DE1458134A1 - Method and apparatus for removing molten metal from a container - Google Patents

Description

BBC ■ -

BROWIf ₉ BOTERI & ΟΙΕ

Aktiengesellschaft Mannheim, 24 * 8.1962

Mannheim Pat / Ld / W

Mp.no. 701/62

Method and device for removing molten metal from a container «, ■

The Gießen.von standard parts made of metal, especially light metal, is often done in such a way that the molten metal is removed from a container, Z ₀ B _{8, from} the crucible of a melting or holding furnace with the help of a suitable pump device and fed to the casting molds in the appropriate amount "If the same standard parts are being cast, the meta, quantity required to cast each part is always the same

If the same parts are to be cast in large numbers, special precautions are expediently taken through which the removal of the same amount of metal is ensured in the simplest possible way The fact that the level of the melt pool and thus the height by which the liquid metal is raised when it is removed must, during the pouring of the contents of the crucible, constantly changes »

The main pumping devices that come into consideration for the stated purpose are? The introduction of pressurized gas into the gas-tight sealed crucible or a part thereof, whereby the metal is pressed through a riser pipe upwardly "Further, pumps can be used, the pumping action beruh on dynamic force effects. *» Ζ, as centrifugal pumps and eventually come electromagnetic Pumps, for example those in which the liquid metal is moved under the action of a traveling magnetic field, should be considered. With all of these pumping devices, the amount of the time unit conveyed depends to a considerable extent on the pressure to be overcome, ie in the present Pail on the level of the ₍ bath level in the crucible.

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In an arrangement in which this introduction of pressurized gas in If the closed crucible is used as a pumping device, it is already known that the same withdrawal quantities can be maintained by the respective duration of action of the compressed gas with sinking bathroom level, each time is reduced by the same amount of time.

the

is lengthened. In this way, with any pressure Keep the amount of metal removed constant, but take the times required for the individual removals with increasing head. This is particularly disadvantageous if the potting is carried out automatically should be, for example, in such a way that the molds in a predetermined rhythm under the outlet opening of the Ford err ear it be led through «.

In a method for removing molten metal from a container serving to hold the metal, for example from the crucible of a metal melting or holding furnace from which the metal is conveyed via a riser by means of a pump device, this disadvantage is avoided according to the invention in that the The filling level or the level of the metal bath in the container is measured and, as a function of this measured value, the output of the pumping device is automatically changed so that the same amounts of metal are always conveyed at the same times during the entire removal process _e

The determination of the bath level can be done in different ways, For example, a float arranged in the crucible can be used to control the power of the Pump device controls »Another possibility is to to arrange the crucible on a weighing device and the change in the bath level from the change in the crucible weight to investigate.

Of the above-mentioned arrangements referred to as the pumping device Above all, mechanical devices, such as centrifugal pumps ^ are suitable for the intended purpose »also electromagnetic« Pumps, provided they are in the entire

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Depending on the situation of the individual case, insert the information well. the Promotion of the liquid metal by means of pressurized gas let into the closed container is not very suitable because a Changing the pressure in the closed container can only be achieved with a considerable delay, which is all the more becomes larger, the larger the volume not filled with metal, of the container.

Various devices are shown in the drawings, with which the method according to the invention can be carried out.

1 represents the crucible of a melting or holding furnace. The liquid metal contained therein is pumped out with a centrifugal pump 2 taken via a riser 3. In the example of FIG. 1, a compressed air motor 4 is used to drive the pump, which is fed from a compressed air tank 8 o

A float 5 controls depending on the level of the liquid metal The throttle valve 8 is controlled via a drive device 6, which can consist, for example, of a toothed rack and a toothed wheel and thus the performance of the engine 4. By appropriate design The transmission device 6, for example by switching on cams or the like. Can without Another such functional dependency of the DurohlaB opening of the valve 8 can be achieved by the float position that the amount of metal conveyed by the pump 4 per unit of time remains constant regardless of the pressure height h. Under the circumstances, it may be appropriate to run parallel to the valve 8 to arrange a lifting path indicated by dashed lines in the drawing with a fixed throttle valve 10. By . Opening the shut-off valve 9 for the same times, compliance with ZoB. can be ensured by a time relay, the same amounts of metal are then always removed from the container 1.

A slightly different device according to the invention is in the lig. 2 shown. Here, an electric motor 4 ^{1 is} provided to drive the pump 2, which is generated from a power source 12.

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feeds isto To determine the amount of metal or the metal level In the container 1 there is a weighing device 11 which, depending on the weight on it, a resistor 13 or introduces another actuator *

By suitable subdivision of the resistance, auoh here such an adaptation of the speed of the pump 2 to the respective delivery head achieve that the Fördeimegeje time unit remains constant

Another embodiment is based on the Pig. 3 explained will.

