COLD-FORGING MOLDING METHOD OF GEAR

To achieve a cold-forging molding method of a gear which can easily manufacture a gear.SOLUTION: A cold-forging molding method of a gear includes a step of pushing a material M with a first punch 2, and swelling excess thickness of the material M in the periphery of the first punch 2 while molding a part of a spline on an outer peripheral surface of the material M, a step of pushing the material M with a second punch 3, and forming a work hardening part 11 while forming a groove part 10 on a surface on the side of the second punch 3 in the material M, and a step of pushing the material M with the first punch 2, and breaking the excess thickness of the material M with the work hardening part 11 as a start point while molding a residual part of the spline on the outer peripheral surface of the material M.SELECTED DRAWING: Figure 6 【課題】容易に歯車を製造可能な歯車の冷間鍛造成形方法を実現する。【解決手段】本開示の一形態に係る歯車の冷間鍛造成形方法は、第１のパンチ２で素材Ｍを押し込み、素材Ｍの外周面にスプラインの一部を成形しつつ第１のパンチ２の周辺に素材Ｍの余肉を盛り上がらせる工程と、第２のパンチ３で素材Ｍを押し込み、素材Ｍにおける第２のパンチ３の側の面に溝部１０を形成しつつ加工硬化部１１を形成する工程と、第１のパンチ２で素材Ｍを押し込み、素材Ｍの外周面にスプラインの残りの部分を成形しつつ加工硬化部１１を起点に素材Ｍの余肉を破断させる工程と、を備える。【選択図】図６