Automatic dosing system applied to pretreatment of automobile coating workshop

Abstract

The invention discloses an automatic chemical adding system applied to pretreatment of an automobile coating workshop, the automatic chemical adding system comprises a chemical storage unit, the chemical storage unit comprises a plurality of chemical storage barrels and stirring assemblies arranged in the chemical storage barrels, and weighing modules are arranged at the bottoms of the chemical storage barrels; the metering and adding unit is connected with the medicine storage unit, the metering and adding unit comprises a treatment tank, a first-stage filter is connected below the treatment tank, and a second-stage filter is connected below the first-stage filter; one end of the secondary filter is connected to the top of the mixed reaction unit, and the mixed reaction unit comprises a reaction tank and a reagent group connected with the reaction tank; the central controller is electrically connected with a plurality of analyzers, and the central controller is used for controlling the dosage of the reagent group and the medicine storage unit; the flowmeter and the density sensor are combined for metering, the mass flow of the medicament is directly measured, and the influence of temperature and viscosity on the metering precision is eliminated; meanwhile, the dosing strategy is corrected in real time through a medicine storage barrel weighing module and a reaction tank concentration sensor.

Description

Technical Field

[0001] The present invention relates to the technical field of automotive painting, and particularly relates to an automatic chemical dosing system applied to the pretreatment in an automotive painting workshop. Background Art

[0002] In the automotive manufacturing process, pretreatment before painting is a key link determining the quality of the body paint film. Its core objective is to remove grease, rust and impurities on the body surface through chemical treatment and form a base film layer (such as a phosphating film) conducive to the adhesion of the paint. The pretreatment process usually includes steps such as degreasing, water washing, surface conditioning, phosphating, passivation, etc. Specific chemicals are required for each step, and parameters such as chemical concentration, temperature, pH value, etc. directly affect the treatment effect. For example:

[0003] Degreasing process: The concentration of the degreaser (mainly composed of alkaline surfactants) needs to be controlled at 5% - 10%. Insufficient concentration will result in oil residue, while excessive concentration will increase the cleaning difficulty and cost;

[0004] Phosphating process: The free acidity, total acidity, and zinc ion concentration of the phosphating solution (containing zinc phosphate, accelerator, etc.) need to be strictly controlled to form a uniform and dense phosphating film, which directly affects the adhesion and corrosion resistance of the subsequent paint film.

[0005] Traditional methods for dosing in pretreatment mainly include the following:

[0006] 1. Manual chemical dosing

[0007] Manually carry the barreled chemicals to the chemical storage tank, estimate the dosing amount based on experience or a simple level gauge, and manually open the valve to inject into the reaction tank. The advantages of this method are low initial equipment cost and suitability for small-scale production lines; however, it has significant disadvantages: poor metering accuracy (error can reach ±15%), relying on the experience of operators; high labor intensity, frequent handling of heavy chemical barrels (the weight of a single barrel is usually ≥20 kg); low safety, as the chemicals are highly corrosive (such as concentrated phosphoric acid, sodium hydroxide), prone to leakage or contact injuries; unable to respond to changes in working conditions in real time. For example, when the production line speed suddenly increases, the dosing amount cannot be adjusted in time according to the change in the chemical consumption rate.

[0008] 2. Semi-automatic chemical dosing (relay control + simple metering pump)

[0009] Use an electromagnetic diaphragm pump or a plunger pump as the dosing power, estimate the dosing amount by controlling the running time of the pump through a time relay, and cooperate with single-point sensors such as a pH meter and a conductivity meter to monitor the parameters of the reaction tank. This method is an improvement over manual dosing, but still has the following problems:

[0010] Open-loop control defect: The dosing is only based on a fixed time interval, and a "monitoring - feedback - adjustment" closed-loop is not formed. For example, when the change in water quality hardness causes fluctuations in the consumption rate of phosphating solution, the dosing amount cannot be automatically corrected.

[0011] Single and lagging sensors: Only the parameters at the end of the reaction tank are monitored, and the intermediate links such as the liquid level of the chemical storage tank, the temperature of the chemical agent, and the pipeline pressure are not monitored, making it difficult to troubleshoot faults.

[0012] Poor compatibility: It operates independently from the production line control system (such as PLC), and key data such as the production line speed and the number of workpieces processed cannot be obtained in real time, resulting in a rigid dosing strategy. Summary of the Invention

[0013] The purpose of the present invention is to provide an automatic chemical dosing system applied to the pretreatment of an automotive painting workshop to solve the problems in the prior art.

