| 摘要 |
PURPOSE:To manufacture a roughly formed material of a connecting rod without requiring machining by placing the head on the base end of bar-like material, restraining just under it, upsetting the middle part of the shaft, and after forming an undercut part right under the head, drawing the middle part of the shaft. CONSTITUTION:After upsetting the head 2 on the base end of a bar material 1, a part right under the head is restrained, and a part which is nearer to the tip than the part 11 right under the head 2 in the header is bulged out by upsetting. The bar material 1 for which working of undercut part 36 is completed is taken out from the header. Then, clamping under the thread 3, clamping of connecting rod fitting part 4 and head trimming 6 are made to complete manufacture of a roughly formed material of the connecting rod bolt. As the undercut part 36 is formed right under the head 2, no remaining part of drawing of the shaft occurs, and accordingly machining for removing it is not necessary. |
