A coating delivery cleaning system and a prepainted sheet production line

Abstract

The present application belongs to the technical field of color coated steel plate processing, and particularly relates to a coating conveying and cleaning system and a color coated plate production line, which comprises at least one coating supply unit and a cleaning unit, the coating supply unit comprises a coating conveying mechanism and a buffer barrel, the buffer barrel is fixedly communicated with a medium output end of the coating conveying mechanism; a mounting interface communicating with an inner cavity of the buffer barrel is formed at a top end of the buffer barrel, and the mounting interface is detachably assembled with a cleaning quick connector; the cleaning unit comprises a cleaning fluid supply pipeline, and the cleaning fluid supply pipeline is detachably and switchably communicated with the inner cavity of the buffer barrel through the cleaning quick connector. The present application solves the problem that incomplete manual cleaning causes residual coating to affect subsequent matching precision and coating quality, and also solves the problem of overflow of organic solvent vapor in the cleaning process, thereby inhibiting unorganized emission of volatile organic compounds from the source, and meeting increasingly strict environmental protection and occupational health and safety requirements.

Description

Technical Field

[0001] This invention belongs to the technical field of color-coated steel plate processing, specifically relating to a paint conveying and cleaning system and a color-coated plate production line, which is particularly suitable for the automatic supply, circulation and cleaning of paint in a continuous color-coating production line. Background Technology

[0002] Color-coated steel sheets (hereinafter referred to as color-coated sheets) are produced on continuous production lines using cold-rolled strip steel or galvanized strip steel as substrates. After surface pretreatment, one or more layers of liquid coating are applied using a roller coating method, followed by baking and cooling. The continuous production of color-coated sheets consumes large quantities of various colors of paint and thinner. Before production, the required paint and thinner need to be further mixed. The mixed paint is then transported to the coating room via pipelines and pumped into paint trays for coating. Traditional paint mixing, conveying, and cleaning operations largely rely on manual labor, resulting in problems such as large mixing errors and arbitrary parameter recording.

[0003] Existing technologies include research on automated coating delivery functions. For example, patent document CN222943748U discloses a centrifugal roller cold coating batching device and an automatic batching and spraying system. This system connects a coating storage tank and a thinner storage tank to the main delivery pipeline and uses electric valves and a delivery pump to achieve coating delivery. Another example is a coating delivery system disclosed in patent document CN110026310A, which uses a pneumatic diaphragm pump to deliver coating to the spray gun and includes a return pipeline to allow the coating to flow back to the coating tank when the spray gun is not in operation. However, after delivery, the buffer tank, mixing tank, and delivery pipeline of such systems often require manual disassembly or separate cleaning equipment for cleaning. This results in low cleaning efficiency and incomplete cleaning, affecting the accuracy of subsequent coating proportions and spraying quality, and increasing equipment maintenance difficulty and downtime. Furthermore, regardless of whether manual disassembly or dedicated cleaning equipment is used, it is difficult to effectively suppress the leakage of fugitive gases during the cleaning process, which can easily cause pollution to the production environment.

[0004] In summary, existing technologies for conveying and cleaning pre-coated steel sheet coatings still have significant limitations: On the one hand, the cleaning process heavily relies on manual disassembly or independent equipment, which is not only time-consuming and labor-intensive, but also inefficient and difficult to guarantee thoroughness, severely restricting the accuracy of subsequent coating proportions and the stability of coating quality, while also increasing equipment maintenance costs and downtime; on the other hand, the lack of effective suppression of fugitive emissions of volatile organic compounds during coating conveying and cleaning operations leads to deterioration of workshop air quality, failing to meet increasingly stringent environmental protection and occupational health and safety requirements. Therefore, a new technical solution is needed to address these technical problems. Summary of the Invention

[0005] The purpose of this invention is to provide a paint conveying and cleaning system and a color-coated steel sheet production line to solve the problems mentioned in the background art, such as the current paint conveying and cleaning technology for color-coated steel sheets severely restricting the accuracy of subsequent paint mixing and the stability of coating quality, increasing equipment maintenance costs and downtime; at the same time, it also lacks effective suppression of fugitive emissions of volatile organic compounds, causing deterioration of workshop air quality and failing to meet increasingly stringent environmental protection and occupational health and safety requirements.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a paint delivery and cleaning system, comprising at least one paint supply unit and a cleaning unit. The paint supply unit includes a paint delivery mechanism and a buffer tank, the buffer tank being fixedly connected to the medium output end of the paint delivery mechanism. The top of the buffer tank is provided with an installation interface communicating with its inner cavity, the installation interface being detachably equipped with a cleaning quick connector. The cleaning unit includes a cleaning fluid supply pipeline, the cleaning fluid supply pipeline being detachably connected to the inner cavity of the buffer tank via a cleaning quick connector. The cleaning unit is used to deliver cleaning fluid into the buffer tank to complete a closed-loop cleaning operation on the buffer tank body and all paint delivery pipelines connected to the buffer tank.

