Design of Harmonic Drive with Double-Circular-Arc Tooth Profile

This paper proposes a method for designing the double-circular-arc tooth profile of the harmonic drive with consideration of the relative motion characteristics between flexspline and circular spline teeth. Compared with the conventional double-circular-arc tooth profile, the proposed one has fewer parameters and higher correlation between the circular-arc and design parameters. First, the proposed tooth profile consisting of two circular arcs is introduced and its equation is formulated. Secondly, the trajectory of the flexspline tooth profile is analyzed in the case of the circular spline fixed. Then the envelope motion process of the tooth profile is investigated and the continuous conjugation condition is established for designing the parameters of flexspline tooth profile. Finally, the effectiveness of the design method is verified by numerical example. The result shows that the proposed tooth profile can achieve continuous engagement without interference and there are 37.7% of teeth participating in engagement. The research may provide a new thought for the innovative design of harmonic drive tooth profile.