Phosphating device for pretreatment of large metal surface coating production line

Abstract

The invention relates to the technical field of metal processing, in particular to a large metal surface coating production line pretreatment phosphating device which comprises a phosphating box and further comprises a collecting tank arranged at one corner of the bottom end of the phosphating box, a sewage pumping pipe is arranged on the phosphating box, one end of the sewage pumping pipe is located in the collecting tank, and the other end of the sewage pumping pipe is located in the collecting tank. According to the device, the collecting tank is arranged at one corner of the bottom end of the phosphating box body and is matched with the sewage pumping pipe and the external water pump, sediment can be pumped out in time, and the situation that the phosphating effect is affected due to sediment accumulation is avoided; the scraping plate can be driven by the circulating driving part to circularly move in the box body, bottom sediments are effectively pushed into the collecting tank, and the bottom of the box body is kept clean; the water absorption elastic bag absorbs water on the lower layer when the scraper is located at the bottom end of the box body, and when the scraper moves to the upper layer, the extrusion part and the scraper are matched to extrude and discharge the water, so that the water in the box body is mixed up and down, the concentration of a phosphating solution is uniform, and the phosphating quality and stability of the metal surface are improved.

Description

Technical Field

[0001] This invention relates to the field of metal processing technology, specifically to a phosphating device for pretreatment in a large-scale metal surface coating production line. Background Technology

[0002] In large-scale metal surface coating production lines, phosphating is a core pretreatment step. Through a chemical reaction, it forms a thin film of insoluble phosphate on the metal surface, significantly improving coating adhesion and corrosion resistance, and providing a high-quality substrate for subsequent coating. Phosphating equipment must balance efficiency, film quality, and equipment stability. It typically consists of pre-degreasing, degreasing, washing, surface conditioning, phosphating, and passivation processes connected in series by an automated conveying system to form a continuous production line. The phosphating tank, as the core equipment, plays a crucial role in ensuring the metal workpiece reacts fully with the phosphating solution to form a uniform phosphate film. In existing technologies, precipitates form at the bottom of the phosphating tank during workpiece processing, mainly from phosphate crystals generated during the phosphating reaction and impurities detached from the workpiece surface. Accumulated precipitates occupy tank volume, clog the circulation system, and lead to a decline in phosphate film quality, affecting the workpiece's corrosion resistance and service life. Therefore, we propose a phosphating device for pretreatment in large-scale metal surface coating production lines. Summary of the Invention

[0003] To address the aforementioned technical problems, this application provides a phosphating device for pretreatment in a large-scale metal surface coating production line. The device includes a phosphating tank and a collection trough located at one corner of the bottom of the phosphating tank. A sludge suction pipe is installed on the phosphating tank, with one end of the pipe located within the collection trough and connected to an external water pump. A scraper is installed inside the phosphating tank to push sediment from the bottom of the tank into the collection trough. A circulation drive component connected to the scraper is installed inside the phosphating tank to drive the scraper to circulate between the top and bottom of the phosphating tank. A water-absorbing elastic bladder is installed on one side of the scraper to absorb water from the lower layer of the phosphating tank when the scraper is at the bottom. A squeezing component is installed on the scraper to cooperate with the scraper to squeeze the water-absorbing elastic bladder when the scraper moves to the upper layer of the phosphating tank, thereby discharging the water from the lower layer of the phosphating tank and mixing the water within the phosphating tank.

[0004] In some embodiments, the scraper adopts a symmetrical split design, which includes two rectangular plates. The phosphating box is provided with a deflector connected to the rectangular plates, which is used to drive the two rectangular plates to deflect and be stored to the side of the phosphating box when the rectangular plates move to the top of the phosphating box, so as to avoid the workpiece. The extrusion component includes an extrusion plate disposed on one side of a rectangular plate. A linkage component is provided between the extrusion plate and the rectangular plate to drive the extrusion plate to move toward the rectangular plate when the rectangular plate deflects, thereby extruding the water-absorbing elastic bladder. The water-absorbing elastic bladder is fixedly connected to one side of the extrusion plate, and a water outlet pipe is fixedly connected to the extrusion plate. The water outlet pipe is connected to the water-absorbing elastic bladder, and a one-way valve is installed in the water outlet pipe to allow only water to flow out of the water-absorbing elastic bladder. A water inlet hole is provided on the extrusion plate, and a sealing element is provided on the extrusion plate to block the water inlet hole when the extrusion plate is at the top of the phosphating box, and to open the water inlet hole when the extrusion plate is at the top of the phosphating box.

