Lag screw bolt

Abstract

To provide a lag screw bolt having no hexagonal head part with a female screw formed at its end part, which can be screwed with a normal rotary tool.SOLUTION: A bolt body 1 is formed so as to be screwed into a pilot hole Q1 drilled in wood Q. A thread 2 is formed so as to extend from a tip part to a rear end part of the bolt body 1. A square hole 3 having a planar polygonal shape is recessed into the rear end part of the bolt body 1. A female thread part 4 is recessed into a deep inside part of a mating recess part L3. A rotary tool is connected to the square hole 3 to screw the bolt body 1.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a lag screw bolt that can be embedded in wood without using a special mounting jig. [Background technology]

[0002] A lag screw bolt without a hexagonal head is used, for example, in the method of connecting cross-laminated timber Q (CLT) described in Patent Document 1. This lag screw bolt L is formed so that the root diameter of the thread matches the inner diameter of the pilot hole Q1, and has the effect of being able to connect the cross-laminated timber Q (CLT) of a wood-steel hybrid structure to the steel material P without using any adhesive. Moreover, unlike when using a general lag screw bolt with a hexagonal head, it does not require time-consuming work such as drilling the seat of the wood or filling it with epoxy resin, making it an extremely effective part for shortening the construction period of a wood-steel hybrid structure.

[0003] A dedicated mounting jig used for embedding this lag screw bolt in the pilot hole Q1 is described in Patent Document 2. This mounting jig is equipped with a tightening bolt body 1 that connects to the female thread portion L3 at the end of the lag screw bolt L, a retaining cylinder 2 that is used when removing the tightening bolt body 1 from the female thread portion L3 of the lag screw bolt, and abutment plate 3 that abuts against the opening of the pilot hole Q1.

[0004] The method of using this mounting jig is to screw the tightening bolt body 1 into the female thread portion L3 of the lag screw bolt L with the retaining cylinder 2 and the backing plate 3 attached to the tightening bolt body 1. Then, the tightening bolt body 1 is rotated to embed the lag screw bolt L until the backing plate 3 abuts against the open end of the pilot hole Q1. Thereafter, when removing the tightening bolt body 1 from the female thread portion L3 of the embedded lag screw bolt L, the tightening bolt body 1 is removed while holding the retaining cylinder 2 with a wrench or the like. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6986764 [Patent Document 2] Patent No. 6923984 Summary of the Invention [Problem to be solved by the invention]

[0006] The lag screw bolt shown in Patent Document 1 can simplify the work process because it does not require drilling a countersunk hole in wood or filling with epoxy resin, as with a lag screw bolt having a hexagonal head. However, when a tightening bolt is screwed into the female thread 3 recessed at the end of the lag screw bolt L and the lag screw bolt L is embedded in the pilot hole Q1 by rotating the bolt, the threads of the bolt bite into the female thread 3 of the lag screw bolt L and are tightened. As a result, when the tightening bolt is rotated in the reverse direction to be removed, the lag screw bolt L comes out together with the bolt, which is an inconvenience.

[0007] For this reason, when embedding the lag screw bolt L without a hexagonal head, it was necessary to use a dedicated mounting jig as shown in Patent Document 2. That is, when removing the tightening bolt body 1, the tightening bolt body 1 is removed while the retaining cylinder body 2 is fixed with a wrench or the like. Therefore, since the lag screw bolt L without a hexagonal head requires the use of a special dedicated tool, it was difficult to embed the lag screw bolt L with only a normal rotating tool, as in the case of a lag screw bolt with a hexagonal head.

[0008] Moreover, since a special tool is required to embed the lag screw bolt L, which does not have a hexagonal head, the depth to which it can be embedded is limited to the opening of the pilot hole Q1, and it is difficult to embed it deep into the pilot hole Q1. Therefore, there is also the inconvenience that the range of use of the lag screw bolt L is limited.

[0009] Therefore, the present invention has been created to solve the above-mentioned problems, and aims to provide a lug screw bolt that can be embedded using a normal rotary tool even in the case of a lug screw bolt L that does not have a hexagonal head, and that can be embedded deep into a pilot hole, thereby expanding the range of use. [Means for solving the problem]

[0010] In order to achieve the above-mentioned object, the first means of the present invention is a lag screw bolt having a female threaded portion 4 formed inward from the rear end of a bolt body 1 without a hexagonal head, for screwing a connecting bolt, and a square hole 3 for connecting a rotating tool 10 is recessed between the rear end of the bolt body 1 and the female threaded portion 4.

[0011] The second lag screw bolt comprises the bolt body 1 to be embedded in a pilot hole Q1 drilled in a piece of wood Q, a thread 2 extending from the front end to the rear end of the bolt body 1, the square hole 3 recessed in the rear end of the bolt body 1, and the female thread portion 4 formed with a smaller diameter than the square hole 3.

