A laser string welding device

Abstract

The present invention relates to the technical field of laser welding, and particularly relates to a laser string welding device, which includes a conveying mechanism, a pressing mechanism, and an optical path system. The pressing mechanism can be removably placed on the top of the conveyor belt. The pressing mechanism includes a fixture body and a plurality of heat conduction media for pressing a plurality of juxtaposed weld seams. The plurality of heat conduction media are arranged side by side on the side of the fixture body. The optical path system includes a laser, an optical path shaping module, a galvanometer, and a field lens arranged in sequence above the conveyor belt. The laser beam emitted by the laser enters the galvanometer after being shaped by the optical path shaping module. The galvanometer drives the shaped laser beam to deflect along a preset route, and then shoots downward through the field lens onto the heat conduction media. The optical path shaping module shapes the laser beam into a long strip-shaped light spot, which is more suitable for the string welding of a plurality of juxtaposed weld seams of battery cells, improving the string welding efficiency. Through the heat conduction media, overheating caused by direct irradiation of the welding laser is avoided, damage to the product to be welded is avoided, and the welding efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of laser welding, and particularly relates to a laser string welding device. Background Art

[0002] In the manufacturing process of crystalline silicon solar cell modules, the cells must be welded into strings to conduct and output current. The welding of cells and cell strings has a crucial impact on the production efficiency and quality stability of crystalline silicon solar cell modules. The traditional welding methods for crystalline silicon solar cells and cell strings are as follows: The first is manual welding, usually using an electric soldering iron for welding, with low production efficiency and poor quality stability; the second is infrared heating welding, which uses infrared heating tubes to first weld each cell into a cell string through a solder tape. The welding speed is relatively slow, the cells are heated as a whole, prone to deformation, prone to breakage of the cells, and large energy consumption; the third is high-frequency induction welding, which generates eddy currents in the solder tape through a high-frequency induction coil for welding.

[0003] With the development of technology and the improvement of product performance, the disadvantages of the above welding methods are more prominent. For example, in the second type of infrared heating tube, it first uses infrared heating tubes to weld each cell into a cell string through a solder tape, then transports the cell string onto the backplane of the module, and finally welds multiple cell strings together with an electric soldering iron. 1. When the infrared heating tube welds the cell and the solder tape, it will heat the positions outside the area to be welded, which is extremely likely to cause a decline in the performance of the cell; 2. The heat generated by this welding method is relatively high, resulting in an obvious increase in the ambient temperature and unnecessary losses to the constant temperature workshop. Generally speaking, the existing welding methods have relatively complex equipment structures and are very difficult to maintain; there are still problems such as low welding efficiency, easy virtual soldering of the solder tape, and easy damage to the cells.

[0004] Therefore, a laser welding method has emerged in the market. For example, a fitting structure and welding equipment for laser welding of solar cell modules disclosed in the Chinese patent document with the publication number CN217859343U, belonging to the technical field of solar cell preparation, includes a corresponding pressing plate assembly, a bearing plate assembly, and a driving module, so that the materials to be welded can be correspondingly placed on the bearing plate assembly and reliably pressed by the pressing plate assembly, so that the solder tape in the materials to be welded always adheres closely to the cell during laser welding. Its equipment structure is compact, the control is simple, it can achieve tight fitting during the welding of the materials to be welded, avoid virtual soldering, and also reduces the deformation or damage of the materials during the material fitting and pressing process due to the inclusion of a transparent flexible member, improving the efficiency and quality of the preparation of solar cell modules and reducing the cost of the preparation of solar cell modules.

[0005] On the one hand, however, in the existing laser welding equipment, the welding tapes are intermittently dispersed, that is, a small section of welding tape is respectively arranged between two adjacent solar cells. The welding tape is used to realize the connection between adjacent solar cells, and the position of the welding tape is aligned with the welding position of the solar cell. When welding, the laser spot hitting the solar cell is generally circular or annular. Currently, for the solar cells to be welded by the applicant, the grid lines to be welded in the solar cell are multiple parallel straight welds, and fine welding wires are distributed along the length of the welds to cover the entire weld. When welding, the laser spot needs to heat the entire welding wire of multiple welds. However, the above existing laser welding equipment can only achieve dispersed spot welding and cannot meet the welding requirements of parallel grid lines.

