Anti-loosening fastener and method of manufacturing the same

Abstract

The application discloses an anti-loosening fastener and a manufacturing method thereof, relates to the technical field of fasteners, and improves the problems that the existing plug-in fastener is prone to axial back-off of a mandrel, retraction of an expansion locking part, reduction of clamping force and loosening of the fastener under the action of long-term vibration and alternating load, and comprises a cap body, the mandrel and the expansion locking part, the cap body is provided with a sleeve, a guide hole is arranged in the sleeve, the mandrel is arranged in the guide hole, a tapered distraction part is formed at the lower end of the mandrel, locking teeth are arranged on the outer periphery of the mandrel, the expansion locking part is connected to the lower end of the sleeve, a guide cavity is arranged in the expansion locking part for the tapered distraction part to pass through, and a plurality of elastic locking pieces are arranged in the guide cavity in a circumferential interval, and a retreat-preventing piece is arranged in the guide cavity and is engaged with the locking teeth. The application has the effects of improving the axial locking stability of the mandrel, keeping the expansion locking part in a continuous locking state, and improving the anti-vibration and anti-loosening performance of the fastener.

Description

Technical Field

[0001] This application relates to the field of fastener technology, and in particular to an anti-loosening fastener and a method for manufacturing the same. Background Technology

[0002] Fasteners are widely used for connecting and fixing products such as automobiles, electronic equipment, home appliances, machinery, molds and industrial equipment. Among them, plug-in fasteners are widely used for quick connection between plastic parts, thin sheet metal parts and composite materials due to their advantages such as convenient installation, high assembly efficiency and no need for threaded mating.

[0003] Existing plug-in fasteners typically include a cap, a spindle, and an expansion locking part. During installation, the expansion locking part is inserted into the mounting hole, and then the spindle is pushed to move axially, causing the expansion locking part to open radially and form a snap-fit ​​with the inner wall of the mounting hole, thereby achieving connection and fixation.

[0004] However, existing plug-in fasteners primarily rely on the elastic deformation of the expansion locking part and the frictional fit between it and the mounting hole for fixation. Under vehicle vibration, equipment operation, or long-term alternating loads, the expansion locking part is prone to elastic decay due to repeated stress, and its radial support force gradually decreases. Simultaneously, there is usually a lack of a reliable anti-retraction structure between the mandrel and the expansion locking part, allowing the mandrel to easily experience slight axial retraction. This causes the expansion locking part to gradually shrink, continuously reducing the locking force between it and the mounting hole. When this slight displacement accumulates, the fastener is prone to axial withdrawal, and in severe cases, it may even completely detach from the mounting hole, affecting the stability and reliability of the connection structure. Summary of the Invention

[0005] To address the problem that existing plug-in fasteners suffer from weakened support force in the expansion locking part and axial retraction of the spindle under long-term vibration and alternating loads, leading to shrinkage of the expansion locking part, reduced locking force, and ultimately easy loosening and removal from the mounting hole, this application provides an anti-loosening fastener and its manufacturing method.

[0006] This application provides an anti-loosening fastener and its manufacturing method, adopting the following technical solution: An anti-loosening fastener includes a cap body, a spindle, and an expansion locking part. The cap body is provided with a sleeve, and a guide hole is provided through the sleeve along the axial direction. The mandrel is provided through the guide hole, the upper end of the mandrel is located in the cap body, the lower end extends out of the sleeve and forms a tapered opening, and the outer periphery of the mandrel is provided with locking teeth. The expansion locking part is connected to the lower end of the sleeve. The expansion locking part is provided with a guide cavity along the axial direction for the conical expansion part to pass through. The expansion locking part includes a plurality of elastic locking pieces distributed circumferentially, and a slot is formed between each elastic locking piece. The guide cavity is provided with a backstop that engages with the locking teeth. The backstop is located above the tapered expansion portion, and the locking teeth engage with the backstop sequentially along the spindle insertion direction.

[0007] Preferably, the anti-reverse component includes a plurality of elastic locking claws spaced apart circumferentially along the guide cavity. One end of each elastic locking claw is connected to the expansion locking portion, and the other end extends obliquely toward the center of the guide cavity and contacts the locking teeth.

