On-line diaphragm coating quality adjusting method

Abstract

The invention discloses a coated diaphragm quality online adjusting method. The method comprises gravure coating thickness control and regular spot coating morphology control. In gravure coating thickness control, firstly, an optimal gap value is automatically matched, then online dynamic compensation and real-time gap adjustment are carried out according to the tested coating thickness, meanwhile, the service life of a scraper is predicted, and active early warning and replacement prompting are carried out before the scraper is completely invalid; in regular spot coating morphology control, firstly, the distance between a back roller and a rubber roller is finely adjusted in a manual inching mode, the distance value at the moment is detected through a digital distance meter, then the machine is started for trial coating, the spot morphology is subjected to imaging monitoring and analysis through a CCD system, whether the morphology of a trial coating film roll meets the requirement or not is judged, and if yes, regular spot coating is finished. And if the requirements are met, point coating operation is carried out based on the gap set value, and if the morphology is abnormal and does not meet the requirements, the distance is finely adjusted again until the requirements are met. Manual intervention is reduced through double-system automatic control, and the consistency of coated products is improved through dynamic compensation.

Description

Technical Field

[0001] This invention relates to a method for online adjustment of the quality of coated separators, belonging to the field of regular coating technology for lithium battery separators. Background Technology

[0002] In the regular coating of lithium battery separators, existing coating methods have significant drawbacks, limiting process efficiency and consistency. Specifically, in gravure coating thickness control methods, the current doctor blade gap setting after replacement relies entirely on operator experience and requires multiple offline measurements for calibration, resulting in low efficiency. Furthermore, traditional mechanical locking structures set the doctor blade gap to a fixed static parameter, which cannot cope with the gradual expansion of the slurry channel caused by wear on the doctor blade working surface, leading to continuous fluctuations in coating thickness and forcing frequent shutdowns for adjustment. In regular dot coating morphology control methods, the adjustment of the back roller distance relies on manual trial coating iterations and offline observation, which is time-consuming and generates a large amount of waste film. Moreover, existing methods completely lack online sensing and real-time compensation capabilities for dynamic distance offsets caused by mechanical vibration, roller thermal expansion, and other factors during the coating process, leading to dot matrix defects.

[0003] The shortcomings of these methods have become the main bottleneck in achieving large-scale production of highly consistent regular coated diaphragms. Summary of the Invention

[0004] The purpose of this invention is to provide an online method for adjusting the quality of coated diaphragms. This method reduces manual intervention through dual-system automatic control and improves the consistency of coated products through dynamic compensation. In the gravure coating thickness control system, servo closed-loop drive is used to achieve automatic calibration of the gap between the material box and the gravure roller, and real-time wear compensation, ensuring coating thickness fluctuations are ≤±0.2μm. In the regular dot coating morphology control system, a digital rangefinder monitors the distance between the glue roller and the back roller in real time, and an online CCD vision system captures the morphology of the coating dots in real time, automatically triggering millisecond-level dynamic compensation to eliminate dot diameter / spacing deviations.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is: an online adjustment method for the quality of coated diaphragms, characterized in that it includes gravure coating thickness control and regular dot coating morphology control;

[0006] The method for controlling the thickness of the gravure coating is as follows: First, the optimal gap value is automatically matched according to the process formula. Then, the gap is adjusted in real time by online dynamic compensation based on the tested coating thickness. At the same time, the service life of the scraper is predicted by monitoring the amount of adjustment. The scraper is given an early warning before it completely fails and is prompted to be replaced.

[0007] The method for controlling the morphology of the regular dot coating is as follows: First, the servo motor is manually operated to fine-tune the distance between the back roller and the glue roller, and the distance value at this time is detected by a digital rangefinder. Then, the machine is turned on for trial coating, and the dot morphology after coating is monitored online, continuously, and in real time by a CCD system. The collected images are analyzed in real time to determine whether the morphology of the trial coated film roll meets the requirements. If it meets the requirements, the distance parameter is set, and the dot coating operation is performed based on the set distance value. If the morphology is abnormal and does not meet the requirements, the distance is readjusted until the requirements are met.

[0008] Furthermore, in the control of the gravure coating thickness, a process formula database of key parameters associated with the coating is pre-established through testing and practical experience. After the doctor blade is replaced, the system automatically extracts and matches the preset optimal gap parameters from the formula database based on the input doctor blade parameters.

[0009] Furthermore, in the control of the gravure coating thickness, a high-precision online thickness gauge is integrated to continuously detect the thickness of the coated diaphragm in real time.