To ensure that the constant flow rate is adhered to as precisely as possible To achieve, it is useful that the liquid metal before the start of each removal process up to one certain mirror height S is pushed up in the riser, so that at the beginning of the removal only a short and constant The way to the outflow end of the pipe ^ is to be covered. In addition, such a measure, especially when casting magnesium and magnesium alloys, has a special effect Gate part. As is well known, magnesium has a very high affinity for oxygen and tends to have a higher affinity when air is exposed to it Temperature to burn, the molten magnesium is therefore to prevent the entry of oxygen, with a Salt covered or kept under protective gas

Both measures can, however, in a riser pipe, whichever the magnesium is pumped, cannot be made sufficiently effective, so that deposits of magnesium oxide in the riser pipe which reduce the free pipe cross-section, i.e. can lead to an overgrowth of the pipe. This phenomenon is limited to a short, easily replaceable piece of pipe, if the metal is always up to a constant level S in the pipeline.

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In order to achieve this state ₉ , the pump 2 must be operated with a relatively low power, which is largely dependent on the height of the bath level in the crucible, and which is referred to below as the holding power the mirror height in the pipe required »

Various methods are known for measuring the height of the liquid level in a non-transparent pipe, with the measured values being able to serve more or less effectively as actual values for a regulation _e

It is particularly useful to determine the level of the metal proved in the riser 2 with the help of hard X-rays, for which in particular ^ rays come into question, the emitted by radioactive isotopes.

If one wanted to send these rays through the pipe perpendicular to its longitudinal axis, then in many cases the amount of rays penetrating through the pipe would change very little compared to the empty state when the pipe is filled with molten metal. The control of a control device is then hardly possible »This is Z ₀ B in particular« the case with normal steel pipes through which magnesium is conveyed. Rays is to take place, is significantly widened. However, it is more expedient to use a tube that is bent twice and stand vertically in between and to introduce the rays in the axial direction through the vertical piece. "

Riser pipe 3 is outside the container 1 between two approximately right-angled bends a piece of perpendicular out, as shown at 3 '.

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From a radiation source 14, ζ "Β" one located in a NaOH open at the bottom lead the capsule radiating isotope, rays therethrough sent through the tube piece 3 ¹ and in each of the height of NaOH of the metal located in this Eohrstüok more or less strongly absorbed Because of the beam The liquid column passing through can be selected to be much larger than the thickness of the tube walls, so by changing the liquid level S there are considerable changes in the absorption receiving apparatus 15 converted into an electrical ffrö'Sö ™ ₉ converts which updates the Flüssigkeitsspiegela S sufficiently _s changes to thereafter the holding power of the motor 4 * and the pump 2 of known, not shown aid in the sense of keeping constant the level height S while to be able to regulate the times between the individual metal withdrawals "

During the removal of liquid metal, the regulation of the holding power is put out of action and the power the pump is controlled, as previously described, depending on the height of the bath level in container 1 «

The invention is not tied to the exemplary embodiment described, but can be modified in many ways will. In particular, the described measuring devices and pumping devices should be replaced by devices that are the same or have a similar effect

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Claims (8)

_ 7 - 1 <»Upper Austria I tt patent claims: 1. Method for removing molten metal from a container used to hold the metal, for example from the crucible of a metal clay furnace or holding furnace, from which the metal is conveyed via a riser by means of a pump device, characterized in that, that the degree of filling or the metal bath level in the Measured in the container and, depending on this measured value, the output of the pump unit is automatically changed is that during the entire removal process always equal amounts of metal are conveyed at the same time. 2 device for performing the method according to claim 1, characterized in that a float is provided for measuring the height of the bath level which is mechanical and / or electrical transmission equipment controls the performance of the pump unit. 3. Device for carrying out the method according to claim 1, characterized by a measuring device which measures the weight of the container with the molten metal and which, via mechanical and / or electrical transmission device known per se, corresponds to the respective filling level of the container as a function of the measured The relevant weight controls the performance of the pump unit. 4 »Device according to claim 2 or 3, characterized in that for conveying the molten metal from the container in a manner known per se a mechanical arranged in the container below the bath level, after dynamic principle working rotating pump is provided, and control means through which the speed of the pump motor and so that the delivery rate of the pump can be changed 909805/0519 - 8th - . 701/62 5.- Device according to claim 2 or 3 * characterized in that that a known electromagnetic pump, E.g. eddy current pump, for pumping the molten liquid Metals, from the container is used and control means are provided through which the drive power of the electromagnetic Pump can be changed 6. Device according to one of claims 2-5 »marked by means of a control device, which regulates the liquid level during the times between metal withdrawals keeps constant in the metal pipe at a level little below the outlet opening of the riser pipe. ™ 7. Apparatus according to claim 1, characterized in that the determination of the metal bath level in the riser is carried out with the aid of a source of radioactive radiation, preferably a radiating isotope ₉ , the rays of which are converted into an electrical variable after penetrating the riser in a receiving device, which in turn controls the power of the pumping device (holding power) in the sense of keeping the mirror height constant in the riser pipe 8. Apparatus according to claim 7, characterized by a such an arrangement of the riser pipe and the source radio- / diaS d ± .e rays
active S trahlei ^ after starting one between two \ Bends in the riser pipe, which is approximately perpendicular, to the receiving device. 909805/06 19 bath