THREAD CUTTING METHOD FOR DEVELOPABLE TOOTH FLANK DOUBLE ENVELOPING WORM USING PINION CUTTER

PURPOSE:To achieve a high productivity with the use of a pinion cutter, by rotating a pinion cutter around a medium gear shaft in accordance with the rotation of the same gear and giving the relative motion in the gear axial direction relatively between the worm shaft and medium gear shaft. CONSTITUTION:In a developable tooth face drum type worm gear, a blade straight cutting edge is arranged so that the cutting edge of a blade 2 exists within the medium gear plane at the same pitch as the teeth of a medium gear (tooth number of medium gear-reduction gear ratio of medium gear Xworm bar number) and in the tooth number equal to the tooth number thereof or 1/integral number and at the pitch of integral number times within the plane vertical to a tool shaft 1. Now this blade cutting edge may not be located on the plane vertical to the tool shaft 1. Namely, it may be arranged so as to composedd a helicoid with the tool shaft 1 as the axis. The cutter blade 2 arranged like this is rotated in accordance with the rotary motion of the medium gear and a longitudinal feed is applied on the blank of the worm.