Laser composite rivet-free connection process for sheet material connection

Abstract

The invention provides a laser composite rivet-free connection process for sheet material connection. The laser composite rivet-free connection process comprises a laser etching treatment stage, a positioning pre-tightening stage, a preliminary forming stage, a plastic forming stage, a demolding stage and a laser heat fusion stage. Aiming at rivet-free connection preparation of a sheet material, laser etching treatment and a laser thermal fusion process are combined, so that a sheet connecting structure with higher bonding strength is obtained. According to the laser etching treatment provided by the invention, a specific micro-tissue structure is prepared at the joint of the surface of the metal substrate by using laser, so that the surface roughness of the joint is increased; according to the laser heat fusion process, the upper plate and the lower plate are locally melted and rapidly solidified at the rivet-free connection point through laser to form combination, metallurgical bonding of the connection area is further enhanced through laser heat fusion, and therefore the bonding strength of the plates in laser composite rivet-free connection is remarkably improved.

Description

Technical Field

[0001] The invention relates to the technical field of plate connection, in particular to a laser composite rivet-free connection process for connecting thin plate materials. Background Art

[0002] Commonly used metal-to-metal joining methods include riveting, bonding, and welding (thermal joining). Riveting provides higher connection strength, but may cause stress concentration, which affects the fatigue performance of the joint. Although the bonding method is easy to operate and low in cost, its reliability is poor under environmental factors such as hot and humid conditions, and the joint performance may deteriorate rapidly. In the welding process, resistance heating welding may leave heating elements inside the joint, affecting its performance; while ultrasonic welding may destroy the structure of the material inside the joint, limiting further improvement of strength. Summary of the invention

[0003] The present invention provides a laser composite rivet-free connection process for connecting thin plate materials, aiming to solve the problem that the metal connection process in the prior art has a great influence on the material properties, resulting in the inability to further improve the material properties after connection.

[0004] A laser composite rivet-free connection process for connecting thin plate materials, comprising: Step 1, laser etching treatment stage, using laser to perform laser etching treatment on the plate to be treated, and preparing a specific microstructure in the connection area; Step 2: During the positioning and pre-tightening stage, the etched plates to be processed are stacked and clamped on the mold to expose the connection area so that the connection area is located corresponding to the stamping device; Step 3: In the initial forming stage, a punching device is used to perform preliminary punching on the connection area, and the punching area is positioned so that the connection area of ​​the plate to be processed forms a mold prototype; Step 4, in the plastic forming stage, a stamping device is used to stamp the stamping area multiple times until the connection area of ​​the plate to be processed fits the mold to form a lap joint; Step 5: In the demoulding stage, the stamping device is withdrawn and the stamped sheet is taken out; Step 6, laser thermal fusion stage, for the stamped sheet, the connection point is located at the overlap joint, and laser thermal fusion treatment is performed at the connection point using a laser to achieve rivet-free connection of the thin plate material.

[0005] Furthermore, in step 1, a specific micro-texture structure is prepared in the connection area, and the micro-texture structure is a grid-like structure.

[0006] Furthermore, the grid structure is a network structure composed of a plurality of square grids; the width of the grid lines in the grid structure is 100 to 500 μm; the depth of the grid lines is 10 to 80 μm; and the spacing between adjacent parallel grid lines is 100 to 500 μm.

[0007] Furthermore, the laser power of the laser etching process is 30 to 80 W; The scanning speed of the laser etching process is 3000-5000 mm / s; The laser etching processing frequency is 200-600KHz; The laser inclination angle of the laser etching process is 10° to 30°.

[0008] Furthermore, in step 4, the length and width planes of the plate are overlapped to form a lap joint after stamping, and the area of ​​the lap joint accounts for 15-20% of the total area of ​​the plate.

[0009] Furthermore, after the plates are overlapped, a laser is used to partially melt the upper and lower plates at the connection point and quickly solidify them to form a bond.

[0010] Furthermore, the laser power of the laser thermal fusion is 400-1000W; The scanning speed of the laser thermal fusion is 2000-5000 mm / s; The laser thermal fusion frequency is 30 to 60 KHz; The laser inclination angle of the laser thermal fusion is 10° to 30°.

[0011] Furthermore, the laser path at the connection point is a circular or cross-shaped route.

