Rolling method and device for reducing black wire defect of cold-rolled aluminum foil

Abstract

The invention provides a rolling method for reducing cold-rolled aluminum foil black wire defects. The rolling method comprises the following steps that strip steel is clamped and positioned in a preset rolling area of a cold-rolling mill through a clamping and positioning device; a transmission device of the cold-rolling mill is started to drive the working rollers to rotate, and the strip steel is rolled between the working rollers; rolling oil of the strip steel is cleaned through a high-frequency ultrasonic generator, the rolling oil is filtered through a gradient microfiltration membrane set, and the filtered oil is conveyed to a cold rolling mill through an oil pump; a high-speed visual positioning unit is used for detecting surface defects of the strip steel, defect morphology and position coordinates are captured, and sulfur / phosphorus-containing extreme pressure additive microdroplets are sprayed through a spraying device for surface repairing; and in the rolling process, the strip steel is subjected to homogenizing annealing through an annealing device. The aluminum foil surface black filament defect is effectively reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to a rolling method and device for reducing black silk defects of cold-rolled aluminum foil. BACKGROUND

[0002] Cold-rolled aluminum foil is an important aluminum alloy material, widely used in packaging, electronics, automobiles and other industries. However, during the cold rolling process, black silk defects often appear on the surface of the aluminum foil, which are usually manifested as surface streaks or spot-like flaws, seriously affecting the appearance quality and use performance of the aluminum foil. Black silk defects not only affect the visual effect of the product, but also reduce the mechanical properties and corrosion resistance of the aluminum foil, thereby increasing the subsequent processing cost and production scrap rate, so reducing and eliminating the black silk defects on the surface of the cold-rolled aluminum foil has always been one of the important technical challenges in the field of cold-rolled aluminum foil production.

[0003] Although the prior art has made some improvements to improve black silk defects by improving the cold rolling machine equipment, rolling oil cleaning, annealing treatment and other aspects, there are still problems such as insufficient cleaning effect, inaccurate surface defect repair, etc., especially in terms of deep cleaning of rolling oil, accurate control of strip steel temperature, real-time detection and repair of surface defects, etc.

[0004] Therefore, there is still a lot of room for improvement in the prior art in solving the black silk defects of cold-rolled aluminum foil, and the prior art needs to be improved in view of the above problems. SUMMARY

[0005] The purpose of the present application is to solve the above problems of the prior art, and to provide a rolling method and device for reducing black silk defects of cold-rolled aluminum foil, which has the effects of reducing black silk defects on the surface of the aluminum foil, improving the cleanliness of the rolling oil, optimizing the control of the strip steel temperature and the accuracy of the surface repair. These purposes of the present application are achieved in the following ways:

[0006] In one aspect, the present application proposes a rolling method for reducing black silk defects of cold-rolled aluminum foil, comprising the following steps: step one, clamping and positioning the strip steel in the preset rolling area of the cold rolling mill through the clamping positioning device; step two, starting the driving device of the cold rolling mill to drive the work roll to rotate, and the strip steel is rolled between the work rolls, and the gap between the work rolls is controlled between 0.1-1.5mm; step three, using a high-frequency ultrasonic generator to clean the rolling oil of the strip steel, the ultrasonic frequency is 40-100kHz, and the rolling oil is filtered through a gradient microporous filter membrane group, the pore size of the filter membrane is 50-5μm, and the filtered oil is delivered to the cold rolling mill through an oil pump; step four, using a high-speed visual positioning unit to detect the surface defects of the strip steel, capturing the defect morphology and position coordinates, and spraying sulfur / phosphorus extreme pressure additive droplets through a spraying device for surface repair, and the spraying diameter of the droplets is controlled between 15-25μm; step five, between the rolling process, the strip steel is homogenized annealed through an annealing device, the annealing temperature is controlled between 580-650℃, and the annealing time is controlled between 4-8 hours.

[0007] Further, between step two and step three, the strip steel is preheated to 150-250℃ using a heating device to reduce plastic deformation and surface cracks of the strip steel during rolling, and to achieve temperature distribution of the strip steel during rolling.

[0008] Further, between step three and step four, the strip steel surface is further cleaned by a spray cleaning system, which uses high-pressure micro-spray to remove small particle impurities and oil stains on the surface.

[0009] Further, between step four and step five, a laser surface scanner is used to scan the surface of the strip steel to detect micro-defects on the surface of the strip steel and their distribution in real time, the scanner generates repair data according to the morphology, size and position of the defects, and automatically adjusts the spraying amount and direction of the spraying device through the control system to realize point-by-point and quantitative surface repair.

[0010] Further, after step five, the annealed strip steel is cooled by a cooling device.