[0008] Preferably, the locking teeth include a plurality of annular teeth arranged sequentially along the spindle axis, and a locking groove is formed between two adjacent annular teeth, with the anti-reverse member embedded in the locking groove.

[0009] Preferably, the expansion locking part includes a plurality of axially extending elastic locking pieces, with a through slot formed between adjacent elastic locking pieces, and each elastic locking piece having an outwardly protruding locking protrusion at its lower end.

[0010] Preferably, a first limiting gasket is fitted on the outer side of the sleeve, and a second limiting gasket is fitted on the outer side of the expansion locking part. The first limiting gasket and the second limiting gasket are spaced apart along the axial direction of the mandrel.

[0011] Preferably, the cap body includes a mounting base connected to the upper end of the sleeve, and two radially extending operating wing plates are respectively connected to both sides of the mounting base, with the two operating wing plates symmetrically distributed around the center of the mounting base.

[0012] A method for manufacturing an anti-loosening fastener includes the following steps: S1. The cap body, sleeve and mandrel blanks are formed by cold heading process; S2. The lower end of the mandrel is shaped to form a tapered expansion part, and locking teeth are machined on the outer periphery of the mandrel rod. S3. The expansion locking part is prepared by stamping or injection molding process, and a guide cavity, multiple elastic locking pieces and anti-reverse parts are formed; S4. Insert the mandrel into the sleeve so that the locking teeth correspond to the anti-reverse part, and then connect the expansion locking part to the lower end of the sleeve. S5. Place the first limiting washer and the second limiting washer into their respective positions to complete the assembly of the anti-loosening fasteners.

[0013] In summary, this application includes at least one of the following beneficial effects: 1. This application provides a locking tooth on the outer periphery of the mandrel body and a backstop that meshes with the locking tooth in the guide cavity of the expansion locking part, so that the mandrel can maintain an axially locked state after the expansion locking part is pushed open, reducing the possibility of the mandrel backing up under vibration and alternating load, thereby reducing the problem of loosening of the expansion locking part caused by the mandrel backing up and improving the stability of the fastening connection; 2. This application provides a tapered expansion portion at the lower end of the mandrel and a guide cavity for the tapered expansion portion to pass through in the expansion locking portion, so that multiple elastic locking plates can be pushed outward synchronously during the axial movement of the mandrel, so that the elastic locking plates form a stable engagement with the inner wall of the mounting hole, thereby improving the radial locking capability of the fastener. 3. In addition, a first limiting washer and a second limiting washer are respectively provided on the outside of the sleeve and the outside of the expansion locking part, so that the fastener can form a multi-position axial limiting structure after installation, reducing the possibility of axial movement of the fastener as a whole in the mounting hole and improving the connection reliability during long-term use. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the overall structure of the fastener in this embodiment of the present application; Figure 2 This is a cross-sectional schematic diagram of the fastener of this embodiment of the present application; Figure 3 This is a cross-sectional schematic diagram of the expansion locking part in this embodiment of the present application.

[0015] Explanation of reference numerals in the attached drawings: 1. Cap body; 11. Mounting base; 111. Operating wing plate; 12. Sleeve; 121. Guide hole; 2. Mandrel; 21. Conical expansion part; 22. Locking tooth part; 221. Ring tooth; 3. Expansion locking part; 31. Guide cavity; 32. Elastic locking piece; 321. Locking protrusion; 4. Anti-reverse component; 5. First limiting washer; 6. Second limiting washer. Detailed Implementation

[0016] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0017] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0018] In this application, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0019] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0020] In addition, the term "multiple" should mean two or more.

[0021] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments. Example

[0022] This application discloses an anti-loosening fastener, including a cap 1 at the top, a spindle 2 passing through the inside of the cap 1, and an expansion locking part 3 connected to the bottom of the cap 1. The anti-loosening fastener adopts a split structure. The axial movement of the spindle 2 causes the expansion locking part 3 to expand radially, and the anti-reverse fit between the spindle 2 and the expansion locking part 3 maintains the locked state, thereby improving the connection stability of the fastener under vibration and alternating load environments.

