JP2017067190A - Wood screw - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wood screw capable of improving screwing-in performance in fastening by suppressing occurrence of screwing-in resistance resulting from chips occurring in screwing-in.SOLUTION: A wood screw 1 includes a head part 3 at one end of a shaft part 2, and a tip part 4 at the other end, and is provided with a screw thread 5 from the tip part 4 to the shaft part 2. In the wood screw, at a portion of the shaft part 2 where the screw thread 5 is provided, provided is a pair of cutting grooves 7 having a length to such an extent as to part a plurality of threads of the screw thread 5 and having a depth deeper than a trough in the screw thread 5; and arrangement angles of both cutting grooves 7 with a shaft center of the shaft part 2 as a center are set so as to be equal to or less than a right angle within a range where they are not overlapped with each other.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a wood screw that can suppress the occurrence of screwing resistance caused by chips generated during screwing and improve the screwing performance during fastening.

  A general wood screw used for fastening a wood material has a shaft portion having a predetermined length necessary for fastening, a head portion provided at one end of the shaft portion for receiving rotation, and the other end of the shaft portion. And has a structure in which a screw thread is provided from the tip portion to the shaft portion.

  When such a wood screw is screwed directly into a wood material without a pilot hole, the shaft portion enters by the tapping function of the screw thread. At this time, the entering shaft portion pushes the wood material from the inside, and the wood material Depending on the material and screwing position of the wood, there is a risk of causing cracks in the wood material, and because there is no function to cut the wood material fiber in the shaft part, the generation of screwing resistance of the shaft part to the wood material is said to be large There's a problem.

  Conventionally, as a wood screw that solves the above-described problems, a cutting groove having a length that divides a plurality of threads along the axial direction of the shaft portion is provided in a portion where the thread portion of the shaft portion or the tip portion is formed. At the edge of the cutting edge located at the rear of the cutting groove in the screwing direction, when cutting into the wood material, cutting the thread inside the wood material while cutting the fiber where the shaft part enters, Chips generated by cutting are discharged to the outside of the wood material through the cutting grooves, or a part thereof is stored in the cutting grooves. (See Patent Documents 1 to 3)

  Each wood screw provided with a cutting groove as in Patent Documents 1 to 3 as described above cuts the interior of the wood material with the cutting edge of the cutting groove when screwed, compared to a general wood screw. Even if it is screwed in without removing the process, there is an advantage that the occurrence of screwing resistance of the shaft part to the wood material is reduced, and the wood material can be prevented from cracking by cutting the inside of the wood material. Since the cut chips are discharged to the outside through the cutting grooves, the function of reducing the occurrence of the screwing resistance is further improved.

JP 2014-1119023 A JP 2003-139117 A Utility Model Registration No. 3153125

  However, the wood screw of Patent Document 1 has a structure in which a plurality of cutting grooves are provided at equal intervals in the circumferential direction at the position of the tip portion formed in a conical shape. The inside can only be cut with a diameter smaller than the outer diameter of the shaft or thread, and the cutting groove has a small storage capacity for the chips produced by the cutting, so surplus chips are placed between the wood and the thread interface. This bites in and increases the screwing resistance.

  In addition, the cutting groove provided only at the short tip must be screwed in the long shaft part provided with the thread in the state where the cutting groove is filled with chips at the initial stage of screwing and the cutting function is lowered. The wood screw like 1 has a problem in that it has a small function of reducing the screwing resistance of the shaft portion and preventing the wood material from cracking.

  Next, the wood screws of Patent Documents 2 and 3 have a structure in which two to four short cutting grooves extending from the boundary between the tip portion and the shaft portion to the head side are arranged at equal intervals in the circumferential direction. Therefore, at the initial stage of screwing, cutting can be performed with a diameter commensurate with the outer diameter of the shaft portion or thread, but the circumferential arrangement angle of adjacent cutting grooves becomes a right angle or more, and in this way, the interval between adjacent cutting grooves is When the width is increased in the circumferential direction, the distance until the chips cut in each cutting groove are stored in the cutting groove in the next position in the screwing direction becomes longer. Therefore, between the cutting grooves, the outer periphery of the screw thread and the wood material There is a problem that the chips that have digged between the internal interfaces move to the rear in the screwing direction of the wood screw, and this becomes resistance to screwing of the shaft portion, and there is little function to reduce the generation of screwing resistance.