[0012] The technical solution adopted by the present invention has the following beneficial effects: In the present invention, the thin plate material is combined with the preparation process of laser etching and laser thermal fusion in the process of preparing the rivetless connection, so as to obtain a plate structure with higher bonding strength. The laser etching process provided by the present invention uses laser to prepare a specific microstructure at the connection of the metal substrate surface, thereby increasing the surface roughness of the connection; the laser thermal fusion process uses laser to locally melt the upper and lower plates at the connection point and quickly solidify to form a connection. The laser thermal fusion further enhances the metallurgical bonding of the connection area, thereby significantly improving the bonding strength of the plate in the laser composite rivetless connection. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 A schematic diagram of a laser composite rivet-free connection process for connecting thin plate materials provided by the present invention; Figure 2A schematic diagram of the structure of a rivet-free connection device based on a laser composite rivet-free connection process provided by the present invention; Figure 3 A schematic diagram of a three-axis automatic clamping laser device provided by the present invention; Figure 4 A schematic diagram of a rivetless connection testing machine provided by the present invention; Figure 5 A schematic diagram of a metal sheet after forming provided by the present invention; Figure 6 This is a morphology diagram of the laser etching process and laser thermal fusion provided by the present invention. DETAILED DESCRIPTION

[0014] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

[0015] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples, but it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention rather than limiting the patent claims of the present invention.

[0016] All raw materials of the present invention have no particular limitation on their sources, and can be purchased from the market or prepared according to conventional methods known to those skilled in the art.

[0017] See also Figure 1 , a laser composite rivet-free connection process for thin plate material connection, comprising: Step 1: In the laser etching treatment stage, a laser is used to perform laser etching on the plate to be treated, and a specific microstructure is prepared in the connection area.

[0018] Among them, see Figure 6 , Figure 6 Figure a shows the structure of the laser etching process, in which a specific microstructure is prepared in the connection area. The microtexture structure is a grid structure, which is a network structure composed of multiple square grids. The width of the grid lines in the grid structure is 100 to 500 μm; the depth of the grid lines is 10 to 80 μm; and the spacing between adjacent parallel grid lines is 100 to 500 μm.

[0019] During the etching process, the laser power of the laser etching process is 30-80W; the scanning speed of the laser etching process is 3000-5000mm / s; the frequency of the laser etching process is 200-600KHz; and the laser inclination angle of the laser etching process is 10°-30°.

[0020] Step 2: During the positioning and pre-tightening stage, the etched plates to be processed are stacked and clamped on the mold to expose the connection area so that the connection area is located corresponding to the stamping device; Step 3: Initial forming stage: Use a punching device to perform initial punching on the connection area. As the upper punch continues to move downward, more of the sheet is squeezed into the lower sheet. In addition to elastic deformation, plastic deformation gradually occurs during this process. The extruded material gradually reaches the plastic deformation condition, and the sheet begins to slowly fill the lower die. Step 4: In the plastic forming stage, plastic deformation plays a major role. The punch continues to move downward, and the upper and lower sheets are completely squeezed and filled into the groove of the lower die. At this time, the punch stroke is about to reach the maximum value, and the connection area of ​​the sheet to be processed is completely filled with the die to form a lap joint. The punching force during the stamping process is 50kN, the number of stamping times is single forming, and the shape of the stamping joint is circular.

[0021] Wherein, for the overlapping of the plates, the length and width planes of the plates are overlapped, and a lap joint is formed after stamping, and the area of ​​the lap joint accounts for 15-20% of the total area of ​​the plates.

[0022] Step 5: In the demoulding stage, the stamping device is withdrawn and the stamped sheet is taken out; Step 6, laser thermal fusion stage, for the stamped sheet, the connection point is located at the overlap joint, and laser thermal fusion treatment is performed at the connection point using a laser to achieve rivet-free connection of the thin plate material.

[0023] In this example, see Figure 6 , Figure 6 Figure b shows the structure of laser thermal fusion. After the plates are overlapped, a laser is used to locally melt the upper and lower plates at the connection point and quickly solidify them to form a bond. During the fusion process, the laser power of laser thermal fusion is 400-1000W; the scanning speed of laser thermal fusion is 2000-5000mm / s; the frequency of laser thermal fusion is 30-60KHz; and the laser inclination angle of laser thermal fusion is 10°-30°.

[0024] The laser path at the connection point may be a circular, cross-shaped or any other arbitrarily set route.

[0025] In addition, in this embodiment, see Figure 2-Figure 4 The present invention also provides a rivet-free connection device based on a laser composite rivet-free connection process, the device comprising a rivet-free connection testing machine 1, a plate 2 and a three-axis automatic clamping laser device 3.

