Method and system for controlling zinc alloy coating thickness

Abstract

This invention provides a method and system for controlling the thickness of zinc alloy coatings. The method includes: acquiring the intensity of characteristic spectral lines of zinc in the zinc alloy coating area at first preset time intervals, inputting the data into a thickness inversion model to obtain a current thickness estimate; using the difference between the thickness estimate and the target thickness as a control deviation, substituting it into a PID closed-loop control model with feedforward compensation to calculate the initial adjustment amount of the coating process parameters; verifying the initial adjustment amount, performing amplitude limiting processing by comparing the expected thickness correction amplitude with a preset threshold to obtain the final adjustment amount; generating a control command based on the final adjustment amount and sending it to the coating equipment. This invention achieves real-time thickness acquisition through online spectral inversion, and combines feedforward PID control, amplitude limiting verification of the adjustment amount, and safety boundary control to solve the problems of measurement lag, easy over-limit of adjustment amount, and poor equipment safety in existing methods, achieving high-precision and high-safety closed-loop control.

Description

Technical Field

[0001] This invention relates to the field of zinc alloy thickness control technology, and in particular to a method and system for controlling the coating thickness of zinc alloys. Background Technology

[0002] Zinc alloy coating is a crucial process for corrosion protection and decoration of metal surfaces. The uniformity and precision of the coating thickness directly affect the product's corrosion resistance, mechanical properties, and production costs. Traditional thickness control methods often employ offline sampling measurements combined with manual adjustments, which suffer from significant lag and struggle to cope with dynamic interference factors such as zinc melt temperature fluctuations, substrate surface changes, and air knife pressure disturbances during the coating process. In recent years, some production lines have introduced online thickness measurement devices; however, existing direct measurement methods (such as X-ray backscattering and eddy current methods) suffer from poor measurement stability, slow response, and potential health hazards in the high-temperature molten zinc alloy environment. Therefore, achieving rapid, accurate, and closed-loop control of zinc alloy coating thickness is a pressing technical problem that needs to be solved in this field. Summary of the Invention

[0003] The purpose of this invention is to provide a method and system for controlling the coating thickness of zinc alloys, aiming to solve the problems of zinc alloy measurement lag, lack of closed-loop regulation, and easy over-limit of regulation in existing methods.

[0004] In a first aspect, the present invention provides a method for controlling the thickness of a zinc alloy coating, the method comprising:

[0005] The intensity of the characteristic spectral line of zinc element at at least one measurement point in the zinc alloy coating area is collected every first preset time interval, and the intensity of the characteristic spectral line of zinc element is input into the pre-constructed thickness inversion model to obtain the current thickness estimate of the zinc alloy.

[0006] The difference between the current thickness estimate and the target thickness value is used as the control deviation. The control deviation is substituted into the preset closed-loop control model to calculate the initial adjustment amount of the coating process parameters.

[0007] The initial adjustment amount is verified to obtain the final adjustment amount after verification. A control command is generated based on the final adjustment amount and sent to the coating equipment.

[0008] In some embodiments, a thickness inversion model is constructed based on the following formula:

[0009] ;

[0010] in, Here is the thickness estimate at time t. Let be the intensity of the characteristic spectral line of zinc at time t. The intensity of the characteristic spectral lines of the matrix elements. Let be the temperature of the molten pool at time t. All of these are model parameters determined through experimental calibration.

[0011] In some embodiments, the step of using the difference between the current thickness estimate and the target thickness value as a control deviation, and substituting the control deviation into a preset closed-loop control model to calculate the initial adjustment amount of the coating process parameters includes:

[0012] The initial adjustment amount is calculated using the following formula:

[0013] ;

[0014] in, Let be the initial adjustment amount at time t. , , All are PID parameters. This is the feedforward gain coefficient. To control deviation.

[0015] In some embodiments, the step of verifying the initial adjustment amount to obtain the verified final adjustment amount includes:

[0016] The expected thickness correction range corresponding to the initial adjustment amount is calculated using the following formula:

[0017] ;

[0018] in, Let be the expected thickness correction range at time t. For process sensitivity coefficient, Let be the air knife pressure at time t. Let be the linear velocity of the workpiece at time t;

[0019] Determine whether the expected thickness correction range exceeds the preset maximum allowable correction threshold;

[0020] If the expected thickness correction range is greater than the preset maximum allowable correction threshold, the initial adjustment amount will be limited according to the following formula:

[0021] ;

[0022] in, For the final adjustment amount, This is the preset maximum allowable correction threshold;

[0023] If the expected thickness correction is less than or equal to the preset maximum allowable correction threshold, then let .

