Lock nut

Abstract

To provide a lock nut which has a small number of components and is excellent in portability and workability and suitable for reduction of the size and the weight.SOLUTION: A lock nut is screwed onto a thread section 2a of a bolt 2 and has a body section 3 formed by spirally winding a wire material which has a rectangular cross section. A thread groove 5 for engaging the thread section 2a is formed on an inner-circumferential surface 3c of the body section 3 across the entire length thereof in an axial direction. The body section 3 is screwed and mounted onto a thread section 2b of the bolt 2 which is provided penetrating through fastening targets Wa, Wb. When force is applied to the mounted body section 3 in a releasing direction for loosening the body section 3, the wire material is reduced in diameter by elastic deformation, and as a result, friction occurs between the body section 3 and the thread section 2b to prevent the body section 3 from loosening effectively.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a locking nut, and more particularly to a technique for preventing a nut attached to the threaded portion of a bolt from loosening or falling off due to loosening. [Background technology]

[0002] Conventionally, as this type of locking nut, a locking nut that uses wedge technology is known (see, for example, Patent Document 1).

[0003] Figure 4 shows a conventional locking nut a. This locking nut a is composed of a nut body b and a washer c that is used in combination with the nut body b. The nut body b has a recess g on the tightening bearing surface d that is larger in diameter than the threaded hole e and whose inner circumferential side forms a tapered surface f in the shape of a truncated cone, and is provided coaxially with the threaded hole e.

[0004] On the other hand, the washer c has a tapered surface i in the shape of a truncated cone on the outer peripheral surface of the bolt insertion hole h, and this tapered surface i forms a protrusion j that can be fitted into the recess g of the nut body b, but the center line B of this tapered surface i is offset by a small distance L from the center line A of the bolt insertion hole h.

[0005] In locking nut a configured in this way, washer c is fitted onto the threaded portion q of bolt p, which is inserted through fastened objects m and n, and nut body b is screwed on and tightened. Since the tapered surface i of protruding portion j of washer c, which is fitted into recess g of nut body b, is eccentric by a distance L from the axis of threaded hole e, tapered surface f of recess g, and bolt insertion hole h of washer c (see center line A in the diagram), a wedge action occurs between tapered surface f of nut body b and tapered surface i of washer c, and a pressing force acts on threaded portion q in a direction perpendicular to the axis. This pressing force gradually increases until tightening seat d of nut body b comes into close contact with washer c, thereby exerting a powerful locking effect on locking nut a. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Utility Model Application Publication No. 57-184308 Summary of the Invention [Problem to be solved by the invention]

[0007] However, such conventional locking nuts have the following problems, and improvements are desired.

[0008] (1) Conventional locking nuts a consist of two parts: a nut body b and a washer c. This means that the nut has a large number of parts, making it difficult to handle.

[0009] That is, conventional locking nut a will not function as a locking nut a if either the nut body b or the washer c is missing, so users of locking nut a must always carry both the nut body b and the washer c, which makes it difficult to carry. In particular, at work sites where this type of locking nut is used (for example, construction sites such as bridges), workers often carry the nut in their pockets, so there has been a strong demand for easier portability.

[0010] Furthermore, conventional locking nuts a require two steps for use: fitting washer c and screwing nut body b, which makes installation a time-consuming process and reduces work efficiency.

[0011] (2) Conventional locking nuts (a) have a structure in which the tapered surface (i) of the protrusion (j) formed on the washer (c) acts as a wedge, so the nut body (b) and the washer (c) must be made of a strong material that is not easily damaged or deformed. For this reason, conventional locking nuts (a) are often made of metal, especially high-strength iron or stainless steel, which tends to make each locking nut heavy.

[0012] Therefore, conventional locking nuts a tend to increase the overall weight of the object to which they are attached, and there was a need to improve this (to provide a lightweight locking nut).

