External refining method for battery aluminum foil blank

Abstract

The invention provides an external refining method for a battery aluminum foil blank. The external refining method comprises the following steps: S1, adding a refiner; s2, rotary blowing is carried out; s3, electromagnetic purification; and S4, ultrasonic treatment. Compared with the prior art, the refining agent added in the step S1 is stirred and dispersed through the step S2, agglomeration and sedimentation of the refining agent particles are reduced, then the large-size refining agent particles are removed through the step S3, and finally the remaining small-size refining agent particles are subjected to ultrasonic crushing and dispersion through the step S4. After the four steps are carried out, the particle size distribution of the remaining refiner is more uniform, the average size is smaller, the number of particles is larger, the distribution is more dispersed, and the degree of supercooling generated under the ultrasonic cavitation effect promotes the pre-nucleation of the refiner particles. Compared with the prior art, the beneficial effects of the refiner particles are promoted, and the harmful effects of the refiner particles are avoided.

Description

Technical Field

[0001] The present invention relates to the technology of metal smelting, and specifically, to an out-of-furnace refining method for battery aluminum foil blanks. Background Art

[0002] With the development of new energy power batteries, the requirements for the strength, toughness, pinholes, etc. of battery aluminum foil are getting higher and higher.

[0003] At present, the common process flow in the battery aluminum foil industry is casting-rolling and cold rolling, that is, blanks are manufactured through the casting-rolling process, and then battery aluminum foil products are produced through cold rolling, intermediate annealing, and foil rolling. During the casting-rolling production process of aluminum foil blanks, the traditional technology is to add an aluminum-titanium-boron grain refiner with a proportion of 0.1%-0.5% into the molten aluminum online. Its generated high-melting-point fine particles such as TiB2 serve as foreign crystal nuclei during solidification, which can significantly refine the grain structure and achieve the purposes of improving strength and plasticity and reducing component segregation. A disadvantage of this technology is that only about 1% of the TiB2 particles in the added refiner play the role of effective nucleation cores, and the remaining particles do not play a role and even become harmful impurities, affecting the performance of aluminum foil.

[0004] Patent document CN104611589A (application number: 201410837629.1) discloses a method for producing double-zero aluminum foil blanks by ultrasonic casting-rolling. The method includes the following steps: 1) Melting: batching and melting according to the composition of the alloy; 2) Furnace guiding, refining in a holding furnace, filtering, and degassing; 3) Casting-rolling: A multi-stage shunt block is used at the casting nozzle of the front box for casting-rolling. The ultrasonic coupling head is inserted into the molten aluminum in the front box, and the insertion depth into the molten aluminum is 10 mm to 15 mm. The coupling head is directly opposite the casting nozzle, and then the ultrasonic generator is turned on to introduce ultrasound without adding a grain refiner. This patent provides a new idea by adding ultrasound at the position directly opposite the casting nozzle in the front box to refine grains and replace the traditional grain refiner. However, its deficiencies are as follows: First, it is necessary to insert the coupling head at the position directly opposite the casting nozzle in the front box. Since the space near the casting nozzle is limited, the coupling head will occupy the operation space, resulting in inconvenient operation. Second, the ultrasonic operation process and the coupling head maintenance process will both cause liquid level fluctuations, and the casting nozzle position has high requirements for liquid level accuracy, which is likely to interfere with production stability. Third, at present, the coupling head usually has two materials, metal and ceramic. The metal material is easily corroded by molten aluminum, so it has a short service life and will pollute the molten aluminum; the ceramic material is prone to cracking, so the power density is relatively low, and the grain refinement effect on grains is limited. Summary of the Invention

[0005] Aiming at the defects in the prior art, the purpose of the present invention is to provide an out-of-furnace refining method for battery aluminum foil blanks.

[0006] According to an out-of-furnace refining method for battery aluminum foil blanks provided by the present invention, it includes:

[0007] Step S1: Uniformly add a grain refiner 3 into the aluminum liquid chute 2 through a wire feeder 1;

[0008] Step S2: Carry out degassing using a rotary injection machine 4, and the grain refiner 3 is uniformly mixed with the aluminum liquid under the stirring action of the rotary injection machine 4;

[0009] Step S3: Remove the grain refiner particles in the aluminum liquid through an electromagnetic purification device 6;

[0010] Step S4: Crush and disperse the remaining grain refiner particles through an ultrasonic device 7.

