Aluminum foil blank and cast rolling method thereof

Abstract

The invention discloses a cast rolling method of an aluminum foil blank, which comprises the following steps: step S1, smelting, stirring, refining for the first time, standing for the first time, slagging off for the first time, turning down, refining for the second time, slagging off for the second time, standing for the second time and degassing in sequence according to a raw material formula to complete the preparation of molten aluminum; s2, the molten aluminum is filtered through a filter box; and S3, the filtered molten aluminum sequentially passes through a steady flow box, a front box and a casting nozzle to be fed into a double-roller type casting and rolling machine to be sequentially subjected to continuous casting and rolling and coiling, and an aluminum foil blank is obtained. The aluminum foil blank obtained through the cast rolling method is further rolled to obtain the aluminum foil with the thickness of 0.012-0.015 mm, the pinhole density of the aluminum foil is 0.008-0.012 / m < 2 >, the black line density of the aluminum foil is 0.0002-0.0005 / m < 2 >, and the black line length of the aluminum foil is smaller than or equal to 3 mm, so that the pinhole density and the black line density of the aluminum foil are reduced, and the black line length of the aluminum foil is shortened.

Description

[Technical field]

[0001] The invention relates to the technical field of aluminum processing, and in particular to an aluminum foil blank and a casting and rolling method thereof. [Background technology]

[0002] The casting and rolling method for producing aluminum foil billets has the advantages of "short process, low cost, and low energy consumption". However, in the casting and rolling production process, there are still corresponding defects due to the limitations of its production conditions, as follows:

[0003] 1. When ordinary electrolytic aluminum ingots are used for production, the Mg content is not strictly restricted, which easily leads to the generation of spinel defects of MgO or Al2O3*MgO during the smelting process. MgO and Al2O3*MgO are easy to gather at the casting nozzle and enter the casting and rolling coil; because the V content is not strictly restricted, it is easy to cause V and AlTi5B1 refiner to agglomerate.

[0004] 2. Use Grade A AlTi5B1 grain refiner and add it to the flow channel 2 to 5 meters away from the degassing box entrance. When the flow channel temperature is 680 to 720 ° C, it is easy for the refiner to not be fully dissolved due to the low temperature, and the TiB2 particles will agglomerate and form slag.

[0005] 3. The filtration process uses a double-stage ceramic filter plate with a thickness of 50mm, "50ppi+60ppi" or "60ppi+60ppi" or "60ppi+70ppi". The probability of intercepting inclusions with a particle size greater than or equal to 5μm is only 70-75%. The slag is measured on the aluminum liquid at the outlet of the filter box, and the inclusion content is 0.08-0.16mm 2 / Kg; therefore, inclusions such as oxides, chlorides, nitrides, etc. with a particle size of 5 to 20 μm cannot be effectively intercepted and flow into the aluminum melt; and some old production lines have small space and no area to install additional tubular filters or deep bed filters with higher accuracy. In addition, adding tubular filters or deep bed filters will also increase production costs.

[0006] In summary, the casting and rolling method of aluminum foil billets in the related art will eventually lead to the production of aluminum foil with defects such as high pinhole density, excessive black line density of aluminum foil, and excessively long black lines of aluminum foil. [Summary of the invention]

[0007] The purpose of the embodiments of the present invention is to provide a new aluminum foil blank and a casting and rolling method thereof, so as to solve the problem that the casting and rolling method of the aluminum foil blank in the related art will eventually lead to the production of aluminum foil with a large pinhole density, an excessively large black line density of the aluminum foil, and an excessively long black line of the aluminum foil.

[0008] In a first aspect, an embodiment of the present invention provides a casting and rolling method for an aluminum foil blank, which comprises the following steps:

[0009] Step S1, preparing aluminum liquid by melting, stirring, first refining, first standing, first slagging, pouring, second refining, second slagging, second standing and degassing according to the following raw material formula, and the degassing process is carried out by a degassing box;

[0010] The components and mass percentages of the raw material formula are: Al≥99.700%, Si≤0.100%, Fe≤0.200%, Cu≤0.007%, Ga≤0.030%, Mg≤0.008%, Zn≤0.030%, V≤0.012%, Ti≤0.020%, the sum of other impurity elements is less than or equal to 0.300%, and the mass percentage of a single element of other impurity elements is less than or equal to 0.030%; the element Ti is configured in the form of AlTi5B0.6 aluminum titanium boron wire, and is used as a grain refiner to be fed into the inlet of the degassing box through a wire feeder in the process of degassing by a single wire. During the degassing process, the temperature of the aluminum liquid in the degassing box is 725±5°C;

[0011] Step S2, filtering the aluminum liquid through a filter box; a double-stage foam ceramic filter plate with a thickness of 100 mm and a thickness of 60 ppi and 80 ppi is used for filtering, and the temperature of the aluminum liquid during filtering is 705-710° C.;

[0012] Step S3, the filtered aluminum liquid is sent to a twin-roll caster through a flow stabilizing box, a flow trough, a front box and a casting nozzle in sequence for continuous casting and rolling and then coiled to obtain an aluminum foil billet; before the twin-roll caster is used, a dust prevention device of the twin-roll caster is installed, and during the continuous casting and rolling process, the casting roll surface of the twin-roll caster is continuously lubricated by flame spraying.

[0013] Preferably, in step S1, when the grain refiner is added during the degassing process, the grain refiner is vibrated by a transverse vibration device, and the vibration frequency of the transverse vibration device is 45 to 55 times per minute; the cooling water pressure of the casting roll sleeve is 0.7 to 0.9 MPa.

[0014] Preferably, in step S1, the microstructure of the grain refiner meets the following requirements: 2In the longitudinal section microstructure, the number of TiB2 particles with a size less than or equal to 1.8μm accounts for greater than or equal to 95%, and the maximum size of the TiB2 particles is less than or equal to 4μm; among the agglomerated TiB2 particles, the number of agglomerated TiB2 particles with a size less than or equal to 25μm is less than or equal to 3, and the number of agglomerated TiB2 particles with a size greater than 25μm is 0; among the TiAl3 particles, the number of TiAl3 particles with a size less than or equal to 100μm accounts for greater than or equal to 95%, and the average size of the TiAl3 particles is less than or equal to 25μm, and the maximum size of a single TiAl3 particle is less than or equal to 150μm; the total length of oxide and salt inclusions is less than or equal to 1000μm, and the maximum size is less than or equal to 500μm.

