Ultrasonic-assisted cast rolling device and application thereof

Abstract

The invention discloses an ultrasonic-assisted casting and rolling device which comprises an inclined double-roller casting and rolling machine, a casting nozzle, a front box, an ultrasonic generator, an ultrasonic transducer and an ultrasonic probe, an outlet of the casting nozzle is connected with a roller gap of the double-roller casting and rolling machine, an inlet of the casting nozzle is connected with the front box, the ultrasonic transducer is connected with the ultrasonic generator through a cable, and the ultrasonic probe is connected with the front box. The ultrasonic probe is connected with the ultrasonic transducer, and the front end of the ultrasonic probe extends into the aluminum alloy liquid of the front box and is close to an inlet of the casting nozzle. By optimizing the structure and the position of the ultrasonic probe and utilizing the high-frequency vibration and acoustic cavitation effect of high-energy ultrasonic waves, the uniformity of molten aluminum solute and temperature in a cast-rolling area is improved, the grain structure is refined, composition segregation is inhibited, edge cracks are eliminated, the problem that high-alloying and wide-width plate strips are difficult to cast and roll is solved, and the cast-rolling quality of the plate strips is improved. And the structure property uniformity of the aluminum plate strip is improved. The invention further discloses application of the ultrasonic-assisted cast-rolling device to production of aluminum alloy plates and strips.

Description

Technical Field

[0001] The invention belongs to the technical field of aluminum alloy casting and rolling, and specifically relates to an ultrasonic assisted casting and rolling device and application thereof. Background Art

[0002] Casting and rolling is to inject aluminum alloy liquid directly into the roll gap between the twin rolls of the casting and rolling machine, and solidify it into aluminum alloy strips under the cooling and pressure of the casting and rolling rolls. Aluminum alloy casting and rolling has the advantages of short process, small footprint, high efficiency and energy saving, and small investment. However, the grains of cast-rolled aluminum alloy strips are relatively coarse, the composition segregation is serious, and the edge cracking is more serious, resulting in uneven organizational properties of aluminum alloy strips, poor plasticity, poor deep drawing performance, severe cracking during deep drawing, and anisotropic performance of aluminum alloy strips, resulting in a high earing rate of deep-drawn aluminum products. When casting and rolling high-alloyed aluminum alloys, aluminum alloy liquid is easy to block the casting nozzle.

[0003] The Chinese patent document with publication number CN219503683U discloses an ultrasonic casting and rolling production device for aluminum alloy plates and strips, wherein an ultrasonic mechanism is arranged outside the casting nozzle, and the ultrasonic mechanism includes a base and a cover plate, and 3-7 ultrasonic vibrators are evenly arranged on the top surface of the cover plate, and the ultrasonic vibrators are arranged just above the cross flow channel of the casting nozzle, and the ultrasonic vibrators are electrically connected to the ultrasonic generator. The patent achieves the purpose of grain refinement by arranging multiple ultrasonic vibrators on the casting nozzle cover plate.

[0004] The Chinese patent document with publication number CN116809878A discloses a continuous casting and rolling method of aluminum alloy plates based on multi-source ultrasound-assisted quality improvement, including melting, adding refiners, degassing, slag removal, casting and rolling to obtain aluminum alloy billets, and the strengthening homogenization treatment stage includes multiple ultrasonic treatment nodes. The patent assists aluminum liquid in degassing, impurity removal, grain refinement and strengthening homogenization process by setting multiple ultrasonic rods arranged in a butterfly shape in the front box, thereby improving the problems of segregation and nozzle blockage.

[0005] The Chinese patent document with publication number CN101602095A discloses an electromagnetic field oscillation casting and rolling device and method, the device is composed of a casting and rolling machine and a pinch roll, the casting and rolling machine includes a pouring nozzle and an upper casting and rolling roll, the upper casting and rolling roll is provided with an excitation coil, and the casting nozzle is provided with an electrode. The method includes passing direct current into the excitation coil during casting and rolling to generate magnetic induction in the roll gap, passing alternating current into the pinch roll and the electrode, and improving the flowability of the melt through the action of the electromagnetic field, refining the internal structure, improving the uniformity of element distribution, and reducing the tendency of the cast and rolled billet to generate cracks.

[0006] A Chinese patent document with publication number CN102189103A discloses an integrated electromagnetic ultrasonic casting and rolling device and method for light alloys. An induction coil and an ultrasonic generator are respectively arranged on the outside and upper part of the crystallizer to generate an electromagnetic ultrasonic composite external field, thereby improving the surface and internal quality of the ingot and the plastic deformation ability of the ingot. High-quality continuously cast slabs are directly hot-rolled. Under the action of multiple rows of rollers with adjustable gaps close to the crystallizer, the ingot undergoes continuous plastic deformation, and the thickness is continuously reduced to obtain a thin plate of light alloy.

[0007] From the results of literature retrieval and production practice experience, the existing electromagnetic casting and rolling of plates and strips is difficult to achieve industrial production due to the harsh implementation conditions, complex electromagnetic casting and rolling equipment and its process. Since the end face shape of the existing ultrasonic probe is usually cylindrical, the range of action of the ultrasonic wave in the aluminum alloy liquid is small, and a single ultrasonic probe cannot meet the casting and rolling needs of high-alloy aluminum alloys and wide-width aluminum alloy plates and strips. In order to meet the casting and rolling production needs of high-alloy aluminum alloys and wide-width aluminum alloy plates and strips, the existing ultrasonic casting and rolling technology usually sets multiple ultrasonic probes on the front box or the casting nozzle, which makes the device complicated and the process control difficult, which not only increases the production cost, but also makes it difficult to achieve industrial production. Therefore, the existing aluminum alloy casting and rolling equipment and methods still need to be improved and developed. Summary of the invention

[0008] In view of the problems and shortcomings mentioned in the background technology, the present invention provides an ultrasonic assisted casting and rolling device and its application, which adopts high-energy ultrasonic wave to assist casting and rolling, and solves the problem of difficulty in casting and rolling of high-alloy aluminum alloys and wide-width plates and strips by optimizing the structure and installation position of the ultrasonic probe. The high-frequency vibration and acoustic cavitation effect of high-energy ultrasonic wave can refine the grains of aluminum alloy plates and strips, inhibit component segregation and edge cracking, and improve the uniformity of organizational composition and mechanical properties of cast-rolled aluminum plates and strips.

