Classifications

• • 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
  • B22D11/10—Supplying or treating molten metal

Definitions

• the invention relates to a casting device with an intermediate container for a molten metal, a device for maintaining a selectable level of the melt in the intermediate container, and with a nozzle for dispensing the melt to a shaping device or mold.
• Such intermediate containers are often also available as a tundish or as a mold.
• Such a casting device is known for example from US-A-4,482,012, but also from US-A-4,358,416 or DE-U-76 12 351.
• metal is conveyed into a tundish arranged above the continuous casting device as an intermediate container, the outlet of which is regulated in such a way that a constant level results in the melt container of a continuous casting device.
• a constant or adjustable level over time is important for the quality of the manufactured product, be it a slab, a billet, bolt, sheet, band or the product close to the final shape, or for the proper and trouble-free operation.
• a disadvantage of the known arrangements is that the metal in the tundish cannot or cannot simply be protected against oxidation. This is particularly disadvantageous when non-ferrous metals such as aluminum or even magnesium are to be cast. Although it is known to cover the surface of the melt in a tundish with a powder in order to prevent the entry of oxygen, this leads to undesirable impurities. Another disadvantage is the fact that the known arrangement is both investment and space consuming.
• the invention is therefore based on the object of ensuring the good quality of the product in a simple manner, and this is achieved according to the invention in that the device for maintaining the level of the melt has at least one metering pump in the intermediate container, which has a setting arrangement for metering for a selectable level, and that the outlet of this intermediate container is provided with at least one nozzle each for delivering the melt to the shaping device or mold.
• the outlet of an intermediate container is simultaneously used as a nozzle to form a conveyor belt which is deposited and cooled there, especially a sheet-like metal strand.
• the invention can be applied not only to (continuous) continuous casting devices, but also for the discontinuous casting of semi-finished products, such as ingots, or finished products. Because it has been shown in tests that the quality of the product (from the metallurgical point of view) can be improved if, for example, the nozzle with the metallostatic pressure (or controlled pump pressure) which is constant with the aid of the metering pump is designed to be so wide that it is Length of a mess shape (or other shape) fills evenly (and quickly). The uniformity of the conditions should play a role in the resultant more uniform (fine) grain in the metal of the product.
• the filling can take place from above (ingot shape) or laterally or from below, as is the case, for example, with low-pressure casting or with continuous casting upwards.
• the arrangement can, however, be further simplified in that the intermediate container is formed by a chamber of a dosing furnace. In this way, the furnace and the casting device form one unit.
• the intermediate container is closed and optionally has a supply for a protective gas.
• the closed intermediate container can be charged with protective gas, as is preferred. It may be desirable to do this under pressure, such a pressure then advantageously being used to regulate the (eg metallostatic) pressure at the nozzle. In space- in general, however, the inert gas pressure will be negligible and therefore need not be taken into account, which simplifies the regulation.
• the metering pump has a pump tube, which reaches down to a level in the melt that is located between the bottom area of a chamber located in front of the intermediate container and its melt level, because in this way impurities which are present either settle on the floor or exist as floating substances on the surface of the melt, do not get into the product via the intermediate container.
• the feed pump is designed so that the shaft of the metering pump is mounted within a tube passing through the intermediate container and forming the pump tube, then the unwanted movements of the molten pool emanating from its rotating pump shaft can remain restricted to the inside of the tube surrounding the shaft and thus undesirable bath movements (e.g. Vortex) in the intermediate container should be avoided if possible.
• undesirable bath movements e.g. Vortex
• the nozzle is designed as a slot nozzle slot nozzle for dispensing a sheet-like strand, high-quality sheets can be produced.
• several casting nozzles can also be arranged next to one another. In such a case it may be advantageous if the outlet of the intermediate container is connected to a distributor for several nozzles.
• the intermediate container is equipped with an upwardly directed nozzle, which communicates with the pump tube, so that a mold can be filled from below or an upwardly directed strand can be generated by means of the metallostatic pressure that is created by the level control in the pump tube, then can be placed appropriately Branches, a controlled mold filling from below (as in low-pressure casting) or an upward-directed nozzle for vertical continuous casting is fed upwards.
• the metal pumped up in the pump tube provides the metallostatic pressure for the filling of the mold (s) or the continuous feeding of the extruded strand.
• the pump tube can be heated if necessary.
• the mold filling speed can be adjusted by controlling the melt level in the pump tube (by means of a corresponding, continuously measuring level probe of a known type).
• the system has the great advantage that, in an emergency (breakthrough of the mold or strand), the melt is almost instantaneously switched off by switching off the pump ⁇
• the actual nozzle can be connected directly to the outlet as a component that is structurally separate from the intermediate container, in order to facilitate the setting up (orientation of the nozzle according to all three or at least two solid angles) and its maintenance.