[0005] In some embodiments, the circulating drive includes a shaft rotatably connected to the four corners of the phosphating chamber, multiple shafts having sprockets fixedly connected to their ends, the sprockets being connected to each other by a chain, and one end of a shaft passing through the phosphating chamber. A drive motor is fixedly connected to the phosphating chamber, the output shaft of the drive motor being fixed to one of the shafts, a U-shaped frame being mounted on the chain, and a rectangular plate being connected to the U-shaped frame.

[0006] In some embodiments, the deflecting member includes a connecting plate fixedly connected to one side of the rectangular plate, a hollow column fixedly connected to one end of the connecting plate, a shaft II fixedly connected to the U-shaped frame, one end of the shaft II passing through the hollow column and rotatably connected to it, and a torsion spring sleeved on the shaft II installed inside the hollow column, the two ends of the torsion spring being fixed to the inner wall of the hollow column and the shaft II respectively, and when the rectangular plate is deflected, the torsion spring is subjected to torsion to provide it with self-recovering elastic force; Furthermore, a top plate is fixedly connected to the inner wall of the top of the phosphating box, which is used to hold one end of the rectangular plate in place when the rectangular plate moves, so that the rectangular plate can be deflected, and one end of the top plate is designed with a slope.

[0007] In some embodiments, the linkage includes multiple connecting rods 1 disposed between the rectangular plate and the extrusion plate. The two ends of the multiple connecting rods 1 are rotatably connected to the rectangular plate and the extrusion plate respectively via rotating shafts. The water-absorbing elastic bladder is slidably connected to the side of the rectangular plate, and a sliding plate is slidably connected to the rectangular plate. The sliding plate is rotatably connected to one of the connecting rods 1 via a rotating shaft, and a sliding sleeve is fixedly connected to the rectangular plate. One end of the sliding plate slides through the sliding sleeve to guide and limit the movement of the sliding plate. Furthermore, a deflection plate is fixedly connected to one end of the second shaft, a slide groove is provided at one end of the slide plate, and a third shaft that slides through the slide groove is fixedly connected to one end of the deflection plate.

[0008] In some embodiments, the sealing component includes a plurality of perforated plates slidably connected to the extrusion plate, each perforated plate corresponding to a plurality of water inlets. A strip plate is fixedly connected between the plurality of perforated plates, and a sliding plate is fixedly connected to the strip plate. One end of the sliding plate slides through the extrusion plate and is rotatably connected to a round roller via a rotating shaft. When the extrusion plate moves to the bottom of the phosphating tank, the round roller is pushed by the inner wall of the bottom of the phosphating tank to drive the perforated plates to move, so that the holes on the perforated plates are aligned with the water inlets for connection. Furthermore, a spring sheet is provided between the strip plate and the inner wall of the extrusion plate.

[0009] In some embodiments, a limiting protrusion is fixedly connected to the U-shaped frame, and when the rectangular plate is at the bottom of the phosphating box, the limiting protrusion contacts and abuts against the connecting plate.

[0010] In some embodiments, inner support plates that abut against the inner side of the chain are fixedly connected to the inner walls of the top and bottom of the phosphating box, and a limiting plate is fixedly connected to one side of the U-shaped frame. A side support plate is fixedly connected to one end of the inner support plate at the top of the phosphating box. A guide groove is provided on the side support plate. During the movement of the rectangular plate along the top of the phosphating box, the limiting plate can be driven to slide along the guide groove, thereby guiding and limiting the movement of the U-shaped frame.

