Method for continuous heat treatment and levelling of an ultra-thin sheet of aluminium matrix composite material

Abstract

This invention discloses a method for continuous heat treatment and leveling of ultrathin aluminum-based composite material sheets. The method includes hot-plate pressing, cold-plate pressing, leveling with a leveling machine, and stress-relief pitting. Specifically, the sheet is heat-treated using hot and cold plate pressing, with controlled holding pressure, temperature, and time. It is then transported by conveyor belt and immediately leveled using a high-precision CNC leveling machine. The flatness of the sheet is controlled by adjusting the roller spacing. Finally, pitting is applied to the surface of the sheet using a punch press to eliminate internal stress. This method solves the problem of warping and twisting of workpieces caused by internal material stress during processing. The resulting ultrathin sheet has a smooth shape, good flatness, and is free from wavy edges, twisting, wrinkles, and warping.

Description

Technical Field

[0001] This invention relates to a method for continuous heat treatment and leveling of ultrathin aluminum-based composite material sheets, belonging to the field of materials processing. Background Technology

[0002] Aluminum-based composite materials possess advantages such as low density, good dimensional stability, high specific strength and specific stiffness, and excellent wear resistance. In recent years, with the development of related research, the demand for large-size, ultra-thin aluminum-based composite products has been gradually increasing in various fields such as aerospace, automotive, optical devices, and electronic products. The expanding electronics market has led to a surge in the application of electronic components, placing demands on lightweight and mass-produced components. In the aerospace industry, while meeting performance specifications, there are also requirements for large-scale and lightweight aircraft.

[0003] However, the preparation of ultrathin aluminum-based composite sheets suffers from numerous problems, such as poor flatness and substandard mechanical properties, failing to meet application requirements. To meet performance specifications, ultrathin aluminum-based composite sheets often require heat treatment to improve performance. Traditional heat treatment involves heating the sheet at high temperatures and holding it at a constant temperature for a certain period, followed by rapid cooling (quenching) to obtain a supersaturated solid solution. Common cooling methods include water cooling, oil cooling, and air cooling, with different cooling rates for different media. Different cooling methods can be adopted according to performance requirements and actual needs. However, due to excessively rapid cooling rates and uneven cooling rates on the material surface, conventional water-quenching of ultrathin sheets is difficult, inevitably causing significant internal stress within the sheet. This leads to severe deformation of the sheet, especially ultrathin sheets, during heat treatment, resulting in problems such as wavy edges, twisting, wrinkles, and warping. The sheet exhibits significant twisting deformation, resulting in uneven sheet shape and an inability to guarantee the flatness of the ultrathin sheet. In addition, traditional heat treatment is affected by fluctuations in other factors such as holding temperature, holding time, transfer time, and cooling medium temperature, resulting in unstable heat treatment effects that cannot consistently meet product specifications and greatly affect the stability of product use.

[0004] A common method for leveling ultra-thin aluminum-based composite sheets is using a leveling machine. The heat-treated sheet is placed on the leveling machine, and the machine's pressure is used to repeatedly flatten the surface until the desired flatness and precision are achieved. However, this method is unsuitable for leveling large-sized ultra-thin sheets, and improper process control can lead to waviness, distortion, wrinkles, and even cracking, resulting in poor leveling performance and insufficient stability and reliability in practical applications. Therefore, traditional material processing techniques struggle to meet the shape and flatness requirements of various sheet products.

[0005] Currently, there are few reports on continuous heat treatment and leveling processes for ultra-thin aluminum-based composite sheets. Therefore, the shape control of ultra-thin sheets has attracted widespread attention, and there is an urgent need to design a suitable method for continuous heat treatment and leveling of large-size ultra-thin aluminum-based composite sheets to improve the mechanical properties of the material while controlling the material shape, ensuring good flatness, and reducing defects such as wavy edges, twisting, wrinkles, and warping to meet application requirements. Summary of the Invention

[0006] The purpose of this invention is to provide a method for continuous heat treatment and leveling of large-size ultra-thin aluminum-based composite material sheets, so as to solve the problem of warping and twisting of workpieces caused by internal stress of the material during processing and forming, and to ensure the flatness of the sheet while improving the strength of the material.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A method for continuous heat treatment and leveling of ultrathin aluminum-based composite material sheets includes the following steps:

[0009] (1) The heating plate with an upper and lower opening structure is used to press the plate with hot plate pressure. The heating plate has an upper pressure plate and a lower pressure plate. The heating plate is set to a temperature of 500-550℃. After the plate is transported to the lower pressure plate, it is held for 5 seconds. Then the upper pressure plate presses down to close the plate. The pressure is 15-25MPa and the pressure holding time is 10-15min. After the pressure holding is completed, the upper pressure plate is lifted.