[0015] Preferably, the inner lining of the filter box, the inner lining of the flow box, the inner lining of the front box, the inner lining of the flow channel and the casting nozzle that will be in contact with the aluminum liquid are sprayed or painted with boron nitride coating before use; the components and mass percentage of the boron nitride coating include: 26-28% hexagonal boron nitride powder, 5-9% binder, and the boron nitride coating does not contain phosphates, silicates, pigments, additives and fillers.

[0016] Preferably, the components and mass percentages of the hexagonal boron nitride powder are: hexagonal boron nitride is greater than or equal to 99.9%, boron oxide is less than or equal to 0.1%, and hexagonal boron nitride with a particle size of 15 to 40 μm and hexagonal boron nitride with a particle size of 0.5 to 5 μm are mixed in a ratio of 1:0.1 to 1:1 to form the hexagonal boron nitride powder, and the raw material of the binder is aluminum sol with a particle size of 3 to 40 nm.

[0017] Preferably, before the flow stabilizer is used, a high-aluminum fiber blanket is used as a sealing soft connection liner for connecting the filter box and the flow stabilizer; the components and mass percentages of the high-aluminum fiber blanket are: Al2O3 70-72%, SiO2 27-30%, CaO <0.1%, MgO <0.1%, 70-mesh slag ball <0.5%, the thickness of the high-aluminum fiber blanket is 23-28 mm, and the volume density of the high-aluminum fiber blanket is 86-110 kg / m 3 The average tensile strength of high-aluminum fiber blanket is 80-95Kg / m 2 .

[0018] Preferably, before installing the dust prevention device on the twin-roll cast-rolling mill, the machine column, top crossbeam, nozzle adjustment mechanism, cast-rolling mill arch, pressure device, cast-rolling roll rotary joint, cast-rolling roll bearing seat, lifting guide plate, flame spray lubrication guide rail, exit guide roller, pinch roller, scissors, winding guide roller and winding shaft of the twin-roll cast-rolling mill are cleaned.

[0019] Preferably, before the twin-roll casting mill is used, the outlet guide roller and the winding guide roller of the twin-roll casting mill are replaced with spray guide rollers sprayed with tungsten carbide; the thickness of the tungsten carbide layer sprayed on the spray guide roller is 0.1-0.2 mm, the roughness of the tungsten carbide layer sprayed on the spray guide roller is 0.02-0.15 μm, and the hardness of the tungsten carbide layer sprayed on the spray guide roller is greater than or equal to 1000 HV 300 The components and mass percentages of tungsten carbide include: W≥50%, C≥5%, Cr≥5%.

[0020] Preferably, the dust prevention device includes a cover plate integrally formed with the top of the machine train of the twin-roll cast-rolling mill, a cloth curtain installed on the transmission side and the winding side of the machine train of the twin-roll cast-rolling mill, a long and transparent polyvinyl chloride soft plastic curtain installed on the operation side of the machine train of the twin-roll cast-rolling mill, an electric rolling door installed on the arch of the twin-roll cast-rolling mill, and a cloth strip sealed between the casting roller bearing seats on the operation side and the transmission side of the machine train of the twin-roll cast-rolling mill, the upper part of the cloth curtain is in contact with the cover plate, the lower part of the cloth curtain is in contact with the ground, the upper part of the polyvinyl chloride soft plastic curtain is in contact with the cover plate, the lower part of the polyvinyl chloride soft plastic curtain is in contact with the ground, and when the electric rolling door is opened, the bottom of the electric rolling door is spaced 40 to 100 mm from the upper part of the front box.

[0021] In a second aspect, an embodiment of the present invention provides an aluminum foil blank, which is made by the casting and rolling method of the aluminum foil blank as described above.

[0022] Compared with the related art, the casting and rolling method of the aluminum foil billet in the present invention limits the raw material components, specifically limits the elements Mg and V, uses AlTi5B0.6 aluminum titanium boron wire as a grain refiner, and uses a double-stage foam ceramic filter plate with a thickness of 100 mm and a thickness of 60ppi and 80ppi for filtering, installs a dust prevention device on the double-roll casting and rolling mill, sprays the surface of the casting and rolling roll, and limits other parameters for continuous casting and rolling. The cast and rolling coil for the aluminum foil billet produced by the above method has an inclusion content of 0.009-0.015mm after the aluminum liquid is filtered. 2 / Kg, and there is no obvious foreign matter pressed into the surface, no aluminum sticking and no scratch defects, and it is further rolled into a finished aluminum foil with a thickness of 0.012-0.015mm, and its pinhole density is 0.008~0.012 / m 2 , black line density is 0.0002~0.0005 / m 2 , the black line length is less than or equal to 3mm, thereby greatly reducing the pinhole density and black line density of the aluminum foil, and shortening the black line length of the aluminum foil.

Brief Description of the Drawings

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work, among which:

[0024] Figure 1 A schematic flow chart of a casting and rolling method for aluminum foil blanks provided in an embodiment of the present invention;

[0025] Figure 2 A schematic structural diagram of a dust prevention device installed on a twin-roll casting and rolling mill used in the casting and rolling method of aluminum foil billets provided in an embodiment of the present invention. [Specific implementation method]

[0026] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] The embodiment of the present invention provides a casting and rolling method for aluminum foil billet, Figure 1 As shown, it includes the following steps:

[0028] S1. According to the raw material formula, aluminum liquid is prepared by smelting, stirring, first refining, first standing, first slag removal, furnace pouring, second refining, second slag removal, second standing and degassing.

