A supercritical carbon dioxide automatic spraying system

Abstract

The application discloses a supercritical carbon dioxide automatic spraying system, which comprises a coating mixing unit, a spraying operation unit and a controller. The coating mixing unit pressurizes and heats carbon dioxide to a supercritical state through a multi-stage mixing container, and mixes and dissolves with a plurality of coating components to form a dissolved coating. The spraying operation unit adjusts the spraying path and angle according to the shape and size of the area to be sprayed through a robot sliding table and a multi-degree-of-freedom operation mechanical arm, and realizes accurate and uniform spraying. The controller is communicatively connected with various sensors, flow meters, valves, electric heating wires and other equipment, and monitors and adjusts the temperature, pressure, flow and ratio of carbon dioxide and coating in real time, so that the carbon dioxide and the coating are mixed and sprayed in a supercritical state, the carbon dioxide is prevented from being gasified or condensed, and the spraying effect is ensured. The system can stably form the dissolved coating and improve the spraying quality, and has the advantages of flexible operation and wide spraying range.

Description

Technical Field

[0001] This invention belongs to the field of spraying and relates to a spraying system, particularly a supercritical carbon dioxide automatic spraying system, which can pressurize and heat carbon dioxide to a supercritical state and mix it with several coating components, enabling flexible operation of the spraying work and improving spraying efficiency and quality. Background Technology

[0002] Paint coatings serve multiple functions, including protection, decoration, and labeling, and are widely used in numerous fields such as aircraft, automobiles, ships, machinery, and construction. However, traditional spraying methods, whether air spraying, high-pressure airless spraying, electrostatic spraying, or heated spraying, all require the addition of organic solvents to dilute the paint. These organic solvents consist of various slowly volatile organic compounds (VOCs), such as hydrocarbons (benzene, toluene, xylene, gasoline, etc.), alcohols, and ethers. These VOCs slow down the drying process and are often toxic and carcinogenic, affecting the health of workers. To reduce VOC emissions and hazards, traditional spraying methods require various measures, such as using low-VOC paints, installing exhaust systems and filtration devices, and requiring workers to wear protective clothing and masks. These measures not only increase the cost and complexity of spraying but also fail to completely eliminate the impact of VOCs, and are inconvenient and inefficient.

[0003] To address the aforementioned drawbacks, a new spraying process using supercritical carbon dioxide (SC-CO2) to replace organic solvents has been proposed. Supercritical carbon dioxide refers to the fluid state in which carbon dioxide transforms from a gaseous or liquid state under certain temperature and pressure conditions, exhibiting unique physical properties such as high density, low viscosity, low surface tension, and high diffusion coefficient. Supercritical carbon dioxide has the following advantages: (1) It is non-toxic, non-flammable, recyclable, and does not produce VOC emissions, making it an environmentally friendly solvent; (2) It has good solubility and selectivity, can be mixed and miscible with various coating components, and its solubility and viscosity can be changed by adjusting temperature and pressure; (3) It has the benefit of synergistic carbon emission reduction, and can utilize carbon dioxide from industrial waste gas as a raw material to reduce greenhouse gas emissions.

[0004] The new spraying process using supercritical carbon dioxide to replace organic solvents mainly includes the following steps: (1) pressurizing and heating carbon dioxide to a supercritical state; (2) mixing and dissolving supercritical carbon dioxide with paint components to form a dissolved paint; (3) conveying the dissolved paint to the spray gun through a high-pressure hose; (4) spraying the area to be sprayed with the spray gun; (5) after the sprayed dissolved paint comes into contact with ambient air, the carbon dioxide evaporates rapidly, forming a uniform and dense coating. This process can achieve efficient, low-pollution, and low-cost spraying, improving spraying efficiency and quality, and ensuring the safety and health of spraying personnel.

[0005] However, the new spraying process using supercritical carbon dioxide to replace organic solvents still has some problems and shortcomings, mainly in the following aspects: (1) The equipment is complex, requiring the use of high-pressure pumps, heaters, mixers, buffers and other equipment, which occupy a large space and have high maintenance costs; (2) The process flow is long, requiring multiple steps to complete the spraying, which is time-consuming and inefficient; (3) It requires full human participation, making it impossible to achieve automated and intelligent spraying, resulting in inconvenient operation and low precision.

[0006] In summary, while the existing new spraying process using supercritical carbon dioxide to replace organic solvents has certain advantages, it still has some problems and shortcomings that urgently need to be improved and perfected. Summary of the Invention

[0007] (I) Purpose of the Invention

[0008] To address the aforementioned deficiencies and shortcomings of existing technologies, this invention proposes a supercritical carbon dioxide automatic spraying system. By incorporating a multi-stage mixing container with heating function and a paint buffer container within the paint mixing unit, it achieves efficient mixing of carbon dioxide and paint, and flexible operation of the spraying process, thereby improving spraying efficiency and quality. This system can pressurize and heat carbon dioxide to a supercritical state, mixing it with several paint components to form a dissolved paint. Furthermore, the system can adjust the proportions, flow rates, temperatures, and pressures of the paint components based on real-time monitoring data, maintaining the dissolved paint in a stable state within the paint buffer container and preventing paint stratification or sedimentation. In addition, by incorporating a multi-degree-of-freedom robotic arm and spray gun within the spraying unit, precise and uniform spraying of parts with different locations and structures is achieved. The use of a movable work platform and robotic slide further enhances spraying efficiency and flexibility by enabling spraying of parts with different locations and structures. Finally, the system can adjust the spraying path and angle according to the shape and size of the area to be sprayed, achieving precise and uniform spraying. The system can also control the dissolved coating to remain in a supercritical state during transport, preventing the vaporization or condensation of carbon dioxide and ensuring the coating effect.