  Therefore, the object of the present invention is to provide two cutting grooves in the shaft portion in a state in which the circumferential interval is close, and the chips generated by the cutting grooves positioned in the front in the screwing rotation direction are removed by the subsequent cutting grooves. It is an object of the present invention to provide a tapping wood screw that can be stored quickly and reduce the amount of chips from getting into the interface between the outer periphery of the screw thread and the inside of the wood material, thereby greatly improving the screwing performance.

  In order to solve the above problems, the invention of claim 1 includes a shaft portion, a head portion provided at one end of the shaft portion, and a tip portion provided at the other end of the shaft portion, A wood screw provided with a screw thread from the tip part to the shaft part, wherein two cutting grooves are provided at positions spaced apart in the circumferential direction of the shaft part at the part where the screw thread of the shaft part is provided, The two cutting grooves have a length that divides a plurality of threads along the axial direction of the shaft section, and a depth deeper than a valley between the thread threads, with the shaft center of both cutting grooves as the center. The arrangement angle to be set is set to be equal to or less than a right angle within a range not overlapping each other.

  The invention of claim 2 is the same length and depth as the cutting groove at a position different from the adjacent interval set so as to be equal to or less than the right angle of the two cutting grooves at the portion where the thread of the shaft portion is provided. A required number of other cutting grooves having a thickness are provided.

  According to a third aspect of the present invention, a plurality of sets of cutting grooves, each of which is a set of the two, are provided at equal intervals along the circumferential direction of the shaft portion in the portion where the thread of the shaft portion is provided. is there.

  According to a fourth aspect of the present invention, the two cutting grooves and the other cutting groove are provided at a plurality of positions along the axial direction of the portion where the thread of the shaft portion is provided at a distance from each other. In addition, a thread without a groove is left between the end portions of the cutting grooves adjacent to each other in the axial direction of the shaft portion.

  According to a fifth aspect of the present invention, each of the cutting grooves is provided so as to be inclined such that an end portion located on the head side is located behind the end portion located on the tip end side in the screwing rotation direction of the wood screw. It is what has been made.

  According to a sixth aspect of the present invention, the cutting groove provided at a position closer to the tip end side of the shaft portion is such that an end portion located on the tip end side starts from a boundary portion between the tip end portion and the shaft portion. It is what.

  Here, the screw thread of the wood screw is provided in the range of the substantially intermediate part of the shaft part from the tip part, and the head side from the intermediate part of the shaft part is a circular screw-free part, A thread may be provided from the tip to the head without providing the non-threaded thread, and the thread may be either a multiple thread or a single thread.

  Further, each cutting groove provided in the shaft portion is opened to the outer surface side at an opening angle of 70 °, for example, and in the invention of claim 4, the cutting groove is left between the cutting grooves along the axial direction of the shaft portion. The thread without a groove has a length of about 1 to 4 threads, and the cutting groove on the tip side divided in the axial direction by the thread without the groove encloses the chips and stores them inside. The cutting groove on the head side contains excess cutting powder, reducing the occurrence of screwing resistance caused by cutting powder, and at the same time, cutting powder held in both cutting grooves located in the axial direction However, it complements the reduction of the contact area with the wood material of the shaft portion and screw thread due to the cutting groove, thereby suppressing the drop of the pull-out strength of the wood screw.

  Furthermore, by making the angle of arrangement of the two cutting grooves close to a right angle or less, it becomes possible to sharpen the space between the two cutting grooves in the screw thread during the manufacture of the wood screw. The cutting efficiency of the material fibers and the storage function of the chips can be improved.

  According to the wood screw of the first aspect of the present invention, the length where the plurality of threads are divided along the axial direction of the shaft portion and the depth deeper than the valley between the threads are provided in the portion where the thread portion of the shaft portion is provided. The two cutting grooves have been provided, and the arrangement angle centered on the axial center of both cutting grooves was set to be close to a right angle or less, so the wood material cut by the cutting groove located at the tip of the screwing direction Chips can be quickly concentrated and stored in this cutting groove and the cutting groove at the next position, and the generation of chips that bite between the outer periphery of the shaft and screw threads and the interior of the wood is minimized. Thus, it is possible to prevent the chips from becoming screwing resistance and to smoothly screw in without impairing the screwing performance.

  Further, according to the inventions of claims 2 and 3, by providing two cutting grooves and another cutting groove, or by further providing two cutting grooves, the cutting efficiency at the time of screwing and the chip storage efficiency can be improved. Therefore, it can be screwed more efficiently and smoothly.