[0006] On the other hand, in the existing laser welding equipment, the laser directly irradiates on the product. Especially when directly irradiating on the solar cell, it is easy to cause efficiency loss or even damage. Summary of the Invention

[0007] In view of the above technical problems existing in the prior art, the present invention provides a laser string welding device.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] Provide a laser string welding device, including a conveying mechanism, a pressing mechanism and an optical path system. The conveying mechanism includes a conveyor base, a metal conveyor belt movably installed on the conveyor base for conveying the product to be welded, and a conveying drive mechanism for driving the conveyor belt;

[0010] The pressing mechanism can be removably placed on the top of the conveyor belt. The pressing mechanism includes a fixture body and multiple heat conduction medium bodies for pressing multiple parallel welds. The multiple heat conduction medium bodies are arranged side by side on the side of the fixture body;

[0011] The optical path system includes a laser, an optical path shaping module, a galvanometer and a field lens arranged in sequence above the conveyor belt. The laser beam emitted by the laser enters the galvanometer after being shaped by the optical path shaping module. The galvanometer drives the shaped laser beam to deflect along a preset route, and then shoots downward through the field lens to the heat conduction medium body; the optical path shaping module shapes the laser beam into a strip-shaped spot. The length range of the spot is 10 mm to 40 mm, and the width of the spot is 2 mm to 8 mm. The preset route passes through multiple parallel grid lines, and the spot is arranged along the length direction of the grid lines.

[0012] Specifically, the optical path system further includes an optical path support base. The optical path support base includes a column and a support block. The column supports the support block. The laser, the optical path shaping module, the galvanometer and the field lens are fixed on the support block. A product passage for the product to be welded to pass through is left beside the column.

[0013] Specifically, the optical path system further includes a dust extraction device. The dust extraction device includes a dust extraction frame located above the product channel and below the field lens. The dust extraction frame is provided with an air inlet and an air outlet. A exhaust fan is provided at the air inlet and / or the air outlet. The dust extraction frame is provided with a light passing hole, and the light passing hole is aligned with the field lens upward.

[0014] Specifically, a light blocking plate is arranged inside the dust extraction frame. The light blocking plate is located at the side of the light passing hole and is arranged along the arrangement direction of the grid lines. The optical path support base is also provided with a light blocking adjustment driving mechanism for driving and adjusting the position of the light blocking plate in the light passing hole.

[0015] Specifically, the dust extraction frame includes a frame body and a cover body located at the side of the frame body. A lock is provided between the cover body and the frame body, and operating the lock can release the restriction on the cover body to open the cover body.

[0016] Specifically, the fixture body is provided with a plurality of telescopic elastic columns, and a plurality of heat conducting media are floatingly installed on the fixture body via a plurality of elastic connecting columns.

[0017] Specifically, the fixture body includes a supporting end and a connecting part. The connecting part is located between the two supporting ends. A plurality of heat conducting media are fixed to the connecting part, and the connecting part is provided with a plurality of relief holes aligned with the heat conducting media.

[0018] Specifically, a constant temperature heating device is provided at the top of the conveyor belt. The constant temperature heating device is used to heat the conveyor belt and indirectly heat the products to be welded on the conveyor belt.

[0019] Specifically, the conveyor belt includes a horizontal section for supporting and conveying the products to be welded. The number of the constant temperature heating devices is multiple, and the multiple constant temperature heating devices are distributed at the bottom of the horizontal section.

[0020] Specifically, a positioning magnet is provided at the side of the fixture body.

[0021] Advantages of the present invention:

[0022] The laser string welding device of the present invention, compared with the prior art, the optical path system shapes the laser beam into a long strip-shaped light spot, and the light spot is offset for welding along the length direction of multiple parallel grid lines. Compared with the traditional circular or annular light spot, this long strip-shaped light spot is more suitable for the string welding of multiple parallel welds of battery cells, improving the string welding efficiency. Through the heat conducting media, using the principle of heat transfer, the heat of the welding laser is transferred to the solder at the weld, avoiding overheating caused by direct irradiation of the welding laser, avoiding damage to the products to be welded, and improving the welding efficiency. Moreover, the multiple parallel heat conducting media are convenient for pressing multiple welds simultaneously. Description of the Drawings

[0023] Figure 1 It is a schematic structural diagram of the laser string welding device in the embodiment.