[0009] The technical solution adopted by the present invention to achieve the above-mentioned purpose is as follows:

[0010] The first aspect of the present invention provides an ultrasonic assisted casting and rolling device, which is characterized in that it includes an inclined twin-roll casting machine, a casting nozzle, a front box, an ultrasonic generator, an ultrasonic transducer and an ultrasonic probe, the outlet of the casting nozzle is connected to the roll gap of the twin-roll casting machine, the inlet of the casting nozzle is connected to the front box, the ultrasonic transducer is connected to the ultrasonic generator through a cable, the ultrasonic probe is connected to the ultrasonic transducer, and the front end of the ultrasonic probe extends into the aluminum alloy liquid in the front box and is close to the inlet of the casting nozzle.

[0011] Preferably, the front end of the ultrasonic probe is triangular in shape, and the width of the front end face of the ultrasonic probe is the same as the inlet width of the casting nozzle.

[0012] The front end of the existing ultrasonic probe is usually cylindrical. The ultrasonic wave is transmitted to the aluminum alloy liquid along the ultrasonic probe. Since the front end area of ​​the ultrasonic probe is small, the ultrasonic wave has a higher intensity in the aluminum alloy liquid, but the ultrasonic wave has a smaller range in the aluminum alloy liquid. In order to adapt to the casting and rolling of high-alloyed aluminum alloy and wide aluminum alloy strips, the existing ultrasonic assisted casting and rolling has to set multiple ultrasonic probes on the front box or casting nozzle to transmit the ultrasonic wave to all the aluminum alloy liquid on the front box or casting nozzle, which makes the device complicated and the process control difficult. In order to solve the problems and shortcomings existing in the existing ultrasonic casting and rolling, the present invention creatively designs the front end of the ultrasonic probe into a triangular shape, and the width of the front end face of the ultrasonic probe is the same as the inlet width of the casting nozzle. Since the front end of the ultrasonic probe becomes wider and the width is the same as the inlet width of the casting nozzle, the ultrasonic wave can be transmitted to a wider aluminum alloy liquid through the ultrasonic probe, and the front end of the ultrasonic probe is close to the inlet of the casting nozzle, so that the ultrasonic wave can be transmitted to the aluminum alloy liquid in the casting nozzle, and further transmitted to the aluminum alloy liquid between the casting and rolling rollers, so as to achieve high-frequency vibration and acoustic cavitation effects on the aluminum alloy liquid solidifying between the roller gaps, refine the grains of the cast-rolled aluminum alloy slab, inhibit component segregation, and inhibit cracking at the edge of the cast-rolled aluminum alloy slab by homogenizing the composition and temperature field, thereby solving the problem of difficulty in casting and rolling high-alloyed aluminum alloys and wide-width plates and strips.

[0013] Preferably, the thickness H of the front end face of the ultrasonic probe is 10-15 mm, and the distance between the front end face of the ultrasonic probe and the inlet of the casting nozzle is 10-20 mm, and the material of the ultrasonic probe is TC4 titanium alloy.

[0014] In order to be able to transmit the ultrasonic wave to the aluminum alloy liquid of the casting nozzle through the ultrasonic probe, and to give play to the high-frequency vibration and acoustic cavitation effect of the ultrasonic wave on the cast aluminum alloy liquid, the front end thickness of the ultrasonic probe should not exceed 15 mm, otherwise it is easy to cause the ultrasonic wave to have too wide a range of action in the aluminum alloy liquid and cause the energy loss to be too fast. The front end thickness of the preferred ultrasonic probe is 10-15 mm. The distance between the front end of the ultrasonic probe and the entrance of the casting nozzle should not exceed 20 mm. If the distance is too large, it will also cause the energy loss of the ultrasonic wave in the aluminum alloy liquid to decrease too fast. The distance between the front end of the preferred ultrasonic probe and the entrance of the casting nozzle is 10-20 mm. The material of the ultrasonic probe can be titanium alloy or stainless steel, but the stainless steel ultrasonic probe is easily corroded and melted in the aluminum alloy liquid, which causes the shape and size of the ultrasonic probe to change and lose the function of transmitting ultrasonic waves. On the other hand, the corrosion and melting of the stainless steel ultrasonic probe will also cause the content of impurity element iron in the aluminum alloy liquid to increase and reduce the purity of the aluminum alloy liquid. TC4 titanium alloy has a high melting point and is resistant to high-temperature erosion by aluminum alloy liquid. Even if slight erosion and melting occur, the titanium element will not pollute the aluminum alloy liquid, but can refine the grains of the cast-rolled aluminum alloy slab. Therefore, TC4 titanium alloy ultrasonic probe is preferred.

[0015] Preferably, the ultrasonic generator has an operating voltage of 300-400V, an operating frequency of 30-50kHz, and an operating power of 10-20kW.

[0016] In order to improve the high-frequency vibration and acoustic cavitation effect of ultrasonic waves on aluminum alloy liquid in the casting and rolling zone, refine the grain structure of cast-rolled aluminum alloy slabs, inhibit component segregation and edge cracking, improve the uniformity of the organizational composition of cast-rolled aluminum alloy strips, and solve the ultrasonic effect of high-alloy aluminum alloy, especially wide-width aluminum alloy strip casting and rolling, it is necessary to use high-energy ultrasonic waves. The working voltage of the ultrasonic generator cannot be less than 300V, the working frequency cannot be less than 30kHz, and the working power cannot be less than 10kW, otherwise the high-frequency vibration and acoustic cavitation effect of ultrasonic waves are not ideal, and the grains of cast-rolled aluminum alloy slabs cannot be effectively refined, and component segregation and edge cracking cannot be inhibited. The working voltage, frequency and power of the ultrasonic generator should not be too high, otherwise the energy consumption of the equipment will increase significantly, and the equipment cost will be too expensive, resulting in a substantial increase in production costs. The preferred working voltage of the ultrasonic generator is 300-400V, the working frequency is 30-50kHz, and the working power is 10-20kW.