[0010] (2) The plate is subjected to cold plate pressing using a cooling plate with an upper and lower opening structure. The cooling plate has an upper plate and a lower plate. The temperature of the cooling plate is set at 20-30℃. After the plate is transported to the lower plate, it is held for 1-2 seconds. Then the upper plate presses down to close the plate. The pressure is 15-25MPa and the holding time is 30-60 seconds. After the holding time is completed, the upper plate is lifted. The combination of hot plate pressing and cold plate pressing is a continuous heat treatment process.

[0011] (3) The heat-treated plate is leveled. The gap between the infeed rollers of the leveling machine is set to -0.4 to -0.8 mm, the gap between the outfeed rollers is set to 0 to 0.3 mm, and the linear speed is set to 2-6 m / min.

[0012] (4) The sheet metal is transported to the punch press by conveyor belt and the internal stress is eliminated by punching. The holding pressure of the punch press is 5-15MPa, the holding temperature is 180-220℃, and the holding time is 30-60s.

[0013] Furthermore, the dimensions of the plate are length × width × thickness = (0.5-1.5)m × (0.5-1.5)m × (0.1-0.5)mm.

[0014] Furthermore, in step (1), the upper and lower pressure plates are heated by multiple parallel heating rods, and thermocouples are used to monitor the temperature of the pressure plate surface.

[0015] Furthermore, in step (2), the upper and lower pressure plates are respectively arranged with S-shaped cooling pipes, and cooling circulating water is circulated inside. Thermocouples are used to monitor the temperature of the pressure plate surface.

[0016] Furthermore, in steps (1) and (2), the external dimensions of the upper pressure plate and the lower pressure plate are length × width = 2m × 2m.

[0017] Furthermore, in steps (1) and (2), a 2m wide metal mesh conveyor belt is used to transport the sheet material at a mesh belt speed of 5-10m / min.

[0018] Furthermore, in steps (1) and (2), the stroke of the heating plate and the cooling plate, that is, the distance that the upper plate is fed from the top to the point where it is in contact with the lower plate, is 20mm, and the lifting and lowering of the upper and lower plates are controlled by a hydraulic column.

[0019] Furthermore, in step (4), the punch press has a stripper plate with continuous upper pitting and a lower die plate with continuous lower pitting. The upper and lower pitting are staggered to ensure that the surface of the sheet material between the stripper plate and the lower die plate is subjected to uniform force.

[0020] The advantages of this invention are:

[0021] The method of this invention employs a continuous heat treatment process consisting of hot plate pressing and cold plate pressing. By controlling the holding pressure, holding temperature, and holding time, the sheet metal is heat-treated, then transported by conveyor belt, and immediately leveled by a high-precision CNC leveling machine. The flatness of the sheet metal is controlled by adjusting the roller spacing. Finally, stress relief and pitting are applied, which solves the problem of workpiece warping and twisting caused by internal stress in the material during processing and forming.

[0022] Compared with traditional methods, the method of this invention can perform continuous heat treatment and leveling on large-size ultra-thin aluminum-based composite materials, avoiding the use of direct water-cooling quenching. The method results in less torsion and deformation of the sheet material, reducing defects such as wavy edges, twisting, wrinkles, and warping, while ensuring mechanical properties. In addition, the entire processing flow is simple in principle, easy to operate, and the process parameters are simple and controllable. Related equipment can be easily designed and modified according to actual needs, with a high degree of automation, high yield, and the ability to process continuously in batches, achieving large-scale production. Attached Figure Description

[0023] Figure 1 This is a flowchart illustrating the continuous heat treatment and leveling process of the ultrathin aluminum-based composite material sheet of the present invention.

[0024] Figure 2 This is a schematic diagram of hot plate pressure.

