JP2008502483A - Aluminum and / or aluminum alloy casting method and facility - Google Patents

Abstract

Al and Al alloy casting process in which the Al melt is added to at least one casting station (33, 34) where the melt is cast to a semifinished product. In adding the Al melt to the casting station a number of ladles (25) are used, into which the melt is filled, transported and treated in a further step (32) and finally fed to casting stations 33 or 34 with removal of the ladles. An independent claim is included for a casting unit as described above.

Description

  The present invention relates to a method for casting aluminum and / or aluminum alloy according to the generic term of claim 1, and also to a casting machine for carrying out the method.

  Casting methods and casters for aluminum and / or aluminum alloys are known in the art, where solid or liquid aluminum is melted in a melting furnace and then retained in a smelting furnace, from which molten aluminum flows into a long channel After that, it flows to the casting station and as a result, receives various treatments. In this way, alloy additives are added to the molten aluminum flowing along the flow path, and before the melting, an inert purge gas is injected through the filter, and when it reaches the casting station, it is cast into a semi-finished product (usually The outline of the aluminum casting machine is shown in FIG. 1). The possibility of homogenizing molten aluminum is limited. The processing time is related to the casting process and is therefore predetermined and limited with respect to time.

  The individual processing stations must be fully coordinated with each other. Even if one of the stages of this inline casting machine does not function, the entire casting machine must be stopped. If the flow path through which the molten aluminum flows is long, the temperature will drop and the material must be heated in the smelting furnace so that a sufficient temperature can be reached upon arrival at the casting station. The long casting time means that a melting furnace or smelting furnace must be available for the entire casting time before the next batch of molten aluminum is used. Also, the energy consumption of the furnace increases correspondingly. Usually, the use of a reflective furnace with hydrocarbon fuels has the disadvantage of rapid absorption of hydrogen from the burner flame. In addition, greenhouse gases and other pollutants are created that burden the atmosphere. On the other hand, the fact that the molten aluminum flows through the long open flow path means that the molten aluminum absorbs hydrogen from the atmosphere and generates scale.

  The object of the present invention is to propose a more economical and more flexible casting method of aluminum and / or aluminum alloy, and also to carry out this method to obtain an optimal period for the treatment and casting of molten aluminum. Resulting in a casting machine that enables the production of semi-finished products of improved quality.

  This object is achieved according to the invention by a casting method comprising the features of claim 1 and a casting machine comprising the features of claim 13.

  The desired improvement of the casting method according to the invention and the desired improvement of the casting machine according to the invention constitute the content of the dependent claims.

  By utilizing the ladle according to the invention, this stage of the method is separated in time from the actual casting process by treating the molten aluminum in a controllable sequence and possibly feeding it to several casting stations. . Individual treatments are no longer fixed and subject to time restrictions, but if necessary, adapt until the desired quality of the molten aluminum to be cast is achieved in the associated ladle Is possible.

  The method according to the invention no longer requires a large smelting furnace and is therefore much more efficient than the in-line method. When used, these furnaces are used for melting and heating, but not for long-term insulation. They can take the form of induction furnaces that are energy efficient and advantageous for the environment.

  Next, the present invention will be described in further detail using the drawings.

  FIG. 1 shows a state-of-the-art casting machine 1 for aluminum and / or aluminum alloys. Liquid or solid aluminum is introduced as a base material into a first stage or station 2 including a melting furnace 3 and a smelting furnace 4 attached thereto. For example, aluminum can be supplied from the pot room using the conveying ladle 5 or as a waste batch. The furnaces 3 and 4 are usually large-scale reflection furnaces that use hydrocarbon fuel. Molten aluminum generated in the melting furnace 3 is heated to a necessary temperature in the refining furnace 4 and partially homogenized by stirring.