[0017] The second aspect of the present invention provides an application of an ultrasonic assisted casting and rolling device, which is characterized in that the ultrasonic assisted casting and rolling device is used to cast and roll an aluminum alloy strip, and the following steps are sequentially included:

[0018] Step 1: Melt and prepare aluminum alloy liquid according to the composition and mass percentage of the aluminum alloy, and control the temperature of the aluminum alloy liquid at 720-740°C;

[0019] Step 2: using argon gas with a purity of ≥99.99% and a refining agent of 0.1-0.2% by weight of the aluminum alloy liquid to spray and refine the aluminum alloy liquid for 10-20 minutes to remove slag;

[0020] Step 3: Use a mixed gas consisting of argon gas with a purity of ≥99.99%, sulfur hexafluoride and carbon monoxide to spray and refine the aluminum alloy liquid for 10-20 minutes to remove hydrogen;

[0021] Step 4: Introduce the aluminum alloy liquid into the front box, start the ultrasonic generator, and continuously cast and roll the aluminum alloy liquid into an aluminum alloy plate and strip with a thickness of 6-8 mm under the assistance of ultrasonic waves.

[0022] The ultrasonic assisted casting and rolling device of the present invention solves the problem of difficulty in casting and rolling high-alloy aluminum alloys and wide strips, and can be applied to the production of aluminum alloys including but not limited to 1 series, 3 series, 5 series, 6 series and 8 series. Preferably, the aluminum alloy is 1235 aluminum alloy, 3004 aluminum alloy, 5052 aluminum alloy, 6016 aluminum alloy or 8011 aluminum alloy, wherein the 1235 aluminum alloy is composed of the following components in mass percentage: Si 0.18-0.22%, Fe 0.43-0.48%, Cu≤0.05%, Mn≤0.05%, Mg≤0.05%, Zn≤0.1%, Ti≤0.06%, V≤0.05%, and the balance is Al and other inevitable impurity elements, the individual content of other impurity elements is ≤0.03%, and the total amount of other impurity elements is ≤0.1%. 3004 aluminum alloy is composed of the following mass percentages: Si≤0.2%, Fe≤0.2%, Cu≤0.1%, Mn 1.05-1.1%, Mg0.85-0.9%, Zn≤0.1%, the balance is Al and other inevitable impurity elements, the individual content of other impurity elements is ≤0.05%, and the total amount of other impurity elements is ≤0.15%. 5052 aluminum alloy is composed of the following mass percentages: Si≤0.2%, Fe≤0.2%, Cu≤0.1%, Mn≤0.1%, Mg 2.43-2.48%, Cr 0.17-0.22%, Zn≤0.1%, the balance is Al and other inevitable impurity elements, the individual content of other impurity elements is ≤0.05%, and the total amount of other impurity elements is ≤0.15%. 6016 aluminum alloy is composed of the following mass percentages: Si 1.15-1.2%, Fe≤0.2%, Cu≤0.1%, Mn≤0.1%, Mg 0.38-0.42%, Cr≤0.1%, Zn≤0.1%, V 0.08-0.12%, the balance is Al and other inevitable impurity elements, the individual content of other impurity elements is ≤0.05%, and the total amount of other impurity elements is ≤0.15%. 8011 aluminum alloy is composed of the following mass percentages: Si 0.58-0.62%, Fe 0.73-0.78%, Cu≤0.1%, Mn≤0.1%, Zn≤0.1%, Ti≤0.06%, the balance is Al and other inevitable impurity elements, the individual content of other impurity elements is ≤0.05%, and the total amount of other impurity elements is ≤0.15%.

[0023] Preferably, the refining agent in step 2 is composed of the following components in mass percentage: NaCl 35.12%, NaF 19.84%, TiCl3 16.51%, SrSO4 10.06%, KPO3 11.45%, and Na2B4O7 7.02%. The preparation method of the refining agent comprises the following steps in sequence: (1) according to the composition and mass percentage of the refining agent, NaCl, NaF, TiCl3, SrSO4, KPO3, and Na2B4O7 with a purity of ≥99.8% are selected as raw materials for batching; (2) the ingredients are added into water at a temperature of 70°C and stirred to dissolve into an aqueous solution, the mass ratio of water to ingredients being 1.2, and then the aqueous solution is heated to 100°C to evaporate to obtain solid crystals; (3) the solid crystals are crushed into powders with a particle size of less than 2 mm, and the powders are dried and dehydrated at 160°C for 4 hours to obtain the refining agent.

[0024] During the smelting and preparation process, aluminum alloy liquid will inevitably be involved in slag and gas. The slag is mainly aluminum oxide, and the gas is mainly hydrogen. If the gas slag in the aluminum alloy liquid is not removed, it will be left in the aluminum alloy strip to form defects such as pores and looseness, which will not only reduce the strength and plasticity of the aluminum alloy strip, but also cause cracking during stamping. In order to improve the strength and plasticity of cast and rolled aluminum alloy strips and reduce the tendency to crack, the aluminum alloy liquid must be treated with slag and hydrogen removal.

[0025] The spray refining is to use a powder spray tank and a metal tube, use argon as a carrier, and spray the powder refining agent into the aluminum alloy liquid, so that the refining agent contacts and reacts with the aluminum alloy liquid, and the inclusions are taken out of the aluminum alloy liquid. The effect of spray refining is not only related to the purity of argon, the amount of refining agent and the spray refining time, but also closely related to the composition and preparation method of the refining agent. The components of the existing refining agent are mainly fluoride salts and chloride salts, which are directly mixed after crushing. The components of the refining agent exist independently of each other, resulting in a high melting point of the refining agent and low degassing and slag removal efficiency. In addition, the existing refining agent has a single function and does not have a refining and deterioration function. The refining agent and the deteriorating agent must be added separately, resulting in an increase in the casting and rolling production cost.

