| 摘要 |
PROBLEM TO BE SOLVED: To finish an internal gear quickly by finish-forming through forging the internal gear having teeth on the inner periphery. SOLUTION: An inner die 1 formed with internal gear forming teeth 2 on the outer peripheral face and an annular outer die 10 is arranged to be fit while holding a prescribed forming clearance S on opposing one pressure receiving plate 3 side, a core metal 4 is fit to the shaft center of the inner die 1, the inner peripheral face of the inner die 1 corresponding to the internal gear forming teeth 2 and the outer peripheral face of the core metal 4 are brought into contact through a taper face 7 contracting in the direction 25 of other pressure receiving plate, the outer periphery of the outer die 10 is fit to a bracer 12, the outer peripheral face of the outer die 10 corresponding to the internal gear forming teeth 2 and the inner peripheral face of the bracer 12 are brought into contact through a taper face 13 expanding in the direction of the other pressure receiving plate 25, and a first punch 26 capable to be fit to the forming clearance S and second punch 27 and a third punch 28 pressing the outer die 10 and the inner die 1 are provided on the opposing other pressure receiving plate 25.
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