Abstract: The tooth surface of the stationary internal toroidal gear that is the key parts of the
toroidal drive is a complex space curved surface. In order to realize the complex surface of the NC
processing and using the finite element method for the contact analysis, whether obtaining the
accurate entity model of the stationary internal toroidal gear or not is the key to resolving the
problem. In this paper aiming at the stationary internal toroidal gear digital modeling problems,
according to the mathematical model of the stationary internal toroidal gear, the grid division
method of the helical tooth surface is given, the method of the stationary internal toroidal gear
discrete modeling based on the numerical method is put forward. The method adopts cutting
planes to scatter the stationary internal toroidal gear model into data point cloud, so as to get the
stationary internal toroidal gear discrete model as the basis for later complex curved surface
interpolation reconstruction.

Key words: toroidal drive, stationary internal toroidal gear, discrete modeling, entity model