CN110842161A - Casting method of 2-series and 7-series aluminum alloy - Google Patents
Casting method of 2-series and 7-series aluminum alloy Download PDFInfo
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- CN110842161A CN110842161A CN201911030494.7A CN201911030494A CN110842161A CN 110842161 A CN110842161 A CN 110842161A CN 201911030494 A CN201911030494 A CN 201911030494A CN 110842161 A CN110842161 A CN 110842161A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/04—Continuous casting of metals, i.e. casting in indefinite lengths into open-ended moulds
- B22D11/055—Cooling the moulds
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/001—Continuous casting of metals, i.e. casting in indefinite lengths of specific alloys
- B22D11/003—Aluminium alloys
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/16—Controlling or regulating processes or operations
- B22D11/22—Controlling or regulating processes or operations for cooling cast stock or mould
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Abstract
The invention provides a casting method of 2-series and 7-series aluminum alloy, which comprises the following steps: 1) purifying the cooling water; 2) introducing the aluminum alloy liquid into a crystallizer; 3) and introducing cooling water into the crystallizer to cool the aluminum alloy liquid. The invention supplies water by separating the pipelines used by the secondary cooling and the primary cooling, can realize differential pressure adjustment, increases the water pressure of the secondary cooling water under the condition that the water pressure of the primary cooling water is not changed, further improves the quantity of the secondary cooling water to improve the cooling effect, has unchanged integral casting speed, reduces the influence of the water pressure of the cooling water on the casting by purifying the cooling water, and can reduce the casting difficulty and improve the yield of 2-series and 7-series aluminum alloys by using the casting method.
Description
Technical Field
The invention relates to the field of aluminum alloy casting, in particular to a casting method of 2-series and 7-series aluminum alloys.
Background
When casting 2-series or 7-series aluminum alloys, the alloy strength is high, and therefore, the casting speed needs to be slowed down to prevent cracking. When the universal die plate is used for casting the alloys, waste products are easily generated, and the production is not controlled well.
Through mass retrieval, the aluminum alloy casting method in the prior art, such as the aluminum alloy die-casting die with the rapid cooling function disclosed in the publication number CN109759560A, is found to be capable of carrying out comprehensive cooling on the die, so that the cooling speed is improved, and then the die can be cooled again through the cooling fan, so that the effect of rapid cooling is achieved, the production efficiency of the casting is improved, the quality of the casting is ensured, and further, the huge economic loss caused to the die using enterprises is avoided. Or the device and the method for producing the aluminum alloy thin bar disclosed in the publication number CN102962416B are adopted, the obtained cast ingot has uniform and fine internal structure, the production cost of the aluminum alloy thin bar is greatly reduced, the casting process is stable, and the industrial continuous production of the high-quality aluminum alloy thin bar is easy to realize. Or, as disclosed in CN108568500A, the casting apparatus and method for suppressing the segregation of components of an aluminum alloy ingot can reduce the temperature of the core of the melt, increase the number of nucleation particles, reduce the depth of liquid cavities, and refine the solidification structure.
In summary, the casting method of the aluminum alloy in the prior art does not aim at the casting method of the 2-series and 7-series aluminum alloys, and the invention is specially made.
Disclosure of Invention
The invention provides a casting method of 2-series and 7-series aluminum alloy to solve the problems,
in order to achieve the purpose, the invention adopts the following technical scheme:
a method of casting a 2-series, 7-series aluminum alloy, the casting method comprising the steps of:
1) purifying the cooling water;
2) introducing the aluminum alloy liquid into a crystallizer;
3) and introducing cooling water into the crystallizer to cool the aluminum alloy liquid.
Furthermore, the crystallizer comprises a row of primary water holes uniformly and densely distributed on the upper inner side of the crystallizer in the circumferential direction and a row of secondary water holes uniformly and densely distributed on the lower inner side of the crystallizer in the circumferential direction.
Further, the step 3) specifically comprises the following steps:
3.1) carrying out primary cooling on the aluminum alloy liquid;
3.2) after the aluminum alloy liquid is stabilized, carrying out secondary cooling on the stabilized aluminum alloy liquid.