[0010] Furthermore, if the detected coating thickness is within the required range, the equipment continues to produce stably; if the detected coating thickness is not within the required range, the deviation between the current thickness and the target value is calculated based on the real-time thickness data, and then the gap between the material box and the gravure roller is dynamically adjusted to ensure that the coating thickness always meets the requirements.

[0011] Furthermore, the gap between the material box and the gravure roller is adjusted by a gravure roller-material box adjusting servo motor in conjunction with a slide rail. Dynamic adjustment is achieved by generating compensation commands to the servo motor through a coating thickness compensation algorithm model. The coating thickness compensation algorithm model is defined as follows:

[0012] The coating thickness y(t) is dominated by the slurry channel gap h(t):

[0013] y(t)=k*h(t)+d(t)

[0014] in,

[0015] k - Slurry transfer coefficient;

[0016] h(t) - Dynamic gap, i.e., the distance between the material box and the gravure roller, in μm;

[0017] d(t) - external disturbance;

[0018] The scraper wear δw(t) causes a time-varying expansion of the gap h(t):

[0019] h(t) = h0 + u(t) + δw(t)

[0020] in,

[0021] h0 - Initial gap setting;

[0022] u(t) - Servo motor compensation displacement;

[0023] δw(t) - wear depth, a monotonically increasing function, δw(t)≥0;

[0024] Set the target thickness γ, and the real-time deviation is:

[0025] e(t) = γ - y(t)

[0026] Using a proportional-integral (PI) control law:

[0027]

[0028] K p -Proportional gain;

[0029] K i -Integral gain;

[0030] Combining the above models, we obtain the expression for the thickness dynamic compensation model:

[0031]

[0032] in:

[0033] k*h0 - The reference thickness determined by the initial set gap;

[0034] k*K p *(γ-y(t))-Proportional control: Real-time countermeasure against thickness fluctuations;

[0035] -Integral control: progressively compensates for systematic deviations caused by scraper wear δw(t);

[0036] k*δw(t) - Thickness drift caused by scraper wear.

[0037] Furthermore, by continuously monitoring and recording the dynamic displacement of the servo motor to compensate for scraper wear, a safe threshold for the displacement is set based on the scraper life and process requirements. When the monitored displacement approaches or reaches the preset threshold, the system automatically triggers an audible and visual alarm signal, proactively providing a warning and prompting replacement before the scraper completely fails.

[0038] Furthermore, in the rule-based dot-matrix morphology control, if the morphology is abnormal and does not meet the requirements, the spacing is readjusted by manual dot-matrix operation or by feedback dynamic compensation.

[0039] Furthermore, the acquired images are analyzed in real time. When a morphological defect or key parameter exceeds the allowable range, a compensation command is generated in real time. The compensation command instantly triggers the rubber roller-back roller pitch adjustment servo motor to finely adjust the distance between the rubber roller and the back roller.

[0040] Furthermore, one servo motor for adjusting the distance between the rubber roller and the back roller is installed on each of the left and right sides of the frame, and together with the slide rail, the left and right sides of the rubber roller and the back roller can be adjusted independently.

[0041] The beneficial effects of this invention are as follows:

[0042] (1) Regarding the gravure coating thickness control system:

[0043] 1) Solves the waste of materials and time caused by repeated trial coatings after blade replacement: Completely replaces the method of multiple trial coating iterations and offline measurement that relies on operator experience, and realizes "one-click" accurate initial setting of gap parameters, significantly improving blade replacement efficiency and reducing material waste.

[0044] 2) Solving the problem of thickness drift caused by scraper wear: ① Integrating an online thickness gauge to detect thickness in real time, and feeding back to the servo motor of the material box to dynamically compensate for scraper wear, ensuring thickness fluctuation ≤ ±0.2μm, improving product consistency. ② Actively preventing scraper failure by monitoring the servo motor displacement to reach a safety threshold. When the limit value is reached, an audible and visual alarm is automatically triggered and a replacement scraper is prompted, achieving predictive maintenance.

[0045] (2) Regarding the rule-based dot painting morphology control system:

[0046] 1) Upgrading existing equipment solution with servo-driven distance adjustment and human-machine interaction: A contact digital rangefinder replaces the dial indicator to improve the distance adjustment test error, and a servo motor replaces the existing mechanical crank to achieve precise adjustment of the roller gap. This enables precise control of the servo motor, real-time display and storage of operating data to build a complete quality traceability and process optimization database.

