A photovoltaic cell continuous string welding device and welding method

Abstract

The application discloses a kind of photovoltaic cell continuous string welding equipment and welding method, including power transmission mechanism and welding lamp box, the power transmission mechanism is sequentially divided into the welding strip positioning section, buffer section and welding section that are independently conveyed with each other along the conveying direction, at least one string of cell can be stored in the buffer section, the welding lamp box is located in welding section, and the welding strip positioning section is step-by-step motion conveying, and the welding section is continuous motion conveying;The buffer section is used to receive the predetermined number of cells from the welding positioning section, and the predetermined number of cells is connected in series and then conveyed to the welding section together.The application adopts three independent transmission structures, realizes the continuous conveying of welding section, the welding lamp box can keep open state, ensures that different cells, different areas of the same cell are welded under the same conditions, improves the uniformity and stability of welding.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic design technology, and in particular to a continuous string welding equipment and welding method for photovoltaic cells. Background Technology

[0002] The photovoltaic cell stringing process in the manufacturing of crystalline silicon photovoltaic modules involves connecting the cells one by one, end to end and positive and negative terminals, using photovoltaic welding ribbons to form a cell string.

[0003] Currently, all brands of string welding machines align the welding strip with the main grid and welding PAD points on the battery cell mechanically during welding. Then, the strip moves into the welding station in a stepping motion. Most of these machines use infrared heating welding mode, where one or more cells from a string move into the welding station in a stepping motion. The infrared light box module turns on the light source and keeps it on for a certain period of time before turning it off. Then, the strip moves out from another direction in a stepping motion, and the next one or more cells move into the welding station at the same time. The light source is turned on and kept on for a certain period of time, which can be less than 1 second or more. The time can be set and controlled according to different welding processes, and the typical value is usually between 0.5 seconds and 10 seconds.

[0004] The basic operating steps of the above-mentioned conventional string welding machine are as follows: When the transmission line is in a stopped state of step-forward movement, the front-end action mechanism transports the battery cell and the welding strip to the designated position on the transmission line, and positions the welding strip and the battery cell in advance; at the same time, the welding station welds the battery cell that has been arranged; after the actions of the two stations are completed, the transmission line steps forward again for a while, and the above actions are repeated.

[0005] In this operating mode, the welding light box needs to be frequently turned on and off, resulting in unstable temperature in the welding area and large fluctuations in welding quality. Since each welding operation involves rapidly turning the heating source (usually an infrared heating lamp group) on and off, the temperature in the welding area rises and falls rapidly, making it impossible to achieve effective and stable monitoring and closed-loop control. This causes the temperature of the entire welding area to become a monitoring blind spot, often requiring skilled and experienced personnel to debug the equipment and process windows, affecting the first-pass yield and equipment uptime.

[0006] While existing technologies have proposed string welding machines that connect batteries in series before feeding them into the welding light box, the mechanical structures used are quite complex, significantly increasing the precision requirements for equipment processing and the subsequent maintenance costs.

[0007] Therefore, how to design a simple structure that can achieve continuous welding and improve the yield of production products is a technical problem that needs to be solved. Summary of the Invention

[0008] To address the technical problem of unstable welding zone temperature in existing string welding machines, which leads to large fluctuations in welding quality and affects production yield and equipment uptime, this invention provides a continuous string welding device and welding method for photovoltaic cells to solve the above problems.

[0009] This invention proposes a continuous string welding device for photovoltaic cells, including a power conveying mechanism and a welding light box. The power conveying mechanism is divided into a welding strip positioning section, a buffer section, and a welding section, which are independently conveyed along the conveying direction. The buffer section can hold at least one string of cells. The welding light box is located in the welding section. The welding strip positioning section is a step-type motion conveyor, and the welding section is a continuous motion conveyor. The buffer section is used to receive a predetermined number of cells from the welding positioning section and convey the predetermined number of cells in series to the welding section.

[0010] Furthermore, the welding strip positioning section, buffer section, and welding section each include a conveyor frame, an annular conveyor belt, a drive wheel and a driven wheel rotatably connected to the conveyor frame, and a drive motor for driving the drive wheel to rotate. The drive wheel and the driven wheel are located at both ends of the annular conveyor belt.

[0011] Furthermore, the surface of the annular conveyor belt is provided with several negative pressure adsorption holes.

