Studies on tooth surface modification of worm gears (2nd report, tooth bearing tests of worm gears with modified tooth surface)

The purpose of this study is to prove the usefulness of the surface modification method for cylindrical worm gears as proposed in the first report. The method is applicable to worm gears with an arbitrary profile, producing a good entrance gap without transmission error. The entrance gap is indispensable for worm gear drives. This paper is composed of three parts. First, a method for calculating the grinding wheel profile in order to finish a worm with an arbitrary profile is proposed. Second, the grinding tests of the involute worm gears with from 1 to 7 threads are conducted using the CNC gear grinder. Third, the proposed modification method is applied to the worm gears (m = 4 mm, N1/N2 = 3/38) when the cutting edge profile of the hob for finishing the worm wheel was given. A pair of test worm gears is fabricated and the tooth bearing tests are conducted. The tooth bearing patterns with a good entrance gap were obtained as expected in the design stage.