A modular spray control system and method of control

Abstract

The application belongs to the technical field of spraying control, and particularly relates to a modular spraying control system, comprising: a central control module, which is used for receiving input instructions, coordinating the work of other modules and performing spraying operations; a parameter input module, which is connected with the central control module and is used for receiving external spraying process parameter setting values; a signal input module, which is connected with the central control module and is used for receiving external on-off quantity control signals; and an analog quantity output module, which is connected with the central control module and is used for outputting analog quantity control signals. The application adopts a distributed modular structure, when a certain module fails, the failed module can be directly replaced online, the whole system does not need to be re-adjusted, the maintenance time and downtime loss are greatly shortened. Meanwhile, the functional modules can be flexibly added or reduced according to different spraying process requirements, the whole control system does not need to be replaced, the equipment modification cost and adaptation period are significantly reduced.

Description

Technical Field

[0001] This invention belongs to the field of spraying control technology, and particularly relates to a modular spraying control system and control method. Background Technology

[0002] With the rapid development of the automotive manufacturing industry, the painting process, as a key link in automobile manufacturing, has increasingly higher requirements for painting quality, production efficiency, and equipment reliability. Electrostatic rotary cup painting systems, due to their advantages such as good atomization effect, high paint utilization rate, and stable painting quality, have become the mainstream equipment for painting automotive body, bumper, and other components.

[0003] Traditional spray painting control systems typically employ a highly integrated, monolithic architecture, where all control functions are integrated into a single dedicated controller, with data exchange between functions achieved via an internal bus. While this monolithic architecture can meet basic control requirements in a single application scenario, it presents the following significant problems in actual production: First, the system has a high degree of integration but poor scalability. Different car models and different processes (such as primer, color paint, clear coat, and powder coating) have different requirements for control functions. However, the hardware resources and software functions inside the integrated controller are fixed. When it is necessary to adapt to a new painting process or add new control functions, it is often necessary to replace the entire controller, resulting in high equipment modification costs and long cycles.

[0004] Secondly, maintenance is difficult and downtime is long. The integrated controller has a high degree of coupling between its various functional modules. When a functional module fails, it usually needs to be returned to the factory for repair or the entire controller needs to be replaced. The maintenance cycle is long, which leads to a significant increase in production line downtime and seriously affects production efficiency.

[0005] In terms of control precision, traditional spraying control systems also have significant shortcomings: In terms of rotary cup speed control, the rotary cup speed range is typically 0-60000 rpm. Within different speed ranges, the dynamic characteristics of the air-bearing motor differ significantly. In the low-speed range, the mechanical friction of the air-bearing motor dominates, resulting in a slow system response; in the high-speed range, air resistance dominates, making the system prone to overshoot and oscillation. Traditional control systems use a single PID parameter for adjustment across the entire speed range, which cannot simultaneously address the control requirements of different speed ranges. This leads to large fluctuations in the rotary cup speed, directly affecting the atomization effect and the uniformity of the coating film thickness.

[0006] In terms of forming air control, the required forming airflow varies significantly depending on the diameter of the rotary cup. Small-diameter rotary cups are used for fine spraying, requiring low flow rates and high adjustment sensitivity; large-diameter rotary cups are used for large-area spraying, requiring high flow rates and high inertia. Traditional control systems use fixed proportional coefficients for adjustment, which cannot simultaneously meet the control accuracy requirements of different flow ranges, resulting in unstable spray patterns and uneven spray edges.

[0007] In terms of paint flow control, traditional control systems mostly adopt open-loop control, which means that the speed of the gear pump motor is controlled only according to the set value, without real-time feedback correction of the actual paint flow. Due to the influence of factors such as paint viscosity changes with temperature and pipeline resistance fluctuations, there is a large deviation between the actual paint flow and the set value, resulting in uneven coating thickness.

[0008] In terms of safety protection, traditional systems typically control the start and stop of the high-voltage generator only through communication. When the communication link fails, the high-voltage power supply cannot be reliably cut off, posing a safety hazard of high-voltage electrostatic injury.

[0009] Therefore, there is an urgent need for a modular, high-precision, and highly reliable spraying control system and method to solve the problems existing in the above-mentioned prior art. Summary of the Invention

[0010] The purpose of this invention is to address the aforementioned technical problems by providing a modular spraying control system and method.

