Anti-loose double-nut bolt

Abstract

The utility model relates to the technical field of bolts, one embodiment of the utility model provides an anti-loose double-nut bolt which comprises a screw, an inner nut, an outer nut and an anti-loose bead, the inner nut and the outer nut are both in threaded connection to the screw, the outer nut abuts against the inner nut, an anti-loose wedge groove is formed in the inner wall of the outer nut, and the anti-loose bead is located in the anti-loose wedge groove. The depth of the anti-loosening wedge groove is gradually increased in the screwing direction of the outer nut, and after the outer nut rotates in the unscrewing direction, the anti-loosening bead moves towards the top of the anti-loosening wedge groove and is used for abutting against the screw rod, and force for preventing the outer nut from being unscrewed is provided. By means of the technical scheme, the technical problems that in the prior art, bolts are prone to loosening after being used for a long time, and an existing anti-loosening technology cannot meet use requirements are solved.

Description

Technical Field

[0001] The embodiments disclosed herein relate to the field of bolt technology, and more specifically, to a locking double-cap bolt. Background Technology

[0002] Bolted connections, as one of the most fundamental fastening methods in mechanical engineering, are widely used in machinery, building structures, transportation, and other fields. Traditional bolts typically consist of a bolt shank, a nut, and a matching washer, relying on the frictional force generated by the threaded engagement and axial preload to achieve their fastening function. However, under long-term dynamic loads, vibrations, or cyclic temperature changes, microscopic slippage can easily occur between the threaded parts, causing the preload to gradually decrease, leading to loosening or even complete failure of the bolt connection. Such loosening problems can cause minor issues like component displacement and decreased connection sealing, or more serious issues like structural instability or mechanical system collapse, posing significant safety hazards.

[0003] Existing technologies for improving bolt loosening prevention mainly include the following types: First, friction-based loosening (such as spring washers and double-nut structures), which delays loosening by increasing the friction of the contact surface, but its loosening prevention effect is easily affected by the vibration frequency and amplitude, and may still fail due to material fatigue or surface wear after long-term use; Second, chemical bonding-based loosening (such as threadlocker), which forms resistance after the adhesive fills the thread gap and cures, but has drawbacks such as limited curing time and difficulty in disassembly.

[0004] In summary, existing anti-loosening technologies often have limitations in terms of reliability, ease of use, cost, or applicable scenarios, making it difficult to meet the stringent requirements for long-term stability of bolted connections under complex working conditions. Therefore, there is an urgent need for a new bolt design scheme that is simple in structure, has excellent anti-loosening performance, and is reusable, in order to overcome the shortcomings of traditional technologies. Utility Model Content

[0005] To overcome the above-mentioned defects, the embodiments of this disclosure provide a double-cap bolt for preventing loosening, which solves the technical problem that bolts are prone to loosening after long-term use and that existing anti-loosening technologies cannot meet the usage requirements.

[0006] According to one aspect, at least one embodiment of this disclosure provides a locking double-nut bolt, including a screw, an inner nut, an outer nut, and a locking ball. The inner nut and the outer nut are both threaded onto the screw. The outer nut abuts against the inner nut. The inner wall of the outer nut has a locking wedge groove. The locking ball is located in the locking wedge groove. The depth of the locking wedge groove gradually increases along the tightening direction of the outer nut. When the outer nut is rotated in the loosening direction, the locking ball moves toward the top of the locking wedge groove to abut against the screw and provide a force to prevent the outer nut from loosening.

[0007] For example, in at least one embodiment of this disclosure, an anti-loosening double-cap bolt further includes:

[0008] It also includes a nylon retainer strip, which is detachably inserted into the anti-loosening wedge groove along the axial direction of the outer nut to block the anti-loosening bead.

[0009] For example, in at least one embodiment of this disclosure, an anti-loosening double-cap bolt further includes:

[0010] The outer nut has a through hole, the nylon strip has a screw hole, and a screw is also included. The screw passes through the through hole and is threaded into the screw hole for positioning the nylon strip.

