Abstract: This invention relates to tube bending mandrels and, more particularly, to an improved version thereof characterized by a threaded connection between the tube-shaping ring and the necks of the ball-carrying links that functions in cooperation with an annular stop-forming rib and a retaining ring at opposite ends of the threaded link neck section to resist equally well both tension loads and compression loads while maintaining precise axial spacing between subassemblies in an assembly where, except for the links at opposite extremities, all parts remain fully interchangeable.

Abstract: This invention relates to an improved tube bending mandrel of the general type having fixed and bendable sections and wherein the latter comprises a chain of ball and socket elements linked together in end to end relation with each such element being encircled by a ring of the same diameter as the fixed section cooperating therewith and with one another to define limited movable universal connections therebetween. More specifically, the instant invention relates to an improved ball and socket assembly wherein the ball portion comprises two or more spherically-surfaced ring segments which cooperate with each other and with a spherically-concave head formed integral with the body in which the socket is formed on the opposite end of the link to form the ball.