[0009] (II) Technical Solution

[0010] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0011] A supercritical carbon dioxide automatic spraying system, comprising at least a paint mixing unit, a spraying operation unit, and a controller, characterized in that,

[0012] The paint mixing unit includes at least a movable working platform and at least one carbon dioxide gas cylinder, several paint component chambers, and a paint mixing device fixedly mounted on the movable working platform. The paint mixing device includes at least a carbon dioxide buffer container at its upper part, a multi-stage mixing container in its middle part, and a paint buffer container at its lower part. The outer wall of the multi-stage mixing container is provided with an electric heating wire that is communicatively connected to and controlled by the controller, thereby enabling the multi-stage mixing container to have a heating function.

[0013] The carbon dioxide buffer container has at least one carbon dioxide inlet at the top, at least one mixing outlet at the bottom, and several inlets on the side wall near the bottom. The multi-stage mixing container has at least one inlet at the top and at least one outlet at the bottom. The paint buffer container has at least one inlet at the top and at least one outlet on the side wall near the bottom. Furthermore, the inlet at the top of the multi-stage mixing container is connected to the mixing outlet at the bottom of the carbon dioxide buffer container, and the outlet at the bottom of the multi-stage mixing container is connected to the inlet at the top of the paint buffer container.

[0014] The outlet of the carbon dioxide tank is connected to the inlet at the top of the carbon dioxide buffer container via a gas transport pipeline. The outlet of each coating component chamber is connected to the corresponding inlet on the carbon dioxide buffer container via a material transport pipeline. At least one booster pump is provided on the gas transport pipeline, and at least one coating pump is provided on the material transport pipeline. Both the booster pump and the coating pump are communicatively connected to the controller and are controlled by it.

[0015] The spraying unit includes at least a robot slide rail, a robot slide table, and a multi-degree-of-freedom robotic arm. The robot slide table is slidably mounted on the robot slide rail. The bottom of the multi-degree-of-freedom robotic arm is fixedly mounted on the robot slide table. The end of the multi-degree-of-freedom robotic arm is equipped with a spray gun. The spray gun is connected to the outlet of the paint buffer container through a high-pressure hose. The outer wall of the high-pressure hose is provided with an electric heating wire. The robot slide table, the multi-degree-of-freedom robotic arm, the spray gun, and the electric heating wire on the outer wall of the high-pressure hose are all communicatively connected to and controlled by the controller.

[0016] Preferably, in the coating mixing unit, at least one pneumatic valve I is provided on the gas transport pipeline between the carbon dioxide tank and the booster pump, which is communicatively connected to and controlled by the controller; at least one carbon dioxide flow meter is provided on the gas transport pipeline between the booster pump and the carbon dioxide buffer container; at least one carbon dioxide buffer temperature sensor and one carbon dioxide buffer pressure sensor are provided on the carbon dioxide buffer container, which extends into its internal space; and at least one coating buffer temperature sensor and one coating buffer pressure sensor are provided on the coating buffer container, which extends into its internal space. Furthermore, the carbon dioxide flow meter, carbon dioxide buffer temperature sensor, carbon dioxide buffer pressure sensor, coating buffer temperature sensor, and coating buffer pressure sensor are all communicatively connected to the controller and provide feedback on the collected information.

[0017] Furthermore, the booster pump is a pneumatic booster pump, which is also connected to an air compressor through a pipeline equipped with a pneumatic valve II and is driven by high-pressure air generated by the air compressor. In addition, the pneumatic valve II and the air compressor are both communicatively connected to the controller and are controlled by it.

[0018] Preferably, in the coating mixing unit, the plurality of coating component chambers include at least one coating first component chamber and one coating second component chamber. At least one coating pump I, one electric regulating valve I, and one coating first component flow meter are installed on the material transport pipeline between the coating first component chamber and the carbon dioxide buffer container. At least one coating pump II, one electric regulating valve II, and one coating second component flow meter are installed on the material transport pipeline between the coating second component chamber and the carbon dioxide buffer container. Furthermore, the coating pump I, coating pump II, electric regulating valve I, and electric regulating valve II are all communicatively connected to the controller and controlled by it. The coating first component flow meter and the coating second component flow meter are both communicatively connected to the controller and feed back collected information to it.

[0019] Preferably, in the coating mixing unit, the outer wall of the multi-stage mixing container is provided with an electric heating wire that is communicatively connected to and controlled by the controller, thereby enabling the multi-stage mixing container to have a heating function. The inner cavity of the multi-stage mixing container is cylindrical in shape and its central axis extends vertically. Multiple inclined downward partitions are arranged on the inner wall of the multi-stage mixing container in a staggered spatial arrangement from the top inlet to the bottom outlet. The space between two adjacent partitions forms a fluid channel for the mixing and mutual solubility of carbon dioxide and different coating components. The fluid channel between adjacent partitions is arranged from the top inlet to the bottom outlet in a manner that gradually increases in the vertical direction.

