A method of adjusting a doctor blade of a film printer

Abstract

The application discloses a doctor blade adjustment method of a film printing machine and belongs to the technical field of film printing. The method comprises the following steps: obtaining an adjustment trigger signal, including a film specification switching signal, a printing cylinder station switching signal, a printing speed change signal, a printing mode switching signal, a pressure deviation trigger signal and a prediction trigger signal based on a printing quality prediction model; determining a target parameter set containing a doctor blade height, a doctor blade angle and a doctor blade pressure according to the type of the trigger signal; calculating the parameter adjustment amount; retreating the doctor blade before adjustment; adjusting and detecting the deviation in real time according to the priority of the height, the angle and the pressure in sequence; repeating the adjustment and reducing the adjustment amount by a certain proportion each time when the deviation exists; sticking the doctor blade after the adjustment; verifying the target value through a sensor and compensating for the adjustment when the target value is not reached; and recording and updating the database. The doctor blade parameter is intelligently adjusted in a systematic way through the cooperation of multi-dimensional triggering, prediction and prediction, hierarchical iteration and closed-loop verification, and the printing quality is improved.

Description

Technical Field

[0001] This invention belongs to the field of thin film printing technology, and specifically relates to a method for adjusting the squeegee of a thin film printing machine. Background Technology

[0002] A film printing machine (also known as an electronic shaft gravure printing machine) is a specialized piece of equipment widely used for printing on plastic film packaging materials. It typically includes a feeding unit, a printing unit, a drying unit, and a take-up unit. After being output from the feeding unit, the film passes through each printing unit sequentially to complete the front and back patterns. After drying and curing, it is then wound up by the take-up unit into a finished product. In gravure printing, the surface of the printing cylinder is engraved with recessed areas for images. As the cylinder rotates, these recesses fill with ink. After a doctor blade removes excess ink from the blank areas, the impression cylinder transfers the ink from the recesses to the film surface, completing the printing process.

[0003] The doctor blade assembly is one of the core components of a gravure printing press, and the accuracy of its adjustment directly determines the print quality. Currently, some film printing presses are equipped with doctor blade adjustment devices, enabling mechanical or programmed adjustment of the doctor blade position and orientation. However, the above adjustment methods still have the following shortcomings: Squeegee adjustment is highly dependent on manual experience, with target values ​​largely relying on manual judgment and lacking standardized methods, making it difficult to guarantee consistent printing quality; the height, angle, and pressure of the squeegee lack coordinated adjustment, and due to the coupling relationship between these parameters, repeated adjustments and low efficiency are easily caused; squeegee adjustment lacks linkage with changes in equipment status, requiring manual parameter resetting when facing situations such as film specification changes, impression cylinder position changes, or printing speed changes, resulting in long changeover times; for double-sided printing, the squeegees on the front and back sides are installed in opposite directions, and the parameters of the two sides need to be set separately and affect each other, further increasing the difficulty of manual adjustment; in addition, there is a lack of quantitative verification of the adjustment effect after squeegee adjustment, usually requiring test printing to verify the effect, resulting in material waste; during squeegee use, wear also lacks intelligent compensation, often only being replaced after obvious quality problems occur, lacking a proactive compensation mechanism based on usage data.

[0004] To address the aforementioned problems, this invention provides a method for adjusting the squeegee of a film printing machine. By systematically and collaboratively adjusting the squeegee height, angle, and pressure, the squeegee can precisely scrape off excess ink from the surface of the printing cylinder, effectively improving the quality of film printing. Summary of the Invention

[0005] To address the aforementioned problems in the prior art, this invention provides a method for adjusting the squeegee of a film printing machine.

