JP5956045B1 - Lock nut - Google Patents

Abstract

Provided is a lock nut that is fastened to a male screw with good workability and exhibits a locking function. A main nut member 2 whose bottom surface 2B is pressed against a fastened surface C1 by being fastened to a male screw B2, and a top nut 2A provided on the top surface 2A side opposite to the bottom surface 2B of the main nut member 2. The auxiliary nut member 3 fastened to the male screw B <b> 2 together with the member 2, and a joint portion 4 that joins and integrates the main nut member 2 and the auxiliary nut member 3, and is pulled more than the main nut member 2 and the auxiliary nut member 3. A joint 4 having low strength, a lock pin insertion portion 6 penetrating from the bottom surface 2B of the main nut member 2 to the top surface 2A, and a lock pin 5 inserted into the lock pin insertion portion 6, and fastened to the male screw B2. And a lock pin 5 that comes into contact with the fastened surface C1 before the main nut member 2 and presses the auxiliary nut member 3 upward by being pressed against the fastened surface C1. [Selection] Figure 7

Description

  The present invention relates to a lock nut that is fastened to a male screw and exhibits a locking function.

  As a lock nut that is fastened to a male screw and exhibits a locking function, for example, a lock nut described in Patent Document 1 is known. 18 is a perspective view showing a lock nut described in Patent Document 1, FIG. 19 is a sectional view taken along the line 102A-102A in FIG. 18, and FIG. 20 is an explanatory view showing a method of using the lock nut of FIG.

  A lock nut 101A shown in FIGS. 18 and 19 is obtained by processing a commercially available hexagonal nut. A split slit 102 is formed on the upper side of the nut, and the split slit 102 is formed on the upper side. A lock resistance applying portion 103, a lock pin insertion hole 104 penetrating into the split slit 102, and a lock pin 105 inserted into the lock pin insertion hole 104. The dividing slit 102 is formed so as to divide almost the entire screw hole 106 vertically.

  With such a configuration, when the lock pin 105 is inserted until it comes into contact with the lower surface 131 of the lock resistance applying portion 103, the lower end portion 151 of the lock pin 105 protrudes from the bottom surface 113 of the lock nut 101A. . When the nut is fastened, a pressing force is applied to the protruding lower end portion 151 from the fastening object, so that the lock pin 105 moves upward, and the upper end portion 152 of the lock pin 105 moves on the lower surface 131 of the lock resistance applying portion 103. By pressing, the lock resistance applying portion 103 is deformed to warp upward.

  When the fastened object Y is fastened to the fastened object X by the lock nut 101A, as shown in FIG. 20 (a), the lock nut 101A is connected to the male screw B connected to the fastened object X and the fastened object Y, and the washer W. And screwed until the lower end 151 of the lock pin 105 contacts the surface of the washer W.

  Subsequently, as shown in FIG. 20B, when the lock nut 101A is further tightened with a fastening tool such as a spanner, the lock nut 101A is screwed downward along the male screw B, while the lock pin 105 is attached to the washer W. Therefore, the downward movement is restricted. For this reason, the lower end portion 151 of the lock pin 105 receives an upward pressing force by the reaction force from the washer W and moves upward, and the upper end portion 152 of the lock pin 105 presses the lower surface 131 of the lock resistance applying portion 103.

  Then, as shown in FIG. 20C, the lock resistance applying portion 103 is half pitch according to the length of the lock pin 105 by tightening until the bottom surface 113 of the lock nut 101 </ b> A comes into close contact with the surface of the washer W. The male screw surface of the screw hole 106 is strongly pressed against the screw surface of the male screw B to generate a large frictional resistance, thereby exhibiting a high loosening prevention effect.

  21 and 22 are a plan view and a left side view showing another lock nut described in Patent Document 1, and FIG. 23 is an explanatory view showing a method of using the lock nut shown in FIG. The lock nut 101B shown in FIGS. 21 and 22 is of a type that exerts a locking function by being overlapped and fastened on top of a normal nut. The outer edge portion 108 of the lock nut 101B is formed to have a smaller diameter than the outer edge portion of the lock target nut N, and one locking protrusion 109 is formed protruding from the outer edge portion 108. The locking protrusion 109 protrudes at a predetermined downward inclination angle, and the tip 191 extends downward from the bottom surface 114 of the lock nut 101B.

