Low-temperature production process of aluminum-plastic composite plate

Abstract

This invention discloses a low-temperature production process for aluminum composite panels, characterized by the following steps performed in sequence: Plastic granule mixing step: adding plastic raw materials into a mixing device for mixing; granule extrusion step: heating and melting the mixed material through an extruder and extruding it; plasticizing step: plasticizing the extruded molten material; sheeting step: pressing the plasticized material into a plastic substrate; polymer film bonding step: bonding a polymer film to at least one surface of the plastic substrate; high-low temperature aluminum sheet composite step: bonding the substrate treated with the polymer film with aluminum sheets treated with high and low temperatures to form a composite panel; cooling and forming step: cooling the composite panel to set its shape; inspection and coating step: inspecting the cooled and shaped panel for quality and covering its surface with a protective film; trimming and shearing step: trimming and shearing the edges of the inspected and coated panel to a fixed length; finished product unloading step: stacking or packaging the trimmed and sheared finished products to complete the unloading process.

Description

Technical Field

[0001] This invention relates to the technical field of aluminum composite panels, and in particular to a low-temperature production process for aluminum composite panels. Background Technology

[0002] Aluminum composite panels (ACPs), a new type of composite material, consist of a plastic core layer and two aluminum sheets. They combine the hardness of metal with the lightness of plastic and are widely used in building curtain walls, interior decoration, and billboards. The quality of their manufacturing process directly determines the flatness, composite strength, and durability of the panels.

[0003] Currently, the mature aluminum composite panel (ACP) production process in the industry typically employs a high-temperature lamination technique. This involves heating aluminum sheets to a high temperature range of 120°C to 180°C, allowing the polymer adhesive film to fully melt before pressing it onto the plastic core board. However, this high-temperature process has the following inherent drawbacks in practical applications: First, the plastic core board suffers from severe thermal deformation. The coefficient of thermal expansion of plastic materials is much higher than that of aluminum. Under high-temperature composite conditions, the plastic core board expands significantly in volume after heating and shrinks considerably after cooling. This results in significant thermal stress within the board, ultimately manifesting as warping and unevenness of the board surface, severely affecting the product's appearance and installation performance.

[0004] Secondly, shape control is difficult. During high-temperature processing, the significant temperature difference between the aluminum sheet and the plastic core board, coupled with inconsistent cooling rates after lamination, easily leads to shape defects such as twisting and bending. This is especially pronounced for large-format aluminum composite panels, where the shape control issues caused by high-temperature processing are even more severe, making it difficult to improve yield rates.

[0005] Third, the operating window is narrow, and process control is difficult. High-temperature lamination is highly sensitive to parameters such as temperature, pressure, and speed. Temperature fluctuations exceeding ±5℃ can lead to over-melting and flow of the polymer film or insufficient melting, resulting in unstable composite interface quality. This places extremely stringent requirements on the technical experience of operators and the precision of equipment control.

[0006] Fourth, it has high energy consumption and high production costs. Heating aluminum sheets to over 120°C requires a large amount of thermal energy, and strong cooling is required after lamination. The alternating heating and cooling process wastes energy and increases production costs.

[0007] To address the shortcomings of the aforementioned high-temperature processes, those skilled in the art have attempted to alleviate the heat deformation problem by lowering the lamination temperature. However, low-temperature lamination presents new challenges, such as insufficient melting of the polymer film and inadequate interfacial bonding strength. How to achieve uniform melting and firm adhesion of the polymer film under low-temperature conditions, while ensuring a flat surface and excellent shape, has become a key technological bottleneck restricting the advancement of aluminum composite panel production technology.

[0008] This invention, through equipment upgrades and process innovation, adopts a technical solution combining dual-oven gradient preheating with steel-steel composite roller groups, successfully achieving a breakthrough in the low-temperature production process of aluminum composite panels and effectively solving the hidden defects of the aforementioned high-temperature processes. Summary of the Invention

[0009] The present invention proposes a low-temperature production process for aluminum composite panels, which solves the above-mentioned problems existing in the use of existing technologies.

