JP2002512889A - Method for treating molten metal, particularly light metal molten metal, and closed-type measuring and holding furnace pressurized with protective gas - Google Patents

Abstract

The invention relates to a method for processing a molten metal mass, especially a molten light metal mass, and a dosing furnace which is encapsulated and which can be pressurized by protective gas. The method should enable a quantity of molten mass to be exactly and quickly dosed for a successive casting process. The method provides that the quantity of molten mass corresponding to the gross second cast is fed to the coupled casting machine or casting mold by increasing the gas pressure in the dosing furnace. The increase of the gas pressure corresponds to the difference between the bath level of the molten mass and a level specified value in the casting machine or casting mold. The temperature of the molten mass is measured in the dosing furnace and is regulated at a preset temperature value. The level of the molten mass in the rising pipe and/or the bath height of the molten mass in the dosing furnace is/are measured and is/are regulated between preset limiting values. The gas pressure in the protective gas is regulated in the dosing furnace in such a way that, independent of the bath height in the dosing furnace, the level of the molten mass in the rising pipe is essentially the same before each feeding of the molten mass to the casting machine or casting mold. The dosing quantity and the casting temperature are maintained as manipulated and disturbance variables between selectable limiting values by the supplied heating capacities, the quantity of the fed charging material, and by the extracted quantity of molten mass. The casting process is carried out in the casting machine or casting mold under protective gas. The method is provided for processing molten metal masses which have to be melted under protective gas, e.g. magnesium.

Description

DETAILED DESCRIPTION OF THE INVENTION

The present invention uses a closed-type holding furnace connected to a casting machine or a mold via a riser tube and pressurized by a protective gas, and the casting machine or the mold is pressurized with a protective gas in the measuring-holding furnace. The present invention relates to a method for treating a metal melt, particularly a light metal melt, supplied with a quantity of the molten metal quantified by the method, and a measuring and holding furnace suitable for carrying out the method.

[0002] In practice, a large number of melting and dosing systems with mechanical or pneumatic feeders are known (see "Casting Dictionary" by E. Brunhuba, Schule and Schön Publishers, 1997). 17th edition, pp. 137-139), in which the handling of the melt takes place via a relatively long transport path in an mostly open atmosphere and is characterized by a free-falling melt pouring. ing. Such a system has the disadvantage that melt quality is degraded by melting loss, slag or oxide formation and gas occlusion and by strong fluctuations in casting temperature which negatively affect the reliability of the process and therefore the quality of the cast part. . Furthermore, the dosing accuracy of the melt is limited, which is disadvantageous both with regard to the quality of the cast parts and with regard to the economics of all manufacturing processes.

In the melting and low-pressure casting process according to DE 20 41 588, a mold to be connected directly to a riser is produced by means of a charging object from a melt vessel to a corresponding amount of casting material in a mold cavity. Of the melt, the melt level being kept constant during the melting and casting steps by means of a pressure-controlled protective gas filling.

A major disadvantage of this method is that high melting rates with constant casting temperature adjustment are hardly possible. The application of this method to low-pressure casting is limited, since metering by gas pressure regulation in conjunction with direct replenishment does not give the required metering accuracy. Furthermore, only specific rod-shaped charging bodies with suitable connecting elements can be used with this method.

German Patent Application DE 42 03 193 discloses a method for handling molten magnesium and magnesium alloys, in which the molten metal is introduced into a casting machine to be charged and into a protective gas volume on the surface of the molten metal bath. Supplied by generating overpressure. This overpressure is generated by opening a valve connecting the holding furnace to the pressure tank. The metering of the molten metal is carried out by measuring the weight of the supplied molten metal or the amount related thereto.
After the metering, the pressure equalization between the protective gas in the holding furnace and the protective gas in the casting apparatus takes place again, that is to say atmospheric pressure occurs when the casting is removed.

[0006] This solution has the disadvantage that the metering of the melt is still inaccurate and therefore the quality of the casting is inadequate.