Further, the primary water hole and the secondary water hole are respectively controlled by independent valves.
Furthermore, the inclination angles of the primary water holes and the secondary water holes in the same row relative to the horizontal plane are different, and the inclination angle of the primary water hole is larger than that of the secondary water hole; and at least two primary water holes are symmetrically designed according to the center of the crystallizer.
Further, the step 1) specifically comprises the following steps:
1.1) collecting cooling water;
1.2) filtering the cooling water;
1.3) adding supplementary water;
1.4) softening the added make-up water.
The beneficial technical effects obtained by the invention are as follows:
1. the pipeline that uses through cooling the secondary and once separately supplies water, can realize differential pressure and adjust, under the unchangeable condition of primary cooling water pressure, with secondary cooling water pressure increase, and then improve secondary cooling water quantity and improve the cooling effect, and whole casting speed is unchangeable.
2. The influence of the water quality of the cooling water on the casting process is reduced by purifying the cooling water.
3. By using the casting method, the casting difficulty of the 2-series and 7-series aluminum alloys can be reduced and the yield can be improved.
Drawings
The invention will be further understood from the following description in conjunction with the accompanying drawings. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the embodiments. Like reference numerals designate corresponding parts throughout the different views.
FIG. 1 is a schematic flow chart of a method for casting a 2-series, 7-series aluminum alloy according to one embodiment of the present invention;
FIG. 2 is a schematic process flow diagram of a method for casting a 2-series or 7-series aluminum alloy according to an embodiment of the present invention;
FIG. 3 is a schematic structural diagram of a crystallizer according to one embodiment of the present invention;
FIG. 4 is a schematic structural diagram of a crystallizer according to one embodiment of the present invention before modification;
fig. 5 is a schematic diagram of a modified structure of a crystallizer according to one embodiment of the present invention.
Description of the drawings: 1-primary cooling water; 2-secondary cooling water.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to embodiments thereof; it should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. Other systems, methods, and/or features of the present embodiments will become apparent to those skilled in the art upon review of the following detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description, be within the scope of the invention, and be protected by the accompanying claims. Additional features of the disclosed embodiments are described in, and will be apparent from, the detailed description that follows.
The same or similar reference numerals in the drawings of the embodiments of the present invention correspond to the same or similar components; in the description of the present invention, it should be understood that if there is an orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", etc. based on the orientation or positional relationship shown in the drawings, it is only for convenience of describing the present invention and simplifying the description, but it is not intended to indicate or imply that the device or component referred to must have a specific orientation, be constructed in a specific orientation, and be operated, and therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and are not to be construed as limiting the present patent, and the specific meaning of the terms described above will be understood by those of ordinary skill in the art according to the specific circumstances.
The invention relates to a casting method of 2-series and 7-series aluminum alloy, which explains the following embodiments according to the description of the attached drawings:
the first embodiment is as follows:
the generation of the aluminum casting hot cracks is mainly because the shrinkage stress of the casting exceeds the bonding force among metal crystal grains, and most of metals at the cracks are usually oxidized along the grain boundaries and lose the metal luster when being observed from the cracks and fractures. The cracks extend along the grain boundary, are zigzag in shape, wide in surface and narrow in interior, and some of the cracks penetrate through the end face of the whole casting.
The tendency of cracking is different between different aluminum alloy castings because the greater the difference between the temperature at which the cast aluminum alloy begins to form a complete crystal framework during solidification and the solidification temperature, the greater the shrinkage of the alloy and the greater the tendency of cracking, and even the same alloy has different tendencies of cracking due to factors such as the resistance of the mold, the structure of the casting, and the pouring process.
In order to improve the yield, the present embodiment provides a casting method of a 2-series, 7-series aluminum alloy, the casting method including the steps of:
1) purifying the cooling water;
2) introducing the aluminum alloy liquid into a crystallizer;
3) and introducing cooling water into the crystallizer to cool the aluminum alloy liquid.
The step 1) specifically comprises the following steps:
1.1) collecting cooling water;
1.2) filtering the cooling water;
1.3) adding supplementary water;
1.4) softening the added make-up water.
