A method for preparing high-elongation cold-formed drug foil by casting and rolling 8021 alloy

Abstract

This invention belongs to the field of aluminum alloy material technology, specifically disclosing a method for preparing high-elongation cold-formed drug foil from cast-rolled 8021 alloy. The method involves producing 8021 alloy billets by casting and rolling, followed by homogenization annealing, cold rough rolling, longitudinal shearing, secondary annealing, and aluminum foil finishing to produce finished aluminum foil. The combined casting and cold rolling processes result in a more significant grain refinement effect. The mechanical properties of the finished product after annealing are superior to those produced by hot rolling, meeting the requirements for deep drawing of cold-formed drug foil. Compared with the conventional direct-cooling ingot hot rolling process for producing cold-formed drug foil, this method eliminates multiple steps such as ingot casting, billet milling, and multiple passes of hot rough rolling, resulting in fewer processes, higher yield, and shorter production time, thus offering significant economic and social benefits.

Description

Technical Field

[0001] This invention belongs to the field of aluminum alloy material technology, and specifically discloses a method for preparing high elongation cold-formed drug foil by casting and rolling 8021 alloy. Background Technology

[0002] Aluminum foil is soft and has excellent moisture-proof, airtight, and light-blocking properties, making it widely used as a packaging material in the food, pharmaceutical, and tobacco industries. Especially in pharmaceutical packaging, almost all medicines use aluminum foil blister packs or PVC thermoformed blister packs combined with PTP aluminum foil. However, for drugs that are easily hygroscopic, hydrolyzed, oxidized, oxygen-sensitive, or light-sensitive, as well as high-value drugs, anti-tumor drugs, export drugs, and drugs requiring long shelf life, it is necessary to use blister packs made of multi-layer composite materials such as BOPA + aluminum foil + PVC / PVDC. Using such cold-formed blister packs can provide thorough moisture-proof, airtight, and light-blocking protection.

[0003] The multi-layer composite material made of BOPA + aluminum foil + PVC / PVDC has high strength and good ductility. After cold stamping, it can be directly stamped into deep cavity blister packs without heating, without damaging the barrier layer. It can make complex shapes with a depth of 15mm or more. The blister pack material produced by this method is 100% oxygen-barrier, moisture-barrier, and light-barrier, with a barrier force of about 60 times that of PVC, which can completely isolate environmental influences. In addition, it has strong formability, does not crack when deep drawn, and has no pinholes, making it suitable for irregularly shaped / large-sized pharmaceuticals. It has high mechanical strength, is puncture-resistant, tear-resistant, has good stiffness, and is resistant to high and low temperatures and extreme environments.

[0004] Currently, the aluminum foil used in domestic cold-formed blister production is generally in the thickness range of 0.04-0.07mm, all produced using hot-rolled 8021 alloy. The core reason for this is that the hot-rolling process ensures high homogeneity equiaxed crystals and stable Fe-Si fine dispersed phases, achieving uniform precipitation of Fe-Si fine particles and inhibiting abnormal grain growth. Furthermore, by matching cold rolling and annealing processes, high elongation of the finished aluminum foil can be achieved, meeting the requirements for deep drawing without cracking. The conventional production process for hot-rolled 8021 alloy aluminum foil is: melting → ingot casting → milling → homogenization annealing → hot rough rolling → hot finish rolling → cold rolling → secondary annealing → cold rolling → edge trimming → foil rolling → slitting → finished product annealing → inspection and packaging. However, the hot-rolling method involves many processes, a long process, high energy consumption, long production cycle, low yield, and high production costs. Moreover, hot-rolling production lines require large equipment, resulting in significant investment costs for purchase, installation, and maintenance, leading to substantial initial investment.

[0005] Chinese patent CN111349825A discloses a method for producing high-toughness battery aluminum foil using a short-process casting and rolling billet. This method requires adding a Sr modifier during the melting and casting process, melting at 770°C for 4-6 hours, and then refining. The added Sr element is chemically very reactive and will preferentially oxidize after being added to the aluminum melt. The resulting strontium oxide has a density of less than 1, which means that it cannot form a dense protective film. At the same time, the aluminum melt temperature of 770°C is much higher than the upper limit of the safe temperature of aluminum melt of 750°C. The interaction between the two makes the hydrogen absorption more serious, which will cause the Sr element to seriously affect the melt quality. In addition, this method requires thirteen processes and at least ten rolling passes, which is a long production process with many rolling passes and high production costs. Chinese patent CN120268800B discloses a method for preparing cast-rolled 8021 alloy aluminum foil. This production method produces a product with relatively high elongation, barely comparable to conventional hot-rolled billet products, but it cannot meet the deep-drawing requirements for cold-formed pharmaceutical foil. Furthermore, the aluminum foil produced according to this method has relatively coarse grains, with obvious coarse grain patterns on the dark side, affecting its performance in certain scenarios. Chinese patent CN111822504B discloses a method for manufacturing pharmaceutical aluminum foil, which introduces an ultrasonic generator into a holding furnace to refine the grains of the molten aluminum. However, because the holding furnace stores a large amount of melt, and the processed melt requires more than 1 hour before casting and rolling, the beneficial effects of ultrasonic vibration and stirring have already been lost, failing to achieve the desired grain refinement effect. Summary of the Invention

[0006] To address the problems in the background art, this invention discloses a method for preparing high-elongation cold-formed drug foil from cast-rolled 8021 alloy. The method involves producing 8021 alloy billets by casting and rolling, followed by homogenization annealing, cold rough rolling, longitudinal shearing, secondary annealing, and aluminum foil finishing to produce finished aluminum foil. The mechanical properties of the finished product after annealing are superior to those of products produced by hot rolling, thus meeting the requirements for deep drawing of cold-formed drug foil.