[0029] Wherein, the components and mass percentages of the raw material formula are: Al≥99.700%, Si≤0.100%, Fe≤0.200%, Cu≤0.007%, Ga≤0.030%, Mg≤0.008%, Zn≤0.030%, V≤0.012%, Ti≤0.020%, the sum of other impurity elements is less than or equal to 0.300%, and the mass percentage of a single element in other impurity elements is less than or equal to 0.030%. Preferably, the components and mass percentages of the raw material formula are: Al, 99.790%, Si, 0.050%, Fe, 0.080%, Cu, 0.005%, Ga, 0.013%, Mg, 0.002%, Zn, 0.010%, V, 0.010%, Ti, 0.002%, and the sum of other impurity elements is 0.038%.

[0030] During the smelting and casting of aluminum and aluminum alloys, spinel defects of MgO or Al2O3*MgO are easily formed. MgO and Al2O3*MgO are easy to gather at the casting nozzle and enter the casting and rolling coil, so the original Mg content in the electrolytic aluminum ingot should be strictly controlled, but it should not be too strict, otherwise it will increase the procurement cost; V in the aluminum melt is easy to agglomerate with the elements Ti and B in the grain refiner of the aluminum titanium boron wire, resulting in "titanium deposition", so V in the electrolytic aluminum ingot should be limited. Taking all factors into consideration, Mg in the electrolytic aluminum ingot is ≤0.008% and V is ≤0.012%.

[0031] The steps of smelting, stirring, first refining, first standing and first slagging are all carried out in the smelting furnace, and stirring is done by electromagnetic stirring; pouring the furnace is to pour the liquid in the smelting furnace into the holding furnace, and the second refining, second slagging and second standing are all carried out in the holding furnace. Between the first slagging and pouring, the steps of sampling the smelting furnace and testing the chemical composition and chemical adjustment are also included in order to strictly control the composition of the raw material formula.

[0032] The element Ti is configured in the form of AlTi5B0.6 aluminum titanium boron wire, and is fed into the inlet of the degassing box as a grain refiner through a wire feeder in the degassing process in the form of a single wire. During the degassing process, the degassing box is used for degassing, and a silicon carbide rotor is used for degassing. The temperature of the aluminum liquid in the degassing box is 725±5°C. Preferably, the temperature of the aluminum liquid in the degassing box is 721-728°C.

[0033] The microstructure of the grain refiner meets the following requirements: 2In the longitudinal section microstructure, among single TiB2 particles, the number of TiB2 particles with a size less than or equal to 1.8μm accounts for greater than or equal to 95%, and the maximum size of the TiB2 particles is less than or equal to 4μm; among agglomerated TiB2 particles, the number of agglomerated TiB2 particles with a size less than or equal to 25μm is less than or equal to 3, and the number of agglomerated TiB2 particles with a size greater than 25μm is 0; among TiAl3 particles, the number of TiAl3 particles with a size less than or equal to 100μm accounts for greater than or equal to 95%, and the average size of TiAl3 particles is less than or equal to 25μm, and the maximum size of a single TiAl3 particle is less than or equal to 150μm; the total length of oxide and salt inclusions is less than or equal to 1000μm, and the maximum size is less than or equal to 500μm; and there are no solid inclusions such as aluminum-boron compounds, refractory materials, and undissolved metal inclusions. Preferably, in a single TiB2 particle, the number of TiB2 particles with a size less than or equal to 1.8μm accounts for greater than or equal to 98%, and the maximum size of the TiB2 particles is 4μm; in agglomerated TiB2 particles, the number of agglomerated TiB2 particles with a size less than or equal to 25μm is 2 and the number of agglomerated TiB2 particles with a size greater than 25μm is 0; in TiAl3 particles, the number of TiAl3 particles with a size less than or equal to 100μm accounts for greater than or equal to 96%, and the average size of the TiAl3 particles is 20μm, and the maximum size of a single TiAl3 particle is 150μm; the total length of oxide and salt inclusions is 750μm, and the maximum size is 300μm.

[0034] Among the grain refiners of aluminum titanium boron wire, TiB2 particles have a high melting point (2900-3225°C), large surface free energy, and a density of 4.5 g / cm 3 , while the density of aluminum melt is 2.5~2.7g / cm 3 , which will cause TiB2 particles to be unable to dissolve in the aluminum melt, and they are prone to self-agglomeration in the aluminum melt, or adsorb other particles (such as V, various insoluble solids) to agglomerate. After that, because their density is greater than that of the aluminum liquid, they are very easy to precipitate at the bottom of the aluminum liquid. In addition, among the grain refiners of aluminum titanium boron wire, the larger the size and the greater the number of TiAl3 particles, the more difficult it is to quickly dissolve in the aluminum melt. Therefore, AlTi5B0.6 is selected to replace AlTi5B1, limiting the maximum size and number of TiB2 particles, and limiting the maximum size and number of TiAl3 particles. Limiting the total length and maximum size of oxide and salt inclusions, and not allowing solid inclusions, etc., can reduce the probability of particle agglomeration and deposition.

[0035] When the grain refiner is added during the degassing process, the grain refiner is vibrated by a transverse vibration device, and the vibration frequency of the transverse vibration device is 45 to 55 times per minute. Preferably, the vibration frequency of the transverse vibration device is 50 times per minute; the cooling water pressure of the casting roll sleeve of the twin-roll casting mill is 0.7 to 0.9 MPa, and preferably, the cooling water pressure of the casting roll sleeve of the twin-roll casting mill is 0.85 MPa.

[0036] Because there is heat loss in the flow channel between the furnace outlet and the degassing box entrance during the second static period, the temperature of the aluminum liquid is between 680 and 720°C, which is unstable. Especially when the aluminum liquid temperature is less than or equal to 700°C, the dissolution rate of TiAl3 particles will be reduced, so it is necessary to change the aluminum titanium boron wire addition point to the degassing box. Since the degassing box has a heating device, the aluminum liquid temperature can be stably maintained at 725±5°C, and the rotation of the silicon nitride rotor in the degassing box will promote the dissolution of TiAl3 particles. At the same time, vibrating the lateral vibration device introduced by the aluminum titanium boron wire can also promote the dissolution of TiAl3 particles. However, since the B content in AlTi5B0.6 is significantly lower than that in AlTi5B1, and TiB2 particles can significantly enhance the grain refining ability of Al-Ti, using AlTi5B0.6 to replace AlTi5B1 will weaken the grain refining ability when other conditions remain unchanged. Therefore, it is necessary to increase the cooling water pressure of the casting roll sleeve to 0.7-0.9MPa (the cooling water pressure of the conventional casting roll sleeve is 0.4-0.65MPa) to compensate for the weakened grain refining ability by increasing the degree of supercooling.

