A Novel Non-Contact Measurement Method of Ball Screw Thread Profile Detection Based on Machine Vision

Abstract

The transmission accuracy of the ball screw depends on the processing quality of the thread profile. Traditional detection method of thread profile is complicated and inefficient. When shooting the thread profile of the ball screw in the normal section, the camera axis must be tilted to the lead angle, and adjustment errors are easily introduced from both the front view and the top view. When shooting in the axial section, the spiral lines block each other, so the actual thread profile cannot be captured for detection. In order to solve the above problems, a thread profile detection method is proposed: the theoretical equation of the ball screw thread profile in the axial section is derived based on the theoretical thread profile in the normal section, and the theoretical equation of the thread profile projection curve in the axial section is solved based on helix analysis, and the differential equation between them is obtained; then, the theoretical correction value of the thread profile projection curve is obtained by Linear Search to find the boundary value; the actual thread profile in both axial section and normal section is finally obtained with the theoretical correction value, which can support accurate measurement and detection of the key parameters of the thread profile. Experiments show that the proposed method can effectively improve the accuracy of the ball screw thread profile detection.

Keywords

• ball screw thread detection
• thread profile on axis section
• thread profile projection curve on axial section
• thread profile on normal section
• machine vision