[0007] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: A method for preparing high-elongation cold-formed drug foil by casting and rolling 8021 alloy specifically includes the following steps: S1. Smelting: Add 45%–55% (by mass) of remelting aluminum ingots and 45%–55% (by mass) of molten aluminum to the smelting furnace. Heat the solid material in the furnace and stir until homogeneous. The melt temperature is 735–749℃. Add alloying agents to the smelting furnace to determine the alloy composition. The mass percentage of the aluminum melt composition is as follows: Si≤0.1%, Fe: 1.3%–1.6%, Cu≤0.04%, Mn≤0.02%, Mg≤0.0%. 2%, Cr≤0.01%, Zn≤0.05%, Ti≤0.025%, with the balance being Al. After the alloy composition ratio is found to be qualified, a refining machine is used to introduce high-purity argon and granular refining agent into the aluminum melt for refining. After refining, the slag on the surface of the aluminum melt is removed, and after settling, the aluminum melt is poured into a holding furnace. During the pouring process, flow refining is carried out. After the pouring is completed, the temperature of the aluminum melt in the holding furnace is 735~745℃. The aluminum melt in the holding furnace is refined once every 3 hours. S2, Casting and Rolling: The molten aluminum in the holding furnace is smoothly discharged through the flow port to the degassing box for degassing and slag removal, and then enters the plate filter box for filtration. The temperature of the molten aluminum at the inlet of the degassing box is not lower than 725℃. Aluminum titanium boron wire is added to the molten aluminum. After degassing, slag removal and filtration, the molten aluminum flows into the front box at a constant speed through the flow stabilizer. The molten aluminum in the front box flows into the space between the upper and lower casting rolls at a constant speed through the casting nozzle. Under the cooling action of the upper and lower casting rolls, the molten aluminum quickly solidifies into a casting plate. The length of the casting and rolling zone is ≥65mm, the casting and rolling speed is ≥980mm / min, and the thickness of the casting and rolling plate is 6.5~7.0mm. The casting and rolling plate is rolled into a casting and rolling coil by the coiler. S3. Homogenization annealing: Using a tube sleeve, the cast and rolled coil obtained in S2 is suspended on the annealing material rack and loaded into a box-type annealing furnace for homogenization annealing. After 4 hours, the furnace temperature is raised to 635℃ at a uniform rate and then held for 20-25 hours. Then, the side cooling is turned on to lower the furnace temperature to 170℃ and held for 2 hours before being taken out of the furnace. S4. Cold rough rolling: After homogenization annealing, the cast-rolled coil is cooled to below 45°C and then transferred to a cold rolling mill for rolling. After three passes, a 0.7mm thick cold-rolled coil is obtained. The specific rolling passes are 6.5~7.0mm→3.1mm→1.5mm→0.7mm. S5, Longitudinal shearing: The cold-rolled coil obtained in S4 is transferred to the longitudinal shearing machine for edge trimming; S6. Secondary annealing: After the S5 is trimmed, the cold-rolled coil is suspended on the annealing rack and put into the box-type annealing furnace for secondary annealing. After 4 hours, the furnace temperature is raised to 480℃ at a uniform rate and held for 10-20 hours. Then the furnace temperature is lowered to 430℃ and held for 5 hours. Finally, the side cooling is turned on to lower the furnace temperature to 170℃ and held for 2 hours before being taken out of the furnace. S7. Finishing rolling of aluminum foil: After the cold-rolled coils that have undergone secondary annealing are cooled to below 45°C after being taken out of the furnace, they are transferred to the foil rolling mill for rolling. The specific rolling passes are 0.7mm→0.35mm→0.17mm→0.085mm→0.04~0.06mm. Among them, the fourth rolling pass is a double-sided rolling, and double-sided edge trimming is performed during double-sided rolling. The double-sided edge trimming rolling speed is less than 400m / min, and the rolling oil spraying amount is greater than 980L / min. S8. Finished product slitting and annealing: The aluminum foil rolled in S7 is slitting into finished products as required. After slitting, the finished products are placed in an annealing furnace for annealing. After 12 hours, the furnace temperature is raised to 220℃ at a uniform rate and held for 8 hours. After another 4 hours, the furnace temperature is raised to 250℃ and held for 50-70 hours. Finally, after 2 hours, the furnace temperature is lowered to 170℃ and held for 4 hours before being taken out of the furnace. S9. Testing and Packaging: Test the mechanical properties of the finished product. The tensile strength of the finished product should be 95-110 MPa, the yield strength should be 60-70 MPa, the elongation should be ≥28%, and the cupping should be ≥7.8 mm. After passing the inspection, package the product according to the packaging requirements.

[0008] Furthermore, in the method for preparing high-elongation cold-formed foil from cast-rolled 8021 alloy, when adding alloying agents to make alloy composition proportions in step S1, manual stirring is carried out simultaneously with electromagnetic stirring for a stirring time of more than 25 minutes to ensure uniform stirring of the melt in the furnace.

[0009] Furthermore, in the method for preparing high-elongation cold-formed drug foil using cast-rolled 8021 alloy, in step S2, ultrasonic casting crystallizers are respectively installed at the inlet of the degassing box and inside the front box. The ultrasonic casting crystallizer at the inlet of the degassing box has a frequency of 30-40 kHz and a power of 900-950 W, while the ultrasonic casting crystallizer inside the front box has a frequency of 15-25 kHz and a power of 400-550 W.

[0010] Furthermore, in the method for preparing high-elongation cold-formed foil from cast-rolled 8021 alloy, in step S3, the blowing mode is turned on during heating, the frequency of the positive pressure fan is adjusted to 10 Hz, and the air intake valve ratio is set to 5%. During heat preservation, positive and negative pressure circulation is turned on, the frequency of the positive pressure fan is adjusted to 20 Hz, the air intake valve ratio is set to 20%, the frequency of the negative pressure fan is adjusted to 10 Hz, and the exhaust valve ratio is set to 10%.

