JP2003301829A - Bolt-nut locking structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bolt-nut locking structure in which a nut can be prevented from loosening without elongating a bolt shaft length, in which manufacturing easiness and cost reduction can be achieved, and in which loosening can be securely achieved using an existing bolt. <P>SOLUTION: A lock nut 13 is engaged with an inverse thread 122 in a long nut 12, and the long nut is engaged with a shaft of a bolt 11. The bolt and the nut are strongly fastened to each other. As vibration or the like is added to this fastening structure to start the loosening of the nut, the lock nut is tightened. The loosening of the nut to the bolt is thus prevented. Even by a bolt 53 that is directly driven into a device body 51, loosening can be securely prevented by a lock nut 58 engaged with an inverse thread 57 in it. When an external force is added in a bolt loosening direction, the external force acts in a lock nut tightening direction. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bolt / nut loosening prevention structure for preventing loosening of bolts / nuts due to vibration, repeated load, impact, etc., and a bolt / nut used therefor.

[0002]

2. Description of the Related Art As a conventional bolt / nut loosening prevention structure, when a right screw with which a tightening nut is screwed is screwed on a shaft of a bolt, a reverse screw (left screw) is formed at the tip of the shaft. Generally, a structure in which a lock nut is screwed onto the left screw is common. For example, JP-A 2000-199509, JP-A 11-303840, and JP-A 1-73.
Such a structure is disclosed in Japanese Patent Publication No. 118 and the like.

[0003]

However, this loosening prevention structure has the following drawbacks. That is, a tip portion for screwing the lock nut is required, and the axial length of the bolt itself is long. In addition, two stages of screws with different diameters are formed on the shaft of the bolt, and these screws are formed by reverse screws, which makes the bolt itself cumbersome to manufacture.
The cost was high.

[0004]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to prevent the nut from loosening without increasing the bolt shaft length. Further, it is an object of the present invention to provide a locking structure which is easy to manufacture and leads to cost reduction.
Further, according to the present invention, it is an object of the present invention to provide a structure capable of reliably preventing loosening by replacing only a nut, that is, using an existing bolt.

[0005]

According to a first aspect of the present invention, there is provided a bolt / nut loosening prevention structure for loosening a nut screwed into a bolt, wherein the nut outer peripheral surface is provided on the bolt head side. , A reverse threaded part with a thread formed in the opposite direction to the inner peripheral thread of the nut is provided, and a lock nut is screwed into this reverse threaded part to prevent the nut from loosening from the bolt It is a stop structure. A member to be fastened may be sandwiched between the bolt and the nut. In this case, the members to be fastened may be single or plural. As bolts, implant bolts (s
tud bolt). The head shape of the bolt or nut may be polygonal or circular. Further, the material, size, shape, etc. are not questioned.

According to a second aspect of the present invention, there is provided a bolt / nut loosening prevention structure for loosening a bolt screwed into a target member, wherein an outer peripheral surface of a head of the bolt is provided on the target member side. A bolt with a reverse threaded part that has a thread formed in the opposite direction to the screw of the bolt is provided, and a lock nut is screwed into this reverse threaded part to prevent the bolt from loosening.
It has a structure that prevents the nuts from loosening. The present invention can be applied to a structure having no nut. That is, for example, even when a bolt is screwed into a screw hole formed in a target member such as a vehicle body or a machine body, the loosening can be prevented by forming a reverse screw portion on the head of the bolt.

According to a third aspect of the present invention, there is provided a bolt / nut loosening prevention structure according to the first or second aspect, wherein the pitch of the screw of the reverse screw portion is smaller than the pitch of the inner peripheral surface screw of the nut. . This is because the smaller the pitch, the more difficult it is to loosen.

