Fastening member

Abstract

To provide a fastening member that is relatively easy to manufacture, and does not require use of a dedicated wrench to control a tightening torque.SOLUTION: A fastening member is, for example, a hexagonal nut 1 having a female thread part 10. The nut 1 has a first portion 11 and a second portion 12 located closer to a fastening target material 6 than the first portion 11. The first portion 11 is a portion into which a non-illustrated rotational operating tool (such as an impact wrench and a hexagonal socket set therein) is fitted. The first portion 11 and second portion 12 are connected by a connection part 13 that breaks when the first portion 11 is tightened by rotation of the rotational operating tool with a tightening torque required for the second portion 12.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] This invention relates to fastening members such as nuts and bolts.

Background Art

[0002] Patent Document 1 discloses a double nut in which a first nut and a second nut are firmly integrated and can exhibit a loosening prevention function. This double nut includes a first nut and a second nut. The first nut is provided with a cylindrical convex portion eccentric with respect to the first screw hole, and the second nut is provided with a fitting portion eccentric with respect to the second screw hole and fitting with the convex portion.

[0003] Conventionally, a method of fixing a member by performing torque control with a socket wrench is known. In this method, since the tightening torque is ensured by breaking the pin tail of the bolt, it has excellent accuracy in the fastening torque and does not particularly require a torque measuring tool or the like.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, although the technique disclosed in Patent Document 1 can exhibit a loosening prevention function by integrating two nuts, its production is not easy, and it is not easy to perform appropriate torque control either. Also, in torque control using a bolt with a pin tail, it is necessary to use a dedicated socket wrench.

[0006] An object of this invention is to provide a fastening member that is relatively easy to manufacture and does not require a dedicated socket wrench to control the tightening torque.

Means for Solving the Problem

[0007] In order to solve the above problems, the fastening member of the present invention is a fastening member having a threaded portion, and has a first portion to which a rotary operating tool is attached and a second portion located closer to the material to be fastened than the first portion. The first portion is connected to the second portion by a connecting portion that is broken when the first portion is tightened by the rotary operating tool with the tightening torque required for the second portion.

[0008] With the above configuration, since the first portion and the second portion are connected by the connecting portion, the manufacturing is relatively easy. Also, by tightening the first portion with the rotary operating tool set to a torque larger than the specified torque required for the second portion, the first portion will be tightened with the specified torque, so the fastening operation becomes simple. That is, by tightening such a rotary operating tool, the connecting portion breaks, and by this breakage, the second portion is tightened with the tightening torque required for the second portion. Further, as the rotary operating tool, an impact wrench or the like equipped with a hexagonal socket that fits only on the first portion may be used, and it is not necessary to control the tightening torque using a dedicated torque wrench.

[0009] The fastening member is a nut, and the connecting portion may be a remaining portion formed by a cut portion cut orthogonally to the female screw portion of the screw portion of the nut so as to form a boundary between the first portion and the second portion. According to this, for example, the connecting portion can be formed by a relatively simple method of forming the cut portion at a predetermined depth at an intermediate position in the height direction of a ready-made nut to obtain a remaining portion. Also, by further rotating the first portion after the breakage, a double-nut structure is formed and loosening of the second portion is prevented.

[0010] The fastening member is a nut, and the connecting portion may be a metal portion provided at the opposing portion of the first portion and the second portion to join the first portion and the second portion.

[0011] The metal portion may be formed by projection welding. Alternatively, the metal portion may be composed of a pin that is fitted into fitting holes formed in each of the first portion and the second portion to join the first portion and the second portion.

[0012] At the separation location of the first portion and the second portion, there may be an adhesive that adheres the first portion and the second portion when pressurized. According to this, a stronger anti-loosening can be realized.

[0013] The adhesive may be colored and may protrude from the separation location when pressurized. According to this, both the application of a tightening marking and a strong anti-loosening can be realized.

[0014] The fastening member is a bolt, and the connecting portion may be formed on the bolt head.

[0015] In the bolt or nut, at the separation location of the first portion and the second portion, there may be a colored material that protrudes from the separation location when pressurized. According to this, the colored material protruding from the separation location becomes a tightening marking.

