A composite double-effect expansion threaded core-pulling rivet and a mounting method thereof

Abstract

The application discloses a composite double-effect expansion threaded core-pulling rivet and a mounting method, and relates to the technical field of rivets, and can be widely applied to different riveting scenes. The composite double-effect expansion threaded core-pulling rivet is mainly composed of a rivet shank and a rivet sleeve, the taper expansion section is matched with the taper surface of the inner taper hole section, rotation prevention and anti-pulling fixation of the radial clamping of the hole wall are realized, meanwhile, the threaded locking drives the riveting deformation part to form an end bulge, and the axial clamping is realized in cooperation with the stop part. The mounting method only needs to insert the composite double-effect expansion threaded core-pulling rivet into the through hole from one side of the riveted part, and the double-effect locking can be completed by single-step rotary feeding, the connection strength and the anti-loosening performance are greatly improved, the mounting is efficient, the operation is convenient, the structure is reasonable, the composite double-effect expansion threaded core-pulling rivet can be widely applied to different riveting scenes, and has strong practicability and popularization value.

Description

Technical Field

[0001] This invention relates to the field of fastener technology, and in particular to a composite double-effect expansion threaded pop rivet and its installation method. Background Technology

[0002] Blind rivets are single-sided fasteners widely used in aerospace, automotive manufacturing, and general industrial fields for connecting thin-plate structures where conventional bolts or rivets cannot be used for double-sided operations.

[0003] In the prior art, the SLEEVEBOLT series fasteners developed by LISIAEROSPACE utilize the principle of tapered expansion. The tapered portion of the shank engages with the tapered hole of the sleeve, creating radial interference during installation, thus providing excellent fatigue resistance and sealing performance. However, these fasteners typically require additional protective devices to prevent misalignment of the taper before transportation or installation, resulting in a more complex structure and increased manufacturing costs and assembly steps.

[0004] Another existing technology, HOWMET's ERGOBOLT series, employs a different locking mechanism. It uses the internal thread at the tail end of the rivet to engage with the thread on the rivet shank. Later in the installation process, continued screwing causes the rivet end to form a bulge (or head) on the back of the interlayer, thus achieving mechanical locking. However, this structure has relatively weak initial radial expansion capacity, limited support for the hole walls of the composite laminate, and difficulty in fully utilizing the fatigue resistance potential of the composite structure.

[0005] In addition, traditional threaded pull pins, such as the latest patent application (publication number CN121273741A) filed by China Aviation Industry Standard Parts Manufacturing Co., Ltd., although combining multiple components, have a relatively complex structure, cumbersome installation steps, and need to be improved in terms of adaptability to composite material laminates.

[0006] Similarly, in fastener structural design, how to organically combine the high fatigue resistance of tapered interference fit with the high pull-out resistance of end bulge locking, and simplify the pre-assembly process and improve adaptability to different materials has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0007] A primary objective of this invention is to provide a composite double-effect expansion threaded blind rivet. Through a composite structure of conical expansion, threaded locking, and end bulge riveting, the rivet achieves dual fixation during installation by radially expanding to grip the hole wall and axially bulging to clamp the workpiece. At the same time, the threaded fit ensures reliable locking and prevents loosening, thereby improving the connection strength, anti-loosening ability, and riveting stability of the blind rivet.

[0008] This invention achieves the above objective through the following technical solution: a composite double-effect expansion threaded blind rivet, comprising a rivet shank and a rivet sleeve through which the rivet shank passes; the rivet shank comprises a stop section, a tapered expansion section, and an external thread section integrally connected sequentially along the axial direction; the outer diameter of the tapered expansion section gradually decreases towards the external thread section, and the outer diameter of the external thread section is smaller than the minimum outer diameter of the tapered expansion section; the rivet sleeve is axially hollow, comprising a stop portion, an inner tapered hole portion, a riveting deformation portion, and an internal thread portion integrally connected sequentially along the axial direction. The inner wall of the inner conical hole matches the taper of the outer wall of the conical expansion section. The inner diameter of the internal thread is smaller than the inner diameter of the remaining positions of the rivet sleeve. The external thread section is threadedly engaged with the internal thread. When the rivet shank and the rivet sleeve are locked, the inner wall of the inner conical hole is interference-fitted with the outer wall of the conical expansion section and expands radially to fit tightly against the hole wall of the riveted component. The inner wall of the stop portion fits against the outer wall of the stop section. The riveting deformation portion deforms into a bulge to cooperate with the stop portion to axially clamp the riveted component.

