JP2000018231A - Screwing body release preventing tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the releasing of a screwing body such as a bolt and a nut after the screwing by a mischief or the like. SOLUTION: This screwing body release preventive tool is composed of a container form cap 1 which can cover the outer side of a screwing body such as a nut or a bolt head; and a washer 2 or a C-shape ring fixed to the screwing body; and by locking an engaging receiver 13 formed on the inner peripheral surface of the cap 1 by the elastic deforming part of the washer 2 or the C-shape ring, the cap 1 is made impossible to remove in the condition covered on the outer side of the screwing body, and thereby, the screwing body is made impossible to release by a mischief or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screw unthread prevention device for preventing screw members such as bolts and nuts after being screwed and tightened from being unraveled by mischief.

[0002]

BACKGROUND OF THE INVENTION Outdoor constructions, such as towers, for example, use a large number of bolts and nuts for their assembly, but these threads are external to the construction. Is left uncovered. By the way, if the screw body for assembling the structure is exposed to the outside, the screw body can be unscrewed with a tool, and there is a risk that an insidious person may twist the screw body by mischief.

Conventionally, as a bolt / nut loosening prevention structure, for example, a split nut has been used, and after tightening the nut, a split pin is inserted. However, in this case, a locking function is provided. However, it cannot prevent twisting due to mischief. Also, conventionally, there is a type in which the outer surface of the bolt head or the nut is machined into a shape that can be turned in the screwing direction but hard to be tooled in the screwing direction,
Even in this case, the screw body cannot be completely prevented from being untwisted. It is conceivable to weld the screw body after screwing and tightening the screw body so that the screw body cannot be unscrewed, but in that case, welding equipment is required on site and welding is troublesome.

[0004] It is an object of the present invention to provide a screw body untwisting device which can prevent screw bodies such as bolts and nuts after screwing from being screwed by mischief.

[0005]

The present invention has the following structure as means for solving the above-mentioned problems.

[0006] screw body threaded solution preventer of the invention of claim 1 appended claims to one aspect of the present invention, in the container-like cap and the washer of the screw body that can cover the outer screw member such as a nut or bolt head It is configured.

[0007] The cap has a volume capable of accommodating a nut or bolt head therein. In the case where a double nut (two-step upper and lower nuts) is used as the screw body, the height of the cap is set to a value corresponding thereto. The material of the cap may be metal or plastic.

The washer is preferably made of metal. In addition, a hole for bolt insertion is formed in the center of the washer.
At least two leaf springs are integrally formed on the outer periphery of the washer at a predetermined angular interval. In addition, each leaf spring is
It is preferable to form them at equal angular intervals on the outer periphery of the washer. or,
Each leaf spring has a locking piece that is elastically deformable in the radial direction of the washer and that is inclined downward and outward.

On the other hand, an engagement receiving portion is formed on the inner peripheral surface of the cap to engage with the lower end of each locking piece of each leaf spring. The engagement receiving portion is preferably a concave groove. Further, the engagement receiving portion may be formed only in a portion corresponding to each locking piece, or may be continuous with the entire inner surface of the cap.

[0010] In the screw body anti-threading device of the present invention, the washer is fixed with the screw body, and the cap is placed on the outside of the screw body. The receiving part is engaged from above.

[0011] The screw body twist prevention device of claim 1 of the present application is used as follows. That is, when fixing the structure with the bolt and nut, the washer with a leaf spring is fixed with the bolt head or nut. In this state, each leaf spring of the washer is located outside the bolt head or the nut, respectively, and the locking pieces of each leaf spring are respectively arranged downward and obliquely outward. Next, when the cap is pressed down from above the bolt head or the nut, the lower opening edge of the cap abuts against each locking piece (slope), and each leaf spring is bent inward. When the cap is further moved down, the leaf spring elastically returns when the lower end of each locking piece corresponds to the engagement receiving portion on the inner surface of the cap, and the lower end of each locking piece is engaged with the cap. The engagement portion is engaged with the receiving portion from above, and at this time, the setting of the screw body twist prevention device is completed.

[0012] In the set state of the screw body screw preventing device of the first aspect, since the cap covers the outside of the bolt head or the nut, the bolt head or the nut cannot be screwed from the outside. . In addition, each locking piece (a plurality of locking pieces in the circumferential direction) of the washer fixed to the bolt head or the nut is engaged with the engagement receiving portion of the cap from the upper side. At the same time, the cap cannot be removed unless it is forced to flex inward. Therefore, when the cap is set on the bolt head or nut, the bolt or nut cannot be twisted by mischief. In addition, when the cap is covered, the bolt head or the nut is completely covered with the cap, so that the bolt head or the nut does not get wet with rainwater and rust can be prevented.

