Automatic optimization adjustment method for gravure printing process parameters

Abstract

The method comprises the following steps: initializing process parameters and setting iteration and termination conditions, presetting quality standards and constructing a target function, obtaining a current optimal process parameter evaluation index, randomly searching for new process parameters, calculating a new process parameter evaluation index, judging whether to accept or reject the new process parameters as a new current optimal solution according to an acceptance criterion, and outputting a global optimal process parameter as an optimal solution combination of the gravure printing process parameters until the termination condition is met, so as to control the printing machine to realize automatic adjustment. The gravure printing process parameter automatic optimization adjustment method has the characteristics of high efficiency, automation and cost saving.

Description

Technical Field

[0001] This invention belongs to the field of gravure printing technology and relates to a method for automatically optimizing and adjusting gravure printing process parameters. Background Technology

[0002] In traditional gravure printing production, the adjustment of process parameters mainly relies on the experience and skills of the operators. Technicians need to repeatedly adjust the equipment settings based on the requirements of the printed materials and the actual gravure printing effect, gradually optimizing the process parameters through trial and error. This method has the following drawbacks: First, it depends on the operator's personal experience and manual adjustments, and different operators may arrive at different adjustment results, leading to inconsistencies in the quality of gravure printing. This is not only time-consuming and inefficient, but may also result in waste of manpower and materials. Second, manual adjustments are unlikely to achieve global optimization of process parameters, often easily getting stuck in local optima, thus failing to fully utilize the potential of the gravure printing equipment.

[0003] Currently, although some rule-based and simple model-based automatic adjustment techniques have been applied in actual production, these methods generally lack flexibility and adaptability, making it difficult to cope with the changing gravure printing conditions and diverse gravure printing tasks. Therefore, developing a more efficient, intelligent, and widely applicable method for optimizing gravure printing process parameters has become crucial for improving the technological level of the gravure printing industry. Summary of the Invention

[0004] The purpose of this invention is to provide an automatic optimization and adjustment method for gravure printing process parameters, which features high efficiency, automation, and cost savings.

[0005] The technical solution adopted in this invention is an automatic optimization and adjustment method for gravure printing process parameters. The steps are as follows: initializing process parameters and setting start parameters and termination conditions, preset quality standards and constructing objective functions, obtaining the current optimal process parameter evaluation index, randomly searching for new process parameters, calculating the new process parameter evaluation index, outputting a new current optimal solution according to the acceptance criteria, until the termination condition is met and the globally optimal process parameters are output as the optimal solution combination of gravure printing process parameters, thereby controlling the printing press to achieve automatic adjustment.

[0006] The invention is further characterized by:

[0007] The specific steps are as follows:

[0008] Step 1: Initialize process parameters and set initial temperature, cooling rate, number of iterations, and termination temperature;

[0009] Step 2: Input the initialized process parameters and iteration conditions into the gravure printing control system to control the gravure printing equipment to perform one printing process; based on the preset quality standard of the printing effect, construct the objective function, calculate the gravure printing quality evaluation index under the current process parameters, use it as the current optimal process parameter evaluation index, and take the current process parameters as the current optimal solution.

[0010] Step 3: Generate new process parameters by random perturbation, complete one printing process, calculate the gravure printing quality evaluation index under the new process parameters, and record the new process parameters and the corresponding evaluation index.

[0011] Step 4: Compare the evaluation index of the new process parameters with the evaluation index of the current optimal process parameters, and output the new current optimal solution according to the acceptance criteria;

[0012] Step 5 and Step 4: After each output, determine whether the optimization termination condition is met. If it is met, directly output the globally optimal process parameters. If not, gradually reduce the system temperature according to the cooling rate. Repeat Step 3-4 once after each temperature reduction and output the results until the optimization termination condition is met. Output the globally optimal process parameters as the optimal solution combination of gravure printing process parameters, thereby controlling the printing equipment to achieve automated adjustment.

