Analysis and optimization of shielding in measuring helical gear tooth flank by laser interferometry

Abstract

Phase shifting laser interferometry is an effective method to measure the form error of a helical gear tooth flank. However, during measurement, part of the measurement light is inevitably shielded by an adjacent tooth or its own structure, and thus cannot be captured by the detector, resulting in the inability to collect a complete set of tooth surface shape information. This problem restrains the practicality of measuring a gear tooth flank by laser interferometry. We propose an analysis method and optimal search algorithm for shielding, to collect a complete set of tooth surface information from a measured gear. First, we propose an analysis method for shielding, based on ray-tracing, which allows the measurable region of helical gear tooth flanks with common parameters to be statistically analyzed. The variation law of the main parameters and a measurable region of the common helical gear tooth surface is expounded. Second, in order to obtain the complete interferogram, we propose an optimal search algorithm for shielding, by changing the relative position between the measured gear and the measurement optical system. Finally, relevant simulation and experiments prove that the proposed analysis and optimization methods are feasible. Furthermore, when the oblique incidence method is used to measure the shielded precision complex surface, the proposed methods of analyzing and optimizing shielding can be used for reference, to realize the complete measurement of the measured surface.