| 摘要 |
<p>OBJECT: To provide a method of manufacturing a valve for an internal combustion engine, the valve being highly hardened from the surface of its valve face to a deep region MEANS OF ACHIEVING THE OBJECT: A valve face (16) of an intermediate valve product W3 is forged, utilizing a die unit (40) equipped with a die (42) having protruding pressing sections and with a press punch (48), so as to create radial slip deformations therein The die (42) also has grooves (46) formed along the circumference of the die such that the grooves (46) and the pressing sections alternate. During forging, the intermediate valve product W3 is repeatedly rotated through a predetermined angle relative to the die (40) in synchronism with the punch (48) in operation. By virtue of the protruding pressing section (43), the die (42) can provide the valve head with larger plastic deformations in a deeper region than conventional dies, thereby hardening the deeper layers as well as shallow layers of the valve face. Although deformations of the valve face (16) deformed once by the protruding pressing sections 43 are discontinuoously distributed along the periphery of the valve head, the valve face 16 becomes uniformly deformed after it is repeatedly rotated relative to the pressing protrusions 43 during forging.</p> |
