Advanced Gear Manufacturing and Finishing

Classical and Modern Processes

Kapil Gupta, Neelesh Kumar Jain, Rolf Laubscher

• Publisher: Academic Press
• Year: 2017
• Print ISBN: 9780128044605
• eBook ISBN: 9780128045060
• Topic: Technology & Engineering
• Subtopic: Mechanical Engineering
• Index: Technology & Engineering

Advanced Gear Manufacturing and Finishing offers detailed coverage of advanced manufacturing technologies used in the production of gears, including new methods such as spark erosion machining, abrasive water jet machining, additive layer manufacturing, laser shaping, and sustainable manufacturing of gears.The industry in this area is constantly producing new settings where gears must endure ever increasing stresses, strains, and temperatures. Advanced methods in manufacturing, finishing, and surface property enhancement have emerged in recent years to meet these challenges.This unique book takes a critical look at the state-of-the-art research into these new methods, and the latest improvements to classic technologies in both gear manufacturing and finishing. This book is essential reading for researchers and engineers working in the fields of powertrain manufacturing, gear technology, and advanced manufacturing technologies.- Describes the machining systems, main components, and working procedures with the help of diagrams and photos.- Demonstrates the mechanisms and capabilities of new methods.- Shows improvements to a range of gear manufacturing and finishing technologies.- Provides a critical review of recent research in a range of fields relevant to gear manufacturing technologies.

Chapter 1

Introduction to Gear Engineering

Abstract

Gears are basic mechanical components used to transmit motion and/or power and are responsible for the smooth functioning of a significant number of machines, instruments, and equipments employed in most major industrial, scientific, and domestic applications. The purpose of this chapter is to present a basic introduction to gears, their use, and manufacture. The chapter commences with an introduction to gears along with a brief history. A classification scheme is then presented based on the gear-shaft axis orientation and corresponding gear types with their unique features and applications. The applicable gear terminology and nomenclature along with the most important gear materials, their properties, and application areas are presented next. The chapter is concluded with a brief introduction into gear manufacture comprising both conventional and advanced types along with the relevant finishing processes.

Keywords

Bevel gear; involute; gear hobbing; noncircular gear; spline; spur gear; worm wheel

1.1 Introduction and History of Gears

1.1.1 Introduction

A gear is basically a toothed wheel that works in tandem with another gear (or gears) to transmit power and/or motion to change speed and/or direction of motion. Dudley defined a gear as “a geometric shape that has teeth uniformly spaced around the circumference and is made to mesh its teeth with another gear” [1]. Slipping is a major problem during transmission of motion and power between two shafts by rope or belt drive and consequently may affect the precision and efficiency of the system adversely. This slipping phenomenon is largely avoided by means of gear drives. The compact layout, flexibility, high efficiency, and reliability are the most important features that make gears and gear drives the first choice in many applications. Gear sizes range from nanometers (nanogears) to meters (macrogears) with corresponding application areas from nanoelectromechanical systems (NEMS) to large mills and wind turbines. A wide range of materials ranging from plastics and ceramics to ultrahigh strength steels are used in gear manufacture.

Gears and subsequently the gear manufacturing industry plays an integral role in many industrial sectors as it is one of the basic mechanical components used for transmission of motion and/or power in equipment, machines, and instruments. Several conventional and advanced methods of gear manufacture are available for use in specialized applications to produce gears that are fit for purpose. Technological advancements in gear engineering over the last few decades have enabled the gear industry to produce near-net shaped and high-quality gears by short process chains and a lower environmental footprint.

1.1.2 History

The writings of Aristotle (4th century B.C.) reflect some of the earliest reference to gears and their use [2]. He specifically noted that the direction of rotation is reversed when one gear wheel drives another. Water-lifting devices, in the form of ‘Persian wheels’, were used in the 3rd century B.C. Animals such as camels, bullocks, and buffaloes were used to drive these devices that were typically associated with open wells. In this arrangement, an animal driven horizontal toothed wheel was meshed into a vertical toothed wheel that was then used to lift water containers that were attached to another geared mechanism (Fig. 1.1). Later on, this method was successfully adopted for use in water-driven grain mills and other devices. During the 3rd century, Archimedes also developed a device (Antikythera mechanism) that was equipped with numerous gears to simulate positions of astronomical bodies [3]. The sketchbooks of Leonardo da Vinci, dating to the mid 1400s, depict various unique gear mechanisms. Initially, wood was the material of choice for gear manufacture until it was subsequently replaced by cast iron.

Figure 1.1 ‘Persian wheel’: A water-lifting gearing mechanism used during 3rd century. Source: Reproduced with permission from P.L. Fraenkel, Water lifting devices, FAO irrigation and Drainage Paper 43, Corporate Document Repository, Food and Agriculture Organization of the United Nations, Rome, 1986 [4].

A more advanced approach to gear engineering came into being at around 1400 with more comprehensive use of science and mathematics in gear design and the associated mechanisms. The first major investigation into gear design as regards to proving the benefits of the involute curve over a cycloidal was conducted by Philip de la Hire in France and later confirmed by a Swiss mathematician Leonard Euler who was responsible for the law of conjugate action [1]. The industrial revolution in England during the 18th century led to the use of cycloidal gears for clocks, irrigation devices, water mills, and powered machines. Further uses were rapidly developed and explored with the invention of the locomotive, vehicles, and other machines. Gear hobbing and shaping technologies were developed in the early 19th century providing the foundation for fabrication of better quality commercial gears. Various new gear types, materials, and surface treatment techniques were introduced during the 19th century. Further advancement in gear manufacturing, measurement techniques, and testing technologies during the late 19th and in early 20th centuries led the way for significant growth in its application in industry.

1.2 Classification and Gear Types

A wide range of gear types exist to fulfill various different application requirements. Gears and gear systems are usually classified according to the orientation/arrangement of its associated rotational axes. Gears are therefore classified as parallel-shaft gears, intersecting-shaft gears and nonparallel nonintersecting-shaft gears (refer Table 1.1). The details regarding these three categories and the corresponding gear types are discussed in detail in the following subsections.

Table 1.1

The Three Major Categories of Gear Classification and Corresponding Gear Types

Categories of Gears (Based on the Orientation of Gear Shafts)	Types of Gears	Representation	Features, Applications and Methods of Manufacture
Parallel-shaft gears	Spur gears		Features: Simple to design and manufacture, highest efficiency, easy to assemble, offer excellent precision, high wear and noisy operation
			Applications: Automotive transmission; Industrial drives; Machine tools; Motors and pumps; Agriculture equipment; Scientific instruments; Electronic devices; Large mills
			Methods of Manufacture: Hobbing, shaping, milling, broaching, casting, extrusion, stamping, powder metallurgy, ...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• Preface
• Chapter 1. Introduction to Gear Engineering
• Chapter 2. Conventional Manufacturing of Cylindrical Gears
• Chapter 3. Manufacturing of Conical and Noncircular Gears
• Chapter 4. Advances in Gear Manufacturing
• Chapter 5. Conventional and Advanced Finishing of Gears
• Chapter 6. Surface Property Enhancement of Gears
• Chapter 7. Measurement of Gear Accuracy
• Index