[0037] Of course, according to actual needs, the aluminum liquid can also be prepared through smelting, first stirring, first refining, first standing, first slag removal, second stirring, second standing, second slag removal, furnace pouring, second refining, third slag removal, third standing and degassing processes in sequence.

[0038] S2. Filtering the aluminum liquid through a filter box.

[0039] The filtration was carried out using a double-stage foam ceramic filter plate with a thickness of 100 mm and 60 ppi and 80 ppi, and the temperature of the aluminum liquid was 705-710° C. during the filtration.

[0040] When the aluminum melt containing inclusions passes through the foam ceramic filter plate, its filtration efficiency is related to the following factors: n = (Ci-C0) / Ci = 1-exp (K0*L / Um), where n is the filtration efficiency, K0 is the kinetic parameter coefficient, Ci is the initial concentration of inclusions in the aluminum melt, C0 is the concentration of inclusions in the aluminum melt after filtration, L is the thickness of the foam ceramic filter plate, and Um is the filtration accuracy of the aluminum melt. At present, the thickness of the foam ceramic filter plates used in the industry is 50mm without other thickness specifications. This embodiment improves the filtration accuracy by changing the thickness of the foam ceramic filter plate from 50mm to 100mm and the mesh number from 60ppi to 80ppi, which is equivalent to improving the filtration accuracy by not less than 100%, and increasing the interception probability of inclusions; and changing to this filtration arrangement does not require additional space, and does not require additional tubular filters or deep bed filters, and the cost is relatively low, which is very suitable for upgrading the filtration facilities of old production lines with small spaces.

[0041] After testing, the inclusion content of the aluminum liquid after filtration is 0.009~0.015mm 2 / Kg; the dust in the area in front of the casting roll with a size greater than or equal to 5.0μm is 100-175 pieces / m 3 , dust particles with a size greater than or equal to 10.0 μm are 50 to 100 particles / m 3 Preferably, the inclusion content of the aluminum liquid after filtration is 0.013 mm 2 / Kg; the dust in the area in front of the casting roll with a size greater than or equal to 5.0μm is 110 to 124 pieces / m 3 , the number of dust particles with a size greater than or equal to 10.0 μm is 68 to 83 per m 3 .

[0042] S3, the filtered aluminum liquid is sent to a twin-roll casting and rolling machine through a flow stabilizing box, a flow trough, a front box and a casting nozzle in sequence for continuous casting and rolling, and then coiled to obtain an aluminum foil billet.

[0043] The continuous casting and rolling process continuously lubricates the casting roll surface of the twin-roll casting and rolling mill through flame spraying.

[0044] Before using the twin-roll casting and rolling mill, a dust prevention device of the twin-roll casting and rolling mill is installed; Figure 2As shown in the figure, the machine train of the twin-roll casting and rolling mill is not installed with the internal structure, and only the frame 1 of the machine train of the twin-roll casting and rolling mill is shown. The dust prevention device includes a cover plate 2 integrally formed with the top of the machine train of the twin-roll casting and rolling mill, a cloth curtain 3 installed on the transmission side and the winding side of the machine train of the twin-roll casting and rolling mill, a long and transparent polyvinyl chloride (PVC) soft plastic curtain 4 installed on the operating side of the machine train of the twin-roll casting and rolling mill, and a memorial arch installed on the twin-roll casting and rolling mill. The electric rolling door 5 on the double-roll casting mill is sealed with a clean cloth strip (not shown) between the machine operation side and the casting roller bearing seat on the transmission side. The upper part of the cloth curtain 3 is in contact with the cover plate 1, and the lower part of the cloth curtain 3 is in contact with the ground. The upper part of the polyvinyl chloride soft plastic curtain 4 is in contact with the cover plate 1, and the lower part of the polyvinyl chloride soft plastic curtain 4 is in contact with the ground. After the electric rolling door 5 is opened, the electric rolling door 5 falls down and the bottom thereof is spaced 40 to 100 mm from the upper part of the front box. Preferably, after the electric rolling door 5 is opened, the electric rolling door 5 falls down and the bottom thereof is spaced 45 to 47 mm from the upper part of the front box.

[0045] Since there is only a wall between the static area where the smelting furnace and the static furnace are located and the casting and rolling area where the twin-roll caster is located, a large amount of dust and foreign matter will be generated in the static area where the smelting furnace and the static furnace are located during the melting, refining and slagging processes. These dust and foreign matter will float into the casting and rolling area through the gaps in the wall and the gaps in the roof. The dust outside the doors and windows of the casting and rolling area will also float into the casting and rolling area when the doors and windows are opened. The casting and rolling area itself will also produce a large amount of dust and foreign matter. If the entire twin-roll cast-rolling mill's machine array area is exposed, the above-mentioned dust and foreign matter will fall on various parts of the cast-rolling mill's array line. For example, some dust and foreign matter fall on the surface of the casting and rolling roller and are pressed into the surface or sub-surface of the slab at the moment of casting and rolling; some dust and foreign matter fall on the "upper surface of the slab between the exit roll gap of the casting and rolling roller and the winding shaft of the casting and rolling mill", and are thus rolled in (the casting and rolling mill does not coil clockwise but counterclockwise), causing damage to the interlayer plate surface, and eventually forming "holes", "pinholes", and "black lines".

