| 摘要 |
PROBLEM TO BE SOLVED: To provide a technology of easily manufacturing a crankshaft that has a large diameter eccentric part and a hollow part penetrating both ends.SOLUTION: A crankshaft includes: a shaft part; a large diameter eccentric part whose diameter is larger than the shaft part and is eccentric from the shaft part; and a hollow hole that penetrates both ends. For manufacturing the crankshaft, a hollow pipe having a hollow hole that penetrates both ends is prepared. Subsequently, a projected part whose outer and inner peripheral surfaces are projected outwardly is formed by performing upset forging on the prepared hollow pipe, and the large diameter eccentric part having the hollow hole is formed by performing the upset forging on the projected part. |
