Patent Application
20220316519
The present disclosure relates to a security nut and a security bolt.
Conventional nuts and bolts have been developed to make it difficult for others to loosen them once they have been tightened. For example, JP 5113956 B describes a nut and a bolt which have a head engageable only with a dedicated tool, and thus can be tightened only with the dedicated tool. Such a nut and a bolt are useful, for example, to prevent others from disassembling machinery or equipment which has been assembled using the nut and the bolt. In particular, such a nut and a bolt are useful for preventing theft of machinery or equipment assembled by means of the nut and the bolt, and for hiding an internal structure of the machinery or equipment from others.
The nut and the bolt described in Patent Document 1 (JP 5113956 B) lack versatility because they require a dedicated tool suitable for them when they are tightened. In addition, preparation of the dedicated tool may increase the cost.
The present disclosure has been made in view of the above circumstances. The object of the present disclosure is to provide a nut and a bolt that make it difficult to be loosened once they have been tightened.
A security nut according to the present disclosure comprises:
a nut body having an inside screw; and
a plurality of torque transmission projections provided on an outer surface of the nut body along a circumferential direction;
wherein:
each torque transmission projection has a torque transmission surface provided on an upstream side in a tightening direction of the security nut, and a release surface provided on a downstream side in the tightening direction of the security nut; and
a ridge line is formed between the release surface and the torque transmission surface, the ridge line inclining toward the upstream side of the tightening direction along the circumferential direction, from an advancing-direction end of the nut body to a retracting-direction end of the nut body.
In the security nut according to the present disclosure, a flange may be provided on the advancing-direction end of the nut body.
In the security nut according to the present disclosure, an annular protrusion may be provided on the retracting-direction end of the nut body.
In the security nut according to the present disclosure,
L1, L2 and L3 may satisfy below relationships:
0.5×L3≤L2≤L3 Expression (1)
0.2×L1≤L2≤0.4×L1 Expression (2)
A security bolt according to the present disclosure comprises:
a shaft part having an outside screw; and
a bolt head part provided on the shaft part, the bolt head part having a bolt head part body, and a plurality of torque transmission projections provided on an outer surface of the bolt head part body along a circumferential direction;
wherein:
each torque transmission projection has a torque transmission surface provided on an upstream side in a tightening direction of the security bolt, and a release surface provided on a downstream side in the tightening direction of the security bolt;
and
a ridge line is formed between the release surface and the torque transmission surface, the ridge line inclining toward the upstream side of the tightening direction along the circumferential direction, from an advancing-direction end of the bolt head part body to a retracting-direction end of the bolt head part body.
In the security bolt according to the present disclosure, the bolt head part body may have a flange provided on the advancing-direction end of the bolt head part body.
In the security bolt according to the present disclosure, the bolt head part body may have a truncated conical protrusion provided on the retracting-direction end of the bolt head part body.
In the security bolt according to the present disclosure,
L4, L5 and L6 may satisfy below relationships:
0.5×L6≤L5≤L6 Expression (3)
0.2×L4≤L5≤0.4×L4 Expression (4)
where L4 represents a circumferential pitch between the torque transmission projections, L5 represents a circumferential length of the torque transmission surface of each torque transmission projection, and L6 represents a circumferential length of the release surface of each torque transmission projection.
The present disclosure can provide a nut and a bolt that make it difficult to be loosened once they have been tightened.
A nut of a first embodiment of the present disclosure is described first with reference to
The security nut 1 is rotated about an axis LA, when tightened on a bolt. In the first embodiment, a direction of the axis LA is referred to as an axial direction DA, and a direction surrounding the axis LA is referred to as a circumferential direction DB. A direction of the axial direction DA along which the security nut 1 moves when it is tightened is referred to as an advancing direction, and a direction thereof along which the security nut 1 moves when it is loosened is referred to as a retracting direction. Further, an advancing-direction end of the nut body 11 of the security nut 1 is the advancing-direction end 91, and a retracting-direction end thereof is the retracting-direction end 92. A radial direction of the security nut 1 is referred to as a radial direction DC.
A direction of the circumferential direction DB along which the security nut 1 is tightened is referred to as a tightening direction SB1, and a direction thereof along which the security nut 1 is loosened is referred to as a loosening direction SB2.
Next, respective constituent elements of the security nut 1 are further described.
First, the nut body 11 is described. As described above, the nut body 11 is a part of the security nut 1, which has the inside screw 11a. In the example shown in
By inserting the bolt 71 into the through hole 11b from the advancing-direction end 91 of the nut body 11 and by rotating the security nut 1 in the tightening direction SB1, the inside screw 11a can be meshed with an outer screw of the bolt. Thus, the security nut 1 can be tightened on the bolt.
Next, the torque transmission projections 3 are described. The torque transmission projections 3 are provided on the outer surface of the nut body 11 along the circumferential direction DB.
