Method of manufacturing a valve for an internal combustion engine

摘要

A method of manufacturing a valve for an internal combustion engine, comprises: (i) a primary step of forging a bulging portion at one end of a rod material to form a generally disk-shape valve head of the valve having a tapered periphery; (ii) an thickness adjustment step of machining an excessively thick portion of the valve head; and (iii) a secondary step of forging a peripheral region of the valve head to create radial slip deformations therein to form a valve face of the valve head. In the step of thickness adjustment, only the front end of the disk-shape valve head is machined without harming dense grain flow lines induced in the tapered face (16a) in the primary forging while advantageously saving the valve material and reducing thickness adjustment time. In the secondary forging, the hardness of the valve face is further enhanced.

主权项

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.