[0010] The technical solution of this invention is implemented as follows: A low-temperature production process for aluminum composite panels, characterized by comprising the following steps performed in sequence: Plastic granule mixing steps: Put the plastic raw materials into the mixing equipment for mixing; Pellet extrusion step: The stirred mixture is heated, melted, and extruded through an extruder; Plasticizing step: Plasticizing the extruded molten material; Tableting step: The plasticized material is pressed into a plastic substrate; Step of attaching polymer film: attaching polymer film to at least one surface of the plastic substrate; Low-temperature aluminum sheet lamination steps: A substrate treated with a polymer film is laminated with an aluminum sheet preheated at low temperature to form a composite plate; specifically, the first aluminum sheet and the second aluminum sheet are continuously conveyed to the pretreatment area by an unwinding device, and after degreasing and / or chemical conversion treatment, they enter the lamination unit under tension control; the first aluminum sheet and the second aluminum sheet are respectively preheated by a gradient through a double oven set at the front and back, and the preheating temperature is controlled in the low-temperature range of 60°C to 100°C; a plastic substrate with a polymer film already adhered to its surface is simultaneously conveyed between the first aluminum sheet and the second aluminum sheet, so that the first aluminum sheet is on the upper side of the substrate and the second aluminum sheet is on the lower side of the substrate. The aluminum sheet is located on the underside of the substrate; the three components are pressed together at a linear speed of 0.5 m / min to 5 m / min under the action of a steel-steel composite roller group, with the composite pressure controlled between 1.0 MPa and 4.0 MPa, and the composite roller temperature controlled between 40°C and 80°C; through the aforementioned low-temperature preheating and steel-steel roller composite, the polymer film is uniformly melted and impregnated at a lower temperature, enhancing the interfacial bonding force with the aluminum sheet, while avoiding overheating and deformation of the plastic substrate; the thickness uniformity of the composite aluminum-plastic board is monitored by an online thickness gauge, and the edge alignment between the aluminum sheet and the core board is controlled by an adjustment device to ensure that the composite interface is free of bubbles, wrinkles, and misalignment; Cooling and forming step: The composite board is cooled to set its shape; Inspection of the coating process: After the board has cooled and solidified, a quality inspection is carried out, and a protective film is applied to the surface. Trimming and cutting steps: Trim and cut the edges of the laminated board to a fixed length after inspection; Finished product unloading steps: Stack or package the trimmed and cut finished products to complete the unloading process.

[0011] Preferably, in the plastic granule mixing step, the mixing time is 10-40 minutes and the mixing speed is 100-800 rpm.

[0012] Preferably, in the granule extrusion step, the operating temperature of the extruder is 140℃-260℃.

[0013] Preferably, the plasticizing step specifically includes: conveying the molten material extruded by the extruder to a plasticizing screw or dynamic mixing device, and further homogenizing it at a plasticizing temperature of 180°C to 240°C for 1 to 5 minutes. The shearing action of the screw ensures that the components in the material are fully mixed, the molecular chains are arranged more uniformly, internal stress of the melt is eliminated, and the melt flowability and film stability are improved.

[0014] Preferably, the tableting step specifically includes: conveying the plasticized molten material through the extruder head to at least a pair of relatively rotating pressure rollers, wherein the gap between the pressure rollers is set to 1 mm to 10 mm according to the thickness of the target plastic substrate, the temperature of the pressure rollers is controlled within the range of 30°C to 80°C, and by adjusting the speed of the pressure rollers to match the extrusion speed, the material is pressed and formed into a continuous plastic substrate with uniform thickness and smooth surface between the pressure rollers. At the same time, the calendering action of the pressure rollers eliminates the micropores inside the material, thereby improving the density and flatness of the substrate.

[0015] Preferably, the tableting step specifically includes the following process control steps: (1) Configuration of the pressure roller group: a three-roller or four-roller calender is used as the tableting execution mechanism, the surface of the pressure roller is chrome-plated or mirror-polished, the surface roughness Ra≤0.2μm, and the diameter of the pressure roller is 300mm to 600mm; (2) Gap adjustment: Based on the thickness of the target plastic substrate, the gap between the first pair of pressure rollers is preset to 1.0 mm to 10.0 mm by hydraulic or electric gap adjustment device, and the gap between subsequent pressure rollers is gradually reduced by 0.1 mm to 0.5 mm to achieve progressive thinning and reduce internal stress concentration; (3) Temperature zone control: Each pressure roller is equipped with an independent circulating temperature control system. The temperature zones of the pressure rollers are set along the material flow direction as follows: 30℃ to 50℃ in the inlet section, 50℃ to 70℃ in the middle section, and 40℃ to 60℃ in the outlet section, so that the material experiences a temperature gradient change of "preheating-calendering-shaping" during the pressing process. (4) Speed ​​synchronization control: Each pressure roller is driven to operate independently by a servo motor. The PLC control system monitors the extruder outlet linear speed and the linear speed of each pressure roller in real time to ensure that the speed deviation is ≤0.5% and avoid material accumulation or stretching due to speed mismatch. (5) Pressure adjustment: Pressure sensors are installed at both ends of the pressure roller to monitor the linear pressure between the roller gaps in real time. The linear pressure is stabilized in the range of 20N / mm to 80N / mm through a closed-loop control system to ensure that the transverse thickness difference of the plate is ≤0.05mm. (6) Online thickness monitoring: An online thickness gauge is installed at the tableting outlet to continuously monitor the thickness of the plastic substrate. When the thickness deviation exceeds the set threshold, the pressure roller gap or extrusion amount is automatically adjusted. (7) Surface treatment: During the pressing process, release coating or a small amount of release agent is sprayed on the surface of the pressing roller to prevent molten material from adhering to the roller surface and ensure the smoothness of the substrate surface; (8) Stress relief: After the plastic substrate is pressed, it is introduced into the buffer bracket by the guide roller and naturally relaxed for 30 to 120 seconds in a tension-free state to eliminate the residual stress generated during the rolling process and prevent the substrate from shrinking and deforming.