[0011] Preferably, the step S1 includes: uniformly adding a grain refiner 3 with a proportion of 0.01% - 0.5% into the aluminum liquid chute 2 through a wire feeder 1.

[0012] Preferably, the step S2 includes: introducing an inert gas into the aluminum liquid using a rotary injection machine 4 for degassing; using the rotary shearing action of the rotary spray head component 4-1 on the rotary injection machine to break up the bubbles for degassing.

[0013] Preferably, the rotary spray head component 4-1 on the rotary injection machine is made of ceramic material, the number of rotating heads is 1 - 6, the rotation speed is adjustable from 0 - 600 rpm, and the gas flow rate is adjustable from 0 - 2.5 m 3 / h.

[0014] Preferably, the step S3 includes: removing the grain refiner particles in the aluminum liquid that meet the preset requirements by adjusting the electromagnetic purification parameters of the electromagnetic purification device 6.

[0015] Preferably, the electromagnetic purification parameters of the electromagnetic purification device 6 include: an electromagnetic purification working frequency of 8 - 15 KHz, a power of 0 - 60 KW, which can effectively remove non-metallic inclusions and grain refiner particles above 1 μm.

[0016] Preferably, the step S4 includes: further crushing and dispersing the remaining grain refiner particles under the extrusion and oscillation effects of the ultrasonic field of the ultrasonic device 7; at the same time, generating supercooling under the ultrasonic cavitation effect to pre-nucleate the grain refiner particles.

[0017] Preferably, the coupling head component 7-1 on the ultrasonic device in the ultrasonic device 7 is made of ceramic material, and the number of coupling heads is 1 - 10.

[0018] Preferably, the ultrasonic coupling head rotates circularly or swings reciprocally in the box driven by a bracket to ensure that the action range of the ultrasonic field is more uniform.

[0019] A battery aluminum foil blank according to the present invention is refined by using the above-mentioned off-furnace refining method for battery aluminum foil blanks.

[0020] Compared with the prior art, the present invention has the following beneficial effects: First, the present invention disperses the grain refiner through stirring to prevent the agglomeration and sedimentation of the grain refiner particles. Then, electromagnetic purification is used to remove the large-sized grain refiner particles. Subsequently, ultrasonic technology is adopted to ultrasonically break and disperse the remaining small-sized grain refiner particles. After these four steps, the remaining grain refiner particles have a more uniform size distribution, a smaller average size, a larger number of particles, and a more dispersed distribution. Moreover, the undercooling generated under the ultrasonic cavitation effect promotes the pre-nucleation of the grain refiner particles. Under the condition of maintaining the same addition amount of the grain refiner, the grains of the cast-rolled billet are finer and more uniform; under the condition of maintaining a comparable grain refinement effect, the addition amount of the grain refiner can be significantly reduced. The present invention not only fully promotes the beneficial effects of the grain refiner particles but also avoids their harmful effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Other features, objects, and advantages of the present invention will become more apparent by reading the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0022] Figure 1 is a schematic structural diagram of the present invention;

[0023] Among them, 1 - wire feeder; 2 - aluminum liquid flow tank; 3 - grain refiner; 4 - rotary injection machine; 4-1 - rotary spray head component on the rotary injection machine; 5 - degassing tank; 6 - electromagnetic purification equipment; 7 - ultrasonic equipment; 7-1 - coupling head component on the ultrasonic equipment.

[0024] Figure 2 is an EBSD map of the grain structure of the 1100 aluminum alloy cast-rolled billet produced by the process of Comparative Example 1 of the present invention;

[0025] Figure 3 is an EBSD map of the grain structure of the 1100 aluminum alloy cast-rolled billet produced by the process of Comparative Example 2 of the present invention; DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] The present invention will be described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several changes and improvements can still be made. These all belong to the protection scope of the present invention.

