Vacuum laser welding device and method for improving welding seam quality of shell and end cover

Abstract

The invention discloses a vacuum laser welding device and method for improving the welding seam quality of a shell and an end cover, belongs to the field of new energy equipment manufacturing, and aims to solve the problems of welding oxidation, pollution, gas interference and the like. The device comprises a cabin and a vacuum pump set which are connected, a motor is arranged on one side of the cabin, a welding rotary table is connected with an output shaft of the motor, an air cylinder is arranged on the other side of the cabin, a pressing block is rotationally arranged on a piston rod of the air cylinder, and the piston rod of the air cylinder and the output shaft of the motor are coaxially and oppositely arranged. The air cylinder sequentially and coaxially presses the end cover and the shell on the welding rotary table through the pressing block, the support is connected with the bottom of the cabin, the two rolling wheels are arranged on the lower side of the shell in parallel, and the periphery of the shell is in rolling fit with the peripheries of the two rolling wheels. Welding is conducted in the vacuum environment, oxygen and impurities in air can be effectively removed, air holes and cracks are prevented from being generated, the precision of laser energy control can be greatly improved, uniform distribution of heat input is ensured, and therefore the stability of welding forming is remarkably improved.

Description

Technical Field

[0001] The present invention belongs to the field of new energy equipment manufacturing, and particularly relates to a vacuum laser welding device and method for improving the weld quality of a housing and an end cap. Background Art

[0002] During the battery manufacturing process, welding, as a key process step, has an important impact on battery performance. Although traditional atmospheric pressure welding has advantages such as simple operation and low equipment cost, it is easily interfered by environmental factors. To prevent oxidation and improve welding quality, atmospheric pressure welding is usually supplemented with a protective gas flow. However, in actual applications, the protective gas is easily mixed with air and oxygen is involved, resulting in defects such as pores and cracks during the welding process, which in turn affect the joint tightness, structural sealing, and product reliability, and there are potential safety hazards. To solve the above problems, vacuum welding technology has gradually attracted attention. By welding in a vacuum environment, oxidation, contamination, and gas interference can be effectively avoided, and the joint quality can be improved. However, current vacuum welding is mainly applied to large-sized components, and there are still many technical challenges in its application in the field of precision parts such as battery manufacturing.

[0003] The precise welding of the housing and end cap of a full pole ear large cylindrical battery is a key difficulty in the manufacturing process of large cylindrical batteries. Currently, this process usually uses laser welding technology and realizes rotary welding with the help of a turntable to ensure the continuity of the weld. At present, the side-blowing protective gas method is mostly used during the welding process for atmosphere isolation, but this method is prone to external air mixing, which in turn causes problems such as welding defects and process instability. In actual operation, equipment vibration is relatively common, and the workpiece is inevitably subjected to uneven stress during rotation, which is likely to cause weld offset, resulting in uneven local heating in the welding area, and then forming cold joints or other local defects. At the same time, with the extension of the welding path, the weld thermal accumulation effect is significant, and local overheating further exacerbates the welding instability and defect tendency, seriously affecting the welding quality, and then restricting the comprehensive performance and service life of the product. In view of the above problems, the limitations of traditional laser welding technology are becoming increasingly apparent. Realizing the organic integration of vacuum technology and laser welding technology has become an effective way to improve the welding quality of large cylindrical housings and end caps. However, during the vacuum welding process, how to effectively protect the optical system and avoid the interference of spatter and soot on the laser transmission and focusing system is another key problem restricting the further popularization and application of this technology. Summary of the Invention

[0004] The object of the present invention is to provide a vacuum laser welding device and method for improving the weld quality of a housing / end cover. The device effectively prevents oxidation, contamination, and gas interference by constructing a vacuum environment, ensuring the purity of the weld. By adopting an integrated design of the cabin turntable, a double-end pressing mechanism with pressure self-compensation, and an elastic-rigid composite pressing block, precise positioning and rotational centering of the parts in the flat state are achieved, improving the temperature control accuracy and pressing stability, avoiding workpiece deformation, offset, and local heat accumulation, and ensuring the welding depth and sealing performance. Combining micro-airflow and electrostatic adsorption technologies effectively prevents optical path contamination, ensures the stability and safety of energy transmission, and significantly improves the stability of the welding process and the welding quality. The technical solution adopted by the present invention is as follows:

[0005] A vacuum laser welding device for improving the weld quality of a housing and an end cover, wherein the housing is a cylindrical housing of a full-tab large cylindrical battery, and the end cover is a circular plate-shaped end cover of a full-tab large cylindrical battery. The device includes a vacuum system and a motion system;

[0006] The vacuum system includes a cabin and a vacuum pump group. The cabin is a hollow member with an upper opening. A cabin door opens and closes the opening of the cabin. The cabin is connected to the vacuum pump group, and the vacuum pump group is electrically connected to a control system;

[0007] The motion system includes a welding turntable, a pressing block, and two rollers. A motor is provided on one side wall of the cabin. The output shaft of the motor extends into the cabin. The welding turntable is connected to the output shaft of the motor. A cylinder is provided on the other side wall of the cabin. The cylinder is connected to an air compressor. A pressing block is rotatably provided on the piston rod of the cylinder. The piston rod of the cylinder and the output shaft of the motor are coaxially arranged in opposite directions. The cylinder presses the end cover and the housing coaxially on the welding turntable through the pressing block in sequence. A support is provided at the bottom of the cabin through a bottom plate. The two rollers are arranged in parallel on the lower side of the housing. The two rollers are respectively rotatably engaged with the support. The outer circumference of the housing is tangentially and rotatably engaged with the outer circumferences of the two rollers.