  When the lock target nut N is used to prevent the lock target nut N from being loosened, first, the lock target nut N is screwed into the male screw B and rotated until it comes into contact with the fastener X as shown in FIG. . Subsequently, when the lock nut 101B is screwed into the male screw B and rotated, as shown in FIG. 23 (b), the lock protrusion 109 protruding from the outer edge portion 108 having a smaller diameter than the outer edge portion of the lock target nut N is obtained. Is stopped when the leading end 191 contacts the upper end surface of the nut N to be locked.

  When the lock nut 101B is further tightened by a fastening tool such as a spanner, the lock nut 101B is screwed downward along the male screw B, while the lock projection 109 is moved downward by the upper end surface of the lock target nut N. Be regulated. Therefore, as shown in FIG. 23C, the lock nut 101B is inclined so as to lift the side on which the lock protrusion 109 is formed. As a result, the male screw surface of the male screw hole 107 of the lock nut 101B is strongly pressed against the screw surface of the male screw B to generate a large frictional resistance.

JP 2007-315524 A

  However, the conventional lock nuts 101A and 101B have the following problems. First, in the case of the former lock nut 101A, a crack 110 (see FIG. 20C) is generated from the back of the split slit 102 due to vibration or the like depending on the use environment. Further, when the crack 110 invades the bottom 113 side of the lock nut 110A, the fastening performance of the lock nut 110A is greatly deteriorated.

  On the other hand, in the case of the latter lock nut 101B, since the lock target nut N is fastened to the male screw B, and then the lock nut 101B is fastened, it is troublesome and the number of steps increases. Further, when the lock nut 101B is screwed into the male screw B, there is already a lock target nut N fastened to the male screw B, so that a fastening tool for fastening the lock nut 101B is not engaged with the lock target nut N. Workability is poor because it is necessary. Particularly, since the lock nut 101B is thin, there is a problem that it is very difficult to work.

  Accordingly, an object of the present invention is to provide a lock nut that is fastened to a male screw with good workability and exhibits a function of preventing loosening.

  The lock nut of the present invention is provided on the main nut member whose bottom surface is pressed against the surface to be fastened by being fastened to the male screw, and on the top surface side opposite to the bottom surface of the main nut member. An auxiliary nut member to be fastened, a joint portion for joining and integrating the main nut member and the auxiliary nut member, a joint portion having lower tensile strength than the main nut member and the auxiliary nut member, and a bottom surface of the main nut member A lock pin insertion part that penetrates from the top to the top surface, and a lock pin that is inserted into the lock pin insertion part, abuts on the surface to be fastened before the main nut member and presses against the surface to be fastened when fastened to the male screw And a lock pin that presses the auxiliary nut member upward.

  In the lock nut of the present invention, the main nut member and the auxiliary nut member are joined and integrated by the joint portion, so that it can be easily performed by a single operation using a fastening tool such as a socket or a spanner like a normal nut. It is possible to fasten to a male screw. When the lock nut is screwed in, the lock pin comes into contact with the fastened surface before the main nut member and is pressed against the fastened surface, whereby the auxiliary nut member is pressed upward. As a result, the auxiliary nut member is deformed so as to warp upward, so that the backlash of the screw is eliminated, a force for stretching the main nut member and the auxiliary nut member is generated, and a loosening prevention function is exhibited.

  Here, the lock pin insertion portion can be a through hole provided inside the side surface of the main nut member, but the lock pin insertion portion is opened toward the side of the main nut member. It is desirable that the groove is a concave groove having an opening, and further having a drop-off preventing part for preventing the lock pin from dropping from the opening. When the lock pin insertion part is a through hole provided on the inner side of the side surface of the main nut member, high-precision drilling is required in the thin part, but the lock pin insertion part is the main nut. When the concave groove opened toward the side of the member is used, the side surface of the main nut member may be cut, so that the processing becomes easy.

  Moreover, it is desirable that the lock pin forms a part of the side surface of the main nut member in a state of being fitted into the concave groove. As a result, the outer shape of the main nut member becomes almost the same as that of a normal nut in a state where the lock pin is inserted into the concave groove, and can be easily fastened by a fastening tool such as a socket or a spanner like a normal nut. It becomes possible.

  Moreover, it is desirable that the joint portion and the lock pin insertion portion are provided at diagonal positions of the main nut member. As a result, the auxiliary nut member is pressed upward by the lock pin provided at the diagonal position of the main nut member with the joint portion as a fulcrum, so that the auxiliary nut member is deformed to warp upward even with a slight pressing force. This eliminates screw backlash.