[0011] Further, the high-frequency ultrasonic generator in step three uses ultrasonic waves with a frequency range of 40-60kHz for cleaning, and the working time of the high-frequency ultrasonic generator is 30-60 seconds each time.

[0012] Further, during the annealing process in step five, the temperature in the annealing furnace is set at 610℃, the annealing time is 5 hours, and the atmosphere in the annealing furnace is controlled by an atmosphere adjusting system to be a mixture of nitrogen and hydrogen gas, wherein the hydrogen concentration is maintained at 3-5%, to remove the oxide layer on the surface of the aluminum foil.

[0013] In another aspect, the present application also provides a rolling device for reducing black silk defects of cold-rolled aluminum foil, which is used to realize the rolling method for reducing black silk defects of cold-rolled aluminum foil, and comprises a clamping and positioning device for clamping and positioning a strip steel in a preset rolling area of a cold rolling mill; a cold rolling mill body for transmitting power and driving a work roll to rotate; a heating device for preheating the strip steel to 150-250 DEG C before rolling, which adopts electric heating or hot air circulation; a high-frequency ultrasonic cleaning device comprising an ultrasonic generator and an ultrasonic heat exchanger, wherein the working frequency of the ultrasonic generator is 40-100 kHz, and the ultrasonic generator is connected with a gradient microporous filter membrane group, and the filtered cleaning oil is delivered to the cold rolling mill through an oil pump; a spray cleaning system for further cleaning the surface of the strip steel; a high-speed visual positioning unit comprising a high-precision camera system for real-time monitoring of surface defects of the strip steel, capturing defect morphology and position coordinates, and outputting defect data through a control system; a spraying device for accurately spraying sulfur / phosphorus extreme pressure additive droplets to the defect position on the surface of the strip steel; a laser surface scanner for high-precision scanning of the surface of the strip steel, wherein the scanner generates repair data according to the morphology, size and position of the surface defects, and automatically adjusts the spraying amount and spraying direction of the spraying device through the control system; an annealing device comprising an annealing furnace and an atmosphere adjusting system, wherein the annealing furnace is used to heat the strip steel to 580-650 DEG C and maintain at the required annealing temperature, and the atmosphere adjusting system in the annealing furnace controls the atmosphere in the annealing furnace to be a mixed gas of nitrogen and hydrogen, and the hydrogen concentration is controlled to be 3-5%; and a cooling device for cooling the annealed strip steel.

[0014] Compared with the prior art, the present application has the advantages that the rolling oil cleanliness is improved by high-frequency ultrasonic cleaning combined with gradient filtration, the surface defects are repaired by high-speed visual positioning and micro-droplet spraying, and the strip steel performance is optimized by homogenizing annealing, so that the aluminum foil surface black silk defects are effectively reduced, and the product surface quality and processing efficiency are improved. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 Fig. 1 is a flowchart of a rolling method for reducing black silk defects of cold-rolled aluminum foil. DETAILED DESCRIPTION

[0016] In order to deepen the understanding of the present application, the present application will be further described in detail below in combination with embodiments and drawings, which are only used to explain the present application and do not constitute a limitation on the protection scope of the present application.

[0017] In the prior art, black silk defects are often caused by surface contamination, rolling oil deterioration, uneven temperature control and insufficient annealing treatment during the production of cold-rolled aluminum foil. The traditional method tries to solve this problem by improving the rolling equipment or optimizing the annealing process, but there are limitations such as low cleaning efficiency, uneven temperature distribution, and insufficient defect repair precision. For example, the conventional rolling oil filtration system cannot completely remove small particles, and residual contaminants are easy to embed in the surface of the aluminum foil during rolling; inaccurate control of annealing process parameters can lead to residual oxide layer or grain coarsening, which in turn causes surface stripe or spot defects.

[0018] To solve the above problems, because the generation of black silk defects involves multiple factor coupling, it is necessary to optimize from four aspects of rolling process stability, contaminant removal efficiency, surface repair precision and material uniformity. First, the traditional clamping positioning method is easy to cause the strip to deviate, so a high-precision positioning device needs to be developed to stabilize the rolling area; second, the conventional oil cleaning technology is difficult to remove micron-level contaminants, so deep cleaning needs to be achieved by combining high-frequency ultrasonic cavitation effect and gradient filtration; third, surface defect repair needs to match micron-level spraying precision, so visual positioning and micro-droplet spraying need to be introduced for collaborative control; finally, the annealing process needs to balance the temperature uniformity and the removal efficiency of the oxide layer, so the annealing parameters and atmosphere control need to be optimized.