[0009] Specifically, the wall thickness of the riveted deformation portion is equal to the minimum wall thickness of the inner tapered hole portion and less than the maximum wall thickness of the inner thread portion.

[0010] Specifically, the stop section is a tapered structure that gradually decreases in size from one end near the drive section to the other end near the tapered expansion section, and the taper of the stop section is greater than the taper of the tapered expansion section.

[0011] Specifically, the nail rod also includes a drive section connected to one end of the stop section, and a necking groove is provided at the position adjacent to the stop section.

[0012] Furthermore, the end face of the drive section is provided with an inner polygonal countersunk hole for cooperating with a wrench.

[0013] Furthermore, the cross-sectional shape of the drive segment is a non-circular drive structure.

[0014] Furthermore, the drive section is a spline shaft structure with multiple key teeth evenly distributed circumferentially.

[0015] Another major objective of this invention is to provide an installation method for a composite double-effect expansion threaded core-pulling rivet. By rotating the feed, thread locking and axial pressure are achieved, and the bulging riveting of the rivet sleeve end and the radial expansion of the conical surface to clamp the hole wall are completed simultaneously. In one installation action, axial clamping and radial anti-rotation and anti-pull-out fixation are formed at the same time, so as to achieve reliable locking of the riveted parts, improve installation efficiency and connection stability.

[0016] This invention achieves the above objective through the following technical solution: a method for installing a composite double-effect expansion threaded pop rivet, comprising: 1) With the internal thread facing forward, pass the composite double-effect expansion threaded rivet through the through hole of the riveted part from the front until the stop is blocked by the edge of the through hole. 2) The rivet rod rotates and moves axially within the rivet sleeve, forcing the riveting deformation part to undergo radial plastic deformation to form a bulge structure, which squeezes the reverse side of the riveted part; at the same time, the outer wall of the tapered expansion section generates a radial component force on the inner wall of the inner tapered hole, causing the wall of the inner tapered hole to expand and deform outward, thereby tightly adhering to the hole wall of the through hole in the radial direction, forming radial fixation; at the end of the riveting, the stop section, the stop part, the hole wall of the riveted part and the bulge are tightly adhered in sequence, forming axial fixation.

[0017] Specifically, the initial state of the composite double-effect expansion threaded core-pulling rivet is as follows: the external thread section and the internal thread section are initially engaged, the rivet shank and the rivet sleeve are connected to form a loosely connected whole, and the inner wall of the stop section and the outer wall of the stop section make non-deformation contact.

[0018] Specifically, when there is a drive section at one end of the rivet shank, torque is applied to the drive section; at the end of the riveting, the drive section is rotated to break the rivet shank at the neck groove, and the rest of the rivet shank except for the drive section remains on the riveted part.

[0019] The beneficial effects of the technical solution of this invention are: 1. The composite double-effect expansion threaded blind rivet uses a composite structure of conical surface matching expansion, threaded locking and end bulge riveting to achieve dual fixation of the workpiece during rivet installation by radial expansion to grip the hole wall and axial bulge clamping the workpiece. At the same time, the threaded fit ensures reliable locking and is not easy to loosen, thereby improving the connection strength, anti-loosening ability and riveting stability of the blind rivet.

[0020] 2. The installation method achieves thread locking and axial pressure through rotary feed, simultaneously completing the bulging riveting of the rivet end and the radial expansion of the conical surface to clamp the hole wall. In one installation action, axial clamping and radial anti-rotation and anti-pull-out fixation are formed at the same time, realizing reliable locking of the riveted parts, improving installation efficiency and connection stability. Attached Figure Description

[0021] Figure 1 This is the front view of a composite double-effect expansion threaded blind rivet during tightening. Figure 2 This is an axial sectional view of the push rod; Figure 3 This is an axial sectional view of the nail sleeve; Figure 4 This is an axial sectional view of a composite double-effect expansion threaded blind rivet in its initial state. Figure 5This is a diagram showing the state of a composite double-effect expansion threaded blind rivet during the riveting process.