[0027] Example 1

[0028] According to an in-furnace refining method for battery aluminum foil billets provided by the present invention, as Figure 1 shown, it includes:

[0029] Step S1: Adding a grain refiner, uniformly adding the grain refiner into the aluminum liquid flow tank through a wire feeder;

[0030] Step S2: Rotary injection. While the rotary injector injects an inert gas into the molten aluminum, the bubbles are broken up by the rotary shearing action of the rotary nozzle, achieving a good degassing effect. At the same time, under the stirring action of the rotary injector, the grain refiner added in Step S1 is evenly mixed with the molten aluminum;

[0031] Step S3: Electromagnetic purification. Electromagnetic purification is a method of separating non-metallic inclusions in molten metal by using the repulsive force of an electromagnetic field on non-metallic inclusions. Traditional filtration methods rely on changing the mesh number of the filter medium to change the filtration accuracy, while electromagnetic purification can adjust the filtration accuracy by adjusting parameters such as current intensity and frequency. In the present invention, by adjusting appropriate electromagnetic purification parameters, not only micron-sized non-metallic inclusions can be removed, but also a part of the larger-sized grain refiner particles can be removed. Therefore, the large-sized grain refiner mixed into the molten aluminum in Step S2 is removed;

[0032] Step S4: Ultrasonic treatment. Under the strong "squeezing" and "violent oscillation" effects of the ultrasonic field, the remaining grain refiner particles after the treatment in Step S3 are further broken and dispersed, so that the final particle size distribution is more uniform, the number of particles is more, and the distribution is more uniform. At the same time, the supercooling generated under the ultrasonic cavitation effect promotes the pre-nucleation of the grain refiner particles, thus achieving a better refinement effect and less particle residue;

[0033] Specifically, in the said Step S1, the addition ratio of the grain refiner is 0.01%-0.5%;

[0034] Specifically, in the said Step S2, the rotary injector uses a ceramic rotary nozzle, the number of rotors is 1-6, the rotational speed is adjustable from 0 to 600 rpm, and the gas flow rate is adjustable from 0 to 2.5 m 3 / h;

[0035] Specifically, in the said Step S3, the working frequency of electromagnetic purification is 8-15 KHz, the power is adjustable from 0 to 60 KW, and non-metallic inclusions and grain refiner particles above 1 μm can be effectively removed.

[0036] Specifically, in the said Step S4, the ultrasonic coupling head is made of ceramic, the number of coupling heads is 1-10, and the coupling heads can be driven by a bracket to rotate in a cycle or swing reciprocally in the box body to ensure that the action range of the ultrasonic field is more uniform.

[0037] A battery aluminum foil blank according to the present invention is refined by using the above-mentioned off-furnace refining method for battery aluminum foil blanks.

[0038] Example 2

[0039] Example 2 is a preferred example of Example 1

[0040] An off-furnace refining method for the blank of battery aluminum foil provided by the present invention includes:

[0041] Step S1: Adding a refiner. The feeder 1 evenly adds the refiner 3 into the aluminum liquid chute 2 at a ratio of 0.15%, and the added refiner 3 is dissolved into the aluminum liquid contained in the aluminum liquid chute 2;

[0042] Step S2: Rotary spraying. The rotary spraying machine 4 drives the rotary spray head 4-1 made of ceramic material to extend into the aluminum liquid contained in the degassing box 5 and rotate at a speed of 350 rpm. Inert gas is introduced into the aluminum liquid through the rotary spray head 4-1, with a flow rate of 1.5 m 3 / h. The rotary shearing action of the rotary spray head 4-1 breaks up the bubbles, playing a good degassing role; at the same time, under the rotary stirring action of the rotary spray head 4-1 in Step S1, the dissolved refiner 3 is evenly mixed with the aluminum liquid, reducing the agglomeration and sedimentation of the refiner particles;

[0043] Step S3: Electromagnetic purification. An electromagnetic field with a frequency of 10 KHz and a power of 40 KW is introduced into the aluminum liquid through the electromagnetic purification equipment 6 to remove non-metallic inclusions larger than 1 μm in the molten metal. At the same time, if the particle diameter of the refiner 3 mixed into the aluminum liquid in Step S2 is greater than 1 μm, it will be removed;