The step 3) specifically comprises the following steps:
3.1) carrying out primary cooling on the aluminum alloy liquid;
3.2) after the aluminum alloy liquid is stabilized, carrying out secondary cooling on the stabilized aluminum alloy liquid.
The crystallizer comprises a row of primary water holes uniformly and densely distributed on the upper inner side of the crystallizer in the circumferential direction and a row of secondary water holes uniformly and densely distributed on the lower inner side of the crystallizer in the circumferential direction.
The primary water hole and the secondary water hole are respectively controlled by independent valves.
The primary water holes and the secondary water holes in the same row have different inclination angles relative to the horizontal plane, and the inclination angle of the primary water holes is larger than that of the secondary water holes; and at least two primary water holes are symmetrically designed according to the center of the crystallizer.
Example two:
casting begins when the dummy bar head fills and the molten metal contacts the mold walls. The height of the metal level in the crystallizer plays a major role in the thermal conductivity through the walls of the crystallizer. Other factors that affect the thermal conductivity through the walls of the crystallizer are:
condition of inner wall of crystallizer: the smoother and flatter the wall of the crystallizer, the less oxidation, the greater the heat dissipation through the wall of the crystallizer. For this reason, preferably, the upper cover of the crystallizer is designed with an independent oil cavity, and the oil cavity can continuously and automatically seep oil to the graphite lining during casting, so that the lubricating effect of the crystallizer is increased. The graphite lining is high-strength and high-toughness graphite for casting, the graphite lining is designed by taper, the taper angle range is 174-179 degrees, and the contact friction force between the aluminum alloy melt and the graphite in the casting process can be reduced. The graphite lining adopts the up-down symmetrical design, when the lower graphite is worn due to overlong casting time, the graphite can be turned over for continuous use, and the service life of the graphite can be prolonged by one time compared with the graphite adopting the asymmetrical design.
Water input mode in crystallizer: the more timely and sufficient the water input in the crystallizer is, the stronger the cooling capacity of the wall of the crystallizer is. For this purpose, a water storage cavity is preferably connected in the crystallizer, and a certain buffering time can be provided for water input.
Quality of cooling water: the chemical mass of the water causes mineral deposits in the crystallizer, which reduces heat transfer efficiency; the higher the temperature of the water, the lower the heat dissipation from the walls of the crystallizer. Therefore, it is preferable to purify the cooling water before cooling and to strictly treat the recovered cooling water for recycling, thereby ensuring that the water quality does not affect the casting.
Type of lubricating oil: the higher the heat conduction efficiency of the lubricating oil coated on the inner wall surface of the crystallizer is, the larger the heat dissipation capacity of the wall of the crystallizer is. Preferably, the lubricating oil is designed to be flowable instead of being coated in advance, so that the lubricating oil on the inner wall surface of the crystallizer can be continuously ensured not to be reduced, and the heat conduction efficiency is reduced.
Thermal conductivity of the alloy: the higher the thermal conductivity of the alloy, the greater the heat dissipation from the mold walls. Preferably, an alloy material with high heat conductivity, excellent heat conductivity, high heat resistance and high corrosion resistance is selected as a substrate of the crystallizer, so that heat can be transferred out more quickly, and meanwhile, in order to ensure that the crystallizer is not easy to deform, the crystallizer is made of high-temperature-resistant steel.
The heat lost through the crystallizer walls is very small, of the order of only 5% of the total heat lost, while direct cooling accounts for 95%. The heat dissipation through the crystallizer wall is not larger and better, the heat dissipation effect of the crystallizer wall is better, and the surface segregation layer is thicker; however, the worse the heat dissipation effect of the crystallizer wall, the more the conditions of remelting leakage and surface liquation are increased.
The primary water cooling is adopted, and the secondary water cooling is adopted to wash the surface of the aluminum alloy cast ingot formed by the aluminum alloy liquid by cooling water and take away the heat of the aluminum alloy cast ingot so as to finish the forming process. The main influence factors of the heat removal by the secondary water cooling are influenced by the following factors:
firstly, cooling water temperature;
secondly, cooling water flow;
thirdly, the uniformity of water flow distribution;
fourthly, the quality of the cooling water comprises chemical quality and cleanliness;
fifthly, water spraying angle;
and sixthly, applying a warpage reducing technology.