The object of the present invention is to provide a method of the type mentioned at the beginning with a metallurgically reliable process operation, an accurate and rapid dosing of the quantity of molten metal required for the casting process and a casting process connected downstream. To improve the quality of the castings and to achieve an optimal connection to the casting. It is a further object of the present invention to provide a holding furnace suitable for this method.

According to the invention, it is provided according to the invention that a quantity of molten metal corresponding to the entire casting is supplied to the casting machine or mold by increasing the gas pressure in the metering and holding furnace to the casting machine or mold. The rise in temperature corresponds to the height difference between the bath level of the molten metal and the target level in the casting machine or mold, the temperature of the molten metal is measured in the weighing furnace and adjusted to a preset temperature value. The level of the molten metal in the riser and / or the bath level of the molten metal in the weighing furnace is measured and adjusted to a preset limit value, and the gas pressure of the protective gas in the weighing furnace is increased. Before each supply of the molten metal to the casting machine or the mold, the level is adjusted so that it is almost equal irrespective of the bath level in the holding furnace, and the amount of the molten metal and the casting temperature are controlled as operating and disturbance quantities. Heating power supplied, supply The amount and the melt volume is taken of the charging material, is kept between selectable limit values, the casting process is resolved by being carried out under protective gas in caster or a mold.

[0009] Preferably, the method is carried out by measuring the gas pressure of the protective gas in the holding furnace and adjusting it according to a preset function in relation to the bath level of the molten metal in the holding furnace. .

The present invention provides an early control of the disturbance amount of the whole process by connecting a regulating circuit for charging, bath level of the melt in the holding furnace, gas pressure on the bath surface in the holding furnace and temperature of the melt bath. Enable.

In that case, the precisely quantified amount of molten metal during the dosing of the molten metal into the subsequent casting process is reduced from the level below the bath surface of the measuring and holding furnace to the gravity by a slight disturbance via the riser pipe. Reaching into the casting machine or mold.

It is advantageous that the melt is additionally heated in the riser. Heating should be performed in a controlled manner by measuring the temperature of the molten metal in the riser and adjusting it to a preset temperature value by the heating power supplied to the riser.

The transport of the molten metal always takes place in a closed system via the shortest stroke, with the shortest transport time and under precisely regulated temperature conditions. The result is a highly reliable and controllable process required for the production of high quality parts.

[0014] The addition of the metal to the system may be solid, using alloy materials having properties guaranteed by the supplier, or using a clarified and treated melt whose properties are accurately set and documented. And can be performed on liquids.

It is particularly advantageous to use a metallurgically valuable continuous cast ingot that can be very easily integrated into the system and contains only impurities and oxides. When very high demands are placed on the quality of the part, the surface of the continuous cast ingot may be machined. However, with flexible sluices, all other conventional ingot formats can also be used.

The heat supply is adapted to the respective stage of the process and takes place in a minimum stroke to the heat flow with a constant amount of metal, guaranteeing optimal energy uptake and thus high efficiency.

All the heating types available for furnace technology are applied or combined, so that the most technically and economically significant solution is realized for the respective application.

When charging the solid alloy material, a precise quantification is performed by a defined feed adjustment, and a pre-heating determined by a regulated heating before the metal is immersed in the melt. Is done. Melting by immersion in a large bath of molten metal allows for strong heat transfer at the point where heat of melting must be provided. It is advantageous that the alloy material is first held by the guide so that no metal splashes occur as the alloy material enters the bath and the cold material does not sink directly below the melt bath. The charging device with the guide is preferably arranged in the furnace lid or on the upper side wall so that the uncontrolled falling of the alloy material into the furnace is prevented by self-locking.

When charging the liquid, a metered quantity of metal having a defined temperature is introduced below the bath surface, for example via a siphon. A liquid charge can also be applied in combination with a solid charge as a supplement, for example to add purified return material.

It is advantageous for the bath level to be maintained in the system under a protective gas atmosphere with an elevated pressure compared to atmospheric pressure. Thereby, the melt reaction, dissolution loss and impurities are effectively prevented. Since a low dead volume and a quantified make-up charge allow a reduction in the use of protective gas, more expensive gases such as, for example, argon can also be used. It is thus possible to omit environmentally harmful substances such as, for example, SF ₆ or SO ₂ .

