| 摘要 |
PURPOSE:To expand a two face part without any underfill and to prevent the building-up of an end face by forming the relation in the outer diameter at the head side of the two face part of a blank, the outer diameter at the handle side and the inner diameter at the shoulder part of a lower die in a taper shape, subjecting the two face to ironing in main forming and forming the face of the two face part in parallel. CONSTITUTION:A blank 1d becomes of what a two face part 2d and head part 6d are formed after passing a preforming stage. In the case of taking the outer diameter of the head side 3d of the two face part 2d as A, the outer diameter of the handle side 4d as C and the inner diameter of the shoulder 25 of the lower die 24 for ball stud main forming at the following stage as B the forming is executed so as to attain to A >B>C. The blank 1d is then set inside the die milling part of a ball stud main forming lower die 24, a ball stud main forming upper die 20 and a slide knockout pin 23 are acted and a spherical head 6e is formed by upsetting the head 6d in the axial line direction. Simultaneously the two face part 2d is subjected to ironing to form the taper faces 5d and 5d in parallel faces 5e, 5e.
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