| 摘要 |
PROBLEM TO BE SOLVED: To form surely and efficiently a dynamic pressure groove, even when a bearing member has a small spring back amount or hardly has it. SOLUTION: A core rod 20A provided with a groove 21 and a projection 22 on an outer peripheral surface is inserted in a cylindrical bearing member 15. The bearing member 15 is compressed in a die hole 5a, so that the bearing member 15 is pressed on the core rod 20A to transfer a bearing surface 11a and a dynamic pressure groove 12 on the inner peripheral surface of the bearing member 15. Then, an outer peripheral surface of the bearing member 15 is released from the die, and the core rod 20A is drawn out while both of end surfaces of the bearing member 15 are pressed by upper and lower punches. Since an enlarging diameter amount of the bearing member 15 increases by pressurization in addition to spring back, draw of the core rod becomes possible and easy. As a result, a dynamic pressure groove can be surely formed.
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