[0016] Preferably, in the low-temperature aluminum sheet composite step, the dual ovens set up before and after the aluminum sheet include a first oven and a second oven. The preheating temperature of the first oven is 50°C to 70°C, and the preheating temperature of the second oven is 70°C to 100°C, so that the aluminum sheet undergoes a gradient heating preheating process.

[0017] Preferably, the steel-steel composite roller group consists of one or more pairs of steel pressure rollers with a roller surface hardness of HRC58-62 and a roller surface roughness Ra≤0.4μm. Hydraulic synchronization mechanisms are provided at both ends of the composite roller group to ensure uniform distribution of composite pressure.

[0018] Preferably, the cooling and molding step adopts air cooling or water cooling, and the cooling temperature is 5°C to 30°C.

[0019] Preferably, in the inspection and coating step, the protective film is attached to the surface of the board by electrostatic adsorption or hot pressing; in the trimming and cutting step, the cutting size error is controlled within ±2mm; the finished product unloading step includes automatic stacking and wrapping of the finished products.

[0020] Compared with the prior art, the low-temperature production process of aluminum composite panels described in this invention has the following advantages: This invention abandons the traditional high-temperature composite process, controlling the preheating temperature of the aluminum sheet within a low-temperature range of 60℃ to 100℃. This significantly reduces the heat input to the plastic core board during the composite process, decreasing thermal expansion by more than 60%. The resulting composite material exhibits significantly reduced internal thermal stress, achieving a surface flatness of ≤0.3mm / m, an improvement of over 40% compared to high-temperature processes. This fundamentally solves the problems of warping and unevenness caused by high-temperature processes.

[0021] This invention incorporates dual ovens before and after the aluminum sheet is laminated, subjecting the aluminum sheet to a gradient temperature increase process: 50°C to 70°C (first oven) and 70°C to 100°C (second oven). This gradual preheating method avoids localized overheating of the aluminum sheet surface and ensures uniform temperature when the aluminum sheet enters the lamination zone. This allows the polymer film to fully melt and wet within the low-temperature range of 60°C to 100°C, achieving an interfacial bonding strength of over 7.5 N / mm, thus solving the technical problem of insufficient low-temperature lamination bonding strength.

[0022] This invention uses a steel-steel composite roller assembly to replace the traditional steel-rubber roller assembly. The roller surface hardness reaches HRC58-62, and the composite pressure can be increased to 1.0MPa to 4.0MPa (30% to 50% higher than the traditional process). Under low-temperature conditions, the insufficient thermal energy is compensated by increasing the composite pressure, allowing the polymer film to fully flow and fill the microscopic pits on the aluminum sheet surface under pressure, forming a strong mechanical anchor and chemical bond. The composite interface is free of bubbles and delamination, and the peel strength meets and exceeds national standards.

[0023] Because the composite process is completed at low temperatures, the plastic core board has a short thermal history and minimal heat accumulation, preserving the original molecular orientation and crystalline morphology of the material. This results in a reduction of post-shrinkage during subsequent cooling and storage to below 0.5 mm / m. Combined with the stress-relieving process in the pressing step, the final product exhibits excellent dimensional stability and anti-warping capabilities, meeting the stringent requirements of high-end curtain wall decoration.

[0024] This invention expands the composite temperature window from ±5℃ in high-temperature processes to ±15℃, significantly reducing sensitivity to temperature fluctuations. The steel-steel composite roller assembly, combined with a hydraulic synchronization mechanism, ensures uniform composite pressure distribution, with a pressure difference between the edge and center ≤0.2MPa. Operators no longer need to frequently adjust parameters, ensuring a stable and controllable production process. This reduces reliance on operational experience, allowing new employees to become competent after short-term training, significantly lowering personnel training costs and reducing the risk of quality fluctuations.

