A gradient pressure control and spray head cooperative control method and system for clean and precise paint spraying

Abstract

The application relates to a gradient pressure control and spray head cooperative control method and system for clean and precise paint spraying. A workpiece paint spraying system comprises a first paint spraying room, a transition buffer zone and a second paint spraying room. Each paint spraying room is divided into a pressure control area and is equipped with a diagonal double spray head and a pressure sensor. The control method comprises the following steps: configuring a target pressure value of each area, calculating a deviation value of a pressure measurement value and the target value, generating a linkage adjustment instruction when the deviation exceeds a range, and sending the instruction to a supply and exhaust side actuator to make the deviation return and maintain the supply air volume greater than the exhaust air volume; calculating an initial deflection angle of the diagonal double spray head according to the workpiece size and a reference gun distance, collecting the distance from the spray head to the workpiece surface during spraying and calculating the height difference from the reference gun distance, sending a height adjustment instruction when the height difference exceeds a threshold, calculating an optimal deflection angle according to the adjusted gun distance and generating a cooperative adjustment instruction; after the primer is completed, the workpiece is dried in the transition buffer zone and then transferred to the second paint spraying room for topcoat or varnish spraying. The application can effectively improve the film quality consistency and the paint spraying yield.

Description

Technical Field

[0001] This application relates to the field of spray painting process control technology, and in particular to a gradient pressure control and spray head coordinated control method and system for clean and precision spray painting. Background Technology

[0002] With the increasing demands for surface coating quality in modern manufacturing, spray painting has become widely used for surface treatment of industrial products requiring high cleanliness, such as integrated circuit components, precision electronic components, automotive parts, and aerospace devices. During the spray painting process, the airflow organization and pressure distribution within the spray booth directly affect the directional flow and removal of paint mist. Clean air is introduced from the top of the spray booth to create a positive pressure environment, while air containing paint mist is discharged from the bottom to create a negative pressure environment. This pressure difference drives the airflow from top to bottom in a directional manner to prevent paint mist from diffusing backwards and contaminating the workpiece surface and the working environment.

[0003] However, in actual spraying processes, due to factors such as local airflow disturbances caused by the reciprocating motion of the nozzle, dynamic changes in air supply and exhaust volumes, and the opening and closing of the spray booth door, the pressure in different areas of the spray booth often deviates from the set value, making it difficult to maintain the stability of the pressure gradient. When the pressure gradient is disrupted, air containing paint mist may diffuse upstream or leak outside the spray booth, resulting in particulate matter adhering to the workpiece surface, uneven paint film thickness, and even defects such as orange peel and sagging, seriously affecting the protective performance and appearance quality of the coating. Furthermore, the distance between the nozzle and the workpiece surface during spraying, i.e., the gun distance, is a key parameter affecting the uniformity of the paint film and the spray coverage. For workpieces with raised or recessed surfaces, the actual distance between the nozzle and the workpiece surface during reciprocating motion will fluctuate with changes in the workpiece shape. Too close a gun distance leads to excessively thick local paint films or even sagging, while too far a gun distance leads to paint mist dispersion, insufficient coverage, and reduced paint film adhesion.

[0004] Currently, most existing painting systems struggle to adapt to real-time changes in workpiece surface morphology, especially when painting precision components such as integrated circuit parts. Even minute deviations in nozzle distance can lead to significant uneven paint film thickness, affecting the accuracy of subsequent circuit patterns and the reliability of components. Furthermore, when nozzle height adjustment alters the nozzle distance, if the nozzle deflection angle is not adjusted accordingly, the paint mist coverage width will mismatch with the workpiece width, further exacerbating the uneven coverage problem. In addition, if primer and topcoat spraying are performed continuously in the same spray booth, solvent vapors and suspended paint mist in the primer may interfere with the topcoat film quality. Insufficient primer leveling and drying time before topcoat spraying can lead to decreased interlayer adhesion. Existing dual-spray booth interval spraying processes still have shortcomings in the independent configuration of pressure control parameters and environmental management of transition buffer zones. Summary of the Invention

[0005] To address the aforementioned technical problems, this application provides a gradient pressure control and nozzle coordinated control method and system for clean precision spraying.

[0006] Firstly, this application provides a gradient pressure control and nozzle coordinated control method for clean precision spray painting, executed by the control unit of a workpiece spray painting system. The workpiece spray painting system includes a first spray booth, a transition buffer zone, and a second spray booth arranged sequentially along the production line. Each spray booth is divided into multiple pressure control zones from top to bottom and equipped with diagonally opposite dual nozzles and pressure sensors. The control method adopts the following technical solution: Configure the pressure target value for each pressure control zone, and associate and store the pressure target value with the corresponding pressure sensor; Collect pressure measurement values ​​from each pressure sensor, compare the pressure measurement values ​​with the corresponding pressure target values ​​to obtain pressure deviation values, and mark the corresponding pressure control area as an area to be adjusted when the pressure deviation value exceeds the allowable deviation range. Based on the area to be adjusted, a linkage adjustment command is generated and sent to the corresponding air supply and exhaust side actuators to keep the pressure deviation value within the allowable range and maintain the air supply volume greater than the exhaust volume. Obtain the geometric dimensions of the workpiece to be coated, calculate the initial deflection angle of the diagonal dual nozzles based on the geometric dimensions and the preset reference nozzle distance, and send the initial position control command for the nozzles; wherein, the preset reference nozzle distance is the target distance from the diagonal dual nozzles to the surface of the workpiece to be coated. The diagonal dual spray nozzles of the first spray booth are controlled to spray primer onto the workpiece to be sprayed. At the same time, the actual distance from the diagonal dual spray nozzles to the surface of the workpiece to be sprayed is collected and the height deviation from the preset reference gun distance is calculated. When the height deviation exceeds the preset deviation threshold, a spray nozzle height adjustment command is sent to the height adjustment mechanism to obtain the adjusted actual gun distance. The optimal deflection angle is calculated based on the adjusted actual gun distance. An angle coordination adjustment command is generated based on the difference between the optimal deflection angle and the initial deflection angle and sent to the nozzle angle adjustment mechanism. After the primer is applied, the control conveyor transfers the workpiece to be sprayed to the transition buffer for leveling and drying. After a preset time, it is transferred to the second spray booth, and the diagonal dual spray nozzles of the second spray booth are controlled to perform topcoat or protective clear coat spraying. During the primer, topcoat or protective clear coat spraying process, the above-mentioned pressure deviation calculation and linkage adjustment, as well as height deviation calculation and angle coordination adjustment steps are continuously executed.

[0007] By adopting the above technical solution, the paint booth is divided into multiple pressure control zones from top to bottom and configured with progressively decreasing pressure target values. Pressure sensors collect pressure measurements in each zone in real time and compare them with the target values. When the pressure deviation exceeds the allowable range, the actuators on the air supply and exhaust sides are adjusted to bring the pressure back to the target range. At the same time, the air supply volume is always greater than the exhaust volume to maintain a slight positive pressure in the paint booth. Thus, the upper clean environment protection and the lower paint mist directional removal are achieved simultaneously in the same paint booth, which solves the contradiction between the opposite pressure environment requirements of cleanliness and mist removal in traditional solutions. In terms of spraying accuracy, the initial deflection angle of the diagonal dual nozzles is calculated based on the workpiece geometry and the reference gun distance. During the spraying process, the actual distance from the nozzle to the workpiece surface is collected in real time and the height deviation is detected. When the deviation exceeds the threshold, the height is adjusted to obtain a new actual gun distance. Then, the optimal deflection angle is recalculated based on the new gun distance and the nozzle angle is adjusted synchronously to keep the paint mist coverage constant when the gun distance fluctuates, avoiding the coverage mismatch problem caused by independent adjustment of height and angle in the existing technology. In terms of process flow, a dual-spray booth is used for intermittent spraying combined with an intermediate buffer zone for leveling and drying, so that the workpiece is in a temperature and humidity controlled environment when it is transferred between processes, ensuring the consistency of interlayer adhesion, while decoupling drying waiting time from the production line rhythm. By having the above three technical modules run in parallel on the timeline, and be independent of each other in terms of data flow while being uniformly controlled by the control unit, the simultaneous protection of clean environment maintenance, directional removal of paint mist, and coating uniformity is achieved.

[0008] Secondly, this application provides a gradient pressure control and nozzle coordination control system for clean precision spray painting, including a control unit for a workpiece spray painting system. The workpiece spray painting system includes a first spray booth, a transition buffer zone, and a second spray booth arranged sequentially along the production line. Each spray booth is divided into multiple pressure control zones from top to bottom and equipped with diagonally opposite dual nozzles and pressure sensors. The control system adopts the following technical solution: The pressure target configuration module is used to configure the pressure target value for each pressure control zone and associate the pressure target value with the corresponding pressure sensor for storage. The pressure deviation calculation module is used to collect the pressure measurement values ​​of each pressure sensor, compare the pressure measurement values ​​with the corresponding pressure target values ​​to obtain the pressure deviation value, and mark the corresponding pressure control area as the area to be adjusted when the pressure deviation value exceeds the allowable deviation range. The linkage adjustment module is used to generate linkage adjustment commands based on the area to be adjusted and send them to the corresponding air supply and exhaust side actuators to keep the pressure deviation value within the allowable range and maintain the air supply volume greater than the exhaust volume. The initial deflection angle calculation module is used to obtain the geometric dimension information of the workpiece to be sprayed, calculate the initial deflection angle of the diagonal dual nozzles based on the geometric dimension information and the preset reference gun distance, and send the initial position control command of the nozzles; wherein, the preset reference gun distance is the target distance from the diagonal dual nozzles to the surface of the workpiece to be sprayed. The height deviation adjustment module is used to control the diagonal double spray nozzles of the first spray booth to perform primer spraying on the workpiece to be sprayed. At the same time, it collects the actual distance from the diagonal double spray nozzles to the surface of the workpiece to be sprayed and calculates the height deviation from the preset reference gun distance. When the height deviation exceeds the preset deviation threshold, it sends a spray nozzle height adjustment command to the height adjustment mechanism to obtain the adjusted actual gun distance. The deflection angle coordination adjustment module is used to calculate the optimal deflection angle based on the adjusted actual gun distance, generate a deflection angle coordination adjustment command based on the difference between the optimal deflection angle and the initial deflection angle, and send it to the nozzle angle adjustment mechanism. The spraying flow control module is used to control the conveying mechanism to transfer the workpiece to be sprayed to the transition buffer for leveling and drying after the primer spraying is completed. After the preset time is reached, it is transferred to the second spray booth, and the module controls the diagonal double spray nozzles of the second spray booth to perform topcoat or protective clear coat spraying. The module continuously performs the above-mentioned pressure deviation calculation and linkage adjustment, as well as height deviation calculation and angle coordination adjustment steps during the primer, topcoat or protective clear coat spraying process.

[0009] Thirdly, this application provides a computer device, which adopts the following technical solution: A computer device includes a memory, a processor, and a computer program stored in the memory, the processor executing the computer program to perform the steps of the method as described in the first aspect.

[0010] Fourthly, this application provides a computer-readable storage medium, which adopts the following technical solution: A computer-readable storage medium storing a computer program that can be loaded by a processor and executed as in any of the methods in the first aspect.

[0011] In summary, this application includes at least one of the following beneficial technical effects: maintaining the directional flow of clean air from top to bottom within the spray booth through gradient pressure control and effectively removing paint mist, thus avoiding convective contamination and paint mist overflow; ensuring precise matching of the paint mist coverage width with the workpiece width and paint film uniformity through coordinated adjustment of the distance and angle of the diagonal dual spray nozzles; and avoiding cross-contamination between different coatings by spraying the primer and topcoat separately in separate booths and leveling and drying through a transition buffer zone. The above solutions are suitable for precision painting scenarios with high cleanliness requirements, such as integrated circuit components, and can improve the consistency of paint film quality and the yield rate of coatings, while reducing rework costs caused by pressure fluctuations or nozzle distance deviations. Attached Figure Description

[0012] Figure 1 This is a first flowchart illustrating a gradient pressure control and nozzle coordinated control method for clean precision spraying, according to one embodiment of this application.

[0013] Figure 2 This is a second flowchart illustrating the gradient pressure control and nozzle coordinated control method for clean precision spraying, according to one embodiment of this application.

[0014] Figure 3 This is a schematic diagram of the third process of a gradient pressure control and nozzle coordinated control method for clean precision spraying, according to one embodiment of this application.

[0015] Figure 4 This is a schematic diagram of the fourth process of a gradient pressure control and nozzle coordinated control method for clean precision spraying, according to one embodiment of this application. Detailed Implementation

[0016] To make the purpose, technical solution, and advantages of this application clearer, the following description is provided in conjunction with the appendix. Figures 1-4 The present application will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the application.

[0017] This application discloses a gradient pressure control and nozzle coordinated control method for clean precision spraying, which is executed by the control unit of the workpiece spraying system. The workpiece spraying system includes a first spray booth, a transition buffer zone and a second spray booth arranged sequentially along the production line. Each spray booth is divided into multiple pressure control zones from top to bottom and is equipped with diagonal dual nozzles and pressure sensors.

[0018] Specifically, the first spray booth is used for primer spraying, the transition buffer zone is used for leveling and drying between processes, and the second spray booth is used for topcoat or protective clear coat spraying. These three booths are connected in series along the production line, allowing the workpiece to flow unidirectionally to complete all painting processes. The first and second spray booths have identical internal structures, each divided from top to bottom into a top air supply zone, a working zone, and a bottom exhaust zone. A transition buffer zone serves as a pressure buffer area between the two spray booths. These four zones constitute a progressively decreasing pressure control system. Different height areas within each spray booth perform different functions: the upper area is responsible for clean air supply, the middle area for spraying operations, and the lower area for paint mist removal. The different pressure target values ​​in each area create a progressively decreasing pressure gradient within the spray booth. The transition buffer zone isolates the two spray booths with a near-normal atmospheric pressure, preventing paint mist from cross-diffusion between processes.