[0013] The process parameters include color registration deviation, ink volume, and paper feed speed. The initialization specifically involves generating initial values ​​using a random generation method.

[0014] Quality standards include image sharpness, color saturation, and color difference.

[0015] In step 2, the objective function is constructed using a weighted sum, and the expression for the objective function is:

[0016]

[0017] in, It is the objective function value, representing a given vector of process parameters. Overall printing quality evaluation; It is the value of the i-th evaluation index; w i It is the weight of the i-th evaluation indicator.

[0018] Step 3 specifically involves:

[0019] Step 3.1: Based on the current process parameters, generate new process parameters through random perturbation;

[0020] Step 3.2: Input the new process parameters into the gravure printing control system and control the gravure printing equipment to perform the printing process again;

[0021] Step 3.3: Based on the results of gravure printing, calculate the printing quality evaluation index under the new process parameters using the objective function;

[0022] Step 3.4: Record the new process parameters and the corresponding evaluation indicators for the new process parameters.

[0023] The random disturbance is specifically defined as: adding a small random disturbance value to the current process parameter, with the random disturbance value not exceeding 30% of the current process parameter value.

[0024] In step 4, the acceptance criteria are as follows:

[0025]

[0026] Where ΔE is the difference between the evaluation index of the new process parameters and the evaluation index of the current optimal process parameters. It is calculated as the evaluation index of the new process parameters minus the evaluation index of the current optimal process parameters. If ΔE < 0, it means that the evaluation index of the new process parameters is better than the evaluation index of the current optimal process parameters, and the acceptance criterion F = 1. In this case, the new process parameters will be accepted as the new current optimal solution, and the current process parameters will be replaced by the new process parameters. If ΔE ≥ 0, it means that the evaluation index of the new process parameters is worse than the evaluation index of the current optimal process parameters, and the acceptance criterion F = 1. At this point, the acceptance criterion determines whether to accept the new process parameters based on the calculated acceptance probability P.

[0027] The acceptance probability P is expressed as follows:

[0028]

[0029] T is the current system temperature. The higher the temperature, the greater the probability of accepting a poor solution; the lower the temperature, the smaller the probability of accepting a poor solution. k is the adjustment constant, and exp represents the natural exponent.

[0030] A random number between 0 and 1 is generated. If the random number is less than or equal to the acceptance probability P, the new process parameters are accepted and updated to the new current optimal solution, and the current process parameters are replaced with the new process parameters; otherwise, the current optimal solution is kept unchanged.

[0031] The optimized termination condition is: the number of iterations is met or the current system temperature reaches the termination temperature; the cooling process specifically involves: gradually reducing the system temperature using a linear cooling method based on the cooling rate.

[0032] The beneficial effects of this invention are:

[0033] 1) Improve gravure printing quality: Through precise optimization, the best combination of gravure printing process parameters can be found quickly, achieving optimal matching of color registration, ink volume control and paper feed speed. This fine control greatly reduces the color deviation, image blurring and other problems that may occur during the gravure printing process, thereby ensuring high-quality output of gravure printed products.

[0034] 2) Reduced operational difficulty: The traditional gravure printing parameter adjustment process relies on the experience of technicians and manual debugging, which is not only time-consuming but also inefficient. This invention reduces the dependence on manual skills through automatic optimization and adjustment, making the operation simpler, which helps to lower the technical threshold and reduce training costs.

