Surface treatment method for matte stainless steel roller coating

Abstract

The invention provides a matte stainless steel roller coating surface treatment method which comprises the following steps: carrying out vibration grinding pretreatment on a stainless steel base material, activating phosphate, carrying out sequential coating process roller coating, carrying out three-section gradient curing and the like. The problems of insufficient circulating stability of the etching liquid, low dynamic pressure control precision, insufficient coating uniformity and adhesive force and the like are effectively solved, and the method has the advantages of improving the circulating stability of the etching liquid, improving the dynamic pressure control precision and improving the coating uniformity and adhesive force.

Description

Technical Field

[0001] The present invention relates to the technical field of stainless steel surface treatment, and more particularly, to a matte stainless steel roll coating surface treatment method. Background Art

[0002] There are multiple technical defects in the traditional roll coating process for matte stainless steel treatment, which seriously affect product quality and production efficiency. First of all, the insufficient stability of the etching solution circulation is a prominent problem. During the sand surface etching process, the repeated use of the etching solution easily causes changes in the concentration gradient, which directly results in differences in the hole density on the surface of the steel strip, making the surface roughness deviation reach more than ±0.2 μm. This non-uniformity not only affects the appearance quality of the product but may also reduce the adhesion of the subsequent coating.

[0003] Secondly, the low precision of dynamic pressure control is also an urgent problem to be solved. The traditional linear guide type pressure regulating mechanism has obvious friction interference, making it difficult to accurately control the pressure actually applied to the steel strip. This instability of pressure control is directly reflected in the coating thickness, resulting in a film thickness fluctuation range exceeding ±5%, and the detection error of the pressure sensor is as high as 30%. Such a large error not only affects the uniformity of the coating but may also cause the paint to be too thick or too thin in local areas, affecting the overall performance of the product.

[0004] Finally, the insufficient coating uniformity and adhesion are another key factor restricting the improvement of product quality. The existing process parameters are often too single and cannot adapt to the characteristics of different coatings. Especially during the curing process, the curing temperature gradient does not match the rheological properties of the coating, easily leading to the orange peel effect on the coating surface, which not only affects the appearance but also reduces the adhesion between the coating and the substrate. This decrease in adhesion may cause the coating to peel or fall off during subsequent use, greatly shortening the service life of the product.

[0005] In view of the above problems, the existing technology urgently needs to be improved. Summary of the Invention

[0006] In order to solve the above technical problems, the purpose of the present invention is to provide a matte stainless steel roll coating surface treatment method, which has the advantages of improving the stability of etching solution circulation, enhancing the precision of dynamic pressure control, and improving the coating uniformity and adhesion.

[0007] To solve the above technical problems, the present invention adopts the following technical solutions:

[0008] The present invention provides a matte stainless steel roll coating surface treatment method, comprising the following steps: performing vibration grinding pretreatment on a stainless steel substrate, controlling the amplitude at 0.1 - 0.3 mm and the frequency at 50 Hz, using alumina abrasive with a particle size of 50 - 100 μm to make the surface roughness Ra reach 0.8 - 1.2 μm; immersing the pretreated substrate in a phosphate activation solution with pH = 3.5 - 4.0 for 60 - 90 seconds; performing roll coating using a forward coating process, controlling the ratio of the rotational speed (v) of the coating roll to the moving speed (v) of the substrate to satisfy 0.7 ≤ v / v ≤ 1.5, and the ratio of the rotational speed (v) of the liquid-taking roll to the moving speed (v) of the substrate to satisfy 0.25 ≤ v / v ≤ 0.9; curing in three-stage gradients: preheating section 50 - 80 °C / 30 s → main curing section 120 - 150 °C / 90 s → post-curing section 80 - 100 °C / 60 s.

[0009] Further, the present application also proposes that the contact pressure between the roller and the substrate in the steps is controlled in stages: the initial contact pressure is 100 - 150 kgf; the pressure in the main curing stage is reduced to 50 - 80 kgf; the pressure in the post-curing stage is restored to 120 ± 10 kgf.