[0020] Furthermore, the electric heating wires are arranged in a partitioned manner on the outer wall of the multi-stage mixing container to achieve partitioned heating of the fluid channels between different partitions. The controller is equipped with a temperature control module that is communicatively connected to the electric heating wires. The voltage and current of the electric heating wires are dynamically adjusted through the temperature control module, so that the temperature in the inner cavity of the multi-stage mixing container gradually increases from the feed inlet at the top to the discharge outlet at the bottom.

[0021] Furthermore, the temperature within the multi-stage mixing container is maintained between 35°C and 55°C to ensure that carbon dioxide stably reaches a supercritical state, while simultaneously ensuring that the coating components reach their optimal mixing temperature. The supercritical temperature and pressure of carbon dioxide are 31.26°C and 72.9 atm, respectively. Setting the temperature above 35°C ensures that carbon dioxide stably reaches a supercritical state. In addition, unlike the optimal mixing temperature of many coating components, which works best between 50°C and 60°C, setting an upper limit of 55°C covers the optimal mixing temperature requirements for most coating components.

[0022] Furthermore, the paint buffer container is equipped with a safety valve. When the internal pressure of the paint buffer container exceeds a set safety value, the safety valve automatically opens to release some of the pressure, thereby preventing damage to the paint buffer container.

[0023] In the multi-stage mixing container of this invention, by flexibly adjusting the temperature within the container's interior and gradually increasing it, two advantages are achieved. First, carbon dioxide and coatings can reach optimal solubility and viscosity in a supercritical state, thereby improving the coating's fluidity and stability and preventing phenomena such as layering, sedimentation, and crystallization during spraying, which would affect the spraying effect and quality. Second, by creating a temperature gradient in the dissolved coating formed by carbon dioxide and coatings in a supercritical state, the thermal and kinetic energy of the dissolved coating is increased, enhancing the spraying speed and distance, thus increasing the spraying range and efficiency. Furthermore, different coating components possess different physicochemical properties, and their optimal mixing temperatures vary. By controlling the heating wires in zones, each coating component can reach its optimal mixing temperature, optimizing the mixing effect. Simultaneously, the viscosity of the coating components decreases with increasing temperature. Gradually increasing the temperature within the multi-stage mixing container effectively reduces the viscosity of the coating components, facilitating mixing and spraying of the coating components with carbon dioxide.

[0024] The multi-stage mixing container in this invention is the core component of the coating mixing device. It is responsible for pressurizing and heating carbon dioxide to a supercritical state, and mixing it with several coating components to form a dissolved coating. The outer wall of the multi-stage mixing container is equipped with an electric heating wire, which can adjust the temperature according to the controller's instructions, ensuring that the carbon dioxide reaches a supercritical state (above 31.26℃ and 72.9 atm) within the container. This structural design facilitates the thorough mixing and dissolution of carbon dioxide with different coating components. Furthermore, the arrangement of the baffles in the multi-stage mixing container also provides flow resistance control, adjusting the size and shape of the fluid channels according to the physical properties and flow characteristics of the carbon dioxide and coating components. This ensures suitable pressure and velocity within the fluid channels, preventing excessively large or small pressure or velocity differences that could lead to carbon dioxide vaporization or condensation, thus affecting the coating effect.

[0025] Preferably, in the spraying operation unit, the end of the multi-degree-of-freedom robotic arm is provided with an end gripper, and the spray gun is gripped by the end gripper.

[0026] Preferably, in the spraying unit, the spray gun is provided with at least one spray gun temperature sensor and one spray gun pressure sensor that extend into its container space. The spray gun temperature sensor and the spray gun pressure sensor are both communicatively connected to the controller and feed back collected information to it.

[0027] The supercritical carbon dioxide automatic spraying system of this invention uses a controller as its core component. This controller receives spraying commands and controls various devices and parameters in the paint mixing and spraying units, achieving efficient mixing of carbon dioxide and paint, and automating and intelligently managing the spraying process. The controller communicates with various sensors, flow meters, booster pumps, paint pumps, electric regulating valves, electric heating wires, robotic slides, multi-degree-of-freedom robotic arms, and spray guns, enabling real-time monitoring and adjustment of the temperature, pressure, flow rate, and ratio of carbon dioxide and paint. This ensures that carbon dioxide and paint are mixed and sprayed under supercritical conditions, preventing carbon dioxide vaporization or condensation and guaranteeing optimal spraying results. Furthermore, by controlling the movement and rotation of the robotic slide and multi-degree-of-freedom robotic arm, the controller adjusts the spraying path and angle according to the shape and size of the area to be sprayed, achieving precise and uniform spraying. By controlling the movement of the movable work platform, it enables spraying of parts in different locations and with different structures, improving spraying efficiency and flexibility.

[0028] (III) Technical Effects

[0029] Compared with the prior art, the supercritical carbon dioxide automatic spraying system of the present invention has the following beneficial and significant technical effects:

[0030] (1) The supercritical carbon dioxide automatic spraying system of the present invention, by installing a paint pump, an electric regulating valve, and a paint component flow meter on the material conveying pipeline between the paint component chamber and the carbon dioxide buffer container, can regulate the pressure and flow rate of the paint component, and adjust the speed of the paint pump according to real-time monitoring data, so that the paint component and supercritical carbon dioxide are mixed in a suitable ratio. The present invention also installs a paint buffer zone temperature sensor and a paint buffer zone pressure sensor on the paint buffer container, which can monitor the temperature and pressure of the paint buffer zone, so that the dissolved paint is maintained in a stable state in the paint buffer container, avoiding the problem of paint stratification or sedimentation.

