Method for eliminating bar rising phenomenon during annealing of double-zero aluminum foil coil

Abstract

The method comprises the steps of slitting, material preparation, winding, annealing, packaging and warehousing, single-zero aluminum foil is wound on the outer ring of the double-zero aluminum foil, the single-zero aluminum foil on the outer ring after winding can limit deformation of the internal double-zero aluminum foil during annealing, and the problem of annealing and lifting of the double-zero aluminum foil is solved. And after annealing is completed, the single-zero aluminum foil on the outer ring is made into a single-zero aluminum foil finished product, the double-zero aluminum foil on the inner ring is made into a double-zero aluminum foil finished product, products of two specifications are produced at the same time through the same annealing procedure, and the productivity is improved while the production cost is reduced. In addition, the method replaces the traditional mode that a large amount of time is allocated for removing rolling oil in the temperature rising section of the double-zero aluminum foil, the temperature rising time of the double-zero aluminum foil is shortened after the single-zero aluminum foil is wound, the production efficiency and the product percent of pass are improved, the waste loss of the aluminum foil in the annealing process is reduced, and the purposes of reducing cost and improving efficiency are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of aluminum foil production, and in particular to a method for eliminating the phenomenon of barring during annealing of a double-zero aluminum foil coil. Background Art

[0002] Double zero aluminum foil generally refers to aluminum foil with a thickness of less than 0.01m. Because of its light-shielding, fresh-keeping, and anti-corrosion properties, it is widely used as a lining material in the cigarette, food, medicine, electronics and other industries. When used, it is compounded with other packaging substrates to enhance the strength of the packaging material. In the process of compounding aluminum foil with other packaging substrates, once the aluminum foil cannot be compounded with the substrate smoothly, the compound quality will not meet the quality requirements of the packaging material, resulting in a large amount of raw materials being scrapped, especially the composite substrate, whose loss is several times that of the aluminum foil of the same length. Therefore, after the rolled aluminum foil is cut according to customer needs, it needs to be annealed from the processed state to the soft state to reduce its brittleness and make it less prone to rupture. At the same time, the rolling oil on the surface of the aluminum foil can be evaporated cleanly, making it easy to compound and print. However, due to the complex composition of the rolling oil, the gap between the layers of the aluminum foil produced in roll form is very small, and the annealing process is the last step in the production of soft double zero foil. Once an error occurs, the loss is huge.

[0003] The annealing of aluminum foil is divided into three stages: heating, heat preservation and cooling. During the annealing process, the heating rate is the key to controlling the quality. The setting of the heating rate needs to comprehensively consider the heating characteristics of the aluminum foil roll, the heating capacity of the equipment, energy consumption and duration. During the heating process of the aluminum foil, there is always a certain temperature difference between the surface aluminum foil and the inner aluminum foil. Once the thermal expansion of the surface of the aluminum foil exceeds a certain degree, irreversible surface deformation will occur, causing the surface of the aluminum foil to rise (also called hot drum). Specifically, the outer ring of the aluminum foil roll is heated more and expands faster, with an expansion of δ1, while the inner aluminum foil is heated less and expands slower, with an expansion of δ2. The thermal expansion coefficient of aluminum is K=23×10 -6 / ℃; thermal expansion of aluminum metal δ (dimensional change) = thermal expansion coefficient of aluminum K × length × temperature change; metal has an elastic limit σe. If the deformation of the metal is less than σe, elastic deformation occurs and it can be recovered. If the deformation is greater than σe, plastic deformation occurs and it cannot be recovered. If δ1-δ2+internal stress ≤σe, part of the thermal expansion of the surface aluminum foil will be offset by elastic deformation and no deformation will occur; if δ1-δ2+internal stress>σe, the thermal expansion of the surface of the aluminum foil exceeds a certain degree, and the surface of the aluminum foil will be barred. Under the same heating rate, the thinner the thickness of the aluminum foil, the more likely the aluminum foil roll will have a temperature difference between the outer and inner rings, and the more likely it is that δ1-δ2+internal stress>σe, and the more likely it is that the surface will be barred. As the heating rate of the aluminum foil roll increases, the temperature difference between the outer and inner rings of the aluminum foil roll will increase, so the double-zero aluminum foil roll is more likely to have barring during the annealing process than the single-zero aluminum foil roll.

