High-precision measurement of gear tooth profile using line spectral confocal method

Abstract

The optical measurement of gear tooth profile has the advantages of high efficiency and non-contact, but its measurement accuracy has not reached the accuracy of the existing contact method. Therefore, a line spectral confocal high-precision gear tooth profile measurement method is proposed. First, the gear optical measurement coordinate system is established using a standard mandrel and the optimal measurement position model for the measured tooth profile not blocked by the adjacent tooth is established. Then, to solve the problem that the tooth profile information contained in the optical measurement results and contact measurement results is inconsistent and cannot be directly compared, a virtual probe envelope filtering method for the tooth profile optical measurement data is proposed. Next, to verify the accuracy of the line spectral confocal gear measurement system, the tooth profile deviation measurement experiments using a two-accuracy-level gear involute master are conducted. The results show that the proposed line spectral confocal method has high measurement repeatability and accuracy. The maximum absolute difference between the tooth profile deviation measurement results and the verification results is 0.16 µm, and that the tooth profile deviation curve maintains highly consistent with the verification curve. Finally, the tooth profile deviation measurement experiments using a two-accuracy-level spur gear are performed. The results indicate that the maximum absolute difference between the tooth profile deviation evaluation results measured with the proposed method and the gear measuring center is 0.28 µm. The maximum absolute difference between the two profile deviation curves by point-to-point is 0.52 μm, and the average absolute difference is 0.16 μm. The proposed line spectral confocal method can realize the high-precision measurement of gear tooth profile.