[0007] Furthermore, the coating conveying mechanism includes a primer conveying mechanism, a back paint conveying mechanism, and a top coat conveying mechanism. The media output ends of the primer conveying mechanism and the back paint conveying mechanism are connected to a primary coating machine, and the media output end of the top coat conveying mechanism is connected to a finishing coating machine.

[0008] Furthermore, the primer conveying mechanism and the back coat conveying mechanism have the same structure and both include a primary coating thinner bucket, a primary coating paint bucket, and a primary coating mixing bucket. The primary coating thinner bucket and the primary coating paint bucket are arranged in parallel, and their media output ends are connected to the media input end of the primary coating mixing bucket through a primary coating conveying pipeline. A primary coating one-way pump is installed on the primary coating conveying pipeline. The input end of the primary coating one-way pump is connected to the media output ends of the primary coating thinner bucket and the primary coating paint bucket respectively through the primary coating conveying pipeline. A primary coating normally open solenoid valve is separately installed on the primary coating conveying pipeline corresponding to the primary coating thinner bucket and the primary coating paint bucket. The output end of the primary coating one-way pump is connected to the media input end of the primary coating mixing bucket through the primary coating conveying pipeline. A primary coating hose, a primary coating quick-connect fitting, and a primary coating electric valve are sequentially connected in series along the medium conveying direction on the primary coating delivery pipeline between the unidirectional pump and the primary coating mixing tank. A primary coating bidirectional pump is also installed on the primary coating delivery pipeline. One end of the bidirectional pump is connected to the medium output end of the primary coating mixing tank through the primary coating delivery pipeline, and the other end is connected to the installation interface of the corresponding buffer tank through the primary coating delivery pipeline. A primary coating ball valve is installed on the primary coating delivery pipeline between the installation interface and the bidirectional pump. Two sets of bypass pipelines are also provided on the primary coating delivery pipeline. Each set of bypass pipelines is connected in parallel to the primary coating unidirectional pump and the primary coating bidirectional pump, respectively. Each bypass pipeline is equipped with a normally closed primary coating solenoid valve.

[0009] Furthermore, the topcoat conveying mechanism includes at least one set of color paint conveying units. Each set of color paint conveying units has the same structure and includes a thinner bucket, a paint bucket, and a mixing bucket. The thinner bucket and the paint bucket are arranged in parallel, and their media output ends are connected to the media input end of the mixing bucket via a thinner conveying pipeline. A one-way pump is installed on the thinner conveying pipeline. The input end of the one-way pump is connected to the media output ends of the thinner bucket and the paint bucket via the thinner conveying pipeline. A normally open solenoid valve is individually installed on the thinner conveying pipeline corresponding to the output ends of the thinner bucket and the paint bucket. The output end of the one-way pump is connected to the mixing bucket via the thinner conveying pipeline. At the medium input end of the tank, and on the fine coating conveying pipeline between the fine coating unidirectional pump and the fine coating mixing tank, a fine coating hose, a fine coating quick connector, and a fine coating electric valve are sequentially connected in series along the medium conveying direction; a fine coating bidirectional pump is also installed on the fine coating conveying pipeline, one end of which is connected to the medium output end of the fine coating mixing tank through the fine coating conveying pipeline, and the other end of which is connected to the installation interface of the corresponding buffer tank through the fine coating conveying pipeline. A fine coating ball valve is installed on the fine coating conveying pipeline between the installation interface and the fine coating bidirectional pump; two sets of bypass pipelines are also provided on the fine coating conveying pipeline, and the two sets of bypass pipelines are respectively connected in parallel with the fine coating unidirectional pump and the fine coating bidirectional pump, and each of the bypass pipelines is equipped with a fine coating normally closed solenoid valve.

[0010] Furthermore, the cleaning unit also includes a cleaning thinner tank. The medium output end of the cleaning thinner tank is connected to the input end of the cleaning fluid supply pipeline. The output end of the cleaning fluid supply pipeline branches to form multiple independent cleaning branches. Each cleaning branch is equipped with a cleaning ball valve and a cleaning quick connector in series along the direction of cleaning fluid flow. Each cleaning quick connector corresponds to and can be detachably connected to the installation interface of each buffer tank, so that each buffer tank forms a switchable closed-loop cleaning circuit with the cleaning thinner tank through the corresponding cleaning branch, the cleaning fluid supply pipeline and the cleaning thinner tank.

[0011] In addition to the above technical solutions, there are also color-coated steel sheet production lines equipped with this paint conveying and cleaning system.

[0012] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention, by opening an installation interface at the top of the buffer tank and assembling a quick-connect cleaning connector, allows the cleaning unit to be detachably connected to the inner cavity of the buffer tank via this quick-connect connector. During cleaning, the cleaning fluid enters all the paint delivery pipelines connected to the buffer tank through the buffer tank, completing a closed-loop cleaning operation on the buffer tank body and the entire delivery pipeline system. Compared to existing technologies that require manual disassembly of pipelines or the use of separate cleaning equipment, this system can complete system-level cleaning without disassembling any pipeline components, significantly shortening cleaning time and reducing equipment downtime. It also effectively avoids the problem of residual paint affecting subsequent mixing accuracy and coating quality due to incomplete manual cleaning. Furthermore, the fixed connection design between the buffer tank and the paint delivery pipeline, and the detachable sealed connection between the quick-connect cleaning connector and the installation interface, ensure that the entire paint delivery and cleaning process is completed within a closed pipeline system. The cleaning fluid circulates in the closed loop, effectively preventing the leakage of organic solvent vapors during cleaning and suppressing the fugitive emission of volatile organic compounds at the source, meeting increasingly stringent environmental protection and occupational health and safety requirements.