[0019] Therefore, the present application proposes a rolling method for reducing black silk defects of cold-rolled aluminum foil, comprising the following steps: step one, clamping and positioning the strip steel in the preset rolling area of the cold rolling mill by the clamping positioning device; step two, starting the driving device of the cold rolling mill to drive the work roll to rotate, and the strip steel is rolled between the work rolls, and the gap between the work rolls is controlled between 0.1-1.5mm; step three, using a high-frequency ultrasonic generator to clean the rolling oil of the strip steel, the ultrasonic frequency is 40-100kHz, and the rolling oil is filtered through a gradient microporous filter membrane group, the pore size of the filter membrane is 50-5μm, and the filtered oil is delivered to the cold rolling mill by an oil pump; step four, using a high-speed visual positioning unit to detect the surface defects of the strip steel, capturing the defect morphology and position coordinates, and spraying sulfur / phosphorus extreme pressure additive micro-droplets through a spraying device for surface repair, the spraying diameter of the micro-droplets is controlled between 15-25μm; step five, between the rolling process, the strip steel is homogenized annealed by an annealing device, the annealing temperature is controlled between 580-650℃, and the annealing time is controlled between 4-8 hours.

[0020] It should be noted that the clamping positioning device refers to a mechanical clamp with multi-point pressure adjustment function, which can be realized by a hydraulic servo control unit, and is used to eliminate the position deviation of the strip during rolling. The gap control between the work rolls refers to the adjustment of the roll gap through the linkage of high-precision displacement sensors and servo motors, which can be realized by a closed-loop feedback control system, and is used to match the rolling deformation requirements of aluminum foil with different thicknesses. The high-frequency ultrasonic generator refers to a transducer device that can generate mechanical vibrations of a specific frequency, which can be realized by a piezoelectric ceramic element, and is used to strip the contaminants attached to the surface of the strip through cavitation effect. The gradient microporous filter membrane group refers to a multi-layer filtering structure with decreasing pore size distribution, which can be realized by stacking stainless steel sintered filter cartridges, and is used to intercept the particulate impurities in the oil in stages. The high-speed visual positioning unit refers to an image acquisition system equipped with a high-speed camera, which can be realized by a linear array CCD sensor, and is used to capture the micro-topography of surface defects in real time. The sulfur / phosphorus extreme pressure additive microdroplet refers to a liquid repair agent containing sulfur or phosphorus compounds, which can be realized by a micron-sized atomizing nozzle, and is used to form a lubricating protective layer at the defect site. Homogenization annealing refers to the constant temperature heat treatment process of the strip in a controllable atmosphere, which can be realized by a radiation tube heating and atmosphere circulation system, and is used to eliminate internal stress and remove surface oxide layer.

[0021] Specifically, the strip is fixed at a predetermined position by the clamping positioning device before rolling to avoid uneven stress on the surface due to position deviation during rolling. The gap between the work rolls is dynamically adjusted by a closed-loop control system to ensure uniform distribution of rolling force. High-frequency ultrasonic waves generate cavitation bubbles when acting on rolling oil, stripping off oil stains and particles attached to the surface of the strip, and then the gradient filter membrane group intercepts pollutants of different particle sizes in stages to maintain oil cleanliness. The high-speed visual system scans the surface of the strip in real time, identifies defects, and triggers the microdroplet spraying device to form a lubricating film by accurately covering the defect area with extreme pressure additives. During the annealing process, the strip is subjected to constant temperature treatment in a nitrogen-hydrogen mixed atmosphere to eliminate rolling stress and remove the oxide layer.

[0022] Compared with the prior art, the traditional method usually optimizes the rolling parameters or annealing process alone, while the present application achieves systematic improvement through multi-link cooperative control. Conventional rolling oil cleaning only uses single-stage filtration, while the present application significantly improves cleaning efficiency by combining ultrasonic cavitation and gradient filtration; traditional surface repair relies on manual detection and coating, while the present application realizes automatic repair through visual positioning and microdroplet spraying; ordinary annealing process uses single temperature control, while the present application improves material performance by adjusting the atmosphere and synchronizing the temperature homogenization treatment.

[0023] By the technical scheme, the generation of the black silk defect on the surface of the cold-rolled aluminum foil is effectively reduced. The improvement of the positioning accuracy of the strip steel reduces the risk of surface cracks caused by rolling deviation; the deep cleaning of the rolling oil reduces the secondary attachment of pollutants; the micron-level jetting repair accurately fills the surface micro-cracks; and the controllable annealing process eliminates the internal stress of the material and removes the oxide layer. The synergistic effect of each step realizes the whole-process control from the removal of pollutants, defect repair to material performance optimization.

[0024] The application further proposes adding a step of preheating the strip steel to 150-250 DEG C by using a heating device between step two and step three, so as to reduce the plastic deformation and surface cracks of the strip steel in the rolling process and realize the temperature distribution of the strip steel in the rolling process.

