JP2017067189A - Wood screw - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wood screw capable of suppressing occurrence of deterioration in strength against tension after screwing-in, without impairing screwing-in performance in fastening.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, a plurality of cutting grooves 7 are provided with intervals along an axial direction of the shaft part 2, the cutting groove having a length to such an extent as to parting a plurality of threads of the screw thread 5 and having a depth deeper than a trough of the portion where the screw thread 5 is provided; and between end parts of cutting grooves 7 adjacent to each other in the axial direction of the shaft part 2, a screw thread 5a with no groove is left.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a wood screw that improves the screwing performance at the time of fastening and can suppress the occurrence of a decrease in tensile strength after screwing.

  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 time of screwing into a wood material, cutting is performed while cutting the fiber in the wood material's internal thread and shaft part at the edge of the cutting edge located behind the cutting groove in the screwing direction. The chips generated by the above 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 4)

  Each wood screw provided with a cutting groove as in Patent Documents 1 to 4 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, so a pilot hole is formed in the wood material. 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 Japanese Patent No. 3942243

  However, the wood screw in 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 cutting groove can only cut with a smaller diameter than the outer diameter of the part or thread, and the cutting groove has a small storage capacity for the cutting chips generated by cutting, so that the cutting powder stored inside the cutting groove fills this cutting groove. In the initial stage of screwing, the cutting function of the cutting groove is reduced, and a long shaft portion with a thread is required to be screwed into the short tip portion. There is a problem in that there are few functions to prevent cracking.

  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 tip portion and the shaft portion to the head side are provided at equal intervals in the circumferential direction. Sometimes it is possible to cut with a diameter that matches the outer diameter of the shaft and thread, but if the chips stored inside the cutting groove fill the cutting groove, the chips generated thereafter will follow the cutting groove. There is a problem that the shaft portion and the outer periphery of the screw thread and the internal interface of the wood material bite, and this becomes resistance to screwing of the shaft portion, and there are few functions to reduce the generation of screwing resistance.

  Furthermore, the wood screw of Patent Document 4 is provided with an inclined cutting groove over the entire length of the thread forming portion of the shaft portion, and chips are discharged to the outside sequentially in the cutting groove when screwed into the wood material. , The occurrence of screwing resistance of the shaft part can be reduced, but the contact area with the wood material of the shaft part and the screw thread is reduced due to the presence of the cutting groove over the entire length of the screw thread, and the contact area is reduced after screwing. In proportion to this, the tensile strength of the wood screw decreases.

  Therefore, the problem of the present invention is to divide the cutting groove on the tip side and the head side of the thread provided on the shaft part, and leave a thread without a groove between the ends of both cutting grooves, Cutting chips generated by the cutting groove located on the tip side can be stored in this cutting groove, and by storing excess cutting powder in the cutting groove on the head side, the screwing performance is not impaired and cutting is performed. The reduction in the contact area of the shaft and thread wood after fastening by providing the groove can be supplemented by the chips held in both cutting grooves, and the decrease in tensile strength after screwing is suppressed. It is to provide a tapping wood screw that can be used.

  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, and having a length to divide a plurality of screw threads along the axial direction of the shaft part in the part provided with the screw thread of the shaft part In addition, a cutting groove deeper than the valley of the threaded portion is provided, and the cutting groove is provided at a plurality of positions along the axial direction of the shaft portion at a distance from each other, and in the axial direction of the shaft portion. A thread without a groove is left between the ends of adjacent cutting grooves.

  According to a second aspect of the present invention, the cutting groove is provided such that an end portion located on the head side with respect to an end portion located on the tip end side is inclined so as to be located rearward in the screwing rotation direction of the wood screw. It is what I did.

  According to a third aspect of the present invention, a plurality of the cutting grooves are provided at equal intervals around the shaft portion.

  According to a fourth aspect of the present invention, the cutting groove provided 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. is there.

  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 at a plurality of positions along the axial direction of the shaft portion is composed of a plurality of combinations arranged at equal intervals along the circumferential direction of the shaft portion. , An open angle of 70 ° is opened to the outer surface side, and a thread without a groove left between the axial cutting grooves has a length of about 1 to 4 threads. The cutting groove on the tip side that is divided in the axial direction by a non-threaded screw has a function of confining and storing the chip inside, and the cutting groove on the head side stores the excess cutting powder. This reduces the occurrence of screwing resistance caused by the above and prevents the chips from being discharged to the outside of the wood material. Complementing the reduction of the contact area, this improves the tensile strength of wood screws. It is possible to suppress the bottom.