[0011] The present invention has at least the following beneficial effects: The collection tank of this device is located at one corner of the bottom of the phosphating tank. Together with the sludge suction pipe and external water pump, it can promptly remove sediment and prevent sediment accumulation from affecting the phosphating effect. The scraper can circulate within the tank under the drive of the circulation component, effectively pushing the sediment at the bottom into the collection tank and keeping the bottom of the tank clean. The water-absorbing elastic bladder draws in the lower layer of water when the scraper is at the bottom of the tank. When the scraper moves to the upper layer, the extrusion component works with the scraper to expel the water, achieving mixing of the water inside the tank and making the phosphating solution concentration uniform, which helps to improve the quality and stability of the phosphating treatment of metal surfaces. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 For the present invention Figure 1 Schematic diagram of partial cross-section; Figure 3 For the present invention Figure 2 Schematic diagram of partial cross-section; Figure 4 For the present invention Figure 3 Schematic diagram of the structure of area A in the middle; Figure 5 For the present invention Figure 3 Schematic diagram of partial cross-section; Figure 6 For the present invention Figure 5 Schematic diagram of the structure of Zone B; Figure 7 For the present invention Figure 5 Schematic diagram of partial cross-section.

[0013] In the diagram: 1-Phosphating tank; 2-Collection tank; 3-Sludge suction pipe; 4-Scraper; 5-Circulation drive component; 6-Water-absorbing elastic bladder; 7-Extrusion component; 11-Rectangular plate; 12-Deflection component; 13-Extrusion plate; 14-Linkage component; 15-Outlet pipe; 16-One-way valve; 17-Inlet hole; 18-Sealing component; 19-Shaft 1; 20-U-shaped frame; 21-Sprocket; 22-Drive motor; 23-Connecting plate ; 24-Hollow column; 25-Shaft 2; 26-Torsion spring; 27-Top plate; 28-Connecting rod 1; 29-Slide plate; 31-Connecting rod 2; 32-Sliding sleeve; 33-Deflection plate; 34-Slide groove; 35-Shaft 3; 36-Perforated plate; 37-Strip plate; 38-Sliding plate; 39-Round roller; 41-Spring piece; 42-Limiting protrusion; 43-Inner support plate; 44-Limiting plate; 45-Side support plate; 46-Guide groove. Detailed Implementation

[0014] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0015] Please see Figures 1-7 The present invention provides a technical solution: a phosphating device for pretreatment in a large-scale metal surface coating production line, comprising a phosphating chamber 1, and further comprising: Collection tank 2 is located at one corner of the bottom of phosphating box 1. A sludge suction pipe 3 is installed on phosphating box 1. One end of the sludge suction pipe 3 is located in collection tank 2 and is connected to an external water pump for extracting sediment from collection tank 2. Scraper 4 is installed inside the phosphating box 1 to push the sediment at the bottom of the phosphating box 1 into the collection tank 2; The circulating drive component 5 is set inside the phosphating box 1 and connected to the scraper 4, and is used to drive the scraper 4 to circulate between the top and bottom of the phosphating box 1. The water-absorbing elastic bladder 6 is located on one side of the scraper 4 and is used to absorb the lower layer of water in the phosphating tank 1 when the scraper 4 is at the bottom of the phosphating tank 1. The extrusion component 7 is disposed on the scraper 4 and connected to the water-absorbing elastic bladder 6. When the scraper 4 moves to the upper layer of the phosphating tank 1, it cooperates with the scraper 4 to extrude the water-absorbing elastic bladder 6 to discharge the water in the lower layer of the phosphating tank 1, so as to mix the water in the phosphating tank 1. Specifically, the collection tank 2 of this device is located at one corner of the bottom of the phosphating tank 1. Together with the sludge suction pipe 3 and the external water pump, it can promptly remove the sediment and prevent sediment accumulation from affecting the phosphating effect. The scraper 4 can circulate and move within the tank under the drive of the circulation drive component 5, effectively pushing the bottom sediment into the collection tank 2 and keeping the bottom of the tank clean. The water-absorbing elastic bladder 6 absorbs the lower layer of water when the scraper 4 is at the bottom of the tank. When the scraper 4 moves to the upper layer, the squeezing component 7 works with the scraper 4 to squeeze out the water, realizing the mixing of the water in the tank from top to bottom, making the phosphating solution concentration uniform, which helps to improve the quality and stability of the phosphating treatment of the metal surface.

