| 摘要 |
PURPOSE:To form easily the shape of cut end of a hook into prescribed dimensions and shapes, by inserting a mandrel between the inside of a curved rod material and rod material-delivering hole and cutting the material, in manufacturing a coiled spring having hooks at both ends. CONSTITUTION:In processing a rod material into a coiled spring having hooks consisting of a front hook (a), a rear hook (e), and a spirally curved part (c); a curved-part forming tool 5, the 1st forming tool 8, a mandrel tool 9, and plural forming tools and a cutting tool 13 of the 2nd forming tool 15 are respectively attached to an attaching surface 1 placed in the direction perpendicular to that of the material feeding by arranging them radially from a rod material delivering hole set as a center. In processing the material, which is delivered from the delivering hole, into the coiled spring having holes, the cutting tool 13 is arranged so as not to form an about 1/4 portion of the rear hook (e) and to leave the 1/4 portion of arc behind by inserting a mandrel so that it touches at the back side of the hook, and a cutting direction is shifted by 90 deg. to form an arced part at the tail end of the rear hook (e) when the coiled spring is cut. Thus the rear hook (e) is formed into the prescribed arced hook free from a straight part. |