[0013] 2. This invention organically integrates the paint supply unit and the cleaning unit. The paint conveying mechanism includes a primer conveying mechanism, a back coat conveying mechanism, and a top coat conveying mechanism, which are respectively connected to the primer coater and the finish coater. Through the coordinated operation of unidirectional pumps, bidirectional pumps, solenoid valves, ball valves, and bypass pipelines, each conveying mechanism can achieve automatic proportioning, conveying, and return of thinner and paint. During cleaning, simply switching the corresponding valve state and starting the bidirectional pump is sufficient to automatically complete the cleaning of designated pipelines and buffer tanks. The entire system requires no manual intervention for disassembly, handling, or separate cleaning equipment operation, greatly reducing the labor intensity and skill requirements of operators, while also reducing equipment maintenance frequency and costs.

[0014] 3. This invention employs a unidirectional pump for forward conveying of coatings and thinners, and a bidirectional pump for bidirectional circulation of the cleaning medium. It is equipped with normally open and normally closed solenoid valves working in tandem: during conveying, the main valve is open and the bypass valve is closed; during recovery and cleaning, the bypass valve is switched on. The medium flow direction is automatically switched by an electronic control program, eliminating the need for manual valve operation and significantly reducing the error rate, thus preventing mixing and spillage accidents caused by human error. Furthermore, the invention incorporates a series hose structure between the unidirectional pump and the mixing tank to buffer the fluid impact generated by the pump, reducing pipeline vibration and leakage risks. A quick-connect coupling is located in the middle of the pipeline, allowing for partial disconnection during pipeline blockage or equipment maintenance, eliminating the need for complete pipeline disassembly, thus simplifying maintenance and reducing downtime.

[0015] 4. This invention activates a unidirectional pump in the early stages of cleaning, connected to a normally closed solenoid valve, automatically returning any remaining unpainted paint in the pipeline to the corresponding unpainted paint bucket. Compared to existing technologies where residual paint in the pipeline can only be discarded directly with the cleaning thinner, this system significantly reduces the loss of high-value paint, resulting in a substantial reduction in paint procurement costs in long-term production. After the entire pipeline is cleaned, the mixed thinner is returned to the dedicated unpainted thinner bucket via an independent return pipeline, preventing the generation of disposable cleaning solvents. The recovered thinner can be directly used for mixing paints of the same color family. This differs from the existing model where cleaning waste is collected and difficult to reuse, requiring hazardous waste disposal. This significantly reduces thinner consumption, while also lowering hazardous waste generation and disposal costs, achieving both economic and environmental benefits.

[0016] 5. This invention, by installing standardized, detachable quick-connect cleaning connectors on the top of each mixing tank and buffer tank, and by providing multiple independent cleaning branches within the cleaning unit, with each branch controlled individually by a ball valve, physically isolates the cleaning circuits for different colored paints, completely preventing cross-contamination of different thinners and paints, and ensuring color consistency in each batch of color-coated steel sheets. Furthermore, by replacing the universal standard quick-connect cleaning connectors with individual cleaning fluid supply pipelines, all buffer tanks at the initial coating and finishing coating stations on the production line can be connected sequentially. One cleaning unit can serve multiple paint supply units, eliminating the need for a separate cleaning unit for each mixing and buffer station, significantly reducing investment in cleaning equipment. Moreover, when adding a new paint coating station to the production line, only the buffer tank needs to be added with the same installation interface to connect to the existing cleaning unit, without the need to re-lay the main cleaning pipeline. Additionally, the quick-connect connectors and installation interfaces are independent consumable parts, which can be replaced individually when damaged, eliminating the need to replace the entire buffer tank or pipeline, resulting in lower equipment maintenance costs. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the principle structure of the paint delivery and cleaning system of the present invention; Figure 2 for Figure 1 A schematic diagram illustrating the principle and structure of the intermediate and primary coating sections; Figure 3 for Figure 1 A schematic diagram illustrating the principle and structure of the intermediate coating section; Figure 4 for Figure 1 A schematic diagram of the principle structure of the cleaning unit; Figure 5 This is a schematic cross-sectional view of the mixing tank of the present invention.