(1) A main nut member whose bottom surface is pressed against the surface to be fastened by being fastened to the male screw and an auxiliary provided on the top surface side opposite to the bottom surface of the main nut member and fastened to the male screw together with the main nut member A joint part that joins and integrates a nut member, a main nut member, and an auxiliary nut member, a joint part having lower tensile strength than the main nut member and the auxiliary nut member, and from the bottom surface to the top surface of the main nut member A lock pin insertion portion that is penetrated, and a lock pin that is inserted into the lock pin insertion portion, abuts on the surface to be fastened before the main nut member when being fastened to the male screw, and is pressed against the surface to be fastened According to the lock nut including the lock pin that presses the auxiliary nut member upward by means of a fastening tool such as a socket or a spanner like a normal nut, it is fastened to the male screw in a single operation with good workability. , It is possible to exhibit the self-locking function.

(2) The lock pin insertion portion has an opening portion that opens toward the side of the main nut member, and further includes a drop prevention portion that prevents the lock pin from falling off from the opening portion, thereby enabling processing. It is possible to provide an inexpensive lock nut that is easy and inexpensive to manufacture.

(3) By forming a part of the side surface of the main nut member with the lock pin fitted in the concave groove, it can be easily tightened with a fastening tool such as a socket or a spanner like an ordinary nut. And a special fastening tool is not required.

(4) Since the joint portion and the lock pin insertion portion are provided at the diagonal positions of the main nut member, the auxiliary nut member is deformed so that the auxiliary nut member warps upward even with a slight pressing force. Backlash can be eliminated, and the loosening prevention function can be efficiently exhibited.

It is a top view of the lock nut in a 1st embodiment of the present invention. It is a front view of the lock nut of FIG. It is the III-III sectional view taken on the line of FIG. It is a bottom view of the lock nut of FIG. It is the VV sectional view taken on the line of FIG. It is explanatory drawing which shows the usage method of the lock nut of FIG. 1, Comprising: It is a figure which shows the state before fastening. It is explanatory drawing which shows the usage method of the lock nut of FIG. 1, Comprising: It is a figure which shows the state after fastening. It is a longitudinal cross-sectional view of FIG. It is a front view of the lock nut in a 2nd embodiment of the present invention. It is a longitudinal cross-sectional view of the lock nut of FIG. FIG. 10 is a bottom view of the lock nut of FIG. 9. It is explanatory drawing which shows the usage method of the lock nut of FIG. 9, Comprising: It is a figure which shows the state after fastening. It is a front view of the lock nut in a 3rd embodiment of the present invention. It is a longitudinal cross-sectional view of the lock nut of FIG. It is the XV-XV sectional view taken on the line of FIG. It is a top view of the lock nut in a 4th embodiment of the present invention. It is the XVII-XVII sectional view taken on the line of FIG. It is a perspective view which shows the conventional lock nut. It is the 102A-102A sectional view taken on the line in FIG. It is explanatory drawing which shows the usage method of the lock nut of FIG. It is a top view which shows another conventional lock nut. It is a left view of the lock nut of FIG. It is explanatory drawing which shows the usage method of the lock nut of FIG.

(Embodiment 1)
1 is a plan view of a lock nut according to a first embodiment of the present invention, FIG. 2 is a front view, FIG. 3 is a sectional view taken along line III-III in FIG. 1, FIG. 4 is a bottom view, and FIG. It is V line sectional drawing.

  As shown in FIGS. 1 to 5, the lock nut 1 </ b> A according to the first embodiment of the present invention includes a main nut member 2 whose bottom surface 2 </ b> B is pressed against a fastened surface by being fastened to a male screw, and a main nut member 2. The auxiliary nut member 3 is provided on the top surface 2A side opposite to the bottom surface 2B, and is fastened to the male screw together with the main nut member 2, and the joint portion for joining and integrating the main nut member 2 and the auxiliary nut member 3 4 and a lock pin 5 that is inserted into the lock pin insertion portion 6 of the main nut member 2.

  The main nut member 2 has substantially the same shape as a normal hex nut, but is formed with a lock pin insertion portion 6 penetrating from the bottom surface 2B to the top surface 2A. The lock pin insertion portion 6 is a concave groove having an opening 6 </ b> A opened toward the side 2 </ b> C of the main nut member 2. The bottom surface 2B of the main nut member 2 is formed so that the entire surface is flat. The main nut member 2 is formed of a steel material such as a carbon steel material for machine structure, a rolled steel material for general structure, or a stainless steel material.

