New Design Method for Flexspline Tooth Profile of Harmonic Drive Considering Deformation

In the paper, the deformation of the inner surface of the flexspline (FS) of the harmonic drive (HD) is different with the deformation of the top of the flexible gear is presented. For improving the meshing qualities of harmonic drive, to analysis the cause of the different deformation, to avoid meshing interference between FS and circular spline (CS), the curvature difference between the inner surface and the tooth top of the FS after deformation is analyzed based on ring theory. In order to make the deformed tooth profile reach the predetermined meshing position, this paper takes the double arc tangent tooth profile as an example; a new tooth profile of FS was designed by shifting the coordinates of tooth profile to avoid undercutting during meshing, and then improves the operation reliability between FS with CS. To verify the effectiveness and correctness of the research, the finite element method (FEM) is employed to verify the different deformation between the inner surface and the tooth top of the flexspline.