[0013] The present invention has been made in consideration of these problems, and its purpose is to provide a locking nut that has a small number of parts, is easy to carry and use, and is suitable for being small and lightweight. [Means for solving the problem]

[0014] In order to achieve the above-mentioned object, the anti-loosening nut of the present invention is a anti-loosening nut that is attached to the threaded portion of a bolt, and is characterized in that it has a main body portion formed by spirally winding a wire rod having a rectangular cross section, and the main body portion has a thread groove formed on its inner surface over its entire axial length that screws into the threaded portion.

[0015] This locking nut has a thread groove formed on the inner circumferential surface of the body that threads onto the threaded portion over the entire axial length, so that by aligning the thread groove of the body with the threaded portion of the bolt and rotating the body in the tightening direction (the direction in which the nut is tightened), the body advances along the threaded portion and continues to advance until the body abuts against the object to be fastened (including a washer).

[0016] After the main body comes into contact with the workpiece, when force is applied to the main body in the tightening direction, the spirally wound wire expands while deforming against elasticity. This expansion temporarily loosens the engagement between the main body and the threaded portion, but when the force applied to the main body is released, the expanded wire in the main body returns to its original shape and contracts in diameter due to elastic deformation. At this time, the friction generated between the inner surface of the main body and the threaded portion tightens and fixes the main body to the threaded portion.

[0017] Once the main body is fastened and fixed in this way, even if a force is subsequently applied in the opposite direction to the fastening direction, i.e., in the removal direction (the direction to loosen the nut), the force will reduce the diameter of the main body and increase the friction between the inner surface of the main body and the threaded portion, so that the main body is firmly fastened to the threaded portion.

[0018] Therefore, with the anti-loosening nut of the present invention, after the main body is screwed onto the threaded portion of the bolt inserted into the object to be fastened and tightened to a position where it abuts against the object to be fastened, the nut will not loosen even if a force is applied to the main body in the direction of removal.

[0019] The present invention has the following features as its preferred embodiments. (1) The main body is characterized in that the wire is tightly wound. By tightly winding the wire in this manner, the thread groove formed on the inner surface of the main body can be formed continuously without interruption, and the main body can be smoothly attached to the threaded portion (rotated in the tightening direction).

[0020] (2) The main body is characterized by being made of a wire material made of metal or resin. In other words, the anti-loosening nut of the present invention prevents the nut from loosening by utilizing the diameter-reducing effect of the main body portion (tightening of the threaded portion) caused by a force acting in the direction of removal on the main body portion, so that resins other than metal can be used as the material for constructing the main body portion, making it possible to reduce the weight of the anti-loosening nut.

[0021] (3) The main body is characterized in that it is formed by forming a screw groove on the inner peripheral surface of a square spring. In this invention, the main body is constructed by forming a thread groove in a square spring, so the main body can be formed using, for example, a commercially available square spring, which allows the main body to be manufactured inexpensively and the locking nut to be provided at a low price.

[0022] (4) The main body has an outer peripheral surface formed in a hexagonal shape. In this invention, the outer surface of the main body is hexagonal, so when attaching the main body to the threaded portion of the bolt, the main body can be rotated in the tightening direction using a spanner or wrench, just like a hex bolt. [Effects of the Invention]

[0023] According to the present invention, the main body portion attached to the threaded portion of a bolt inserted into the object to be fastened reduces in diameter and is firmly fastened to the threaded portion when a force in the direction of removal is applied to the main body portion, thereby effectively preventing the main body portion from rotating in the direction of removal, i.e., preventing the main body portion attached to the threaded portion from loosening.

[0024] Furthermore, the locking nut according to the present invention is made up of only one body, so the number of parts is small, making it possible to provide a locking nut that is easy to carry and work with.