[0025] This invention upgrades equipment by adding a double oven and a steel-steel composite roller assembly, resulting in a short investment payback period. The low-temperature process reduces aluminum sheet heating energy consumption by more than 40%, correspondingly reduces cooling load, and lowers overall energy consumption by 35%. Simultaneously, the low-temperature environment reduces thermal decomposition of plastic materials and VOCs release, making the production process more environmentally friendly and aligning with the development direction of green manufacturing.

[0026] The aluminum composite panels produced by the process of this invention maintain high peel strength, while the panel flatness, dimensional stability, and weather resistance are all superior to those produced by traditional high-temperature processes. This can meet the needs of more high-end application scenarios, such as large-area curtain walls, high-end exhibition panels, and precision instrument housings, significantly enhancing market competitiveness.

[0027] In summary, this invention, through the technological innovation of dual-oven gradient preheating and steel-steel composite roller group, successfully transforms the aluminum composite panel production process from a high-temperature route to a low-temperature route. This completely solves the inherent defects of high-temperature processes, such as uncontrolled panel shape, difficult operation, and high energy consumption. It achieves multiple beneficial effects, including flat panel surface, good composite process, excellent panel shape, and easy control of production operation, demonstrating significant technological progress and broad industrial application prospects. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of an aluminum composite panel production process according to this embodiment. Detailed Implementation

[0030] The following will refer to the appendices in the embodiments of the present invention. Figure 1 The technical solutions in the embodiments of the present invention are clearly and completely described herein. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention. Example

[0031] The aluminum composite panel production process of the present invention will be further described in detail below with reference to specific embodiments. These embodiments are intended to exemplify the implementation of the present invention and are not intended to limit the scope of protection of the present invention. Example

[0032] This embodiment provides a low-temperature production process for aluminum composite panels, which is carried out according to the following steps: Step 1: Mixing plastic granules. Add 70 parts of low-density polyethylene (LDPE) granules, 30 parts of high-density polyethylene (HDPE) granules, 8 parts of titanium dioxide, 0.4 parts of antioxidant 1010, and 0.6 parts of calcium stearate to a high-speed mixer. Mix for 25 minutes at a speed of 550 rpm to ensure that all components are fully dispersed and uniform. The material temperature should be controlled below 45℃ to prevent the low-melting-point additives from melting and agglomerating prematurely.

[0033] Step 2, Pellet Extrusion. The uniformly mixed material is conveyed to a single-screw extruder via a vacuum feeder. The extruder screw has a length-to-diameter ratio of 30:1 and a compression ratio of 3.2. The extruder temperatures are set as follows: feeding section 145℃, compression section 175℃, metering section 195℃, and die head 205℃. The screw speed is 42 rpm. After being heated, melted, sheared, and mixed within the extruder, the material is extruded from the T-die head into molten sheets.

[0034] Step 3, Plasticization. The molten material extruded from the extruder enters a dynamic mixing unit for further plasticization. This unit employs a twin-screw mixing structure, with the plasticization temperature controlled at 210℃ and a material residence time of approximately 3.5 minutes. Through the strong shearing action of the screws, the components in the material are thoroughly mixed, the molecular chains become more uniform, internal stress in the melt is eliminated, and melt flowability and film stability are improved. The plasticized melt is then filtered through a screen changer to remove impurities before proceeding to the next process.

[0035] Step 4, Tableting Step. This step uses a four-roll calender for tableting, and is performed according to the following process control steps: (1) Configuration of pressure roller group: The calender consists of four pressure rollers with a diameter of 450mm. The surface of the pressure rollers is chrome-plated and mirror-polished, with a surface roughness Ra=0.12μm to ensure the surface smoothness of the substrate.

[0036] (2) Gap adjustment: Based on the target substrate thickness of 3.0mm, the gap between the first pair of pressure rollers is preset to 4.2mm, the gap between the second pair of pressure rollers is preset to 3.5mm, the gap between the third pair of pressure rollers is preset to 3.1mm, and the gap between the fourth pair of pressure rollers, which are used as shaping rollers, is kept at 3.0mm. The gaps of each roller are gradually reduced by 0.7mm, 0.4mm, and 0.1mm to achieve progressive thinning and reduce internal stress concentration.

[0037] (3) Temperature zone control: Each pressure roller is equipped with an independent circulating temperature control system. The temperature of the pressure roller is set along the material flow direction as follows: 45℃ in the inlet section (first roller), 65℃ in the middle section (second roller), 55℃ in the outlet section (third roller), and 50℃ in the fourth roller, so that the material undergoes a temperature gradient change of "preheating-calendering-shaping" during the pressing process.

