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CAD CAM Theory and Practice PDF

667 Pages·2012·20.59 MB·English
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i Ibrahim Zeid R Sivasubramanian ‘or Sale in India, Pakistan, Nepal, Bangladesh, Sri Lanka and Bhutan only IN| == Tata McGraw Hill Special Indian Edition 2009 Published in India by arrangement with the McGraw-Hill Companies, Inc., New York Sales Territories: India, Pakistan, Nepal, Bangladesh, Sri Lanka and Bhutan CAD/CAM: Theory and Practice Copvricht © 1991. by The McGraw-Hill Companies, Inc. All Rights reserved. No part of this publication Fifth reprint 2010 RAZCRRYZRABLR may be reproduced or distributed in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise or stored in a database or retrieval system without the prior written permission of The McGraw-Hill Companies. Inc. including, but not limited to, in any network or other electronic storage or transmission, or broadcast for distance learning. This edition can be exported from India only by the publishers, Tata McGraw Hill Education Private Limited ISBN (13): 978-0-07-015134-5 ISBN (10): 0-07-015134-2 Managing Director: Ajay Shukla General Manager: Publishing—SEM & Tech Ed: Vibha Mahajan Manager Sponsoring: Shalini Jha Sr. Editorial Executive: Surabhi Shukla Asst. Development Editor: Devshree Lohchab Executive —Editorial Services: Sohini Mukherjee Senior Production Manager: P L Pandita General Manager: Marketing—Higher Education: Michael J Cruz Sr. Product Manager: SEM & Tech Ed: Biju Ganesan General Manager—Production: Rajender P Ghansela Asst. General Manager—Production: B L Dogra Information contained in this work has been obtained by Tata McGraw Hill, from sources believed to be reliable. However, neither Tata McGraw Hill nor its authors guarantee the accuracy or completeness of any information published herein, and neither Tata McGraw Hill nor its authors shail be responsible for any errors, omissions, or damages arising out of use of this information. This work is published with the understanding that Tata McGraw Hill and its authors are supplying information but are not attempting to render engineering or other professional services. If such services are required, the assistance of an appropriate professional should be sought. ‘Typeset at Mukesh Technologies Pvt. Ltd., #10, 100 Feet Road, Ellapillaichavadi, Pondicherry 605 005 and printed at Adarsh Printers, C-50/51, Naveen Shahdara, Delhi 110 032 Cover: SDR Graw-Hill Contents Preface xvii 1 OVERVIEW OF CAD/CAM SYSTEMS L Introduction 3 LL_CAD/CAM Contents and Tools 3 1.2 History of CAD/CAM Development 8 L3.__CAD/CAM Market Trends 10 1.4 Definition of CAD/CAM Tools 14 1.5 Industrial Look at CAD/CAM 17 1.6 Book Approach 20 1.7 Book Organization 2/ Problems 22 Bibliography 24 2. CAD/CAM Hardware 25 2.1 Introduction 25 2.2 Types of Systems 27 2.2.1__Mainframe-Based Systems 28 2.2.2__Minicomputer-Based Systems 30 2.2.3 Microcomputer-Based Systems 32 2.2.4 Workstation-Based systems _34 2.3. CAD/CAM Systems Evaluation Criteria 35 2.3.1 System Considerations 36 2.3.2 Geometric Modeling Capabilities 37 2.3.3 Design Documentation 38 2.3.4 Application 38 24 Input Devices 38 2.4.1 Keyboards 40 2.4.2 Lightpens 42 2.4.3 Digitizing Tablets 44 2.4.4 Mouse Systems 46 Contents 2.4.5 Joysticks, Trackballs and Thumbwheels 47 2.4.6 OtherInput Devices 48 2.5 OutputDevices 49 2.5.1 Graphics Displays 49 2.5.2 Hardcopy Printers and Plotters 60 2.6 Hardware Integration and Networking 66 2.7 Programmable Logic Controllers(PLCs) 69 2.7.1 ElementofPLC 69 2.7.2 _ Hardware Configuration of PLC _70 2.7.3 PLCProgramming 7] 2.74 Advantages ofPLC 72 2.7.5 Comparison between PLC and Computers 72 2.8 Hardware Trends 73 Problems 82 Bibliography 85 3. CAD/CAM Software 3.1 Introduction 88 3.2 Graphics Standards 9/ Sch. “Dd: 94 3.3.2 Database 94 3.3.3 Database Management System (DBMS) 98 3.3.4 Database Coordinate System 