[0046] Therefore, shielding and protecting the top, operating side, transmission side, coiling side, front of the casting rolls and the gaps of the bearing seats at both ends of the casting rolls in the twin-roll cast-rolling mill can prevent the entry of dust and foreign matter from the outside; at the same time, it is very critical and necessary to thoroughly clean the dust and foreign matter in various parts of the machine train itself (equivalent to cleaning before use). By installing dust-proof devices, the machine train production can be protected from dust and foreign matter to the greatest extent, reducing the probability of dust and foreign matter invading the surface of the slab; in addition, installing a transparent PVC soft plastic curtain on the operating side of the machine train is conducive to the operator to observe the operation of the strip in the machine train at all times, which is conducive to timely disposal in the event of abnormal emergencies.

[0047] Before installing the dust prevention device on the twin-roll caster, the machine column, top crossbeam, nozzle adjustment mechanism, caster arch, pressure device (pressing up device or pressing down device), casting roll rotating joint, casting roll bearing seat, lifting guide plate, flame spray lubrication guide rail, exit guide roller, pinch roller, scissors, winding guide roller and winding shaft of the twin-roll caster are cleaned, cleared and cleaned.

[0048] Before the twin-roll casting mill is used, the outlet guide roller and the winding guide roller of the twin-roll casting mill are replaced with spray guide rollers sprayed with tungsten carbide; the thickness of the tungsten carbide layer sprayed on the spray guide roller is 0.1-0.2 mm, the roughness Ra of the tungsten carbide layer sprayed on the spray guide roller is 0.02-0.15 μm, and the hardness of the tungsten carbide layer sprayed on the spray guide roller is greater than or equal to 1000 HV 300 The components and mass percentages of tungsten carbide include: W ≥ 50%, C ≥ 5%, Cr ≥ 5%, etc. Preferably, the thickness of the tungsten carbide layer sprayed by the spray guide roller is 0.15 mm, the roughness Ra of the tungsten carbide layer sprayed by the spray guide roller is 0.08 μm, and the hardness of the tungsten carbide layer sprayed by the spray guide roller is 11001000 HV 300 ; The components and mass percentages of tungsten carbide are: W 65%, C 8%, Cr 7% and 20% of other substances.

[0049] The use of sprayed guide rollers can ensure that the surface hardness of the outlet guide roller and the winding guide roller is greater than or equal to 1000HV during use. 300 , and the higher the hardness, the better the wear resistance of its surface; in order to reduce the dry friction between the exit guide roller and the winding guide roller and the slab, and reduce the shedding of aluminum powder on the slab surface, the roughness Ra of the tungsten carbide layer sprayed by the spray guide roller must be designed to be 0.02~0.15μm; and the thickness of the tungsten carbide layer sprayed by the spray guide roller is designed to be 0.1~0.2mm, which can ensure its wear resistance, and the hardness will not be low and uneven, and it can also save costs.

[0050] The inner lining of the filter box, the inner lining of the flow box, the inner lining of the front box, the inner lining of the flow channel and the casting nozzle that will be in contact with the aluminum liquid are sprayed or painted with boron nitride coating before use; the components and mass percentages of the boron nitride coating include: 26-28% hexagonal boron nitride powder, 5-9% binder, etc., and the boron nitride coating does not contain phosphate, silicate, pigment (cobalt oxide, cobalt aluminate), additives and fillers. Preferably, the components and mass percentages of the boron nitride coating are: 26.5% hexagonal boron nitride powder, 8.7% binder and the remaining other substances.

[0051] The components and mass percentages of the hexagonal boron nitride powder are: hexagonal boron nitride is greater than or equal to 99.9%, boron oxide is less than or equal to 0.1%, and hexagonal boron nitride with a particle size of 15 to 40 μm and hexagonal boron nitride with a particle size of 0.5 to 5 μm are mixed in a ratio of 1:0.1 to 1:1 to form the hexagonal boron nitride powder, and the raw material of the binder (aluminum oxide) is aluminum sol with a particle size of 3 to 40 nm. Preferably, the components and mass percentages of the hexagonal boron nitride powder are: 99.95% hexagonal boron nitride, 0.05% boron oxide, and the ratio of hexagonal boron nitride with a particle size of 15 to 40 μm to hexagonal boron nitride with a particle size of 0.5 to 5 μm is 1 to 0.5, and the raw material of the binder (aluminum oxide) is aluminum sol with a particle size of 5 to 30 nm.

[0052] By using the above-mentioned boron nitride coating, the probability of impurities of the boron nitride coating falling off on the surfaces of the lining of the filter box, the lining of the flow box, the lining of the front box, the lining of the flow channel and the casting nozzle that are in contact with aluminum water can be reduced; and improving the purity of hexagonal boron nitride can increase the service life of the boron nitride coating; and using hexagonal boron nitride of different particle sizes in combination can overcome the cracking, shedding and other phenomena caused by the mismatch of thermal expansion coefficients at high temperatures; the smaller the particle size of the aluminum sol, the larger its specific surface area, and the more excellent its dispersibility and permeability, and ultimately improve the bonding ability of hexagonal boron nitride and refractory materials during use.

[0053] Before the flow stabilizing box is used, a high-aluminum fiber blanket is used as a sealing soft connection liner for connecting the filter box and the flow stabilizing box; the components and mass percentages of the high-aluminum fiber blanket are: Al2O3 70-72%, SiO2 27-30%, CaO<0.1%, MgO<0.1%, 70-mesh slag ball<0.5%, the thickness of the high-aluminum fiber blanket is 23-28 mm, and the volume density of the high-aluminum fiber blanket is 86-110 Kg / m 3 The average tensile strength of high-aluminum fiber blanket is 80-95Kg / m 2 Preferably, the components and mass percentages of the high-aluminum fiber blanket are: Al2O3 71.5%, SiO2 28%, CaO 0.03%, MgO 0.02%, 70-mesh slag balls 0.1%, the thickness of the high-aluminum fiber blanket is 24-27 mm, and the volume density of the high-aluminum fiber blanket is 95 Kg / m 3 The average tensile strength of high aluminum fiber blanket is 87Kg / m 2 .

