P1: GDZ/SPH P2: GDZ CB672/Litvin-Sample-DVR CB672/Litvin CB672/Litvin-v2.cls April 20, 2004 10:8 ii This page intentionally left blank P1: GDZ/SPH P2: GDZ CB672/Litvin-Sample-DVR CB672/Litvin CB672/Litvin-v2.cls April 20, 2004 10:8 GEAR GEOMETRY AND APPLIED THEORY Second Edition Revised and expanded, Gear Geometry and Applied Theory, 2nd edition, cov- ers the theory, design, geometry, and manufacture of all types of gears and gear drives. Gear Geometry and Applied Theory is an invaluable reference for de- signers, theoreticians, students, and manufacturers. This new edition includes advances in gear theory, gear manufacturing, and computer simulation. Among the new topics are (1) new geometry for modified spur and helical gears, face-gear drives, and cycloidal pumps; (2) new design approaches for one-stage planetary gear trains and spiral bevel gear drives; (3) an enhanced approach for stress analysis of gear drives with FEM; (4) new methods of grinding face-gear drives, generating double-crowned pinions, and generating new types of helical gears; (5) broad application of simulation of meshing and TCA; and (6) new theories on the simulation of meshing for multi-body systems, detection of cases wherein the contact lines on generating surfaces may have their own envelope, and detection and avoidance of singularities of generated surfaces. Faydor L. Litvin is Director of the Gear Research Center and Distinguished Professor Emeritus in the Department of Mechanical and Industrial Engineering, University of Illinois at Chicago. He holds patents for twenty-five inventions, and he was recognized as Inventor of the Year by the University of Illinois at Chicago in 2001. Alfonso Fuentes is Associate Professor of Mechanical Engineering at the Polytechnic University of Cartagena. i P1: GDZ/SPH P2: GDZ CB672/Litvin-Sample-DVR CB672/Litvin CB672/Litvin-v2.cls April 20, 2004 10:8 ii P1: GDZ/SPH P2: GDZ CB672/Litvin-Sample-DVR CB672/Litvin CB672/Litvin-v2.cls April 20, 2004 10:8 Gear Geometry and Applied Theory SECOND EDITION Faydor L. Litvin University of Illinois at Chicago Alfonso Fuentes Polytechnic University of Cartagena iii    Cambridge, New York, Melbourne, Madrid, Cape Town, Singapore, São Paulo Cambridge University Press The Edinburgh Building, Cambridge  , UK First published in print format - ---- - ---- © Faydor L. Litvin and Alfonso Fuentes 2004 2004 Information on this title: www.cambrid g e.or g /9780521815178 This publication is in copyright. Subject to statutory exception and to the provision of relevant collective licensing agreements, no reproduction of any part may take place without the written permission of Cambridge University Press. - --- - --- Cambridge University Press has no responsibility for the persistence or accuracy of s for external or third-party internet websites referred to in this publication, and does not guarantee that any content on such websites is, or will remain, accurate or appropriate. Published in the United States of America by Cambridge University Press, New York www.cambridge.org hardback eBook (EBL) eBook (EBL) hardback    Cambridge, New York, Melbourne, Madrid, Cape Town, Singapore, São Paulo Cambridge University Press The Edinburgh Building, Cambridge  , UK First published in print format - ---- - ---- © Faydor L. Litvin and Alfonso Fuentes 2004 2004 Information on this title: www.cambrid g e.or g /9780521815178 This publication is in copyright. Subject to statutory exception and to the provision of relevant collective licensing agreements, no reproduction of any part may take place without the written permission of Cambridge University Press. - --- - --- Cambridge University Press has no responsibility for the persistence or accuracy of s for external or third-party internet websites referred to in this publication, and does not