[0026] In view of the problems and shortcomings of the existing refining agents, the present invention has developed a highly efficient and multifunctional refining agent, which is prepared by a solution evaporation method, so that the components re-solidify and recrystallize to form a eutectic with a lower melting point. For example, the melting point of NaCl is 801°C, and the melting point of NaF is 993°C. After evaporation and re-solidification, the two can form a NaCl·NaF eutectic with a melting point of only 698°C. The melting point of the refining agent is greatly reduced, making it easier for the refining agent to dissolve in the aluminum alloy liquid, and enhancing the degassing and slag removal effect of the refining agent. Among them, NaCl reacts with the aluminum alloy liquid to generate AlCl3 with a boiling point of only 180°C. The AlCl3 bubbles escape from the aluminum alloy liquid by adsorbing and capturing inclusions and hydrogen during the floating process, which plays a role in degassing and slag removal. NaF molten salt can destroy the aluminum oxide film, dissolve inclusions such as aluminum oxide into the molten salt, promote the separation of inclusions from the aluminum alloy liquid, and enhance the deslag removal function of the refining agent. The Ti element generated by the reaction of TiCl3 with aluminum alloy liquid enters the aluminum alloy liquid, which can refine the grains of cast aluminum alloy strips, improve plasticity and uniformity of structure, and avoid the increase of cost by adding additional refiners. The generated AlCl3 bubbles can also absorb and capture inclusions and hydrogen during the floating process, enhancing the degassing and slag removal effect of the refining agent. The Sr and P elements generated by the reaction of SrSO4 and KPO3 with aluminum alloy liquid can refine the modified Si phase, eliminate the damage of coarse Si relative strength and plasticity, and improve the strength and plasticity of cast aluminum alloy strips. The SO2 bubbles obtained by the reaction can also absorb and capture inclusions and hydrogen, and enhance the degassing and slag removal ability of the refining agent. Na2B4O7 generates B elements by reacting with aluminum alloy liquid, which can refine the modified Fe-rich phase, eliminate the harm of coarse Fe-rich phase, and improve the strength and plasticity of cast aluminum alloy strips.

[0027] Preferably, in step three, the volume percentage of sulfur hexafluoride in the mixed gas is 9-11%, the volume percentage of carbon monoxide is 3-5%, the amount of the mixed gas is 0.5-0.6 cubic meters per minute, and the pressure of the mixed gas is 0.2-0.3 MPa.

[0028] Refining agent spray refining is mainly for slag removal. Although it also has the function of dehydrogenation, the dehydrogenation effect is limited because the refining agent inevitably contains water, which will be brought into the refining agent during spray refining, causing the aluminum alloy liquid to reabsorb hydrogen, so that the dehydrogenation is always in a dynamic equilibrium process. Usually, it is difficult to reduce the hydrogen content of the aluminum alloy liquid to below 0.1ml / 100gAl by refining agent spray refining. In order to obtain highly clean aluminum alloy liquid, it is also necessary to blow air for refining and dehydrogenation.

[0029] In the existing air blowing refining, the degassing medium blown in is mainly inert gas nitrogen or argon, or a mixture of inert gas and chlorine. Since the relative molecular mass of nitrogen, argon and chlorine is small, the gas density is small. Among them, the relative molecular mass of nitrogen is 28.01 and the density is 1.25kg / m 3The relative molecular mass of argon is 39.94 and the density is 1.78 kg / m 3 The relative molecular mass of chlorine is 70.91 and the density is 3.21kg / m 3 . This causes the bubbles to float up faster in the aluminum alloy liquid, and the contact time between the bubbles and the aluminum alloy liquid is shorter, which greatly reduces the dehydrogenation effect. In addition, although the relative density of chlorine is relatively large, chlorine is a toxic gas with a strong pungent odor, which will not only seriously corrode equipment, but also cause environmental pollution.

[0030] In view of the problems and shortcomings of the existing air blowing refining, the present invention creatively blows in a mixed gas consisting of argon with a purity of ≥99.99%, sulfur hexafluoride and carbon monoxide, wherein sulfur hexafluoride is a high-density, high-stability gas, and is non-toxic, non-combustible and non-corrosive. The relative molecular mass of sulfur hexafluoride is 146.05 and the density is 6.5kg / m 3 Adding sulfur hexafluoride to the mixed gas can significantly slow down the floating speed of bubbles in the aluminum alloy liquid, increase the contact time between the bubbles and the aluminum alloy liquid, and enable the bubbles to capture and adsorb more hydrogen and inclusions, thereby improving the degassing and slag removal effect. The purpose of adding carbon monoxide to the mixed gas is to allow carbon monoxide to capture oxygen in the aluminum alloy liquid to form carbon dioxide, prevent oxygen from forming an aluminum oxide film on the bubble surface again with aluminum, and enhance the ability of the bubbles to capture and adsorb hydrogen and inclusions. Through mixed gas refining, the hydrogen content of the aluminum alloy liquid can be reduced to below 0.1ml / 100gAl, greatly improving the cleanliness of the aluminum alloy liquid.

[0031] Preferably, the working voltage of the ultrasonic generator in step 4 is 300-400V, the working frequency is 30-50kHz, the working power is 10-20kW, the temperature of the aluminum alloy liquid in the front box is controlled at 690-710°C, and the casting speed is 700-900 mm / min.

[0032] In order to improve the high-frequency vibration and acoustic cavitation effect of ultrasonic waves on aluminum alloy liquid in the casting and rolling zone, refine the grain structure of cast and rolled aluminum alloy slabs, inhibit component segregation and edge cracking, improve the uniformity of the organizational composition of cast and rolled aluminum alloy strips, and solve the ultrasonic effect of high-alloy aluminum alloy, especially wide-width aluminum alloy strip casting and rolling, the working voltage of the ultrasonic generator cannot be lower than 300V, the working frequency cannot be lower than 30kHz, and the working power cannot be lower than 10kW, otherwise the high-frequency vibration and acoustic cavitation effect of ultrasonic waves will not be ideal. The working voltage, frequency and power of the ultrasonic generator should not be too high, otherwise the energy consumption of the equipment will be too high, the equipment cost will be too high, and the production cost will be significantly increased. In order to obtain high-quality cast-rolled aluminum alloy plates and strips, it is also necessary to reasonably control the temperature of the aluminum alloy liquid in the front box and the casting and rolling speed. When casting and rolling 1 series and 8 series low-alloyed aluminum alloys, the temperature of the aluminum alloy liquid in the front box can be lower and the casting and rolling speed can be appropriately increased. However, when casting and rolling 3 series, 5 series and 6 series high-alloyed aluminum alloys, in order to increase the fluidity of the aluminum alloy liquid and prevent the aluminum alloy liquid from clogging the casting nozzle, the temperature of the aluminum alloy liquid should be appropriately controlled at a high point, and the casting and rolling speed should not be too fast.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] (1) The present invention adopts high-energy ultrasonic wave to assist casting and rolling. By optimizing the structure of ultrasonic probe, the problem of difficulty in casting and rolling high-alloy aluminum alloy and wide-width aluminum alloy plates and strips is solved. Through the high-frequency vibration and acoustic cavitation effect of high-energy ultrasonic wave, the grains of aluminum alloy plates and strips are refined, the component segregation and edge cracking are suppressed, and the uniformity of the organizational composition and the mechanical properties of the cast-rolled aluminum alloy plates and strips are improved.