  The auxiliary nut member 3 has substantially the same shape as a normal hex nut, but is formed at a height of about 1.5 to 2 pitch thinner than the main nut member 2. The bottom surface 3B of the auxiliary nut member is formed so that the entire surface is flat. The top surface 3A is chamfered, but it may be formed so that the entire surface is flat. The auxiliary nut member 3 is formed of a steel material such as a carbon steel material for machine structure. When the main nut member 2 is a stainless steel material, the auxiliary nut member 3 is also the same material.

  The joint portion 4 is provided at a diagonal position of the main nut member 2 with respect to the lock pin insertion portion 6. The joint 4 is an adhesive that joins and integrates the main nut member 2 and the auxiliary nut member 3. In addition, the junction part 4 is formed in the state which fitted both the main nut member 2 and the auxiliary | assistant nut member 3 to the external thread, for example. Further, as will be described later, the joint portion 4 prevents the main nut member 2 and the auxiliary nut member 3 from being separated when the lock nut 1A is tightened to the male screw. Since the main nut member 2 and the auxiliary nut member 3 are separated from each other after the contact, the tensile strength is lower than that of the main nut member 2 and the auxiliary nut member 3. In addition, the junction part 4 may melt and integrate the main nut member 2 and the auxiliary nut member 3 by spot welding or the like.

  The lock pin 5 has an angled surface 5 </ b> C that forms a part of the side surface (hexagonal surface) of the main nut member 2 in a state of being inserted into the concave groove of the lock pin insertion portion 6. Maintain the width across flats. Further, the lock pin 5 has an inclined surface 5D that becomes narrower toward the outside than the width W1 of the concave groove of the lock pin insertion portion 6. On the other hand, the end portion of the opening 6A of the lock pin insertion portion 6 constitutes a drop prevention portion 6B that prevents the lock pin 5 from dropping from the opening 6A by being bent inward (inclined surface 5D side). ing.

  The lock pin 5 is formed to be longer than the distance from the bottom surface 2B of the main nut member 2 to the bottom surface 3B of the auxiliary nut member 3, and is fastened to the surface to be fastened before the main nut member 2 when fastened to the male screw. The auxiliary nut member 3 is pressed upward by abutting and being pressed against the fastening surface.

  Next, a method of using the lock nut 1A having the above configuration will be described. 6 is an explanatory view showing how to use the lock nut 1A shown in FIG. 1 and shows a state before fastening. FIG. 7 is an explanatory view showing how to use the lock nut 1A shown in FIG. FIG. 8 is a longitudinal sectional view of FIG.

  As shown in FIG. 6, when the lock nut 1 </ b> A is fitted and screwed into the male screw B <b> 2 communicated with the fastened member B <b> 1, the lower end portion 5 </ b> B of the lock pin 5 is fastened to the fastened member B <b> 1 before the main nut member 2. Abut. Subsequently, when the lock nut 1A is further tightened by the fastening tool, the lock nut 1A is screwed downward along the male screw B2, while the lock pin 5 is restricted from moving downward by the fastened surface C1. Thereby, the lower end portion 5B of the lock pin 5 receives an upward pressing force due to the reaction force from the fastened surface C1, and moves upward, and the auxiliary nut member 3 is pressed upward by the upper end portion 5A of the lock pin 5.

  As shown in FIGS. 7 and 8, when the bottom surface 2B of the lock nut 1A is tightened until it comes into close contact with the surface C1 to be fastened, the auxiliary nut member 3 is deformed so as to warp upward, and screw backlash occurs. As a result, a force for stretching the main nut member 2 and the auxiliary nut member 3 is generated, and the lock nut 1A exhibits a function of preventing loosening.

  As described above, in the lock nut 1A according to the present embodiment, it is possible to fasten the male screw B2 with a single work with a good workability by using a fastening tool such as a socket or a spanner as in the case of an ordinary nut, thereby exhibiting a locking function. Is possible. Further, the joint portion 4 has lower tensile strength than the main nut member 2 and the auxiliary nut member 3, and the joint portion 4 may be separated after the lock pin 5 comes into contact with the surface C1 to be fastened. By breaking the portion 4 first, the main nut member 2 and the auxiliary nut member 3 are protected.