Therefore, in order to obtain a better cooling effect without affecting the yield of the 2-series and 7-series aluminum alloys and further increase the casting speed, the present embodiment provides a casting method of the 2-series and 7-series aluminum alloys, which comprises the following steps:
1) the cooling water is purified, so that water quality fluctuation is reduced, and the quality of the cooling water is improved;
2) introducing the aluminum alloy liquid subjected to degassing and impurity removal into a crystallizer, and starting ingot casting;
3) and introducing the purified cooling water into a crystallizer to cool the aluminum alloy liquid after degassing and impurity removal.
Furthermore, the crystallizer comprises a row of primary water holes which are uniformly and circumferentially distributed on the upper inner side of the crystallizer and a row of secondary water holes which are uniformly and circumferentially distributed on the lower inner side of the crystallizer; preferably, the water storage cavity is divided into a secondary water chamber and a primary water chamber, the secondary water hole is connected with the secondary water chamber, and the primary water hole is connected with the primary water chamber.
Further, the step 3) specifically comprises the following steps:
3.1), carrying out primary cooling on the aluminum alloy liquid, and carrying out cooling primary shaping on the aluminum alloy liquid through heat conduction of a crystallizer to form a cast ingot;
3.2) after the aluminum alloy liquid forms the ingot stably, carrying out secondary cooling on the ingot to ensure that the ingot is completely shaped.
In order to realize that primary cooling and secondary cooling do not interfere with each other, the primary water hole and the secondary water hole are controlled by independent valves respectively.
Furthermore, the inclination angles of the primary water holes and the secondary water holes in the same row relative to the horizontal plane are different, and the inclination angle of the primary water hole is larger than that of the secondary water hole; and at least two primary water holes are symmetrically designed according to the center of the crystallizer.
Further, a lower water outlet communicated with the primary water hole is positioned above the primary water hole communicated with the secondary water hole; preferably, the primary water holes and the secondary water holes are divided into two rows and are circumferentially and uniformly densely distributed on the inner wall of the crystallizer, and the design can ensure the uniformity of water flow distribution.
In order to better ensure the quality of the cooling water, the step 1) specifically comprises the following steps:
1.1) collecting and recycling the used cooling water, and collecting the cooling water through a closed cooling tower;
1.2) filtering the collected cooling water, and introducing the filtered cooling water into a clear water tank of a crystallization tank;
1.3) adding make-up water, wherein in the cooling process, a part of cooling water is inevitably consumed to reduce the total amount of the cooling water, so that the cooling water needs to be supplemented to ensure that the flow of the cooling water is not changed;
1.4) softening the added make-up water to ensure stable water quality.
Example three:
casting begins when the dummy bar head fills and the molten metal contacts the mold walls. The height of the metal level in the crystallizer plays a major role in the thermal conductivity through the walls of the crystallizer. Other factors that affect the thermal conductivity through the walls of the crystallizer are:
condition of inner wall of crystallizer: the smoother and flatter the wall of the crystallizer, the less oxidation, the greater the heat dissipation through the wall of the crystallizer. For this reason, preferably, the upper cover of the crystallizer is designed with an independent oil cavity, and the oil cavity can continuously and automatically seep oil to the graphite lining during casting, so that the lubricating effect of the crystallizer is increased. The graphite lining is high-strength and high-toughness graphite for casting, the graphite lining is designed by taper, the taper angle range is 174-179 degrees, and the contact friction force between the aluminum alloy melt and the graphite in the casting process can be reduced. The graphite lining adopts the up-down symmetrical design, when the lower graphite is worn due to overlong casting time, the graphite can be turned over for continuous use, and the service life of the graphite can be prolonged by one time compared with the graphite adopting the asymmetrical design.