[0024] Figure 2 Schematic structural diagram of the conveying mechanism of the laser string welding device in the embodiment.

[0025] Figure 3 Schematic structural diagram of the pressing mechanism in the embodiment.

[0026] Figure 4 Schematic diagram of the pressing mechanism pressing the battery panel in one of the usage states in the embodiment.

[0027] Figure 5 Exploded view of the pressing mechanism in the embodiment.

[0028] Figure 6 Schematic structural diagram of the optical path system of a laser string welding device in the embodiment.

[0029] Figure 7 Schematic structural diagram of the dust extraction device in the embodiment.

[0030] Figure 8 Schematic diagram of the optical path shaping module, galvanometer, field lens, and emitted laser beam in the embodiment.

[0031] Figure 9 Route deviation trajectory of the emitted laser beam during operation.

[0032] Reference numerals:

[0033] Optical path system 1, laser 11, optical path shaping module 12, galvanometer 13, field lens 14, optical path support base 15, column 151, support block 152, intermediate support plate 153, product channel 154, dust extraction device 16, dust extraction frame 161, frame body 1611, cover body 1612, lock 1613, air inlet 162, air outlet 163, exhaust fan 164, light passing hole 165, light blocking plate 17, light blocking adjustment driving mechanism 18.

[0034] Conveying mechanism 2, conveyor base 21, conveyor belt 22, horizontal section 221, conveying driving mechanism 23, constant temperature heating device 24;

[0035] Pressing mechanism 3, fixture body 31, supporting end 311, connecting portion 312, relief hole 313, heat-conducting medium body 32, telescopic elastic column 33, positioning magnet 34. Detailed implementation manners

[0036] The following further describes in detail the implementation manners of the present invention in conjunction with the drawings and embodiments. The following embodiments are used to illustrate the present invention, but cannot be used to limit the scope of the present invention.

[0037] In the description of the present invention, unless otherwise specified, "a plurality of" means two or more; the orientation or positional relationship indicated by terms such as "upper", "lower", "left", "right", "inner", "outer", "front end", "rear end", "head", "tail", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention. In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "connected" and "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0038] The laser string welding device of this embodiment, as Figures 1 to 9 shown, includes a conveying mechanism, a pressing mechanism, and an optical path system. The conveying mechanism 2 includes a conveying machine base 21, a conveyor belt 22 made of metal, and a conveying driving mechanism 23 for driving the conveyor belt 22. The conveyor belt 22 is installed on the conveying machine base 21 in a recyclable manner through rollers. The conveying driving mechanism 23 is a motor that drives the rollers to rotate and then drives the conveyor belt 22 to move. The conveyor belt 22 is provided with a plurality of mesh holes. The conveyor belt 22 includes a horizontal section 221 for supporting and conveying the products to be welded. A plurality of pressing mechanisms 3 are placed on the horizontal section 221, and the pressing mechanisms 3 can be placed on the top of the conveyor belt 22 away from the ground.

[0039] Each pressing mechanism 3 includes a fixture body 31 and a plurality of heat-conducting media 32 for pressing a plurality of weld seams of the products to be welded. The plurality of heat-conducting media 32 are arranged side by side at the bottom side of the fixture body 31. Specifically, the fixture body 31 is provided with a plurality of telescopic elastic columns 33, and the plurality of heat-conducting media 32 are floatingly installed on the fixture body 31 via a plurality of elastic connecting columns. Specifically, the heat-conducting media 32 are in sheet form, and the bottom surfaces of the plurality of heat-conducting media 32 are arranged on the same horizontal plane, which is convenient for simultaneously pressing a plurality of weld seams arranged in parallel on a flat battery panel. The pressing module mechanism is recycled, and the battery cells are accurately pressed and positioned above the conveyor belt 22 by a peripheral robot.

