Abstract: TI worm drive is a novel kind of hourglass worm, which consists of involute helical gear and enveloping hourglass worm. Accurate grinding for TI worm is the key manufacture technology for TI worm drive being popularized and applied, which means to obtain the profile of grinding wheel corresponding to the current grinding method. With the analysis of the movement relationship and the characteristic of the generating surface, the problem of accurate grinding for TI worm is converted into grinding for involute helical by shaped wheel. According to the theory of gear mesh, mesh equation for grinding involute helicoid by grinding wheel is deduced, the equation of the axial section profile of grinding wheel which can accurately grind TI worm is gained.

Key words: Grinding process, Helical gear, Hourglass worm, Profile of grinding wheel, Spiral motion