[0011] For example, in at least one embodiment of this disclosure, an anti-loosening double-cap bolt further includes:

[0012] The inner nut end face has a tightening wedge groove, and the outer nut end face has a tightening wedge portion. The tightening wedge portion is used to cooperate with the tightening wedge groove after the outer nut and the inner nut are tightened together.

[0013] For example, in at least one embodiment of this disclosure, an anti-loosening double-cap bolt further includes:

[0014] The inner wall of the tightening wedge groove has a rubber lining.

[0015] For example, in at least one embodiment of this disclosure, an anti-loosening double-cap bolt further includes:

[0016] The sidewall of the tightening wedge has anti-slip texture, which is used to abut against the rubber lining.

[0017] For example, in at least one embodiment of this disclosure, an anti-loosening double-cap bolt further includes:

[0018] The outer nut end face has an anti-slip pad, which is used to abut against the end face of the inner nut.

[0019] For example, in at least one embodiment of this disclosure, an anti-loosening double-cap bolt further includes:

[0020] The outer nut has a countersunk hole on its surface, which communicates with the through hole and is used to accommodate the head of the screw.

[0021] The beneficial effects of the embodiments disclosed herein are as follows:

[0022] In this disclosure, in practical applications, the screw is first passed through the corresponding hole of the component to be fastened. Then, the inner nut is manually or with the aid of a tool screwed onto the screw. The position of the inner nut on the screw is adjusted according to the actual needs of the component connection until the desired pre-positioned state is achieved. At this point, the inner nut initially fixes the relative position of the connected components.

[0023] Next, begin tightening the outer nut. During the tightening process, as the depth of the anti-loosening wedge groove on its inner wall gradually increases along the tightening direction, the anti-loosening ball will move along the inclined surface of the anti-loosening wedge groove towards the deeper bottom as the outer nut rotates. Finally, the outer nut is successfully tightened and tightly abuts against the inner nut, achieving further fastening of the connected parts, while providing further locking force to the inner nut, thus achieving an anti-loosening effect.

[0024] When the equipment is in operation, the bolts are affected by external factors such as vibration, dynamic load, or temperature changes, causing the inner nut to be subjected to a force in the direction of loosening. The inner nut then begins to rotate. As the inner nut rotates, it transmits this loosening force to the outer nut. The anti-loosening ball gradually moves along the inclined surface of the anti-loosening wedge groove towards the shallower end (the shallower end) of the groove, eventually abutting against the bolt. This generates strong friction, which acts through the anti-loosening ball onto the bottom wall of the anti-loosening wedge groove. This friction is opposite to the loosening direction of the outer nut, effectively preventing the outer nut from loosening and thus ensuring the stability of the bolt connection under complex working conditions, preventing the connection from loosening.

[0025] Through its unique anti-loosening wedge groove and anti-loosening bead structure design, it can promptly generate a reverse resisting force when the bolt is subjected to loosening external force. Compared with traditional friction anti-loosening and chemical bonding anti-loosening, it is not affected by vibration frequency and amplitude, nor does it have problems such as curing time limitations, which greatly improves the anti-loosening reliability under complex working conditions. It consists of only a screw, inner nut, outer nut and anti-loosening bead, with a simple structure, easy to manufacture and assemble, reducing production costs and process difficulty. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this disclosure, the accompanying drawings used in the description of the embodiments of this disclosure will be briefly introduced below. Obviously, the drawings described below are merely some exemplary embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on the content of the exemplary embodiments of this disclosure and these drawings without any creative effort.

[0027] Figure 1 This is one of the structural schematic diagrams of an anti-loosening double-cap bolt in one embodiment of this disclosure;

[0028] Figure 2 This is a second schematic diagram of the structure of an anti-loosening double-cap bolt in one embodiment of the present disclosure;

[0029] Figure 3 for Figure 2 An enlarged view of point A in the embodiment;

[0030] Figure 4 for Figure 1 A schematic diagram of the structure of the inner wall of the outer nut in the embodiment;

[0031] Figure 5 for Figure 1 A schematic diagram of the structure of the end faces of the outer nut and the inner nut in the embodiment;

[0032] Figure 6 for Figure 5 Enlarged view of point B in the embodiment;

[0033] Figure 7 for Figure 5 Enlarged view of point C in the embodiment;

[0034] Figure 8 for Figure 1 A schematic diagram of the outer nut end face in the embodiment.