[0054] The production of high-aluminum fiber blankets mostly adopts the sol-gel method to prepare raw fibers, and alumina fibers are prepared through high-temperature calcination and other processes to reduce the slag ball content and increase the alumina content, which can increase the average tensile strength of the fiber, improve the ability of the fiber blanket to resist pulverization under high temperature environments, and increase the service life. During the casting and rolling production process, each batch generally produces 14 to 24 rolls continuously after the plate is erected, which is about 4.5 to 8 days. During this long period of time, the high temperature (685 to 730°C) must keep the high-aluminum fiber blanket in good operating condition and prevent abnormal shedding.

[0055] During the continuous casting and rolling process, carbon slag, aluminum powder, dust and other foreign matter at both ends of the casting rolls in the twin-roll casting and rolling mill are sucked out every hour using an industrial high-power vacuum cleaner, and the number of suction times is greater than or equal to 2 times.

[0056] During the continuous casting and rolling process, the surface of the casting roll of the twin-roll casting and rolling mill needs to be flame sprayed at all times. The combustion medium that produces the flame is liquefied petroleum gas. These liquefied petroleum gases produce a carbon layer through incomplete combustion that falls on the surface of the casting roll to play a lubricating and anti-sticking role. However, this lubrication method also has disadvantages, namely, a large amount of carbon slag will be produced at both ends of the casting roll. If these carbon slags are gathered, they may fall on the surface of the casting roll and cannot be eliminated. In addition, aluminum powder generated by dry friction between the steel exit guide roller closest to the casting roll and the slab, and dust on the outside of the bearing seat of the casting roll and other foreign matter may fall on both ends of the casting roll. Therefore, it is necessary to clean these foreign matter regularly. In this way, an industrial high-power vacuum cleaner is used to suck the two ends of the casting roll every hour.

[0057] In the related art, the defects of the casting and rolling method of aluminum foil blank are as follows:

[0058] 1. In terms of raw materials, ordinary electrolytic aluminum ingots are usually used, and the requirements for some components and mass fractions are: Mg≤0.02%, V≤0.03%; the defects are spinel defects that easily lead to the production of MgO or Al2O3*MgO during the smelting process, and easily lead to the agglomeration of V and AlTi5B1 refiner.

[0059] 2. When ordinary boron nitride coating is used for production, the role of the pigment (cobalt oxide, cobalt aluminate) is to make the parts in contact with molten aluminum, such as "the inner lining of the filter box, the inner lining of the flow box, the inner lining of the front box, the inner lining of the flow channel and the casting nozzle" appear blue after being coated or sprayed with boron nitride coating to distinguish them. However, it is essentially an impurity and will fall off and enter the aluminum melt to form slag. In addition, binders (phosphates, silicates), additives (bentonite, magnesium oxide, zinc oxide), fillers (kaolin, silicon dioxide, aluminum hydroxide, boron carbide, chromium trioxide) and the like increase the risk of falling off and forming slag for the aluminum melt.

[0060] 3. When ordinary fiber blankets are used for production, since ordinary fibers are produced by spinning or blowing, the fibers are formed with the help of compressed gas or mechanical force, resulting in uneven fiber thickness and a high slag ball content, so they are easy to fall off and enter the aluminum melt; especially between the filter box outlet and the casting nozzle inlet, once the slag balls fall off and enter the aluminum melt, they cannot be removed later.

[0061] 4. Use Grade A AlTi5B1 grain refiner and add it in the flow channel 2 to 5m away from the degassing box entrance. When the flow channel temperature is 680 to 720℃, it is easy for the refiner to not be fully dissolved due to the low temperature, and the TiB2 particles will agglomerate and form slag.

[0062] 5. Using a double-stage ceramic filter plate with a thickness of 50mm, "50ppi+60ppi" or "60ppi+60ppi" or "60ppi+70ppi", the probability of intercepting inclusions with a particle size greater than or equal to 5μm is only 70-75%. The slag is measured on the aluminum liquid at the outlet of the filter box, and the inclusion content is 0.08-0.16mm 2 / Kg; therefore, inclusions such as oxides, chlorides and nitrides with a particle size of 5 to 20 μm cannot be effectively intercepted and flow into the aluminum melt; and some old production lines have small space and no area to install additional tubular filters or deep bed filters with higher accuracy; in addition, adding tubular filters or deep bed filters will also increase production costs.

[0063] 6. In the current twin-roll casting mill, there are often some gaps above the machine column that are not covered and blocked. In addition, the top and front of the casting rolls are exposed and unprotected. When various dust foreign matters (mainly foreign matters with complex composition of elements such as Fe, Si, Na, Mg, K, Cl, F, B, O, Ti, Ca, V, C, etc.) are scattered and fallen in the areas of the casting and rolling workshop roof, the crane, and the wall near the static furnace, the dust particle counter is used to measure the area in front of the casting rolls. The result is that the foreign matter particles with a size greater than or equal to 5.0μm are 400 to 700 / m 3 , foreign particles with a size greater than or equal to 10.0 μm are 200 to 400 / m 3 When falling onto the surface of the casting roller, foreign matter will be pressed into the surface of the cast slab, destroying the continuity of the aluminum matrix and eventually forming defects such as "holes", "pinholes" and "black lines".

[0064] 7. Regarding the steel roller scratching the surface of the cast-rolled coil, since ordinary low-carbon steel is used as the guide roller, and the guide roller is not surface treated or is simply chrome-plated, the soft aluminum slab is in dry friction contact with the guide roller during long-term high-temperature use, resulting in aluminum powder adhesion to the guide roller, or the guide roller surface falling off, scratching the slab surface, and then causing aluminum powder, iron-containing debris, dust, etc. on the guide roller surface to fall off and press into the slab surface, eventually forming defects such as "holes", "pinholes", and "black lines".

[0065] 8. When the cast aluminum foil blank obtained by the related technology is further rolled to obtain a finished product with a thickness of 0.012-0.015 mm, the pinhole density is 0.2-0.3 / m after testing. 2 , black line density is 0.01~0.03 / m 2 , the length of the black line is 3 to 100 mm.