[0025] It should be noted that the heating device refers to a device for adjusting the temperature of the strip steel by an external heat source, which can be realized by electric heating or hot air circulation, and its function is to actively control the temperature of the strip steel to avoid the decrease of material plasticity and local stress concentration caused by insufficient temperature. Among them, preheating to 150-250 DEG C means heating the whole or part of the strip steel to this temperature range, which can be realized by segmented temperature control or continuous heating. The selection of this temperature range can not only improve the plastic deformation capacity of the material, but also avoid the volatilization of the rolling oil or the excessive softening of the material caused by too high temperature.

[0026] Specifically, the strip steel is preheated by the heating device before rolling, so that the temperature of the surface and the inside of the strip steel uniformly rises to the set range. At this temperature, the ductility of the aluminum material is improved, and the internal stress distribution of the material during rolling is more uniform, thereby reducing the surface cracks and plastic deformation caused by local temperature difference. At the same time, the temperature control is coordinated with the subsequent rolling oil cleaning step to avoid the combination of low-temperature rolling oil residue and impurities on the surface of the strip steel to form a defect source.

[0027] Compared with the prior art, the traditional cold rolling process usually relies on ambient temperature or rolling friction to generate heat for temperature adjustment, which leads to uneven temperature distribution of the strip steel and makes it difficult to reach the critical value required for plastic deformation. By actively preheating, the application accurately controls the temperature range of the strip steel, which not only overcomes the brittleness problem caused by low-temperature rolling, but also avoids the failure of rolling oil caused by high temperature, thereby reducing the black silk defect caused by temperature fluctuation at the root.

[0028] By the technical scheme, the application can effectively reduce the surface crack occurrence rate of the strip steel in the rolling process caused by insufficient temperature, improve the plastic deformation capacity of the material, make the surface of the aluminum foil after rolling more smooth, and reduce the black silk defect caused by local stress concentration or crack propagation.

[0029] The application further adds a high-pressure micro-spray cleaning process after the rolling oil filtration and cleaning and before the surface defect repair, and the strip steel surface is further cleaned through a spray cleaning system, and the spray cleaning system adopts high-pressure micro-spray to remove small particle impurities and oil stains on the surface.

[0030] It should be noted that the high-pressure micro-spray refers to a cleaning method of forming micron-sized atomized particles through high-pressure fluid impact, and specifically, a pumping system with a pressure range of 5-20 MPa can be combined with a multi-hole nozzle array to achieve the method, and the surface contaminants are stripped through the kinetic energy impact of the atomized particles. The spray cleaning system refers to a cleaning device composed of a high-pressure pump, a multi-stage filtration unit and a directional nozzle, and specifically, a closed-loop circulating water system can be combined with an anti-clogging nozzle structure to achieve the method, and the full area of the strip steel surface is covered through directional spraying to avoid residual cleaning liquid.

[0031] Specifically, after the ultrasonic cleaning and gradient filtration of the rolling oil are completed, the strip steel enters the high-pressure micro-spray cleaning stage. The high-pressure pump pressurizes the filtered cleaning liquid and delivers it to the nozzle array to form a uniform distribution of micron-sized atomized particle flow. The atomized particles impact the strip steel surface at high speed, and their kinetic energy is sufficient to strip nanoscale particle contaminants and oil film residues. The waste liquid after cleaning enters the multi-stage filtration unit through the recovery pipeline, and after removing the impurities, it participates in the circulation again. The process is arranged before the surface defect detection and repair, so that the surface of the strip steel reaches an ultra-clean state and eliminates the possibility of contaminants being embedded in the aluminum foil matrix during the subsequent rolling process.

[0032] Compared with the prior art, the traditional process only relies on single ultrasonic cleaning, and the removal effect of the oil film and micron-sized particles attached to the surface is limited. The present application effectively solves the problem of secondary pollution caused by traditional immersion cleaning by constructing a multi-stage cleaning system and adding dynamic impact cleaning on the basis of physical filtration. At the same time, the directional coverage characteristics of high-pressure micro-spray avoid blind areas in cleaning, and provide uniform and clean surface conditions for the subsequent defect detection and repair process.

[0033] Through the above technical solutions, the present application can effectively remove the rolling oil stains and micron-sized particle contaminants remaining on the surface of the strip steel during the cold rolling process, and block the formation path of black silk defects. The reasonable arrangement of the cleaning process avoids the embedding of contaminants in the aluminum foil matrix in the subsequent rolling process, significantly improves the surface cleanliness, and creates necessary conditions for accurate detection and repair of surface defects.

