A bolt permanent anti-loosening device

Abstract

This invention discloses a permanent anti-loosening device for bolts, comprising pairs or groups of screws and nuts. A screw head fixing plate is provided on the head side of multiple screws, and the screw head fixing plate has a limiting countersunk hole matching the shape of the screw head to restrict the rotation of the screw head. The shanks of multiple screws sequentially pass through the bolt hole of the fastener to be fastened and the opening of a nut anti-loosening fixing seat. The nut anti-loosening fixing seat fits against the surface of the fastener to be fastened. The screw ends extend from the front side of the nut anti-loosening fixing seat for nut tightening. A locking sleeve limiting groove is provided in the opening of the nut anti-loosening fixing seat; a locking sleeve is embedded in the locking sleeve limiting groove. The locking sleeve has an inner limiting hole and an outer limiting part. The inner limiting hole matches the outer contour of the nut to restrict the rotation of the nut, and the outer limiting part matches the inner wall of the locking sleeve limiting groove to restrict the rotation of the locking sleeve itself. This device has a simple structure, is easy to assemble, has high reliability, can achieve permanent anti-loosening, and is compatible with various bolt specifications.

Description

Technical Field

[0001] This invention relates to the field of mechanical fastener technology, and in particular to a permanent anti-loosening device for bolts. Background Technology

[0002] Bolted connections are the most widely used detachable rigid connection method in fields such as mechanical equipment, rail transportation, aerospace, construction machinery, power equipment, and building steel structures. In practical engineering applications, bolted connections are subjected to complex working conditions such as alternating vibration, impact loads, high and low temperature alternation, and stress fatigue. The threaded contact surfaces are prone to micro-slippage, preload decay, and material creep, causing relative rotation between the bolt and nut, leading to loosening or even failure of the connection. Loose bolts not only cause abnormal noises in equipment operation, decreased structural accuracy, accelerated component wear, and shortened service life, but in severe cases, they can also lead to component detachment, equipment failure, production line shutdown, and even major safety accidents and economic losses. Therefore, the reliability and durability of bolted connections in preventing loosening are core key indicators for ensuring the safe and stable operation of various industrial equipment.

[0003] Currently, the mainstream bolt anti-loosening technologies in the industry are mainly divided into three categories: 1. Friction-based anti-loosening: represented by spring washers, double nuts, self-locking threads, and elastic washers, relying on the friction between the threaded pair and the contact surface to counteract vibration and slippage. The anti-loosening effect of this type of technology is highly dependent on the assembly preload. Under long-term vibration, stress fatigue, and temperature changes, the coefficient of friction is easily attenuated, and the elastic component is prone to fatigue failure, leading to a gradual loss of preload and a significant decrease in anti-loosening performance. It is only suitable for light loads or static conditions and has poor long-term stability. 2. Mechanical anti-loosening: mainly composed of cotter pins, locking washers, and locking plates, which physically limit the rotation of the threads. Compared to friction-based anti-loosening, its reliability is improved, but it suffers from problems such as cumbersome assembly, poor adaptability, and high requirements for installation accuracy. Furthermore, the limiting structure has a fitting gap, making it prone to deformation, wear, or detachment under high-frequency vibration and heavy-load impact conditions. This type of structure only achieves anti-loosening limiting and cannot completely lock the threaded pair; loosening failure will still occur after long-term service. Moreover, the structure is easily damaged after disassembly and cannot be reused, lacking permanent anti-loosening properties. 3. Adhesive-based anti-loosening: This method uses thread-locking adhesive to fill the thread gap and achieve anti-loosening, offering advantages such as simple operation and strong adaptability. However, the adhesive curing effect is greatly affected by ambient temperature, construction process, and thread cleanliness; it is prone to brittleness at low temperatures and softening failure at high temperatures. The adhesive layer is also prone to aging and detachment under long-term vibration and shear forces, resulting in a limited anti-loosening lifespan. Additionally, adhesive connections are difficult to disassemble and repair, leading to high maintenance costs and failing to meet the anti-loosening requirements of long-term equipment service.

[0004] In summary, existing conventional anti-loosening structures generally suffer from technical shortcomings such as weak vibration resistance, poor temperature resistance, susceptibility to fatigue failure, limited service life, and inability to permanently lock, making them unsuitable for harsh working conditions such as heavy loads, high-frequency vibrations, and long-term continuous service. Therefore, the industry urgently needs an anti-loosening device that is simple in structure, easy to assemble, highly reliable, can achieve permanent anti-loosening, and is compatible with various bolt specifications. Summary of the Invention

[0005] To solve the above-mentioned technical problems, the present invention provides a permanent anti-loosening device for bolts.