[0035] 3) Enhanced adaptability and versatility: It is not only applicable to various gravure printing machines, but also capable of self-learning and adjusting to different gravure printing materials and operational requirements, thus enhancing the system's versatility and adaptability, making it particularly suitable for gravure printing fields that require high-quality output;

[0036] 4) Huge market potential: The optimization and adjustment method of this invention has broad market prospects. It can help various gravure printing companies improve production efficiency, save costs, and enhance the market competitiveness of their products. Attached Figure Description

[0037] Figure 1 This is a flowchart of the automatic optimization and adjustment method for gravure printing process parameters according to the present invention;

[0038] Figure 2 This is a flowchart of the acceptance criteria in the automatic optimization and adjustment method for gravure printing process parameters of the present invention. Detailed Implementation

[0039] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0040] Example 1

[0041] The automatic optimization and adjustment method for gravure printing process parameters of the present invention is as follows: Figure 1As shown, the specific steps are as follows: Initialize process parameters and set start and end conditions; preset quality standards and construct an objective function; obtain the current optimal process parameter evaluation index; randomly search for new process parameters; calculate the new process parameter evaluation index; judge whether to accept or reject the new process parameters as the new current optimal solution based on acceptance criteria; until the termination condition is met, output the globally optimal process parameters as the optimal combination of gravure printing process parameters, thereby controlling the printing press to achieve automated adjustment. This not only improves the automation level of the gravure printing process but also significantly improves the quality of gravure printed products and increases the efficiency and reliability of the production process. It has good versatility and adaptability, and can be widely used in various types of gravure printing equipment and diverse gravure printing materials, possessing great market potential and application value.

[0042] The specific steps are as follows:

[0043] Step 1, a) Initialization stage: Initialize process parameters and set initial temperature, cooling rate, number of iterations, and termination temperature;

[0044] The initialization phase is the foundation and starting point of the entire process. In this phase, it is necessary to set the initial values ​​for the gravure printing process parameters, which will directly affect the subsequent simulated gravure printing effect and quality evaluation indicators. The following are the detailed steps and methods for the initialization phase:

[0045] Determine initial process parameters: First, set initial values ​​for the gravure printing process parameters. These parameters include color registration deviation, ink volume, and paper feed speed. The initial values ​​for these parameters can be generated randomly.

[0046] Setting the initial temperature (T_initial): The initial temperature is the temperature value set at the beginning of the search, determining the probability of accepting a poor solution in the early stages. The initial temperature is a key parameter that determines the thermodynamic characteristics during the search process. The initial temperature can also be adjusted according to actual conditions to ensure that the optimal solution is found within a reasonable timeframe.

[0047] Set the termination temperature (T_final): The termination temperature is one of the conditions for ending the search. If the current system temperature drops to the termination temperature, the search will stop and the current optimal gravure printing process parameters will be output. When setting this temperature, a balance needs to be struck between search efficiency and solution quality; adjustments can be made based on actual conditions.

[0048] Setting the cooling rate (alpha): The cooling rate determines how quickly the system temperature decreases during the search process, expressed as the percentage decrease in temperature after each iteration. A faster cooling rate may lead to getting trapped in a local optimum, while a slower cooling rate may make the search process too time-consuming. The cooling process decreases linearly, used to determine the amount of temperature reduction after each iteration.

[0049] Setting the Iteration Number: The iteration number is another key parameter that determines the search process. It is the total number of iterations and also determines when to stop. A larger number of iterations can improve the quality of the solution, but it will also increase the computation time. Therefore, it is necessary to set an appropriate number of iterations based on the actual situation to ensure that the optimal solution can be found within a reasonable time.

[0050] Step 2, b) Evaluation phase:

[0051] The evaluation phase assesses the impact of currently set gravure printing process parameters on print quality. The purpose of this phase is to quantify the quality of printed products under different process parameter settings and to provide a basis for decision-making in the subsequent search phase. The specific steps of the evaluation phase are as follows:

[0052] 2.1 Input the initial process parameters into the gravure printing control system to control the gravure printing equipment to perform one printing process; in this process, there will be actual operations such as ink transfer, paper feeding, and color superposition.

[0053] 2.2. Pre-set a set of quality standards;

[0054] Before starting the evaluation, a set of quality standards is preset based on the printing effect to evaluate various performance indicators of the printed products. These quality standards include image sharpness, color saturation, and color difference, and an objective function is constructed using a weighted sum. for:

[0055]

[0056] In equation (1), It is the objective function value, representing a given vector of process parameters. Overall printing quality evaluation; It is the value of the i-th evaluation index, which reflects the process parameter vector. Performance in a specific aspect. The value ranges from 0 to 100, depending on the actual printing effect.

