Abstract: A blow molded convoluted boot for use with constant velocity joints is provided with a retention convolution, the inside diameter of which is proportioned to form a direct attachment to an annular recess formed in an outer surface of the body of a CV joint for retaining the boot on the CV joint and resisting axial forces tending to pull the boot off the joint when the CV joint is operated at high offset angles.

Abstract: Injection molding apparatus is disclosed in which weld lines are removed from a part, such as a parison, which weld lines are caused by the interruption or splitting of the flow of plastic material around core support pins or the like by the provision of an annular mixing chamber which opens into the plastic material flow passage. The plastic material is caused to move radially into the mixing chamber where it is spread by reason of the increasing volume encountered, accompanied by a reversal of flow radially inwardly into an annular injection gate. The movement of plastic material within the chamber and the resultant increase in temperature by reason of shear, eliminates the weld lines which have been formed in the material by reason of the splitting of flow around the pins.