[0011] In view of this, the present invention provides a modular spraying control system, comprising: The central control module is used to receive input commands, coordinate and control the work of other modules, and execute the spraying operation. The parameter input module is connected to the central control module and is used to receive external spraying process parameter settings. The signal input module is connected to the central control module and is used to receive external switch control signals; An analog output module, connected to the central control module, is used to output analog control signals; A high-voltage communication module, connected to the central control module, is used for data exchange with the high-voltage generator; The motor communication module is connected to the central control module and is used for data exchange with the motor controller; The data acquisition module is connected to the central control module and is used to acquire feedback signals from the spraying process. The rotary cup's rotation speed is controlled by driving air, and its spray shape is controlled by forming air. Gear pumps, driven by electric motors, are used to deliver paint; The analog output module is connected to a drive air proportional valve for controlling the rotation speed of the rotary cup and a forming air proportional valve for controlling the spraying shape of the rotary cup. The data acquisition module is connected to a speed sensor for detecting the rotation speed of the rotary cup, an air flow meter for detecting the forming air flow, and a paint flow sensor for detecting the paint flow. The central control module controls the drive air proportional valve, the forming air proportional valve, and the motor controller to achieve closed-loop control of the rotary cup rotation speed, spraying shape, and paint flow.

[0012] Furthermore, the central control module is pre-programmed with a control program written using function block programming. The control program includes independent high-pressure control function blocks, speed control function blocks, forming air control function blocks, paint flow control function blocks, and alarm diagnosis function blocks. The central control module is configured to selectively call and combine the above function blocks according to different spraying process requirements.

[0013] Furthermore, the parameter input module includes a first communication module for communicating with a host computer and / or a first analog-to-digital conversion module for receiving external analog signals; the signal input module is a digital input module.

[0014] Furthermore, the speed control function block is configured to execute a multi-stage stepped PID control method; The central control module calls the PID parameter group corresponding to the different speed ranges of the rotating cup's set speed or actual feedback value to perform closed-loop regulation.

[0015] Furthermore, the forming air control function block is configured to execute an interval proportional coefficient control method; The central control module uses a proportional coefficient corresponding to the set flow rate of the forming air to perform closed-loop adjustment based on the different flow rate ranges.

[0016] Furthermore, it also includes digital output modules and relays; The digital output module is connected to the central control module, and its output terminal controls the on / off state of the relay; The relay is connected in series in the drive power circuit of the high-voltage generator. When a fault or emergency stop signal is received, the central control module controls it to disconnect to cut off the drive power of the high-voltage generator.

[0017] Furthermore, the paint flow control function block is configured as follows: The paint flow rate setpoint is converted into a motor speed setpoint and sent to the motor controller to drive the gear pump. Simultaneously, it receives actual flow feedback from the paint flow sensor and dynamically adjusts the motor speed setpoint. It also monitors the pressure at the inlet and outlet of the gear pump, and controls the gear pump to stop running when the pressure is abnormal.

[0018] A modular spraying control method based on the above system includes the following steps: S1: System initialization, the central control module identifies the connected functional modules; S2: Receives spraying parameter settings and control commands; S3: The central control module starts the rotary cup and gear pump according to the instructions; S4: Real-time acquisition of feedback signals for rotary cup rotation speed, molding air flow rate, and coating flow rate; S5: The central control module dynamically adjusts the output of the drive air proportional valve and the forming air proportional valve based on the deviation between the feedback signal and the set value, using segmented PID control algorithm and interval proportional coefficient control algorithm respectively, to achieve closed-loop control. S6: After the spraying is completed, execute the shutdown procedure.

[0019] Furthermore, step S5 also includes a linkage adjustment step: When the rotation speed of the rotary cup changes, the set values ​​of the forming air flow and coating flow are adjusted synchronously to maintain the stability of the sprayed film thickness.

[0020] Furthermore, it also includes fault diagnosis and handling steps: Each functional block module monitors the hardware status in real time and reports it to the central control module; The central control module analyzes abnormal states and determines the fault level; If the fault is minor, an alarm will be triggered; if the fault is serious, an automatic shutdown or adaptive adjustment strategy will be implemented.

[0021] The beneficial effects of this invention are: This invention employs a distributed modular structure, dividing the control system hardware into multiple independent functional modules, including a central control module, parameter input module, signal input module, analog output module, high-voltage communication module, motor communication module, and data acquisition module. These modules are connected via standardized interfaces, supporting online plug-and-play expansion. When a module fails, it can be directly replaced online without requiring the entire system to be re-tuned, significantly reducing maintenance time and downtime losses. Furthermore, functional modules can be flexibly added or removed according to different spraying process requirements without replacing the entire control system, significantly reducing equipment modification costs and adaptation time.

[0022] This invention breaks down the control logic into independent high-pressure control, speed control, forming air control, paint flow control, and alarm diagnosis blocks. These blocks interact through standardized data interfaces and can be selectively called and combined according to different spraying process requirements. This allows a single program to adapt to multiple spraying scenarios, significantly shortening the program development cycle. Furthermore, each block operates independently, and an anomaly in one block will not affect the normal operation of other blocks, thus improving the system's fault tolerance.

