| 摘要 |
PROBLEM TO BE SOLVED: To provide an efficient producing method of a coil spring capable of increasing natural oscillation frequency while preventing or reducing concentration of local stress upon elastic deformation operation.SOLUTION: The method includes a spiral formation process for forming a spiral object comprising a fixed spiral part, a first movable spiral part and a second movable spiral part from a straight long member 100 in a manner that an approximately straight long member 100 is transported to one side in a first direction along a longitudinal direction by a pair of transporting rollers 120, and one side in a second direction of the long member 100 is engaged with a pressing member 130 moveable in the second direction. In the spiral formation process, the position in the second direction of the pressing member 130 is adjusted, based on a signal from a rotational speed sensor detecting the rotational speed of the transporting rollers 120, in a state of recognizing the relationship between the position in the longitudinal direction of the long member 100 engaged with the pressing member 130 and the position in the circumferential direction after being formed into the spiral object. |