  Moreover, in the lock nut 1A in this embodiment, since the lock pin insertion part 6 is a concave groove opened toward the side 2C of the main nut member 2, the side surface of the main nut member 2 may be cut. Therefore, it is possible to provide an inexpensive lock nut 1A that is easy to process and can be manufactured at a low cost.

  In the lock nut 1A according to the present embodiment, in order to prevent the lock pin 5 from dropping from the lock pin insertion portion 6 that is a concave groove, the end portion of the opening 6A of the lock pin insertion portion 6 is inward. Although the fall prevention part 6B is formed by bending, the lock pin insertion part 6 itself can be constituted as a dovetail groove that also serves as the fall prevention part 6B. Further, the drop-off prevention portion 6B can be configured by providing irregularities on the side surface of the lock pin insertion portion 6.

  Further, in the lock nut 1A according to the present embodiment, the joint portion 4 and the lock pin insertion portion 6 are provided at diagonal positions of the main nut member 2, so that the auxiliary nut member 3 is mainly used with the joint portion 4 as a fulcrum. Since the lock pin 5 provided at the diagonal position of the nut member 2 is pressed upward, the auxiliary nut member 3 is deformed to warp upward even with a slight pressing force so as to eliminate screw backlash. Efficiently demonstrates the function of preventing loosening. Note that the joint portion 4 and the lock pin insertion portion 6 are not necessarily provided at diagonal positions.

(Embodiment 2)
9 is a front view of the lock nut according to the second embodiment of the present invention, FIG. 10 is a longitudinal sectional view of the lock nut of FIG. 9, FIG. 11 is a bottom view of the lock nut of FIG. It is explanatory drawing which shows the usage method of, Comprising: It is a figure which shows the state after fastening. In addition, in the following description, the same code | symbol is attached | subjected about the same component as the above-mentioned lock nut 1A, and the detailed description is abbreviate | omitted.

  As shown in FIGS. 9-11, in lock nut 1B in 2nd Embodiment of this invention, the lock pin insertion part 6 is formed in two places of the diagonal position of the main nut member 2, Each lock pin insertion part A lock pin 5 is inserted into 6. Although not shown, the main nut member 2 and the auxiliary nut member 3 are joined and integrated by a joint portion having a lower tensile strength than the main nut member 2 and the auxiliary nut member 3.

  Also in the lock nut 1B having this configuration, the lock nut 1B is fitted and screwed into the male screw B2 communicated with the fastened member B1, and the lower end portions 5B of the two lock pins 5 are fastened before the main nut member 2 is fastened. When further tightened by the fastening tool from the state in contact with the member B1, the lower end portions 5B of the two lock pins 5 are moved upward by the reaction force from the fastened surface C1, and are moved upward. The auxiliary nut member 3 is pressed upward by the upper end portion 5 </ b> A of the pin 5.

  Then, as shown in FIG. 12, when the bottom surface 2B of the lock nut 1B is tightened until it comes into close contact with the fastened surface C1, the auxiliary nut member 3 is deformed so as to warp upward, and screw backlash is eliminated. A force that stretches the main nut member 2 and the auxiliary nut member 3 is generated, and the lock nut 1B exhibits a loosening prevention function.

(Embodiment 3)
13 is a front view of a lock nut according to a third embodiment of the present invention, FIG. 14 is a longitudinal sectional view of the lock nut of FIG. 13, and FIG. 15 is a sectional view taken along line XV-XV of FIG. In the following description, the same reference numerals are given to components common to the above-described lock nut 1A, and detailed description thereof is omitted.

  As shown in FIGS. 13 to 15, the lock nut 1 </ b> C according to the third embodiment of the present invention has a through hole 8 as a lock pin insertion portion inside the side surface of the main nut member 2. The through hole 8 is a round hole penetrating from the bottom surface 2B to the top surface 2A. A cylindrical lock pin 7 is fitted in the through hole 8.

  In the lock nut 1C having this configuration, similarly to the lock nut 1A, the lock nut 1C is fitted into the male screw B2 communicated with the fastened member B1 and screwed, and the bottom surface 2B of the lock nut 1C is in close contact with the fastened surface C1. When the nut is tightened, the auxiliary nut member 3 is deformed so as to warp upward, so that the backlash of the screw is eliminated, a force for stretching the main nut member 2 and the auxiliary nut member 3 is generated, and the lock nut 1C is prevented from loosening. Demonstrate the function.