[0057] w i is the weight of the i-th evaluation indicator, representing its importance relative to other indicators. A higher weight indicates a greater impact of that indicator on the overall score. This can be achieved by adjusting the weight w. i This can reflect the relative importance of different quality characteristics in the overall evaluation. For example, if color saturation is crucial to print quality, then the weight corresponding to color saturation can be set higher. This weighted sum method allows priority to be given to factors that have the greatest impact on the quality of the final product.

[0058] 2.3 After a printing cycle is completed, the gravure printing quality evaluation index (objective function) under the current process parameters is calculated according to the preset quality standards. This index is used as the current optimal process parameter evaluation index. This includes the analysis of the printed image, such as measuring image sharpness, color saturation, color difference, etc., and the current process parameters are used as the current optimal solution.

[0059] Step 3, c) Search phase:

[0060] The search phase is the core of the method of this invention. It is responsible for exploring the parameter space of gravure printing processes and finding the optimal combination of parameters that can improve printing quality. Specifically:

[0061] 3.1. Based on the current process parameters, generate new process parameters through random perturbation;

[0062] This is achieved by adding a small random disturbance value to the current process parameters. The magnitude of the disturbance is controlled by the system's temperature parameters. The disturbance range is larger when the temperature is higher and smaller when the temperature is lower.

[0063] The random disturbance value shall not exceed 30% of the current process parameter value.

[0064] 3.2 Input the new process parameters into the gravure printing control system and control the gravure printing equipment to perform a printing process again; this step involves resetting the gravure printing equipment to reflect the new parameter settings.

[0065] 3.3 Based on the results of gravure printing, calculate the printing quality evaluation indicators under the new process parameters, such as image sharpness, color saturation, and color difference. These indicators will be used for subsequent acceptance criteria judgment.

[0066] 3.4 Record the new process parameters and their corresponding evaluation indicators; so as to compare them with the current optimal solution and the current optimal process parameter evaluation indicators, and to use them for possible backtracking and analysis.

[0067] During the search phase, a balance needs to be struck between exploration and exploitation. In the early stages, more exploration is required, involving trying new parameters that are significantly different from the current solution; while in the later stages, more exploitation may be needed, involving a more detailed search within the neighborhood of the current solution. This balance can be achieved by adjusting the current system temperature and cooling rate.

[0068] Step 4, d) Acceptance criteria judgment:

[0069] The acceptance criterion judgment stage is a crucial step, determining whether to accept the new process parameters as the current solution. The specific steps are as follows:

[0070] The evaluation index of the new process parameters is compared with the current optimal process parameter evaluation index, including image clarity, color saturation, color difference, etc., and a new current optimal solution is output according to the acceptance criteria.

[0071] The acceptance criteria are as follows:

[0072]

[0073] ΔE represents the difference between the evaluation index of the new process parameters and the evaluation index of the current optimal process parameters. It is calculated as the new process parameter evaluation index minus the current optimal process parameter evaluation index. If ΔE < 0, it means the evaluation index corresponding to the new process parameters is better than the evaluation index of the current optimal solution, and the acceptance criterion F = 1. The new process parameters will be accepted as the new current optimal solution, and the current process parameters will replace the new process parameters. If ΔE ≥ 0, it means the evaluation index of the new process parameters is worse than the evaluation index of the current optimal process parameters, and the acceptance criterion... At this point, the acceptance criterion determines whether to accept the new process parameters based on the calculated acceptance probability P.

[0074] The acceptance probability P is expressed as follows:

[0075]

[0076] In the formula, T is the current system temperature. The higher the temperature, the greater the probability of accepting a worse solution; the lower the temperature, the smaller the probability of accepting a worse solution; k is an adjustment constant, which can generally be taken as 1, and exp represents the natural exponent.