[0016] The scraper 4 adopts a symmetrical split design, which includes two rectangular plates 11. A deflector 12 connected to the rectangular plates 11 is provided inside the phosphating box 1. When the rectangular plates 11 move to the top of the phosphating box 1, it drives the two rectangular plates 11 to deflect and retract to the side of the phosphating box 1 to avoid the workpiece. When the rectangular plates 11 move to the top of the phosphating box 1, they deflect and retract to the side to cleverly avoid the workpiece and avoid obstructing the workpiece's entry, exit or processing. The water-absorbing elastic bladder 6 absorbs the lower layer of water when the scraper 4 is at the bottom of the box. When the scraper 4 moves to the upper layer, the extrusion member 7 works with the scraper 4 to expel the water, realizing the mixing of water in the box and ensuring uniform concentration of phosphating solution. The cooperation of multiple structures comprehensively improves the quality, efficiency and stability of metal surface phosphating treatment. The extrusion component 7 includes an extrusion plate 13 disposed on one side of the rectangular plate 11. A linkage component 14 is provided between the extrusion plate 13 and the rectangular plate 11, which is used to drive the extrusion plate 13 to move towards the rectangular plate 11 when the rectangular plate 11 deflects, thereby extruding the water-absorbing elastic bladder 6. The water-absorbing elastic bladder 6 is fixedly connected to one side of the extrusion plate 13, and a water outlet pipe 15 is fixedly connected to the extrusion plate 13. The water outlet pipe 15 is in communication with the water-absorbing elastic bladder 6, and a one-way valve 16 is installed inside the water outlet pipe 15. The function of this one-way valve 16 is to allow water to flow out only from the water-absorbing elastic bladder 6. When the extrusion plate 13 moves relative to the rectangular plate 11 and extrudes the water-absorbing elastic bladder 6, the lower layer of water inside the water-absorbing elastic bladder 6 can be discharged to the upper layer of the phosphating tank 1 through the water outlet pipe 15. Meanwhile, based on the special design of the one-way valve 16, when the rectangular plate 11 is no longer restricted by the top plate 27 and automatically deflects and resets, due to the structural characteristics of the one-way valve 16 in the outlet pipe 15, the water-absorbing elastic bladder 6 cannot automatically return to its original state to absorb water. A water inlet hole 17 is provided on the extrusion plate 13. The water inlet hole 17 is also connected to the water-absorbing elastic bladder 6. A sealing member 18 is provided on the extrusion plate 13 to block the water inlet hole 17 when the extrusion plate 13 is at the top of the phosphating box 1, and to open the water inlet hole 17 when the extrusion plate 13 is at the top of the phosphating box 1. At this time, the water-absorbing elastic bladder 6 can automatically return to its original state to absorb the water in the lower layer of the phosphating box 1.

[0017] The circulating drive unit 5 includes shafts 19 rotatably connected to the four corners of the phosphating chamber 1. Multiple shafts 19 are fixedly connected to sprockets 21 at their ends. The sprockets 21 are connected to each other by a chain. One end of a shaft 19 passes through the phosphating chamber 1. A drive motor 22 is fixedly connected to the phosphating chamber 1. The output shaft of the drive motor 22 is fixedly connected to a shaft 19. A U-shaped frame 20 is installed on the chain. A rectangular plate 11 is connected to the U-shaped frame 20. When the drive motor 22 is started, its output shaft drives the shaft 19 connected to it to rotate, thereby driving all shafts 19 to rotate synchronously. At the same time, the chain moves accordingly, and finally drives the rectangular plate 11 connected to the U-shaped frame 20 to move inside the phosphating chamber 1.