[0025] Furthermore, it is easy to manufacture a small body that can accommodate small-diameter bolts.Furthermore, the body of the locking nut according to the present invention can be made of resin, making it possible to provide a small and lightweight locking nut. [Brief explanation of the drawings]

[0026] [Figure 1] 1A and 1B are diagrams showing an example of the external configuration of a locking nut according to the present invention, with FIG. 1A being a front view and FIG. 1B being a plan view. [Figure 2] 4 is a cross-sectional view showing the locking nut attached to the threaded portion of a bolt. FIG. [Figure 3] FIG. 10 is a plan view showing another example of the locking nut. [Figure 4] FIG. 10 is a cross-sectional view showing a conventional locking nut attached to the threaded portion of a bolt. DETAILED DESCRIPTION OF THE INVENTION

[0027] Hereinafter, a locking nut according to the present invention will be described in detail with reference to the drawings. Embodiment 1 The locking nut 1 according to the present invention is a fastener used together with a bolt 2 to fix or tighten objects Wa and Wb to be fastened, and as shown in FIG. 1, is formed by spirally winding a wire rod.

[0028] First, a brief description will be given of the bolt 2 on which the locking nut 1 is used. As is well known, the bolt 2 is a fastener used together with a nut to fix or tighten the fastened objects Wa, Wb, and has a threaded portion (shank) 2a with threads formed thereon and a head 2b. In the example shown in Figure 2, the bolt 2 is a hexagonal bolt with a hexagonal head 2b, but the locking nut 1 according to the present invention can also be applied to bolts other than hexagonal bolts (for example, hexagon socket head bolts, eye bolts, etc.).

[0029] In contrast, the locking nut 1 is composed of a main body 3 made of a wire wound in a spiral shape, as shown in Figure 1. In this embodiment, the main body 3 is made of a metal wire having a rectangular cross section tightly wound in a spiral shape of the same diameter, and has a through hole 4 formed in its center that passes through in the axial direction.

[0030] In the locking nut 1 of this embodiment, the wire constituting the main body 3 has a rectangular cross section, and this wire is tightly wound so that the inner circumferential surface 3c of the main body 3 is a nearly flush cylindrical surface, and by making the inner circumferential surface 3c a flush cylindrical surface in this way, it is possible to easily perform the formation process (thread cutting process) of the thread groove 5, which will be described later. In the illustrated example, to clearly show that the wire is wound spirally, adjacent wires are drawn with a slight gap between them, but the wire of the main body 3 in this embodiment is wound so that adjacent wires are in tight contact with each other.

[0031] The reason why wire rods made of metal (for example, iron, stainless steel, aluminum, etc.) are used for the main body 3 is that the main body 3 can be configured to be elastically deformable and can have sufficient strength compared to other materials such as resin. Therefore, if strength as high as that of metal is not required, the main body 3 (wire rod) can also be configured using materials other than metal (for example, synthetic resins such as plastics, etc.).

[0032] In this embodiment, the upper end surface 3a and the lower end surface 3c of the main body 3 are each formed flat. This is because the upper end surface 3a or the lower end surface 3b of the main body 3 forms a seating surface that abuts against the fastened objects Wa, Wb when the main body 3 is used as a locking nut 1. Therefore, for example, if only one of the upper end surface 3b or the lower end surface 3c is used as the seating surface, it is sufficient to form only the side to be used as the seating surface (the upper end surface 3a or the lower end surface 3b) flat.

[0033] The through hole 4 constitutes a threaded hole in the locking nut 1 according to the present invention, and a thread groove 5 is formed on the inner peripheral surface 3c of the main body 3 that forms the through hole 4, over the entire length in the axial direction (see the vertical direction in FIG. 1(a)). The thread groove 5 is set in a shape that allows it to be threaded onto the threads of the bolt 2 to be used. In other words, the specific shape of the thread groove 5 (nominal diameter, pitch, etc.) is determined according to the specifications of the threads of the bolt 2 (thread diameter, pitch, etc.).