[0038] (4) Speed ​​synchronization control: The servo motor drives each pressure roller to operate independently. The PLC control system monitors the extruder outlet linear speed (about 1.5m / min) and the linear speed of each pressure roller in real time to ensure that the deviation of each roller linear speed is ≤0.3% and avoid material accumulation or stretching due to speed mismatch.

[0039] (5) Pressure adjustment: Pressure sensors are installed at both ends of the pressure roller to monitor the linear pressure between the roller gaps in real time. The linear pressure is stabilized within the range of 50N / mm±3N / mm through a closed-loop control system to ensure that the transverse thickness difference of the plate is ≤0.04mm.

[0040] (6) Online thickness monitoring: A β-ray online thickness gauge is installed at the tableting outlet to continuously monitor the thickness of the plastic substrate. When the thickness deviation exceeds ±0.08mm, the system automatically adjusts the gap of the third pair of pressure rollers or the speed of the extruder screw to achieve closed-loop control.

[0041] (7) Surface treatment: During the tableting process, food-grade release agent is intermittently sprayed onto the surface of the pressure roller through a micro-spraying device to prevent molten material from adhering to the roller surface and to ensure that the substrate surface is free of scratches and roller sticking marks.

[0042] (8) Stress relief: After the plastic substrate is pressed and formed, it is introduced into the buffer bracket by the guide roller and naturally relaxed for 90 seconds in a tension-free state to eliminate the residual stress generated during the rolling process and prevent the substrate from shrinking and deforming in the future.

[0043] Through the above-mentioned refined control, the plastic substrate produced has a thickness of 3.01mm (target 3.0mm), a transverse thickness range of 0.03mm, and a smooth and defect-free surface, meeting the requirements for subsequent lamination.

[0044] Step 5: Applying the polymer film. EVA (ethylene-vinyl acetate copolymer) adhesive film, 0.10 mm thick, is continuously applied to both sides of the pressed plastic substrate using an unwinding device. The bonding temperature is 70℃, the bonding pressure is 0.35 MPa, and the bonding speed is 1.5 m / min. After bonding, a flattening roller is used to remove air bubbles between the film and the substrate, ensuring a tight bond between the adhesive film and the core board surface, forming a laminated core board.

[0045] Step 6, Low-temperature aluminum sheet composite step. Take two rolls of aluminum alloy sheet (grade 3003) with a thickness of 0.4mm and a width matching the core board, and perform the following processing on each: (1) Aluminum sheet pretreatment: Two rolls of aluminum sheets are continuously conveyed to the pretreatment area through the unwinding device, and are successively subjected to alkaline washing and degreasing, water washing, and chemical conversion treatment (zirconium-titanium treatment) to form an environmentally friendly conversion film layer on the surface of the aluminum sheet, which enhances the adhesion to the polymer film.

[0046] (2) Gradient preheating in dual ovens: The first and second aluminum sheets after pretreatment are successively placed in dual ovens set up in front and behind for gradient preheating. The temperature of the first oven is 60℃ and the temperature of the second oven is 85℃. The aluminum sheet takes 15 seconds to pass through each oven, and the total preheating time is 30 seconds, so that the aluminum sheet undergoes a gradient heating process from 60℃ to 85℃. When it comes out of the second oven, the temperature of the aluminum sheet is stable between 82℃ and 85℃.

[0047] (3) Synchronous conveying: The plastic substrate with the polymer film attached to its surface is synchronously conveyed between the first aluminum sheet and the second aluminum sheet, so that the first aluminum sheet is located on the upper side of the substrate and the second aluminum sheet is located on the lower side of the substrate. The three are aligned and enter the steel-steel composite roller group under the guidance of the guide roller.

[0048] (4) Steel-steel roller composite: The composite roller assembly consists of a pair of steel pressure rollers with a diameter of 550mm, a roller surface hardness of HRC60, and a roller surface roughness of Ra=0.3μm. Hydraulic synchronization mechanisms are installed at both ends of the two rollers. The composite pressure is set to 2.5MPa, the composite linear speed is 1.5m / min, and the composite roller temperature is controlled at 60℃ (through constant temperature maintained by circulating water inside the rollers). The three components are pressed together under the action of the steel-steel composite rollers to form an aluminum-plastic composite panel.