[0008] Further, the cabin is a metal material member or a transparent non-metal material member. When the cabin is a metal material member, the wall thickness of the cabin is 5 mm to 15 mm. An observation window is provided on the side wall of the cabin, or a CCD industrial camera is installed in the cabin;

[0009] When the cabin is a transparent non-metal material member, the wall thickness of the cabin is 10 mm to 30 mm.

[0010] Further, the cabin door is a metal material member or a transparent non-metal material member. When the cabin door is a metal material member, the thickness of the cabin door is 5 mm to 15 mm. A high-transparency glass is provided on the cabin door, and the thickness of the high-transparency glass is 10 mm to 20 mm;

[0011] When the cabin door is a transparent non-metal material member, the thickness of the cabin door is 10 mm to 30 mm.

[0012] Further, the vacuum pump group is a pump group composed of multiple mechanical pumps, or a pump group composed of a mechanical pump and a Roots pump, or a pump group composed of a mechanical pump, a Roots pump and a molecular pump. The pumping efficiency of the vacuum pump group is 5 L / min to 30 L / min, so that the vacuum degree in the chamber reaches 10 -2 Pa to 10 5 Pa;

[0013] An elastic sealing ring is provided at the edge of the hatch door. After the hatch door is closed and locked, the hatch door seals the opening of the chamber through the elastic sealing ring.

[0014] Further, the control system includes a vacuum gauge, an electromagnetic switch and a PLC controller. The vacuum gauge is arranged on the chamber to measure the vacuum degree in the chamber. The electromagnetic switch opens and closes the vacuum pump group. The vacuum gauge and the electromagnetic switch are respectively electrically connected to the PLC controller. When the ambient pressure displayed by the gas vacuum gauge reaches the expected pressure, the PLC controller controls the electromagnetic switch to close the vacuum pump group, so that the pressure in the chamber tends to be stable;

[0015] Alternatively, the control system includes an air extraction switch and a pressure gauge. The pressure gauge is arranged on the chamber. When the pressure gauge reaches the expected pressure, the vacuum pump group is closed by closing the air extraction switch, so that the pressure in the chamber tends to be stable.

[0016] Further, the side of the welding turntable facing the cylinder is the working end face. A cylindrical groove is provided on the working end face of the welding turntable. The cylindrical groove is inserted and matched with one end of the housing to achieve precise positioning of the housing. The diameter of the cylindrical groove is 46 mm to 46.5 mm, and the depth of the cylindrical groove is 5 mm to 15 mm.

[0017] Further, the pressing block is a cylindrical member. The diameter of the pressing block is 35 mm to 42 mm. The side of the pressing block facing the motor is the working end face. A spacer is provided on the working end face of the pressing block. The spacer is composed of a number of alternately distributed metal units and rubber units. A cooling channel is opened in the pressing block.

[0018] Further, the motor is electrically connected to a speed controller;

[0019] The roller is a rubber wheel. The length of the roller is 30 mm to 50 mm, and the diameter of the roller is 10 mm to 20 mm;

[0020] A pressure sensor is provided between the welding turntable and the motor. The measurement range of the pressure sensor is 0 N to 500 N. An electromagnetic valve is provided between the cylinder and the air compressor. The electromagnetic valve and the pressure sensor are respectively electrically connected to the PLC controller;

[0021] On both sides of the cabin body below the cabin door, there are an intake slit and an extraction slit respectively. The intake slit is connected to an inert gas cylinder, and an inert protective gas is provided inside the inert gas cylinder. The extraction slit is connected to an extraction device;

[0022] The top of the cabin body is provided with an electrostatic adsorption layer.

[0023] The present invention also provides a method for improving the welding quality of the shell and the end cover, which is realized relying on the above-mentioned vacuum laser welding device for improving the welding quality of the shell and the end cover, and includes the following steps:

[0024] Step 1: Assemble one end of the shell with the end cover. Place the other end of the shell in the groove of the welding turntable, and make the lower side of the outer periphery of the shell tangent to the outer peripheries of the two rollers respectively. Adjust the position of the pressing block so that the cylinder presses the end cover and the shell coaxially on the welding turntable through the pressing block in sequence. The pressing force output by the cylinder is 50N - 150N;

[0025] Step 2: Close the cabin door, start the vacuum pump group, and within 3s - 10s, make the vacuum degree in the cabin body be 10 -2 Pa - 10 5 Pa;

[0026] Step 3: Adjust the position of the laser head so that the laser head is directly above the high-transmission glass of the cabin door made of metal material, or above the cabin door made of transparent non-metal material, so that the laser spot passes through the high-transmission glass and falls on the connection part to be welded of the shell and the end cover, or directly passes through the transparent cabin door and falls on the connection part to be welded of the shell and the end cover;

[0027] Step 4: Adjust the laser welding parameters so that the laser power is 600W - 1800W, the laser defocus amount is +1mm - +4mm. Start the welding turntable. After the rotation speed reaches the preset value, open the inert gas cylinder and the extraction device, and turn on the laser to perform laser welding on the shell and the end cover.

