Abstract:

The traditional design, manufacturing and examination of spiral bevel gears depend frequently on the position and size of the contact pattern on tooth surfaces. In this paper, a new designing concept based on the transmission error is presented. Firstly, the information on dynamic characteristics and strength behavior reported by the transmission error, such as designed contact ratio, real contact ratio, vibrating excitation, load share between tooth pairs and sensitivity of the contact pattern to the error, is analyzed. Based on the analysis mentioned above, three types of designs on transmission errors are presented. They are: (1) A parabolic transmission error curve with a designed width between two ends, which is obtained by inclining the direction of the contact path on the tooth surface. It results in a contact ratio of 2.0-3.0 and the improved dynamics and strength behavior. (2)A parabolic transmission error curve with the designed amplitude, which is obtained by controlling the relative curvature of tooth surfaces along contact path. It results in a low sensitivity of contact pattern to error, as well as a high contact ratio under operating and maximum loads. (3)A fourth order transmission error curve with the designed width between two ends and amplitude, which can be obtained by CNC machine. It results in an improved dynamic behavior under light load, as well as the superiorities mentioned above. An approach to designing the spiral bevel gear drives with high performance is advanced.

Key words: spiral bevel gear, transmission error, contact ratio