[0014] To achieve the above object, a technical solution adopted by the present invention is: An automatic chemical dosing system applied to the pretreatment of an automotive painting workshop, comprising:

[0015] A chemical storage unit, the chemical storage unit includes a plurality of chemical storage tanks and a stirring assembly arranged inside the chemical storage tanks, and a weighing module is arranged at the bottom of the chemical storage tanks;

[0016] A metering and dosing unit, the metering and dosing unit is connected to the chemical storage unit, the metering and dosing unit includes a treatment tank, a primary filter is connected below the treatment tank, and a secondary filter is connected below the primary filter;

[0017] A mixing and reaction unit, one end of the secondary filter is connected to the top of the mixing and reaction unit, the mixing and reaction unit includes a reaction tank and a reagent group connected to the reaction tank;

[0018] A central controller, the central controller is electrically connected to a plurality of analyzers, and the central controller is used to control the dosing amounts of the reagent group and the chemical storage unit.

[0019] Preferably, a plurality of the chemical storage tanks are respectively a degreasing agent tank, a surface conditioner tank, a phosphating agent tank, and a promoter tank. A metering pump is arranged at the top of any one of the chemical storage tanks. One end of the metering pump is connected to a check valve, one end of the check valve is connected to a flow meter, one end of the flow meter is connected to a ball valve, and one end of the ball valve is connected above the treatment tank.

[0020] Preferably, a calibration cylinder is arranged on one side of any one of the chemical storage tanks, and a liquid level gauge is arranged on the other side.

[0021] Preferably, in one solution, the stirring assembly includes a stirring motor fixedly installed on the top of the medicine storage barrel. The shaft end of the stirring motor is connected to a stirring shaft. The stirring shaft is inserted into the interior of the medicine storage barrel. The bottom end of the stirring shaft is hinged with a stirring head, and the stirring head is of a fan blade structure.

[0022] Preferably, in one solution, the primary filter is provided with a 40μm - 60μm stainless steel filter mesh, the secondary filter is provided with a 5μm - 15μm sintered metal filter element. A peristaltic pump is arranged between the primary filter and the secondary filter. One end of the secondary filter is connected to an automatic valve, and a peristaltic pump is arranged between the automatic valve and the mixing reaction unit.

[0023] Preferably, in one solution, a PH electrode is arranged in the reaction tank, and a vacuum pump is arranged at the bottom of the reaction tank. One end of the vacuum pump is connected to a waste water tank.

[0024] Preferably, in one solution, the reagent group includes a PH buffer tank, a cleaning agent tank, a pure water tank, a standard solution tank and a hydrochloric acid reagent tank arranged side by side. The PH buffer tank, the cleaning agent tank, the pure water tank, the standard solution tank and the hydrochloric acid reagent tank are all connected to the reaction tank through peristaltic pumps. A liquid level gauge is arranged on one side of the PH buffer tank, the cleaning agent tank, the pure water tank, the standard solution tank and the hydrochloric acid reagent tank.

[0025] Preferably, in one solution, multiple analyzers include a first analyzer, a second analyzer and a third analyzer. The first analyzer is a PH analyzer. The second analyzer is used to detect and analyze the free acid, total acid and promotion point in the reaction tank. The third analyzer is used to detect and analyze the free base and total base in the reaction tank.

[0026] Preferably, in one solution, the central controller is electrically connected to a data acquisition unit, a model analysis unit, an execution control unit and a feedback correction unit. The data acquisition unit obtains the weight, density and temperature of the medicine in the medicine storage unit;

[0027] The data acquisition unit obtains the mass flow, pipeline pressure and pump motor current of the metering and dosing unit; The data acquisition unit obtains the concentration, pH, conductivity, volume, production line speed and workpiece type in the mixing reaction unit;

[0028] The model analysis unit calls the corresponding formula according to the workpiece type and calculates the theoretical medicine demand;

[0029] The execution control unit drives the metering pump to control the quantitative dosing of the degreasing agent medicine barrel, the surface conditioner medicine barrel, the phosphating agent medicine barrel and the accelerator medicine barrel, and controls the operation of the stirring motor to uniformly mix the medicine;

[0030] The feedback correction unit compares the concentration value in the mixing reaction unit with the target value to obtain a concentration difference. If the concentration difference is greater than the set concentration difference threshold, the dosing amount of the degreasing agent, surface conditioner, phosphating agent or accelerator is adjusted.