[0025] Figure 3 This is a schematic diagram showing the arrangement of heating rods inside the upper and lower pressure plates of the heating plate.

[0026] Figure 4 This is a schematic diagram of a cold-rolled steel plate under heavy pressure.

[0027] Figure 5 This is a schematic diagram showing the arrangement of cooling pipes inside the upper and lower pressure plates of the cooling plate.

[0028] Figure 6 A schematic diagram of leveling using a high-precision CNC leveling machine.

[0029] Figure 7 A schematic diagram of stress-relieving pitting. Detailed Implementation

[0030] To more clearly describe the technical solution of the present invention, the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0031] The aluminum-based composite material described in this invention is a particle-reinforced aluminum-based composite material, wherein the volume fraction of ceramic particles is 15-30%, and the ceramic particles are one or more of SiC, B4C, Al2O3, etc.; the aluminum matrix is ​​a 6xxx series aluminum alloy, a 7xxx series aluminum alloy, a 2xxx series aluminum alloy, or a 5xxx series aluminum alloy.

[0032] The method of this invention employs hot plate pressing and cold plate pressing. The plate is heat-treated by controlling the holding pressure, holding temperature and holding time. Then, it is transported by conveyor belt and leveled immediately by a high-precision CNC leveling machine. The flatness of the plate is controlled by adjusting the roller spacing. Finally, stress is relieved by pitting.

[0033] like Figure 1 The diagram shown is a process flow chart for continuous heat treatment and leveling of ultrathin aluminum-based composite material sheets according to the present invention, which shows the structural schematic diagram of the equipment used in each step.

[0034] Combination Figures 1-3 As shown, the heating plate used in the hot plate pressing step has an upper pressure plate 1, a lower pressure plate 2, and a hydraulic column 3 that controls the lifting and lowering of the upper pressure plate 1. The ultra-thin sheet 4 is conveyed to the lower pressure plate 2. Multiple heating rods 5 are arranged in parallel inside the upper pressure plate 1 and the lower pressure plate 2, respectively.

[0035] Combination Figure 1 , 4As shown in Figure 5, the structure of the cooling plate used in the cold plate pressing step is the same as that of the heating plate, except for the arrangement of the cooling pipes inside the upper and lower pressure plates. The cooling plate has an upper pressure plate 11, a lower pressure plate 12, and a hydraulic column 13 for controlling the lifting and lowering of the upper pressure plate 11. The ultra-thin sheet 4 is conveyed to the lower pressure plate 12. S-shaped cooling pipes 15 are respectively arranged inside the upper pressure plate 11 and the lower pressure plate 12.

[0036] Combination Figure 1 , 6 As shown, in the leveling step using a high-precision CNC leveling machine, the upper and lower rollers 6 and 7 are arranged in sequence. The ultra-thin sheet material enters from the inlet roller, is conveyed between the two rollers for leveling, and flows into the next process from the outlet roller.

[0037] Combination Figure 1 , 7 As shown, the punch press used in the stress-relief pitting step has a stripper plate 17 with continuous upper pitting 16 and a lower template 19 with continuous lower pitting 18. The upper pitting 16 and lower pitting 18 are staggered to make the surface of the sheet material between the stripper plate and the lower template uniformly stressed.

[0038] The method used in the following embodiments specifically includes the following steps:

[0039] (1) A 2m wide metal mesh conveyor belt is used to transport the sheet material (length × width × thickness = (0.5-1.5)m × (0.5-1.5)m × (0.1-0.5)mm) to the heating plate at a belt speed of 5-10m / min. The heating plate has an upper and lower opening structure with a stroke of 20mm. The lifting and lowering of the pressure plate is controlled by a hydraulic column. Multiple parallel heating rods are used inside the upper and lower pressure plates for heating. Thermocouples are used to monitor the temperature of the pressure plate surface. The external dimensions of the upper and lower pressure plates are 2m × 2m (length × width). The heating plate is pre-set to a temperature of 500-550℃. After the sheet material is transported to the lower pressure plate, it is held for 5 seconds. Then, the upper pressure plate presses down to close the sheet material, with a pressure of 15-25MPa and a holding time of 10-15min. After the pressure holding is completed, the upper pressure plate is lifted.

