A novel cylindrical skiving tool with error-free flank faces for internal circular splines

Abstract

Strain wave gearing is widely applied in robotics and aerospace because of its zero-backlash and high gear ratio. Its circular spline (CS) is a rigid internal gear engaged with a flex spline (FS), driven by the wave generator's rotation. Obtaining the CS's tooth profile is difficult because the FS has a deformed ellipse shape caused by the wave generator. Furthermore, most CSs are manufactured by gear shaping and thus are lower precision and productivity comparing to external gears produced by gear hobbing. Power skiving is recently applied to overcome this problem. Mathematical models of CS and its skiving tool are established here. Moreover, a cylindrical tool is submitted to make tool manufacturing easier than a conical tool. A novel design for the error-free cylindrical tool and the skived gear is eventually derived. By modifying machine settings of the skiving process, it provides a relief angle to avoid the cylindrical tool rubbing with the internal gear. This manufacturing process is conducted on a six-axis CNC bevel gear cutting machine. An error analysis of the VERICUT cutting simulation result confirms the correctness of the proposed models.