| 摘要 |
PROBLEM TO BE SOLVED: To provide a manufacturing method capable of forming a bearing surface with simple equipment, a few man-hour, and excellent accuracy. SOLUTION: A forming die 21a inserted in an inner circumferential surface of a sintered alloy stock 1' in which the density ratioα(%) is set in a range of 75<=α<85, a pressing force is applied to the sintered metal stock by a die 20 and upper and lower punches 22, 23, and the inner circumferential surfaces is pressed against the forming die 21a and plastically deformed to simultaneously form a formed area of a hydrodynamic groove of the bearing surface and other area. Then, the forming die 21a is released from the inner circumferential surface of the sintered metal stock 1' making use of the spring-back of the sintered metal stock 1' by removing the pressing force.
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