Eccentric locknut assembly

Abstract

The utility model discloses an eccentric locknut assembly which comprises a nut and a gasket. And an eccentric step and a positioning step are processed on the fastening matching surface of the nut. The eccentric step and the positioning step are respectively matched with the eccentric inner circle and the positioning inner circle on the gasket, the eccentric distance of the eccentric circle and the positioning circle is preferably the sum of the absolute values of the deviations of the internal thread and the external thread, and the screwing angle of the pre-tightening force is preferably 45-60 degrees. The end face of the nut is provided with more than two fins which are uniformly distributed in a whole circle or a circumference. And after being deformed, the fins are matched with the fin grooves on the gasket and do not protrude out of the fastening matching surface of the gasket. In order to facilitate sleeving mechanization, the gasket is provided with a guide face, and the nut is provided with a cold heading mark. The nut and the gasket are assembled and matched into an integrated structure and are not separated, and the nut and the gasket can be directly screwed for installation.

Description

Technical Field

[0001] This utility model applies to the fastener industry and relates to anti-loosening nuts, specifically an integrated nut assembly that uses eccentricity to achieve anti-loosening. Background Technology

[0002] Fasteners typically refer to standard parts such as bolts and nuts. When bolts and nuts are threaded together to fasten workpieces, washers, shims, or elastic washers are usually used. Shims increase the contact area between the bolt or nut and the workpiece. Under the preload of the bolt, they increase the friction between the washer and the workpiece, thus preventing loosening. However, as the elastic preload gradually disappears, the washer becomes ineffective in preventing loosening. Therefore, elastic washers are used, utilizing their elasticity to strengthen the bolt preload for a longer period, thus preventing loosening. However, the elastic deformation of the elastic washer also diminishes as the stress disappears, thus failing to achieve the anti-loosening effect. Therefore, improvements need to be made to the structure of the nut or bolt to achieve the anti-loosening effect, such as the wedge-clamp anti-loosening nut (CN117145851A) and the ribbed anti-loosening nut (CN117905778A). There are many patent applications in this area, such as the combined anti-loosening nut (CN109026962B) and the anti-loosening nut (CN110410409B), both of which use two nuts to cooperate in preventing loosening. Most anti-loosening patents only emphasize the anti-loosening effect without considering manufacturing costs and market acceptance. Currently, the best-selling anti-loosening nut on the market is patent CN2084122U, which embeds a nylon anti-loosening ring on the upper surface of the nut's inner hole, using the deformation of the anti-loosening ring to achieve anti-loosening. This anti-loosening nut has a simple structure, low cost, and is easy to mass-produce mechanically. Patent CN116428261A is an anti-loosening nut that uses a spring ring instead of the nylon anti-loosening ring in the aforementioned patent.

[0003] There are also patents that improve the structure of gaskets to achieve anti-loosening, such as CN113983065A, which describes an eccentric anti-loosening washer that uses radial elastic deformation to press the stud or screw on the inner ring and the bolt head or nut on the outer ring. This creates a clamping force on the threaded connection, preventing the threaded pair from loosening. At the same time, the clamping force generates static friction at the clamping position to prevent the nut or bolt head from rotating, thus achieving a dual anti-loosening effect. This anti-loosening washer adds a local radial clamping structure on the outer ring. This structure is not easy to manufacture by stamping, and both cold stamping and hot stamping place high demands on the material's deformation fluidity and mold design. CN117108619A discloses an anti-loosening nut assembly with an eccentric hole washer. The nut end face has a protrusion, and the washer has multiple limiting grooves matching the protrusion. The inner hole of the washer is an eccentric hole, and the groove distribution circle is concentric with the eccentric hole. A countersunk groove, consistent with the outer circle of the washer, is machined on the bolt hole of the fastened object. When this nut assembly is connected to the bolt, the washer is located in the countersunk groove. After the nut is tightened, the protrusion on it will most likely get stuck in the limiting groove. Even if the protrusion does not enter the limiting groove, it will increase the anti-loosening friction between the washer and the nut. If the nut has a tendency to rotate in the opposite direction, because the inner hole of the washer is eccentric, it cannot rotate in the opposite direction within the limiting groove, thus preventing the nut from rotating in the opposite direction and achieving the purpose of preventing the nut from loosening. This assembly imposes requirements on the workpiece, requiring the machining of limiting grooves that mate with the washer, increasing the workpiece's production process.

