Development of a new gear profile measuring machine with five-link closed-loop mechanism

As conventional measurement method in a gear production line, a gear rolling tester is used to identify defective gears. However, there is a demand to judge by tooth profile and helix measurement. The purpose of this study is to establish an inexpensive and compact gear measurement system that can be easily installed in a gear production line. Since it is necessary to develop a measuring machine with high general versatility and space saving to be introduced to a gear production line, we focused on a measurement system using a robot. In this study, first, a gear measuring machine (GMM) using a SCARA robot was made and evaluated for accuracy as a GMM. To solve the problems obtained from the evaluation, a GMM with a five-link closed-loop mechanism consisting of a Direct Drive (DD) mechanism was developed, with optimal link lengths derived by simulation to achieve high accuracy. Then, the errors due to the manufacturing accuracy of the link length and the mounting angle of the rotary encoder of the developed GMM were estimated by calibration, and the compensation was implemented based on the errors. Finally, the repeatability of measurement of the developed GMM was verified using the involute artifact.