Pole piece coating closed-loop control method

Abstract

The invention provides a pole piece coating closed-loop control method, which comprises the following steps: adjusting the overall surface density, the width size and the single-point surface density in sequence through a closed-loop control process, adjusting the longitudinal surface density by adjusting the pump speed according to the detection result of a thickness gauge, and adjusting the single-point surface density by adjusting the pump speed according to the detection result of the thickness gauge. The transverse surface density is adjusted by adjusting the height of the T block and / or the distance between the two ends of the die head and the pole piece, and then the width size is adjusted by adjusting the distance between the left end and the right end of the die head and the pole piece and / or adjusting the pump speed according to the detection result of the visual detector; finally, the single-point surface density is adjusted by adjusting the adjusting T blocks according to the detection result of the thickness gauge, all links are subjected to closed-loop control, full-automatic accurate adjustment from the overall surface density to the width to the single-point surface density can be achieved, high coating quality can be guaranteed, and meanwhile the labor cost is greatly reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of spraying, pouring or flowing liquid or other fluids onto the surface of a workpiece, and in particular to a closed-loop control method for electrode coating. Background Art

[0002] With the rapid development of the new energy industry, the output of lithium batteries is increasing. The safety and capacity of lithium batteries are the focus of users, which is closely related to the quality control of each process step in the battery manufacturing process. Currently, in the battery coating process, the surface density of the electrode surface coating is often detected by a thickness gauge, and the width of the electrode surface coating is detected by a CCD camera. If the surface density or width is not qualified, an alarm is issued, and then manual adjustments are made to the feed pump speed, the distance between the two ends of the die and the electrode, and the die lip gap. However, this results in very high labor costs. Summary of the Invention

[0003] The purpose of the present invention is to provide a closed-loop control method for electrode coating, so as to solve the problem of high labor costs caused by the existing manual control method.

[0004] The closed-loop control method for electrode coating of the present invention includes the following closed-loop control process: The closed-loop control process includes sequential overall area density adjustment, width size adjustment and single-point area density adjustment; The overall surface density adjustment includes judging whether the longitudinal surface density of the coating meets the surface density mean requirement based on the detection result of the thickness gauge. If not and the deviation is within the set tolerance range, adjusting the pump speed of the die feed pump until the longitudinal surface density meets the requirement, and then keeping the pump speed unchanged. If not and the deviation exceeds the set tolerance range, an alarm is issued. Afterwards, judging whether the consistency of the transverse surface density of the coating is qualified. If not and within the set tolerance range, adjusting the distance from both ends of the die to the pole piece and / or adjusting the height of the T block until the transverse surface density consistency is qualified. If not and beyond the set tolerance range, an alarm is issued. Width size adjustment includes judging whether the coating width size is qualified based on the visual inspection instrument. If not, adjust the distance from the left and right ends of the die head to the pole piece and / or adjust the pump speed until the coating width size is qualified; Single-point surface density adjustment includes judging whether the surface density of the coating corresponding to each adjustment T block is equal to the middle value of the surface density average range based on the detection results of the thickness gauge, and adjusting the height of each adjustment T block until the surface density is equal to the middle value of the surface density average range.

[0005] The present invention provides a new closed-loop control method for electrode coating, which is a pioneering invention. The closed-loop control method for electrode coating of the present invention adjusts the overall surface density, the width size and the single-point surface density in sequence through a closed-loop control process. The adjustment of the overall surface density is first adjusted by adjusting the pump speed according to the detection result of the thickness gauge, and the closed-loop control is performed until the adjustment is qualified. Then, the transverse surface density is adjusted by adjusting the T-block height and / or the distance from the two ends of the die to the electrode, and the closed-loop control is performed until the adjustment is qualified. Then, according to the detection result of the visual inspection instrument, the width size is adjusted by adjusting the distance from the left and right ends of the die to the electrode and / or adjusting the pump speed, and the closed-loop control is performed until the adjustment is qualified. Finally, according to the detection result of the thickness gauge, the single-point surface density is adjusted by adjusting each adjustment T block, and the closed-loop control is performed until it is adjusted to the surface density mean. In this way, the closed-loop control adjustment of the entire process can achieve fully automatic and precise adjustment from the overall surface density to the width to the single-point surface density, which can ensure high coating quality while greatly reducing labor costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 A schematic diagram of the structure of a partial extrusion coating machine to which the closed-loop control method for electrode coating of the present invention is applied; Figure 2 This is a control main logic flow chart of the electrode coating closed-loop control method of the present invention; Figure 3 This is a lateral consistency adjustment method in the closed-loop control method for electrode coating of the present invention; Figure 4 This is a method for adjusting the longitudinal surface density in the closed-loop control method for electrode coating of the present invention; Figure 5 This is a logic block diagram for adjusting the coating size in the closed-loop control method for electrode coating of the present invention.

