JP2023096297A - screw - Google Patents

Abstract

To provide a screw capable of improving the bending and torsional strength of a shaft part by increasing a section modulus of the shaft part, and preventing generation of bending and breakage during screwing.SOLUTION: In a screw 1, a sharp end 5 is formed at the other end of a shaft part 3 having a head part 4 at one end, and a screw thread 2 is provided on the outer periphery of the shaft part 3. On both sides of a root side of the screw thread 2 of the shaft part 3, a slope 6 that spread out on both sides is provided. Further, in valleys 7 of the screw thread 2, a ridge 8 is provided so that a height from the valley 7 is lower than a height of the screw thread 2. A section modulus of the shaft part 3 is increased by the slopes 6 and the ridges 8.SELECTED DRAWING: Figure 2

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screw used for fastening wooden structures, and more particularly, to a screw having a shank with a large section modulus to strengthen the shank against bending and torsional stress.

The basic structure of a screw for fastening wooden structures has a structure in which a head is provided at one end of a threaded shank and a sharp tip is provided at the other end, and is screwed into a wooden structure with a rotary tool. A screw is used to tightly fasten a wooden structure by inserting it while rotating with a screw thread. In order not only to improve work efficiency but also to prevent bending and breakage of the shaft during screwing, the shaft is required to have sufficient strength against bending and twisting stress.

In general, when a screw is screwed in, a linear load is applied to the threads, and as the screw progresses into the wooden material, the torsional load acting on the shaft increases. The load concentrates on the corners of the root and root portions of the thread on the shaft, which causes cracks and bends in the shaft. This is conspicuous in the case of a hard screw or a screw with a long axis, and for this reason, a situation occurs in which the required strength of fastening of a wooden structure cannot be obtained, or the fastening ends in failure.

In order to prevent such cracks, bending, and breakage in the shank of a screw, the strength of the corners between the base and root of the screw thread in the shank should be improved. By increasing the modulus, it is necessary to strengthen the stress against bending and twisting.

In a conventional screw, in order to improve the strength of the corner portion between the root portion of the screw thread and the root portion of the shaft portion, as in Patent Documents 1 and 2, a screw thread on both sides at the root side of the screw thread provided on the shaft portion has been proposed. At the position of , a slope is provided that starts in the middle of the side of this thread as a base point, descends from this base point toward the valley formed between the threads, and spreads out on both sides of the thread. Accordingly, it has been proposed to increase the strength by increasing the thickness of the root side of the thread.

Next, as a screw intended to improve the efficiency of the screwing operation, as in Patent Documents 3 and 4, a ridge whose height is lower than the ridge is provided in the middle of the ridge, and this ridge is provided at the time of screwing. By cutting and agitating the wood structure between the screw threads, the wood structure is softened, and the screw threads progress through this softened structure part, preventing cracks in the wood material and reducing the resistance during screwing. is known to reduce the occurrence of

JP 2012-7723 A Japanese Utility Model Publication No. 48-2908 JP-A-9-217722 JP-A-2000-2218

By the way, the screws as shown in the above-mentioned Patent Documents 1 and 2 simply thicken the root portion of the screw thread and reinforce a part of the shaft portion between the screw threads. In this case, there is only the shank portion, and since the shank between the slopes does not structurally improve the strength of stress against bending and torsion, as a result, the load is applied to the shank between the slopes during screwing. Therefore, there is a problem that it is not possible to sufficiently prevent the occurrence of bending or breakage of the shaft portion during screwing.

Further, the screws disclosed in Patent Documents 3 and 4 are intended to improve the efficiency of the driving operation by the action of the ridges provided between the threads. Since it is a structure provided at the position of the part, there is nothing to improve the strength of the entire length of the shaft part, and it is necessary to prevent bending and nicks in the shaft part due to the torsional stress that increases as the amount of screwing progresses. There is a problem that it is not possible to

Accordingly, an object of the present invention is to increase the section modulus between threads of the shank as much as possible to increase the stress against bending and torsion of the entire length of the shank, thereby preventing bending and breakage of the shank. is to provide

In order to solve the above problems, the invention of claim 1 provides a screw in which a head is provided at one end, a sharpened end is formed at the other end of the shaft, and a screw thread is provided on the outer periphery of the shaft, On both sides of the screw thread provided on the shaft portion, at the position on the root side, starting from the middle of the side surface of this screw thread as a starting point, moving downward from this starting point toward the solstice point on the valley portion while spreading on both sides. and a ridge parallel to the axial direction of the shaft or inclined in a direction along the lead angle of the thread is provided in the valley between the threads, and the valley of the ridge The height from the thread is set to be lower than the height of the screw thread.

According to the invention of claim 2, in the invention of claim 1, the slope is formed as a slope that is recessed linearly or arcuately.