According to a second aspect of the present invention, there is provided a screw body anti-threading device according to the second aspect of the present invention, which is capable of elastically deforming in a radial direction with a container-like cap capable of covering the outside of a screw body such as a nut or a bolt head. And a perfect C-shaped ring. That is, in the second aspect, a C-shaped ring is employed as the means for locking the cap, instead of the washer of the first aspect.

The C-shaped ring is made of steel. Also, the C-shaped ring has a ring outer diameter slightly larger than the inner diameter of the cap in a free state, and the ring outer diameter becomes equal to or smaller than the inner diameter of the cap when compressed inward in the radial direction. A shape is adopted.

An annular engagement receiving portion is formed on the inner peripheral surface of the cap so as to engage with the outer peripheral edge of the C-shaped ring.

[0016] In the screw member anti-threading device of the second aspect, the C-shaped ring is fixed so as to be immovable in the bolt axis direction by a screw member in a state where it can be elastically deformed in the radial direction. With the cap on, the outer peripheral edge of the C-shaped ring is engaged with the engagement receiving portion of the cap from above. In the screw body anti-threading device of the second aspect, a spacer of the C-shaped ring may be used as a means for fixing the C-shaped ring in a state capable of being elastically deformed in the radial direction by the screw body. It is good to use what integrally formed the spacer part of the C-shaped ring.

The screw untwisting device according to claim 2 of the present application is used as follows. That is, according to the second aspect, when the structure is fixed with the bolt and the nut, the C-shaped ring is fixed in a state of being elastically deformable in the radial direction and immovable in the axial direction of the bolt with the bolt head or the nut. . next,
When the cap is pressed down from above the bolt head or the nut, the lower end opening edge of the cap abuts against the outer peripheral edge of the C-shaped ring from the outside thereof, thereby bending the C-shaped ring inward. When the cap is further moved down, the C-shaped ring elastically returns when the outer peripheral edge of the C-shaped ring corresponds to the engagement receiving portion on the inner surface of the cap, and the outer peripheral edge of the C-shaped ring is At this point, the setting of the screw unthread prevention device is completed.

[0018] Even in the set state of the screw body screw preventing device according to the second aspect, since the cap covers the outside of the bolt head or the nut, the bolt head or the nut cannot be screwed from outside. . Also, since the outer peripheral edge of the C-shaped ring fixed to the bolt head or the nut is engaged with the engagement receiving portion of the cap, unless the C-shaped ring is forcibly bent inward, The cap cannot be removed. Therefore, even with the screw body screw preventing device according to the second aspect, when the cap is set on the bolt head or the nut, the bolt or the nut cannot be screwed by mischief.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. 1 to 11. FIGS. 1 to 3 show a first embodiment, FIGS. 4 and 5 show a second embodiment, and FIGS. 7 and 8 show a third embodiment, FIGS. 8 and 9 show a fourth embodiment, and FIGS. 10 and 11 show a fifth embodiment. In these embodiments, the upper fixing member 5 is tightened to the lower base member 6 with the bolts 3 and the nuts 4, and a screw body is screwed to the nut 4 side exposed above the upper fixing member 5. Attach the protective equipment. Therefore, in each of the first to fifth embodiments, the nut 4 is a screw body described in the claims of the present application.

The first embodiment of FIGS. 1 to 3 and the second embodiment of FIGS. 4 and 5 correspond to the first embodiment of the present invention, respectively, and correspond to the third embodiment of FIGS. 8 and 9
The fourth embodiment of FIG. 10 and the fifth embodiment of FIGS.
Each corresponds to the implementation of claim 2 of the present application. In addition, each of the screw body untwisting devices according to the first embodiment shown in FIGS. 1 to 3 and the third embodiment shown in FIGS. 6 and 7 has a structure in which one nut 4 is screwed to the bolt 3. On the other hand, each screw body anti-splitting device of the second embodiment shown in FIGS. 4 and 5, the fourth embodiment shown in FIGS. 8 and 9, and the fifth embodiment shown in FIGS. This is applied when two upper and lower nuts (so-called double nuts) 4 and 4 are screwed to the bolt 3.