[0007] In the figure: 1. Feed pump; 2. Die adjustment drive mechanism; 3. Temperature probe; 4. Feed pipeline; 5. Slit extrusion coating die; 6. Adjustment T-block; 7. Electrode; 8. CCD detector; 9. Back roller; 10. Duplex online thickness gauge; 11. Die lip gap. DETAILED DESCRIPTION

[0008] The present invention addresses the problem that existing extrusion coaters rely on manual adjustment when coating parameters such as coating thickness, size and surface density do not meet the requirements after detecting them, resulting in high labor costs. By performing closed-loop control adjustment on each detection parameter when the requirements are not met, the labor costs can be greatly reduced while ensuring the coating requirements.

[0009] In order to facilitate the understanding of the closed-loop control method for electrode coating of the present invention, first combine Figure 1The structure of the extrusion coating machine to which the control method of the present invention is applied is introduced. Figure 1 After unwinding, the rolled electrode 7 is wound around the back roller 9. A slot-type extrusion coating die 5 is provided on the front side of the back roller 9, that is, on the other side of the electrode 7 opposite to the back roller 9. The slot-type extrusion coating die 5 passes through the die lip gap 11 toward the electrode coating wound on the back roller 9, thereby forming a coating on the electrode 7. The front side of the slot-type extrusion coating die 5 is connected to the feed pipe 4. The slot-type extrusion die 5 is provided with an extrusion channel. The coating passing through the feed pipe 4 enters the extrusion channel and is discharged through the die lip gap 11.

[0010] The slit-type extrusion coating die 5 is provided with a group of adjustment T-blocks 6. There are multiple adjustment T-blocks 6 in the group and they are arranged along the length of the extrusion channel. Each adjustment T-block 6 is equipped with an adjustment T-block driving mechanism that drives it to move in the up and down directions to adjust the opening of the extrusion channel. When the adjustment T-block 6 moves upward and the opening increases, the flow rate of the extrusion channel at the position corresponding to the adjustment T-block 6 increases, and the coating thickness at the corresponding position on the electrode increases. When the adjustment T-block 6 moves downward and the opening decreases, the flow rate of the extrusion channel at the position corresponding to the adjustment T-block 6 decreases, and the coating thickness at the corresponding position on the electrode decreases. The left and right ends of the slit-type extrusion coating die 5, that is, the two ends in the width direction of the electrode, are respectively provided with a die adjustment driving mechanism 2. The die adjustment driving mechanism 2 can drive the two ends of the slit-type extrusion coating die 5 to approach and move away from the electrode. When moving away from the electrode, the coating thickness of the electrode increases, and when approaching the electrode, the coating thickness of the electrode decreases. The feed pipeline 4 is connected to a feed pump 1, which supplies coating to the slot extrusion coating die 5. When the pump speed increases, the feed flow rate increases, and when the pump speed decreases, the feed flow rate decreases.

[0011] The downstream side of the electrode 7 of the back roller 9, i.e., the side after coating, is equipped with a CCD detector 8 and a duplex online thickness gauge 10. The CCD detector 8 is used to detect the width of the coating, and the duplex online thickness gauge 10 is used to detect the thickness of the coating. One of the duplex online thickness gauges is used to detect the overall thickness of the coating to obtain data on the longitudinal surface density and the transverse surface density, and the other thickness gauge is used to detect the edge thickness of the coating.

[0012] A temperature probe 3 is provided on the feeding pipeline 4. The temperature probe 3 is used to detect the temperature of the coating to be fed into the slot extrusion coating die 5 to ensure that the coating temperature is qualified.