[0034] 1(a) shows the locking nut 1 with 5.5 turns of wire in the main body 3, but the number of turns N and the thickness (axial thickness) L1 of the wire constituting the locking nut 1 can be changed as needed. As will be described later, the locking nut 1 of the present invention achieves its locking effect by utilizing the friction generated between the threaded portion 2a and the wire (the inner peripheral surface 3a of the main body 3). Therefore, by increasing or decreasing the number of turns N and the wire thickness L1, the frictional force generated between the threaded portion 2a and the wire can be adjusted. In other words, increasing the number of turns N and the wire thickness L1 increases the frictional force acting between the threaded portion 2a and the wire, thereby improving the locking effect of the locking nut 1.

[0035] In addition, in the illustrated example, the overall shape of the main body 3 is shown as being a slightly flattened shape in which the radial length L3 is slightly longer than the axial length L2, but it is also possible to configure the main body 3 so that the axial length L2 is longer than the radial length L3 by changing the settings of the number of turns N of the wire and the thickness L1 of the wire.

[0036] Next, a method for manufacturing the locking nut 1 configured as described above will be described. As described above, the locking nut 1 according to this embodiment is mainly composed of the main body 3, which is made of tightly wound metal wire having a rectangular cross section, and therefore, for example, a commercially available square spring can be used as the wire. Commercially available square springs are inexpensive, so by using a square spring as the material for the main body 3, the manufacturing costs of the locking nut 1 can be kept low.

[0037] Then, a thread groove 5 is formed on the inner surface of a commercially available square spring using a metalworking tool for thread cutting such as a tap, thereby completing the locking nut 1 (main body 3) according to the present invention.

[0038] In this way, the locking nut 1 of the present invention can be completed by purchasing a commercially available square spring and forming the desired thread groove 5 in the purchased square spring, so the locking nut 1 can be manufactured with fewer steps and at low cost.

[0039] Next, how to use the locking nut 1 configured as above will be described with reference to FIG. When fastening objects Wa, Wb using the locking nut 1 according to the present invention to fasten them together, first the positions of the mounting holes ha, hb for inserting the bolt drilled in the fastened objects Wa, Wb are aligned, and the bolt 2 is inserted through the mounting holes ha, hb. In the illustrated example, the bolt 2 is inserted upward from below the fastened object Wb, which is located on the lower layer, through the mounting holes ha, hb, with the tip of the threaded portion 2a protruding outside the fastened object Wa.

[0040] Then, the main body 3 of the locking nut 1 is screwed onto the threaded portion 2a protruding from the fastened object Wa. That is, the thread groove 5 formed on the inner peripheral surface 3c of the main body 3 is aligned with the thread formed on the threaded portion 2a of the bolt 2, and the main body 3 is rotated in the tightening direction (the direction in which the nut is tightened, usually clockwise). This causes the main body 3 to move forward along the threaded portion 2a until the lower end surface 3b, which forms the seating surface, abuts against the fastened object Wa.

[0041] When the main body 3 is advanced until it abuts against the workpiece Wa, further force in the tightening direction is applied to the main body 3 from that position, tightening the workpieces Wa, Wb. As a result, the workpieces Wa, Wb are firmly tightened, and at the same time, a force that expands the spirally wound wire acts on the main body 3 against the elasticity of the wire. When the workpieces Wa, Wb are tightened and the tightening operation is stopped, the force that expanded the wire is released, and the expanded wire of the main body 3 returns to its original shape and contracts in diameter due to elastic deformation. At this time, friction is generated between the inner peripheral surface 3c of the main body 3 and the threaded portion 2a, and the main body 3 is tightened and fixed to the threaded portion 2a.

[0042] Once the main body 3 has been fastened to the threaded portion 2a in this way, if a force is subsequently applied in the opposite direction to the tightening direction, i.e., in the direction to loosen the nut (removal direction), the force acts to reduce the diameter of the spirally wound main body 3, thereby increasing the friction caused by contact between the threaded portion 2a of the bolt 2 and the inner peripheral surface 3c of the main body 3. As a result, the main body 3 is prevented from loosening in the removal direction, and the locking effect of the locking nut 1 is exerted.