[0018] The components include: 1. Primer buffer tank; 2. Back coat buffer tank; 3. Initial coat thinner tank; 4. Initial coat paint tank; 5. Initial coat mixing tank; 6. Initial coat delivery pipeline; 7. Initial coat one-way pump; 8. Initial coat normally open solenoid valve; 9. Initial coat hose; 10. Initial coat quick connector; 11. Initial coat electric valve; 12. Initial coat two-way pump; 13. Initial coat ball valve; 14. Initial coat normally closed solenoid valve; 15. Topcoat buffer tank; 16. Finishing coat thinner tank; 17. Finishing coat paint tank; 18. Finishing coat mixing tank; 19. Finishing coat... 20. Coating delivery pipeline; 21. Fine coating one-way pump; 22. Fine coating normally open solenoid valve; 23. Fine coating hose; 24. Fine coating quick connector; 25. Fine coating electric valve; 26. Fine coating two-way pump; 27. Fine coating ball valve; 28. Cleaning thinner tank; 29. ​​Cleaning fluid supply pipeline; 30. Cleaning ball valve; 31. Cleaning quick connector; 32. Fine coating normally closed solenoid valve; 33. Tank body; 34. Agitator; 35. Discharge pipe; 36. Discharge hole; 37. Double-ended internal threaded connector; 38. Cleaning pump. Detailed Implementation

[0019] The following examples are used to further illustrate the content of the present invention and do not limit the application of the present invention. Example 1:

[0020] Please see Figures 1-5 This embodiment provides a paint delivery and cleaning system, including a primary coating supply unit, a fine coating supply unit, and a cleaning unit. The cleaning unit is used to deliver cleaning fluid into the primary coating supply unit and the fine coating supply unit to complete a closed-loop cleaning operation for the primary coating supply unit, the fine coating supply unit, and all paint delivery pipelines connected to them.

[0021] The primary coating supply unit includes a primer conveying mechanism, a back coating conveying mechanism, a primer buffer tank 1 fixedly connected to the medium output end of the primer conveying mechanism, and a back coating buffer tank 2 fixedly connected to the medium output end of the back coating conveying mechanism. The medium output ends of both the primer buffer tank 1 and the back coating buffer tank 2 are connected to a primary coating machine (the functions and structures of conventional equipment such as primary coating machines are well known in the art, and the connection settings are also common knowledge, so they will not be described in detail here, and are not shown in the attached drawings). The primer conveying mechanism and the back paint conveying mechanism have the same structure and both include a primary coating thinner bucket 3, a primary coating paint bucket 4 and a primary coating mixing bucket 5. The primary coating thinner bucket 3 and the primary coating paint bucket 4 are arranged in parallel, and the media output ends of both are connected to the media input end of the primary coating mixing bucket 5 through the primary coating conveying pipe 6. A primary coating unidirectional pump 7 is installed on the primary coating conveying pipeline 6. The input end of the primary coating unidirectional pump 7 is connected to the medium output end of the primary coating thinner tank 3 and the medium output end of the primary coating paint tank 4 through the primary coating conveying pipeline 6. A primary coating normally open solenoid valve 8 is installed separately on the primary coating conveying pipeline 6 corresponding to the primary coating thinner tank 3 and the primary coating paint tank 4. The output end of the primary coating unidirectional pump 7 is connected to the medium input end of the primary coating mixing tank 5 through the primary coating conveying pipeline 6. A primary coating hose 9, a primary coating quick connector 10 and a primary coating electric valve 11 are connected in series along the medium conveying direction on the primary coating conveying pipeline 6 between the primary coating unidirectional pump 7 and the primary coating mixing tank 5. The primary coating conveying pipeline 6 is also equipped with a primary coating bidirectional pump 12. One end of the primary coating bidirectional pump 12 is connected to the medium output end of the primary coating mixing tank 5 through the primary coating conveying pipeline 6, and the other end of the primary coating bidirectional pump 12 is connected to the installation interface of the corresponding primer buffer tank 1 or back paint buffer tank 2 through the primary coating conveying pipeline 6. A primary coating ball valve 13 is installed on the primary coating conveying pipeline 6 between the installation interface and the primary coating bidirectional pump 12. The primary coating delivery pipeline 6 is also equipped with two sets of bypass pipelines, which are connected in parallel to the primary coating unidirectional pump 7 and the primary coating bidirectional pump 12 respectively. Each bypass pipeline is equipped with a primary coating normally closed solenoid valve 14.

