High-strength steel plate self-piercing riveting device and laser pre-slotting connection method

Abstract

A high-strength steel plate self-punching riveting device and a laser pre-slotting connecting method, the self-punching riveting device comprises a C-shaped frame installed at the front end of a mechanical arm, a punch is installed at the upper end of the head of the C-shaped frame, a concave die is arranged at the lower end of the head of the C-shaped frame, and a high-strength steel plate and a plate to be riveted with the high-strength steel plate are placed on the concave die; a slide rail is arranged above the concave die through the C-shaped frame, and a laser device is arranged on the slide rail; the laser device is used to cut an annular groove in the area where the rivet is to be pierced first, then the punch drives the rivet to pierce the high-strength steel plate and the plate to be riveted with the high-strength steel plate from the annular groove, mechanical self-locking is formed, until the concave die is completely filled, the rivet stops moving, and riveting is completed. In the present application, an annular groove is opened on the upper high-strength steel plate by using the laser device before riveting, and the rivet is pierced into the slotted position during the riveting process. Since the high-strength steel plate is pre-slotted and the rivet is aligned with the slotted position, the rivet will form a fracture zone in the high-strength steel plate after being pierced, thereby improving the connection quality.

Description

Technical Field

[0001] This invention belongs to the field of automobile manufacturing technology, specifically relating to a high-strength steel plate self-piercing riveting device and a laser pre-grooving connection method. Background Technology

[0002] With conservation, green development, and circularity becoming the development trends of new automotive materials and processes, lightweighting has also become one of the important means of carbon emission reduction in the automotive industry. Related research shows that for every 100kg reduction in the overall weight of a gasoline-powered vehicle, fuel consumption can be reduced by 0.4L per 100km; for every 10kg reduction in the overall weight of an electric vehicle, the total driving range can be increased by 2.5km. Developing a multi-material hybrid application system using high-strength steel and aluminum alloys as the main materials is the medium- to long-term development goal of automotive lightweighting.

[0003] Significant differences in thermodynamic, metallurgical, and mechanical properties between dissimilar metals make joining them extremely difficult. Traditional electric welding has several shortcomings; for example, in steel-aluminum spot welding, only the aluminum melts, resulting in a hard and brittle intermetallic compound at the joint surface that is weakly resistant to shear and tensile forces. Self-piercing riveting utilizes a riveting die to insert rivets into two or more layers of sheet metal under specific pressure and speed, creating an interlock between the rivet and the sheet metal to achieve the connection. Self-piercing riveting is not only suitable for joining similar materials but can also achieve two-layer and multi-layer connections of homogeneous and dissimilar materials such as aluminum alloys, magnesium alloys, and high-strength steel, as well as polymer materials and composite materials. The riveting process has low energy consumption, no heat effect, and does not damage the coating.

[0004] However, as the proportion of high-strength steel sheets used in car bodies continues to increase, traditional self-piercing riveting suffers from problems such as rivet upsetting, failure to form self-locking, and cracking of the lower layer sheet. This is mainly related to the thickness and strength of the upper and lower sheet materials. As the strength of the steel sheet increases, its plasticity decreases, making it more difficult for the rivet to penetrate during the riveting process, increasing the resistance to deformation of the steel sheet, and thus reducing the riveting quality. Summary of the Invention

[0005] The purpose of this invention is to address the problems in the prior art by providing a self-piercing riveting device for high-strength steel plates and a laser pre-grooving connection method, which makes it easier for rivets to pierce high-strength steel plates and ensures joint quality, thereby achieving a high-quality connection.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A self-piercing riveting device for high-strength steel plates includes a C-frame mounted on the front end of a robotic arm. A punch is mounted on the upper end of the head of the C-frame, and a die is set at the lower end of the head of the C-frame. A high-strength steel plate and the plate material to be riveted to the high-strength steel plate are placed on the die. A slide rail is set above the die via the C-frame, and a laser device is set on the slide rail. The laser device first cuts an annular groove in the area where the rivet will penetrate. Then, the punch drives the rivet to penetrate the high-strength steel plate and the plate material to be riveted to the high-strength steel plate through the annular groove, forming a mechanical self-locking mechanism until the die is completely filled, the rivet stops moving, and the riveting is completed.

[0008] Furthermore, the high-strength steel plate includes DP series high-strength steel plate, and the plate that needs to be riveted to the high-strength steel plate is an aluminum alloy plate.