[0006] The technical solution adopted in this invention is as follows: A permanent anti-loosening device for bolts includes pairs or groups of screws and nuts. A screw head fixing plate is provided on the head side of multiple screws. The screw head fixing plate has a limiting countersunk hole that matches the shape of the screw head to limit the rotation of the screw head. The shanks of multiple screws pass sequentially through the bolt hole of the fastener to be fastened and the opening of a nut anti-loosening fixing seat. The nut anti-loosening fixing seat fits against the surface of the fastener to be fastened. The screw ends extend from the front side of the nut anti-loosening fixing seat for nut fastening. A locking sleeve limiting groove is provided in the opening of the nut anti-loosening fixing seat. A locking sleeve is embedded in the locking sleeve limiting groove. The locking sleeve has an inner limiting hole and an outer limiting part. The inner limiting hole matches the outer contour of the nut to limit the rotation of the nut. The outer limiting part matches the inner wall of the locking sleeve limiting groove to limit the rotation of the locking sleeve itself.

[0007] Furthermore, the limiting countersunk hole includes a hexagonal countersunk groove and a through hole, with the screw rod passing through the through hole and the screw head confined in the hexagonal countersunk groove.

[0008] Furthermore, the upper side of the nut anti-loosening fixing seat is provided with a limiting pin hole through the locking sleeve limiting groove, and the locking sleeve is provided with a pin limiting groove, into which a pin can be inserted to limit the axial movement of the locking sleeve.

[0009] Furthermore, symmetrical limit pin holes are provided on the left and right sides of the locking sleeve limiting groove, and U-shaped pins are inserted to limit and fix the locking sleeve.

[0010] Furthermore, the front of the locking sleeve is provided with multiple set screw holes.

[0011] Furthermore, a sealing plate is provided on the front side of the nut anti-loosening fixing seat, and the end of the screw passes through the through hole of the sealing plate and is threaded to the sealing nut to press and fix the sealing plate on the front side of the nut anti-loosening fixing seat.

[0012] Furthermore, the inner limiting hole is a hexagonal hole for matching the nut.

[0013] Furthermore, the outer limiting part consists of multiple limiting teeth evenly distributed along the outer periphery of the locking sleeve. Each limiting tooth extends axially and meshes with the corresponding tooth groove on the inner wall of the locking sleeve limiting groove to restrict the rotation of the locking sleeve relative to the locking sleeve limiting groove.

[0014] Furthermore, the pin limiting groove is an annular groove circumferentially formed in the middle of the locking sleeve.

[0015] Compared with the prior art, the present invention has the following advantages: 1. This invention uses a countersunk hole on the screw head fixing plate to circumferentially limit the screw head, preventing screw rotation. Simultaneously, the inner limiting hole of the locking sleeve engages with the outer contour of the nut to restrict nut rotation, and the evenly distributed limiting teeth on the outer circumference of the locking sleeve mesh with the grooves on the inner wall of the locking sleeve's limiting groove, further restricting the locking sleeve's own rotation. Through the synergistic effect of these multiple mechanical locking structures, a rigid constraint without gaps is formed between the screw and nut, fundamentally eliminating the possibility of relative rotation of the threaded pair, achieving true permanent anti-loosening, and completely solving the problem of loosening failure caused by vibration, impact, temperature changes, and other factors during long-term service using traditional anti-loosening methods.

[0016] 2. The screw and nut in the device of this invention adopt a conventional national standard bolt structure in pairs or groups. No structural modification or special processing is required for the bolt body. It has strong versatility and does not change the existing standard bolt structure. The anti-loosening function can be achieved by adding auxiliary components such as screw head fixing plate, nut anti-loosening fixing seat and locking sleeve. The structure is simple, with good versatility and interchangeability. It can be adapted to bolt connections of various standard specifications, reducing implementation costs and technical thresholds.

[0017] 3. The components of this invention are connected by detachable methods such as fitting and pin insertion, simplifying the assembly process and requiring no special tools. Axial positioning and fixing of the locking sleeve is achieved simply by inserting a pin through the engagement of the limiting pin hole and pin limiting groove, making operation convenient. Furthermore, the overall structure does not employ irreversible connection methods such as adhesive bonding; when disassembly and maintenance are required, the locking state can be released simply by removing the pin. All components are reusable, significantly reducing subsequent maintenance costs.

