation 146

7.4 Linear Transformations 1477.5 Display 1497.6 Windowing and Clipping 1507.7 Display Files for Three-dimensional Data 1507.8 Visualization of Three-dimensional Data 151

7.8.1 Perspective Transformation 1527.8.2 Brightness Modulation 1537.8.3 Hidden-line removal 1537.8.4 Shading 1537.8.5 Movement 154

Review Questions 154Practice Problems 155

8. WIRE FRAME MODELLING 157–186Introduction 1578.1 Importance of Geometric Modelling 1578.2 Requirements of Geometric Modelling 1578.3 Types of Models 158

8.3.1 Wire Frame Modelling 1588.3.2 Surface Modelling 1598.3.3 Solid Modelling 160

8.4 Wire Frame Entities 1618.5 Representation of Curves 1618.6 Design of Curved Shapes 1638.7 Analytic Curves 1648.8 Parametric Representation of Analytic Curves 164

8.8.1 Line 1648.8.2 Circles 1658.8.3 Ellipse 1678.8.4 Parabola 1698.8.5 Hyperbola 171

8.9 Synthetic Curves 1728.10 Parametric Representation of Synthetic Curves 173

8.10.1 Cubic Spline Curves 1748.10.2 Bezier Curves 1768.10.3 B-spline Curves 177

8.11 Limitations of Wire Frame Modelling 178

Computer Aided Design AndManufacturing

Publisher : PHI Learning ISBN : 9788120333420Author : LALIT NARAYAN,K., MALLIKARJUNA RAO,K., SARCAR, M.M.M.

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