[0009] The aluminum alloy sheet includes any one of the 2000 series, 6000 series and 7000 series aluminum alloy sheets.

[0010] As a preferred embodiment, the tail of the punch is connected to the drive system, which is equipped with an ultrasonic system and a hydraulic cylinder. One end of the ultrasonic system is connected to the tail of the punch, and the other end is connected to the hydraulic column of the hydraulic cylinder, which drives the punch to move up and down.

[0011] As a preferred embodiment, the slide rail is arranged at an angle, allowing the laser device to move obliquely downwards to the area where the rivet is to be inserted, and to move obliquely upwards after completing the annular groove cutting, without interfering with the downward movement of the punch.

[0012] As a preferred embodiment, the slide rail is provided with two rollers at both ends. The rollers are connected to a stepper motor. The stepper motor controls the rollers by rotating forward and backward. The rollers drive the slide rail, thereby controlling the laser device to move in and out of the slide rail.

[0013] As a preferred embodiment, a die base is provided below the die, and the die is mounted on a C-frame via the die base; the robotic arm has multiple movable joints, and the tail end of the robotic arm is mounted on the robotic arm base.

[0014] A laser pre-grooving connection method based on the aforementioned high-strength steel plate self-piercing riveting device includes the following steps:

[0015] Place a high-strength steel plate and the sheet material that needs to be riveted to the high-strength steel plate on the die.

[0016] The laser device is moved along the slide rail to the area above where the rivet is to be inserted, and the robotic arm drives the laser device to pre-cut an annular groove in the area where the rivet is to be inserted.

[0017] The laser device returns along the slide rail, and the punch drives the rivet to pierce the high-strength steel plate and the plate that needs to be riveted to the high-strength steel plate through the pre-cut annular groove, forming a mechanical self-locking until the die is completely filled.

[0018] After the rivet stops moving and remains in place for a set time, the punch returns, completing the riveting process.

[0019] As a preferred option, when the laser device pre-cuts the annular groove in the area where the rivet will be inserted, the power of the laser device is 400W and the cutting depth is 0.1mm to 0.3mm.

[0020] As a preferred embodiment, when the punch drives the rivet to pierce the high-strength steel plate and the plate that needs to be riveted to the high-strength steel plate through the pre-cut annular groove, first align the rivet with the pre-cut annular groove, turn on the ultrasonic system connected to the tail of the punch, and the hydraulic cylinder continues to press the punch down so that the rivet pierces the high-strength steel plate and the plate that needs to be riveted to the high-strength steel plate. The ultrasonic power emitted by the ultrasonic system is 1kW to 5kW, and the amplitude is 3μm to 20μm. The rivet is inserted at the peak of the ultrasonic wave.

[0021] As a preferred method, after the rivet stops moving, the rivet is held in the die for 0 to 5 seconds before the punch is returned to complete the riveting.

[0022] Compared with the prior art, the present invention has at least the following beneficial effects:

[0023] For high-strength steel plates with a strength exceeding 1000 MPa, previous methods for improving the quality of self-piercing riveting connections have focused on heating the high-strength steel plate to reduce hardness and increase ductility. This invention proposes a low-power laser-induced pre-grooving self-piercing riveting device that induces fracture in high-strength steel plates. Before riveting, a laser device is used to create an annular groove in the upper layer of high-strength steel plate. During riveting, the rivet penetrates the groove. Because the groove is pre-grooved on the surface of the high-strength steel plate and the rivet is aligned with the groove, a fracture zone is formed after the rivet penetrates the plate. Compared to direct riveting, this method makes it easier for the rivet to pierce the high-strength steel plate.

[0024] Furthermore, the material to be riveted to the high-strength steel plate in this invention is an aluminum alloy plate. Due to the good thermal conductivity and the tendency of aluminum alloy to oxidize and form a protective film, spot welding is not an effective method for joining aluminum alloys. Furthermore, joining high-strength steel and aluminum alloy can lead to a chemical reaction due to their different melting points, resulting in oxide formation around the weld area. The self-piercing riveting device and laser pre-grooving connection method proposed in this invention do not consider the physical properties of aluminum alloys and do not generate oxides, thus ensuring joint quality.

[0025] Furthermore, in the self-piercing riveting device proposed in this invention, the laser device is coaxially arranged with the punch, and a forward and reverse rotating motor is provided at the end of the slide rail. The forward and reverse rotation of the motor drives the laser device to move in and out of the slide rail. After laser grooving, the laser device retracts, and the punch presses down to begin riveting. The self-piercing riveting device proposed in this invention can effectively reduce the size of the equipment and make operation more convenient.