[0066] Compared with the related art, the casting and rolling method of the aluminum foil billet in this embodiment limits its raw material components, specifically limits the element Mg and the element V, and uses AlTi5B0.6 aluminum titanium boron wire as a grain refiner, and uses a double-stage foam ceramic filter plate with a thickness of 100 mm and a thickness of 60ppi and 80ppi for filtering, installs a dust prevention device on the double-roller casting and rolling mill, and sprays the surface of the casting and rolling roller. In addition, the above-mentioned other production parameters are further limited before continuous casting and rolling. The other undefined process steps adopt the conventional steps in the prior art. The cast-rolled coil for the aluminum foil billet produced by the above method has an inclusion content of 0.009-0.015mm after the aluminum liquid is filtered. 2 / Kg, and there is no obvious foreign matter pressed into the surface, no aluminum sticking and no scratch defects, and it is further rolled into a finished aluminum foil with a thickness of 0.012-0.015mm, and its pinhole density is 0.008~0.012 / m 2 , black line density is 0.0002~0.0005 / m 2 , the length of the black line is less than or equal to 3mm, thereby greatly reducing the pinhole density and black line density of the aluminum foil, and shortening the black line length of the aluminum foil. In addition, the various problems mentioned in the first to eighth aspects of the above-mentioned related technologies can be solved by defining the various condition parameters.

[0067] By the above-mentioned casting and rolling method of the present invention, the following conditions are met as an example:

[0068] In step S1, the components and mass percentages of the raw material formula are: Al, 99.790%, Si, 0.050%, Fe, 0.080%, Cu, 0.005%, Ga, 0.013%, Mg, 0.002%, Zn, 0.010%, V, 0.010%, Ti, 0.002%, and the sum of other impurity elements is 0.038%.

[0069] The temperature of the aluminum liquid in the degassing box is 721-728°C.

[0070] The microstructure of the grain refiner meets the following requirements: 2 In the longitudinal section microstructure, among single TiB2 particles, the number of TiB2 particles with a size less than or equal to 1.8μm accounts for greater than or equal to 98%, and the maximum size of the TiB2 particles is 4μm; among the agglomerated TiB2 particles, the number of agglomerated TiB2 particles with a size less than or equal to 25μm is 2, and the number of agglomerated TiB2 particles with a size greater than 25μm is 0; among the TiAl3 particles, the number of TiAl3 particles with a size less than or equal to 100μm accounts for greater than or equal to 96%, and the average size of the TiAl3 particles is 20μm, and the maximum size of a single TiAl3 particle is 150μm; the total length of oxide and salt inclusions is 750μm, and the maximum size is 300μm.

[0071] The vibration frequency of the lateral vibration device is 50 times per minute.

[0072] In step S3, the cooling water pressure of the casting roll sleeve of the twin-roll casting mill is 0.85 MPa.

[0073] After the electric rolling door is opened, the electric rolling door falls and the interval between its bottom and the upper part of the front box is 45 to 47 mm.

[0074] The thickness of the tungsten carbide layer sprayed by the spray guide roller is 0.15mm, the roughness Ra of the tungsten carbide layer sprayed by the spray guide roller is 0.08μm, and the hardness of the tungsten carbide layer sprayed by the spray guide roller is 11001000HV 300 ; The components and mass percentages of tungsten carbide are: W 65%, C 8%, Cr 7% and 20% of other substances.

[0075] The components and mass percentages of the boron nitride coating are: 26.5% of hexagonal boron nitride powder, 8.7% of a binder and the remainder being other substances.

[0076] The components and mass percentages of the hexagonal boron nitride powder are: 99.95% hexagonal boron nitride, 0.05% boron oxide, and the ratio of hexagonal boron nitride with a particle size of 15 to 40 μm to hexagonal boron nitride with a particle size of 0.5 to 5 μm is 1 to 0.5. The raw material of the binder (aluminum oxide) is aluminum sol with a particle size of 5 to 30 nm.

[0077] The components and mass percentages of the high-aluminum fiber blanket are: Al2O3 71.5%, SiO2 28%, CaO 0.03%, MgO 0.02%, 70-mesh slag ball 0.1%, the thickness of the high-aluminum fiber blanket is 24-27 mm, and the volume density of the high-aluminum fiber blanket is 95 Kg / m 3 The average tensile strength of high aluminum fiber blanket is 87Kg / m 2 .

[0078] The result is: the inclusion content of aluminum liquid after the filter box is 0.013mm 2 / Kg, the particle count in the area in front of the casting roll was 110-124 particles / m 3 , the number of dust particles with a size greater than or equal to 10.0 μm is 68 to 83 per m 3 The final pinhole density of the aluminum foil blank is 0.009 to 0.01 per m 2 The black line density of aluminum foil blank is 0.0002~0.0003pcs / m 2 , and the length of the black line is less than or equal to 3mm.

[0079] The present invention also provides another embodiment, an aluminum foil blank, which is made by the casting and rolling method of the aluminum foil blank in the above embodiment.

[0080] Since the aluminum foil blank in this embodiment is made by the casting and rolling method of the aluminum foil blank in the above embodiment, the aluminum foil blank in this embodiment can also achieve the technical effect achieved by the casting and rolling method of the aluminum foil blank in the above embodiment, which will not be elaborated here.

[0081] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A casting and rolling method for aluminum foil billet, characterized in that: The casting and rolling method of the aluminum foil blank comprises the following steps: Step S1, preparing aluminum liquid by melting, stirring, first refining, first standing, first slagging, pouring, second refining, second slagging, second standing and degassing according to the following raw material formula, and the degassing process is carried out by a degassing box; The components and mass percentages of the raw material formula are: Al≥99.700%, Si≤0.100%, Fe≤0.200%, Cu≤0.007%, Ga≤0.030%, Mg≤0.008%, Zn≤0.030%, V≤0.012%, Ti≤0.020%, the sum of other impurity elements is less than or equal to 0.300%, and the mass percentage of a single element of other impurity elements is less than or equal to 0.030%; the element Ti is configured in the form of AlTi5B0.6 aluminum titanium boron wire, and is used as a grain refiner to be fed into the inlet of the degassing box through a wire feeder in the process of degassing by a single wire. During the degassing process, the temperature of the aluminum liquid in the degassing box is 725±5°C; Step S2, filtering the aluminum liquid through a filter box; a double-stage foam ceramic filter plate with a thickness of 100 mm and a thickness of 60 ppi and 80 ppi is used for filtering, and the temperature of the aluminum liquid during filtering is 705-710° C.; Step S3, the filtered aluminum liquid is sent to a twin-roll caster through a flow stabilizing box, a flow trough, a front box and a casting nozzle in sequence for continuous casting and rolling and then coiled to obtain an aluminum foil billet; before the twin-roll caster is used, a dust prevention device of the twin-roll caster is installed, and during the continuous casting and rolling process, the casting roll surface of the twin-roll caster is continuously lubricated by flame spraying.

