FORGING METHOD

PROBLEM TO BE SOLVED: To provide a forging method for furthermore reducing an underfill part from a formed product. SOLUTION: A material 16 is fed in a forming space 17 formed of a die 11 and a pair of pressing punches 13, 14 provided movably on the die 11, and the material 16 is pressed by the pressing punches 13, 14 to form a product in the forming space 17. In the pressing step, a preceding punch 15 provided on the upper pressing punch 13 is projected from the pressing punch 13 in advance, the material 16 is pressed by the pressing punches 13, 14, and the preceding punch 15 is inserted in the material 16. Thereafter, in a flow-splitting step, by splitting flow of the material 16 in a locus space of the preceding punch 15 formed when depressing the preceding punch from the material 16 into the pressing punch 13 during the pressing of the material 16, the flow toward an underfill space 18 formed in a corner of the forming space 17 is imparted to the material 16. The ratio of the volume of the locus space of the preceding punch 15 to the volume of the underfill space 18 is set to be a value in the range of ≥20 to ≤100. COPYRIGHT: (C)2011,JPO&INPIT