Kinematic pairs of different types are well known and widely used. One example of such a pair is disclosed in WO 2007/084901, where a ball joint has a ball with an attached shank, an inner bearing and an outer bearing both having a wear surface, and a biasing element made from a Belleville washer type spring. Furthermore, the ball joint has a socket which is closed at its inner end and which has an opening at its outer end. The ball joint is assembled in a first step where the biasing element is inserted into the socket and in a second step where the inner bearing is inserted into the socket, followed by the ball with the attached shank and the outer bearing. In this arrangement, the inner bearing rests on the biasing element and the ball is kept between the wear surfaces of the inner and the outer bearing, while the shank—which is attached to the ball—is passed through an opening in the outer bearing. In order to finalize the assembly of the ball joint, the outer bearing is pressed into the socket against the preload force of the biasing element and the outer rim of the socket is folded inside towards a centre of the socket's opening. Due to the folded rim, the outer bearing is kept in place inside the socket and the compression of the ball between the inner and the outer bearing is maintained for providing a stiffness of the ball joint.
This known ball joint has a number of disadvantages: it comprises a large number of parts and there are production-related deviations in the shape and size of the ball and the inner and outer bearing. Furthermore, due to the limiting accuracy with which rim is folded inwards, the compression of the ball between the inner and the outer bearing varies for every ball joint.
USPTO Backgrounds
USPTO Backgrounds