[0031] Preferably, in one solution, the central controller is built-in with a control algorithm library, and the control algorithm library includes a main control algorithm and a self-learning model: the main control algorithm is a multi-variable coupling control algorithm based on fuzzy PID. The input parameters of the multi-variable coupling control algorithm based on fuzzy PID include the production line speed, workpiece surface area, current concentration in the reaction tank, and temperature, and the outputs are the metering pump speed and agitator frequency.

[0032] The self-learning model is an LSTM neural network model, and the LSTM neural network model is used to predict the chemical consumption rate under different working conditions and adjust the dosing strategy.

[0033] Due to the application of the above technical solutions, the beneficial effects of this application compared with the prior art are as follows:

[0034] 1. Full-process precise metering and dynamic compensation

[0035] Combined metering of a flow meter and a density sensor is adopted to directly measure the mass flow rate of the chemical, eliminating the influence of temperature and viscosity on the metering accuracy, and the accuracy can reach ±0.5%; at the same time, through the weighing module of the chemical storage tank and the concentration sensor of the reaction tank, the dosing strategy is corrected in real time.

[0036] 2. Multi-variable adaptive control and intelligent decision-making

[0037] Based on the mathematical model of the pretreatment process, integrating PLC real-time data (production line speed, workpiece type), sensor data (temperature, pH, conductivity) and historical database, the dosing amount is automatically adjusted through the fuzzy PID algorithm.

[0038] 3. Full-system status monitoring and fault self-healing

[0039] Deploy a multi-level sensor network (chemical storage tank liquid level / weight / temperature, pipeline pressure / flow, pump body vibration / current) to achieve full-process monitoring from chemical storage to the dosing end;

[0040] Built-in fault diagnosis algorithm, automatically identify abnormalities such as insufficient chemicals, pipeline blockage, pump body failure, etc., trigger early warnings and execute emergency handling (such as switching to a standby pump, starting a pipeline cleaning program).

[0041] 4. Human-machine collaboration and remote operation and maintenance integration

[0042] Develop an interactive HMI interface, integrate functions such as trend analysis, energy consumption statistics, and formula management, and support touch screen operation and gesture control;

[0043] Equipped with a 5G / industrial Ethernet communication module, it conducts real-time data interaction with the factory MES system and cloud platform to achieve remote parameter configuration, fault diagnosis, and big data analysis.

[0044] 5. Anti-corrosion design and modular easy-maintenance structure

[0045] The medicine storage bucket, pipelines, and valves are made of acid- and alkali-resistant materials (such as 316L stainless steel, PP-H, PVDF), and the surfaces of key components are sprayed with a polytetrafluoroethylene (PTFE) coating, with the service life extended to more than 5 years.

[0046] Quick-release joints and drawer-type sensor mounting brackets are adopted, and component replacement can be completed within 30 minutes during maintenance without shutting down the power supply. Description of the drawings

[0047] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art.

[0048] Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0049] Figure 1 It is a block diagram of the automatic dosing system applied to the pretreatment of the automotive painting workshop of the present invention.

[0050] Figure 2 It is a control block diagram of the automatic dosing system applied to the pretreatment of the automotive painting workshop of the present invention.

[0051] Figure 3 It is a schematic structural diagram of the medicine storage bucket of the automatic dosing system applied to the pretreatment of the automotive painting workshop of the present invention.

[0052] 1. Processing tank, 2. Primary filter, 3. Peristaltic pump, 4. Secondary filter, 5. Automatic valve, 6. Vacuum pump, 7. First analyzer, 8. Third analyzer, 9. Second analyzer, 10. Central controller, 11. Reaction tank, 12. PH electrode, 13. PH buffer tank, 14. Cleaning agent tank, 15. Liquid level gauge, 16. Waste water tank, 17. Pure water tank, 18. Standard solution tank, 19. Hydrochloric acid reagent tank, 20. Degreasing agent drum, 21. Surface conditioner drum, 22. Phosphating agent drum, 23. Accelerator drum, 24. Standard measuring cylinder, 25. Metering pump, 26. Check valve, 27. Flow meter, 28. Ball valve, 29. Data acquisition unit, 30. Model analysis unit, 31. Execution control unit, 32. Feedback correction unit, 33. Stirring motor, 34. Stirring shaft, 35. Stirring head, 36. Discharge port, 37. Weighing module, 38. Chemical storage drum, 39. Filling port. Detailed implementation manners

[0053] In order to enable those skilled in the art of this technology to better understand the solution of this application, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of this application.

