ボールセンタを用いた精密円筒研削 続報 鋼球の摩耗の影響

Abstract

In high precision cylindrical grinding, it is known that the accurate and inexpensive steel balls in place of the cone centers enable to grind workpiece accurately without influences of the misalignments and the geometrical deviations of the center holes. The purpose of this study is to explain the supporting characteristics of these ball centers. In this paper, endurance tests were performed and ball's wear was measured to investigate its effect on the rotational accuracy and the roundness of the workpiece. The obtained main results are as follows : (1) The rotational accuracy and the roundness of the workpiece were kept at high levels during the endurance test of three hours regardless of the ball wear. Therefore, the wear had little effect on the accuracy. (2) The contact points between the ball and the holder gradually shifted to other points, not worn yet. Then the accuracy average effect maintains the rotational accuracy at a high level. (3) Lubrication every quarter hour reduced the ball wear to half. Moreover, the lubrication prevented the ball from release effectively. Consequently, there is no fear for the ball wear in ordinary circumstances.