A Study of the Hobbing Method by Radial Feed at the Start of Cutting : Part 1, Hobbing Tests of Helical Gears

Abstract

In hobbing. gears are usually cut with axial feed of the hob. However, for cutting of helical gears or large gears. the path is too long from the point that the hob teeth initially come in to contact with the gear blank to the point from which the tooth profile begins to he generated. If radial feed is used in the initial cut-in process, the hobbing time will be substantially shortened since the distance of the feed is similer to the tooth depth which is shorter than that of axial feed. However, the load of the hob teeth is largo in radial feed and the possibilities of large wear of the hob and an increasing vibration of cutting exist. In this research. cutting tests were performed comparing the hob wear in radial feed, , with that in axial feed hobbing. The result are as follows. (1) The wear of the hob by radial feed cutting was nat as great for tests in which the feed rate was about 2/3 times the axial feed. (2) In helical gear hobbing, the wear of the hob engaged in radial-axial feed hobbing was less than that for a whole gear being cut by axial feed only, since the extent of teeth under the large cutting load in radial feed differs from axial feed cutting.