[0044] Step S4: Ultrasonic treatment. The ultrasonic equipment 7 drives 3 coupling heads 7-1 to extend into the aluminum liquid. The ultrasonic field generated around the coupling heads 7-1 further breaks and disperses the refiner particles with a size of 1 μm and below remaining after the treatment in Step S3. At the same time, the ultrasonic equipment 7 drives the coupling heads 7-1 to perform a planar reciprocating motion, making the action range of the ultrasonic field wider and the distribution more uniform. The refiner particles have a more uniform size distribution, a larger number of particles, and are more dispersed under the action of the ultrasonic field. At the same time, the supercooling generated under the ultrasonic cavitation effect promotes the pre-nucleation of the refiner particles, thereby achieving a better refining effect and less particle residue.

[0045] Comparative Example 1: On the 1100 alloy aluminum sheet continuous casting and rolling production line, the traditional off-furnace refining process is adopted, and an aluminum-titanium-boron grain refiner with a ratio of 0.18% is added. The EBSD map of the grain structure at the center of the cross-section of the continuous casting and rolling blank is as Figure 2 shown.

[0046] Comparative Example 2: On the 1100 alloy aluminum sheet continuous casting and rolling production line, under the condition of adopting the off-furnace refining process provided by the present invention and adding an aluminum-titanium-boron grain refiner with a ratio of 0.18%, and successively passing through rotary spraying, electromagnetic purification, and ultrasonic treatment. Specifically: The rotary spraying machine 4 drives the rotary spray head 4-1 made of ceramic material to rotate at a speed of 350 rpm, and inert gas is introduced into the aluminum liquid through the rotary spray head 4-1, with a flow rate of 1.5 m 3 / h; The operating frequency of the electromagnetic purification device 6 is 10 KHz, and the power is 40 KW; While the ultrasonic device 7 drives 3 coupling heads 7-1 to extend into the molten aluminum for ultrasonic treatment, a planar reciprocating motion is performed. The EBSD map of the grain structure at the center of the cross-section of the cast-rolled blank is as Figure 3 shown, compared with Figure 2 the grain size is significantly reduced.

[0047] Comparative Example 3: On the 3102 alloy aluminum sheet casting and rolling production line, a traditional out-of-furnace refining process is adopted, and an aluminum-titanium-boron grain refiner with a proportion of 0.28% is added. The average grain size at the center of the cross-section of the cast-rolled blank reaches 130 μm.

[0048] Comparative Example 3: On the 3102 alloy aluminum sheet casting and rolling production line, under the condition of adopting the out-of-furnace refining process provided by the present invention and adding an aluminum-titanium-boron grain refiner with a proportion of 0.10%, and successively through rotary injection, electromagnetic purification, and ultrasonic treatment, specifically: The rotary injection machine 4 drives the ceramic rotary nozzle 4-1 to rotate at a speed of 350 rpm, and inert gas is introduced into the molten aluminum through the rotary nozzle 4-1, with a flow rate of 1.5 m 3 / h; The operating frequency of the electromagnetic purification device 6 is 10 KHz, and the power is 40 KW; While the ultrasonic device 7 drives 3 coupling heads 7-1 to extend into the molten aluminum for ultrasonic treatment, a planar reciprocating motion is performed. The grain size at the center of the cross-section of the cast-rolled blank reaches 127 μm.

[0049] Comparative Example 1 and Comparative Example 2 are both 1100 alloy aluminum, and the addition amount of the aluminum-titanium-boron grain refiner is also 0.18%. Since Comparative Example 2 adopted the out-of-furnace refining method provided by the present invention, the beneficial effects of the refiner particles were fully exerted, and the grain size of the cast-rolled blank was significantly reduced.

[0050] Comparative Example 3 and Comparative Example 4 are both 3102 alloy aluminum. Since Comparative Example 4 adopted the out-of-furnace refining method provided by the present invention, under the condition that the grain size of the cast-rolled blank is comparable, the addition amount of the aluminum-titanium-boron grain refiner is reduced from 0.28% in Comparative Example 3 to 0.10% in Comparative Example 4, significantly reducing the dosage of the refiner and well avoiding its harmful effects.