[0023] This invention addresses the issue of significant differences in the dynamic characteristics of a rotary cup across different speed ranges by dividing the speed range into multiple intervals, each using an independent set of PID parameters for closed-loop control. A larger proportional gain is used in the low-speed range to improve response speed, while a smaller proportional gain is used in the high-speed range to avoid overshoot and oscillation. This achieves high-precision speed control across the entire speed range, effectively suppressing speed fluctuations, ensuring the stability of coating atomization, and ultimately improving the uniformity of the sprayed film thickness.

[0024] This invention addresses the issue of varying airflow requirements for forming in different types of rotary cups by dynamically adjusting a proportional coefficient based on the range of the set flow rate. A larger proportional coefficient is used in the low flow rate range to improve adjustment accuracy, while a smaller proportional coefficient is used in the high flow rate range to avoid system oscillation. This ensures stable airflow control for forming in rotary cups of different diameters and in different spraying scenarios, guaranteeing the stability of the spray pattern and improving the neatness of the sprayed edges.

[0025] This invention employs feedforward control for rapid response to changes in the flow setpoint, while simultaneously using actual flow feedback for dynamic correction. This eliminates the impact of factors such as changes in coating viscosity and fluctuations in pipeline resistance on the actual flow rate, significantly improving the control accuracy of the coating flow. Furthermore, by monitoring the inlet and outlet pressures of the gear pump in real time, it can promptly detect abnormal operating conditions such as material shortages and pipe blockages, and automatically shut down for protection, preventing equipment damage and safety accidents.

[0026] This invention, based on monitoring the status of a high-voltage generator via communication, adds a safety relay controlled by a digital output module. This relay is connected in series in the high-voltage generator's drive power supply circuit. When a system malfunctions or experiences an emergency stop, it not only sends a shutdown command via communication but also physically disconnects the high-voltage drive power supply via the relay. Even if the communication link fails, the high-voltage power supply can be reliably cut off, preventing injury to personnel from high-voltage static electricity and significantly improving safety.

[0027] When the rotation speed of the rotary cup changes, the invention automatically adjusts the set values ​​of the molding air flow and the paint flow to ensure that the three always maintain the optimal matching relationship. This avoids spraying defects such as uneven film thickness and orange peel caused by changes in a single parameter, and ensures that uniform and stable spraying quality can still be obtained under varying working conditions.

[0028] This invention categorizes faults into three levels: minor, moderate, and severe. Minor faults only trigger an alarm and do not affect operation, avoiding frequent downtime that could impact production efficiency. Moderate faults result in the system automatically attempting to adjust parameters for repair. Severe faults trigger an immediate safety shutdown protection mechanism. This tiered handling mechanism ensures both production continuity and the safety of equipment and personnel, while also enabling rapid fault location and significantly reducing troubleshooting time. Attached Figure Description

[0029] Figure 1 Modular spray coating control system functional zoning diagram; Figure 2 : Block diagram of modular spraying control system; Figure 3 Flowchart of closed-loop control of rotary cup speed; Figure 4 Flowchart of closed-loop control for molding air; Figure 5 High-voltage control flowchart; Figure 6 Flow control flowchart. Detailed Implementation

[0030] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0031] In the description of this application, it should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. For ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0032] It should be noted that the terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and are not limited in number; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0033] It should be noted that in the description of this application, the directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this application. The directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0034] It should be noted that, in this application, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. Furthermore, it should be noted that the scope of the methods and apparatuses in the embodiments of this application is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.

[0035] like Figures 1-6 As shown: Example 1: Hardware Architecture of Modular Spraying Control System The modular spraying control system provided in this embodiment adopts a distributed modular structure, with a central control module as the core. All modules are connected through standardized interfaces, supporting online plug-and-play expansion.

[0036] The central control module uses an industrial-grade programmable logic controller (PLC, such as the Siemens S7-1500 series) as the control core of the entire system, responsible for coordinating the work of various functional modules, executing control algorithms, and processing data interaction. Industrial-grade PLCs possess high reliability and strong anti-interference capabilities, enabling stable operation in the high-temperature, high-dust, and strong electromagnetic interference environment of a painting workshop. Furthermore, they support multi-protocol communication, allowing compatibility with slave modules from different brands, thus solving the problems of poor compatibility and high expansion costs associated with traditional dedicated controllers.