  When the molten aluminum reaches the required temperature, it is led from the smelting furnace 4 to the casting station 7 via the long flow path 6, so that the second of the casting machine 1 with the filter 13 connected upstream of the casting station 7. Pass through various processing stations 11, 12 that form a stage 10. At the processing station 11, various alloy additives are added to the molten aluminum. In the processing station 12, gas purification is performed.

  The casting station 7 where the molten aluminum is cast into a semi-finished product can be operated continuously or semi-continuously in a manner known in the art, and therefore no further details will be refrained.

  The processing period in the second stage 10 is related to the casting process carried out in the casting station 7 and is therefore predetermined and subject to limitations. The individual processing stations 11, 12 must be perfectly synchronized with each other with regard to their function. If one of the stages of this in-line casting machine does not work, the entire casting machine 1 must be stopped. If the flow path through which the molten aluminum flows is long, the temperature will drop and the material will be overheated in the smelting furnace so that a sufficient temperature (eg 700 ° C.) can be reached upon arrival at the casting station 7. Must be present (eg, up to 730 ° C.). A long casting time means that the melting and smelting furnace 4 must be available for the entire casting time before the next batch of molten aluminum is used. The energy consumption of the furnaces 3 and 4 increases accordingly.

  In the case of reverberatory furnaces with hydrocarbon fuels, the disadvantage of rapid absorption of hydrogen from the burner flame arises. In addition, greenhouse gases and other pollutants that burden the atmosphere are also generated. On the other hand, the fact that the molten aluminum flows through the long open channel 6 also means that the molten aluminum absorbs hydrogen from the atmosphere and generates scale.

  FIG. 2 shows a schematic view of an aluminum and / or aluminum alloy casting machine 1 according to the invention. The first stage of the casting process according to the invention takes place at the filling station 21 where hot molten aluminum is poured into several ladles 25. The capacity of the ladle is, for example, 15t. Use a transfer ladle to allow hot (approximately 900 ° C.) liquid aluminum from the pot room to be poured directly into the ladle 25, or at least one, preferably several Assign furnaces 22, 23, 24 to filling station 21 to be responsible for the distribution of molten aluminum so that not only liquid aluminum but also scrap aluminum or ingots supplied for recast serve as the base material It is possible to do so. Molten aluminum can be poured into one of the ladle 25, for example, at half-hour intervals. Conveniently, it is possible to inject ladle 25 of different qualities (different aluminum purity) from the individual furnaces into the ladle 25, so that the ladle, if possible, to each ladle It is possible to control the filling of the mixed material from different furnaces 22, 23, 24.

  As the furnaces 22, 23, 24, it is desirable to be able to use an electric induction furnace that is considerably more energy efficient than the reflection furnace. These can be, for example, induction furnaces with a capacity of 20 t, from each of which 15 t of molten aluminum is poured into a ladle and the remaining 5 t can be used for further charge melting. Is possible.

  The casting machine 1 according to the invention comprises a purification and preparation station 30 from which the cleaned and preheated ladle 25a is transported to the filling station 21 and filled (in FIG. The pan 25 is indicated schematically by the letter T). For example, by preheating ladle 25 to 900 ° C., molten aluminum injected from furnaces 22, 23, 24 operated at a temperature of about 800 ° C. would be typical without preheating. It is possible to stay in the ladle 25 for a longer period of time until the casting temperature drops to 700 ° C.

  When each ladle 25 is filled, the ladle is tilted and the scale is removed from the surface of the molten bath (scale removal).

  The ladle 25 filled at the filling station 21 is conveyed to the processing station 32 and the second stage of the casting process is performed. First, an alloy additive is added to the molten aluminum (see ladle represented by 25b in FIG. 2). (However, it is possible to first put at least a portion of the alloy additive into the cleaned ladle 25a before pouring into the molten aluminum.) Thereafter, the molten aluminum is homogenized and purified ( (See ladle 25c). For this reason, the ladle is arranged below the rotary impeller that can be immersed in each ladle 25c, for example, injecting an inert gas such as argon or nitrogen, resulting in the removal of bonded hydrogen from the molten aluminum, Homogenization and / or temperature control can be performed. Injecting argon eliminates the absorption of hydrogen from the moisture contained in the atmosphere and reduces scale formation. A small amount of chlorine can be added to the purge gas to remove trace alkali contaminants.