[0012] The bolt body 1 of the third means has a through hole 5 penetrating the axial center of the bolt body 1, the square hole 3 is formed on the rear end side of the through hole 5, and the female thread portion 4 is formed along a part or the entire length of the through hole 5.

[0013] The through hole 5 of the fourth means is formed so that the inner diameter at the front end side of the bolt body 1 is smaller than the inner diameter at the rear end side. Effect of the Invention

[0014] According to the present invention, even the lag screw bolt L without a hexagonal head can be embedded using only a normal rotary tool without using a special tool. Moreover, it is now possible to embed the lag screw bolt deep into the pilot hole.

[0015] Furthermore, the hollow bolt body 1 can reduce the weight of the lag screw bolt L. Furthermore, the through hole 5 of the bolt body 1 can be used to expand the range of applications of the lag screw bolt. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is an exploded perspective view showing an embodiment of the present invention and a rotary tool. [Diagram 2] FIG. 1 is a vertical cross-sectional view showing an embodiment of the present invention in use. [Diagram 3] FIG. 1A is a plan view of an embodiment of a fitting recess of the present invention, and FIG. [Figure 4] 6(a) to 6(c) are plan views showing other embodiments of the fitting recess of the present invention. [Diagram 5] FIG. 11 is an exploded perspective view showing a rotation jig and another embodiment of the present invention. [Figure 6] 5(a) to 5(c) are vertical cross-sectional views showing other embodiments of the present invention. [Figure 7] FIG. 11 is a vertical sectional view showing another usage state of the present invention. [Figure 8] FIG. 11 is a vertical sectional view showing another usage state of the present invention. [Figure 9] FIG. 11 is a vertical sectional view showing another usage state of the present invention. [Figure 10] FIG. 11 is a vertical sectional view showing another usage state of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] The present invention is a lag screw bolt that is mainly used to connect cross-laminated timber (CLT). Cross-laminated timber (CLT) is a type of wood that is made by arranging sawn boards (lamina) and then laminating and gluing them so that the grain direction is perpendicular to the board. This type of wood is also used for architectural structural materials, civil engineering materials, furniture, etc.

[0018] On the other hand, lag screw bolts are bolts that connect earthquake-resistant hardware, traditionally known as hold-down hardware or pull-down hardware, and are important connecting components that ensure earthquake resistance by attaching earthquake-resistant hardware to the foundation or base and columns, or between columns or between columns and beams on upper and lower floors, in order to counter the pull-out force that acts on the load-bearing walls when a wooden building is subjected to horizontal force.

[0019] In construction methods using cross-laminated timber (CLT) such as wood-steel hybrid structures, lag screw bolts without hexagonal heads and with a female thread recessed into the rear end are used. The present invention is a lag screw bolt without a hexagonal head, in which a female thread 4 is formed from the rear end toward the inside.

[0020] That is, the main configuration of the present invention is a lag screw bolt equipped with a bolt body 1, a thread 2, a square hole 3, and a female thread portion 4 (see FIG. 1). The lag screw bolt is embedded in a pilot hole Q1 having a diameter between the root diameter and the crest diameter of the thread 2.

[0021] The bolt body 1 is the part to be embedded in a pilot hole Q1 drilled in wood Q, and has a screw thread 2 formed on the entire outside from the front end to the rear end of the bolt body (see Figure 1). The illustrated bolt body 1 is in the form of a solid bolt. It is also possible to form a hollow bolt body 1 with a through hole 5 in the axial center of the bolt body 1 (see Figure 6).

[0022] The square hole 3 is a recessed portion at the rear end of the bolt body 1 and is formed so as to be connected to a rotary tool 10 (see FIG. 1).

[0023] This square hole 3 is formed, for example, in the shape of a hexagonal hole of a hexagonal socket bolt, and is used to connect a commonly used rotary tool 10 such as a driver bit (see Fig. 1 and Fig. 3(A)). A female thread portion 4 is formed continuously at the tip side of this square hole 3 (see Fig. 3(B)).

[0024] The shape of the square hole 3 can be selected arbitrarily so as to correspond to the rotating tool 10 (see FIG. 4). In the figure (A), the square hole 3 has a dodecagonal shape when viewed from above, and (B) has a star shape with a hexagonal shape when viewed from above. Also, (C) has a star shape with a quadrangle when viewed from above. In this way, the square hole 3 is formed so as to correspond to various rotating tools 10 that are commonly used. Therefore, by connecting a long socket or the like to the rotating tool 10, it is also possible to embed the bolt body 1 in the pilot hole Q1 of a deep hole.