[0011] Furthermore, in the method for preparing high-elongation cold-formed foil from cast-rolled 8021 alloy, in steps S3 and S6, before annealing the coil, several transverse steel strips are applied through a sleeve, and several longitudinal steel strips are applied along the circumference of the coil to bind the coil and prevent loose layers.

[0012] Furthermore, in the method for preparing high-elongation cold-formed drug foil by casting and rolling 8021 alloy, in step S4, a one-key speed increase or decrease is performed for each pass during rolling, and step speed increase or decrease is not allowed.

[0013] Furthermore, in the method for preparing high-elongation cold-formed drug foil using cast-rolled 8021 alloy, in step S5, the total tension during edge trimming is ≤2000N, the width tolerance of the material after trimming is less than ±1mm, the tower-shaped layering does not exceed 2mm, the burrs do not exceed 0.1mm, and there is no aluminum powder accumulation or oil on the edge.

[0014] Furthermore, in the method for preparing high-elongation cold-formed foil from cast-rolled 8021 alloy, during step S7, the content of rolling oil residue is less than 1.5%, and the light transmittance is greater than 98%.

[0015] Furthermore, in the method for preparing high-elongation cold-formed foil from cast-rolled 8021 alloy, in step S8, the annealing furnace maintains negative pressure throughout the annealing process. After the annealing process is completed, the material is taken out of the furnace and cooled down to room temperature by using a convection fan.

[0016] Compared with the prior art, the beneficial effects of the present invention are: (1) The method of preparing high elongation cold-formed drug foil by casting and rolling 8021 alloy of the present invention directly produces 6-7mm thick billets by casting and rolling. The casting and rolling process adopts a large casting and rolling zone + high-speed casting and rolling method. The aluminum melt leaves the high temperature zone faster and the cooling speed is faster. The grains are transformed into solids as soon as they cool and nucleate. The grains do not have time to grow before forming the billet. The grains of the billet are more delicate and uniform. Before the cold rolling process, the ultra-high temperature of 630℃ is rapidly heated and homogenized. The original rolling texture is broken and an annealed texture is formed. At the same time, the structure is rapidly and completely recrystallized to form new, fine, non-preferred equiaxed crystals. The casting and rolling process and the cold rolling process are superimposed, and the grain refinement effect is more obvious. Compared with the conventional direct cooling casting hot rolling method for producing cold-formed drug foil, it saves many steps such as casting, billet milling and multi-pass hot rough rolling. The production method of the present invention has fewer processes, higher yield and shorter production time, and has obvious economic and social benefits. (2) The method for preparing high elongation cold-formed foil by casting and rolling 8021 alloy of the present invention has a reasonable process flow design and adopts the production process of casting and rolling-homogenization annealing-cold rough rolling-slitting edge shearing-secondary annealing-aluminum foil finishing rolling. Both cold rough rolling and aluminum foil finishing rolling are set after annealing, which reduces the rolling deformation and tensile strength, and can realize single-pass high processing rate rolling, and realize the aluminum foil finished product in 7 rolling passes. Compared with the currently disclosed casting and rolling production process, it reduces 1-2 rolling passes. In addition, the thickness of aluminum coil sheet is reasonably set during the two annealing and slitting, reducing the number of material transfers and improving production efficiency. (3) The method of preparing high elongation cold-formed foil by casting and rolling 8021 alloy of the present invention uses dual-stage ultrasonic casting technology at the aluminum-titanium-boron wire addition point and the front box position, and reasonably sets ultrasonic parameters. An ultrasonic casting crystallizer is configured at the aluminum-titanium-boron wire addition point. The ultrasonic vibration and stirring breaks up the Al3Ti and TiB2 agglomerates, enhancing the grain refinement effect. An ultrasonic casting crystallizer is configured at the front box. The strong stirring of the melt eliminates high iron segregation and iron-rich phase, and does not produce liquid surface fluctuation and slag formation. The use of dual-stage ultrasonic casting also eliminates dendritic segregation and banded segregation through stirring, and the composition uniformity is greatly improved. The ultrasonic stirring of the melt activates a large number of nucleation particles, significantly improves the grain size of the billet, and makes the structure more uniform and more isotropic. Due to the significant improvement of segregation inside the billet, the mechanical properties of the finished product are improved, the cracking tendency of the end product is lower, and the use effect is better. (4) The method of preparing high elongation cold-formed drug foil by casting and rolling 8021 alloy of the present invention uses ultrasonic casting technology to improve the grain refinement effect, which can significantly reduce the amount of aluminum titanium boron wire added, and reduce the amount of added by 60% compared with conventional process. At the same time, due to the strong stirring effect of ultrasonic, the possibility of titanium deposition is significantly reduced, avoiding the quality risk of white strips in billet. While reducing production costs, it directly improves product quality and stability. (5) The method of preparing high elongation cold-formed foil by casting and rolling 8021 alloy of the present invention is as follows: after homogenization annealing, the (6.5-7.0) mm thick cast and rolled plate is rolled to 3.1 mm thick in one pass. The high processing rate rolling makes the grains of the billet uniformly broken from the core to the surface, especially the coarse grains in the core of the cast and rolled plate are broken. In addition, the high processing rate forms a strong deformation texture, which is conducive to obtaining a cubic texture after recrystallization. The cubic texture ensures the deep drawing effect of the finished product. (6) The method of preparing high elongation cold-formed foil by casting and rolling 8021 alloy of the present invention uses a metal temperature of 630℃ for homogenization annealing, which significantly improves the diffusion rate of Fe and Si solute atoms, smooths the composition gradient between the dendrites in the cast state more quickly, and increases the uniformity of the composition within the crystal. The non-equilibrium eutectic phase and coarse needle-like β-AlFeSi phase in the cast and rolled billet are more fully spheroidized at 630℃, and the spheroidization rate and roundness of the β-AlFeSi phase are higher. The phase changes from long needle-like shape to short rod / granular shape, and the stress concentration points are greatly reduced, which promotes a significant improvement in plasticity and crack resistance. There are fewer and smaller residual brittle phases, which significantly improves the mechanical properties of the finished product. Detailed Implementation