[0012] Furthermore, it also includes a cell transport mechanism, a ribbon clamping mechanism, a ribbon straightening mechanism, and an upper pressure fixture. The cell transport mechanism transports the cells to the ribbon positioning section. The ribbon clamping mechanism and the ribbon straightening mechanism are arranged along the conveying direction in the ribbon positioning section and are adapted to clamp the ribbon. The upper pressure fixture is located directly above the ribbon positioning section and presses against the cells.

[0013] Furthermore, the welding light box includes a box body and several infrared lamps located inside the box body, and several temperature sensors are provided inside the box body.

[0014] Furthermore, the upper pressure fixture includes a pressure plate and a plurality of spring pressure heads located below the pressure plate, the spring pressure heads being in contact with the welding strip.

[0015] Furthermore, the pressure plate has several through holes running vertically through it.

[0016] Furthermore, the buffer segment switches between step-type motion transport and continuous motion transport.

[0017] This invention also proposes a welding method using the aforementioned photovoltaic cell continuous string welding equipment, comprising the following steps: S1: feeding, placing and positioning the welding strip and cells during a pause in the welding strip positioning section; S2: step-feeding; the welding strip positioning section steps-feeds a predetermined number of cells to the buffer section until at least one cell string is formed on the buffer section. During this step, the buffer section does not feed cell strings to the welding section; S3: continuous feeding; the buffer section continuously feeds cell strings to the welding section. During this step, the welding strip positioning section does not feed cells to the buffer section; S4: welding; welding the cell strings inside the welding light box; S5: repeating steps S1-S4 until all cells are welded.

[0018] Furthermore, in step S2, the buffer section is a step-like movement with the same conveying speed and frequency as the welding strip positioning section, and in step S3, the buffer section is a continuous movement with the same conveying speed as the welding section.

[0019] The beneficial effects of this invention are:

[0020] (2) The photovoltaic cell continuous string welding equipment and welding method of the present invention adopts a three-section independent transmission structure. The feeding part and the welding part are separated by adjusting different power outputs. After storing a specified number of cells in the intermediate buffer section, the cells are transported to the welding section at one time, thereby realizing continuous transmission of the welding section. The welding light box can be kept in the open state to ensure that different cells and different areas of the same cell are welded under the same conditions, thereby improving the uniformity and stability of welding.

[0021] (2) The present invention uses an upper elastic pressing and a lower negative pressure adsorption method to achieve the positioning of the battery cell, and the battery cell and the welding ribbon have a better bonding effect. Attached Figure Description

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0023] Figure 1 This is a front view of the photovoltaic cell continuous string welding equipment described in this invention in its first state;

[0024] Figure 2 This is a front view of the photovoltaic cell continuous string welding equipment described in this invention in its second state;

[0025] Figure 3 This is a top view of the photovoltaic cell continuous string welding equipment described in this invention in its second state;

[0026] Figure 4 This is a front view of the photovoltaic cell continuous string welding equipment described in this invention in its third state;

[0027] Figure 5This is a top view of the photovoltaic cell continuous string welding equipment described in this invention in either the first or second state.

[0028] Figure 6 yes Figure 5 Enlarged view of point a in the middle;

[0029] Figure 7 yes Figure 4 Sectional view along axis AA;

[0030] Figure 8 yes Figure 7 Enlarged view at point b in the middle;

[0031] Figure 9 This is a schematic diagram of the connection structure between the battery cell and the solder strip in this invention;

[0032] Figure 10 yes Figure 9 Sectional view along the BB direction;

[0033] Figure 11 This is a three-dimensional view of the welded light box in this invention.

[0034] In the diagram, 1. Welding strip positioning section, 2. Buffer section, 3. Welding section, 4. Welding light box, 401. Box body, 402. Infrared lamp tube, 5. Conveyor frame, 6. Circular conveyor belt, 7. Driving wheel, 8. Driven wheel, 9. Drive motor, 10. Battery cell handling mechanism, 11. Welding strip clamping mechanism, 12. Welding strip straightening mechanism, 1201. Pressure rod, 1202. Lifting cylinder, 13. Upper pressure fixture, 1301. Pressure plate, 1302. Spring pressure head, 14. Battery cell, 15. Negative pressure adsorption hole, 16. Through hole, 17. First battery string, 18. Second battery string, 19. Third battery string, 20. Fourth battery string, 21. Welding strip. Detailed Implementation

[0035] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0036] Example 1

[0037] like Figures 1-11As shown, a photovoltaic cell continuous string welding device includes a power conveying mechanism and a welding light box 4. The power conveying mechanism is divided into a welding strip positioning section, a buffer section 2, and a welding section 3, which are independently conveyed along the conveying direction. The buffer section 2 can store at least one string of cells 14. The welding light box 4 is located in the welding section 3. The welding strip positioning section is a step-type motion conveying, and the welding section 3 is a continuous motion conveying. The buffer section 2 is used to receive a predetermined number of cells 14 from the welding positioning section 1 and convey the predetermined number of cells in series to the welding section 3.

