A type of anti-loosening nut

Abstract

This invention discloses an anti-loosening nut, comprising an integral nut body and a cap ring. A spring is freely placed inside the cap ring, with the spring's helix direction aligned with the thread direction, and it is not fixedly connected to the nut body or cap ring. The inner wall of the cap ring is machined with raised ridges. When these ridges apply a tangential force along the thread direction to the upper protrusion of the spring, the nut can be easily installed. If a tangential force against the thread direction is applied to the lower protrusion of the spring, the nut can be removed. When the raised ridge contacts the upper protrusion, the elastic contact angle of the lower protrusion is no greater than 9°. To facilitate installation and prevent the spring from falling off, a ring cap is provided on the cap ring. Alternatively, a groove can be machined on the inner wall of the cap ring to replace the raised ridge, with the two protrusions of the spring placed within the groove. This invention offers good anti-loosening performance, is reusable, has a simple structure, a short production process, and a competitive price advantage.

Description

Technical Field

[0001] This invention applies to the fastener industry and relates to fastening nuts, particularly a nut with anti-loosening function. Background Technology

[0002] There are many methods for preventing fasteners from loosening, with numerous inventions focusing on bolts, nuts, or integrated anti-loosening mechanisms. Regarding nuts, CN2692401Y discloses a spring-loaded anti-loosening nut, which has a crescent-shaped groove machined on the internal thread of the nut, within which a spring and ball bearings are placed, using the ball bearings to prevent loosening. CN2851697Y discloses an anti-loosening and anti-dislodging nut, whose principle is the same as the aforementioned patents, consisting of a nut body and an outer sleeve, except that the blind hole for placing the spring and ball bearings is machined on the outer cylindrical surface of the nut body. CN2918843Y discloses an anti-loosening and anti-theft one-way bolt and nut, utilizing the fact that the bolt and nut can only rotate in one direction to achieve anti-loosening and anti-theft measures.

[0003] CN203641238U discloses an anti-loosening and anti-theft nut. An elastic threaded sleeve is placed inside the cavity of the body. One end of the elastic threaded sleeve is fixedly connected to the body, and the other end is clearance-fitted with the body. The elastic threaded sleeve engages with the external thread of the fastener, causing elastic retraction and generating axial force. This creates significant pressure between the internal thread of the elastic threaded sleeve and the external thread of the fastener, resulting in substantial friction and preventing easy slippage, thus providing excellent anti-theft protection. Its biggest drawback also lies in this elastic force. Because of this anti-theft effect, the nut cannot be easily installed, failing to meet usage requirements. If installation can be achieved with high torque, removal can also be achieved with high torque, since the friction is the same. In other words, if the spring elasticity and the friction generated by the external thread engagement are equal, installation is possible, but the anti-theft function is not achieved; conversely, if the nut can be anti-theft, installation is impossible. CN113217518A discloses an anti-loosening nut and its processing method. A spring body is installed in a countersunk hole in the nut body, and the outer ring of the spring body is fixedly connected to the end face of the nut body. The countersunk hole in the nut body is welded to the spring assembly. This patent uses a welded connection to replace the spring retainer, which has high requirements for fit with the nut body, solving the problems of inaccurate spring positioning and retainer deformation interference caused by tolerances. Although this patent solves the installation problems of the aforementioned patents, the presence of the welding process significantly increases the production cost of the product. Summary of the Invention

[0004] The technical problem solved by this invention is to provide an anti-loosening nut that uses the elastic force of a spring to fix it in the external thread to achieve anti-loosening. It has a simple structure, short production process, low production cost, and is easy to install.

[0005] The technical solution adopted in this invention is as follows: a lock nut, comprising an integral nut body and a cap ring, wherein a spring is placed inside the cap ring, and the helical direction of the spring is consistent with the helical direction of the internal thread of the nut body. The spring is freely placed and is not fixedly connected to the nut body or the cap ring. The inner diameter of the spring is not greater than the outer diameter of the mating external thread. The spring has two protrusions at its upper and lower ends, the upper end being an upper protrusion and the lower end being a lower protrusion. A raised ridge is machined on the inner wall of the cap ring, and the raised ridge mates with the two protrusions of the spring, applying a tangential force to the two protrusions. When the nut is installed, the raised ridge contacts the upper protrusion; when the nut is loosened, the raised ridge contacts the lower protrusion. After the lock nut is installed, the elastic contact angle between the lower protrusion and the raised ridge is not greater than 9°, and the elastic contact angle is the angle at which the raised ridge contacts the lower protrusion when the nut is loosened. A ring cap is provided on the cap ring, and the inner diameter of the ring cap is smaller than the outer diameter of the spring. An installation opening can be designed on the ring cap, and the installation opening is preferably located above the raised ridge to facilitate cold deformation processing.

