Process and system for dosing molten metal

Abstract

A method for dosing molten metal comprises providing molten metal (21) in a casting furnace (2), metered filling of a quantity of the molten metal (21) from the casting furnace (2) into a pre-dosing container (8) and emptying the molten metal (21) from the pre-dosing container (8).

Description

The invention relates to a method and a system for metering liquid, in particular molten, metal, in particular light metal, in particular aluminum, in particular aluminum-containing alloys, in particular magnesium and / or in particular magnesium-containing alloys.A method and an apparatus for casting metal are known from WO 2016 / 184 686 A1. Molten metal is filled into a casting mold from a casting furnace by means of a riser pipe. By means of an adapter unit, the casting furnace can be fluidically decoupled from the casting mold.It is the object of the present invention to improve the casting of metal, in particular to speed up the process.This object is achieved according to the invention by a method having the features specified in claim 1 and by a plant having the features specified in claim 7.According to the invention, it has been recognized that it is advantageous if metal melt, which is to be filled into a casting mold and / or into a casting machine, is initially metered into a pre-metering container from a casting furnace. This means that an amount of the metal melt, which can be fixed in a variable manner in particular, is discharged into the pre-metering container and provided there. The metal melt is metered from the casting furnace into the predispensing container. The predispensing container is arranged outside the casting furnace and in particular is embodied separately from the casting furnace. The predispensing container is in particular fluidically connected to the casting furnace by means of a connecting line, in particular in the form of a riser pipe.The predispensing container is filled in particular with a protective gas, in particular an inert gas. In the casting of aluminum alloys, nitrogen or argon in particular serves as inert gas. In the casting of magnesium, the inert gas used is in particular gas mixtures of tetrafluoroethane, sulphur dioxide and / or a special inert magnesium gas which is sold under the trade name Novec® 612.It is possible in particular to provide a plurality of predispensing containers which can be fluidically connected to the casting furnace, in particular in a modular manner. The predispensing containers can have, in particular, filling volumes of different sizes.It has been recognized in particular that the metering accuracy of the metal melt is improved. In particular, the metering accuracy is independent of a filling degree of the metal melt in the casting furnace. The filling degree of the casting furnace influences the inertia of the moving mass in the form of the metal melt and must be taken into account in the control parameters of the casting furnace. This consideration is possible only to a limited extent and is prevented by the use of the predispensing container according to the invention. The metal melt can be metered with a higher accuracy and discharged into the casting mold and / or into the casting machine.In particular, the metal melt can flow out of the predispensing container automatically.Because the nominal volume of the pre-metering container is smaller and in particular significantly smaller than the filling volume of the casting furnace, the metering accuracy is correspondingly increased. In particular, the nominal volume of the pre-dosing container is at most 10% of the filling volume of the casting furnace, in particular at most 8%, in particular at most 6%, in particular at most 5% and in particular at most 3%. The accuracy of the dosing quantity depends in particular on a sensor system which is used to monitor the fill level in the pre-dosing container. In particular, the accuracy of the metering quantity thus depends on the accuracy of a pressure control, a height measurement, a weight measurement and / or a size of the cross-sectional area of the pre-metering container.In particular, it has been recognized that the pre-metering container already enables metering of the metal melt, while the casting mold and / or the casting machine is still filled with metal melt from a previous casting cycle. According to the invention, it has thus been recognized that the pre-metering of the metal melt on the one hand and the filling of the casting mold and / or of the casting machine on the other hand can be decoupled from one another. This means in particular that after a casting has been removed from the casting mold and / or from the casting machine, the metal melt predosed in the predose container can be directly filled into the casting mold and / or the casting machine, in particular without additional metering. This reduces the time required for filling the casting mold and / or the casting machine to transfer the melt into the casting mold and / or the casting machine. The pre-metering of the metal melt and the production of a casting, in particular in the casting mold and / or in the casting machine, can take place in a temporally overlapping manner and in particular simultaneously.Overall, there is a potential for shortening the cycle time during the production of corresponding cast parts. The method according to the invention can advantageously be automated and economical.It is also possible in particular to connect a plurality of predispensing containers in parallel to the casting furnace. The predispensing containers can fill a casting mold and / or a casting