[0022] The fine coating supply unit includes a topcoat conveying mechanism and a topcoat buffer tank 15 that is fixedly connected to the medium output end of the topcoat conveying mechanism. The medium output ends of the topcoat buffer tank 15 are all connected to a fine coating machine (the functions and structures of conventional equipment such as fine coating machines are well known in the art, and the connection settings are also common knowledge, so they will not be described in detail here, and are not shown in the accompanying drawings). The topcoat conveying mechanism includes three sets of color paint conveying units (since topcoat is commonly used in three colors, this embodiment uses three sets of color paint conveying units as an example). The three sets of color paint conveying units have the same structure and each includes a fine coating thinner bucket 16, a fine coating paint bucket 17, and a fine coating mixing bucket 18. The fine coating thinner bucket 16 and the fine coating paint bucket 17 are arranged in parallel, and the medium output ends of both are connected to the medium input end of the fine coating mixing bucket 18 through the fine coating conveying pipe 19. A fine coating one-way pump 20 is installed on the fine coating conveying pipeline 19. The input end of the fine coating one-way pump 20 is connected to the medium output end of the fine coating thinner bucket 16 and the medium output end of the fine coating paint bucket 17 through the fine coating conveying pipeline 19. A fine coating normally open solenoid valve 21 is installed separately on the fine coating conveying pipeline 19 corresponding to the output ends of the fine coating thinner bucket 16 and the fine coating paint bucket 17. The output end of the fine coating one-way pump 20 is connected to the medium input end of the fine coating mixing bucket 18 through the fine coating conveying pipeline 19. A fine coating hose 22, a fine coating quick connector 23 and a fine coating electric valve 24 are installed in series along the medium conveying direction on the fine coating conveying pipeline 19 between the fine coating one-way pump 20 and the fine coating mixing bucket 18. The fine coating conveying pipeline 19 is also equipped with a fine coating bidirectional pump 25. One end of the fine coating bidirectional pump 25 is connected to the medium output end of the fine coating mixing tank 18 through the fine coating conveying pipeline 19, and the other end of the fine coating bidirectional pump 25 is connected to the installation interface of the corresponding topcoat buffer tank 15 through the fine coating conveying pipeline 19. A fine coating ball valve 26 is installed on the fine coating conveying pipeline 19 between the installation interface and the fine coating bidirectional pump 25. The fine coating conveying pipeline 19 is also equipped with two sets of bypass pipelines, which are connected in parallel to the fine coating one-way pump 20 and the fine coating two-way pump 25 respectively. Each bypass pipeline is equipped with a fine coating normally closed solenoid valve 31.

[0023] The cleaning unit includes a cleaning thinner tank 27 and a cleaning fluid supply pipeline 28. The medium output end of the cleaning thinner tank 27 is connected to the input end of the cleaning pump 37, and the output end of the cleaning pump 37 is connected to the input end of the cleaning fluid supply pipeline 28. A cleaning pump 37 (one-way pump) is installed on the cleaning fluid supply pipeline 28 to pump the thinner from the cleaning thinner tank 27 into the cleaning fluid supply pipeline 28. The output end of the cleaning fluid supply pipeline 28 branches to form multiple independent cleaning branches, and each cleaning branch is connected in series along the direction of cleaning fluid flow. The assembly is equipped with a cleaning ball valve 29 and a cleaning quick connector 30. Each cleaning quick connector 30 is detachably connected to the installation interface of each buffer tank (each buffer tank includes a primer buffer tank 1, a back paint buffer tank 2, and three topcoat buffer tanks 15. Among them, two topcoat buffer tanks 15 of different colors are close to each other. In order to save the cost of laying cleaning branch lines, they can share a cleaning quick connector 30). This allows each buffer tank to form a switchable closed-loop cleaning circuit with the corresponding cleaning branch line, the cleaning fluid supply pipeline 28, and the cleaning thinner tank 27.

[0024] Please see Figure 5All the above mixing tanks include a tank body 32 and a mixer 33. The top side of the tank body 32 is inserted and connected to the medium output end of the corresponding conveying pipes (each conveying pipe includes the initial coating conveying pipe 6 and the fine coating conveying pipe 19), so that each conveying pipe can transport the mixed paint in the tank body 32 to the corresponding buffer tank. There is a vertical discharge pipe 34 on one side of the inside of the tank body 32. The upper end of the discharge pipe 34 is provided with multiple discharge holes 35 (the discharge holes can divide the paint into multiple fine streams when it is sprayed from the discharge pipe, which can effectively prevent the paint from being sprayed out of the discharge pipe). (caking), the lower end of the discharge pipe 34 penetrates the bottom side wall of the barrel 32 and extends to the outside of the barrel 32, and is fixedly connected to the medium input end of each corresponding conveying pipe. The end of the discharge pipe 34 extending outside the barrel 32 is threadedly connected to a double-ended internal threaded connector 36 (for fixing the discharge pipe 34). Each electric valve (including the initial coating electric valve 11 and the fine coating electric valve 24) is connected to the medium input end of the conveying pipe, so that each conveying pipe can convey the corresponding thinner and oil into the barrel 32 and mix them by the agitator 33.

[0025] The working principle and usage process of this embodiment are as follows: Figures 1-5 As shown, after the paint conveying and cleaning system is assembled, the operator installs the entire system on the color-coated steel sheet production line (the functions and structures of conventional equipment such as color-coated steel sheet production lines are well known in the field, and the connection settings are also common knowledge, so they will not be explained in detail here, nor are they shown in the attached drawings). The purpose is to solve the problem of residual paint affecting the subsequent mixing accuracy and coating quality due to incomplete manual cleaning. At the same time, it also solves the problem of organic solvent vapor overflow during the cleaning process, suppressing the fugitive emission of volatile organic compounds from the source, which meets the increasingly stringent environmental protection and occupational health and safety requirements.

[0026] The paint conveying and cleaning system provided in this embodiment mainly operates in two working modes: paint conveying and supply mode and cleaning operation mode. The two modes are automatically switched through the state switching of each valve and the start and stop control of the pump.