[0031] (2) The supercritical carbon dioxide automatic spraying system of the present invention utilizes a multi-stage mixing container with heating function to pressurize and heat carbon dioxide to a supercritical state, and mix and dissolve it with several coating components to form a dissolved coating. By adopting a multi-stage mixing method, it is beneficial to fully mix and dissolve carbon dioxide with different coating components, avoiding the need for multiple reaction vessels or stirring tanks for premixing, dilution, homogenization and other steps in traditional spraying, simplifying the process and reducing costs.

[0032] (3) The supercritical carbon dioxide automatic spraying system of the present invention uses a multi-degree-of-freedom robotic arm and a spray gun to adjust the spraying path and angle according to the shape and size of the area to be sprayed, so as to achieve precise and uniform spraying. Furthermore, by using a movable work platform and a robot slide, it can achieve spraying of parts with different positions and structures. These functions enable the present invention to adapt to different spraying needs and occasions, such as the spraying of mechanical equipment such as airplanes, ships, and automobiles, as well as buildings, thereby improving spraying efficiency and flexibility.

[0033] (4) The supercritical carbon dioxide automatic spraying system of the present invention uses multiple temperature and pressure sensors to adjust the temperature and pressure of each link of the system according to the detected actual temperature and pressure, thereby ensuring that carbon dioxide and coating are mixed and sprayed in a supercritical state, avoiding the vaporization or condensation of carbon dioxide, and ensuring the spraying effect. For example, the high-pressure hose with heating function and the spray gun temperature sensor set in the spraying operation unit can control the dissolved coating to be maintained in a supercritical state during the transportation process, preventing the vaporization or condensation of carbon dioxide and ensuring the spraying effect. Attached Figure Description

[0034] Figure 1 The diagram shown is a schematic of the supercritical carbon dioxide automatic spraying system of the present invention.

[0035] Figure 2 The diagram shown is a schematic representation of the coating mixing unit in this invention.

[0036] Figure 3The diagram shown is a structural schematic of the multi-stage mixing container in this invention;

[0037] Figure 4 The diagram shown is a structural schematic of the spraying unit in this invention;

[0038] Figure 5 The diagram shown is a schematic of the control circuit of the supercritical carbon dioxide automatic spraying system of the present invention.

[0039] Explanation of reference numerals in the attached figures:

[0040] 1. Mobile operating platform; 2. Gas transport pipeline; 3. Booster pump; 4. Carbon dioxide flow meter; 5. Paint buffer temperature sensor; 6. Multi-stage mixing container; 61. Electric heating wire; 62. Baffle plate; 7. Paint buffer container; 8. Paint buffer pressure sensor; 9. Hose connector; 10. First component chamber of paint; 11. Second component chamber of paint; 12. High-pressure hose with heating function; 13. Robotic arm; 14. Control circuit; 15. Robot slide; 16. Air compressor; 17. Carbon dioxide gas tank; 18. Pneumatic valve I; 19. Pneumatic valve II; 20. Carbon dioxide buffer temperature sensor; 21. Carbon dioxide buffer pressure sensor; 22. Carbon dioxide buffer container; 23. Electric regulating valve I; 24. Electric regulating valve II; 25. First component flow meter of paint; 26. Second component flow meter of paint; 27. Spray gun temperature sensor; 28. Controller; 29. ​​Spray gun pressure sensor; 30. Paint pump I; 31. Paint pump II; 32. Spray gun; 33. End gripper; 34. Robot slide rail. Detailed Implementation

[0041] To better understand the present invention, the following embodiments further illustrate its content. Throughout the accompanying drawings, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions. The described embodiments are some, but not all, of the embodiments of the present invention. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention. 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. The structure and technical solutions of the present invention will be further described in detail below with reference to the accompanying drawings, providing one embodiment of the present invention.

[0042] like Figure 1 , 5As shown, the supercritical carbon dioxide automatic spraying system of the present invention comprises a mobile working platform 1, a gas transport pipeline 2, a booster pump 3, a carbon dioxide flow meter 4, a paint buffer temperature sensor 5, a multi-stage mixing container 6, a paint buffer container 7, a paint buffer pressure sensor 8, a hose connector 9, a first component paint chamber 10, a second component paint chamber 11, a high-pressure hose with heating function 12, a robotic arm 13, a control circuit 14, a robot slide 15, an air compressor 16, a carbon dioxide gas tank 17, a pneumatic valve I 18, a pneumatic valve II 19, a carbon dioxide buffer temperature sensor 20, a carbon dioxide buffer pressure sensor 21, a carbon dioxide buffer container 22, an electric regulating valve I 23, an electric regulating valve II 24, a first component paint flow meter 25, a second component paint flow meter 26, a spray gun temperature sensor 27, a controller 28, a spray gun pressure sensor 29, a paint pump I 30, a paint pump II 31, a spray gun 32, an end effector 33, and a robot slide rail 34, etc.