[0054] It should be noted that the terms "first", "second", etc. in the specification and claims of this application and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily need to be used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so as to implement the embodiments of this application described here. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device including a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0055] In this application, the orientation or positional relationship indicated by terms such as "upper", "lower", "left", "right", "front", "rear", "top", "bottom", "inner", "outer", "middle", "vertical", "horizontal", "lateral", "longitudinal", etc. is based on the orientation or positional relationship shown in the drawings. These terms are mainly used to better describe the present invention and its embodiments, and are not used to limit that the indicated devices, elements or components must have a specific orientation, or be constructed and operated in a specific orientation.

[0056] Moreover, in addition to being used to indicate orientation or positional relationship, some of the above terms may also be used to indicate other meanings. For example, the term "upper" may also be used to indicate a certain attachment relationship or connection relationship in some cases. For those of ordinary skill in the art, the specific meanings of these terms in the present invention can be understood according to specific circumstances.

[0057] In addition, the terms "install", "set", "provided with", "connect", "connected", "socketed" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or there is internal communication between two devices, components or parts. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0058] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0059] Embodiment 1

[0060] Figures 1 - 3 An automatic chemical dosing system for the pretreatment in an automotive painting workshop according to the present invention includes:

[0061] A chemical storage unit, which includes a plurality of chemical storage barrels 38 and a stirring assembly arranged inside the chemical storage barrel 38, and a weighing module 37 is arranged at the bottom of the chemical storage barrel 38;

[0062] Specifically, the chemical storage unit is used to store liquid chemicals such as degreasing agent, phosphating solution, surface conditioner, etc. It adopts a modular design, and a single chemical storage barrel 38 can operate independently or be used in combination.

[0063] The main body of the tank body of the chemical storage tank is made of 316L stainless steel (for acidic chemicals) or PP-H (for alkaline chemicals), the inner wall roughness Ra ≤ 0.8μm, reducing chemical residue and crystal adhesion; the capacity is 500L - 5000L, and a detachable thermal insulation layer (the thermal insulation material is glass wool, with a thickness of 50mm) is arranged outside to maintain the chemical temperature at 20°C ± 5°C (to avoid the influence of temperature fluctuation on the metering accuracy);

[0064] The weighing module 37 is 4 groups of high-precision pressure sensors (accuracy ±0.1% FS), which real-time monitors the chemical weight and calculates the volume in combination with a density sensor, solving the measurement error problem caused by chemical foam and evaporation of the traditional liquid level gauge 15;

[0065] The stirring assembly adopts a low-speed magnetic stirrer (rotation speed 50 - 100rpm), avoiding high-shear damage to the chemical components, and the surface of the stirring blades is coated with PTFE to prevent solid particles from adhering.

[0066] The ultrasonic liquid level switch sets high and low liquid level thresholds. When the weight of the chemical agent is lower than the lower limit (remaining amount 20%), it triggers an audible and visual alarm and automatically sends a replenishment request to the logistics system.

[0067] The leakage detection belt is laid along the perimeter of the bottom of the tank body. It uses a conductive polymer sensor to cut off the inlet / outlet valves within 0.5 seconds when liquid leakage is detected and starts the cofferdam drainage pump.

[0068] The metering and dosing unit is connected to the chemical agent storage unit. The metering and dosing unit includes treatment tank 1, and a primary filter 2 is connected below treatment tank 1, and a secondary filter 4 is connected below primary filter 2.

[0069] Specifically, the metering and dosing unit realizes the precise delivery of the chemical agent from the storage tank to reaction tank 11. The core components include:

[0070] Primary filter 2: A 50μm stainless steel filter screen to remove large particle impurities (such as packaging debris, crystal blocks) in the chemical agent.

[0071] Secondary filter 4: A 10μm sintered metal filter element, equipped with a self-cleaning mechanism (reverse pulse cleaning, with a settable cycle) to prevent the filter element from clogging and affecting the flow stability.

[0072] 25 groups of high-precision metering pumps:

[0073] Main pump: An electromagnetic diaphragm metering pump 25 (such as Milton Roy GM series) is used, configured with a servo motor drive, with a flow regulation range of 0 - 100% and an accuracy of ±0.5%.