[0034] The application further proposes to increase the use of a laser surface scanner to scan the surface of the strip steel between step four and step five, to detect micro-defects and their distribution on the surface of the strip steel in real time. The scanner generates repair data according to the shape, size and position of the defects, and automatically adjusts the spraying amount and direction of the spraying device through the control system to realize point-by-point and quantitative surface repair.

[0035] It should be noted that the laser surface scanner refers to a device for non-contact three-dimensional topography detection of the surface of the strip steel by a laser beam, which can be realized by a semiconductor laser with a wavelength range of 400-700nm cooperating with a high-speed photoelectric sensor array, and can capture micro defects such as surface concave-convex and cracks with micron-level resolution. The control system refers to an automatic adjustment module for operating the spraying parameters based on the defect feature parameters, which can be realized by an industrial computer combined with a motion control card, and the defect coordinates and depth data are converted into the moving track of the spraying device and the valve opening signal. The spraying direction adjustment function of the spraying device refers to a mechanism for multi-axis deflection of the nozzle driven by a servo motor, which can be realized by a two-degree-of-freedom rotary platform cooperating with a micro electromagnetic valve array, and the spraying angle can be accurately deflected within ±30 degrees.

[0036] Specifically, after the surface of the strip steel is completed by the surface repair agent spraying, the laser surface scanner continuously scans along the strip steel running direction, and the surface three-dimensional topography data is constructed by the laser interference principle. When a micro defect with a depth exceeding a set threshold is detected, the scanner transmits the geometric parameters of the defect to the control system. The control system calculates the volume of the required repair agent according to the defect depth distribution, and determines the triggering time of the spraying device in combination with the moving speed of the strip steel. After receiving the control instruction, the spraying device controls the micro-droplet spraying amount by adjusting the opening time of the nozzle and the electromagnetic valve pressure, and drives the rotary platform to change the spraying angle, so that the repair agent micro-droplets accurately cover the defect area.

[0037] Compared with the prior art, the traditional method relies on manual inspection or two-dimensional visual detection, which cannot accurately identify the depth information of micro cracks, resulting in mismatch between the amount of repair agent and the severity of defects. The existing spraying device usually adopts a fixed spraying mode, which cannot dynamically adjust the spraying track according to the defect position, and is easy to cause incomplete coverage or excessive accumulation of repair agent. The present application realizes the accurate matching of the amount of repair agent and the defect characteristics by acquiring the defect depth data through three-dimensional laser scanning and dynamically adjusting the spraying parameters.

[0038] Through the above technical scheme, the present application effectively solves the repair omission problem caused by insufficient surface defect detection accuracy, and avoids the material waste caused by excessive use of repair agent. By real-time matching of the spraying parameters and the defect characteristics, the corresponding repair agent coverage amount is ensured for defects of different sizes, and the secondary surface defects caused by uneven distribution of repair agent are eliminated.

[0039] The present application further proposes a technical scheme of adding a cooling device to cool the strip steel after the annealing process.

[0040] It should be noted that the cooling device refers to a device for controlling the temperature of the high-temperature strip after annealing, which can be realized by using a forced air cooling system or a water cooling circulation system. By adjusting the flow rate and temperature of the cooling medium, the strip gradually decreases from the annealing temperature to the normal temperature. The role of the cooling device is to avoid the local temperature gradient caused by the difference in natural cooling rate, thereby reducing the accumulation of residual stress. Among them, the cooling process refers to actively controlling the cooling rate and temperature distribution to achieve uniform cooling of the strip after annealing. Specifically, it can be realized by using the segmented cooling or gradient cooling method, for example, first using medium-speed air cooling to reduce the transition temperature, and then further cooling by water cooling circulation. This process can inhibit the occurrence of oxidation reaction and prevent the surface oxidation layer from remaining.

[0041] Specifically, the strip after annealing is in a high-temperature softening state. If it is directly exposed to air, the surface will form thermal stress due to sudden temperature drop, resulting in stress concentration at the grain boundary or the generation of an oxidation layer. By using a cooling device to control the cooling of the strip, such as using a forced air cooling system to uniformly blow the surface of the strip, or adjusting the overall temperature of the strip by water cooling circulation, the cooling rate can be matched with the thermal conductivity characteristics of the material. In this process, the grain structure of the strip is stable, avoiding the formation of micro-cracks caused by local rapid cooling, and reducing the formation of oxidation spots by inhibiting the contact between oxygen and the high-temperature aluminum surface. As a result, the residual stress distribution of the strip is more uniform, and the surface oxidation layer is effectively controlled, thereby reducing the probability of black silk defects.