[0028] Furthermore, the laser head described in Step 3 is any one of a conventional welding head, a swing welding head, and a galvanometer welding head:

[0029] The laser spot described in Step 3 is any one of a Gaussian spot, a double focus, a rectangular spot, and an adjustable ring core spot;

[0030] The laser described in Step 4 is any one of an infrared laser, a fiber laser, a semiconductor laser, a disk laser, and a CO2 laser;

[0031] The rotation speed described in Step 4 is set according to the welding speed of 250mm / s - 500mm / s;

[0032] If the laser head has a swinging function, in step 4, the swinging amplitude of the laser welding parameters is set to 0.1 mm to 0.3 mm, the swinging frequency is 200 Hz to 600 Hz, and the swinging mode is any one of circular, linear, infinite, and figure-eight shapes.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] By performing welding in a vacuum environment, not only can oxygen and impurities in the air be effectively excluded to prevent the generation of pores and cracks, but also the accuracy of laser energy control can be significantly improved to ensure uniform distribution of heat input, thereby significantly enhancing the stability of welding formation. Through the self-compensation of the top pressure of the workpiece to be welded and the design of the flexible-rigid composite pressing block, the temperature control accuracy near the welding area is enhanced, the stability of part pressing during welding is improved, and the problems of weld offset and local overheating caused by environmental interference and equipment vibration are effectively alleviated, ensuring the continuity and tightness of the welded joint. The air curtain barrier can effectively avoid the interference and pollution of smoke and splash to the optical transmission system. In addition, the diverse optional technologies make the real-time monitoring and parameter regulation of the welding process more convenient, realizing the rapid establishment and stable control of a high-vacuum environment, thereby significantly enhancing the welding depth and overall welding quality. These technical advantages not only improve production efficiency but also provide a solid guarantee for the safety and reliability of the full-tab large cylindrical battery, showing good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is a schematic structural diagram of the device of the present invention;

[0036] Figure 2 is a welding effect diagram of the housing and the end cover of Example 1 of the present invention;

[0037] Figure 3 is a welding effect diagram of the housing and the end cover of Example 2 of the present invention.

[0038] In the figure, 11. Control system, 12. Vacuum pump group, 13. Cabin body, 14. Cabin door, 15. High-transparency glass, 21. Motor, 22. Welding turntable, 23. Roller, 24. Support, 25. Base plate, 26. Pressing block, 27. Cylinder, 28. Air compressor, 3. End cover, 4. Housing. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0039] To make the objectives, technical solutions, and advantages of the present invention clearer and more understandable, the present invention will be described below through specific embodiments shown in the drawings. However, it should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, the descriptions of well-known structures and technologies are omitted to avoid unnecessarily confusing the concepts of the present invention.

[0040] The connections mentioned in the present invention are divided into fixed connections and detachable connections. The fixed connections, i.e., non-detachable connections, include but are not limited to conventional fixed connection methods such as hemming connection, rivet connection, bonding connection, and welding connection. The detachable connections include but are not limited to conventional disassembly methods such as bolt connection, snap connection, pin connection, and hinge connection. When the specific connection method is not clearly defined, it is default that at least one connection method can be found among the existing connection methods to achieve this function, and those skilled in the art can select according to their needs. For example: welding connection is selected for fixed connection, and bolt connection is selected for detachable connection.

[0041] The following will further elaborate on the present invention in conjunction with the accompanying drawings. The following embodiments are explanations of the present invention, and the present invention is not limited to the following embodiments.

[0042] Embodiment 1: As Figures 1 to 3 shown, a vacuum laser welding device for improving the weld quality of a housing and an end cap, wherein the housing 4 is a cylindrical housing 4 of a full-tab large cylindrical battery, and the end cap 3 is a circular plate-shaped end cap 3 of a full-tab large cylindrical battery. The device includes a vacuum system and a motion system, which cooperate with each other to achieve high-quality welding of the housing 4 and the end cap 3 of the full-tab large cylindrical battery;

[0043] The vacuum system includes a chamber 13 and a vacuum pump group 12. The chamber 13 is a hollow member with an upper opening. A chamber door 14 opens and closes the opening of the chamber 13. The chamber 13 is connected to the vacuum pump group 12. After the chamber door 14 is closed, a closed environment can be formed with the chamber 13. A gas connector is provided on the side wall of the chamber 13 for docking with the vacuum pump group 12. The chamber 13 can be evacuated by the vacuum pump group 12 to create a high-airtightness and controllable welding environment to ensure the isolation of oxygen and other impurities during the welding process. The vacuum pump group 12 is electrically connected to the control system 11;

[0044] The motion system includes a welding turntable 22, a pressing block 26, and two rollers 23. A motor 21 is provided on one side wall of the cabin body 13. The output shaft of the motor 21 extends into the cabin body 13. The welding turntable 22 is connected to the output shaft of the motor 21. A cylinder 27 is provided on the other side wall of the cabin body 13. The cylinder 27 is connected to an air compressor 28. The input air pressure range of the cylinder 27 is 0.1 MPa to 1 MPa. A pressing block 26 is rotatably arranged on the piston rod of the cylinder 27. The pressing block 26 is rotationally matched with the piston rod of the cylinder 27 through a thrust bearing. The piston rod of the cylinder 27 and the output shaft of the motor 21 are coaxially arranged in opposite directions. The cylinder 27 presses the end cap 3 and the housing 4 coaxially onto the welding turntable 22 in sequence through the pressing block 26. The support 24 is arranged at the bottom of the cabin body 13 through a bottom plate 25. The two rollers 23 are arranged in parallel on the lower side of the housing 4. The two rollers 23 are respectively rotationally matched with the support 24. The outer circumference of the housing 4 is in rolling contact with the outer circumferences of the two rollers 23 in a tangential manner. Through the multi-mechanism linkage of the motion system, the precise positioning and fixing of the housing 4 and the end cap 3 of the full-tab large cylindrical battery are realized, and the efficient coordination of the movements of each component during the welding process is ensured.

