An accurate measurement method of gear transmission error based on a double-angle measurement device

In this paper, a geometric model of a grating and reading head was established, where the relationship between the angle deviation, which was compensated for by double reading heads, and the actual angle is deduced. A new measurement method was proposed by applying the clock pulse counting method to the measurement of the transmission error of the gear pair input-and-output angle encoder while taking into account the gear pair's transmission error. To demonstrate the feasibility of this measurement method, a transmission error test bench of involute gear pairs was built. Based on the output gear, the counted pulses were divided into integer pulses and non-integer pulses, and a transmission error curve was obtained by processing the pulses. The transmission errors of a helical gear with untrimmed angles and a gear pair with trimmed angles were also measured. Compared with the untrimmed gear pair, the first-order amplitude of the trimmed gear pair was reduced by 25.25%, 0.79%, and 16.9%, but other whole-order full-harmonic amplitudes were excited. However, the peak value of the single tooth surface of the trimmed gear pair was generally less than that of the untrimmed gear pair. The peak transmission error and the amplitude of the tooth harmonic frequency had good repeatability, within 16%, which verified the feasibility of the transmission error test method. The measurement precision reached 1 arcsecond in the tooth frequency.