JPH09317746A - Locking structure for screw - Google Patents

Abstract

PROBLEM TO BE SOLVED: To hold the fastening force for a fastened item with a fastening force less than a proper fastening force without requiring any complete fastening of a bolt and further prevent a looseness at a threaded part caused by aging from being produced. SOLUTION: This structure is comprised of a bolt main body 10 having a head part 10a and a threaded part 10b; a flange 11 fixed to the head part 10a of the bolt main body 10 and placed between the head part 10a and a fastened item 30; a plurality of projected semi-spherical protrusions 20 arranged at a contacted surface of the flange 11 in respect to the fastened item 30 and along a circumferential line around a rotating axis of the bolt main body 10; and a semi-spherical concave part 31 to which a plurality of protrusions 20 arranged on the fastened item 30 are engaged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screw locking structure, and more particularly to a screw locking structure capable of tightening and holding an object to be fastened with a tightening force smaller than an appropriate tightening force of a bolt. .

[0002]

2. Description of the Related Art A bolt used to fasten an object to be fastened has a screw loosening prevention structure in order to prevent loosening of a threaded portion and maintain a fastening force of the object to be fastened.
As a conventional screw loosening prevention structure, for example,
There is a "bolt with locking mechanism" described in Japanese Patent No. 004912. FIG. 6 is a sectional view of the conventional bolt with a locking mechanism, FIG. 7 is a plan view of the same, and FIG. 8 is a sectional view showing a fastening state of an object to be fastened with the bolt with a locking mechanism.

As shown in these figures, the actual Kaihei 1-00
The bolt with a locking mechanism of No. 4912 is the one to be fastened.
A bolt for fastening a and 5b, which is a bolt head 1
Further, the flange-shaped washer 2 is integrally formed. In this flange-shaped washer 2, the surface 2a on the threaded portion 4 side is formed as a concave tapered surface having a small inclination angle (inclination angle θ in FIG. 6) with respect to the direction perpendicular to the bolt axis. An annular groove 3 is formed at the base of the head 1 of the flange-shaped washer 2.

According to the bolt with the locking mechanism having the above-mentioned structure, when the bolt is integrally screwed to the objects to be fastened 5a, 5b and tightened, the flange-shaped washer 2 is the upper surface of the object to be fastened 5a. When the bolt is tightened with an appropriate tightening force, the flange-shaped washer 2 elastically deforms from the concave groove 3 portion (direction of arrow a in FIG. 8) and presses the object to be fastened 5a with a certain elasticity. It will be. By the pressing of the flange-shaped washer 2, the bolt is always biased toward the object 5 to be fastened, loosening of the bolt after tightening is prevented, and the fastening force of the objects 5a and 5b to be fastened is maintained. .

[0005]

As described above, in the conventional screw locking structure, the bolt is tightened to the proper tightening force to prevent the screw from being loosened by the urging force of the flanged washer in a completely tightened state. However, when loosening due to secular change occurs in the threaded portion of the bolt including the object to be fastened, prevention of this has not been considered. For this reason, in the conventional screw loosening prevention structure, when the fastening screw portion loosens due to aging and is no longer completely fastened, the urging force of the flange washer no longer works, and as a result, the fastened object is fastened. It was impossible to maintain the fastening force.

In the conventional screw loosening prevention structure, loosening of the screw portion is prevented only when the bolts are completely fastened. Therefore, for example, the object to be fastened is made of a plastic material or the like under a certain fastening force. There is also a problem that it is not possible to prevent such loosening of the object to be fastened when it is difficult to completely fasten it because the creep phenomenon due to secular change is remarkable.

The present invention has been proposed in order to solve the problems of the prior art as described above, and it is not necessary to completely tighten the bolts, and the tightening force less than the proper tightening force can be applied. An object of the present invention is to provide a screw loosening prevention structure capable of retaining the fastening force of a fastening object and effectively preventing loosening of a screw portion due to aging.