Water input mode in crystallizer: the more timely and sufficient the water input in the crystallizer is, the stronger the cooling capacity of the wall of the crystallizer is. For this purpose, a water storage cavity is preferably connected in the crystallizer, and a certain buffering time can be provided for water input.
Quality of cooling water: the chemical mass of the water causes mineral deposits in the crystallizer, which reduces heat transfer efficiency; the higher the temperature of the water, the lower the heat dissipation from the walls of the crystallizer. Therefore, it is preferable to purify the cooling water before cooling and to strictly treat the recovered cooling water for recycling, thereby ensuring that the water quality does not affect the casting.
Type of lubricating oil: the higher the heat conduction efficiency of the lubricating oil coated on the inner wall surface of the crystallizer is, the larger the heat dissipation capacity of the wall of the crystallizer is. Preferably, the lubricating oil is designed to be flowable instead of being coated in advance, so that the lubricating oil on the inner wall surface of the crystallizer can be continuously ensured not to be reduced, and the heat conduction efficiency is reduced. Meanwhile, the method is a casting method of 2-series and 7-series aluminum alloys, so that more lubricating oil is needed, and the lubricating oil is about twice of that of common aluminum alloys.
Thermal conductivity of the alloy: the higher the thermal conductivity of the alloy, the greater the heat dissipation from the mold walls. Preferably, an alloy material with high heat conductivity, excellent heat conductivity, high heat resistance and high corrosion resistance is selected as a substrate of the crystallizer, so that heat can be transferred out more quickly, and meanwhile, in order to ensure that the crystallizer is not easy to deform, the crystallizer is made of high-temperature-resistant steel.
The heat lost through the crystallizer walls is very small, of the order of only 5% of the total heat lost, while direct cooling accounts for 95%. The heat dissipation through the crystallizer wall is not larger and better, the heat dissipation effect of the crystallizer wall is better, and the surface segregation layer is thicker; however, the worse the heat dissipation effect of the crystallizer wall, the more the conditions of remelting leakage and surface liquation are increased.
The primary water cooling is adopted, and the secondary water cooling is adopted to wash the surface of the aluminum alloy cast ingot formed by the aluminum alloy liquid by cooling water and take away the heat of the aluminum alloy cast ingot so as to finish the forming process. The main influence factors of the heat removal by the secondary water cooling are influenced by the following factors:
firstly, cooling water temperature;
secondly, cooling water flow;
thirdly, the uniformity of water flow distribution;
fourthly, the quality of the cooling water comprises chemical quality and cleanliness;
fifthly, water spraying angle;
and sixthly, applying a warpage reducing technology.
Therefore, in order to obtain a better cooling effect without affecting the yield of the 2-series and 7-series aluminum alloys and further increase the casting speed, the present embodiment provides a casting method of the 2-series and 7-series aluminum alloys, which comprises the following steps:
1) the cooling water is purified, so that water quality fluctuation is reduced, and the quality of the cooling water is improved;
2) introducing the aluminum alloy liquid subjected to degassing and impurity removal into a crystallizer, and starting ingot casting;
3) and introducing the purified cooling water into a crystallizer to cool the aluminum alloy liquid after degassing and impurity removal.
Furthermore, the crystallizer comprises a row of primary water holes which are uniformly and circumferentially distributed on the upper inner side of the crystallizer and a row of secondary water holes which are uniformly and circumferentially distributed on the lower inner side of the crystallizer; preferably, the water storage cavity is divided into a secondary water chamber and a primary water chamber, the secondary water hole is connected with the secondary water chamber, and the primary water hole is connected with the primary water chamber. This design can ensure the homogeneity of water distribution.
Further, the step 3) specifically comprises the following steps:
3.1), carrying out primary cooling on the aluminum alloy liquid, and carrying out cooling primary shaping on the aluminum alloy liquid through heat conduction of a crystallizer to form a cast ingot;
3.2) after the aluminum alloy liquid is stabilized to form an ingot, carrying out secondary cooling on the ingot to ensure that the ingot is completely shaped;
3.3), adding a temperature sensor on the crystallizer to monitor the water temperature of the cooling water and the temperature of the cast ingot so as to adjust the temperature when necessary.