[0026] Furthermore, the self-piercing riveting device proposed in this invention features an ultrasonic device above the punch. During the riveting process, the rivet impacts the upper sheet metal at high frequency, accelerating crack initiation and propagation under impact conditions, thus reducing the forming resistance of the upper high-strength steel sheet. The high-strength steel sheet is driven by the rivet to impact the lower aluminum alloy sheet at high frequency, resulting in localized metallurgical bonding between the two metal sheets at the contact surface. This mechanical-metallurgical dual bonding significantly improves the quality of the riveted joint. The lower aluminum alloy sheet experiences high-frequency friction with the die, using frictional heat to soften the aluminum alloy sheet, reducing the difficulty of deformation and allowing for better filling of the die. Attached Figure Description

[0027] Figure 1 A schematic diagram of the structure of the self-piercing riveting device for high-strength steel plates according to an embodiment of the present invention;

[0028] Figure 2 A partial cross-sectional schematic diagram of the self-piercing riveting device for high-strength steel plates according to an embodiment of the present invention;

[0029] Figure 3 A schematic diagram of the laser device before movement in the self-piercing riveting device for high-strength steel plates according to an embodiment of the present invention;

[0030] Figure 4 A schematic diagram of the laser device moving to the position of cutting the annular groove in the self-piercing riveting device for high-strength steel plates according to an embodiment of the present invention;

[0031] Figure 5 A schematic diagram of the laser device return and punch pressing of the high-strength steel plate self-piercing riveting device according to an embodiment of the present invention;

[0032] Figure 6 A schematic diagram of the pre-cut annular groove structure of the high-strength steel plate self-piercing riveting device according to an embodiment of the present invention;

[0033] Figure 7 A schematic diagram of the process of the punch driving the rivet to pierce the high-strength steel plate and the aluminum alloy plate through the annular groove in an embodiment of the present invention: (a) before the punch presses down; (b) the rivet pierces the high-strength steel plate; (c) the rivet pierces the two layers of plates and completely fills the die cavity; (d) the punch retracts;

[0034] In the attached diagram: 1-C-frame; 2-stepper motor; 3-slide rail; 4-robotic arm; 5-robotic arm base; 6-die base; 7-die; 8-laser device; 9-punch; 10-drive system; 11-hydraulic cylinder; 12-flange; 13-ultrasonic system; 14-hydraulic column; 15-upper high-strength steel plate; 16-lower aluminum alloy plate. Detailed Implementation

[0035] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0036] To address the problem that existing technologies cannot achieve the connection of high-strength steel plates and aluminum alloy plates while ensuring joint quality, this invention proposes a self-piercing riveting device for high-strength steel plates and a laser pre-grooving connection method.

[0037] For details, please refer to Figure 1 , Figure 2 The high-strength steel plate self-piercing riveting device proposed in this embodiment of the invention includes a C-shaped frame 1 installed at the front end of a robotic arm 4. A punch 9 is installed at the upper end of the head of the C-shaped frame 1, and a die 7 is set at the lower end of the head of the C-shaped frame 1. A high-strength steel plate and the plate material to be riveted to the high-strength steel plate are placed on the die 7. A slide rail 3 is set above the die 7 via the C-shaped frame 1, and a laser device 8 is set on the slide rail 3. The laser device 8 first cuts an annular groove in the area where the rivet will penetrate. Then, the punch 9 drives the rivet to penetrate the high-strength steel plate and the plate material to be riveted to the high-strength steel plate through the annular groove, forming a mechanical self-locking mechanism until the die 7 is completely filled, the rivet stops moving, and the riveting is completed.

[0038] Because the difficulty of rivet penetration increases during riveting, the resistance to steel plate deformation also increases, leading to a decrease in riveting quality. Therefore, improving riveting quality can be addressed by reducing the resistance of rivet penetration into the steel plate. Existing technologies for reducing rivet penetration resistance primarily include hot self-piercing riveting, which involves heating the riveting material. However, heating the area to be riveted before riveting can result in a transition phase in the hot-formed area, making it prone to cracking, generating residual stress in the surrounding area, and causing deformation of the riveting area.

[0039] The self-piercing riveting device and laser pre-grooving connection method for high-strength steel plates proposed in this invention improve upon traditional riveting methods, making them easier to operate and enabling high-quality connections between high-strength steel plates and aluminum alloys.