[0010] Further, the present application also proposes that the coating comprises the following components: fluoropolymer 35 ± 5 wt%; epoxy-modified acrylic resin 20 ± 3 wt%; nano-SiO 5 - 8 wt% (particle size 30 - 50 nm); titanium oxide / aluminum oxide composite powder 3 - 5 wt%; gradient curing agent 0.5 - 1.2 wt%.

[0011] Further, the present application also proposes that the mass ratio of TiO to Al O in the titanium oxide / aluminum oxide composite powder is 1:1.2 - 1.5, and a resistivity gradient coating (10 3 -10 Ω·cm) is formed by plasma spraying.

[0012] Further, the present application also proposes that during the curing process, a temperature-speed linkage model is established:

[0013]

[0014] where T base is the reference temperature, and k is the material thermal conductivity; k = 15 - 25, n = 1.2 - 1.5.

[0015] Further, the present application also proposes that during the curing process in step (d), it further includes: using an infrared thermal imager to monitor the temperature distribution on the roller surface in real time, dynamically adjusting the heating power through a PID algorithm, and when the detected local temperature deviation exceeds 5%, starting a gradient compensation module to achieve a temperature field standard deviation ≤ 3 °C.

[0016] Furthermore, the present application also proposes that during the curing process of step (d), it further includes: spraying a composite coating containing microcapsule phase change material on the roll surface, using the heat absorption / exothermic characteristics of the material phase change to buffer temperature fluctuations, and controlling the temperature gradient during the curing process within 15 °C / m.

[0017] Furthermore, the present application also proposes that during the curing process of step (d), it further includes: training a deep reinforcement learning model, where the network depth of the learning model ≥ 15 layers, to achieve the autonomous evolution of the gradient mode under complex working conditions.

[0018] Furthermore, the present application also proposes that the method for training the deep reinforcement learning model includes:

[0019] Deep network topology optimization: Adopting a residual network architecture with ≥ 15 layers, and solving the problem of gradient disappearance through skip connections;

[0020] Hierarchical reinforcement mechanism: Constructing a three-layer decision-making model,

[0021] Perception layer: Real-time collecting process parameters such as coating thickness deviation and surface roughness;

[0022] Policy layer: Generating control instructions such as spraying paths and cooling cycles based on the PPO algorithm;

[0023] Evolution layer: Realizing the autonomous evolution of the gradient mode through an offline experience replay pool, and storing more than 10^5 groups of historical working condition data.

[0024] Furthermore, the present application also proposes that it further includes:

[0025] Dynamic gradient compensation algorithm:

[0026]

[0027] Among them, the compensation coefficient α is dynamically adjusted with the coating thickness deviation (0.2 - 0.8), and the γ value in the cooling stage decays to 0.5.

[0028] As can be seen from the above, a matte stainless steel roll coating surface treatment method provided by the present application includes steps such as vibration grinding pretreatment, phosphate activation, roll coating by a direct coating process, and three-stage gradient curing of a stainless steel substrate. By precisely controlling each process parameter and introducing a deep reinforcement learning model, problems such as insufficient etching solution circulation stability, low dynamic pressure control accuracy, and insufficient coating uniformity and adhesion are effectively solved, and it has the advantages of improving etching solution circulation stability, enhancing dynamic pressure control accuracy, and improving coating uniformity and adhesion. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a process flow chart of a matte stainless steel roll coating surface treatment method according to an embodiment of the present invention;

[0030] Figure 2 This is the temperature control module diagram in the curing stage of a matte stainless steel roll coating surface treatment method according to an embodiment of the present invention;

[0031] Figure 3 This is the structural block diagram of the deep reinforcement learning model of a matte stainless steel roll coating surface treatment method according to an embodiment of the present invention. Detailed implementation manners

[0032] The following details the implementation manners of the present invention. Examples of the implementation manners are shown in the accompanying drawings, where the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions throughout. The implementation manners described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention and should not be construed as a limitation of the present invention.

