Push rod having irregularly shaped internal bore

摘要

A push rod and method of making same is provided which includes the step of cold extruding an irregularly shaped internal bore into the inner wall of an elongated hollow tube, thereby increasing the internal surface area and internal volume over conventional straight-walled tubes. In the preferred embodiment, the internal bore is defined by a cross-section of an equal number of alternately connected convex and concave portions which result in a varying wall thickness about the perimeter of the push rod. The thick wall regions are designed to be located diametrically opposite the thin wall regions.