machine at the same time or in a manner offset in time with respect to one another.Emptying the metal melt from the predosed container can be accelerated in particular by introducing the protective gas into the predosed container. In particular, a protective gas container is connected to the pre-dosing container, in particular to an upper side of the pre-dosing container. The protective gas can be supplied to the predispensing container in an upper region and in particular from above. A filling opening for the metered filling of the metal melt into the pre-metering container and / or a discharge opening for letting the metal melt flow out of the pre-metering container are arranged in particular in a lower region and in particular on the underside of the pre-metering container.The method according to the invention is uncomplicated, since the metal melt metered in the pre-metering container can run directly into the casting mold and / or into the casting machine. The installation is of uncomplicated design. The execution of the method is failsafe and robust.In order to speed up the emptying of the metal melt from the predispensing container and in particular to implement it in a failsafe manner, in particular in a process-stable manner, the pressure in the predispensing container can be varied. A pressure increase in the pre-dosing container is possible in particular in that the pre-dosing container is designed as a closed system. When the metal melt is filled into the pre-metering container, the gas pressure in the pre-metering container increases, in particular by a reduction in volume and / or an increase in temperature. When the metal melt is emptied into the casting mold and / or into the casting machine, the increased gas pressure acts like a mechanical spring and leads to an accelerated discharge of the metal melt, in particular without additional inert gas addition.A method according to claim 2 enables an advantageous metering of the metal melt in the pre-metering container. The filling of the pre-metering container with the metal melt is effected in particular by means of a pump, in particular by means of an electromagnetically operated pump, which conveys the metal melt from the casting furnace into the pre-metering container. In this case, the casting furnace is designed in particular as an open heat-retaining furnace. The delivery of the metal melt can in particular also be effected by means of reduced pressure at the predispensing container, in that the metal melt is sucked from the casting furnace into the predispensing container by means of the reduced pressure.The casting furnace can also be designed as a pressure-tight furnace, in particular as a low-pressure furnace. In this case, the metal melt can be conveyed into the predispensing container by means of the low pressure present in the furnace.The metering, i.e. in particular the monitoring of the amount of the metal melt in the pre-metering container, can be effected volumetrically. For this purpose, in particular the fill level of the metal melt in the predispensing container is monitored. A sensor element, in particular a fill level sensor, which can in particular have a laser element, is used in particular for fill level monitoring. The at least one sensor element is arranged in particular outside the predispensing container.For improved accuracy in the pre-metering of the volume of the metal melt, it is advantageous if the pre-metering container is embodied in slender fashion, i.e. has a small base area compared to its height. The base surface is in particular cylindrical, but can also be polygonal, in particular rectangular or square. In particular, the height of the predispensing container is greater than a maximum diameter of its base surface. When the base is cylindrical, the maximum diameter of the base is the circular diameter. If the base is rectangular or square, the diagonal corresponds to the maximum diameter. In particular, the height is at least 1.5 times the maximum diameter, in particular at least twice, in particular at least 3 times, in particular at least 5 times, in particular at least 10 times, in particular at least 20 times and in particular at most 100 times.The quantity of the metal melt which is metered into the pre-metering container can be defined in particular in a variable manner. For this purpose, the pre-dosing container can be equipped in particular with a plurality of fill level sensors which are arranged spaced apart from one another in particular along the height direction of the pre-dosing container. Additionally or alternatively, it is possible to provide predispensing containers of different nominal volume in order to variably define the volume of the metal melt.Additionally or alternatively, gravimetric metering can be effected. The predispensing container is arranged in particular on at least one load cell, in particular on a plurality of, in particular three, load cells. During the filling of the pre-metering container, the weight increase can be detected and thus the amount of the supplied metal melt can be detected. It is advantageous if disturbance variables are taken into account in the detection of the quantity of the metal melt, in particular the lift of the connecting line, in particular of the riser pipe. Additionally or alternatively, gravimetric metering can also be effected by pressing the pre-metering unit against one or more load cells with a defined pressing force, which is provided, for example, by a mechanical spring element, in particular vertically upward, i.e., directed counter to the gravity. When filling the pre-metering container, the contact pressure is