Cam shaft manufacturing process
AssigneeTextron Inc.
InventorRobert L. Clark
Life of this patent
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Abstract
A cam shaft manufacturing process wherein a cam shaft is cast from a heat-treatable gray cast iron having a high carbide microstructure, is annealed while retaining the carbides and then cooled to room temperature. Surfaces, such as cam lobe surfaces, are then surface hardened and the cam shaft may thereafter be machined. The heat treating process comprises heating the cam shaft at 1600.degree. F. (871.degree. C.) in about twenty minutes, holding the cam shaft at 1600.degree. F. (871.degree. C.) for about twenty minutes and thereafter heat treating the cam shafts at a temperature of 1600.degree. to 1640.degree. F. (871.degree. to 893.degree. C.) for about eighty minutes. The cam shafts are then cooled rapidly to about 400.degree. F. (204.degree. C.), for example, within about an hour and a half, and thereafter air cooled.
Claims14
In a process for manufacturing a cam shaft having a series of cam lobes wherein the cam shaft is cast from a heat-treatable gray cast iron having alloyed therewith elements selected from the group consisting of silicon, manganese, chromium, nickel, copper, molybdenum and vanadium, wherein the cast cam shaft is heat treated to improve the machinability while maintaining carbide structure, and is thereafter milled, surface hardened at least at the cam lobes and thereafter machined, the improvement in the heat-treating step comprising:
- heating said cam shaft to a temperature in the range of about 1550.degree. to 1700.degree. F. (843.degree.-927.degree. C.) in a time less than two hours, holding said cam shaft at said temperature for a period of one to four hours to anneal the cam shaft while retaining carbides and without substantial formation of austenite, and
- cooling said cam shaft to at least 400.degree. F. (204.degree. C.) within one to four hours.
Dependencies are inferred from the claim text.