[0038] The welding strip positioning section, buffer section 2, and welding section 3 are all conveying structures used to transport the battery cells 14, and can be conveyor belts or conveyor rollers. The welding strip positioning section is the feeding part, used to place the battery cells 14 and welding strips 21, and the battery cells 14 and welding strips 21 are initially aligned. Since the battery cells 14 and welding strips 21 need to be fed one by one, and are stationary during the initial alignment, the forward movement is step-by-step. Buffer section 2 is used to store battery cells 14. After there is one or more strings of battery cells 14 on buffer section 2, they are transported to welding section 3. When the aligned battery cells 14 and welding strips 21 are buffered in buffer section 2, buffer section 2 is connected to welding positioning section 1, and the forward movement is step-by-step. After all the battery cells 14 and welding strips in a string are aligned, the string is continuously transported to welding section 3 in one go. The welding section 3 operates continuously and at a constant speed. In existing string welding machines, the battery cells 14 are fed stepwise to the welding light box 4, with a relatively long interval between each battery cell 14. The welding light box 4 can only be opened after a string of battery cells 14 is aligned with the welding strip 21. This invention allows the battery string to pass through a buffer section after being placed and clamped in the welding strip positioning section, enabling the battery string to pass through the welding light box 4 continuously. The welding heating source (usually a group of infrared lamps 402) does not need to be frequently turned on and off (i.e., temperature rise and fall), ensuring that the battery cells 14 have consistent and uniform time and heating when passing through the welding light box 4. Furthermore, this invention achieves continuous conveying of the welding section 3 through a three-stage conveying structure with different power sources, resulting in a simple structure and low maintenance costs.

[0039] In this embodiment, the welding strip positioning section, buffer section 2, and welding section 3 each include a conveyor frame 5, an annular conveyor belt 6, a drive wheel 7 and a driven wheel 8 rotatably connected to the conveyor frame 5, and a drive motor 9 that drives the drive wheel 7 to rotate. The drive motor 9 in the welding strip positioning section is a stepper motor, the drive motor 9 in the buffer section 2 is a motor that switches between stepper and continuous motion, and the drive motor 9 in the welding section 3 is a continuous motion motor. The drive wheel 7 and the driven wheel 8 are located at both ends of the annular conveyor belt 6. The drive motor 9 drives the drive wheel 7 to rotate, thereby rotating the annular conveyor belt 6, which in turn drives the driven wheel 8 to rotate. The drive motor 9 can be directly connected to the drive wheel 7, or it can be indirectly driven through the conveyor belt. In this case, the drive motor 9 can be placed on the lower layer of the conveyor frame 5.

[0040] The welding positioning section 1 also includes some mainstream welding machine equipment, such as a cell transport mechanism 10, a welding strip clamping mechanism 11, a welding strip straightening mechanism 12, and an upper pressure fixture 13. The cell transport mechanism 10 transports the cell 14 to the welding strip positioning section. The welding strip clamping mechanism 11 and the welding strip straightening mechanism 12 are arranged in the welding strip positioning section along the conveying direction and are suitable for clamping the welding strip 21. The upper pressure fixture 13 is located directly above the welding strip positioning section and presses on the cell 14. The cell handling mechanism 10 can be a handling robot. The welding strip clamping mechanism 11 is located at one end of the welding strip 21 in the input direction on the welding strip positioning section. It is used to clamp the end of the welding strip 21 after it is transported to the welding strip positioning section. It can be clamped by the extension and retraction of a cylinder. The welding strip straightening mechanism 12 is located between the welding strip clamping mechanism 11 and the alignment position of the cell 14 and the welding strip 21 to prevent the welding strip 21 from bending. The welding strip straightening mechanism 12 can include a pressure rod 1201 and a lifting cylinder 1202 that drives the pressure rod 1201 to move up and down. The pressure rod 1201 presses on the welding strip 21. It can also be further provided with a translation cylinder that drives the pressure rod 1201 to move along the conveying direction to adjust the position of the pressure rod 1201 in the conveying direction.