reduced as a result of the weight force of the supplied metal melt, wherein the reduction of the contact pressure is detected for gravimetric metering.Additionally or alternatively, it is also possible to carry out the metered filling of the pre-metering container by means of a pressure monitoring system. It is possible to take into account a pressure difference between the predispensing container and the casting furnace. Additionally or alternatively, the reduced pressure in the casting furnace can also be used for the targeted and metered filling of the pre-metering container.The fill level sensors can also be designed, in particular, as radar sensors or capacitive and / or inductive sensors. The laser sensor is in particular a laser distance sensor which is arranged on an upper side of the predispensing container and detects the distance of the surface of the metal melt from the upper side of the predispensing container. The greater this distance, the lower the fill level. The predispensing container is produced in particular from a melt-resistant material. Ceramic materials have proven suitable for the handling of aluminum melt, in particular a technical ceramic, in particular aluminum titanate, silicon nitride and / or aluminum nitrite. The predispensing container produced in this way has a long service life and a low heat loss. Alternatively, a metallic material coated with zirconium dioxide could also be used. When using magnesium melt, in particular melt of magnesium alloys, the material is a steel material. A coating is unnecessary.The connecting line, in particular the riser pipe, is produced from a resistant material, in particular from a ceramic material, in particular from a technical ceramic.A method according to claim 3 improves automated performance. By means of a regulating unit which is in particular in signal connection with at least one sensor element, the metered filling of the pre-metering container can be effected in a regulated manner. The at least one sensor element is in particular a fill level sensor and / or a load cell.A method according to claim 4 enables fluidic separation of the predispensing container from the casting furnace. In particular, a fluid connection, in particular in the connecting line, is separated. In particular, the fluid connection is interrupted before the metal melt is emptied from the predispensing container. In particular, the emptying of the predispensing container can take place independently of the pressure of the casting furnace. By interrupting the fluid connection, the predispensing container is separated from the casting furnace by pressure.A method according to claim 5 effects an improved movement of the metal melt, in particular from the connecting line back into the casting furnace. The risk of segregation beginning in the casting furnace, i.e. heavy alloy components, such as in particular silicon, settling in the metal melt, is reduced. For ventilating the fluid connection, in particular the connecting line, inert gas can be supplied to the latter by means of an openable ventilation opening. The opening of the ventilation opening can be effected in particular in a controlled and / or regulated manner, in particular by opening a flap and / or by exposing the ventilation opening by rotating and / or axially displacing a rotary piston which is in particular part of a ceramic valve.In a method according to claim 6, the risk of defective castings being produced is reduced. It has been recognized that when the connecting line, in particular in the form of the riser pipe, is immersed in the metal melt in the casting furnace, an oxide skin formed there reaches the predispensing container with the surface of the riser pipe inner diameter. When casting production is started, a first metering quantity can be separated off by means of a branch line. It is ensured that the metal melt metered in the subsequent cycle is low in oxide, in particular free of oxide skin, and is in particular present at a corresponding temperature. The diverted partial amount of the metal melt can be as large as the metered amount. Branching off the metal melt is advantageous in particular whenever the connecting line is immersed in the melt bath in the casting furnace. It is advantageous if the diverted partial amount, which is unsuitable for casting production, is as small as possible. In particular, this portion is smaller than half of the predosed amount, in particular smaller than 30% of the predosed amount, in particular smaller than 20% of the predosed amount and in particular smaller than 10% of the predosed amount.It is advantageous if the predosed quantity is so large that the oxide skin which is located on the surface of the metal melt is arranged completely within the predose container. Since the pre-dosing container is subsequently completely emptied, the oxide skin is discharged from the pre-dosing container. It is additionally advantageous to fill a larger metering quantity in the first cycles, in particular in the first cycle, of a casting production than would be required for the casting cycle, into the pre-metering container. The predispensing container is advantageously preheated and brought more quickly to the required operating temperature. The discharge of the metal melt from the predispensing container is thereby promoted. A discharge cross section, i.e. a cross-sectional area of the branch line, is in particular so large that the branch-off portion, in particular with the oxide skin, can automatically discharge from the pre-metering container, in particular without blockage. In particular, the inner diameter of the branch line is larger