| 摘要 |
PURPOSE:To prevent generation of cracks in the column of a connecting rod of an internal combustion engine for vehicles by setting the pitch between both holes of a hot molding of the connecting rod at the size slightly larger than the pitch between the cores of forging dies at the time of producing the above- mentioned connecting rod by sintering and forging of a powder molding. CONSTITUTION:The connecting rod 1 for the internal combustion engine, which has a crank pin bearing hole 12 at a large end 9 and a piston pin bearing hole 13 at a small end 10 and has the intermediate part consisting of the slender column 11 is produced by molding, sintering and forging in accordance with a powder metallurgical method. The pitch A between the center of the hole 12 and the center of the hole 13 of the hot molding 1a is set larger by about 0.5-1.0% than the pitch B between the center of the large core 2 and the center of the small core 3 in the forming dies 8. Since no pulling tension is exerted to the hot molding 1a as a forging stock, the generation of the cracks in the column 11 of the rod 1 and the consequent degradation of the strength and the generation of the defective connecting rod are prevented.
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