Patent ID: 9015940
Filing Date: 2015-04-28
Classification: B21J,B21K,B23P,F01L,Y10T

Abstract:
1. A method of manufacturing a valve for an internal combustion engine, comprising: a step of primary forging in which a bulging portion at one end of a rod material is forged to form a generally disk-shape valve head of the valve by means of a primary forging die unit having a first die and a first punch; a step of adjusting a thickness of the disk-shape valve head formed in the step of primary forging by machining an excessively thick portion thereof; and a step of secondary forging in which a periphery of the disk-shape valve head is forged to create therein radial slip deformations by means of a secondary forging die unit having a second die and a second punch, the periphery being associated with a valve face that comes into contact with a valve seat of the internal combustion engine, the method further comprising: the primary forging die unit is provided on the first die thereof for forging the valve head with a peripheral taper forming face for forming a tapered face associated with the valve face; and a predetermined tapered face that corresponds to the valve face is formed in the step of primary forging along the periphery of the disk-shape valve head, in conjunction with the valve head and in preparation for the secondary forging; and only a front end opposite the valve face of the disk-shape valve head formed in the primary step is machined in the step of adjusting the thickness.