Each torque transmission projection 3 has a torque transmission surface 31 provided on an upstream side in the tightening direction SB1 of the security nut 1, and a release surface 32 provided on a downstream side in the tightening direction SB1 of the security nut 1.
In addition, a ridge line 33 is formed between the torque transmission surface 31 and the release surface 32. The ridge line 33 inclines toward the upstream side of the tightening direction SB1 along the circumferential direction DB, from the advancing-direction end 91 of the nut body 11 to the retracting-direction end 91 of the nut body 11 (see
When the security nut 1 is rotated in the tightening direction SB1 by means of a general tool for rotating a nut, such as a general wrench, the torque transmission surface 31 receives a torque transmitted from the wrench to the security nut 1.
The security nut 1 according to the first embodiment is formed such that, when a hexagonal socket 81 of a below-described general socket wrench 8 is engaged with the security nut 1, at least a part of the toque transmission surface 31 comes into surface-contact with an inner surface 8a of the hexagonal socket 81. In this case, when the security nut 1 is rotated in the tightening direction SB1, a toque is transmitted to the security nut 1 through a part (parallel surface 31a described below) of the torque transmission surface 31, which is in surface-contact with the inner surface 8a of the hexagonal socket 81. In the example shown in
The release surface 32 forms, between it and the torque transmission surface 31, the ridge line 33. In the example shown in
As described above, the ridge line 33 inclines toward the upstream side of the tightening direction SB1 along the circumferential direction DB, from the advancing-direction end 91 of the nut body 11 to the retracting-direction end 91 of the nut body 11. Thus, as described below, when the hexagonal socket 81 is engaged with the security nut 1 and is rotated in the loosening direction SB2, the ridge line 33 guides the hexagonal socket 81 to float up.
The number, shape and arrangement of the torque transmission projections 3 of the security nut 1 can be suitably determined in accordance with a tool to be used for rotating the security nut 1. In the security nut 1 according to the first embodiment, the number, shape and arrangement of the torque transmission projections 3 are determined on the assumption that the security nut 1 is rotated by means of the below-described general socket wrench 8 having the hexagonal socket 81.
In the example shown in
The respective torque transmission projections 3 have the same shape with one another. Thus, circumferential lengths L2 of the torque transmission surfaces 31 of the torque transmission projections 3 are the same with one another. Similarly, circumferential lengths L3 of the release surfaces 32 of the torque transmission projections 3 are the same with one another.
The circumferential length L2 of the torque transmission surface 31 is a length along the circumferential direction DB of a part of the outer surface 11c of the nut body 11, at which a part of the torque transmission projection 3, which forms the torque transmission surface 31, is provided. In addition, the circumferential length L3 of the release surface 32 is a length along the circumferential direction DB of a part of the outer surface 11c of the nut body 11, at which a part of the torque transmission projection 3, which forms the release surface 32, is provided.
Here, the circumferential pitch L1 between the torque transmission projections 3, the circumferential direction L2 of the torque transmission surface 31, and the circumferential direction L3 of the release surface 32 preferably satisfy the following relationships.
0.5×L3≤L2≤L3 Expression (1)
0.2×L1≤L2≤0.4×L1 Expression (2)
In particular, when the circumferential length L2 of the torque transmission surface 31 is 0.5 times or more the circumferential length L3 of the release surface 32, and is 0.2 times or more the circumferential pitch L1, the following effect can be obtained. The circumferential length L2 of the torque transmission surface 31 can be sufficiently ensured, whereby a surface area of the torque transmission surface 31 can be sufficiently ensured. Thus, a torque from a tool rotating the security nut 1 can be transmitted to the security nut 1 in a sufficiently stable manner.
Here, a virtual surface 31b, which is an extension of the parallel surface 31a of each torque transmission 3, is considered. One-dot chain lines shown in
As shown in
Next, the flange 4 provided on the advancing-direction end 91 of the nut body 11 is described with reference to
The first surface 4b of the flange 4 is inclined inward in the radial direction DC from the rim part 4a toward the retracting-direction end 92. The second surface 4c is a plane perpendicular to the axial direction DA.
As shown in
As shown in
Next, the annular protrusion 51 provided on the retracting-direction end 92 of the nut body 11 is described with reference to
As shown in
(Operation)
Next, an operation of the security nut 1 as structured above is described.
(Operation Upon Tightening)
An example of an operation when the security nut 1 is tightened on a bolt is described with reference to
As shown in
Then, the first securement member 61 and the second securement member 62 are stacked such that the first bolt hole 61a and the second bolt hole 62a are aligned.
Then, the bolt 71 comprising a shaft part 712 having an outside screw 713 and a bolt head part 711 is prepared, and the shaft part 712 of the bolt 71 is inserted through the first bolt hole 61a and the second bolt hole 62a. The bolt 71 has a general shape, for example. For example, the shaft part 712 of the bolt 71 is inserted first through the second bolt hole 62a and then through the first bolt hole 61a.