[0047] 2) Online visual closed-loop control and dynamic compensation improve the consistency of coating point morphology: The CCD vision system captures the morphology of coating points in real time, automatically identifies abnormal point diameter, spacing deviation, adhesion, and missing coating defects, and instantly triggers dynamic interference compensation of servo motors to improve the consistency of coating point morphology. Attached Figure Description

[0048] Figure 1 Flowchart of the online adjustment method for coating diaphragm quality.

[0049] Figure 2 Left view of the online diaphragm coating quality adjustment device;

[0050] In the diagram, 1-coating unit; 2-online thickness gauge; 3-CCD vision inspection instrument; 4-transition unit.

[0051] Figure 3 A front and side view of an online equipment for adjusting the quality of coated diaphragms.

[0052] Figure 4 This is a structural diagram of the coating unit;

[0053] In the diagram, 101-back roller drive motor; 102-back roller coupling; 103-frame; 104-pass roller; 105-back roller; 106-rubber roller; 107-gravure roller; 108-material box mechanism; 109-contact digital rangefinder; 110-dial indicator; 111-back roller drive motor; 112-rubber roller-back roller gap adjustment servo motor; 113-rubber roller mechanism moving slide rail; 114-gravure roller material box mechanism moving slide rail; 115-material box mechanism forward cylinder; 116-gravure roller-material box gap adjustment servo motor; 117-receiving tray; 118-gravure roller material box mechanism support; 119-rubber roller mechanism support; 120-rubber roller drive motor.

[0054] Figure 5 This is a diagram of the interface for adjusting the distance between the rubber roller and the back roller. Detailed Implementation

[0055] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0056] like Figures 1 to 5 As shown, an online method for adjusting the quality of a coated diaphragm includes gravure coating thickness control and regular dot coating morphology control.

[0057] The implementation steps of the gravure coating thickness control system are as follows:

[0058] First, the system automatically matches the optimal gap value based on the set process formula: A process formula database with associated key parameters (doctor blade type, slurry characteristics, gravure roller type, etc.) is pre-established through testing and practical experience. After changing the doctor blade, the system automatically extracts and matches the preset optimal gap parameter from the formula database based on the input doctor blade type and other key parameters. The optimal gap is related to the doctor blade type, slurry characteristics, gravure roller type, etc., and the relationship is not linear. This was verified through extensive on-site process debugging records. The table below shows some process formula data:

[0059]

[0060] Then, based on the online dynamic compensation of the tested coating thickness, the gap is adjusted in real time: an integrated high-precision online thickness gauge is used to continuously detect the thickness of the coated diaphragm. If the product thickness is within the required range, the equipment will continue to produce stably. If the liquid volume changes due to wear of the scraper, causing the product to approach the thickness deviation range, the system will calculate the deviation between the current thickness and the target value (e.g., ±0.2μm) in real time based on the thickness data, and then generate a compensation command to the servo motor to fine-tune the position of the material box mechanism (i.e., the gap between the material box and the gravure roller), achieving dynamic adjustment so that the coating thickness always meets the quality requirements.

[0061] Simultaneously, displacement monitoring is used to predict the lifespan of the scraper: the dynamic displacement (cumulative compensation) of the servo motor to compensate for scraper wear is continuously monitored and recorded. A safe displacement threshold is set based on scraper lifespan and process requirements. When the monitored cumulative displacement approaches or reaches the preset threshold, the system automatically triggers an audible and visual alarm signal, proactively warning and prompting replacement before the scraper completely fails, thus avoiding quality accidents or equipment damage and downtime caused by sudden failure. Currently, the 30mm wide scrapers used in the field typically have a safe length threshold of 5mm from the gravure roller to the inner wall of the material box.

[0062] In this embodiment, the gap between the material box and the gravure roller is adjusted by a gravure roller-material box adjusting servo motor in conjunction with a slide rail. Dynamic adjustment is achieved by generating compensation commands to the servo motor through a coating thickness compensation algorithm model. The coating thickness compensation algorithm model is defined as follows:

[0063] The coating thickness y(t) is dominated by the slurry channel gap h(t):

[0064] y(t)=k*h(t)+d(t)

[0065] in,

[0066] k - Slurry transfer coefficient (related to slurry viscosity, gravure roller mesh depth, etc.);

[0067] h(t) - Dynamic gap (distance between the material box and the gravure roller, in μm);

[0068] d(t) - External disturbances (environmental fluctuations, changes in substrate tension, etc.);

[0069] The scraper wear δw(t) causes a time-varying expansion of the gap h(t):

[0070] h(t) = h0 + u(t) + δw(t)

[0071] in,

[0072] h0 - Initial gap setting (set according to the above process formula, obtained through experience accumulation);