[0027] When the system enters the paint delivery mode, the working process of the primer delivery mechanism and the back coat delivery mechanism is exactly the same. Taking the primer delivery mechanism as an example, the working process of the finish coat delivery unit is similar to that of the initial coat delivery unit. Taking one set of color paint delivery units as an example, the specific working process is as follows: Taking the primer conveying mechanism as an example, the working principle of the back coat conveying mechanism is exactly the same as that of the primer conveying mechanism. The operator starts the paint conveying program according to production needs. At this time, the normally open solenoid valve 8 corresponding to the initial coating thinner bucket 3 and the normally open solenoid valve 8 corresponding to the initial coating paint bucket 4 are both in the open state. The normally closed solenoid valves 14 on the two sets of bypass pipelines are in the closed state. The initial coating electric valve 11 is open, the initial coating ball valve 13 is open, and the initial coating one-way pump 7 starts running. The thinner in the initial coating thinner bucket 3 and the paint in the initial coating paint bucket 4 are respectively drawn by the initial coating one-way pump 7 through their respective initial coating conveying pipelines 6. After the two media converge at the output end of the initial coating one-way pump 7, they flow sequentially through the initial coating conveying pipeline 6 through the initial coating hose 9, the initial coating quick connector 10, and the initial coating electric valve 11, and are finally conveyed to the initial coating mixing tank 5. During this process, the initial coating hose 9 effectively buffers the fluid impact generated by the initial coating one-way pump 7, reducing pipeline vibration and leakage risks.

[0028] Thinner and paint are thoroughly mixed in the primary coating mixing tank 5 by agitator 33 to form a blended coating that meets the process requirements. The uniformly mixed coating is discharged through the discharge pipe 34 at the bottom of the primary coating mixing tank 5 and, driven by the primary coating bidirectional pump 12, is transported through the primary coating conveying pipe 6 to the corresponding primer buffer tank 1 or back coat buffer tank 2 for temporary storage. The coating in the primer buffer tank 1 and back coat buffer tank 2 is then supplied to the corresponding primary coating machines to complete the primer and back coat coating operations.

[0029] The operation of the fine coating supply unit is similar to that of the primary coating supply unit. Taking one set of color paint conveying units as an example, the normally open solenoid valve 21 corresponding to the fine coating thinner bucket 16 and the normally open solenoid valve 21 corresponding to the fine coating paint bucket 17 are both in the open state. The normally closed solenoid valves 31 on the two bypass pipelines are in the closed state. The fine coating electric valve 24 is open, the fine coating ball valve 26 is open, and the fine coating one-way pump 20 is started. The thinner in the fine coating thinner bucket 16 and the paint in the fine coating paint bucket 17 are respectively drawn by the fine coating one-way pump 20, and after merging, they flow through the fine coating conveying pipeline 19 in sequence through the fine coating hose 22, the fine coating quick connector 23, and the fine coating electric valve 24, and are conveyed to the fine coating mixing tank 18 for mixing. The uniformly mixed topcoat paint is discharged through the discharge pipe at the bottom of the fine coating mixing tank 18, and is conveyed to the corresponding topcoat buffer tank 15 for temporary storage under the drive of the fine coating two-way pump 25, and then supplied to the fine coating machine to complete the topcoat coating operation. Since topcoat is often used in a variety of colors, this embodiment uses three sets of color paint conveying units to correspond to three different colors of topcoat paint. Each color paint conveying unit works independently and in parallel to meet the continuous production requirements of changing colors without stopping the machine.

[0030] When a batch of paint is supplied or a paint color needs to be changed, the system switches to cleaning mode. Taking the cleaning of the pipeline corresponding to the primer delivery mechanism as an example, the cleaning process is as follows: Step 1, Residual Paint Return: After disassembling the quick-connect cleaning connector 30, the operator connects it to the mounting interface at the top of the primer buffer tank 1. Then, the operator shuts off the primary coating one-way pump 7, closes the primary coating normally open solenoid valve 8 corresponding to the primary coating thinner tank 3, and opens the primary coating normally closed solenoid valve 14 on the bypass pipeline connected in parallel with the primary coating one-way pump 7, while keeping the primary coating normally open solenoid valve 8 corresponding to the primary coating paint tank 4 open. At this time, the unpainted paint remaining in the primary coating delivery pipeline 6 and the primary coating mixing tank 5 is returned to the primary coating paint tank 4 via the bypass pipeline, driven by the primary coating two-way pump 12. This step automatically recovers the unpainted paint remaining in the pipeline, significantly reducing the loss of high-value paint.

[0031] Step 2, Thinner Cleaning: After the residual paint has been returned, close the normally closed solenoid valve 14 of the primary coating on the bypass line connected in parallel with the primary coating check pump 7, close the normally open solenoid valve 8 corresponding to the primary coating paint can 4, open the normally open solenoid valve 8 corresponding to the primary coating thinner can 3, and start the primary coating check pump 7. The cleaning thinner in the cleaning thinner can 27 is pumped into the cleaning fluid supply line 28 by the cleaning pump 37, and then enters the inner cavity of the primer buffer tank 1 through the cleaning fluid supply line 28, the corresponding cleaning branch, and the cleaning quick connector 30, and then enters the primary coating mixing tank 5 through the primary coating delivery line 6. The agitator 33 in the primary coating mixing tank 5 is started to agitate and clean the inside of the tank.