[0013] The slit extrusion coating die, the feeding method of the die, the coating method of the die, and the adjustment of the positions of the two ends of the die and the adjustment of the extrusion channel described above are all existing methods used in existing extrusion coating machines. Compared with the existing coating machines, the extrusion coating machine used in the closed-loop control method of the electrode coating of the present invention adopts a double-station online thickness gauge as the thickness gauge, and is also configured with a new control module. The CCD detector, the double-station online thickness gauge and the temperature probe are all connected to the control module to transmit the detection data to the control module, and the adjustment T-block drive mechanism, the die adjustment drive mechanism and the feed pump are all connected to the control module so that the control module can control them.

[0014] The implementation of the closed-loop control method for electrode coating of the present invention is as follows: First, temperature probe 3 transmits the temperature signal of the paint in the feed pipe to the control module. If the paint temperature is not up to standard, the entire coating process is stopped and the paint is heated automatically or manually under control. When the paint temperature reaches the standard, the whole machine starts the following closed-loop control process.

[0015] Closed-loop control process Figure 2 As shown in the figure, it specifically includes the following control and adjustment steps in sequence, namely, the overall surface density adjustment step, the width size adjustment step, and the single-point surface density adjustment step. At the beginning of each control step, the electrode is fully scanned by a CCD detector and a dual-station online thickness gauge, and the scanning cycle is set within 4-10 seconds, that is, the electrode is continuously scanned according to the scanning cycle.

[0016] The overall surface density adjustment process includes longitudinal surface density adjustment and transverse surface density adjustment. The longitudinal surface density adjustment is specifically as follows: based on the test results of the thickness gauge, determine whether the longitudinal surface density of the coating meets the surface density mean requirement. If the longitudinal surface density is within the mean requirement range, proceed to the next step, i.e., transverse surface density adjustment; if the longitudinal surface density exceeds the mean requirement range and there is a deviation, and the deviation is within the set tolerance range, adjust the pump speed of the die head feed pump until the longitudinal surface density meets the mean requirement, and then maintain the pump speed unchanged; if the longitudinal surface density exceeds the mean requirement range and there is a deviation, and the deviation exceeds the set tolerance range (the deviation is too large and the adjustment purpose can no longer be achieved through automatic adjustment), an alarm is issued and the problem is handled through manual inspection and maintenance.

[0017] Specific as Figure 4As shown, if the overall longitudinal surface density of the coating does not meet the mean requirement and is higher than the mean, when it is higher than the mean by more than 5%, it exceeds the set tolerance range. At this time, the control module controls the alarm module to alarm and handle it through manual detection and maintenance; when it is between 3-5% higher than the mean, specifically combined with the size of the test result, the pump speed is adjusted (decelerated) with 1rpm as the division value, and the adjustment amount can be 1rpm each time, or the adjustment amount can be nrpm each time, so as to adjust it to be close to the mean requirement as soon as possible; when it is between 2-3% higher than the mean, specifically combined with the size of the test result, the pump speed is adjusted (decelerated) with 0.8rpm as the division value, and the adjustment amount can be 0.8rpm each time, or the adjustment amount can be n*0.8rpm each time, so as to adjust it to be close to the mean requirement as soon as possible; when it is between 1-2% higher than the mean, specifically combined with the test result The pump speed shall be adjusted (decelerated) with a scale value of 0.5 rpm, and the adjustment amount may be 0.5 rpm each time, or n*0.5 rpm each time, so as to adjust it to be close to the mean requirement as soon as possible; when it is between 0.5-1% higher than the mean, the pump speed shall be adjusted (decelerated) with a scale value of 0.2 rpm, and the adjustment amount may be 0.2 rpm each time, or n*0.2 rpm each time, so as to adjust it to be close to the mean requirement as soon as possible; when it is higher than 0.5%, the pump speed shall be adjusted (decelerated) with a scale value of 0.1 rpm, and the adjustment amount may be 0.1 rpm each time, or n*0.1 rpm each time, so as to adjust it to be close to the mean requirement as soon as possible (the deviation shall not exceed 0.1%).