[0041] Figure 4 The battery string and clamp are clamped by the welding strip clamping mechanism 11 and the welding strip straightening mechanism 12 and then transported from the welding strip positioning section to the buffer section, so as not to affect the continuous transport of the welding section 3.

[0042] The welding light box 4 uses conventional radiant heating to preheat, weld, and slowly cool the battery strings. It mainly includes a housing 401 and several infrared lamps 402 located within the housing 401 (such as...). Figure 11 (As shown).

[0043] The battery cell 14 in this invention adopts a double-sided welding method, that is, both the front and back sides of the battery cell 14 are covered with welding ribbons 21. This is a common connection method. The specific laying structure is shown in the figure. In a string of batteries, the welding ribbon 21 on the front (i.e., the upper surface) of the battery cell 14 extends from the welding ribbon 21 connecting to the back of the previous battery cell 14, and the welding ribbon 21 on the back of the battery cell 14 extends backward to connect to the next battery cell 14 (e.g., ...). Figure 9 and Figure 10 (As shown).

[0044] Example 2

[0045] Based on Embodiment 1, this embodiment uses the following method to achieve the positioning of the battery cell 14 and the welding ribbon 21: the upper pressure fixture 13 includes a pressure plate 1301 and several spring pressure heads 1302 located below the pressure plate 1301, the spring pressure heads 1302 contacting the welding ribbon 21. The front welding ribbon 21 is placed directly on the front of the battery cell 14, and then pressed down by the upper pressure fixture 13. In a further design, the surface of the annular conveyor belt 6 is provided with several negative pressure adsorption holes 15 for adsorbing the battery cell 14 and the back welding ribbon 21. Because the battery string has an upper pressure fixture 13 on the front and negative pressure adsorption holes 15 on the back for adsorption and fixation, good positioning accuracy is maintained. Figure 8 As can be seen, the pressure plate 1301 has multiple spring pressure heads 1302 to position the welding points.

[0046] To reduce the weight of the pressure plate 1301 and prevent the battery cell 14 from being damaged due to excessive pressure, preferably, the pressure plate 1301 has several through holes 16 extending vertically.

[0047] Example 3

[0048] Based on the above embodiments, the housing 401 is equipped with several temperature sensors. By deploying temperature sensors at multiple points, the temperature in the entire effective welding area of ​​the welding zone is made uniform.

[0049] Example 4

[0050] A welding method using the aforementioned photovoltaic cell 14 continuous string welding equipment includes the following steps: S1: Feeding, placing and positioning the welding ribbon 21 and the cell 14 while the welding ribbon positioning section pauses its conveying; S2: Step conveying; the welding ribbon positioning section steps conveys a predetermined number of cell 14 to the buffer section 2 until at least one cell string is formed on the buffer section 2. During this step, the buffer section 2 does not convey the cell string to the welding section 3; S3: Continuous conveying; the buffer section 2 continuously conveys the cell string to the welding section 3. During this step, the welding ribbon positioning section does not convey the cell 14 to the buffer section 2; S4: Welding; welding the cell string inside the welding light box 4; S5: Repeating steps S1-S4 until all cell 14 are welded.

[0051] Furthermore, in step S2, the buffer section is a step-like movement with the same conveying speed and frequency as the welding strip positioning section, and in step S3, the buffer section is a continuous movement with the same conveying speed as the welding section 3.

[0052] In the illustrations of this invention, each segment of the power transmission mechanism has three or more battery cells 14 welded in series. In reality, depending on production requirements, each segment of the conveyor belt may have one or more strings. The working process of this invention is described below through three typical states. It should be noted that:

[0053] First state: such as Figure 1 and Figure 5 As shown, the welding strip positioning section and buffer section maintain a step-by-step conveying motion, while the welding section 3 maintains a continuous conveying motion. The first battery string 17 connected in series is in the transition conveying stage between the welding strip positioning section and the buffer section, while the welding strip straightening mechanism 12 behind it continues to position and place the battery cells 14 and welding strip 21.

[0054] Second state: such as Figure 2 and Figure 3 As shown, the welding strip positioning section maintains a step-by-step conveying motion, while the welding section 3 and the buffer section maintain a continuous conveying motion. The second battery string 18 connected in series is in the transition conveying stage between the buffer section and the welding section 3, while the third battery string 19 connected in series is in the waiting conveying stage of the welding positioning section 1.