[0033] In the description of the present invention, it should be understood that if there are terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. indicating the orientation or positional relationship, they are based on the orientation or positional relationship shown in the accompanying drawings. This is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present invention, "a plurality" means two or more unless otherwise specifically defined.

[0034] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "mounted", "connected", and "connected" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection. It may be a mechanical connection or an electrical connection. It may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0035] Embodiment 1:

[0036] As Figures 1-3As shown, the traditional roll coating process has technical defects in matte stainless steel treatment, such as insufficient etching solution circulation stability, low dynamic pressure control accuracy, and insufficient coating uniformity and adhesion. These defects have led to problems such as differences in the hole density on the steel strip surface, large film thickness fluctuation ranges, orange peel effect, and decreased coating adhesion. To solve these problems, the present invention proposes a matte stainless steel roll coating surface treatment method.

[0037] The present invention solves the above technical problems through the following steps. First, the stainless steel substrate is pretreated by vibratory grinding, controlling the amplitude at 0.1 - 0.3 mm, the frequency at 50 Hz, and using alumina abrasive with a particle size of 50 - 100 μm to make the surface roughness Ra reach 0.8 - 1.2 μm. Then, the pretreated substrate is immersed in a phosphate activation solution with a pH of 3.5 - 4.0 for 60 - 90 seconds. Then, roll coating is carried out using the forward coating process, controlling the ratio of the rotation speed of the coating roller to the moving speed of the substrate to satisfy 0.7 ≤ v / v ≤ 1.5, and the ratio of the rotation speed of the liquid pickup roller to v to satisfy 0.25 ≤ v / v ≤ 0.9. Finally, it is cured in three-stage gradients: preheating section 50 - 80 °C / 30 s → main curing section 120 - 150 °C / 90 s → post-curing section 80 - 100 °C / 60 s.

[0038] Through the steps of vibratory grinding pretreatment and immersion in the phosphate activation solution, the surface roughness and chemical activity of the stainless steel substrate are improved, thereby enhancing the adhesion and uniformity of the coating. The control of the speed ratio of the coating roller and the liquid pickup roller in the forward coating process ensures the uniformity of the coating thickness and reduces the film thickness fluctuation. The three-stage gradient curing process optimizes the curing degree and performance of the coating through different combinations of temperature and time, reduces the orange peel effect, and improves the adhesion and stability of the coating. The overall solution solves the technical defects in the traditional roll coating process through the synergistic effect of multiple steps, improving the quality and consistency of stainless steel surface treatment.

[0039] In the traditional roll coating process, insufficient etching solution circulation stability is a major problem. The repeated use of the sand surface etching solution easily leads to changes in the concentration gradient, causing differences in the hole density on the steel strip surface, with a roughness deviation of more than ±0.2 μm. To solve this problem, the present invention adopts the steps of vibratory grinding pretreatment and immersion in the phosphate activation solution, ensuring the surface roughness and chemical activity of the stainless steel substrate, thereby enhancing the adhesion and uniformity of the coating.

[0040] Low dynamic pressure control accuracy is another problem. The traditional linear guide rail type pressure regulation has friction interference, resulting in a film thickness fluctuation range exceeding ±5%, and a sensor detection error of 30%. The present invention ensures the uniformity of the coating thickness and reduces the film thickness fluctuation through the control of the speed ratio of the coating roller and the liquid pickup roller in the forward coating process.

[0041] Insufficient coating uniformity and adhesion are also problems in traditional roll coating processes. The existing process parameters are single, and the curing temperature gradient does not match the rheological properties of the coating, resulting in orange peel effect and decreased adhesion. To solve this problem, the present invention proposes a three-stage gradient curing process, which optimizes the curing degree and performance of the coating through different combinations of temperature and time, reduces the orange peel effect, and improves the adhesion and stability of the coating.

[0042] During the implementation of the present invention, vibratory grinding pretreatment is a key step. By controlling the amplitude at 0.1 - 0.3 mm, the frequency at 50 Hz, and using alumina abrasive with a particle size of 50 - 100 μm, the surface roughness Ra of the stainless steel substrate reaches 0.8 - 1.2 μm. This treatment step greatly improves the surface roughness of the substrate and lays a good foundation for subsequent coating adhesion.