[0074] Standby pump: In parallel with the main pump, when the signal of the main pump diaphragm breakage (detected by a pressure fluctuation sensor) is triggered, it automatically switches within 10 seconds.

[0075] Flowmeter 27: A Coriolis mass flowmeter 27 (accuracy ±0.1%) is used to directly measure the mass flow of the chemical agent, avoiding the defects of traditional volumetric flowmeters 27 affected by temperature and density.

[0076] Dynamic compensation valve group: Includes a pressure regulating valve (maintaining the pipeline pressure at 0.3 - 0.6 MPa) and a temperature compensation module (correcting the density parameter according to the temperature of the chemical agent).

[0077] Pipeline system:

[0078] Pipe material: PVDF pipes are used for acidic chemical agents, and PP-R pipes are used for alkaline chemical agents. The connection method is hot melt welding or quick-release clamps (for easy maintenance).

[0079] Visualization flow path: A transparent sight glass (made of borosilicate glass) is set at the pipe elbow, and a built-in camera is used to monitor the flow state in real time. An image recognition algorithm is combined to judge whether there are bubbles or blockages.

[0080] Mixing reaction unit. One end of the secondary filter 4 is connected to the top of the mixing reaction unit. The mixing reaction unit includes a reaction tank 11 and a reagent group connected to the reaction tank 11.

[0081] Central controller 10. The central controller 10 is electrically connected to multiple analyzers, and the central controller 10 is used to control the dosing amounts of the reagent group and the medicine storage unit.

[0082] The central controller 10 realizes data processing, strategy generation, equipment control and human-computer interaction, and includes the following modules:

[0083] PLC controller: Adopt Siemens S7-1500 or equivalent performance model, support 200+ IO points, and the processing cycle ≤ 1 ms.

[0084] Edge computing gateway: Equipped with an Intel Atom processor, running a Linux system, realizing preprocessing of sensor data (such as denoising, normalization) and local model inference (such as fault prediction algorithm).

[0085] Safety relay module: Independent of the PLC, receives emergency stop signals (such as leakage alarm), and cuts off all power supplies within 0.2 seconds.

[0086] The human-computer interaction software includes the following components:

[0087] HM interface: Designed with WinCC Unified, including:

[0088] Real-time monitoring page: Displays the weights of each medicine storage tank, the concentration curve of the reaction tank 11, and the equipment operation status (green = normal, yellow = warning, red = fault).

[0089] Process recipe page: Supports creating / editing dosing recipes for different workpiece types (such as carbon steel body recipe, aluminum alloy body recipe), and can store 100+ groups of recipes.

[0090] Data analysis page: Generates daily / monthly reports of reagent consumption, equipment energy consumption curves, and fault statistics histograms, and supports exporting to Excel / PDF.

[0091] Remote operation and maintenance module: Connects to the factory cloud platform through the OPCUA protocol to realize:

[0092] Remote parameter configuration: Engineers can adjust the control algorithm parameters in the office without going to the site.

[0093] Fault diagnosis expert system: Based on a knowledge base (storing more than 200 fault scenarios), automatically generate maintenance suggestions (such as "Pipeline blocked, it is recommended to start the backwashing program").

[0094] According to an embodiment of the present invention, the multiple chemical storage barrels 38 are respectively a degreasing agent barrel 20, a surface conditioner barrel 21, a phosphating agent barrel 22 and an accelerator barrel 23. A metering pump 25 is provided at the top of any one of the chemical storage barrels 38. One end of the metering pump 25 is connected to a check valve 26. One end of the check valve 26 is connected to a flowmeter 27. One end of the flowmeter 27 is connected to a ball valve 28. One end of the ball valve 28 is connected above the treatment tank 1.

[0095] According to an embodiment of the present invention, a calibration cylinder 24 is provided on one side of any one of the chemical storage barrels 38, and a liquid level gauge 15 is provided on the other side.

[0096] According to an embodiment of the present invention, the stirring assembly includes a stirring motor 33 fixedly installed on the top of the chemical storage barrel 38. The shaft end of the stirring motor 33 is connected to a stirring shaft 34. The stirring shaft 34 is inserted into the chemical storage barrel 38. The bottom end of the stirring shaft 34 is hinged to a stirring head 35. The stirring head 35 is of a fan blade structure. A discharge port 36 is provided on one side of the chemical storage barrel 38, and a filling port 39 is provided on the top of the chemical storage barrel 38.