[0077] A random number between 0 and 1 is generated. If the random number is less than or equal to the acceptance probability P, the new process parameters are accepted and updated to the new current optimal solution. The current process parameters are then replaced with the new process parameters for use in the next iteration. Otherwise, the current optimal solution is kept unchanged.

[0078] Step 5, e) Temperature reduction and iteration

[0079] Temperature reduction and iterative phases control the search process, gradually approaching the global optimum. For example... Figure 1 and Figure 2 As shown, the specific steps are as follows:

[0080] The optimized termination condition is: either the number of iterations is reached or the current system temperature reaches the termination temperature; either condition is sufficient.

[0081] Step 4: After each output, determine whether the iteration count or the current system temperature has reached the termination temperature. If the count is met, directly output the globally optimal process parameters. If not, use a linear cooling method to gradually reduce the system temperature based on the cooling rate. Repeat steps 3-4 once after each cooling cycle, output the results, and determine whether the optimization termination condition is met. Continue until the predetermined iteration count is reached or the system temperature reaches the preset termination temperature. If either condition is met, stop the optimization and output the globally optimal process parameters as the optimal combination of gravure printing process parameters to control the printing equipment for automated adjustment.

[0082] Temperature reduction: A linear cooling method is used to gradually lower the system temperature. The decrease in temperature affects the probability of accepting new solutions; as the temperature decreases, the probability of accepting worse solutions gradually decreases, which helps the method to finely search for the optimal solution in the later stages.

[0083] Iteration: At each temperature, the operations c (search phase) and d (acceptance criterion judgment phase) are repeated. This includes generating new process parameters, printing, calculating evaluation metrics, comparing the quality of the new and old solutions, and deciding whether to accept the new solution.

[0084] Record the optimal solution: In each iteration, if a better solution is found, record it as the current optimal solution. At the same time, keep track of the global optimal solution found so far.

[0085] Check termination conditions: After each iteration, check if the termination conditions are met. Termination conditions can be that the system temperature reaches a preset termination temperature, or that the predetermined total number of iterations has been reached. Once either condition is met, iteration will stop.

[0086] Output optimal process parameters: When iteration stops, output the current optimal gravure printing process parameters. These parameters represent the best process settings under the given evaluation criteria.

[0087] Example 2

[0088] The automatic optimization and adjustment method for gravure printing process parameters of this invention works as follows: First, an objective function for optimizing gravure printing process parameters is defined. This function comprehensively considers key indicators such as color registration accuracy, ink application consistency, and paper transport stability, quantitatively representing the quality level of the gravure print. Next, new process parameters are randomly searched within the gravure printing process parameter space, and the objective function value under the new process parameters is calculated to obtain a new process parameter evaluation index. If the new process parameter evaluation index value is better than the current optimal process parameter evaluation index, the new parameter setting is accepted; if it is worse than the current value, the new parameter setting is accepted or rejected according to the acceptance criterion. This probability decreases as the "temperature" decreases, thus ensuring that the system does not prematurely fall into a local optimum and helping to find a better solution globally. This allows for the search of the optimal or near-optimal set of process parameters globally.

[0089] The automatic optimization and adjustment method for gravure printing process parameters of the present invention has the following advantages:

[0090] 1) Improve gravure printing quality: Through precise optimization, the best combination of gravure printing process parameters can be found quickly, achieving optimal matching of color registration, ink volume control and paper feed speed. This fine control greatly reduces the color deviation, image blurring and other problems that may occur during the gravure printing process, thereby ensuring high-quality output of gravure printed products.

[0091] 2) Reduced operational difficulty: The traditional gravure printing parameter adjustment process relies on the experience of technicians and manual debugging, which is not only time-consuming but also inefficient. This invention reduces the dependence on manual skills through automatic optimization and adjustment, making the operation simpler, which helps to lower the technical threshold and reduce training costs.

