Abstract: An alloy screw producing method includes a head forging step in which a head working for forming a head portion of a screw on a wire made of magnesium-based alloy obtained by drawing is carried out by warm working to produce a screw blank, and a thread rolling step in which thread rolling for forming screw thread on the screw blank is carried out by warm working to produce a screw. The head working in the head forging step is carried out using holding die which fixes the wire and a punch which forms a head portion of the screw. The holding die and the punch are heated, in which at least the holding die are heated to 140° C. or higher and 250° C. or lower.

Abstract: [Problems] It is an object of the invention to provide a producing method of a magnesium-based alloy screw capable of producing a screw made of magnesium-based alloy having excellent strength with excellent productivity, and to provide a magnesium-based alloy screw. [Means to Solve the Problem] The producing method includes a head forging step in which a head working for forming a head portion of a screw on a wire made of magnesium-based alloy obtained by drawing is carried out by warm working to produce a screw blank, and a thread rolling step in which thread rolling for forming screw thread on the screw blank is carried out by warm working to produce a screw. The head working in the head forging step is carried out using holding die which fixes the wire and a punch which forms a head portion of the screw. The holding die and the punch are heated, in which at least the holding die are heated to 140° C. or higher and 250° C. or lower, thereby heating the wire to 140° C. or higher and lower than 250° C.

Abstract: A self-threading screw comprises a screw main body of metal having a small heead portion in the proximal end of a threaded shank and a head of synthetic resin material fitted onto the small head portion. The synthetic resin head has a polygonal socket wrench engaging means formed on the circumferential peripheral thereof. The small head portion has a rotary tool engaging means so that a rotary tool can engage with the engaging means of the small head portion when the synthetic resin head is cut open. The synthetic resin head has an annular seal face formed in the bottom thereof while a stopper porton is provided having a greater diameter than that of the shank portion and extending downwardly of the seal face. Additionally, an annular packing is mounted beneath the seal face so that the stopper face is located between the seal face and the bottom face of the packing.

Abstract: There is disclosed herein a drill screw which comprises a threaded shank, a drilling portion formed at the forward end of the shank and a head formed at the rearward end of the shank and having a wrench head. The drilling portion includes a body extending axially from the shank, a drilling tip extending forwardly from the body and having a pair of diametrically opposite axially extending flutes. In this arragement, horizontal end cutting edges are provided at the forward end of the drilling tip whereas no web is provided at the forward end thereof. Inclined cutting edges are provided at opposite side edges of the drilling tip and side cutting edges are provided at opposite side edges of the body. The end cutting edges, the inclined cutting edges and the side cutting edges all lie in a diametral axial plane of the drilling portion while cooperating together to form rake faces inclined to cutting surfaces which form the bottom of the flutes.