[0023] The cap body 1 includes a mounting base 11 and a sleeve 12 connected below the mounting base 11. The mounting base 11 has a plate-like structure and is coaxially and fixedly connected to the sleeve 12. The sleeve 12 extends downward along the thickness direction of the mounting base 11. Operating wing plates 111 are integrally connected to both sides of the mounting base 11. The two operating wing plates 111 are symmetrically distributed along the center of the mounting base 11 and extend radially outward to form a sheet-like structure. During installation, the operator can position and apply force to the cap body 1 using the operating wing plates 111, ensuring that the fasteners are inserted into the installation position in a stable posture.

[0024] In addition, a guide hole 121 is provided axially inside the sleeve 12, extending from the upper end to the lower end of the sleeve 12, forming a channel for the mandrel 2 to pass through and move axially. The mandrel 2 is installed in the guide hole 121, and the mandrel 2 has a rod-shaped structure. The upper end of the mandrel 2 is located inside the mounting base 11, and the lower end of the mandrel 2 extends out of the sleeve 12. The lower end of the mandrel 2 is provided with a tapered support portion 21, which is integrally connected to the rod body of the mandrel 2. The tapered support portion 21 extends downward along the axial direction of the mandrel 2, and its outer diameter gradually increases from top to bottom, thereby forming an inclined support surface.

[0025] The mandrel 2 has a locking tooth portion 22 on its outer periphery, which extends axially along the mandrel 2. In this embodiment 1, the locking tooth portion 22 includes a plurality of annular teeth 221 arranged sequentially along the length of the mandrel 2, and a locking groove is formed between two adjacent annular teeth 221. Each annular tooth 221 has a guide side and a locking side; the guide side is inclined toward the insertion direction of the mandrel 2, and the locking side forms a blocking surface along the radial direction of the mandrel 2, so that the mandrel 2 can gradually pass over the anti-reverse structure when moving in the insertion direction, and is blocked and restricted when moving in the reverse direction.

[0026] The expansion locking part 3 is connected to the lower end of the sleeve 12, and a guide cavity 31 is provided axially inside the expansion locking part 3. The guide cavity 31 communicates with the guide hole 121 inside the sleeve 12 and is coaxially arranged with the mandrel 2. The tapered opening part 21 at the lower end of the mandrel 2 can extend into the guide cavity 31 and move axially along the guide cavity 31. The expansion locking part 3 includes a plurality of elastic locking pieces 32 distributed circumferentially, each elastic locking piece 32 extending axially and arranged circumferentially around the guide cavity 31. A through slot is formed between two adjacent elastic locking pieces 32, and the slot extends axially along the expansion locking part 3, so that each elastic locking piece 32 forms an independent elastic deformation region.

[0027] In this embodiment 1, each elastic locking piece 32 has a locking protrusion 321 at its lower end. The locking protrusion 321 is located on the side of the elastic locking piece 32 away from the guide cavity 31 and protrudes radially outward. When the tapered expansion part 21 enters the guide cavity 31 axially, the outer inclined surface of the tapered expansion part 21 abuts against the inner side of the multiple elastic locking pieces 32, and pushes the multiple elastic locking pieces 32 to elastically deform outward at the same time, causing the locking protrusion 321 to expand outward. After installation, the locking protrusion 321 abuts against the inner wall of the mounting hole, thereby forming a radial locking relationship.

[0028] To prevent the mandrel 2 from axially retracting under long-term vibration, a stop member 4 is provided inside the guide cavity 31. The stop member 4 is located above the tapered expansion portion 21 and at a position corresponding to the locking teeth portion 22. The stop member 4 includes multiple elastic locking claws. The multiple elastic locking claws are spaced apart circumferentially along the guide cavity 31, with one end of each elastic locking claw fixedly connected to the expansion locking portion 3, and the other end extending obliquely toward the center of the guide cavity 31. The elastic locking claws are made of an elastic material and can generate radial elastic displacement when pushed by the mandrel 2.

[0029] When the mandrel 2 moves downward, the annular teeth 221 on the mandrel 2 first contact the elastic locking pawl. The guide side of the annular teeth 221 pushes the elastic locking pawl to produce elastic deformation, allowing the mandrel 2 to continue moving downward. When the mandrel 2 moves to the set position, the elastic locking pawl enters the corresponding locking groove and abuts against the locking side of the annular teeth 221. Since a one-way meshing structure is formed between the elastic locking pawl and the locking groove, the mandrel 2 can move in the insertion direction, but cannot exit in the opposite direction due to the restriction of the elastic locking pawl. Thus, while the tapered opening part 21 keeps the elastic locking piece 32 in the open state, the mandrel 2 will not axially retract due to vibration, thereby maintaining the locking force between the expansion locking part 3 and the mounting hole.