[0018] On the contrary, if the overall longitudinal surface density of the coating does not meet the mean requirement and is lower than the mean, when it is lower than the mean by more than 5%, it exceeds the set tolerance range. At this time, the control module controls the alarm module to alarm and handle it through manual inspection and maintenance; when it is between 3-5% lower than the mean, the pump speed is adjusted (increased) with 1rpm as the division value based on the size of the test result. The adjustment amount can be 1rpm each time, or the adjustment amount can be nrpm each time, so as to adjust it to the mean requirement as soon as possible; when it is between 2-3% lower than the mean, the pump speed is adjusted (increased) with 0.8rpm as the division value based on the size of the test result. The adjustment amount can be 0.8rpm each time, or the adjustment amount can be n*0.8rpm each time, so as to adjust it to the mean requirement as soon as possible; when it is between 1-2% lower than the mean, the pump speed is adjusted (increased) with 0.8rpm as the division value based on the test result. The pump speed shall be adjusted (increased) with a scale of 0.5 rpm, and the adjustment amount may be 0.5 rpm each time, or n*0.5 rpm each time, so as to adjust it to be close to the mean requirement as soon as possible; when it is between 0.5-1% lower than the mean, the pump speed shall be adjusted (increased) with a scale of 0.2 rpm, and the adjustment amount may be 0.2 rpm each time, or n*0.2 rpm each time, so as to adjust it to be close to the mean requirement as soon as possible; when it is lower than 0.5%, the pump speed shall be adjusted (increased) with a scale of 0.1 rpm, and the adjustment amount may be 0.1 rpm each time, or n*0.1 rpm each time, so as to adjust it to be close to the mean requirement as soon as possible (the deviation shall not exceed 0.1%).

[0019] The overall principle of the above adjustment strategy is that the larger the deviation, the larger the scale value of each adjustment, and the smaller the deviation, the smaller the scale value of each adjustment, so as to achieve fast and accurate adjustment. The specific method of demarcating the deviation value classification and the adjustment scale value within each deviation value level can be set according to specific needs. The above deviation value classification and the adjustment scale value within each deviation value level are only a specific embodiment and do not limit the scope of the present invention.

[0020] After each adjustment is completed, wait for the test data to be refreshed 2-3 times, and then judge whether the longitudinal surface density is qualified based on the latest test data. If it is unqualified, repeat the above adjustment process. If it is qualified, proceed to the next adjustment step.

[0021] After the longitudinal surface density is adjusted to within the mean range, the consistency of the transverse surface density of the coating is judged based on the test results of the thickness gauge. If the transverse surface density consistency is qualified, proceed to the next step, i.e., the width dimension adjustment link; if the transverse surface density consistency is unqualified and the deviation is within the set tolerance range, adjust the distance from the two ends of the die head to the pole piece separately, or adjust the height of the adjustment T block separately, or adjust the distance from the two ends of the die head to the pole piece and the height of the adjustment T block until the transverse surface density consistency is qualified; if the transverse surface density consistency is unqualified and the deviation exceeds the set tolerance range (the deviation is too large and the adjustment purpose can no longer be achieved through automatic adjustment), an alarm will be issued and the problem will be handled through manual inspection and maintenance.

[0022] Specifically, several points are selected in the width direction of the electrode as reference points, and each point corresponds to a certain range in the width direction. The coating surface contour line is fitted according to the data of the selected points detected by the thickness gauge. If the coating surface contour line fitted by all the selected points is an undulating curve, the height of the adjustment T block corresponding to these selected points is adjusted until all the selected points can fit a straight line.