[0025] The female thread 4 is basically formed on the rear end side of the bolt body 1, and is used to screw in a fixing bolt R, which is mainly a high-strength bolt, to connect a steel plate S or other members (see Figure 2). The illustrated female thread 4 is formed on the inner periphery of a recessed portion on the tip side of the square hole 3, and the bolt body 1 is solid.

[0026] The bolt body 1 can also be formed hollow and have a through hole 5 (see FIG. 6). In this case, the female thread portion 4 can be formed along a part or the entire length of the through hole 5. In this case, the fixing bolt R can be screwed into any position of the through hole 5.

[0027] Furthermore, by increasing the diameter of the through hole 5 to form a thin-walled hollow bolt body 1, the weight of the bolt body 1 can be reduced (see Figs. 6(a) and (b)). Therefore, when using heavy, large-diameter lag screw bolts, it becomes possible to simultaneously transport more than twice as many lag screw bolts as before, improving work efficiency.

[0028] In Fig. 6(b), square holes 3 are formed on both ends of a through hole 5. Furthermore, it is also possible to form the inner diameter of the through hole 5 on the front end side of the bolt body 1 to be smaller than the inner diameter of the through hole 5 on the rear end side (see Fig. 6(c)). When the diameter of the through hole 5 is made smaller, it becomes possible to insert and screw a linear or rod-shaped connecting member T having a threaded end (see Fig. 10). In this way, the shape of the bolt body 1, the position of the square hole 3 and the female thread portion 4, the presence or absence of the through hole 5, etc. can be changed as desired.

[0029] Next, an example of using the lag screw bolt of the present invention will be described. Figure 7 shows an example in which a fixing bolt R, which has passed through the female thread portion 4 of a hollow bolt body 1, is screwed into the female thread portion 4 of another continuous lag screw bolt. The upper bolt body 1 has the female thread portion 4 formed along the entire length of the hollow interior. In this way, it becomes possible to use multiple lag screw bolts in succession.

[0030] Figure 8 shows an example in which a single lag screw bolt is embedded deep inside a pilot hole Q1, and fixing bolts R are screwed into the female threads 4 on both ends. The illustrated bolt body 1 is solid, and has square holes 3 formed on both ends. At this time, cavities are formed in the pilot holes Q1 on both ends of the lag screw bolt, and these cavities are filled with filler P. It is also possible to leave the cavities empty without filling them with filler P.

[0031] Fig. 9 shows a state in which steel plates S are directly fixed to both ends of a solid lag screw bolt. That is, the steel plates S are fixed by screwing fixing bolts R into the female threaded portions 4 on both ends of the bolt body 1. In this case, it is also possible to use hollow lag screw bolts on both ends of the lag screw bolt.

[0032] Fig. 10 shows an example of the use of a lag screw bolt in which the inside diameter of the through hole 5 on the front end side of the bolt body 1 is formed smaller than the inside diameter on the rear end side. In the illustrated example, a female thread 4 is formed in the through hole 5 on the front end side, and a linear or rod-shaped connecting member T is screwed into this female thread 4. These connecting members T are, for example, those with threaded ends. By combining such connecting members T with lag screw bolts, it is possible to further expand the range of use.

[0033] For example, it will be possible to use it to construct rigid frame or truss structures for joints such as walls, floors, columns, beams, and roofs in wooden buildings using structural laminated timber, or in mixed steel and wooden structures.

[0034] In addition, in the present invention, the structure, dimensions, materials of the bolt body 1, thread 2, square hole 3, female thread portion 4, etc., or uses of the lag screw bolt of the present invention are not limited to the examples shown in the drawings, and can be arbitrarily changed without changing the gist of the present invention. [Explanation of symbols]

[0035] P filler Q wood Q1 Pilot hole R Fixing bolt S steel plate T connection member 1 Bolt body 2 Threads 3 square hole 4 Female thread 5 Through hole 10 Rotary tools

Claims

1. A lag screw bolt having a female threaded portion formed inward from the rear end of a bolt body without a hexagonal head for screwing a fixing bolt, characterized in that a square hole for connecting a rotating tool is recessed between the rear end of the bolt body and the female threaded portion.

2. 2. The lag screw bolt according to claim 1, comprising: a bolt body to be embedded in a pilot hole drilled in wood; a screw thread extending from a front end to a rear end of the bolt body; a square hole recessed in the rear end of the bolt body; and the female thread portion formed with a smaller diameter than the square hole.

3. 3. The lag screw bolt according to claim 1 or 2, wherein the bolt body has a through hole penetrating an axial center portion of the bolt body, the square hole is formed on a rear end side of the through hole, and the female thread portion is formed along a part or the entire length of the through hole.

4. 4. The lag screw bolt according to claim 3, wherein the through hole is formed so that the inner diameter at the tip end side of the bolt body is smaller than the inner diameter at the rear end side.

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