  According to the invention of claim 4, the chips filling each cutting groove are confined and come into contact with the inner periphery of the wood material, so that the cutting groove is provided, so that the shaft portion and the thread wood material can be reduced. The reduction of the contact area can be complemented, and the improvement of the fastening force after screwing and the reduction of the pull-out strength can be suppressed, and the pull-out strength equivalent to that of a wood screw without a cutting groove can be ensured.

  Further, according to the invention of claim 5, by providing the cutting groove at a position separated in the axial direction, the cutting groove can be secured long in the axial direction of the shaft portion, so that a storage volume commensurate with the amount of chips generated is ensured. Thus, the chips that are confined in the cutting groove and excessively compressed can be prevented from becoming an element of resistance to screwing of the wood screw, and can be screwed smoothly.

  Further, as in the invention of claim 6, when the cutting groove is provided at a position separated in the axial direction and a thread without a groove is left between the cutting grooves adjacent in the axial direction, The shavings of the cut wood material are stored inside with a thread without a groove, and the surplus cutting powder enters between the shaft part and the outer periphery of the thread and the interface between the inside of the wood material. The swarf that enters between the interfaces immediately enters the cutting groove on the head side before it becomes a resistance factor, and the swarf generated at the time of screwing becomes resistance to the ingress of the subsequent shaft and thread. Thus, the screw can be smoothly screwed without impairing the screwing performance.

(A) is a front view of a wood screw according to the present invention, (b) is an enlarged cross-sectional plan view taken along arrow bb in (a). In the arrow b-b of Fig.1 (a), the expanded cross-sectional top view at the time of providing in the arrangement | positioning which the two cutting grooves approached in the circumferential direction of the axial part most closely

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  As shown in the figure, a wood screw 1 includes a shaft portion 2 having a predetermined length and a diameter, a large-diameter head portion 3 provided at one end of the shaft portion, and a sharp portion provided at the other end of the shaft portion 2. A thread 5 that includes a conical tip 4 and ends on the outer peripheral surface of the shaft 2 and the tip 4 from the tip 4 toward the head 3 in the middle of the length of the shaft 2. Are formed in a continuous manner, and a straight circular screw-free portion 2a is formed between the screw thread 5 of the shaft portion 2 and the head portion 3, and an engagement hole of the rotary tool is formed in the head portion 3. 6 is provided.

  In the wood screw 1, a plurality of cutting grooves 7 that are long along the axial direction of the shaft portion 2 are formed in the portion provided with the screw thread 5 of the shaft portion 2 under the condition of the arrangement interval described later in the circumferential direction of the shaft portion 2. The cutting groove 7 is provided with a length that divides the plurality of screw threads 5 along the axial direction of the shaft portion 2 and a depth deeper than a valley between the screw threads 5, and the outer surface of the shaft portion 2. In the case shown in the drawing, the cutting grooves 7 are provided in two sets in an arrangement spaced apart in the axial direction of the shaft portion 2, and between the ends of the cutting grooves 7 adjacent in the axial direction of the shaft portion 2, The example in which the thread 5a without a groove is left is shown.

  As shown in FIG. 1 (b), each of the cutting grooves 7 is a set of two in parallel along the circumferential direction of the shaft portion 2, and two sets of the cutting grooves 7 are provided. It arrange | positions in the symmetrical position on both sides of the axial center of the axial part 2. As shown in FIG.

  Each cutting groove 7 has a V-shaped cross section with an opening angle α opened at an angle of 70 ° or the front and rear thereof from the bottom portion recessed with respect to the valley between the screw threads 5 to the shaft portion 2. And the edge part which the outer peripheral surface of the thread 5 and the opening edge located in the back of the screwing rotation direction of the cutting groove 7 make is the cutting blade 8.

  In the case of FIG. 1A, the cutting grooves 7 provided at a distance in the axial direction of the shaft portion 2 are the ones located on the tip portion 4 side of the thread 5, the first cutting groove group 7 a, the head What is located closer to the third side is the second cutting groove group 7b, and there is no groove between the ends of the first cutting groove group 7a and the second cutting groove group 7b adjacent to each other in the axial direction of the shaft portion 2. The thread 5a is left, and the thread 5b without a groove remains between the second cutting groove group 7b and the unthreaded portion 2a located on the head 3 side over a predetermined length.