[0035] In the diagram: 1. Screw, 2. Inner nut, 3. Outer nut, 4. Anti-loosening ball, 5. Anti-loosening wedge groove, 6. Nylon retainer, 7. Through hole, 8. Screw hole, 9. Screw, 10. Tightening wedge groove, 11. Tightening wedge part, 12. Rubber liner, 13. Anti-slip texture, 14. Anti-slip pad, 15. Countersunk hole. Detailed Implementation

[0036] The present disclosure will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present disclosure and are not intended to limit the scope of the disclosure.

[0037] To keep the drawings concise, each drawing only schematically shows the parts relevant to the disclosure; these do not represent the actual structure of the product. Furthermore, for ease of understanding, in some drawings, only one of components with the same structure or function is schematically shown, or only one is labeled. In this document, "one" not only means "only one," but can also mean "more than one," and "several" includes "two" and "more than two."

[0038] In this document, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linkage" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this disclosure based on the specific circumstances.

[0039] In this disclosure, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0040] In the description of this embodiment, terms such as "upper," "lower," "left," and "right" are based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of description and simplification of operation, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this disclosure.

[0041] Furthermore, in the description of this application, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0042] like Figures 1-8 As shown, an anti-loosening double-nut bolt according to an embodiment of the present disclosure includes a screw 1, an inner nut 2, an outer nut 3, and an anti-loosening ball 4. The inner nut 2 and the outer nut 3 are both threaded onto the screw 1. The outer nut 3 abuts against the inner nut 2. The inner wall of the outer nut 3 has an anti-loosening wedge groove 5. The anti-loosening ball 4 is located in the anti-loosening wedge groove 5. The depth of the anti-loosening wedge groove 5 gradually increases along the tightening direction of the outer nut 3. After the outer nut 3 is rotated in the loosening direction, the anti-loosening ball 4 moves towards the top of the anti-loosening wedge groove 5 to abut against the screw 1 and provide a force to prevent the outer nut 3 from loosening.

[0043] For example, such as Figures 1-8As shown, in practical applications, first, thread the screw 1 through the corresponding hole of the component to be fastened. Then, manually or with the aid of a tool, screw the inner nut 2 onto the screw 1. Adjust the position of the inner nut 2 on the screw 1 according to the actual needs of the component connection until the ideal pre-positioned state is achieved. At this point, the inner nut 2 initially fixes the relative position of the connected components.

[0044] Then, begin tightening the outer nut 3. During the tightening process, as the depth of the anti-loosening wedge groove 5 on its inner wall gradually increases along the tightening direction, the anti-loosening ball 4 will move along the inclined surface of the anti-loosening wedge groove 5 to the deeper bottom as the outer nut 3 rotates. Finally, the outer nut 3 is successfully tightened and tightly abuts against the inner nut 2, achieving further fastening of the connecting parts, while providing further locking force to the inner nut 2, thus achieving an anti-loosening effect.

[0045] When the equipment is in operation, the bolt is affected by external factors such as vibration, dynamic load, or temperature changes, causing the inner nut 2 to be subjected to a force in the direction of loosening. The inner nut 2 then begins to rotate. As the inner nut 2 rotates, it transmits the force in the direction of loosening to the outer nut 3. The anti-loosening ball 4 gradually moves along the inclined surface of the anti-loosening wedge groove 5 towards the shallow end of the groove (i.e., the shallower end), and eventually abuts against the screw 1, generating a strong frictional force. This frictional force acts on the bottom wall of the anti-loosening wedge groove 5 through the anti-loosening ball 4. This frictional force is opposite to the direction of loosening of the outer nut 3, effectively preventing the outer nut 3 from loosening, thus ensuring the stability of the bolt connection under complex working conditions and preventing loosening.

