JP2024090669A - bolt - Google Patents

Abstract

To provide a bolt capable of fixing a material to be fixed, without reference to the thickness of the material to be fixed.SOLUTION: A bolt 10 fixes a material to be fixed between it and a screwed opposite material. The bolt 10 comprises a head 20 and a shank 30. The shank 30 has a complete thread part 35, and an unthreaded part 33 that is positioned on a base end side with respect to the complete thread part 35 and in which a thread is not formed. The unthreaded part 33 has a diameter φ smaller than an inside diameter d1 of the complete thread part 35.SELECTED DRAWING: Figure 1

Description

The present invention relates to a bolt that secures a fixed material to a mating material with which it is screwed.

A bolt has a male thread and is used for applications such as screwing into a female thread formed in a mating material to tighten and fix a fixed material. A bolt has a cylindrical portion on the shank side, which is made up of a non-threaded portion where no threads are formed in a certain area on the head side, and an incompletely threaded portion. Some bolts have a fully threaded portion with a completely male thread formed on the tip (screw tip) side of this cylindrical portion (each figure in Patent Document 1).

Design Registration No. 1520241

In the bolt 110 described in Patent Document 1, a certain range of the shaft 130 near the head 120 is a cylindrical portion 131, the diameter of which is approximately the same as the diameter (outer diameter) of the top of the threads of the fully threaded portion 135 and larger than the diameter (inner diameter) of the root. On the other hand, a threaded hole 141 is formed in a mating member 140 into which the bolt 110 is screwed, and the inner diameter of the female thread 142 formed in the threaded hole 141 is slightly larger than the inner diameter of the fully threaded portion 135 of the bolt 110 and smaller than the outer diameter.

Therefore, when the cylindrical portion 131 of the screwed bolt 110 reaches the front end of the screw hole 141 of the mating material 140, the female thread 142 of the mating material 140 and the cylindrical portion 131 of the bolt 110 interfere with each other, restricting the rotation of the bolt 110. Then, the bolt 110 cannot advance any further into the mating material 140.

Here, we consider the case where the fixed material 150 is fixed by the bolt 110 and the mating material 140. The fixed material 150 has an insertion hole 151 formed therein through which the shaft portion 130 of the bolt 110 can be inserted. If the thickness of the fixed material 150 is thicker (longer) than the length of the cylindrical portion 131 of the bolt 110, the fixed material 150 can be tightened and fixed between the bolt 110 and the mating material 140 before the cylindrical portion 131 of the bolt 110 reaches the front end of the screw hole 141 of the mating material 140.

On the other hand, as shown in FIG. 4(a), a case will be described in which the thickness of the fixed material 150 is thinner (shorter) than the length of the cylindrical portion 131. As shown in FIG. 4(b), when the cylindrical portion 131 of the screwed bolt 110 reaches the front end of the screw hole 141 of the mating material 140, the fixed material 150 is not yet tightened. However, since the cylindrical portion 131 of the bolt 110 interferes with the front end of the screw hole 141 of the mating material 140 and rotation is restricted, the bolt 110 cannot advance any further into the mating material 140. For this reason, there is a problem that the fixed material 150 cannot be fixed by the bolt 110 and the mating material 140 depending on the length of the cylindrical portion 131 of the bolt 110 and the thickness of the fixed material 150.

Therefore, the present invention aims to provide a bolt that can secure a material to be fixed regardless of the thickness of the material.

The bolt that solves the above problem is a bolt that fixes a fixed material between a screwed mating material, the bolt having a head and a shaft, the shaft having a fully threaded portion and a non-threaded portion that is located proximal to the fully threaded portion and has no threads, the non-threaded portion having a diameter smaller than the inner diameter of the fully threaded portion. This prevents the mating material from interfering with the non-threaded portion.

The non-threaded portion has a length of 1 mm to 10 mm, which allows the bolt to be used for fastening thin materials.
The non-threaded portion has a diameter that is 0.1 mm to 1 mm smaller than the inner diameter of the fully threaded portion, thereby ensuring a clearance between the non-threaded portion and the mating material.

The bolts are made of stainless steel, which ensures strength and corrosion resistance.

The bolt of the present invention makes it possible to fasten the material to be fastened regardless of the thickness of the material.

