Method of Manufacturing a Hardened Forged Steel Component
a technology of hardened forged steel and manufacturing method, which is applied in the direction of furnaces, heat treatment furnaces, heat treatment equipment, etc., can solve the problems of cracking or excessive distortion, difficulty in obtaining even hardness depth between the tips and roots of teeth, and additional cost and complexity of induction hardening equipmen
Inactive Publication Date: 2007-10-25
BISHOP INNOVATION PTY LTD
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Benefits of technology
"The present invention is a method of manufacturing a steel component by heating a portion of a steel blank, forging it to shape, and then cooling it in a controlled manner to a second temperature above 200° C. The surface of the portion is then heated to an austenising temperature and quenched, resulting in a hardened surface. The method can be used to manufacture a steering rack from a round bar of steel. The technical effects of the invention include improved strength and durability of the steel component, as well as improved manufacturing efficiency and cost-effectiveness."
Problems solved by technology
A problem with induction hardening gear teeth is that it is difficult to obtain even hardness depth between the tips and roots of the teeth.
Another problem is that heating and quenching the surface of an otherwise cold component may cause cracking or excessive distortion.
The disadvantage of this method is the additional cost and complexity of the induction hardening equipment.
The component is thus heated twice, once to reach the forging temperature and again for induction hardening, which wastes energy.
Method used
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Embodiment Construction
[0037] The invention will be described as applied to steering racks. However, the invention is equally applicable to other forged steel components requiring surface hardening, and in particular to other components that may be made with net shape forged gear teeth such as bevel gears, ring gears, crown wheels, hypoid gears, steering pinions or differential pinions.
[0038]FIG. 1 schematically illustrates a method of manufacturing a surface hardened forged steel steering rack in accordance with the present invention comprising steps 1 to 5.
[0039] Step 1 comprises heating a steel blank in the form of a round bar to a temperature above 600° C. Preferably the bar is heated to a temperature between 600° C. and 1000° C. suitable for warm forging, and more preferably between 750° C. and 850° C. Preferably heating is done by induction and only the portion of the bar that will be forged is heated. The round bar is made from a medium carbon steel suitable for induction hardening, such as SAE 1...
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Abstract
A method of manufacturing steel components particularly suited to components such as steering racks having net shape forged gear teeth. The method comprising heating at least a portion of a steel blank to a first temperature of at least 600° C., forging the portion to shape, cooling the portion in a controlled manner to a second temperature above 200° C., then immediately heating at least part of the surface of the portion to an austenising temperature, and then quenching the portion to harden the surface.
Description
TECHNICAL FIELD [0001] The present invention relates to a method of manufacturing surface hardened forged steel components, and in particular it relates to manufacturing components having forged gear teeth, such as steering racks. BACKGROUND [0002] Surface hardening steel components by induction hardening is well known. The process provides a hard, wear resistant outer layer, whilst retaining a relatively soft, tough core, and is well suited to mass production. Induction hardening is typically applied to medium carbon steels, having between 0.3% and 0.8% carbon (0.3-0.8% C) and more typically about 0.4% C. The theory and practice of induction hardening steel is well known. In brief, induction hardening uses an electrical conductor, usually in the form of a coil with at least one turn, placed close to the surface area to be hardened and energised by an electric current at a suitable frequency. This heats the surface layer of the steel component above the austenising temperature, whic...
Claims
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IPC IPC(8): C21D7/13
CPCB21K1/767C21D1/06C21D1/10C21D1/18C21D1/20C22C38/18C21D8/00C21D9/0068C21D9/32C21D2211/008C21D7/13Y02P10/25C21D1/02
Inventor POLLARD, KENNTH BRIAN THOMPSON
Owner BISHOP INNOVATION PTY LTD