Tooth Surface Configurations Caused by the Errors in Hobs and Hobbing Machines

Abstract

Estimation of the errors of a hob and a hobbing machine is necessary in order to improve the hobbing accuracy. This paper focuses on the configurations remaining on the tooth surfaces of hobbed gears, and illustrates analytically the tooth surface configurations caused by the errors of the hob and the hobbing machine. The errors of hobs concerned are the lead variation and the eccentricity, while the errors of the hobbing machine include the variation of the rotational center and the rotational irregularity of the table. The above-mentioned hobbing errors are closely related to the tooth surface configurations, and particularly, the feed marks express the characteristics of the tooth surfaces very well. As a result of the investigation on the tooth surface configurations and the formation mechanism of the feed marks, it is possible to estimate the hobbing errors by the calculated tooth surface configurations of hobbed gears.