Advantages of the Invention

[0016] According to the present invention, manufacturing is relatively easy, and various effects such as not having to control the tightening torque using a dedicated wrench are achieved.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0018] (Embodiment 1) Hereinafter, embodiments of the present invention will be described based on the accompanying drawings. The fastening member of the embodiment is a hexagonal nut 1 having an internal thread portion 10 as shown in FIGS. 1(A), 1(B), and 1(C). This nut 1 has a first portion 11 and a second portion 12 located closer to the member to be fastened 6 than the first portion 11. The first portion 11 is a portion into which a rotating operation tool (for example, a hexagonal socket set in an impact wrench) (not shown) fits. The above rotating operation tool does not fit into the second portion 12.

[0019] The first portion 11 and the second portion 12 are connected by a connecting portion 13. The connecting portion 13 is broken when the first portion 11 is tightened by the rotation of the rotating operation tool with the tightening torque required for the second portion 12.

[0020] As shown in Fig. 2, the connecting portion 13 is a ring-shaped remaining portion located between the cut portion 14 cut orthogonally to the female screw portion 10 of the off-the-shelf nut before it becomes the nut 1 and the female screw portion 10 so as to form the boundary between the first portion 11 and the second portion 12. Such a remaining portion can be formed, for example, by applying a disk cutter C to the side surface (hexagonal surface side) of the nut 1 while rotating the off-the-shelf nut around the central axis of the nut and cutting it. It is desirable that the width (thickness of the disk cutter C) of the cut portion 14 be, for example, equal to or less than the pitch of the thread of the female screw portion 10.

[0021] Also, in the cut portion 14 which is the separation location between the first portion 11 and the second portion 12, a colored material 3 made of, for example, resin that protrudes from the cut portion 14 when pressurized is adhered. The above-mentioned pressurization occurs when the first portion 11 approaches the second portion 12 due to further rotation of the first portion 11 after the breakage of the connecting portion 13, that is, when a locked state by a double nut is formed.

[0022] With the above configuration, since the first portion 11 and the second portion 12 are connected by the connecting portion 13, the nut 1 can be manufactured relatively easily. Also, by simply tightening the first portion 11 with the above-mentioned rotation operating tool set to a torque larger than the tightening torque required for the second portion 12, the first portion 11 is tightened to the specified torque, so the fastening work becomes easy. That is, by tightening such a rotation operating tool, the connecting portion 13 breaks, and due to this breakage, the second portion 12 is tightened to the tightening torque required for the second portion 12. Then, by further rotating the first portion 11, a double nut structure is formed and the loosening of the second portion 12 is prevented. Also, for the above-mentioned rotation operating tool, for example, a hexagonal socket having a depth that fits only into the first portion 11 can be used, and there is no need to control the tightening torque using a dedicated torque wrench.

[0023] If the connecting portion 13 is the remaining portion due to the cut portion 14, for example, the connecting portion 13 can be formed by a relatively simple method such as forming the cut portion 14 at a predetermined depth at the intermediate position in the height direction of a ready-made nut to obtain the remaining portion.

[0024] For example, in the female thread portion 10 of an M12 nut which is a ready-made nut, the inner diameter is 10.23 mm and the bottom diameter is 11.85 mm. When the side surface (hexagonal surface side) of the ready-made nut is shaved with a disk cutter C and the ring-shaped connecting portion 13 is formed so that the thickness becomes 1 mm with respect to the bottom diameter (11.85 mm), the area (shearing portion area) of this connecting portion 13 is 40.4 mm 2 This results in a shearing strength of the connecting portion 13 of 9938.4 (Max 410 N / mm 2 × 40.4 mm × 0.6), and the connecting portion 13 is sheared with a force of about 10 N·m, resulting in the double nut structure.

[0025] Also, if the coloring material 3 is attached to the cut portion 14 which is the separation location between the first portion 11 and the second portion 12, the coloring material 3 protruding from the separation location serves as a tightening marking, eliminating the need for an operator to manually write the tightening marking using paint.

