DIRECT GEAR DESIGN BY ALEXANDER L. KAPELEVICH

DIRECT GEAR DESIGN BY ALEXANDER L. KAPELEVICH

Contents:

1 Historical Overview

2 Macrogeometry of Involute Gears

3 Area of Existence of Involute Gears

4 Involute Gearing Limits

5 Tooth Geometry Optimization

6 Gear Design Details

7 Tolerancing and Tolerance Analysis.

8 Gear Fabrication Technologies and Tooling

9 Gear Measurement

10 Comparison of Traditional and Direct Gear Design

11 Implementation Examples

Preface:

Gears and gear drives have been known and used for millennia as critical components of mechanisms and machines. Over the last several decades the development of gearing has mostly focused in the following fields: the improving of material, manufacturing technology and tooling, thermal treatment, tooth surface engineering and coatings, tribology and lubricants, testing technology and diagnostics. Constant demand for high-performance gear transmissions has resulted in significant progress in gear tooth microgeometry, which defines deviation from the nominal involute surface to achieve the optimal tooth contact localization for higher load capacity and lower transmission error. However, the development of gear macro geometry (the defining of the tooth shape and dimensional proportions) and gear design methods is traditionally based on the preselected instrumental generating rack and has remained frozen in time. The vast majority of gears are designed with the standard 20° pressure angle tooth proportions. For some demanding applications, like aerospace and automotive industries, the standard tooth proportions are altered to provide a higher transmission load capacity. Nevertheless, even for these applications the gear design methodol ogy has not evolved for many years.This book introduces an alternate gear design approach called Direct Gear Design®. Developed over the past thirty years, it has been implemented in custom gear applications to maximize gear drive performance. Some segments of this book were published in technical magazines and presented at gear conferences. The successful implementations of this method, and the positive responses generated by the magazine publications and gear confer ence presentations, motivated me to write this book and share this knowl edge and experience with the gear engineering community. In this book the Direct Gear Design method is presented as another engineering tool that can be beneficial for many gear drives. I tried to avoid general conclusions and recommendations, realizing that in custom gearing one solution can be ben eficial for certain types of applications but could be completely unacceptable for others. For practical purposes and to facilitate the understanding of the Direct Gear Design method for gear engineers, I used the same established standard gear nomenclature and specification as much as possible. This book is written by an engineer, for engineers to show a beneficial alternative to the traditional way of gear design. I hope that it will expand the readers’ perspective on the opportunity for further gear transmission improvements and inspire them to be open-minded in solving their practical gear design tasks.

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