[0042] Compared with the prior art, the strip after annealing in the traditional process usually uses natural cooling method, which is uncontrollable in cooling rate, easy to cause temperature gradient difference in different areas of the strip, and further cause residual stress concentration and uneven oxidation layer. By introducing the cooling device, the present application actively controls the cooling process, such as adjusting the air speed of the forced air cooling system or the flow rate of the water cooling system, so that the overall temperature of the strip decreases uniformly, avoiding the randomness of natural cooling. In addition, the cooling stage is not intervened in the prior art, which makes it difficult to completely remove the oxidation layer, while the present application inhibits the oxidation reaction by controlling the cooling environment, further improving the surface quality.

[0043] Through the above technical scheme, the present application effectively solves the problems of residual stress accumulation and surface oxidation layer remaining caused by uneven cooling or improper cooling rate of the strip after annealing, reduces the probability of black silk defects on the surface of the aluminum foil, and improves the grain uniformity and surface integrity of the strip.

[0044] The application further proposes that during the annealing process, the temperature in the annealing furnace is set to 610℃, the annealing time is 5 hours, the atmosphere in the annealing furnace is controlled by the atmosphere adjusting system to be a mixed gas of nitrogen and hydrogen, and the hydrogen concentration is maintained at 3-5% to remove the surface oxide layer of the aluminum foil; and the high-frequency ultrasonic generator in step three uses ultrasonic waves with a frequency range of 40-60 kHz for cleaning, and the working time of the high-frequency ultrasonic generator is 30-60 seconds each time.

[0045] It should be noted that the temperature setting in the annealing furnace refers to the constant temperature maintained in the furnace during the annealing process, which can be realized by resistance heating or gas heating. This temperature range can promote the uniformization of aluminum foil grains and avoid excessive oxidation of the surface. The annealing time refers to the duration of the continuous heating of the strip in the annealing furnace, which can be realized by the linkage of temperature sensors and control systems. This time parameter ensures that the oxide layer is fully decomposed and the internal stress of the material is effectively released. The atmosphere adjusting system refers to a device for regulating the composition of the gas in the annealing furnace, which can be realized by the cooperative work of a gas flow meter and a proportional mixing valve. The target concentration is maintained by real-time monitoring and adjustment of the gas ratio. The mixed gas of nitrogen and hydrogen refers to a protective atmosphere with nitrogen as the main body and a certain proportion of hydrogen added. It can be realized by using a premixed gas supply device, in which nitrogen acts as an inert gas to isolate oxygen, and hydrogen acts as a reducing agent to decompose aluminum oxide. The hydrogen concentration maintained at 3-5% refers to the volume ratio range of hydrogen in the mixed gas, which can be realized by a gas analyzer and a feedback control system. This concentration range can effectively reduce the oxide layer and avoid the risk of explosion.

[0046] Specifically, when the annealing furnace temperature is set to 610℃, the aluminum foil material is in the recrystallization temperature range, which can promote grain refinement and eliminate rolling stress, while avoiding grain coarsening caused by excessive temperature. The annealing time is set to 5 hours, which allows the reduction reaction of aluminum oxide and hydrogen to proceed fully, ensuring that the surface oxide layer is completely converted into volatile substances. Nitrogen acts as a protective atmosphere to block the contact between oxygen and aluminum foil, preventing the formation of secondary oxide layers during the annealing process. When the hydrogen concentration is controlled at 3-5%, its reducing ability is sufficient to decompose aluminum oxide to generate water vapor, and this concentration is below the lower limit of hydrogen explosion, ensuring the safety of the annealing process. The combination of temperature and time optimizes the removal efficiency of the oxide layer, and the synergistic effect of nitrogen-hydrogen mixed gas achieves a balance between oxide layer removal and surface protection.

[0047] Compared with the prior art, the traditional annealing process usually adopts a single nitrogen protection or a working mode with excessively high hydrogen concentration. The single nitrogen cannot remove the existing oxide layer, and the excessively high hydrogen concentration has safety risks and increases costs. The application realizes efficient removal of the oxide layer under the premise of ensuring safety by precisely controlling the hydrogen concentration and the annealing parameters. The annealing temperature in the prior art often adopts a wide range, resulting in incomplete removal of the oxide layer or damage to the material performance, while the application makes the aluminum oxide decomposition reaction kinetics optimal by the parameter combination of 610 DEG C and 5 hours.

[0048] Through the above technical solution, the application solves the problem of black silk defects caused by residual oxide layer in the annealing process, and realizes the complete removal of the oxide layer on the surface of the aluminum foil through the synergistic control of specific temperature, time and atmosphere parameters. The scheme avoids the safety hazards caused by excessively high hydrogen concentration in the traditional process, and overcomes the technical defects that single nitrogen protection cannot remove the oxide layer, significantly improving the cleanliness of the aluminum foil surface and the quality of the finished product.