guarantee that any content on such websites is, or will remain, accurate or appropriate. Published in the United States of America by Cambridge University Press, New York www.cambridge.org hardback eBook (EBL) eBook (EBL) hardback P1: GDZ/SPH P2: GDZ CB672/Litvin-Sample-DVR CB672/Litvin CB672/Litvin-v2.cls April 20, 2004 10:8 Contents Foreword by Graziano Curti page xii Preface xiv Acknowledgments xv 1 Coordinate Transformation 1 1.1 Homogeneous Coordinates 1 1.2 Coordinate Transformation in Matrix Representation 2 1.3 Rotation About an Axis 6 1.4 Rotational and Translational 4 ×4 Matrices 14 1.5 Examples of Coordinate Transformation 15 1.6 Application to Derivation of Curves 24 1.7 Application to Derivation of Surfaces 28 2 Relative Velocity 33 2.1 Vector Representation 33 2.2 Matrix Representation 39 2.3 Application of Skew-Symmetric Matrices 41 3 Centrodes, Axodes, and Operating Pitch Surfaces 44 3.1 The Concept of Centrodes 44 3.2 Pitch Circle 49 3.3 Operating Pitch Circles 50 3.4 Axodes in Rotation Between Intersected Axes 51 3.5 Axodes in Rotation Between Crossed Axes 52 3.6 Operating Pitch Surfaces for Gears with Crossed Axes 56 4 Planar Curves 59 4.1 Parametric Representation 59 4.2 Representation by Implicit Function 60 4.3 Tangent and Normal to a Planar Curve 60 4.4 Curvature of Planar Curves 68 5 Surfaces 78 5.1 Parametric Representation of Surfaces 78 5.2 Curvilinear Coordinates 78 5.3 Tangent Plane and Surface Normal 79 v P1: GDZ/SPH P2: GDZ CB672/Litvin-Sample-DVR CB672/Litvin CB672/Litvin-v2.cls April 20, 2004 10:8 vi Contents 5.4 Representation of a Surface by Implicit Function 82 5.5 Examples of Surfaces 82 6 Conjugated Surfaces and Curves 97 6.1 Envelope to a Family of Surfaces: Necessary Conditions of Existence 97 6.2 Basic Kinematic Relations 102 6.3 Conditions of Nonundercutting 103 6.4 Sufficient Conditions for Existence of an Envelope to a Family of Surfaces 107 6.5 Contact Lines; Surface of Action 110 6.6 Envelope to Family of Contact Lines on Generating Surface  1 112 6.7 Formation of Branches of Envelope to Parametric Families of Surfaces and Curves 114 6.8 Wildhaber’s Concept of Limit Contact Normal 118 6.9 Fillet Generation 119 6.10 Two-Parameter Enveloping 124 6.11 Axes of Meshing 128 6.12 Knots of Meshing 134 6.13 Problems 137 7 Curvatures of Surfaces and Curves 153 7.1 Introduction 153 7.2 Spatial Curve in 3D-Space 153 7.3 Surface Curves 164 7.4 First and Second Fundamental Forms 175 7.5 Principal Directions and Curvatures 180 7.6 Euler’s Equation 188 7.7 Gaussian Curvature; Three Types of Surface Points 189 7.8 Dupin’s Indicatrix 193 7.9 Geodesic Line; Surface Torsion 194 8 Mating Surfaces: Curvature Relations, Contact Ellipse 202 8.1 Introduction 202 8.2 Basic Equations 203 8.3 Planar Gearing: Relation Between Curvatures 204 8.4 Direct Relations Between Principal Curvatures of Mating Surfaces 218 8.5 Direct Relations Between Normal Curvatures of Mating Surfaces 226 8.6 Diagonalization of Curvature Matrix 231 8.7 Contact Ellipse 234 9 Computerized Simulation of Meshing and Contact 241 9.1 Introduction 241 9.2 Predesign of a Parabolic Function of Transmission Errors 242 9.3 Local Synthesis 245 P1: GDZ/SPH P2: GDZ CB672/Litvin-Sample-DVR CB672/Litvin CB672/Litvin-v2.cls April 20, 2004 10:8 Contents vii 9.4 Tooth Contact Analysis 249 9.5 Application of Finite Element Analysis for Design of Gear Drives 257 9.6 Edge Contact 260 10 Spur Involute Gears 267 10.1 Introduction 267 10.2 Geometry of Involute Curves 268 10.3 Generation of Involute Curves by Tools 273 10.4 Tooth Element Proportions 278 10.5 Meshing of Involute Gear with Rack-Cutter 280 10.6 Relations Between Tooth Thicknesses Measured on Various Circles 285 10.7 Meshing of External Involute Gears 287 10.8 Contact Ratio 292 10.9 Nonstandard Gears 294 11 Internal Involute Gears 304 11.1 