[0092] 3) Enhanced adaptability and versatility: It is not only applicable to various gravure printing machines, but also capable of self-learning and adjusting to different gravure printing materials and operational requirements, thus enhancing the system's versatility and adaptability, making it particularly suitable for gravure printing fields that require high-quality output;

[0093] 4) Huge market potential: The optimization and adjustment method of this invention has broad market prospects. It can help various gravure printing companies improve production efficiency, save costs, and enhance the market competitiveness of their products.

[0094] Example 3

[0095] The automatic optimization and adjustment method for gravure printing process parameters of the present invention comprises the following steps:

[0096] a) Initialization phase:

[0097] 1) Determine initial process parameters: First, set initial values ​​for the gravure printing process parameters. These parameters include color registration deviation, ink volume, and paper feed speed. The initial values ​​for these parameters can be generated randomly.

[0098] 2) The initial temperature is set to 10000 to ensure that the search process can escape local optima and find the global optimum.

[0099] 3) Set the termination temperature to 100.

[0100] 4) Set the cooling rate to 10 to ensure that the optimal solution can be found within a reasonable time. The cooling process decreases linearly to determine the amount of temperature reduction after each iteration.

[0101] 5) Setting the total number of iterations to 70 can also be used as one of the termination conditions.

[0102] b) Evaluation phase:

[0103] 1) Gravure Printing: The current gravure printing process parameters are input into the gravure printing control system to control the actual gravure printing equipment to perform a printing process. This process involves actual operations such as ink transfer, paper feeding, and color layering.

[0104] 2) Quality Standard Setting: Before starting the evaluation, a set of quality standards needs to be preset based on the printing effect to assess various performance indicators of the printed products. The quality standards include image sharpness, color saturation, and color difference, and an objective function is constructed using a weighted sum. Represented as:

[0105]

[0106] in, It is the objective function value, representing a given vector of process parameters. The overall print quality assessment below is used to evaluate the print quality corresponding to these parameters. The evaluation index is image sharpness. Color saturation Color difference w1 represents the weight of image sharpness, w2 represents the weight of color saturation, and w3 represents the weight of color difference. We set w1 = 0.4, w2 = 0.3, and w3 = 0.3.

[0107] 3) Calculate the evaluation index: After printing is completed, calculate the gravure printing quality evaluation index (objective function) under the current process parameters according to the preset quality standards, and use it as the current optimal process parameter evaluation index. This includes the analysis of the printed image, such as measuring image sharpness, color saturation, color difference, etc., and taking the current process parameters as the current optimal solution.

[0108] c) Search phase:

[0109] 1) Generate a new combination of process parameters: Based on the current process parameters, a new set of process parameters is randomly generated. This is achieved by adding a small random perturbation value to the current process parameters, with the perturbation value being 30% of the current process parameter value. The magnitude of the perturbation is controlled by the system's temperature parameter; the perturbation range is larger when the temperature is higher and smaller when the temperature is lower.

[0110] 2) Applying new parameters for printing: Based on the new process parameters, input the new process parameters into the gravure printing control system to control the gravure printing equipment to perform another printing process.

[0111] 3) Based on the results of gravure printing, calculate the printing quality evaluation indicators under the new process parameters, such as image sharpness, color saturation, and color difference. These indicators will be used for subsequent acceptance criteria judgment.

[0112] 4) Record the new process parameters and the corresponding evaluation indicators of the new process parameters so as to compare them with the current optimal solution and the current optimal process parameter evaluation indicators, and use them for possible backtracking and analysis.

[0113] d) Acceptance criteria judgment:

[0114] The acceptance criterion determination stage is a crucial step in the method of this invention, as it determines whether to accept the new process parameters as the current solution. The following are the detailed steps and methods for the acceptance criterion determination stage:

[0115] 1) Comparative Evaluation Indicators: First, compare the evaluation indicators of the new process parameters with the current optimal process parameter evaluation indicators. These evaluation indicators include image sharpness, color saturation, color difference, etc.

