JP2000240632A - Lock nut - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lock nut unremovable after once fastening a bolt and nut. SOLUTION: A ring receiving part 31 is formed on the outside of a lock nut main body 30, a rotational operating part 32 is formed on the rear end of the lock nut main body, a notch 33 is formed therebetween, and a loose ring 34 is rotatably externally fitted to the ring receiving part 31 substantially covering the ring receiving part 31. After fastening of the lock nut is completed by operating the rotational operating part, the notch is broken to keep the lock nut main body unremovable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lock nut, and more particularly to a lock nut in which a bolt and a nut cannot be released once the bolt and nut have been fastened.

[0002]

2. Description of the Related Art When two or more workpieces are fastened,
Bolts and nuts are often used. Normally, in such a bolt / nut, a bolt shaft portion is inserted into an insertion hole of a member to be fastened, a female screw of the nut is screwed into a male screw of the bolt, and a plurality of members to be tightened are tightened between the bolt head and the nut. The method of fastening is common.

[0003] By the way, in this type of bolt / nut, there is a possibility that the fastening may be loosened due to vibration, thermal expansion, aging, etc., and therefore various methods for preventing loosening have been proposed. For example, a method using a bending washer or a lock wire,
A method of passing a split pin through a nut and a bolt, a method using a double nut (JP-A-6-26512, etc.), a method using a bolt having a self-locking screw (JP-A-7-42724, etc.), A method is known in which a locking claw is provided, a receiving portion with which the locking claw can engage is formed on the bolt screw portion side, and only rotation in the tightening direction of the nut is allowed (Japanese Patent Laid-Open No. 6-249222). I have.

[0004]

However, the conventional methods for preventing loosening are based on the premise that bolts and nuts are reused, and simply prevent loosening of the fastening.
If the bolt or the nut is intentionally turned by an excessive force, the bolt or the nut turns in a loosening direction, and there is a problem that the fastening of the member to be fastened can be released.

In order to prevent this, it is necessary to fix the bolt screw portion and the nut by welding or the like, but the operation is very complicated.

On the other hand, in the conventional locking method, the nut cannot be loosened unless the locking claw is disengaged.
It is very complicated to assemble the engagement claws with the nut, resulting in high cost.

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to prevent the manufacturing process from becoming complicated and to prevent the bolts and nuts from being released once they are fastened.

[0008]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above-mentioned problems, and as a result, the lock nut is constituted by a portion that can be rotated from the outside and a portion that cannot be rotated,
The present invention has been completed by focusing on the fact that it is sufficient to tighten the lock nut at the portion where the rotation operation can be performed, and to break the portion where the rotation operation can be performed when the tightening is completed so that the lock nut cannot be operated in the removing direction.

That is, the lock nut according to the present invention is used for a bolt-nut type fastener in which at least two members to be fastened are tightened between a bolt head and a nut, and locking of the fastening is prevented. In the lock nut for performing the above, a female screw which can be screwed with a bolt screw portion is engraved on the inner peripheral surface of the lock nut main body, and a ring receiving portion is provided on the outer surface of the lock nut main body with a large size in the longitudinal direction of the lock nut main body. A rotation operation part formed over a portion and being rotatable by a jig is formed at a rear end of the lock nut body,
A notch that breaks with a torsional load equal to or greater than a predetermined value is formed between the rotary operation part and the lock nut body continuously or discontinuously in a ring, while the idle ring is formed in the ring receiving part. The lock nut main body is behind the nut of the bolt screw portion by the operation of the rotation operation portion, and the lock nut main body moves the rotation operation portion to the free end side of the bolt screw portion by substantially covering the ring receiving portion. And screwed in,
When the lock nut body and the nut compete with each other, when the torsional load on the rotation operation part reaches a predetermined value or more, the rotation operation part is broken from the lock nut body by the notch and the lock nut body is removed. The operation is disabled.

One of the features of the present invention is that when the tightening of the lock nut body is completed, the rotation operating portion is broken so that the lock nut body cannot be removed.
As a result, even if the bolts and nuts are intentionally loosened with excessive force, the idle ring does not rotate and the lock nut body cannot be loosened, and the nut is locked by the lock nut body, and the bolt, nut or lock nut body is loosened. Is not broken unless it is broken.

The rotary operating portion is preferably formed in a hexagonal shape like a normal lock nut, but may be formed in another shape, for example, a saw-like knurl formed on a rod portion as long as it can be rotated by a jig. Since the ring receiving portion needs to have a shape that allows the idling ring to idle, the outer shape is made cylindrical.

The notch needs to be broken when the lock nut body and the nut compete with each other and the torsional load on the rotary operation portion reaches a predetermined value or more.
Therefore, the size and shape of the notch are set based on the fastening force of the lock nut.

[0013]

According to the present invention, when the tightening of the lock nut main body is completed, the rotation operating portion is broken from the notch so that the lock nut main body cannot be removed, so that an excessive force is intentionally applied. Even if you try to loosen the bolts and nuts, the idle ring cannot rotate and the lock nut body cannot be loosened, the nut is locked by the lock nut body, and it will not be released unless the bolt, nut or lock nut body is broken. Absent.