[0026] like Figure 2 and Figure 4As shown, the rivetless connection testing machine 1 includes a C-shaped frame 11, an upper punch 12, a bottom die 13, a controller 14 and a pneumatic device 15. The upper punch 12 is arranged at the upper end of the C-shaped groove of the C-shaped frame 11, and a three-axis automatic clamping laser device 3 is arranged at the bottom of the C-shaped groove. The bottom die 13 is arranged at the lower end of the C-shaped groove of the C-shaped frame 11, corresponding to the position of the upper punch 12, and is located below the three-axis automatic clamping laser device 3. The controller 14 and the pneumatic device 15 are arranged at the upper end of the C-shaped frame 11, and the output end of the pneumatic device 15 is connected to the upper punch 12.

[0027] like Figure 2 and Figure 3 As shown, the three-axis automatic clamping laser device 3 is assembled on the extension table of the rivetless connection test machine 1, including a plate positioning fixture 31, a laser emitter 32, a main machine 33, a motor 34, a Z-axis track 35, a vertical laser fixture 36, a transmission shaft 37, a Y-axis track 38, and an X-axis track 39; the plate positioning fixture 31 is arranged in the C-shaped groove of the C-shaped frame 11, and a Z-axis track 35, a Y-axis track 38, and an X-axis track 39 are arranged on one side of the plate positioning fixture 31, the X-axis track 39 is arranged on both sides of the plate positioning fixture 31, and is slidably connected to the plate positioning fixture 31, the Y-axis track 38 is arranged at the upper end of the X-axis track 39, the Z-axis track 35 is clamped on the Y-axis track 38 through a slider, the laser emitter 32 is fixed on the Z-axis track 35 through the vertical laser fixture 36, the motor 34 is arranged at the end of the X-axis track 39, and is connected to the X-axis tracks 39 on both sides through a transmission shaft 37.

[0028] The rivetless connection testing machine 1 can replace the upper punch 12 and the bottom die 13 according to different sheet materials; during the rivetless connection, the controller 14 is used to control the vertical movement of the upper punch 12.

[0029] The three-axis automatic clamping laser device 3 uses laser to perform laser etching on the unconnected plates to prepare a specific microstructure in the connection area; after the rivetless connection, laser thermal fusion is performed at the connection point.

[0030] The laser emitter 32 can adjust the laser power and the laser scanning speed through the host 33 to achieve the process of laser etching and laser thermal fusion.

[0031] In this embodiment, the length dimension of the thin plate is 80-150 mm, the width dimension is 20-50 mm, and the thickness dimension is 1.5-3 mm.

[0032] The working process of a rivet-free connection device based on laser composite rivet-free connection process is as follows: First, an untreated metal material, such as an aluminum alloy plate having a size of 110 mm x 20 mm x 1.5 mm, is mounted on the plate positioning fixture 31 .

[0033] Second, start the three-axis automatic clamping laser device 3, control the input from the host 33, adjust the laser emitter 32 to control the laser power and laser scanning speed, the laser power of the laser etching process is 60W, the scanning speed is 5000mm / s; the laser frequency is 400KHz, the laser inclination angle is 10°, and a grid-like network structure composed of multiple square grids is formed. The width of the grid line in the grid structure is 300μm; the depth of the grid line is 20μm; the spacing between adjacent parallel grid lines is 300μm; and the host 33 is used to control the laser emitter 32 to set a specific laser etching processing path, start the host 33 to control the movement of the upper plate positioning fixture 311, and perform laser etching on the lower plate. Start the host 33 to control the movement of the lower plate positioning fixture 312, perform laser etching on the upper plate and automatically flip the upper plate so that the laser etching processing areas overlap and move to the connection area.

[0034] Third, the rivetless connection testing machine 1 is started, the upper punch 12 and the bottom die 13 are replaced appropriately, and the controller 14 is used to complete the positioning pre-tightening stage, the preliminary forming stage, the plastic forming stage, and the demolding stage.

[0035] Fourth, after the rivetless connection, the three-axis automatic clamping laser device 3 is started, the input is controlled from the host 33, the laser emitter 32 is adjusted to control the laser power and the laser scanning speed, and the laser emitter 32 is controlled by the host 33 to set a specific laser thermal fusion path. The laser power of the laser thermal fusion is 600W, the laser scanning speed is 2000mm / s, the laser thermal fusion frequency is 50KHz, the laser inclination angle of the laser thermal fusion is 10°, and the laser trajectory is circular, completing the laser thermal fusion of the metal surface; completing the laser composite rivetless connection, the plate structure after the metal plate is connected is as follows Figure 5 As shown, the experiment was repeated to prepare 5 examples.

[0036] Process 2: Start the rivetless connection test machine 1, replace the upper punch 12 and the bottom die 13 appropriately, install the untreated metal material, 110 mm x 20 mm x 1.5 mm aluminum alloy plate, on the plate positioning fixture 31, move it to the connection area, and complete the rivetless connection process using the controller 14. Repeat the experiment and prepare 5 comparative examples.