[0043] Soaking in phosphate activation solution is another key step. Immersing the pretreated substrate in a phosphate activation solution with pH = 3.5 - 4.0 for 60 - 90 seconds can improve the chemical activity of the substrate surface, thereby further enhancing the adhesion of the coating.

[0044] Controlling the speed ratio of the coating roller and the liquid pickup roller in the forward coating process is the key to ensuring the uniformity of the coating thickness. By controlling the ratio of the coating roller rotation speed to the substrate moving speed to satisfy 0.7 ≤ v / v ≤ 1.5, and the ratio of the liquid pickup roller rotation speed to v to satisfy 0.25 ≤ v / v ≤ 0.9, the film thickness fluctuation can be effectively reduced and the uniformity of the coating can be ensured.

[0045] The three-stage gradient curing process is the key to optimizing the curing degree and performance of the coating. Through the combination of a preheating section at 50 - 80 °C / 30 s, a main curing section at 120 - 150 °C / 90 s, and a post-curing section at 80 - 100 °C / 60 s, the orange peel effect can be reduced and the adhesion and stability of the coating can be improved.

[0046] In summary, through the synergistic effect of vibratory grinding pretreatment, soaking in phosphate activation solution, forward coating process, and three-stage gradient curing process, the present invention solves the technical problems of insufficient etching solution circulation stability, low dynamic pressure control accuracy, and insufficient coating uniformity and adhesion in traditional roll coating processes, and improves the quality and consistency of stainless steel surface treatment.

[0047] Furthermore, the present application also proposes that the contact pressure between the roller and the substrate in step (c) is controlled in stages: the initial contact pressure is 100 - 150 kgf; the pressure is reduced to 50 - 80 kgf during the main curing stage; the pressure is restored to 120 ± 10 kgf during the post-curing stage.

[0048] During the roll coating process, by controlling the contact pressure between the roller and the substrate in stages, a higher pressure can be applied in the initial stage to ensure the preliminary adhesion of the coating. Subsequently, the pressure is reduced in the main curing stage to avoid excessive compression and deformation of the coating. Finally, the pressure is restored in the post-curing stage to ensure the final adhesion and surface quality of the coating. Such staged pressure control can optimize the uniformity and adhesion of the coating, thus solving the problems of film thickness fluctuation and insufficient adhesion caused by improper pressure control in traditional processes.

[0049] Specifically, the initial contact pressure is set between 100 - 150 kgf to ensure that the coating can adhere to the substrate surface quickly and uniformly. The pressure in the main curing stage is reduced to 50 - 80 kgf to prevent the coating from being subjected to excessive compressive stress during curing, thereby maintaining the integrity and uniformity of the coating. The pressure in the post-curing stage is restored to 120 ± 10 kgf to ensure that the coating has good adhesion and surface quality during final curing. As a preferred implementation, precise control of the contact pressure can be achieved through a servo motor and a pressure sensor to meet the pressure requirements of different stages.

[0050] Thus, through the staged pressure control method of this application, the problems of low precision in dynamic pressure control and insufficient coating uniformity and adhesion existing in traditional roll coating processes are effectively solved. Compared with the prior art, the solution of this application can significantly reduce film thickness fluctuation, improve the adhesion and surface quality of the coating, and enhance the reliability and stability of the overall process.

[0051] Furthermore, this application also proposes that the coating contains the following components: fluoropolymer 35 ± 5 wt%, epoxy-modified acrylic resin 20 ± 3 wt%, nano-SiO₂ 5 - 8 wt% (particle size 30 - 50 nm), titanium oxide / aluminum oxide composite powder 3 - 5 wt%, gradient curing agent 0.5 - 1.2 wt%.