[0035] (2) The present invention significantly improves the cleanliness of the cast-rolled aluminum alloy strip by refining agent blowing refining and blowing mixed gas refining, eliminates the damage of gas slag to the mechanical properties of the cast-rolled aluminum alloy strip, and further improves the strength and plasticity of the cast-rolled aluminum alloy strip. There is no need to add additional refiners and modifiers, which reduces the production process and reduces the production cost.

[0036] (3) Compared with the existing similar cast-rolled aluminum alloy plates and strips, the tensile strength of the aluminum alloy plates and strips cast and rolled by the technical solution of the present invention is increased by more than 10%, and the elongation after fracture is increased by more than 30%, which is beneficial to improving the deep drawing performance of the aluminum alloy plates and strips, reducing the deep drawing cracking tendency and earing rate of the aluminum alloy plates and strips, and improving the qualified rate of aluminum products. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic structural diagram of the ultrasonic assisted casting and rolling device of the present invention.

[0038] Figure 2 Schematic diagram of the shape of the ultrasonic probe of the present invention.

[0039] Figure 3 Schematic diagram of the end face shape of the ultrasonic probe of the present invention.

[0040] Figure 4 This is a site photo of the ultrasonic-assisted casting and rolling of aluminum alloy strips according to the present invention.

[0041] Figure 5 This is the edge morphology of the ultrasonically assisted cast-rolled aluminum alloy strip in Example 1 of the present invention.

[0042] Figure 6 This is the edge morphology of the conventional cast-rolled aluminum alloy strip in comparative example 1. DETAILED DESCRIPTION

[0043] The technical solution of the present invention is described clearly and completely below in conjunction with the accompanying drawings and embodiments. 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.

[0044] like Figure 1 As shown, the ultrasonic assisted casting and rolling device of the present invention comprises an inclined twin-roll casting machine 1, a casting nozzle 2, a front box 3, an ultrasonic generator 4, an ultrasonic transducer 5 and an ultrasonic probe 6, wherein the outlet 21 of the casting nozzle 2 is connected to the roll gap 11 of the inclined twin-roll casting machine 1, the inlet 22 of the casting nozzle 2 is connected to the front box 3, the ultrasonic transducer 5 is connected to the ultrasonic generator 4 via a cable 7, the ultrasonic probe 6 is connected to the ultrasonic transducer 5, and the front end 61 of the ultrasonic probe 6 extends into the aluminum alloy liquid 9 in the front box 3 and is close to the inlet 22 of the casting nozzle 2. Specifically, as Figure 2 and Figure 3 As shown, the front end 61 of the ultrasonic probe 6 is triangular in shape, the end face is rectangular, the end face width W is the same as the width of the inlet 22 of the casting nozzle 2, the thickness H of the end face is 10-15 mm, the distance between the end face of the ultrasonic probe 6 and the inlet 22 of the casting nozzle 2 is 10-20 mm, and the material of the ultrasonic probe 6 is TC4 titanium alloy. In addition, the front end of the ultrasonic probe 6 can also be set to other geometric shapes, as long as the front end is ensured to be a structure that expands from the inside to the outside, and the end face width is the same as the inlet width of the casting nozzle. In this embodiment, the operating voltage of the ultrasonic generator is 300-400V, the operating frequency is 30-50kHz, and the operating power is 10-20kW. Moreover, the ultrasonic generator 4 and the ultrasonic transducer 5 are both existing products on the market, so even if their structure and principle are not described in detail, they are easy to understand for those skilled in the art.

[0045] Embodiment 1:

[0046] The 1235 aluminum alloy strip is cast and rolled by an ultrasonic assisted casting and rolling device, the end face thickness H of the ultrasonic probe is 12.5 mm, the distance between the end face of the ultrasonic probe and the casting nozzle entrance is 15 mm, and the 1235 aluminum alloy is composed of the following components by mass percentage: Si 0.19%, Fe 0.45%, Cu≤0.05%, Mn≤0.05%, Mg≤0.05%, Zn≤0.1%, Ti≤0.06%, V≤0.05%, the balance is Al and other inevitable impurity elements, the single content of other impurity elements is ≤0.03%, and the total amount of other impurity elements is ≤0.1%; the casting and rolling method comprises the following steps in sequence: step 1: smelting and preparing aluminum alloy liquid according to the composition and mass percentage of the 1235 aluminum alloy, and controlling the temperature of the aluminum alloy liquid at 730°C; step 2: using argon gas with a purity of 99.99% and a refining agent of 0.15% by weight of the aluminum alloy liquid to spray and refine the aluminum alloy liquid for 15 minutes to remove slag; step 3: using The aluminum alloy liquid is sprayed and refined with a mixed gas consisting of argon gas with a purity of 99.99%, sulfur hexafluoride and carbon monoxide for 15 minutes for dehydrogenation treatment. The volume percentage of sulfur hexafluoride in the mixed gas is 10%, the volume percentage of carbon monoxide is 4%, the amount of the mixed gas is 0.5 cubic meters per minute, and the pressure of the mixed gas is 0.2 MPa; Step 4: Introduce the aluminum alloy liquid into the front box, start the ultrasonic generator, the working voltage is 350V, the working frequency is 40kHz, and the working power is 15kW. Under the auxiliary action of ultrasonic waves, the 690°C aluminum alloy liquid is continuously cast and rolled into a 1235 aluminum alloy plate and strip with a thickness of 7 mm at a casting and rolling speed of 900 mm per minute.

