| 摘要 |
An improved ball-and-socket joint for use with dental model articulators of a vertex type comprising two brackets (13,14) hinged together at one end and each connected at the other end by a ball-and-socket joint (11,12) to a separate one of two stone plates (21,22) bearing dental castings. The ball-and-socket (11,12) joints have releasable mechanical means (26)for affixing the ball in the socket after the plates have been aligned for bite and occlusal fit between the dental castings. Affixing the ball in a socket is achieved by mechanically adjusting the diameter of one relative to the other of the socket and the ball to create a friction force that affixes the ball in the socket. In one embodiment, the mechanical means comprises a C-clamp having a concave band with a cross-sectional diameter substantially equal to the ball diameter and a gap to allow the ball to be snap-fit into the C-clamp. A bolt through flanges at the ends of the C-clamp is used to reduce a gap between flanges, thereby increasing without limit the frictional clamping force on the ball. In another embodiment, the ball is inserted into a truncated spherical cavity formed on a stalk in four parts with gaps between the parts. The ball gaps permit the ball to be snap-fit into the spherical cavity serving as the socket for the joint. A bolt threaded through the bracket base and stalk that supports the ball is turned to drive it between the four parts in the socket, thereby spreading apart the four parts of the ball in the cavity to produce the necessary friction force between the ball and cavity wall to affix the ball in the socket. |
