High-strength steel plate self-piercing rivet nut
By introducing a toothed ring and toothed tip structure into the self-piercing rivet nut of high-strength steel plate, the problem of connection failure in the prior art is solved, and the effective riveting and anti-rotation effect of high-strength steel plate is achieved, thereby improving the reliability and durability of the connection.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- JIANGSU MINGYANG WIND POWER TECH CO LTD
- Filing Date
- 2025-07-08
- Publication Date
- 2026-06-05
AI Technical Summary
Existing high-strength steel plate self-piercing rivet nuts fail to effectively embed their teeth into steel plates with a strength of 1600MPa or higher when riveting, resulting in connection failure and inability to prevent rotation.
A high-strength steel plate self-piercing rivet nut was designed, which adopts a toothed ring and tooth tip structure. The ratio of the outer diameter of the toothed ring to the diameter of the second annular platform is 1.1~1.2, and the tooth tip is an acute angle. Combined with the arc groove design, the piercing ability is enhanced, and the internal thread is used to achieve fastening, forming a three-dimensional anti-rotation system.
It achieves effective riveting on steel plates with a strength of over 1600MPa, enhances anti-rotation capability, reduces riveting force, avoids burrs and substrate cracking, and improves the reliability and durability of the connection.
Smart Images
Figure CN224326548U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of piercing and pressing rivet nuts, and in particular to a high-strength steel plate self-piercing and pressing rivet nut. Background Technology
[0002] Ultra-high strength steel possesses excellent impact resistance and offers significant advantages in processing technology and cost, meeting the dual requirements of reducing vehicle weight and improving collision safety. Therefore, ultra-high strength steel is widely used in the manufacture of critical impact-resistant structural components of the body-in-white, such as anti-collision beams, front and rear bumpers, A-pillars, B-pillars, and various reinforcing plates. Welding is commonly used to join hot-formed steel sheets to the vehicle body. Due to the presence of the Al-Si coating on the steel sheet, welding causes the enrichment and segregation of Al elements in the weld. The Al-rich micro-regions remain as δ-ferrite after welding, severely reducing the strength of the weld joint.
[0003] Riveting, due to its lack of heat input, avoidance of material property changes, and excellent fatigue resistance and process stability, is increasingly used in the connection of hot-formed steel in body-in-white. For example, patent CN221591482U discloses a self-piercing press-fit nut suitable for GPa-grade ultra-high strength steel. Its structure includes a nut body with a central hole along the axial direction, and a key tooth platform and a self-piercing cone formed sequentially along the axial direction on the lower end face of the nut body. The key tooth platform includes multiple circumferentially spaced key teeth, with tooth grooves between adjacent key teeth. The self-piercing cone sits in an inverted cone shape on the platform of the key tooth platform between the tooth grooves and the first central hole.
[0004] However, existing technologies have some problems: because the key teeth are symmetrically distributed radially on the support surface, when riveting hot-formed steel plates with strength above 1600MPa, the key teeth cannot be embedded in the steel plate due to their size and strength factors, resulting in connection failure and failing to play the role of preventing rotation. Therefore, we propose a high-strength steel plate self-piercing press-fit nut. Utility Model Content
[0005] To address the shortcomings of existing technologies, this utility model provides a high-strength steel plate self-piercing rivet nut. By setting toothed rings and tooth tips, it can pierce steel plates with a strength of over 1600MPa, preventing rotation, providing greater riveting force, and adhering closely to the steel plate.
[0006] The purpose of this utility model is achieved as follows: A high-strength steel plate self-piercing rivet nut includes a nut body, on which a first annular platform is provided, and on which a second annular platform is provided. The nut body, the first annular platform, and the second annular platform are integrally formed. A toothed ring is provided on the outer side of the first annular platform, the gap of the toothed ring is set in an arc, and the toothed ring is provided with tooth tips. A groove is opened at the connection between the second annular platform and the first annular platform. A connecting hole is opened on the second annular platform, the connecting hole penetrates the nut body, and the interior of the connecting hole is provided with internal threads.
[0007] Optionally, the nut body is provided with an anti-loosening surface, and the nut body and the second annular platform form an anti-loosening step structure.
[0008] Optionally, the second annular platform is truncated cone-shaped, and the lower end of the second annular platform contacts the first annular platform.
[0009] Optionally, the end face of the first annular platform forms an inclined angle with the inclined surface of the second annular platform, and the first annular platform and the second annular platform form an anti-detachment step structure.
[0010] Optionally, the ratio of the outer diameter of the gear ring to the diameter of the second annular platform is between 1.1 and 1.2.