FIG. 1(a) is a side view of the bolt, and FIG. 1(b) is a plan view of the bolt. 2(a), 2(b), and 2(c) are explanatory diagrams showing the fixing of plate materials by bolts and thick plates, respectively. 3(a), 3(b), and 3(c) are explanatory diagrams showing fastening of plate materials with bolts and nuts. 4(a) and 4(b) are explanatory diagrams showing the fastening of plate materials by bolts according to the prior art.

Hereinafter, one embodiment of a hexagon socket extra low head bolt (hereinafter simply referred to as a "bolt") 10 embodying the present invention will be described with reference to Figures 1 and 2. In addition, a thick plate 40 as a mating material that screws into this bolt 10 and a method of using them will also be described.

(Bolt 10)
FIG. 1(a) shows a side view of the bolt 10 of this embodiment. The bolt 10 is composed of a head 20 and a shaft 30, both of which are integrally formed from stainless steel. In describing the bolt 10 of this embodiment, the left-right direction in FIG. 1(a) is referred to as the length direction of the bolt 10 and each of its constituent parts. The up-down direction in FIG. 1(a) and FIG. 1(b) and the left-right direction in FIG. 1(b) are referred to as the radial direction of the bolt 10 and each of its constituent parts. In describing the head 20 of the bolt 10, the left side surface in FIG. 1(a), specifically the surface shown in FIG. 1(b), is referred to as the surface 21, and the opposite surface is referred to as the seat surface 22. In describing the shaft 30 of the bolt 10, the left side in FIG. 1(a), which is connected to the head 20 in the length direction, is referred to as the base end, and the right side in FIG. 1(a), which is the so-called screw tip, is referred to as the tip.

As shown in Figures 1(a) and 1(b), the head 20 of the bolt 10 is disk-shaped with a constant diameter and length. The surface 21 of the head 20 is flat, and the outer edge of the surface 21 is chamfered. A bottomed hexagonal hole 23 is formed in the center of the surface 21 of the head 20 in the longitudinal direction. This hexagonal hole 23 is a hole for inserting a tool such as a hexagonal wrench, and its size varies depending on the size of the bolt 10. The bottom of the hexagonal hole 23 is conical, and its tip reaches the shaft 30 in the longitudinal direction. The center of the disk-shaped head 20 and the center of the hexagonal hole 23 (the intersection of the diagonals) are concentric.

As shown in FIG. 1(a), the shaft portion 30 is formed integrally with the head portion 20, and extends from the seat surface 22 of the head portion 20 toward the tip. The shaft portion 30 is formed, in order, from the base end toward the tip, with a cylindrical portion 31 and a threaded portion 32. The cylindrical portion 31 is made up of a non-threaded portion 33 that has no threads formed on its outer circumferential surface, and an incompletely threaded portion 34 that expands in diameter from the non-threaded portion 33 toward the threaded portion 32 and has an incompletely threaded portion. The threaded portion 32 is made up of a completely threaded portion 35 that is formed continuous with the incompletely threaded portion 34, and a chamfered portion 36 that is formed at the tip of the completely threaded portion 35.

The length of the shaft 30, or the so-called neck length, is not specified and can be set according to the nominal diameter of the screw. As an example, a length of 3 to 7 mm can be used for nominal diameter M3, 4 to 9 mm for M4, and 5 to 11 mm for M5 and M6.

As shown in FIG. 1(a), the non-threaded portion 33 extends vertically from the seat surface 22 of the head 20 and is cylindrical with a constant diameter φ of a circular cross section. No threads are formed on the outer circumferential surface of the non-threaded portion 33. The shaft portion 30 including the non-threaded portion 33 is solid, but as shown in FIG. 1(a), the tip of the hexagonal hole 23 formed on the surface 21 of the head 20 is located on the base end side of the non-threaded portion 33. The non-threaded portion 33 is formed with a diameter φ smaller than the diameter (inner diameter) d1 of the valley bottom of the fully threaded portion 35 described later. Specifically, the diameter φ of the non-threaded portion 33 can be 0.1 mm to 1 mm smaller than the inner diameter d1 of the fully threaded portion 35. There is no particular regulation for the length of the non-threaded portion 33, and for example, 1.7 mm for nominal diameter M3, 2.3 mm for M4, 2.4 mm for M5, and 2.6 mm for M6 can be adopted. For these reasons, the length of the non-threaded portion 33 can be in the range of 1 mm to 10 mm. The non-threaded portion 33 can be formed by cutting.