[0046] Through the unique anti-loosening wedge groove 5 and anti-loosening ball 4 structural design, a reverse resisting force can be generated in time when the bolt is subjected to loosening external force. Compared with traditional friction anti-loosening and chemical bonding anti-loosening, it is not affected by vibration frequency and amplitude, and there are no problems such as curing time limitations, which greatly improves the anti-loosening reliability under complex working conditions. It consists of only a screw 1, inner nut 2, outer nut 3 and anti-loosening ball 4, with a simple structure, easy to manufacture and assemble, reducing production costs and process difficulty.

[0047] In some examples, a nylon retainer 6 is also included, which is detachably inserted into the anti-loosening wedge groove 5 along the axial direction of the outer nut 3 to block the anti-loosening bead 4.

[0048] For example, such as Figure 1 , 2As shown in Figures 4 and 5, during actual assembly, the initial installation of the screw 1, inner nut 2, and outer nut 3 is completed first. Once the outer nut 3 is tightened to the appropriate position and the anti-loosening ball 4 is at the deepest part of the anti-loosening wedge groove 5, the nylon retainer 6 is installed. The nylon retainer 6 is inserted into the anti-loosening wedge groove 5 along the axial direction of the outer nut 3, ensuring that it is tightly embedded. Once inserted, the nylon retainer 6 effectively prevents the anti-loosening ball 4 from dislodging. During normal bolt operation, the nylon retainer 6 continuously restricts the position of the anti-loosening ball 4, preventing it from dislodging from the anti-loosening wedge groove 5 when subjected to external forces such as vibration or impact.

[0049] When the bolt needs to be maintained, repaired, or parts replaced, and the outer nut 3 needs to be removed, simply pull the nylon retainer 6 out of the anti-loosening wedge groove 5 to release the obstruction of the anti-loosening ball 4, then invert the outer nut 3, allowing the anti-loosening ball 4 to fall out by its own weight. In some applications where inverting the outer nut 3 is not permitted, a special tool can be used to remove the anti-loosening ball 4. In this embodiment, the anti-loosening ball 4 is made of a ferromagnetic material. A rod with a magnetic adsorption element at the end can be used. The rod is inserted into the anti-loosening wedge groove 5, and after the magnetic adsorption element attracts the anti-loosening ball 4, the rod is pulled out, thereby removing the anti-loosening ball 4, allowing the outer nut 3 to be loosened normally.

[0050] The nylon retainer 6 effectively blocks the anti-loosening beads 4, preventing them from accidentally falling out under complex working conditions and ensuring stable anti-loosening performance. The nylon retainer 6 is detachable and easy to insert, making maintenance and replacement of the anti-loosening beads 4 or other components simple and convenient. The nylon material has good wear resistance and a certain degree of flexibility, not only providing stability by blocking the anti-loosening beads 4, but also resisting damage during repeated insertion and removal from the anti-loosening wedge groove 5.

[0051] In some examples, the outer nut 3 has a through hole 7, the nylon retainer 6 has a screw hole 8, and a screw 9 is also included, which passes through the through hole 7 and is threaded into the screw hole 8 for positioning the nylon retainer 6.

[0052] For example, such as Figure 2 , 4 As shown in Figure 5, select a suitable screw 9, pass it through the through hole 7 of the outer nut 3, and then begin to tighten it. As the screw 9 is screwed in, its thread engages with the threaded hole 8 on the nylon retainer 6 until the screw 9 is fully tightened. The screw 9 and the outer nut 3 are connected together, thereby achieving precise positioning of the nylon retainer 6, effectively preventing displacement or loosening of the nylon retainer 6, and ensuring that it always stably blocks the anti-loosening bead 4. When it is necessary to remove the nylon retainer 6, simply turn the screw 9 in the opposite direction to remove it from the threaded hole 8, and the nylon retainer 6 can be easily removed.

[0053] The nylon retaining strip 6 is securely connected to the outer nut 3 by screw 9, ensuring reliable fixation of the nylon retaining strip 6 and preventing loosening due to external forces. This ensures the nylon retaining strip 6 continuously and stably blocks the anti-loosening bead 4. The positioning method is simple and easy to operate. The combination of screw 9, screw hole 8, and through hole 7 is a common and standard connection method, facilitating easy replacement when components are damaged, reducing maintenance costs, and improving the product's versatility and practicality.