[0040] In one possible implementation, the high-strength steel plate in this embodiment of the invention is a DP series high-strength steel plate, and the plate that needs to be riveted to the high-strength steel plate is an aluminum alloy plate.

[0041] DP series high-strength steel plates, also known as dual-phase steel, are an advanced type of high-strength steel. They are primarily composed of ferrite and martensite, with the martensite dispersed in island-like patterns within the ferrite matrix. This unique microstructure endows DP steel with excellent mechanical properties. Key characteristics of DP steel include a low yield strength ratio, high elongation, and a rapid initial hardening rate. A low yield strength ratio means the steel can better absorb energy and delay fracture under stress, thus improving the structure's impact resistance. High elongation allows the steel to undergo significant plastic deformation under external forces without easily fracturing. A rapid initial hardening rate means the steel can quickly increase its stiffness in the early stages of stress, effectively resisting deformation.

[0042] These properties of DP steel have led to its widespread use in the automotive industry. It can be used to manufacture automotive side beams, side members, crossbeams, pillars, chassis reinforcements, fuel tank supports, and structural components, reinforcements, and crash barriers for the vehicle body. Using DP steel not only improves the strength and rigidity of automobiles but also reduces vehicle weight, improves fuel economy, and enhances vehicle safety.

[0043] Furthermore, with advancements in steel sheet performance and forming technology, DP steel is also used in the manufacture of automotive body panels, including inner and outer panels. This not only improves the appearance of automobiles but also enhances the overall rigidity and safety. In summary, DP series high-strength steel sheets, with their excellent mechanical properties and wide range of applications, have become an indispensable material in the automotive industry. With continued technological progress and process refinement, DP steel will play an even more crucial role in future automotive manufacturing.

[0044] Aluminum alloy sheets can be any of the 2000, 6000, and 7000 series. Each series has its unique composition and properties, making them suitable for different applications. 2000 series aluminum alloys (Al-Cu-Mg) are primarily composed of aluminum, copper, and magnesium, and may contain trace amounts of other elements to improve performance. They offer good strength, machinability, and corrosion resistance. Due to the presence of copper and magnesium, these alloys also exhibit excellent heat treatment performance and high mechanical properties. They are commonly used in aerospace, automotive manufacturing, construction, and machinery parts. 6000 series aluminum alloys (Al-Si-Mg) are primarily composed of aluminum, silicon, and magnesium, and may contain trace amounts of other alloying elements. They offer good weldability, corrosion resistance, machinability, and moderate strength. The addition of silicon improves the alloy's casting properties and resistance to hot cracking, while magnesium enhances its mechanical properties. 6000 series aluminum alloys are widely used in automotive bodies, marine applications, building structures, and electronic product housings. 7000 series aluminum alloys (Al-Zn-Mg-Cu) are composed of aluminum, zinc, magnesium, and copper, and may also contain trace amounts of other alloying elements to optimize performance. They possess high strength, good fatigue resistance, corrosion resistance, and machinability. These alloys also exhibit high thermal stability and low density, making them ideal for lightweight applications. 7000 series aluminum alloys are primarily used in aerospace, automotive manufacturing (especially high-performance cars and racing cars), bicycles, and sporting goods to reduce product weight and improve performance.

[0045] In one possible implementation, the tail of the punch 9 in this embodiment of the invention is connected to the drive system 10. The drive system 10 is equipped with an ultrasonic system 13 and a hydraulic cylinder 11. One end of the ultrasonic system 13 is connected to the tail of the punch 9, and the other end is connected to the hydraulic column 14 of the hydraulic cylinder 11. The hydraulic column 14 drives the punch 9 to move up and down.

[0046] In one possible implementation, the slide rail 3 of this embodiment is arranged at an angle. The laser device 8 can move obliquely downwards along the slide rail 3 to the area where the rivet is to be inserted, and can move obliquely upwards after completing the annular groove cutting, without interfering with the downward pressing movement of the punch 9. Two rollers are provided at both ends of the slide rail 3. The rollers are connected to the stepper motor 2. The stepper motor 2 controls the rollers by forward and reverse rotation. The rollers drive the slide rail 3, thereby controlling the laser device 8 to move in and out of the slide rail 3.

[0047] Preferably, in this embodiment of the invention, a die base 6 is provided below the die 7, and the die base 6 is mounted on the C-shaped frame 1. The robotic arm 4 has multiple movable joints, and the tail end of the robotic arm 4 is mounted on the robotic arm base 5.