[0045] The cabin body 13 is a metal material component or a transparent non-metal material component. When the cabin body 13 is a metal material component, such as carbon steel, stainless steel, superalloy, etc., the wall thickness of the cabin body 13 is 5 mm to 15 mm. An observation window is provided on the side wall of the cabin body 13 for observing various phenomena during the welding process and taking corresponding measures. Or, a CCD industrial camera is installed inside the cabin body 13 for observing various phenomena during the welding process and taking corresponding measures.

[0046] When the cabin body 13 is a transparent non-metal material component, such as acrylic, etc., the wall thickness of the cabin body 13 is 10 mm to 30 mm. Various phenomena during the welding process can be directly observed through the transparent cabin body 13 and corresponding measures can be taken.

[0047] The cabin door 14 is a metal material component or a transparent non-metal material component. When the cabin door 14 is a metal material component, such as carbon steel, stainless steel, superalloy, etc., the thickness of the cabin door 14 is 5 mm to 15 mm. A high-transparency glass 15 is provided on the cabin door 14. The thickness of the high-transparency glass 15 is 10 mm to 20 mm, which is used to ensure the normal incidence of the laser.

[0048] When the cabin door 14 is a transparent non-metal material component, such as acrylic, etc., the thickness of the cabin door 14 is 10 mm to 30 mm, so that the laser can directly enter through the cabin door 14 for welding the housing 4 and the end cap 3.

[0049] The vacuum pump set 12 can be a pump set composed of multiple mechanical pumps, or a pump set composed of a mechanical pump and a Roots pump, or a pump set composed of a mechanical pump, a Roots pump and a molecular pump according to different actual vacuum degree requirements. The pumping efficiency of the vacuum pump set 12 is 5 L / min to 30 L / min, so that the vacuum degree in the cabin 13 reaches 10 -2 Pa to 10 5 Pa;

[0050] An elastic sealing ring is provided at the edge of the cabin door 14. After the cabin door 14 is closed and locked, the cabin door 14 seals the opening of the cabin 13 through the elastic sealing ring, which can fully isolate the entry of external air.

[0051] The control system 11 includes a vacuum gauge, an electromagnetic switch and a PLC controller. The vacuum gauge is arranged on the cabin 13 and is used to measure the vacuum degree in the cabin 13. The electromagnetic switch opens and closes the vacuum pump set 12. The vacuum gauge and the electromagnetic switch are respectively electrically connected to the PLC controller. When the ambient pressure displayed by the air vacuum gauge reaches the expected pressure, the PLC controller controls the electromagnetic switch to close the vacuum pump set 12, so that the pressure in the cabin 13 tends to be stable;

[0052] Alternatively, the control system 11 includes an air extraction switch and a pressure gauge. The pressure gauge is arranged on the cabin 13. When the pressure gauge reaches the expected pressure, the vacuum pump set 12 is closed by closing the air extraction switch, so that the pressure in the cabin 13 tends to be stable.

[0053] The side of the welding turntable 22 facing the cylinder 27 is the working end face. A cylindrical groove is provided on the working end face of the welding turntable 22. The cylindrical groove is inserted and matched with one end of the housing 4 to realize the precise positioning of the housing 4. The diameter of the cylindrical groove is 46 mm to 46.5 mm, and the depth of the cylindrical groove is 5 mm to 15 mm.

[0054] The pressing block 26 is a cylindrical member. The diameter of the pressing block 26 is 35 mm to 42 mm. The side of the pressing block 26 facing the motor 21 is the working end face. A spacer is provided on the working end face of the pressing block 26. The spacer is composed of several alternately distributed metal units and rubber units, forming an elastic-rigid composite design. The metal units can select materials such as aluminum and copper with high thermal conductivity for the rapid conduction of local heat during welding. The rubber units can be selected as high-temperature-resistant rubbers such as silicone rubber or fluororubber. While providing flexible support and avoiding uneven stress, it avoids the melting of the rubber. The several metal units and rubber units can be alternately distributed in any way such as concentric circles or grids. A cooling channel is opened in the pressing block 26, and cooling liquid can be introduced during the welding process to effectively cool the welding area, equalize the temperature distribution, and avoid local overheating.

[0055] The motor 21 is electrically connected to the speed controller, and the speed controller controls the speed range of the motor 21 to be 0 r / min to 1000 r / min;

[0056] The roller 23 is a wheel made of soft material such as rubber. The length of the roller 23 is 30 mm to 50 mm, and the diameter of the roller 23 is 10 mm to 20 mm;

[0057] A pressure sensor is provided between the welding turntable 22 and the motor 21, which can feedback the pressing force between the large cylindrical battery case 4 and the end cover 3. The measurement range of the pressure sensor is 0 N to 500 N. An electromagnetic valve is provided between the air cylinder 27 and the air compressor 28. The electromagnetic valve and the pressure sensor are respectively electrically connected to the PLC controller. The pressure sensor collects data and gives real-time feedback to realize the adaptive adjustment of the pressing force of the pressing block 26. When detecting workpiece deformation or vibration, the pressure compensation is automatically adjusted to ensure that the top pressure received by the case 4 and the end cover 3 is uniform and constant and the welding process is stable;

[0058] On both sides of the cabin body 13, 3 mm to 5 mm below the cabin door 14, an air intake slit and an air extraction slit are respectively provided. The air intake slit is connected to an inert gas cylinder, and the inert gas cylinder is filled with an inert protective gas. The inert protective gas is any one of argon, helium and nitrogen. The air extraction slit is connected to an air extraction device. The inert protective gas enters the cabin body 13 through the air intake slit and forms an air curtain barrier to prevent the attachment of welding fumes to the protective lens. The air extraction device continuously extracts the inert protective gas and the welding fumes. The inlet air flow rate and the extraction air flow rate of the inert protective gas are generally 2 L / min - 3 L / min;

[0059] The top of the cabin body 13 is provided with an electrostatic adsorption layer, which can adsorb the residual particles in the welding fumes and avoid optical path pollution.