[0004] When the aluminum foil coil is heated in the furnace atmosphere, it can only absorb heat through the outer ring surface and two end faces. Although the heat transfer area of ​​the outer ring surface of the aluminum foil coil is large, the gap between the aluminum foil layers is small and the rolling oil is blocked, resulting in insufficient heat transfer depth. Therefore, under the same coil diameter, the thinner the aluminum foil, the more layers it has. For aluminum foil with a thickness of less than 0.009mm, the heat can only reach 10-15mm on the surface. Although the heat transfer area of ​​the end face of the aluminum foil coil is small, the heat transfer depth is large because the heat conduction is carried out along the inside of the aluminum foil metal matrix. Therefore, in order to control the bar-raising phenomenon during the annealing of double-zero aluminum foil, a large amount of time needs to be allocated to the heating section to ensure that the double-zero aluminum foil coil is heated slowly and the rolling oil is removed. The rolling oil can only evaporate from the end surface of the aluminum foil coil, so the wider the aluminum foil coil, the longer the oil removal time. In addition, the precision of the annealing furnace equipment and the changes in ambient temperature during the day and night, winter and summer will affect the heating process, so simply extending the heating time cannot completely eliminate the bar-raising phenomenon during annealing.

[0005] Conventional double-zero aluminum foil heating methods are divided into the following two types: (1) Two-stage step heating: For aluminum foil with a width of ≥1000mm, the temperature is first raised to 100℃ at a rate of 1-6℃ / h during annealing, and then kept at this temperature for 0-5h, and then raised to the highest temperature at a rate of 1-10℃ / h for heat preservation annealing. The whole heating process usually takes between 25-150h, and the wider the width of the aluminum foil roll and the longer the number of meters, the longer the heating time; (2) Multi-stage step heating: For aluminum foil with a width of ≥1000mm, the temperature is first raised to 100℃ at a rate of 1-6℃ / h, and ... kept at this temperature for 0-5h. For aluminum foil with a thickness of 1 mm, when annealing, first heat it up to 60℃ at a rate of 1-6℃ / h and keep it warm for 0-3h; then heat it up to 100℃ at a rate of 1-8℃ and keep it warm for 0-3h; then heat it up to 150℃ at a rate of 1-10℃ and keep it warm for 0-5h; finally heat it up to the highest temperature at a rate of 1-12℃ / h for heat preservation annealing. The whole heating process is generally between 20-130h, and the wider the width of the aluminum foil roll and the longer the number of meters, the longer the heating time. It can be seen that the heating process of double-zero aluminum foil seriously affects the production efficiency of the product and wastes a lot of resources. The wider the width and the longer the number of meters of the product, the more serious the waste.

[0006] There are currently two ways to prevent double-zero aluminum foil from barring: (1) Wrapping kraft paper around the outside of the aluminum foil roll. This method requires that the kraft paper is thick enough to block surface heat absorption. The kraft paper is fixed to the outer surface of the aluminum foil roll by wrapping the aluminum foil, so there is a lot of waste after annealing, and it cannot completely solve the problem of double-zero aluminum foil barring during annealing; (2) Reducing annealing barring by extending the standing time of the aluminum foil outside the furnace, mainly by standing at room temperature to allow the aluminum foil roll to release some internal stress. In this way, during the annealing process, it is more difficult for δ1-δ2+internal stress>σe to occur. Although this method can reduce barring, it cannot completely solve the problem of double-zero aluminum foil barring during annealing. Summary of the invention

[0007] The invention provides a method for eliminating the annealing bar phenomenon of a double-zero aluminum foil coil, wherein the annealing bar phenomenon is eliminated by welding a single-zero aluminum foil to the outer ring of the double-zero aluminum foil, thereby saving annealing heating time and improving production efficiency and yield rate.