[0037] Table 1 Static load strength under different processes Static load tensile tests were performed on the specimens of the two different processes to obtain the static load strength. From the comparison of the data in Table 1, it can be seen that by laser etching and preparing micro-textures, rivetless connection, laser thermal fusion treatment at the connection point, and direct rivetless connection, the average static load of the aluminum alloy joint was increased from 1142N to 2088.6N, an increase of nearly 1.82 times.

[0038] Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea, including the best mode, and also enables any technician in the field to practice the present invention, including the manufacture and use of any device or system, and the implementation of any combined method.

[0039] The present invention combines the preparation process of laser etching and laser thermal fusion in the preparation process of rivetless connection of thin plate materials, thereby obtaining a plate structure with higher bonding strength. The laser etching process provided by the present invention uses laser to prepare a specific microstructure at the connection of the metal substrate surface, thereby increasing the surface roughness of the connection; the laser thermal fusion process uses laser to locally melt the upper and lower plates at the connection point and quickly solidify to form a connection. The laser thermal fusion further enhances the metallurgical bonding of the connection area, thereby significantly improving the bonding strength of the plate in the laser composite rivetless connection.

[0040] Finally, it should be pointed out that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them. Although the present invention has been described in detail with reference to the above embodiments, a person skilled in the art should understand that the technical solutions described in the above embodiments can still be modified, or some of the technical features can be replaced by equivalents, and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A laser composite rivet-free connection process for thin plate material connection, characterized in that: include: Step 1, laser etching treatment stage, using laser to perform laser etching treatment on the plate to be treated, and preparing a specific microstructure in the connection area; Step 2: During the positioning and pre-tightening stage, the etched plates to be processed are stacked and clamped on the mold to expose the connection area so that the connection area is located corresponding to the stamping device; Step 3: In the initial forming stage, the connection area is initially punched using a punching device. As the upper punch continues to move downward, more of the sheet is squeezed into the lower sheet. In addition to elastic deformation, plastic deformation gradually occurs during this process. The extruded material gradually reaches the plastic deformation condition, and the sheet begins to slowly fill the lower die. Step 4: In the plastic forming stage, plastic deformation plays a major role. The punch continues to move downward, and the upper and lower sheets are completely squeezed and filled into the groove of the lower die. At this time, the punch stroke is about to reach the maximum value, and the connection area of ​​the sheet to be processed is completely filled with the die to form a lap joint. Step 5: In the demoulding stage, the stamping device is withdrawn and the stamped sheet is taken out; Step 6, laser thermal fusion stage, for the stamped sheet, the connection point is located at the overlap joint, and laser thermal fusion treatment is performed at the connection point using a laser to achieve rivet-free connection of the thin plate material.

2. The laser composite rivetless connection process for thin plate material connection according to claim 1 is characterized in that: In the step 1, a specific micro-texture structure is prepared in the connection area, and the micro-texture structure is a grid-like structure.

3. The laser composite rivetless connection process for thin plate material connection according to claim 2 is characterized in that: The grid structure is a network structure composed of a plurality of square grids; the width of the grid lines in the grid structure is 100-500 μm; the depth of the grid lines is 10-80 μm; and the spacing between adjacent parallel grid lines is 100-500 μm.

4. The laser composite rivetless connection process for thin plate material connection according to claim 1, characterized in that: The laser power of the laser etching process is 30 to 80 W; The scanning speed of the laser etching process is 3000-5000 mm / s; The laser etching processing frequency is 200-600KHz; The laser inclination angle of the laser etching process is 10° to 30°.

5. The laser composite rivetless connection process for thin plate material connection according to claim 1, characterized in that: In step 4, the length and width planes of the plate are overlapped, and a lap joint is formed after stamping, and the area of ​​the lap joint accounts for 15-20% of the total area of ​​the plate.

6. The laser composite rivetless connection process for thin plate material connection according to claim 1, characterized in that: After the plates are overlapped, a laser is used to locally melt the upper and lower plates at the connection point and quickly solidify them to form a bond.

7. The laser composite rivetless connection process for thin plate material connection according to claim 1, characterized in that: The laser power of the laser thermal fusion is 400-1000W; The scanning speed of the laser thermal fusion is 2000-5000 mm / s; The laser thermal fusion frequency is 30 to 60 KHz; The laser inclination angle of the laser thermal fusion is 10° to 30°.

8. The laser composite rivetless connection process for thin plate material connection according to claim 1, characterized in that: The laser path at the connection point is a circular or cross-shaped route.

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