[0097] According to an embodiment of the present invention, the primary filter 2 is provided with a 40μm - 60μm stainless steel filter screen, the secondary filter 4 is provided with a 5μm - 15μm sintered metal filter element. A peristaltic pump 3 is provided between the primary filter 2 and the secondary filter. One end of the secondary filter 4 is connected to an automatic valve 5. A peristaltic pump 3 is provided between the automatic valve 5 and the mixing reaction unit.

[0098] According to an embodiment of the present invention, a PH electrode 12 is provided in the reaction tank 11, and a vacuum pump 6 is provided at the bottom of the reaction tank 11. One end of the vacuum pump 6 is connected to a waste water tank 16.

[0099] According to an embodiment of the present invention, the reagent group includes a PH buffer tank 13, a cleaning agent tank 14, a pure water tank 17, a standard solution tank 18 and a hydrochloric acid reagent tank 19 arranged in parallel. The PH buffer tank 13, the cleaning agent tank 14, the pure water tank 17, the standard solution tank 18 and the hydrochloric acid reagent tank 19 are all connected to the reaction tank 11 through a peristaltic pump 3. Liquid level gauges 15 are provided on one side of the PH buffer tank 13, the cleaning agent tank 14, the pure water tank 17, the standard solution tank 18 and the hydrochloric acid reagent tank 19.

[0100] According to an embodiment of the present invention, the multiple analyzers include a first analyzer 7, a second analyzer 9 and a third analyzer 8. The first analyzer 7 is a PH analyzer. The second analyzer 9 is used to detect and analyze the free acid, total acid and promotion point in the reaction tank 11. The third analyzer 8 is used to detect and analyze the free base and total base in the reaction tank 11.

[0101] According to an embodiment of the present invention, a central controller 10 is electrically connected to a data acquisition unit 29, a model analysis unit 30, an execution control unit 31, and a feedback correction unit 32. The data acquisition unit 29 acquires the weight, density, and temperature of the medicament in the medicament storage unit.

[0102] The data acquisition unit 29 acquires the mass flow rate, pipeline pressure, and pump motor current of the metering and dosing unit. The data acquisition unit 29 acquires the concentration, pH, conductivity, volume, production line speed, and workpiece type in the mixing and reaction unit.

[0103] The model analysis unit 30 calls the corresponding formula according to the workpiece type and calculates the theoretical medicament demand.

[0104] The execution control unit 31 drives the metering pump 25 to control the quantitative dosing of the degreasing agent drum 20, the surface conditioner drum 21, the phosphating agent drum 22, and the accelerator drum 23, and controls the operation of the stirring motor 33 to uniformly mix the medicaments.

[0105] The feedback correction unit 32 compares the concentration value in the mixing and reaction unit with the target value to obtain a concentration difference. If the concentration difference is greater than the set concentration difference threshold, the dosing amount of the degreasing agent, surface conditioner, phosphating agent, or accelerator is adjusted.

[0106] According to an embodiment of the present invention, the central controller 10 is built-in with a control algorithm library, and the control algorithm library includes a main control algorithm and a self-learning model: the main control algorithm is a multi-variable coupling control algorithm based on fuzzy PID. The input parameters of the multi-variable coupling control algorithm based on fuzzy PID include the production line speed, workpiece surface area, current concentration in the reaction tank 11, and temperature, and the outputs are the rotation speed of the metering pump 25 and the stirring frequency.

[0107] The self-learning model is an LSTM neural network model, which is used to predict the medicament consumption rate under different working conditions and adjust the dosing strategy.

[0108] According to an embodiment of the present invention, the core control logic of the system is divided into four links: data acquisition → model calculation → execution control → feedback correction, as Figure 2 shown (control flow chart):

[0109] Data acquisition layer

[0110] Medicament storage unit: Acquire the medicament weight (W), density (ρ), and temperature (T1);

[0111] Metering and dosing unit: Acquire the mass flow rate (M), pipeline pressure (P), and pump motor current (I);

[0112] Mixing and reaction unit: Acquire the concentration (C), pH, conductivity (EC), volume (V), production line speed (v), and workpiece type (T).

[0113] Model calculation layer

[0114] Reagent demand calculation:

[0115] Call the corresponding formula according to the workpiece type (T) to calculate the theoretical reagent demand.