[0049] The application further provides a rolling device for reducing black silk defects of cold-rolled aluminum foil, which comprises a clamping and positioning device, a cold rolling machine body, a heating device, a high-frequency ultrasonic cleaning device, a spray cleaning system, a high-speed visual positioning unit, a spraying device, a laser surface scanner, an annealing device and a cooling device.

[0050] It should be noted that the clamping and positioning device refers to a device that stably clamps the strip steel at the preset position of the cold rolling machine through a mechanical fixing mechanism, which can be realized by a combination structure of hydraulic clamping jaws and guide rails, and its function is to eliminate the local stress concentration caused by the deviation of the strip steel. The heating device refers to a device for pre-treating the strip steel by a heat source, which can be realized by an array of electric heating pipes or a circulating hot air channel structure, and its function is to homogenize the temperature distribution of the strip steel to reduce rolling cracks. The high-frequency ultrasonic cleaning device refers to a cleaning module composed of an ultrasonic transducer and an oil circulation system, which can be realized by a combination structure of a piezoelectric ceramic generator and a multi-stage filter membrane group, and its function is to strip the contaminants in the rolling oil through high-frequency vibration. The gradient microporous filter membrane group refers to a filter assembly with a pore size decreasing distribution characteristic, which can be realized by a multi-layer ceramic composite membrane stacking structure, and its function is to intercept impurity particles of different particle sizes step by step. The high-speed visual positioning unit refers to a defect detection system based on optical imaging, which can be realized by a combination structure of a high-speed CMOS camera and an image processing chip, and its function is to capture the morphological characteristics of surface defects in real time. The laser surface scanner refers to a microscopic detection equipment based on the principle of laser reflection, which can be realized by a combination structure of a femtosecond laser source and a three-dimensional scanning probe, and its function is to generate high-resolution surface topography data.

[0051] Specifically, after the strip steel is fixed by the clamping positioning device, the heating device raises the overall temperature of the strip steel to a preset range through hot air circulation to eliminate the temperature gradient in the rolling process. The high-frequency ultrasonic cleaning device decomposes the pollutants in the rolling oil through 40-100 kHz mechanical vibration waves, and the gradient filter membrane group performs multi-stage purification treatment on the oil. The spray cleaning system performs secondary removal of the surface residues of the strip steel through high-pressure micro-mist flow. The high-speed visual positioning unit and the laser scanner work cooperatively to respectively acquire macro defect position and microscopic morphology data, generate repair parameters and transmit them to the spraying device. The spraying device adjusts the spraying angle and dosage of the sulfur / phosphorus additive according to the parameters to realize accurate coverage of the defect area. The annealing device synchronously completes the removal of the oxidation layer and the grain recombination in a high-temperature environment through a nitrogen-hydrogen mixed atmosphere.

[0052] Compared with the prior art, the existing rolling device usually adopts a single oil liquid filtration mode, which cannot effectively remove submicron particles and lacks a strip steel temperature pre-adjustment function. The present application realizes multi-stage deep purification of rolling oil through the combination of ultrasonic cleaning and gradient filtration, solves the problem of uneven temperature distribution in the strip steel rolling and annealing process through the cooperative temperature control of the heating device and the annealing device, improves the recognition accuracy of surface defects to the micron level through the dual detection mechanism of visual positioning and laser scanning, and realizes the fixed-point and quantitative treatment of the defect area through the adjustable spraying repair system.

[0053] Through the above technical solutions, the pollutant removal efficiency of the rolling oil is significantly improved, the temperature gradient in the strip steel rolling process is effectively controlled, the detection accuracy and repair accuracy of surface defects are improved, and the removal effect of the oxidation layer in the annealing process is enhanced, finally reducing the black silk defect occurrence rate of the cold-rolled aluminum foil and achieving the surface quality of the industrial application standard.

[0054] In summary, the present application realizes accurate positioning control in the strip steel rolling process, eliminates surface stress cracks caused by position deviation, effectively removes small pollutants in the rolling oil through a multi-stage oil purification system to avoid impurities embedded in the surface of the aluminum foil, realizes online identification and accurate repair of surface defects through the combination of optical detection and chemical repair, and synchronously removes the oxidation layer and inhibits secondary oxidation through the controllable atmosphere annealing process, finally comprehensively solving the black silk defect problem of the cold-rolled aluminum foil.

[0055] Finally, it should be pointed out that the above examples are only used to illustrate the technical solutions of the present application and not to limit it. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced equivalently without departing from the purpose and scope of the present application, which should be covered in the scope of the claims of the present application.