100 3.3.5 Working Coordinate System 102 3.3.6 Screen Coordinate System 106 3.4 Modes of Graphics Operations 108 3.5 UserInterface 110 3.6 SoftwareModules 113 3.6.1 Operating System (OS) Module 1/3 3.6.2 GraphicsModule 113 3.6.3 Applications Module 114 3.6.4 ProgrammingModule 1/8 3.6.5 Communications Module 1/8 3.7 Modeling and Viewing 119 3.8 Software Documentation 123 3.9 Software Development _/23 3.10 Efficient Use of CAD/CAM Software 124 3.11 Software Trends 126 Problems 128 Bibliography 129 88 133 GEOMETRIC MODELING 4. Types and Mathematical Representations of Curves 4.1 Introduction 135 4.2 Wireframe Models 1.37 4.3, Wireframe Entities 139 4.4 CurveRepresentation 152 4.5 Parametric Represenation of AnalyticCurves 157 4.5.1 Review of Vector Algebra 158 4.5.2 Lines 160 45.3 Circles 168 4.5.4 Ellipses 176 4.5.5 Parabolas 184 4.5.6 Hyperbolas 188 4.5.7 Conics 189 4.6 Parametric Represenation of SyntheticCurves 193 4.6.1 Hermite Cubic Splines 195 4.6.2 BezierCurves 200 4.6.3 B-SplineCurves 207 4.6.4 RationalCurves 218 4.7 Curve Manipulations 219 4.7.1 Displaying 219 4.7.2 Evaluating Points on Curves. 219 4.7.3 Blending 220 4.7.4 Segmentation 222 4.75 Trimming 225 4.7.6 Intersection 225 4.1.7 Transformation 227 4.8 Design and Engineering Applications 227 Problems 234 Bibliography 239 5. Types and Mathematical Representations of Surfaces 5.1 Introduction 24] 5.2 Surface Models 243 5.3 Surface Entities 245 5.4 Surface Representation 252 5.5 Parametric Represenation of Analytic Surfaces 262 5.5.1 Plane Surface 262 5.5.2 Ruled Surface 266 5.5.3__Surface of Revolution 267 5.5.4 Tabulated Cylinder 268 5.6__ Parametric Representation of Synethetic Surfaces 269 135 241 Contents 3 ix 5.6.2 Bezier Surface 277 5.6.3. B-Spline Surface 282 5.6.4 Coons Surface 287 5.6.5 Blending Surface 29] 5.6.6 Offset Surface 292 5.6.7 Triangular Patches 293 5.6.8 Sculptured Surface 295 5.6.9 Rational Parametric Surface 295 5.7 Surface Manipulations 295 5.7.1 Displaying 295 5.7.2 Evaluating Points and Curves on Surfaces 296 5.7.3. Segmentation 296 5.7.4 Trimming 30] 5.7.5 Intersection 301 5.7.6 Projection 302 5.7.7 Transformation 304 5.8 Design and Engineering Applications 304 Problems 311 Bibliography 313 6. Types and Mathematical Representations of Solids 318 6.1 Introduction 318 6.2 SolidModels 320 6.3 SolidEntities 323 6.4 SolidRepresentation 328 6.5 Fundamentals of Solid Modeling 335 6.5.1 SetTheory 335 6.5.2 Regularized Set Operations 340 6.5.3. Set Membership Classification 343 6.6 Half-spaces 346 6.6.1 BasicElements 347 6.6.2 Building Operations 348 6.6.3 Remarks 35] 6.7__ Boundary Represenation(B-rep) 357 621 Basic Elements 353 6.7.2 Building Operations 360 6.7.3 Remarks _370 6.8 Constructive Solid Geometry (CSG) 371 6.8.1 BasicElements 380 6.8.2 Building Operations 390 6.8.3 Remarks 398 6.9 Sweep Representation 398 6.9.1 BasicElements 400 6.9.2 Building Operations 400 6.9.3 Remarks 40] x & Contents 6.10 Analytical Solid Modeling (ASM) 401 6.10.1 BasicElements 402 6.10.2 Building Operations 406 6.10.3 Remarks 407 6.11 Other Representations 407 6.12 Organization of Solid Modelers 409 6.13 Solid Manipulations 41] 6.13.1 Displaying 4/2 6.13.2 Evaluating Points, Curves and Surfaces on Solids 412 6.13.3 Segmentation 4/3 6.13.4 Trimming and Intersection 413 6.13.5 Transformation 41/3 6.13.6 Editing 413 6.14 Solid Modeling-Based Applications 414 6.15 Design and Engineering Applications 414 Problems 418 Bibliography 421 7. CAD/CAM Data Exchange 425 7.1 Introduction 425 7.2. Evolution of DataExchange Format 429 7.2.1 Shape-Based Format 430 7.2.2 Product Data-Based Format 432 7.2.3 ISOStandard 433 7.3 IGES 434 7.3.1 Description 435 7.3.2 DataRepresentation 438 7.3.3 File Structure and Format 444 7.3.4 Processors 448 7.3.5 Remarks 455 74 PDES 455 7.4.1 Description 456 7.4.2 DataRepresentation 460 74.3 Remarks 460 Problems 460 Bibliography 461 TWO- AND THREE-DIMENSIONAL GRAPHICS CONCEPTS 8. Geometric