Performance of skiving hobs in finishing induction hardened and carburized gears

摘要

The present investigation was conducted using six kinds of carbide bobs, and the following results were obtained: 1. Induction hardened gears with a Vickers hardness of about 600 Hv could be easily finished by a carbide skiving hob without coating. 2. Carburized gears with a hardness of about 750 Hv were very difficult to finish due to wear and chipping at the cutting edges when skiving bobs without coating were used. 3. When a carbide skiving bob with a coated TiN layer of about 5 μm in thickness was used, the tool life increased by a factor of 10 in comparison to the one without coating. 4. The skiving hob with a coated layer on the flank only was effective in increasing the tool life, especially in finishing induction hardened gears with a hardness of about 600 Hv. 5. The flank wear of the trailing side cutting edge was appreciably greater than that of the leading side cutting edge when the bobs were used for finishing carburized gears. 6. The reason for the difference in the wear is explained by calculating the difference in the maximum tool angles of the leading and trailing sides (Fig. 17). 7. It is estimated that the tool life of a skiving bob to be used for finishing fully hardened carburized gears can be increased by introducing coated bobs with almost the same tool angle for leading and trailing sides. 8. The tool angles for the leading side and trailing side cutting edges become the same value when the numerical value of the spiral angle of the bob is made equal to that of the lead angle of the bob tooth thread.