than the inner diameter of the riser pipe.If the pressure in the pre-metering container is controlled and / or regulated, the pressure at the outlet opening of the pre-metering container can be kept constant independently of the fill level of the metal melt in the pre-metering container. By using a cooling device, it is possible to meter out a profile element, in particular continuously.The branch line is also referred to as a bypass line. The branch line ensures the branching off of a partial quantity of the metal melt without the metal melt having to be guided through the discharge opening of the predispensing container.Alternatively, it is conceivable to let the partial quantity to be branched off run off into the casting mold and separate it as a defective casting part. The branch line would then be unnecessary.A plant according to claim 7 enables the advantages of the method according to claim 1. in the plant the casting furnace is in particular designed as an open heat-retaining furnace or as a pressure-tight furnace, in particular as a low-pressure furnace. The plant has at least one predispensing container and can also have a plurality of predispensing containers. Each predispensing container is connected to the casting furnace by means of a connecting line, in particular by means of its own connecting line. In particular, each predispensing container can be connected directly by means of a connecting line in terms of fluid technology to the casting furnace. The connecting line is in particular designed as a riser pipe. The at least one predispensing container is designed to be fluidically connectable to a casting mold and / or to a casting machine. Alternatively, the metal melt can be metered out directly, in particular as a wire, from the at least one pre-metering container.In particular, the plant is of modular design, so that the at least predispensing container can be detachably connected to the casting furnace in a variable manner. In particular, the plant according to the invention can be combined with already existing metering furnaces. Accordingly, the at least one predispensing container can be detachably connected to the casting mold and / or the casting machine. In particular, the predispensing container is designed to be mobile in order to be moved between the casting furnace and the casting mold and / or the casting machine. It is in particular conceivable for the casting furnace and the casting mold and / or the casting machine to be arranged spaced apart from one another. It is conceivable, for example, to connect the predispensing container to the casting furnace and to fill it in metered fashion with the metal melt. The predispensing container can then be shut off and transported to the casting mold and / or to the casting machine. There, the predispensing container can then be fluidically detachably connected to the casting mold and / or the casting machine.A plant according to claim 8 allows for increased flexibility in the production of castings.It is possible in particular to connect a plurality of predispensing containers to a low-pressure casting furnace. In the case of different volumes of the pre-dosing containers, i.e. in particular in the case of different base areas of the pre-dosing containers, a different amount, i.e. a different volume, of the metal melt can be dosed at a respectively identical fill level. Additionally or alternatively, it is possible to shut off the inflow into the respective pre-dosing container when the pre-dosed quantity is reached, i.e. when a desired fill level is reached. If the internal pressure in the casting furnace is increased further, the fill level of the metal melt in the further predispensing containers still connected to the casting furnace will increase further. As a result, different metering quantities in the different pre-metering containers can be adjusted in a targeted manner. The setting of the respective metering quantity is thus adjustable via the fill level. In particular, it is possible to set the different metering quantities with only one pressure control, namely centrally in the casting furnace. Such a system can also be designed by means of gravimetric metering. In particular, in this case the predispensing containers can be designed with identical size.A plant according to claim 10 enables an automated execution of the method, in particular fully automatically. A control unit is in particular in signal connection with at least one sensor element, in particular wired or wireless.A plant according to claim 11 ensures a targeted temperature control of the metered amount of metal in the pre-metering container. For this purpose, the predispensing container can have at least one, in particular electrical, heating element which serves for the active heating of the predispensing container. It is also conceivable to heat a shut-off element which serves to shut off the predispensing container. The heating element used is, in particular, a gas burner, a submerged heater, an electric cartridge heater and / or electric heating coils. It is also conceivable for a predispensing container to be of double-walled design with a heating jacket. Additionally or alternatively, the predispensing container can be designed with a thermal insulation, which is designed in particular from a thermal insulation material. The thermal insulation acts passively and serves in particular to reduce heat losses in the predispensing container. A temperature drop can thereby be minimized. In particular, it is thereby possible to already fill the pre-dosing container while a previous casting cycle still takes place in the casting mold