Claims

1. A rolling method for reducing black wire defects in cold-rolled aluminum foil, characterized in that, Includes the following steps: Step 1: Clamp and position the strip steel in the preset rolling area of ​​the cold rolling mill using a clamping and positioning device. Step 2: Start the transmission device of the cold rolling mill to drive the work rolls to rotate, rolling the strip steel between the work rolls. The gap between the work rolls is controlled between 0.1-1.5mm. Step 3: Clean the rolling oil of the strip steel using a high-frequency ultrasonic generator (ultrasonic frequency 40-100kHz). Filter the rolling oil through a gradient microporous filter membrane (pore size range 50-5μm). The filtered oil is then pumped back to the cold rolling mill. Step 4: Use a high-speed vision positioning unit to detect surface defects in the strip steel, capturing the defect morphology and location coordinates. Surface repair is performed by spraying sulfur / phosphorus extreme pressure additive microdroplets using a spraying device (droplet diameter controlled between 15-25μm). Step 5: Between rolling processes, perform homogenization annealing on the strip steel using an annealing device (annealing temperature controlled between 580-650℃, annealing time controlled between 4-8 hours).

2. The rolling method for reducing black wire defects in cold-rolled aluminum foil according to claim 1, characterized in that, Between steps two and three, the process also includes: using a heating device to preheat the strip to 150-250°C to reduce plastic deformation and surface cracks in the strip during rolling, thereby achieving the desired temperature distribution of the strip during rolling.

3. The rolling method for reducing black wire defects in cold-rolled aluminum foil according to claim 1, characterized in that, Between steps three and four, the process also includes further cleaning the surface of the strip steel using a spray cleaning system that employs high-pressure micro-spraying to remove tiny particulate impurities and oil stains from the surface.

4. The rolling method for reducing black wire defects in cold-rolled aluminum foil according to claim 1, characterized in that, Between steps four and five, the process also includes: using a laser surface scanner to scan the surface of the strip steel, detecting microscopic defects and their distribution on the strip steel surface in real time, generating repair data based on the shape, size, and location of the defects, and automatically adjusting the spray volume and direction of the spraying device through the control system to achieve targeted and quantitative surface repair.

5. The rolling method for reducing black wire defects in cold-rolled aluminum foil according to claim 1, characterized in that, After step five, the process also includes cooling the annealed strip using a cooling device.

6. The rolling method for reducing black wire defects in cold-rolled aluminum foil according to claim 1, characterized in that, The high-frequency ultrasonic generator in step three uses ultrasonic waves in the frequency range of 40-60kHz for cleaning, and the working time of the high-frequency ultrasonic generator is 30-60 seconds each time.

7. The rolling method for reducing black wire defects in cold-rolled aluminum foil according to claim 1, characterized in that, In the annealing process of step five, the temperature inside the annealing furnace is set at 610℃ and the annealing time is 5 hours. The atmosphere inside the annealing furnace is controlled by an atmosphere conditioning system to be a mixture of nitrogen and hydrogen, with the hydrogen concentration maintained at 3-5% to remove the oxide layer on the surface of the aluminum foil.

8. A rolling apparatus for reducing black wire defects in cold-rolled aluminum foil, used to implement the rolling method for reducing black wire defects in cold-rolled aluminum foil as described in claims 1-7, characterized in that, Includes a clamping and positioning device for clamping and positioning the strip steel in a preset rolling area of ​​a cold rolling mill; The cold rolling mill body is used to transmit power and drive the work rolls to rotate; the heating device is used to preheat the strip steel to 150-250℃ before rolling, and the heating device adopts electric heating or hot air circulation; the high-frequency ultrasonic cleaning device includes an ultrasonic generator and an ultrasonic heat exchanger, the ultrasonic generator operates at a frequency of 40-100kHz, and is used to clean the rolling oil on the surface of the strip steel. The ultrasonic generator is connected to a gradient microporous filter membrane group, and the filtered cleaning oil is delivered to the cold rolling mill through an oil pump; the spray cleaning system is used to further clean the surface of the strip steel; the high-speed vision positioning unit includes a high-precision camera system, which is used to monitor the surface defects of the strip steel in real time, capture the shape and location coordinates of the defects, and output the defect data through the control system. The equipment includes: a spraying device for precisely spraying sulfur / phosphorus extreme pressure additive microdroplets onto defects on the strip surface; a laser surface scanner for high-precision scanning of the strip surface, generating repair data based on the shape, size, and location of surface defects, and automatically adjusting the spraying volume and direction of the spraying device through a control system; an annealing device including an annealing furnace and an atmosphere conditioning system, wherein the annealing furnace is used to heat the strip to 580-650℃ and maintain it at the required annealing temperature, and the atmosphere conditioning system in the annealing furnace controls the atmosphere inside the annealing furnace to be a mixture of nitrogen and hydrogen, with the hydrogen concentration controlled at 3-5%; and a cooling device for cooling the annealed strip.

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