[0116] Dynamic compensation and correction:

[0117] Introduce the temperature compensation coefficient (α = 1 + 0.001×(T1 - 20)) and the viscosity correction coefficient (β, calculated by the density-viscosity empirical formula) to obtain the actual dosing amount.

[0118] Control quantity output:

[0119] Calculate the rotation speed (n) of the metering pump 25 and the agitator frequency (f) through the fuzzy PID algorithm, where the PID parameters are automatically switched according to the working conditions (such as increasing the proportional coefficient P during high-speed production).

[0120] Execution control layer

[0121] Drive the metering pump 25 to dose according to the actual flow rate, and at the same time control the operation of the agitator to ensure rapid and uniform mixing of the reagent;

[0122] When it is detected that the remaining amount in the storage tank is lower than 15%, automatically send a replenishment request (including reagent type, remaining amount, and urgency) to the logistics system.

[0123] Feedback correction layer

[0124] Collect the concentration data of the reaction tank 11 every 5 seconds, compare it with the target value. If the deviation exceeds ±2%, trigger the feedforward compensation algorithm to adjust the dosing amount in the next control cycle;

[0125] Perform self-calibration on the system every month: Verify the metering accuracy by dosing a known amount of reagent into the empty reaction tank 11, and automatically correct the flow coefficient.

[0126] In summary, this application uses the combination of the flowmeter 27 and the density sensor for metering, directly measures the reagent mass flow rate, eliminates the influence of temperature and viscosity on the metering accuracy, and the accuracy can reach ±0.5%; at the same time, through the weighing module 37 of the storage barrel 38 and the concentration sensor of the reaction tank 11, the dosing strategy is corrected in real time.

[0127] Multivariable adaptive control and intelligent decision-making

[0128] Based on the mathematical model of the pretreatment process, integrating PLC real-time data (production line speed, workpiece type), sensor data (temperature, pH, conductivity) and the historical database, automatically adjust the dosing amount through the fuzzy PID algorithm.

[0129] Full-system status monitoring and self-healing of faults

[0130] Deploy a multi-level sensor network (liquid level / weight / temperature of the medicine storage bucket 38, pipeline pressure / flow rate, pump body vibration / current) to achieve full-process monitoring from medicine storage to the dosing end;

[0131] Built-in fault diagnosis algorithm to automatically identify anomalies such as insufficient medicine, pipeline blockage, and pump body failure, trigger early warnings and execute emergency handling (such as switching to a standby pump, starting a pipeline cleaning program).

[0132] Integration of human-machine collaboration and remote operation and maintenance

[0133] Develop an interactive HMI interface, integrating functions such as trend analysis, energy consumption statistics, and formula management, supporting touch screen operation and gesture control;

[0134] Equipped with a 5G / industrial Ethernet communication module, for real-time data interaction with the factory MES system and cloud platform, to achieve remote parameter configuration, fault diagnosis, and big data analysis.

[0135] Anti-corrosion design and modular easy-maintenance structure

[0136] The medicine storage bucket 38, pipelines, and valves are made of acid- and alkali-resistant materials (such as 316L stainless steel, PP-H, PVDF), and the surfaces of key components are sprayed with a polytetrafluoroethylene (PTFE) coating, with the service life extended to more than 5 years;

[0137] Adopt quick-release joints and drawer-type sensor mounting brackets, and component replacement can be completed within 30 minutes during maintenance without shutting down the power supply.

[0138] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An automatic chemical dosing system applied to the pretreatment of an automobile painting workshop, characterized in that , including: A medicine storage unit, which includes a plurality of medicine storage barrels and a stirring assembly arranged inside the medicine storage barrels. A weighing module is arranged at the bottom of the medicine storage barrels; A metering and dosing unit, which is connected to the medicine storage unit. The metering and dosing unit includes a treatment tank. A primary filter is connected below the treatment tank, and a secondary filter is connected below the primary filter; A mixing and reaction unit, one end of the secondary filter is connected to the top of the mixing and reaction unit. The mixing and reaction unit includes a reaction tank and a reagent group connected to the reaction tank; A central controller, which is electrically connected to a plurality of analyzers. The central controller is used to control the dosing amounts of the reagent group and the medicine storage unit.