[0037] The specific configurations and connections of each module are as follows: The first communication module (corresponding to communication module #1 in the attached diagram): is a PROFINET Ethernet communication module used to connect to the host computer (industrial control computer) and receive different painting process parameter settings for different vehicle models from the host computer, including rotary cup speed, forming air flow rate, paint flow rate, high voltage, etc. It can also feed back system operating status data to the host computer. By sending parameters via communication with the host computer, it can flexibly adapt to the painting process requirements of different vehicle models, eliminating the need for manual modification of controller parameters on-site, and reducing changeover time from 30 minutes in traditional systems to 5 minutes.

[0038] The first analog-to-digital conversion module (corresponding to Module 1 in the attached diagram) is a 4-channel 4-20mA analog input module used to receive analog process parameters input via external hardwire, serving as a redundant backup for the first communication module. When the communication link fails, key parameters can be input via hardwire to ensure continued system operation. This dual-channel parameter input design not only satisfies the flexibility of digital parameter distribution but also enhances the system's fault tolerance through hardwire backup, preventing production stoppages due to communication failures and improving production continuity by over 90%.

[0039] Digital input module (corresponding to the digital input module in the attached diagram): This is a 16-channel 24VDC digital input module used to receive external hardwired switch control signals, including system enable signals, fault reset signals, emergency stop signals, and workpiece position signals. Employing hardwired input of critical safety signals, the response time can be controlled to within 1ms, far faster than the transmission delay of communication signals. This ensures immediate response to safety commands such as emergency stops, protecting personnel and equipment safety.

[0040] Analog output module (corresponding to the digital-to-analog converter module in the attached diagram): This is a 4-channel 0-10V analog output module. Its output terminals are connected to the control input terminals of the drive air proportional valve and the forming air proportional valve, respectively. It outputs 0-10V analog control signals to adjust the valve opening, thereby controlling the drive air pressure and forming air flow of the rotary cup. The analog output enables stepless adjustment of the valve opening with an adjustment accuracy of up to 0.1%. Compared with the step-wise adjustment of traditional on / off control, it can significantly improve the accuracy of air flow control and provide hardware support for the stability of the rotary cup atomization effect.

[0041] The high-voltage communication module (corresponding to communication module #2 in the attached diagram) is a CANopen communication module. It connects to the high-voltage generator via a CAN bus and is used to send voltage setpoints (0-100kV) to the generator while simultaneously receiving feedback data such as the generator's operating status, fault codes, and actual output voltage. Compared to traditional analog control, CAN bus communication enables bidirectional interaction of high-voltage parameters. It can both send setpoints and monitor the generator's status in real time, facilitating timely detection of high-voltage anomalies. Furthermore, the CAN bus has strong anti-interference capabilities, making it suitable for stable data transmission in high-voltage electrostatic environments.

[0042] The motor communication module (corresponding to communication module #3 in the attached diagram) is an RS485 communication module that connects to the servo motor controller of the gear pump via the Modbus RTU protocol. It is used to send motor speed setpoints and receive data such as actual motor speed, torque, and fault status. Compared to traditional analog control, communication-based motor control enables more precise speed regulation and allows for real-time acquisition of motor operating status, facilitating fault diagnosis and preventative maintenance.

[0043] The data acquisition module (corresponding to analog-to-digital converter module 2 in the attached diagram) is an 8-channel 16-bit analog-to-digital converter module, whose input terminals are connected to the following sensors: Fiber optic amplifier: Installed on the side of the rotary cup air flotation motor, it is used to collect the pulse signal generated by the motor rotation. The central control module calculates the actual rotation speed of the rotary cup based on the pulse frequency. Pressure sensors: installed on the inlet and outlet pipes of the gear pump respectively, used to detect the paint supply pressure and the pump outlet pressure; Air flow meter: Installed on the forming air pipeline, used to detect the actual forming air flow rate; Paint flow sensor: Installed on the outlet pipe of the gear pump, used to detect the actual amount of paint dispensed.

[0044] The collaborative acquisition of multiple types of sensors can obtain all key parameters of the spraying process in real time, providing accurate data support for closed-loop control. The 16-bit acquisition accuracy can improve the signal resolution to 0.01%, ensuring the accuracy of feedback data and thus improving the accuracy of closed-loop control.

[0045] Digital output module (corresponding to the digital output module in the attached diagram): This is an 8-channel relay output module. One of the output channels is connected to the coil of a safety relay. The normally open contact of this safety relay is connected in series in the 220V drive power supply circuit of the high-voltage generator to physically cut off the high-voltage power supply in case of fault or emergency stop.

[0046] The actuators include a rotary cup driven by an air-bearing motor and a gear pump driven by a servo motor. The output of the analog output module is connected to the air inlet of the air-bearing motor via a drive air proportional valve and to the forming air nozzle of the rotary cup via a forming air proportional valve. Compared to traditional electric rotary cups, the air-bearing motor-driven rotary cup eliminates mechanical contact wear, achieves a maximum speed of 60,000 rpm, and features lower operating noise and a longer lifespan, making it suitable for high-precision spraying requirements. The servo motor-driven gear pump ensures precise delivery of paint flow, with flow fluctuations controlled within ±1%, guaranteeing stable paint supply.