[0019] Each spray booth contains two sets of diagonal dual-nozzle sprayers along the workpiece conveying direction. Each set includes two nozzles: a left nozzle and a right nozzle positioned on either side of the workpiece. The two sets of diagonal dual-nozzle sprayers are arranged sequentially along the conveying direction to cover different length sections of the workpiece. The height and skew angle adjustments of the two sets of nozzles are controlled uniformly or independently by a control unit. For shorter workpieces, only one set of diagonal dual-nozzle sprayers can be used for spraying; for longer workpieces, both sets of diagonal dual-nozzle sprayers operate synchronously and independently perform height deviation acquisition and skew angle coordinated adjustment. Pressure sensors are distributed within each area to collect local pressure data.

[0020] As a specific implementation of the workpiece painting system, the pressure control area includes a top air supply area, a working area, and a bottom exhaust area located inside each paint booth from top to bottom, as well as a transition buffer zone located between two paint booths. The pressure target value of each pressure control area is based on the atmospheric pressure outside the paint booth and decreases step by step. Each paint booth is equipped with an air supply filter at the top, and the pressure sensor of the top air supply area is arranged below the air supply filter. The pressure sensor of the working area is arranged in the middle of the side wall of the paint booth and below the bracket of the diagonal double spray head. The pressure sensor of the transition buffer zone is arranged in the middle of the passage between the two paint booths. Each paint booth is equipped with an exhaust device at the bottom, and the pressure sensor of the bottom exhaust area is arranged above the exhaust device.

[0021] The top air supply zone, working zone, and bottom exhaust zone correspond to the functional division of different height levels inside the spray booth, while the transition buffer zone corresponds to the connecting channel between two spray booths. The top air supply zone is located below the air supply filter at the top of the spray booth and is the area where filtered clean airflow enters the spray booth. The working zone is located in the middle of the spray booth and is the area where diagonal dual spray nozzles perform spraying operations. The transition buffer zone is located at the connecting channel between two spray booths and is the area through which workpieces pass during inter-process transfer. It also serves as a pressure control area, acting as a buffer and isolation between the two booths. The bottom exhaust zone is located above the bottom exhaust device of the spray booth and is the area where paint mist is directionally sucked out.

[0022] The target pressure values ​​for each zone are referenced to the atmospheric pressure outside the paint booth. This means that the sensor readings reflect the slight differential pressure between the zone's interior and the external atmosphere. The target pressure values ​​decrease progressively, with the highest pressure in the top supply air zone and the lowest in the bottom exhaust air zone. This creates a transition from positive to negative pressure within the paint booth, causing the airflow to move directionally from top to bottom. A transition buffer zone, with pressure between the work area and the bottom exhaust air zone, isolates the two paint booths with a near-normal atmospheric pressure. In practice, differential pressure sensors can be used, with a range covering ±100 Pa and an accuracy of at least ±0.5 Pa, sufficient to measure the minute pressure differences between zones within the paint booth.

[0023] In this embodiment, each spray booth is equipped with an air supply filter on its top. This air supply filter is a HEPA high-efficiency particulate air filter, installed at the air outlet on the top panel of the spray booth. External air is driven by the air supply fan through the HEPA filter before entering the spray booth. The aforementioned HEPA filter has a filtration level of H13 or H14, with a filtration efficiency of not less than 99.95% for particles larger than 0.3μm. The air exchange rate inside the spray booth is not less than 25 times per hour, ensuring that the interior of the spray booth meets the ISO Class 7 (Class 10,000) cleanliness standard, providing an environmental basis that meets the requirements for particulate matter concentration control for the spraying of integrated circuit components.

[0024] Pressure sensors in the top air supply zone are arranged 5 to 10 cm below the HEPA filter, with 1 to 2 sensors placed diagonally. These sensors are used to monitor the pressure of the filtered clean airflow. The target pressure value for this zone is +8 to +15 Pa. A slight positive pressure is maintained to prevent unfiltered external air from entering through gaps in the paint booth doors, observation windows, or other unsealed areas.

[0025] The pressure sensors in the work area are arranged in two groups: the first group, one on each side, is positioned on the side wall of the spray booth at a height of 1.2 to 1.5 meters above the ground, and is used to monitor the lateral pressure distribution in the spraying operation space; the second group, two sensors, is positioned below the brackets of the diagonally opposite dual spray heads at a height of 10 to 20 centimeters above the workpiece surface, and is used to monitor pressure changes in the core spraying area. The second group of sensors is installed 2 to 8 centimeters above the workpiece surface in the core spraying space to avoid paint mist directly contaminating the sensor probes. Its measurements characterize the pressure state of the work area. The target pressure value for this area is +3 to +8 Pa. Spatially, the work area corresponds to the region 2 to 8 centimeters above the workpiece surface between the spray head and the workpiece. This area is the core working space where paint mist travels from the nozzle to the workpiece surface during spraying. Its pressure state directly affects the flight trajectory and adhesion uniformity of the paint mist. Maintaining the pressure in the work area within a slightly positive pressure range of +3 to +8 Pa can prevent excessive pressure differentials from disturbing the paint mist's flight direction while preventing external contaminants from laterally intruding into the core spraying area.

[0026] One pressure sensor for the transition buffer zone is located in the middle of the channel between the two paint booths. It is used to monitor the pressure status in the workpiece flow channel. The target pressure value in this area is 0 to -3 Pa, close to normal pressure or slightly negative pressure, which plays a role in pressure buffering and transition between the two paint booths.

[0027] Each spray booth is equipped with an exhaust system at the bottom, which includes a water curtain system and an electrostatic precipitator. The water curtain system is installed above the exhaust vent on the bottom plate of the spray booth to capture paint mist particles. The electrostatic precipitator is located in the downstream duct of the water curtain system to remove residual charged particles after water curtain treatment. One to two pressure sensors are located 10 to 20 cm above the water curtain system in the bottom exhaust area to monitor the negative pressure in the paint mist removal area. The target pressure value in this area is -20 to -50 Pa, maintaining sufficient negative pressure to directionally draw paint mist aerosols and solvent volatiles to the exhaust system for discharge.

[0028] For example, taking the integrated circuit substrate spraying scenario as an example, the interior height of the first spray booth is approximately 2m. A HEPA filter is installed 15cm from the top of the ceiling. Two sensors in the top air supply zone are positioned 8cm below the filter, arranged diagonally. Sensors on the side walls of the work area are installed at a height of 1.4m, one on each side. Sensors under the spray nozzle bracket are installed 15cm from the workpiece surface, one on each side. The transition channel is approximately 0.8m long, with sensors positioned in the center of the channel. The water curtain device is installed 50cm above the base plate, and two sensors in the bottom exhaust zone are positioned 15cm above the water curtain device. After the system starts, the sensors in each area collect data synchronously. The sensor readings in the top air supply zone are approximately +12Pa, in the work area approximately +5Pa, in the transition buffer zone approximately -1Pa, and in the bottom exhaust zone approximately -35Pa, with the target pressure values ​​decreasing progressively in each area. The paint booth has a pressure funnel effect, with positive pressure at the top and negative pressure at the bottom. Clean air flows naturally from top to bottom under the pressure difference, and paint mist is directed to the bottom exhaust device and discharged without flowing back to the work area. The transition buffer zone isolates the two paint booths under a slight negative pressure state to prevent paint mist from one paint booth from spreading to the other through the channel.

[0029] Reference Figure 1 A gradient pressure control and nozzle coordinated control method for clean precision spray painting, specifically including: Step S101: Configure the pressure target value for each pressure control zone and associate and store the pressure target value with the corresponding pressure sensor; The pressure target value refers to the pressure setpoint that is expected to be maintained in each pressure control zone, with the external atmospheric pressure of the paint booth as the reference. Associating and storing the pressure target value with the corresponding pressure sensor establishes a mapping relationship between zone number, sensor number, and pressure setpoint, enabling subsequent sensor measurements to be quickly matched with the corresponding zone's pressure target value for comparison.

[0030] Specifically, during the system initialization phase, the control unit reads the configuration information of each pressure control zone. This configuration information includes the zone identifier, the number of each pressure sensor within the zone, and the target pressure value and allowable deviation range for each zone. The control unit organizes this information into a pressure gradient control parameter table and stores it in memory. Each pressure sensor number in the parameter table corresponds to a target pressure value and an allowable deviation range. The target pressure values ​​decrease progressively from the top supply air zone to the bottom exhaust air zone, creating a smooth transition from positive to negative pressure.

[0031] Step S102: Collect the pressure measurement values ​​of each pressure sensor, compare the pressure measurement values ​​with the corresponding pressure target values ​​to obtain the pressure deviation value, and mark the corresponding pressure control area as the area to be adjusted when the pressure deviation value exceeds the allowable deviation range. The pressure deviation value refers to the difference between the current pressure measurement and the target pressure value for that area. A positive value indicates that the pressure is higher than the target value, while a negative value indicates that the pressure is lower than the target value. The allowable deviation range refers to the range within which the pressure in each area is allowed to fluctuate. Exceeding this range indicates that the pressure in the area has deviated from the normal control range and requires intervention from the actuator.

[0032] Specifically, the control unit has a sampling period of 5 to 10 seconds, traversing all pressure sensors and reading their current output values ​​during each sampling. For each sensor, the control unit retrieves the target pressure value and allowable deviation range for its region from the pressure gradient control parameter table, and calculates the pressure deviation value as equal to the measured pressure value minus the target pressure value. If the absolute value of the pressure deviation value is not greater than the allowable deviation range, the region is considered normal; if the absolute value of the pressure deviation value is greater than the allowable deviation range, the region identifier is written into the adjustment queue. The control unit simultaneously calculates the pressure difference between each pressure control zone within the paint booth, determines whether the pressure in each zone within the paint booth forms a gradient relationship decreasing from top to bottom, and calculates the pressure difference between the transition buffer zone and each zone within the adjacent paint booths, determining whether the pressure in the transition buffer zone is within the buffer isolation range. If the pressure difference between adjacent zones within the paint booth reverses or the pressure difference between the transition buffer zone and adjacent zones within the paint booth exceeds a preset range, the affected zones are simultaneously marked as adjustment zones.

[0033] For example, assuming the target pressure value for the top-supply air zone is +12 Pa and the allowable deviation range is ±2 Pa, if the current pressure measurement value of the sensor in this area is +6 Pa, then the pressure deviation value is -6 Pa, and its absolute value exceeds the allowable range of ±2 Pa. The control unit will mark the top-supply air zone as an area to be adjusted. Similarly, if the target pressure value for the bottom-exhaust air zone is -35 Pa and the allowable deviation range is ±5 Pa, and the current measurement value is -28 Pa, then the pressure deviation value is +7 Pa, and its absolute value exceeds the allowable range of ±5 Pa. This area will also be marked as an area to be adjusted.

[0034] Step S103: Generate a linkage adjustment command based on the area to be adjusted and send it to the corresponding air supply and exhaust side actuators to keep the pressure deviation value within the allowable range and maintain the air supply volume greater than the exhaust volume. The supply air actuator refers to the device that controls the air volume of the paint booth, including a supply air frequency converter and an electric supply air valve. The supply air frequency converter changes the air volume by adjusting the speed of the supply fan, and the electric supply air valve changes the airflow area by adjusting the valve opening. The exhaust air actuator refers to the device that controls the exhaust air volume of the paint booth, including an exhaust frequency converter fan and an electric exhaust valve. Interlocking regulation means that the supply and exhaust air sides act in concert rather than independently, considering the impact on other areas while adjusting the pressure in one area. Maintaining an air supply volume greater than the exhaust volume is a constraint condition to ensure a slight positive pressure throughout the paint booth, preventing unfiltered external air from seeping in through gaps.

[0035] Specifically, when the area to be adjusted is the top-supply air zone or the work area and the pressure deviation is too high (positive pressure), the control unit reduces the frequency of the supply air inverter or decreases the opening of the electric supply air valve to reduce the supply air volume. When the pressure deviation is insufficient (positive pressure), the control unit increases the frequency of the supply air inverter or increases the opening of the electric supply air valve to increase the supply air volume. When the area to be adjusted is the bottom-exhaust air zone and the negative pressure is insufficient, an adjustment command is generated to increase the frequency of the exhaust air inverter fan or increase the opening of the electric exhaust air valve to enhance the exhaust suction. After each adjustment, the control unit recalculates the ratio of supply air volume to exhaust air volume and maintains this ratio within the range of 1.05 to 1.15. When the frequency of the supply air inverter has reached the upper or lower limit and the pressure deviation has not been eliminated, the control unit activates the electric supply air valve for auxiliary adjustment.

[0036] In some embodiments, the ratio of supply air volume to exhaust air volume is dynamically adjusted based on the sealing performance of the paint booth and the cleanliness of the external environment. When the sealing performance of the paint booth deteriorates (e.g., aging of the door sealing strip, gaps appearing in the observation window) or the cleanliness of the external environment decreases (e.g., increased dust concentration in the workshop), the control unit adjusts the ratio towards the upper limit of 1.15 to increase the supply air volume margin and strengthen the positive pressure barrier effect. When the sealing performance of the paint booth is good and the cleanliness of the external environment meets the requirements, the control unit adjusts the ratio towards the lower limit of 1.05 to reduce the energy consumption of the air supply system. The dynamic adjustment of the ratio is achieved through a mapping table of sealing performance rating and external cleanliness level pre-stored in the control unit. After each adjustment, the pressure deviation value is continuously monitored in subsequent sampling cycles to verify whether it returns to the allowable range to verify the adjustment effect.