[0040] (2) A 2m wide metal mesh conveyor belt is used to transport the sheet material to the cooling plate. The cooling plate has the same dimensions, stroke, and control method as the heating plate. The upper and lower pressure plates of the cooling plate are equipped with S-shaped cooling pipes with circulating cooling water. Thermocouples are used to monitor the surface temperature of the pressure plate. The pressure plate has an external dimension of 2m × 2m. After the sheet material is transported to the lower pressure plate, it is held for 1-2 seconds. Then, the upper pressure plate presses down to hold the sheet material, with a pressure of 15-25MPa and a holding time of 30-60 seconds. After the pressure holding is completed, the upper pressure plate is lifted.

[0041] (3) A high-precision CNC leveling machine is used to level the heat-treated sheet metal. Depending on the thickness of the sheet metal, the setting values ​​of the infeed roller spacing, the outlet roller spacing, and the linear speed have a certain impact on the leveling of the sheet metal: if the infeed roller spacing is too low, the sheet metal to be leveled cannot be leveled by the infeed roller; if the infeed roller spacing is too high, the sheet metal cannot be effectively leveled, and the leveling effect is poor; if the outlet roller spacing is too low, the sheet metal passing through two layers of rollers will warp, curl, etc., and may even damage the surface of the sheet metal; if the outlet roller spacing is too high, the sheet metal cannot be effectively leveled, and the leveling effect is poor; if the linear speed is too low, it will affect the overall processing efficiency of the sheet metal and may cause wrinkles in the sheet metal; if the linear speed is too high, the stress in the sheet metal cannot be fully released, and the leveling effect is poor. Taking this invention as an example, the MHT12 series high-precision CNC leveling machine of Guangdong Dayongsheng Technology Co., Ltd. is used to level the sheet metal. Since the thickness of the sheet material is 0.1 to 0.5 mm, the gap between the infeed rollers needs to be set to -0.4 to -0.8 mm in advance, the gap between the outfeed rollers needs to be set to 0 to 0.3 mm, and the linear speed needs to be set to 2-6 m / min. Then, the ultra-thin sheet material is fed into the rollers by a conveyor belt to level it, so as to obtain an ultra-thin sheet material with a flat surface, no wavy edges, twists, or wrinkles.

[0042] (4) The sheet metal is transported to a punch press via a conveyor belt to remove internal stress by creating pits. The punch press holds pressure at 5-15 MPa, holds temperature at 180-220℃, and holds pressure for 30-60 seconds. The upper pits on the stripper plate and the lower pits on the lower die plate are staggered, ensuring uniform stress distribution on the workpiece surface. This effectively limits deformation caused by stress release, eliminates internal stress in the sheet metal, controls its flatness, and ensures a smooth surface without warping.

[0043] In step (1), the conveyor belt speed, heating plate temperature, plate holding time, holding pressure, and holding time are adjustable. In step (2), the conveyor belt speed, plate holding time, holding pressure, and holding time are adjustable. In step (3), the feed roller spacing, feed roller distance, and linear speed are adjustable. In step (4), the holding pressure, holding temperature, and holding time are adjustable.

[0044] Example 1

[0045] In this embodiment, the aluminum-based composite material is reinforced with SiC ceramic particles, the volume fraction of SiC is 15%, the aluminum matrix is ​​6xxx series aluminum alloy, and the plate thickness is 0.2mm.

[0046] 1. Hot Plate Pressing: Set the heating plate temperature to 550℃, the holding pressure to 15MPa, the holding time to 10min, and the conveyor belt speed to 6m / min. Transport a 1m×1m×0.20mm sheet onto the lower pressure plate of the heating plate and hold it for 5s. Then, press down the upper pressure plate to hold the sheet in place. After the pressure holding is complete, lift the upper pressure plate.

[0047] 2. Cold Plate Pressing: The conveyor belt speed is set to 10m / min, the pressure setting is 15MPa, and the pressure holding time is set to 30s. The plate is transported to the lower pressure plate of the cold plate and held for 1s. The upper pressure plate then presses down to hold the plate in place. After the pressure holding is completed, the upper pressure plate is lifted.

[0048] 3. Leveling with a leveling machine: The MHT12 series high-precision CNC leveling machine is used to level the sheet metal. The gap between the infeed rollers is set to -0.8mm, the gap between the outfeed rollers is set to 0mm, and the linear speed is set to 2m / min. The heat-treated sheet metal is fed into the leveling machine for leveling using a conveyor belt.