[0008]

In order to achieve the above object, a screw locking structure according to claim 1 of the present invention has a head portion on one side and a screw portion to be fastened to an object to be fastened on the other side. A bolt main body having a portion, a flange fixed to the head of the bolt main body, interposed between the head and the object to be fastened, and a projection protruding on the contact surface side of the flange with the object to be fastened. A concave portion with which the protrusion provided on the object to be fastened is engaged.

According to a second aspect of the present invention, in the screw loosening prevention structure, the protrusion is formed in a hemispherical shape.

According to a third aspect of the present invention, in the screw loosening prevention structure, the concave portion has a hemispherical shape.

According to a fourth aspect of the present invention, there is provided a screw locking structure, wherein a plurality of the protrusions are provided so as to project along a circumferential line centering on a rotation axis of the bolt body of the flange, and the recess is provided. The same number of protrusions as the protrusions are formed at positions corresponding to the protrusions.

Further, in a screw loosening prevention structure according to a fifth aspect of the present invention, a plurality of the projections are provided so as to project along a circumferential line around the rotation axis of the bolt body of the flange, and the recesses are provided. A plurality of protrusions are formed at positions corresponding to the plurality of protrusions.

According to the locking structure of the present invention having such a structure, the spherical protrusion projecting on the flange washer integrally formed on the head of the bolt main body has the bolt center shaft on the object side. It can be engaged with the recess formed on the circumference of the.

Thus, even if the bolt is not tightened with a proper tightening force, the engagement of the object to be fastened can be held by the engagement of the projection and the recess and the loosening of the screw due to stress relaxation can be prevented. Also, the object to be fastened can be held with a weak fastening force. Therefore, it becomes possible to effectively prevent the screw from loosening and maintain the fastening force even with respect to a member such as a plastic material having a remarkable creep phenomenon.

Further, since the engagement between the projection and the recess also functions as a stopper for preventing the loosening of the threaded portion, the threaded portion after fastening becomes difficult to rotate, which causes loosening of the threaded portion due to aging. Can be effectively prevented.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a screw locking structure of the present invention will be described below with reference to the drawings. FIG. 1 shows a screw locking structure according to the present embodiment.
(A) is a side view of the bolt body, (b) is a bottom view of the same,
Further, (c) is a plan view of an object to be fastened. Also, in FIG.
The fastening state of the to-be-fastened object by the screw loosening prevention structure which concerns on this embodiment is shown, (a) is a state before tightening of a bolt,
(B) is a partial cross-sectional front view showing a state after tightening.

In these drawings, reference numeral 10 denotes a bolt body having a head portion 10a on one side and a screw portion 10 screwed to an object to be fastened 30 (30a, 30b) on the other side.
b. Reference numeral 11 denotes a flange, which is fixed to the head portion 10a of the bolt body 10 and is connected to the head portion 10a and the fastening object 30 (3.
0a). In this embodiment, the flange 11 has an outer diameter equal to the outer diameter of the standard washer +
It is about 5 mm and is formed integrally with the bolt body 10.

Further, the flange 11 has an object to be fastened 30a.
A plurality of spherical projections 20 are provided on the contact surface side with. As shown in FIG. 1 (b), the plurality of protrusions are provided at four locations along the circumference of the contact surface of the flange 11 with the object to be fastened 20 a, which is centered on the rotation axis of the bolt body 10. It is formed at intervals.

The projection 20 is preferably formed integrally with the flange 11 by using the same material as the flange 11. Further, it is preferable that the projection 20 has a hemispherical shape as shown in the present embodiment from the viewpoint of smoothly engaging and disengaging the recess 31 of the article to be fastened 30, which will be described later.
In addition to this, a spherical shape, an elliptical spherical shape, or the like may be used.

On the other hand, the fastened body 30 that contacts the flange 11
On the a side, the same number of recesses 31 as the protrusions 20 are formed at positions corresponding to the plurality of protrusions 20 around the screw hole that penetrates the bolt body 10. The shape of the recess 31 is a hemispherical recess so that the projection 20 of the flange 11 can be smoothly engaged and disengaged. In addition, this recess 31
The inner diameter and the outer diameter of the protrusions 20 are preferably about 4: 5.