Since the bath level in the dosing furnace is adjusted within a narrow range by means of continuous refilling, the feed height to the casting machine is kept small. This allows for a relatively low overpressure. Thus, simple and precise pressure control can be realized.

It is advantageous for the supplied charge to be preheated before it is put into the holding furnace. Here again, it is advantageous for the temperature of the charge to be measured and adjusted to a preset temperature value by the heating power supplied during the preheating.

During the dispensing of the molten metal, the removal of the molten metal takes place in the lower area of the bath via the riser tube with slight turbulence against the gravity, at which time the molten metal is just melted in the upper area of the bath. Metal is not guaranteed to be sent directly from the system.

[0024] The method is also carried out in such a way that the dosing chamber is filled with molten metal because of the time-independent dosing of the casting process, due to the fact that the front chamber to be placed in the casting machine or the mold is filled.

The individual control circuits can be connected to a programmable control device.

The circuit for adjusting the metering amount of the melt and the casting temperature in conjunction with the make-up charge allows very high metering with a constant casting temperature.

The efficiency of the holding furnace is clearly increased by incorporating energy into a substantially constant volume of the melt.

It is preferred that the heating of the molten bath is preferably carried out in the lower region of the crucible vessel, so that unacceptable overheating, heat and temperature differences in the bath are avoided by natural convection.
If resistance heating wires are used, they are distributed outside on the outer surface of a cylindrical measuring and holding furnace in order to obtain the high heating power required during melting and heat holding, or in a so-called immersion heating element Placed in

When higher power densities are required, induction heating, in which the efficiency is increased by the connection of a substantially constant melt volume, can be used advantageously. Since the use of a large number of coils results in a precise local power adaptation, the highest power is also obtained in the lower area of the bath if necessary. A particular advantage of the induction technology is that a variable frequency selection is possible to effectively set the power intake and bath movement.

The high melting capacity of induction heating allows for an ideal compact device with high flexibility, which is very suitable for use, for example, in a flexible production cell of a die casting machine.

Modern quality assurance requires a reproducible whole process of all manufacturing systems without uncontrollably affecting the process interface. Thus, a real-time regulated furnace process is realized by the method according to the invention. Other improvements include, for example, a metal surface sensor in the injection chamber of a die-casting machine, a laser level sensor on a feeder or other thermocouples, such that a regulating circuit including all furnace and casting processes is configured. This is achieved by a sensor in the casting machine.

The advantages obtained by the present invention, in addition to the high quality of the prepared melt, are, inter alia, the simple equipment technology, in a compact installation, from the preparation of the melt of the supplied material used to the optimal casting process. It includes that all issues up to the casting process during the connection are solved.

[0033] The high reliability of the process allows for an environmentally friendly automatic foundry with increased casting quality and low emission pollution.

According to the invention, a dosing furnace suitable for carrying out the method is, according to the invention, a replenishment charging device for a solid or liquid charging material and, via a regulator, a heating device acting on a heating device by means of a temperature (T _s ) acting on the thermocouple measuring the replenishment charging device via a regulator, a level sensor for the bath level (H) of the molten metal and / or a pressure generator for the protective gas via a regulator, A pressure sensor in the holding furnace and / or a level sensor in the riser which also acts in the event of a level sensor failure as a regulator for refilling.

The gas pressure regulator can then be designed such that the bath level of the molten metal measured by the level sensor in the holding furnace is given as a disturbance quantity. In this way, regardless of the respective bath level, the gas pressure is always maintained such that a specific bath level is formed in the riser pipe before each supply of molten metal to the casting apparatus. Alternatively, however, the gas pressure is also changed independently of the melt level in the riser pipe if it is measured here by means of a level sensor. In this case, the high gas pressure in the dosing furnace is used for adjusting the supply charge.

It is advantageous that the solid charging material replenishment charging device comprises a sluice provided with a tubular packing and a charging material feed drive which cooperates with a charging level sensor. It is.

