A real time wear measurement system for tripod type constant velocity joints

Abstract

A real-time wear measurement system for tripod type Constant Velocity (CV) joints is proposed in this study. Adhesive wear on tripod type CV joints is very crucial to the life time of CV joints but it is very difficult to measure the wear depth of a tripod type CV joint separate from the drive shaft assembly. The wear measurement system developed in this study can measure the wear depth of a tripod type CV joint in real-time as it applies kinematics and forces to the CV joint.In order to apply the same motions as the motions of an actual CV joint, kinematics of the CV joint has been analyzed. As a result, reciprocating stroke and yaw motions have been completely implemented in the system. The wear measurement system comprises four parts. The first part is for applying normal forces to a set of spherical roller and housing track. One servo motor, spur gear and ball screw sets were employed to generate and augment the normal forces. The second and third parts are for applying reciprocating stroke and yaw motions, respectively. These parts synchronize with each other to make the same motion profiles as the actual CV joint. The fourth part is for measurement. This part consists of load cell and rotary encoder to measure the surge normal forces caused by the flaking phenomena and the wear depth caused by the adhesive wear. In the case of the encoder, the wear depth is augmented by the ball screw and spur gear sets so 0.18°/μm of measurement resolution can be achieved.For the validation of the system, a tripod type CV joint was selected, and its wear depth was measured by the system and the results were compared with the wear depth measured by a profilometer.