[0047] All modules adopt a DIN rail-mounted, pluggable design and connect to the central control module via standardized PROFINET, CAN, and RS485 interfaces. When a module fails, it can be replaced online without requiring the entire system to be re-tuned. Maintenance time can be reduced from over 4 hours in traditional integrated systems to less than 30 minutes. Furthermore, functional modules can be flexibly added or removed according to different painting process requirements, reducing expansion costs by over 70% compared to traditional systems.

[0048] Example 2: The function block programming and modular control logic are as follows: In this embodiment, the control program within the central control module is written using Function Block Diagram (FBD) programming. All control logic is broken down into independent functional blocks, including high-pressure control, speed control, molding air control, paint flow control, and alarm diagnostic blocks. These functional blocks interact through standardized data interfaces and can be flexibly combined and called according to different painting process requirements (such as body topcoat painting, bumper primer / color paint / clear coat painting, and powder coating). The function block programming design ensures that modifications to the control logic do not require changes to the entire program architecture. When adapting to new painting processes, only the parameters or combinations of the corresponding functional blocks need to be adjusted. The program development cycle can be shortened from the traditional two weeks to three days. Furthermore, each functional block operates independently; an anomaly in one functional block will not affect the normal operation of other functional blocks, improving the system's fault tolerance.

[0049] Example 3: The specific implementations of each core control function block are as follows: Speed ​​control function block: This function block implements three-stage control of the rotating cup speed, including the rapid speed increase stage, the stable speed operation stage, and the rotating cup deceleration stage. Rapid Lifting Phase: Upon receiving the start command, the analog output module outputs a maximum voltage of 8V to the drive air proportional valve, and the rotary cup rapidly lifts to 80% of the target speed within 2 seconds; During stable operation: A multi-segment stepped PID control method is adopted. The central control module calls the PID parameter group corresponding to the different speed ranges of the actual feedback speed of the rotor collected by the data acquisition module for closed-loop adjustment. The specific range division is as follows: First range: speed < 5000 rpm, using the first set of PID parameters (Kp=2.0, Ki=0.5, Kd=0.1). Second range: 5000rpm≤speed<10000rpm, using the second set of PID parameters (Kp=1.5, Ki=0.3, Kd=0.05). The third range is 10000rpm ≤ speed < 30000rpm, using the third set of PID parameters (Kp=1.0, Ki=0.2, Kd=0.02). The fourth range is 30,000 rpm ≤ speed < 50,000 rpm, using the fourth set of PID parameters (Kp=0.8, Ki=0.15, Kd=0.01). Fifth range: speed ≥ 50000rpm, using the fifth group of PID parameters (Kp=0.5, Ki=0.1, Kd=0.005). Deceleration phase: After the spraying is completed, the analog output module outputs a low voltage of 1V, and the rotary cup decelerates to below 1000rpm within 3 seconds and then stops.

[0050] Traditional single PID parameters cannot adapt to the differences in dynamic characteristics of the rotary cup at different speeds. At low speeds, the friction force of the air-bearing motor accounts for a large proportion, requiring a larger proportional coefficient to improve the response speed. At high speeds, air resistance accounts for a large proportion, requiring a smaller proportional coefficient to avoid overshoot. By adopting multi-stage stepped PID control, the rotary cup speed fluctuation can be reduced from ±500rpm in traditional control to ±3rpm, improving the speed control accuracy by more than 99%. This effectively avoids the problem of uneven paint atomization caused by speed fluctuations, and reduces the coating film thickness deviation from ±8μm to ±5μm, significantly improving the coating quality.

[0051] Forming air control function block: This function block adopts a range-based proportional coefficient closed-loop control method. The central control module calls the proportional coefficient corresponding to the different flow ranges of the forming air flow setpoint, and adjusts the output voltage of the forming air proportional valve through the analog output module to achieve closed-loop regulation. The specific range division is as follows: First range: Flow rate setting < 60L / min (corresponding to fine spraying scenarios for small-diameter rotary cups), Kp=1.2, Ki=0.005, Kd=0.01; Second range: 60L / min ≤ flow rate setpoint ≤ 180L / min (corresponding to the conventional spraying scenario of medium-diameter rotary cup), Kp=0.8, Ki=0.005, Kd=0.01; Third range: Flow rate setting value > 180L / min (corresponding to high flow rate spraying scenarios with large-diameter rotary cups), Kp=0.5, Ki=0.005, Kd=0.01.