In order to realize that primary cooling and secondary cooling do not interfere with each other, the primary water hole and the secondary water hole are controlled by independent valves respectively.
The primary water holes and the secondary water holes in the same row have different inclination angles relative to the horizontal plane, and the inclination angle of the primary water holes is larger than that of the secondary water holes.
In order to better ensure the quality of the cooling water, the step 1) specifically comprises the following steps:
1.1) collecting and recycling the used cooling water, and collecting the cooling water through a closed cooling tower;
1.2) filtering the collected cooling water, and introducing the filtered cooling water into a clear water tank of a crystallization tank;
1.3) adding make-up water, wherein in the cooling process, a part of cooling water is inevitably consumed to reduce the total amount of the cooling water, so that the cooling water needs to be supplemented to ensure that the flow of the cooling water is not changed;
1.4) softening the added make-up water, wherein the soft water has strong corrosivity to the inner surface of carbon steel of the equipment, and the main reason is that calcium and magnesium ions in the soft water are basically removed, and the water quality is not scaled but has corrosivity. Furthermore, chloride ions are a catalyst causing water corrosiveness, strongly promote and accelerate the exchange reaction of electrons on the metal surface, and are easily and preferentially adsorbed on the metal surface, particularly, at the positions where defects or weaknesses or gaps are formed on the metal surface and the small holes with concentrated stress are treated densely and reacted. Meanwhile, when the soft water is prepared by adopting the sodium ion tank process, although the hardness of the water can meet the index requirement, the total salt content is unchanged, the salt concentration in the water is high, the conductivity of the water body is also high, and the generated electrochemical corrosion is also fast. It is not negligible that the dissolved oxygen in the circulating water plays an important role in the corrosion of the metal, and it acts as a cathodic depolarizer on the surface of the corroded metal, promoting the corrosion of the metal, and can cause severe corrosion even at very low oxygen concentrations.
In order to ensure stable water quality, the following steps are required:
① selection of appropriate corrosion inhibitors
The corrosion inhibitor is added to effectively inhibit corrosion, the soft water closed-circuit corrosion inhibitor mainly comprises nitrate, chromate, phosphate, silicate, organic ammonium, molybdate and the like, because the cooling water of the crystallizer belongs to circulating cooling water with high heat flow density and local overheating, the corrosion inhibitor with a molybdate formula is selected according to the process conditions, system parameters and operation conditions of the system, the corrosion inhibitor is an anodic oxide film type corrosion inhibitor, the corrosion inhibition principle is that when carbon steel is corroded,
ferrous ions (Fe2+) are generated on the iron anode and enter the solution, under the action of oxygen, the ferrous ions are oxidized into ferric ions (Fe3+) and rapidly form a complex with molybdate anions to be attached to the surface of the carbon steel, and the corrosion resistance effect is achieved, and the reaction is as follows: the [ Fe-MoO4-Fe2O3] generated by the reaction is a passivation film with anti-corrosion performance, is tough and transparent, is insoluble in neutral and alkaline water, resists high temperature, high chlorine and high sulfate radical, and has good effect in the range of pH value of 6.5-9.5.
② passivation
Molybdate corrosion inhibitors have the advantage of inhibiting corrosion at higher temperatures and have the disadvantage that such anodic corrosion inhibitors do not function at low concentrations of the agent and, in some cases, also promote corrosion. When the cooling water system has the phenomena of high total iron content of water and yellowing of water, the system is corroded and should be passivated.
The passivation treatment is to add a large amount of corrosion inhibitor, form high-concentration molybdate ions in water to act with the contacted carbon steel, generate a layer of passivation film with the thickness of 3-30 nm on the surface of the carbon steel, protect a system from corrosion, ensure that the concentration of the medicament in the system reaches 1000ppm during passivation, and complete passivation when a tough and transparent passivation film is formed on a monitoring hanging piece.