[0024] In some embodiments, the step of generating control commands based on the final adjustment amount includes:

[0025] The final adjustment amount is summed with the control signal of the coating equipment at the current moment to obtain the original control command;

[0026] If the original control command is greater than the preset safety control limit, then the preset safety control limit shall be used as the final control command;

[0027] If the original control command is less than the preset safety control lower limit, then the preset safety control lower limit shall be used as the final control command;

[0028] If the original control command is less than or equal to the preset safety control upper limit and greater than or equal to the preset safety control lower limit, then the original command shall be used as the final control command.

[0029] Secondly, the present invention provides a control system for the coating thickness of a zinc alloy, the system comprising:

[0030] The thickness calculation module is used to collect the intensity of the characteristic spectral line of zinc element at at least one measurement point in the zinc alloy coating area every first preset time, and input the intensity of the characteristic spectral line of zinc element into the pre-constructed thickness inversion model to obtain the current thickness estimate of the zinc alloy.

[0031] The adjustment amount calculation module is used to use the difference between the current thickness estimate and the target thickness value as the control deviation, and substitute the control deviation into the preset closed-loop control model to calculate the initial adjustment amount of the coating process parameters.

[0032] The control command generation module is used to verify the initial adjustment amount, obtain the verified final adjustment amount, generate a control command based on the final adjustment amount, and send the control command to the coating equipment.

[0033] Thirdly, the present invention provides a storage medium storing one or more programs that, when executed by a processor, implement the above-described method for controlling the thickness of zinc alloy coating.

[0034] Fourthly, the present invention provides an electronic device, the electronic device comprising a memory and a processor, wherein:

[0035] The memory is used to store computer programs;

[0036] When the processor executes the computer program stored in the memory, it implements the above-mentioned method for controlling the thickness of the zinc alloy coating.

[0037] Compared with the prior art, the present invention has the following advantages:

[0038] This invention enables online, high-precision, and safe closed-loop control of zinc alloy coating thickness, significantly improving thickness uniformity, control response speed, and process safety. Specifically, by periodically collecting the intensity of characteristic zinc elemental spectral lines and combining this with the molten pool temperature, a thickness inversion model is constructed. This allows for rapid estimation of the current thickness without contact with the high-temperature molten coating, overcoming the severe lag of traditional offline sampling and detection, and achieving real-time online thickness sensing. Furthermore, the thickness deviation is input into a PID model with a feedforward term. The thickness change rate feedforward term compensates for fluctuation trends before the deviation significantly increases, effectively suppressing thickness fluctuations caused by dynamic disturbances such as air knife pressure fluctuations and linear velocity changes, thus improving the dynamic response capability and anti-interference performance of the control system. Furthermore, by calculating the expected thickness correction range and comparing it with the preset maximum allowable correction threshold, the initial adjustment amount is limited when the expected correction range exceeds the limit. At the same time, safety control upper and lower limits are introduced for secondary limiting when generating control commands, forming a dual safety guarantee mechanism. This effectively avoids process defects such as drastic fluctuations in air knife pressure, overload of coating roller motor, or flow marks and missed coating caused by excessive adjustment in a single control cycle. It ensures that the coating equipment always operates within the safety boundary, significantly improving the robustness and engineering practicality of the control process. Attached Figure Description

[0039] Figure 1 This is a flowchart of a method for controlling the coating thickness of a zinc alloy according to an embodiment of the present invention;

[0040] Figure 2 This is a schematic diagram of a control system for zinc alloy coating thickness according to an embodiment of the present invention.

[0041] The following detailed description, in conjunction with the accompanying drawings, will further illustrate the present invention. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art. The terms "comprising" and similar expressions used herein mean that the element or object preceding the word covers the element or object listed after the word and its equivalents, but does not exclude other elements or objects.

[0043] like Figure 1As shown, an embodiment of the present invention proposes a method for controlling the coating thickness of zinc alloy, the method comprising steps S101 to S103, wherein:

[0044] Step S101: Collect the intensity of the characteristic spectral line of zinc element at at least one measurement point in the zinc alloy coating area every first preset time, and input the intensity of the characteristic spectral line of zinc element into the pre-constructed thickness inversion model to obtain the current thickness estimate of the zinc alloy.