[0030] Furthermore, to improve the axial limiting effect after fastener installation, a first limiting washer 5 is provided on the outer side of the sleeve 12, and a second limiting washer 6 is provided on the outer side of the expansion locking part 3. The first limiting washer 5 is sleeved on the outer periphery of the sleeve 12 and is located close to the cap 1. The second limiting washer 6 is sleeved on the outer periphery of the expansion locking part 3 and is located above the locking protrusion 321. The first limiting washer 5 and the second limiting washer 6 are spaced apart along the axial direction of the mandrel 2.

[0031] When the fastener is inserted into the mounting hole of the part to be connected, the first limiting washer 5 and the second limiting washer 6 are located on both sides of the part to be connected and abut against the surface of the part to be connected, thereby restricting the fastener from moving along the axial direction of the mounting hole.

[0032] The installation process for anti-loosening fasteners is as follows: First, insert the expansion locking part 3 into the mounting hole on the part to be connected, so that the cap 1 is located on the outside of the part to be connected; Subsequently, axial pressure is applied to the mandrel 2, causing the mandrel 2 to move downward along the guide hole 121; The tapered opening part 21 at the lower end of the spindle 2 enters the interior of the expansion locking part 3 and pushes multiple elastic locking pieces 32 to open outward, so that the locking protrusion 321 forms a snap-fit ​​with the inner wall of the mounting hole; During the movement of the spindle 2, the locking teeth 22 pass over the anti-reverse member 4 in sequence, and the elastic locking claws gradually enter the corresponding locking grooves; When the spindle 2 moves to the installation position, the elastic locking pawl remains engaged with the locking groove, restricting the spindle 2 from moving in the opposite direction. At this time, the expansion locking part 3 remains in an expanded state, the locking protrusion 321 continues to abut against the inner wall of the mounting hole, and the first limiting washer 5 and the second limiting washer 6 form an axial limit, so that the fastener remains in a stable connection state. Example

[0033] A method for manufacturing an anti-loosening fastener, the method being used to prepare the anti-loosening fastener of Example 1, includes the following steps: Step S1: Machining of the cap body 1 and sleeve 12 blanks. Engineering plastic granules are selected as raw materials, and the cap body 1 blank is prepared through injection molding, forming an integral structure with the cap body 1, mounting base 11, operating wing plate 111, and sleeve 12. During injection molding, an axially penetrating guide hole 121 is pre-drilled inside the sleeve 12, allowing the subsequent mandrel 2 to move axially along the guide hole 121.

[0034] Step S2: Mandrel 2 Machining. A mandrel 2 blank is prepared from a high-strength engineering plastic or metal material. The lower end of the mandrel 2 is machined by turning or molding to form a tapered support 21. Subsequently, multiple axially arranged annular teeth 221 are machined around the outer periphery of the mandrel 2, forming locking grooves between adjacent annular teeth 221. After machining, the surface of the mandrel 2 is deburred to ensure the edges of the annular teeth 221 remain intact, improving the meshing stability between the mandrel 2 and the anti-locking component 4.

[0035] Step S3: Machining of the expansion locking part 3. The expansion locking part 3 is prepared using injection molding, forming an axially penetrating guide cavity 31 inside the expansion locking part 3. Subsequently, multiple elastic locking pieces 32 are formed at circumferential intervals using a mold structure, and slots are formed between adjacent elastic locking pieces 32. At the same time, multiple elastic locking claws are formed inside the guide cavity 31, maintaining a connection between the elastic locking claws and the expansion locking part 3, and are inclined towards the center of the guide cavity 31.

[0036] Step S4: Assemble the mandrel 2 and the expansion locking part 3. Insert the mandrel 2 into the sleeve 12, positioning the mandrel 2 rod within the guide hole 121. Then, install the expansion locking part 3 onto the lower end of the sleeve 12, ensuring that the guide cavity 31 of the expansion locking part 3 is coaxially aligned with the guide hole 121 of the sleeve 12. During assembly, align the anti-reverse member 4 with the locking teeth 22 on the mandrel 2, allowing the elastic locking pawl to engage with the ring teeth 221.