[0008] To achieve its purpose, the present invention adopts the following technical solutions: A method for eliminating the phenomenon of double-zero aluminum foil coil annealing and barring, comprising the following steps: (1) Slitting: Slitting the rolled double-zero aluminum foil into double-zero aluminum foil rolls as needed, and the material will not be unloaded after slitting is completed; (2) preparing materials; selecting a single zero aluminum foil with the same alloy and width as the double zero aluminum foil roll in step (1), and welding the single zero aluminum foil and the double zero aluminum foil roll together; (3) Winding; cutting the single zero aluminum foil in step (2) and winding it around the outer ring of the double zero aluminum foil roll in step (1), and unloading the material after cutting to obtain an aluminum foil roll; (4) Annealing; the aluminum foil coil of step (3) is placed in an annealing furnace, heated to 180-230°C for 1-10 hours, and then kept warm for 30-60 hours for annealing, and then the temperature is reduced to 180-190°C and kept warm until the rolling oil is completely removed; after the annealing is completed, the coil is taken out of the furnace and cooled, and the single zero aluminum foil wrapped around the outer ring of the aluminum foil coil is wound around another tube core by re-unwinding and rewinding, thereby obtaining a double zero aluminum foil coil and a single zero aluminum foil coil respectively; (5) Packaging: After the double zero aluminum foil rolls and single zero aluminum foil rolls obtained in step (4) are tested and found to be qualified and have no abnormal appearance, they are packaged and put into storage respectively.

[0009] Furthermore, the thickness of the double-zero aluminum foil rolled in step (1) is 0.0053-0.0099 mm.

[0010] Furthermore, a slitting machine is used in both steps (1) and (3).

[0011] Furthermore, in step (2), the thickness of the single zero aluminum foil is 0.02-0.05 mm.

[0012] Furthermore, ultrasonic welding is used when welding the single zero aluminum foil and the double zero aluminum foil rolls in step (2).

[0013] Furthermore, in step (3), the number of meters of single zero aluminum foil winding is greater than 500m.

[0014] The beneficial effects of the present invention are as follows: This method wraps the single-zero aluminum foil around the outer ring of the double-zero aluminum foil. Since the single-zero aluminum foil does not have a high requirement for the heating speed as the double-zero aluminum foil, the single-zero aluminum foil on the outer ring after winding will limit the deformation of the inner double-zero aluminum foil during annealing, eliminating the annealing problem of the double-zero aluminum foil. After the annealing is completed, the single-zero aluminum foil on the outer ring is made into a single-zero aluminum foil finished product, and the double-zero aluminum foil on the inner ring is made into a double-zero aluminum foil finished product by re-unwinding and rewinding. Two specifications of products are produced simultaneously through the same annealing process, reducing production costs while increasing production capacity. Moreover, this method replaces the traditional method of allocating a large amount of time to remove the rolling oil in the heating section of the double-zero aluminum foil. After winding the single-zero aluminum foil, the heating time of the double-zero aluminum foil is shortened, the production efficiency and product qualification rate are improved, and the waste loss of aluminum foil during the annealing process is reduced, achieving the purpose of reducing costs and increasing efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a physical picture of the finished product of the double zero aluminum foil roll in Example 1 of the present invention; Figure 2 This is a physical picture of the finished product of the single zero aluminum foil roll in Example 1 of the present invention. DETAILED DESCRIPTION