[0022] The diagram is marked as follows: 100-Composite double-effect expansion threaded blind rivet, 1-Pin rod, 11-Drive section, 111-Key tooth, 101-Neck break groove, 12-Stop section, 13-Conical expansion section, 14-External thread section; 2-Sleeve, 21-Stop, 22-Inner tapered hole, 23-Riveting deformation, 23a-Bulge, 24-Internal thread; 200 - Riveted parts. Detailed Implementation

[0023] The present invention will be further described in detail below with reference to specific embodiments.

[0024] Example: like Figure 1 and Figure 4 As shown, this embodiment discloses a composite double-effect expansion threaded pop rivet 100, including a rivet shank 1 and a rivet sleeve 2 through which the rivet shank 1 passes.

[0025] The nail rod 1 is mainly used to provide driving, locking, conical expansion and fracture separation functions, while the nail sleeve 2 is mainly used to realize radial expansion, end riveting deformation and axial clamping. In this invention, the two work together to complete the double-effect expansion and threaded locking riveting.

[0026] like Figure 2 As shown, the nail rod 1 includes a drive section 11, a stop section 12, a tapered expansion section 13, and an external thread section 14 that are integrally connected in sequence along the axial direction. The outer diameter of the tapered expansion section 13 gradually decreases towards the external thread section 14. That is, the outer diameter D1 of the tapered expansion section 13 near the stop section 12 is greater than the outer diameter D2 of the tapered expansion section 13 near the stop section 12, thus creating a taper. The outer diameter of the external thread section 14 is smaller than the minimum outer diameter D2 of the tapered expansion section 13, so that the external thread section 14 can smoothly enter the nail sleeve 2 and achieve threaded engagement, while ensuring that the tapered expansion section 13 can form a radial tightening effect on the nail sleeve 2.

[0027] The drive section 11 is used in conjunction with the tightening tool to receive torque and drive the nail shank 1 to rotate, thereby achieving thread feed and riveting force application. The stop section 12 fits and limits the axial insertion position of the nail shank 1 with the stop part 21 of the nail sleeve 2, and at the same time forms end face support after locking to ensure reliable axial positioning. The external thread section 14 and the internal thread part 24 of the nail sleeve 2 form a threaded pair, and axial feed is achieved by rotation, converting the rotational motion into axial locking force, while ensuring that it is not easy to loosen after riveting. The key point here is that during the continuous tightening of the nail shank 1, the inner tapered hole part 22 not only makes tapered surface contact with the tapered expansion section 13, but also generates radial component force during thread feed, forcing the nail sleeve 2 to expand radially and hug the through hole wall, thereby achieving radial pull-out resistance and anti-rotation fixation.

[0028] like Figure 3 As shown, the nail sleeve 2 is an axially hollow structure, which is integrally connected along the axial direction with a stop part 21, an inner tapered hole part 22, a riveting deformation part 23, and an internal thread part 24. The inner wall of the inner tapered hole part 22 matches the outer wall of the tapered expansion section 13 in taper, which facilitates the fit between the two and realizes expansion deformation. The outer diameter D3 of the inner tapered hole part 22 near the stop part 21 is larger than the outer diameter D4 of the end near the riveting deformation part 23, thus creating a taper. The inner diameter of the internal thread part 24 is smaller than the inner diameter of the rest of the nail sleeve 2. The external thread section 14 and the internal thread part 24 form a threaded fit, and axial feeding and locking are realized by rotation.

[0029] like Figure 3 As shown, the wall thickness of the riveting deformation portion 23 is equal to the minimum wall thickness of the inner tapered hole portion 22, and less than the maximum wall thickness of the inner thread portion 24. The thinner wall of the riveting deformation portion 23 causes the riveting deformation portion 23 and the inner tapered hole portion 22 to undergo plastic deformation preferentially under stress, which ensures that the end can bulge smoothly and that the middle section can expand radially effectively.