[0049] (5) Process control: The aluminum sheet is uniformly heated in a low-temperature range through gradient preheating in a dual oven; the EVA film is fully melted and impregnated at a low temperature of 60℃ to 85℃ by the high pressure of the steel-steel composite roller, forming a firm bond with the upper and lower aluminum sheets. During the composite process, the common problems of overheating and softening of the plastic substrate and edge glue overflow in high-temperature processes are completely eliminated. The total thickness of the composite aluminum-plastic board is monitored by an online thickness gauge (target 3.8mm, deviation ≤0.1mm), and the edge alignment of the aluminum sheet and the core board is controlled by a photoelectric alignment device to ensure that the edge alignment error of the aluminum sheet and the core board on both sides is ≤0.8mm, and the composite interface is free of bubbles, wrinkles and misalignment.

[0050] Step 7, Cooling and Shaping. The composite aluminum-plastic sheet is placed into a wind-cooled cooling channel. The cooling air temperature is 18℃, and the air velocity is 6m / s. A top-and-bottom blowing method is used to ensure uniform cooling of the sheet. The cooling time is 5 minutes, reducing the sheet temperature to below 35℃, thus completing the shaping process. Guide rollers are used for support during cooling to prevent the sheet from sagging and deforming due to its own weight.

[0051] Step 8, Inspect the lamination process. After cooling and setting, the boards enter the online inspection station: (1) Quality inspection: The CCD vision inspection system is used in conjunction with manual visual inspection to check whether there are defects such as bubbles, scratches, bumps, aluminum sheet scratches, and composite delamination on the surface of the board. In this embodiment, a total of 100 boards were inspected, 98 of which were qualified and 2 were unqualified (both of which had minor scratches on the surface during transportation). The unqualified products were directly rejected and sent to the scrap area.

[0052] (2) Covering with protective film: After passing inspection, the boards are immediately placed in the film-coating station, where a 0.12mm thick PE protective film is applied to the upper surface of the boards. The film-coating method uses electrostatic adsorption combined with rubber roller pressure, with an electrostatic voltage of 10kV and a pressure of 0.3MPa, to ensure that the protective film is applied smoothly without air bubbles.

[0053] Step 9, Trimming and Shearing. The qualified laminated sheets are sent to the trimming and shearing unit: (1) Trimming: First, use a disc to cut off the irregular edges on both sides, with a cut of about 12mm on each side. After trimming, the width of the plate is accurate to 1220mm (target width), and the cutting width error is controlled within ±1mm.

[0054] (2) Fixed-length shearing: Fixed-length shearing is performed according to customer requirements. In this embodiment, the shearing length is 2440mm. The shearing is completed during the conveying of the sheet material using a flying shear mechanism. The shearing accuracy is ±1.5mm, and the cut is smooth and burr-free.

[0055] Step 10, Finished Product Offline Step. The cut finished sheets are conveyed to the automated stacking station via a conveyor belt. (1) Automatic stacking: The robotic arm grabs the boards and neatly stacks them on the pallet, with 10 boards per package, and protective paper strips are placed between the layers to prevent scratches.

[0056] (2) Packaging: After stacking, wrap with stretch film, cover with waterproof kraft paper on the outside, and add corner protectors to protect the four corners.

[0057] (3) Labeling and warehousing: Affix product labels (including specifications, production date, inspector code, process label "low temperature composite" and other information) and transfer them to the finished product warehouse by forklift.

[0058] Product testing results: The aluminum composite panel prepared in this embodiment was tested by the National Building Materials Testing Center, and its main performance indicators are as follows: Peel strength: 8.2 N / mm (standard requirement ≥5.0 N / mm) Surface flatness: ≤0.25mm / m (far superior to the national standard ≤1.0mm / m) Board warpage: ≤0.8mm (diagonal 1000mm) Thickness deviation: ±0.08mm Composite interface condition: No bubbles, no delamination, no wrinkles Temperature resistance: No cracking or delamination after 20 cycles from -40℃ to 80℃. Product qualification rate: 98.0% Example

[0059] This embodiment is basically the same as Embodiment 1, except that some process parameters have been adjusted to verify the process window of the present invention.

[0060] Step 4, pressing process. The target substrate thickness is 4.0mm. The initial gap between the first pair of pressure rollers is preset to 5.5mm, gradually decreasing to 4.0mm. The pressure roller temperatures are set as follows: inlet section 40℃, middle section 60℃, outlet section 50℃. The linear pressure is stabilized at 45N / mm ± 4N / mm.

[0061] Step 6, Low-temperature aluminum sheet lamination step. The dual oven temperatures are set as follows: first oven 55℃, second oven 75℃; lamination pressure 3.5MPa; lamination linear speed 1.2m / min; lamination roller temperature 50℃.

[0062] The remaining steps are the same as in Example 1.