FIG.
As shown in the figure, a nut (screw body) screwed to the bolt 3
4 includes a cap 1 capable of covering the outside of the nut 4 and a washer 2 laid on the lower surface of the nut 4.

The material of the cap 1 may be metal or plastic. The cap 1 is formed in an inverted container shape in which an upper portion of a side peripheral wall 11 whose lower side is opened is closed by an upper surface wall 12. The cap 1 of the first embodiment is
As shown in FIG. 2, a large-diameter portion for accommodating one nut 4 and one washer 2 on a lower side, and a tip portion (screw portion) of a bolt 3 projecting from an upper surface of the nut 4 on an upper side. And a small diameter portion to be formed are integrally formed. In the cap 1, the inner diameter of the lower side peripheral wall 11 is slightly larger than the maximum diameter portion (diagonal length of the corner) of the nut 4 to be covered. In the cap 1, the side peripheral wall 11 may be a large diameter portion having the same diameter over the entire height.

The washer 2 is preferably made of a steel plate. As the washer 2, one in which two leaf springs 22 are integrally formed at a position facing the outer periphery (interval of 180 °) of a ring portion 21 having a bolt insertion hole 25 formed in the center portion is used.
In another embodiment, three or more leaf springs 22 may be formed. In this case, the leaf springs 22 may be formed at equal angular intervals on the outer periphery of the washer.

In the first embodiment, each of the leaf springs 22 has a small height (for example, nut 4) from the outer periphery of the ring portion 21.
(Up to の of the height of the slab), and locking pieces 24, 24, which are inclined downward and outward, are formed at the upper ends of the rising pieces 23, 23. ing. The distance W (FIG. 1) between the lower ends of the locking pieces 24, 24 of the two leaf springs 22, 22 is slightly larger than the inner diameter D of the cap-side peripheral wall 11. And each leaf spring 2
2 and 22 are each elastically deformable in the radial direction of the ring portion 21. In the leaf spring 22 of the first embodiment, the rising piece 23 is mainly elastically deformed.

On the other hand, on the inner peripheral surface of the cap side peripheral wall 11 near the lower end, the locking pieces 24, 24 of the leaf springs 22, 22 are provided.
Are formed with engagement receiving portions 13 which engage with the lower ends of the respective members. The engagement receiving portion 13 is formed in an annular groove shape. Note that the engagement receiving portion 13 may be formed only in a portion corresponding to each of the locking pieces 24, 24.

Engagement receiving portion 13 on cap side peripheral wall 11
Are formed in the vicinity of the upper part at intervals of 90 ° in the circumferential direction. The number of the small holes 17 may be only two at the opposing position, and the small holes 17 may not be formed if there are three or more leaf springs 22 formed on the washer 2 side. These small holes 17, 17
After the cap 1 is set outside the nut 4, when it is necessary to remove the cap 1 for some reason (for example, adjusting the position of the fixed members 5 and 6), as shown in FIG. This is for inserting children 7a, 7a.
The method of using the tool 7 will be described later.

The screw untwisting device of the embodiment shown in FIG. 1 is used to prevent unscrewing of a screw (bolt head or nut) of an outdoor building fixed with bolts and nuts such as a steel tower. However, how to use it will be described below. When fixing the structure (the lower base member 6 and the upper fixing member 5) with the bolt 3 and the nut 4, as shown in FIG.
The washer 2 is fixed between the lower surface of the nut 4 (it may be a bolt head) and the upper surface of the upper fixing member 5 with the 2 facing upward. In this state, each leaf spring 2 of the washer 2
2 and 22 are located outside the nut 4, and the locking pieces 24 and 24 of the leaf springs 22 and 22 respectively face downward and obliquely outward. Next, when the cap 1 is put on the nut 4 from above and pressed down, as shown in FIG.
4 against the slope of each leaf spring 22, 22 (rising piece 23).
Parts) are bent inward. And FIG. 3 (B)
When the cap 1 is further moved downward from the state shown in FIG.
3, the leaf springs 22 return elastically to the outside, and the lower ends of the locking pieces 24, 24 are attached to the engagement receiving portions 13 on the cap 1 side from above, as shown in FIG. Engage.
As described above, in the screw unthread prevention device, the setting is completed only by pushing down the cap 1 from above with the washer 2 attached below the nut 4. In this setting state, the lower end surface of the cap 1 is close to the upper surface of the upper fixing material 5.