[0043] More specifically, the aforementioned components in the supercritical carbon dioxide automatic spraying system of the present invention can be collectively divided into a paint mixing unit, a spraying operation unit, and a controller 28. Wherein:

[0044] like Figure 2 , 5As shown, the paint mixing unit of the present invention includes at least a movable working platform 1, at least one carbon dioxide tank 17 fixedly mounted on the movable working platform 1, several paint component chambers 10 and 11, and a paint mixing device. The paint mixing device includes at least a carbon dioxide buffer container 22 located at its upper part, a multi-stage mixing container 6 with heating function located in its middle part, and a paint buffer container 7 located at its lower part. The outer wall of the multi-stage mixing container 6 is provided with an electric heating wire that is communicatively connected to and controlled by a controller 28, thereby enabling the multi-stage mixing container 6 to have a heating function. The carbon dioxide buffer container 22 has at least one carbon dioxide inlet at its top, at least one mixing outlet at its bottom, and several feed inlets on its side wall near the bottom. The multi-stage mixing container 6 has at least one feed inlet at its top and several feed inlets at its bottom. At least one discharge port is provided. The top of the paint buffer container 7 is provided with at least one inlet and the side wall near the bottom is provided with at least one discharge port. The inlet of the top of the multi-stage mixing container 6 is connected to the mixing outlet of the bottom of the carbon dioxide buffer container 22, and the outlet of the bottom of the multi-stage mixing container 6 is connected to the inlet of the top of the paint buffer container 7. The outlet of the carbon dioxide gas tank 17 is connected to the gas inlet of the top of the carbon dioxide buffer container 22 through the gas transport pipeline 2. The discharge ports of each paint component chamber 10 and 11 are connected to the corresponding inlet of the carbon dioxide buffer container 22 through the material transport pipeline. At least one booster pump 3 is provided on the gas transport pipeline 2, and at least one paint pump 29 and 30 are provided on the material transport pipeline. The booster pump 3, paint pump 29 and 30 are all communicatively connected to the controller and are controlled by it.

[0045] In a preferred embodiment of the present invention, at least one pneumatic valve I 18 is provided on the gas transport pipeline 2 between the carbon dioxide tank 17 and the booster pump 3, and at least one carbon dioxide flow meter 4 is provided on the gas transport pipeline 2 between the booster pump 3 and the carbon dioxide buffer container 22. The booster pump 3 is a pneumatic booster pump, and the booster pump 3 is also connected to an air compressor 16 through a pipeline provided with a pneumatic valve II 19 and is driven by the high-pressure air generated by the air compressor 16. At least one carbon dioxide buffer temperature sensor 20 and one carbon dioxide buffer pressure sensor 21 extending into its internal space are provided on the carbon dioxide buffer container 22, and at least one paint buffer temperature sensor 5 and one paint buffer pressure sensor 8 extending into its internal space are provided on the paint buffer container 7. The coating component chambers 10 and 11 include at least one coating first component chamber 10 and one coating second component chamber 11. At least one coating pump I 29, one electric regulating valve I 23, and one coating first component flow meter 25 are provided on the material transport pipeline between the coating first component chamber 10 and the carbon dioxide buffer container 22. At least one coating pump II 30, one electric regulating valve II 24, and one coating second component flow meter 26 are provided on the material transport pipeline between the coating second component chamber 11 and the carbon dioxide buffer container 22.

[0046] like Figure 3 As shown, the multi-stage mixing container 6 in the coating mixing unit of the present invention has an electric heating wire 61 on its outer wall that is communicatively connected to and controlled by the controller 28, thereby enabling the multi-stage mixing container 6 to have a heating function. The inner cavity of the multi-stage mixing container 6 is cylindrical in shape and its central axis extends vertically. Multiple inclined downward partitions 62 are arranged on the inner wall of the multi-stage mixing container 6 in a staggered manner from the top inlet to the bottom outlet. The space between two adjacent partitions 62 forms a fluid channel for the mixing and mutual solubility of carbon dioxide and different coating components. The fluid channel between adjacent partitions 62 is arranged from the top inlet to the bottom outlet in a manner that gradually increases in the vertical direction.

[0047] Furthermore, as a preferred embodiment, the electric heating wires 61 are arranged in a partitioned manner on the outer wall of the multi-stage mixing container 6 to achieve partitioned heating of the fluid channels between different partitions 62. The controller 28 is equipped with a temperature control module that communicates with the electric heating wires, and dynamically adjusts the voltage and current of the electric heating wires 61 through the temperature control module, so that the temperature inside the multi-stage mixing container gradually increases from the inlet at the top to the outlet at the bottom. In addition, the overall temperature inside the multi-stage mixing container is maintained between 35℃ and 55℃ to ensure that carbon dioxide stably reaches a supercritical state, while also ensuring that the coating components reach their optimal mixing temperature. The supercritical temperature and pressure of carbon dioxide are 31.26℃ and 72.9 atm, respectively. Setting the temperature above 35℃ ensures that carbon dioxide stably reaches a supercritical state. Furthermore, unlike the optimal mixing temperature of some coating components, many work best at 50-60℃. Setting an upper limit of 55℃ covers the optimal mixing temperature requirements of most coating components. Meanwhile, a safety valve is installed on the paint buffer container 6. When the internal pressure of the paint buffer container exceeds the set safety value, the safety valve will automatically open to release some of the pressure and prevent damage to the paint buffer container.