③ maintenance of passivation film
Although the formed passivation film can play a role in preventing corrosion, the oxide film type corrosion inhibitor can be consumed in the film forming process, a medicament is still required to be added to repair the damaged oxide film after the film forming process, chloride ions, high temperature and high water flow speed can damage the oxide film, therefore, the corrosion inhibitor is continuously added in daily operation, the concentration of the medicament is required to be maintained at 200ppm in the adding amount, the role of repairing the oxide film and preventing corrosion can be achieved, and the maintenance condition of the passivation film can be mastered by monitoring the change of iron ions in circulating water every day. (ii) a
1.5) monitoring the water quality of the water purifying tank of the crystallizer:
① stably replenishing water quality:
the make-up water can bring suspended solids such as dust, spores and the like in the air into the cooling water, so that the water quality needs to be controlled, and suspended particles in the water must be removed through flocculation precipitation in case of the water quality exceeding the standard. When the turbidity in the water supplement is less than 20NTU, the water quality of the system is stable.
② management of make-up water volume of circulating water system:
according to the pollution discharge and the scientific water supplement of the water loss of the circulating water system, the stabilizing effect of the water quality can be improved. Random pollution discharge not only wastes water resources and increases the consumption of medicaments, but also aggravates equipment corrosion.
③ performing side filtration
In the running process of the system, salt and particles brought by water supplement are accumulated in the system, and the salt and the particles cause index pollutants such as the turbidity of circulating water to exceed an allowable value, so that a bypass filter facility is required to be arranged to perform bypass flow filtration treatment on the circulating cooling water so as to ensure that content indexes such as the turbidity, iron ions and the like in the circulating cooling water are kept in a specified range and keep the wall of a heat exchange pipe clean. When the side filtration amount is 3-5%, the turbidity in the water can be controlled within 10 NTU.
④ control of microorganisms
Microorganisms brought by the water supplement in the cooling water can propagate in the cooling water in a large quantity to form slime, and the sterilization algicide is added to control the breeding of bacteria and algae in the circulating water system and the harm of the slime. 90% of the water is heterotrophic bacteria, and after the sterilization algicide is added, the monitoring value of the heterotrophic bacteria number is less than 1 multiplied by 105/mL.
1.6) regulating the temperature of the water purifying tank of the crystallizer, and controlling the integral water temperature in the crystallizer to be the optimal water temperature.
The crystallizer of this application has designed two hydroeciums, and the primary water room is located the top, and the secondary water room is located the below, by the valve intercommunication between secondary water room and primary water room. When cooling water enters the crystallizer, the cooling water firstly enters the primary water chamber, if a valve between the water chambers is in an open state, the primary water and the secondary water are sprayed out from the primary water hole and the secondary water hole respectively, the primary water has a higher spray angle and is firstly contacted with the surface of the flat ingot to rebound, and a water curtain formed by the secondary water can block the rebounded primary water back to the surface of the flat ingot, so that the effect of enhancing cooling is generated; if the water valve is in a closed state, only secondary water is sprayed out, and the cooling effect is not enhanced. The core of controlling the warping of the ingot tail is to precisely control the cooling strength at a certain moment in the early casting stage. The crystallizer of this application adjusts the change of the great degree of cooling intensity through the opening of control water valve at a certain moment.
Typically, to obtain different initial cooling strengths, this is achieved by adjusting the initial cooling water flow, the opening of the water valve and the initial casting speed. The larger the initial cooling water flow is, the stronger the cooling intensity is; the greater the initial casting speed, the lower the cooling intensity; under the condition that double water injection can be met, the opening of the water valve can obviously improve the cooling strength.
In the casting starting stage, the water flow is low, the water valve is in a closed state, cooling water is sprayed out from the secondary water holes only, the cooling strength is very low, the heat of aluminum liquid is taken away mainly through the dummy ingot head and the cooling water, and a hotter starting condition is created for casting, so that the shrinkage and the warping of the flat ingot which is just solidified and formed are not obvious. With the increase of water flow and the opening of the water valve, the cooling strength begins to be obviously improved, the contraction of the slab ingot begins to be accelerated, which is represented by the rapid increase of the warping degree of the ingot tail until the formed slab ingot shell can resist the contraction stress.