[0060] Embodiment 2: As Figures 1 to 3 shown, a method for improving the weld quality of the case and the end cover is realized by relying on the vacuum laser welding device for improving the weld quality of the case and the end cover described in Embodiment 1, and includes the following steps:

[0061] Step 1: Assemble one end of the case 4 with the end cover 3, place the other end of the case 4 in the groove of the welding turntable 22, and make the lower side of the outer circumference of the case 4 tangent to the outer circumferences of the two rollers 23 respectively. Adjust the position of the pressing block 26 so that the air cylinder 27 presses the end cover 3 and the case 4 coaxially on the welding turntable 22 through the pressing block 26 in sequence. The pressing force output by the air cylinder 27 is 50 N to 150 N;

[0062] Step 2: Close the cabin door 14 and start the vacuum pump group 12. Within 3 s to 10 s, make the vacuum degree in the cabin body 13 be 10 - 2 Pa to 105 Pa;

[0063] Step 3: Adjust the position of the laser head so that the laser head is directly above the high-transparency glass 15 of the hatch 14 of the metallic material or above the hatch 14 of the transparent non-metallic material, and make the laser spot pass through the high-transparency glass 15 and fall on the connection part to be joined between the housing 4 and the end cap 3, or directly pass through the transparent hatch 14 and fall on the connection part to be joined between the housing 4 and the end cap 3;

[0064] Step 4: Adjust the laser welding parameters so that the laser power is 600W - 1800W, the laser defocus amount is +1mm - +4mm. Start the welding turntable 22. After the rotational speed reaches the preset value, open the inert gas cylinder and the air extraction device, and turn on the laser to perform laser welding on the housing 4 and the end cap 3.

[0065] The laser head described in Step 3 is any one of a conventional welding head, a swing welding head, and a galvanometer welding head:

[0066] The laser spot described in Step 3 is any one of a Gaussian spot, a double focus, a rectangular spot, and an adjustable ring core spot;

[0067] The laser described in Step 4 is any one of an infrared laser, a fiber laser, a semiconductor laser, a disk laser, and a CO2 laser;

[0068] The rotational speed described in Step 4 is set according to the welding speed of 250mm / s - 500mm / s;

[0069] If the laser head has a swing function, then in Step 4, the swing amplitude of the laser welding parameters is set to 0.1mm - 0.3mm, the swing frequency is 200Hz - 600Hz, and the swing mode is any one of circular, linear, infinite, and figure-eight shapes, so as to improve the adaptability to processing errors.

[0070] The main advantages of the present invention are as follows: By performing welding in a vacuum environment, not only can oxygen and impurities in the air be effectively excluded to prevent the generation of pores and cracks, but also the accuracy of laser energy control can be significantly improved to ensure uniform distribution of heat input, thereby remarkably enhancing the stability of welding formation. Through the self-compensation of the top pressure on the workpiece to be welded and the design of the flexible-rigid composite pressing block 26, the temperature control accuracy near the welding area is enhanced, the stability of part pressing during welding is improved, and the problems of weld offset and local overheating caused by environmental interference and equipment vibration are effectively alleviated, ensuring the continuity and tightness of the welded joint. The air curtain barrier can effectively avoid the interference and pollution of smoke and spatter to the optical transmission system. In addition, the diverse optional technologies make the real-time monitoring and parameter regulation of the welding process more convenient, realizing the rapid establishment and stable control of a high-vacuum environment, thereby significantly enhancing the welding depth and overall welding quality. These technical advantages not only improve production efficiency but also provide a solid guarantee for the safety and reliability of full-tab large cylindrical batteries, showing good application prospects.

[0071] The present invention will be further described below with reference to examples:

[0072] Example 1: According to the actual working condition requirements, the housing 4 is the housing of a 4680 series large cylindrical battery, and the end cap 3 is the current collector plate of a 4680 series large cylindrical battery. Among them, the diameter of the housing 4 is 46 mm, the length is 80 mm, the thickness is 0.5 mm, and the material is stainless steel; the diameter of the end cap 3 is 46 mm, the thickness is 0.5 mm, and the material is stainless steel. The specific implementation scheme is as follows:

[0073] The cabin 13 is made of stainless steel, and the wall thickness of the cabin 13 is 10 mm. An observation window is opened on the side wall of the cabin 13 for observing various phenomena during the welding process and taking corresponding measures. A gas joint is provided on the side wall of the cabin 13 for connecting to the vacuum pump group 12 to evacuate the air in the cabin 13 and create a vacuum environment inside the cabin. The cabin door 14 is made of stainless steel, and its thickness is 10 mm. A high-transmission glass 15 is integrated on the top of the cabin door 14, and the thickness of the high-transmission glass 15 is 10 mm, which is used to ensure the normal incidence of the laser. The vacuum pump group 12 is a pump group composed of a mechanical pump and a Roots pump, and the pumping efficiency of the vacuum pump group 12 is set to 10 L / min, which can achieve the control of the vacuum degree within the range of 10 -1 ~10 5 Pa. The control system 11 is composed of an air extraction switch and a pressure gauge. When the pressure gauge reaches the expected pressure, the air extraction switch is closed to make the pressure inside the cabin tend to be stable.