[0055] Third state: such as Figure 4 and Figure 5 As shown, the welding strip positioning section maintains a step-by-step motion conveying, the welding section 3 maintains a continuous motion conveying, and the buffer section begins to switch from continuous motion conveying to step-by-step motion conveying. The first battery string 17 connected in series is in the transition conveying stage between the welding strip positioning section and the buffer section, and the fourth battery string 20 connected in series is welded under the welding light box 4.

[0056] In the description of this invention, it should be understood that the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, in the description of this invention, unless otherwise stated, "multiple pieces" means two or more pieces.

[0057] In this specification, the illustrative expressions of the terms do not necessarily refer to the same embodiments. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments.

[0058] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A continuous string welding equipment for photovoltaic cells, characterized in that: The device includes a power conveying mechanism and a welding light box. The power conveying mechanism is divided into three independent conveying sections along the conveying direction: a welding strip positioning section, a buffer section, and a welding section. The welding strip positioning section is used to place the battery cells and welding strips and to initially align them. The buffer section can hold at least one string of battery cells. The welding light box is located in the welding section. The welding strip positioning section is a step-type motion conveyor, and the welding section is a continuous motion conveyor. The buffer section receives a predetermined number of battery cells from the welding positioning section and connects them in series before conveying them to the welding section. The buffer section switches between step-type and continuous motion conveying. Once multiple strings of battery cells are on the buffer section, they are conveyed to the welding section. The welding section operates continuously at a constant speed, allowing the battery cells to pass through the buffer section after being placed and clamped in the welding strip positioning section. This ensures that the battery cells can pass through the welding light box during continuous forward movement, eliminating the need for frequent switching of the welding heating source. The welding light box is equipped with several temperature sensors, and by controlling these sensors at multiple points, the temperature within the entire effective welding area is made uniform, ensuring that the battery cells experience consistent and uniform heating during their passage through the welding light box.

2. The photovoltaic cell continuous string welding equipment according to claim 1, characterized in that: The welding strip positioning section, buffer section and welding section each include a conveyor frame, an annular conveyor belt, a drive wheel and a driven wheel rotatably connected to the conveyor frame, and a drive motor that drives the drive wheel to rotate. The drive wheel and the driven wheel are located at both ends of the annular conveyor belt.

3. The photovoltaic cell continuous string welding equipment according to claim 2, characterized in that: The surface of the annular conveyor belt is provided with several negative pressure adsorption holes.

4. The photovoltaic cell continuous string welding equipment according to claim 3, characterized in that: It also includes a cell transport mechanism, a ribbon clamping mechanism, a ribbon straightening mechanism, and an upper pressure fixture. The cell transport mechanism transports the cells to the ribbon positioning section. The ribbon clamping mechanism and the ribbon straightening mechanism are arranged along the conveying direction in the ribbon positioning section and are adapted to clamp the ribbon. The upper pressure fixture is located directly above the ribbon positioning section and presses against the cells.

5. The photovoltaic cell continuous string welding equipment according to claim 1, characterized in that: The welding light box includes several infrared lamps located inside the box.

6. The photovoltaic cell continuous string welding equipment according to claim 4, characterized in that: The upper pressure fixture includes a pressure plate and a plurality of spring pressure heads located below the pressure plate, the spring pressure heads being in contact with the welding strip.

7. The photovoltaic cell continuous string welding equipment according to claim 6, characterized in that: The pressure plate has several through holes running vertically through it.

8. A welding method, characterized in that, The method employs the photovoltaic cell continuous string welding equipment described in any one of claims 1-7. Includes the following steps: S1: Loading: Place and position the welding strip and battery cells when the conveying is paused at the welding strip positioning section; S2: Step-by-step conveying; The welding strip positioning section steps-by-step to convey a predetermined number of battery cells to the buffer section until at least one battery string is formed on the buffer section. During this step, the buffer section does not convey battery strings to the welding section. S3: Continuous delivery; the buffer section continuously delivers battery strings to the welding section. During this step, the welding strip positioning section does not deliver battery cells to the buffer section. S4: Welding; Welding battery strings inside a welding light box; S5: Repeat steps S1-S4 until all battery cells are welded.

9. The welding method according to claim 8, characterized in that: In step S2, the buffer section is a step-like movement with the same conveying speed and frequency as the welding strip positioning section. In step S3, the buffer section is a continuous movement with the same conveying speed as the welding section.

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