[0006] Furthermore, the spring wire has a circular cross-section with 1-3 turns, and the protruding ridges are 2-6 evenly distributed, cooperating with the spring.

[0007] Furthermore, to increase the friction between the spring and the external thread, the spring cross-section is trapezoidal or triangular, the number of spring coils is less than one, and there are one or two protruding ridges.

[0008] Furthermore, the protruding ridge is replaced by a groove, and the protruding ridge and the groove are opposite each other. The two protruding heads of the spring are placed in the groove, which is equivalent to placing them between the protruding ridges.

[0009] The beneficial effects of this invention are: it has good anti-loosening effect, simple structure, short production process, no need for special equipment, low production cost, and competitive price advantage. The spring and external thread have a wide range of applications, do not require special tools, are easy to install, and are reusable. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of the structure of Example 1. Figure 2 AA section view;

[0011] Figure 2 for Figure 1 Top view;

[0012] Figure 3 This is a schematic diagram of the installation in Example 1. Figure 4 BB cross-sectional view;

[0013] Figure 4 for Figure 3 Top view;

[0014] Figure 5 This is a schematic diagram illustrating an incorrect spring mounting position in Example 1.

[0015] Figure 6 This is a top view of the structure of Example 2;

[0016] Figure 7 This is a schematic diagram illustrating an incorrect spring installation position in Example 2;

[0017] Figure 8 This is a top view of Example 3;

[0018] Figure 9 This is a schematic diagram of the structure of Example 4. Figure 10 CC section view;

[0019] Figure 10 for Figure 9 Top view;

[0020] Figure 11 This is a schematic diagram of the installation process in Example 4;

[0021] Figure 12 This is a schematic diagram of the structure of Example 5;

[0022] Figure 13 for Figure 12 Top view;

[0023] Figure 14 This is a schematic diagram of the installation process in Example 5;

[0024] Figure 15 This is a schematic diagram of the structure of Example 6. Figure 16 DD sectional view;

[0025] Figure 16 for Figure 15 Top view;

[0026] Figure 17 This is a schematic diagram of the installation process in Example 6;

[0027] Figure 18 Schematic diagrams of different cross-sections of the spring in Example 6;

[0028] In the attached diagram: 1-nut body, 2-cap ring, 3-spring, 4-screw;

[0029] 21-Protruding ridge, 22-Ring cap, 23-Mounting port;

[0030] 31 - Upper convex head, 32 - Lower convex head. Detailed Implementation Example 1

[0031] The anti-loosening nut structure in this embodiment is as shown in the attached figure. Figure 1 and attached Figure 2As shown, the device includes a nut body 1, a cap ring 2, and a spring 3. The nut body 1 and cap ring 2 are an integral structure. The spring 3 is freely placed inside the cap ring 2 and is not fixedly connected to either the nut body 1 or the cap ring 2. The helix direction of the spring 3 is consistent with the helix direction of the internal thread of the nut body, that is, consistent with the helix direction of the external thread of the screw being installed. (See attached diagram.) Figure 2 In this design, right-hand rotation (clockwise) is for tightening the nut, and left-hand rotation (counter-clockwise) is for loosening it; therefore, spring 3 is a right-hand spring. At both ends of the spring wire, two protruding heads protrude from the outer circumference of the spring. The upper protrusion is called upper protrusion 31, and the lower protrusion is called lower protrusion 32. In this embodiment, the angle between the two protrusions is 90°, and the number of spring coils is 1.25 or 2.25. The attached diagram is based on 1.25 coils. The nut body 1 is a standard hexagonal nut, and the cap ring 2 is located at the upper end of the nut body. The two are integrally formed, cold-forged or hot-forged together. When the nut body 1 rotates, the cap ring 2 rotates simultaneously. On the inner wall of the cap ring 2, protruding ridges 21 are machined. In this embodiment, the protruding ridges are evenly distributed in a hexagonal pattern, and the protruding ridges 21 mate with the two protruding heads of the spring.

