| 摘要 |
PURPOSE:To obtain a coil spring having high strength by a simple device, by giving reaction force to a twisting rotation of a blank material by a specified contact member, and limiting the distortion quantity of the blank material, when heating a steel coil blank material, and thereafter, coiling it on the way of cooling. CONSTITUTION:A coil blank material 1 is heated up to a temperature at which it is converted to austenite, and thereafter, is cooled suddenly, and is coiled on the way of cooling. Also, a contact member, for instance, rolls 2, 2 are provided in the vicinity of a winding start position of the coiling. In case of a coil wound clockwise in a figure, the blank material 1 executes a twisting motion in the direction f1 together with the coiling, therefore, the rolls 2, 2 are also apt to be driven and rotated in the same direction. Therefore, the coiling is executed simultaneously by giving damping force to the rolls 2, 2 and giving reaction force in the reverse twisting direction against the rotation of the blank material 1, so that total distortion on the surface of the blank material 1 becomes within a range of 0.1-0.4. In this way, the generation of a constricted part, the roughness of the surface, etc. on the surface of the blank material 1 is prevented. In this regard, the blank material 1 is cooled suddenly by a device 3 thereafter. |