[0052] The components of the coating play a role in improving the coating performance and stability. The fluoropolymer provides excellent chemical resistance and weather resistance. The epoxy-modified acrylic resin enhances the adhesion and abrasion resistance of the coating. Nano-SiO₂ provides better coating uniformity and surface smoothness due to its small particle size. The titanium oxide / aluminum oxide composite powder enhances the mechanical strength and corrosion resistance of the coating. The gradient curing agent ensures the uniformity and stability of the coating curing process. Through the reasonable ratio and interaction of the above components, the problem of how to improve the performance and stability of the coating in the matte stainless steel roll coating surface treatment method is solved, ensuring that the coating has excellent adhesion, uniformity, and durability.

[0053] For the selection of fluoropolymer, polytetrafluoroethylene (PTFE) or fluorocarbon resin can be considered. These materials have excellent chemical resistance and weather resistance. Epoxy-modified acrylic resin can be obtained by chemically modifying epoxy resin with acrylic resin to enhance the adhesion and abrasion resistance of the coating. The particle size of nano-SiO should be controlled between 30 - 50 nm to ensure the uniformity and surface smoothness of the coating, and nano-SiO can be prepared by the sol-gel method. Titanium oxide / aluminum oxide composite powder can be prepared by physical mixing method or chemical precipitation method to ensure the uniformity of its particle size and distribution. For the selection of gradient curing agent, a two-component curing agent system can be considered. By controlling the ratio of the curing agent and the curing conditions, the uniformity and stability of the coating curing process can be ensured.

[0054] By adopting the above technical means, the coating of the present application has significant advantages in improving the performance and stability of the coating in the matte stainless steel roll coating surface treatment method. Compared with the prior art, the coating of the present application not only improves the chemical resistance, weather resistance, adhesion and abrasion resistance of the coating, but also further improves the uniformity, surface smoothness, mechanical strength and corrosion resistance of the coating through the synergistic effect of nano-SiO and titanium oxide / aluminum oxide composite powder. The application of the gradient curing agent ensures the uniformity and stability of the coating during the curing process, avoiding the common problems of uneven curing and coating defects in the traditional process. Thus, the coating of the present application significantly improves the overall performance and stability of the coating in the matte stainless steel roll coating surface treatment method.

[0055] Furthermore, the present application also proposes that the mass ratio of TiO to AlO in the titanium oxide / aluminum oxide composite powder is 1:1.2 - 1.5, and a resistivity gradient coating (10 3 -10 Ω·cm) is formed by plasma spraying.

[0056] The mass ratio of TiO to AlO in the titanium oxide / aluminum oxide composite powder is 1:1.2 - 1.5, and a resistivity gradient coating is formed by plasma spraying, aiming to solve the problems of controlling the ratio of titanium oxide and aluminum oxide in the coating and the resistivity gradient of the coating. These technical features cooperate with each other to ensure that the coating has different resistivities in different regions, thereby improving the performance and stability of the coating.

[0057] Specifically, the mass ratio of titanium oxide to aluminum oxide is 1:1.2 - 1.5. Through this ratio, the composition of the composite powder can be effectively controlled, thereby forming a stable structure in the coating. The plasma spraying technique is used to spray this composite powder onto the surface of the substrate to form a resistivity gradient coating. By adjusting the spraying process parameters, the coating can have different resistivities in different regions, so that the coating exhibits excellent performance in practical applications. For example, in the high-resistivity region, the coating can effectively block the current, while in the low-resistivity region, the coating can conduct electricity, thus realizing the multifunctionality of the coating.

[0058] Thus, by controlling the mass ratio of titanium oxide to aluminum oxide and adopting the plasma spraying technique, this application successfully solves the problems of uneven coating composition and single resistivity in the traditional technology. Compared with the prior art, the technical solution of this application not only improves the uniformity and stability of the coating, but also enables the coating to exhibit better performance in different application scenarios through the design of the resistivity gradient. Therefore, this application has significant advantages in improving the coating quality and functionality.

[0059] Furthermore, this application also proposes that during the curing process in step (d), a temperature-speed linkage model is established:

[0060]

[0061] , where T base is the reference temperature, and k is the material thermal conductivity coefficient; k = 15 - 25, n = 1.2 - 1.5.

