Circular Spline Tooth Longitudinal Modification Design and Contact Analysis for Harmonic Drives with Short Flexspline

• Published in: Machines (Basel) 2024-11, Vol.12 (11), p.777
• Main Authors: He, Xingyu, Feng, Hesheng, Zhang, Menghan, Shen, Zaishang, Liu, Boyang, Su, Peng, Liu, Haoyu, Guan, Yabin
• Format: Article
• Language: English
• Subjects: Analysis; Arc cutting; circular spline; Conjugation; Contact angle; contact characteristics; Contact pressure; Contact stresses; Coordinate transformations; Design techniques; double circular arc common-tangent tooth profile; Finite element method; harmonic drive; Hydrogen sulfide; Liu, Timothy; Load; longitudinal modification; Mathematical models; Meshing; Methods; short flexspline; Stress concentration; Teeth
• ISSN: 2075-1702; 2075-1702
• DOI: 10.3390/machines12110777

Harmonic drives (HDs) with short flexspline (FS) always suffer from small meshing areas and severe stress concentration caused by large cone angles when a short FS is assembled and loaded. To address this issue, a tooth longitudinal modification method for the circular spline (CS) with a double circular arc common-tangent tooth profile (DCTP) is proposed. Using neutral layer and envelope conjugation theories, a mathematical model of the conventional straight CS tooth was developed. A shaping cutter for this tooth profile was then designed through coordinate transformation and meshing principles. The proposed longitudinal modification for the CS was achieved by adjusting the cutter’s trajectory. A precise finite element model of the HD was developed, revealing that tooth longitudinal modification can reduce the maximum contact pressure by 69.6% and significantly increase the contact area for HDs with short FS. This work provides valuable technical references for improving the contact state of HDs with short FS.