For better realization control, the secondary hydroecium with first hydroecium can supply water through the pipeline of difference, and two hydroeciums realize control through different valves simultaneously, and all valves can be unified regulation and control it through control system, can also control its installation proportion and control this kind and can realize differential pressure water supply, and primary cooling water pressure is unchangeable, increases the water pressure in the pipeline alone, can improve secondary cooling water quantity, and then improves the cooling effect under the condition that does not slow down casting speed.
In summary, the present invention provides a casting method of 2-series and 7-series aluminum alloys, which can realize differential pressure adjustment by supplying water separately from a pipeline used for secondary cooling and primary cooling, increase the water pressure of the secondary cooling water under the condition that the water pressure of the primary cooling water is not changed, further increase the amount of the secondary cooling water to improve the cooling effect, and keep the casting speed unchanged, reduce the influence of the cooling water on casting by purifying the cooling water, and reduce the casting difficulty and improve the yield of the 2-series and 7-series aluminum alloys by using the casting method.
Although the invention has been described above with reference to various embodiments, it should be understood that many changes and modifications may be made without departing from the scope of the invention. That is, the methods, systems, and devices discussed above are examples. Various configurations may omit, substitute, or add various procedures or components as appropriate. For example, in alternative configurations, the methods may be performed in an order different than that described, and/or various components may be added, omitted, and/or combined. Moreover, features described with respect to certain configurations may be combined in various other configurations, as different aspects and elements of the configurations may be combined in a similar manner. Further, elements therein may be updated as technology evolves, i.e., many elements are examples and do not limit the scope of the disclosure or claims.
Specific details are given in the description to provide a thorough understanding of the exemplary configurations including implementations. However, configurations may be practiced without these specific details, e.g., well-known circuits, processes, algorithms, structures, and techniques have been shown without unnecessary detail in order to avoid obscuring the configurations. This description provides example configurations only, and does not limit the scope, applicability, or configuration of the claims. Rather, the foregoing description of the configurations will provide those skilled in the art with an enabling description for implementing the described techniques. Various changes may be made in the function and arrangement of elements without departing from the spirit or scope of the disclosure.
It is intended that the foregoing detailed description be regarded as illustrative rather than limiting, and that it be understood that it is the following claims, including all equivalents, that are intended to define the spirit and scope of this invention. The above examples are to be construed as merely illustrative and not limitative of the remainder of the disclosure. After reading the description of the invention, the skilled person can make various changes or modifications to the invention, and these equivalent changes and modifications also fall into the scope of the invention defined by the claims.
Claims (6)
1. A casting method of 2-series and 7-series aluminum alloy is characterized by comprising the following steps:
1) purifying the cooling water;
2) introducing the aluminum alloy liquid into a crystallizer;
3) and introducing cooling water into the crystallizer to cool the aluminum alloy liquid.
2. The method of claim 1, wherein the mold includes a row of primary water holes uniformly circumferentially spaced on an upper inner side of the mold and a row of secondary water holes uniformly circumferentially spaced on a lower inner side of the mold.
3. A method of casting a 2-series, 7-series aluminum alloy as claimed in any one of the preceding claims, wherein said step 3) includes the steps of:
3.1) carrying out primary cooling on the aluminum alloy liquid;
3.2) after the aluminum alloy liquid is stabilized, carrying out secondary cooling on the stabilized aluminum alloy liquid.
4. A method of casting a 2-series, 7-series aluminum alloy according to any one of the preceding claims, wherein the primary water orifice and the secondary water orifice are controlled by separate valves.
5. A method of casting a 2-series, 7-series aluminum alloy according to any one of the preceding claims, wherein the primary water holes and the secondary water holes in the same row have different inclination angles with respect to the horizontal plane, and the inclination angle of the primary water holes is greater than that of the secondary water holes; and at least two primary water holes are symmetrically designed according to the center of the crystallizer.
6. A method of casting a 2-series, 7-series aluminum alloy as claimed in any one of the preceding claims, wherein said step 1) includes the steps of:
1.1) collecting cooling water;
1.2) filtering the cooling water;
1.3) adding supplementary water;
1.4) softening the added make-up water.
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