[0054] In some examples, the inner nut 2 has a tightening wedge groove 10 on its end face, and the outer nut 3 has a tightening wedge portion 11 on its end face. The tightening wedge portion 11 is used to engage with the tightening wedge groove 10 after the outer nut 3 and the inner nut 2 are tightened together.

[0055] For example, such as Figure 5 As shown, when installing the anti-loosening double-nut bolt, first screw the inner nut 2 onto the designated position on the bolt 1 to initially fix the connecting parts. Then screw on the outer nut 3, which gradually approaches the inner nut 2 during the tightening process. When the end face of the outer nut 3 is about to abut the end face of the inner nut 2, the tightening wedge 11 gradually embeds into the tightening wedge groove 10. Due to the wedge-shaped design of the tightening wedge 11 and the tightening wedge groove 10, they will wedge against each other during the embedding process. This wedge action increases the relative rotational resistance between the inner nut 2 and the outer nut 3. When subjected to external forces such as vibration or impact that may cause the bolt to loosen, the inner nut 2 and the outer nut 3 can better cooperate to resist these external forces and maintain relative stability, thereby effectively preventing the entire bolt connection from loosening.

[0056] The engagement of the tightening wedge 11 and the tightening wedge groove 10 forms an additional fastening structure between the inner and outer nuts 3, increasing the friction and engagement force between the nuts and improving the bolt's anti-loosening ability under complex working conditions. It cleverly utilizes the end face space of the nut, achieving improved anti-loosening performance without adding extra complex components or volume. The engagement process of the tightening wedge 11 and the tightening wedge groove 10 is naturally integrated into the tightening operation of the outer nut 3, requiring no additional installation steps or complex processes, and does not affect the original installation procedure.

[0057] In some examples, the inner wall of the tightening wedge groove 10 has a rubber lining 12.

[0058] For example, such as Figure 7As shown, during the manufacturing stage, the rubber liner 12 is pre-attached to the inner wall of the tightening wedge groove 10 to ensure that the rubber liner 12 is tightly attached and there is no risk of it falling off. During installation, when the outer nut 3 is tightened and the tightening wedge 11 contacts the tightening wedge groove 10, a large frictional force is generated between the surface of the rubber liner 12 and the tightening wedge 11. When the inner nut 2 and the outer nut 3 are subjected to external force and tend to rotate relative to each other, the rubber liner 12 will adapt to this tendency through its own deformation, always maintaining a tight contact with the tightening wedge 11, effectively preventing relative sliding between the tightening wedge 11 and the tightening wedge groove 10.

[0059] The rubber liner 12 generates higher friction than ordinary metal surfaces, significantly enhancing the connection and tightness between the inner nut 2 and the outer nut 3, and effectively improving the anti-loosening performance. The rubber liner 12 has good buffering and vibration damping properties. When the bolt is subjected to external forces such as vibration and impact, it can absorb some energy, reduce the relative displacement between the inner nut 2 and the outer nut 3, and further prevent the bolt from loosening.

[0060] In some examples, the sidewall of the tightening wedge 11 has anti-slip texture 13, which is used to abut against the rubber liner 12.

[0061] For example, such as Figure 5 , 6 As shown, during bolt assembly, when the outer nut 3 is tightened, the anti-slip texture 13 on the side wall of the tightening wedge 11 comes into contact with the rubber liner 12 on the inner wall of the tightening wedge groove 10. Due to the texture design of the anti-slip texture 13, its contact area with the rubber liner 12 is increased. The rubber liner 12, with its own elasticity, tightly adheres to the anti-slip texture 13, while the anti-slip texture 13 prevents the rubber liner 12 from sliding. The two work together to generate a strong frictional force, effectively resisting the relative rotation between the inner nut 2 and the outer nut 3, thereby preventing the bolt from loosening.

[0062] In some examples, the outer nut 3 has an anti-slip pad 14 on its end face, which is used to abut against the end face of the inner nut 2.