  The above-described two cutting grooves 7 are set so that the arrangement angle θ centered on the axis of the shaft portion 2 is not more than a right angle within a range where they do not overlap each other. In the example of FIG. An example in which the arrangement angle θ is set to 80 ° is shown. When two sets of cutting grooves 7 are provided, the adjacent interval θ1 with the counterpart cutting groove is 100 °.

  Moreover, the example of FIG. 2 shows the case where the two cutting grooves 7 are arranged in the circumferential direction of the shaft portion 2 so as to be closest to each other, and the arrangement angle θ is set to 45 °. The adjoining interval θ1 is 135 °. Here, the arrangement angle θ has a lower limit of 45 ° from the relationship between the diameter and height of the thread 5 and the opening angle α of the cutting groove 7, and if the arrangement angle θ is further narrowed, Since the cutting grooves 7 overlap each other at the crest portion, the outer diameter of the thread 5c is reduced, and the screwing function of the thread 5 and the pull-out strength after fastening are reduced.

  If the arrangement angle θ is set to be equal to or less than a right angle in the two cutting grooves 7 as a set, the two cutting grooves 7 are arranged close to each other in the circumferential direction. In the case of manufacturing by manufacturing, a part of the material pushed for forming the cutting groove 7 can be efficiently transferred to the thread forming portion between the pair of cutting grooves 7. The thread 5c between the cutting grooves 7 forming a set can be formed in a sharp edge shape, and there is an advantage that the resistance of the screwing can be reduced by efficiently cutting the fibers of the wood material when screwing.

  As shown in FIG. 1A, the cutting groove 7 of the first cutting groove group 7 a provided near the tip portion 4 side of the shaft portion 2 has an end located on the tip portion 4 side at the tip portion 4. Starting from the boundary between the shaft portion 2 and the shaft 5, the length along the axial direction of the shaft portion is divided so as to divide the plurality of threads 5. In addition to being effectively prevented, the cutting groove 7 of the first cutting groove group 7a further improves the cutting performance when screwed into the wood material, so that the end portion located on the tip portion 4 side is improved. The end portion located on the head 3 side is provided in an inclined shape so as to be positioned at the rear of the screwing rotation direction of the wood screw 1, for example, at an angle of about 17 ° with respect to the axis of the shaft portion. Yes.

  The cutting groove 7 of the second cutting groove group 7b provided near the head 3 side of the shaft portion 2 is also provided under the same length and inclined conditions as the cutting groove 7 of the first cutting groove group 7a. The interval between the adjacent ends of the first cutting groove group 7a and the second cutting groove group 7b is such that the thread 5a without grooves left between them has a length of about 1 to 4 threads. Is set to

  The thread 5 provided on the wood screw 1 is not limited to the double thread as shown in the figure, but may be a single thread or more, and the length and depth of the cutting groove 7 and the shaft portion 2 The number to be arranged in the axial direction can be set as appropriate under the condition that efficient cutting of the wood material when screwed into the wood material of the wood screw 1 and the total amount of chips generated by this cutting can be securely stored. An example of specific numerical values of each part of the wood screw 1 is shown. In the double thread wood screw 1 having a total length of 65 mm and a diameter of the shaft portion 2 of 3 mm, the cutting groove 7 is a length along the axial direction of the shaft portion 2. The depth between the end portions of the first cutting groove group 7a and the second cutting groove group 7b is as follows. It is set to 5.5 mm.

  Further, in the first cutting groove group 7a and the second cutting groove group 7b, two cutting grooves 7 arranged in the circumferential direction of the shaft portion 2 are provided as two sets as shown in the figure. It is not limited to the example shown in the figure, for example, one provided with only two cutting grooves 7 as a set, for further improving the cutting efficiency at the time of screwing and securing the storage space for the chips, A structure in which two or more cutting grooves are basically formed and a single cutting groove 7 or a combination of a plurality of cutting grooves 7 may be combined therewith. It is provided at a position different from the interval between the grooves 7 and below the right angle.

  The wood screw of the present invention is configured as described above, and a method of using the wood screw 1 in the illustrated embodiment will be described.

  When the wood material is screwed from the sharp tip portion 4 to fasten the wood material, the thread 5 formed on the outer periphery of the tip portion 4 bites, and the shaft portion is caused by the screw 5 being screwed. Then, the cutting groove 7 of the first cutting groove group 7a provided on the tip portion 4 side of the shaft portion 2 cuts the wood material with the cutting blade 8, and the thread By cutting the spiral hole according to 5 and the valley diameter, the generation of resistance during screwing is reduced, and the chips generated by the cutting are housed inside.