[0062] This technical feature includes establishing a temperature-speed linkage model during the curing process. This model is realized through the formula

[0063] where T base is the reference temperature, the value range of k is from 15 to 25, and the value range of n is from 1.2 to 1.5. This model aims to dynamically adjust the curing temperature to match the coating curing speed, thereby ensuring the coating uniformity and adhesion. Through this temperature-speed linkage model, precise control of the curing process temperature can be achieved, ensuring the best curing effect at different coating speeds. This control method can solve the problems of insufficient coating uniformity and adhesion caused by the mismatch between temperature and coating speed in the traditional process.

[0064] The establishment of the temperature-speed linkage model needs to be based on the specific requirements and parameters of the curing process. First, determine the reference temperature Tbase, which is usually set according to the characteristics of the coating material and the curing requirements. Then, select appropriate k and n values, which can be determined through experiments and theoretical analysis to ensure the sensitivity and accuracy of temperature adjustment. Specifically, the real-time linkage control of temperature and coating speed can be achieved by adjusting the temperature control system of the curing equipment. For example, when the coating speed increases, the curing temperature is increased to accelerate the curing process, and vice versa. As a preferred implementation, temperature sensors and speed sensors can be integrated into the curing equipment, and the automation control of the temperature-speed linkage model can be realized through a feedback control system.

[0065] Through the temperature-speed linkage model, this application realizes the dynamic adjustment of the curing process temperature, ensuring the best curing effect at different coating speeds. Compared with the prior art, this application solves the problems of insufficient coating uniformity and adhesion caused by the mismatch between temperature and coating speed in the traditional process, and improves the quality and reliability of the coating. Therefore, this application improves the precision and stability of the process through the temperature-speed linkage model during the curing process, and has significant technical advantages.

[0066] Furthermore, this application also proposes that during the curing process in step (d), it also includes: using an infrared thermal imager to monitor the temperature distribution on the roller surface in real time. In this embodiment, a FLIR A65 infrared thermal imager (accuracy ±1°C) is used, and the heating power is dynamically adjusted through a PID algorithm (in this embodiment, a fuzzy PID algorithm is used, and the response time <0.5 s). When the detected local temperature deviation exceeds 5%, the gradient compensation module is started to achieve a temperature field standard deviation ≤3°C. This method deeply combines thermal imaging technology, fuzzy control theory and mechatronics, and overcomes the problems of "edge effect" and "snake-shaped temperature difference" in continuous metal strip coating.

[0067] During the curing process in step (d), it also includes: spraying a composite coating containing microencapsulated phase change material on the roller surface, and using the heat absorption / release characteristics of the material phase change to buffer the temperature fluctuation, and controlling the temperature gradient during the curing process within 15°C / m. The phase change material (PCM) can absorb or release a large amount of heat at a specific temperature, thereby regulating the temperature change. Microencapsulation is to wrap the phase change material in tiny capsules to prevent leakage and improve stability. Utilizing this material for temperature control during the roller coating process, especially during the curing stage, breaks through the limitations of high energy consumption and slow response of traditional temperature control methods.

[0068] During the curing process in step (d), it also includes: training a deep reinforcement learning model, and the network depth of the learning model ≥15 layers to achieve the autonomous evolution of the gradient mode under complex working conditions.

[0069] The method for training the deep reinforcement learning model includes:

[0070] Deep network topology optimization: Adopt a residual network architecture with ≥15 layers to solve the problem of gradient disappearance through skip connections;

[0071] Hierarchical reinforcement mechanism: Construct a three-layer decision-making model,

[0072] Perception layer: Real-time collect process parameters such as coating thickness deviation and surface roughness;

[0073] Policy layer: Generate control instructions such as spraying paths and cooling cycles based on the PPO algorithm;

[0074] Evolution layer: Achieve autonomous evolution of the gradient mode through an offline experience replay pool, and store more than 10^5 groups of historical working condition data.

[0075] It also includes:

[0076] Dynamic gradient compensation algorithm:

[0077]

[0078] Among them, the compensation coefficient α is dynamically adjusted with the coating thickness deviation (0.2 - 0.8), and the γ value in the cooling stage decays to 0.5.