and / or the casting machine. As a result, the cycle time can be shortened overall.The embodiment of the heating element according to claim 12 is particularly energy efficient. The direct heating acts directly and efficiently. If, in addition, the predispensing container is produced from a highly insulating material, in particular a ceramic material, heat losses are minimized.The embodiment of the predispensing container according to claim 13 enables the advantageous metering of the metal melt and its discharge into the casting mould and / or the casting machine. A pipette dispenser is filled by means of reduced pressure via the connecting line, in particular the riser pipe, by metal melt being sucked from the pouring furnace into the predispensing container. The reduced pressure is held in the pre-dosing container, then the inflow into the pre-dosing container, i.e. connecting line, is interrupted by means of a closure element, in particular by means of a rotary piston, a slide or a stopper, and after the metal melt has discharged from the pre-dosing container, the inflow is released again. The negative pressure can then be compensated for in a targeted manner, so that the metal melt can drain, in particular through a drain line, into the casting mold and / or into the casting machine.A shut-off element according to claim 14 simplifies the automated execution of the method. The shut-off element enables in particular the switched shut-off of the connecting line. The shut-off element can be designed as a rotary closure according to WO 2016 / 184 686 A1. With regard to the geometric configuration and the function of the rotary closure, express reference is made to WO 2016 / 184 686 A1. Other shut-off elements are known from U.S. Pat. No. 4,196,829 A, from DE 10 2004 043 444 B3 and from DE 20 2005 010 254 U1. The shut-off element is in particular a stopper, a slide and / or a piston.An actuator according to claim 15 simplifies the actuation of the shut-off element.Both the features specified in the patent claims and the features specified in the following exemplary embodiments of a plant according to the invention are each suitable, alone or in combination with one another, for further developing the subject matter according to the invention. The respective combinations of features are not restrictive with respect to the development of the subject matter of the invention, but essentially have only an exemplary character.Further features, advantages and details of the invention are evident from the following description of exemplary embodiments with reference to the drawing. The following are shown: FIG. 1 shows a perspective view of a plant according to the invention for metering molten metal, having a casting furnace and two pre-metering containers connected thereto, FIG. 2 shows a schematic longitudinal sectional illustration of a plant according to a second exemplary embodiment, FIG. 3 shows a perspective sectional view of the predispensing container according to FIG. 2 with the casting mold connected during the filling of the predispensing container, FIG. 4 is a view corresponding to FIG. 3 with interrupted fluid connection between the pre-metering container and the casting furnace, FIG. 5 shows a representation corresponding to FIGS. 3 and 4 during emptying of the pre-dosing container, FIG. 6 shows a representation corresponding to FIGS. 3 to 5 of a system according to a further exemplary embodiment without a casting mold.A plant identified as a whole by 1 in FIG. 1 serves for metering metal melt, in particular metallic materials which comprise aluminum and / or magnesium, in particular pure aluminum, aluminum alloys, pure magnesium and / or magnesium alloys.The plant 1 comprises a casting furnace 2, which in the exemplary embodiment is designed as a pressure-tight casting furnace. The casting furnace 2 has an inner container 3, with an upper cylinder section and a lower spherical cap section formed integrally thereon. The inner container 3 is also referred to as a crucible. The inner container 3 can also have a different geometric shape.The inner container 3 is surrounded by a thermal insulating layer 4 in order to reduce the heat loss during the metering process. In addition, the casting furnace 2 can have a heating device, not shown in detail, in order to enable separate heating.The casting furnace 2 has a compressed gas connection 5 for a drying gas supply. At the compressed gas connection 5, a line for connection to a central compressed gas supply can be present. A regulated supply of compressed gas can take place via the compressed gas connection 5, in particular with a control unit which is configured in a stationary manner on the casting furnace 2.On its upper side, the casting furnace 2, in particular the inner container 3, can be closed in a pressure-tight manner by a cover 6. The cover 6 is thermally insulated.The casting furnace 2 has a pressure-tight connecting line, not shown, to the outside in order to be able to increase the pressure atmosphere above the metal melt in the inner container 3.The plant 1 has two predispensing units 7. According to the exemplary embodiment shown, the predispensing units 7 are of identical design. Each pre-metering unit 7 comprises a pre-metering container 8, which is fluidically connected to the casting furnace 2, in particular to the inner container 3, by means of a connecting line 9. The connecting line 9 comprises a removal pipe 10 which is guided sealed by an opening in the cover 6 into the casting furnace 2, in particular into the inner container 3, and dips into the metal melt there. The connecting line 9 further comprises a riser