  After treatment of the molten aluminum, the ladle 25 can be stored in a storage station provided for storage until the casting station 33 or 34 is available (FIG. 2 shows such storage). The station is schematically indicated by the letter S). The casting machine 20 preferably comprises several such casting stations (two are shown in FIG. 2), capable of transporting the ladle 25 from the processing or storage station to the casting station, Molten aluminum is cast into semi-finished products at a casting station.

  It is advantageous to maintain the temperature of the molten aluminum by covering the ladle 25 with a lid.

  During the time spent at the storage station S, the temperature in the ladle 25 can be lowered by pouring argon through a perforated plug at the bottom of the ladle, or incorporated into the lid of the ladle. It can also be maintained or raised by a small burner.

  In each casting station 33, 34, the ladle 25d is evacuated from the bottom of the ladle by means of a controllable opening of the sliding closure, so that the spilled molten aluminum is preferably encased in an inert gas, collector.・ Guided by spout. During this stage, again, argon can be blown through the porous plug at the bottom of the ladle and the molten aluminum can be stirred and purified. By covering the ladle 25d, it is possible to generate an inert atmosphere in the upper region, and as a result, the oxidation and absorption of hydrogen are suppressed.

  The casting stations 33, 34 are each equipped with a filter system as known in the art and are operated continuously or semi-continuously.

  After emptying the ladle 25d, these ladles are transported to the purification and preparation station 30 described above, cleaned (see ladle 25e) and prepared for reuse, especially preheated. (See ladle 25a). The empty ladle can be stored in a storage station S provided for storage until subsequent use.

  Multiple paths are provided for transporting the ladle 25 from one station to the next or storage station (S), so that the ladle 25 can be transported by rail or overhead hoist. Yes.

  The casting machine according to the present invention controls the injection of charge from the individual furnaces 22, 23, 24 into the individual ladle 25, alloy additives, heating, cooling, gas supply, and processing time, A control system is provided that allows molten aluminum in the desired quality, desired temperature, and fully homogenized state to reach the casting stations 33,34.

  Using the ladle 25 according to the present invention, this process step can be carried out with respect to time, in terms of actual casting, preferably by processing and feeding molten aluminum in a controllable order to several casting stations 33, 34. Disconnected from the process. The individual treatments are no longer predetermined in terms of time and are not limited, and if necessary, in each ladle until the desired quality of the molten aluminum to be cast is achieved. It is possible to adjust. For example, if it is necessary to reduce the hydrogen content, the gas purification period can be extended. This option does not exist in the conventional inline process according to FIG. Caster production is determined by the actual casting process by the casting station alone, which can be continued until the supply of processed molten aluminum to the casting station is interrupted as necessary.

  The method according to the invention is considerably more efficient than an in-line process because it no longer requires a large smelting furnace. When used, these furnaces are used for melting and heating, but not for long-term insulation. They can take the form of induction furnaces that are energy efficient and economically advantageous. By preheating the ladle, it is possible to reduce the melting temperature achievable in the furnace.

1 is a schematic diagram for one of the embodiments of a state-of-the-art aluminum casting machine. 1 is a schematic view of one embodiment of an aluminum casting machine according to the present invention.