[0049] 4. Stress Relief and Pinning: Set the press pressure to 5MPa, the holding temperature to 180℃, and the holding time to 30s. Transport the leveled sheet metal to the press using a conveyor belt to perform pinning to eliminate internal stress.

[0050] The obtained sheet material has a flat surface, free from wavy edges, twisting, wrinkles, and warping, with an edge flatness ≤0.3mm as measured by feeler gauge. Tensile strength, yield strength, and elongation were tested using a WDW-100 electronic universal testing machine, following the test method GB / T228.1-2010. Samples were prepared according to the test method, and tensile specimens were tested using a universal testing machine to assess their mechanical properties. The test results were: tensile strength 470MPa, yield strength 380MPa, and elongation 5%.

[0051] Example 2

[0052] In this embodiment, the aluminum-based composite material is reinforced with SiC ceramic particles, the volume fraction of SiC is 20%, the aluminum matrix is ​​a 2xxx series aluminum alloy, and the plate thickness is 0.3 mm.

[0053] 1. Hot Plate Pressing: Set the heating plate temperature to 530℃, the holding pressure to 20MPa, the holding time to 10min, and the conveyor belt speed to 6m / min. Transport a 0.5m×0.5m×0.30mm sheet onto the lower pressure plate of the heating plate, hold it for 5s, and then press down the upper pressure plate to hold the sheet. After the pressure holding is completed, lift the upper pressure plate.

[0054] 2. Cold Plate Pressing: The conveyor belt speed is set to 8m / min, the pressure is set to 20MPa, and the holding time is set to 45s. The plate is transported to the lower pressure plate of the cold plate and held for 1s. The upper pressure plate then presses down to hold the plate in place. After the pressure holding is completed, the upper pressure plate is lifted.

[0055] 3. Leveling with a leveling machine: The MHT12 series high-precision CNC leveling machine is used to level the sheet metal. The infeed roller spacing of the high-precision CNC leveling machine is set to -0.6mm, the outlet roller spacing is set to 0.2mm, and the linear speed is set to 4m / min. The heat-treated sheet metal is fed into the leveling machine for leveling using a conveyor belt.

[0056] 4. Stress Relief and Pinning: Set the press pressure to 10MPa, the press temperature to 200℃, and the press time to 45s. Transport the leveled sheet metal to the press using a conveyor belt to perform pinning to eliminate internal stress.

[0057] The obtained sheet material has a flat surface, free from wavy edges, twisting, wrinkles, and warping, with an edge flatness ≤0.2mm as measured by feeler gauge. Tensile strength, yield strength, and elongation were tested using a WDW-100 electronic universal testing machine, following the test method GB / T228.1-2010. Samples were prepared according to the test method, and tensile specimens were tested using a universal testing machine for mechanical properties. The test results were: tensile strength 480MPa, yield strength 400MPa, and elongation 5%.

[0058] Example 3

[0059] In this embodiment, the aluminum-based composite material is reinforced with SiC and B4C ceramic particles, with a total volume fraction of 25% for SiC and B4C. The aluminum matrix is ​​a 6xxx series aluminum alloy, and the plate thickness is 0.4 mm.

[0060] 1. Hot Plate Pressing: Set the heating plate temperature to 500℃, the holding pressure to 25MPa, the holding time to 15min, and the conveyor belt speed to 6m / min. Transport a sheet material with dimensions of 1.5m×1.5m×0.40mm onto the lower pressure plate of the heating plate, hold it for 5s, and then press down the upper pressure plate to hold the sheet material. After the pressure holding is completed, lift the upper pressure plate.

[0061] 2. Cold Plate Pressing: The conveyor belt speed is set to 6 m / min, the pressure is set to 25 MPa, and the holding time is set to 60 s. The plate is transported to the lower pressure plate of the cold plate and held for 1 s. The upper pressure plate then presses down to hold the plate in place. After the pressure holding is completed, the upper pressure plate is lifted.

[0062] 3. Leveling with a leveling machine: The MHT12 series high-precision CNC leveling machine is used to level the sheet metal. The infeed roller spacing of the high-precision CNC leveling machine is set to -0.4mm, the outlet roller spacing is set to 0.3mm, and the linear speed is set to 6m / min. The heat-treated sheet metal is fed into the leveling machine for leveling using a conveyor belt.