[0026] Note that an adhesive (for example, Loctite (registered trademark)) that adheres the first portion 11 and the second portion 12 by being pressurized may be attached to the separation location between the first portion 11 and the second portion 12. According to this, a stronger anti-loosening can be achieved by adhesion. The above adhesive may be colored and may protrude from the separation location when pressurized. According to this, both the application of the tightening marking and a strong anti-loosening can be achieved.

[0027] A modified example of the nut 1 is shown in Fig. 3(A). In this modified example of the nut 1, for example, a ready-made nut is fixed so that the ready-made nut does not rotate, and a disk cutter C is applied to the side surface (hexagonal surface side) of the ready-made nut sequentially from two directions facing each other and cut, whereby a connection portion 13 (remaining portion) with a predetermined area is formed. The connection portion 13 formed in this way is located at two positions on the edge side with the female screw portion 10 interposed therebetween in a plan view of the nut 1. The shear strength of the connection portion 13 in this case can be calculated by multiplying the total area of the two positions on the edge side by 0.6 times the material strength.

[0028] Also, another modified example of the nut 1 is shown in Fig. 3(B). In this modified example of the nut 1, for example, a ready-made nut is fixed so that the ready-made nut does not rotate, and a disk cutter C is applied to the side surface (hexagonal surface side) of the ready-made nut sequentially from three directions shifted by approximately 120 degrees from each other and cut, whereby a connection portion 13 (remaining portion) with a predetermined area is formed. The connection portion 13 formed in this way is located at three positions near the female screw portion 10 with the female screw portion 10 interposed therebetween in a plan view of the nut 1. The shear strength of the connection portion 13 in this case can be calculated by multiplying the total area of the three positions in the vicinity by 0.6 times the material strength.

[0029] (Embodiment 2) Next, a fastening member according to another embodiment will be described with reference to the drawings. As shown in Figs. 4(A) and 4(B), the fastening member of this embodiment is the nut 1 and has a structure having a connection portion 13A which is a metal portion. The connection portion 13A is provided at an opposing portion between the first portion 11 and the second portion 12 and joins the first portion 11 and the second portion 12. A gap portion 14A (separated portion) with a predetermined width is formed between the first portion 11 and the second portion 12. Note that the connection portion 13A is located, for example, at two positions at a predetermined distance from the female screw portion 10 with the female screw portion 10 interposed therebetween in a plan view of the nut 1. The shear strength of the connection portion 13A in this case can be calculated by multiplying the total area of the two positions at the predetermined distance from each other by 0.6 times the material strength. Of course, the formation position and number of the connection portion 13A are not limited to such an example.

[0030] The connecting part 13A is formed by projection welding. As an example, between the separated first part 11 and the second part 12 where the female screw part 10 has not yet been formed in the central hole part, a metal ball serving as the connecting part 13A is arranged, and pressure is applied to the metal ball. Then, by the heat generated from flowing a large current through the metal ball, the metal ball is melted to obtain the connecting part 13A. After that, taps T are made in both central hole parts of the first part 11 and the second part 12 to form the female screw part 10. Note that instead of the metal ball, the first part 11 or the second part 12 may be processed to have a metal convex part.

[0031] (Embodiment 3) Next, a fastening member of another embodiment will be described with reference to the drawings. As shown in FIGS. 5(A) and 5(B), the fastening member of this embodiment is a nut 1 and has a structure with a connecting part 13B which is a metal part. The connecting part 13B is provided at the opposing locations of the first part 11 and the second part 12 to join the first part 11 and the second part 12. A gap part 14A (separated location) with a predetermined width is formed between the first part 11 and the second part 12.

[0032] The connecting part 13B consists of metal pins that are fitted into fitting hole parts formed in each of the first part 11 and the second part 12 to join the first part 11 and the second part 12. The connecting part 13B is located, for example, at two locations separated by a predetermined distance from the female screw part 10 with the female screw part 10 being sandwiched in a plan view of the nut 1. In this case, the shear strength of the connecting part 13B can be calculated by multiplying the total area of the two locations separated by the predetermined distance by 0.6 times the material strength. Of course, the formation position and number of the connecting part 13B are not limited to such an example.