[0023] Specifically, when adjusting the height of the corresponding adjustment T block, such as Figure 3 As shown, if the overall longitudinal surface density of the coating does not meet the mean requirement and is higher than the mean, when it is higher than the mean by more than 5%, it exceeds the set tolerance range. At this time, the control module controls the alarm module to alarm and handle it through manual inspection and maintenance; when it is between 3-5% higher than the mean, based on the size of the test result, the height of the adjustment T block is adjusted (lowered) with a graduation value of 40μm / time, and the adjustment amount can be 40μm each time, or the adjustment amount can be an integer multiple of 40μm each time, so as to be able to adjust to the mean requirement as soon as possible; when it is between 2-3% higher than the mean, based on the size of the test result, the height of the adjustment T block is adjusted (lowered) with a graduation value of 30μm / time, and the adjustment amount can be 30μm each time, or The adjustment amount is an integer multiple of 30μm, so as to adjust it to be close to the mean requirement as soon as possible; when it is between 1-2% higher than the mean, based on the specific size of the test results, the height of the adjustment T block is adjusted (lowered) with a graduation value of 20μm / time, and the adjustment amount each time can be 20μm, or the adjustment amount each time can be an integer multiple of 20μm, so as to adjust it to be close to the mean requirement as soon as possible; when it is between 0.5-1% higher than the mean, based on the specific size of the test results, the height of the adjustment T block is adjusted (lowered) with a graduation value of 10μm / time, and the adjustment amount each time can be 10μm, or the adjustment amount each time can be an integer multiple of 10μm, so as to adjust it to be close to the mean requirement (the deviation is not more than 0.5%) as soon as possible.

[0024] On the contrary, if the overall lateral surface density of the coating does not meet the mean requirement and is lower than the mean, when it is lower than the mean by more than 5%, it exceeds the set tolerance range. At this time, the control module controls the alarm module to alarm and handle it through manual inspection and maintenance; when it is between 3-5% lower than the mean, based on the size of the test results, the height of the adjustment T block is adjusted (increased) with a graduation value of 40μm / time, and the adjustment amount can be 40μm each time, or the adjustment amount can be an integer multiple of 40μm each time, so as to adjust it to be close to the mean requirement as soon as possible; when it is between 2-3% lower than the mean, based on the size of the test results, the height of the adjustment T block is adjusted (increased) with a graduation value of 30μm / time, and the adjustment amount can be 30μm each time, or The adjustment amount is an integer multiple of 30μm, so as to adjust it to be close to the mean requirement as soon as possible; when it is between 1-2% lower than the mean, based on the specific size of the test results, the height of the adjustment T block is adjusted (increased) with a graduation value of 20μm / time, and the adjustment amount each time can be 20μm, or the adjustment amount each time can be an integer multiple of 20μm, so as to adjust it to be close to the mean requirement as soon as possible; when it is between 0.5-1% lower than the mean, based on the specific size of the test results, the height of the adjustment T block is adjusted (increased) with a graduation value of 10μm / time, and the adjustment amount each time can be 10μm, or the adjustment amount each time can be an integer multiple of 10μm, so as to adjust it to be close to the mean requirement (deviation not more than 0.5%) as soon as possible.

[0025] Similarly, the overall principle of the above adjustment strategy is that the larger the deviation, the larger the scale value of each adjustment, and the smaller the deviation, the smaller the scale value of each adjustment, so as to achieve fast and accurate adjustment. The specific demarcation of the deviation value classification and the adjustment scale value within each deviation value level can be set according to specific needs. The above deviation value classification and the adjustment scale value within each deviation value level are only a specific embodiment and do not limit the scope of the present invention.

[0026] When all selected points can be fitted into a straight line, and the slope of the fitted line is 0, it proves that the lateral surface density of the coating is highly consistent across the entire width of the electrode. If the slope of the fitted line is not 0, it proves that the overall surface density of the coating changes gradually from one side to the other across the width of the electrode. In this case, reduce the distance between the die and the electrode on the side with greater coating thickness, or increase the distance between the die and the electrode on the side with less coating thickness, so that the slope of the fitted line approaches 0; or overall reduce the height of the T-block on the half with greater coating thickness, or overall increase the height of the T-block on the half with less coating thickness, so that the slope of the fitted line approaches 0.

[0027] In specific implementations, the number of selected points can be determined based on the length of the entire die lip gap. The number of selected points should not be too small, otherwise it will easily lead to inaccurate transverse consistency testing and adjustment. At the same time, the number of selected points should not be too large, otherwise it will easily lead to overly cumbersome testing or adjustment. Furthermore, the width range occupied by the selected points is based on the width dimensions of an integer number of adjustment T-blocks. In one embodiment, the width range occupied by the selected points is set to 20 mm or 40 mm, based on the width dimensions of one or two adjustment T-blocks.

