Wood screw

Abstract

The invention provides a wood screw which cannot damage tightening performance in fastening state and can restrain the reduction of pulling resistance strenth after tightening. The wood screw (1) comprises a head (3) on one side of a shaft (2) and comprises a front end (4) on the other side, screw thread (5) spreads from the front end (4) of the shaft (2), cutting grooves (7) are respectively arranged with intervals on a plurality of axial positions along the shaft (2) and on the screw thread (5) of the shaft (2), the cutting grooves (2) have lengths which can make a plurality of scread threads (5) to be cut and are deeper than grooves of the scread threads (5), and grooveless screw thread (5a) are left between the ends of the cutting grooves (7) abutted along the axial direction of the shaft (2).

Description

technical field [0001] The present invention relates to a wood screw capable of improving screw-in performance during fastening and suppressing a decrease in tensile strength after screwing in. In addition, the present invention relates to suppressing the generation of screwing resistance caused by chips generated during screwing and making A wood screw with improved screw-in performance during fastening. Background technique [0002] A general wood screw used for fastening wooden materials has a structure including: a shaft portion having a predetermined length required for fastening, a head for receiving rotation provided at one end of the shaft portion, and a The tip portion of the other end of the shaft portion is provided with screw threads extending from the tip portion to the shaft portion. [0003] If such a wood screw is directly screwed into a wooden material without a pre-drilled hole, the shaft part enters through the self-tapping function of the thread teeth. A...

AI Technical Summary

Problems solved by technology

[0010] However, the wood screw of Patent Document 1 has a structure in which a plurality of cutting grooves are arranged at equal intervals along the circumferential direction at the position of the tapered front end, so when screwing in, only the ratio of the shaft portion and the screw thread can be used. The small diameter of the outer diameter cuts the inside of the wood material, and the cutting groove has a small storage capacity for cutting chips, so the chips stored inside the cutting groove will fill the cutting groove, and the cutting groove will be cut at the initial stage of screwing. The cutting function of the shaft is reduced, and in addition, it is necessary to screw in the longer shaft part provided with the thread teeth with respect to the shorter front end, so there is little function of reducing the screwing resistance of the shaft part and preventing the cracking of the wooden material. The problem

[0011] In addition, the wood screws of Patent Documents 2 and 3 have a structure in which a plurality of short cutting grooves extending from the boundary between the front end portion and the shaft portion toward the head side are provided at equal intervals in the circumferential direction, so when screwing in initially, It can be cut with a diameter that matches the outer diameter of the shaft and thread, but if the chips stored in the cutting groove completely fill the cutting groove, the chips generated later will invade the shaft and thread that enter the cutting groove The interface between the outer periphery of the tooth and the interior of the wooden material acts as a resistance to the screwing of the shaft, and there is a problem that the function of reducing the generation of screwing resistance is small.

[0012] Furthermore, in the wood screw of Patent Document 4, the inclined cutting groove is provided over the entire length of the thread formation portion of the shaft portion, and the chips are sequentially discharged to the outside by the cutting groove when screwing into a wooden material, so that the shaft can be reduced. However, due to the existence of cutting grooves throughout the entire length of the thread teeth, the contact area between the shaft and the thread teeth and the wooden material is reduced. After screwing in, the wood screw is proportional to the reduction in the contact area. The tensile strength is reduced

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