In the set state of the screw untwisting device,
As shown in FIG. 2, since the cap 1 covers the outside of the nut 4, the nut 4 cannot be screwed from the outside. The nut 4 is provided on the engagement receiving portion 13 of the cap 1.
The cap 1 is removed unless the locking pieces 24, 24 of the washer 2 fixed to the inner side are engaged from above, unless the locking pieces 24, 24 are simultaneously forcibly bent inward. Can not. Therefore, when the cap 1 is set on the nut 4, the nut 4 cannot be unscrewed.
When it is necessary to adjust the position of the upper fixing member 5 after the cap 1 is put on, for example, the cap 1 is turned to rotate the two small holes 17 and 17 formed in the side peripheral wall 11 thereof.
Correspond to the respective leaf springs 22, 22, and in this state, the respective leaf springs 22, 22 are pressed inwardly through the small holes 17, 17 by the respective tip projections 7 a, 7 a of the tool 7. Then, each of the leaf springs 22, 22 is bent inward, and each of the locking pieces 24, 2 is bent.
When the cap 4 is disengaged from the engagement receiving portion 13 and the cap 1 is pulled up in this state, the cap 1 can be removed.
After removing the cap 1, loosening the nut 4 with a tool, adjusting the position of the upper fixing material 5, and tightening the nut 4 again,
The cap 1 is reset outside the nut 4. In addition, after confirming that the upper fixing material 5 was attached to the normal position,
If the small hole 17 of the cap 1 is filled with an appropriate filler, there is no need to remove the cap 1 unless the cap 1 (or the leaf spring 22) is broken firmly, and the nut 4 can be loosened by mischief by a mischievous person. Trouble can be completely prevented. In addition, when the cap 1 is covered, the bolt screw portion and the nut 4 are completely covered by the cap 1, so that
The bolt screw portion and the nut are no longer wet with rainwater, thereby preventing rust. Also, in this embodiment,
The engagement receiving portion 13 on the cap 1 side is formed in an annular shape,
When the cap 1 in the set state is rotated horizontally, the caps 1 do not come off even when the cap 1 is rotated, since the caps 1 rotate idly in a state in which the locking pieces 24 are engaged with the engagement receiving portions 13. .

The screw thread preventing device of the second embodiment shown in FIGS. 4 and 5 is used when two nuts 4 and 4 (so-called double nuts) are screwed to the bolt 3. In this case, the height of the side peripheral wall 11 of the cap 1 is increased to match the height of the double nuts 4. The leaf springs 22, 22 of the washer 2 extend downward and obliquely outward from two locations on the outer periphery of the ring portion 21, respectively. In the case of the second embodiment, the leaf spring 22 itself serves as the locking piece 24.

The screw member untwisting device of the second embodiment is
It is used as follows. First, the base member 6 and the upper fixing member 5 are fastened and fixed with the lower nut 4 and the bolt 3, and the washer 2 is placed on the lower nut 4 with the leaf spring 22 facing upward, and the washer 2 is raised. It is fixed with the nut 4. Then, similarly to the first embodiment, when the cap 1 is pushed down so as to cover the outer sides of the double nuts 4, 4, the engagement receiving portions 13 on the cap 1 side engage the locking pieces 2 of the leaf springs 22, 22.
Engage with the lower ends of 4,24. It should be noted that the screw member untwisting device of the second embodiment also functions in the same manner as that of the first embodiment.

6 and 7, a screw ring preventing device according to a third embodiment uses a C-shaped ring 2A in place of the washer 2 of the first embodiment. This C-shaped ring 2A is elastically deformable in the radial direction, and in its free state, the outer diameter X is slightly larger than the inner diameter D of the cap 1, and when bent inward in the radial direction, it is equal to or larger than the inner diameter D of the cap. A form that can be reduced to a small diameter is also employed. The lower end opening edge 14 of the cap 1 is a tapered surface that is open outward, and the lower end inner diameter of the lower end opening edge 14 is the C-shaped ring 2.
The outer diameter X is set to be slightly larger than the outer diameter X in the free state of A. The C-shaped ring 2 of this embodiment
A has a ring material having a square cross section, but may have a circular cross section.