[0028] In the above adjustment process, after each adjustment is completed, wait for the test data to be refreshed 2-3 times, and then judge whether the adjustment purpose is achieved based on the latest test data. If the adjustment purpose is not achieved, repeat the above adjustment process. If the adjustment purpose is achieved, proceed to the next adjustment step.

[0029] By adjusting the longitudinal surface density and the transverse surface density, the overall control of the coating quality within the unit length and electrode width is achieved, and then the coating width size and single-point surface density are adjusted. This method of adjustment from overall adjustment, rough adjustment to local adjustment, fine adjustment has a higher adjustment efficiency.

[0030] After the overall surface density is adjusted to within the required range, the width adjustment step is performed. When adjusting the width, the general principle is to comprehensively consider the distance from the left and right ends of the die to the pole piece and the adjustment of the pump speed, and to adjust the width while ensuring that the longitudinal surface density mean and the transverse surface density consistency meet the requirements. Adjusting the pump speed may cause the overall surface density to change. Therefore, during the width adjustment process, the distance from the left and right ends of the die to the pole piece should be adjusted first. If the surface density does not exceed the requirements, the pump speed should be kept unchanged. If the surface density exceeds the requirements, the pump speed should be adjusted.

[0031] Specific as Figure 5 As shown, the coating dimension, i.e., the coating width, is determined to be acceptable based on the data detected by the CCD detector. If the coating width is larger than the standard value, the coating width should be reduced by increasing the GAP value (i.e., the distance from the left and right ends of the die to the electrode) and fine-tuned in 1μm increments. If the GAP adjustment affects the overall surface density, resulting in an increase in density, the feed pump speed should be appropriately reduced in 0.1rpm increments. If the coating width is smaller than the standard value, the coating width should be increased by decreasing the GAP value (i.e., the distance from the left and right ends of the die to the electrode) and fine-tuned in 1μm increments. If the GAP adjustment affects the overall surface density, resulting in a decrease in density, the feed pump speed should be appropriately increased in 0.1rpm increments. This should be continued until the width is within ±0.5mm of the standard size.

[0032] In the above adjustment process, after each adjustment is completed, wait for the test data to be refreshed 2-3 times, and then judge whether the adjustment purpose is achieved based on the latest test data. If the adjustment purpose is not achieved, repeat the above adjustment process. If the adjustment purpose is achieved, proceed to the next adjustment step.

[0033] When the overall surface density and width dimensions are qualified, single-point surface density adjustment is performed based on the thickness data detected by the thickness gauge. Single-point surface density adjustment is to determine whether the surface density of the coating corresponding to each adjustment T-block is equal to the middle value of the surface density mean range based on the detection results of the thickness gauge, and adjust the height of each adjustment T-block until the surface density is equal to the middle value of the surface density mean range. This adjustment process requires some adjustment T-blocks to be raised and some adjustment T-blocks to be lowered. The overall surface density will not change significantly and can be maintained within the required range. Ultimately, the consistency of the lateral surface density across the entire width of the pole piece is better and closer to the standard value.

[0034] In addition, during the entire closed-loop control process described above, the coating edge thickness is detected in real time by another thickness gauge in the dual-station online thickness gauge. When the coating edge thickness is less than the set minimum edge thickness value, it indicates that edge thinning has occurred. At this time, the control module controls the alarm module to sound an alarm.

[0035] After the above adjustment steps are completed, the control module enters the continuous maintenance state to ensure the stability of the coating state. Generally, it is necessary to control the single-point surface density and the left and right GAP values. This is a fine-tuning in process monitoring, and the parameter fluctuations are often small.

[0036] Through the electrode coating closed-loop control method of the present invention introduced above, the coating surface density and dimensional anomalies can be monitored and adjusted in real time, which can reduce manpower and at the same time reduce scrap caused by manual debugging and improve yield.

[0037] The above embodiment is a preferred embodiment of the present invention and cannot be used as a limitation of the present invention. For example, in other embodiments, if other measures have been taken to ensure the coating temperature of the feed pipeline, there is no need to detect whether the die feed temperature meets the coating requirements before performing the closed-loop control process.