  According to the wood screw of the present invention, the cutting grooves are provided at a plurality of positions along the axial direction of the screw thread provided on the shaft portion at a distance, and the thread without a groove is left between the adjacent cutting grooves. The wood chips cut by the cutting groove on the tip end side are stored inside with a thread without a groove, and the excess chips enter the shaft and the outer periphery of the thread and the inside of the wood By setting the screw threads without grooves to a few short ones, the chips that bite between the interfaces will fit in the cutting grooves on the head side before becoming a resistance factor, and screw in. Occasionally, the generated chips are prevented from resisting the subsequent shaft and thread, and can be screwed smoothly without impairing the screwing performance.

  In addition, the chips that fill the inside of each cutting groove are confined without being discharged to the outside of the wood material and come into contact with the inner periphery of the wood material. The reduction in the contact area of the screw can be supplemented, the fastening force after screwing can be improved and the tensile strength can be prevented from being lowered, and the tensile strength equivalent to that of a wood screw without a cutting groove can be secured.

  Furthermore, by providing a plurality of cutting grooves in the axial direction of the shaft portion, it is possible to secure a storage volume commensurate with the amount of chips generated, thereby being confined in the cutting grooves and excessively compressed. It is possible to prevent the cutting chips from deteriorating the cutting function of the cutting groove and to become an element of resistance against screwing of the wood screw, and to be screwed smoothly.

(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).

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

  As shown in the figure, the wood screw 1 has a shaft portion 2 having a predetermined length and a diameter, a head 3 provided at one end of the shaft portion, and a sharp cone-like shape provided at the other end of the shaft portion 2. A tip 5 is provided, and on the outer peripheral surfaces of the shaft 2 and the tip 4, a thread 5 ending in the middle of the length of the shaft 2 is continuous from the tip 4 toward the head 3. A straight circular screw-free part 2a is formed between the thread 5 of the shaft part 2 and the head part 3, and an engaging hole 6 for a rotary tool is provided in the head part 3. It has been.

  In the wood screw 1, a plurality of cutting grooves 7 that are long along the axial direction of the shaft portion 2 are provided in the portion provided with the screw thread 5 of the shaft portion 2 in an arrangement spaced apart in the axial direction of the shaft portion 2. The cutting groove 7 has a length that divides the plurality of screw threads 5 along the axial direction of the shaft portion 2, and a depth deeper than the valley of the portion where the screw threads 5 are provided. Between the ends of the cutting grooves 7 adjacent to each other in the axial direction, a thread 5a having no grooves is left.

  As shown in FIG. 1B, the cutting grooves 7 provided at a distance in the axial direction of the shaft portion 2 are provided so that a plurality of cutting grooves 7 are arranged in parallel along the circumferential direction of the shaft portion 2. For example, four cutting grooves 7 are provided at equal intervals in the circumferential direction of the shaft portion 2.

  Each cutting groove 7 has a V-shaped cross section that opens outwardly at an opening angle α of 70 ° or an angle before and after the bottom from the bottom that is recessed with respect to the valley of the portion where the thread 5 is provided, An edge portion formed by an outer peripheral surface of the shaft portion 2 and the thread 5 and an opening edge located behind the cutting groove 7 in the screwing rotation direction is a 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 remains, 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.

  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. And has a length along the axial direction of the shaft portion so as to divide a plurality of threads 5, and the cutting grooves 7 of the first cutting groove group 7 a are: In order to improve the cutting performance at the time of screwing into the wood material, the end located on the head 3 side with respect to the end located on the tip 4 side is located behind the screwing rotation direction of the wood screw 1, For example, it is provided in an inclined shape so as to have an angle of about 17 ° with respect to the axis of the shaft portion.

  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 first cutting groove group 7a. The interval between the end portions of the adjacent cutting grooves 7 of the first cutting groove group 7a and the second cutting groove group 7b is about 1 to 4 threads with no groove 5a left between them. Is set to

  The thread 5 provided on the wood screw 1 is not limited to two as shown in the figure, and may be a single thread or more, and the length and depth of the cutting groove 7 and the axis of the shaft 2 The number arranged in the direction and the number arranged in the circumferential direction of the shaft portion 2 can reliably store the 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. An example of specific numerical values of each part of the wood screw 1 when manufactured by rolling is shown by way of example. A double thread wood screw having a total length of 65 mm and a diameter of the shaft portion 2 of 3 mm is shown. 1, the cutting groove 7 has a depth that the length along the axial direction of the shaft portion 2 is 7.5 mm and the bottom portion is recessed by 0.3 mm with respect to the trough of the portion where the screw thread 5 is provided. The interval between the end portions of the first cutting groove group 7a and the second cutting groove group 7b is 5 It is set to 5mm.