pipe 11 which is detachably coupled to the extraction pipe 10. In particular, the extraction pipe 10 and the riser pipe 11 are arranged concentrically with respect to one another. The riser pipe 11 is part of an adapter unit 12 to which the predispensing container 8 is fluidically connected. The adapter unit 12 has an adapter housing 13, in which a piston 14 is arranged. With regard to the construction and mode of operation of the adapter unit 12, in particular the melt feed from the casting furnace 2 into the predispensing container 8, express reference is made to WO 2016 / 184 686 A1.A drain line 15 is connected to the predispensing container 8, in particular by means of the adapter unit 12. The outlet line 15 is designed in particular as a vertically downwardly oriented pipe or line. By means of the outlet line 15, the predispensing container 8 can be fluidically connected to a casting mold or casting machine, not shown in FIG. 1.The predispensing container 8 is placed with its underside on the adapter unit 12, in particular on the adapter housing and in particular concentrically with respect to the piston 14. The pre-dosing container 8 has an upper cylinder section and a lower cone section, which promotes the automatic emptying of the pre-dosing container 8. The upper cylinder section of the pre-dosing container 8 is sealed pressure-tightly on its upper side by a container cover 16.The pre-dosing container 8 is flooded with a protective gas which is stored in a compensation container 17. The compensating container 17 is connected to the container cover 16 on the predispensing container 8.The piston 14 forms a shut-off element, with which the connecting line 9, in particular the riser pipe 11, can be shut off. In the shut-off state, the predispensing container 8 is fluidically separated from the casting furnace 2. The piston 14 can be actuated in particular by means of an actuator, not shown in detail, in particular can be rotated about its longitudinal axis. The actuator is in particular an electromotive drive which is in particular controllable and in particular controllable. The actuator may alternatively be hydraulically, pneumatically and / or manually actuated.The predispensing unit 7 has a sensor element 18. Sensor element 18 is designed as a displacement sensor, in particular as a laser distance sensor. The sensor element 18 is arranged on the compensation container 17 and serves for fill level monitoring of the protective gas in the compensation container 17. the fill level of the protective gas in the compensation container 17 enables a direct conclusion about the fill level of the metal melt in the pre-dosing container 8.It is understood that the plant 1 can also be equipped with only one single pre-dosing unit 7 or with more than two pre-dosing units 7.The system 1 has a regulating unit 19, which is shown purely schematically. The control unit 19 enables automated operation of the installation 1, in particular fully automated operation. The control unit 19 is in signal connection in particular with the casting furnace 2, in particular a temperature sensor arranged therein and a pressure sensor arranged therein, with the adapter unit 12, in particular the piston 14 and the drive for the piston 14, and / or with the sensor element 18. The signal connection is in particular bidirectional. The signal connection is in particular cable-bound, but can also be implemented wirelessly.The function of the plant 1 is explained in more detail below. To carry out a metering process, metal melt is removed from the inner container 3 of the casting furnace 2 via the connecting line 9 and metered in the pre-metering container 8. During the dosed filling of the pre-dosing container 8, the shut-off element is in an opening position. During the filling process, the fill level of the metal melt in the predispensing container 8 is monitored, in particular continuously, by means of the sensor element 18.When the desired fill level in the pre-dosing container 8 is reached, the piston 14 is displaced, in particular rotated, into a shut-off position, so that the connecting line 9, in particular in the riser pipe 11, is closed by means of the piston 14. A further supply of melt from the casting furnace 2 into the predispensing container 8 is thereby prevented. Because the pre-dosing container 8 has a comparatively small volume, the pre-dosing of the metal melt in the pre-dosing container 8 can take place very accurately. In particular, the pre-metering of the metal melt in the pre-metering container 8 can already take place for the subsequent casting process, while a casting cycle in the casting mold and / or the casting machine still continues. As soon as the casting produced in the casting mold and / or the casting machine is finished and removed, the metal melt can run out of the predispensing container 8 into the casting mold and / or into the casting machine. The running off can take place in particular automatically. However, the draining can be effected by applying pressure, in particular by means of the protective gas, from the compensating container 17.In the following, a second exemplary embodiment of a plant is described with reference to FIGS. 2 to 5. Structurally identical parts are given the same reference numerals as in the first exemplary embodiment, to the description of which reference is hereby made. Structurally different, but functionally similar, parts are given the same reference numerals with an suffix a.As shown in FIG. 2, the removal tube 10 is pressed against a spring force of a wave compensator 20 into the interior of the casting furnace 2, in particular into the inner