[0037] Step S104: Obtain the geometric dimension information of the workpiece to be sprayed, calculate the initial deflection angle of the diagonal dual nozzles based on the geometric dimension information and the preset reference gun distance, and send the initial position control command of the nozzles; wherein, the preset reference gun distance is the target distance from the diagonal dual nozzles to the surface of the workpiece to be sprayed. The geometric dimensions include the workpiece width and the design reference height of the workpiece surface. The workpiece width determines the spray area that the nozzles need to cover, and the design reference height is the ideal height position of the workpiece surface. The preset reference nozzle distance refers to the target distance from the diagonal dual nozzles to the surface of the workpiece to be sprayed, i.e., the optimal nozzle distance required by the spraying process. The initial tilt angle refers to the symmetrical tilt angle calculated by the diagonal dual nozzles based on the workpiece width and reference nozzle distance before spraying begins, so that the paint mist fan-shaped areas of the two nozzles cross-cover the workpiece surface. The initial nozzle position control command refers to the conversion of the calculated tilt angle and nozzle distance into positioning commands for the nozzle angle adjustment mechanism and height adjustment mechanism.

[0038] Specifically, the control unit obtains the workpiece width and the workpiece surface design reference height input by the operator through a human-machine interface or a host computer system, and simultaneously reads the preset reference gun distance. The control unit calculates the optimal deflection angle for the diagonal dual nozzles based on the workpiece width and the reference gun distance. The calculation method is that the deflection angle equals half the workpiece width divided by the arctangent of the reference gun distance, with the left nozzle deflection angle taking a negative value and the right nozzle deflection angle taking a positive value. The control unit generates an initial nozzle angle control command and sends it to the worm gear angle adjustment mechanism driven by a stepper motor, causing the two nozzles to rotate to their corresponding deflection angle positions. Simultaneously, based on the design reference height, it generates an initial nozzle height control command and sends it to the lead screw height adjustment mechanism driven by a servo motor, causing the nozzles to move to the reference gun distance from the workpiece surface.

[0039] As one implementation of the worm gear angle adjustment mechanism, the nozzle is mounted on the nozzle bracket via a universal joint. The universal joint adopts a ball joint structure, which allows the nozzle to deflect around the center of the ball in multiple degrees of freedom. Each nozzle corresponds to a set of stepper motor-driven worm gear reduction mechanisms. After receiving the deflection angle command sent by the control unit, the stepper motor drives the nozzle to rotate around the center of the universal joint to the target deflection angle position through the worm gear reduction mechanism. The worm gear reduction mechanism has a self-locking characteristic, which keeps the deflection angle of the nozzle stable during the spraying process and is not affected by vibration.

[0040] In some embodiments, the deflection angles of the left and right nozzles in the diagonal dual-nozzle system are determined by the control unit according to the workpiece width and reference gun distance using the deflection angle calculation formula. The two nozzles are independently driven by their respective stepper motors to achieve asymmetrical settings with different deflection angles. The angle adjustment mechanism has an adjustment range of ±15° and an adjustment accuracy of ±0.5°, covering the full deflection angle range required by the diagonal dual-nozzle system under typical workpiece width and reference gun distance conditions.

[0041] For example, taking an integrated circuit substrate with a width of 200mm as an example, with a preset reference nozzle distance of 150mm, the optimal deflection angle is arctan(100 / 150)≈33.7°, the left nozzle deflection angle is set to -33.7° and the right nozzle deflection angle is set to +33.7°. The nozzle angle adjustment mechanism adjusts the two nozzles to the above-mentioned deflection angles, and the height adjustment mechanism adjusts the nozzles to a position 150mm from the substrate surface. After that, the nozzles begin spraying from this initial position.

[0042] Step S105: Control the diagonal double spray nozzles of the first spray booth to perform primer spraying on the workpiece to be sprayed. At the same time, collect the actual distance from the diagonal double spray nozzles to the surface of the workpiece to be sprayed and calculate the height deviation from the preset reference gun distance. When the height deviation exceeds the preset deviation threshold, send the nozzle height adjustment command to the height adjustment mechanism to obtain the adjusted actual gun distance. The actual distance refers to the instantaneous distance between the nozzle and the workpiece surface measured by the displacement sensor during the spraying process. Height deviation is the difference between the actual distance and the preset reference nozzle distance, reflecting the degree to which local undulations on the workpiece surface cause the distance between the nozzle and the workpiece surface to deviate from the target value. The preset deviation threshold is the criterion for determining whether height deviation requires adjustment. The adjusted actual nozzle distance refers to the new distance between the nozzle and the workpiece surface after the height adjustment mechanism performs compensation; this value serves as the input parameter for recalculating the deflection angle in the next step. This step is performed only after the spraying process has begun; changes in the actual nozzle distance only occur when the nozzle moves along the workpiece surface during spraying due to surface undulations.

[0043] Specifically, laser displacement sensors are used, with at least two mounted diagonally on the nozzle bracket. The sensor optical axes point vertically downwards towards the workpiece surface, and the sampling period is 5 to 10 seconds. The control unit calculates the average value of the measurements from each laser displacement sensor as the current actual nozzle distance, and the difference between the actual distance and the preset reference distance is taken as the height deviation. When the absolute value of the height deviation exceeds the preset deviation threshold, the control unit calculates the height compensation amount and generates a height adjustment command, which is sent to the servo motor-driven lead screw height adjustment mechanism. The servo motor drives the nozzle bracket to move the compensation amount by a distance along the height direction, with an adjustment accuracy of ±0.05mm and a response time of no more than 0.5 seconds. After adjustment, the control unit reads the latest measurement value from the displacement sensor as the adjusted actual nozzle distance.

[0044] It should be noted that the maximum adjustment speed of the height adjustment mechanism is 50mm / s, which allows the nozzle to complete height compensation before the sprayer moves to the area with large protrusions or depressions on the workpiece surface, thus avoiding excessive local gun distance deviation due to compensation lag.

[0045] For example, the preset reference nozzle distance is 150mm, and the preset deviation threshold is ±2mm. When there is a 0.5mm protrusion on the workpiece surface, the actual distance measured by the displacement sensor is 149.5mm, and the height deviation is -0.5mm. Since its absolute value does not exceed the 2mm threshold, the nozzle maintains its current height. When there is a 3mm indentation on the workpiece surface, the actual distance is 153mm, and the height deviation is +3mm. Since its absolute value exceeds the 2mm threshold, the control unit generates a height compensation adjustment command of -3mm. The servo motor drives the nozzle to descend 3mm, restoring the actual nozzle distance to around 150mm.

[0046] Step S106: Calculate the optimal deflection angle based on the adjusted actual gun distance, generate a deflection angle coordinated adjustment command based on the difference between the optimal deflection angle and the initial deflection angle, and send it to the nozzle angle adjustment mechanism. The optimal deflection angle refers to the deflection angle of the diagonal dual nozzles, recalculated and verified based on the adjusted actual nozzle distance and the workpiece width in the geometric dimensions. The deflection angle coordinated adjustment command refers to the control command containing the new deflection angles of the left and right nozzles in the diagonal dual nozzles, which is sent to the nozzle angle adjustment mechanism to drive the two nozzles to synchronously perform deflection angle adjustments.

[0047] In this embodiment, after the control unit obtains the adjusted actual gun distance from the height adjustment mechanism, it reads the geometric dimension information of the workpiece to be coated from the memory and extracts the workpiece width parameter. It then substitutes the adjusted actual gun distance H into the deflection angle calculation formula α=arctan(W / 2H) to recalculate the candidate deflection angle α, keeping the workpiece width W unchanged. Next, the control unit calculates the paint mist coverage width based on the adjusted actual gun distance, the candidate deflection angle, and the nozzle spray cone angle of the diagonal dual nozzles. When the paint mist coverage width is less than the workpiece width, the candidate deflection angle and / or the adjusted actual gun distance are adjusted and recalculated until the paint mist coverage width is not less than the workpiece width. The candidate deflection angle that finally meets the conditions is determined as the optimal deflection angle.

[0048] Subsequently, the control unit calculates the angle difference between the optimal angle and the initial angle, generates a new angle for the left nozzle and a new angle for the right nozzle based on the angle difference, encapsulates it as an angle coordination adjustment command, and sends it to the nozzle angle adjustment mechanism for synchronous execution.

[0049] For example, assuming a preset reference gun distance of 150mm and a workpiece width of 200mm, the control unit calculates an initial deflection angle of 33.7°. During the spraying process, due to the protrusion of the workpiece surface and the increase in nozzle height, the adjusted actual gun distance becomes 147mm. The control unit substitutes 147mm and 200mm into the same calculation relationship to recalculate a candidate deflection angle of 34.2°. Based on the adjusted actual gun distance, candidate deflection angle, and nozzle spray cone angle, the control unit calculates the paint mist coverage width. After verification, the paint mist coverage width is not less than the workpiece width, and 34.2° is determined as the optimal deflection angle, with a deflection angle difference of 0.5°. The control unit adds 0.5° to the current deflection angle of the left nozzle (33.7°) to obtain a new deflection angle of 34.2° for the left nozzle, and adds 0.5° to the current deflection angle of the right nozzle (33.7°) to obtain a new deflection angle of 34.2° for the right nozzle. A deflection angle coordination adjustment command is generated and sent to the nozzle angle adjustment mechanism, and both nozzles synchronously deflect from 33.7° to 34.2°.

[0050] Step S107: After the primer is sprayed, the conveying mechanism is controlled to transfer the workpiece to be sprayed to the transition buffer for leveling and drying. After the preset time is reached, it is transferred to the second spray booth, and the diagonal double nozzles of the second spray booth are controlled to spray the topcoat or protective clear coat. During the primer, topcoat or protective clear coat spraying process, the above-mentioned steps of pressure deviation calculation and linkage adjustment, as well as height deviation calculation and angle coordination adjustment are continuously executed.

[0051] Specifically, the transition buffer zone refers to a sealed space located between the first and second spray booths, equipped with a temperature and humidity control module, used for the workpiece to naturally level and dry after the primer is applied. The preset duration refers to the time the workpiece remains in the transition buffer zone for leveling and drying, configured according to the primer type and workpiece material. The step of "continuously executing the above-mentioned pressure deviation calculation and linkage adjustment, as well as height deviation calculation and angle coordination adjustment" means that the gradient pressure control closed loop and the spray head coordination closed loop remain operational throughout the entire time period of primer and topcoat or protective clear coat application, without interruption due to process switching.

[0052] In this embodiment, after the primer is applied, the control unit controls the conveyor belt to send the workpiece from the first spray booth through an isolation damper into a transition buffer zone. The temperature in the transition buffer zone is maintained between 25 and 30°C, and the humidity is maintained between 40% and 60% RH. The workpiece dwell time is 3 to 10 minutes and is adjustable depending on the primer type and workpiece material. After the dwell time reaches the set value, the control unit controls the conveyor belt to send the workpiece from the transition buffer zone through another isolation damper into the second spray booth. The diagonal dual spray nozzles in the second spray booth also perform initial angle calculation and initial positioning before spraying, and similarly perform height deviation acquisition and angle adjustment during spraying. The gradient pressure control parameter tables for the first and second spray booths can be configured independently to adapt to the different cleanliness and mist emission requirements of different processes.

[0053] For example, after the integrated circuit substrate completes the primer coating in the first spray booth, it enters a transition buffer zone. The buffer zone temperature is set to 28°C, the humidity is set to 50%RH, and the dwell time is set to 5 minutes. After 5 minutes, the substrate enters the second spray booth to be coated with the topcoat. During the topcoat coating process, the displacement sensor detects a 1mm warpage at the edge of the substrate. The control unit automatically performs height compensation and angle adjustment to ensure that the topcoat film thickness is consistent with that of the primer.

[0054] In addition, when the pressure measurement value of the transition buffer exceeds the set safety threshold, an isolation damper closing command can be generated and sent to the isolation damper actuator between the two paint booths to cut off the airflow channel; when the pressure measurement value of the transition buffer returns to within the set safety threshold, an isolation damper opening command can be generated to restore the airflow channel.

[0055] In the above embodiment, the paint booth is divided into multiple pressure control zones from top to bottom and configured with progressively decreasing pressure target values. Pressure sensors collect pressure measurements in each zone in real time and compare them with the target values. When the pressure deviation exceeds the allowable range, the actuators on the air supply and exhaust sides are adjusted to bring the pressure back to the target range. At the same time, the air supply volume is always greater than the exhaust volume to maintain a slight positive pressure in the paint booth as a whole. Thus, the upper clean environment protection and the lower paint mist directional removal are achieved simultaneously in the same paint booth, which solves the contradiction between the opposite pressure environment requirements of cleanliness and mist removal in traditional solutions. In terms of spraying accuracy, the initial deflection angle of the diagonal dual nozzles is calculated based on the workpiece geometry and the reference gun distance. During the spraying process, the actual distance from the nozzle to the workpiece surface is collected in real time and the height deviation is detected. When the deviation exceeds the threshold, the height is adjusted to obtain a new actual gun distance. Then, the optimal deflection angle is recalculated based on the new gun distance and the nozzle angle is adjusted synchronously to keep the paint mist coverage constant when the gun distance fluctuates. This avoids the coverage mismatch problem caused by independent adjustment of height and angle in the existing technology. Compared with the vertical spraying method of a single nozzle, the diagonal dual nozzles spray at opposite deflection angles so that the paint mist fan cross-covers the workpiece surface. The uniformity of the paint film thickness can be improved by more than 30%. Especially in the edge area of ​​the workpiece and the area with changes in surface morphology, the cross-covering method effectively makes up for the defect of thinning of the paint film at the edge when spraying with a single nozzle.