[0032] Step 3: Cleaning of Pipelines and Buffer Tanks: Start the primary coating bidirectional pump 12 to reverse the flow of the cleaning thinner mixed with residual paint in the primary coating mixing tank 5 through the primary coating delivery pipeline 6 to the primer buffer tank 1, cleaning the primer buffer tank 1 and the primary coating delivery pipeline 6. After cleaning, the mixed thinner is drawn back into the primary coating mixing tank 5 by the primary coating bidirectional pump 12, forming a closed-loop cleaning cycle.

[0033] Step 4: Waste Cleaning Liquid Recovery: Close the primary coating check pump 7, close the primary coating normally open solenoid valve 8 corresponding to the primary coating paint bucket 4, keep the primary coating normally open solenoid valve 8 corresponding to the primary coating thinner bucket 3 in the open state, and open the primary coating normally closed solenoid valve 14 on the bypass pipeline connected in parallel with the primary coating check pump 7. The mixed thinner after cleaning flows back to the primary coating thinner bucket 3 through the discharge pipe 34 at the bottom of the primary coating mixing tank 5, the primary coating conveying pipeline 6, and the bypass pipeline. Since this mixed thinner only contains paint components of the same color, it can be directly recycled for subsequent mixing of paints of the same color, without generating disposable waste cleaning solvent, greatly reducing thinner consumption and hazardous waste generation.

[0034] The cleaning process for each color paint conveying unit in the back paint conveying mechanism and top paint conveying mechanism is exactly the same as the cleaning process for the primer conveying mechanism. For the top paint conveying mechanism, since different color paint conveying units correspond to different colors of top paint, each cleaning branch is equipped with an independent cleaning ball valve 29. By individually controlling the on / off state of each cleaning branch, the cleaning circuits of different color paint pipelines are physically isolated, completely eliminating cross-color mixing between different color thinners and paints, and ensuring the consistency of the top paint color in each batch of color-coated steel sheets.

[0035] Throughout the cleaning process, the cleaning fluid circulates continuously within a closed pipeline system, effectively preventing the leakage of organic solvent vapors and suppressing the fugitive emission of volatile organic compounds at the source. Operators only need to switch the corresponding valve status and start the appropriate pump set to automatically complete the comprehensive cleaning of the designated pipelines and buffer tanks without the need for manual disassembly of any pipeline components, significantly reducing cleaning time and lowering equipment downtime and maintenance costs.

[0036] Through the above-described workflow of conveying, supplying, and cleaning operations, the system achieves the following beneficial effects: (1) Environmental protection and closed system: The entire conveying and cleaning process is completed in a closed pipeline, which effectively suppresses the fugitive emission of volatile organic compounds and improves the workshop environment.

[0037] (2) High efficiency and automation: Through the coordinated control of solenoid valves, unidirectional pumps and bidirectional pumps, the entire process from batching, conveying, reflux to cleaning is fully automated, which greatly reduces the intensity of manual labor and the risk of misoperation.

[0038] (3) Cost saving: The unique residual paint return mechanism and cleaning thinner recycling and reuse mechanism significantly reduce the consumption of paint and solvent, while reducing hazardous waste treatment costs.

[0039] (4) Thorough cleaning: The system adopts a combination of bidirectional pump circulation cleaning and internal mixing cleaning in the mixing tank to ensure that there are no dead corners in the cleaning process and to guarantee the quality stability of subsequent coating products. Example 2:

[0040] Please see Figures 1-5 As another objective of the present invention, a color-coated steel sheet production line is provided, wherein the color-coated steel sheet production line is provided with the paint conveying and cleaning system described above. Therefore, the color-coated steel sheet production line can obtain any of the beneficial effects of the paint conveying and cleaning system described above, which will not be repeated here.

Claims

1. A paint delivery and cleaning system, comprising at least one paint supply unit and a cleaning unit, characterized in that, The paint supply unit includes a paint conveying mechanism and a buffer tank. The buffer tank is fixedly connected to the medium output end of the paint conveying mechanism. The top of the buffer tank has an installation interface that connects to its inner cavity. The installation interface is detachably fitted with a quick-connect cleaning connector. The cleaning unit includes a cleaning fluid supply pipeline. The cleaning fluid supply pipeline is detachably connected to the inner cavity of the buffer tank through a quick-connect cleaning connector. The cleaning unit is used to deliver cleaning fluid into the buffer tank to complete a closed-loop cleaning operation on the buffer tank body and all paint conveying pipelines connected to the buffer tank.