  The first cutting groove group 7a includes a pair of cutting grooves 7, and the arrangement angle θ of the two cutting grooves 7 is a right angle or less as long as they do not overlap each other. As a result, the pair of cutting grooves 7 are close to each other in the screwing rotation direction, and the wood material fibers are efficiently cut by the sharp screw threads 5c between the adjacent cutting grooves 7. The wood chips cut by the cutting groove 7 positioned forward in the screwing rotation direction can be quickly concentrated and stored in the cutting groove 7 and the cutting groove 7 at the next position.

  By storing such chips, it is possible to minimize the generation of chips that bite between the outer periphery of the shaft portion 2 and the thread 5 and the internal interface of the wood material, and to prevent the chips from becoming screwing resistance. Thus, the wood screw 1 can be smoothly screwed without impairing the screwing performance.

  When the entire length of the first cutting groove group 7a enters the wood material, next, the thread 5a without a groove enters, and the cutting groove 7 of the first cutting groove group 7a is a thread 5a without the groove. By being cut off from the outside, the chips generated by cutting by the further rotation approach of the first cutting groove group 7 a are confined in the cutting groove 7, and the space generated in the shaft portion 2 by the formation of the cutting groove 7. Will be filled with chips.

  The surplus portion of the swarf filling the cutting groove 7 of the first cutting groove group 7a is pushed out to the head side from the interface between the thread 5a having no groove and its valley and the wood material. Since the unthreaded thread 5a is set to be as short as 1 to 4 threads, the excess cutting powder is cut in the second cutting groove group 7b at the next position before it becomes a resistance element against screwing of the shaft portion 2. It is stored in the groove 7.

The second cutting groove group 7b provided on the head 3 side enters the thread 5a having no groove, and proceeds along the spiral hole through which the thread 5a having no groove has passed. The cutting groove 7 of the cutting groove group 7b accommodates the above-described excess cutting powder so that the cutting powder does not become a resistance element against screwing of the shaft portion 2, and the cutting groove group 7b of the second cutting groove group 7b When the full length of the part enters, the thread 5b without a groove on the head 3 side enters subsequently, the cutting groove 7 of the second cutting groove group 7b is cut off from the outside, and the chips inside are confined. It is done.

  At this time, also in the second cutting groove group 7b, similarly to the first cutting groove group 7b, the two cutting grooves 7 are provided with a set of cutting grooves 7, and the two cutting grooves 7 are arranged as a set. The angle θ is set to be equal to or less than a right angle within a range where they do not overlap with each other, and a structure in which the two cutting grooves 7 are close to each other in the screwing rotation direction makes it possible to obtain a sharp screw between the adjacent cutting grooves 7. The crest 5c can be provided, and the chips generated by cutting are cut into fine pieces, and the wood material chips cut by the cutting grooves 7 positioned in the front in the screwing rotation direction are separated from the cutting grooves 7 and the next position. The cutting grooves 7 can be quickly concentrated and stored.

  Moreover, the distance of the circumferential direction of the thread 5c located between the two cutting grooves 7 which make a pair becomes close by making the space | interval of the cutting grooves 7 which two make a set approach the arrangement | positioning space | interval of a cutting groove. Can be shortened as compared with the conventional one provided at an arrangement interval of 90 ° or more. Thus, when the circumferential length of the thread 5c located between the cutting grooves 7 is shortened, the wood screw 1 At the time of screwing, the contact condition of the screw thread 5 to the wood material becomes uneven in the circumferential direction, and the screw thread 5c approaches the condition of line contact from the surface contact to the wood material. For example, as shown in FIG. When the spacing between the cutting grooves 7 as a set is set to 45 °, the thread 5c between the cutting grooves 7 has a sharp edge shape at the outer peripheral portion, and this portion is projected when screwed into the wood material. By acting, a guide function is created and screwing efficiency can be improved. The

  In addition, the arrangement of the cutting grooves 7 in the second cutting groove group 7b is not limited to the illustrated example in which two sets of two are provided as one set. In order to further improve the cutting efficiency during screwing and to secure a storage space for cutting chips, a pair of cutting grooves is basically used as a single cutting groove. A structure in which one or a plurality of 7 is combined may be used.