[0056] In terms of process flow, a dual-spray booth is used for intermittent spraying, combined with intermediate transition buffer zone leveling and drying, so that the workpiece is in a temperature and humidity controlled environment when it is transferred between processes, ensuring the consistency of interlayer adhesion, and decoupling the drying waiting time from the production line rhythm. By having the above three technical modules run in parallel on the timeline, and be independent of each other in terms of data flow while being uniformly controlled by the control unit, the simultaneous protection of clean environment maintenance, directional removal of paint mist, and coating uniformity is achieved.

[0057] Reference Figure 2 As a further implementation of the gradient pressure control and nozzle coordinated control method, the method also includes: Step S201: When the change in the pressure measurement value of any pressure sensor relative to the adjacent sampling period exceeds the preset fluctuation threshold, the pressure sensor is marked as an abnormal sensor. Within the paint booth, pressure changes are gradual during steady-state operation. The speed adjustment response time of the supply and exhaust frequency converters is typically on the order of seconds, and the pressure field does not experience drastic jumps within a single sampling period. When the pressure measurement value of a pressure sensor changes beyond a preset fluctuation threshold between adjacent sampling periods, it indicates that the sensor may have malfunctioned (e.g., sensitive element drift, poor wiring contact) or been subjected to transient interference (e.g., airflow impact, electromagnetic interference). Its current output value no longer accurately reflects the pressure state of its area, and it is marked as an abnormal sensor to trigger subsequent fault-tolerant processing. A normal pressure sensor refers to a pressure sensor within its pressure control area that is not marked as abnormal and whose output value is reliable.

[0058] In this embodiment, the control unit not only calculates the pressure deviation value of each pressure sensor in each sampling cycle, but also calculates the difference between the current sampled value and the measured value of the previous sampling cycle for each pressure sensor and takes the absolute value. This absolute value is then compared with a preset fluctuation threshold. The preset fluctuation threshold refers to the maximum allowable change in pressure measurement value between two adjacent samples under normal operating conditions. It can be set according to the pressure fluctuation characteristics of each area. In the top air supply area and the working area, where the airflow is more active near the air supply outlet, the fluctuation threshold can be appropriately relaxed. In the bottom exhaust area, where the exhaust device generates periodic airflow pulsations, the fluctuation threshold needs to take into account the pulsation amplitude. When the absolute value of the difference corresponding to a pressure sensor exceeds the preset fluctuation threshold of its area, the control unit writes the pressure sensor's number into the anomaly flag table. In subsequent steps, the measured value of this sensor will no longer directly participate in the pressure deviation value calculation, but will instead enter the alternative value acquisition process.

[0059] For example, suppose the work area is equipped with three pressure sensors, numbered S1, S2, and S3, with a preset fluctuation threshold of 10 Pa. In a certain sampling period, the measured value of S2 abruptly changes from +5 Pa in the previous period to +28 Pa, a change of 23 Pa, exceeding the 10 Pa fluctuation threshold. The control unit marks S2 as an abnormal sensor. Meanwhile, the measured values ​​of S1 and S3 are +4.8 Pa and +5.2 Pa respectively, both within the normal range, maintaining a normal status. When the control unit subsequently calculates the pressure deviation for the work area, it will no longer use the abnormal value of +28 Pa for S2, but instead triggers a replacement value acquisition process.

[0060] Step S202: Determine whether there is a normal pressure sensor in the same pressure control area as the abnormal sensor; if yes, proceed to step S203; if no, proceed to step S204. Step S203: Obtain the pressure measurement value of the normal pressure sensor within the same pressure control area; Step S204: Obtain the pressure measurement value of the normal pressure sensor that is spatially closest to the abnormal sensor in the adjacent pressure control area; When an abnormal sensor is flagged, the control unit needs to find a reliable alternative measurement to maintain uninterrupted pressure deviation calculations for that area. The alternative value is obtained based on proximity: it is preferentially obtained from the same pressure control area as the abnormal sensor, because sensors within the same area are under similar pressure conditions, and their measurements best reflect the true pressure state of that area. Only when all sensors within the same area are flagged as abnormal is the measurement value from the nearest normal sensor in an adjacent pressure control area obtained, because the closer the spatial distance, the more similar the pressure environment, and the better the representativeness of the alternative value.

[0061] Specifically, after reading the abnormal sensor number from the abnormality label table, the control unit searches for the pressure control area identifier to which the sensor belongs, and then iterates through the status labels of all other pressure sensors within that area. If there is at least one normal pressure sensor that is not marked as abnormal, the pressure measurement value of one of the normal sensors is selected as the substitute value; when there are multiple normal sensors in the same area, the average of their measurements can be used as the substitute value to improve representativeness. If all sensors in the area are marked as abnormal, the control unit calculates the spatial distance between each normal pressure sensor and the abnormal sensor in adjacent pressure control areas, starting from the installation coordinates of the abnormal sensor, and selects the pressure measurement value of the normal sensor with the smallest distance as the substitute value.

[0062] It should be noted that when obtaining replacement values ​​across regions, the pressure environment of the area where the replacement sensor is located differs from that of the area where the abnormal sensor is located. Therefore, the replacement value is only used as a temporary estimate. The control unit also generates an abnormal sensor maintenance reminder signal and sends it to the maintenance terminal to prompt for prompt repair or replacement.

[0063] For example, suppose there is only one pressure sensor S4 in the bottom exhaust area. If S4 is marked as abnormal, and there are no other normal sensors in the same area, the control unit searches for the nearest adjacent area, the transition buffer zone. The transition buffer zone has one normal sensor S5, and the spatial distance between S5 and S4 is 0.6m. The control unit continues searching to the work area, which has three normal sensors. The closest sensor to S4 is S3, which is 1.2m away. Comparing the spatial distances of each candidate sensor to S4, S5 is the closest (0.6m), so the measured value of S5 is used as the replacement value for S4. Similarly, suppose S2 in the work area is marked as abnormal, but S1 and S3 are both normal. The control unit directly uses the average of the measured values ​​of S1 and S3 as the replacement value, without needing to search across areas.

[0064] Step S205: Replace the pressure measurement value of the abnormal sensor with the obtained pressure measurement value, and use it as the pressure measurement value of the area to which the abnormal sensor belongs in the calculation of the pressure deviation value.

[0065] The pressure deviation value is the basis for the control unit to determine whether adjustment is needed in each pressure control zone. It is calculated by subtracting the target pressure value of the zone from the measured pressure value. When the measured value of an abnormal sensor is replaced by a substitute value, the control unit uses the substitute value, not the original abnormal value, in the pressure deviation value calculation, allowing pressure monitoring in that zone to continue operating during sensor malfunctions. The substitute value is paired with the target pressure value of the zone containing the abnormal sensor, not the target pressure value of the zone containing the replacement sensor. This is because the substitute value represents an estimated pressure value for the zone containing the abnormal sensor and is only meaningful when compared with the target pressure value of that zone. When the abnormal sensor returns to normal (i.e., its measured value changes within the fluctuation threshold in subsequent sampling periods), the control unit clears its abnormal marker and resumes using its own measured value in the calculation; the substitute value becomes invalid simultaneously.

[0066] Specifically, the control unit writes the substitute value into the corresponding data slot in the data storage area of ​​the abnormal sensor, overwriting the original abnormal value. After that, the calculation process of the pressure deviation value in this area is completely consistent with that of the normal sensor. The control unit compares the substitute value with the pressure target value of the area to which the abnormal sensor belongs, calculates the pressure deviation value, and determines whether the deviation value exceeds the allowable deviation range. If it does, the area is marked as an area to be adjusted and a linkage adjustment command is generated.

[0067] For example, continuing with the previous example of an anomaly in the bottom exhaust zone S4, after S4 is marked as abnormal, the control unit takes the measured value of the transition buffer S5, -1 Pa, as a substitute value and writes it into the data slot of S4. The target pressure value for the bottom exhaust zone is -35 Pa. The control unit compares the substitute value -1 Pa with the target pressure value -35 Pa and calculates a pressure deviation value of +34 Pa. This deviation value indicates that the negative pressure in the bottom exhaust zone is seriously insufficient (the actual substitute value is much higher than the target negative pressure value). The control unit marks the bottom exhaust zone as an area to be adjusted and generates an adjustment command to increase the frequency of the exhaust variable frequency fan.

[0068] It should be noted that since the substitute value comes from the transition buffer rather than the bottom exhaust area, the actual pressure deviation may not be as large as +34Pa. However, this estimate is sufficient to trigger the adjustment action to make the system respond in the correct direction. The accurate deviation value can be obtained after S4 returns to normal. When the variation of the measured value of S4 returns to within the fluctuation threshold in subsequent sampling cycles, the control unit clears the abnormal mark of S4 and resumes using S4's own measured value for calculation.

[0069] In the above implementation, when any pressure sensor inside the paint booth malfunctions or experiences a transient interference causing abnormal fluctuations in the measured value, the control unit can promptly detect the anomaly and mark the faulty sensor. Subsequently, it obtains alternative measured values ​​according to the principle of priority within the area and proximity across areas. The alternative values ​​are then substituted into the pressure deviation value calculation to ensure that the pressure monitoring of that area does not stop during the period of sensor malfunction. This avoids the problem of the entire pressure control area failing due to the failure of a single sensor, thus affecting the stability of the pressure gradient in the paint booth. At the same time, maintenance reminder signals prompt maintenance personnel to perform timely repairs, ensuring the long-term reliable operation of the pressure monitoring network.

[0070] As one implementation of step S103, generating a linkage adjustment command based on the area to be adjusted and sending it to the corresponding air supply and exhaust side actuators includes: The corresponding air supply side actuator and air exhaust side actuator are determined according to the marking of the area to be adjusted; wherein, the air supply side actuator includes an air supply frequency converter and an electric air supply valve corresponding to the air supply filter, and the air exhaust side actuator includes an exhaust frequency converter fan and an electric exhaust valve in the exhaust device; Specifically, the air supply inverter regulates the speed of the air supply fan motor by changing the power supply frequency; the higher the speed, the greater the volume of fresh air delivered into the paint booth per unit time. The electric air supply valve is installed in the air supply duct and drives the valve plate to rotate via an electric actuator, changing the airflow area of ​​the duct; the larger the opening, the lower the duct resistance and the greater the air supply volume. The exhaust inverter fan regulates the exhaust suction force by changing its speed; the higher the speed, the greater the volume of air extracted from the paint booth per unit time. The electric exhaust valve is installed in the exhaust duct and changes the exhaust channel resistance by adjusting its opening.

[0071] The supply air actuator and supply air filter are installed on the same supply air duct. The supply air filter is responsible for intercepting particulate matter in the fresh air to ensure the cleanliness of the supplied air. The supply air frequency converter and electric supply air valve are responsible for adjusting the supply air volume, and the two work in series. The exhaust air actuator is located inside the exhaust air device. The exhaust air device includes paint mist treatment units such as water curtains and electrostatic dust removal to purify the exhaust air. The exhaust air frequency converter and electric exhaust air valve are responsible for adjusting the exhaust air volume. When the exhaust air volume changes, the airflow through the paint mist treatment unit changes accordingly.

[0072] In addition, the exhaust-side actuator also includes a evaporative cooling pad pump flow rate regulating device. The water film thickness of the evaporative cooling pad device changes with the pump flow rate. When the water film thickness increases, the duct resistance increases and the exhaust volume decreases; when the water film thickness decreases, the duct resistance decreases and the exhaust volume increases. Besides regulating the frequency of the exhaust variable frequency fan and the opening of the electric exhaust valve, the control unit can also use the evaporative cooling pad pump flow rate as an auxiliary means of regulating the exhaust volume. When the frequency of the exhaust variable frequency fan has reached its upper limit and the opening of the electric exhaust valve has reached its limit, but the negative pressure in the bottom exhaust area is still insufficient, the control unit generates a command to reduce the evaporative cooling pad pump flow rate to reduce duct resistance and increase the exhaust volume.

[0073] In this embodiment, the control unit pre-stores a zone-actuator mapping table, which records the identifier of each pressure control zone and its corresponding supply-side actuator number and exhaust-side actuator number. When a zone is marked as an area to be adjusted, the control unit uses the zone identifier as an index to query the mapping table to obtain the corresponding supply air inverter number, electric supply air valve number, exhaust air inverter fan number, and electric exhaust air valve number. Subsequently, in subsequent steps, a linkage adjustment command is sent to one or more actuators based on the type of pressure deviation value. The zone-actuator mapping relationship is configured once during the system commissioning phase according to the paint booth piping layout and does not change dynamically during operation.

[0074] For example, suppose the top air supply zone corresponds to the air supply inverter number VFD-S1 and the electric air supply valve number VAV-S1 in the mapping table, and the bottom exhaust zone corresponds to the exhaust inverter fan number VFD-E1 and the electric exhaust valve number VAV-E1. When the top air supply zone is marked as an area to be adjusted, the control unit queries the mapping table to obtain VFD-S1 and VAV-S1, and subsequent linkage adjustment commands will be sent to these two actuators; when the bottom exhaust zone is marked as an area to be adjusted, the control unit obtains VFD-E1 and VAV-E1, and linkage adjustment commands will be sent to these two actuators.

[0075] Next, after determining the corresponding supply and exhaust actuators, the linkage adjustment command generated based on the area to be adjusted mainly falls into the following four categories: 1. When the area to be adjusted is the top air supply area or the working area and the pressure deviation value is too high, a linkage adjustment command is generated to reduce the frequency of the air supply inverter or reduce the opening of the electric air supply valve. When the pressure deviation value is insufficient, a linkage adjustment command is generated to increase the frequency of the air supply inverter or increase the opening of the electric air supply valve. Excessive positive pressure refers to a pressure measurement value in the top air supply area or work area exceeding the target pressure value and the upper limit of the allowable deviation range. In this case, the air supply volume in the area is excessive relative to the exhaust volume, which may cause air containing paint mist to diffuse to the outside of the paint booth or adjacent areas. Insufficient positive pressure refers to a pressure measurement value below the target pressure value and the lower limit of the allowable deviation range. In this case, the air supply volume in the area is insufficient to maintain the positive pressure barrier, and unpurified air from outside may seep into the paint booth through gaps such as door seams and observation windows, contaminating the surface of the workpiece.