[0045] It should be noted that, due to the high-temperature molten state of the zinc alloy coating during the coating process, traditional contact or non-contact direct measurement methods suffer from problems such as poor accuracy, slow response, or safety hazards. Therefore, this embodiment employs a strategy of indirect inversion using spectral analysis. Specifically, the system automatically triggers a data acquisition action every first preset time interval (e.g., every 100 milliseconds) to obtain the characteristic spectral line intensity of zinc at at least one measurement point in the coated area. This spectral line intensity is directly related to the excitation density of zinc atoms in the coating, and thus has a clear physical correspondence with the coating thickness. These spectral line intensity data are input into a pre-constructed thickness inversion model built through calibration experiments. The model quickly calculates the estimated thickness at the current moment based on parameters such as the ratio of zinc to matrix element spectral line intensities and the current molten pool temperature. The core value of this step lies in achieving non-contact, rapid, and continuous thickness acquisition, providing timely and reliable input data for subsequent closed-loop control, and completely changing the lag inherent in traditional offline sampling methods.

[0046] Specifically, in some embodiments, the thickness inversion model is constructed according to the following formula:

[0047] ;

[0048] in, Here is the thickness estimate at time t. Let be the intensity of the characteristic spectral line of zinc at time t. The intensity of the characteristic spectral lines of the matrix elements. Let be the temperature of the molten pool at time t. All of these are model parameters determined through experimental calibration.

[0049] In summary, the above formula effectively eliminates common-mode interference such as light source fluctuations and measurement distance variations by incorporating the spectral intensity ratio of zinc to matrix elements. Simultaneously, it introduces molten pool temperature as a correction term to compensate for the influence of temperature on plasma excitation efficiency. The model coefficients in this formula are pre-determined through standard sample calibration experiments, giving the thickness inversion model clear physical meaning and operability, significantly improving the accuracy and robustness of the thickness estimate.

[0050] Step S102: Using the difference between the current thickness estimate and the target thickness value as the control deviation, substitute the control deviation into the preset closed-loop control model to calculate the initial adjustment amount of the coating process parameters;

[0051] It should be noted that after obtaining the current thickness estimate, the system subtracts it from the preset target thickness value to obtain the control deviation. This deviation reflects the difference between the current coating thickness and the desired thickness, and is the direct basis for determining how to adjust the coating equipment. Subsequently, the system substitutes this control deviation into a preset closed-loop control model for calculation. This model adopts a proportional-integral-derivative control algorithm with a feedforward compensation term: the proportional term provides immediate adjustment based on the magnitude of the current deviation, the integral term eliminates long-term accumulated steady-state errors, the derivative term applies reverse adjustment in advance based on the trend of deviation changes to prevent overshoot, and the feedforward term uses the thickness change rate information to compensate for known disturbances in advance. Through the calculation of this model, the system finally outputs a specific initial adjustment amount for the coating process parameter, such as the increase in air knife pressure or the decrease in coating roller gap.

[0052] Specifically, the initial adjustment amount is calculated according to the following formula:

[0053] ;

[0054] in, Let be the initial adjustment amount at time t. , , All are PID parameters. This is the feedforward gain coefficient. To control deviation.

[0055] Step S103: Verify the initial adjustment amount to obtain the final adjustment amount after verification, generate a control command based on the final adjustment amount, and send the control command to the coating equipment.

[0056] In practical engineering applications, excessive adjustment amounts can lead to coating equipment exceeding its physical limits or safety boundaries. For example, a sudden increase in air knife pressure could damage the equipment, or excessive adjustment could cause drastic fluctuations in coating thickness, rendering the coating unusable. Therefore, this step first verifies the initial adjustment amount. Verification typically involves calculating the expected thickness correction range corresponding to the adjustment amount and determining whether this range exceeds a preset maximum allowable correction threshold. If it does, the adjustment amount is limited to a safe range, resulting in the final adjustment amount. Then, the system generates specific control commands executable by the coating equipment based on this final, safety-verified adjustment amount, such as a specific voltage signal or digital command. Finally, this command is sent to the corresponding coating equipment, such as the air knife pressure regulating valve or the coating roller gap adjusting motor, via the industrial bus or I / O port, completing a full control cycle. Through this step, the system prioritizes equipment safety and process stability while pursuing high-precision control, avoiding production accidents caused by extreme adjustment commands.