[0073] u(t) - Servo motor compensation displacement;

[0074] δw(t) - wear depth (monotonically increasing function, δw(t)≥0);

[0075] Set the target thickness γ, and the real-time deviation is:

[0076] e(t) = γ - y(t)

[0077] Employing a proportional-integral (PI) control law (balancing response speed and steady-state accuracy):

[0078]

[0079] K p - Proportional gain (for fast response to current deviation);

[0080] K i - Integral gain (eliminating historical accumulated bias);

[0081] Combining the above models, we obtain the theoretical expression for the thickness dynamic compensation system:

[0082]

[0083] in:

[0084] k*h0 - The reference thickness determined by the initial set gap;

[0085] k*K p *(γ-y(t))-Proportional control: Real-time countermeasures against thickness fluctuations (such as sudden disturbances like vibration);

[0086] -Integral control: Gradually compensates for systematic deviations caused by scraper wear δw(t);

[0087] k*δw(t) - Thickness drift caused by scraper wear (actively canceled by the integral term).

[0088] The implementation steps of the rule-based dot-matrix morphology control system are as follows:

[0089] First, the servo motor is manually jogged to fine-tune the distance between the back roller and the glue roller. The distance value is then detected by a digital rangefinder. After that, a trial coating is performed, and the morphology of the coated dots is monitored online, continuously, and in real time by a CCD system. The acquired images are analyzed in real time to determine whether the morphology of the trial coated film roll meets the requirements. If it does, the distance parameter is set, and the dot coating operation is performed based on the set distance value. If the morphology is abnormal and does not meet the requirements, the distance is readjusted until the requirements are met.

[0090] In this embodiment, if the morphological abnormalities do not meet the requirements, the spacing can be fine-tuned manually or through feedback dynamic compensation. The feedback dynamic compensation method involves real-time identification and analysis of the acquired images. When morphological defects or key parameters exceeding the allowable range are detected, a compensation command is generated instantly. This compensation command immediately triggers the rubber roller-back roller spacing servo motor to fine-tune the spacing between the rubber roller and the back roller.

[0091] In this embodiment, one servo motor for adjusting the distance between the rubber roller and the back roller is provided on each of the left and right sides of the frame, and together with the slide rail, the left and right sides of the rubber roller and the back roller are adjusted separately.

[0092] like Figure 5 The coating spacing can be adjusted via the user interface, including functions such as left and right spacing adjustment, manual movement, spacing setting, and spacing change data.

[0093] "Servo Enable" - "ON" means servo control is on, "OFF" means servo control is off;

[0094] "Displacement sensor", "left and right distance" - Real-time displacement data is detected through contact displacement sensors;

[0095] "Manual Movement" - Manually adjust the distance between the rubber roller and the back roller by "Forward" and "Backward";

[0096] "Gap Setting" - Manually move and adjust. Set after the morphology of the test coating roll meets the requirements. This position indicates that it is the initial position of the process.

[0097] "Servo Adjustment" - ON means that the servo motor adjusts the spacing in real time through the CCD feedback signal, and OFF means that no feedback signal is received.

[0098] "Spacing Set" - This button returns the machine to the initial process position after shutdown operations such as equipment cleaning or film cutting. The spacing set function enables one-click automatic calibration of coated film rolls of the same specification.

[0099] "Spacing Change Data" - This data can be stored and viewed in real time, allowing relevant personnel to trace product quality and optimize process parameters.

[0100] In summary, this method systematically solves the shortcomings of traditional methods that rely on manual, offline, and static adjustments, and realizes intelligent setting of process parameters, online dynamic compensation, and predictable maintenance, thereby significantly improving the efficiency, consistency, and intelligence level of regular coating.

[0101] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the above embodiments do not limit the scope of protection of the present invention in any way, and all technical solutions obtained by equivalent substitution or other means fall within the scope of protection of the present invention. Parts not covered in this invention are the same as or can be implemented using existing technology.

Claims

1. A method for quality on-line regulation of coated separators, characterized by, The method for controlling the gravure coating thickness comprises the following steps: firstly, automatically matching the best gap value according to the process formula; then, dynamically compensating the coating thickness on line, adjusting the gap in real time, predicting the service life of the doctor blade by monitoring the displacement amount of the adjustment, and actively warning and prompting the replacement before the doctor blade is completely invalid. The method for controlling the gravure coating thickness also comprises the following steps: firstly, controlling the servo motor to work by the manual point operation mode to finely adjust the distance between the back roll and the glue roll, and detecting the distance value at this time by the digital distance meter; then, starting the test coating and continuously and real-timely imaging monitoring the point morphology after the coating by the CCD system, and immediately analyzing the collected images to determine whether the test coating film roll morphology meets the requirements; if yes, setting the gap parameter, and performing the point coating operation based on the gap setting value; if no, finely adjusting the distance until the requirements are met.