[0076] In this embodiment, when the area to be adjusted is a top-supply air zone or a working area, the control unit reads the pressure deviation value of that area and determines the direction of the deviation. If the pressure deviation value is too high (positive pressure), the control unit generates an adjustment command to reduce the frequency of the air supply inverter or to reduce the opening of the electric air supply valve. Both methods can reduce the air supply volume, thereby reducing the area pressure. The control unit selects the priority adjustment target based on the current frequency range of the air supply inverter. When the inverter frequency is in the middle range (not close to the upper or lower limit), the inverter frequency is adjusted first because the inverter has a fast response speed and high adjustment accuracy. When the inverter frequency is close to the lower limit, the opening of the electric air supply valve is adjusted first. If the pressure deviation value is insufficient (positive pressure), the operation is reversed. The control unit generates an adjustment command to increase the frequency of the air supply inverter or to increase the opening of the electric air supply valve, again selecting the priority adjustment target based on the frequency range of the inverter. The adjustment command includes a target frequency value or a target opening value. The target value is calculated by the control unit according to the magnitude of the pressure deviation value according to a preset adjustment ratio.

[0077] For example, suppose the target pressure in the work area is +5 Pa, the allowable deviation range is ±2 Pa, the current measured pressure is +9 Pa, the pressure deviation is +4 Pa, and the deviation direction is positive pressure (too high). The control unit checks that the current frequency of the air supply inverter is 38 Hz, which is in the middle range (lower limit 20 Hz, upper limit 50 Hz). Therefore, it prioritizes generating a command to reduce the inverter frequency, calculating the target frequency as 33 Hz according to the preset adjustment ratio. After the control unit adjusts the frequency from 38 Hz to 33 Hz, the pressure in the work area drops back to +6 Pa in the next sampling cycle. It is still outside the allowable range, but the deviation has narrowed. The control unit continues to generate small reduction commands until the pressure returns to the range of +3 Pa to +7 Pa.

[0078] 2. When the area to be adjusted is the bottom exhaust area and the pressure deviation value is insufficient negative pressure, a linkage adjustment command is generated to increase the frequency of the exhaust variable frequency fan or increase the opening of the electric exhaust valve. When the pressure deviation value is too high negative pressure, a linkage adjustment command is generated to decrease the frequency of the exhaust variable frequency fan or decrease the opening of the electric exhaust valve. Insufficient negative pressure refers to a pressure measurement value in the bottom exhaust area that is higher than the target pressure value and exceeds the allowable deviation range. In other words, the absolute value of the negative pressure is not large enough, and the exhaust suction is insufficient to effectively draw the air containing paint mist downwards from the spray booth. The paint mist may then stagnate in the upper part of the spray booth and adhere to the workpiece surface. Excessive negative pressure refers to a pressure measurement value that is lower than the target pressure value and exceeds the allowable deviation range. In other words, the absolute value of the negative pressure is too large, and the exhaust suction is too strong, potentially drawing away clean air from the upper part of the spray booth too quickly, disrupting the top-to-bottom gradient airflow and increasing the load on the air supply system.

[0079] In this embodiment, when the area to be adjusted is the bottom exhaust zone, the control unit reads the pressure deviation value of that area and determines the direction of the deviation. If the pressure deviation value is insufficient negative pressure, the control unit generates an adjustment command to increase the frequency of the exhaust variable frequency fan or to increase the opening of the electric exhaust valve. Both methods can enhance the exhaust suction force and deepen the negative pressure. When the frequency of the exhaust variable frequency fan is in the middle range, the fan frequency is adjusted first. When the fan frequency is close to the upper limit, the opening of the electric exhaust valve is increased as a supplementary measure. If the pressure deviation value is too high negative pressure, the operation is reversed. The control unit generates an adjustment command to decrease the frequency of the exhaust variable frequency fan or to decrease the opening of the electric exhaust valve to weaken the exhaust suction force and reduce the negative pressure. The target frequency value or target opening value in the adjustment command is also calculated by the control unit according to the pressure deviation value according to a preset adjustment ratio. After adjustment, the control unit continuously monitors whether the pressure deviation value returns to the allowable range in subsequent sampling cycles.

[0080] For example, assuming the target pressure in the bottom exhaust zone is -35 Pa with an allowable deviation range of ±5 Pa, and the current measured pressure is -25 Pa, the pressure deviation is +10 Pa, indicating insufficient negative pressure. The control unit checks that the current frequency of the exhaust variable frequency fan is 30 Hz, which is in the middle range (lower limit 15 Hz, upper limit 45 Hz). Therefore, it prioritizes generating a command to increase the fan frequency, calculating the target frequency to be 38 Hz according to the preset adjustment ratio. After the control unit increases the fan frequency from 30 Hz to 38 Hz, the negative pressure in the bottom exhaust zone deepens to -32 Pa in the next sampling cycle. The control unit continues to make small adjustments until the pressure returns to the range of -30 Pa to -40 Pa.

[0081] It should be noted that when the negative pressure in the bottom exhaust area is insufficient and the frequency of the exhaust variable frequency fan has reached its upper limit and the opening of the electric exhaust valve has reached its limit, the pressure deviation value still has not returned to the allowable range. The control unit generates an exhaust abnormality alarm signal and sends it to the operation and maintenance terminal. The alarm signal includes the current pressure measurement value, the pressure target value, the magnitude of the deviation value, and the record information of the adjustment actions that have been performed, so as to prompt the operation and maintenance personnel to check whether there are hardware abnormalities such as water curtain blockage, duct leakage, or fan failure in the exhaust device.

[0082] 3. When the area to be adjusted is a transition buffer zone, according to the direction of the pressure difference between the transition buffer zone and each pressure control zone connected to the airflow, a linkage adjustment command is generated for the air supply side actuator or exhaust side actuator corresponding to the area with abnormal pressure difference with the transition buffer zone in the top air supply zone, working zone or bottom exhaust zone. The transition buffer zone is a connecting passage between two adjacent paint booths. It does not have independent air supply or exhaust actuators; its pressure is influenced by the airflow dynamics of each pressure control zone within both paint booths. When the pressure in the top air supply zone or work area is too high, airflow diffuses from the high-pressure side towards the transition buffer zone, causing its pressure to rise. Conversely, when the negative pressure in the bottom exhaust zone is too strong, airflow is drawn from the transition buffer zone through the passage into the bottom exhaust zone of the paint booth, causing its pressure to drop. Therefore, pressure anomalies in the transition buffer zone are not directly regulated by its own actuators, but rather indirectly controlled by identifying the direction of the abnormal pressure difference, locating the associated area, and then adjusting the actuators in that area.

[0083] In this embodiment, when the area to be adjusted is a transition buffer zone, the control unit calculates the pressure difference between the transition buffer zone and each pressure control zone connected to the airflow, and compares each difference with the corresponding preset pressure difference range to identify abnormal directions. If the pressure difference between the transition buffer zone and the working area shrinks to below the preset range (i.e., the pressures of the two areas tend to be close), it indicates that the pressure in the working area is too high, forcing the airflow into the transition buffer zone. The control unit generates a reduction adjustment command to the air supply side actuator of the working area to reduce the air supply volume and pressure in the working area. If the pressure difference between the transition buffer zone and the bottom exhaust zone expands to above the preset range (i.e., the pressure difference between the two areas widens), it indicates that the negative pressure in the bottom exhaust zone is too strong, excessively drawing away the airflow from the transition buffer zone. The control unit generates a reduction adjustment command to the exhaust side actuator of the bottom exhaust zone to weaken the exhaust suction force and reduce the negative pressure in the bottom exhaust zone. After adjustment, the control unit continuously monitors whether the pressure difference between the transition buffer zone and adjacent areas returns to the preset range in subsequent sampling cycles.

[0084] For example, suppose the target pressure value of the transition buffer zone is -1 Pa, the current measured value is +4 Pa, the pressure difference between the transition buffer zone and the working zone (currently +5 Pa) is 1 Pa, and the pressure difference between the transition buffer zone and the bottom exhaust zone (currently -35 Pa) is 39 Pa. The preset normal range for the pressure difference between the transition buffer zone and the working zone is 4 Pa ​​to 8 Pa, and the normal range for the pressure difference between the transition buffer zone and the bottom exhaust zone is 30 Pa to 38 Pa. The comparison reveals that the 1 Pa difference between the transition buffer zone and the working zone is lower than the lower limit of the normal range (4 Pa), indicating that the pressure in the working zone is too high, causing airflow to be forced into the transition buffer zone, thus increasing its pressure. Simultaneously, the 39 Pa difference between the transition buffer zone and the bottom exhaust zone exceeds the upper limit of the normal range (38 Pa), indicating that the negative pressure in the bottom exhaust zone is too strong, drawing airflow away from the transition buffer zone. After comprehensive judgment, the control unit simultaneously sends a reduction command to the actuator on the air supply side of the working zone and a reduction command to the actuator on the exhaust side of the bottom exhaust zone, restoring pressure balance in the transition buffer zone from both sides.

[0085] 4. When the frequency of the air supply inverter has reached the upper or lower limit and the pressure deviation value is still not within the allowable range, an auxiliary adjustment command for the electric air supply valve is generated as a linkage adjustment command; wherein, the auxiliary adjustment direction of the electric air supply valve corresponds to the deviation direction of the pressure deviation value.

[0086] The upper and lower frequency limits are the boundary values ​​of the frequency adjustment range of the air supply inverter, determined by the rated parameters of the fan motor and the system design conditions. When the air supply inverter frequency has reached the upper limit, the fan is already running at full speed, and simply increasing the frequency cannot further increase the air volume. When the frequency has reached the lower limit, the fan has already dropped to the minimum safe operating speed, and further reduction may cause the fan to stop or insufficient heat dissipation. In this case, if the pressure deviation value still does not return to the allowable range, it indicates that the inverter's individual adjustment has reached its limit, and an electric air supply valve needs to be introduced as an auxiliary adjustment method.

[0087] Specifically, before generating each inverter adjustment command, the control unit checks whether the current inverter frequency has reached its upper or lower limit. If it has reached the boundary and the pressure deviation value is still not within the allowable range, the control unit generates an auxiliary adjustment command for the electric air supply valve. The auxiliary adjustment direction corresponds to the deviation direction of the pressure deviation value. When the pressure is too high and the air supply volume needs to be reduced, the opening of the electric air supply valve is reduced to increase the duct resistance and limit the air supply volume; when the pressure is too low and the air supply volume needs to be increased, the opening of the electric air supply valve is increased to reduce the duct resistance and increase the air supply volume. The auxiliary adjustment command includes a target opening value. The control unit calculates the increment based on the current pressure deviation value and the current valve opening, and gradually adjusts the valve opening until the pressure deviation value returns to the allowable range or the valve opening also reaches its limit.

[0088] For example, assuming the target pressure in the top air supply zone is +15 Pa and the allowable deviation range is ±3 Pa, the current measured pressure is +8 Pa, and the pressure deviation is -7 Pa, indicating insufficient positive pressure. The control unit first attempts to increase the frequency of the air supply inverter, but the current frequency has already reached the upper limit of 50 Hz and cannot be increased further. The control unit then generates an auxiliary adjustment command for the electric air supply valve. The current valve opening is 55%, and the target opening is calculated to be 80% based on the pressure deviation value. The control unit gradually increases the valve opening from 55% to 80%. After the valve opening increases, the duct resistance decreases. Although the fan speed has reached its upper limit, the actual air volume increases due to the reduced duct resistance. The pressure in the top air supply zone recovers to +12 Pa in subsequent sampling periods, returning to the allowable range of +12 Pa to +18 Pa.

[0089] In the above embodiments, the control unit can accurately match the corresponding actuator according to the type of the area to be adjusted and the direction of pressure deviation. For the top air supply area and the working area, the air supply volume is adjusted by the air supply side actuator to achieve positive pressure control. For the bottom exhaust area, the exhaust volume is adjusted by the exhaust side actuator to achieve negative pressure control. For the transition buffer zone, the pressure balance is restored by indirectly adjusting the actuator of the associated area by identifying the abnormal direction of the pressure difference in the airflow connection area. When the frequency converter reaches its capacity limit, an electric air valve is automatically introduced for auxiliary adjustment to broaden the overall adjustment range. This ensures that the pressure in each pressure control area in the paint booth is always stable within the target range and the gradient distribution is not disrupted, thus guaranteeing the directional flow of paint mist and the cleanliness of the workpiece surface during the painting process.

[0090] Reference Figure 3 As one implementation of step S106, the steps of calculating the optimal deflection angle based on the adjusted actual gun distance, generating a deflection angle coordinated adjustment command based on the difference between the optimal deflection angle and the initial deflection angle, and sending it to the nozzle angle adjustment mechanism include: Step S301: Based on the adjusted actual gun distance and the workpiece width in the geometric dimension information, recalculate the candidate deflection angle using the same calculation relationship as the initial deflection angle. The candidate deflection angle is a value recalculated after the nozzle height adjustment is completed, using the adjusted actual nozzle distance instead of the preset reference nozzle distance as the input parameter. The initial deflection angle is pre-calculated based on geometric dimensions and the preset reference nozzle distance, and the nozzle is set according to the initial deflection angle before spraying begins. When the height adjustment mechanism adjusts the nozzle height according to the height deviation, the actual distance from the nozzle to the workpiece surface changes from the preset reference nozzle distance to the adjusted actual nozzle distance. The initial deflection angle originally calculated based on the preset reference nozzle distance is no longer applicable to the new nozzle distance conditions. Therefore, the same calculation relationship needs to be used to recalculate the deflection angle with the adjusted actual nozzle distance.