[0074] The described welding turntable 22 is driven by a stepper motor and is equipped with a speed controller, with a speed range of 0 - 800 r / min. The input air pressure range of the cylinder 27 is 0.1 - 1 MPa. By connecting an external air compressor 28, the input air pressure of the cylinder 27 is adjusted to achieve the pressing of the large cylindrical battery case 4 and the end cover 3. The groove diameter of the welding turntable 22 is 46.1 mm, and the groove depth is 10 mm. The length of the roller 23 is 40 mm, and the diameter is 15 mm. The diameter of the pressing block 26 is 40 mm.

[0075] The steps of the usage method are as follows:

[0076] Step 1: Assemble one end of the case 4 with the end cover 3. Place the other end of the case 4 in the groove of the welding turntable 22, and make the lower side of the outer circumference of the case 4 tangent to the outer circumferences of the two rollers 23 respectively. Adjust the position of the pressing block 26 so that the cylinder 27 presses the end cover 3 and the case 4 coaxially on the welding turntable 22 through the pressing block 26. The pressing force output by the cylinder 27 is 100 N.

[0077] Step 2: Close the hatch 14 and start the vacuum pump group 12. Make the vacuum degree in the cabin 13 reach 10 Pa within 5 s.

[0078] Step 3: Adjust the position of the laser head so that the laser head is directly above the high - permeability glass 15 of the hatch 14 made of metal material, or above the hatch 14 made of transparent non - metal material, so that the laser spot passes through the high - permeability glass 15 and falls on the connection part to be welded of the case 4 and the end cover 3, or directly passes through the transparent hatch 14 and falls on the connection part to be welded of the case 4 and the end cover 3.

[0079] Step 4: Adjust the laser welding parameters so that the laser power is 1200 W and the laser defocus amount is +2 mm. Start the welding turntable 22. After the speed reaches the preset value, open the inert gas cylinder and the pumping device, and turn on the laser to perform laser welding on the case 4 and the end cover 3.

[0080] The laser head described in Step 3 is a conventional welding head, and the laser spot is a Gaussian spot. The laser used in Step 4 is a conventional infrared laser with a wavelength of 1064 nm. The speed is set according to a welding speed of 300 mm / s.

[0081] By observing the welding process, it can be clearly found that when using the vacuum laser welding device and method of the present invention, compared with atmospheric pressure welding, the spatter and plasma phenomena are significantly reduced, there is no obvious blackening on the weld surface, as Figure 2 and the penetration depth and weld width are uniform. This fully proves that this technology has obvious advantages in improving the weld quality of the large cylindrical battery case 4 and the end cover 3.

[0082] Example 2: According to the actual working condition requirements, the housing 4 is the housing of a 4680 series large cylindrical battery, and the end cover 3 is the current collector plate of a 4680 series large cylindrical battery. Among them, the diameter of the housing is 46 mm, the height is 80 mm, the thickness is 0.5 mm, and the material is stainless steel; the diameter of the end cover 3 is 46 mm, the thickness is 0.5 mm, and the material is stainless steel. The specific implementation plan is as follows:

[0083] The cabin 13 is made of acrylic, and the thickness of the cabin wall of the cabin 13 is 20 mm. Various phenomena during the welding process can be directly observed, and corresponding measures can be taken. A gas joint is provided on the side wall of the cabin 13 for docking with the vacuum pump group 12 to evacuate the air in the cabin 13 and create a vacuum environment inside the cabin. The cabin door 14 is made of acrylic, and its thickness is 20 mm. The laser can directly penetrate the cabin door 14 for incidence. The vacuum pump group 12 is a pump group composed of a mechanical pump, a Roots pump, and a molecular pump. The pumping efficiency of the vacuum pump group 12 is set to 30 L / min, and the vacuum degree can be controlled within the range of 10 -2 ~10 5 Pa. The control system 11 includes a vacuum gauge, an electromagnetic switch, and a PLC controller. When the pressure gauge reaches the expected pressure, the PLC controller shuts down the vacuum pump group 12 to make the pressure inside the cabin tend to be stable.

[0084] The welding turntable 22 is driven by a servo motor and is equipped with a speed controller, and the speed range is 0~1000 r / min. The input air pressure range of the cylinder 27 is 0.1~1 MPa. By connecting an external air compressor 28, the input air pressure of the cylinder 27 is adjusted to realize the pressing of the large cylindrical battery housing 4 and the end cover 3. The groove diameter of the welding turntable 22 is 46.05 mm, and the groove depth is 15 mm. The length of the roller 23 is 50 mm, and the diameter is 20 mm. The diameter of the pressing block 26 is 42 mm.