[0048] In the multi-stage mixing container of this invention, by flexibly adjusting the temperature within the container's interior and gradually increasing it, two advantages are achieved. First, carbon dioxide and coatings can reach optimal solubility and viscosity in a supercritical state, thereby improving the coating's fluidity and stability and preventing phenomena such as layering, sedimentation, and crystallization during spraying, which would affect the spraying effect and quality. Second, by creating a temperature gradient in the dissolved coating formed by carbon dioxide and coatings in a supercritical state, the thermal and kinetic energy of the dissolved coating is increased, enhancing the spraying speed and distance, thus increasing the spraying range and efficiency. Furthermore, different coating components possess different physicochemical properties, and their optimal mixing temperatures vary. By controlling the heating wires in zones, each coating component can reach its optimal mixing temperature, optimizing the mixing effect. Simultaneously, the viscosity of the coating components decreases with increasing temperature. Gradually increasing the temperature within the multi-stage mixing container effectively reduces the viscosity of the coating components, facilitating mixing and spraying of the coating components with carbon dioxide.

[0049] The multi-stage mixing container 6 in this invention is the core component of the coating mixing device. It is responsible for pressurizing and heating carbon dioxide to a supercritical state, and mixing and dissolving it with several coating components to form a dissolved coating. The outer wall of the multi-stage mixing container 6 is equipped with an electric heating wire 61, which can adjust the temperature according to the instructions of the controller 28, ensuring that the carbon dioxide reaches a supercritical state (above 31.26℃ and 72.9 atm) within the multi-stage mixing container 6. This structural design facilitates the thorough mixing and dissolution of carbon dioxide with different coating components. Furthermore, the arrangement of the baffles 62 in the multi-stage mixing container 6 also has a flow resistance control function, adjusting the size and shape of the fluid channels according to the physical properties and flow characteristics of the carbon dioxide and coating components. This ensures suitable pressure and velocity within the fluid channels, preventing excessively large or small pressure or velocity differences that could lead to carbon dioxide vaporization or condensation, affecting the spraying effect.

[0050] like Figure 4 , 5As shown, the spraying unit of the present invention includes at least a robot slide rail 33, a robot slide table 15, and a multi-degree-of-freedom robotic arm 13. The robot slide table 15 is slidably mounted on the robot slide rail 33. The bottom of the multi-degree-of-freedom robotic arm 13 is fixedly mounted on the robot slide table 15. A spray gun 31 is provided at the end of the multi-degree-of-freedom robotic arm 13. The spray gun 31 is connected to the outlet of the paint buffer container 7 via a high-pressure hose 12 with heating function. Preferably, an end effector 32 is provided at the end of the multi-degree-of-freedom robotic arm 13, and the spray gun 31 is held by the end effector 32. The spray gun 31 is provided with at least a spray gun temperature sensor 27 and a spray gun pressure sensor 28 extending into its container space. Furthermore, the robot slide table 15, the multi-degree-of-freedom robotic arm 13, the spray gun 31, and the electric heating wire on the outer wall of the high-pressure hose are all communicatively connected to the controller.

[0051] like Figure 5 As shown, in the supercritical carbon dioxide automatic spraying system of the present invention, the controller 28 is the core component of the entire system. It is responsible for receiving spraying commands and controlling various equipment and parameters of the paint mixing unit and the spraying operation unit, achieving efficient mixing of carbon dioxide and paint and automating and intelligentizing the spraying process. The controller 28 communicates with various sensors, flow meters, booster pumps, paint pumps, electric regulating valves, electric heating wires, robot slides, multi-degree-of-freedom robotic arms, and spray guns, enabling real-time monitoring and adjustment of the temperature, pressure, flow rate, and ratio of carbon dioxide and paint. This ensures that carbon dioxide and paint are mixed and sprayed in a supercritical state, preventing the vaporization or condensation of carbon dioxide and guaranteeing the spraying effect. By controlling the movement and rotation of the robot slide and the multi-degree-of-freedom robotic arm, the controller 28 can adjust the spraying path and angle according to the shape and size of the area to be sprayed, achieving precise and uniform spraying. Furthermore, by controlling the movement of the movable work platform, it can spray parts in different positions and with different structures, improving spraying efficiency and flexibility.

[0052] The working principle of the supercritical carbon dioxide automatic spraying system of the present invention is as follows:

[0053] After starting the spraying operation, the air compressor 16 is turned on first, followed by the pneumatic valve I 18 and the booster pump 3. Gaseous carbon dioxide is extracted from the carbon dioxide tank 17 and pressurized and sent to the carbon dioxide buffer container 22. The carbon dioxide buffer temperature sensor 20, the carbon dioxide buffer pressure sensor 21 and the carbon dioxide flow meter 4 monitor the temperature, pressure and flow of carbon dioxide in real time. The carbon dioxide is heated in the multi-stage mixing container 6 with heating function and reaches a supercritical state of 31.26℃ and above 72.9 atm.

[0054] Subsequently, electric regulating valves I23 and II24 are opened, activating paint pumps I29 and II30 to extract the first and second components of paint from the first component chamber 10 and the second component chamber 11, respectively. The first component flow meter 25 and the second component flow meter 26 monitor the flow rates of the first and second components of paint, respectively. By adjusting the speed of paint pumps I29 and II30 in real time, the amounts of the first and second components of paint are appropriately proportioned. The first and second components of paint are mixed and miscible with supercritical carbon dioxide in the multi-stage mixing zone 6 with heating function, and are cached in the paint buffer zone 7 to reach a stable state.