[0030] like Figure 2 As shown, the stop section 12 is a tapered structure that gradually decreases in size from one end near the drive section 11 to the other end near the tapered expansion section 13. The taper of the stop section 12 is greater than that of the tapered expansion section 13, which facilitates its fit and positioning against the inner wall of the stop part 21. At the same time, it forms a limit during the locking process to prevent the nail rod 1 from extending too far.

[0031] like Figure 1 and Figure 2 As shown, the nail rod 1 also includes a drive section 11 connected to one end of the stop section 12. The drive section 11 and the stop section 12 are adjacent to each other and a necking groove 101 is provided. After riveting, the drive section 11 can be broken at the necking groove 101 by applying torque, leaving only the working part in the riveted part 200 and not occupying external installation space.

[0032] like Figure 1As shown, the middle of the end face of the drive section 11 can be provided with an inner polygonal countersunk hole for cooperating with a wrench, or a drive structure with a non-circular cross section can be adopted. In this embodiment, the drive section 11 preferably adopts a spline shaft structure with multiple circumferentially distributed key teeth 111, which is convenient for cooperating with tightening tools to transmit torque and achieve stable rotational feed.

[0033] like Figure 4 As shown, the initial state of the composite double-effect expansion threaded core-pulling rivet 100 is as follows: the external thread section 14 and the internal thread section 24 are initially engaged, the rivet shank 1 and the rivet sleeve 2 are connected as a loosely connected whole, and the inner wall of the stop section 21 and the outer wall of the stop section 12 form a deformation-free contact, which facilitates pre-installation and insertion into the workpiece.

[0034] like Figure 4 and Figure 5 As shown, this embodiment also provides an installation method for a composite double-effect expansion threaded blind rivet, the specific steps of which are as follows: 1) With the internal thread 24 facing forward, the composite double-effect expansion threaded core rivet 100 is passed through the through hole of the riveted part 200 from the front until the stop part 21 is blocked by the edge of the through hole, thus completing the pre-installation positioning. 2) The tightening tool is fitted to the drive section 11, and a torque is applied to make the nail rod 1 rotate and move axially within the nail sleeve 2. Under the action of thread feed, the riveting deformation part 23 is squeezed to produce radial plastic deformation and forms a bulge structure 23a outward, which presses against and squeezes the reverse side of the riveted part 200. At the same time, the outer wall of the tapered expansion section 13 interacts with the inner wall of the inner tapered hole 22 and generates a radial component force, which pushes the wall of the inner tapered hole 22 to expand and deform outward, closely adhering to the hole wall of the through hole, forming a radial anti-rotation and anti-pull-out fixing structure. In the final state of riveting and locking, the stop section 12, the stop part 21, the hole wall of the riveted part 200 and the bulge 23a are in close contact in sequence, forming a reliable axial clamping and fixing.

[0035] After the riveting is in place, torque is continued to be applied to the drive section 11, and the nail rod 1 breaks under force at the neck groove 101. The drive section 11 is removed, and the rest of the nail rod 1 remains in the riveted part 200, completing the entire installation process.

[0036] The technical advantages of this invention are as follows: 1. Double fixing, reliable connection: The radial clamping of the hole wall is achieved through the matching expansion of the conical surface (anti-rotation and anti-pull-out), and the axial clamping of the workpiece is achieved through the end bulge riveting. The double fixing combined with the thread self-locking greatly improves the connection strength and anti-loosening ability of the core-pulling rivet.

[0037] 2. Highly efficient installation and easy operation: Simply insert the part into the through hole from one side of the riveted part, and the radial expansion and axial riveting are completed simultaneously with one rotational feed action. Pre-installation and positioning are simple and do not require complicated procedures, which significantly improves installation efficiency. The drive section design makes it easy to apply force with tools. After riveting, the excess part can be quickly separated through the neck groove without occupying external space.

[0038] 3. Reasonable structure and controllable deformation: The wall thickness of each part of the nail sleeve and the taper of each section of the nail rod are optimized to ensure that the riveting deformation part and the inner conical hole part deform as needed during riveting, with accurate positioning and stable locking, which can meet the installation requirements of the through hole of the riveted part.

[0039] 4. High adaptability and practicality: The drive section can adopt a variety of drive structures (internal multi-angle countersunk hole, spline shaft, etc.) to adapt to different tightening tools and meet diverse installation scenarios. The overall structure is designed as an integrated unit, which improves the service life and stability of the rivets.