[0018] 4. The present invention provides a sealing plate on the front side of the nut anti-loosening fixing seat, and presses and fixes the sealing plate by the sealing nut, forming a closed protection for the nut and threaded connection, effectively isolating external moisture, dust and corrosive media, preventing the nut and threads from being unable to be disassembled later due to rust, and significantly improving the adaptability and service life of the device in harsh working environments such as humidity, salt spray and dust.

[0019] 5. This invention abandons the reliance of traditional friction-based anti-loosening methods on pre-tightening force and friction coefficient, and adopts a rigid mechanical locking principle. The locking structure is not affected by vibration frequency, load size and temperature changes. It has strong vibration resistance, good temperature resistance and is not prone to fatigue failure. It is particularly suitable for harsh working conditions such as heavy load, high frequency vibration and long-term continuous service in rail transit, aerospace, engineering machinery, power equipment and other industries where the reliability of anti-loosening is extremely high. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the structure of the present invention with the sealing plate removed; Figure 3 This is an exploded view of the present invention; Figure 4 This is a schematic diagram of the screw head fixing plate of the present invention; Figure 5 This is a schematic diagram of the structure of the nut anti-loosening fixing seat of the present invention; Figure 6 This is a front view of the locking sleeve of the present invention; Figure 7 This is a side view of the locking sleeve of the present invention.

[0021] In the diagram: 1. Screw; 2. Screw head fixing plate; 3. Nut anti-loosening fixing seat; 31. Locking sleeve limiting groove; 4. Nut; 5. Locking sleeve; 51. Inner limiting hole; 52. Outer limiting part; 53. Set screw hole; 54. Annular groove; 6. Sealing plate; 7. Sealing nut; 8. U-pin; 9. First fixing plate; 10. Second fixing plate. Detailed Implementation

[0022] To better understand the purpose, structure, and function of this invention, a permanent anti-loosening device for bolts according to this invention will be described in further detail below with reference to the accompanying drawings.

[0023] like Figures 1-3 As shown, a permanent anti-loosening device for bolts is used to achieve the anti-loosening function of paired or grouped bolts. It includes paired or grouped screws 1 and nuts 4. A screw head fixing plate 2 is provided on the head side of multiple screws 1. The screw head fixing plate 2 has a limiting countersunk hole matching the shape of the screw head to limit the rotation of the screw head. The shanks of multiple screws 1 pass sequentially through the bolt holes of the first fixing plate 9 and the second fixing plate 10 to be tightened, and through the opening of a nut anti-loosening fixing seat 3. The nut anti-loosening fixing seat 3 is attached to... The screw 1 extends from the front of the nut anti-loosening fixing seat 3 to be fastened to the surface of the second fixing plate 10. The nut anti-loosening fixing seat 3 has a locking sleeve limiting groove 31 in the opening. The locking sleeve limiting groove 31 is fitted with a locking sleeve 5. The locking sleeve 5 has an inner limiting hole 51 and an outer limiting part 52. The inner limiting hole 51 is matched with the outer contour of the nut 4 to limit the rotation of the nut 4. The outer limiting part 52 is matched with the inner wall of the locking sleeve limiting groove 31 to limit the rotation of the locking sleeve 5 itself.

[0024] like Figure 4 As shown, in this embodiment, the screw head fixing plate 2 is provided with a hexagonal countersunk hole or other hole of a shape that can restrict the rotation of the screw head 1, thereby limiting and fixing the hexagonal head of the screw 1 to prevent the screw 1 from rotating.

[0025] After the hexagonal head of the screw 1 is limited and fixed by the screw head fixing plate 2, the screw 1 passes through the bolt holes of the first fixing plate 9 and the second fixing plate 10, and then the nut anti-loosening fixing seat 3 is installed. Then the nut 4 is tightened. After the nut 4 reaches the pre-tightening torque, the locking sleeve 5 is put on the nut 4 and the nut anti-loosening fixing seat 3. At this time, the nut 4 of the bolt will be locked by the locking sleeve 5 and the nut anti-loosening fixing seat 3, and no more rotational displacement will occur.