[0063] Testing showed that the aluminum composite panel produced in this embodiment had a peel strength of 7.6 N / mm and a surface flatness of ≤0.30 mm / m. All indicators met the requirements, proving that the process of this invention can still stably produce qualified products after parameter adjustment.

[0064] Example 3 (Comparative Example: Traditional High-Temperature Process) This comparative example was produced using a traditional high-temperature composite process to verify the technical advantages of the low-temperature process of this invention.

[0065] Steps 1-5 are the same as in Example 1.

[0066] Step 6, High-temperature aluminum sheet lamination step (comparative example). The aluminum sheet was heated to 150℃ (traditional high-temperature range), without using a double oven gradient preheating method; the lamination roller group used a combination of steel and rubber rollers, with a lamination pressure of 1.5MPa; the lamination temperature was 120℃; the remaining conditions were the same as in Example 1.

[0067] Steps 7-10 are the same as in Example 1.

[0068] Comparative product test results: Peel strength: 7.9 N / mm (slightly lower than Example 1) Surface flatness: ≤0.85mm / m (significantly inferior to Example 1) Board warpage: ≤3.2mm (some boards exceed the warpage limit) Product qualification rate: 91.5% (the main defects are uneven board shape and edge warping) Energy consumption comparison: Example 1 saves 42% more energy than the comparative example. The comparative results show that the low-temperature process of the present invention maintains high peel strength while significantly improving the flatness and shape control of the board surface compared to the traditional high-temperature process. The pass rate is increased by 6.5 percentage points and energy consumption is reduced by more than 40%, which fully verifies the advanced nature and practicality of the technical solution of the present invention.

[0069] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A low-temperature production process for aluminum composite panels, characterized in that, This includes the following steps performed in sequence: Plastic granule mixing steps: Put the plastic raw materials into the mixing equipment for mixing; Pellet extrusion step: The stirred mixture is heated, melted, and extruded through an extruder; Plasticizing step: Plasticizing the extruded molten material; Tableting step: The plasticized material is pressed into a plastic substrate; Step of attaching polymer film: attaching polymer film to at least one surface of the plastic substrate; Low-temperature aluminum sheet lamination steps: A substrate treated with a polymer film is laminated with an aluminum sheet preheated at low temperature to form a composite plate; specifically, the first aluminum sheet and the second aluminum sheet are continuously conveyed to the pretreatment area by an unwinding device, and after degreasing and / or chemical conversion treatment, they enter the lamination unit under tension control; the first aluminum sheet and the second aluminum sheet are respectively preheated by a gradient through a double oven set at the front and back, and the preheating temperature is controlled in the low-temperature range of 60°C to 100°C; a plastic substrate with a polymer film already adhered to its surface is simultaneously conveyed between the first aluminum sheet and the second aluminum sheet, so that the first aluminum sheet is on the upper side of the substrate and the second aluminum sheet is on the lower side of the substrate. The aluminum sheet is located on the underside of the substrate; the three components are pressed together at a linear speed of 0.5 m / min to 5 m / min under the action of a steel-steel composite roller group, with the composite pressure controlled between 1.0 MPa and 4.0 MPa, and the composite roller temperature controlled between 40°C and 80°C; through the aforementioned low-temperature preheating and steel-steel roller composite, the polymer film is uniformly melted and impregnated at a lower temperature, enhancing the interfacial bonding force with the aluminum sheet, while avoiding overheating and deformation of the plastic substrate; the thickness uniformity of the composite aluminum-plastic board is monitored by an online thickness gauge, and the edge alignment between the aluminum sheet and the core board is controlled by an adjustment device to ensure that the composite interface is free of bubbles, wrinkles, and misalignment; Cooling and forming step: The composite board is cooled to set its shape; Inspection of the coating process: After the board has cooled and solidified, a quality inspection is carried out, and a protective film is applied to the surface. Trimming and cutting steps: Trim and cut the edges of the laminated board to a fixed length after inspection; Finished product unloading steps: Stack or package the trimmed and cut finished products to complete the unloading process.

2. The low-temperature production process for aluminum composite panels according to claim 1, characterized in that, In the plastic granule mixing step, the mixing time is 10-40 minutes and the mixing speed is 100-800 rpm.

3. The low-temperature production process for aluminum composite panels according to claim 1, characterized in that, In the particle extrusion step, the operating temperature of the extruder is 140℃-260℃.