2. The method for quality on-line adjustment of coated separators according to claim 1, characterized in that, In the method for controlling the gravure coating thickness, the process formula database of the key parameters associated by the test and the practical experience is established in advance, and after the doctor blade is replaced, the system automatically extracts and matches the preset best gap parameter from the formula database according to the input doctor blade parameter. In the method for controlling the gravure coating thickness, the high-precision on-line thickness meter is integrated to continuously and real-timely detect the coating diaphragm thickness.

3. The method of claim 1, wherein the step of determining the quality of the coated separator comprises: If the detected coating diaphragm thickness is within the required range, the equipment continuously and stably produces; if the detected coating diaphragm thickness is not within the required range, the deviation between the current thickness and the target value is calculated according to the real-time thickness data, and then the gap between the material box and the gravure roll is dynamically adjusted to make the coating film thickness always meet the requirements.

4. The method of claim 1, wherein the step of determining the quality of the coated separator comprises: The gap between the material box and the gravure roll is adjusted by the gravure roll-material box adjusting servo motor and the slide rail, wherein the servo motor generates the compensation instruction to realize the dynamic adjustment by establishing the coating thickness compensation algorithm model, and the coating thickness compensation algorithm model is defined as follows:

5. The method of claim 4, wherein the step of determining the quality of the coated separator comprises the steps of: determining the thickness of the coated separator; determining the weight of the coated separator; and determining the weight per unit area of the coated separator. The coating thickness y(t) is dominated by the slurry passage gap h(t):

6. The method of claim 5, wherein the step of determining the quality of the coated separator comprises the steps of: determining the thickness of the coated separator; determining the weight of the coated separator; and determining the weight per unit area of the coated separator. y(t)=k*h(t)+d(t) wherein, k-slurry transfer coefficient; h(t)-dynamic gap, i.e. the distance between the material box and the gravure roll, unit: μm; d(t)-external disturbance; The wear amount δw(t) of the doctor blade causes the time-varying expansion of the gap h(t): h(t)=h0+u(t)+δw(t) wherein, h0-initial set gap; u(t)-servo motor compensation displacement; δw(t)-wear depth, monotonic increasing function, δw(t)≥0; The set target thickness γ and the real-time deviation are: e(t)=γ-y(t) The proportional-integral (PI) control law is adopted: The above models are associated to obtain the thickness dynamic compensation model expression: wherein, K p - proportional gain; K i - integral gain; k*h0-initial set gap determined reference thickness; k*δw(t)-thickness drift caused by the doctor blade wear. ​ k * k p *(γ - y(t)) - proportional control: real-time counteract thickness fluctuations; - integral control: progressive compensation of systematic deviations caused by the wear of the doctor blade δw(t); ​ 7. The method for quality on-line adjustment of coated separators according to any of claims 1 or 6, characterized in that, By continuously monitoring and recording the dynamic displacement of the servo motor for compensating the doctor blade wear, a safety threshold of displacement based on the life of the doctor blade and process requirements is set, when the monitored displacement approaches or reaches the preset threshold, the system automatically triggers an audible and visual alarm signal, actively warns before the doctor blade completely fails, and prompts replacement.

8. The method of claim 2, wherein the coating of the separator is adjusted on-line. In the rule point coating morphology control, if the morphology is abnormal and does not meet the requirements, the interval is readjusted through manual jogging or feedback dynamic compensation.

9. The method of claim 8, wherein the step of determining the quality of the coated separator comprises the steps of: determining the thickness of the coated separator; determining the weight of the coated separator; and determining the weight per unit area of the coated separator. The collected images are analyzed in real time, and when the morphology defects or key parameters exceed the allowed range, compensation instructions are generated in real time, which instantaneously trigger the glue roller-back roller distance servo motor to fine-tune the distance between the glue roller and the back roller.

10. The method of claim 9, wherein the step of determining the quality of the coated separator comprises the steps of: determining the thickness of the coated separator; determining the weight of the coated separator; and determining the weight per unit area of the coated separator. The glue roller-back roller distance servo motor is arranged on the left and right sides of the rack, and cooperates with the slide rail to realize independent adjustment of the left and right sides of the glue roller and the back roller.

Images