According to a fourth aspect of the present invention, there is provided a nut used in the bolt / nut loosening prevention structure according to the first aspect, which has an inner peripheral surface screw into which the bolt is screwed. At the same time, on the bolt head side on the outer peripheral surface thereof, there is a reverse threaded portion in which a screw is formed in the direction opposite to the thread on the inner peripheral surface, and the lock nut is screwed into this reverse threaded portion. It is a nut used for the locking structure. The reverse threaded portion is formed at least on the bolt head side of the nut. In the case of a stud, it is the side where it is implanted.

According to a fifth aspect of the present invention, there is provided a bolt used in the structure for preventing loosening of a bolt / nut according to the second aspect, wherein the shaft portion has a shaft screw screwed into a screw hole of a target member. In addition to that, on the outer peripheral surface of the head portion thereof, on the side of the screw hole, there is a reverse screw portion in which a screw is formed in the opposite direction to the shaft screw, and the lock nut is screwed into the reverse screw portion. This is a bolt used for the nut locking structure.

[0010]

According to the invention described in claims 1, 3 and 4, first, the lock nut is screwed into the reverse threaded portion of the nut. Then, the nut is screwed into the shaft of the bolt. As a result, the nut is screwed into the bolt, and the bolt and the nut are firmly fastened. Even if vibration or the like is applied to the fastening structure, the lock nut will be tightened if the nut is loosened. as a result,
The nut is prevented from loosening with respect to the bolt. Incidentally. One surface of the lock nut is in contact with a member to be fastened, for example.

According to the second and fifth aspects of the invention, even when the bolt is directly screwed into the main body of the apparatus and the like, and the loosening is to be prevented, the locknut can surely prevent the loosening. This is because when an external force acts in the direction in which the bolt loosens, the external force acts in the tightening direction on the lock nut.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a front view showing a bolt / nut loosening prevention structure with a part thereof broken away. FIG. 2 is an exploded view of this nut loosening prevention structure. As shown in these drawings, the hexagonal bolt 11 and the long nut 12 are screwed together, and the fastened member 2 which is, for example, a metal plate member is interposed therebetween.
Clamp and fix 1 and 22. The hexagon bolt 11 has a hexagonal head portion 111 and a shaft portion 112 having a predetermined length and a screw threaded on the tip side. This screw is, for example, a coarse metric screw. The long nut 12 has a reverse threaded portion 122 in which a fine thread in the reverse direction is cut on one side (one side in the axial direction) of the outer peripheral surface of the long nut 12 in addition to the inner peripheral surface screw 121 screwed into the screw of the shaft portion 112. have. That is, the reverse screw portion 12
2 is formed with a screw having a smaller pitch than the inner peripheral surface screw 121. On the other side of the outer peripheral surface, a hexagonal spanner or the like locking portion 123 is provided. The lock nut 13 screwed to the reverse threaded portion 122 is a hexagonal nut larger than the outer shape of the long nut 12. Needless to say, the materials, dimensions, etc. of the hexagon bolts 11, long nuts 12, and lock nuts 13 can be appropriately configured. It is determined by the part to be used.

In the nut loosening prevention structure having the above structure, first, the lock nut 13 is screwed into the reverse threaded portion 122 of the long nut 12. In this case, the lock nut 13 and the long nut 12 are screwed so that their end surfaces are flush with each other. Next, the long nut 12 is screwed into the hexagon bolt 11. At this time, the bolt shaft portion 112 is inserted into the holes of the members to be fastened 21, 22 and the tip end portion thereof projects. Therefore, the members to be fastened 21 and 22 are sandwiched between the long nut 12 screwed with a predetermined torque and the head portion 111 of the bolt to be firmly coupled. At this time, the end surface of the lock nut 13 also comes into contact with the outer surface of the fastened member 22. Then, in this fastening structure, even if vibration or the like acts, when the long nut 12 tries to loosen, the lock nut 13 is tightened. Therefore, the long nut 12 is prevented from loosening. In particular, since the lock nut 13 uses fine threads, it moves faster in the axial direction with respect to external force such as vibration compared to coarse threads, and is quicker than the case where the same screws are used. The loosening prevention can be performed.

