INTRODUCTION TO COMPUTER NUMERICAL CONTROL (CNC)

Transcription

1 INTRODUCTION TO COMPUTER NUMERICAL CONTROL (CNC) FOURTH EDITION James Y.Valentino Joseph Goldenberg PEARSON Prentice Hall Upper Saddle River, New Jersey Columbus, Ohio

2 CONTENTS CHAPTER I Introduction to Computer Numerical Control Manufacturing I I Chapter Objectives I 1 2 Introduction I 1 3 Numerical Control Definition, Its Concepts and Advantages I 1-4 Definition of Computer Numerical Control and Its Components 1-5 Advantages of CNC Compared with NC Special Requirements for Utilizing CNC Financial Rewards of CNC Investment CNC Machining Centers and Turning Centers Other Types of CNC Equipment 8 I 10 CNC Input and Storage Media 8 I-11 Chapter Summary II CHAPTER 1 Modern Machine Tool Controls Chapter Objectives Introduction Different Types of System Control Loop Systems for Controlling Tool Movement Establishing Locations via Cartesian Coordinates CNC Machine Axes of Motion Types oftool Positioning Modes Units Used for Positioning Coordinates Chapter Summary 25 CHAPTER 3 Too/ing for Hole and Milling Operations Chapter Objectives Introduction Tooling for Drilling Operations 32 XI

3 xii Contents 3 4 Carbide Insert Technology Tooling for Hole Operations That Follow Drilling Tool Speeds and Feeds for Hole Operations Tooling for Profile Milling and Facing Operations Coated Tooling Tool Speeds and Feeds for Milling Operations Feed Directions for Milling Operations Cutting Fluids for CNC Operations Chapter Summary 54 CHAPTER 4 Exploring Features of CNC Machining Centers Chapter Objectives Introduction Background on CNC Machining Centers Tooling Systems Used with Automatic Tool Changers Methods of Securing Tools in Tool Holders Methods of Securing Tooling Systems to the CNC Spindle Automatic Tool Changer Systems Pallet Loading Systems Features of the Machine Control Unit (MCU) Machining Centers Chapter Summary 77 CHAPTERS Review of Basic Blueprint Reading 80 for CNC Programmers 5-1 Chapter Objectives Introduction Sheet Sizes Drawing Formats Interpreting Lines in Drawings Projection Conventions Used in Drawings Visualizing 3D Objects from 2D Othographic Views Auxiliary Views Sectional Views Reading Dimensions Reading Threads and Thread Notes Reading Surface Finish Symbols and Notes Chapter Summary 131 Bibliography

4 Contents xiii CHAPTER 6 Review of Basic Material Specifications 133 for CNC Programmers 6-1 Chapter Objectives Introduction Reading Material Specifications Understanding Heat Treatment Notes Interpreting Surface Coating Notes Chapter Summary 150 Bibliography CHAPTER 7 Review of Basic Geometric Dimensioning 151 and Tolerancing for CNC Programmers 7-1 Chapter Objectives Introduction GDTTerminology Part Form Controls Datums Part Profile Controls Part Location, Orientation, and Runout Controls Chapter Summary 166 < Bibliography CHAPTER 8 Mathematics for CNC Programming Chapter Objectives Introduction Determining Sides of Right Triangles Useful Angle Concepts Determining Angles of Right Triangles Oblique Triangles KwikTrig Trigonometry/Geometry Software Installation Starting KwikTrig Chapter Summary 178 CHAPTER 9 An Overview of CNC Shop Activities Chapter Objectives Introduction 182

5 xiv Contents 9-3 Essential CNC Shop Activities Part Drawing Study Methodizing of Operations for CNC Machining Centers Deciding on a CNC Machine Methods of Holding the Part During Machining Machining Determination Cutting Conditions Writing a Programming Manuscript Inputting Programs to the Machine Control Unit Setup Procedure Debugging and Verifying the Program Part Production Chapter Summary 201 CHAPTER 10 Word Address Programming Chapter Objectives Introduction Programming Language Format Programming Language Terminology Arrangement of Addresses in a Block Program and Sequence Numbers (O, N Codes) Preparatory Functions (G Codes) Dimension Words (X.Y.Z... Codes) Feed Rate (F Code) Spindle Speed (S Code) Miscellaneous Machine Functions (M Codes) Automatic Tool Changing (M6 Code) Tool Length Offset and Cutter Radius Compensation (H, D Codes) Comments Chapter Summary 213 CHAPTER I I Running the Mill Simulator I Chapter Objectives Introduction Predator Simulation Software System Requirements Conventions Used in This Chapter Installation Running a Mill Simulation Job Stored on CD Using the Virtual CNC to Inspect the Machined Part 221