[0048] The working process of the high-strength steel plate self-piercing riveting device in this embodiment of the invention includes:

[0049] Please see Figure 3 A 1mm thick high-strength steel plate is placed on the upper layer, and a 2mm thick aluminum alloy plate is placed on the lower layer. The two plates are then assembled and pressed together to ensure that the plates do not separate during the rivet piercing process. At this stage, the preparation phase is still underway, and the laser device 8 has not yet moved. Please refer to [link / reference]. Figure 4 Two rollers are installed at the front and rear ends of the slide rail 3. The slide rail 3 can be a belt. The stepper motor 2 controls the rollers by rotating forward and backward, thereby controlling the laser device 8 to move in and out of the slide rail 3. When the laser device 8 reaches the designated position, the stepper motor 2 stops rotating, and the robotic arm 4 drives the entire device to draw a circle, cutting an annular groove with a depth of 0.2mm. At this time, the robotic arm 4 returns to its original position, the stepper motor 2 reverses, and the laser device 8 returns along the original path of the slide rail 3. The hydraulic oil in the hydraulic cylinder 11 is pressed down, driving the punch 9 to move downward, aligning the rivet with the annular groove. Please refer to [link to relevant documentation]. Figure 5 The ultrasonic device 13 is activated, and the rivet begins to penetrate the upper plate at the peak of the ultrasonic wave, with the ultrasonic power controlled at 3kW. It continues to penetrate the lower plate until the die 7 is completely filled. The rivet then stops pressing down and remains in the die 7, with the ultrasonic wave lasting 3 seconds. After the ultrasonic wave ends, hydraulic oil flows from the high-pressure chamber to the low-pressure chamber, and the punch 9 disengages from the rivet and moves upward, ending the riveting process. During this process, the laser device 8 and the punch 9 are coaxially aligned, and the laser device's movement direction is parallel to the slide rail, thus preventing motion interference. The laser device 8 pre-cuts an annular groove on the upper high-strength steel plate, as shown in the image. Figure 6 As shown.

[0050] In this embodiment of the invention, the process of the punch driving the rivet through the annular groove to pierce through the upper high-strength steel plate 15 and the lower aluminum alloy plate 16 is as follows: Figure 7 As shown: Figure 7 As shown in (a), the upper high-strength steel plate 15 had tiny laser grooves laser-cut before the rivets were inserted. Figure 7 As shown in (b), when the punch 9 presses down, the rivet will penetrate and create a crack in the upper high-strength steel plate 15, as indicated by the marked area in the figure. The rivet will penetrate this area. Figure 7 As shown in (c), the punch 9 continues to press down, and the metal flows to the die 7 until it is completely filled, at which point the rivet legs open to form a mechanical self-locking mechanism. Figure 7 As shown in (d), punch 9 retracts, and the self-piercing riveting ends.

[0051] This invention also proposes a laser pre-cutting groove connection method based on the self-piercing riveting device for high-strength steel plates. The method utilizes a laser device 8 to pre-cut an annular groove in the area where the rivet will penetrate, and mainly includes the following steps:

[0052] Place a high-strength steel plate and the sheet material that needs to be riveted to the high-strength steel plate on the die 7;

[0053] The laser device 8 is moved along the slide rail 3 to the area above where the rivet is to be inserted. The robotic arm 4 drives the laser device 8 to pre-cut an annular groove in the area where the rivet is to be inserted. The power of the laser device 8 is 400W and the cutting depth is 0.1mm to 0.3mm.

[0054] The laser device 8 returns along the slide rail 3, and the punch 9 drives the rivet to pierce the high-strength steel plate and the plate that needs to be riveted to the high-strength steel plate through the pre-cut annular groove, forming a mechanical self-locking until the die 7 is completely filled. When the punch 9 drives the rivet to pierce the high-strength steel plate and the plate that needs to be riveted to the high-strength steel plate through the pre-cut annular groove, first align the rivet with the pre-cut annular groove, turn on the ultrasonic system 13 connected to the tail of the punch 9, and the hydraulic cylinder 11 continues to press the punch 9 down, so that the rivet pierces the high-strength steel plate and the plate that needs to be riveted to the high-strength steel plate. The ultrasonic power emitted by the ultrasonic system 13 is 1kW to 5kW, and the amplitude is 3μm to 20μm. The rivet is inserted at the peak of the ultrasonic wave.

[0055] After the rivet stops moving and remains in place for 0 to 5 seconds, the punch 9 returns, completing the riveting process.

