Shaft-supported composite high-strength machine element and method of making the same

Abstract

Abstract A machine element consisting of a shaft having thereon an enlargement such as a gear or cam is made in composite form at a much lower cost in labor and materials than in one-piece form by providing a solid metal supporting shaft of the desired dimensions with a roughened zone, as by coarse-knurling it. A sintered powdered metal preform of suitable metal for the enlargement is prepared in a conventional manner of slightly smaller diameter and of slightly greater length than the finally-desired configuration, and with a central longitudinal bore of slightly larger diameter than the shaft, to allow for expansion of both preform and shaft when both are heated to a forging temperature of 1800° F. to 2000° F. When so heated, the shaft on its roughened zone is preferably coated with brazing metal and dropped into a correspondingly-shaped lower socket in the top of the lower plunger of a forging die-set with a die cavity of the correct finished size and shape, allowance being made for contraction upon cooling. The similarly heated preform is dropped onto the upper end of the shaft and slides down it into the die cavity. The upper plunger of the die-set with a similar shaft socket therein is then moved downward into the die cavity with sufficient forging force to shorten the preform while expanding it outward into engagement with the die bore, then inward to interlock with the roughened shaft zone while the brazing metal layer thereon prevents cracking from differences of expansion. At the same time, this forging pressure converts the sintered powdered metal preform into a substantially solid enlargement. The upper and lower plungers are then moved upward to eject the composite forged machine element from the die cavity.

Inventors

• 👤 John Haller

Bibliographic Details