The replenishment charging device for the solid charging material comprises a material chamber shiftable by a slider cylinder and a sluice with a feed device to an upper position of the material chamber controlled via a displacement sensor, a gas pressure And an adjusting device, wherein the material chamber may be fitted at its open end in its upper and lower positions with a slider which opens and closes alternately.

In an advantageous manner, support rails can be provided which are partially immersed in the melt and tied to the sluice, for self-locking and supporting the solid charge.

Preferably, the sluice is provided with a temperature-controlled heating device for the charge.

It is advantageous that the replenishment charging device for the liquid charging material comprises a molten metal container which can be connected to the injection pipe of the measuring and holding furnace, and the molten metal container is provided with a molten metal feeding device cooperating with the level sensor. It is.

To carry out a preferred variant of the method according to the invention, the riser is also provided with a temperature-controlled heating device for the molten metal.

The holding furnace may consist of a steel crucible as a basic element. For security reasons,
This may optionally be surrounded by a molten metal storage tank having an empty space for receiving the molten metal flowing out of the measuring and holding furnace.

In the case of induction heating, it is also possible, for example, to wrap the metal crucible with a ceramic block, which ensures good support and additional protection in case of crucible leakage.

The riser has at least the entire casting volume and preferably at least 3
It should have an inner diameter of 0 mm. Furthermore, the riser should be connected directly from below to the die casting machine or the injection chamber of the mold. This configuration guarantees an undisturbed feed of the melt during short transport runs and thus enables short dosing times with low temperature losses.

For a flexible connection to the die-casting machine, the holding furnace is such that a riser tube opens into the front chamber, which is connected to the injection chamber of the die-casting machine via a short tube. It may be configured. In this case, the front chamber may have an overflow port so that it always receives only a defined amount of molten metal.

According to another variant, the riser pipe is connected from below to the injection chamber of the die-casting machine and has a second connection channel opening into the injection chamber at the height of the intended injection level, The excessively large quantity of molten metal is automatically returned to the front chamber via.

In order to control the entire process, a central furnace controller may be provided, for example, in the form of a program-stored controller, wherein the central controller of the die-casting machine transmits signals for transmitting process parameters. It is connected to this central furnace control via wires.

Hereinafter, the present invention will be described in more detail with reference to Examples.

In the measuring and holding furnace shown in FIG. 1, a rod-shaped alloy material 1 is pushed through a sluice packing 4 of a sluice 5 by a feeder 3 adjusted via a displacement sensor 2. The sluice 5 has a heating device 6 for preheating the rod-shaped alloy material 1. A temperature sensor 7 measures the temperature of the alloy material 1, and the value of this temperature is provided to a regulator 8 which regulates the heating device 6.

In the crucible 9 there is a molten metal bath 10 heated by a resistance heating element 11.
The temperature sensor 12 in the molten bath 10 gives a measurement signal to the heating power controller 13. The alloy material 1 is guided slowly through the support rails 14 into the melt bath 10, which melts in the upper bath area.

The bath surface 15 is protected by a protective gas 16 from dissolution loss and oxidation. The protective gas 16 is always under a slight overpressure.

The level sensor 17 measures the height of the bath surface 15, and when the minimum level value falls below, causes the feeding device 3 to be recharged.

The connection to the casting chamber of a casting device, for example a die-casting machine, is made by a riser 18. The riser pipe 18 is also heated by a heating device 19. The heating device 19 is adjusted by a thermocouple 20 and a controller 21 to set a desired casting temperature in the molten metal.

The holding furnace is protected from large outward radiation losses by insulating walls 22.
In the event of a leak in the crucible 9, the molten metal flows into the storage tank 23 surrounding the crucible 9.

The gas pressure of the protective gas 16 on the bath surface 15 is measured by a gas pressure sensor 24, regulated by a gas pressure regulator 25 via a gas regulating valve 26 and measured by the gas pressure regulator 25 by a level sensor 17. The height of the bath surface 15 is superimposed. This is because the gas pressure on the bath surface 15 is affected by this.

In other words, before dispensing the molten metal to the casting device 27 connected at the subsequent stage, the specific height of the bath surface 15, the gas pressure of the protective gas 16 related thereto and the desired molten metal temperature are always maintained. And exists.