[0056] Although preferred embodiments of the present invention have been shown and described above, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the embodiments of the present invention, the scope of protection of which is defined by the appended claims and their equivalents.

Claims

1. A self-piercing riveting device for high-strength steel plates, characterized in that, The system includes a C-frame (1) installed at the front end of the robotic arm (4), a punch (9) installed at the upper end of the head of the C-frame (1), a die (7) set at the lower end of the head of the C-frame (1), a high-strength steel plate and a plate that needs to be riveted to the high-strength steel plate are placed on the die (7); a slide rail (3) is set above the die (7) through the C-frame (1), and a laser device (8) is set on the slide rail (3); the laser device (8) first cuts an annular groove in the area where the rivet is to be pierced, and then the punch (9) drives the rivet to pierce the high-strength steel plate and the plate that needs to be riveted to the high-strength steel plate through the annular groove, forming a mechanical self-locking until the die (7) is completely filled, the rivet stops moving, and the riveting is completed; The tail of the punch (9) is connected to the drive system (10). The drive system (10) is equipped with an ultrasonic system (13) and a hydraulic cylinder (11). One end of the ultrasonic system (13) is connected to the tail of the punch (9), and the other end is connected to the hydraulic column (14) of the hydraulic cylinder (11). The hydraulic column (14) drives the punch (9) to move up and down. The slide rail (3) is arranged at an angle, and the laser device (8) can move obliquely downward through the slide rail (3) to the area where the rivet is to be inserted, and can move obliquely upward after completing the annular groove cutting, without interfering with the downward movement of the punch (9).

2. The high-strength steel plate self-piercing riveting device according to claim 1, characterized in that, The high-strength steel plate includes DP series high-strength steel plate, and the plate that needs to be riveted to the high-strength steel plate is aluminum alloy plate. The aluminum alloy sheet includes any one of the 2000 series, 6000 series and 7000 series aluminum alloy sheets.

3. The high-strength steel plate self-piercing riveting device according to claim 1, characterized in that, The slide rail (3) has two rollers at both ends. The rollers are connected to the stepper motor (2). The stepper motor (2) controls the rollers by rotating forward and backward. The rollers drive the slide rail (3) and thus control the laser device (8) to move in and out of the slide rail (3).

4. The high-strength steel plate self-piercing riveting device according to claim 1, characterized in that, A die base (6) is provided below the die (7), and the die base (6) is mounted on the C-frame (1); The robotic arm (4) has multiple movable joints, and the tail end of the robotic arm (4) is mounted on the robotic arm base (5).

5. A laser pre-grooving connection method based on the high-strength steel plate self-piercing riveting device according to claim 1, characterized in that, Includes the following steps: Place a high-strength steel plate and a plate that needs to be riveted to the high-strength steel plate on the die (7); The laser device (8) is moved along the slide rail (3) to the area where the rivet is to be inserted, and the laser device (8) is driven by the robotic arm (4) to pre-cut an annular groove in the area where the rivet is to be inserted. The laser device (8) returns along the slide rail (3), and the punch (9) drives the rivet to pierce the high-strength steel plate and the plate that needs to be riveted to the high-strength steel plate through the pre-cut annular groove, forming a mechanical self-locking until the die (7) is completely filled. After the rivet stops moving and remains in place for a set time, the punch (9) returns, completing the riveting process.

6. The laser pre-grooving connection method according to claim 5, characterized in that, When the laser device (8) pre-cuts the annular groove in the area where the rivet will be inserted, the power of the laser device (8) is 400W and the cutting depth is 0.1mm to 0.3mm.

7. The laser pre-grooving connection method according to claim 5, characterized in that, When the punch (9) drives the rivet to pierce the high-strength steel plate and the plate that needs to be riveted to the high-strength steel plate through the pre-cut annular groove, first align the rivet with the pre-cut annular groove, turn on the ultrasonic system (13) connected to the tail of the punch (9), and the hydraulic cylinder (11) continues to press the punch (9) down so that the rivet pierces the high-strength steel plate and the plate that needs to be riveted to the high-strength steel plate. The ultrasonic power emitted by the ultrasonic system (13) is 1kW to 5kW and the amplitude is 3μm to 20μm. The rivet is inserted at the peak of the ultrasonic wave.

8. The laser pre-grooving connection method according to claim 5, characterized in that, After the rivet stops moving, it stays in the die (7) for 0 to 5 seconds before the punch (9) is returned to complete the riveting.

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