[0011] Compared with the prior art, the beneficial effects of this utility model are as follows:
[0012] By setting a toothed ring structure, the arc grooves between the teeth on the toothed ring, as well as the sharp tooth tips, penetrate the steel along the holes in the steel plate. Due to the poor fluidity of the steel plate, the toothed ring with arc grooves is more conducive to wrapping the plate. This tooth shape does not require greater riveting force, ensuring the life of the riveting die; the riveting surface of the steel plate fits effectively with the nut, and the riveting back is flat; there are no burrs on the edge of the riveting hole. Attached Figure Description
[0013] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.
[0014] Figure 1 This is a schematic diagram of the overall structure provided by this utility model.
[0015] Figure 2 This is a cross-sectional schematic diagram of the overall structure provided by this utility model.
[0016] Figure 3 This is a schematic diagram of the working state of the nut provided by this utility model.
[0017] Figure 4 This is a schematic diagram of the sheet metal punching after riveting provided by this utility model.
[0018] In the diagram: 1. Nut body; 11. Connecting hole; 12. Internal thread; 13. Anti-detachment surface; 2. First annular platform; 21. Gear ring; 22. Tooth tip; 3. Second annular platform; 31. Groove; 4. Upper die; 5. Lower die; 6. Sheet metal; 7. Punch. Detailed Implementation
[0019] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.
[0020] like Figures 1 to 4 The high-strength steel plate self-piercing rivet nut shown includes a nut body 1, a first annular platform 2 on the nut body 1, a second annular platform 3 on the first annular platform 2, the nut body 1, the first annular platform 2 and the second annular platform 3 being integrally formed, a toothed ring 21 being provided on the outer side of the first annular platform 2, a groove 31 being provided at the connection between the second annular platform 3 and the first annular platform 2, a connecting hole 11 being provided on the second annular platform 3, the connecting hole 11 penetrating the nut body 1, and an internal thread 12 being provided inside the connecting hole 11.
[0021] It should be noted that the embodiments provided by this utility model are made of ultra-high strength alloy steel by cold heading. After heat treatment, the finished product has a tensile strength of over 1500MPa, a plasticity of over 1300MPa, and a hardness of over 500HV, thus possessing good strength, plasticity, and hardness.
[0022] Furthermore, the toothed ring 21 on the outer side of the first annular platform 2 is used to enhance the anti-rotation engagement capability with the steel plate, and the groove 31 structure of the second annular platform 3 is used to optimize stress distribution and prevent the substrate from cracking during riveting. The overall structure achieves high-precision fastening through the internal thread 12 of the connecting hole 11, thereby adapting to the piercing riveting scenario of steel plates with a strength of 1600MPa or higher and improving assembly efficiency.
[0023] Specifically, the nut body 1 is provided with an anti-loosening surface 13, and the nut body 1 and the second annular platform 3 form an anti-loosening step structure. The second annular platform 3 is set in the shape of a frustum. The lower end of the second annular platform 3 contacts the first annular platform 2. The end face of the first annular platform 2 and the inclined surface of the second annular platform 3 form an inclined angle. The first annular platform 2 and the second annular platform 3 form an anti-loosening step structure.
[0024] Furthermore, the front end of the nut body adopts a two-stage step design, including a first annular platform 2 and a second annular platform 3, which together with the outer diameter of the nut body 1 form a double anti-disengagement mechanism. The first anti-disengagement step is formed by the end face of the first annular platform 2 and the outer end face of the second annular platform 3 forming an inclined angle of 30°~50°. This angle forms the first anti-disengagement step, optimizes the material flow path during puncture, causes the steel plate to be squeezed and deformed, and avoids stress concentration.
[0025] The difference between the outer diameter of the second annular platform 3 and the diameter of the nut body achieves mechanical interlocking, forming a second anti-disengagement step. Combined with the bidirectional engagement of the toothed ring 21 on the outer periphery of the first annular platform 2, a three-dimensional anti-rotation system is formed. This combined structure greatly increases the contact area between the nut and the steel plate after riveting, reducing the displacement under dynamic load. The synergistic effect of the two steps can disperse shear stress, achieving sufficient pull-out force even on high-strength steel plates, while keeping the substrate free of cracks.
[0026] Specifically, the gap of the gear ring 21 is set in an arc, and the gear ring 21 is provided with 24-40 tooth tips 22.
[0027] Furthermore, firstly, the design of the arc-shaped tooth gap makes the material flow smoother, guiding the steel plate to undergo extrusion deformation during puncture, avoiding micro-cracks in the substrate caused by stress concentration. The streamlined arc structure can reduce puncture resistance, and at the same time, the arc surface forms a continuous material filling area after riveting, significantly increasing the contact area between the tooth ring 21 and the plate, and enhancing the torsional resistance.