  The wood screw 1 of the present invention is configured as described above. When a plurality of wood materials are fastened with a sharp tip 4 to fasten the wood, a thread formed on the outer periphery of the tip 4 is formed. 5 is bitten and the shaft portion 2 continues to enter by the screw thread 5 being threaded. First, the first cutting groove group 7 a provided on the tip portion 4 side of the shaft portion 2 is cut. The wood material is cut with the blade 8a.

  At this time, a part of the chips generated by the cutting of the cutting blade 8a is cut and simultaneously stored in the cutting groove 7a, and a part thereof is positioned behind the cutting blade 8a as a surplus in the screwing rotation direction. It will be screwed along the subsequent screw thread 5, and the surplus chips will be further cut by the subsequent cutting blade 8b located behind the cutting blade 8a in the screwing rotation direction.

  As a result, when the entire length of the first cutting groove 7a has entered the wood material, each cutting groove 7a is in a state in which a part of the chips generated by cutting the cutting groove 7a is stored. The surplus cutting powder continues to be screwed along the subsequent thread 5 located behind the cutting blade 8a in the screwing rotation direction.

  However, since the screw thread 5 having no groove is provided in the wood screw 1, excess cutting powder is not cut by the cutting blade 8, and is further cut off from the outside by the screw thread 5a having no groove. The excess chips and the chips generated by the cutting by the further rotation of the cutting groove 7a are surely confined in the cutting grooves 7a, and the space generated in the shaft portion 2 by the formation of the cutting grooves 7a is cut with the chips. Will meet.

  A part of the excess portion of the cutting powder filling the inside of each cutting groove 7 of the first cutting groove group 7a is pushed out to the head side from the interface between the screw thread 5a having no groove and its valley and the wood material. Since the thread 5a without the groove is set to be as short as about 1 to 4 threads, the excess cutting powder becomes the second cutting groove at the next position before it becomes a resistance element against screwing of the shaft portion 2. It is stored in the cutting groove 7 of the group 7b.

  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 group 7b accommodates the above-described excess cutting chips so that the cutting chips do not become a resistance element against screwing of the shaft portion 2, and the total length of the second cutting groove group 7b is reduced. Then, the thread 5b without a groove on the head 3 side enters, and the second cutting groove group 7b is cut off from the outside by the thread 5b without a groove on the head 3 side. The cutting powder is not discharged to the outside of the wood material, but is surely confined in the cutting groove 7 of the second cutting groove group 7b.

  As described above, when the wood screw 1 is screwed in, the first cutting groove group 7a and the second cutting groove group 7b cut the screw hole 5 and the spiral hole according to the valley diameter thereof, so that the shaft portion 2 enters. In addition to reducing the resistance at the same time, the occurrence of cracks in the wood material can be effectively prevented, and the first cutting groove group 7a and the second cutting groove group are spaced apart from each other at a plurality of positions in the axial direction of the screw thread 5. 7b is provided, a thread 5a having no groove is present between the first cutting groove group 7a and the second cutting groove group 7b, and there is no groove on the head 3 side of the second cutting groove group 7b. By providing the screw thread 5b, chips generated by screwing the shaft portion 2 are stored in the cutting grooves 7 of the first cutting groove group 7a and the second cutting groove group 7b, and the chips are resistant to screwing. It can be prevented from becoming an element.

  Further, a thread 5a not present between the first cutting groove group 7a and the second cutting groove group 7b is present, and a thread thread 5b having no groove is provided on the head 3 side of the second cutting groove group 7b. Thus, the chips generated by screwing the shaft portion 2 are securely discharged and stored in the cutting grooves 7 of the first cutting groove group 7a and the second cutting groove group 7b without being discharged to the outside of the wood material. As a result, the amount of contact area between the shaft portion 2 and the wood material due to the provision of the cutting grooves 7 is compensated, and the amount of the contact area is compensated to ensure the fastening strength and after fastening. Thus, the tensile strength can be maintained.

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

Claims (4)

  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, The portion provided with the thread of the shaft portion has a length to divide a plurality of threads along the axial direction of the shaft portion, and a cutting groove deeper than the valley of the portion provided with the thread is provided. The cutting grooves are provided at a plurality of positions along the axial direction of the shaft portion at a distance from each other, and a grooveless thread remains between the ends of the cutting grooves adjacent to each other in the axial direction of the shaft portion. Wood screw characterized by being.   The cutting groove is provided such that an end portion located on the head side with respect to an end portion located on the tip end portion side is provided in an inclined shape located rearward in the screwing rotation direction of the wood screw. The wood screw according to 1.   3. The wood screw according to claim 1, wherein a plurality of the cutting grooves are provided at equal intervals around the shaft portion.   The cutting groove provided near the tip end side of the shaft portion has an end portion located on the tip portion side starting from a boundary portion between the tip portion and the shaft portion. Wood screw described in crab.