The recess 31 is the projection 2 of the flange 11.
From the viewpoint of smoothly engaging with and disengaging from 0, it is preferable to have a hemispherical shape corresponding to the shape of the protrusion 20, but other than this, it is also possible to use a cylindrical recess or the like having a circular cross section. . Further, the thickness of the object to be fastened 30a forming the recess 31 needs to be at least the radius of the protrusion 20 or more and the depth of the recess 31 or more.

Next, the case where the objects to be fastened 30a and 30b are fastened by the screw loosening preventive structure of the present embodiment having such a configuration will be described. As shown in FIG. 2, in the present embodiment, two objects to be fastened 30a to be fastened,
Among the 30b, a through hole 32 for bolt penetration and a concave portion 31 are formed in the upper fastening object 30a, and the lower fastening object 30a is formed.
A tap with which the threaded portion 30b of the bolt main body 10 is screwed is cut in b, and a washer 40 is interposed between the objects to be fastened 30a, 30b.

First, the aligned objects 30a, 3 are aligned.
0b, insert the bolt body 10 from the threaded portion 10b side,
Tighten. FIG. 3 shows the relationship between the screw rotation speed and the tightening force when tightening the bolt. In the figure, if the proper tightening force (depending on the size and material) of the threaded portion 10b of the bolt body 10 is F1 to F2 and the corresponding screw rotation speeds are n1 to n2, the protrusion 20 is at the position P0. It engages with the concave portion 31, and the tightening force at that time becomes F0, and a gap is created with the tightening force in the vicinity thereof.

At this time, F0 <F1 and F
Even though the tightening force of 0 is less than the proper tightening force, this P
In order to rotate the bolt body 10 from the point O, it is necessary to exceed the tightening force gap (falling amount of the tightening force). As a result, the bolt body 10 becomes difficult to rotate and the screw is difficult to loosen when the projection 20 and the recess 31 are engaged with each other.

That is, as the bolt body 10 is tightened, the tightening force acting on the bolt body 10 is P0, P, as shown in FIG.
The tightening force once loosens at each point of a and Pb, and the rotational torque required for further rotation from that point increases in both the tightening direction and the tightening direction, so that the tightening force of the bolt body 10 is maintained. It In addition, in the straight line portion in FIG. 3 other than the points P0, Pa, and Pb, which are the depression points, the projection 20 and the fastening object 30a are in point contact with each other, and the bolt body 10 is in an unstable state in which it is easy to rotate. Therefore, it is not suitable for retaining the tightening force.

Therefore, for example, the threaded portion 10b of the bolt body 10 is a thread of the thread standard M5, and the flange 11 of φ15 is used.
When the projections 20 having a diameter of φ2 are further provided so as to be integrated with each other, and the recess 31 on the side of the object to be fastened 30a has a diameter of 1.6, the recess 3
The amount of lowering of the bolt main body 10 when the protrusion 20 is engaged with 1 is about one pitch. That is, in terms of the number of rotations of the bolt body 10, it becomes equal to the tightening force when one rotation is less,
In that state, the tightening force can be maintained.

As described above, according to the screw loosening prevention structure of the present embodiment, the spherical protrusion projecting on the flange washer integrally formed on the head of the bolt body is the center of the bolt on the object to be fastened. It can be engaged with a recess formed on the circumference of the shaft. As a result, even if the bolt is not tightened with the proper tightening force, the engagement of the object to be fastened can be held by the engagement of the projection and the recess, and the loosening of the screw due to stress relaxation can be prevented, and the tightening force is weaker than the proper tightening force. The object to be fastened can be held by force.

