Theory study of a novel planar enveloping internal-meshing worm drive

Abstract

Some special compact mechanical transmissions with multi-load are required in robot joints, artillery systems, agricultural machinery and multirole shaft-driving devices, but the existing products of mechanical transmissions cannot meet the demand of modern industry, and need some new transmission structure or solution. To this end a novel worm gear named the planar enveloping internal-meshing worm drive is proposed for applications requiring multi-load transmission for the first time. Its meshing functions, including the induced normal curvature, lubrication angle, and relative entrainment velocity, are developed on basis of gear meshing theory. Furthermore, the meshing zone for the worm tooth is analyzed through tooth contact analysis in order to determine the optimal mother plane dip angle b. Moreover, the tooth profile of the worm wheel is optimized and the worm parameters obtained through tooth contact analysis is verified. Finally, the worm gear is manufactured by using the 3D-printing technology to measure the correction for the theory investigation. The presented worm drive exhibits ideal meshing performance, with minor contact stress and high lubrication. This gear set is expected to find applications in such systems as robot joints, artillery systems, and multi-roller shaft-driving devices.

Direct method to determine singular point of enveloped surface and its application to worm wheel tooth surface

“…Zhao et al [23,24] studied the undercutting problems in the conical surface enveloping conical worm drive and supplied detailed numerical results of limit points. While constructing a three-dimensional model for the planar worm wheel, Deng & Feng [25] encountered an interference problem, and this interference was avoided by modifying the tooth profile of the gear. Chi et al [26] derived the undercutting limit line of a planar enveloping hourglass worm.…”