The incomplete thread portion 34 is a portion located at the boundary between the non-threaded portion 33 and the completely threaded portion 35. The incomplete thread portion 34 tapers from the non-threaded portion 33, where no threads are formed, toward the completely threaded portion 35, and has an incomplete thread shape, with the thread becoming higher in height toward the tip, leading to the completely threaded portion 35. There is no particular regulation for the length of the incomplete thread portion 34, and it can vary depending on the nominal diameter, and when converted into the pitch of the thread, it can be 0.5 to 2 pitches.

As shown in FIG. 1(a), the fully threaded portion 35 is a portion in which a complete male thread is formed. The male thread formed in the fully threaded portion 35 is formed in a shape having a specified pitch, inner diameter d1, and top diameter (outer diameter) d corresponding to the nominal diameter. The length of the fully threaded portion 35 is not particularly specified, and can be determined by balancing the length of the cylindrical portion 31, etc. The inner diameter d1 of the fully threaded portion 35 is larger than the diameter φ of the non-threaded portion 33, i.e. d1>φ.

As shown in FIG. 1(a), the chamfered portion 36 is formed at the tip of the complete thread portion 35, and is a portion in which the diameter decreases toward the tip. This chamfered portion 36 is also an incomplete thread portion in which a thread with an incomplete ridge shape is formed.

(Thick plate 40)
As shown in Fig. 2(a), a screw hole 41 that opens forward is formed in a thick plate 40 into which the bolt 10 is screwed, and a female screw portion 42 having an inner diameter D1 that can be screwed into the fully threaded portion 35 of the bolt 10 is formed on the inner peripheral surface of the screw hole 41. The relationship between the inner diameter d1 of the bolt 10 and the inner diameter D1 of the thick plate 40 is D1>d1. The thick plate 40 is made of a metal material such as stainless steel, and the screw hole 41 is formed to be longer than the shaft portion 30 of the bolt 10, but is not shown in the figure. Note that the right side of the thick plate 40 in Fig. 2 is called the back, and the left side is called the front.

(How to use Bolt 10)
Next, a method for fixing one plate material (fixed material) 50 to a thick plate 40 using the bolt 10 of this embodiment will be described. A through hole 51 that is larger than the outer diameter d of the fully threaded portion 35 of the bolt 10 and smaller than the diameters of the head 20 and nut 60 of the bolt 10 is formed in advance in the plate material 50 to be fixed. The thickness of the plate material 50 used is thinner (shorter) than the length of the cylindrical portion 31 of the bolt 10.

As shown in FIG. 2(a), the through hole 51 of the plate material 50 is aligned and positioned in front of the screw hole 41 of the thick plate 40, and the shaft portion 30 of the bolt 10 is inserted into the through hole 51 of the plate material 50 and the screw hole 41 of the thick plate 40. A female thread portion 42 is formed in the screw hole 41, and the fully threaded portion 35 of the bolt 10 can be screwed into it. The bolt 10 is rotated with a tool or the like (not shown), and the shaft portion 30 of the bolt 10 is moved to the back of the screw hole 41 of the thick plate 40 and tightened.

As shown in FIG. 2B, when the base end of the complete threaded portion 35 of the bolt 10 reaches the front end, which is the opening end of the screw hole 41 of the thick plate 40, the female threaded portion 42 of the thick plate 40 and the complete threaded portion 35 of the bolt 10 can be released from each other. When the bolt 10 continues to rotate, the female threaded portion 42 of the thick plate 40 at the portion where the screwing with the complete threaded portion 35 is released moves to the non-threaded portion 33 via the incomplete threaded portion 34. Here, the diameter φ of the non-threaded portion 33 is smaller than the inner diameter d1 of the complete threaded portion 35. This means that the diameter φ of the non-threaded portion 33 is smaller than the inner diameter D1 of the female threaded portion 42 of the thick plate 40, and D1>d1>φ. Therefore, a clearance exists between the female threaded portion 42 of the thick plate 40 and the non-threaded portion 33 of the shaft portion 30, and the female threaded portion 42 of the thick plate 40 does not interfere with the non-threaded portion 33 of the bolt 10.