[0004] The applicant filed two applications on June 26, 2024, entitled "A Double Eccentric Washer Anti-Loosening Nut," with application numbers 2024108417384 and 2024214843609. The nut and washer are complementary components, both indispensable. During installation, the operator assembles the nut and washer, with the eccentricity marks on the nut and washer corresponding. The disadvantage is that the nut and washer are separate pieces, not an integrated structure before installation; installation is impossible without the nut, and the anti-loosening effect is ineffective without the washer. To facilitate installation and transportation and avoid separation, this application processes them into a single integrated structure. Utility Model Content

[0005] The technical problem solved by this utility model is to provide an eccentric anti-loosening nut assembly that utilizes eccentric tightening to achieve full elastic contact of the thread on one side, thus preventing loosening. The assembly is a one-piece structure, simple in design, with a short manufacturing process, and convenient for transportation and installation.

[0006] The technical solution adopted in this utility model is as follows: the eccentric anti-loosening nut assembly includes a nut and a washer. Two steps are machined on the fastening mating surface of the nut: an upper eccentric step and a lower positioning step. A stepped hole is machined on the washer, the eccentric inner circle above which mates with the eccentric outer circle of the nut's eccentric step. The inner hole of the washer is a positioning inner circle, which mates with the positioning outer circle of the nut's positioning step. A wing is provided on the end face of the positioning step; a wing groove is designed at the junction of the positioning inner circle and the fastening mating surface of the washer. This wing groove mates with the deformed wing. The deformed wing does not protrude from the fastening mating surface of the washer and does not affect the installation of this eccentric anti-loosening nut assembly.

[0007] Furthermore, the upper and lower positions of the eccentric step and the positioning step are interchanged, that is, the upper position is the positioning step and the lower position is the eccentric step, and the wing is disposed on the end face of the eccentric step.

[0008] Furthermore, the eccentricity between the eccentric outer circle and the positioning outer circle, and the eccentricity between the eccentric inner circle and the positioning inner circle, are the sum of the absolute value of the negative deviation of the external thread and the positive deviation of the internal thread. The tightening angle for applying preload to the nut is 30°-90°, preferably 45°-60°. At this angle, the thread elastic deformation is relatively small, and the thread elastic recovery time is long, which helps to prevent loosening for a long time after installation.

[0009] Furthermore, the eccentric outer circle and the eccentric inner circle are mating conical surfaces, and the positioning outer circle and the positioning inner circle are mating conical surfaces. This facilitates demolding after cold heading of the nut and cold stamping deformation of the washer, and helps to improve the service life of the mold.

[0010] Furthermore, the fins are either a complete circle or two or more evenly distributed around the circumference. The smaller the fin size, the higher the cold heading rate, the lower the resistance to deformation, and the more favorable it is for cold pressing deformation.

[0011] Furthermore, the gasket is provided with two parallel guide surfaces, which helps to maintain a fixed orientation within the gasket conveying groove. The nut is provided with cold forging markings on two parallel surfaces corresponding to the guide surfaces, which facilitates the positioning and inspection of the nut within the nut conveying groove, ensuring that the orientation corresponds to the orientation of the gasket guide surface, thus preparing for precise fitting and realizing the mechanization of gasket and nut fitting.

[0012] The beneficial effects of this utility model are: The structure is simple, with the nut and washer assembled as a single unit that cannot be separated. The process of setting up the washer and nut during installation is moved forward; installation simply requires tightening, making it convenient, saving installation time, and preventing waste of nuts or washers. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the structure of Example 1;

[0014] Figure 2 for Figure 1 A top view of the gasket;

[0015] Figure 3 for Figure 1 A bottom view diagram of a nut;

[0016] Figure 4 This is an installation diagram of Example 1;

[0017] Figure 5 This is a production process diagram for Example 1;

[0018] Figure 6 This is a schematic diagram of the cold heading blank for the nut in Example 2;

[0019] Figure 7 for Figure 6 A top-down view;

[0020] Figure 8 This is a schematic diagram of the structure of Example 3;

[0021] In the diagram: 1-Nut, 2-Washer, 3-Centerline I, 4-Centerline II, 5-Bolt, 6-Workpiece, 7-Bolt centerline;