Introduction 304 11.2 Generation of Gear Fillet 305 11.3 Conditions of Nonundercutting 309 11.4 Interference by Assembly 314 12 Noncircular Gears 318 12.1 Introduction 318 12.2 Centrodes of Noncircular Gears 318 12.3 Closed Centrodes 323 12.4 Elliptical and Modified Elliptical Gears 326 12.5 Conditions of Centrode Convexity 329 12.6 Conjugation of an Eccentric Circular Gear with a Noncircular Gear 330 12.7 Identical Centrodes 331 12.8 Design of Combined Noncircular Gear Mechanism 333 12.9 Generation Based on Application of Noncircular Master-Gears 335 12.10 Enveloping Method for Generation 336 12.11 Evolute of Tooth Profiles 341 12.12 Pressure Angle 344 Appendix 12.A: Displacement Functions for Generation by Rack-Cutter 345 Appendix 12.B: Displacement Functions for Generation by Shaper 348 13 Cycloidal Gearing 350 13.1 Introduction 350 13.2 Generation of Cycloidal Curves 350 13.3 Equations of Cycloidal Curves 354 13.4 Camus’ Theorem and Its Application 355 13.5 External Pin Gearing 359 13.6 Internal Pin Gearing 365 P1: GDZ/SPH P2: GDZ CB672/Litvin-Sample-DVR CB672/Litvin CB672/Litvin-v2.cls April 20, 2004 10:8 viii Contents 13.7 Overcentrode Cycloidal Gearing 367 13.8 Root’s Blower 369 14 Involute Helical Gears with Parallel Axes 375 14.1 Introduction 375 14.2 General Considerations 375 14.3 Screw Involute Surface 377 14.4 Meshing of a Helical Gear with a Rack 382 14.5 Meshing of Mating Helical Gears 392 14.6 Conditions of Nonundercutting 396 14.7 Contact Ratio 398 14.8 Force Transmission 399 14.9 Results of Tooth Contact Analysis (TCA) 402 14.10 Nomenclature 403 15 Modified Involute Gears 404 15.1 Introduction 404 15.2 Axodes of Helical Gears and Rack-Cutters 407 15.3 Profile-Crowned Pinion and Gear Tooth Surfaces 411 15.4 Tooth Contact Analysis (TCA) of Profile-Crowned Pinion and Gear Tooth Surfaces 414 15.5 Longitudinal Crowning of Pinion by a Plunging Disk 419 15.6 Grinding of Double-Crowned Pinion by a Worm 424 15.7 TCA of Gear Drive with Double-Crowned Pinion 430 15.8 Undercutting and Pointing 432 15.9 Stress Analysis 435 16 Involute Helical Gears with Crossed Axes 441 16.1 Introduction 441 16.2 Analysis and Simulation of Meshing of Helical Gears 443 16.3 Simulation of Meshing of Crossed Helical Gears 452 16.4 Generation of Conjugated Tooth Surfaces of Crossed Helical Gears 455 16.5 Design of Crossed Helical Gears 458 16.6 Stress Analysis 465 Appendix 16.A: Derivation of Shortest Center Distance for Canonical Design 467 Appendix 16.B: Derivation of Equation of Canonical Design f (γ o ,α on ,λ b1 ,λ b2 ) = 0 472 Appendix 16.C: Relations Between Parameters α pt and α pn 473 Appendix 16.D: Derivation of Equation (16.5.5) 473 Appendix 16.E: Derivation of Additional Relations Between α ot1 and α ot2 474 17 New Version of Novikov–Wildhaber Helical Gears 475 17.1 Introduction 475 17.2 Axodes of Helical Gears and Rack-Cutter 478 17.3 Parabolic Rack-Cutters 479 17.4 Profile-Crowned Pinion and Gear Tooth Surfaces 482 [...]... 597 601 19 Worm -Gear Drives with Cylindrical Worms 19.1 Introduction 19.2 Pitch Surfaces and Gear Ratio 19.3 Design Parameters and Their Relations 19.4 Generation and Geometry of ZA Worms 19.5 Generation and Geometry of ZN Worms 19.6 Generation and Geometry of ZI (Involute) Worms 19.7 Geometry and Generation of K Worms 19.8 Geometry and Generation of F-I Worms (Version I) 19.9 Geometry and Generation... revised and substantially augmented in comparison with the first edition of 1994 New topics in the second edition include the following new developments: (1) A new geometry of modified spur gears, helical gears with parallel and crossed axes, a new version of Novikov–Wildhaber helical gears, a new geometry of facegear drives, geometry of cycloidal pumps, a new approach for design of one-stage planetary gear. .. order to detect and avoid areas of severe