Explanation of symbols

  21 filling station, 22 furnace, 23 furnace, 24 furnace, 25 ladle, 30 preparation station, 32 processing station, 33 casting station, 34 casting station, S storage station

Claims (19)

  A method of casting aluminum or aluminum alloy in which molten aluminum is processed and sent to at least one casting station (33, 34) and cast into a semi-finished product or the like, the molten aluminum being processed, Utilizing several ladles (25) to send to each casting station (33, 34), the molten aluminum is poured into the ladle and transported to another stage (32) where it is processed. And further to the casting station (33, 34) for emptying the contents of the ladle (25).   2. In yet another stage (30), the emptied ladle (25) is cleaned and provided for reuse, in particular preheated. Casting method.   In the first stage (21), the molten aluminum is injected into the ladle (25) from one or several furnaces (22, 23, 24), resulting in several furnaces ( 22, 23, 24), it is possible to inject molten aluminum of different quality from the individual furnaces (22, 23, 24) into the ladle (25). Item 3. The casting method according to item 1 or 2.   The casting method according to claim 3, wherein an induction furnace is used in the first stage (21).   After filling each of the pans (25), scale is removed from the surface of the molten bath (scale removal), and the pan is tilted to an inclined position for this purpose. The casting method according to the item.   6. The method according to claim 1, wherein the second stage includes addition of an alloy additive to the molten aluminum, purification, homogenization, and temperature adjustment when necessary. The casting method according to the item.   In the second processing stage (32), the ladle (25) is arranged below the submerged rotary impeller to remove hydrogen bonds, homogenize, and adjust the temperature when necessary, using argon or nitrogen. 7. A casting method according to claim 6, wherein a small amount of chlorine is mixed with the purge gas in order to blow in an inert gas such as   8. At least a portion of the alloy additive is placed in the emptied and cleaned ladle (25) prior to pouring the molten aluminum. The casting method described in 1.   The ladle (25) passes through individual stations or stages by rails or overhead hoists, multiple passes through several casting stations (33, 34) and is filled with molten aluminum until used. A ladle (25) and / or a storage station (S) added for storing empty ladles, as claimed in any one of the preceding claims. The casting method according to the item.   In the respective casting stations (33, 34), the ladle (25) is emptied from the bottom of the ladle by means of a controllable opening of a sliding closure so that the molten aluminum flowing out is inert. The casting method according to claim 1, wherein the casting method is guided to a collector spout wrapped with gas.   Molten aluminum, if necessary, filling of the ladle (25) with mixed material from the respective furnace (22, 23, 24), addition of alloy additives, homogenization, temperature control and further the selected casting 11. Casting method according to any one of claims 6 to 10, characterized in that the processing and supply of the molten aluminum in time series to the stations (33, 34) are computer controlled.   12. Casting method according to any one of the preceding claims, characterized in that each casting station (33, 34) is operated continuously or semi-continuously and is equipped with a filter system.   A casting machine for carrying out the process according to claim 1, comprising at least one casting station (33, 34) and means for processing molten aluminum and feeding it to the casting station (33, 34). The molten aluminum treatment means and supply means include a number of ladles (25) capable of being filled with the molten aluminum in a first filling station (21), the ladle being a second ladle. A plurality of transport paths are provided that can be transported to the processing station (32), and further from which the respective casting stations (33, 34) can be transported, and each ladle (25) Casting machine, characterized by having a sliding closure or the like, which can open and empty the ladle.   For the empty ladle (25), a purification and preparation station (30) is further provided, from which the ladle can be conveyed to the filling station (21). The casting machine according to claim 13.   A ladle (25) filled with molten aluminum and / or an additional storage station (S) is provided for storing an empty ladle (25) until use. The casting machine according to claim 13 or 14.   The filling station (21) is provided with several furnaces (22, 23, 24) capable of supplying basic materials, preferably induction furnaces, and if necessary, said induction furnaces (22, 23). 24) It is possible to supply aluminum materials of various qualities to the casting machine according to any one of claims 13 to 15.   17. The ladle (25) according to any one of claims 13 to 16, characterized in that the ladle (25) is covered by a lid to which a burner can be attached in order to maintain or raise the temperature of the molten aluminum. Casting machine.   The casting machine according to any one of claims 13 to 17, wherein the ladle (25) is equipped with a porous plug for injecting an inert gas.   19. A rail or hoist is provided for transporting the ladle (25) from one station to the next and to the storage station (S). The casting machine described.

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