In addition, in the screw-thread releasing device according to the third embodiment, the washer 3 functioning as a spacer for the C-shaped ring 2A.
1 is used. As the washer 31, a ring body having a vertical step with a large diameter on the lower side and a small diameter on the upper side is used. The outer diameter E of the lower large diameter portion 32 of the washer 31 is slightly larger than the inner diameter Y of the hole 25A of the C-shaped ring 2A in a free state and slightly smaller than the outer diameter X of the C-shaped ring 2A. Also, the outer diameter F of the upper small diameter portion 33 of the washer 31.
Is slightly smaller than the inner diameter Y of the C-shaped ring 2A, and the C-shaped ring 2A is arranged on the outer periphery of the upper small-diameter portion 33 of the washer 31 (mounted on the lower large-diameter portion 32). A gap is formed to allow the shaped ring 2A to bend inward in the radial direction. Furthermore, the upper small diameter portion 3 of the washer 31
The height G of 3 is slightly (for example, about 0.5 mm) slightly larger than the thickness Z of the C-shaped ring 2A.

[0033] The screw body untwisting device according to the third embodiment comprises:
It is used as shown in FIG. That is, in the usage example of FIG. 7, the bolt 3 is inserted from below into each hole of the building (the lower base member 6 and the upper fixing member 5), and the washer 31 is fitted to a screw portion projecting upward from the upper fixing member 5. Combine. Next, after the C-shaped ring 2A is externally fitted to the upper small diameter portion 33 of the washer 31 (after being placed on the lower large diameter portion 32), the nut 4 is screwed and tightened to the bolt screw portion. In this state, the C-shaped ring 2A is sandwiched between the upper surface of the lower large-diameter portion 32 of the washer and the lower surface of the nut 4, and cannot be moved up and down, but is elastically deformed in the radial direction. It is possible to do. Then, when the cap 1 is put on from above the nut 4 and pressed down, the outer peripheral edge of the C-shaped ring 2A is pressed inward by the lower opening edge 14 (having a tapered surface) of the cap 1 so that the C The shape ring 2A is bent inward.
When the cap 1 is further moved downward, when the C-shaped ring 2A corresponds to the engagement receiving portion 13 on the inner surface of the cap, the C-shaped ring 2A elastically returns to the outside, and its outer peripheral edge is closer to the cap 1 side. Into the engagement receiving portion 13. Also in the case of the third embodiment, the engagement receiving portion 13 of the cap 1 is locked to the outer peripheral edge of the C-shaped ring 2 </ b> A fixed with the nut 4 in the set state of the screw unthread prevention device. Therefore, unless the C-shaped ring 2A is forced to bend inward, the cap 1
Can not be removed. If it is necessary to remove the cap 1 for some reason, the cap-side peripheral wall 11
The C-shaped ring 2A may be forcibly bent inward by inserting the tip projections 7a, 7a of the tool 7 (FIG. 2) from the holes 17, 17 formed in the C-shaped ring 2A.

In the fourth embodiment shown in FIG. 8 and FIG.
To make room for the installation of the shaped ring 2A, the nut 4
A small-diameter portion 43 is formed on one surface of A. In addition, this 4th
In the embodiment, the structure (the lower base member 6 and the upper fixing member 5)
In order to assemble, as shown in FIG.
A is used. Then, the nut 4 </ b> A having the small-diameter portion 43 formed on the thread portion of the bolt 3 is first attached to the small-diameter portion 43.
Is screwed and tightened so that the upper side is
A C-shaped ring 2 </ b> A is fitted to the outer periphery of 3, and then the upper nut 4 is tightened. In this case, the C-shaped ring 2A
Are elastically deformable in the radial direction. Then, when the cap 1 is pushed down while being covered with the nuts 4 and 4A, the engagement receiving portion 13 of the cap 1 is moved to the C-shaped ring 2A.
Can be locked.

In the fifth embodiment shown in FIGS. 10 and 11, a stepped nut 4B is used in addition to the double nuts 4 to create a space for installing the C-shaped ring 2A. The stepped nut 4B has a small diameter portion 43 formed on the lower surface thereof. Then, the structure (lower base member 6)
After the upper fixing member 5) is assembled with the bolts 3 and the double nuts 4 and 4, the C-shaped ring 2A is placed on the upper surface of the upper nut 4, and then the stepped nut 4B is placed in such a manner that the small diameter portion 43 faces down. Screw and tighten to the bolt thread. In this case, the C-shaped ring 2A is also elastically deformable in the radial direction. Then, when the cap 1 is pushed down while being covered with the nuts 4, 4, and 4B, the engagement receiving portion 13 of the cap 1 can be locked to the C-shaped ring 2A.

