Method for manufacturing valve for internal combustion engine

Abstract

A method for manufacturing a valve is provided. A mold (40) equipped with a die (42) and a pressing punch (48) is used to perform forging whereby slip deformation is produced from the inner circumferential side toward the outer circumferential side of an umbrella-part face (16). The die (42) is provided with pressing projections (43) that form the umbrella-part face (16). The pressing projections (43) and recessed grooves (46) are provided alternating continuously in the circumferential direction on the die (42), and the umbrella-part face (16) is forged while an intermediate valve product (W3) is rotated at a prescribed angle with respect to the mold (40) in coordination with the pressing operation of the punch (48). The amount of elastic deformation of the source material in the depth direction by means of the pressing projections (43) is greater than with a conventional mold (die), and to that extent a higher hardening of the deep part of the umbrella-part face (16) is enabled. The region of plastic deformation separates in the circumferential direction, but the formed surface (forged surface) of the plastically deformed umbrella-part face (16) is smoothed by shifting the pressing location of the pressing projections (43) in the circumferential direction with each pressing operation of the punch (48).

Description

technical field [0001] The present invention relates to a method for manufacturing a valve for an internal combustion engine, and more particularly, to a method for manufacturing a valve for an internal combustion engine in which the hardness of the sheath surface is increased by forging the sheath surface to cause sliding deformation on a billet. Background technique [0002] The umbrella surface of the suction and exhaust valves for internal combustion engines is an important part that opens and closes the combustion chamber in contact with the valve seat, so wear resistance and high temperature corrosion resistance are required. Furthermore, many attempts to improve wear resistance and high-temperature corrosion resistance by specifying the temperature conditions and working ratios of forging have been proposed so far. However, in conventional proposals, the hardness of the umbrella surface is insufficient, combustion residues bite into the umbrella surface, and indentati...

AI Technical Summary

Problems solved by technology

However, in the conventionally proposed solutions, the hardness of the umbrella surface is insufficient, and the combustion residue bites into the umbrella surface, causing indentation, and the blow-by resistance deteriorates, which is particularly noticeable in diesel engines using low-quality fuel.

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