During the metering of the melt, the gas pressure is now adjusted between the bath level and the level setpoint in the casting machine as accurately as possible, corresponding to the metering quantity and the feed height to the casting machine. Is increased by the pressure difference corresponding to the level difference of

In some cases, the accuracy of the dosing is determined by the level sensor of the casting apparatus and the gas pressure regulator 25
Increased by feedback to

Prior to metering, the casting apparatus 27 was also filled with protective gas 16 so that all metering and casting processes were performed under protective gas.

FIG. 2 shows a measuring furnace having a crucible 9 to be induction heated. Since the melt reaches the interface to the casting device 27 via a vertical riser 18 which is mainly heated via the holding furnace, the additional heating device 19 is designed to be correspondingly small.

According to this variant, the level of the molten metal in the riser pipe 18 is measured by the level sensor 56 and, via the gas pressure in the measuring and holding furnace, it is substantially before each supply of molten metal to the casting apparatus. Adjusted to be equal.

The induction heating means 28 is regulated by the temperature sensor 12 and the heating power regulator 13 and allows for flexible power intake with variable frequency and independent coil drive. Good mixing of the melt bath 10 is achieved by the induced force action, which ensures that elution and precipitation at the bottom of the crucible 9 are avoided.

The crucible 9 is supported by a ceramic intermediate layer 29. This intermediate layer 29
Additionally provide good protection in case of crucible leakage.

In this case, the ingot-shaped alloy material 1 is preheated to a temperature determined by an independent heating device 6.

The ingot (possibly a number of aligned ingots) is slid straight into the sluice 30. At this time, since the slider cylinder 31 is at the lower position, the slider 32 opens and the slider 33 closes.

A brief protective gas flush after sliding the ingot into the material chamber formed between the sliders 32, 33 forces out the air brought with the ingot.

Next, the slider cylinder 31 moves to a center position where both openings of the sliders 32 and 33 are closed.

The pressure in the sluice 30 is raised to the same level as in the furnace chamber by the gas pressure regulator 34 and the gas pressure valve 35 for the sluice 30. Since the slider cylinder 31 moves to the upper position, the slider 33 is opened. Feeding device 3 is supporting rail 1
4. Put the ingot on 4 into the dissolution zone on the bath surface.

Next, the slider cylinder 31 returns to the center position, the overpressure in the sluice 30 is broken down again, and the protection gas 16 is recovered.

For rapid charging of the holding furnace, for example after a longer switch-off or after a failure, all the sluices 30 are fitted with mounting flanges so that the ingot can be put into the pressureless furnace very quickly. Disconnected from The shape of the sluice 30 is such that the hot protective gas 16 is trapped and retained in the upper part and only a small amount of air is drawn in during insertion of the ingot.

The adjustment and metering of the process parameters takes place in a manner analogous to the embodiment according to FIG.

FIG. 3 shows the temperature T _m , T _f1 , the melt temperature T _s of the alloy material 1 for the embodiment according to FIG.
3 shows the connection of a regulating circuit for the casting temperature T _g , the bath height H and the gas pressure P _g of the protective gas 16. The transfer function is generally denoted by F.

The molten metal in the molten metal bath 10 is reduced by the metering amount md, and the solid content is reduced by using a volume controller (in this embodiment, for example, the feed device 3 for the bar-shaped alloy material 1 according to FIG. 1). By supplying the charge m of the alloy material 1 or the charge fl of the liquid alloy material 1, the bath height H of the bath surface 15 which is adjusted to a predetermined limit value is determined.

As the amount of disturbance to the bath height H, a melt temperature T _s that changes strongly acts on this occasion. This change in melt temperature causes a different expansion of the melt bath 10.

Therefore, the molten metal temperature T _s is adjusted to a narrow limit temperature by the heating power controller 13.