2. The automatic chemical dosing system applied to the pretreatment of an automobile painting workshop according to claim 1, characterized in that, The plurality of medicine storage barrels are respectively a degreasing agent barrel, a surface conditioner barrel, a phosphating agent barrel and a promoter barrel. A metering pump is arranged at the top of any one of the medicine storage barrels. One end of the metering pump is connected to a check valve. One end of the check valve is connected to a flow meter. One end of the flow meter is connected to a ball valve. One end of the ball valve is connected above the treatment tank.

3. The automatic chemical dosing system applied to the pretreatment of an automotive painting workshop according to claim 2, wherein, A calibration cylinder is arranged on one side of any one of the medicine storage barrels, and a liquid level gauge is arranged on the other side.

4. The automatic chemical dosing system applied to the pretreatment of an automotive painting workshop according to claim 1, wherein, The stirring assembly includes a stirring motor fixedly installed at the top of the medicine storage barrel. The shaft end of the stirring motor is connected to a stirring shaft. The stirring shaft is inserted into the medicine storage barrel. The bottom end of the stirring shaft is hinged with a stirring head, and the stirring head is of a fan blade structure.

5. The automatic chemical dosing system applied to the pretreatment of an automobile painting workshop according to claim 1, characterized in that, The primary filter is provided with a 40μm - 60μm stainless steel filter screen, and the secondary filter is provided with a 5μm - 15μm sintered metal filter element. A peristaltic pump is arranged between the primary filter and the secondary filter. One end of the secondary filter is connected to an automatic valve, and a peristaltic pump is arranged between the automatic valve and the mixing and reaction unit.

6. The automatic chemical dosing system for the pretreatment in an automotive painting workshop according to claim 1, wherein A PH electrode is arranged in the reaction tank, and a vacuum pump is arranged at the bottom of the reaction tank. One end of the vacuum pump is connected to a waste water tank.

7. The automatic chemical dosing system for the pretreatment in an automotive painting workshop according to claim 1, wherein, The reagent group includes a PH buffer tank, a cleaning agent tank, a pure water tank, a standard solution tank and a hydrochloric acid reagent tank arranged in parallel. The PH buffer tank, the cleaning agent tank, the pure water tank, the standard solution tank and the hydrochloric acid reagent tank are all connected to the reaction tank through peristaltic pumps. Liquid level gauges are arranged on one side of the PH buffer tank, the cleaning agent tank, the pure water tank, the standard solution tank and the hydrochloric acid reagent tank.

8. The automatic chemical dosing system for the pretreatment in an automotive painting workshop as described in claim 1, wherein, The plurality of analyzers include a first analyzer, a second analyzer and a third analyzer. The first analyzer is a PH analyzer. The second analyzer is used to detect and analyze the free acid, total acid and promotion point in the reaction tank. The third analyzer is used to detect and analyze the free base and total base in the reaction tank.

9. The automatic chemical dosing system for pretreatment in an automotive painting workshop according to claim 1, characterized in that, The central controller is electrically connected to a data acquisition unit, a model analysis unit, an execution control unit and a feedback correction unit. The data acquisition unit obtains the medicine weight, density and temperature of the medicine storage unit; The data acquisition unit obtains the mass flow rate, pipeline pressure and pump motor current of the metering and dosing unit; The data acquisition unit obtains the concentration, pH, conductivity, volume, production line speed and workpiece type in the mixing and reaction unit; The model analysis unit calls the corresponding formula according to the workpiece type and calculates the theoretical medicine demand; The execution control unit drives the metering pump to control the quantitative dosing of the degreasing agent drum, surface conditioner drum, phosphating agent drum, and accelerator drum, and controls the operation of the stirring motor to uniformly mix the agents. The feedback correction unit compares the concentration value in the mixing reaction unit with the target value to obtain a concentration difference. If the concentration difference is greater than the set concentration difference threshold, the dosing amount of the degreasing agent, surface conditioner, phosphating agent, or accelerator is adjusted.

10. The automatic chemical dosing system for pretreatment in an automotive painting workshop as described in claim 1, characterized in that, The central controller has a built-in control algorithm library, and the control algorithm library includes a main control algorithm and a self-learning model: the main control algorithm is a multi-variable coupling control algorithm based on fuzzy PID. The input parameters of the multi-variable coupling control algorithm based on fuzzy PID include the production line speed, workpiece surface area, current concentration in the reaction tank, and temperature, and the outputs are the metering pump speed and agitator frequency. The self-learning model is an LSTM neural network model, and the LSTM neural network model is used to predict the chemical agent consumption rate under different working conditions and adjust the dosing strategy.

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