[0032] The included angle between the upper and lower convex heads is 90°, and the included angle between two adjacent convex ridges is 60°. Therefore, there can be one or two convex ridges between two convex heads. When there is one convex ridge between the upper and lower convex heads, as shown in the attached figure... Figure 2 As shown, when the nut body is turned clockwise, the convex edge X first contacts the upper convex head of the spring. At this time, the rotation angle δ between the lower convex head and the convex edge Y is the static contact angle, that is, when the spring is not under force, the nut body can contact the lower convex head when rotated counterclockwise by an angle δ. When the nut and screw are installed, after the convex edge X contacts the upper convex head of the spring, the spring rotates clockwise simultaneously with the nut body inside the cap ring. When the screw 4 moves upward into the cap ring, the upper end of the screw 4 will push against the spring and move upward. At this time, the spring is compressed, keeping it inside the cap ring, and the spring cannot move upward. The screw continues to move upward, causing the spring wire at the lower part of the spring to enter the external thread of the screw. Subsequently, the spring wire gradually enters the external thread according to the guide of the external thread as the nut body rotates clockwise, as shown in the attached figure. Figure 3 As shown. Once the spring wire enters the external thread, the frictional resistance generated between the spring and the external thread will impede the rotation of the cap ring and the nut body. (See attached image.) Figure 4 As shown, the tangential force exerted by the convex ridge X on the upper convex head of the spring causes the spring to open outward, that is, to deform in the direction of increasing inner radial direction. The spring partially disengages from the external thread, thereby reducing the contact area with the external thread and reducing friction. Since the lower convex head is a free end, when the frictional force is less than the force on the upper convex head, the spring can continue to rotate clockwise with the nut body, achieving the installation of the anti-loosening nut. When there are two convex ridges between the upper and lower convex heads, as shown in the attached diagram... Figure 5As shown, when the nut body rotates clockwise, the convex ridge X first contacts the lower convex head. The tangential force on the lower convex head causes the spring to deform in the direction of decreasing inner diameter, i.e., locking deformation, which increases the friction between the spring and the external thread, making it impossible to install the nut.

[0033] The total number of spring coils is 1.25 or 2.25. There are no special requirements for the spring pitch; the spring's inner diameter only needs to be large enough to fit into the external thread. Because the spring wire has a circular cross-section, when the spring contacts the external thread, the circle acts as an arc angle. Under pressure, the spring wire automatically slides into the external thread. Then, the tangential force exerted by the convex ridge on the upper convex head guides the spring gradually into the external thread. Even if the spring pitch is zero, or the spring's inner diameter is smaller than the root diameter of the external thread, the spring can still fit into the external thread. As long as the spring's inner diameter is not greater than the screw's outer diameter (i.e., the spring's inner diameter is not greater than the outer diameter of the external thread), meaning that as long as there is elastic friction between the spring and the external thread, it can be used. The size requirements for the spring are not high.

[0034] Taking an M16 nut as an example, the spring wire diameter is 1.4mm, and the spring's inner diameter matches the nut's inner diameter, which is 13.84mm. When the lower convex head drives the spring into the external thread, the spring's outer diameter gradually increases, resulting in elastic deformation. This elastic deformation creates friction between the spring wire and the external thread of the screw. After the spring enters the external thread, its inner diameter increases from 13.84mm to 14.6mm. During this increase in inner diameter, the contact angle also changes, increasing from 7-8° in the static state to 8-9° in the elastic state. Figure 2 The static contact angle δ variation shown is as follows: Figure 4 The elastic contact angle shown is δ1. This elastic contact angle is the angle at which the upper convex head contacts the convex ridge X when the spring is in an elastic state within the external thread, and the convex ridge Y rotates counterclockwise to contact the lower convex head. In other words, after the lock nut is installed, the nut body rotates, and the convex ridge contacts the lower convex head at that rotation angle. After the spring is installed on the external thread, angle δ1 is greater than δ. This is because the diameter and length of the spring wire remain unchanged, but the inner diameter of the spring increases, increasing the arc distance between the convex ridge Y and the lower convex head, thus increasing angle δ1. The larger the change in the inner diameter of the spring when it transitions from a static to an elastic state, or the greater the number of spring coils, the greater the difference between angle δ1 and angle δ. To reduce the difference between the two angles and the frictional force of the installed nut, the number of spring coils should not exceed 3. It should be noted that the anti-loosening frictional force between the spring and the external thread is the frictional force that the installed nut needs to overcome. The greater this frictional force, the better the anti-loosening effect, but the greater the installation torque of the nut, making installation more difficult.