[0017] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the scope of protection of the present invention is not limited to the following embodiments. Example 1

[0018] A method for preparing high-elongation cold-formed drug foil by casting and rolling 8021 alloy includes the following steps: S1. Smelting: Add 48.6% (by mass) of remelting aluminum ingots and 51.4% (by mass) of electrolytic aluminum liquid to the smelting furnace. Use a natural gas torch to heat the solid material in the furnace. Turn on the electromagnetic stirrer to ensure uniform mixing of the melt. The melt temperature is 747℃. Add alloying agents to the smelting furnace to determine the alloy composition. The mass percentage of the aluminum melt composition is as follows: Si=0.09%, Fe=1.36%, Cu=0.02%, Mn=0.01%, Mg=0.01%, Cr=0.01%, Zn=0. 0.01%, Ti=0.021%, balance Al. Simultaneous electromagnetic stirring and manual stirring are performed for 35 minutes to ensure uniform mixing of the melt in the furnace. After the alloy composition is verified to be qualified, a refining machine is used to introduce high-purity argon and granular refining agent into the aluminum melt through a stainless steel pipe for refining. After refining, the slag on the surface of the aluminum melt is removed, and after standing for 30 minutes, the aluminum melt is poured into a holding furnace. During the pouring process, flow refining is performed. After pouring, the temperature of the aluminum melt in the holding furnace is 738℃. The aluminum melt in the holding furnace is refined every 3 hours. S2, Casting and Rolling: The molten aluminum in the holding furnace is smoothly discharged through the flow channel to the degassing box for degassing and slag removal, and then enters the plate filter box for filtration. After degassing, slag removal, and filtration, the molten aluminum flows into the front box at a uniform speed through the flow stabilizer. The rotor speed of the degassing box is 525 r / min. The filter box uses a 50+60 PPI dual-stage filter plate. Aluminum-titanium-boron wire is added to the molten aluminum at the inlet of the degassing box. The temperature of the molten aluminum at the point where the aluminum-titanium-boron wire is added is 729℃. Ultrasonic casting crystallizers are installed at the inlet of the degassing box and inside the front box, respectively. The frequency is 30kHz and the power is 900W. The ultrasonic casting crystallizer in the front box has a frequency of 15kHz and a power of 400W. The front box is connected to the casting nozzle. The casting nozzle is made using a large flow divider block in a single-stage flow distribution method. The aluminum melt in the front box flows uniformly between the upper and lower casting rolls through the casting nozzle. Under the cooling effect of the upper and lower casting rolls, the aluminum melt quickly solidifies into a casting plate. The length of the casting and rolling zone is 68mm, the casting and rolling speed is 1010mm / min, and the thickness of the casting and rolling plate is 6.5mm. The casting and rolling plate is rolled into a casting and rolling coil by the coiler. S3. Homogenization Annealing: The cast-rolled coil obtained in S2 is bound with four transverse steel strips and six longitudinal steel strips along the circumference of the coil. The coils are tied tightly without loosening. Using a pipe sleeve, the cast-rolled coil is suspended and placed on the annealing rack and loaded into the box-type annealing furnace. Four coils are loaded per furnace, evenly placed, and the furnace door is tightened. After checking that the fan and cooling water are normal, the furnace is opened for homogenization annealing. After 4 hours, the furnace temperature is raised to 635℃ at a uniform rate and then held for 20 hours. During the temperature rise, the blowing mode is turned on, the positive pressure fan frequency is adjusted to 10HZ, and the air inlet valve ratio is set to 5%. During the holding period, positive and negative pressure circulation is turned on, the positive pressure fan frequency is adjusted to 20HZ, the air inlet valve ratio is set to 20%, the negative pressure fan frequency is adjusted to 10HZ, and the exhaust valve ratio is set to 10%. Then, the side cooling is turned on to lower the furnace temperature to 170℃ and hold for 2 hours before being removed from the furnace. S4. Cold rough rolling: After homogenization annealing, the cast-rolled coil is cooled to below 45°C and then transferred to a cold rolling mill for rolling. After three passes, a 0.7mm thick cold-rolled coil is obtained. The specific rolling passes are 6.5mm→3.1mm→1.5mm→0.7mm. During rolling, each pass is subject to one-key speed increase or decrease. Step speed increase or decrease is not allowed. S5. Longitudinal shearing: The cold-rolled coil obtained in S4 is transferred to the longitudinal shearing machine for edge trimming. The total tension during edge trimming is ≤2000N, the width tolerance of the material after trimming is less than ±1mm, the tower-shaped layer does not exceed 2mm, the burrs do not exceed 0.1mm, and there is no aluminum powder accumulation or oil on the edge. S6. Secondary annealing: After the S5 is trimmed and cold-rolled coil is bundled into steel strip, it is suspended on the annealing rack and loaded into the box-type annealing furnace. The material is suspended throughout the transfer, annealing and cooling process. Four coils of material are loaded into each furnace and evenly placed. The furnace door is pressed tight. After checking that the fan and cooling water are normal, the furnace is opened for secondary annealing. After 4 hours, the furnace temperature is raised to 480℃ at a uniform rate and held for 10 hours. Then the furnace temperature is lowered to 430℃ and held for 5 hours. Finally, the side cooling is opened to lower the furnace temperature to 170℃ and held for 2 hours before being taken out of the furnace. S7. Aluminum Foil Finishing Rolling: After the cold-rolled coils are cooled to below 45°C after secondary annealing, they are transferred to the foil rolling mill for rolling. The rolling oil residue content is less than 1.5% and the light transmittance is greater than 98%. The specific rolling passes are 0.7mm→0.35mm→0.17mm→0.085mm→0.05mm. The fourth rolling pass is a double-sided rolling, which includes double-sided edge trimming. To ensure the stability of the edge trimming, the double-sided edge trimming rolling speed is 340m / min and the rolling oil spraying amount is 980L / min. S8. Finished product slitting and annealing: The aluminum foil rolled in S7 is slitting into finished products as required. After slitting, the finished products are placed in an annealing furnace for annealing. After 12 hours, the furnace temperature is raised to 220℃ at a constant rate and held for 8 hours. After another 4 hours, the furnace temperature is raised to 250℃ and held for 50 hours. Finally, after 2 hours, the furnace temperature is lowered to 170℃ and held for 4 hours before being taken out of the furnace. The annealing furnace is kept under negative pressure throughout the annealing process. After the annealing process is completed, the material is taken out of the furnace and cooled down by using a convection fan to cool it to room temperature. S9. Inspection and Packaging: Before packaging the finished product, inspect the material thickness, width, end face quality, surface quality, water application, pinhole condition, and unfolding properties for any abnormalities. Take samples to test the mechanical properties of the finished product. The finished product has a tensile strength of 98 MPa, a yield strength of 65 MPa, an elongation of 32%, and a cupping of 8.0 mm. After passing the inspection, package the product according to the packaging requirements. Example 2