[0091] Specifically, after receiving the adjusted actual nozzle distance from the height adjustment mechanism, the control unit reads the geometric dimensions of the workpiece to be sprayed from the memory and extracts the workpiece width parameter. The control unit substitutes the adjusted actual nozzle distance H_new into the deflection angle calculation formula α_new = arctan(W / 2H_new) to recalculate the candidate deflection angle α_new. This calculation relationship is based on the geometric relationship between the nozzle position, nozzle distance, and workpiece width. The nozzle is located diagonally above the workpiece, and the deflection angle determines the landing point of the spray centerline on the workpiece surface. The nozzle distance and deflection angle together determine the projection of the spray coverage area onto the workpiece width direction.

[0092] Step S302: Obtain the spray cone angle of the diagonal dual nozzles. Calculate the paint mist coverage width based on the adjusted actual gun distance, candidate deflection angle, and spray cone angle. When the paint mist coverage width is less than the workpiece width, increase the candidate deflection angle and / or decrease the adjusted actual gun distance. Recalculate the paint mist coverage width based on the adjusted candidate deflection angle and adjusted actual gun distance until the paint mist coverage width is not less than the workpiece width. Determine the candidate deflection angle that finally meets the conditions as the optimal deflection angle. The spray cone angle is the inherent spray diffusion angle of the nozzle, determined by the nozzle model and spraying parameters, reflecting the conical diffusion range of the paint mist after it exits the nozzle. The paint mist coverage width is the actual span of the paint mist cone across the width of the workpiece when spraying under given nozzle distance and deflection angle conditions; it is influenced by the nozzle distance, deflection angle, and spray cone angle. A larger nozzle distance results in a wider paint mist diffusion range; a larger deflection angle causes the spray point to be further outward from the workpiece; and a larger spray cone angle results in a greater diffusion amplitude per unit nozzle distance. While candidate deflection angles are calculated, it is not yet confirmed whether they can completely cover the workpiece width with paint mist; therefore, they need to be substituted into the coverage width calculation for verification.

[0093] In this embodiment, the control unit acquires the nozzle spray cone angle of the diagonally opposite dual nozzles. This cone angle parameter is stored as a constant in the control unit after the nozzle selection is determined. The control unit substitutes the adjusted actual nozzle distance H_new, the candidate deflection angle α_new, and the nozzle spray cone angle into the calculation formula: Coverage width = 2 × H_new × tan(α_new + θ / 2), where θ is the nozzle spray cone angle.

[0094] Next, the control unit calculates the paint mist coverage width and compares it with the workpiece width: if the paint mist coverage width is not less than the workpiece width, it means that the candidate angle can ensure that the paint mist completely covers the workpiece surface, and the control unit directly determines the candidate angle as the optimal angle; if the paint mist coverage width is less than the workpiece width, it means that the spraying under the current candidate angle will leave uncovered gaps on the workpiece surface, the control unit increases the candidate angle to move the spray landing point further outward to expand the coverage span, and / or decreases the adjusted actual gun distance to bring the nozzle closer to the workpiece to increase the paint mist diffusion range. After each adjustment, the paint mist coverage width is recalculated and compared with the workpiece width again, and the cycle is iterated until the paint mist coverage width is not less than the workpiece width, and the candidate angle that finally meets the conditions is determined as the optimal angle.

[0095] For example, assuming the adjusted actual gun distance is 260mm, the candidate deflection angle is 24°, the nozzle spray cone angle is 30°, and the workpiece width is 400mm, the control unit substitutes 260mm, 24°, and 30° into the coverage width calculation relationship, obtaining a paint mist coverage width of 370mm, which is less than the workpiece width of 400mm. This indicates that the paint mist cannot completely cover the workpiece at the 24° candidate deflection angle. The control unit increases the candidate deflection angle to 27° and recalculates the paint mist coverage width to 405mm, which is not less than the workpiece width of 400mm. The coverage condition is met, and the control unit determines 27° as the optimal deflection angle.

[0096] Step S303: Calculate the angle difference between the optimal angle and the initial angle, and add the angle difference to the current angles of the left and right nozzles in the diagonal dual nozzles respectively, to generate an angle coordination adjustment command including the new angles of the left and right nozzles, and send it to the corresponding nozzle angle adjustment mechanism for synchronous execution; wherein, the current angles of the left and right nozzles are both the initial angles.

[0097] The deflection angle difference is the angular difference between the optimal deflection angle and the initial deflection angle, reflecting the change in deflection angle before and after nozzle height adjustment. Diagonal dual nozzles include a left nozzle and a right nozzle symmetrically arranged on both sides of the workpiece. Both nozzles are set to their initial deflection angle before spraying begins. After height adjustment is completed and the optimal deflection angle is determined, both nozzles need to be synchronously adjusted from their initial deflection angle to the new deflection angle position calculated based on the optimal deflection angle.

[0098] Specifically, the control unit calculates the difference between the optimal deflection angle and the initial deflection angle, determining the sign and magnitude of the difference. If the difference is positive, it indicates the optimal deflection angle is greater than the initial deflection angle, requiring both nozzles to increase their deflection angle. If the difference is negative, it indicates the optimal deflection angle is less than the initial deflection angle, requiring both nozzles to decrease their deflection angle. The control unit adds the deflection angle difference to the current deflection angle of the left nozzle to obtain a new deflection angle for the left nozzle, and adds the same difference to the current deflection angle of the right nozzle to obtain a new deflection angle for the right nozzle. Since the left and right nozzles are symmetrically arranged and have the same current deflection angle, the two new deflection angles are the same in value but symmetrical in deflection direction after adding the same difference. The control unit encapsulates the new deflection angles of the left and right nozzles into a deflection angle coordination adjustment command and sends it to the nozzle angle adjustment mechanism. Upon receiving the command, the left and right nozzle drivers in the angle adjustment mechanism drive the corresponding nozzles to rotate, ensuring that both nozzles synchronously reach the new deflection angle position before spraying begins.

[0099] For example, assuming the initial deflection angle is 20°, the optimal deflection angle is 27°, and the deflection angle difference is +7°, the control unit adds +7° to the current deflection angle of the left nozzle (20°) to obtain a new deflection angle of 27° for the left nozzle, and adds +7° to the current deflection angle of the right nozzle (20°) to obtain a new deflection angle of 27° for the right nozzle. The control unit generates a coordinated deflection angle adjustment command containing the new deflection angles of 27° for both the left and right nozzles, and sends it to the nozzle angle adjustment mechanism. The drivers of the two nozzles synchronously rotate the nozzles from 20° to 27°, and spraying begins after the coordinated deflection angle adjustment is completed.

[0100] In the above implementation, after the nozzle height is adjusted, the control unit recalculates the candidate deflection angle based on the adjusted actual gun distance. The optimal deflection angle is determined only after the verification and iteration of the paint mist coverage width ensures that the candidate deflection angle can meet the coverage requirements of the workpiece width. This avoids the problem of insufficient paint mist coverage caused by the mismatch of deflection angle due to changes in gun distance. Subsequently, a deflection angle collaborative adjustment command is generated based on the difference between the optimal deflection angle and the initial deflection angle, driving the diagonal dual nozzles to synchronously adjust the deflection angle. This ensures that the two nozzles maintain the match between the paint mist coverage width and the workpiece width under the new gun distance after height adjustment, guaranteeing the integrity and uniformity of the spray coverage.

[0101] As a further implementation of the gradient pressure control and nozzle coordinated control method, the control method also includes the following three situations and corresponding handling methods during the spraying of primer, topcoat, or protective clear coat: 1. When a protrusion on the workpiece surface causes the actual distance between the diagonal dual nozzles and the workpiece surface to be sprayed to be less than the preset reference nozzle distance, the control unit sends a nozzle height adjustment command to the height adjustment mechanism to raise the nozzles and obtain the adjusted actual nozzle distance. Based on the adjusted actual nozzle distance, the optimal deflection angle is recalculated, and a deflection angle coordination adjustment command is generated based on the difference between the optimal deflection angle and the initial deflection angle and sent to the nozzle angle adjustment mechanism. The recalculated optimal deflection angle is greater than the initial deflection angle. In this context, a workpiece surface protrusion refers to a region on the workpiece surface that is locally higher than the reference surface, such as a weld, folded edge, or localized coating buildup. When the nozzle passes over a protruding area, the actual distance from the diagonal dual nozzles to the workpiece surface to be sprayed decreases to less than the preset reference nozzle distance. The control unit sends a nozzle height adjustment command to the height adjustment mechanism to raise the nozzles, thus obtaining the adjusted actual nozzle distance. Since the protruding area still keeps the workpiece surface higher than the reference surface, the adjusted actual nozzle distance is still less than the preset reference nozzle distance. Based on the same calculation relationship as the initial deflection angle, the optimal deflection angle is recalculated using the adjusted actual nozzle distance and is greater than the initial deflection angle.

[0102] In this embodiment, the control unit continuously collects the actual distance from the diagonal dual nozzles to the surface of the workpiece during the spraying process and compares it with a preset reference nozzle distance. When the actual distance is less than the preset reference nozzle distance, the control unit drives the nozzles to rise, and after rising, obtains the adjusted actual nozzle distance. The control unit substitutes the adjusted actual nozzle distance and the workpiece width into the same calculation relationship as the initial deflection angle calculation to recalculate the candidate deflection angle, which is determined as the optimal deflection angle after verification by the paint mist coverage width. Since the adjusted actual nozzle distance is still less than the preset reference nozzle distance, and the optimal deflection angle is greater than the initial deflection angle, the control unit calculates the deflection angle difference between the optimal deflection angle and the initial deflection angle, and adds the deflection angle difference to the current deflection angle of the left and right nozzles to generate a deflection angle collaborative adjustment command, which is sent to the nozzle angle adjustment mechanism for synchronous execution.

[0103] For example, assuming a preset baseline nozzle distance of 150mm, a workpiece width of 200mm, and an initial deflection angle of 33.7°, when the nozzle passes a 5mm high weld protrusion on the workpiece surface, the actual distance decreases to 145mm. The control unit sends a height adjustment command to raise the nozzle by 2mm, resulting in an actual nozzle distance of 147mm. The control unit substitutes 147mm and 200mm into the calculation relationship to recalculate the candidate deflection angle, which is 34.2°. After verification that the paint mist coverage width is not less than the workpiece width, 34.2° is determined as the optimal deflection angle, with a deflection angle difference of 0.5°. The control unit adds 0.5° to the current deflection angle of 33.7° for both the left and right nozzles, generating a new deflection angle of 34.2°. This collaborative adjustment command is then sent to the nozzle angle adjustment mechanism.

[0104] 2. When the workpiece surface is concave, causing the actual distance between the diagonal dual nozzles and the workpiece surface to be sprayed to be greater than the preset reference nozzle distance, the control unit sends a nozzle height adjustment command to the height adjustment mechanism to lower the nozzles and obtain the adjusted actual nozzle distance. Based on the adjusted actual nozzle distance, the optimal deflection angle is recalculated, and a deflection angle coordination adjustment command is generated based on the difference between the optimal deflection angle and the initial deflection angle and sent to the nozzle angle adjustment mechanism; wherein, the recalculated optimal deflection angle is less than the initial deflection angle; In this context, a workpiece surface depression refers to an area on the workpiece surface that is locally lower than the reference plane, such as an inner corner of a bend, a groove, or an edge transition arc. When the nozzle passes through a depression area, the actual distance from the diagonal dual nozzles to the surface of the workpiece increases to a level greater than the preset reference nozzle distance. The control unit sends a nozzle height adjustment command to the height adjustment mechanism, causing the nozzles to lower, resulting in the adjusted actual nozzle distance. Because the depression area still causes the workpiece surface to be lower than the reference plane, the adjusted actual nozzle distance is still greater than the preset reference nozzle distance. Based on the same calculation relationship as the initial deflection angle, the optimal deflection angle, recalculated using the adjusted actual nozzle distance, is less than the initial deflection angle.

[0105] In this embodiment, when the actual distance is greater than the preset reference gun distance, the control unit drives the nozzle to lower. After lowering, the adjusted actual gun distance is obtained. The adjusted actual gun distance and the workpiece width are substituted into the same calculation relationship as the initial deflection angle to recalculate the candidate deflection angle. After verification by the paint mist coverage width, the optimal deflection angle is determined. Since the adjusted actual gun distance is still greater than the preset reference gun distance, the optimal deflection angle is less than the initial deflection angle. The control unit calculates the deflection angle difference between the optimal deflection angle and the initial deflection angle, and adds the deflection angle difference to the current deflection angles of the left and right nozzles to generate a deflection angle collaborative adjustment command, which is sent to the nozzle angle adjustment mechanism for synchronous execution.

[0106] For example, assuming a preset baseline nozzle distance of 150mm, a workpiece width of 200mm, and an initial deflection angle of 33.7°, when the nozzle passes through a 5mm deep groove on the workpiece surface, the actual distance increases to 155mm. The control unit sends a height adjustment command to lower the nozzle by 2mm, resulting in an actual nozzle distance of 153mm. The control unit substitutes 153mm and 200mm into the calculation relationship to recalculate the candidate deflection angle, which is 33.2°. After verification that the paint mist coverage width is not less than the workpiece width, 33.2° is determined as the optimal deflection angle, with a deflection angle difference of -0.5°. The control unit adds -0.5° to the current deflection angle of 33.7° for both the left and right nozzles, generating a new deflection angle of 33.2°. This new angle adjustment command is then sent to the nozzle angle adjustment mechanism.