[0040] The heat-conducting medium body 32 can be made of existing materials: graphite, graphite copper foil, diamond, diamond aluminum, diamond copper, ceramics, alumina ceramics, zirconia ceramics, aluminum nitride ceramics, silicon carbide materials, quartz. Diamond has good comprehensive thermophysical properties. Its thermal conductivity at room temperature is 700 - 2200 W / (m·K), and its coefficient of thermal expansion is 0.8×10-6 / K. According to the mixture rule, the diamond / metal matrix composite material prepared by adding diamond particles to a high thermal conductivity metal matrix such as Ag, Cu, and Al can become a new type of electronic packaging material with both low coefficient of thermal expansion and high thermal conductivity.

[0041] In this embodiment, the fixture body 31 includes a supporting end 311 and a connecting portion 312. The connecting portion 312 is located between the two supporting ends 311. A plurality of heat-conducting medium bodies 32 are fixed to the connecting portion 312. The connecting portion 312 is provided with a plurality of relief holes 313 that align with the heat-conducting medium bodies 32, so that as many laser beams as possible shine downward onto the heat-conducting medium bodies 32 to improve the uniformity. The main function of the fixture body 31 is to fix the heat-conducting medium bodies 32 and provide the weight required for pressing and the space required for series soldering. The main function of the telescopic elastic column 33 is to distribute the weight of the fixture body 31, prevent the overall weight of the fixture body 31 from being too large and damaging the battery chip, and fix the heat-conducting medium bodies 32 and ensure that the series soldering medium presses the welding tape and the battery chip horizontally.

[0042] In this embodiment, a constant temperature heating device 24 is provided on the top of the conveyor belt 22. The constant temperature heating device 24 is used to heat the conveyor belt 22 and indirectly heat the products to be welded on the conveyor belt 22. The number of the constant temperature heating devices 24 is multiple. The multiple constant temperature heating devices 24 are distributed at the bottom of the horizontal section 221, and the temperatures of the respective constant temperature heating devices 24 are independently controlled to adapt to different stages. The constant temperature heating device 24 ensures that the battery chips are welded at the same or nearly the same temperature, mainly to ensure the welding effect. The constant temperature heating device 24 is installed below the conveyor belt 22, and the temperature is conducted to the battery chips through the conveyor belt 22.

[0043] Specifically, a positioning magnet 34 is provided on the side of the fixture body 31 to facilitate mutual adsorption and positioning with the conveyor belt 22.

[0044] The optical path system 1 includes a laser 11, an optical path shaping module 12, a galvanometer 13, and a field lens 14 arranged in sequence. The laser 11 is an off-the-shelf existing module that emits a laser beam to provide the energy required for laser string welding. The main function of the optical path shaping module 12 is to shape the light spot of the laser 11, optimize the energy distribution of the light spot, and provide the required light spot shape. The main function of the galvanometer 13 is to provide different string welding routes according to the string welding of different cell grid lines. The main function of the field lens 14 is to focus the laser and ensure the consistency of the light spot required for each grid line string welding of the entire cell. The laser beam emitted by the laser 11 enters the galvanometer 13 after being shaped by the optical path shaping module 12. The galvanometer 13 drives the shaped laser beam to deflect along a preset route, and then emits downward through the field lens 14. The core innovation of the optical path system 1 lies in that the optical path shaping module 12 shapes the laser beam into a long strip-shaped light spot, that is, the cross-sectional shape of the laser beam, or more precisely, the pattern shape of the laser beam hitting the cell. The length range of the light spot is 10 mm to 40 mm, and the width of the light spot is 2 mm to 8 mm. It can be various long strip shapes such as oval, rectangular, and diamond-shaped. The length of the light spot is arranged along the length direction of the grid line, and the preset route passes through multiple parallel grid lines, preferably in a continuously reverse U shape as shown in Figure 9 so that the straight sides of the U shape pass through the grid lines in sequence. For example, it enters from the left side of the topmost weld seam, reaches the right side to complete the string welding of one weld seam and then moves downward, then laterally moves to the left to string weld another weld seam, then moves downward again, and moves to the right to string weld the third weld seam, and so on. Of course, for the same weld seam, the above preset route and the illustration show that the laser beam only passes through once. In fact, it can scan back and forth several times and then deflect to another weld seam.

