| 摘要 |
<p>A method for manufacturing a valve for which a mold (40) equipped with a die (42) provided with pressing projections (43) that form an umbrella-part face (16) and equipped with 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 the umbrella-part face (16), wherein 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).</p> |