[0107] 3. When the nozzle reciprocates to the reversing position, the control unit maintains the current nozzle height unchanged, swaps the deflection directions of the left and right nozzles in the diagonal double nozzles, and generates a deflection angle coordinated adjustment command to be sent to the nozzle angle adjustment mechanism.

[0108] The reciprocating motion of the nozzles refers to the movement of the diagonal double nozzles along the width of the workpiece to cover the entire surface of the workpiece. The reversing position is the position where the nozzles reverse their direction of motion when they reach the end of their stroke. In the diagonal double nozzles, the left and right nozzles are symmetrically arranged on both sides of the workpiece. The deflection direction of the two nozzles is related to the direction of motion. When the direction of motion is from left to right, the left nozzle deflects to the right and the right nozzle deflects to the left. After the direction of motion is reversed, the deflection directions of the two nozzles need to be interchanged to maintain the same spray coverage.

[0109] In this embodiment, the control unit monitors the reciprocating position of the diagonally opposite dual nozzles. When the nozzles reach the reversing position, the control unit does not send a height adjustment command, maintaining the current nozzle height unchanged. The control unit swaps the deflection directions of the left and right nozzles; the left nozzle changes from its original deflection direction to the opposite direction, and the right nozzle changes from its original deflection direction to the opposite direction, while the absolute value of the deflection angle remains unchanged. The control unit generates a deflection angle coordinated adjustment command based on the swapped deflection directions and sends it to the nozzle angle adjustment mechanism. The angle adjustment mechanism drives the left and right nozzles to rotate synchronously to the swapped deflection directions, and then the nozzles begin to move in the opposite direction.

[0110] For example, suppose two diagonally opposite nozzles move from left to right, with the left nozzle deflecting 33.7° to the right and the right nozzle deflecting 33.7° to the left. When the nozzles reach the right-side reversal position, the control unit maintains the nozzle height constant, changes the left nozzle's deflection direction from right to left (deflection angle from +33.7° to -33.7°), and changes the right nozzle's deflection direction from left to right (deflection angle from -33.7° to +33.7°). A coordinated deflection angle adjustment command is generated and sent to the nozzle angle adjustment mechanism. After the two nozzles synchronously complete the direction swap, they begin moving from right to left.

[0111] In the above embodiments, the control unit adopts corresponding adjustment strategies for three typical working conditions during the spraying process: protrusions, depressions, and nozzle reversal. When there is a protrusion, the nozzle is raised and the optimal deflection angle is increased to compensate for the narrowing of the coverage area caused by the reduction of the gun distance. When there is a depression, the nozzle is lowered and the optimal deflection angle is reduced to avoid paint mist dissipation caused by the increase of the gun distance. When reversing, the height is kept constant and the deflection directions of the left and right nozzles are interchanged to match the spray coverage relationship after the movement direction is reversed. This ensures that the nozzle always maintains the match between the paint mist coverage width and the workpiece width during the changes in the workpiece surface morphology and the movement reversal, thus ensuring the uniformity and continuity of the spray coverage.

[0112] Reference Figure 4 As a further implementation of the gradient pressure control and nozzle coordinated control method, a temperature and humidity adjustment module is provided in the transition buffer zone; Step S401: After the workpiece to be sprayed enters the transition buffer, the control unit controls the temperature and humidity adjustment module to maintain the temperature and humidity in the transition buffer within the preset temperature and humidity range. The temperature and humidity control module is a device installed within the transition buffer zone to regulate the internal air temperature and humidity. It includes one or more of a heater, cooler, humidifier, and dehumidifier. The transition buffer zone is the connecting area between the first and second spray booths. Workpieces to be coated enter the transition buffer zone after the primer is applied for leveling and drying. The preset ranges are the upper temperature limit, lower temperature limit, upper humidity limit, and lower humidity limit pre-set in the control unit.

[0113] Specifically, after the workpiece to be coated enters the transition buffer zone, the control unit activates the temperature and humidity control module. The temperature and humidity control module monitors the temperature and humidity within the transition buffer zone in real time through sensors. When the temperature is below the lower limit of the preset range, the control unit activates the heater to raise the temperature; when the temperature is above the upper limit of the preset range, the control unit activates the cooler to lower the temperature. When the humidity is below the lower limit of the preset range, the control unit activates the humidifier to humidify; when the humidity is above the upper limit of the preset range, the control unit activates the dehumidifier to dehumidify, so that the temperature and humidity within the transition buffer zone are continuously maintained within the preset range.

[0114] Step S402: The control unit obtains the primer type and workpiece material of the workpiece to be sprayed, and configures the preset time according to the primer type and workpiece material; The primer type and workpiece material are input into the control unit by the operator via a human-machine interface before spraying begins. Primer type refers to the type of coating used for the primer layer on the workpiece to be sprayed, such as epoxy primer, polyurethane primer, or acrylic primer. Different primer types have different leveling and drying rates. Workpiece material refers to the type of material of the workpiece to be sprayed, such as carbon steel, aluminum alloy, or stainless steel. Different workpiece materials have different thermal conductivity and surface tension, which affect the primer leveling time differently. The preset duration is the total time the workpiece to be sprayed stays in the transition buffer zone, configured by the control unit based on the combination of primer type and workpiece material.

[0115] Step S403: After the workpiece to be sprayed has stayed in the transition buffer for a preset time, the control unit controls the conveying mechanism to transfer the workpiece to be sprayed to the second spray booth. The internal layout of the second spray booth is the same as that of the first spray booth, and the pressure target values ​​of each pressure control area in the second spray booth are configured independently.

[0116] In this embodiment, the control unit stores a mapping table between primer type, workpiece material, and preset duration. The control unit queries the mapping table using the primer type and workpiece material as indexes to obtain the corresponding preset duration. After the workpiece to be painted enters the transition buffer, the control unit starts timing. When the dwell time reaches the configured preset duration, the control unit controls the conveying mechanism to transfer the workpiece to be painted from the transition buffer to the second spray booth.

[0117] The interior layout of the second spray booth is the same as that of the first spray booth. It is also divided into multiple pressure control zones from top to bottom and equipped with diagonal dual spray nozzles and pressure sensors. However, the pressure target value of each pressure control zone in the second spray booth is configured independently according to the spraying process requirements of the topcoat or protective clear coat, and does not change with the pressure target value of the first spray booth.

[0118] For example, assuming the primer type of the workpiece to be sprayed is epoxy primer and the workpiece material is aluminum alloy, the control unit queries the mapping table to obtain a preset duration of 15 minutes. After the workpiece to be sprayed enters the transition buffer, the control unit starts timing, and at the same time, the temperature and humidity control module maintains the temperature at 22°C and the humidity at 50%. After 15 minutes, the control unit controls the conveyor mechanism to transfer the workpiece to the second spray booth. The target pressure value of the top air supply zone of the second spray booth is configured as +12Pa (+15Pa in the first spray booth), and the target pressure value of the bottom exhaust zone is configured as -30Pa (-35Pa in the first spray booth). The difference in the target pressure values ​​is independently set because the requirements for airflow organization during topcoat spraying are different from those for primer spraying.

[0119] In the above embodiments, after the workpiece to be sprayed enters the transition buffer, the control unit controls the temperature and humidity regulation module to maintain the temperature and humidity within a preset range, providing stable environmental conditions for primer leveling and drying. A preset time is configured according to the primer type and workpiece material, allowing different coatings and workpieces of different materials to obtain appropriate leveling and drying times, avoiding paint film defects caused by insufficient leveling or reduced production efficiency due to excessive waiting. After the dwell time reaches the configured value, the workpiece is transferred to the second spray booth. The second spray booth has the same internal layout as the first spray booth, but the pressure target value is configured independently, allowing primer spraying and topcoat spraying to be carried out under different pressure gradient conditions, improving the flexibility and adaptability of the spraying process.

[0120] This application also discloses a gradient pressure control and nozzle coordination control system for clean precision spraying.

[0121] A gradient pressure control and nozzle coordination control system for clean precision spray painting specifically includes a control unit for a workpiece spray painting system. The workpiece spray painting system includes a first spray booth, a transition buffer zone, and a second spray booth arranged sequentially along the production line. Each spray booth is divided into multiple pressure control zones from top to bottom and is equipped with diagonally dual nozzles and pressure sensors. The control system also includes: The pressure target configuration module is used to configure the pressure target value for each pressure control zone and associate and store the pressure target value with the corresponding pressure sensor. The pressure deviation calculation module is used to collect the pressure measurement values ​​of each pressure sensor, compare the pressure measurement values ​​with the corresponding pressure target values ​​to obtain the pressure deviation value, and mark the corresponding pressure control area as the area to be adjusted when the pressure deviation value exceeds the allowable deviation range. The linkage adjustment module is used to generate linkage adjustment commands based on the area to be adjusted and send them to the corresponding air supply and exhaust side actuators to keep the pressure deviation value within the allowable range and maintain the air supply volume greater than the exhaust volume. The initial deflection angle calculation module is used to obtain the geometric dimension information of the workpiece to be sprayed, calculate the initial deflection angle of the diagonal dual nozzles based on the geometric dimension information and the preset reference gun distance, and send the initial position control command of the nozzles; wherein, the preset reference gun distance is the target distance from the diagonal dual nozzles to the surface of the workpiece to be sprayed. The height deviation adjustment module is used to control the diagonal double nozzles of the first spray booth to perform primer spraying on the workpiece to be sprayed. At the same time, it collects the actual distance from the diagonal double nozzles to the surface of the workpiece to be sprayed and calculates the height deviation from the preset reference gun distance. When the height deviation exceeds the preset deviation threshold, it sends a nozzle height adjustment command to the height adjustment mechanism to obtain the adjusted actual gun distance. The deflection angle coordination adjustment module is used to calculate the optimal deflection angle based on the actual gun distance after adjustment, generate a deflection angle coordination adjustment command based on the difference between the optimal deflection angle and the initial deflection angle, and send it to the nozzle angle adjustment mechanism. The spraying flow control module is used to control the conveying mechanism to transfer the workpiece to be sprayed to the transition buffer for leveling and drying after the primer spraying is completed. After the preset time is reached, it is transferred to the second spray booth and the diagonal double spray nozzles of the second spray booth are controlled to perform topcoat or protective clear coat spraying. The module continuously executes the above-mentioned pressure deviation calculation and linkage adjustment, as well as height deviation calculation and angle coordination adjustment steps during the primer, topcoat or protective clear coat spraying process.

[0122] The gradient pressure control and nozzle coordinated control system for clean precision spraying according to the embodiments of this application can realize any of the above methods, and the specific working process of each module in the system can refer to the corresponding process in the above method embodiments.

[0123] In the several embodiments provided in this application, it should be understood that the provided methods and systems can be implemented in other ways. For example, the system embodiments described above are merely illustrative; for example, the division of a certain module is merely a logical functional division, and in actual implementation there may be other division methods, such as multiple modules can be combined or integrated into another system, or some features can be ignored or not executed.

[0124] In the above embodiments, the air supply side adjustment of the pressure control actuator adopts a combination of frequency converter adjustment of fan speed and electric air valve adjustment of opening. As an alternative embodiment, the air supply side adjustment can also adopt frequency converter adjustment or air valve adjustment alone. The air supply and exhaust linkage relationship adopts frequency converter linkage control in the above embodiments. As an alternative embodiment, mechanical fixed ratio linkage can also be adopted, that is, the air supply and exhaust fans are driven coaxially to run at a fixed speed ratio. The pressure sensor arrangement adopts a distributed arrangement of 6 to 8 points in the above embodiments. As an alternative embodiment, one sensor can be arranged at each of the key points at the top and bottom and the pressure in the middle area can be estimated.

[0125] Regarding nozzle height adjustment, the above implementation method uses a servo motor with a precision lead screw for driving and a laser displacement sensor for detection. As an alternative implementation method, the height adjustment actuator can be a cylinder-driven or semi-automatic method with manual adjustment and sensor monitoring. The height detection can be performed using a visual sensor or a contact probe for offline calibration.

[0126] Regarding nozzle angle adjustment, the above implementation method uses a stepper motor with a worm gear reducer. As an alternative implementation method, a servo motor with a reducer or a manual universal joint with an angle scale display can also be used. The diagonal dual nozzles operate with an adjustable deflection angle in the above implementation method. As an alternative implementation method, a fixed deflection angle or an array of three or more nozzles can also be used.

[0127] Regarding the interval spraying method, the above implementation adopts a layout of two spray booths with an intermediate buffer zone. As an alternative implementation, a single spray booth can be used for two round trips, or a drying waiting area can be set in the middle of a single spray booth. The primer drying method in the above implementation adopts natural leveling drying. As an alternative implementation, forced hot air drying or UV curing drying can also be used.

[0128] Regarding the paint mist treatment system, the above-described implementation method uses a combination of water curtain and electrostatic dust removal. As an alternative implementation method, multi-stage filtration with dry filter paper or activated carbon adsorption device can also be used. The water curtain parameters are fixed parameters in the above-described implementation method. As an alternative implementation method, the water curtain pump flow rate can also be set to adjustable as an auxiliary means of adjusting the exhaust volume.

[0129] It should be noted that the above alternative implementation methods can be selected according to specific working conditions and cost requirements, and all fall within the protection scope of this application.

[0130] This application also discloses a computer device.

[0131] A computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement a gradient pressure control and nozzle coordinated control method for clean precision spraying as described above.

[0132] This application also discloses a computer-readable storage medium.

[0133] A computer-readable storage medium storing a computer program that can be loaded by a processor and executed by any of the methods described above for gradient pressure control and nozzle coordinated control in a clean precision spraying process.