FIG. 3 shows another embodiment of the present invention. In this embodiment, the fastening member 54 is fixed to the machine body 51 by screwing the bolt 53 into the screw hole 52 formed in the machine body 51 without using a nut. The bolt 53 has a reverse screw portion 57 between the head portion 55 and the shaft portion 56. That is, the reverse screw portion 57 is formed on the shaft portion 56 side of the head portion 55, the diameter thereof is substantially the same as that of the head portion 55, and a screw in the direction opposite to the screw of the shaft portion 56 is formed on the outer surface. The pitch of the screws in the opposite direction is smaller than that of the shaft screws. And this reverse screw part 57
A lock nut 58 is screwed into this. Lock nut 5
8 contacts the outer surface of the member 54 to be fastened. As a result, the bolt 53 is locked by the lock nut 58. The rest of the construction is the same as that of the above-mentioned embodiment, so it is omitted.

Further, for example, a stud bolt may be used instead of the hexagon bolt. The number of members to be fastened is not limited to a plurality, and it goes without saying that a single member may be used. Further, even if the contact surface of the lock nut with the member to be fastened is roughened to increase the frictional force, it is effective to prevent loosening.

[0016]

According to the present invention, it is possible to securely prevent the bolts and nuts from loosening. Further, in that case, it is not necessary to lengthen the bolt shaft length. That is, the existing bolt can be used as it is. Further, the manufacturing thereof can be easily performed, and as a result, the locking structure can be provided at low cost.

[Brief description of drawings]

FIG. 1 is a front view of a bolt / nut loosening preventive structure according to an embodiment of the present invention with a part broken away.

FIG. 2 is an exploded view of a bolt / nut locking structure according to an embodiment of the present invention.

FIG. 3 is a sectional view showing a bolt / nut loosening prevention structure according to another embodiment of the present invention.

[Explanation of symbols]

11 Hexagon bolts, 12 long nuts, 13 lock nuts, 51 Machine body (target member), 53 volts, 55 volt head, 56 bolt shank, 57 bolt reverse thread, 58 lock nuts, 111 bolt head, 121 Inner surface screw, 122 Reverse screw part.

Claims (5)

[Claims] 1. A bolt-nut loosening prevention structure for loosening a nut screwed into a bolt, wherein the nut outer peripheral surface is on the bolt head side in a direction opposite to the inner peripheral thread of the nut. A bolt / nut loosening prevention structure in which a reverse threaded portion with a thread is provided, and a lock nut is screwed into this reverse threaded portion to prevent the nut from loosening from the bolt. 2. A bolt / nut loosening prevention structure for preventing a bolt screwed into a target member from loosening, wherein the bolt head has an outer peripheral surface on the target member side in the direction opposite to the screw of the bolt. A bolt / nut loosening prevention structure in which a reverse threaded portion with a screw formed on the is provided, and a lock nut is screwed into this reverse threaded portion to prevent the bolt from loosening. 3. The bolt / nut loosening prevention structure according to claim 1, wherein the thread of the reverse threaded portion has a smaller pitch than the thread on the inner peripheral surface of the nut. 4. A nut used in the loosening prevention structure for a bolt / nut according to claim 1, wherein the nut has an inner peripheral surface screw into which the bolt is screwed, and the outer peripheral surface thereof The bolt head side has a reverse threaded portion in which a screw is formed in the opposite direction to the inner peripheral surface screw, and the lock nut is screwed into this reverse threaded portion. nut. 5. A bolt used in the structure for preventing loosening of a bolt / nut according to claim 2, wherein the shaft portion has a shaft screw screwed into a screw hole of a target member, and On the outer peripheral surface, on the side of the screw hole, there is a reverse screw part in which a screw is formed in the opposite direction to the shaft screw, and the lock nut is screwed into this reverse screw part. Bolts that will be.