[0006] The objective of this invention can be achieved through the following technical solutions: A method for adjusting the squeegee of a film printing machine, the film printing machine including a first printing unit and a second printing unit, each printing unit being provided with a squeegee assembly, a lifting drive mechanism for driving the squeegee assembly to rise and fall, an angle adjustment mechanism for driving the squeegee assembly to rotate, a pressure adjustment mechanism for driving the squeegee assembly to press and retract, and a sensing component for detecting the actual state of the squeegee; the film printing machine also includes a rotatable and switchable impression cylinder mechanism, the impression cylinder mechanism having multiple stations for installing impression cylinders of different lengths; the film printing machine also includes a control system, the control system being communicatively connected to the sensing component, the lifting drive mechanism, the angle adjustment mechanism, and the pressure adjustment mechanism, respectively, including the following steps: Step S1: Obtain an adjustment trigger signal, which includes at least one of the following: film specification switching signal, impression cylinder station switching signal, printing speed change signal, printing mode switching signal, pressure deviation trigger signal, and prediction trigger signal; the prediction trigger signal is a signal generated based on a printing quality prediction model. Step S2: Determine the target parameter set for this adjustment based on the type of the adjustment trigger signal. The target parameter set includes at least one of the target value of the squeegee height, the target value of the squeegee angle, and the target value of the squeegee pressure. When the adjustment trigger signal is an impression cylinder station switching signal, determine the target value of the squeegee height based on the preset correspondence between the length of the impression cylinder and the working height of the squeegee, according to the length of the impression cylinder after switching. Step S3: Calculate the adjustment amount for each parameter based on the target parameter set and the current actual parameter values; Step S4: Before performing any adjustment action, the control system first retracts the squeegee from the printing cylinder surface through the pressure adjustment mechanism; then, based on the real-time parameters fed back by the sensing components, the control system performs adjustment actions in a preset priority order, sequentially adjusting the squeegee height, squeegee angle, and squeegee pressure to their respective target values. During the adjustment process, the sensing components detect in real time whether the adjusted parameters deviate due to subsequent adjustments. If a deviation occurs, the corresponding adjustment is repeated, and the adjustment amount is reduced by a preset ratio each time it is repeated, until all parameter deviations are within the allowable range or the number of iterations reaches the preset upper limit; after all adjustment actions are completed, the pressure adjustment mechanism slowly re-adheres the squeegee to the printing cylinder surface. Step S5: After performing each adjustment action, verify whether the actual parameters have reached the target value through the corresponding sensor. If the deviation exceeds the allowable range, make compensation adjustments. Step S6: Record the parameter data adjusted this time and update the equipment parameter database.

[0007] As a preferred embodiment of the present invention, the calculation method for the target value of the scraper pressure in step S3 is as follows: P_target=P_base×(V_current / V_standard)×K_width×K_ink×K_plate Wherein, P_base is the base pressure value, V_current is the current printing speed, V_standard is the standard printing speed, K_width is the width coefficient related to the film width, K_ink is the ink coefficient related to the ink viscosity, and K_plate is the plate coefficient related to the plate type.

[0008] As a preferred embodiment of the present invention, step S3 further includes an online ink characteristic detection step before calculating the target value of the doctor blade pressure: Viscosity and temperature sensors are installed in the ink tank to detect the viscosity and temperature of the ink in real time. Based on the detected ink viscosity η and ink temperature T, the ink coefficient K_ink is dynamically calculated: K_ink=K_ink_base×[1+β×(η-η_0) / η_0+γ×(T-T_0)] Where η_0 is the standard ink viscosity, T_0 is the standard ambient temperature, β is the viscosity influence coefficient, and γ is the temperature influence coefficient; When the ink viscosity changes beyond a preset threshold, the target values ​​for the doctor blade pressure and doctor blade angle are automatically corrected; the ink coefficient K_ink is updated periodically according to a preset update frequency, and the update frequency is not less than once per minute.

[0009] As a preferred embodiment of the present invention, when the adjustment trigger signal is a printing mode switching signal and the circuit is switched to double-sided printing mode: A first adjustment strategy is applied to the doctor blade of the first printing unit, and a second adjustment strategy is applied to the doctor blade of the second printing unit. In the first adjustment strategy and the second adjustment strategy, the installation direction of the scraper is opposite, the sign of the target value of the scraper angle is opposite, and the pressure target value of the scrapers on both sides is calculated independently according to the tension distribution of the film on both sides.

[0010] As a preferred embodiment of the present invention, it further includes a closed-loop optimization step for printing quality: During the printing process, image data of the printed matter is continuously acquired by an image sensor, and image features including density uniformity, number and width of squeegee lines, and dot sharpness are extracted. By correlating image features with current scraper parameters, a parameter-quality mapping relationship is established. When a slow deterioration trend in quality indicators is detected, a fine-tuning probe is conducted before triggering the formal adjustment: parameters are gradually adjusted with a preset step size, the direction of change in quality indicators is observed, and the optimal adjustment direction is determined before the formal adjustment is executed. The quality improvement effect after each adjustment is recorded in the database for use in optimizing subsequent adjustment strategies.

[0011] As a preferred technical solution of the present invention, the printing quality prediction model takes the current doctor blade usage time, cumulative number of ink scraping times, printing speed, ink viscosity, ambient temperature and ambient humidity as inputs, and outputs a predicted ink scraping quality score; when the predicted ink scraping quality score is lower than a preset threshold, a prediction trigger signal is automatically generated.

[0012] As a preferred technical solution of the present invention, the preset priority order in step S4 is as follows: first adjust the scraper height to the target value, then adjust the scraper angle to the target value, and finally adjust the scraper pressure to the target value.

[0013] As a preferred embodiment of the present invention, it further includes a strategy self-optimization step: After each complete adjustment process from steps S1 to S6, record the convergence time, number of iterations, and actual overshoot of each parameter. The convergence time, number of iterations, and overshoot are compared with historical adjustment data to evaluate the effectiveness of the current adjustment strategy. When the convergence time of consecutive adjustments exceeds a preset threshold or the number of iterations exceeds a preset number, the preset ratio is automatically adjusted to optimize the convergence efficiency of subsequent adjustments. The optimized adjustment strategy parameters are updated to the device parameter database for subsequent adjustment processes under the same type of trigger signal.