[0035] After the spring is installed on the external thread, its elastic force and the friction between the spring and the external thread keep it fixed inside the thread. If it is necessary to unscrew the nut, see attached... Figure 4As shown, a large torque is required to rotate the nut body counterclockwise by an angle δ1, i.e., the elastic contact angle. At this time, the convex ridge X, which mounts the nut on the upper convex head, rotates away from the upper convex head, and the adjacent convex ridge Y, in the counterclockwise direction, contacts the lower convex head below the spring. Since the spring is fixed to the external thread by friction, the tangential force on the lower convex head must overcome this friction to loosen it, causing the spring to rotate counterclockwise around the external thread. Normally, the tangential force on the lower convex head causes the spring to open outwards, reducing the contact area and friction between the spring and the screw's external thread. The upper convex head is the free end; when the friction is less than the force on the lower convex head, the nut can be unscrewed from the screw and reused.

[0036] The anti-loosening principle of this embodiment is as follows: the friction between the spring and the external thread keeps the spring fixed inside the external thread, thus preventing the nut from loosening. After the convex edge contacts the lower convex head, if the nut loosens, it needs to overcome this frictional force. Within the elastic contact angle δ1, the elastic deformation of the thread is used to prevent loosening, that is, the elastic preload of the nut and the screw is used to prevent loosening. Therefore, the smaller the elastic contact angle δ1, the better the anti-loosening effect. In principle, the elastic contact angle δ1 should be controlled within 9°. In other words, after the torque is greater than the spring friction, the nut tightening rotation angle should not be less than 9°. The static contact angle δ is used to install the spring inside the cap ring. The larger the angle, the easier the spring installation. However, the static contact angle δ is less than δ1, so δ should not be greater than 9°. Ideally, δ should be 0°. Therefore, a comprehensive design of δ angle, spring coils, and spring inner diameter is needed to control the elastic contact angle δ1. Example 2

[0037] This embodiment is similar in structure to Embodiment 1, the difference being the number and position of the spring coils. In Embodiment 1, the spring has 1.25 or 2.25 coils, while in this embodiment, the spring has 1.75 or 2.75 coils. The two protruding heads remain perpendicular, as shown in the attached figure. Figure 6As shown, there are two protruding ribs 21 between the two protruding heads at 90°. When installed by clockwise rotation, the tangential force applied by the rib X to the upper protruding head causes the spring to rotate clockwise simultaneously with the nut body within the cap ring. When the screw moves upward into the cap ring, the upper end of the screw pushes against the spring as it moves upward. At this point, the spring is compressed, keeping it within the cap ring and preventing it from moving upward. The continued upward movement of the screw causes the lower protruding head of the spring to enter the external thread of the screw. Subsequently, the spring wire rotates clockwise with the nut body, gradually entering the external thread guided by the external thread. The friction of the spring gradually increases, and the tangential force applied by the rib X to the upper protruding head causes the spring to open, reducing the friction between it and the external thread. The lower protruding head is the free end. When the friction is less than the force on the upper protruding head, the spring can continue to be screwed clockwise into the external thread of the screw body, thus achieving the installation of the anti-loosening nut. When rotated counterclockwise, the convex ridge Y first contacts the lower convex head at the bottom of the spring. The tangential force on the lower convex head causes the spring to open, reducing the friction between it and the external thread. The upper convex head is the free end. When the friction is less than the force on the lower convex head, the nut can be screwed counterclockwise to unscrew the external thread of the screw. If a convex ridge is provided between the two convex heads, as shown in the attached diagram... Figure 7 As shown. When the nut body is rotated clockwise to install the nut, the convex edge first contacts the lower convex head, causing the spring to undergo locking deformation, increasing the friction between the spring and the external thread, making the nut difficult or impossible to install.