container 3. By means of the spring force of the wave compensator 20, the separation point between the extraction pipe 10 and the riser pipe 11 can be connected in a pressure-tight manner. The extraction pipe 10 is also referred to as a furnace riser. It is alternatively possible to use a riser pipe arrangement known from the prior art, in which the riser pipe is firmly fixed to the cover 6. In such an embodiment, the sealing is guaranteed in that the casting furnace 2 is pressed together with the predispensing container 8 aand additional sealing elements are used.FIG. 2 shows the metal melt 21 in the inner container 3. FIG. 2 shows the installation 1 ain a state in which the connecting line 9 is disconnected.The casting furnace 2 has a heating device 22, which is designed in the form of an electrically heatable immersion heater, which is held on the cover 6 and dips into the metal melt 21 in the inner container 3.The predispensing container 8a has a heating element 23. The heating element 23 serves for the active heating of the pre-dosing container 8 aand thereby enables a targeted temperature control of the metal melt 21 in the pre-dosing container 8 a. In particular, the heating element 23 can be regulated by means of the regulating unit 19. The heating element 23 is in particular designed as an electric heating coil and is arranged on the outer periphery of the predispensing container 8 a, in particular along the entire container height. This ensures homogeneous heating of the pre-metering container 8 ain order to reduce and in particular eliminate a loss of temperature of the metal melt 21 located in the pre-metering container 8 a. The housing of the predispensing container 8a has a thermal insulation material. The housing forms a thermal insulation of the pre-dosing container 8 a.The predispensing container 8a has a container opening 24, which is arranged centrally at a lower end of the cone section. The container opening 24 is arranged in particular concentrically with respect to the longitudinal axis 25 of the piston 14. Through the container opening 24, metal melt 21 can be fed into the predispensing container 8 aand discharged again from the predispensing container 8 a. The container opening 24 forms both a feed opening and a discharge opening for the metal melt 21, and the sensor element 18 ais arranged directly on the pre-dosing container 8 a, in particular on the container lid 16, in the exemplary embodiment shown. The sensor element 18 acan be used to directly detect the fill level of the metal melt 21 in the predispensing container 8 a.By means of the outlet line 15, the predispensing container 8 ais fluidically connected to a casting mold 26.It is particularly advantageous if the container opening 24 is connected not only to the discharge opening 27 but also to a bypass opening to which a branch line can be connected. As a result, it is possible to branch off, i.e. separate out, a portion of the metal melt 21 that is not to be used for the metering process, i.e. not to discharge it into the casting mold and / or the casting machine.In the following, a metering method with the system 1a is explained in more detail with reference to FIGS. 2 to 5.The molten metal 21 is supplied in the casting furnace 2 and optionally kept at constant temperature by means of the heating device 22. By means of the connecting line 9, i.e. by means of the extraction pipe 10 and the riser pipe 11, the metal melt 21 is fed through the container opening 24 to the predispensing container 8 a. For this purpose, the piston 14 is rotated starting from the position in FIG. 2 with respect to the longitudinal axis 25 into the position according to FIG. 3. As a result, a fluid connection is established from the riser pipe 11, i.e. from the connecting line 9, to the predispensing container 8 a. Due to the internal pressure in the casting furnace 2, the molten metal 21 is forced into the predispensing container 8a through the discharge pipe 10 and the riser pipe 11. During this, the fill level of the metal melt 21 in the predispensing container 8 ais continuously monitored by means of the sensor element 18 a. The protective gas present in the empty pre-dosing container 8 a, in particular argon or nitrogen, is displaced by the metal melt 21 into the compensating container 17. When the adjusted fill level of the metal melt 21 is reached, a fill level signal is transmitted from the sensor element 18 ato the regulating unit 19, which then transmits an adjustment signal to the drive of the adapter unit 12. By means of the drive, the piston 14 is rotated into a holding position which is illustrated in FIG. 4. In the holding position of the piston 14, the fluid connection along the connecting line 9 is separated. The molten metal 21 is held in the predispensing container 8a. The metal melt 21 in the connecting line 9 can automatically flow back into the casting furnace 2. For this purpose, it may be advantageous to ventilate the connecting line 9.The filling of the pre-metering container 8 a, i.e. the pre-metering of the metal melt 21 for a subsequent casting process, takes place in particular already at a point in time at which a casting cycle of a previous casting still takes place in the casting mold 26. As soon as this casting cycle is concluded and a produced casting is removed from the casting mold 26, an enable signal is transmitted from a controller of the casting mold 26 to the control unit 19. The control unit 19 transmits a further actuating signal to the adapter unit 12, in particular to the drive of the piston 14. In the discharge position, the metal melt 21 can automatically flow out of the pre-metering