In the third to fifth embodiments shown in FIGS. 6 to 11, the engagement receiving portion 13 on the cap 1 side is
Is positioned so as to match the height of the C-shaped ring 2A to be assembled. Further, in the third to fifth embodiments, since the inner diameter of the cap 1 is slightly larger than the outer diameter of the nuts 4, 4A, 4B, the cap 1 may be kneaded with, for example, a crowbar or a screwdriver. Since the inner surface of the cap abuts against the outer surface of the nut 4, 4A, 4B or the C-shaped ring 2A, the cap 1 cannot be kneaded. Note that, in each embodiment, portions denoted by the same reference numerals have the same function.

[0037]

According to the first and second aspects of the present invention, the anti-threading device has the following effects. In other words, when the screw body anti-splitting device of the present application is used, the outside of the screw body 4 such as a bolt head or a nut can be covered with the container-like cap 1.
The tightened screw body 4 cannot be unraveled by mischief. In addition, in the set state of the screw body untwisting device,
Since the engagement receiving portion 13 of the cap 1 is engaged with the locking pieces 24, 24 of the washer 2 or the outer peripheral edge of the C-shaped ring 2A in the cap 1, the cap 1 cannot be removed,
There is an effect that mischief (the unraveling of the screw body 4) can be reliably prevented. Further, the cap 1 is provided with each locking piece 2 of the washer 2.
Since it can be set only by pushing down on the 4, 24 or C-shaped ring 2A, there is an effect that the setting operation can be easily performed. Further, in the state where the cap 1 is covered, the bolt screw portion and the nut 4 are completely covered with the cap 1, so that the bolt screw portion and the nut do not get wet with rainwater, and the rust can be prevented from being generated. There is also.

[Brief description of the drawings]

FIG. 1 is a perspective view of a screw body twist prevention device according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a use state of the screw body anti-splitting device of FIG. 1;

FIG. 3 is an explanatory view of a setting method of the screw body anti-splitting device of FIG. 1;

FIG. 4 is a perspective view of a screw body twist prevention device according to a second embodiment of the present application.

FIG. 5 is a cross-sectional view showing a use state of the screw body twist prevention device of FIG. 4;

FIG. 6 is a perspective view of a screw body twist prevention device according to a third embodiment of the present application.

FIG. 7 is a cross-sectional view showing a use state of the screw body twist prevention device of FIG. 6;

FIG. 8 is a perspective view of a screw body twist prevention device according to a fourth embodiment of the present invention.

FIG. 9 is a cross-sectional view showing a use state of the screw body twist prevention device of FIG. 8;

FIG. 10 is a perspective view of a screw body twist prevention device according to a fifth embodiment of the present invention.

FIG. 11 is a cross-sectional view showing a use state of the screw body twist prevention device of FIG. 10;

[Explanation of symbols]

1 is a cap, 2 is a washer, 2A is a C-shaped ring, 3 is a bolt, 4 is a nut (screw body), 11 is a side peripheral wall, 13 is an engagement receiving portion, 21 is a ring portion, 22 is a leaf spring, and 24 is a leaf spring. It is a locking piece.

Claims (2)

[Claims] A screw body (4) such as a nut or bolt head
And a washer (2) of a screw body (4) that can cover the outside of the at least two leaf springs (2) on the outer periphery of the washer (2) at a predetermined angular interval. Each leaf spring (22, 22) has a locking piece (24) that is elastically deformable in the radial direction of the washer (2) and is inclined downward and obliquely outward. The locking piece (2) is provided on the inner peripheral surface of the cap (1).
Engagement receiving portions (13) respectively engaged with the lower ends of (4, 24).
In addition, the washer (2) is fixed with the screw body (4), and the cap (1) is covered on the outside of the screw body (4). 22. A screw body twist prevention device, wherein the lower ends of the locking pieces (24, 24) of (22) are respectively engaged with the engagement receiving portions (13) of the cap (1) from above. 2. A screw (4, 4) such as a nut or bolt head.
4A, 4B), a container-like cap (1) capable of covering the outside and a C-shaped ring (2A) elastically deformable in the radial direction.
And the C-shaped ring (2) is provided on the inner peripheral surface of the cap (1).
A) An annular engagement receiving portion (13) is formed to engage with the outer peripheral edge of the screw body (4, 4A) while the C-shaped ring (2A) is elastically deformable in the radial direction. , 4B), the outer peripheral edge of the C-shaped ring (2A) is fixed in a state where the cap (1) is put on the outside of the screw body (4, 4A, 4B). The engagement receiving portion (1) of the cap (1)
(3) The screw member is prevented from being unlocked from above.