[0043] Thus, according to the present invention, the main body 3 attached to the threaded portion 2b of the bolt inserted through the fastened objects Wa, Wb contracts in diameter and is firmly fastened to the threaded portion 2b when a force in the direction of removal acts on the main body 3, thereby effectively preventing loosening of the main body 3 attached to the threaded portion 2b.

[0044] Furthermore, because the locking nut 1 of the present invention is composed only of the main body 3, it is composed of fewer parts than conventional locking nuts that use wedge technology (locking nuts that use washers).As a result, the locking nut 1 of the present invention is more portable than conventional products, and can be used more easily because the process of attaching a washer can be omitted.

[0045] Furthermore, the locking nut 1 according to the present invention is suitable for miniaturization due to its simple structure, and it is possible to provide a locking nut 1 that can be applied to small bolts and screws, for example.

[0046] Furthermore, the locking nut 1 of the present invention allows the number of turns N and thickness L1 of the wire in the main body 3 to be adjusted depending on the strength of the locking effect required, and the material used to construct the main body 3 can also be selected, so that it is possible to provide, for example, a small, lightweight locking nut 1.

[0047] Embodiment 2 Next, another embodiment of the locking nut 1 according to the present invention will be described with reference to FIG. 3 has a modified shape of the outer peripheral surface 3d of the main body 3, but other structures are the same as those of the above-described embodiment 1. Therefore, parts that have the same configuration are given the same reference numerals and descriptions thereof will be omitted.

[0048] In the locking nut 1 shown in this embodiment, the outer peripheral surface 3d of the main body 3 is formed into a hexagonal prism shape that is hexagonal in plan view. By forming the outer peripheral surface 3d of the main body 3 into a hexagonal shape in this way, the locking nut 1 can be tightened using a tool (such as a spanner or wrench) that is used to tighten hexagonal nuts, improving the ease of installation of the locking nut 1. Note that, in the locking nut 1 shown in this embodiment, the outer peripheral surface 3d of the main body 3 has a shape that is suitable for manipulation with a tool, so it is of course possible to configure the outer peripheral surface 3d into a polygonal prism shape other than a hexagonal prism.

[0049] The above-described embodiments are merely preferred embodiments of the present invention, and the present invention is not limited to these, and various design modifications are possible within the scope of the present invention.

[0050] For example, in the above-described embodiment, the main body 3 is configured by tightly winding adjacent wire rods in close contact with each other, but if it is possible to form a screw groove 5 on the inner surface 3c of the main body 3, the main body 3 may be configured with a fixed gap between adjacent wire rods.

[0051] Furthermore, in the above-described embodiment, a case has been shown in which a square spring is used to manufacture the main body 3, but it is of course possible to manufacture the main body 3 using a wire material other than a square spring.

[0052] In addition, in the above-described embodiment, a structure is shown in which the anti-loosening nut 1 is directly abutted against the upper fastened object Wb when fastening the fastened objects Wa and Wb, but it is also possible to interpose a part such as a washer between the fastened object Wb and the anti-loosening nut 1, for example. [Explanation of symbols]

[0053] 1 Locking nut 2 bolts 2a Bolt thread 2b Bolt head 3 Main body 3a Top surface of the main body 3b Bottom surface of the main body 3c Inner surface of main body 3d Outer surface of the main body 4 through holes 5 Thread groove Wa,Wb Fastened object

Claims

1. A locking nut attached to the threaded portion of a bolt, a main body formed by spirally winding a wire rod having a rectangular cross section; The main body has a thread groove formed on its inner circumferential surface over the entire axial length to be threadedly engaged with the threaded portion. A locking nut characterized by:

2. 2. The locking nut according to claim 1, wherein the main body is formed by tightly winding the wire.

3. 3. The locking nut according to claim 1, wherein the main body is made of a wire material made of metal or resin.

4. 3. The locking nut according to claim 1, wherein the main body is formed by forming a thread groove on the inner peripheral surface of a square spring.

5. 3. The locking nut according to claim 1, wherein the outer circumferential surface of the main body is formed in a hexagonal shape.

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