[0051] Research shows that the more concentrated the size distribution of the grain refiner particles, the smaller the average size, the larger the quantity, and the more dispersed the distribution, the better the grain refinement effect. In the present invention, first, through the rotational stirring action of the rotary spraying head 4-1, the molten grain refiner particles are quickly and evenly mixed with the aluminum liquid, reducing the agglomeration and sedimentation between the grain refiner particles. Then, the electromagnetic purification device 6 is used to remove the large-sized grain refiner particles, and then the ultrasonic device 7 is used to ultrasonically break and disperse the remaining small-sized grain refiner particles, so that the remaining grain refiner particles are in the optimal particle size distribution range, and the undercooling generated under the ultrasonic cavitation effect promotes the pre-nucleation of the grain refiner particles. Compared with the prior art, it not only gives full play to the beneficial effects of the grain refiner particles but also avoids their harmful effects.

[0052] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Without conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. An in-furnace refining method for battery aluminum foil blanks, characterized in that, Including Step S1: Uniformly add a grain refiner (3) into the molten aluminum launder (2) through a wire feeder (1); Step S2: Degas using a rotary injection machine (4), and the grain refiner (3) is uniformly mixed with the molten aluminum under the stirring action of the rotary injection machine (4); Step S3: Remove the grain refiner particles in the molten aluminum through an electromagnetic purification device (6); Step S4: Crush and disperse the remaining grain refiner particles through an ultrasonic device (7).

2. The method for out-of-furnace refining of battery aluminum foil blanks according to claim 1, characterized in that, The said Step S1 includes: Uniformly add a grain refiner (3) with a proportion of 0.01%-0.5% into the molten aluminum launder (2) through a wire feeder (1).

3. The method for out-of-furnace refining of battery aluminum foil billets according to claim 1, characterized in that, The said Step S2 includes: Pass an inert gas into the molten aluminum for degassing using a rotary injection machine (4); Use the rotary shearing action of the rotary nozzle component (4-1) on the rotary injection machine to break up the bubbles for degassing.

4. The method for out-of-furnace refining of battery aluminum foil blanks according to claim 3, characterized in that, The rotating spray head component (4-1) on the rotating spray blower is made of ceramic material, with the number of rotating heads being 1-6, the rotation speed being adjustable from 0 to 600 rpm, and the gas flow rate being adjustable from 0 to 2.5 m 3 / h.

5. The method for refining aluminum foil blanks for batteries outside the furnace according to claim 1, characterized in that, The said Step S3 includes: Remove the grain refiner particles in the molten aluminum that meet the preset requirements by adjusting the electromagnetic purification parameters of the electromagnetic purification device (6).

6. According to claim 5, wherein The electromagnetic purification parameters of the electromagnetic purification device (6) include: an electromagnetic purification working frequency of 8-15 KHz, a power of 0-60 KW, which can effectively remove non-metallic inclusions and grain refiner particles above 1 μm.

7. The method for refining battery aluminum foil billets outside the furnace according to claim 1, characterized in that The said Step S4 includes: Under the extrusion and oscillation effects of the ultrasonic field of the ultrasonic device (7), further crush and disperse the remaining grain refiner particles; At the same time, supercooling generated under the ultrasonic cavitation effect enables the grain refiner particles to pre-nucleate.

8. The method for refining aluminum foil blanks for batteries outside the furnace according to claim 1, characterized in that, The coupling head component (7-1) on the ultrasonic device in the said ultrasonic device (7) is made of ceramic material, and the number of coupling heads is 1-10.

9. The method for refining aluminum foil billets for batteries outside the furnace according to claim 8, characterized in that, The said ultrasonic coupling head circulates or reciprocates in the box driven by a bracket to ensure that the action range of the ultrasonic field is more uniform.

10. A battery aluminum foil blank, characterized in that, Refined by using the out-of-furnace refining method for battery aluminum foil blanks according to any one of claims 1 to 9.

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