[0057] Specifically, the expected thickness correction range corresponding to the initial adjustment amount is calculated according to the following formula:

[0058] ;

[0059] in, Let be the expected thickness correction range at time t. For process sensitivity coefficient, Let be the air knife pressure at time t. Let be the linear velocity of the workpiece at time t;

[0060] Determine whether the expected thickness correction range exceeds the preset maximum allowable correction threshold;

[0061] If the expected thickness correction range is greater than the preset maximum allowable correction threshold, the initial adjustment amount will be limited according to the following formula:

[0062] ;

[0063] in, For the final adjustment amount, This is the preset maximum allowable correction threshold;

[0064] If the expected thickness correction is less than or equal to the preset maximum allowable correction threshold, then let .

[0065] Furthermore, in some embodiments, the final adjustment amount needs to be summed with the control signal of the coating equipment at the current moment to obtain the original control command; if the original control command is greater than the preset safety control upper limit, then the preset safety control upper limit is used as the final control command; if the original control command is less than the preset safety control lower limit, then the preset safety control lower limit is used as the final control command; if the original control command is less than or equal to the preset safety control upper limit and greater than or equal to the preset safety control lower limit, then the original command is used as the final control command.

[0066] By pre-setting upper and lower safety control limits, the original control commands are subject to secondary judgment and limitation: if the original command exceeds the upper limit, the upper limit value is used as the final control command; if it is below the lower limit, the lower limit value is used as the final control command; if it is between the upper and lower limits, the original command is retained. This ensures that every control command sent to the coating equipment is strictly limited within the equipment's safe operating boundaries, effectively avoiding problems such as actuator saturation, damage, or process loss caused by command exceeding limits.

[0067] In summary, the aforementioned method for controlling the thickness of zinc alloy coatings enables online, high-precision, and safe closed-loop control of the coating thickness, significantly improving thickness uniformity, control response speed, and process safety. Specifically, by periodically collecting the intensity of characteristic spectral lines of zinc and combining this with the molten pool temperature, a thickness inversion model is constructed. This allows for rapid estimation of the current thickness without contact with the high-temperature molten coating, overcoming the severe lag of traditional offline sampling and detection, and achieving real-time online thickness sensing. Furthermore, the thickness deviation is input into a PID model with a feedforward term. The thickness change rate feedforward term compensates for fluctuation trends before the deviation significantly increases, effectively suppressing thickness fluctuations caused by dynamic disturbances such as air knife pressure fluctuations and linear velocity changes, thus improving the dynamic response capability and anti-interference performance of the control system. Furthermore, by calculating the expected thickness correction range and comparing it with the preset maximum allowable correction threshold, the initial adjustment amount is limited when the expected correction range exceeds the limit. At the same time, safety control upper and lower limits are introduced for secondary limiting when generating control commands, forming a dual safety guarantee mechanism. This effectively avoids process defects such as drastic fluctuations in air knife pressure, overload of coating roller motor, or flow marks and missed coating caused by excessive adjustment in a single control cycle. It ensures that the coating equipment always operates within the safety boundary, significantly improving the robustness and engineering practicality of the control process.

[0068] like Figure 2 As shown, one embodiment of the present invention proposes a control system for the coating thickness of zinc alloy, the system comprising:

[0069] The thickness calculation module 10 is used to collect the intensity of the zinc element characteristic spectral line at at least one measurement point in the zinc alloy coating area every first preset time, and input the intensity of the zinc element characteristic spectral line into the pre-constructed thickness inversion model to obtain the current thickness estimate of the zinc alloy.

[0070] The adjustment amount calculation module 20 is used to use the difference between the current thickness estimate and the target thickness value as the control deviation, and substitute the control deviation into the preset closed-loop control model to calculate the initial adjustment amount of the coating process parameters.

[0071] The control command generation module 30 is used to verify the initial adjustment amount, obtain the verified final adjustment amount, generate a control command based on the final adjustment amount, and send the control command to the coating equipment.

[0072] In another aspect, the present invention also proposes a storage medium having stored one or more programs thereon, which, when executed by a processor, implement the above-described method for controlling the thickness of the zinc alloy coating.

[0073] In another aspect, the present invention provides an electronic device, including a memory and a processor, wherein the memory is used to store a computer program, and the processor is used to execute the computer program stored in the memory to realize the above-mentioned method for controlling the thickness of zinc alloy coating.

[0074] Those skilled in the art will understand that the logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can mean any means that can contain stored, communicated, propagated, or transmitted programs for use by, or in conjunction with, an instruction execution system, apparatus, or device.

[0075] More specific examples of computer-readable media (a non-exhaustive list) include: electrical connections (electronic devices) having one or more wires, portable computer disk drives (magnetic devices), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Furthermore, computer-readable media can even be paper or other suitable media on which the program can be printed, because the program can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in computer memory.