[0052] Different diameter rotary cups have significantly different requirements for the flow rate of the forming air. Small-diameter rotary cups have high flow rate adjustment sensitivity and require a larger proportional coefficient to improve adjustment accuracy. Large-diameter rotary cups have large flow rate inertia and require a smaller proportional coefficient to avoid oscillation. By adopting interval proportional coefficient control, the fluctuation of the forming air flow rate can be reduced from ±15L / min in traditional control to ±5L / min, improving the flow rate control accuracy by more than 66%. This adapts to the atomization requirements of rotary cups of different diameters, effectively avoiding the problem of unstable spray pattern caused by the fluctuation of forming air, and improving the neatness of the spray edge by more than 40%.

[0053] Paint Flow Control Function Block: This function block implements closed-loop control with flow feedforward and feedback. The paint flow rate setpoint (0-500ml / min) is linearly converted into the motor speed setpoint (0-3000rpm), and sent to the servo motor controller via the motor communication module to drive the gear pump. The actual flow rate feedback of the paint flow sensor is collected every 10ms through the data acquisition module. If the actual flow rate deviates from the set value by more than ±2%, the motor speed setting value is adjusted by 60% of the deviation until the flow rate stabilizes. The real-time monitoring data acquisition module collects data from the inlet and outlet pressure sensors of the gear pump. If the inlet pressure is lower than 0.2MPa (indicating a lack of material) or the outlet pressure is higher than 1.5MPa (indicating a blockage), the motor will be stopped immediately and a fault alarm will be output.

[0054] The feedforward + feedback closed-loop control method can quickly respond to changes in the flow setpoint through feedforward and correct deviations in the actual flow through feedback, improving the accuracy of paint flow control from ±10% in traditional open-loop control to ±1%. At the same time, the pressure protection mechanism can detect abnormalities such as pipeline blockage and material shortage in a timely manner, avoiding safety accidents such as gear pump dry running damage or pipeline rupture, reducing the equipment failure rate by more than 60%.

[0055] High-voltage control function block: This function block interacts with the high-voltage generator via a high-voltage communication module, sending voltage setpoints (0-100kV) and receiving the generator's operating status information. Simultaneously, it controls a safety relay connected in series in the generator's drive power supply circuit via a digital output module: when the system is in normal operation, the relay is closed to supply power; when a fault signal from the high-voltage generator or a system emergency stop signal is received, the relay is immediately opened, physically cutting off the high-voltage drive power supply. This dual safety mechanism design monitors the high-voltage generator's status in real time via communication and physically cuts off the power supply via relays. Even if the communication link fails, the high-voltage power supply can be cut off through a hard-wired safety circuit, preventing injury from high-voltage static electricity. The safety level meets the PLd level requirements of ISO 13849-1.

[0056] Alarm and Diagnostic Function Block: This function block monitors the operating status of all modules in real time and classifies faults into three levels for handling: Level 1 fault (minor): The sensor signal fluctuation exceeds the threshold but does not exceed the range. For example, if the speed signal collected by the data acquisition module fluctuates by more than 100 rpm, the system will output an alarm prompt, which will not affect the operation. Level 2 fault (moderate): The control deviation exceeds the allowable range. For example, if the actual speed deviates from the set value by more than 500 rpm for 5 seconds, the system will automatically switch PID parameters to attempt adjustment and output an alarm. Level 3 fault (serious): Safety-related faults, such as high-voltage generator failure, excessively high gear pump outlet pressure, or receiving an emergency stop signal from the digital input module. The system immediately cuts off the high-voltage relay through the digital output module, stops all actuators, latches the fault code, and must be manually reset to restart.

[0057] The graded fault handling mechanism not only avoids frequent downtime caused by minor faults that affect production efficiency, but also ensures safety protection in the event of serious faults. The fault diagnosis time is shortened from more than 2 hours of manual troubleshooting in traditional systems to less than 10 minutes, and the overall utilization rate of equipment is increased by more than 25%.

[0058] Example 4: The control method provided in this embodiment is based on the above system, and the specific steps are as follows: Step S1: System Initialization: After the central control module is powered on, it scans all slave modules via the PROFINET bus, reading the module's hardware ID, firmware version, and online status. Simultaneously, it reads the status word of the high-voltage generator via the high-voltage communication module and the status word of the motor controller via the motor communication module. After confirming that all modules are communicating normally and without faults, the system enters standby mode. It automatically identifies the functions of connected modules, eliminating the need for manual configuration of module parameters. Initialization time is reduced from 30 minutes in traditional systems to 5 minutes, lowering the operational difficulty for operators.