Then, the inside screw 11a of the nut body 11 of the security nut 1 is partially meshed with the outside screw 713 of the shaft part 712 inserted through the first bolt hole 61a and the second bolt hole 62a. For example, after the bolt 71 has been held and secured, the inside screw 11a can be partially meshed with the outside screw 713 by rotating the security nut 1 in the tightening direction SB1 while bringing the advancing-direction end 91 of the nut body 11 of the security nut 1 close to the tip of the shaft part 712.
Then, the security nut 1 is further rotated in the tightening direction SB1 by means of a socket wrench 8 having a hexagonal socket 81.
The operation of rotating the security nut 1 by means of the socket wrench 8 is further described with reference to
In this manner, the torque transmission surface 31 of each torque transmission projection 3 comes into surface-contact with the inner surface 8a of the hexagonal socket 81. Then, the hexagonal socket 81 is rotated in the tightening direction SB1 while the bolt 71 is being secured. At this time, since the torque transmission surface 31 of each torque transmission projection 3 is in surface-contact with the inner surface 8a of the hexagonal socket 81, a torque from the rotating hexagonal socket 81 is transmitted to the security nut 1 through the torque transmission surface 31. This can rotate the security nut 1 in the tightening direction SB1. In this manner, the security nut 1 can be tightened on the bolt 71 by means of a general tool such as the socket wrench 8 having the hexagonal socket 81.
The security nut 1 is further rotated by means of the socket wrench 8 so that the security nut 1 is tightened on the bolt 71, as shown in
Since the security nut 1 comprises the flange 4 provided on the advancing-direction end 91 of the nut body 11, the following effect can be obtained when the security nut 1 is tightened on a bolt. That is to say, when a plurality of securement members 61, 62 are secured to each other by tightening the security nut 1 on a bolt, the flange 4 is interposed between the torque transmission projections 3 and the securement members 61, 62. Thus, there is no possibility that the torque transmission projections 3 come into direct contact with the securement members 61, 62 so as to be subject to a pressure from the securement members 61, 62. Thus, the torque transmission projections 3 are difficult to be damaged by the pressure from the securement members 61, 62.
(Operation Upon Loosening)
Next, an example of an operation of making difficult the security nut 1 tightened on the bolt 71 to be loosened is described with reference to
At this time, since the release surface 32 is inclined as described above, the release surface 32 and the inner surface 8a of the hexagonal socket 81 will not come into surface-contact with each other. In this case, the inner surface 8a of the hexagonal socket 81 bears against the ridge lines 33 without being in contact with the release surfaces 32. When the hexagonal socket 81 engaged with the securing nut 1 is further rotated in the loosening direction SB2, the hexagonal socket 81 floats up along the inclination of the ridge lines 33, so that the hexagonal socket 81 is disengaged from the security nut 1. Thus, even when the hexagonal socket 81 engaged with the security nut 1 is rotated toward the loosening direction SB2, no torque is transmitted to the security nut 1 from the hexagonal socket 81, whereby it is impossible to loosen the security nut 1. Thus, the security nut 1 according to the first embodiment can make it difficult to be loosened once it has been tightened.
Next, a second embodiment of the present disclosure is described.
The second embodiment relates to a security bolt 2 including a shaft part 22 having an outside screw 22a, and a bolt head part 21 provided on the shaft part 22. The bolt head part 21 has a torque transmission projection 3 having the same structure as the security nut 1 in the first embodiment. Namely, it is difficult for the security bolt 2 shown in the second embodiment to be loosened once it has been tightened. In the second embodiment, differences from the first embodiment are mainly described. In the following description and the drawings used in the following description, parts that can be configured in the same manner as the first embodiment described above are shown by the same reference numerals used for corresponding parts in the first embodiment, and redundant description is omitted.
Next, respective constituent elements of the security bolt 2 are further described.
The shaft part 22 is described. As described above, the shaft part 22 is a part of the security bolt 2, which has an outside screw 22a. In the example shown in
Next, the bolt head part 21 is described first. As described above, the bolt head part 21 of the security bolt 2 has the bolt head part body 211, the torque transmission projections 3, the flange 4, and the truncated conical protrusion 53. The bolt head part body 211 has the same shape as that of the nut body 11 in the first embodiment, except that it does not have the inside screw 11a and the through hole 11b. The description about the nut body 11 in the first embodiment is applied to the description about the bolt head part body 211 in the second embodiment, as long as they are not contradictory to each other. In the bolt head part body 211, an end where the shaft part 22 is located is an advancing-direction end 91. An end of the bolt head part body 211, which is opposed to the advancing-direction end 91, is a retracting-direction end 92.