[0028] Secondly, the tooth tip 22 is set with an acute angle, which can ensure that it can quickly break through the oxide layer on the surface of the steel plate in the initial piercing stage. Its tip stress concentration effect can locally soften the high-strength steel material and reduce the overall pressing force. After forming, the tooth tip 22 is embedded in the plate to form a mechanical interlocking point, and the connection is prevented from loosening through the multi-point anchoring effect.
[0029] Finally, the combination of the arc gap and the sharp tooth tip 22 gives the nut body 1 excellent guidance during the piercing stage and can form a three-dimensional interlocking structure during the final forming, taking into account both installation processability and connection reliability. It is especially suitable for high-strength steel plates with coatings or paints on the surface, which can maintain the integrity of the coating and achieve long-term anti-loosening effect under vibration conditions.
[0030] Specifically, the ratio of the outer diameter of the gear ring 21 to the diameter of the second annular platform 3 is between 1.1 and 1.2.
[0031] Furthermore, according to experimental verification, if the outer diameter of the toothed ring 21 is too large, exceeding 1.2 times, the piercing resistance will increase significantly, and there may be problems such as overloading of the riveting equipment or uneven deformation of the sheet metal.
[0032] If the outer diameter of the toothed ring 21 is too small, less than 1.1 times, the engagement depth will be insufficient, affecting the connection strength.
[0033] Therefore, when the ratio of the outer diameter of the toothed ring 21 to the diameter of the second annular platform 3 is 1.1 to 1.2, a low pressing force is maintained while ensuring the engagement depth. This ratio allows the toothed ring 21 and the second annular platform 3 to work together. The toothed ring 21 is responsible for initial piercing and anti-loosening, while the second annular platform 3 provides support and restricts the material flow direction, making the extrusion deformation of the sheet metal after riveting more controllable and avoiding cracking or warping.
[0034] For example, an ultra-high strength alloy steel is selected, which, by mass percentage, consists of the following components: C: 0.35%, Si: 0.055%, Mn: 0.47%, P: 0.002%, S: 0.0004%, Cr: 1.95%, Mo: 2.44%, V: 0.40%, Ni: 0.80%, Nb: 0.1%, and the balance Fe.
[0035] Ultra-high strength steel treated with spheroidization was used to cold-forge M6 rivet nuts. After cold forging, tapping was performed, followed by a tempering heat treatment process: quenching at 1050℃ for 35 minutes followed by tempering at 550℃ for 120 minutes. After heat treatment, the rivet nuts underwent shot blasting and then zinc-aluminum coating surface treatment.
[0036] The processed rivet nuts are self-piercing riveted to 1800MPa, 1.2mm thick hot-formed steel. The riveting strength is: anti-rotation torque up to 36Nm, push-out force up to 4.2kN, airtightness meets 0.5MPa air pressure, test time 60s, no air leakage.
[0037] The above description of the embodiments is only for the purpose of helping to understand the method and core idea of this utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made to this utility model without departing from the principle of this utility model, and these improvements and modifications also fall within the protection scope of the claims of this utility model.
Claims
1. A high-strength steel plate self-piercing press-fit nut, comprising a nut body (1), characterized in that: The nut body (1) is provided with a first annular platform (2), and the first annular platform (2) is provided with a second annular platform (3). The nut body (1), the first annular platform (2) and the second annular platform (3) are integrally formed. A toothed ring (21) is provided on the outer side of the first annular platform (2). The gap of the toothed ring (21) is set in an arc. The toothed ring (21) is provided with tooth tips (22). A groove (31) is opened at the connection between the second annular platform (3) and the first annular platform (2). A connecting hole (11) is opened on the second annular platform (3). The connecting hole (11) penetrates the nut body (1). An internal thread (12) is provided inside the connecting hole (11).
2. The high-strength steel plate self-piercing rivet nut according to claim 1, characterized in that: The nut body (1) is provided with an anti-detachment surface (13), and the nut body (1) and the second annular platform (3) form an anti-detachment step structure.
3. The high-strength steel plate self-piercing rivet nut according to claim 1, characterized in that: The second annular platform (3) is arranged in the shape of a frustum, and the lower end of the second annular platform (3) is in contact with the first annular platform (2).
4. The high-strength steel plate self-piercing rivet nut according to claim 1, characterized in that: The end face of the first annular platform (2) and the inclined surface of the second annular platform (3) form an inclined angle, and the first annular platform (2) and the second annular platform (3) form an anti-detachment step structure.
5. A high-strength steel plate self-piercing rivet nut according to claim 1, characterized in that: The ratio of the outer diameter of the gear ring (21) to the diameter of the second annular platform (3) is between 1.1 and 1.2.