Also, a ring receiving portion is provided on the lock nut body,
Although the rotating operation part and the notch are formed, the ring receiving part and the rotating operation part can be formed by forging, and the notch can be formed by cutting, so that the lock nut body can be manufactured relatively easily, and the idle ring can be formed. Since it is merely fitted into the ring receiving portion, the manufacturing is not complicated as a whole, and the cost is not increased.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to specific examples shown in the accompanying drawings. 1 to 3 show a preferred embodiment of a lock nut according to the present invention. In FIG. 3, the lock nut main body 30 has an internal thread formed on the inner peripheral surface thereof, and a ring receiving portion 31 is formed on the outer peripheral surface of the lock nut 30 by forging over substantially the entire length.

A rotary operation part 32 is integrally formed at the rear end of the lock nut body 30 by forging. The rotary operation part 32 has a hexagonal outer shape, and the inside has a larger diameter than the bolt screw part 13. It has a cylindrical shape.

The lock nut main body 30 and the rotation operation section 3
A notch 33 is continuously formed in a ring shape by cutting between the two, and breaks when the torsional load on the rotary operation portion 32 reaches a predetermined value.

An annular idle ring 34 is rotatably mounted on the ring receiving portion 31. The idle ring 34 has a length L with respect to the length L + 1 of the ring receiving portion 31, that is, a ring L. The length is set to cover most of the receiving portion 31.

When a plurality of members W1 and W2 are to be fastened, the male screw 13 of the bolt 10 is inserted into the insertion hole of the members W1 and W2 via the washer 40, and the male screw 1
3 is provided with a female thread 21 of the nut 20 via a washer 40.
And the two fastened members W1 and W2 are fastened between the head 12 of the bolt 10 and the nut 20. The washer 40 may not be used in some cases.

Thereafter, the lock nut main body 30 is aligned with the free end of the male screw portion 13 of the bolt 10 and the rotation operation portion 3
2, the lock nut main body 30 is screwed to compete with the nut 20, and then the rotation operation portion 32 is further operated until a predetermined tightening force is obtained. As shown in FIG. While the nut 20 is locked, a torsional load of a predetermined value or more acts on the rotation operation unit 32,
The rotation operation part 32 can be removed by breaking from the notch 33 in FIG.

Then, even if the lock nut body 30 is to be loosened, there is no place where only the idling ring 34 can be operated from outside, and the idling ring 34 cannot rotate and the lock nut body 30 cannot be loosened.
Is locked by the lock nut body 30, and the bolt 1
Unless the nut 0, the nut 20, or the lock nut body 30 is broken, the fastening cannot be removed, and the reliability of the fastening can be greatly improved.

Further, the lock nut of this embodiment can be used as a fastener for the existing bolt 10 and nut 20. Therefore, the reliability of the fastening can be greatly improved only by replacing the lock nut with the existing lock nut. Is very large.

Further, the ring receiving portion 31 and the rotation operating portion 32 of the lock nut main body 30 are forged by the notch 3
Since the lock nut 3 is formed by cutting, the lock nut body 30 can be manufactured relatively easily, and since the idling ring is merely fitted into the ring receiving portion, the manufacturing is not complicated as a whole and the cost is low. Can be manufactured.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a bolt and nut type fastener using a lock nut according to a preferred embodiment of the present invention.

FIG. 2 is a view showing a state in which a rotation operation unit 32 in FIG. 1 is broken.

FIG. 3 is a perspective view showing the lock nut.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Bolt 12 Head 13 Male thread part 20 Nut 21 Female thread part 30 Lock nut main body 31 Ring receiving part 32 Rotating operation part 33 Notch 34 Idling ring W1, W2 Fastened member

Claims (2)

[Claims] 1. A lock nut for use in a bolt-and-nut type fastener for fastening at least two members to be fastened between a bolt head and a nut, wherein the lock nut prevents locking. A female screw which can be screwed with a bolt screw portion is engraved on an inner peripheral surface of the main body, and a ring receiving portion is formed on an outer peripheral surface of the lock nut main body over most of a longitudinal direction of the lock nut main body. A rotary operation part that can be rotated by a jig is formed at the rear end of the main body, and a notch that breaks with a torsional load of a predetermined value or more between the rotary operation part and the lock nut main body is annularly continuous. On the other hand, the idle ring is rotatably mounted on the ring receiving portion so as to substantially cover the ring receiving portion, and the bolt is operated by the rotation operation portion. The lock nut body is screwed behind the nut of the screw portion with the rotation operation portion being the free end side of the bolt screw portion, and the lock nut body and the nut compete with each other to twist the rotation operation portion. A lock nut, wherein when the load reaches a predetermined value or more, the rotation operating portion is broken by the notch from the lock nut main body so that the lock nut main body cannot be removed. 2. The lock nut according to claim 1, wherein the rotation operation portion has a shape of a hexagon nut.