[0059] Step S2: Receive painting parameters: The host computer sends the painting parameters of the current vehicle model through the first communication module, including the rotary cup speed setting value of 40000rpm, the forming air flow setting value of 120L / min, the paint flow setting value of 300ml / min, and the high voltage setting value of 80kV. At the same time, it outputs the system enable signal through the digital input module.

[0060] Step S3: Start-up of Execution Components: The central control module starts the execution components according to a preset timing sequence: First, the digital output module opens the air source solenoid valve, and the analog output module outputs 2V voltage to the drive air proportional valve, causing the rotary cup to accelerate; simultaneously, the analog output module outputs 0.8V voltage to the forming air proportional valve to pre-open the forming air; a motor speed setting of 1800rpm is sent to the servo motor controller via the motor communication module, and the gear pump starts supplying paint; an 80kV high voltage setting is sent to the high voltage generator via the high voltage communication module, starting the electrostatic high voltage. This preset timing sequence avoids current surges caused by simultaneous startup of all execution components, and ensures synchronized matching of paint supply, atomization, and high-voltage electrostatic discharge, preventing spraying defects during the startup phase.

[0061] Step S4: Real-time Data Acquisition: The data acquisition module acquires feedback signals from each sensor every 10ms, including the actual rotational speed of the rotary cup acquired through the fiber optic amplifier, the actual forming air flow rate acquired through the air flow meter, the actual paint flow rate acquired through the paint flow sensor, and the inlet and outlet pressures of the gear pump acquired through the pressure sensor. The 10ms acquisition cycle meets the real-time control requirements of the high-speed spraying process, ensuring the timeliness of feedback data and providing reliable data support for closed-loop control.

[0062] Step S5: Closed-loop regulation and linkage control: The speed control function block determines that the actual speed acquired by the data acquisition module is in the range of 30,000-50,000 rpm, calls the fourth group of PID parameters, calculates the voltage output by the analog output module to the drive air proportional valve and adjusts it to 4.2V, so that the speed is stabilized at 40,000±3 rpm. The forming air control function block determines that the set value of 120L / min is in the range of 60-180L / min, calls the proportional coefficient Kp=0.8, and adjusts the output voltage to 1.1V through the analog output module to stabilize the actual flow rate collected by the data acquisition module at 120±5L / min; The paint flow control function block judges that the actual flow rate collected by the data acquisition module is 295ml / min, which is 1.7% lower than the set value. The motor speed is increased to 1850rpm through the motor communication module to stabilize the flow rate at 300±3ml / min. Linkage adjustment logic: When the rotation speed of the rotary cup changes by more than 5000 rpm, the set values ​​of the forming air and coating flow rate are automatically adjusted. For example, if the rotation speed increases from 40000 rpm to 50000 rpm (an increase of 25%), the setting value of the forming air will automatically increase by 20% to 144 L / min, and the setting value of the coating flow rate will automatically increase by 12% to 336 ml / min to ensure the uniformity of the sprayed film thickness.

[0063] The linkage adjustment ensures that the matching relationship between the rotation speed, atomized air, and paint flow rate is always in the optimal state, avoiding spraying defects such as uneven film thickness and orange peel caused by changes in a single parameter. The overall vehicle spraying film thickness deviation is reduced from ±8μm to ±5μm, and the first-pass coating qualification rate is increased from 85% to over 98%.

[0064] Step S6: Shutdown Procedure: After spraying is completed, the following components are stopped according to the preset sequence: First, the paint flow is shut off, and the motor speed is reduced to 0 via the motor communication module; then, the analog output module outputs a 0.5V low voltage, and after the rotary cup speed is reduced to below 1000rpm, the drive air solenoid valve is closed via the digital output module; the cleaning solenoid valve is opened via the digital output module to clean the rotary cup and pipeline; finally, the high-voltage relay is disconnected via the digital output module to cut off the high-voltage power supply, and the system returns to standby mode. The preset shutdown sequence avoids paint drying and clogging caused by stopping paint supply when the rotary cup rotates at high speed. The cleaning procedure ensures that residual paint in the pipeline is cleaned thoroughly, avoiding color mixing problems when switching between different paint colors.

[0065] Example 5: This embodiment illustrates the modular expansion capability of the system: If applied to powder coating scenarios, the paint flow sensor connected to the paint flow control function block and data acquisition module can be removed, and a powder flow control function block and powder flow meter can be added, while other modules remain unchanged. The expansion cost is only 10% of the original system. If applied to multi-color spraying scenarios, a color-changing valve control function block and multiple color-changing solenoid valves (driven by digital output modules) can be added to realize automatic switching of different color paints, reducing the color-changing time from 15 minutes in the traditional system to 5 minutes. If remote monitoring functionality is required, a 4G communication module can be added to upload operational data to a cloud server, enabling remote fault diagnosis and production data statistics.