[0026] like Figures 5-7 As shown, in this embodiment, a recessed gear groove is constructed on the nut anti-loosening fixing seat 3, and the outer limiting part of the locking sleeve 5 is a limiting tooth that can be engaged with it. On the upper side of the nut anti-loosening fixing seat 3, on the left and right sides of the locking sleeve limiting groove 31, there are symmetrical through holes for installing U-shaped pins 8 as limiting pin holes. A rectangular slot is constructed in the middle of the locking sleeve 5. Specifically, the pin limiting groove is an annular groove 54 circumferentially opened in the middle of the locking sleeve 5. This allows the locking sleeve 5 to be limited by the U-shaped pin 8 after it is installed in the nut anti-loosening fixing seat 3, preventing the locking sleeve 5 from coming off due to vibration or other reasons.

[0027] The locking sleeve 5 has a set screw hole 53 on the front. When it is necessary to remove the bolt, the set screw can be used to push the locking sleeve 5 out through the set screw hole 53, so that the nut 4 can be easily installed and removed.

[0028] A sealing plate 6 is installed on the outside of the nut anti-loosening fixing seat 3. The end of the screw 1 passes through the through hole of the sealing plate 6 and is threaded to the sealing nut 7. The sealing plate 6 protects the nut 4 and the locking sleeve 5, which are mainly subjected to force inside. At the same time, relevant anti-rust grease can be applied to the gap between the locking sleeve 5 and the sealing plate 6 to effectively prevent rust.

[0029] It is understood that the present invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. Furthermore, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present invention.

Claims

1. A permanent anti-loosening device for bolts, characterized in that, Includes a pair or group of screws (1) and nuts (4). A screw head fixing plate (2) is provided on the head side of multiple screws (1). The screw head fixing plate (2) has a limiting countersunk hole that matches the shape of the screw head (1) to limit the rotation of the screw head (1). The shanks of multiple screws (1) pass through the bolt hole of the fastener to be fastened and the opening of a nut anti-loosening fixing seat (3) in sequence. The nut anti-loosening fixing seat (3) fits against the surface of the fastener to be fastened. The end of the screw (1) exits from the nut anti-loosening fixing seat (4). 3) The front side extends out to allow the nut (4) to be tightened. The opening of the nut anti-loosening fixing seat (3) is provided with a locking sleeve limiting groove (31). The locking sleeve limiting groove (31) is fitted with a locking sleeve (5). The locking sleeve (5) has an inner limiting hole (51) and an outer limiting part (52). The inner limiting hole (51) cooperates with the outer contour of the nut (4) to limit the rotation of the nut (4). The outer limiting part (52) cooperates with the inner wall of the locking sleeve limiting groove (31) to limit the rotation of the locking sleeve (5) itself.

2. The permanent anti-loosening device for bolts according to claim 1, characterized in that, The limiting countersunk hole includes a hexagonal countersunk groove and a through hole. The screw (1) rod is inserted into the through hole, and the screw head is restricted in the hexagonal countersunk groove.

3. The permanent anti-loosening device for bolts according to claim 1, characterized in that, The upper side of the nut anti-loosening fixing seat (3) has a limiting pin hole through the locking sleeve limiting groove (31), and the locking sleeve (5) has a pin limiting groove, into which a pin can be inserted to limit the axial movement of the locking sleeve (5).

4. The permanent anti-loosening device for bolts according to claim 3, characterized in that, The locking sleeve limiting groove (31) has symmetrical limiting pin holes on the left and right sides, and U-shaped pins (8) are inserted to limit and fix the locking sleeve (5).

5. The permanent anti-loosening device for bolts according to claim 1, characterized in that, The locking sleeve (5) has multiple set screw holes (53) on its front side.

6. The permanent anti-loosening device for bolts according to claim 1, characterized in that, A sealing plate (6) is provided on the front side of the nut anti-loosening fixing seat (3). The end of the screw (1) passes through the through hole of the sealing plate (6) and is threaded to the sealing nut (7) so as to press and fix the sealing plate (6) on the front side of the nut anti-loosening fixing seat (3).

7. The permanent anti-loosening device for bolts according to claim 1, characterized in that, The inner limiting hole (51) is a hexagonal hole for matching nut (4).

8. The permanent anti-loosening device for bolts according to claim 1, characterized in that, The outer limiting part (52) consists of multiple limiting teeth evenly distributed along the outer periphery of the locking sleeve (5). Each limiting tooth extends axially and meshes with the corresponding tooth groove on the inner wall of the locking sleeve limiting groove (31) to restrict the rotation of the locking sleeve (5) relative to the locking sleeve limiting groove (31).

9. The permanent anti-loosening device for bolts according to any one of claims 1 to 8, characterized in that, The pin limiting groove is an annular groove (54) circumferentially opened in the middle of the locking sleeve (5).

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