CHAPTER 1
AN
OVERVIEW OF GEAR MANUFACTURING PROCESSES
Gear
manufacturing has been one of the most complicated of the metal cutting
processes. From the beginning of the century, the demand for better
productivity of gear manufacturing equipment was posed by “The Machines that
changed the World” i.e. AUTOMOBILES.
GEARS
IN AUTOMOBILE TRANSMISSIONS
A gear box transmits
the engine power to the driving wheels with the help of different gearing
systems. Different gear combinations are used to give the smooth running, the
lower fuel consumption, and the optimum driving comfort. Generally, passenger
car transmissions are provided with 4-5 forward speeds and one reverse speed.
In front wheel models, hypoid gears have been replaced by helical gears. Fig.
4.1 shows a typical transaxle of front drive model. Involute splines, both
external and internal, are also widely used on various shafts and hubs for
slide meshings in transmission system. Bevel gear and pinion are still used in
differential of automobiles. However, parallel axes spur and helical gears are
the main gears in automotive transmission. Manufacturing of gears presents a
demanding challenge for metallurgists in heat treatment, for supervisors in
machining and gear cutting, and for quality engineers in keeping the quality to
the required standards.
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| Fig. 4.1 A Typical Transaxle of a Modern Passenger Car |
Gear manufacturing process
dynamics are undergoing a major breakthrough in last two decades. Solutions
being sought are not corrective but preventative. Normally, either soft gear
process dynamic or hard gear process dynamic is being aimed. Objective is to
cut the number of operations or machines through which a work gear needs to
pass to attain the final specifications of dimensions and tooth form quality.