[0014] As a preferred embodiment of the present invention, the printing quality prediction model is an adaptive update model: After step S5 is completed, the current actual printing quality data is collected through the image sensor; The actual printing quality data is compared with the predicted ink scraping quality score used to generate this adjustment in step S1, and the prediction deviation is calculated. When the prediction deviation exceeds a preset threshold, the actual printing quality data is used as a labeling sample to correct the model parameters of the printing quality prediction model online. The corrected model parameters are updated in the device parameter database for use in the generation of subsequent prediction trigger signals.

[0015] Beneficial effects: This invention upgrades doctor blade adjustment from passive response to active prediction through a multi-dimensional triggering mechanism and predictive triggering signals. This enables real-time linkage between doctor blade adjustment and changes in working conditions such as film specification switching and printing cylinder station switching, shortening changeover time. Combined with a multi-parameter comprehensive calculation formula for doctor blade pressure target value and online detection and dynamic updating of ink characteristics, it achieves scientific quantitative determination of doctor blade pressure target value, eliminating reliance on manual experience.

[0016] By employing a safe execution logic of first retreating, then adjusting in layers, iterating over deviations, and finally bonding, and adjusting sequentially according to the priority order of height, angle, and pressure while detecting deviations in real time, the coupling problem between the three parameters is effectively solved, achieving rapid and accurate convergence. A closed-loop control is formed through sensor verification and compensation adjustment, and experience is digitally accumulated by combining data recording and database updates. The printing quality closed-loop optimization steps establish a parameter-quality mapping relationship through image acquisition and feature extraction, and perform fine-tuning exploration to determine the optimal adjustment direction when quality deteriorates, forming a complete intelligent closed loop.

[0017] The strategy self-optimization step records the convergence time, number of iterations, and overshoot and compares them with historical data. When the efficiency of repeated adjustments is not good, it automatically adjusts the preset ratio and updates the database, realizing the upgrade from parameter closed loop to strategy closed loop. The predictive model adaptive update step compares the actual printing quality data with the predicted score. When the prediction deviation exceeds the threshold, it uses the actual data as a labeled sample to correct the model parameters online, realizing the continuous self-evolution of the predictive model and significantly improving the consistency and stability of film printing quality. Attached Figure Description

[0018] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the accompanying drawings.

[0019] Figure 1 This is a schematic diagram of the main process steps of the film printing machine doctor blade adjustment method of the present invention; Figure 2 This is a schematic diagram of the self-optimization of the adjustment strategy and the adaptive update of the prediction model branch process of the present invention; Figure 3 This is a schematic diagram of the overall structure of the film printing machine and the film feeding process of the present invention; Figure 4 This is a partially enlarged schematic diagram of the doctor blade adjustment mechanism of the printing unit of the present invention.

[0020] Reference numerals: 1. First printing unit; 2. Second printing unit; 3. Squeegee assembly; 4. Lifting drive mechanism; 5. Angle adjustment mechanism; 6. Pressure adjustment mechanism; 7. Impression cylinder mechanism. Detailed Implementation

[0021] To further illustrate the technical means and effects adopted by the present invention to achieve the intended purpose, the following detailed description of the specific implementation methods, structures, features and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided.

[0022] Please see Figures 1 to 4 This invention provides a method for adjusting the squeegee in a film printing machine. The film printing machine used in this invention is an electronic shaft gravure printing machine, which includes a first printing unit 1 and a second printing unit 2. The film printing machine typically also includes a feeding unit, a drying unit, and a receiving unit. The first printing unit 1 is used to print the front side of the film, and the second printing unit 2 is used to print the back side of the film. After being output from the feeding unit, the film sequentially passes through the first printing unit 1 to complete the front side pattern printing. After the front side ink is dried by the drying air duct, it is reversed by the flipping guide roller and then passes through the second printing unit 2 to complete the back side pattern printing. After a second drying and curing process, it is wound up by the receiving unit into a finished product.

[0023] Each printing unit is equipped with a doctor blade assembly 3, a lifting drive mechanism 4 for raising and lowering the doctor blade assembly 3, an angle adjustment mechanism 5 for rotating the doctor blade assembly 3, a horizontal adjustment mechanism for moving the doctor blade assembly 3 horizontally, a pressure adjustment mechanism 6 for pressing and retracting the doctor blade assembly 3, and a sensor component for detecting the actual state of the doctor blade. The lifting drive mechanism 4 can employ a servo motor and lead screw drive structure to drive the doctor blade assembly 3 to rise and fall vertically, thereby adjusting the height of the doctor blade relative to the printing cylinder surface. The angle adjustment mechanism 5 can employ a servo motor and worm gear drive structure to drive the doctor blade assembly 3 to rotate around a horizontal axis, thereby adjusting the contact angle between the doctor blade and the printing cylinder surface. The horizontal adjustment mechanism drives the doctor blade assembly 3 to approach or move away from the printing cylinder surface horizontally, adjusting the doctor blade to the appropriate ink-scraping position according to the size of the printing cylinder. The pressure adjustment mechanism 6 can employ a cylinder drive structure, adjusting the pressure of the doctor blade pressing against the printing cylinder surface by controlling the air supply pressure of the cylinder, and realizing the pressing and retracting actions of the doctor blade.