[0022] 11-Outer stepped surface, 12-Eccentric outer circle, 13-Nut stepped annular surface, 14-Positioning outer circle, 15-Wing;

[0023] 21-Upper plane, 22-Eccentric inner circle, 23-Gasket stepped annular surface, 24-Positioning inner circle, 25-Wing groove, 26-Guide surface. Detailed Implementation

[0024] The text above and below is an appendix. Figure 1 The vertical direction. The fastening surfaces of the following gaskets are attached. Figure 1 The lower plane of the washer and the fastening mating surface of the nut refer to the stepped surface of the nut's mounting end. Example

[0025] The structure of the eccentric anti-loosening nut assembly in this embodiment is shown in the attached figure. Figure 1-3 As shown, it includes a nut 1 and a washer 2.

[0026] Nut 1 is a modification of the standard nut, as shown in the attached image. Figure 1 and attached Figure 3As shown, the shape is an outer hexagon with an inner circle. The centerline of the nut is centerline I3. Two steps are machined on the fastening surface of nut 1: the upper, larger diameter step is the eccentric step, and the lower, smaller diameter step is the positioning step. The eccentric step is formed by the outer step surface 11 and the eccentric outer circle 12. The outer step surface 11 is a plane of an outer hexagon with an inner eccentric circle. The centerline of the eccentric outer circle 12 is centerline II4. Centerline II4 has an eccentricity relative to centerline I3, and this eccentricity is not less than twice the clearance between the nut's internal thread and the bolt's external thread. The positioning step is formed by the nut step annular surface 13 and the positioning outer circle 14. The nut step annular surface 13 is an annular plane of the eccentric inner and outer circles, as shown in the attached figure. Figure 3 As shown, the center line of the outer positioning circle 14 is the center line I3 of the nut. A wing 15 is provided on the end face of the lower positioning step. The wing 15 is relatively thin to facilitate cold pressing deformation.

[0027] As attached Figure 2 As shown, the inner hole of gasket 2 is machined with a stepped hole. The upper part of this stepped hole is formed by an eccentric inner circle 22 and a stepped surface 23 of the gasket. The eccentric inner circle 22 mates with the eccentric outer circle 12, and its center line is center line II4. The stepped surface 23 of the gasket is an annular plane of the eccentric inner and outer circles, as shown in the attached figure. Figure 2 As shown. The inner hole of the gasket 2 is a positioning inner circle 24, and the center line of the positioning inner circle 24 is the center line I3. The positioning outer circle 14 mates with the positioning inner circle 24. A wing groove 25 is designed at the junction of the positioning inner circle 24 and the lower surface (fastening mating surface) of the gasket. This wing groove 25 mates with the wing 15 to facilitate the deformation of the wing 15 and provide space for the deformed wing 15. After deformation, the wing 15 is placed in the wing groove 25, does not protrude from the fastening mating surface of the gasket, and does not hinder the installation of this embodiment.

[0028] The production process of this embodiment is shown in the appendix. Figure 5 As shown, the process includes cold heading, tapping, assembly, and cold pressing. Cold heading involves cold heading the raw material into a nut blank, during which the outer diameter of the washer is no larger than the diameter of the positioning outer circle. Tapping involves machining the thread into the inner hole of the nut. Assembly involves fitting the washer and nut together, with the eccentric outer circle and positioning outer circle of the nut mate with the eccentric inner circle and positioning inner circle of the washer. To facilitate the assembly, two parallel guide surfaces 26 are provided on the washer, which correspond to the two parallel surfaces of the outer hexagon of the nut, ensuring that the center lines I and II of the nut and washer are aligned. After the washer is assembled, a spherical or arc-shaped pressure head is used to cold-press and deform the washer, causing the washer 15 to enter the washer groove 25, thereby fixing the washer and nut together, achieving an integrated structure that cannot be separated.