• a leveling device is advantageously provided for this purpose. This set-up is also already made easier if the intermediate container can be adjusted in at least one spatial axis by means of a device, such as a carriage, a slide and / or a lifting device.
• the intermediate container can also serve to feed a distribution system for multiple strand casting.
• This system for a plurality of nozzles lying next to one another can also be designed such that it can be pivoted away and take over the function of the so-called hottop over individual molds, as is generally the case in vertical downward casting.
• Appropriate temperature control (heating or cooling) in the intermediate container can result in a partially solidified alloy suspension at the outlet.
• Their consistency can be controlled by grain refining agents or structure-influencing measures (e.g. sonication).
• the use of a metering pump to keep the level constant can have a particularly advantageous effect here because such a pump introduces shear forces into the melt and can thus ensure a fine globulitic structure. Above all, globulitic primary crystals are created in this way, which can possibly serve as seeds in a subsequent suspension section (such as the bottom leading to the outlet).
• a temperature control device in particular a heating device
• U.N- The “temperature control device” is understood to mean both a heating and a cooling device, the latter of which can be advantageous in some cases.
• a sensor preferably an inductive one
• Such a sensor can simply be a temperature sensor, because the temperature of the metal is a measure of its solidification.
• the sensor can also be an inductive sensor. Such a sensor and its effect is described for another training and application in US-A-5,601,743.
• Fig. 1 shows a section through a first embodiment to which
• Fig. 1a shows an embodiment variant, the cross section in the sense of the plane A-A of Fig. 1a in the
• FIG. 1B illustrates a particularly preferred storage of a metering oven designed according to the invention
• Fig. 2 shows a section similar to Figs. 1 and 1a through a further embodiment, to which the
• Fig. 2A illustrates a section along line A-A of Fig. 2;
• Fig. 5 shows another embodiment for mold filling or continuous casting upwards.
• a furnace chamber 1 with a crucible 1a, into which a molten metal 2, in particular a non-ferrous metal, such as aluminum or magnesium, is filled.
• the molten metal 2 can be connected via an opening 4 to an upstream chamber 3, via which the loading via a loading inlet 30 takes place in a manner known per se, advantageously until a level N 'sensed by a level sensor 11a is reached.
• the furnace chamber 1 is provided with a heater 5 (or several) which is only indicated. This furnace heater can be of any type known per se, for example gas heating.
• a line 6 may also be used in a known manner for the supply of a protective gas or for evacuation. If necessary, several such lines 6, 6a, 6b are provided.
• This metering pump is preferably designed as a so-called swelling pump, as has become known from US-A-5,908,488 or EP-A-1, 130,266.
• the pump tube 7 serves here as an inlet for an intermediate container 10 and preferably merges into the expanded intermediate container 10 on its upper side.
• This intermediate container 10 is also closed and can have line 6a or 6b corresponding to line 6.
• a level sensor 11 of a type known per se is connected with its output to a comparison stage 12 which receives a TARGET signal from a TARGET signal generator 13 and compares it with the ACTUAL signal supplied by the sensor 11. Accordingly, the metering pump 8 is controlled via a control stage 14, i.e. either the speed of the pump 8 can be regulated or the pump is switched off when the desired level is reached and then started again as soon as the level has dropped. Should a higher pressure be built up within the intermediate container via the protective gas lines 6a or 6b, this could either be measured within the intermediate container 10 with the aid of a pressure sensor built into it, or could also be entered directly into the comparison stage 12 from the protective gas source, for example as a correction value ,
• zugesellen which is switched on when necessary, for example in place of the metering pump 8, and conveys the molten metal from the intermediate container back into the crucible 1a.
• the pressure achieved by the metering pump 8 can be controlled or regulated within the intermediate container 10, in particular by means of a control circuit with a pressure sensor.
• the pump tube 7 ends at the underside at a height which is above the bottom 2a of the crucible 1a but below the upper level N 'contained therein. In this way, it is avoided that contaminants deposited on the bottom 2a or present as floating substances in level N 'enter the pump tube 7, which here is molded onto the intermediate container 10 as part of the latter.
• At least its outlet 15 should have one, as has already been explained above.
• This outlet 15 is preferably provided at the end of a sloping bottom surface 16 against the intermediate container 10.
• the slope of the bottom surface 16 is intended to ensure that, in the event of a business interruption, any melt present in this area flows back into the intermediate container and does not solidify in the outlet area.
• the angle ⁇ to a horizontal plane should be at least 4 °, but on the other hand should not be too steep. The angle is preferably at most 20 °. As shown in FIG.