[0024] The sensing components include at least a position sensor for detecting the actual height of the squeegee, an angle sensor for detecting the actual angle of the squeegee, and a pressure sensor for detecting the actual contact pressure between the squeegee and the printing plate cylinder. The film printing machine also includes a rotatable impression cylinder mechanism 7, which has multiple stations for mounting impression cylinders of different lengths. Each station can be pre-installed with impression cylinders of different lengths to accommodate film printing of different widths. The film printing machine also includes a control system, which is communicatively connected to the sensing components, the lifting drive mechanism 4, the angle adjustment mechanism 5, and the pressure adjustment mechanism 6. The control system receives detection signals from the sensing components and sends control commands to each drive mechanism to execute the method steps of the present invention.

[0025] The present invention provides a method for adjusting the squeegee of a film printing machine, comprising the following steps.

[0026] Step S1: Acquire adjustment trigger signals. The control system monitors and acquires various adjustment trigger signals in real time. These signals include at least one of the following: film specification switching signal, impression cylinder station switching signal, printing speed change signal, printing mode switching signal, pressure deviation trigger signal, and prediction trigger signal. By setting a multi-dimensional triggering mechanism including prediction trigger signals, this invention achieves diversified coverage of doctor blade adjustment trigger signals. Specifically, the film specification switching signal and impression cylinder station switching signal are used to address changes in printing requirements for films of different widths; the printing speed change signal is used to address changes in doctor blade pressure requirements caused by production speed adjustments; the printing mode switching signal is used to address mode switching between single-sided and double-sided printing; and the pressure deviation trigger signal is used to address real-time fluctuations in doctor blade pressure during the printing process. In particular, the introduction of prediction trigger signals allows doctor blade adjustment to move beyond simply responding to existing deviations. Instead, it enables early prediction of declining ink quality based on a printing quality prediction model, proactively triggering adjustments before actual deterioration in printing quality. This represents an upgrade from passive response-based adjustment to proactive prediction-based adjustment.

[0027] The film specification switching signal is generated when the operator selects to switch film width specifications through the human-machine interface, such as switching from narrow film to wide film or from medium film to narrow film. The impression cylinder station switching signal is generated when the impression cylinder mechanism 7 rotates to switch stations, such as switching from a station with a narrow impression cylinder to a station with a wide impression cylinder. The printing speed change signal is generated when the printing speed changes and the change exceeds a preset threshold. The printing mode switching signal is generated when switching between single-sided and double-sided printing modes. The pressure deviation trigger signal is generated when the deviation between the actual pressure value detected by the pressure sensor and the target pressure value exceeds a preset threshold. The prediction trigger signal is generated based on a printing quality prediction model. This model takes the current doctor blade usage time, cumulative number of doctor blade strokes, printing speed, ink viscosity, ambient temperature, and ambient humidity as inputs and outputs a predicted doctor blade quality score. A prediction trigger signal is automatically generated when the predicted doctor blade quality score is lower than a preset threshold.

[0028] Step S2: Determine the target parameter set for this adjustment based on the type of the adjustment trigger signal. After acquiring the adjustment trigger signal, the control system first identifies the type of the trigger signal, and then determines the target parameter set for this adjustment based on the type of the trigger signal. The target parameter set includes at least one of the target values ​​for squeegee height, squeegee angle, and squeegee pressure. Specifically, when the trigger signal is a film specification switching signal or an impression cylinder station switching signal, the target parameter set includes the target values ​​for squeegee height and squeegee pressure. When the trigger signal is a printing speed change signal, the target parameter set includes the target value for squeegee pressure. When the trigger signal is a printing mode switching signal, the target parameter set includes the target values ​​for the squeegee angle and squeegee pressure of the first printing unit 1 and the second printing unit 2. When the trigger signal is a pressure deviation trigger signal, the target parameter set includes the target value for squeegee pressure.

[0029] When the trigger signal is adjusted to the impression cylinder station switching signal, the target value of the squeegee height is determined based on the preset correspondence between the impression cylinder length and the squeegee working height, according to the changed impression cylinder length. This correspondence can be pre-stored in the parameter database of the control system. Different impression cylinder lengths correspond to different squeegee working heights to ensure that the squeegee can accurately act on the corresponding area of ​​the printing cylinder surface when printing films of different widths.

