| 摘要 |
PROBLEM TO BE SOLVED: To provide an apparatus and a method for forging a gear by which the forming precision of the gear and the durability of an inner punch can compatibly be improved. SOLUTION: The gear forging apparatus 1 is provided with; a punching-core 2; the inner punch 31; an outer punch 32; a die 5; and a die-sleeve 6. The outer punch 32 is formed of an outer circumferential side portion 83 on the upper-end surface 801 in the axial direction of a blank 80 for gear by receiving the pressurizing force with a first pressurizing source. The inner punch 31 is formed of an inner circumferential side portion 82 at the upper-end surface 801 in the axial direction of the blank 80 for gear with a second pressurizing source generating smaller pressurizing force in the comparison with the first pressurizing source. The punching-core 2 is formed of an annular recessed part 21 caved to the inner circumferential side into the lower position from the vicinity of the inner circumferential side position to the lower end surface of the inner punch 31, on the whole circumference on the outer circumferential surface. When the gear 8 is formed, the annular recessed part 2 is held in the state being opposed to the upper-side portion of the inner circumferential surface 803 of the blank 80 for gear. COPYRIGHT: (C)2009,JPO&INPIT
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