[0085] The steps of the usage method are as follows:

[0086] Step 1: Assemble one end of the housing 4 with the end cover 3. Place the other end of the housing 4 in the groove of the welding turntable 22, and make the lower side of the outer circumference of the housing 4 tangent to the outer circumferences of the two rollers 23 respectively. Adjust the position of the pressing block 26 so that the cylinder 27 presses the end cover 3 and the housing 4 coaxially on the welding turntable 22 through the pressing block 26. The pressing force output by the cylinder 27 is 120 N;

[0087] Step 2: Close the cabin door 14 and start the vacuum pump group 12. Within 10 s, make the vacuum degree in the cabin 13 reach 10 -2 Pa;

[0088] Step 3: Adjust the position of the laser head so that the laser head is directly above the high-transparency glass 15 of the hatch 14 of the metal material, or above the hatch 14 of the transparent non-metal material, so that the laser spot passes through the high-transparency glass 15 and falls on the connection area between the housing 4 and the end cover 3, or directly passes through the transparent hatch 14 and falls on the connection area between the housing 4 and the end cover 3;

[0089] Step 4: Adjust the laser welding parameters so that the laser power is 1200W and the laser defocus amount is +2mm. Start the welding turntable 22. After the rotation speed reaches the preset value, open the inert gas cylinder and the air extraction device, and turn on the laser to perform laser welding on the housing 4 and the end cover 3.

[0090] The laser head described in Step 3 is a swing-type welding head, and the laser spot is an adjustable ring-core spot. The laser used in Step 4 is a conventional infrared laser with a wavelength of 1064nm. The rotation speed is set according to a welding speed of 500mm / s, the swing amplitude is 0.2mm, and the swing frequency is 500Hz.

[0091] By comparing the normal-pressure welding process, it can be observed that vacuum laser welding has the following significant advantages: First, the spatter and plasma phenomena generated during the welding process are significantly reduced; Second, the surface quality of the weld is significantly improved, and no obvious blackening phenomenon is observed, such as Figure 3 ; Third, the weld formation is more uniform, and the consistency of the penetration depth and the weld width is significantly improved. The comparison results with Example 1 show that by increasing the vacuum degree and optimizing the matching of the corresponding welding parameters, not only the welding quality can be ensured, but also the welding efficiency can be further improved. These experimental phenomena fully prove that the vacuum laser welding device and its usage method for the large cylindrical battery housing and the end cover proposed by the present invention have significant advantages in terms of welding quality and efficiency.

[0092] The above embodiments are only illustrative descriptions of the present invention and do not limit its protection scope. Those skilled in the art can also make partial changes to it, as long as they do not exceed the spiritual essence of the present invention, they are within the protection scope of the present invention.

Claims

1. A vacuum laser welding device for improving the quality of the weld seams of a shell and an end cover, wherein the shell (4) is a cylindrical shell (4) of a large cylindrical battery with full tabs, and the end cover (3) is a circular plate-shaped end cover (3) of a large cylindrical battery with full tabs, characterized in that: The device includes a vacuum system and a motion system; The vacuum system comprises a cabin (13) and a vacuum pump group (12); the cabin (13) is a hollow component with an upper opening; a cabin door (14) opens and closes the opening of the cabin (13); the cabin (13) is connected to the vacuum pump group (12); and the vacuum pump group (12) is electrically connected to the control system (11); The motion system comprises a welding turntable (22), a pressure block (26) and two rollers (23); a motor (21) is provided on a wall of one side of the cabin (13); an output shaft of the motor (21) extends into the cabin (13); the welding turntable (22) is connected to the output shaft of the motor (21); a cylinder (27) is provided on a wall of the other side of the cabin (13); the cylinder (27) is connected to an air compressor (28); a pressure block (26) is rotatably provided on a piston rod of the cylinder (27); and the cylinder (27) The piston rod is coaxially arranged with the output shaft of the motor (21) and faces each other, the cylinder (27) sequentially coaxially presses the end cover (3) and the housing (4) onto the welding turntable (22) through the pressing block (26), the support (24) is arranged at the bottom of the cabin (13) through the bottom plate (25), the two rollers (23) are arranged in parallel on the lower side of the housing (4), the two rollers (23) are respectively rotatably matched with the support (24), and the outer periphery of the housing (4) is respectively tangentially rolling matched with the outer peripheries of the two rollers (23).

2. A vacuum laser welding device for improving the quality of the weld between the shell and the end cover according to claim 1, characterized in that: The cabin (13) is a metal material component or a transparent non-metal material component. When the cabin (13) is a metal material component, the thickness of the cabin wall of the cabin (13) is 5 mm to 15 mm, and an observation window is provided on the side wall of the cabin (13), or a CCD industrial camera is installed in the cabin (13); When the cabin body (13) is a transparent non-metallic material component, the thickness of the cabin wall of the cabin body (13) is 10 mm to 30 mm.

3. A vacuum laser welding device for improving the quality of the weld seams between the shell and the end cover according to claim 2, characterized in that: The hatch door (14) is a metal material component or a transparent non-metal material component. When the hatch door (14) is a metal material component, the thickness of the hatch door (14) is 5 mm to 15 mm. The hatch door (14) is provided with a high-transmittance glass (15), and the thickness of the high-transmittance glass (15) is 10 mm to 20 mm. When the hatch door (14) is a transparent non-metallic material component, the thickness of the hatch door (14) is 10 mm to 30 mm.

4. A vacuum laser welding device for improving the quality of the weld seams between the shell and the end cover according to claim 3, characterized in that: The vacuum pump group (12) is a pump group composed of multiple mechanical pumps, or a pump group composed of a mechanical pump and a Roots pump, or a pump group composed of a mechanical pump, a Roots pump and a molecular pump. The vacuum pump group (12) has a suction efficiency of 5L / min to 30L / min, so that the vacuum degree in the cabin (13) reaches 10 -2 Pa~10 5 Pa; An elastic sealing ring is provided at the edge of the hatch door (14); after the hatch door (14) is closed and locked, the hatch door (14) seals the opening of the cabin body (13) through the elastic sealing ring.