[0038] This embodiment conveys the same meaning as Embodiment 1, and the anti-loosening principle is the same. For the M16 nut, with the spring having the same dimensions as in Embodiment 1, the elastic contact angle δ1 increases by less than 1° due to the increase of half a turn in the spring coil. Although the friction of the spring increases the anti-loosening effect, the increased elastic contact angle weakens the anti-loosening effect within the elastic contact angle. Therefore, the δ angle is reduced, and the δ1 angle is controlled to not exceed 9°. Example 3

[0039] This embodiment is shown in the appendix. Figure 8 As shown. Four convex ridges are evenly distributed on the inner surface of the cap ring. When the upper convex head of the spring contacts the convex ridge, the static contact angle between the lower convex head and the convex ridge is δ. (From the attached...) Figure 8It can be seen that, with a fixed position of the upper convex head, the mating positions with the same static contact angle δ between the lower convex head and the convex ridges are consistent with the number of convex ridges, which is also four. This allows the position of the lower convex head to be adjusted using the position of the convex ridges, resulting in different numbers of spring coils, thereby adjusting the contact area between the spring and the external thread, and thus adjusting the friction or anti-loosening torque. In other words, with the same spring inner diameter, spring wire cross-sectional diameter, and elasticity, the friction with the external thread can be adjusted within a small range by adjusting the position of the lower convex head to meet the requirements of the anti-loosening torque. The more convex ridges there are, the smaller the adjustment angle, and the smaller and more precise the range of friction adjustment. However, it is not recommended to have a large number of convex ridges. If the upper convex head deforms under the action of the convex ridges, causing the cap ring to rotate, while the spring does not rotate (i.e., the spring has already unfolded and deformed), the friction is still greater than the force on the upper convex head. In this case, if the convex ridge contacts the lower convex head, and the tangential force exerted by the convex ridge on the lower convex head does not cause the spring to rotate, the force on the lower convex head will cause the spring to lock, increasing the friction between the spring and the external thread, making it impossible to install the nut. Therefore, in order to balance the contradiction between installation and adjustment of friction, the number of protrusions should not be too many. This invention selects 2-6 evenly distributed protrusions. Example 4

[0040] In the above embodiments, when installing the nut, the spring needs to be compressed to prevent it from moving upwards and sliding into the external thread of the screw. Additionally, in embodiments 1 and 2, the angle between the upper and lower protrusions of the spring has a positional relationship with the convex ridge in the cap ring. When rotating clockwise, if the lower protrusion contacts the convex ridge first, the spring will lock, preventing the nut from being installed. This can cause unnecessary difficulties in nut installation, requiring careful attention to the positional relationship between the spring protrusion and the convex ridge; otherwise, reinstallation may be necessary.

[0041] To facilitate installation, this embodiment adds a ring cover 22 to the above embodiment, as shown in the attached figure. Figure 9 and attached Figure 10As shown. A cap 22 is designed on the top of the cap ring 2. The inner diameter of the cap is smaller than the outer diameter of the spring 3. This serves three purposes: first, it prevents the spring from detaching from the cap ring, facilitating packaging, transportation, and storage; second, it applies pressure to the spring, facilitating its insertion into the external thread of the screw, achieving a fit with the external thread; and third, it ensures accurate spring positioning. The cap is formed by mechanized cold forging or cold bending, so that the upper part of the cold-deformed cap ring becomes the cap while the spring is accurately placed inside. Thus, the placement of the spring and the pressing of the cap are completed in one process, resulting in a short production flow, low cost, and no waste. A notch on the cap forms an installation port 23. Through this port, it is possible to check whether the spring is placed inside the cap ring and whether the upper protrusion is in the correct position. If the spring is not placed inside the cap ring, it can be inserted through this installation port. If the upper protrusion is in the wrong position, it can be adjusted through this installation port, or the cap can be pried open to remove the spring, its position adjusted, and the cap pressed back down. To facilitate the deformation processing of the cap, the installation port is designed above the protruding ridge.