[0079] Deep learning autonomous optimization: Based on the deep reinforcement learning model with ≥15 layers of residual networks, through hierarchical decision-making (perception layer → policy layer → evolution layer) and the dynamic gradient compensation algorithm Realize the adaptive evolution of process parameters.

[0080] Example 2:

[0081] Implementation of basic process

[0082] Substrate pretreatment:

[0083] Place a 304 stainless steel plate in a vibratory grinding machine, set the amplitude to 0.2 mm and the frequency to 50 Hz, treat it with alumina abrasive with a particle size of 75 μm for 20 minutes, and measure the surface Ra = 1.0 μm.

[0084] Immerse it in a phosphate activation solution with pH = 3.8 (containing 5 wt% zinc dihydrogen phosphate) for 75 seconds, take it out and wash and dry it.

[0085] Roll coating process:

[0086] The rotation speed of the coating roller v = 15 m / min, the moving speed of the substrate v = 12 m / min, and the speed ratio v / v = 1.25; the rotation speed of the liquid-taking roller v = 8 m / min, and the speed ratio v / v = 0.67.

[0087] Staged pressure control: Initial pressure 130 kgf → Main curing stage 70 kgf → Post-curing stage 115 kgf.

[0088] Coating formulation: Fluoropolymer 33 wt%, Epoxy-modified acrylic resin 18 wt%, Nano-SiO (40 nm) 6.5 wt%, TiO / AlO composite powder (1:1.3) 4 wt%, Gradient curing agent 0.8 wt%.

[0089] Gradient curing:

[0090] Preheating section: 70 °C / 30 s, Monitor the temperature distribution using an infrared thermal imager, Adjust the heating power by PID to make the temperature difference ≤ 2.5 °C.

[0091] Main curing section: 135 °C / 90 s, Start the temperature-speed linkage model (T_base = 130 °C, k = 20, n = 1.3).

[0092] Post-curing section: 90 °C / 60 s, Spray a phase change coating containing paraffin microcapsules (particle size 10 μm), Buffer the temperature fluctuation to a gradient ≤ 12 °C / m.

[0093] Example 2: Intelligent optimization and expansion

[0094] Deep reinforcement learning model training:

[0095] Network architecture: Use an 18-layer ResNet, The input layer receives 12-dimensional parameters such as coating thickness (±5 μm), surface Ra value (0.8 - 1.2 μm), and curing temperature deviation.

[0096] Training data: Call 10^5 sets of working conditions from the historical database, including the optimal parameter combinations under different environmental humidities (30 - 80% RH) and substrate thicknesses (0.5 - 2.0 mm).

[0097] Dynamic compensation algorithm: Set α = 0.6 (α = 0.8 when the thickness deviation > 3 μm), γ = 0.5 in the cooling stage, Optimize the spraying path through Q-value iteration.

[0098] Composite powder preparation:

[0099] Mix TiO and AlO in a ratio of 1:1.4, Form a gradient structure with a resistivity ranging from 10 3 (surface layer) to 10 Ω·cm (bottom layer) by plasma spraying (power 50 kW, carrier gas Ar / H = 9:1).

[0100] Experimental data

[0101] Perform performance tests on the matte stainless steel plate prepared in Example 1:

[0102] Glossiness: GU = 15 ± 2 measured at an incident angle of 60° (GU of the traditional process is 25 - 30).

[0103] Wear resistance: Mass loss ≤ 2 mg after 5000 cycles of Taber abrasion test (CS - 10 wheel, 1 kg load).

[0104] Salt spray resistance: No blistering, peeling, and corrosion propagation width < 0.5 mm after 1000 h of neutral salt spray test.

[0105] Industrial application

[0106] This method has been successfully applied to the production line of elevator decorative panels. Compared with the original process, the defective rate of the product has decreased from 8% to 1.2%, and the energy consumption has been reduced by 18%.

