Telescoping tubes for torque transmission

摘要

An improved telescoping torque transmitting connection and a method for making tubes used in the formation of this connection are disclosed. The tubes are formed with inwardly extending lobes and the lobes are formed so that the wall thickness of the tube in their vicinity is at least as great as it is in the remainder of the tube, whereby the strength of the tube is not reduced by formation of the lobes. The lobes are formed with substantially flat flanks for interaction with the lobes of the mating tube, whereby the contact between the two tubes is made at a plurality of planar surfaces rather than along a plurality of lines so that the end loading developed when the tubes are telescoped with respect to one another under load is not excessive. The method for making the tubes involves drawing a precursor tube to an intermediate precursor having non-uniform wall thickness, in which the wall thickness of the tube is increased in the vicinity of the lobes to be formed, so that the wall thickness of the eventually-formed lobes is at least as great as that of the tube in the areas not having the lobes formed therein.