[0029] When using this embodiment, as shown in the attached document... Figure 4As shown, the internal thread of the nut is screwed into the external thread of the bolt 5, and the washer and nut rotate simultaneously. When the fastening mating surface of the washer just contacts the workpiece 6, the friction between the washer and the workpiece is very small, and the washer can still rotate with the nut. When the outer stepped surface 11 of the nut contacts the upper surface 21 of the washer, or the nut stepped annular surface 13 of the nut contacts the washer stepped surface 23 of the washer, the axial force applied by the nut to the washer increases the friction between the lower surface (fastening mating surface) of the washer and the workpiece, and the washer stops rotating. At this time, the eccentric outer circle 12 of the nut and the eccentric inner circle 22 of the washer are in contact. Since no preload is applied, the thread does not undergo elastic deformation. For standard fasteners, the preload is usually tightened by 90° to 180°. Continue to tighten the nut to apply the preload, tightening by about 30°-90°. At this time, the force between the eccentric outer circle 12 and the eccentric inner circle 22 causes the nut and washer to move horizontally together. The result of the translation is shown in the attached figure. Figure 4 As shown, the bolt centerline 7 is offset to the left of the nut centerline I3, resulting in tight contact between the nut's internal thread and the bolt's external thread on the left side, eliminating gaps and increasing the thread contact area. The elastic deformation generated by the preload not only increases the friction between the washer and the workpiece but also increases the friction between the internal and external threads, achieving an anti-loosening effect for the nut connection. In this embodiment, the preload tightening angle is small, the axial preload is small, and the elastic deformation is small, mainly relying on the attached... Figure 4 The internal thread of the nut on the left side and the external thread of the bolt are in full contact after elastic deformation, which increases the friction area and friction force to prevent loosening after pre-tightening during installation.

[0030] It should be noted that: 1) The center line of the eccentric outer circle of the nut and the center line of the eccentric inner circle of the washer do not need to be consistent, as long as they can be moved together after contact. 2) As attached Figure 1 The nut's positioning outer circle is located below the eccentric outer circle, ensuring uniform fin thickness. 3) Apply preload when tightening the nut; the tightening angle should be 45°-60°. The eccentricity design ensures that the thread undergoes elastic deformation while maintaining the desired tension. Figure 4The left-side thread is in full contact, so the eccentricity of centerline I and centerline II is related to the thread clearance. The thread elastic deformation at this angle is relatively small, and the thread elastic recovery time is long, which helps prevent loosening after installation in this embodiment. 4) A guide surface is provided on the gasket to automate the fitting process. The guide surface contacts the two side plates of the gasket conveying groove, ensuring the consistency of the gasket's conveying direction and achieving precise fitting with the nut. 5) The nut is a regular hexagon, consistent in three directions, but only in one direction when fitting with the gasket. Therefore, it is advisable to cold-forge markings on two parallel surfaces corresponding to the guide surface to facilitate nut positioning and inspection within the nut conveying groove, ensuring that this direction corresponds to the direction of the gasket guide surface, preparing for precise fitting. 6) The production of ordinary nuts includes two main processes: cold forging and tapping. This embodiment adds fitting and cold pressing, which are performed at one station. Cold pressing is performed directly after fitting. Although an additional station is added to the production process, it ensures a one-to-one correspondence between the nut and the gasket, eliminating the need for separate transportation. During installation, fitting is not required; direct screwing is sufficient. This production process essentially moves the subsequent installation of the nut and washer to the production stage, greatly facilitating installation and eliminating nut waste due to washer loss. 7) If the eccentricity is twice the thread clearance, a 90° turn will achieve full thread contact on one side. Although the thread specifications are fixed, there are deviations in the machining dimensions of the internal and external threads. Therefore, the eccentricity should ideally be the sum of the absolute value of the negative deviation of the standard external thread and the positive deviation of the standard internal thread (the thread deviation is twice the thread clearance). In this case, the nut turning angle should not exceed 90°, and in most cases, it should be between 45° and 60°. Example

[0031] The structure of the eccentric anti-loosening nut assembly in this embodiment is shown in the attached figure. Figure 6 and attached Figure 7 As shown, the difference from Embodiment 1 is that the winglets 15 are multiple circumferentially distributed, not a complete circle; any two or more evenly distributed winglets are acceptable. The attached diagram for this embodiment shows four. In Embodiment 1, the complete circular winglets are difficult to cold-forge and have high cold-pressing deformation resistance, requiring a high-pressure stamping press. Therefore, the complete circular winglets in Embodiment 1 are replaced with multiple evenly distributed small-sized winglets, increasing the cold-forging forming rate and reducing the cold-pressing deformation resistance. Example

