Development of a Highly Accurate Ball Joint to Use Epoxy-Type Bond for Sliding Surface

A parallelly-actuated mechanism has a disadvantage of having a smaller workspace than a serial mechanism. It is important to get a larger workspace in order to expand its application field. The workspace of the parallel mechanism depends on the swing angle of the ball joints used in the mechanism. If the housing of the ball joint is milled close to the equator of the ball to achieve a large swing angle, the ball may leave the housing during the motion. This paper presents a new method for making a ball joint using epoxy-type bond that enables a large swing angle and precise motion without any special techniques. It realizes a comparatively cheaper and simpler way of making the ball joint. This approach can be applied to assembling precise parts with small clearances that are difficult to machine. This paper also describes the ball joints performance characteristics and the coating process of the release-agent to achieve precise clearance. A clearance of approximately ±0.015mm on the new ball joints was achieved.