[0016] The present invention will be further described below in conjunction with embodiments: In the following embodiments of the present invention, the slitting machine is an Achenbach vertical slitting machine. When slitting double zero aluminum foil, the slitting parameters of the slitting machine are shown in Table 1. When slitting single zero aluminum foil, the slitting parameters of the slitting machine are shown in Table 2: Table 1 Double zero aluminum foil slitting parameters Table 2 Single zero aluminum foil slitting parameters Example 1 The present invention provides a method for eliminating the phenomenon of double-zero aluminum foil coil annealing, comprising the following steps: (1) Slitting: According to the slitting parameters shown in Table 3, the rolled 8079 alloy double zero aluminum foil with a thickness of 0.006 mm is cut into double zero aluminum foil coils with a length of 24200 m and a width of 1290 mm on a slitting machine. After the slitting is completed, the material is not unloaded; Table 3 Double zero aluminum foil slitting parameters (2) Material preparation: Select single zero aluminum foil of 8079 alloy with a thickness of 0.02 mm, a width of 1290 mm, and a length of 3600 m, and weld the single zero aluminum foil and double zero aluminum foil rolls together by ultrasonic welding; (3) Winding; slitting the single zero aluminum foil in step (2) and winding it around the outer ring of the double zero aluminum foil roll after slitting in step (1), and unloading after slitting according to the slitting parameters shown in Table 4 to obtain an aluminum foil roll; Table 4 Single zero aluminum foil slitting parameters (4) Annealing: The aluminum foil coil of step (3) is placed in an annealing furnace, heated to 220°C for 6 hours, and then kept warm for 40 hours for annealing, and then the temperature is reduced to 180°C and kept warm until the rolling oil is completely removed; after the annealing is completed, the coil is taken out of the furnace for cooling, and the single zero aluminum foil wrapped around the outer ring of the aluminum foil coil is wound around another tube core by rewinding and unwinding to obtain Figure 1 The specifications shown are 0.006mm×1290mm×24200m double zero aluminum foil roll and Figure 2 The specifications shown are single zero aluminum foil rolls of 0.02mm × 1290mm × 3600m.

[0017] Depend on Figure 1 It can be seen that the double-zero aluminum foil roll produced by the method of the present invention has a smooth surface without deformation, and the bar phenomenon is eliminated. The double-zero aluminum foil roll and the single-zero aluminum foil roll produced simultaneously by the same process both meet the use requirements and have a high yield rate.

[0018] Example 2 The present invention provides a method for eliminating the phenomenon of double-zero aluminum foil coil annealing, comprising the following steps: (1) Slitting: According to the slitting parameters shown in Table 5, the rolled 1235 alloy double zero aluminum foil with a thickness of 0.007 mm is cut into double zero aluminum foil rolls with a length of 12300 m and a width of 1100 mm on a slitting machine. After the slitting is completed, the material is not unloaded; Table 5 Double zero aluminum foil slitting parameters (2) Material preparation: Select single zero aluminum foil of 1235 alloy with a thickness of 0.032 mm, a width of 1100 mm, and a length of 3000 m, and weld the single zero aluminum foil and double zero aluminum foil rolls together by ultrasonic welding; (3) Winding; slitting the single zero aluminum foil in step (2) and winding it around the outer ring of the double zero aluminum foil roll after slitting in step (1), and unloading after slitting according to the slitting parameters shown in Table 6 to obtain an aluminum foil roll; Table 6 Single zero aluminum foil slitting parameters (4) Annealing; the aluminum foil coil of step (3) is placed in an annealing furnace, heated to 180°C for 5 hours, and then kept warm for 30 hours for annealing, and then the temperature is reduced to 190°C and kept warm until the rolling oil is completely removed; after annealing, the coil is taken out of the furnace and cooled, and the single zero aluminum foil wrapped around the outer ring of the aluminum foil coil is wound around another tube core by re-unwinding and rewinding, thereby obtaining a double zero aluminum foil coil with a specification of 0.007 mm × 1100 mm × 12300 m and a single zero aluminum foil coil with a specification of 0.032 mm × 1100 mm × 3000 m.

[0019] Example 3 The present invention provides a method for eliminating the phenomenon of double-zero aluminum foil coil annealing, comprising the following steps: (1) Slitting: According to the slitting parameters shown in Table 7, the rolled 8079 alloy double zero aluminum foil with a thickness of 0.0063 mm is slit on a slitting machine into double zero aluminum foil coils with a length of 60,000 m and a width of 1,572 mm. After slitting, the material is not unloaded; Table 7 Double zero aluminum foil slitting parameters (2) Material preparation: Select single zero aluminum foil of 8079 alloy with a thickness of 0.022 mm, a width of 1572 mm, and a length of 3000 m, and weld the single zero aluminum foil and double zero aluminum foil rolls together by ultrasonic welding; (3) Winding; slitting the single zero aluminum foil in step (2) and winding it around the outer ring of the double zero aluminum foil roll after slitting in step (1), and unloading after slitting according to the slitting parameters shown in Table 8 to obtain an aluminum foil roll; Table 8 Single zero aluminum foil slitting parameters (4) Annealing; the aluminum foil coil of step (3) is placed in an annealing furnace, heated to 220°C for 10 hours, and then kept warm for 60 hours for annealing, and then the temperature is reduced to 186°C and kept warm until the rolling oil is completely removed; after annealing, the coil is taken out of the furnace and cooled, and the single zero aluminum foil wrapped around the outer ring of the aluminum foil coil is wound around another tube core by re-unwinding and rewinding, thereby obtaining a double zero aluminum foil coil with a specification of 0.0063 mm × 1572 mm × 60000 m and a single zero aluminum foil coil with a specification of 0.022 mm × 1572 mm × 3000 m.