[0116] 2) Determine the acceptance criteria:

[0117]

[0118] ΔE represents the difference between the evaluation index of the new process parameters and the evaluation index of the current optimal process parameters. It is calculated as the new process parameter evaluation index minus the current optimal process parameter evaluation index. If ΔE < 0, it means the evaluation index corresponding to the new process parameters is better than the evaluation index of the current optimal solution, and the acceptance criterion F = 1. The new process parameters will be unconditionally accepted as the new current optimal solution, and the current process parameters will be replaced by the new process parameters. If ΔE ≥ 0, it means the evaluation index of the new process parameters is worse than the evaluation index of the current optimal process parameters, and the acceptance criterion... At this point, the acceptance criterion determines whether to accept the new process parameters based on the calculated acceptance probability P.

[0119] 3) Calculate the acceptance probability: The acceptance probability is usually given by the following formula:

[0120]

[0121] In the formula, T is the current system temperature. The higher the temperature, the greater the probability of accepting a worse solution; the lower the temperature, the smaller the probability of accepting a worse solution; k is an adjustment constant, which can generally be taken as 1, and exp represents the natural exponent.

[0122] 4) Decide whether to accept new parameters: Decide whether to accept new parameters based on the calculated acceptance probability. Generate a random number between 0 and 1. If the random number is less than or equal to the acceptance probability P, then accept the new process parameters and update the current optimal solution. Replace the current process parameters with the new process parameters for use in the next iteration; otherwise, keep the current optimal solution unchanged.

[0123] Repeat the operations of c (search phase) and d (acceptance criterion judgment phase) until the number of iterations is met or the system temperature reaches the termination temperature, and output the latest current optimal solution corresponding to the current system temperature;

[0124] e) Temperature reduction and iteration:

[0125] The temperature reduction and iteration phase is responsible for controlling the search process to gradually approach the global optimum. The steps are as follows:

[0126] 1) Reduce temperature: Use a linear cooling method, gradually reducing the system temperature by 10% each time. The decrease in temperature will affect the probability of accepting new solutions; as the temperature decreases, the probability of accepting worse solutions gradually decreases.

[0127] 2) Iteration: At each temperature, repeat the operations of c (search phase) and d (acceptance criterion judgment phase). This includes generating new process parameters, printing, calculating evaluation indicators, comparing the quality of new and old solutions, and deciding whether to accept the new solution.

[0128] 4) Record the optimal solution: In each iteration, if a better solution is found, record it as the current optimal solution. At the same time, keep track of the global optimal solution found so far.

[0129] 5) Check Termination Condition: After each iteration, check whether the termination condition is met. The termination condition can be that the system temperature reaches a preset termination temperature, or that the predetermined number of iterations has been reached. Once either condition is met, the iteration will stop.

[0130] 6) Output optimal process parameters: When iteration stops, output the current optimal gravure printing process parameters. These parameters represent the best process settings found by this method under the given evaluation criteria.