[0063] 4. Stress Relief and Pinning: Set the press pressure to 15MPa, the press temperature to 220℃, and the press time to 60s. Transport the leveled sheet metal to the press using a conveyor belt to perform pinning to eliminate internal stress.

[0064] The obtained sheet material has a flat surface, free from wavy edges, twisting, wrinkles, and warping; the edge flatness, as measured by a feeler gauge, is ≤0.3mm. Tensile strength, yield strength, and elongation were tested using a WDW-100 electronic universal testing machine, following the test method GB / T228.1-2010. Samples were prepared according to the test method, and tensile specimens were tested using a universal testing machine to assess their mechanical properties. The test results were: tensile strength 500MPa, yield strength 400MPa, and elongation 6%.

Claims

1. A method for continuous heat treatment and leveling of ultrathin aluminum-based composite material sheets, characterized in that, The aluminum-based composite material is a particle-reinforced aluminum-based composite material; the dimensions of the plate are length × width × thickness = (0.5-1.5) m × (0.5-1.5) m × (0.1-0.5) mm, and the method includes the following steps: (1) The heating plate with an upper and lower opening structure is used to press the plate with hot plate pressure. The heating plate has an upper pressure plate and a lower pressure plate. The heating plate is set to a temperature of 500-550℃. After the plate is transported to the lower pressure plate, it is held for 5 seconds. Then the upper pressure plate presses down to close the plate. The pressure is 15-25MPa and the holding time is 10-15min. After the holding time is completed, the upper pressure plate is lifted. (2) The cooling plate with an upper and lower opening and closing structure is used to apply cold plate pressure. The cooling plate has an upper pressure plate and a lower pressure plate. The temperature of the cooling plate is set to 20-30℃. After the plate is transported to the lower pressure plate, it is held for 1-2 seconds. Then the upper pressure plate presses down to close the plate. The pressure is 15-25MPa and the holding time is 30-60 seconds. After the holding time is completed, the upper pressure plate is lifted. (3) Perform a leveling operation on the heat-treated plate, set the gap between the infeed rollers of the leveling machine to -0.4~-0.8mm, the gap between the outfeed rollers to 0~0.3mm, and the linear speed to 2-6m / min; (4) The sheet metal is transported to the punch press by conveyor belt and the internal stress is eliminated by punching. The holding pressure of the punch press is 5-15 MPa, the holding temperature is 180-220℃, and the holding time is 30-60s.

2. The method for continuous heat treatment and leveling of ultrathin aluminum-based composite material sheets according to claim 1, characterized in that, In step (1), the upper and lower pressure plates are heated by multiple parallel heating rods, and thermocouples are used to monitor the temperature of the pressure plate surface.

3. The method for continuous heat treatment and leveling of ultrathin aluminum-based composite material sheets according to claim 1, characterized in that, In step (2), S-shaped cooling pipes are arranged inside the upper and lower pressure plates, and cooling circulating water is circulated inside. Thermocouples are used to monitor the temperature of the pressure plate surface.

4. The method for continuous heat treatment and leveling of ultrathin aluminum-based composite material sheets according to claim 1, characterized in that, In steps (1) and (2), the external dimensions of the upper pressure plate and the lower pressure plate are length × width = 2m × 2m.

5. The method for continuous heat treatment and leveling of ultra-thin aluminum-based composite material sheets according to claim 1, characterized in that, In steps (1) and (2), a 2m wide metal mesh conveyor belt is used to transport the sheet material at a mesh belt speed of 5-10m / min.

6. The method for continuous heat treatment and leveling of ultrathin aluminum-based composite material sheets according to claim 1, characterized in that, In steps (1) and (2), the stroke of the heating plate and the cooling plate is 20 mm, and the lifting and lowering of the upper and lower pressure plates are controlled by the hydraulic column.

7. The method for continuous heat treatment and leveling of ultrathin aluminum-based composite material sheets according to claim 1, characterized in that, In step (4), the punch press has a stripper plate with continuous upper pits and a lower die plate with continuous lower pits. The upper and lower pits are staggered, so that the surface of the sheet material between the stripper plate and the lower die plate is subjected to uniform force.

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