[0055] The paint reaches the spray gun 31 via hose connector 9 and heated high-pressure hose 12. Spray gun temperature sensor 27 and spray gun pressure sensor 28 monitor the temperature and pressure inside the spray gun 31 in real time. By controlling the temperature of the heated high-pressure hose 12, the carbon dioxide is maintained in a supercritical state. The spray gun 31 is held by the end effector 32 and completes the spraying action according to the working path of the multi-degree-of-freedom robotic arm 13. The spraying system is placed on a movable work platform 1. The multi-degree-of-freedom robotic arm 13 is placed on the robot rail 33 via robot slide 15 and can drive the movable work platform 1 and robot slide 15 according to the area to be sprayed, enabling spraying of parts with different positions and structures.

[0056] This embodiment only describes two-component coatings. In practice, the number of components such as component chambers, coating pumps, coating flow meters, and electric regulating valves can be appropriately added or reduced according to the number of coating components, so that the number of coating components is equal to the number of components such as component chambers, coating pumps, coating flow meters, and electric regulating valves.

[0057] The supercritical carbon dioxide automatic spraying system of this invention, by installing a paint pump, an electric regulating valve, and a paint component flow meter in the material delivery pipeline between the paint component chamber and the carbon dioxide buffer container, can regulate the pressure and flow rate of the paint component, and adjust the speed of the paint pump according to real-time monitoring data, so that the paint component and supercritical carbon dioxide are mixed in a suitable ratio. This invention also installs a paint buffer zone temperature sensor and a paint buffer zone pressure sensor on the paint buffer container, which can monitor the temperature and pressure of the paint buffer zone, keeping the dissolved paint in a stable state in the paint buffer container and avoiding problems such as paint stratification or sedimentation.

[0058] The supercritical carbon dioxide automatic spraying system of the present invention utilizes a multi-stage mixing container with heating function to pressurize and heat carbon dioxide to a supercritical state, and mix it with several coating components to form a dissolved coating. By adopting a multi-stage mixing method, it is beneficial to fully mix and dissolve carbon dioxide with different coating components, avoiding the need for multiple reaction vessels or stirring tanks for premixing, dilution, homogenization and other steps required in traditional spraying, thus simplifying the process and reducing costs.

[0059] The supercritical carbon dioxide automatic spraying system of the present invention employs a multi-degree-of-freedom robotic arm and spray gun in its spraying unit. This allows for precise and uniform spraying by adjusting the spraying path and angle according to the shape and size of the area to be sprayed. Furthermore, the use of a movable work platform and robotic slide enables spraying of parts in different locations and with different structures. These functions allow the present invention to adapt to various spraying needs and occasions, such as spraying of aircraft, ships, automobiles, and other mechanical equipment, as well as buildings, thus improving spraying efficiency and flexibility.

[0060] The supercritical carbon dioxide automatic spraying system of the present invention uses multiple temperature and pressure sensors to adjust the temperature and pressure of each component of the system according to the detected actual temperature and pressure. This ensures that carbon dioxide and paint are mixed and sprayed in a supercritical state, avoiding the vaporization or condensation of carbon dioxide and ensuring the spraying effect. For example, the high-pressure hose with heating function and the temperature sensor of the spray gun in the spraying unit can control the dissolved paint to remain in a supercritical state during the transportation process, preventing the vaporization or condensation of carbon dioxide and ensuring the spraying effect.

[0061] The objectives of this invention have been fully and effectively achieved through the above embodiments. Those skilled in the art will understand that this invention includes, but is not limited to, the contents described in the accompanying drawings and the specific embodiments described above. Although the invention has been described with reference to what is currently considered the most practical and preferred embodiments, it should be understood that the invention is not limited to the disclosed embodiments, and any modifications that do not depart from the functional and structural principles of the invention will be included within the scope of the claims.