According to the invention of claim 3, in the invention of claim 1 or 2, the ridge is provided so that the end thereof reaches the slope.

According to a fourth aspect of the invention, in any one of the first to third aspects of the invention, a plurality of the ridges are provided at equal intervals in the circumferential direction of the shaft portion.

The invention according to claim 5 is the invention according to any one of claims 1 to 4, wherein the ridge extends over the entire length of the screw thread from a position excluding the sharp end side of the shaft to the end on the head side. It is designed so that it is provided all the way around.

The invention of claim 6 is the invention of any one of claims 1 to 5, wherein the ridges are also provided at the part of the incomplete thread formed at the head side end of the screw thread. It is.

Here, the slopes provided on both sides of the screw thread described above start from a position lower than half of the height dimension on the side of the screw thread as a starting point, and slope downward from this starting point toward the solstice point on the valley. , the root diameter of the shank is increased on both sides of the thread, and as a result, the thickness on the root side of the thread is increased.

Further, the ridges provided between the threads have a cross-sectional shape of, for example, a trapezoid, and the ridges located between the threads are parallel to the axial direction of the shaft portion or lead in the same direction as the threads. The ridges and the slanted surfaces increase the section modulus of the shank between the threads to the extent possible.

According to the screw of the present invention, the slopes are provided on both sides of the thread root side, and the ridges are provided between the threads, so that the slopes and the ridges increase the section modulus between the threads of the shank. As a result, the stress against bending and twisting of the shaft portion is increased, bending and breakage during screwing can be prevented, and the fastened state can be reliably maintained.

In addition, in a nail with a screw, when screwed into a wooden structure, the ridges between the threads scrape the wooden material, thereby improving the screwing efficiency. If the height from the trough portion is set to be lower than the outer diameter of the screw thread and is equal to or lower than the start point of the slope on the side surface of the screw thread, the protrusion can be formed. Excessive scraping of the wood material between the threads can be suppressed, which makes it possible to both increase the section modulus between the threads of the shaft and secure the screwing amount of the threads to the wood material. This results in a strong fastening of the wooden structure.

FIG. 2 is a front view showing the overall shape of the screw according to the present invention; FIG. 2 is a horizontal front view of the shaft portion of the screw according to the present invention; Enlarged cross-sectional view in a horizontal state along the arrow aa in FIG. Cross-sectional view along arrow bb in FIG. A cross-sectional view in a horizontal state in which the portion of the screw thread and the ridge taken longitudinally at a position close to the arrow aa in FIG. 2 is enlarged.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

As shown in FIGS. 1 to 3, the screw 1 has a shaft portion 3 having a screw thread 2 on its outer circumference and a head portion 4 provided with a rotary tool engaging portion at one end and a sharp tip 5 for screwing in at the other end. The screw thread 2 has slopes 6 on both sides in the axial direction on the root side, and the valley portion 7 between the adjacent screw threads 2 has the screw thread of the shaft portion 3 A ridge 8 is provided in a range extending from a portion of the head portion 2 excluding the sharp end 5 side to the end portion on the head portion 4 side.

The height and pitch of the thread 2, the lead angle, the diameter and total length of the shaft portion 3, etc. are not particularly limited, and may be appropriately set according to the conditions of the wooden structure to be fastened. , the cross section of the thread 2 has an angle of 45°, the height H1 from the valley portion 7 is 1.0 mm, and the pitch P between the threads 2 is the height of the thread 2. The slopes 6 provided on both sides of the screw thread 2 start from the middle of the side surface of the screw thread 2 as a starting point a. b, and spreads toward the trough portion 7 on both sides of the thread 2. This slope 6 is 0.3 mm from the trough portion 7 to the base point a on the side surface of the thread 2. It is set at a position of height H2, and the axial distance L from this base point a to the solstice b where the slope 6 reaches the trough portion 7 is 0.7 mm.

In the illustrated case, the cross-sectional shape connecting the starting point a and the apex point b of the slope 6 is a straight line. By providing it on both sides, the thickness of the root side portion of the screw thread 2 is increased, and as a result, the diameter of the root portion 7 in the shaft portion 3 is thickened on both sides of the screw thread 2, and the strength of the screw thread 2 alone is sufficient. Therefore, the bending and torsional strength of the shaft portion 3 can be improved.

The height of the protrusion 8 from the root portion 7 may be arbitrarily set under the condition that the height from the root portion 7 of the thread 2 is lower than the outer diameter of the thread 2. It is possible to ensure the threaded state of the screw thread 2 to the wooden material when screwing it into the material. It can be set to the same height as the position of the starting point a of the slope 6, or it can be set to a height H3 that is slightly lower by about 0.2 mm as shown in FIG. The ridge 8 is inclined in a direction along the lead angle of the thread 2 with respect to the axial direction of the shaft portion 3 at a lead angle sharper than the lead angle, and as shown in the cross-sectional view of FIG. A plurality of them are provided at equal intervals in the circumferential direction of the shaft portion 3 .