5. A vacuum laser welding device for improving the quality of the weld seams between the shell and the end cover according to claim 4, characterized in that: The control system (11) comprises a vacuum gauge, an electromagnetic switch and a PLC controller. The vacuum gauge is arranged on the cabin (13) and is used to measure the vacuum degree in the cabin (13). The electromagnetic switch starts and stops the vacuum pump group (12). The vacuum gauge and the electromagnetic switch are respectively electrically connected to the PLC controller. When the ambient pressure displayed by the vacuum gauge reaches the expected pressure, the PLC controller controls the electromagnetic switch to turn off the vacuum pump group (12), so that the pressure in the cabin (13) tends to be stable. Alternatively, the control system (11) comprises an air extraction switch and a pressure gauge, wherein the pressure gauge is arranged on the cabin (13), and when the pressure gauge reaches an expected pressure, the vacuum pump group (12) is turned off by closing the air extraction switch, so that the pressure in the cabin (13) tends to be stable.

6. A vacuum laser welding device for improving the quality of the weld seams between the shell and the end cover according to claim 5, characterized in that: The side of the welding turntable (22) facing the cylinder (27) is a working end face, and a cylindrical groove is provided on the working end face of the welding turntable (22). The cylindrical groove is plug-fitted with one end of the shell (4) to achieve accurate positioning of the shell (4), and the diameter of the cylindrical groove is 46 mm to 46.5 mm, and the depth of the cylindrical groove is 5 mm to 15 mm.

7. A vacuum laser welding device for improving the quality of the weld seams between the shell and the end cover according to claim 6, characterized in that: The pressing block (26) is a cylindrical component. The diameter of the pressing block (26) is 35 mm to 42 mm. The side of the pressing block (26) facing the motor (21) is a working end surface. A spacer is provided on the working end surface of the pressing block (26). The spacer is composed of a plurality of alternately distributed metal units and rubber units. A cooling channel is provided in the pressing block (26).

8. A vacuum laser welding device for improving the quality of the weld seams between the shell and the end cover according to claim 7, characterized in that: The motor (21) is electrically connected to the speed controller; The roller (23) is a rubber wheel, the length of the roller (23) is 30 mm to 50 mm, and the diameter of the roller (23) is 10 mm to 20 mm; A pressure sensor is provided between the welding turntable (22) and the motor (21), the measuring range of the pressure sensor being 0N to 500N, and a solenoid valve is provided between the cylinder (27) and the air compressor (28), the solenoid valve and the pressure sensor being electrically connected to the PLC controller respectively; An air intake slit and an air extraction slit are respectively provided on both sides of the cabin body (13) below the cabin door (14), the air intake slit is connected to an inert gas cylinder, an inert protective gas is provided in the inert gas cylinder, and the air extraction slit is connected to an air extraction device; An electrostatic adsorption layer is provided on the top of the cabin (13).

9. A method for improving the quality of the weld seams of a shell and an end cover, which is realized by relying on the vacuum laser welding device for improving the quality of the weld seams of a shell and an end cover as claimed in claim 8, characterized in that: The following steps are involved: Step 1: Assemble one end of the housing (4) and the end cover (3), place the other end of the housing (4) in the groove of the welding turntable (22), and make the lower side of the outer periphery of the housing (4) tangentially match the outer peripheries of the two rollers (23), adjust the position of the pressing block (26), so that the cylinder (27) presses the end cover (3) and the housing (4) coaxially onto the welding turntable (22) in sequence through the pressing block (26), and the pressing force output by the cylinder (27) is 50N to 150N; Step 2: Close the cabin door (14), start the vacuum pump group (12), and make the vacuum degree in the cabin body (13) reach 10 within 3s to 10s. -2 Pa~10 5 Pa; Step 3: Adjust the position of the laser head so that the laser head is placed directly above the high-transmittance glass (15) of the metal hatch (14), or above the transparent non-metal hatch (14), so that the laser spot is projected through the high-transmittance glass (15) and falls on the connection point between the shell (4) and the end cover (3), or directly through the transparent hatch (14) and falls on the connection point between the shell (4) and the end cover (3); Step 4: Adjust the laser welding parameters so that the laser power is 600W to 1800W and the laser defocus is +1mm to +4mm. Start the welding turntable (22). After the rotation speed reaches a preset value, open the inert gas bottle and the exhaust device, and turn on the laser to perform laser welding on the shell (4) and the end cover (3).

10. A method for improving the quality of the welds of the shell and the end cover according to claim 9, characterized in that: The laser head described in step 3 is any one of a conventional welding head, a swing welding head and a galvanometer welding head: The laser spot described in step 3 is any one of a Gaussian spot, a double focus spot, a rectangular spot and a ring core adjustable spot; The laser described in step 4 is any one of an infrared laser, a fiber laser, a semiconductor laser, a disk laser and a CO2 laser; The rotation speed described in step 4 is set at 250 mm / s to 500 mm / s according to the welding rate; If the laser head has a swing function, then in step 4, the swing amplitude of the laser welding parameters is set to 0.1 mm to 0.3 mm, the swing frequency is 200 Hz to 600 Hz, and the swing mode is any one of circular, linear, infinite and figure 8.

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