[0066] Modular design allows the system to be flexibly adapted to different spraying scenarios without the need to redevelop the entire control system. The adaptation cycle for new scenarios is shortened from the traditional 3 months to 1 week, significantly reducing the equipment modification costs for enterprises.

[0067] The embodiments of this application have been described above with reference to the accompanying drawings. Unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other. This application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. A modular spraying control system, characterized in that, include: The central control module is used to receive input commands, coordinate and control the work of other modules, and execute the spraying operation. The parameter input module is connected to the central control module and is used to receive external spraying process parameter settings. The signal input module is connected to the central control module and is used to receive external switch control signals; An analog output module, connected to the central control module, is used to output analog control signals; A high-voltage communication module, connected to the central control module, is used for data exchange with the high-voltage generator; The motor communication module is connected to the central control module and is used for data exchange with the motor controller; The data acquisition module is connected to the central control module and is used to acquire feedback signals from the spraying process. The rotary cup's rotation speed is controlled by driving air, and its spray shape is controlled by forming air. Gear pumps, driven by electric motors, are used to deliver paint; The analog output module is connected to a drive air proportional valve for controlling the rotation speed of the rotary cup and a forming air proportional valve for controlling the spraying shape of the rotary cup. The data acquisition module is connected to a speed sensor for detecting the rotation speed of the rotary cup, an air flow meter for detecting the forming air flow, and a paint flow sensor for detecting the paint flow. The central control module controls the drive air proportional valve, the forming air proportional valve, and the motor controller to achieve closed-loop control of the rotary cup rotation speed, spraying shape, and paint flow.

2. The system according to claim 1, characterized in that, The central control module is pre-programmed with a control program written using function block programming. The control program includes independent high-pressure control function blocks, speed control function blocks, forming air control function blocks, paint flow control function blocks, and alarm diagnosis function blocks. The central control module is configured to selectively call and combine the above function blocks according to different spraying process requirements.

3. The system according to claim 1, characterized in that, The parameter input module includes a first communication module for communicating with a host computer and / or a first analog-to-digital conversion module for receiving external analog signals; the signal input module is a digital input module.

4. The system according to claim 2, characterized in that, The speed control function block is configured to execute a multi-stage stepped PID control method; The central control module calls the PID parameter group corresponding to the different speed ranges of the rotating cup's set speed or actual feedback value to perform closed-loop regulation.

5. The system according to claim 2, characterized in that, The molding air control function block is configured to execute an interval proportional coefficient control method; The central control module uses a proportional coefficient corresponding to the set flow rate of the forming air to perform closed-loop adjustment based on the different flow rate ranges.

6. The system according to claim 1, characterized in that, It also includes digital output modules and relays; The digital output module is connected to the central control module, and its output terminal controls the on / off state of the relay; The relay is connected in series in the drive power circuit of the high-voltage generator. When a fault or emergency stop signal is received, the central control module controls it to disconnect to cut off the drive power of the high-voltage generator.

7. The system according to claim 2, characterized in that, The paint flow control function block is configured as follows: The paint flow rate setpoint is converted into a motor speed setpoint and sent to the motor controller to drive the gear pump. Simultaneously, it receives actual flow feedback from the paint flow sensor and dynamically adjusts the motor speed setpoint. It also monitors the pressure at the inlet and outlet of the gear pump, and controls the gear pump to stop running when the pressure is abnormal.

8. A modular spraying control method based on the system according to any one of claims 1-7, characterized in that, Includes the following steps: S1: System initialization, the central control module identifies the connected functional modules; S2: Receives spraying parameter settings and control commands; S3: The central control module starts the rotary cup and gear pump according to the instructions; S4: Real-time acquisition of feedback signals for rotary cup rotation speed, molding air flow rate, and coating flow rate; S5: The central control module dynamically adjusts the output of the drive air proportional valve and the forming air proportional valve based on the deviation between the feedback signal and the set value, using segmented PID control algorithm and interval proportional coefficient control algorithm respectively, to achieve closed-loop control. S6: After the spraying is completed, execute the shutdown procedure.

9. The method according to claim 8, characterized in that, Step S5 also includes a linkage adjustment step: When the rotation speed of the rotary cup changes, the set values ​​of the forming air flow and coating flow are adjusted synchronously to maintain the stability of the sprayed film thickness.

10. The method according to claim 8, characterized in that, It also includes fault diagnosis and handling steps: Each functional block module monitors the hardware status in real time and reports it to the central control module; The central control module analyzes abnormal states and determines the fault level; If the fault is minor, an alarm will be triggered; if the fault is serious, an automatic shutdown or adaptive adjustment strategy will be implemented.

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