[0063] For example, such as Figure 5 , 6 As shown, the anti-slip pad 14 has a certain degree of elasticity and fits tightly against the end face of the inner nut 2 during the compression process. When the bolt is subjected to an external force that may cause loosening, such as vibration or impact, causing the inner nut 2 and the outer nut 3 to have a relative rotational tendency, the anti-slip pad 14, by virtue of its tight fit with the end face of the inner nut 2, hinders the relative movement of the inner nut 2 and the outer nut 3, thereby preventing the bolt connection from loosening.

[0064] In some examples, the outer nut 3 has a countersunk hole 15 on its surface, which communicates with the through hole 7 and is used to receive the head of the screw 9.

[0065] For example, such as Figure 3 As shown, the outer nut 3 has a countersunk hole 15 on its surface, which, together with the through hole 7, forms a stepped hole structure. After inserting the nylon retainer 6 into the anti-loosening wedge groove 5, the through hole 7 on the outer nut 3 and the screw hole 8 on the nylon retainer 6 are perfectly aligned. At this point, the screw 9 is inserted into the through hole 7 and then screwed into the screw hole 8 on the nylon retainer 6, thereby positioning the nylon retainer 6 and preventing the anti-loosening ball 4 from losing its limit position if the nylon retainer 6 accidentally falls off due to external force. After the screw 9 is installed in place, the nut on its head can be hidden in the countersunk hole 15, thus ensuring the flatness of the surface of the outer nut 3 and also protecting the screw 9.

[0066] It should be noted that the above embodiments are only used to illustrate the technical solutions of this disclosure and are not intended to limit it. Although this disclosure has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this disclosure without departing from the spirit and scope of the technical solutions of this disclosure, and all such modifications and substitutions should be covered within the scope of the claims of this disclosure.

Claims

1. A type of anti-loosening double-cap bolt, characterized in that, The device includes a screw (1), an inner nut (2), an outer nut (3), and a locking bead (4). The inner nut (2) and the outer nut (3) are both threaded onto the screw (1). The outer nut (3) abuts against the inner nut (2). The inner wall of the outer nut (3) has a locking wedge groove (5). The locking bead (4) is located in the locking wedge groove (5). The depth of the locking wedge groove (5) gradually increases along the tightening direction of the outer nut (3). After the outer nut (3) is rotated in the loosening direction, the locking bead (4) moves toward the top of the locking wedge groove (5) to abut against the screw (1) and provide a force to prevent the outer nut (3) from loosening.

2. The anti-loosening double-cap bolt according to claim 1, characterized in that, It also includes a nylon baffle (6), which is detachably inserted into the anti-loosening wedge groove (5) along the axial direction of the outer nut (3) to block the anti-loosening bead (4).

3. The anti-loosening double-cap bolt according to claim 2, characterized in that, The outer nut (3) has a through hole (7), the nylon strip (6) has a screw hole (8), and also includes a screw (9). The screw (9) passes through the through hole (7) and is threaded into the screw hole (8) for positioning the nylon strip (6).

4. The anti-loosening double-cap bolt according to claim 1, characterized in that, The inner nut (2) has a tightening wedge groove (10) on its end face, and the outer nut (3) has a tightening wedge (11) on its end face. The tightening wedge (11) is used to cooperate with the tightening wedge groove (10) after the outer nut (3) and the inner nut (2) are tightened together.

5. The anti-loosening double-cap bolt according to claim 4, characterized in that, The inner wall of the tightening wedge groove (10) has a rubber lining (12).

6. The anti-loosening double-cap bolt according to claim 5, characterized in that, The sidewall of the tightening wedge (11) has anti-slip texture (13), which is used to abut against the rubber liner (12).

7. The anti-loosening double-cap bolt according to claim 1, characterized in that, The outer nut (3) has an anti-slip pad (14) on its end face, which is used to abut against the end face of the inner nut (2).

8. The anti-loosening double-cap bolt according to claim 3, characterized in that, The outer nut (3) has a countersunk hole (15) on its surface. The countersunk hole (15) is connected to the through hole (7). The countersunk hole (15) is used to accommodate the head of the screw (9).

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