Method of manufacturing a valve for an internal combustion engine

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 the 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 characterized in that
• the primary die unit is provided on the 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.