| 摘要 |
PROBLEM TO BE SOLVED: To form a stock for rotation part having a hub part thickened and a rib part thinned by welding/machining from a plate material in a forming method of the stock for rotation part from the plate material. SOLUTION: Prior to forming a hub from a plate material 10, a projecting section 10-2 opposite to a protruding direction of the hub is formed to a center part of the plate material by shallow drawing, successively, by conducting pierce burring while rolling in the projecting section 10-2, the center part of the plate material is protruded in a cylindrical shape, the plate material section protruded in a cylindrical shape is the hub. By holding a cylindrical protruded part to a die while providing a clearance in the radial direction and by strongly pressing, the cylindrical protruded part is made into the hub thickened in the end. Further, a rib part is thinned by plastic working of side ward slippage by a cone shape roller under a low pressure.
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