Method of Preventing Cutting Edge Failure of Hob Due to Chip Crush

Dry hobbing has great advantages such as its environmental friendliness and its ability to reduce manufacturing cost. Dry hobbing, however, often causes failures of the cutting edge of a hob or problems on the surface quality of the tooth flank of a manufactured gear. The pinching and crushing of generated chips between the cutting edge of a hob and the tooth flank of a work gear is considered to be a major cause of such problems. A simulation method of cutting using a hob was reported. In this report, the simulation is applied to solving the industrial problems of dry hobbing. The simulation clarifies the mechanism of cutting edge failures. The “distance of single-edge cutting” of a hob tooth is proposed to be an index of pinching and crushing of chips. Factors influencing this index are investigated and fundamental countermeasures against pinching and crushing are shown. This method has been applied to solving problems in the mass production of automotive gears, and good results were obtained.