[0076] It should be understood that various parts of the present invention can be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0077] While embodiments of the present invention have been described in detail above, it will be apparent to those skilled in the art that various modifications and variations can be made to these embodiments. However, it should be understood that such modifications and variations fall within the scope and spirit of the invention as set forth in the claims. Furthermore, the invention described herein may have other embodiments and can be implemented or carried out in various ways.

Claims

1. A method for controlling the thickness of a zinc alloy coating, characterized in that, The method includes: The intensity of the characteristic spectral line of zinc element at at least one measurement point in the zinc alloy coating area is collected every first preset time interval, and the intensity of the characteristic spectral line of zinc element is input into the pre-constructed thickness inversion model to obtain the current thickness estimate of the zinc alloy. The difference between the current thickness estimate and the target thickness value is used as the control deviation. The control deviation is substituted into the preset closed-loop control model to calculate the initial adjustment amount of the coating process parameters. The initial adjustment amount is verified to obtain the final adjustment amount after verification. A control command is generated based on the final adjustment amount and sent to the coating equipment.

2. The method for controlling the thickness of zinc alloy coating according to claim 1, characterized in that, Construct a thickness inversion model based on the following formula: ； in, Here is the thickness estimate at time t. Let be the intensity of the characteristic spectral line of zinc at time t. The intensity of the characteristic spectral lines of the matrix elements. Let be the temperature of the molten pool at time t. All of these are model parameters determined through experimental calibration.

3. The method for controlling the thickness of zinc alloy coating according to claim 2, characterized in that, The step of using the difference between the current thickness estimate and the target thickness value as the control deviation, and substituting the control deviation into a preset closed-loop control model to calculate the initial adjustment amount of the coating process parameters includes: The initial adjustment amount is calculated using the following formula: ； in, Let be the initial adjustment amount at time t. , , All are PID parameters. This is the feedforward gain coefficient. To control deviation.

4. The method for controlling the thickness of zinc alloy coating according to claim 3, characterized in that, The step of verifying the initial adjustment amount to obtain the verified final adjustment amount includes: The expected thickness correction range corresponding to the initial adjustment amount is calculated using the following formula: ； in, Let be the expected thickness correction range at time t. For process sensitivity coefficient, Let be the air knife pressure at time t. Let be the linear velocity of the workpiece at time t; Determine whether the expected thickness correction range exceeds the preset maximum allowable correction threshold; If the expected thickness correction range is greater than the preset maximum allowable correction threshold, the initial adjustment amount will be limited according to the following formula: ； in, For the final adjustment amount, This is the preset maximum allowable correction threshold; If the expected thickness correction is less than or equal to the preset maximum allowable correction threshold, then let .

5. The method for controlling the thickness of zinc alloy coating according to claim 4, characterized in that, The step of generating control commands based on the final adjustment amount includes: The final adjustment amount is summed with the control signal of the coating equipment at the current moment to obtain the original control command; If the original control command is greater than the preset safety control limit, then the preset safety control limit shall be used as the final control command; If the original control command is less than the preset safety control lower limit, then the preset safety control lower limit shall be used as the final control command. If the original control command is less than or equal to the preset safety control upper limit and greater than or equal to the preset safety control lower limit, then the original command shall be used as the final control command.

6. A control system for the thickness of zinc alloy coating, characterized in that, The system includes: The thickness calculation module is used to collect the intensity of the characteristic spectral line of zinc element at at least one measurement point in the zinc alloy coating area every first preset time, and input the intensity of the characteristic spectral line of zinc element into the pre-constructed thickness inversion model to obtain the current thickness estimate of the zinc alloy. The adjustment amount calculation module is used to use the difference between the current thickness estimate and the target thickness value as the control deviation, and substitute the control deviation into the preset closed-loop control model to calculate the initial adjustment amount of the coating process parameters. The control command generation module is used to verify the initial adjustment amount, obtain the verified final adjustment amount, generate a control command based on the final adjustment amount, and send the control command to the coating equipment.

7. A storage medium, characterized in that, The storage medium stores one or more programs that, when executed by a processor, implement the method for controlling the thickness of zinc alloy coating as described in any one of claims 1-5.

8. An electronic device, characterized in that, The electronic device includes a memory and a processor, wherein: The memory is used to store computer programs; When the processor executes a computer program stored in the memory, it implements the method for controlling the thickness of zinc alloy coating as described in any one of claims 1-5.

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