| 摘要 |
PURPOSE:To stably manufacture the drill screw having an excellent quality by heading head part, a leg part and a drill part of the tip to a cut wire rod, and thereafter, executing a form rolling with a flat die having working teeth and a block tool having the flat face. CONSTITUTION:A cut wire rod 10 is headed by a cold heading machine, and a screw stock 13 having a head part 11 and a leg part 12 is obtained. With respect to this screw stock 13, a drill part 14 is headed in the tip of the leg part 12 by using an exclusive press, etc. A screw stock 16 obtained thereby is charged into a screw form rolling machine, and by a pair of flat dies 1A, 1B provided with working teeth 2 on the form rolling face 3, a tapping screw thread 17 is form-rolled between the head part 11 and the drill part 14. Simultaneously, by a pair of block tools 4A, 4B having a flat face 5, a chip, etc., of the drill part 14 are eliminated and corrected, and also, its outside diameter D is finished to a desired dimension. In such a manner, a drill screw which has the drill part 14 having no burr, etc., and whose outside diameter dimension is stable and in which a prescribed tapping screw thread is provided between the drill part and the head part 11 is obtained. |