[0030] Step S3: Calculate the adjustment amount for each parameter based on the target parameter set and the current actual parameter values. This invention intelligently matches the corresponding target parameter set according to the type of trigger signal. Specifically: when the trigger signal is a film specification switching signal or an impression cylinder station switching signal, the adjustment targets include squeegee height and squeegee pressure to adapt to the changing requirements of different film widths on the squeegee's working position and contact area; when the trigger signal is a printing speed change signal, the adjustment target is squeegee pressure to adapt to the changes in squeegee pressure requirements caused by speed changes; when the trigger signal is a printing mode switching signal, the adjustment targets are the angle and pressure of the two squeegees to adapt to the different installation directions and working parameters of the front and back squeegees during double-sided printing; when the trigger signal is a pressure deviation trigger signal, the adjustment target is squeegee pressure to eliminate real-time pressure deviation. This method of determining the adjustment target based on the trigger type allows the squeegee adjustment to accurately respond to changes in different working conditions, avoiding blind and ineffective adjustments.

[0031] After determining the target parameter set, the control system obtains the actual values ​​of each parameter through the sensing components, and then calculates the difference between each target parameter value and the current actual parameter value as the adjustment amount for each parameter.

[0032] The target value of the scraper pressure is calculated as follows: P_target=P_base×(V_current / V_standard)×K_width×K_ink×K_plate Wherein, P_base is the base pressure value, ranging from 0.2 to 0.3 MPa; V_current is the current printing speed; V_standard is the standard printing speed; K_width is the width coefficient related to the film width. The larger the film width, the larger the contact area between the doctor blade and the printing cylinder, and the greater the width coefficient; K_ink is the ink coefficient related to ink viscosity; K_plate is the plate coefficient related to the printing plate type. For solid plate printing, the plate coefficient is 1.0 to 1.2, and for layered plate printing, the plate coefficient is 0.8 to 1.0.

[0033] Before calculating the target value of the doctor blade pressure, an online ink characteristic detection step is included. Viscosity and temperature sensors are installed in the ink tank to monitor the ink viscosity and temperature in real time. Based on the detected ink viscosity η and ink temperature T, the ink coefficient K_ink is dynamically calculated. K_ink=K_ink_base×[1+β×(η-η_0) / η_0+γ×(T-T_0)] Where η_0 is the standard ink viscosity, T_0 is the standard ambient temperature, β is the viscosity influence coefficient, and γ is the temperature influence coefficient. β is a positive value, generally ranging from 0.5 to 2.0, representing the relative adjustment ratio of the doctor blade pressure target value for every 10% change in ink viscosity relative to the standard viscosity; γ is a negative value, generally ranging from -0.015 to -0.005 / ℃, representing the relative adjustment ratio of the doctor blade pressure target value for every 1℃ change in ink temperature. Both β and γ are empirical fitting parameters and need to be determined experimentally for specific ink systems. The specific calibration method is as follows: at the standard printing speed, keeping other parameters constant, change the ink viscosity and ink temperature respectively, measure the minimum doctor blade pressure required to achieve the same ink-scraping effect, and obtain the values ​​of β and γ through curve fitting. β is determined by the slope of the viscosity-pressure curve, and γ is determined by the slope of the temperature-pressure curve. A goodness of fit R² of not less than 0.95 is considered a valid calibration. After calibration, the values ​​of β and γ are stored in the parameter database of the control system. When the ink viscosity changes beyond a preset threshold, the target values ​​for doctor blade pressure and doctor blade angle are automatically corrected. The ink coefficient K_ink is updated periodically according to a preset update frequency, with an update frequency of no less than once per minute, to ensure that the ink coefficient can reflect changes in ink characteristics in a timely manner.

[0034] During the printing process, when the ink viscosity increases due to solvent evaporation, β causes the control system to automatically increase the target value of the doctor blade pressure, ensuring that the doctor blade can penetrate the high-viscosity ink layer and scrape off excess ink. When the ink temperature rises due to heat generated by the equipment operation, γ causes the control system to automatically decrease the target value of the doctor blade pressure, preventing over-scraping due to a decrease in ink viscosity. Through the synergistic effect of β and γ, the doctor blade pressure can adaptively adjust in real time according to changes in the ink state, maintaining consistent scraping results and avoiding operational errors caused by manual adjustment based on intuition.

[0035] Step S4: Before performing any adjustment, the control system first retracts the doctor blade from the printing cylinder surface via the pressure regulating mechanism 6. This retraction action is to prevent accidental contact between the doctor blade and the printing cylinder during subsequent adjustments, which could cause scratches. Then, based on the real-time parameters fed back by the sensing components, the control system executes the adjustment actions in a preset priority order, sequentially adjusting the doctor blade height, doctor blade angle, and doctor blade pressure to their respective target values.

[0036] The preset priority order is as follows: first adjust the squeegee height to the target value, then adjust the squeegee angle to the target value, and finally adjust the squeegee pressure to the target value. The reason for adjusting in the order of height, angle, and pressure is that adjusting the squeegee height affects the contact angle between the squeegee and the printing cylinder, while adjusting the squeegee angle affects the pressure of the squeegee on the printing plate surface. Adjusting in this order can eliminate the coupling effect between parameters layer by layer.