[0040] The above descriptions are merely some embodiments of the present invention. Those skilled in the art can make various modifications and improvements without departing from the inventive concept of the present invention, and these all fall within the scope of protection of the present invention.

Claims

1. A composite double-effect expansion threaded blind rivet, comprising a rivet shank and a rivet sleeve through which the rivet shank passes; characterized in that: The rivet includes a stop section, a tapered expansion section, and an external thread section integrally connected in sequence along the axial direction; the outer diameter of the tapered expansion section gradually decreases towards the external thread section, and the outer diameter of the external thread section is smaller than the minimum outer diameter of the tapered expansion section; the rivet sleeve is axially hollow and includes a stop portion, an inner tapered hole portion, a riveting deformation portion, and an internal thread portion integrally connected in sequence along the axial direction; the inner wall of the inner tapered hole portion matches the taper of the outer wall of the tapered expansion section; the inner diameter of the internal thread portion is smaller than the inner diameter of the remaining positions of the rivet sleeve; the external thread section is threadedly engaged with the internal thread portion; when the rivet and the rivet sleeve are locked, the inner wall of the inner tapered hole portion is interference-fitted with the outer wall of the tapered expansion section and expands radially to tightly adhere to the hole wall of the riveted component; the inner wall of the stop portion fits against the outer wall of the stop section; and the riveting deformation portion deforms into a bulge to cooperate with the stop portion in axially clamping the riveted component.

2. The composite double-effect expansion threaded blind rivet according to claim 1, characterized in that: The wall thickness of the riveted deformation portion is equal to the minimum wall thickness of the inner tapered hole portion and less than the maximum wall thickness of the internal thread portion.

3. The composite double-effect expansion threaded blind rivet according to claim 1, characterized in that: The stop section is a tapered structure that gradually decreases in size from one end near the drive section to the other end near the tapered expansion section, and the taper of the stop section is greater than the taper of the tapered expansion section.

4. The composite double-effect expansion threaded blind rivet according to claim 1, characterized in that: The nail rod also includes a drive section connected to one end of the stop section, and a necking groove is provided at the position adjacent to the stop section.

5. The composite double-effect expansion threaded blind rivet according to claim 4, characterized in that: The drive section has an internal polygonal countersunk hole in the middle of its end face to accommodate a wrench.

6. The composite double-effect expansion threaded blind rivet according to claim 4, characterized in that: The cross-sectional shape of the drive section is a non-circular drive structure.

7. The composite double-effect expansion threaded blind rivet according to claim 5, characterized in that: The drive section is a spline shaft structure with multiple key teeth evenly distributed circumferentially.

8. A method for installing the composite double-effect expansion threaded pop rivet as described in any one of claims 1-7, characterized in that, include: 1) With the internal thread facing forward, pass the composite double-effect expansion threaded rivet through the through hole of the riveted part from the front until the stop is blocked by the edge of the through hole. 2) The rivet rod rotates and moves axially within the rivet sleeve, forcing the riveting deformation part to undergo radial plastic deformation to form a bulge structure, which squeezes the reverse side of the riveted part; at the same time, the outer wall of the tapered expansion section generates a radial component force on the inner wall of the inner tapered hole, causing the wall of the inner tapered hole to expand and deform outward, thereby tightly adhering to the hole wall of the through hole in the radial direction, forming radial fixation; at the end of the riveting, the stop section, the stop part, the hole wall of the riveted part and the bulge are tightly adhered in sequence, forming axial fixation.

9. The installation method according to claim 8, characterized in that: The initial state of the composite double-effect expansion threaded pop rivet is as follows: the external thread section and the internal thread section are initially engaged, the rivet shank and the rivet sleeve are connected to form a loosely connected whole, and the inner wall of the stop part and the outer wall of the stop section make non-deformation contact.

10. The installation method according to claim 8, characterized in that: When there is a drive section at one end of the rivet shank, torque is applied to the drive section; at the end of the riveting, the drive section is rotated to break the rivet shank at the neck groove, and the rest of the rivet shank except for the drive section remains on the riveted part.

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