Motion simulation of annular polishing

Based on coulomb friction model, the frictional motion model of workpiece relating to polishing pad was presented in annular polishing. By dynamic analysis software, the model was simulated and analyzed. The conclusions from the results were that the workpiece did not rotate steadily. When the angular velocity of ring and direction were same as that of polishing pad, the angular velocity of workpiece hoicked at beginning and then, were same as that of polishing pad before contacting with ring. The angular velocity of workpiece vibrated at the moment of contacting with ring. After that, the angular velocity of workpiece increased gradually and fluctuated at a given value; while the angular velocity of ring decreased gradually and also fluctuated at a given value. Since the contact between workpiece and ring was linear, their linear velocities and directions should be same. But the angular velocity of workpiece was larger than that of polishing pad on condition that the radius of workpiece was less than that of ring. This did not agree with the pure translation principle and the workpiece surface couldn't be flat, either. Consequently, it was needed to be controlled with the angular velocity of ring and radii of ring and workpiece besides friction to make the angular velocity of workpiece equate to that of polishing pad in order to obtain fine surface flatness of workpiece.