[0042] To ensure the cap can apply installation pressure to the spring, the inner diameter of the cap is smaller than the outer diameter of the spring. When the inner diameter of the cap is roughly the same as the inner diameter of the spring, the inner diameter of the cap is smaller than the outer diameter of the screw. After the nut is installed, the screw will push the cap open, as shown in the attached figure. Figure 11 As shown. The presence of the mounting opening facilitates deformation of the ring cap when the screw is pushed out during nut installation. For repeated use, if the ring cap springs back to its original position and provides spring pressure, it can be used directly. If the ring cap undergoes plastic deformation, it can be repaired and reused. Even if the ring cap is deformed and damaged, it becomes an embodiment without a ring cap and can still be used. Example 5

[0043] To reduce the elastic contact angle δ1, the inner diameter of the spring can be increased. This allows for an increase in the inner diameter of the ring cap, as shown in the attached figure. Figure 12 and attached Figure 13 As shown, when the inner diameter of the ring cap is larger than the outer diameter of the external thread, the ring cap can be a single piece, eliminating the need for an mounting opening. It can be cold-formed on the equipment in one step, enclosing the spring beneath the ring cap. The screw installation does not interfere with the ring cap, and the ring cap does not deform. (See attached diagram.) Figure 14 As shown. After the nut is tightened to high torque, it can be reused directly.

[0044] The biggest difference between this embodiment and the previous embodiment is that after the spring is installed on the external thread, the ring cap still maintains pressure on the spring. This pressure causes friction between the ring cap and the top of the spring, which increases the anti-loosening effect of the anti-loosening nut within the elastic contact angle range. Even if the nut is tightened for a long time and the prestress of the screw gradually disappears, this friction can still maintain the anti-loosening effect of the nut. Example 6

[0045] The biggest difference between this embodiment and the previous embodiment lies in the cross-sectional shape of the spring. (See attached...) Figure 15 As shown, the spring cross-section is a combination of trapezoidal and semi-circular shapes. The inner diameter side is a trapezoid that matches the shape and size of the external thread, while the outer diameter side is semi-circular. The nut, after installation, will appear as shown in the attached diagram. Figure 17 As shown in the attached figure. In the above embodiment, the spring cross-section is circular, which facilitates entry into the external thread. However, the contact between the spring and the external thread line results in relatively low anti-loosening friction, requiring an increase in the number of turns to increase friction. But increasing the number of turns increases the elastic contact angle δ1, which actually reduces the anti-loosening effect. This embodiment uses a trapezoidal cross-section to mate with the external thread surface, increasing the contact area and friction, as shown in the attached figure. Figure 16 As shown, a spring with less than one full turn can be used. In this embodiment, only one ridge is machined on the inner wall of the cap ring, and the ridge is arranged between the upper and lower convex heads. When the inner diameter of the spring changes slightly, the static contact angle δ and the elastic contact angle δ1 do not change much. This increases the static contact angle δ and facilitates the installation of the spring.

[0046] The spring's outer diameter cross-section is semi-circular, solely to increase the spring's outer diameter so that the inner diameter of the ring cap is smaller than this outer diameter. The ring cap is cold-forged in one step, its inner diameter being larger than the screw's outer diameter, while simultaneously sealing the spring. Although the spring cross-section in this embodiment is not as easily inserted into the external thread as a circular cross-section, the spring in this embodiment has less than one turn, and the pressure on the top surface of the spring can directly press the spring into the external thread without requiring the elastic force transmission of the spring wire. If the ring cap has the structure of Embodiment 4, the spring's cross-section can be directly made trapezoidal. The aforementioned trapezoidal spring is only for increasing friction. Typically, the shape and size of the screw's external thread deviate; to ensure the spring can adapt to more external threads, the spring's cross-section can be made triangular, utilizing the elastic deformation of the spring and the external thread to achieve surface contact, as shown in the attached figure. Figure 18 As shown on the left. If the trapezoidal cross-sectional dimensions are increased, the ring cap can compress the spring, or the spring wire cross-section can be directly made into a trapezoidal shape, as shown in the attached diagram. Figure 18 As shown on the right.

[0047] This embodiment can further reduce the length of the spring by designing two protruding ridges, one of which mates with the upper protrusion and the other with the lower protrusion. Because this embodiment uses surface contact, the friction is high, resulting in greater spring anti-loosening resistance. Furthermore, since the spring is less than one turn, the elastic contact angle δ1 can be reduced to a minimum, consistent with the δ angle, thus improving the thread's elastic anti-loosening effect.

[0048] The above embodiments are all described with the nut being right-handed as the tightening direction, that is, both the spring and the thread are right-handed. If the nut and the screw are left-handed, the spring will be changed to left-handed accordingly, and the position relationship of the protrusions and the contact angle in the above embodiments will be adjusted accordingly.