[0134] The computer-readable storage medium can be any tangible medium that contains or stores a program that can be used by or in connection with an instruction execution system, apparatus, or device; the program code contained on the computer-readable medium can be transmitted using any suitable medium, including but not limited to wireless, wire, optical fiber, RF, etc., or any suitable combination thereof.

[0135] The above are all preferred embodiments of this application and are not intended to limit the scope of protection of this application. Any feature disclosed in this specification (including the abstract and drawings) may be replaced by other equivalent or similar features unless specifically stated otherwise. That is, unless specifically stated otherwise, each feature is only one example of a series of equivalent or similar features.

Claims

1. A method for gradient pressure control and nozzle coordinated control in clean precision spraying, characterized in that, The control is executed by the control unit of the workpiece painting system, which includes a first spray booth, a transition buffer zone, and a second spray booth arranged sequentially along the production line. Each spray booth is divided into multiple pressure control zones from top to bottom and is equipped with diagonally dual spray nozzles and pressure sensors. The transition buffer zone is equipped with a pressure sensor. The control method includes: Configure the pressure target value for each pressure control zone, and associate and store the pressure target value with the corresponding pressure sensor; The pressure measurement values ​​of each pressure sensor are collected, and the pressure measurement values ​​are compared with the corresponding pressure target values ​​to obtain the pressure deviation value. When the pressure deviation value exceeds the allowable deviation range, the corresponding pressure control area is marked as an area to be adjusted. The pressure difference between each pressure control area inside the spray booth is calculated, and it is determined whether the pressure of each pressure control area forms a gradient relationship that decreases step by step from top to bottom. The pressure difference between the transition buffer and each pressure control area inside the spray booths on both sides is calculated. When the pressure difference between adjacent pressure control areas inside the spray booth reverses or the pressure difference between the transition buffer and the pressure control area inside the adjacent spray booth exceeds the preset range, the affected area is marked as an area to be adjusted. Based on the area to be adjusted, a linkage adjustment command is generated and sent to the corresponding air supply and exhaust side actuators to keep the pressure deviation value within the allowable range and maintain the air supply volume greater than the exhaust volume; when the pressure measurement value of the transition buffer exceeds the set safety threshold, an isolation damper closing command is generated and sent to the isolation damper actuator between the two paint booths to cut off the airflow channel; when the pressure measurement value of the transition buffer returns to within the set safety threshold, an isolation damper opening command is generated to restore the airflow channel. Obtain the geometric dimensions of the workpiece to be coated, calculate the initial deflection angle of the diagonal dual nozzles based on the geometric dimensions and the preset reference nozzle distance, and send the initial position control command for the nozzles; wherein, the preset reference nozzle distance is the target distance from the diagonal dual nozzles to the surface of the workpiece to be coated; The diagonal dual spray nozzles of the first spray booth are controlled to spray primer onto the workpiece to be sprayed. At the same time, the actual distance from the diagonal dual spray nozzles to the surface of the workpiece to be sprayed is collected and the height deviation from the preset reference gun distance is calculated. When the height deviation exceeds the preset deviation threshold, a spray nozzle height adjustment command is sent to the height adjustment mechanism to obtain the adjusted actual gun distance. The optimal deflection angle is calculated based on the adjusted actual gun distance. An angle coordination adjustment command is generated based on the difference between the optimal deflection angle and the initial deflection angle and sent to the nozzle angle adjustment mechanism. After the primer is applied, the control conveyor transfers the workpiece to be sprayed to the transition buffer for leveling and drying. After a preset time, it is transferred to the second spray booth, and the diagonal dual spray nozzles of the second spray booth are controlled to perform topcoat or protective clear coat spraying. During the primer, topcoat or protective clear coat spraying process, the above-mentioned pressure deviation calculation and linkage adjustment, as well as height deviation calculation and angle coordination adjustment steps are continuously executed.

2. The gradient pressure control and nozzle coordinated control method for clean precision spray painting according to claim 1, characterized in that, The pressure control zone includes a top air supply zone, a working zone, and a bottom exhaust zone located inside each spray booth from top to bottom, as well as a transition buffer zone between two spray booths. The target pressure value of each pressure control zone is based on the atmospheric pressure outside the spray booth and decreases progressively. Each spray booth is equipped with an air supply filter at the top, and the pressure sensor of the top air supply zone is located below the air supply filter. The pressure sensor of the working zone is located in the middle of the side wall of the spray booth and below the bracket of the diagonally opposite dual spray heads. The pressure sensor of the transition buffer zone is located in the middle of the passage between two spray booths. Each spray booth is equipped with an exhaust device at the bottom, and the pressure sensor of the bottom exhaust zone is located above the exhaust device.

3. The gradient pressure control and nozzle coordinated control method for clean precision spray painting according to claim 2, characterized in that, The method further includes: When the change in the pressure measurement value of any pressure sensor relative to the adjacent sampling period exceeds the preset fluctuation threshold, the pressure sensor is marked as an abnormal sensor. Determine whether a normal pressure sensor exists within the same pressure control area as the abnormal sensor. If it does, obtain the pressure measurement value of the normal pressure sensor within the same pressure control area. If it does not exist, obtain the pressure measurement value of the normal pressure sensor that is spatially closest to the abnormal sensor in an adjacent pressure control area. The obtained pressure measurement value is used to replace the pressure measurement value of the abnormal sensor, and is used as the pressure measurement value of the area to which the abnormal sensor belongs in the calculation of the pressure deviation value.

4. The gradient pressure control and nozzle coordinated control method for clean precision spray painting according to claim 2, characterized in that, The step of generating a linkage adjustment command based on the area to be adjusted and sending it to the corresponding air supply and exhaust side actuators includes: The corresponding air supply side actuator and air exhaust side actuator are determined according to the identification of the area to be adjusted; wherein, the air supply side actuator includes an air supply frequency converter and an electric air supply valve corresponding to the air supply filter, and the air exhaust side actuator includes an exhaust frequency converter fan and an electric exhaust valve in the exhaust device; When the area to be adjusted is the top air supply area or the working area and the pressure deviation value is too high, a linkage adjustment command is generated to reduce the frequency of the air supply inverter or reduce the opening of the electric air supply valve. When the pressure deviation value is insufficient, a linkage adjustment command is generated to increase the frequency of the air supply inverter or increase the opening of the electric air supply valve. When the area to be adjusted is the bottom exhaust area and the pressure deviation value is insufficient negative pressure, a linkage adjustment command is generated to increase the frequency of the exhaust variable frequency fan or increase the opening of the electric exhaust valve. When the pressure deviation value is too high negative pressure, a linkage adjustment command is generated to decrease the frequency of the exhaust variable frequency fan or decrease the opening of the electric exhaust valve. When the area to be adjusted is a transition buffer zone, a linkage adjustment command is generated for the air supply side actuator or exhaust side actuator corresponding to the area with abnormal pressure difference between the transition buffer zone and each pressure control area connected to the airflow, based on the direction of the pressure difference between the transition buffer zone and each pressure control area connected to the airflow. When the frequency of the air supply inverter has reached the upper or lower limit and the pressure deviation value is still not within the allowable range, an auxiliary adjustment command for the electric air supply valve is generated as the linkage adjustment command; wherein, the auxiliary adjustment direction of the electric air supply valve corresponds to the deviation direction of the pressure deviation value.

5. The gradient pressure control and nozzle coordinated control method for clean precision spray painting according to claim 1, characterized in that, The steps of calculating the optimal deflection angle based on the adjusted actual gun distance, generating a coordinated deflection angle adjustment command based on the difference between the optimal deflection angle and the initial deflection angle, and sending it to the nozzle angle adjustment mechanism include: Based on the adjusted actual gun distance and the workpiece width in the geometric dimension information, the candidate deflection angle is recalculated using the same calculation relationship as that used to calculate the initial deflection angle. Obtain the nozzle spray cone angle of the diagonal dual nozzles. Calculate the paint mist coverage width based on the adjusted actual gun distance, the candidate deflection angle, and the nozzle spray cone angle. When the paint mist coverage width is less than the workpiece width, increase the candidate deflection angle and / or decrease the adjusted actual gun distance. Recalculate the paint mist coverage width based on the adjusted candidate deflection angle and the adjusted actual gun distance until the paint mist coverage width is not less than the workpiece width. Determine the candidate deflection angle that finally meets the conditions as the optimal deflection angle. Calculate the angle difference between the optimal angle and the initial angle, and add the angle difference to the current angles of the left and right nozzles in the diagonal dual nozzles respectively to generate an angle coordination adjustment command including the new angles of the left and right nozzles, and send it to the corresponding nozzle angle adjustment mechanism for synchronous execution; wherein, the current angles of the left and right nozzles are both the initial angles.

6. The gradient pressure control and nozzle coordinated control method for clean precision spray painting according to claim 1, characterized in that, The method also includes the following steps during the application of primer, topcoat, or protective clear coat: When a protrusion on the workpiece surface causes the actual distance between the diagonal dual nozzles and the workpiece surface to be sprayed to be less than the preset reference nozzle distance, the control unit sends a nozzle height adjustment command to the height adjustment mechanism to raise the nozzles, thereby obtaining the adjusted actual nozzle distance. Based on the adjusted actual nozzle distance, the optimal deflection angle is recalculated, and a deflection angle coordination adjustment command is generated based on the difference between the optimal deflection angle and the initial deflection angle and sent to the nozzle angle adjustment mechanism; wherein, the recalculated optimal deflection angle is greater than the initial deflection angle; When the workpiece surface is concave, causing the actual distance from the diagonal dual nozzles to the workpiece surface to be sprayed to be greater than the preset reference nozzle distance, the control unit sends a nozzle height adjustment command to the height adjustment mechanism to lower the nozzles, thereby obtaining the adjusted actual nozzle distance. Based on the adjusted actual nozzle distance, the optimal deflection angle is recalculated, and based on the difference between the optimal deflection angle and the initial deflection angle, a deflection angle coordination adjustment command is generated and sent to the nozzle angle adjustment mechanism; wherein, the recalculated optimal deflection angle is less than the initial deflection angle; When the nozzle reciprocates to the reversing position, the control unit maintains the current nozzle height unchanged, swaps the deflection directions of the left and right nozzles in the diagonal dual nozzles, and generates a deflection angle coordinated adjustment command to be sent to the nozzle angle adjustment mechanism.

7. A gradient pressure control and nozzle coordinated control method for clean precision spray painting according to any one of claims 1 to 6, characterized in that, The transition buffer is equipped with a temperature and humidity control module; after the workpiece to be coated enters the transition buffer, the control unit controls the temperature and humidity control module to maintain the temperature and humidity in the transition buffer within a preset temperature and humidity range. The control unit obtains the primer type and workpiece material of the workpiece to be coated, and configures the preset duration according to the primer type and workpiece material; After the workpiece to be painted has been in the transition buffer for the preset time, the control unit controls the conveying mechanism to transfer the workpiece to be painted to the second paint booth, wherein the internal layout of the second paint booth is the same as that of the first paint booth, and the pressure target value of each pressure control area in the second paint booth is independently configured.

8. A gradient pressure control and nozzle coordination control system for clean precision spray painting, used to execute the gradient pressure control and nozzle coordination control method for clean precision spray painting as described in any one of claims 1 to 7, characterized in that, The control system includes a control unit for a workpiece painting system, which comprises a first spray booth, a transition buffer zone, and a second spray booth arranged sequentially along the production line. Each spray booth is divided into multiple pressure control zones from top to bottom and is equipped with diagonally opposite dual spray nozzles and pressure sensors. The control system also includes: The pressure target configuration module is used to configure the pressure target value for each pressure control zone and associate the pressure target value with the corresponding pressure sensor for storage. The pressure deviation calculation module is used to collect the pressure measurement values ​​of each pressure sensor, compare the pressure measurement values ​​with the corresponding pressure target values ​​to obtain the pressure deviation value, and mark the corresponding pressure control area as the area to be adjusted when the pressure deviation value exceeds the allowable deviation range. The linkage adjustment module is used to generate linkage adjustment commands based on the area to be adjusted and send them to the corresponding air supply and exhaust side actuators to keep the pressure deviation value within the allowable range and maintain the air supply volume greater than the exhaust volume. The initial deflection angle calculation module is used to obtain the geometric dimension information of the workpiece to be sprayed, calculate the initial deflection angle of the diagonal dual nozzles based on the geometric dimension information and the preset reference gun distance, and send the initial position control command of the nozzles; wherein, the preset reference gun distance is the target distance from the diagonal dual nozzles to the surface of the workpiece to be sprayed. The height deviation adjustment module is used to control the diagonal double spray nozzles of the first spray booth to perform primer spraying on the workpiece to be sprayed. At the same time, it collects the actual distance from the diagonal double spray nozzles to the surface of the workpiece to be sprayed and calculates the height deviation from the preset reference gun distance. When the height deviation exceeds the preset deviation threshold, it sends a spray nozzle height adjustment command to the height adjustment mechanism to obtain the adjusted actual gun distance. The deflection angle coordination adjustment module is used to calculate the optimal deflection angle based on the adjusted actual gun distance, generate a deflection angle coordination adjustment command based on the difference between the optimal deflection angle and the initial deflection angle, and send it to the nozzle angle adjustment mechanism. The spraying flow control module is used to control the conveying mechanism to transfer the workpiece to be sprayed to the transition buffer for leveling and drying after the primer spraying is completed. After the preset time is reached, it is transferred to the second spray booth, and the module controls the diagonal double spray nozzles of the second spray booth to perform topcoat or protective clear coat spraying. The module continuously performs the above-mentioned pressure deviation calculation and linkage adjustment, as well as height deviation calculation and angle coordination adjustment steps during the primer, topcoat or protective clear coat spraying process.

9. A computer device, characterized in that: The method includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the program, implements the method as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that: The computer program is stored that can be loaded by a processor and execute the method as described in any one of claims 1 to 7.

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