  As described above, also in the second cutting groove group 7 b, two sets of cutting grooves 7 are provided on the thread 5 of the shaft portion 2 of the wood screw 1, and the shaft centers of both cutting grooves 7 are centered. The cutting angle of the wood material cut by the cutting groove 7 positioned at the tip of the screwing rotation direction is set between the cutting groove 7 and the cutting groove 7 at the next position. It can be quickly concentrated and stored, and by reducing the generation of chips that bite between the outer periphery of the shaft portion 2 and the thread 5 and the internal interface of the wooden material, the chips can be screwed in. Therefore, the wood screw 1 can be smoothly screwed without impairing the screwing performance, and even if the circumferential length of the thread 5c is shortened, the cutting grooves 7 contain the chips in a confined manner, so that the fastening is possible. There will be no reduction in the subsequent pull-out strength.

  Further, by making a screw thread 5b having no groove between the second cutting groove group 7b and the unthreaded portion 2a located on the head 3 side, the cutting groove 7 in the second cutting groove group 7b is set to the outside. It is possible to shut off, and by confining the chips in the cutting grooves 7, it is possible to prevent the chips generated by the screwing of the shaft portion 2 from becoming a resistance element against the screwing.

  Furthermore, the 1st cutting groove group 7a and the 2nd cutting groove group 7b provide the 1st cutting groove group 7a and the 2nd cutting groove group 7b by hold | maintaining the chip produced by cutting inside. As a result, the amount of contact area between the shaft 2 and the wood material is reduced by cutting powder, and the amount of the contact area is supplemented to ensure the fastening strength and maintain the pull-out strength after fastening. Will be able to.

  Although not shown, in the case of a wood screw having a structure in which only two sets of cutting grooves 7 or only the first cutting groove group 7a are provided on the shaft portion 2, a set of two cutting grooves when the wood screws are screwed in. 7 and the amount of chips generated by cutting with the cutting groove 7 of the first cutting groove group 7a, and when the cutting groove 7 of the pair of cutting grooves 7 and the first cutting groove group 7a is provided, If the chip storage volume set by the length, width and depth of the single unit in the cutting groove 7 is matched in advance, it is possible to prevent chips generated during screwing from becoming a resistance element for screwing, A wood screw can be smoothly screwed in without impairing the screwing performance.

DESCRIPTION OF SYMBOLS 1 Wood screw 2 Shaft part 2a Screwless part 3 Head part 4 Tip part 5 Thread 5a Groove without thread 5b Groove without thread 5c Thread between cutting grooves 6 Engagement hole 7 Cutting groove 7a First cutting groove Group 7b Second cutting groove group 8 Cutting blade

Claims (6)

  A wood screw comprising a shaft portion, a head portion provided at one end of the shaft portion, and a tip portion provided at the other end of the shaft portion, wherein a screw thread is provided from the tip portion to the shaft portion, In the portion where the thread portion of the shaft portion is provided, two cutting grooves are provided at positions spaced apart in the circumferential direction of the shaft portion, and the two cutting grooves include a plurality of cutting grooves along the axial direction of the shaft portion. It has a length that divides the thread and a depth that is deeper than the valley between these threads, and the arrangement angle centered on the axial center of both cutting grooves is set to be a right angle or less within a range that does not overlap each other. A wood screw characterized by that.   Another cutting groove having the same length and depth as the cutting groove at a position different from the adjacent interval set so as to be equal to or less than the right angle of the two cutting grooves in the portion provided with the thread of the shaft portion. The wood screw according to claim 1, wherein the required number is provided.   2. A plurality of sets of cutting grooves, each of which is a set of the two, are provided at equal intervals along the circumferential direction of the shaft portion in the portion provided with the thread of the shaft portion. Wood screw mentioned.   The above-mentioned two cutting grooves and another cutting groove are provided at a plurality of positions along the axial direction of the portion where the thread of the shaft portion is provided at a distance from each other, and in the axial direction of the shaft portion. The wood screw according to any one of claims 1 to 3, wherein a thread without a groove is left between ends of adjacent cutting grooves.   Each of the above-mentioned cutting grooves is provided so as to be inclined so that the end located on the head side is located behind the end located on the tip end side in the screwing rotation direction of the wood screw. The wood screw according to any one of claims 1 to 4, wherein   The wood screw according to any one of claims 1 to 5, wherein an end portion of each of the cutting grooves located on a tip portion side starts from a boundary portion between the tip portion and the shaft portion.