[0049] The above embodiment uses a protruding ridge as an example for structural description. Alternatively, a groove can be machined on the inner wall of the cap ring. The protruding ridge and the groove are mutually related. In the above embodiment, the protruding ridge on the inner wall of the cap ring is equivalent to increasing the width of the groove (the circumferential dimension of the cap ring). Increasing the width of the protruding ridge (the circumferential dimension of the cap ring) is equivalent to machining a groove on the inner wall of the cap ring. After replacing the protruding ridge with a groove, the upper and lower protruding heads of the spring are placed inside the groove, which is equivalent to placing the protruding heads between the protruding ridges in the above embodiment.

[0050] This invention has a simple structure. The production process of Examples 1-3 is the same as that of ordinary nuts, with only two steps: forming and thread processing. In other words, the equipment used to produce ordinary nuts can also produce the anti-loosening nuts of this invention, requiring only mold modification without the need for additional or altered equipment. Compared to anti-loosening nuts on the market, this invention has a lower production cost and a significant competitive advantage in market price. However, when installing the nut, a spring and a compression spring are required. Examples 4 and 5 can use a nut-locking device utilizing rubber rings, completing the spring placement and compression ring cover operation in one step, solving the problem of spring placement and compression operations in Examples 1-3. This invention utilizes the tangential deformation of the spring, making installation and disassembly convenient.

[0051] The applicant prepared two M16 nut samples according to Example 5. The inner diameter of the spring was the same as the root diameter of the external thread, the wire diameter was 1.4mm, the contact angle δ was 7-8°, and the number of spring coils was 1.25. Vibration anti-loosening tests were conducted by a testing technology company in Hunan Province. The vibration frequency was 12.5Hz, the amplitude was ±0.8mm, and the number of vibrations was 3000. The initial axial forces were 68.79KN and 67.52KN, respectively, and the residual axial forces after vibration were 62.36KN and 56.42KN, respectively. The test results were 90.65% and 82.35% (residual / initial), indicating a very good anti-loosening effect. After unscrewing and reinstalling, a second vibration anti-loosening test was conducted. The initial axial forces were 67.29KN and 66.75KN, respectively, and the residual axial forces after vibration were 51.48KN and 52.20KN, respectively. The test results were 76.5% and 78.2%, respectively, indicating a still good anti-loosening effect.

[0052] Compared with the prior art CN113217518A and CN203641238U, this invention has four key advantages: First, the spring is not fixed. This technical feature is crucial for manufacturing, as it eliminates the need for specialized tooling or welding equipment to fix the spring, reduces the production steps involved in fixing the spring, and eliminates the use of welding materials and welders. This significantly reduces production costs, especially for nuts produced in large batches. Second, by utilizing the spring's unfolding deformation, the friction between the spring and the external thread is reduced, enabling the nut to be installed and removed easily, meeting the requirements for repeated use, and without damaging the external thread. This solves the problems of the aforementioned two patented nuts being impossible or difficult to install. Third, there is no spring positioning issue. The springs in the aforementioned two patented nuts must be precisely positioned; otherwise, they cannot match the external thread of the screw. This invention does not have this problem, preventing defective products due to positioning deviations or difficulties in nut installation. Fourth, the elastic deformation of the thread and spring is used to achieve anti-loosening. Compared to anti-loosening and anti-theft nuts such as CN2343416Y, CN2388399Y, CN87205352U, and CN212899300U, this invention eliminates the need for special tools or wrenches, greatly simplifying installation. Compared to ball-bearing anti-loosening and anti-theft nuts such as CN2851697Y and CN2692401Y, it features a simpler structure, no pits, and the cap ring and nut body are formed in a single cold or hot forging process, reducing the production steps required for pitting. Compared to ordinary nuts, the material cost of the cap ring is negligible, and the material cost of the spring increases only slightly. The production process remains the same, involving cold or hot forging followed by internal thread machining. Only in embodiments 4 and 5 is a ring pressing process added. Compared to anti-loosening nuts with rubber rings, embodiments 4 and 5 have the same production process and comparable cost. However, anti-loosening nuts with rubber rings are only installed once, and the rubber ring deforms and breaks, making them disposable. This invention not only provides excellent anti-loosening performance but is also reusable, saving users money.