[0047] Embodiment 2:

[0048] The 3004 aluminum alloy strip is cast and rolled by an ultrasonic assisted casting and rolling device, the end face thickness H of the ultrasonic probe is 15 mm, the distance between the end face of the ultrasonic probe and the casting nozzle entrance is 10 mm, and the 3004 aluminum alloy is composed of the following components in mass percentage: Si≤0.2%, Fe≤0.2%, Cu≤0.1%, Mn 1.08%, Mg 0.89%, Zn≤0.1%, the balance is Al and other inevitable impurity elements, the individual content of other impurity elements is ≤0.05%, and the total amount of other impurity elements is ≤0.15%; the casting and rolling method comprises the following steps in sequence: step 1: smelting and preparing aluminum alloy liquid according to the composition and mass percentage of the 3004 aluminum alloy, and controlling the temperature of the aluminum alloy liquid at 740°C; step 2: using argon gas with a purity of 99.99% and a refining agent with a weight of 0.2% of the aluminum alloy liquid to spray and refine the aluminum alloy liquid for 20 minutes to perform slag removal treatment; step 3: using argon gas with a purity of 99.99%, sulfur hexafluoride and monoxide to The aluminum alloy liquid is sprayed and refined with a mixed gas composed of carbon for 20 minutes to remove hydrogen. The volume percentage of sulfur hexafluoride in the mixed gas is 11%, the volume percentage of carbon monoxide is 3%, the amount of the mixed gas is 0.6 cubic meters / minute, and the pressure of the mixed gas is 0.3MPa; Step 4: Introduce the aluminum alloy liquid into the front box, start the ultrasonic generator, the working voltage is 400V, the working frequency is 50kHz, and the working power is 20kW. Under the auxiliary action of ultrasonic wave, the 700℃ aluminum alloy liquid is continuously cast and rolled into a 3004 aluminum alloy plate and strip with a thickness of 6 mm at a casting and rolling speed of 800 mm / minute.

[0049] Embodiment 3:

[0050] The 5052 aluminum alloy strip is cast and rolled using an ultrasonic assisted casting and rolling device. The end face thickness H of the ultrasonic probe is 10 mm, and the distance between the end face of the ultrasonic probe and the casting nozzle entrance is 20 mm. The 5052 aluminum alloy is composed of the following components in mass percentage: Si≤0.2%, Fe≤0.2%, Cu≤0.1%, Mn≤0.1%, Mg 2.46%, Cr 0.21%, Zn≤0.1%, the balance is Al and other inevitable impurity elements, the individual content of other impurity elements is ≤0.05%, and the total amount of other impurity elements is ≤0.15%; the casting and rolling method comprises the following steps in sequence: step 1: smelting and preparing aluminum alloy liquid according to the composition and mass percentage of 5052 aluminum alloy, and controlling the temperature of the aluminum alloy liquid at 740°C; step 2: using argon gas with a purity of 99.99% and a refining agent with a weight of 0.1% of the aluminum alloy liquid to spray and refine the aluminum alloy liquid for 10 minutes to remove slag; step 3: using argon gas with a purity of 99.99%, sulfur hexafluoride and monoxide The aluminum alloy liquid is sprayed and refined with a mixed gas composed of carbon for 20 minutes to remove hydrogen. The volume percentage of sulfur hexafluoride in the mixed gas is 11%, the volume percentage of carbon monoxide is 3%, the amount of the mixed gas is 0.6 cubic meters / minute, and the pressure of the mixed gas is 0.3MPa; Step 4: Introduce the aluminum alloy liquid into the front box, start the ultrasonic generator, the working voltage is 350V, the working frequency is 40kHz, and the working power is 15kW. Under the auxiliary action of ultrasonic wave, the aluminum alloy liquid at 710℃ is continuously cast and rolled into 5052 aluminum alloy plates and strips with a thickness of 8 mm at a casting and rolling speed of 700 mm / minute.

[0051] Embodiment 4:

[0052] The 6016 aluminum alloy strip is cast and rolled using an ultrasonic assisted casting and rolling device. The end face thickness H of the ultrasonic probe is 12.5 mm, and the distance between the end face of the ultrasonic probe and the casting nozzle entrance is 15 mm. The 6016 aluminum alloy is composed of the following mass percentages: Si 1.18%, Fe≤0.2%, Cu≤0.1%, Mn≤0.1%, Mg 0.38%, Cr≤0.1%, Zn≤0.1%, V0.08-0.12%, the balance is Al and other inevitable impurity elements, the individual content of other impurity elements is ≤0.05%, and the total amount of other impurity elements is ≤0.15%; the casting and rolling method comprises the following steps in sequence: step 1: smelting and preparing aluminum alloy liquid according to the composition and mass percentage of 6016 aluminum alloy, and controlling the temperature of the aluminum alloy liquid at 740°C; step 2: using argon gas with a purity of 99.99% and a refining agent with a weight of 0.1% of the aluminum alloy liquid to spray and refine the aluminum alloy liquid for 10 minutes to remove slag; step 3: using argon gas with a purity of 99.99% The aluminum alloy liquid is sprayed and refined with a mixed gas consisting of sulfur hexafluoride and carbon monoxide for 20 minutes for dehydrogenation treatment. The volume percentage of sulfur hexafluoride in the mixed gas is 11%, the volume percentage of carbon monoxide is 3%, the amount of the mixed gas is 0.6 cubic meters per minute, and the pressure of the mixed gas is 0.3 MPa; Step four: introduce the aluminum alloy liquid into the front box, start the ultrasonic generator, the working voltage is 350V, the working frequency is 40kHz, and the working power is 15kW. Under the auxiliary action of ultrasonic wave, the aluminum alloy liquid at 705°C is continuously cast and rolled into a 6016 aluminum alloy plate and strip with a thickness of 8 mm at a casting and rolling speed of 750 mm per minute.

[0053] Embodiment 5:

[0054] An ultrasonic-assisted rolling device is used to roll an 8011 aluminum alloy strip, the end face thickness H of the ultrasonic probe is 12.5 mm, the distance between the end face of the ultrasonic probe and the casting nozzle entrance is 15 mm, and the 8011 aluminum alloy is composed of the following components in mass percentage: Si 0.59%, Fe 0.75%, Cu≤0.1%, Mn≤0.1%, Zn≤0.1%, Ti≤0.06%, and the balance is Al and other inevitable impurity elements, the individual content of other impurity elements is ≤0.05%, and the total amount of other impurity elements is ≤0.15%; the rolling method comprises the following steps in sequence: step 1: smelting and preparing aluminum alloy liquid according to the composition and mass percentage of the 8011 aluminum alloy, and controlling the temperature of the aluminum alloy liquid at 720°C; step 2: using argon gas with a purity of 99.99% and a refining agent with a weight of 0.15% of the aluminum alloy liquid to spray and refine the aluminum alloy liquid for 15 minutes to remove slag; step 3: using a refining agent with a purity of 99.99 The aluminum alloy liquid is sprayed and refined with a mixed gas composed of % argon, sulfur hexafluoride and carbon monoxide for 10 minutes to remove hydrogen. The volume percentage of sulfur hexafluoride in the mixed gas is 9%, the volume percentage of carbon monoxide is 5%, the amount of the mixed gas is 0.5 cubic meters / minute, and the pressure of the mixed gas is 0.2MPa; Step 4: The aluminum alloy liquid is introduced into the front box, and the ultrasonic generator is started with a working voltage of 300V, a working frequency of 30kHz, and a working power of 10kW. Under the auxiliary action of ultrasonic wave, the aluminum alloy liquid at 695°C is continuously cast and rolled into 8011 aluminum alloy plates and strips with a thickness of 7 mm at a casting and rolling speed of 850 mm / minute.