The bath height H affects the gas pressure P _g of the protective gas 16 in the furnace chamber. This is measured by a gas pressure sensor 24 and is regulated via a gas regulating valve 26 and a gas pressure regulator 25, whereby the disturbance superposition causes the melt level in the riser pipe 18 to be adjusted before each dosing step. It is performed so as to be equal regardless of the bath height H of the molten metal bath 10 in the crucible 9. Due to the dispensing of the melt in the melt bath 10 by displacement and the feed by the riser pipe 18, the gas pressure P _g then temporarily corresponds to the required feed height and the amount of metering md to the casting apparatus 27. To be enhanced.

The metering accuracy is enhanced by the feedback of the metered amount of molten metal to the gas pressure regulator 25.

Since the molten metal temperature T _s also acts as a disturbance amount on the gas pressure P _{g in the} furnace chamber,
It is desirable as possible variations in the melt temperature T _s is small.

The casting temperature T _g is measured before or after the interface to the casting machine and is set precisely by the controller 8 of the heating device 19. Input amount when its is molten metal temperature T _s of the melt bath 10. This occurs as a complex function F in the melt bath 10 from the thermal energy taken in, depending on the regulated heating power of the temperature T _m or T _f1 of the alloy material 1 and the charge m or fl used. .

The temperature T _m of the solid alloy material 1 is set by heating adjusted by the controller 8 in the preheating process, starting from the ambient temperature T _mo .

FIG. 4 shows the transport container 37 in a side sectional view. The molten metal bath 10 below the bath surface 15 is supplied from the transport container 37 via the injection pipe 38 to replenish the molten metal with liquid. To this end, the feed channel 39 from the transport container 37 is tightly connected to the injection tube 38 by a releasable coupling 40. Liquid is refilled by the feed pressure regulator 41 until the level sensor 17 in the bath 10 of the measuring and holding furnace switches off at the maximum bath height H.

The transport container 37 is maintained at a temperature T _f1 determined by a heating controller 43 and a thermocouple 44 by an immersion heater 42 that is resistance-heated.

FIG. 5 shows an example of the synergistic action of the measuring and holding furnace with a die casting machine connected at the subsequent stage. A specific amount of magnesium is melted in the pressure-tightly sealed crucible 9 of the measuring and holding furnace. The crucible 9 is connected to a pouring chamber 45 of a die casting machine via a riser pipe 18 mounted in the lower area of the melt bath 10, followed by a die casting mold 46.

The space above the melt bath 10 is filled with argon extracted from the storage container 47. The injection chamber and die casting mold 46 are also filled with argon.

Since the inside of the injection chamber 45 and the inside of the metering furnace are initially at the same gas pressure, the molten metal surface in the riser pipe 18 remains below the inlet opening of the injection chamber 45. The gas pressure in the dosing furnace is increased to fill the injection chamber 45 and argon is displaced from the injection chamber 45 into the die casting mold 46. During the subsequent injection, the piston of the die-casting machine first moves over the opening of the riser pipe 18 into the injection chamber 45, after which the gas pressure in the metering furnace at least reduces the level of the molten metal in the riser pipe 18. Canceled until its departure state is reached again. The melt is then pumped by the piston into the die casting mold 46 and the argon is displaced from the die casting mold 46, whereupon the injection chamber is filled again with argon immediately after the injection has taken place, so that the riser The bath surface in 18 does not come into contact with air. After removing the casting from the die casting mold 46,
The die casting mold is again filled with argon.

All adjustment processes are performed by a central furnace controller 48. Furnace control device 4
Reference numeral 8 is further connected to a central control device 49 of the die casting machine via a signal line 50 for transferring process parameters.

The central furnace controller 48 implemented by the program storage controller controls the time progress of all processes in the set-up phase, including casting weight, solidification time, mold closing time, charging time, ingot format, Once the metering time, the required feed height, etc. have been determined, the individual control circuits can be individually tuned very flexibly, for example by means of programmed "IF-THEN" conditions.

For example, the following progress is regulated: 1) After each dosing step or after each xth dosing step, the charging process is started.
2) After each charging step, the heating power for the melt bath 10 is increased. 3) during a certain time after the arrival of a particular melt temperature T _s, replenishment charging is stopped. 4) If the metering is repeated too little, the production is interrupted and the reference operation is performed. As long as 5) bath surface is not located on the lowest level value, or as long as the melt temperature T _s is too low, the mold is opened and loading process is allowed to start.