Claims

1. A method for automatically optimizing and adjusting gravure printing process parameters, characterized in that, The steps are as follows: initialize process parameters and set start parameters and optimization termination conditions, preset quality standards and construct objective functions, obtain the current optimal process parameter evaluation index, randomly search for new process parameters, calculate the new process parameter evaluation index, output the new current optimal solution according to the acceptance criteria, until the optimization termination condition is met and the global optimal process parameters are output as the optimal solution combination of gravure printing process parameters, so as to control the printing press to achieve automatic adjustment; The specific steps are as follows: Step 1: Initialize process parameters and set initial temperature, cooling rate, number of iterations, and termination temperature; The optimization termination condition is: the number of iterations is met or the current temperature reaches the termination temperature; Step 2: Input the initialized process parameters and the set initial temperature, cooling rate, number of iterations, and termination temperature into the gravure printing control system to control the gravure printing equipment to perform one printing process. Based on the preset quality standards for printing effect, and using the form of weighted sum to construct the objective function, the gravure printing quality evaluation index under the current process parameters is calculated and used as the current optimal process parameter evaluation index, and the current process parameters are taken as the current optimal solution. Step 3: Generate new process parameters by random perturbation, complete one printing process, and use the objective function to calculate the gravure printing quality evaluation index under the new process parameters. Record the new process parameters and the corresponding evaluation index of the new process parameters. Step 4: Compare the evaluation index of the new process parameters with the evaluation index of the current optimal process parameters, and output the new current optimal solution according to the acceptance criteria; Step 5 and Step 4: After each output, determine whether the optimization termination condition is met. If it is met, output the global optimal process parameters directly. If not, gradually reduce the temperature according to the cooling rate. Repeat Step 3-4 once after each temperature reduction and output until the optimization termination condition is met. Output the global optimal process parameters as the optimal solution combination of gravure printing process parameters, thereby controlling the printing equipment to achieve automated adjustment. The process parameters include color registration deviation, ink volume, and paper feed speed. The quality standards include image sharpness, color saturation, and color difference; In step 4, the acceptance criteria are specifically as follows: （2） Where ∆E represents the difference between the evaluation index of the new process parameters and the evaluation index of the current optimal process parameters, calculated as the new process parameter evaluation index minus the current optimal process parameter evaluation index. If ∆E < 0, it indicates that the evaluation index of the new process parameters is better than the current optimal process parameter evaluation index, and the acceptance criterion F = 1. In this case, the new process parameters will be accepted as the new current optimal solution, and the current process parameters will be replaced by the new process parameters. If ∆E ≥ 0, it indicates that the evaluation index of the new process parameters is worse than the current optimal process parameter evaluation index, and the acceptance criterion F = 0. At this point, the acceptance criterion determines whether to accept the new process parameters based on the calculated acceptance probability P. The acceptance probability P is expressed as follows: T is the current temperature. The higher the temperature, the greater the probability of accepting a worse solution; the lower the temperature, the smaller the probability of accepting a worse solution. k is the adjustment constant, and exp represents the natural exponent. A random number between 0 and 1 is generated. If the random number is less than or equal to the acceptance probability P, the new process parameters are accepted and updated to the new current optimal solution, and the current process parameters are replaced with the new process parameters; otherwise, the current optimal solution is kept unchanged.

2. The method for automatically optimizing and adjusting gravure printing process parameters according to claim 1, characterized in that, The initialization specifically involves generating initial values ​​using a random generation method.

3. The automatic optimization and adjustment method for gravure printing process parameters according to claim 1, characterized in that, In step 2, the objective function is constructed using a weighted sum, and the expression for the objective function is: （1） in, It is the objective function value, representing a given vector of process parameters. Overall printing quality evaluation; It is the value of the i-th evaluation index; It is the weight of the i-th evaluation indicator.

4. The method for automatically optimizing and adjusting gravure printing process parameters according to claim 1, characterized in that, Step 3 specifically involves: Step 3.1: Based on the current process parameters, generate new process parameters through random perturbation; Step 3.2: Input the new process parameters into the gravure printing control system and control the gravure printing equipment to perform the printing process again; Step 3.3: Based on the results of gravure printing, calculate the printing quality evaluation index under the new process parameters using the objective function; Step 3.4: Record the new process parameters and the corresponding evaluation indicators for the new process parameters.

5. The automatic optimization and adjustment method for gravure printing process parameters according to claim 1 or 4, characterized in that, The random disturbance specifically refers to adding a small random disturbance value to the current process parameter, where the random disturbance value does not exceed 30% of the current process parameter value.

6. The method for automatically optimizing and adjusting gravure printing process parameters according to claim 1, characterized in that, The cooling process specifically involves gradually reducing the temperature using a linear cooling method based on the cooling rate.

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