| 摘要 |
PROBLEM TO BE SOLVED: To provide a method of manufacturing a crank shaft capable of solving a problem associated with twist work by eliminating the need for the twist work. SOLUTION: In the method of manufacturing the crank shaft 1 used for an in-line three-cylinder engine, the crank shaft is forged with the use of a forming die allowing that the gravity centers of three crank parts 3 including a pair of webs 4, 4, a crank pin 5 held and formed between the webs 4, 4, and counterweights 6, 6 formed at sites opposed to the crank pin 5 of the respective webs 4, 4, exist at 120°rotationally symmetric positions with a shaft 2 of the crank shaft 1 as a center, and moreover, the webs 4, 4 and the counterweights 6, 6 are formed into a shape with draft angles interposing a parting line L of the forming die. COPYRIGHT: (C)2012,JPO&INPIT |