contact stresses (3) Improved conditions of load distribution in planetary gear trains by modification of the applied geometry and regulation of installment of planet gears on the carrier New approaches are presented for gear manufacture that enable (i) grinding of facegear drives by application of a grinding worm of a special shape and (ii) design and manufacture... Equations of Face -Gear Tooth Surface 18.6 Conditions of Nonundercutting of Face -Gear Tooth Surface (Generated by Involute Shaper) 18.7 Pointing of Face -Gear Teeth Generated by Involute Shaper 18.8 Fillet Surface 18.9 Geometry of Parabolic Rack-Cutters 18.10 Second Version of Geometry: Derivation of Tooth Surfaces of Shaper and Pinion 18.11 Second Version of Geometry: Derivation of Face -Gear Tooth Surface... version of Wildhaber–Novikov helical gear drives, spiral bevel gears, and worm -gear drives Computerized simulation of meshing and contact and testing of prototypes of gear drives have confirmed the effectiveness of the ideas presented in the book Three patents for new manufacturing approaches have been obtained by Professor Faydor L Litvin and representatives of gear companies The main ideas in the... States, Italy, Spain, and Japan in gear research The publication of this book will certainly enhance the education and training of engineers in the area of gear theory and design of gear transmissions Prof Eng Graziano Curti Politecnico di Torino, Italy P1: GDZ/SPH P2: GDZ CB672/Litvin-Sample-DVR CB672/Litvin CB672/Litvin-v2.cls April 20, 2004 10:8 Preface The contents of the second edition of the book... the theory of gearing, computerized design, generation, simulation of meshing, and stress analysis of gear drives The first edition of the book is already considered the leading reference in the field by the engineering community, but this edition complements the first with new chapters and thoughtful revision of the previous version, which will make it very useful for the design and manufacture of gear. .. manufacture of gear drives New ideas of gear design presented in the book include: (1) Development of gear drives with improved bearing contact, reduced sensitivity to misalignment, and reduced transmission errors and vibration These goals are achieved by (i) simultaneous application of local synthesis of gear drives and computerized simulation of meshing and contact and (ii) application of a predesigned... Lines 20.6 Worm -Gear Surface Equations 622 622 21 Spiral Bevel Gears 21.1 Introduction 21.2 Basic Ideas of the Developed Approach 21.3 Derivation of Gear Tooth Surfaces 21.4 Derivation of Pinion Tooth Surface 21.5 Local Synthesis and Determination of Pinion Machine-Tool Settings 21.6 Relationships Between Principal Curvatures and Directions of Mating Surfaces 21.7 Simulation of Meshing and Contact 21.8... Design of Spiral Bevel Gear Drives 21.9 Example of Design and Optimization of a Spiral Bevel Gear Drive 21.10 Compensation of the Shift of the Bearing Contact 627 627 628 633 644 22 Hypoid Gear Drives 22.1 Introduction 22.2 Axodes and Operating Pitch Cones 22.3 Tangency of Hypoid Pitch Cones 22.4 Auxiliary Equations 22.5 Design of Hypoid Pitch Cones 22.6 Generation of Face-Milled Hypoid Gear Drives 679 679 . 10:8 GEAR GEOMETRY AND APPLIED THEORY Second Edition Revised and expanded, Gear Geometry and Applied Theory, 2nd edition, cov- ers the theory, design, geometry, and manufacture of all types of gears. gears and gear drives. Gear Geometry and Applied Theory is an invaluable reference for de- signers, theoreticians, students, and manufacturers. This new edition includes advances in gear theory, gear. Worms 557 19.5 Generation and Geometry of ZN Worms 561 19.6 Generation and Geometry of ZI (Involute) Worms 574 19.7 Geometry and Generation of K Worms 581 19.8 Geometry and Generation of F-I Worms