[0037] Step S5: Installation and Inspection of Limiting Shims. Place the first limiting shim 5 on the outside of the sleeve 12, and the second limiting shim 6 on the outside of the expansion locking part 3, adjusting the positions of the two limiting shims. After assembly, inspect the dimensions and insertion / extraction force of the anti-loosening fastener to confirm that the spindle 2 can move in the installation direction, and that the anti-reverse component 4 can restrict the reverse movement of the spindle 2. After passing the inspection, the manufacturing of the anti-loosening fastener is complete.

[0038] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A fastener designed to prevent loosening and a method for manufacturing the same, comprising a cap body (1), a spindle (2), and an expansion locking part (3), characterized in that: The cap body (1) is provided with a sleeve (12), and a guide hole (121) is provided through the sleeve (12) along the axial direction. The mandrel (2) is provided through the guide hole (121). The upper end of the mandrel (2) is located inside the cap body (1), and the lower end extends out of the sleeve (12) and forms a conical opening (21). The outer periphery of the mandrel (2) is provided with locking teeth (22). The expansion locking part (3) is connected to the lower end of the sleeve (12). The expansion locking part (3) is provided with a guide cavity (31) along the axial direction for the conical expansion part (21) to pass through. The expansion locking part (3) includes a plurality of elastic locking pieces (32) distributed circumferentially, and a slot is formed between each elastic locking piece (32). The guide cavity (31) is provided with a stop member (4) that meshes with the locking teeth (22). The stop member (4) is located above the conical expansion part (21). The locking teeth (22) mesh with the stop member (4) in sequence along the insertion direction of the mandrel (2).

2. The anti-loosening fastener and its manufacturing method according to claim 1, characterized in that: The anti-reverse component (4) includes a plurality of elastic locking claws distributed circumferentially along the guide cavity (31). One end of the elastic locking claw is connected to the expansion locking part (3), and the other end extends obliquely toward the center of the guide cavity (31) and contacts the locking tooth part (22).

3. The anti-loosening fastener and its manufacturing method according to claim 1, characterized in that: The locking tooth part (22) includes a plurality of annular teeth (221) arranged sequentially along the axial direction of the spindle (2), and a locking groove is formed between two adjacent annular teeth (221), and the anti-reverse member (4) is embedded in the locking groove.

4. The anti-loosening fastener and its manufacturing method according to claim 3, characterized in that: The expansion locking part (3) includes a plurality of elastic locking pieces (32) extending along the axial direction, with a through slot formed between adjacent elastic locking pieces (32), and each elastic locking piece (32) has an outwardly protruding locking protrusion (321) at its lower end.

5. The anti-loosening fastener and its manufacturing method according to claim 4, characterized in that: The sleeve (12) is fitted with a first limiting gasket (5) on the outside, and the expansion locking part (3) is fitted with a second limiting gasket (6) on the outside. The first limiting gasket (5) and the second limiting gasket (6) are spaced apart along the axial direction of the mandrel (2).

6. The anti-loosening fastener according to claim 1, characterized in that: The cap body (1) includes a mounting base (11) connected to the upper end of the sleeve (12). The mounting base (11) has radially extending operating wing plates (111) connected to both sides of the mounting base (11). The two operating wing plates (111) are symmetrically distributed along the center of the mounting base (11).

7. A method for manufacturing an anti-loosening fastener according to any one of claims 1-6, characterized in that, Includes the following steps: S1. The blanks of the cap body (1), sleeve (12) and mandrel (2) are formed by cold heading process; S2. The lower end of the mandrel (2) is formed by forming a tapered support (21), and a locking tooth (22) is machined on the outer periphery of the mandrel (2). S3. The expansion locking part (3) is prepared by stamping or injection molding process, and a guide cavity (31), multiple elastic locking pieces (32) and a backstop (4) are formed. S4. Insert the mandrel (2) into the sleeve (12) so that the locking teeth (22) correspond to the anti-reverse part (4), and then connect the expansion locking part (3) to the lower end of the sleeve (12); S5. Place the first limiting gasket (5) and the second limiting gasket (6) on their respective positions to complete the assembly of the anti-loosening fasteners.

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