[0107] It should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the embodiments, for those skilled in the art, they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. However, any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A matte stainless steel roller coating surface treatment method, characterized in that The following steps are involved: (a) The stainless steel substrate is pre-treated by vibration grinding, with an amplitude of 0.1-0.3 mm and a frequency of 50 Hz, using alumina sand with a particle size of 50-100 μm, so that the surface roughness Ra reaches 0.8-1.2 μm; (b) immersing the pretreated substrate in a phosphate activation solution with a pH of 3.5-4.0 for 60-90 seconds; (c) roller coating is performed by a straight coating process, and the ratio of the coating roller speed (v) to the substrate moving speed (v) is controlled to satisfy 0.7≤v / v≤1.5, and the ratio of the liquid taking roller speed (v) to the substrate moving speed (v) is controlled to satisfy 0.25≤v / v≤0.9; (d) Gradient curing is divided into three stages: preheating stage 50-80℃ / 30s→main curing stage 120-150℃ / 90s→post-curing stage 80-100℃ / 60s.

2. The matte stainless steel roller coating surface treatment method according to claim 1, characterized in that: The contact pressure between the roller and the substrate in step (c) is controlled in stages: Initial contact pressure 100-150kgf; The pressure in the main curing stage is reduced to 50-80kgf; The pressure is restored to 120±10kgf in the post-curing stage.

3. The matte stainless steel roller coating surface treatment method according to claim 1, characterized in that: The coating used in step (c) comprises the following components: Fluoropolymer 35±5wt%; Epoxy modified acrylic resin 20±3wt%; Nano-SiO5-8wt% (particle size 30-50nm); Titanium oxide / aluminum oxide composite powder 3-5wt%; Gradient curing agent 0.5-1.2wt%.

4. The matte stainless steel roller coating surface treatment method according to claim 3 is characterized in that: The mass ratio of TiO2 to Al2O3 in the titanium oxide / aluminum oxide composite powder is 1:1.2-1.5, and a resistivity gradient coating (10 3 -10Ω·cm).

5. The matte stainless steel roller coating surface treatment method according to claim 1, characterized in that: During the curing process of step (d), a temperature-speed linkage model is established: Among them, T base is the reference temperature, k is the thermal conductivity of the material; k = 15-25, n = 1.2-1.

5.

6. The matte stainless steel roller coating surface treatment method according to claim 1, characterized in that: During the curing process of step (d), it also includes: using an infrared thermal imager to monitor the temperature distribution of the roller surface in real time, dynamically adjusting the heating power through a PID algorithm, and when it is detected that the local temperature deviation exceeds 5%, starting the gradient compensation module to achieve a temperature field standard deviation of ≤3°C.

7. The matte stainless steel roller coating surface treatment method according to claim 1, characterized in that: The curing process of step (d) also includes: spraying a composite coating containing microcapsule phase change material on the roller surface, using the phase change heat absorption / release characteristics of the material to buffer temperature fluctuations, and controlling the temperature gradient of the curing process within 15°C / m.

8. The matte stainless steel roller coating surface treatment method according to claim 1, characterized in that: During the solidification process of step (d), it also includes: training a deep reinforcement learning model, wherein the network depth of the learning model is ≥ 15 layers, to achieve autonomous evolution of the gradient mode under complex working conditions.

9. The matte stainless steel roller coating surface treatment method according to claim 8, characterized in that: The method for training a deep reinforcement learning model comprises: Deep network topology optimization: adopt ≥15 layers of residual network architecture and solve the gradient vanishing problem through skip connections; Layered reinforcement mechanism: building a three-layer decision-making model, Perception layer: real-time collection of process parameters such as coating thickness deviation and surface roughness; Strategy layer: Generate control instructions such as spray path and cooling cycle based on PPO algorithm; Evolution layer: The autonomous evolution of the gradient mode is achieved through the offline experience replay pool, storing more than 10^5 sets of historical operating condition data.

10. The matte stainless steel roller coating surface treatment method according to claim 9, characterized in that: Also includes: Dynamic gradient compensation algorithm: The compensation coefficient α is dynamically adjusted with the coating thickness deviation (0.2-0.8), and the γ value in the cooling stage decays to 0.5.

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