| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a base shape for an outer ring of a bearing capable of enhancing the yield and the productivity and reducing the manufacturing cost by the cold forging from a seamless steel tube formed of bearing steel or the like. Ž<P>SOLUTION: The seamless steel tube 1 formed of bearing steel and having the outside diameter a and the inside diameter b is cut off with the predetermined width c orthogonal to its center axis to simultaneously manufacture a plurality of cut rings. Then, the cut rings 2 are subjected to the shot blasting to remove annular-shaped burrs remaining on an inside diameter surface 22 of each cut ring 2, and the outside diameter surface 21 and the inside diameter surface 22 of each cut ring 2 are subjected to lathe turning to the predetermined diameter, and a decarburized layer on the surface and any surface defect are removed to form a lathe-turned ring 3. Each cut ring is further subjected to the shot blasting, and still further subjected to the phosphate processing or the single lubrication processing as the lubrication processing to form a blank 4 before the cold forging. Then, an inside diameter surface 42 is subjected to the cold ironing molding between a punch 6 and an ejector 7 to form a base shape 8 for an outer ring of a bearing while an outside diameter surface 41 of the blank 4 before the cold forging is restrained by the die 5. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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