[0045] In this embodiment, the optical path system 1 further includes an optical path support base 15, which includes two columns 151 and a support block 152 located at the top of the columns 151. The columns 151 support the support block 152. The laser 11, the optical path shaping module 12, the galvanometer 13, and the field lens 14 are fixed on the support block 152. A product passage 154 for the product to be welded to pass through is left between the two columns 151.

[0046] In this embodiment, the optical path system 1 further includes a dust extraction device 16. An intermediate support plate 153 is provided in the middle of the column 151, and the dust extraction device 16 is fixed to the intermediate support plate 153. The dust extraction device 16 includes a dust extraction frame 161 located above the product channel 154 and below the field lens 14. Air inlets 162 and air outlets 163 are respectively provided on two opposite sides of the dust extraction frame 161. An exhaust fan 164 is provided at the air inlet 162 and / or the air outlet 163. A light passing hole 165 is provided in the middle of the dust extraction frame 161. The light passing hole 165 is aligned with the field lens 14 upward. The laser beam emitted from the field lens 14 passes downward through the light passing hole 165 to perform string welding on the battery cells on the product channel 154. The dust extraction frame 161 includes a frame body 1611 and a cover body 1612 located on the side of the frame body 1611. A latch 1613 is provided between the cover body 1612 and the frame body 1611. Operating the latch 1613 can release the restriction on the cover body 1612 and open the cover body 1612, which is convenient for opening the cover for maintenance. The main function of the dust extraction device 16 is to protect the optical path system from being damaged by dust and to extract dust.

[0047] In this embodiment, a light shielding plate 17 is provided in the dust extraction frame 161. The light shielding plate 17 is located at the side of the light passing hole 165. The light shielding plate 17 is arranged along the arrangement direction of the grid lines. The number of the light shielding plates 17 is two, and the two light shielding plates 17 are respectively located on two opposite sides of the light passing hole 165. The light shielding plate 17 is made of a high-temperature resistant material. The purpose is to block the laser beam beyond the battery cell. As Figure 8 shown, the two ends D are blocked in the length direction of the light spot. On the one hand, it avoids the influence of the laser beam on the surrounding area beyond the battery cell. On the other hand, it ensures the neatness of the string welding of the battery cell. The optical path support base 15 is also provided with a light shielding adjustment driving mechanism 18, specifically a cylinder, for driving and adjusting the position of the light shielding plate 17 in the light passing hole 165 to be applicable to battery plates of different specifications.

[0048] During operation, the robot in the periphery transports the battery cell and the pressing mechanism to above the conveyor belt 22 at a fixed position. After the pressing mechanism 3 presses and positions the battery cell, the conveyor belt transports the battery cell and the pressing mechanism together to directly below the optical path system and the dust extraction device. Then, the optical path system emits light precisely to perform string welding on the battery cell. Finally, the conveyor belt transports the welded battery cell and the pressing mechanism together to the rear of the optical path support base to perform reflow on the pressing mechanism and other processes on the welded battery string. Compared with the prior art:

[0049] 1. The heat-conducting medium 32 can quickly absorb the laser energy and quickly transfer it to the battery cell and the welding tape to complete string welding, avoiding the problems of damage or even destruction caused by the direct irradiation of the laser on the battery cell in the prior art and the problem of efficiency loss of the battery cell caused by the heating of the non-welding area in the traditional string welding technology.

[0050] 2. Compatible with the low-temperature process welding of HJT batteries in the market. The overall heating temperature of traditional welding is high, which affects the efficiency of HJT batteries.

[0051] 3. Compatible with the welding of main-gridless (0BB) battery cells in the market, which cannot be completed by traditional welding;

[0052] 4. For the copper electroplating solution, laser string welding can be used for welding, while the instantaneous temperature of traditional welding cannot reach the required level;

[0053] 5. Compatible with the welding of BC batteries. Currently, the traditional solution requires adding a solder paste printing process in the previous process, resulting in a significant increase in cost. The laser string welding process is simpler, has lower cost, and better effect;

[0054] 6. The heating method is changed from infrared lamp tube radiation heating to laser string welding. The heating area is very small, avoiding the problem that the temperature of the welding area affects the temperature of the entire environment and making it difficult to control the temperature in the constant temperature workshop;

[0055] 7. The energy consumption is significantly reduced compared to traditional welding, with basically zero consumables. The heat source of traditional welding has a limited lifespan;

[0056] 8. Simplify the equipment for easy maintenance.

