Effects of tooth surface modification on planar double-enveloping hourglass worm gear drives

The modification of the planar double-enveloping hourglass worm gear drive can eliminate the phenomenon of the contact line cross and improve the transmission performance. In order to guide the selection of the type and the amount of modification, the equations of the contact zone and rear transition zone on the worm wheel surface are established. According to the position relationship between the contact zone and the rear transition zone on the axial plane and transverse plane, the changes in the tooth surface of the worm wheel obtained by different modification methods are obtained. The tooth surface changes obtained under different modification amounts are further summarized The structure of the modified worm wheel is finally determined. For Type-II drive processed with the center distance modification, the curvature interference limit line on the surface of the worm wheel can be cut off by the last cutting edge of the hob. The larger the amount of the center distance modification value is, the deeper the depth into the rear transition zone is. Finally, the analysis results were verified by the hobbing experiment and the worm gear drive running test.