[0019] A method for preparing high-elongation cold-formed drug foil by casting and rolling 8021 alloy includes the following steps: S1. Smelting: Add 53.2% (by mass) of remelting aluminum ingots and 46.8% (by mass) of electrolytic aluminum liquid to the smelting furnace. Use a natural gas torch to heat the solid material in the furnace. Turn on the electromagnetic stirrer to ensure uniform mixing of the melt. The melt temperature is 747℃. Add alloying agents to the smelting furnace to determine the alloy composition. The mass percentage of the aluminum melt composition is as follows: Si=0.07%, Fe=1.54%, Cu=0.01%, Mn=0.01%, Mg=0.01%, Cr=0.01%, Zn=0. 0.01%, Ti=0.018%, balance Al. Simultaneous electromagnetic stirring and manual stirring are performed for 30 minutes to ensure uniform mixing of the melt in the furnace. After the alloy composition is verified to be qualified, a refining machine is used to introduce high-purity argon and granular refining agent into the aluminum melt through a stainless steel pipe for refining. After refining, the slag on the surface of the aluminum melt is removed, and after standing for 30 minutes, the aluminum melt is poured into a holding furnace. During the pouring process, flow refining is performed. After pouring, the temperature of the aluminum melt in the holding furnace is 745℃. The aluminum melt in the holding furnace is refined every 3 hours. S2, Casting and Rolling: The molten aluminum in the holding furnace is smoothly discharged through the flow channel to the degassing box for degassing and slag removal, and then enters the plate filter box for filtration. After degassing, slag removal, and filtration, the molten aluminum flows into the front box at a uniform speed through the flow stabilizer. The rotor speed of the degassing box is 525 r / min. The filter box uses a 50+60 PPI dual-stage filter plate. Aluminum-titanium-boron wire is added to the molten aluminum at the inlet of the degassing box. The temperature of the molten aluminum at the point where the aluminum-titanium-boron wire is added is 730℃. Ultrasonic casting crystallizers are installed at the inlet of the degassing box and inside the front box, respectively. The frequency is 35kHz and the power is 930W. The ultrasonic casting crystallizer in the front box has a frequency of 20kHz and a power of 450W. The front box is connected to the casting nozzle. The casting nozzle is made using a large flow divider block in a single-stage flow distribution method. The aluminum melt in the front box flows uniformly between the upper and lower casting rolls through the casting nozzle. Under the cooling effect of the upper and lower casting rolls, the aluminum melt quickly solidifies into a casting plate. The length of the casting and rolling zone is 68mm, the casting and rolling speed is 1030mm / min, and the thickness of the casting and rolling plate is 6.8mm. The casting and rolling plate is rolled into a casting and rolling coil by the coiler. S3. Homogenization Annealing: The cast-rolled coil obtained in S2 is bound with four transverse steel strips and six longitudinal steel strips along the circumference of the coil. The coils are tied tightly without loosening. Using a pipe sleeve, the cast-rolled coil is suspended and placed on the annealing rack and loaded into the box-type annealing furnace. Four coils are loaded per furnace, evenly placed, and the furnace door is tightened. After checking that the blower and cooling water are normal, the furnace is opened for homogenization annealing. After 4 hours, the furnace temperature is raised to 635℃ at a uniform rate and then held for 25 hours. During the temperature rise, the blowing mode is turned on, the positive pressure blower frequency is adjusted to 10HZ, and the air inlet valve ratio is set to 5%. During the holding period, positive and negative pressure circulation is turned on, the positive pressure blower frequency is adjusted to 20HZ, the air inlet valve ratio is set to 20%, the negative pressure blower frequency is adjusted to 10HZ, and the exhaust valve ratio is set to 10%. Then, the side cooling is turned on to lower the furnace temperature to 170℃ and hold for 2 hours before being removed from the furnace. S4. Cold rough rolling: After homogenization annealing, the cast-rolled coil is cooled to below 45°C and then transferred to a cold rolling mill for rolling. After three passes, a 0.7mm thick cold-rolled coil is obtained. The specific rolling passes are 6.8mm→3.1mm→1.5mm→0.7mm. During rolling, each pass is subject to one-key speed increase or decrease. Step speed increase or decrease is not allowed. S5. Longitudinal shearing: The cold-rolled coil obtained in S4 is transferred to the longitudinal shearing machine for edge trimming. The total tension during edge trimming is ≤2000N, the width tolerance of the material after trimming is less than ±1mm, the tower-shaped layer does not exceed 2mm, the burrs do not exceed 0.1mm, and there is no aluminum powder accumulation or oil on the edge. S6. Secondary Annealing: After the S5 is trimmed and cold-rolled coil is bundled into steel strip, it is suspended on the annealing rack and loaded into the box-type annealing furnace. The material is suspended throughout the transfer, annealing and cooling process. Four coils of material are loaded into each furnace and evenly placed. The furnace door is pressed tight. After checking that the fan and cooling water are normal, the furnace is opened for secondary annealing. After 4 hours, the furnace temperature is raised to 480℃ at a uniform rate and held for 15 hours. Then the furnace temperature is lowered to 430℃ and held for 5 hours. Finally, the side cooling is opened to lower the furnace temperature to 170℃ and held for 2 hours before being taken out of the furnace. S7. Aluminum Foil Finishing Rolling: After the cold-rolled coils that have undergone secondary annealing are cooled to below 45°C after being taken out of the furnace, they are transferred to the foil rolling mill for rolling. During rolling, the residual content of rolling oil is less than 1.5%, and the light transmittance is greater than 98%. The specific rolling passes are 0.7mm→0.35mm→0.17mm→0.085mm→0.055mm. Among them, the fourth rolling pass is double-jointing rolling, and double-jointing edge trimming rolling is performed during double-jointing rolling. To ensure the stability of edge trimming rolling, the double-jointing edge trimming rolling speed is 340m / min, and the rolling oil spraying amount is 980L / min. S8. Finished product slitting and annealing: The aluminum foil rolled in S7 is slitting into finished products as required. After slitting, the finished products are placed in an annealing furnace for annealing. After 12 hours, the furnace temperature is raised to 220℃ at a uniform rate and held for 8 hours. After another 4 hours, the furnace temperature is raised to 250℃ and held for 60 hours. Finally, after 2 hours, the furnace temperature is lowered to 170℃ and held for 4 hours before being taken out of the furnace. The annealing furnace is kept under negative pressure throughout the annealing process. After the annealing process is completed, the material is taken out of the furnace and a convection fan is used to blow air to cool the material to room temperature. S9. Inspection and Packaging: Before packaging the finished product, inspect the material thickness, width, end face quality, surface quality, water application, pinhole condition, and unfoldability for any abnormalities. Take samples to test the mechanical properties of the finished product. The finished product has a tensile strength of 102 MPa, a yield strength of 68 MPa, an elongation of 34%, and a cupping of 8.1 mm. After passing the inspection, package the product according to the packaging requirements. Example 3