2. The paint conveying and cleaning system according to claim 1, characterized in that, The coating conveying mechanism includes a primer conveying mechanism, a back coat conveying mechanism, and a top coat conveying mechanism. The media output ends of the primer conveying mechanism and the back coat conveying mechanism are connected to a primary coater, and the media output end of the top coat conveying mechanism is connected to a finishing coater.

3. The paint conveying and cleaning system according to claim 2, characterized in that, The primer conveying mechanism and the back paint conveying mechanism have the same structure and both include a primary coating thinner bucket, a primary coating paint bucket, and a primary coating mixing bucket. The primary coating thinner bucket and the primary coating paint bucket are arranged in parallel, and the media output ends of both are connected to the media input end of the primary coating mixing bucket through the primary coating conveying pipeline.

4. The paint conveying and cleaning system according to claim 3, characterized in that, The initial coating conveying pipeline is equipped with an initial coating one-way pump. The input end of the initial coating one-way pump is connected to the medium output end of the initial coating thinner bucket and the medium output end of the initial coating paint bucket through the initial coating conveying pipeline. An initial coating normally open solenoid valve is separately installed on the initial coating conveying pipeline corresponding to the initial coating thinner bucket and the initial coating paint bucket. The output end of the initial coating one-way pump is connected to the medium input end of the initial coating mixing tank through the initial coating conveying pipeline. An initial coating hose, an initial coating quick connector, and an initial coating electric valve are sequentially connected in series along the medium conveying direction on the initial coating conveying pipeline between the initial coating one-way pump and the initial coating mixing tank.

5. A paint conveying and cleaning system according to claim 4, characterized in that, The initial coating delivery pipeline is also equipped with an initial coating bidirectional pump. One end of the initial coating bidirectional pump is connected to the medium output end of the initial coating mixing tank through the initial coating delivery pipeline, and the other end of the initial coating bidirectional pump is connected to the installation interface of the corresponding buffer tank through the initial coating delivery pipeline. An initial coating ball valve is installed on the initial coating delivery pipeline between the installation interface and the initial coating bidirectional pump. The initial coating delivery pipeline is also provided with two sets of bypass pipelines. The two sets of bypass pipelines are respectively connected in parallel with the initial coating unidirectional pump and the initial coating bidirectional pump. Each of the bypass pipelines is equipped with an initial coating normally closed solenoid valve.

6. A paint conveying and cleaning system according to claim 2, characterized in that, The topcoat conveying mechanism includes at least one set of color paint conveying units. Each set of color paint conveying units has the same structure and includes a fine coating thinner bucket, a fine coating paint bucket, and a fine coating mixing bucket. The fine coating thinner bucket and the fine coating paint bucket are arranged in parallel, and the media output ends of both are connected to the media input end of the fine coating mixing bucket through a fine coating conveying pipe.

7. A paint conveying and cleaning system according to claim 6, characterized in that, A fine coating one-way pump is installed on the fine coating conveying pipeline. The input end of the fine coating one-way pump is connected to the medium output end of the fine coating thinner bucket and the medium output end of the fine coating paint bucket through the fine coating conveying pipeline. A fine coating normally open solenoid valve is installed separately on the fine coating conveying pipeline corresponding to the output ends of the fine coating thinner bucket and the fine coating paint bucket. The output end of the fine coating one-way pump is connected to the medium input end of the fine coating mixing bucket through the fine coating conveying pipeline. A fine coating hose, a fine coating quick connector and a fine coating electric valve are installed in series along the medium conveying direction on the fine coating conveying pipeline between the fine coating one-way pump and the fine coating mixing bucket.

8. A paint conveying and cleaning system according to claim 7, characterized in that, The fine coating conveying pipeline is also equipped with a fine coating bidirectional pump. One end of the fine coating bidirectional pump is connected to the medium output end of the fine coating mixing tank through the fine coating conveying pipeline, and the other end of the fine coating bidirectional pump is connected to the installation interface of the corresponding buffer tank through the fine coating conveying pipeline. A fine coating ball valve is installed on the fine coating conveying pipeline between the installation interface and the fine coating bidirectional pump. The fine coating conveying pipeline is also provided with two sets of bypass pipelines. The two sets of bypass pipelines are respectively connected in parallel with the fine coating unidirectional pump and the fine coating bidirectional pump. Each bypass pipeline is equipped with a fine coating normally closed solenoid valve.

9. A paint conveying and cleaning system according to claim 1, characterized in that, The cleaning unit also includes a cleaning thinner tank. The medium output end of the cleaning thinner tank is connected to the input end of the cleaning fluid supply pipeline. The output end of the cleaning fluid supply pipeline branches to form multiple independent cleaning branches. Each cleaning branch is equipped with a cleaning ball valve and a cleaning quick connector in series along the direction of cleaning fluid flow. Each cleaning quick connector corresponds to and can be detachably connected to the installation interface of each buffer tank, so that each buffer tank forms a switchable closed-loop cleaning circuit with the cleaning thinner tank through the corresponding cleaning branch, the cleaning fluid supply pipeline and the cleaning thinner tank.

10. A color-coated steel sheet production line, characterized in that, Includes the paint delivery and cleaning system as described in any one of claims 1-9.

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