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22

2023

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03

Introduction of Carburizing and Quenching Examples Required for Trial Manufacture of Motorcycle Sprockets


An example of carburizing and quenching required for trial production of motorcycle sprockets is introduced:

The method of increasing the effective hardened layer depth of carburizing and quenching and the effect of controlling gear distortion are as follows.

Motorcycle sprockets are carburized and quenched in a multi-purpose furnace. When the effective hardening layer deviation is 0.922 mm and the effective hardening layer depth for small batches is 0.680 mm, the splines are qualified. When the effective hardened layer depth of gears in batch production is 0.594mm, the lower part is poor, and the spline is swollen, which is unacceptable. For this reason, the effective hardened layer depth of the unqualified motorcycle sprocket should be within the upper middle dimensional tolerance, and the spline should be qualified. See Table 4-17 for the effective hardened layer depth and spline hole distortion of carburized and quenched motorcycle sprockets. Figure 4-85 shows the charging direction of motorcycle sprocket.

In actual production, due to the untimely detection of the spline hole, the size of the broach in use becomes smaller, and the spline hole of the motorcycle sprocket shrinks after heat treatment. Therefore, the depth of the carburized layer can be appropriately reduced, and the hardness of the core can be reduced to improve the qualified rate of the gear spline hole deformation.

Some motorcycle sprocket splines have a surface hardness of ≤ 50HRC after heat treatment, and there is no requirement for the hardness of both end faces. After heat treatment, gears with low internal spline hardness can be realigned with a broach to make the major diameter of the spline acceptable. For such motorcycle sprockets, it would be better to carburize first, then cut off the carburized layer, and then broach the splines.