[0020] A method for preparing high-elongation cold-formed drug foil by casting and rolling 8021 alloy includes the following steps: S1. Smelting: Add 49.8% (by mass) of remelting aluminum ingots and 50.2% (by mass) of electrolytic aluminum liquid to the smelting furnace. Heat the solid material in the furnace using a natural gas torch. Turn on the electromagnetic stirrer to ensure uniform mixing of the melt in the furnace. The melt temperature is 747℃. Add alloying agents to the smelting furnace to determine the alloy composition. The mass percentage of the aluminum melt composition is as follows: Si=0.08%, Fe=1.47%, Cu=0.02%, Mn=0.01%, Mg=0.01%, Cr=0.01%, Zn=0. 0.01%, Ti=0.024%, balance Al. Simultaneous electromagnetic stirring and manual stirring were performed for 40 minutes to ensure uniform mixing of the melt in the furnace. After the alloy composition was verified to be qualified, a refining machine was used to introduce high-purity argon and granular refining agent into the aluminum melt through a stainless steel pipe for refining. After refining, the slag on the surface of the aluminum melt was removed, and after standing for 30 minutes, the aluminum melt was poured into a holding furnace. During the pouring process, flow refining was performed. After pouring, the temperature of the aluminum melt in the holding furnace was 740℃. The aluminum melt in the holding furnace was refined every 3 hours. S2, Casting and Rolling: The molten aluminum in the holding furnace is smoothly discharged through the flow channel to the degassing box for degassing and slag removal, and then enters the plate filter box for filtration. After degassing, slag removal, and filtration, the molten aluminum flows into the front box at a uniform speed through the flow stabilizer. The rotor speed of the degassing box is 525 r / min. The filter box uses a 50+60 PPI dual-stage filter plate. Aluminum-titanium-boron wire is added to the molten aluminum at the inlet of the degassing box. The temperature of the molten aluminum at the point where the aluminum-titanium-boron wire is added is 730℃. Ultrasonic casting crystallizers are installed at the inlet of the degassing box and inside the front box, respectively. The frequency is 40kHz and the power is 950W. The ultrasonic casting crystallizer in the front box has a frequency of 25kHz and a power of 550W. The front box is connected to the casting nozzle. The casting nozzle is made using a large flow divider block in a single-stage flow distribution method. The aluminum melt in the front box flows uniformly between the upper and lower casting rolls through the casting nozzle. Under the cooling effect of the upper and lower casting rolls, the aluminum melt quickly solidifies into a casting plate. The length of the casting and rolling zone is 68mm, the casting and rolling speed is 1060mm / min, and the thickness of the casting and rolling plate is 7.0mm. The casting and rolling plate is rolled into a casting and rolling coil by the coiler. S3. Homogenization Annealing: The cast-rolled coil obtained in S2 is bound with four transverse steel strips and six longitudinal steel strips along the circumference of the coil. The coils are tied tightly without loosening. Using a pipe sleeve, the cast-rolled coil is suspended and placed on the annealing rack and loaded into the box-type annealing furnace. Four coils are loaded per furnace, evenly placed, and the furnace door is tightened. After checking that the blower and cooling water are normal, the furnace is opened for homogenization annealing. After 4 hours, the furnace temperature is raised to 635℃ at a uniform rate and then held for 25 hours. During the temperature rise, the blowing mode is turned on, the positive pressure blower frequency is adjusted to 10HZ, and the air inlet valve ratio is set to 5%. During the holding period, positive and negative pressure circulation is turned on, the positive pressure blower frequency is adjusted to 20HZ, the air inlet valve ratio is set to 20%, the negative pressure blower frequency is adjusted to 10HZ, and the exhaust valve ratio is set to 10%. Then, the side cooling is turned on to lower the furnace temperature to 170℃ and hold for 2 hours before being removed from the furnace. S4. Cold rough rolling: After homogenization annealing, the cast-rolled coil is cooled to below 45°C and then transferred to a cold rolling mill for rolling. After three passes, a 0.7mm thick cold-rolled coil is obtained. The specific rolling passes are 7.0mm→3.1mm→1.5mm→0.7mm. During rolling, each pass is subject to one-key speed increase or decrease. Step speed increase or decrease is not allowed. S5. Longitudinal shearing: The cold-rolled coil obtained in S4 is transferred to the longitudinal shearing machine for edge trimming. The total tension during edge trimming is ≤2000N, the width tolerance of the material after trimming is less than ±1mm, the tower-shaped layer does not exceed 2mm, the burrs do not exceed 0.1mm, and there is no aluminum powder accumulation or oil on the edge. S6. Secondary Annealing: After the S5 is trimmed and cold-rolled coil is bundled into steel strip, it is suspended on the annealing rack and loaded into the box-type annealing furnace. The material is suspended throughout the transfer, annealing and cooling process. Four coils of material are loaded into each furnace and evenly placed. The furnace door is pressed tight. After checking that the fan and cooling water are normal, the furnace is opened for secondary annealing. After 4 hours, the furnace temperature is raised to 480℃ at a uniform rate and held for 20 hours. Then the furnace temperature is lowered to 430℃ and held for 5 hours. Finally, the side cooling is opened to lower the furnace temperature to 170℃ and held for 2 hours before being taken out of the furnace. S7. Aluminum Foil Finishing Rolling: After the cold-rolled coils are cooled to below 45°C after secondary annealing, they are transferred to the foil rolling mill for rolling. The rolling oil residue content is less than 1.5% and the light transmittance is greater than 98%. The specific rolling passes are 0.7mm→0.35mm→0.17mm→0.085mm→0.045mm. The fourth rolling pass is a double-sided rolling, which includes double-sided edge trimming. To ensure the stability of the edge trimming, the double-sided edge trimming rolling speed is 340m / min and the rolling oil spraying amount is 980L / min. S8. Finished product slitting and annealing: The aluminum foil rolled in S7 is slitting into finished products as required. After slitting, the finished products are placed in an annealing furnace for annealing. After 12 hours, the furnace temperature is raised to 220℃ at a constant rate and held for 8 hours. After another 4 hours, the furnace temperature is raised to 250℃ and held for 70 hours. Finally, after 2 hours, the furnace temperature is lowered to 170℃ and held for 4 hours before being taken out of the furnace. The annealing furnace is kept under negative pressure throughout the annealing process. After the annealing process is completed, the material is taken out of the furnace and cooled down by using a convection fan to cool it to room temperature. S9. Inspection and Packaging: Before packaging the finished product, inspect the material thickness, width, end face quality, surface quality, water application, pinhole condition, and unfolding properties for any abnormalities. Take samples to test the mechanical properties of the finished product. The finished product has a tensile strength of 101 MPa, a yield strength of 64 MPa, an elongation of 30%, and a cupping of 7.9 mm. After passing the inspection, package the product according to the packaging requirements.