[0018] The deflector 12 includes a connecting plate 23 fixedly connected to one side of the rectangular plate 11. A hollow column 24 is fixedly connected to one end of the connecting plate 23. A shaft 25 is fixedly connected to the U-shaped frame 20. One end of the shaft 25 passes through the hollow column 24 and is rotatably connected to it. A torsion spring 26 is installed inside the hollow column 24 and sleeved on the shaft 25. The two ends of the torsion spring 26 are fixedly connected to the inner wall of the hollow column 24 and the shaft 25, respectively. When the rectangular plate 11 is deflected, the hollow column 24 rotates relative to the shaft 25. At the same time, the torsion spring 26 is twisted by force to provide self-recovering force for the hollow column 24. Furthermore, a top plate 27 is fixedly connected to the inner wall of the top of the phosphating box 1, which is used to hold one end of the rectangular plate 11 when it moves, so that the rectangular plate 11 can be deflected. One end of the top plate 27 is designed with a slope to make the device run more smoothly.

[0019] The linkage 14 includes multiple connecting rods 28 disposed between the rectangular plate 11 and the extrusion plate 13. The two ends of the multiple connecting rods 28 are rotatably connected to the rectangular plate 11 and the extrusion plate 13 respectively via rotating shafts. The water-absorbing elastic bladder 6 is slidably connected to the side of the rectangular plate 11, and a slide plate 29 is slidably connected to the rectangular plate 11. The slide plate 29 is rotatably connected to a connecting rod 28 via a rotating shaft via a connecting rod 31. A sliding sleeve 32 is fixedly connected to the rectangular plate 11. One end of the slide plate 29 slides through the sliding sleeve 32 to guide and limit the movement of the slide plate 29. Furthermore, a deflection plate 33 is fixedly connected to one end of shaft 25, and a slide groove 34 is provided at one end of slide plate 29. A shaft 35 that slides through the slide groove 34 is fixedly connected to one end of deflection plate 33. Specifically, during the process of deflecting rectangular plate 11 relative to shaft 25, slide plate 29 will rotate relative to deflection plate 33, thereby driving slide plate 29 to move relative to rectangular plate 11. The moving rectangular plate 11 drives connecting rod 21 to move, thereby pushing connecting rod 1 28 to deflect through connecting rod 2 31, thereby driving extrusion plate 13 to move relative to rectangular plate 11 to extrude water-absorbing elastic bladder 6.

[0020] The sealing component 18 includes a plurality of perforated plates 36 slidably connected to the extrusion plate 13. The plurality of perforated plates 36 correspond one-to-one with a plurality of water inlet holes 17. A strip plate 37 is fixedly connected between the plurality of perforated plates 36. A sliding plate 38 is fixedly connected to the strip plate 37. One end of the sliding plate 38 slides through the extrusion plate 13 and is rotatably connected to a roller 39 via a rotating shaft. When the extrusion plate 13 moves to the bottom end of the phosphating box 1, it pushes the roller 39 through the inner wall of the bottom end of the phosphating box 1, thereby driving the sliding plate 38 to move, thereby driving the perforated plates 36 fixedly connected to the strip plate 37 to move, so that the holes on the perforated plates 36 are aligned with the water inlet holes 17 for connection. Furthermore, a spring piece 41 is provided between the strip plate 37 and the inner wall of the extrusion plate 13. When a pushing force is applied to the strip plate 37 to cause it to move, the spring piece 41 will deform due to the extrusion action of the strip plate 37 and the inner wall of the extrusion plate 13. During this process, the deformed spring piece 41 will generate a self-restoring elastic force, which can provide the necessary power support for the subsequent reset of the strip plate 37.

[0021] A limiting protrusion 42 is fixedly connected to the U-shaped frame 20. When the rectangular plate 11 is at the bottom of the phosphating box 1, the limiting protrusion 42 contacts and abuts against the connecting plate 23, thereby limiting the rectangular plate 11 and ensuring that it can stably scrape off the precipitate.