2. The casting and rolling method of aluminum foil billet according to claim 1, characterized in that: In the step S1, when the grain refiner is added during the degassing process, the grain refiner is vibrated by a transverse vibration device, and the vibration frequency of the transverse vibration device is 45 to 55 times per minute; the cooling water pressure of the casting roll sleeve is 0.7 to 0.9 MPa.

3. The casting and rolling method of aluminum foil billet according to claim 2, characterized in that: In step S1, the microstructure of the grain refiner meets the following requirements: 2 In the longitudinal section microstructure, among single TiB2 particles, the number of TiB2 particles with a size less than or equal to 1.8μm accounts for greater than or equal to 95%, and the maximum size of the TiB2 particles is less than or equal to 4μm; among the agglomerated TiB2 particles, the number of agglomerated TiB2 particles with a size less than or equal to 25μm is less than or equal to 3, and the number of agglomerated TiB2 particles with a size greater than 25μm is 0; among the TiAl3 particles, the number of TiAl3 particles with a size less than or equal to 100μm accounts for greater than or equal to 95%, and the average size of the TiAl3 particles is less than or equal to 25μm, and the maximum size of a single TiAl3 particle is less than or equal to 150μm; the total length of oxide and salt inclusions is less than or equal to 1000μm, and the maximum size is less than or equal to 500μm.

4. The casting and rolling method of aluminum foil billet according to claim 1, characterized in that: The inner lining of the filter box, the inner lining of the flow box, the inner lining of the front box, the inner lining of the flow channel and the casting nozzle that will be in contact with the aluminum liquid are sprayed or painted with boron nitride coating before use; the components and mass percentage of the boron nitride coating include: 26-28% hexagonal boron nitride powder, 5-9% binder, and the boron nitride coating does not contain phosphate, silicate, pigment, additive and filler.

5. The casting and rolling method of aluminum foil billet according to claim 4, characterized in that: The components and mass percentages of the hexagonal boron nitride powder are: hexagonal boron nitride is greater than or equal to 99.9%, boron oxide is less than or equal to 0.1%, and hexagonal boron nitride with a particle size of 15 to 40 μm and hexagonal boron nitride with a particle size of 0.5 to 5 μm are mixed in a ratio of 1:0.1 to 1:1 to form the hexagonal boron nitride powder, and the raw material of the binder is aluminum sol with a particle size of 3 to 40 nm.

6. The casting and rolling method of aluminum foil billet according to claim 5, characterized in that: Before the flow stabilizing box is used, a high-aluminum fiber blanket is used as a sealing soft connection liner for connecting the filter box and the flow stabilizing box; the components and mass percentages of the high-aluminum fiber blanket are: Al2O3 70-72%, SiO2 27-30%, CaO<0.1%, MgO<0.1%, 70-mesh slag ball<0.5%, the thickness of the high-aluminum fiber blanket is 23-28 mm, and the volume density of the high-aluminum fiber blanket is 86-110 Kg / m 3 The average tensile strength of high-aluminum fiber blanket is 80-95Kg / m 2 .

7. The casting and rolling method of aluminum foil billet according to claim 1, characterized in that: Before installing the dust prevention device on the twin-roll cast-rolling mill, the machine column, top crossbeam, nozzle adjustment mechanism, cast-rolling mill arch, pressure device, cast-rolling roll rotary joint, cast-rolling roll bearing seat, lifting guide plate, flame spray lubrication guide rail, exit guide roller, pinch roller, scissors, winding guide roller and winding shaft of the twin-roll cast-rolling mill are cleaned.

8. The casting and rolling method of aluminum foil billet according to claim 7, characterized in that: Before the twin-roll casting mill is used, the outlet guide roller and the winding guide roller of the twin-roll casting mill are replaced with spray guide rollers sprayed with tungsten carbide; the thickness of the tungsten carbide layer sprayed on the spray guide roller is 0.1-0.2 mm, the roughness of the tungsten carbide layer sprayed on the spray guide roller is 0.02-0.15 μm, and the hardness of the tungsten carbide layer sprayed on the spray guide roller is greater than or equal to 1000 HV 300 The components and mass percentages of tungsten carbide include: W≥50%, C≥5%, Cr≥5%.

9. The casting and rolling method of aluminum foil billet according to claim 1, characterized in that: The dust prevention device includes a cover plate integrally formed with the top of the machine train of the twin-roll casting and rolling mill, a cloth curtain installed on the transmission side and the winding side of the machine train of the twin-roll casting and rolling mill, a long and transparent polyvinyl chloride soft plastic curtain installed on the operation side of the machine train of the twin-roll casting and rolling mill, an electric rolling door installed on the memorial arch of the twin-roll casting and rolling mill, and a cloth strip sealed between the casting roller bearing seats on the operation side and the transmission side of the machine train of the twin-roll casting and rolling mill, the upper part of the cloth curtain is in contact with the cover plate, the lower part of the cloth curtain is in contact with the ground, the upper part of the polyvinyl chloride soft plastic curtain is in contact with the cover plate, the lower part of the polyvinyl chloride soft plastic curtain is in contact with the ground, and when the electric rolling door is opened, the bottom of the electric rolling door is spaced 40 to 100 mm from the upper part of the front box.

10. An aluminum foil blank, characterized in that: The aluminum foil blank is made by the casting and rolling method of the aluminum foil blank according to any one of claims 1 to 9.

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