• the angle ⁇ only needs to extend over part of the bottom surface 16. It is possible, for example, to provide a smaller angle ⁇ toward the outlet 15 or (which is not preferred) to make the angle ⁇ instead of falling to the left (as shown) to the right (based on FIG. 1). s
• the outlet 15 can, according to the invention, either be designed as a nozzle of a continuous casting device or with one (as in the case of FIG. 1a). Therefore, a transport device, in particular with at least one roller 18 (FIG. 1 a), is expediently assigned to it for the removal of the cast product 17. It is preferably a roller 18 that drives a metal conveyor belt 18a, such as copper, or a plurality of rollers. A lateral boundary, for example formed by a side wall 41, for the strip product 17 which has not yet cooled completely ensures a relatively smooth edge thereof. In the case of billets and slabs, other, conventional, roller or sideband constraints can of course be used.
• This transport device is advantageously associated with a cooling device in the form of spray nozzles 22, and a temperature control device 23 with a cooling device, but in particular with a heating device, is advantageously provided for the outlet 15.
• a cooling device in the form of spray nozzles 22, and a temperature control device 23 with a cooling device, but in particular with a heating device, is advantageously provided for the outlet 15.
• the nozzle 15 “freezing” in particular if the continuous casting product 17 is to be a sheet metal and the nozzle 15 is therefore designed as an elongated slot nozzle. The risk can also be particularly great if - for economic reasons alone mixing reasons, the melt in the intermediate container 10 is kept only slightly above the liquidus point, the base 16 possibly being used as a suspension section, as described in the German patent application 101 00632.
• a heating device 23 can be provided in the area of the outlet 15. It is advantageous not to control this heating by hand, but rather a sensor, advantageously an inductive sensor, such as that shown in FIG US-A-5, 601,743 is described, but if necessary merely to provide a temperature sensor 24, since the temperature of the metal or alloy is also a measure of the state of aggregation, in the case of the design according to US-A-5,601, 743 the windings of two induction coils arranged at an axial distance from one another around the metal body of the product to be monitored The output signal of this sensor 24 is fed to a comparison stage 25 which receives a TARGET signal from a TARGET signal generator 26. The difference signal thus obtained at the output of the comparison stage 25 is fed to a control stage 31, which controls the heating (or cooling) device 23 accordingly By determining the degree of solidification, the risk of “freezing” of the nozzle 15 or 115 can be determined.
• a structurally compact device is created in which a tundish is no longer necessary or is formed by the device and in particular its intermediate container 10 itself.
• the integration of furnace 1 or intermediate container 10 and continuous casting device also makes the access of oxygen more difficult or completely prevented, so that the quality of product 17 is increased.
• the entire device is less space and investment in this way.
• Fig. 1a is similar to Fig. 1, but has a nozzle 15a attached to the actual outlet 15, which is separate from the outlet and which is sealed off from the outlet 15.
• a feed line 6c for protective gas can also be provided here.
• the nozzle 15a which is lined with ceramics or graphite in a manner customary for continuous casting devices, is expediently provided with a lubricant line 32 in order not to leave any “chatter marks” on the metal strand when the surface, which is very large in volume, is cooled.
• conventional graphite lubrication can also be used.
• this leveling device 33 has a series of adjusting screws 34 on a support frame and, as a further adjusting device, a crank spindle 35.
• FIG. 1B Another aid for aligning the nozzle 15a is shown in Fig. 1B.
• the entire furnace chamber 1 stands with feet 36 on the pallet 37 of a lifting carriage 38, which is not only able to lift the pallet 37 but can also be moved along rails 39.
• the height of the nozzle 15a above the conveyor belt 18a (FIG. 1a) and the relative position of the nozzle mouth at the beginning of the conveyor belt or its effective length can be changed.
• a nozzle mouth 115 is provided, which is formed by an insert 40 for multiple strand casting, for example also billets or slabs, as can be seen particularly from FIG. 2A. If necessary, the nozzle 115 is also provided as a separate part or a part which can be swiveled about an axis a. If required, he can take over the function of the so-called hottop over individual molds. It would be conceivable, however, to provide several instead of a common intermediate container 10, each of which, for example, is assigned to one (or more) of the billets or slabs to be cast and is therefore connected in parallel. For other applications, however, a series connection of at least two intermediate containers can be advantageous. Fig.
• FIG. 3 shows another embodiment of the metering pump 8 of the intermediate container 10.
• its pump tube 28 is as the intermediate container 10 and its inlet 7 penetrating tube with a leading into the intermediate container 10 Opening 27 formed.
• the pump tube 28 is sealed in the inlet pipe section 7 by means of seals 29 and includes the mounting of the shaft 8a, which can be designed in the usual way for such shafts.
• a plate may be provided with such a bearing for the pump shaft 8a in a manner known per se.
• FIG. 4 shows an embodiment of the intermediate container 10, which allows the melt in the pump tube 7 to be conveyed so high that a mold 42, which is connected to the pump tube 7 by a connecting tube 43, preferably rising to the shape, is practically simultaneously can be filled.