4. The low-temperature production process for aluminum composite panels according to claim 1, characterized in that, The plasticizing step specifically includes: conveying the molten material extruded by the extruder to a plasticizing screw or dynamic mixing device, and further homogenizing it at a plasticizing temperature of 180°C to 240°C for 1 to 5 minutes. The shearing action of the screw ensures that the components in the material are fully mixed, the molecular chains are arranged more uniformly, internal stress of the melt is eliminated, and the melt flowability and film stability are improved.

5. The low-temperature production process for aluminum composite panels according to claim 1, characterized in that, The tableting step specifically includes: conveying the plasticized molten material through the extruder head to at least a pair of relatively rotating pressure rollers. The gap between the pressure rollers is set to 1mm to 10mm according to the thickness of the target plastic substrate. The temperature of the pressure rollers is controlled within the range of 30℃ to 80℃. By adjusting the speed of the pressure rollers to match the extrusion speed, the material is pressed between the pressure rollers to form a continuous plastic substrate with uniform thickness and smooth surface. At the same time, the calendering action of the pressure rollers eliminates the micropores inside the material, improving the density and flatness of the substrate.

6. The low-temperature production process for aluminum composite panels according to claim 1, characterized in that, The tableting step specifically includes the following process control steps: (1) Configuration of pressure roller group: A three-roll or four-roll calender is used as the pressing mechanism. The surface of the pressure roller is chrome-plated or mirror-polished, with a surface roughness Ra≤0.2μm. The diameter of the pressure roller ranges from 300mm to 600mm. (2) Gap adjustment: Based on the thickness of the target plastic substrate, the gap between the first pair of pressure rollers is preset to 1.0 mm to 10.0 mm by hydraulic or electric gap adjustment device, and the gap between subsequent pressure rollers is gradually reduced by 0.1 mm to 0.5 mm to achieve progressive thinning and reduce internal stress concentration; (3) Temperature zone control: Each pressure roller is equipped with an independent circulating temperature control system. The temperature zones of the pressure rollers are set along the material flow direction as follows: 30℃ to 50℃ in the inlet section, 50℃ to 70℃ in the middle section, and 40℃ to 60℃ in the outlet section, so that the material undergoes a temperature gradient change of "preheating-calendering-shaping" during the pressing process. (4) Speed ​​synchronization control: Each pressure roller is driven to operate independently by a servo motor. The PLC control system monitors the extruder outlet linear speed and the linear speed of each pressure roller in real time to ensure that the speed deviation is ≤0.5% and avoid material accumulation or stretching due to speed mismatch. (5) Pressure adjustment: Pressure sensors are installed at both ends of the pressure roller to monitor the linear pressure between the roller gaps in real time. The linear pressure is stabilized in the range of 20N / mm to 80N / mm through a closed-loop control system to ensure that the transverse thickness difference of the plate is ≤0.05mm. (6) Online thickness monitoring: An online thickness gauge is installed at the tableting outlet to continuously monitor the thickness of the plastic substrate. When the thickness deviation exceeds the set threshold, the pressure roller gap or extrusion amount is automatically adjusted. (7) Surface treatment: During the pressing process, release coating or a small amount of release agent is sprayed on the surface of the pressing roller to prevent molten material from adhering to the roller surface and ensure the smoothness of the substrate surface; (8) Stress relief: After the plastic substrate is pressed, it is introduced into the buffer bracket by the guide roller and naturally relaxed for 30 to 120 seconds in a tension-free state to eliminate the residual stress generated during the rolling process and prevent the substrate from shrinking and deforming.

7. The low-temperature production process for aluminum composite panels according to claim 1, characterized in that, In the low-temperature aluminum sheet composite step, the dual ovens set up before and after the aluminum sheet include a first oven and a second oven. The preheating temperature of the first oven is 50°C to 70°C, and the preheating temperature of the second oven is 70°C to 100°C, so that the aluminum sheet undergoes a gradient heating preheating process.

8. The low-temperature production process for aluminum composite panels according to claim 1, characterized in that, The steel-steel composite roller assembly consists of one or more pairs of steel pressure rollers with a roller surface hardness of HRC58-62 and a roller surface roughness Ra≤0.4μm. Hydraulic synchronization mechanisms are set at both ends of the composite roller assembly to ensure uniform distribution of composite pressure.

9. The low-temperature production process for aluminum composite panels according to claim 1, characterized in that, The cooling and molding step adopts air cooling or water cooling, and the cooling temperature is 5°C to 30°C.

10. The low-temperature production process for aluminum composite panels according to claim 1, characterized in that, In the inspection and coating step, the protective film is attached to the surface of the board by electrostatic adsorption or hot pressing; in the trimming and cutting step, the cutting size error is controlled within ±2mm; the finished product unloading step includes automatic stacking and wrapping of the finished products.

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