Finishing of Hob Tooth Flank by Plunge Grinding

It is desirable to increase the number of cutting edges per bob revolution as much as possible to reduce the burden of each cutting edge and the polygon error caused in bobbing process. But, it is difficult to increase the number of cutting edges because interference between the grinding wheel and the following cutting edge in relief grinding of the hob is apt to occur. A method for finishing the hob cutting edges by plunge grinding without relieving motion is proposed. In the method, the cutting edge is finished when the grinding wheel and hob work are in a static position. In this paper, the calculation method of the grinding wheel profile to finish the cutting edges, the optimum static position to obtain the desirable clearance angle, and the effects of the positioning errors of the grinding wheel on the accuracy of finished cutting edges are investigated.