[0055] The refining agent used in step 2 of Examples 1-5 of the present invention is composed of the following components in percentage by mass: NaCl 35.12%, NaF 19.84%, TiCl 3 16.51%, SrSO 4 10.06%, KPO 3 11.45%, Na 2 B 4 O 7 7.02%. The preparation method of the refining agent comprises the following steps in sequence:

[0056] (1) According to the composition and mass percentage of the refining agent, NaCl, NaF, TiCl3, SrSO4, KPO3, and Na2B4O7 with a purity of 99.8% are selected as raw materials for batching; (2) the ingredients are added into water at a temperature of 70° C. and stirred to dissolve into an aqueous solution, wherein the mass ratio of water to the ingredients is 1.2, and then the aqueous solution is heated to 100° C. to evaporate and obtain solid crystals; (3) the solid crystals are crushed into powders with a particle size of less than 2 mm, and the powders are dried and dehydrated at 160° C. for 4 hours to obtain the powder refining agent.

[0057] Comparative Example 1:

[0058] In this comparative example, conventional casting and rolling equipment is used to cast and roll 1235 aluminum alloy plates and strips. The composition, mass percentage and steps of the 1235 aluminum alloy are the same as those in Example 1, except that the casting and rolling equipment used is not equipped with an ultrasonic generator, and the aluminum alloy liquid in step four is directly cast and rolled into 1235 aluminum alloy plates and strips without the assistance of ultrasonic waves.

[0059] Comparative Example 2:

[0060] In this comparative example, an ultrasonic-assisted casting and rolling device is used to cast 3004 aluminum alloy plates and strips. The composition, mass percentage and steps of the 3004 aluminum alloy are the same as those in Example 2, except that the working voltage of the ultrasonic generator in step four is 300V, the working frequency is 30kHz, and the working power is 5kW.

[0061] Comparative Example 3:

[0062] In this comparative example, an ultrasonic-assisted casting and rolling device is used to cast and roll 5052 aluminum alloy plates and strips. The composition, mass percentage and steps of the 5052 aluminum alloy are the same as those in Example 3, except that the refining agent used in step 2 is a commercially available conventional powder refining agent, and the powder refining agent is composed of the following components in mass percentage: NaCl 36.13%, KCl 15.42%, CaF216.84%, NaF19.24%, and C2Cl6 12.37%. The powder refining agent is obtained by directly mixing the raw materials after crushing.

[0063] Comparative Example 4:

[0064] In this comparative example, an ultrasonic-assisted casting and rolling device is used to cast and roll 6016 aluminum alloy plates and strips. The composition, mass percentage and steps of the 6016 aluminum alloy are the same as those in Example 4, except that the degassing medium blown in in step three is argon with a purity of 99.99%, rather than a mixed gas consisting of argon with a purity of 99.99%, sulfur hexafluoride and carbon monoxide.

[0065] Verification example:

[0066] Figure 4 This is a scene photo of ultrasonic-assisted casting and rolling of aluminum alloy strip. Figure 5 This is the edge morphology of the ultrasonically assisted cast-rolled 1235 aluminum alloy strip in Example 1. Figure 6 This is the edge morphology of the conventional cast-rolled 1235 aluminum alloy strip in comparative example 1. Figure 5 It can be seen that the edges of the ultrasonic-assisted cast-rolled 1235 aluminum alloy strip are flat and smooth, with no edge cracks. Figure 6It can be seen that, when conventional casting and rolling equipment is used and ultrasonic wave assisted casting and rolling is not applied, obvious cracks exist at the edges of the cast and rolled 1235 aluminum alloy strip. By comparison, it can be seen that the present invention adopts ultrasonic wave assisted casting and rolling, and improves the uniformity of the solute and temperature field of the aluminum alloy liquid in the casting and rolling zone through the high-frequency vibration and acoustic cavitation effect of ultrasonic wave, refines the grain structure, and can effectively inhibit the cracks from occurring at the edges of the cast and rolled aluminum alloy strip, thereby improving the yield rate of the cast and rolled aluminum alloy strip.

[0067] The hydrogen content and slag content of the aluminum alloy liquid in the front box in Example 1, Example 2, Comparative Example 3 and Comparative Example 4 were tested on site using a hydrogen meter and a slag meter. The results are shown in Table 1. As can be seen from Table 1, the hydrogen content of the aluminum alloy liquid in Example 1 and Example 2 is less than 0.1 ml / 100 gAl, and the slag content is less than 0.05 mm 2 / kgAl. Since the refining agent used in Comparative Example 3 is a conventional refining agent available on the market, and since no mixed gas consisting of argon, sulfur hexafluoride and carbon monoxide is blown into Comparative Example 4, but only argon is blown into the refining, the hydrogen slag content of the aluminum alloy liquid before casting in Comparative Example 3 and Comparative Example 4 is relatively high. By comparison, it can be seen that the use of the technical solution of the present invention can significantly reduce the gas slag content of the aluminum alloy liquid before casting and improve the cleanliness of the aluminum alloy liquid.