[0032] The structure of the eccentric anti-loosening nut assembly in this embodiment is shown in the attached figure. Figure 8As shown, the difference from Embodiment 2 is that the mating eccentric outer circle 12 and eccentric inner circle 22 are changed from cylindrical surfaces to conical surfaces, and / or the mating locating outer circle 14 and locating inner circle 24 are changed from cylindrical surfaces to conical surfaces; the other structures remain the same. Changing the cylindrical surfaces to mating conical surfaces does not affect the use of the anti-loosening nut assembly, but it facilitates demolding after cold heading of the nut and cold stamping deformation of the washer, thus improving the service life of the mold. Example

[0033] In this embodiment, the positions of the eccentric outer circle 12 and the positioning outer circle 14, and the eccentric inner circle 22 and the positioning inner circle 24 in the above embodiments are interchanged. (See attached...) Figure 1 The nut in the middle has a large-diameter upper step for positioning and a small-diameter lower step for eccentricity. The outer positioning circle 14 is located above the eccentric outer circle 12, and the inner positioning circle 24 is located above the eccentric inner circle 22. At this time, the wing 15 is set on the end face of the eccentric step. Although the gap between the eccentric outer circle 12 and the eccentric inner circle 22 is uneven after screwing and installation, it does not affect the wing fixing shim before use, thus achieving the integration of the two.

[0034] This invention features a wing-shaped component machined on the fastening surface of the nut and a wing-shaped groove machined on the fastening surface of the washer. The wing, after deformation, engages with the wing-shaped groove to secure the washer, achieving a seamless assembly of the nut and washer that prevents separation during transport. In use, it can be directly screwed on for installation, eliminating the need for on-site assembly of the nut and washer. This invention moves the assembly of the nut and washer to the production process before installation, saving on-site installation time and improving installation efficiency. Since the nut and washer in this invention work together and are indispensable, their integrated design also prevents nut waste due to wasted washer space.

[0035] This invention employs a positioning circle for positioning, utilizing the interaction of eccentric circles to achieve horizontal movement of the washer and nut, thus achieving full contact on one side of the thread. Synchronized with the elastic deformation of the thread, the preload generates significant inter-thread friction to prevent loosening. The small centerline eccentricity ensures uniform metal deformation and flow, and there are no special requirements for materials or molds. This invention achieves the anti-loosening effect simply by tightening, with no special requirements for the workpiece or bolt. It is convenient to use, has a wide range of applications, and possesses market promotion value.

Claims

1. An eccentric lock nut assembly comprising a nut and a washer, characterized by: The fastening surface of the nut is processed with two steps, the upper step is eccentric step and the lower step is positioning step; the washer is processed with step hole, the upper eccentric inner circle (22) of the step hole is matched with the eccentric outer circle (12) of the eccentric step, the inner hole of the washer is positioning inner circle (24), the positioning inner circle (24) is matched with the positioning outer circle (14) of the positioning step; the end surface of the positioning step is provided with wing (15), the junction of the positioning inner circle (24) and the fastening surface of the washer is designed with wing groove (25), the wing groove (25) is matched with the deformed wing (15), the deformed wing (15) does not protrude the fastening surface of the washer.

2. An eccentric lock nut assembly according to claim 1 wherein: The upper and lower positions of the eccentric step and the positioning step are exchanged, and the wing (15) is arranged on the end surface of the eccentric step.

3. An eccentric lock nut assembly according to claim 1 or 2, wherein: The eccentric distance of the eccentric outer circle (12) and the positioning outer circle (14) and the eccentric distance of the eccentric inner circle (22) and the positioning inner circle (24) are the sum of the absolute value of the negative eccentricity of the external thread and the positive eccentricity of the internal thread.

4. An eccentric lock nut assembly according to claim 3, wherein: The screwing angle of the nut for applying pre-tightening force is 30°-90°.

5. An eccentric lock nut assembly according to claim 1 or 2, wherein: The eccentric outer circle (12) and the eccentric inner circle (22) are matched conical surfaces.

6. An eccentric lock nut assembly according to claim 1 or 2, wherein: The positioning outer circle (14) and the positioning inner circle (24) are matched conical surfaces.

7. An eccentric lock nut assembly according to claim 1 or 2, wherein: The wing (15) is integral circle or more than two wings distributed uniformly in the circumference.

8. An eccentric lock nut assembly according to claim 1 or 2, wherein: The washer is provided with two parallel guide surfaces (26), and the nut is provided with cold heading marks on the corresponding two parallel surfaces of the guide surfaces (26).

Images