Principles of Gear Shaving

Gears are one of the important components in the transmission system. Gear shaving is one of the most efficient and economical gear finishing processes after hobbing. Gear shaving is an advanced gear finishing technique that only requires radial feed. Gear shaving is a very precise machining process, and its benefits include the improvement of productivity and precision, long service life of the tool, and simple machine construction.

1. Principles of the gear shaving processing

The gear shaving process uses the principle of staggered shaft gear transmission. The shaving cutter is the driving wheel, while the shaved gear is the passive wheel. The two roll freely in the form of staggered shaft gears without backlash, and exert a certain pressure on the contact surface between the shaving cutter and the workpiece. During the rolling process, they both produce relative sliding in the direction of the tooth profile and tooth trace. Since the shaving cutter has many serrated edge grooves along the direction of the tooth trace, a layer of metal will be cut from the workpiece along the tooth direction. The workpiece is in the direction of the tooth profile, because the shaving cutter has no edge groove, although there is relative sliding, it does not have a cutting effect.

Gear shaving is a free-cut gear finishing operation that removes fine gears. A lot of metal can be gotten from the working surfaces of the gear teeth. Its purpose is to correct errors in helix angle, index, tooth profile and eccentricity. The process can also improve tooth surface finish and eliminates the danger of load concentration at the tooth end during use through the crown form. Gear shaving provides the modifications of form to reduce gear noise. These improvements can also increase the load-carrying capacity, safety factor and service life of the gears.

Gear shaving is a step of gear finishing. It should not to be confused with gear cutting (rough machining). Gear shaving is a reasonable solution to the inherent errors in gear machining. The shape of the gear shaving cutter can be reground to make the crown and tooth profile suitable for different heat treatment actions because the temperature of the steel is different. The gear shaving cutter can also be reset to allow for lead changes during heat treatment.

2. Gear shaving processing can improve productivity

Among the various methods of finishing gear teeth, shaving is still the most widely used method, especially in mass production, because gear shaving cutters have the ideal cost performance ratio. A major limitation of the shaving process is the difficulty of precisely controlling the deformation caused by thermal treatment, which is an operation performed after shaving. If this method does not ensure the quality of the finished gear, a different process, such as grinding after heat treatment, can be used. The gear shaving process can be performed at high productivity.

In the automotive industry, most gears used in gearboxes are usually suitable for gear shaving. The gear shaving machine is much higher in production speed than the grinding, and its higher cost is not always an advantage in terms of justifying. The noise control can be provided through a ground transmission. In fact, what is known is that the noise level of a gearbox, during transmission in general, does not depend only on the accuracy of the gears, but all factors surrounding the gears also have a considerable effect: the condition of the gear holes, the straightness of end faces, the straightness of shafts, the alignment of journals in gearboxes, etc.

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