| 摘要 |
<p>PROBLEM TO BE SOLVED: To reduce rolling failures to a columnar screw stock when forming a double-end threaded body so as to be capable of performing mass production of the double-end threaded body in a high accuracy.SOLUTION: A double-end threaded body D is rolled by use of a die member 10 including a stiff surface which is relatively displaced with respect to a screw stock B while being brought into press-contact with the screw stock B. The die member 10 includes a double-end threaded part formation region U where a plurality of recess parts 30, which are an approximately parallelogram shapes when viewed in the direction normal to a virtual surface 22 obtained by connecting outermost parts of the surface and are recessed from the virtual surface 22, are arranged along a direction of the relative-displacement. The die member 10 includes a region where an array pitch of the recess parts 30 in the direction of the relative-displacement in the double-end threaded part formation region U is decreased from the upstream side to the downstream side when being relatively displaced with respect to the screw stock B.</p> |