[0037] During the adjustment process, the control system uses sensors to detect in real time whether the adjusted parameters deviate due to subsequent adjustments. For example, adjusting the squeegee angle may cause a slight change in the previously adjusted squeegee height; adjusting the squeegee pressure may cause a slight change in the previously adjusted squeegee angle. If a deviation is detected in the adjusted parameters due to subsequent adjustments, the corresponding adjustment is repeated. Specifically, the adjustment amount is reduced by a preset ratio with each repetition until all parameter deviations are within the allowable range or the number of iterations reaches a preset upper limit. After all adjustments are completed, the pressure regulating mechanism 6 slowly presses the squeegee against the printing cylinder surface, completing the adjustment process.

[0038] This invention solves the coupling problem between the three parameters of doctor blade height, angle, and pressure through a safe execution logic of first withdrawing, then adjusting in layers, iterating over deviations, and finally re-adhering. Specifically, the height, angle, and pressure are adjusted sequentially according to their priority: first the height to the target value, then the angle, and finally the pressure. This order is chosen because adjusting the doctor blade height changes the position of the doctor blade relative to the printing cylinder surface, thus affecting the contact angle between the doctor blade and the printing cylinder; adjusting the doctor blade angle changes the doctor blade's adhesion posture to the printing plate surface, thus affecting the contact pressure. Adjusting in layers according to the order of height, angle, and pressure effectively eliminates the coupling effect between parameters and avoids repeated oscillations. During the adjustment process, it is monitored in real time whether the adjusted parameters deviate due to subsequent adjustments. If a deviation occurs, the corresponding adjustment is repeated, with the adjustment amount reduced by a preset ratio each time, until all parameter deviations are within the allowable range or the number of iterations reaches a preset upper limit. This layered iterative logic ensures rapid and accurate convergence of multi-parameter coordinated adjustments.

[0039] Step S5: After performing each adjustment action, verify whether the actual parameters have reached the target values ​​using the corresponding sensors. Specifically, verify whether the scraper height has reached the target height value using the position sensor, whether the scraper angle has reached the target angle value using the angle sensor, and whether the scraper pressure has reached the target pressure value using the pressure sensor. If the deviation of any parameter exceeds the allowable range, make compensation adjustments until all parameters reach the target value or are within the allowable range.

[0040] Step S6: Record the parameter data for this adjustment and update the equipment parameter database. The control system records and stores data such as the trigger signal type, target values ​​of each parameter, actual values ​​before adjustment, actual values ​​after adjustment, number of iterations during adjustment, and verification results after adjustment in the equipment parameter database for reference in subsequent adjustment processes under the same type of trigger signal.

[0041] When the adjustment trigger signal is a printing mode switching signal and the printing mode is switched to double-sided printing, a first adjustment strategy is executed on the squeegee of the first printing unit 1, and a second adjustment strategy is executed on the squeegee of the second printing unit 2. In the first and second adjustment strategies, the squeegee installation directions are opposite, that is, the squeegee of the first printing unit 1 is installed in front for printing the front side of the film, and the squeegee of the second printing unit 2 is installed in the rear for printing the back side of the film. The signs of the squeegee angle target values ​​are opposite, and the pressure target values ​​of the two squeegees are calculated independently based on the tension distribution of the film on both sides.

[0042] This invention also includes a closed-loop optimization step for printing quality. During the printing process, image data of the printed material is continuously acquired using an image sensor, and image features, including density uniformity, the number and width of squeegee lines, and dot sharpness, are extracted. These image features are correlated with the current squeegee parameters to establish a parameter-quality mapping relationship. When a slow deterioration trend in quality indicators is detected, such as a decrease in density uniformity of more than 5% within 100 meters of continuous printing, a fine-tuning probe is performed before triggering formal adjustments: parameters are gradually adjusted with a preset step size, the direction of change in quality indicators is observed, and the optimal adjustment direction is determined before formal adjustments are executed. The quality improvement effect after each adjustment is recorded in a database for optimizing subsequent adjustment strategies.

[0043] This embodiment of the invention also includes a self-optimization step for the adjustment strategy. After each complete adjustment process from steps S1 to S6, the convergence time, number of iterations, and actual overshoot of each parameter are recorded. The convergence time, number of iterations, and overshoot are compared with historical adjustment data to evaluate the effectiveness of the current adjustment strategy. When the convergence time of multiple consecutive adjustments exceeds a preset threshold or the number of iterations exceeds a preset number, the preset ratio described in step S4 is automatically adjusted to optimize the convergence efficiency of subsequent adjustments. The optimized adjustment strategy parameters are updated to the device parameter database for use in subsequent adjustment processes under the same type of trigger signal.