In the case of FIG. 1, the ridges 8 between the screw threads 2 described above are shown in a helical shape that is continuously arranged with the screw threads 2 interposed in the axial direction of the shaft portion 3. The ridges 8 may be arranged linearly along the axial direction of the shaft portion 3 in addition to the spiral arrangement.

The ridge 8 has, for example, a trapezoidal cross-sectional shape of 60°, and both ends of the ridge 8 reach the slope 6 and are integrated with the slope 6 to reinforce the root portion of the screw thread 2. , when the end of the thread 2 on the side of the head 4 is an incomplete thread, the ridge 8 located at the end on the side of the head 4 is also provided in this incomplete thread. .

In the case of FIG. 1, the screw 1 is provided with the thread 2 over substantially the entire length from the sharp end 5 of the shaft portion 3 to the neck portion of the head portion 4, but an example of a full thread is shown. Alternatively, the tip 5 may be a half screw having a screw thread 2 in the range from the sharp tip 5 to the middle of the shaft portion 3, and the sharp tip 5 may be not only conical but also have a cutting edge. good too.

Furthermore, in the case of FIG. 1, the position and range where the ridge 8 is provided on the screw thread 2 is from a position several threads away from the sharp end 5 of the screw thread 2 toward the head 4 side to the end on the head 4 side. , but they may be arranged scatteredly in several places in the axial direction of the shaft portion 3. Also, the cross-sectional shape of the protrusion 8 and the circumferential direction of the shaft portion may be arranged. The number shown is not limited to the illustrated example.

The screw 1 of the present invention is constructed as described above. When the screw 1 is screwed into a wooden structure from the sharp end 5, the action of the thread 2 penetrates into the wooden structure. A load is applied to the thread 2 along the axial direction of the shank 3, but the screw 1 is supported by the slopes 6 located on both sides of the thread 2 and the ridges 8 provided in the valleys 7 between the threads 2. Since the section modulus of the shank 3 is increased, the bending and torsional strength of the shank is improved, and the screw can be smoothly screwed in without bending or breakage.

In addition, since the slope 6 located on the advance side of the screw 1 is inclined upward from the root 7 toward the middle of the thread 2, the wooden material is guided from the root 7 toward the outer circumference of the thread 2. By doing so, the load in the forward direction applied to the thread 2 is reduced, and the screwing can be made smoother.

Furthermore, when the shaft portion 3 is screwed in, the protrusions 8 provided between the screw threads 2 rotate, so that the protrusions 8 shave and soften the wooden material between the screw threads 2, thereby softening the shaft portion. Since the height of the protrusion 8 is set lower than the height of the thread 2, the thread 2 can be screwed into the wooden material. can be ensured, whereby the pull-out strength of the screw 1 can be obtained.

Thus, by providing the slope 6 at the root portion of the thread 2 and providing the ridge 8 in the valley 7 between the threads 2, the section modulus of the shaft 3 is increased. The bending and torsional strength is improved, and damage to the shaft portion 3 can be prevented during screwing and after the wooden structure is fastened.

In addition, in the tightened state after the screw 1 is screwed in, the protrusion 8 positioned between the screw threads 2 is positioned in the wooden material at a lead angle different from that of the screw thread 2, so that the screw 1 has a locking function and the wooden material. The fastened state of the structure can be reliably maintained.

REFERENCE SIGNS LIST 1 screw 2 thread 3 shank 4 head 5 pointed end 6 slope 7 valley 8 ridge a starting point of slope b solstice of slope

Claims (6)

In a screw having a shank with a head on one end and a sharp end on the other end, and a screw thread on the outer periphery of the shank, on both sides of the screw thread on the shank, at a position on the root side, Starting from the middle of the side surface of the thread, a slope that spreads on both sides while descending from this starting point toward the solstice on the valley is provided, and the valley between the threads is the axis of the shaft Provide a ridge parallel to the direction or inclined in the direction along the lead angle of the thread, and set the height from the root of this ridge to be lower than the height of the thread. A screw characterized by: 2. The screw according to claim 1, wherein the slanted surface is formed as a slanted surface that is linearly or arcuately recessed. 3. The screw according to claim 1 or 2, wherein the ridge is provided so that its end reaches the slope. 4. The screw according to any one of claims 1 to 3, wherein a plurality of said protrusions are provided at equal intervals in the circumferential direction of said shaft portion. 5. The protrusion according to any one of claims 1 to 4, wherein the protrusion is provided over the entire length of the thread from a position excluding the sharp end side of the shaft portion to the end portion on the head portion side. screws described in . 6. The screw according to any one of claims 1 to 5, characterized in that said ridge is also provided at a portion of an incomplete thread formed at the head side end of the screw thread.

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