| 摘要 |
PCT No. PCT/JP81/00027 Sec. 371 Date Oct. 13, 1981 Sec. 102(e) Date Oct. 13, 1981 PCT Filed Feb. 17, 1981 PCT Pub. No. WO81/02450 PCT Pub. Date Sep. 3, 1981.A pair of nail shank pieces are united face to face through the intermediary of a strip metal, and the tip parts of both nail shank pieces are tapered so that both nail shank pieces may be gradually opened as the nail is driven in. The metal strip is subjected to a compressive deformation to support the nail shank pieces from inside, thereby helping in their maintaining an opened state. Both nail shank pieces engage the base material in a dovetail fashion and in this way, the countering force against the nail's coming out is reinforced. A clamping ring fit around the outer circumference of both nail shank pieces to hold the metal strip therebetween such that both nail shank pieces are prevented from opening at the base material surface, and moreover, the opening made by the nail at the base material surface is protected from widening, while aiding in both nail shank pieces entering deep into the base material. |