[0068] Table 1 Hydrogen content and slag content of aluminum alloy liquid before casting and rolling

[0069] Hydrogen content / (ml / 100gAl) <![CDATA[Sludge content / (mm 2 / kg Al)]]> Example 1 0.091 0.045 Example 2 0.088 0.042 Comparative Example 3 0.155 0.079 Comparative Example 4 0.182 0.065

[0070] Samples were taken from the aluminum alloy strips obtained in Examples 1-5 and Comparative Examples 1-4 to test the room temperature tensile mechanical properties of the aluminum alloy strips, and the results are shown in Table 2. As can be seen from Table 2, the aluminum alloy strips of Examples 1-5 have higher tensile strength and elongation after fracture. Comparative Example 1 uses a conventional casting device and does not apply ultrasonic assisted casting and rolling, Comparative Example 2 has an ultrasonic generator with a working power of 5kW, Comparative Example 3 uses a commercially available conventional refining agent for spray refining, and Comparative Example 4 only uses argon gas for refining, resulting in the tensile strength and elongation after fracture of the aluminum alloy strips of Comparative Examples 1-4 being lower than the tensile strength and elongation after fracture of the same aluminum alloy strips of Examples 1-4. Through comparison, it can be seen that the present invention uses high-energy ultrasonic wave to assist casting and rolling, and uses the high-frequency vibration and acoustic cavitation effect of ultrasonic wave to refine grains and inhibit component segregation, and improves the cleanliness of aluminum alloy liquid through refining and purification, thereby greatly improving the strength and plasticity of cast-rolled aluminum alloy plates and strips, especially the significant improvement in plasticity, which can greatly improve the deep drawing performance of cast-rolled aluminum alloy plates and strips, prevent cracking during deep drawing, and reduce the earing rate of deep-drawn aluminum products.

[0071] Table 2 Room temperature tensile mechanical properties of aluminum alloy strips

[0072]

[0073]

Claims

1. An ultrasonic assisted casting and rolling device, It is characterized in that The invention comprises an inclined twin-roll casting machine (1), a casting nozzle (2), a front box (3), an ultrasonic generator (4), an ultrasonic transducer (5) and an ultrasonic probe (6); the outlet (21) of the casting nozzle (2) is connected to the roll gap (11) of the inclined twin-roll casting machine (1); the inlet (22) of the casting nozzle (2) is connected to the front box (3); the ultrasonic transducer (5) is connected to the ultrasonic generator (4) via a cable (7); the ultrasonic probe (6) is connected to the ultrasonic transducer (5); and the front end (61) of the ultrasonic probe (6) extends into the aluminum alloy liquid (9) of the front box (3) and is close to the inlet (22) of the casting nozzle (2).

2. The ultrasonic assisted casting and rolling device according to claim 1, It is characterized in that The front end (61) of the ultrasonic probe (6) is triangular in shape, and the width of the front end face of the ultrasonic probe (6) is the same as the width of the inlet (22) of the casting nozzle (2).

3. The ultrasonic assisted casting and rolling device according to claim 1, It is characterized in that The thickness H of the front end face of the ultrasonic probe (6) is 10-15 mm, and the distance between the front end face of the ultrasonic probe (6) and the inlet (22) of the casting nozzle (2) is 10-20 mm. The material of the ultrasonic probe (6) is TC4 titanium alloy.

4. The ultrasonic assisted casting and rolling device according to claim 1, It is characterized in that The ultrasonic generator (4) has an operating voltage of 300-400V, an operating frequency of 30-50kHz, and an operating power of 10-20kW.

5. An application of an ultrasonic assisted casting and rolling device, wherein the ultrasonic assisted casting and rolling device as claimed in any one of claims 1 to 4 is used to cast and roll an aluminum alloy strip. It is characterized in that The following steps are included in sequence: Step 1: Melt and prepare aluminum alloy liquid according to the composition and mass percentage of the aluminum alloy, and control the temperature of the aluminum alloy liquid at 720-740°C; Step 2: using argon gas with a purity of ≥99.99% and a refining agent of 0.1-0.2% by weight of the aluminum alloy liquid to spray and refine the aluminum alloy liquid for 10-20 minutes to remove slag; Step 3: Use a mixed gas consisting of argon gas with a purity of ≥99.99%, sulfur hexafluoride and carbon monoxide to spray and refine the aluminum alloy liquid for 10-20 minutes to remove hydrogen; Step 4: Introduce the aluminum alloy liquid into the front box, start the ultrasonic generator, and continuously cast and roll the aluminum alloy liquid into an aluminum alloy plate and strip with a thickness of 6-8 mm under the assistance of ultrasonic waves.

6. Application of the ultrasonic assisted casting and rolling device according to claim 5, It is characterized in that The aluminum alloy is 1235 aluminum alloy, 3004 aluminum alloy, 5052 aluminum alloy, 6016 aluminum alloy or 8011 aluminum alloy.

7. Application of the ultrasonic assisted casting and rolling device according to claim 5, It is characterized in that The refining agent in step 2 is composed of the following components in mass percentage: NaCl 35.12%, NaF 19.84%, TiCl 3 16.51%, SrSO 4 10.06%, KPO 3 11.45%, Na 2 B 4 O 7 7.02%.

8. Application of the ultrasonic assisted casting and rolling device according to claim 5 or 7, It is characterized in that The preparation method of the refining agent in step 2 comprises the following steps in sequence: (1) selecting NaCl, NaF, TiCl with a purity of ≥ 99.8% according to the composition and mass percentage of the refining agent; 3 、SrSO 4 , KPO 3 、Na 2 B 4 O 7 The invention relates to a method for preparing raw materials; (2) adding the ingredients into water at a temperature of 70° C. and stirring to dissolve the ingredients into an aqueous solution, wherein the mass ratio of water to the ingredients is 1.2, and then heating the aqueous solution to 100° C. to evaporate the aqueous solution to obtain solid crystals; (3) crushing the solid crystals into powders with a particle size of less than 2 mm, and drying and dehydrating the powders at 160° C. for 4 hours to obtain the refining agent.

9. Application of the ultrasonic assisted casting and rolling device according to claim 5, It is characterized in that In step 3, the volume percentage of sulfur hexafluoride in the mixed gas is 9-11%, the volume percentage of carbon monoxide is 3-5%, the amount of the mixed gas is 0.5-0.6 cubic meters per minute, and the pressure of the mixed gas is 0.2-0.3 MPa.

10. Application of the ultrasonic assisted casting and rolling device according to claim 5, It is characterized in that The working voltage of the ultrasonic generator described in step 4 is 300-400V, the working frequency is 30-50kHz, the working power is 10-20kW, the temperature of the aluminum alloy liquid in the front box is controlled at 690-710°C, and the casting speed is 700-900 mm / min.

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