container 8 ainto the casting mold 26 along the discharge line 15 into the casting mold 26, in particular automatically. The outflow process can be accelerated in particular by the protective gas being forced out of the compensating container 17 into the pre-metering container 8 a. A new cycle can then begin, in particular with the metered filling of the pre-metering container 8 a.In the following, a third exemplary embodiment of a plant is described with reference to FIG. 6. Structurally identical parts are given the same reference numerals as in the two first two exemplary embodiments, to the description of which reference is hereby made. Structurally different, but functionally similar, parts are given the same reference numerals with an suffix b.Compared to the previous exemplary embodiment, the system 1 bsubstantially differs in that the system is designed without a casting mold or casting machine. Accordingly, no outlet line 15 is arranged on the adapter unit 12. The plant 1 bhas a cooling device 32, which is arranged in particular at the discharge opening 27 b.The cooling device 32 enables cooling of the metal melt in the continuous process. The discharge opening 27 bis formed integrally in the adapter housing 13. Alternatively, the dispensing opening 27b can be designed in the form of geometry-imparting, replaceable inserts in the adapter housing 13.Downstream of the cooling device 32 there is arranged a strand receiving device 28 which has a plurality of rotatably mounted conveying rollers 29. The conveyor rollers 29 can be designed to be rotatable by means of a rotary drive, not shown. The conveying rollers 29 are arranged spaced apart from one another along a strand conveying direction 30 and in particular in a plane. The plant 1b is used in particular for producing a continuous wire, in particular from an aluminum alloy or from pure aluminum. For this purpose, in the discharge position of the piston 14, the metal melt 21 is discharged through the discharge opening 27 band a profile element 31 is thereby metered out. By means of the compensating container 17, the pressure in the predispensing container 8 bcan be kept constant independently of the fill level of the metal melt 21.References included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedWO 2016 / 184 686 A1 [0002, 0042, 0052]U.S. Pat. No. 4,196,829 A

[0042] DE 10 2004 043 444 B3

[0042] DE 20 2005 010 254 U1

[0042]

Claims

Method for metering molten metal comprising the method steps - providing molten metal (21) in a casting furnace (2), - metered filling of an amount of the molten metal (21) from the casting furnace (2) into a pre-metering container (8; 8a; 8b), - emptying the molten metal (21) from the pre-metering container (8; 8a; 8b).Method according to claim 1, characterised in that the metered filling of the pre-metering container (8; 8a; 8b) is effected volumetrically and / or gravimetrically.Method according to one of the preceding claims, characterized in that the metered filling of the pre-metering container (8; 8a; 8b) is effected in a controlled manner by means of a control unit (19), wherein the control unit (19) is in particular in signal connection with at least one sensor element (18; 18a; 18b).Method according to one of the preceding claims, characterized bya fluidic connection (9) between the casting furnace (2) and the predispensing container (8; 8a; 8b).Method according to one of the preceding claims, characterized by aeration of a fluid connection (9) between the casting furnace (2) and the predispensing container (8; 8a; 8b), in particular after the interruption of the fluid connection (9).Method according to one of the preceding claims, characterized in that a partial amount of the metal melt (21) is branched off by means of a branch line before emptying.Plant for metering molten metal comprising a. a casting furnace (2) for providing a molten metal (21), b. a pre-metering container (8; 8a; 8b) which can be fluidically connected to the casting furnace (2) by means of a connecting line (9).Plant according to claim 7, characterised bythe fact that several predispensing containers (8; 8a; 8b) are connectable, in particular variably, to the casting furnace (2).Plant according to claim 7 or 8, characterised byat least one casting mould (26), in particular a plurality of casting moulds (26), and / or at least one casting machine, in particular a plurality of casting machines, which can be connected, in particular variably, to the casting furnace (2).System according to one of Claims 7 to 9, characterized bya regulating unit (19) which is in particular in signal connection with at least one sensor element (18; 18a; 18b).Installation according to one of Claims 7 to 10, characterized bya heating element (23) for heating the predispensing container (8; 8a; 8b) and / or a thermal insulation for thermally insulating the predispensing container (8; 8a; 8b).Installation according to Claim 11, characterized in that the heating element (23) is designed as a direct heater integrated on the predispensing container (8; 8a; 8b), in particular as at least one conductor track printed on the predispensing container (8; 8a; 8b).The system according to any one of claims 7 to 12, characterized in that the predispensing container (8; 8a; 8b) is designed as a pipette dispenser.Installation according to one of Claims 7 to 13, characterized bya shut-off element (14) for shutting off the connecting line (9).Installation according to claim 14, characterised in that the shut-off element (14) is actuated by means of an actuator, in particular mechanically, electrically, pneumatically and / or hydraulically.

Images