[0021] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solutions of the present invention, as long as they do not depart from the spirit and scope of the technical solutions of the present invention, should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing high-elongation cold-formed pharmaceutical foil by casting and rolling 8021 alloy, characterized in that, Specifically, the following steps are included: S1. Smelting: Add 45%–55% (by mass) of remelting aluminum ingots and 45%–55% (by mass) of molten aluminum to the smelting furnace. Heat the solid material in the furnace and stir until homogeneous. The melt temperature is 735–749℃. Add alloying agents to the smelting furnace to determine the alloy composition. The mass percentage of the aluminum melt composition is as follows: Si≤0.1%, Fe: 1.3%–1.6%, Cu≤0.04%, Mn≤0.02%, Mg≤0.0%. 2%, Cr≤0.01%, Zn≤0.05%, Ti≤0.025%, with the balance being Al. After the alloy composition ratio is found to be qualified, a refining machine is used to introduce high-purity argon and granular refining agent into the aluminum melt for refining. After refining, the slag on the surface of the aluminum melt is removed, and after settling, the aluminum melt is poured into a holding furnace. During the pouring process, flow refining is carried out. After the pouring is completed, the temperature of the aluminum melt in the holding furnace is 735~745℃. The aluminum melt in the holding furnace is refined once every 3 hours. S2, Casting and Rolling: The molten aluminum in the holding furnace is smoothly discharged through the flow port to the degassing box for degassing and slag removal, and then enters the plate filter box for filtration. The temperature of the molten aluminum at the inlet of the degassing box is not lower than 725℃. Aluminum titanium boron wire is added to the molten aluminum. After degassing, slag removal and filtration, the molten aluminum flows into the front box at a constant speed through the flow stabilizer. The molten aluminum in the front box flows into the space between the upper and lower casting rolls at a constant speed through the casting nozzle. Under the cooling action of the upper and lower casting rolls, the molten aluminum quickly solidifies into a casting plate. The length of the casting and rolling zone is ≥65mm, the casting and rolling speed is ≥980mm / min, and the thickness of the casting and rolling plate is 6.5~7.0mm. The casting and rolling plate is rolled into a casting and rolling coil by the coiler. S3. Homogenization annealing: Using a tube sleeve, the cast and rolled coil obtained in S2 is suspended on the annealing material rack and loaded into a box-type annealing furnace for homogenization annealing. After 4 hours, the furnace temperature is raised to 635℃ at a uniform rate and then held for 20-25 hours. Then, the side cooling is turned on to lower the furnace temperature to 170℃ and held for 2 hours before being taken out of the furnace. S4. Cold rough rolling: After homogenization annealing, the cast-rolled coil is cooled to below 45°C and then transferred to a cold rolling mill for rolling. After three passes, a 0.7mm thick cold-rolled coil is obtained. The specific rolling passes are 6.5~7.0mm→3.1mm→1.5mm→0.7mm. S5, Longitudinal shearing: The cold-rolled coil obtained in S4 is transferred to the longitudinal shearing machine for edge trimming; S6. Secondary annealing: After the S5 is trimmed, the cold-rolled coil is suspended on the annealing rack and put into the box-type annealing furnace for secondary annealing. After 4 hours, the furnace temperature is raised to 480℃ at a uniform rate and held for 10-20 hours. Then the furnace temperature is lowered to 430℃ and held for 5 hours. Finally, the side cooling is turned on to lower the furnace temperature to 170℃ and held for 2 hours before being taken out of the furnace. S7. Precision rolling of aluminum foil: After the cold-rolled coils are annealed twice, they are cooled to below 45°C and then transferred to the foil rolling mill for rolling. The specific rolling passes are 0.7mm→0.35mm→0.17mm→0.085mm→0.04~0.06mm. The fourth rolling pass is a double-sided rolling, during which double-sided edge trimming is performed. The double-sided edge trimming rolling speed is less than 400m / min, and the rolling oil spraying amount is not less than 980L / min. S8. Finished product slitting and annealing: The aluminum foil rolled in S7 is slitting into finished products as required. After slitting, the finished products are placed in an annealing furnace for annealing. After 12 hours, the furnace temperature is raised to 220℃ at a uniform rate and held for 8 hours. After another 4 hours, the furnace temperature is raised to 250℃ and held for 50-70 hours. Finally, after 2 hours, the furnace temperature is lowered to 170℃ and held for 4 hours before being taken out of the furnace. S9. Testing and Packaging: Test the mechanical properties of the finished product. The tensile strength of the finished product should be 95-110 MPa, the yield strength should be 60-70 MPa, the elongation should be ≥28%, and the cupping should be ≥7.8 mm. After passing the inspection, package the product according to the packaging requirements.