As a result, even if the non-threaded portion 33 of the bolt 10 reaches the front end of the screw hole 41 in the thick plate 40, the rotation of the bolt 10 is not restricted. Therefore, as shown in FIG. 2(c), the bolt 10 can continue to rotate and move further inside the thick plate 40, and the plate material 50 can be tightened and fixed by the head 20 of the bolt 10 and the thick plate 40. Note that even if the length of the cylindrical portion 31 of the shaft 30 is shorter than the thickness of the plate material 50, the plate material 50 can be tightened and fixed by the head 20 of the bolt 10 and the thick plate 40 in a similar manner.

According to the bolt 10 of the above embodiment, the following effects can be obtained.
(1) In the above embodiment, the shank 30 has a fully threaded portion 35 and a non-threaded portion 33 on which no threads are formed, and the non-threaded portion 33 has a diameter φ smaller than the inner diameter d1 of the fully threaded portion 35. Therefore, even if the non-threaded portion 33 of the screwed bolt 10 reaches the front end of the screw hole 41 in the thick plate 40, the non-threaded portion 33 does not interfere with the female screw portion 42 of the screw hole 41. The bolt 10 can continue to rotate while being screwed into the thick plate 40, and the non-threaded portion 33 of the bolt 10 can move further inside the screw hole 41 in the thick plate 40.

(2) When the plate material 50 is fixed by the bolt 10 and the thick plate 40, even if the length of the non-threaded portion 33 is longer than the thickness of the plate material 50, the non-threaded portion 33 of the bolt 10 can enter the screw hole 41 of the thick plate 40. Therefore, the plate material 50 can be tightened and fixed by the head 20 of the bolt 10 and the thick plate 40.

(3) The non-threaded portion 33 has a length of 1 mm to 10 mm. Therefore, even if the plate material 50 to be fixed is thin, it can be fastened by using the bolt 10.
(4) The diameter φ of the non-threaded portion 33 is 0.1 mm to 1 mm smaller than the inner diameter d1 of the fully threaded portion 35. Therefore, the non-threaded portion 33 can secure a sufficient clearance to prevent interference with the female threaded portion 42 of the thick plate 40 with which it is screwed.

(5) The bolt 10 is made of stainless steel, so it has excellent strength and corrosion resistance.
The above embodiment may be modified as follows.
Although this embodiment is embodied in the hexagon socket extra low head bolt 10, it may be of other shapes for the head 20. For example, it may be of a machine screw type, a hexagonal column type, or a head 20 of other shapes on which a tool or a hand can be hooked.

Although stainless steel is used for the bolt 10, other materials such as steel, brass, aluminum, titanium, and resin may also be used.
- The diameter φ of the non-threaded portion 33 need only be large enough so as not to interfere with the inner diameter D1 of the female threaded portion 42 of the thick plate 40, and can be set appropriately within a range that can maintain the strength of the bolt 10 depending on the size and material of the thick plate 40, etc.

The length of the non-threaded portion 33 may be changed depending on the size, material, intended use, etc. of the bolt 10.
The non-threaded portion 33, on which no threads are formed, has a circular cross section, but is not limited to this. For example, it may have a polygonal prism shape. In this case, the length of the cross-sectional diagonal of the polygonal prism needs to be smaller than the inner diameter d1 of the completely threaded portion 35 so as not to interfere with the female threaded portion 42 of the thick plate 40.

- The non-threaded portion 33 has a constant diameter φ, but the diameter φ may be changed in the length direction. In this case, the diameter φ at the end side of the non-threaded portion 33 can be made larger. This invention is included as long as at least a part of the non-threaded portion 33 is smaller than the inner diameter d1 of the fully threaded portion 35.

Although the thick plate 40 is used as the mating material, the mating material is not limited to a plate-like material as long as the bolt 10 can be screwed into the mating material. Any material may be used as long as it has a female thread portion 42 into which the bolt 10 can be screwed.
Although one plate material 50 is used as the fixed member, the fixed member is not limited to one, and may be multiple. Also, the fixed member is not limited to being in a plate shape.

Next, an embodiment in which a nut 60 is used as the mating member will be described with reference to FIG.
3, the nut 60 is a so-called hexagonal nut having a hexagonal cylindrical shape with a screw hole 61, and a female threaded portion 62 having an inner diameter D1 that screws into the fully threaded portion 35 of the bolt 10 is formed in the screw hole 61. The nut 60 can be a standard commercially available product that corresponds to the nominal diameter 6 of the bolt 10 to be used, and detailed description thereof will be omitted.

