| 摘要 |
<p>PURPOSE:To improve productivity, to cut superfluous material, to strengthen a shaft part, and to prevent damage to a screw part by forming a longitudinal hole, head, base, and lateral holes, and then by forming the screw part by rolling. CONSTITUTION:The front end part of a rod material 10 cut into a predetermined length is chamfered by providing a face on the front end part of a shaft part 12 by a header process, and a recessed part is formed in the center of the front end part. A longitudinal hole 16 is formed by header process, and a hexagonal head 11 and a hexagonal hole 11a of the center of the head are formed. Lateral holes 17 of the elliptic shape are formed axially symmetrically at two points by punching so that they orthogonally cross the vertical hole 16 in the vicinity of the bottom. Deburring of the lateral hole 17 is carried out by a shot blast method. A screw part 15 is formed by rolling, on which surface treatment (plating) is carried out, and an eye bolt product is thus manufactured. A material corresponding to the volume of the longitudinal hole 16 is saved, while the cross section of a small diametral part 1 at the position of the lateral hole 17 is increased.</p> |