[0020] The tensile strength and elongation of the double zero aluminum foil roll and the single zero aluminum foil roll obtained in Examples 1-3 were tested respectively, and then the surface wetting tension test was carried out by spraying the distilled water to detect the wetting tension of the aluminum foil surface. Finally, the appearance of the aluminum foil roll was checked. The test results are shown in Table 9: Table 9 Single / double zero aluminum foil roll test results From the test results in Table 8, it can be seen that the tensile strength of the double zero aluminum foil roll prepared by this method is ≥80 Mpa, and the elongation is >1.5%. The tensile strength of the single zero aluminum foil roll is ≥75 Mpa, and the elongation is >3%. The surface tension of the single / double zero aluminum foil roll is >73×10 -3 N / m, the surface tension test result is spray A+, which meets the requirements of GB / T22638.4-2016. Finally, check the appearance of the single / double zero aluminum foil rolls, the surface is flat and there is no abnormality, and then pack and put into storage.

Claims

1. A method for eliminating the phenomenon of double zero aluminum foil coil annealing, characterized in that: The following steps are involved: (1) Slitting: Slitting the rolled double-zero aluminum foil into double-zero aluminum foil rolls as needed, and the material will not be unloaded after slitting is completed; (2) Prepare materials; Select a single zero aluminum foil with the same alloy and width as the double zero aluminum foil roll in step (1), and weld the single zero aluminum foil and the double zero aluminum foil roll together; (3) Winding; cutting the single zero aluminum foil in step (2) and winding it around the outer ring of the double zero aluminum foil roll in step (1), and unloading the material after cutting to obtain an aluminum foil roll; (4) Annealing; the aluminum foil coil of step (3) is placed in an annealing furnace, heated to 180-230°C for 1-10 hours, and then kept warm for 30-60 hours for annealing, and then the temperature is reduced to 180-190°C and kept warm until the rolling oil is completely removed; after the annealing is completed, the coil is taken out of the furnace and cooled, and the single zero aluminum foil wrapped around the outer ring of the aluminum foil coil is wound around another tube core by re-unwinding and rewinding, thereby obtaining a double zero aluminum foil coil and a single zero aluminum foil coil respectively; (5) Packaging: After the double zero aluminum foil rolls and single zero aluminum foil rolls obtained in step (4) are qualified and have no abnormal appearance, they are packaged and stored separately.

2. The method for eliminating the annealing bar phenomenon of double zero aluminum foil coil according to claim 1, characterized in that: The thickness of the double zero aluminum foil rolled in step (1) is 0.0053-0.0099 mm.

3. A method for eliminating the annealing bar phenomenon of a double zero aluminum foil coil as claimed in claim 2, characterized in that: In both steps (1) and (3), a slitting machine is used for slitting.

4. A method for eliminating the annealing bar phenomenon of a double zero aluminum foil coil as claimed in claim 3, characterized in that: The thickness of the single zero aluminum foil in step (2) is 0.02-0.05 mm.

5. The method for eliminating the annealing bar phenomenon of double zero aluminum foil coil according to claim 4, characterized in that: Ultrasonic welding is used when welding the single zero aluminum foil and double zero aluminum foil rolls in step (2).

6. A method for eliminating the annealing bar phenomenon of a double zero aluminum foil coil as claimed in claim 5, characterized in that: In step (3), the number of meters of single zero aluminum foil winding is greater than 500m.

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