  In the above-described embodiments, the hexagonal lock nuts 1A, 1B, and 1C have been described. However, the lock nut of the present invention is not limited to this. In short, it may be anything as long as it is rotated by a fastening tool and fastened to a male screw. Further, the lock nuts 1A, 1B, and 1C are not limited to being made of metal, and may be made of resin. Further, the shape of the lock pins 5 and 7 can be changed as appropriate.

(Embodiment 4)
16 is a plan view of a lock nut according to a fourth embodiment of the present invention, and FIG. 17 is a cross-sectional view taken along line XVII-XVII in FIG. In the following description, the same reference numerals are given to components common to the above-described lock nut 1A, and detailed description thereof is omitted.

  As shown in FIGS. 16 and 17, in the lock nut 1 </ b> D according to the fourth embodiment of the present invention, the joint portion that joins and integrates the main nut member 2 and the auxiliary nut member 3 is the main nut member 2 and the auxiliary nut. The heat shrinkable tube 9 integrally covers the nut member 3. The heat-shrinkable tube 9 is a tube formed of a plastic such as a polyolefin, a fluorine-based polymer, or a thermoplastic elastomer that shrinks when heated.

  The lock nut 1D is integrally covered with the heat shrinkable tube 9 and heated while both the main nut member 2 and the auxiliary nut member 3 in which the lock pin 5 is inserted into the lock pin insertion portion 6 are fitted to the male screw. As a result, the heat shrinkable tube 9 is shrunk and integrated.

  In the lock nut 1D having this configuration, similarly to the lock nut 1A, the lock nut 1C is fitted into the male screw B2 communicated with the member to be fastened B1 and screwed, and the bottom surface 2B of the lock nut 1C is in close contact with the fastened surface C1. When the nut is tightened, the auxiliary nut member 3 is deformed so as to warp upward, so that the backlash of the screw is eliminated, a force for stretching the main nut member 2 and the auxiliary nut member 3 is generated, and the lock nut 1C is prevented from loosening. Demonstrate the function.

  Similar to the joint portion 4, the heat-shrinkable tube 9 has a lower tensile strength than the main nut member 2 and the auxiliary nut member 3, and the main nut member 2 and the auxiliary nut member when the lock nut 1A is tightened to the male screw. 3 may not be separated, and may be separated after the lock pin 5 comes into contact with the surface to be fastened.

  The lock nut of the present invention is useful as a nut that is fastened to a male screw with good workability and exhibits a locking function.

1A, 1B, 1C, 1D Lock nut 2 Main nut member 2A, 3A Top surface 2B, 3B Bottom surface 3 Auxiliary nut member 4 Joint portion 5, 7 Lock pin 6 Lock pin insertion portion 8 Through hole 9 Heat shrinkable tube

Claims (7)

A main nut member whose bottom surface is pressed against the tightened surface by being fastened to the male screw;
An auxiliary nut member provided on the top surface side opposite to the bottom surface of the main nut member, and fastened to the male screw together with the main nut member;
A joint that joins and integrates the main nut member and the auxiliary nut member, and a joint having lower tensile strength than the main nut member and the auxiliary nut member;
A lock pin insertion portion penetrating from the bottom surface of the main nut member to the top surface;
A lock pin that is inserted into the lock pin insertion portion, contacts the fastened surface before the main nut member when fastened to the male screw, and is pressed against the fastened surface by the auxiliary nut member A lock nut including a lock pin that presses upward. The lock pin insertion portion is a concave groove having an opening portion opened toward the side of the main nut member, and further having a drop prevention portion for preventing the lock pin from dropping from the opening portion. The lock nut according to claim 1. The lock nut according to claim 2, wherein the lock pin forms a part of a side surface of the main nut member in a state of being fitted into the concave groove.   The lock nut according to any one of claims 1 to 3, wherein the joint portion and the lock pin insertion portion are provided at diagonal positions of the main nut member.   The lock nut according to any one of claims 1 to 4, wherein the joint portion is formed of an adhesive.   The lock nut according to any one of claims 1 to 4, wherein the joint portion is obtained by melting and integrating the main nut member and the auxiliary nut member.   The lock nut according to any one of claims 1 to 3, wherein the joint portion is formed by a heat-shrinkable tube that integrally covers the main nut member and the auxiliary nut member.