[0033] In the production of the nut 1 having the connecting part 13B, for example, between the separated first part 11 and the second part 12 where the female screw part 10 has not yet been formed in the central hole part, the above-mentioned pins serving as the connecting part 13B are press-fitted into the fitting hole parts. After that, taps T are made in the central hole part to form the female screw part 10.

[0034] Even for these modified examples, by simply tightening the first part 11 with the above-described rotary operating tool set to a torque greater than the tightening torque required for the second part 12, the first part 11 will be tightened with the specified torque, thus simplifying the fastening operation. Then, by further rotating the first part 11, a double-nut structure is formed to prevent loosening of the second part 12.

[0035] Since the connecting parts 13A and 13B are the above-described metal parts, the connecting parts 13A and 13B can be formed by relatively simple methods such as projection welding of a metal ball or press-fitting of a pin.

[0036] Note that also in these modified examples, the coloring material 3 or the above-described adhesive may be attached to the gap part 14A which is the separated part between the first part 11 and the second part 12.

[0037] Also, in the above embodiment, the nut 1 is shown as the fastening member. However, as shown in FIG. 6, at the head of the bolt 1B as the fastening member having the male screw part 10B, a connecting part 13C (cutting part 14) may be provided on the central side thereof. The first part 11 of the bolt 1B is tightened only by a rotary operating tool set to a torque greater than the specified torque required for the second part 12 having the male screw part 10B, and the male screw part 10B of the second part 12 will be tightened with the specified torque. That is, by tightening such a rotary operating tool, the connecting part 13C breaks, and due to this breakage, the second part 12 is tightened with the tightening torque required for the second part 12. In the bolt 1B, when the connecting part 13C breaks, the first part 11 detaches from the second part 12. Note that if a coloring material is attached to the cutting part 14 which is the separated part between the first part 11 and the second part 12, the coloring material protruding from the separated part becomes a tightening marking. Also, the head of the bolt 1B may be a hexagonal head or a round head having a hexagonal recess in the center part.

[0038] The embodiments of the present invention have been described above with reference to the drawings. However, the present invention is not limited to the illustrated embodiments. Various modifications and variations can be made to the illustrated embodiments within the same scope or an equivalent scope of the present invention.

Explanation of Reference Numerals

[0039] 1: Nut (fastening member) 1B: Bolt (fastening member) 3: Coloring material 6: Material to be fastened 10: Female screw portion (screw portion) 10B: Male screw portion (screw portion) 11: First part 12: Second part 13: Connection part 13A: Connection part 13B: Connection part 13C: Connection part 14: Notch part 14A: Gap part C: Disk cutter T: Tap

Claims

1. A fastening member having a threaded portion, comprising a first portion to which a rotary operating tool is attached and a second portion located closer to the member to be fastened than the first portion and to which the rotary operating tool is not attached, wherein the first portion is connected to the second portion by a connecting portion that breaks when the first portion is tightened by the rotary operating tool with a tightening torque required for the second portion.

2. The fastening member according to claim 1, wherein the fastening member is a nut, and the connecting portion is a remaining portion of a cut portion cut orthogonally to a female threaded portion which is the threaded portion of the nut so as to form a boundary between the first portion and the second portion.

3. The fastening member according to claim 1, wherein the fastening member is a nut, and the connecting portion is a metal portion provided at a facing position between the first portion and the second portion for joining the first portion and the second portion.

4. The fastening member according to claim 3, wherein the metal portion is formed by projection welding.

5. The fastening member according to claim 3, wherein the metal portion is a pin fitted into fitting hole portions formed in each of the first portion and the second portion for joining the first portion and the second portion.

6. The fastening member according to any one of claims 2 to 5, further comprising an adhesive for adhering the first portion and the second portion by being pressurized at a separating position between the first portion and the second portion.

7. The fastening member according to claim 6, wherein the adhesive is colored and protrudes from the separating position when pressurized.

8. The fastening member according to claim 1, wherein the fastening member is a bolt, and the connecting portion is formed on a bolt head.

9. The fastening member according to any one of claims 2 to 5 and claim 8, further comprising a colored material that protrudes from a separating position between the first portion and the second portion when pressurized.

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