Therefore, it becomes possible to effectively prevent the loosening of the screw and maintain the fastening force even with respect to a member such as a plastic material having a remarkable creep phenomenon. Further, since the engagement between the projection and the recess also functions as a stopper for preventing the screw part from loosening, the screw part after fastening becomes difficult to rotate, which effectively causes the screw part to loosen due to aging. Can be prevented.

As a modification of the present embodiment, FIG.
Alternatively, a loose screw structure as shown in FIG. 5 may be used. That is, as shown in FIG. 4, a plurality of protrusions 20 are provided on the circumference of rotation of the flange, and recesses 31 are formed at positions corresponding to the plurality of protrusions 20 so as to be multiplied with respect to the protrusions 20. . As a result, the tightening force gap can be created in finer steps, and the tightening force of the bolt can be adjusted more finely.

Further, as shown in FIG. 5, the number of the projections 20 and the number of the recesses 31 may be the same, and the numbers of both may be further increased. As a result, as in the case of FIG. 4 described above, the number of engagements between the protrusion 20 and the recess 31 increases as well as the fine adjustment, so that the bolt body 10 is caught by the rotation, that is, the rotation resistance can be increased, and the external force can be increased. The holding force of the bolt main body 10 against the like can be further increased.

[0031]

As described above, according to the screw locking structure of the present invention, the tightening force of the object to be fastened can be applied at a tightening force equal to or less than the proper tightening force without requiring the complete tightening of the bolts. It can be held, and it is possible to effectively prevent loosening of the screw portion due to secular change.

[Brief description of drawings]

1 shows an embodiment of a screw locking structure of the present invention, (a) is a side view of a bolt body, (b) is a bottom view of the same, and (c) is a plan view of an object to be fastened. .

2A and 2B show a fastening state of an object to be fastened according to an embodiment of a screw loosening prevention structure of the invention, FIG. 2A shows a state before tightening a bolt, and FIG. 2B shows a state after tightening, respectively. It is a partial cross section front view.

FIG. 3 is a graph showing the relationship between the screw tightening force and the rotation speed of the bolt body in the screw locking structure of the present invention.

FIG. 4 shows another embodiment of the screw locking structure of the present invention, (a) is a side view of the bolt body, (b) is a bottom view of the same, and (c) is a plan view of the object to be fastened. is there.

5A and 5B show another embodiment of the screw locking structure of the present invention, where FIG. 5A is a side view of a bolt body, FIG. 5B is a bottom view of the same, and FIG. 5C is a plan view of an object to be fastened. is there.

FIG. 6 is a front sectional view showing a conventional screw locking structure.

FIG. 7 is a plan view showing a conventional screw locking structure.

FIG. 8 is a cross-sectional front view of essential parts showing a state after tightening a bolt with a conventional screw locking structure.

[Explanation of symbols]

 10 ... Bolt body 10a ... Head part 10b ... Screw part 11 ... Flange 20 ... Projection 30 ... Fastened object 31 ... Recessed part

Claims (5)

[Claims] 1. A bolt main body having a head portion on one side and a threaded portion screwed to an object to be fastened on the other side; and a head portion of the bolt main body fixed to the head portion and the object to be fastened. A flange interposed between the flange, a protrusion projecting on the contact surface side of the flange with the object to be fastened, and a recess engaged with the protrusion provided on the object to be fastened. Locking structure for screws. 2. The screw loosening preventive structure according to claim 1, wherein the protrusion has a hemispherical shape. 3. The screw locking structure according to claim 1, wherein the recess has a hemispherical shape. 4. A plurality of the protrusions are provided so as to protrude along a circumferential line about the rotation axis of the bolt body of the flange, and the recesses are provided at positions corresponding to the plurality of protrusions. The screw loosening prevention structure according to claim 1, wherein the same number is formed. 5. A plurality of the protrusions are provided so as to protrude along a circumferential line around the rotation axis of the bolt main body of the flange, and the recesses are formed at positions corresponding to the plurality of protrusions from the protrusions. The screw loosening prevention structure according to claim 1, 2 or 3, wherein a large number is formed.