6 Contents xv CHAPTER 12 Programming Hole Operations Chapter Objectives Introduction Fixed or Canned Cycles Hole Operation Commands Writing a Hole Operation Program Chapter Summary 240 CHAPTER I 3 Programming Linear Profiles Chapter Objectives Introduction Linear Interpolation Commands Writing a Linear Profiling Program Determining Cutter Offsets for Inclined Line Profiles Chapter Summary 268 CHAPTER 14 Programming Circular Profiles Chapter Objectives 275 ' 14-2 Introduction Specifying the Plane for Circular Arc Interpolation Circular Interpolation Commands Circular Interpolation via Direct Radius Specification Profiling at Constant Feed Rate Determining Cutter Offsets for Line-Arc Profiles Chapter Summary 297 CHAPTER I 5 Programming with Cutter Diameter Compensation Chapter Objectives Introduction Cutter Diameter Compensation Advantages of Using Cutter Diameter Compensation Some Restrictions with Cutter Diameter Compensation Cutter Diameter Compensation Commands Cutter Diameter Compensation with Z-Axis Movement Cutter Diameter Compensation Interruptions Chapter Summary 327

7 xvi Contents CHAPTER 16 Programming with Subprograms Chapter Objectives Introduction Subprogram Concept Fanuc Commands for Calling a Subprogram and Returning to the Main Program Additional Subprogram Control Features General Rules for Subprogramming Chapter Summary 355 CHAPTER 17 Introduction to the CNC Lathe Chapter Objectives Introduction Backround on the CNC Lathe CNC Lathe Axes of Motion Features of the Machine Control Unit (MCU) Lathes Basic Lathe Operations Tooling for CNC Lathe Operations Tool Speeds, Feeds, and Depth of Cut for Lathe Operations Feed Directions and Rake Angles for Lathe Operations Chapter Summary 385 CHAPTER 18 Running the Lathe Simulator Chapter Objectives Introduction Running a Lathe Simulation Job Stored on CD Using the Virtual CNC to Inspect the Machined Part 393 CHAPTER 19 Fundamental Concepts of CNC Lathe Programming Chapter Objectives Introduction Establishing Locations via Cartesian Coordinates (CNC Lathes) Types of Tool Positioning Modes (CNC Lathes) 397

8 Contents xvii 19-5 Reference Point, Machine Origin, and Program Origin (FANUC Controllers) Methodizing of Operations for CNC Lathes Setup Procedures for CNC Lathes Important Preparatory Functions (G Codes) for Lathes Important Miscellaneous Functions (M Codes) for Lathes Setting the Machining Origin Feed Rate (F Code) Spindle Speed (S Code) Spindle Speed with Constant Surface Speed Control Spindle Speed with Clamp Speed and Constant Surface Speed Controls Automatic Tool Changing Tool Edge Programming Tool Nose Radius Compensation Programming Setting Up Tool Nose Radius Compensation Some Restrictions with Tool Nose Radius Compensation Tool Nose Radius Compensation Commands Linear Interpolation Commands (CNC Lathes) Circular Interpolation Commands (CNC Lathes) Grooving Commands Return to Reference Point Command Chapter Summary 432 CHAPTER 20 Techniques and Fixed Cycles for 440 CNC Lathe Programming 20-1 Chapter Objectives Introduction Turning and Boring Cycle: G Facing Cycle: G Multiple Repetitive Cycles: G70 to G Stock Removal in Turning and Boring Cycle: G Finish Turning and Boring Cycle: G Peck Drilling and Face Grooving Cycle: G Peck Cutoff and Grooving Cycle: G Thread Cutting on CNC Lathes and Turning Centers Single-Pass Threading Cycle: G Multiple-Pass Threading Cycle: G Multiple Repetitive Threading Cycle: G Chapter Summary 478

9 xviii Contents CHAPTER 21 Modern Computer-Aided Part Programming Chapter Objectives Introduction Modern Developments in the Process of CNC Programming Using an Off-Line Computer to Write and Store Part Programs An Introduction to Computer-Aided Programming Languages Basic Elements of the APT Programming Language An Introduction to CAD/CAM Technology The Elements Comprising CAD The Elements Comprising CAM Creating a Complete Part Program Using Mastercam CNC Software Chapter Summary 515 Appendix A 517 Important Safety Precautions 5 / 7 Appendix B 519 Summary of G Codes for Milling Operations (FANUC Controllers) 519 Summary of G Codes for Turning Operations (FANUC Controllers) 521 Summary of M Codes for Milling and Turning Operations (FANUC Controllers) 522 Summary of Auxiliary Functions (FANUC Controllers) 523 Appendix C 526 Recommended Speeds and Feeds for Drilling 526 Recommended Speeds and Feeds for Milling 527 Recommended Speeds and Feeds for Turning 528 Appendix O 530 Summary of Important Machining Formulas 530 Appendix E 532 Tables of Important GDT Symbols 532 Appendix F 534 Identification System for OD and ID Tools 534

10 Contents xix Appendix G 537 Writing and Verifying Mill Part Programs via Predator Simulations Software 537 Appendix H 552 Writing and Verifying Turn Part Programs via Predator Simulation Software 552 Glossary 568 Index 575