METHOD AND APPARATUS FOR STRENGTHENING OF POWDER METAL GEARS BY AUSFORMING

• Main Authors: RAO SUREN B, AMATEAU MAURICE F, SONTI NAGESH
• Format: Patent
• Language: English
• Published: 28.12.2005
• Edition: 7
• Subjects: CASTING; CHEMISTRY; CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION ORPROCESSING OF GOODS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUSMETALS OR ALLOYS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; MAKING METAL MALLEABLE BY DECARBURISATION, TEMPERING OR OTHERTREATMENTS; MAKING METALLIC POWDER; MAKING PARTICULAR METAL OBJECTS BY ROLLING, e.g. SCREWS,WHEELS, RINGS, BARRELS, BALLS; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVINGMATERIAL; METALLURGY; METALLURGY OF IRON; MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; PERFORMING OPERATIONS; POWDER METALLURGY; PUNCHING METAL; TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION; TECHNICAL SUBJECTS COVERED BY FORMER USPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS; TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINSTCLIMATE CHANGE; TRANSPORTING; WORKING METALLIC POWDER

A technique for net shaping gear teeth of a high performance power transmission gear from a powder metal workpiece includes heating a powder metal workpiece in the form of a near net shaped gear blank having gear teeth surfaces above its critical temperature to obtain an austenitic structure throughout its surfaces, isothermally quenching the workpiece at a rate greater than the critical cooling rate of its surfaces to a uniform metastable austenitic temperature just above the martensitic transformation temperature, rolling the gear teeth surfaces of the workpiece to a desired outer peripheral profiled shape between opposed dies, :each die having an outer peripheral profiled surface, while holding the workpiece at the uniform metastable austenitic temperature, the gear teeth surfaces undergoing densification, plastic deformation, and strengthening as a result of the rolling operation, and cooling the workpiece through the martensitic range to thereby harden the surfaces of the gear teeth.