Transformations 465 8.1 Introduction 465 8.2 Transformations of Geometric Models 466 Contents xi 8.2.1 Translation 467 8.2.2 Scaling 469 8.2.3. Reflection 47] 8.2.4 Rotation 474 8.2.5 Homogeneous Representation 483 8.2.6 Concatenated Transformations 486 8.3. Mappings of Geometric Models 488 8.3.1 Translationai Mapping 489 8.3.2 Rotational Mapping 489 8.3.3. General Mapping 49] 8.3.4 Mappings as Changes of Coordinate System 492 8.4 Inverse Transformations and Mappings 496 8.5 Projections of Geometric Models 499 8.5.1 Orthographic Projections 502 8.5.2 Perspective Projections 505 8.6 Design and Engineering Applications 506 Problems 507 Bibliography 511 9. Visual Realism 512 9.1 Introduction 5/2 9.2 ModelClean-Up 515 9.3. Hidden Line Removal 517 9.3.1 Visibility of Object Views 519 9.3.2 Visibility Techniques 520 9.3.3 Sorting 528 9.3.4 Coherence 529 9.3.5 Formulation and Implementation 529 9.3.6 Sample Hidden Line Algorithms 531 9.3.7 Hidden Line Removal for Curved Surfaces 537 9.4 Hidden Surface Removal 537 9.4.1 Thez-Buffer Algorithm 538 9.4.2 Warnock’s Algorithm 538 9.5 Hidden SolidRemoval 539 9.5.1. Ray-Tracing Algorithm 540 9.6 Shading 550 9.6.1 Shading Models 551 9.6.2 Shading Surfaces 554 9.6.3 Shading Enhancements 557 9.6.4 Shading Solids 560 9.7 Coloring 565 9.7.1 ColorModels 566 9.8 User Interface for Shading and Coloring 569 Problems 573 Bibliography 576 xii. Contents 579 10. Graphics Aids 581 10.1 Introduction 581 10.2 Geometric Modifiers 582 10.3 Names 584 10.4 Layers 585 10.5 Colors 587 10.6 Grids 588 10.7 Groups 590 10.8 Dragging and Rubberbanding 590 10.9 Clipping 59] Problems 592 Bibliography 594 11. Graphics Manipulations and Editings 596 11.1 Introduction 596 11.2 Entity Selection Methods 597 11.2.1 Individual Entity 597 11.2.2 All Displayed Entities 597 11.2.3 Groups 598 11.2.4 Enclosing Polygonor Window 598 11.2.5 Chaining Contiguous Entities 598 11.2.6 Width 598 11.3 Manipulation Operations 600 11.3.1 Verification of Model and Database Parameters 600 11.3.2 Entity Verification 600 11.3.3 Entity Copying (Duplication) 600 11.3.4 Geometric Arrays 601 11.3.5 Transformation 603 11.3.6 Entity Blanking/Unblanking 605 11.3.7 Geometric Measurements 606 11.3.8 Entity Offsetting 608 11.4 Editing Operations 609 11.4.1 Entity Trimming 608 11.4.2 Entity Division 6/0 11.4.3 Entity Stretching 6/1 11.4.4 Entity Editing 612 11.5 Design and Engineering Applications 6/2 Problems 615 Bibliography 616 Contents 12. Finite Element Modeling and Analysis 12.1 Introduction 6/7 12.2 General Procedure of the Finite Element Method 619 12.3 Finite Element Analysis 621 12.3.1 Development of Integral Equations 622 12.3.2 Method of Weighted Residuals 63/ 12.3.3 Continuum Discretization 634 12.3.4 Assembly of Element Equations 653 12.3.5. Imposing Boundary Conditions 657 12.3.6 Lumping External Applied Loads 658 12.3.7. Solution of Global Equations 658 12.3.8 Other Finite Element Analyses 659 12.3.9 Convergence of Finite Element Solutions 660 12.4 Isoparametric Evaluation of Element Matrices 661 12.4.1 Element Mapping 661 12.4.2 Shape Functions by Inspection 663 12.43 Evaluation of Element Matrices 665 12.5 Finite Element Modeling 669 12.6 Mesh Generation 670 12.6.1 Mesh Requirements 671 12.6.2 Semi-Automatic Methods 673 12.6.3. Fully Automatic Methods 68/ 12.7 Design and Engineering Applications 688 Problems 691 Bibliography 695 13. Part Programming and Manufacturing 13.1 Introduction 699 13.2 Part Production Cycle 700 13.3 Manufacturing Systems 702 13.4 Manufacturing Processes 704 13.4.1 Removing Processes 705 13.4.2. Forming Processes 706 13.4.3 Deforming Processes 706 13.4.4 Joining Processes 707 13.5 Integration Requirements 708 13.6 Process Planning 711 13.6.1 Manual Approach 7/2 13.6.2 Variant Approach 720 13.6.3 Generative Approach 722 13.6.4 Hybrid Approach 724 13.6.5 Geometric Modeling for Process Planning 724 617 699

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