[0044] In this embodiment of the invention, the printing quality prediction model is an adaptive update model. After executing step S5, the current actual printing quality data is collected through an image sensor. The actual printing quality data is compared with the predicted ink scraping quality score used to generate this adjustment in step S1, and the prediction deviation is calculated. When the prediction deviation exceeds a preset threshold, the actual printing quality data is used as a label sample to correct the model parameters of the printing quality prediction model online. The corrected model parameters are updated to the equipment parameter database for use in the generation of subsequent prediction trigger signals.

[0045] In a specific application example of this invention, an electronic shaft gravure printing machine is used to perform double-sided printing on a polyethylene film with a width of 800 millimeters. For example... Figure 3 As shown, the feeding unit outputs polyethylene film, which passes through the first printing unit 1 to complete the front pattern printing. After the front ink is dried by the drying air duct, it is reversed by the flipping guide roller and then passes through the second printing unit 2 to complete the reverse pattern printing. After a second drying and curing, it is wound up by the receiving unit into a finished product.

[0046] During the printing process, when the operator switches the film size from 800 mm to 1000 mm, the control system receives the film size switching signal and controls the impression cylinder mechanism 7 to rotate and switch to the station equipped with the 1000 mm long impression cylinder. After the impression cylinder station switch is completed, the control system receives the impression cylinder station switch signal, determines the corresponding target value of the squeegee height after the switch based on the preset correspondence between the impression cylinder length and the squeegee working height, and obtains the current actual pressure value through the pressure sensor to calculate the pressure adjustment amount. At this time, the film size switching signal, as a concrete manifestation of the multi-dimensional triggering mechanism, triggers the entire adjustment process.

[0047] The control system first retracts the doctor blade from the printing cylinder surface via the pressure regulating mechanism 6. Then, it adjusts the height, angle, and pressure sequentially according to their priority, detecting deviations in real time during the adjustment process. If a slight deviation in height is detected when adjusting the angle, the height adjustment is immediately repeated; if a slight deviation in angle is detected when adjusting the pressure, the angle adjustment is immediately repeated, until all parameters reach the target values. This hierarchical iterative adjustment logic ensures the coordinated convergence of the three parameters during the switching process.

[0048] After adjustment, sensors are used to verify whether each parameter has reached the target value, and data such as the trigger signal type, target and actual values ​​of each parameter, and number of iterations are recorded, and the database is updated. Sensor verification ensures adjustment accuracy, and data recording accumulates experience data for subsequent similar switches.

[0049] In the above process, the multi-dimensional triggering mechanism initiated the adjustment at the right time, the hierarchical iteration logic executed the adjustment in the right way, the closed-loop verification ensured that the adjustment achieved the expected accuracy, and the data recording enabled the accumulation and reuse of adjustment experience. The four features worked together to achieve rapid and accurate adjustment in the production changeover process. The entire process required no manual intervention, the production changeover time was greatly shortened, and the consistency and stability of printing quality were significantly improved.

[0050] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for adjusting the squeegee of a film printing machine, the film printing machine comprising a first printing unit and a second printing unit, each printing unit being provided with a squeegee assembly, a lifting drive mechanism for driving the squeegee assembly to rise and fall, an angle adjustment mechanism for driving the squeegee assembly to rotate, a pressure adjustment mechanism for driving the squeegee assembly to press and retract, and a sensing component for detecting the actual state of the squeegee; the film printing machine further comprising a rotatable and switchable impression cylinder mechanism, the impression cylinder mechanism having multiple stations for installing impression cylinders of different lengths; the film printing machine further comprising a control system, the control system being communicatively connected to the sensing component, the lifting drive mechanism, the angle adjustment mechanism, and the pressure adjustment mechanism, characterized in that... Includes the following steps: Step S1: Obtain an adjustment trigger signal, which includes at least one of the following: film specification switching signal, impression cylinder station switching signal, printing speed change signal, printing mode switching signal, pressure deviation trigger signal, and prediction trigger signal; the prediction trigger signal is a signal generated based on a printing quality prediction model. Step S2: Determine the target parameter set for this adjustment based on the type of the adjustment trigger signal. The target parameter set includes at least one of the target value of the squeegee height, the target value of the squeegee angle, and the target value of the squeegee pressure. When the adjustment trigger signal is an impression cylinder station switching signal, determine the target value of the squeegee height based on the preset correspondence between the length of the impression cylinder and the working height of the squeegee, according to the length of the impression cylinder after switching. Step S3: Calculate the adjustment amount for each parameter based on the target parameter set and the current actual parameter values; Step S4: Before performing any adjustment action, the control system first retracts the squeegee from the surface of the printing cylinder through the pressure regulating mechanism; then, the control system performs adjustment actions according to the real-time parameters fed back by the sensing components and in a preset priority order, adjusting the squeegee height, squeegee angle and squeegee pressure to their respective target values ​​in sequence. During the adjustment process, the sensing components detect in real time whether the adjusted parameters have deviated due to subsequent adjustments. If a deviation occurs, the corresponding adjustment is repeated, and the adjustment amount is reduced by a preset ratio each time it is repeated, until all parameter deviations are within the allowable range or the number of iterations reaches the preset upper limit. After all adjustments are completed, the doctor blade is slowly pressed against the surface of the printing cylinder using the pressure adjustment mechanism. Step S5: After performing each adjustment action, verify whether the actual parameters have reached the target value through the corresponding sensor. If the deviation exceeds the allowable range, make compensation adjustments. Step S6: Record the parameter data adjusted this time and update the equipment parameter database.