[0053] Patent CN113217518A constitutes the most similar conceptual solution to this invention. Compared with CN113217518A, the advantages of this invention are: 1) Shorter production process. The production process of this invention is the same as that of ordinary nuts, only forming and internal thread processing, resulting in a shorter production process. There is no fixture positioning as in CN113217518A, and no welding process. As long as the mold is changed, the equipment used for forming ordinary nuts can also produce this invention. 2) Spring advantage. The shape and size of the spring in this invention are not strictly limited, and substandard or unqualified springs can be used. In contrast, the outer ring of the spring in CN113217518A needs to be enlarged to match the dimensions of the nut end face or countersunk end face, requiring a special spring. Positioning is required during welding, and the dimensional requirements of the spring body are stricter. 3) Solves the welding problem in CN113217518A. In industrial production, spring materials are usually medium to high carbon steel with a carbon content of more than 0.5%, which has almost no welding properties. If welding springs is required, special welding materials or complex welding processes are needed, such as preheating and slow cooling. This invention eliminates welding; the spring is freely placed, reducing production costs by eliminating welding equipment, materials, and welders. It also eliminates welding quality issues, preventing defective or scrap products caused by welding. 4) Installation and Usage Advantages. This invention allows for smooth installation by simply pressing down on the spring when tightening the nut body, ensuring balanced downward force. Although the upper end of the spring body in CN113217518A is welded and fixed, when the nut is installed by the screw, the downward pressure of the upper ring and the upward force of the screw are not balanced, generating torque on the spring. This makes it difficult for the spring to enter the external thread, requiring positioning welding of the spring body. Once a positioning deviation occurs, multiple adjustments using the spring's deformation capacity are needed to allow the spring body to enter the external thread. In industrial mass production, positioning deviations are unavoidable, resulting in poor nut installation performance in CN113217518A. 5) Advantages in Adapting to External Threads. The elastomer in CN113217518A requires a good fit with the external thread; otherwise, installation will be difficult. This invention is less demanding on the size of the external thread used in the application. Even if the external thread size is not up to standard, it can still be used as long as the spring can generate friction with the thread, thus broadening its application range. In summary, this invention not only solves the inherent defects of CN113217518A, but also considers production cost (as mentioned in points 1), 2), and 3) and installation and use (as mentioned in points 4) and 5), giving it a significant and prominent competitive advantage. Low cost and ease of use are also key factors for launching new products to the market and are guarantees of market acceptance.

Claims

1. A locking nut, comprising an integral nut body (1) and a cap ring (2), wherein a spring (3) is placed inside the cap ring (2), the helical direction of the spring (3) being consistent with the helical direction of the internal thread of the nut body (1); the spring (3) is freely placed and is not fixedly connected to the nut body (1) or the cap ring (2); characterized in that: The inner diameter of the spring (3) is not greater than the outer diameter of the mating external thread. The spring (3) has two protrusions at its upper and lower ends, with the upper end being the upper protrusion (31) and the lower end being the lower protrusion (32). The inner wall of the cap ring (2) is machined with a protruding ridge (21), which mates with the two protrusions of the spring (3) and applies a tangential force to the two protrusions. When the nut is installed, the protruding ridge (21) contacts the upper protrusion (31), and when the nut is loosened, the protruding ridge (21) contacts the lower protrusion (32). 2) Contact; The cap ring (2) is provided with a ring cover (22), the inner diameter of the ring cover (22) is smaller than the outer diameter of the spring (3); After the anti-loosening nut is installed, the elastic contact angle between the lower protrusion (32) and the protrusion (21) is not greater than 9°. This elastic contact angle is the rotation angle at which the spring (3) is in an elastic state in the external thread, and when the upper protrusion (31) contacts the protrusion (21), the nut is loosened by rotating in the opposite direction, and the protrusion (21) contacts the lower protrusion (32).

2. The anti-loosening nut according to claim 1, characterized in that: The ring cover (22) is designed with an installation port (23), which is located above the protruding ridge (21).

3. The anti-loosening nut according to claim 1, characterized in that: The spring (3) has a circular cross-section and 1-3 turns, and the protruding ridges (21) are 2-6 evenly distributed.

4. The anti-loosening nut according to claim 1, characterized in that: The cross-section of the spring (3) is trapezoidal, triangular, or a combination of trapezoid and semicircle, and the number of spring coils is less than one. The number of protruding ribs (21) is 1 or 2.

5. The anti-loosening nut according to claim 1, characterized in that: The protrusion (21) is replaced by a groove, and the two protrusions of the spring (3) are placed in the groove.

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