A method of fixing two plate materials (fixed materials) 50 to a nut 60 using the bolt 10 of this embodiment will be described. Each of the two plate materials 50 to be fixed has a through hole 51 formed in advance that is larger than the outer diameter d of the fully threaded portion 35 of the bolt 10 and smaller than the diameter of the head 20 of the bolt 10 and the nut 60. In addition, the total thickness of the plate materials 50 used is thinner (shorter) than the length of the cylindrical portion 31 of the bolt 10.

As shown in FIG. 3(a), the through holes 51 of the two plate materials 50 to be fixed are fitted onto the shaft portion 30 of the bolt 10. Since the thickness of the two plate materials 50 is shorter than the length of the cylindrical portion 31 of the bolt 10, when the two plate materials 50 are positioned in contact with the seat surface 22 of the head 20 of the bolt 10, the cylindrical portion 31 of the shaft portion 30 of the bolt 10 is exposed from the through holes 51 of the plate materials 50. Then, a nut 60 is screwed onto the shaft portion 30 of the bolt 10, and the nut 60 is rotated to move toward the base end of the shaft portion 30.

As shown in FIG. 3B, when the nut 60 moves to the base end of the complete threaded portion 35 of the shaft portion 30, the female threaded portion 62 of the nut 60 at the base end side can be released from the complete threaded portion 35 of the bolt 10. When the nut 60 continues to rotate, the female threaded portion 62 of the nut 60 at the part where the screw engagement with the complete threaded portion 35 is released moves to the non-threaded portion 33 via the incomplete threaded portion 34. Here, the diameter φ of the non-threaded portion 33 is smaller than the inner diameter d1 of the complete threaded portion 35, and the diameter φ of the non-threaded portion 33 is smaller than the inner diameter D1 of the female threaded portion 62 of the nut 60. Therefore, a clearance exists between the female threaded portion 62 of the nut 60 and the non-threaded portion 33 of the shaft portion 30, and the female threaded portion 62 does not interfere with the non-threaded portion 33.

As a result, even if the fully threaded portion 35 reaches the non-threaded portion 33 of the shaft portion 30 while the nut 60 is rotating, the rotation and movement of the nut 60 are not restricted by the non-threaded portion 33. Therefore, as shown in FIG. 3(c), the nut 60 can continue to rotate and move, and the head 20 of the bolt 10 and the nut 60 can fasten and fix the two plate materials 50 together. Note that if the length of the cylindrical portion 31 of the shaft portion 30 is shorter than the thickness of the two plate materials 50, the cylindrical portion 31 is not exposed from the plate materials 50, and the two plate materials 50 can be fastened and fixed together by the head 20 of the bolt 10 and the nut 60 in the same manner.

The same effects as those of the previous embodiment can be obtained by fixing the plate material 50 with the bolts 10 and nuts 60 of the above embodiment.
The above embodiment may be modified as follows.

A washer may be used when fastening the bolt 10 and the nut 60. The nut 60 may be a double nut.
Next, the technical ideas that can be understood from the above-described embodiment and other examples will be described below together with their effects.

(a) The bolt is a hexagon socket low head bolt. According to the invention described in (a), the head 20 of the bolt 10 can be made thin.

10: Bolt 20: Head 30: Shank 31: Cylindrical portion 32: Threaded portion 33: Non-threaded portion 34: Incompletely threaded portion 35: Completely threaded portion 36: Chamfered portion 40: Thick plate (mate material)
50...Plate material (material to be fixed)
60...Nut (mate material)
φ: diameter (of non-threaded portion 33) d1: inner diameter (of fully threaded portion 35) d: outer diameter (of fully threaded portion 35) D1: inner diameter (of female threaded portions 42, 62)

Claims (4)

A bolt that fastens a workpiece to a mating material with which it is screwed,
The bolt has a head and a shaft.
The shaft portion has a fully threaded portion and a non-threaded portion located proximal to the fully threaded portion and having no threads formed therein,
The non-threaded portion has a diameter smaller than an inner diameter of the fully threaded portion. The bolt according to claim 1, wherein the non-threaded portion has a length of 1 mm to 10 mm. The bolt according to claim 2, wherein the non-threaded portion has a diameter 0.1 mm to 1 mm smaller than the inner diameter of the fully threaded portion. 4. The bolt of claim 3, wherein said bolt is formed from stainless steel.

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