[0022] The inner walls of the top and bottom of the phosphating box 1 are fixedly connected to inner support plates 43 that abut against the inner side of the chain to improve the stability of the device during operation. A limit plate 44 is fixedly connected to one side of the U-shaped frame 20. A side support plate 45 is fixedly connected to one end of the inner support plate 43 at the top of the phosphating box 1. A guide groove 46 is provided on the side support plate 45. During the movement of the rectangular plate 11 along the top of the phosphating box 1, the limit plate 44 can be driven to slide along the guide groove 46, thereby guiding and limiting the movement of the U-shaped frame 20 to improve the stability of the device during operation.

[0023] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0024] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention.

Claims

1. A phosphating device for pretreatment in a large-scale metal surface coating production line, comprising a phosphating chamber (1), characterized in that, It also includes: A collection tank (2) is set at one corner of the bottom of the phosphating box (1). A sludge suction pipe (3) is provided on the phosphating box (1). One end of the sludge suction pipe (3) is located in the collection tank (2), and the sludge suction pipe (3) is connected to an external water pump. A scraper (4) is installed inside the phosphating box (1) to push the sediment at the bottom of the phosphating box (1) into the collection tank (2); A circulating drive unit (5) is installed inside the phosphating box (1) and connected to the scraper (4) to drive the scraper (4) to circulate between the top and bottom of the phosphating box (1); The water-absorbing elastic bladder (6) is set on one side of the scraper (4) and is used to absorb the lower layer of water in the phosphating tank (1) when the scraper (4) is at the bottom of the phosphating tank (1); The extrusion member (7) is set on the scraper (4) and connected to the water-absorbing elastic bladder (6). When the scraper (4) moves to the upper layer of the phosphating box (1), it cooperates with the scraper (4) to expel the water in the lower layer of the phosphating box (1) to mix the water in the phosphating box (1).

2. The phosphating device for pretreatment in a large-scale metal surface coating production line according to claim 1, characterized in that: The scraper (4) adopts a symmetrical split design, which includes two rectangular plates (11). The phosphating box (1) is provided with a deflector (12) connected to the rectangular plates (11). When the rectangular plates (11) move to the top of the phosphating box (1), the two rectangular plates (11) are deflected to the side of the phosphating box (1) to avoid the workpiece. The extrusion member (7) includes an extrusion plate (13) disposed on one side of the rectangular plate (11). A linkage member (14) is provided between the extrusion plate (13) and the rectangular plate (11) for moving the extrusion plate (13) toward the rectangular plate (11) when the rectangular plate (11) is deflected, so as to extrude the water-absorbing elastic bladder (6). The water-absorbing elastic bladder (6) is fixedly connected to one side of the extrusion plate (13), and a water outlet pipe (15) is fixedly connected to the extrusion plate (13). The water outlet pipe (15) is connected to the water-absorbing elastic bladder (6), and a one-way valve (16) is installed in the water outlet pipe (15) for allowing only water to flow out of the water-absorbing elastic bladder (6). A water inlet hole (17) is provided on the extrusion plate (13), and a sealing member (18) is provided on the extrusion plate (13) to block the water inlet hole (17) when the extrusion plate (13) is at the top of the phosphating box (1), and to open the water inlet hole (17) when the extrusion plate (13) is at the top of the phosphating box (1).

3. The phosphating device for pretreatment in a large-scale metal surface coating production line according to claim 2, characterized in that: The circulating drive component (5) includes shafts (19) rotatably connected to the four corners of the phosphating box (1). Multiple shafts (19) are fixedly connected to sprockets (21) at their ends. The sprockets (21) are connected to each other by a chain. One end of one shaft (19) passes through the phosphating box (1). A drive motor (22) is fixedly connected to the phosphating box (1). The output shaft of the drive motor (22) is fixed to one of the shafts (19). A U-shaped frame (20) is installed on the chain. The rectangular plate (11) is connected to the U-shaped frame (20).