2. The method for adjusting the squeegee of a film printing machine according to claim 1, characterized in that, The calculation method for the target value of the scraper pressure in step S3 is as follows: P_target=P_base×(V_current / V_standard)×K_width×K_ink×K_plate Wherein, P_base is the base pressure value, V_current is the current printing speed, V_standard is the standard printing speed, K_width is the width coefficient related to the film width, K_ink is the ink coefficient related to the ink viscosity, and K_plate is the plate coefficient related to the plate type.

3. The method for adjusting the squeegee of a film printing machine according to claim 2, characterized in that, In step S3, before calculating the target value of the doctor blade pressure, an online ink characteristic detection step is also included: Viscosity and temperature sensors are installed in the ink tank to detect the viscosity and temperature of the ink in real time. Based on the detected ink viscosity η and ink temperature T, the ink coefficient K_ink is dynamically calculated: K_ink=K_ink_base×[1+β×(η-η_0) / η_0+γ×(T-T_0)] Where η_0 is the standard ink viscosity, T_0 is the standard ambient temperature, β is the viscosity influence coefficient, and γ is the temperature influence coefficient; When the ink viscosity changes beyond a preset threshold, the target values ​​for the doctor blade pressure and doctor blade angle are automatically corrected; the ink coefficient K_ink is updated periodically according to a preset update frequency, and the update frequency is not less than once per minute.

4. The method for adjusting the squeegee of a film printing machine according to claim 1, characterized in that, When the adjustment trigger signal is a printing mode switching signal and the system switches to double-sided printing mode: A first adjustment strategy is applied to the doctor blade of the first printing unit, and a second adjustment strategy is applied to the doctor blade of the second printing unit. In the first adjustment strategy and the second adjustment strategy, the installation direction of the scraper is opposite, the sign of the target value of the scraper angle is opposite, and the pressure target value of the scrapers on both sides is calculated independently according to the tension distribution of the film on both sides.

5. The method for adjusting the squeegee of a film printing machine according to claim 1, characterized in that, It also includes a closed-loop optimization step for print quality: During the printing process, image data of the printed matter is continuously acquired by an image sensor, and image features including density uniformity, number and width of squeegee lines, and dot sharpness are extracted. By correlating image features with current scraper parameters, a parameter-quality mapping relationship is established. When a slow deterioration trend in quality indicators is detected, a fine-tuning probe is conducted before triggering the formal adjustment: parameters are gradually adjusted with a preset step size, the direction of change in quality indicators is observed, and the optimal adjustment direction is determined before the formal adjustment is executed. The quality improvement effect after each adjustment is recorded in the database for use in optimizing subsequent adjustment strategies.

6. The method for adjusting the squeegee of a film printing machine according to claim 1, characterized in that, The printing quality prediction model takes the current doctor blade usage time, cumulative number of ink scrapings, printing speed, ink viscosity, ambient temperature, and ambient humidity as inputs, and outputs a predicted ink scraping quality score; when the predicted ink scraping quality score is lower than a preset threshold, a prediction trigger signal is automatically generated.

7. The method for adjusting the squeegee of a film printing machine according to claim 1, characterized in that, The preset priority order in step S4 is as follows: first adjust the scraper height to the target value, then adjust the scraper angle to the target value, and finally adjust the scraper pressure to the target value.

8. The method for adjusting the squeegee of a film printing machine according to claim 7, characterized in that, It also includes adjusting the strategy self-optimization steps: After each complete adjustment process from steps S1 to S6, record the convergence time, number of iterations, and actual overshoot of each parameter. The convergence time, number of iterations, and overshoot are compared with historical adjustment data to evaluate the effectiveness of the current adjustment strategy. When the convergence time of consecutive adjustments exceeds a preset threshold or the number of iterations exceeds a preset number, the preset ratio is automatically adjusted to optimize the convergence efficiency of subsequent adjustments. The optimized adjustment strategy parameters are updated to the device parameter database for subsequent adjustment processes under the same type of trigger signal.

9. A method for adjusting the squeegee of a film printing machine according to claim 6, characterized in that, The printing quality prediction model is an adaptive update model: After step S5 is completed, the current actual printing quality data is collected through the image sensor; The actual printing quality data is compared with the predicted ink scraping quality score used to generate this adjustment in step S1, and the prediction deviation is calculated. When the prediction deviation exceeds a preset threshold, the actual printing quality data is used as a labeling sample to correct the model parameters of the printing quality prediction model online. The corrected model parameters are updated in the device parameter database for use in the generation of subsequent prediction trigger signals.

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