Measurement Of Pitch Deviation Based On Average Tooth Profile And Related Technology

Gear, as an important transmission part, directly influences the performance and stability of the device. Therefore, the study of gear precision evaluation is particularly important. Existing pitch deviation measurement is selecting one point on same side of each tooth surface, which is in the middle of the tooth height on the same circumference of a circle, so as to calculate pitch and evaluate the teeth surfaces distribution uniformity. Therefore, some shortcomings of local measurement point will affect the accuracy of pitch evaluation. Concerning the shortcomings of this measuring method, a new pitch deviation evaluation method relying on the average tooth profile, which is related to tooth profile deviation measured by the Mahr891E gear measuring center, has been proposed so as to reflect the distribution uniformity of gear teeth comprehensively and objectively. Finally, a measurement system has been established by using the structured light three-dimensional measurement technology. As a result, this study provides the thinking method and paves the way for the following establishment of a scientific three-dimensional gear deviation evaluation system and realization of a rapid three-dimensional measurement of tooth surface.Concentrating on the gear pitch deviation, this paper provides four main aspects and states specifically below:1. A new evaluation method of pitch deviation has been presented, which make the whole points of the tooth profile trace into the pitch evaluation range and be closed to the real working condition of gear. This pitch evaluation is related to tooth profile deviation. Through analyzing the measuring principle of the gear measuring center, this paper selects the gear measuring center to collect the data and analyze its error correction process.2. Collect the gear tooth profile deviation data by Mahr891E gear measuring center and separate the angle deviation from the tooth profile deviation. An angle deviation evaluation model is created and developed by fitting the angle deviation of the average tooth profile through the least squares fitting to evaluate the distribution uniformity of gear teeth. In order to verify the rationality of the deviation model, the comparative experiments with gear pitch tester are obtained.3. Preliminary research on the technology of structured light measurement has been done, building a structured light measurement system including single camera and projector. With the gray code technology, accurate decoding has been accomplished through projecting two opposite gray codes with all-black and all-white images method.4. Use the projector as a reverse camera, calibrate the system with Zhang’s calibration method and reconstruct the three-dimensional coordinates of object based on triangulation principle. The design of three-dimensional pitch deviation measurement system with structured light is proposed and discussed at last.By comparing the measurement results, pitch cumulative total deviation measured by the method stated in this paper is 5.04μm, while that measured by pitch tester is 5.84μm. Consequently, the method discussed in this paper can better evaluate the actual pitch with generality and provides a new way of pitch evaluation. The tooth surface reconstruction has been initially implemented through structured light measurement system, which contributes to the next three-dimensional measurement of gear deviation.