4. The phosphating device for pretreatment in a large-scale metal surface coating production line according to claim 3, characterized in that: The deflector (12) includes a connecting plate (23) fixedly connected to one side of the rectangular plate (11). A hollow column (24) is fixedly connected to one end of the connecting plate (23). A shaft (25) is fixedly connected to the U-shaped frame (20). One end of the shaft (25) passes through the hollow column (24) and is rotatably connected to it. A torsion spring (26) is installed inside the hollow column (24) and sleeved on the shaft (25). Both ends of the torsion spring (26) are fixed to the inner wall of the hollow column (24) and the shaft (25) respectively. When the rectangular plate (11) is deflected, the torsion spring (26) is subjected to torsion to provide self-recovering elastic force. A top plate (27) is fixedly connected to the inner wall of the top of the phosphating box (1) to hold one end of the rectangular plate (11) in place when the rectangular plate (11) moves, so that the rectangular plate (11) deflects. One end of the top plate (27) is designed with a slope.

5. The phosphating device for pretreatment in a large-scale metal surface coating production line according to claim 4, characterized in that: The linkage (14) includes multiple connecting rods (28) disposed between the rectangular plate (11) and the extrusion plate (13). The two ends of the multiple connecting rods (28) are rotatably connected to the rectangular plate (11) and the extrusion plate (13) respectively via a rotating shaft. The water-absorbing elastic bladder (6) is slidably connected to the side of the rectangular plate (11), and a sliding plate (29) is slidably connected to the rectangular plate (11). The sliding plate (29) is rotatably connected to one of the connecting rods (28) via a rotating shaft via a connecting rod (31). A sliding sleeve (32) is fixedly connected to the rectangular plate (11). One end of the sliding plate (29) slides through the sliding sleeve (32) to guide and limit the movement of the sliding plate (29). Furthermore, a deflection plate (33) is fixedly connected to one end of the second shaft (25), a slide groove (34) is provided at one end of the slide plate (29), and a third shaft (35) that slides through the slide groove (34) is fixedly connected to one end of the deflection plate (33).

6. The phosphating device for pretreatment in a large-scale metal surface coating production line according to claim 5, characterized in that: The sealing component (18) includes multiple perforated plates (36) slidably connected to the extrusion plate (13). The multiple perforated plates (36) correspond one-to-one with multiple water inlets (17). A strip plate (37) is fixedly connected between the multiple perforated plates (36). A sliding plate (38) is fixedly connected to the strip plate (37). One end of the sliding plate (38) slides through the extrusion plate (13) and is rotatably connected to a roller (39) via a rotating shaft. When the extrusion plate (13) moves to the bottom of the phosphating box (1), the roller (39) is pushed by the inner wall of the bottom of the phosphating box (1) to drive the perforated plates (36) to move so that the holes on the perforated plates (36) are aligned with the water inlets (17) for connection. Furthermore, a spring sheet (41) is provided between the inner wall of the strip plate (37) and the extrusion plate (13).

7. The phosphating device for pretreatment in a large-scale metal surface coating production line according to claim 6, characterized in that: A limiting protrusion (42) is fixedly connected to the U-shaped frame (20). When the rectangular plate (11) is at the bottom of the phosphating box (1), the limiting protrusion (42) contacts and abuts against the connecting plate (23).

8. The phosphating device for pretreatment in a large-scale metal surface coating production line according to claim 7, characterized in that: The inner wall of the top and bottom of the phosphating box (1) is fixedly connected with an inner support plate (43) that contacts and abuts against the inner side of the chain. A limit plate (44) is fixedly connected to one side of the U-shaped frame (20). A side support plate (45) is fixedly connected to one end of the inner support plate (43) at the top of the phosphating box (1). A guide groove (46) is provided on the side support plate (45). During the movement of the rectangular plate (11) along the top of the phosphating box (1), the limit plate (44) can be driven to slide along the guide groove (46), thereby guiding and limiting the movement of the U-shaped frame (20).

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