Next, the torque transmission projections 3 of the security bolt 2 are described with reference to
As described above, the security bolt 2 comprises a plurality of the torque transmission projections 3 provided on the outer surface 21c of the bolt head part body 211 along the circumferential direction DB. A shape of the torque transmission projection 3 provided on the bolt head part body 211 and a positional relationship between the torque transmission projections 3 and the bolt head part body 211 are the same as the shape of the torque transmission projection 3 and the positional relationship between the torque transmission projections 3 and the nut body 11 in the first embodiment, as long as they are not contradictory to each other.
Namely, each torque transmission projection 3 has a torque transmission surface 31 provided on an upstream side in a tightening direction SB1 of the security bolt 2, and a release surface 32 provided on a downstream side in the tightening direction SB1 of the security bolt 2. In addition, a ridge line 33 is formed between the torque transmission surface 31 and the release surface 32. The ridge line 33 inclines toward the upstream side of the tightening direction SB1 along the circumferential direction DB, from the advancing-direction end 91 of the bolt head part body 211 to the retracting-direction end 91 of the bolt head part body 211 (see
A circumferential pitch between the torque transmission projections 3 is represented as L4, a circumferential length of the torque transmission surface 31 of each torque transmission projection 3 is represented as L5, and a circumferential length L6 of the release surface 32 of each torque transmission projection 3 is represented as L6. In this case, the circumferential pitch L4 between the torque transmission projections 3, the circumferential length L5 of the torque transmission surface 31, and the circumferential length L6 of the release surface 32 preferably satisfy the following relationships.
0.5×L6≤L5≤L6 Expression (3)
0.2×L4≤L5≤0.4×L4 Expression (4)
When the circumferential pitch L4 between the torque transmission projections 3, the circumferential length L5 of the torque transmission surface 31, and the circumferential length L6 of the release surface 32 satisfy the Expressions (3) and (4), the security bolt 2 can have an effect corresponding to the effect obtained in the security nut 1 according to the first embodiment wherein the circumferential pitch L4 between the torque transmission projections 3, the circumferential length L5 of the torque transmission surface 31, and the circumferential length L6 of the release surface 32 satisfy the Expressions (1) and (2).
As described above, the bolt head part 21 has the flange provided on the advancing-direction end 91 of the bolt head part body 211. A shape of the flange 4 provided on the bolt head part 21 and a positional relationship between the flange 4 and the bolt head part body 211 are the same as the shape of the flange 4 and the positional relationship between the flange 4 and the nut body 11 in the first embodiment, as long as they are not contradictory to each other.
As described above, the bolt head part 21 has the truncated conical protrusion 53 provided on the retracting-direction end 92 of the bolt head part body 211. The truncated conical protrusion 53 has a shape that inhibits the security bolt 2 from being grasped by means of a general tool such as pliers. In the example shown in
(Operation)
Next, an operation of the security bolt 21 as structured above is described.
(Operation Upon Tightening)
An example of an operation when the security bolt 2 is tightened on a nut is described first with reference to
As shown in
Then, the first securement member 61 and the second securement member 62 are stacked such that the first bolt hole 61a and the second bolt hole 62a are aligned.
Then, the shaft part 22 of the security bolt 2 is inserted through the first bolt hole 61a and the second bolt hole 62a. For example, the shaft part 22 of the security bolt 2 inserted first through the second bolt hole 62a and then through the first bolt hole 61a.
Then, the nut 72 comprising an inside screw 721 is prepared. The inside screw 721 of the nut 72 is partially meshed with the outside screw 22a of the shaft part 22 inserted through the first bolt hole 61a and the second bolt hole 62a. The nut 72 has, for example, a general shape. For example, after the security bolt 2 has been held and secured, the inside screw 721 can be partially meshed with the outside screw 22a by rotating the nut 72 while bringing the inside screw 721 of the nut 72 close to the tip of the shaft part 22.
Then, the security bolt 2 is rotated in the tightening direction SB1 by means of a socket wrench 8 having a hexagonal socket 81 as shown in
An effect caused by the torque transmission projections 3 when the security bolt 2 is tightened on the nut 72 is the same as the effect caused by the torque transmission projections 3 when the security nut 1 is tightened on the bolt 71 according to the first embodiment.
(Operation Upon Loosening)
Because of the same operation as the operation of making difficult the security nut 1 tightened on the bolt 71 according to the first embodiment to be loosened, the security bolt 2 tightened on the nut 72 can be made difficult to be loosened.
The aspect of the present invention is not limited to the aforementioned embodiments, but includes various modification examples conceivable by those skilled in the art. The effect of the present invention is also not limited to the aforementioned effect. Namely, various additions, changes and partial deletions are possible to the extent that they do not deviate from the conceptual idea and purpose of the invention derived from the contents specified in the claims and their equivalents.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021-063099 | Apr 2021 | JP | national |
