METHOD OF MANUFACTURING SINTERED BEARING WITH DYNAMIC PRESSURE GROOVE

摘要

PROBLEM TO BE SOLVED: To securely and efficiently form dynamic pressure grooves on a bearing material even if it has no or less spring-back. SOLUTION: A core rod 20A having a groove 21 and convex projection 22 side by side on its outer circumferential surface is inserted into the cylindrical bearing material 15. Subsequent compression of the bearing material 15 in a die opening 5a results in pressure bonding of the material 15 to the core rod 20A. A bearing surface 11a and the groove 12 are transfered on to the inner circumferential surface of the material 15. The material 15 is released from die 5, and the core rod 20A is removed from the material 15. The depth of the groove 21 is set to be larger than a half of the amount of spring-back exhibited by the inner diameter of the bearing surface 11a when the outer circumferential surface of the material 15 is released from die 5. The bearing surface 11a is sized or shaved by convex projection 22 of core rod 20a during the removal of the core rod 20A from the material 15.