2. The method for preparing high-elongation cold-formed pharmaceutical foil by casting and rolling 8021 alloy according to claim 1, characterized in that, When adding alloying agents in step S1 to determine the alloy composition ratio, manual stirring should be carried out simultaneously with electromagnetic stirring for at least 25 minutes to ensure uniform stirring of the melt in the furnace.

3. The method for preparing high-elongation cold-formed pharmaceutical foil by casting and rolling 8021 alloy according to claim 1, characterized in that, In step S2, ultrasonic casting crystallizers are installed at the inlet of the degassing box and inside the front box, respectively. The ultrasonic casting crystallizer at the inlet of the degassing box has a frequency of 30-40 kHz and a power of 900-950 W, while the ultrasonic casting crystallizer inside the front box has a frequency of 15-25 kHz and a power of 400-550 W.

4. The method for preparing high-elongation cold-formed pharmaceutical foil by casting and rolling 8021 alloy according to claim 1, characterized in that, In step S3, when heating up, the blowing mode is turned on, the frequency of the positive pressure fan is adjusted to 10HZ, and the air intake valve ratio is set to 5%. When heat preservation, the positive and negative pressure circulation is turned on, the frequency of the positive pressure fan is adjusted to 20HZ, the air intake valve ratio is set to 20%, the frequency of the negative pressure fan is adjusted to 10HZ, and the exhaust valve ratio is set to 10%.

5. The method for preparing high-elongation cold-formed pharmaceutical foil by casting and rolling 8021 alloy according to claim 1, characterized in that, In steps S3 and S6, before the coil is annealed, several transverse steel strips are applied through the sleeve and several longitudinal steel strips are applied along the circumference of the coil to bind the coil and prevent it from becoming loose.

6. The method for preparing high-elongation cold-formed pharmaceutical foil by casting and rolling 8021 alloy according to claim 1, characterized in that, In step S4, a one-click speed increase or decrease is performed for each pass during rolling; step speed increases or decreases are not allowed.

7. The method for preparing high-elongation cold-formed pharmaceutical foil by casting and rolling 8021 alloy according to claim 1, characterized in that, In step S5, the total tension during edge trimming is ≤2000N, the width tolerance of the material after trimming is less than ±1mm, the tower-shaped layer thickness is no more than 2mm, the burrs are no more than 0.1mm, and there is no aluminum powder accumulation or oil on the edge.

8. The method for preparing high-elongation cold-formed pharmaceutical foil by casting and rolling 8021 alloy according to claim 1, characterized in that, In step S7, during foil rolling, the content of rolling oil residue is less than 1.5%, and the light transmittance is greater than 98%.

9. The method for preparing high-elongation cold-formed pharmaceutical foil by casting and rolling 8021 alloy according to claim 1, characterized in that, In step S8, the annealing furnace maintains negative pressure throughout the annealing process. After the annealing process is completed, the material is taken out of the furnace and a convection fan is used to blow air to cool the material to room temperature.