[0057] 9. Improvement of the optical path system, with the welding efficiency increased by more than 50%, avoiding the problem of insufficient welding efficiency in the existing technology.

[0058] 10. The optical path system shapes the laser beam into a long-strip-shaped light spot, and the light spot offsets for welding along the length direction of multiple parallel grid lines. Compared with the traditional circular or annular light spot, this long-strip-shaped light spot is more suitable for the string welding of multiple parallel welds on the battery cell, improving the string welding efficiency.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than limiting the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A laser string welding device, characterized in that: It includes a conveying mechanism, a pressing mechanism and an optical path system. The conveying mechanism includes a conveyor base, a conveyor belt movably mounted on the conveyor base for conveying the metal material of the product to be welded, and a conveyor drive mechanism for driving the conveyor belt; The pressing mechanism is movably placed on the top of the conveyor belt, and the pressing mechanism includes a jig body and a plurality of heat-conducting medium bodies for pressing the plurality of parallel welds, and the plurality of heat-conducting medium bodies are arranged in parallel on the side of the jig body; The optical path system includes a laser, an optical path shaping module, a galvanometer, and a field lens, which are sequentially arranged above the conveyor belt. The laser beam emitted by the laser is shaped by the optical path shaping module and enters the galvanometer. The galvanometer drives the shaped laser beam to deflect along a preset route and then project downwards toward the heat transfer medium through the field lens. The optical path shaping module shapes the laser beam into a long strip of light spot, the length of which ranges from 10 mm to 40 mm, and the width of which ranges from 2 mm to 8 mm. The preset route passes through a plurality of parallel grid lines, and the light spots are arranged along the length direction of the grid lines. The optical path system also includes an optical path support base, which includes a column and a support block. The column supports the support block. The laser, optical path shaping module, galvanometer and field lens are fixed on the support block. A product channel is left on the side of the column for the products to be welded to pass through. The optical path system also includes a dust extraction device, which includes a dust extraction frame located above the product channel and below the field lens. The dust extraction frame is provided with an air inlet and an air outlet. The air inlet and / or the air outlet are provided with an exhaust fan. The dust extraction frame is provided with a light hole, which is aligned with the field lens upward. A light shield is provided in the dust extraction frame, the light shield is located on the side of the light hole, and the light shield is arranged along the arrangement direction of the grid lines; the optical path support seat is also provided with a light shield adjustment drive mechanism for driving and adjusting the position of the light shield in the light hole; The fixture body is provided with a plurality of telescopic elastic columns, and the plurality of heat-conducting medium bodies are floatably mounted on the fixture body via the plurality of telescopic elastic columns; The fixture body includes a supporting end portion and a connecting portion, wherein the connecting portion is located between the two supporting end portions, a plurality of heat-conducting medium bodies are fixed to the connecting portion, and the connecting portion is provided with a plurality of clearance holes aligned with the heat-conducting medium bodies.

2. The laser string welding device according to claim 1, wherein: The dust extraction frame includes a frame body and a cover body located on the side of the frame body. A lock buckle is provided between the cover body and the frame body. The lock buckle can be operated to release the restriction on the cover body and open the cover body.

3. A laser string welding device according to claim 1, characterized in that: A constant temperature heating device is provided on the top of the conveyor belt, and is used to heat the conveyor belt and indirectly heat the products to be welded on the conveyor belt.

4. The laser string welding device according to claim 3, characterized in that: The conveyor belt comprises a horizontal section for supporting and conveying products to be welded. There are multiple constant temperature heating devices, which are distributed at the bottom of the horizontal section.

5. A laser string welding device according to claim 1, characterized in that: A positioning magnet is provided on the side of the fixture body.

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