• the measurement of the level N 'in the intermediate container 10 allows a suitable control (as is used in a similar form for low-pressure casting) to complete the mold filling in the desired time course.
• the pump tube can be heated so that the melt in it does not solidify and, after the melt solidifies in the sprue area 44 of the mold 42, can drop unhindered in the pump tube by switching off the pump motor 8.
• the solidification of the melt in the sprue area 44 the form 42 can be accelerated by a cooling device which starts at the desired point in time.
• Fig. 4a shows an embodiment similar to Fig. 4.
• a vertically upwardly acting continuous casting device with mold 44 and a schematically illustrated, upwardly acting pulling device 45 in the form of rollers 18 for the strand formed in the mold shown.
• FIG. 5 illustrates an embodiment variant which can be used both for mold filling and for continuous casting upwards.
• the pump 8 is used to pump metal into a mold or mold 42.
• an upward connecting pipe 43 is connected to the mold 42, which can optionally be designed in the manner of the molds for low-pressure casting. J2
• the melt 2 is located in the crucible 1a, which has a bearing block 47 on its bottom 2a. From the cover plate 46 of the furnace 1, an intermediate container 10 with a trapezoidal cross section is held down on the bearing block 47 by means of vertical struts 48. The intermediate container 10 is closed at the top by a cover plate 49 to which on the one hand the connecting pipe 43, on the other hand the pump pipe 7 'with suction holes 50 in the melt 2 and finally a level determination pipe 51 is connected.
• the crucible 1a heated by a heater contains the melt 2, which is first pumped via the suction holes 50 of the pump tube T into the intermediate container 10, which here plays the role of a pressure container , It is only through the metallostatic pressure built up in the intermediate container with the aid of the pump 8 that the melt 2 rises in the two tubes 43 and 51.
• the level determination tube 51 is somewhat higher than the shape 42, so that the level therein can be determined either visually or by means of a level sensor known per se.
• a compact casting unit is created, the other parts shown functioning analogously to the embodiments already discussed.
• this embodiment leads to a closure of the intermediate container against the entry of air without special precautions, without the need to supply a protective gas into the intermediate container.
• the cascade control could first switch on the heater 5 or that of the intermediate container 10 before it switches on that of the nozzle 15 or 115.
• this is not preferred.
• a closed intermediate container 10 separate from the chamber 1, can be used to simplify the furnace construction and to allow the loading directly into the chamber 1, which is due to the melt in the intermediate container 10 will have little influence.
• the additional chamber 3 can thus be dispensed with.
• a heating and / or sensor device for (manual or automatic) regulation of the outlet temperature at the outlet of a furnace or a continuous casting device is an independent invention, which can also be used where the outlet of the intermediate container is not simultaneously forms the nozzle of the continuous caster.
• the actuator is in the present preferred embodiment as one for regulating the heating windings 25, 26 is described, but a cooling device could also be regulated if necessary.
• a magnetic winding provided in the outlet or nozzle area can also impress a static magnetic field on the nozzle mouth in order to achieve a lifting of the strand from the inner surface of the nozzle.
• the device according to the invention can perform the function of the so-called hottop over individual molds.
• all those devices which are conventionally provided there for guiding the strand can be provided at the outlet of the respective nozzle 15, 15a or 115.
• two opposing belts of this type can also be provided (even in the case of horizontal continuous casting), as a result of which the cooling is intensified and the length of the conveyor belt 18a can be shortened.
• such two conveyor belts can initially converge downward, so that the sheet is definitely solidified at the lower end of the conveyor belts during casting. After casting, the two conveyor belts may then be brought from the convergent position into a position parallel to one another.
• the metering pump used in the invention can have any structure in itself. However, it is preferred - as shown - to equip this pump with a shaft which extends vertically into the melt. Suction pumps, piston pumps etc. could also be used, but the embodiment shown with a continuously operating pump, in particular a propeller pump, is most advantageous. LIST OF REFERENCE NUMBERS

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Continuous Casting (AREA)
• Encapsulation Of And Coatings For Semiconductor Or Solid State Devices (AREA)
• Control Of Vending Devices And Auxiliary Devices For Vending Devices (AREA)

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• 2002
  • 2002-01-21 DE DE10201983A patent/DE10201983A1/de not_active Withdrawn
• 2003
  • 2003-01-09 EP EP03729517A patent/EP1467828B1/fr not_active Expired - Lifetime
  • 2003-01-09 DE DE50305477T patent/DE50305477D1/de not_active Expired - Lifetime
  • 2003-01-09 WO PCT/IB2003/000040 patent/WO2003059554A2/fr active IP Right Grant
  • 2003-01-09 AU AU2003201059A patent/AU2003201059A1/en not_active Abandoned
  • 2003-01-09 AT AT03729517T patent/ATE343442T1/de not_active IP Right Cessation

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