[0038] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. The scope of patent protection of the present invention shall be based on the claims. Any equivalent structural changes made using the description and drawings of the present invention shall be included in the scope of protection of the present invention.

Claims

1. A closed-loop control method for electrode coating, characterized in that: Including closed-loop control process: The closed-loop control process includes sequential overall area density adjustment, width size adjustment and single-point area density adjustment; The overall surface density adjustment includes judging whether the longitudinal surface density of the coating meets the surface density mean requirement based on the detection result of the thickness gauge. If not and the deviation is within the set tolerance range, adjusting the pump speed of the die feed pump until the longitudinal surface density meets the requirement, and then keeping the pump speed unchanged. If not and the deviation exceeds the set tolerance range, an alarm is issued. Afterwards, judging whether the consistency of the transverse surface density of the coating is qualified. If not and within the set tolerance range, adjusting the distance from both ends of the die to the pole piece and / or adjusting the height of the T block until the transverse surface density consistency is qualified. If not and beyond the set tolerance range, an alarm is issued. Width size adjustment includes judging whether the coating width size is qualified based on the visual inspection instrument. If not, adjust the distance from the left and right ends of the die head to the pole piece and / or adjust the pump speed until the coating width size is qualified; Single-point surface density adjustment includes judging whether the surface density of the coating corresponding to each adjustment T block is equal to the middle value of the surface density average range based on the detection results of the thickness gauge, and adjusting the height of each adjustment T block until the surface density is equal to the middle value of the surface density average range.

2. The closed-loop control method for electrode coating according to claim 1, characterized in that: Set the scanning inspection cycle of the thickness gauge and visual inspection instrument. When adjusting the pump speed, the height of the T block, and the distance from the left and right ends of the die to the pole piece, each time an adjustment is made, the inspection results are refreshed 2-3 times, and then determine whether to make the next adjustment based on the refreshed inspection results.

3. The closed-loop control method for electrode coating according to claim 2, characterized in that: The scanning cycle is 4-10s.

4. The closed-loop control method for electrode coating according to any one of claims 1 to 3, characterized in that: When judging the consistency of the transverse surface density, multiple points are selected in the coating width direction and the coating surface contour line is fitted. If the coating surface contour line is an undulating curve, the height of the T block is adjusted until the coating surface contour line tends to be a straight line. When the coating surface contour line tends to be a straight line, the distance from the left and right ends of the die to the electrode is adjusted according to the slope of the coating surface contour line, or the height of the T block is adjusted on the half side in the electrode width direction until the slope tends to 0.

5. The closed-loop control method for electrode coating according to claim 4, characterized in that: When the coating surface contour line is an undulating curve and the adjustment T-block of the die head is adjusted, the coating is divided into several length units in the width direction according to the area where the points selected when fitting the straight line are located. Each length unit corresponds to at least one adjustment T-block. The coating surface contour line is adjusted to a straight line by adjusting the height of the adjustment T-block corresponding to the length unit.

6. The closed-loop control method for electrode coating according to claim 5, characterized in that: The width of the coating corresponding to each length unit is between 20 mm and 40 mm.

7. The closed-loop control method for electrode coating according to any one of claims 1 to 3, characterized in that: During the width adjustment process, the distance from the left and right ends of the die to the pole piece and the pump speed are adjusted comprehensively to achieve the width adjustment while ensuring that the longitudinal surface density mean and the transverse surface density consistency meet the requirements.

8. The closed-loop control method for electrode coating according to claim 7, characterized in that: During the width adjustment process, give priority to adjusting the distance from the left and right ends of the die head to the pole piece. Keep the pump speed unchanged unless the surface density exceeds the requirement. Adjust the pump speed if the surface density exceeds the requirement.

9. The closed-loop control method for electrode coating according to any one of claims 1 to 3, characterized in that: During the entire closed-loop control process, the coating edge thickness is detected in real time, and an alarm is triggered when the coating edge thickness is less than the set minimum edge thickness value.

10. The closed-loop control method for electrode coating according to any one of claims 1 to 3, characterized in that: Before the closed-loop control process is carried out, it is detected whether the die feed temperature meets the coating requirements. If not, the feed temperature is adjusted until it meets the coating requirements, and then the closed-loop control process is implemented.

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