Claims

1. A supercritical carbon dioxide automatic spraying system comprising at least a coating mixing unit, a spraying operation unit and a controller, wherein the coating mixing unit comprises at least a movable operation platform, at least one carbon dioxide gas tank, a plurality of coating component cavities and a coating mixing device fixedly arranged on the movable operation platform, the coating mixing device comprises at least a carbon dioxide buffer container at the upper portion, a multi-stage mixing container at the middle portion and a coating buffer container at the lower portion, the outer wall of the multi-stage mixing container is provided with electric heating wires in communication connection with the controller and controlled thereby, so that the multi-stage mixing container has heating function, wherein the carbon dioxide buffer container is provided at least with a carbon dioxide inlet at the top and a mixing outlet at the bottom, and a plurality of material inlets on the side wall near the bottom, the multi-stage mixing container is provided at least with a material inlet at the top and an outlet at the bottom, and the coating buffer container is provided at least with a material inlet at the top and an outlet at the bottom, and wherein the material inlet at the top of the multi-stage mixing container is in communication with the mixing outlet at the bottom of the carbon dioxide buffer container, and the outlet at the bottom of the multi-stage mixing container is in communication with the material inlet at the top of the coating buffer container, the outlet of the carbon dioxide gas tank is in communication with the carbon dioxide inlet at the top of the carbon dioxide buffer container through a gas conveying pipeline, the outlet of each coating component cavity is in communication with the corresponding material inlet of the carbon dioxide buffer container through a material conveying pipeline, at least one booster pump is arranged on the gas conveying pipeline, and at least one coating pump is arranged on the material conveying pipeline, and wherein the booster pump and the coating pump are in communication connection with the controller and controlled thereby; the spraying operation unit comprises at least a robot slide rail, a robot slide table and a multi-degree-of-freedom operation mechanical arm, the robot slide table is arranged in a slidable manner on the robot slide rail, the bottom of the multi-degree-of-freedom operation mechanical arm is fixedly arranged on the robot slide table, the end of the multi-degree-of-freedom operation mechanical arm is provided with an operation spray gun, the operation spray gun is in communication with the outlet of the coating buffer container through a high-pressure hose, the outer wall of the high-pressure hose is provided with electric heating wires, and wherein the robot slide table, the multi-degree-of-freedom operation mechanical arm, the operation spray gun and the electric heating wires on the outer wall of the high-pressure hose are in communication connection with the controller and controlled thereby; in the coating mixing unit, the inner cavity of the multi-stage mixing container is in a cylindrical shape and the central axis thereof extends in a vertical direction, and a plurality of inclined downward partitions are arranged on the inner cavity wall of the multi-stage mixing container in a staggered distribution manner from the material inlet at the top to the outlet at the bottom, the space between adjacent two partitions forms a fluid passage for mixing and mutual solubility of carbon dioxide and different coating components, and the fluid passages between adjacent partitions are arranged from the material inlet at the top to the outlet at the bottom in a gradually increasing manner in the vertical direction. ​ ​ ​ 2. The supercritical carbon dioxide automatic spray system of claim 1, wherein, The paint mixing unit is characterized in that: at least one air valve I is arranged on the gas conveying pipeline between the carbon dioxide gas tank and the booster pump and is in communication connection with the controller and receives control of the controller; at least one carbon dioxide flow meter is arranged on the gas conveying pipeline between the booster pump and the carbon dioxide buffer container; at least one carbon dioxide buffer zone temperature sensor and one carbon dioxide buffer zone pressure sensor are arranged on the carbon dioxide buffer container and extend into the internal space of the carbon dioxide buffer container; at least one paint buffer zone temperature sensor and one paint buffer zone pressure sensor are arranged on the paint buffer container and extend into the internal space of the paint buffer container; and the carbon dioxide flow meter, the carbon dioxide buffer zone temperature sensor, the carbon dioxide buffer zone pressure sensor, the paint buffer zone temperature sensor and the paint buffer zone pressure sensor are in communication connection with the controller and feed back collected information to the controller.

3. The supercritical carbon dioxide automatic spray system of claim 2, wherein, The booster pump is a pneumatic booster pump, and the booster pump is in communication connection with an air compressor through a pipeline provided with an air valve II and is driven by high-pressure air generated by the air compressor; and the air valve II and the air compressor are in communication connection with the controller and receive control of the controller.

4. The supercritical carbon dioxide automatic spray system of claim 1, wherein, The paint mixing unit is characterized in that: the plurality of paint component cavities at least include a paint first component cavity and a paint second component cavity; at least one paint pump I, one electric regulating valve I and one paint first component flow meter are arranged on the material conveying pipeline between the paint first component cavity and the carbon dioxide buffer container; at least one paint pump II, one electric regulating valve II and one paint second component flow meter are arranged on the material conveying pipeline between the paint second component cavity and the carbon dioxide buffer container; and the paint pump I, the paint pump II, the electric regulating valve I and the electric regulating valve II are in communication connection with the controller and receive control of the controller, and the paint first component flow meter and the paint second component flow meter are in communication connection with the controller and feed back collected information to the controller.

5. The supercritical carbon dioxide automatic spray system of claim 1, wherein, The electric heating wires are arranged on the outer wall of the multi-stage mixing container in a partitioned manner to realize partitioned heating of fluid passages between different baffles, and a temperature control module in communication connection with the electric heating wires is arranged in the controller, and the voltage and current of the electric heating wires are dynamically adjusted through the temperature control module, so that the temperature in the inner cavity of the multi-stage mixing container gradually increases from the feed inlet at the top to the discharge outlet at the bottom.

6. The supercritical carbon dioxide automatic spray system of claim 5, wherein, The temperature in the inner cavity of the multi-stage mixing container is kept between 35°C and 55°C as a whole, so as to ensure that the carbon dioxide stably reaches a supercritical state and the paint components reach an optimal mixing temperature.

7. The supercritical carbon dioxide automatic spray system of claim 5, wherein, A safety valve is arranged on the paint buffer container, and when the internal pressure of the paint buffer container exceeds a set safety value, the safety valve is automatically opened to release part of the pressure, so as to avoid damage of the paint buffer container.

8. The supercritical carbon dioxide automatic spray system of claim 1, wherein, In the spraying operation unit, an end gripper is arranged at the end of the multi-degree-of-freedom operation mechanical arm and holds the operation spray gun through the end gripper.

9. The supercritical carbon dioxide automatic spray system of claim 1, wherein, The spraying operation unit is provided with at least a spraying gun temperature sensor and a spraying gun pressure sensor which extend into the container space of the spraying gun, and the spraying gun temperature sensor and the spraying gun pressure sensor are in communication connection with the controller and feed back collected information to the controller.

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