FIG. 6 shows a modification of the connection between the die casting machine and the riser pipe 18. Immediately below the opening of the riser 18 is a front chamber 51 which is connected to the injection chamber 45 via a connection channel 53. In particular, the connection channel 53 is filled in such a way that after the piston of the die-casting machine has passed through the opening of the riser pipe 18, the excessively large quantity of molten metal automatically flows back into the front chamber 51. Chamber 4
5, in which case the gas pressure in the holding furnace is canceled the moment the piston has passed. The opening of the connection channel 53 in the injection chamber 45 must therefore be located where the injection level corresponds as closely as possible to the metering amount of a single injection.

FIG. 7 shows another modification of the connection between the die casting machine and the riser pipe 18. The riser pipe 18 is connected to a heated and closed front chamber 51 via an overflow port 54. In this case, the volume of the front chamber 51 exactly corresponds to the amount of one shot. Tube 52 starting from the injection chamber 45 of the die casting machine
Are immersed in the front chamber 51. The connection to the injection chamber 45 is thus somewhat flexible. The injection in the injection chamber 45 is performed via the protective gas pipe 55 due to the pressure difference between the front chamber 51 and the injection chamber 45 after the gas pressure in the metering furnace is canceled.

[Brief description of the drawings]

FIG. 1 is a sectional view of a weighing furnace with a refill charge in the form of a rod.

FIG. 2 is a cross-sectional view of a measuring and holding furnace having a crucible to be induction-heated.

3 shows a block diagram of an interconnected regulating circuit for the temperature, bath level and gas pressure of the holding furnace according to FIG. 1;

FIG. 4 is a sectional view of a measuring and holding furnace and a transport container for replenishing and charging a liquid.

FIG. 5 is a schematic view showing a weighing and holding furnace together with a casting machine attached at a later stage.

FIG. 6 is a schematic diagram showing a modification of the connection between the measuring and holding furnace and the injection chamber of the die casting machine.

FIG. 7 is a schematic view showing a second modified example of the connection between the weighing furnace and the injection chamber of the die casting machine.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 alloy material 3 feeder 4 sluice packing 5 sluice 6 heating device 7 temperature sensor 8 controller 10 molten metal 11 resistance heating element 12 temperature sensor 13 heating power controller 14 support rail 15 bath surface 16 protective gas 17 level sensor 18 riser pipe 19 heating device 20 thermocouple

──────────────────────────────────────────────────続 き Continuation of front page (81) Designated country EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, IT, LU, MC, NL, PT, SE ), OA (BF, BJ, CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, GM, KE, LS, MW, SD, SL, SZ, UG, ZW), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AL, AM, AT, AU, AZ, BB, BG, BR, BY, CA , CH, CN, CZ, DE, DK, EE, ES, FI, GB, GE, HU, IL, IS, JP, KE, KG, KP, KR, KZ, LK, LR, LS , LT, LU, LV, MD, MG, MK, MN, MW, MX, NO, NZ, PL, PT, RO, RU, SD, SE, SG, SI, SK, TJ, TM, TR, TT, UA, UG, US, UZ, VN (72) Inventor Khan, Joachim Germany 35960 Ehringshausen Mülbachstraße 2F Term (Reference) 4E014 LA09 LA12 LA18 I do.

Claims (34)

[Claims] 1. A closed-type measuring and holding furnace connected to a casting machine or a mold via a riser tube and pressurized by a protective gas is used, and the casting machine or the mold is fixed by pressurizing the protective gas in the measuring and holding furnace. In a method for treating a molten metal, particularly a light metal melt, supplied with a reduced amount of molten metal, an amount of molten metal corresponding to all castings is supplied to a casting machine or a mold by increasing a gas pressure in a measuring and holding furnace. The rise in gas pressure corresponds to the height difference between the bath level of the molten metal and the level setpoint in the casting machine or mold, the temperature of the molten metal is measured in a weighing furnace and a preset temperature value is reached. The level of the molten metal in the riser and / or the bath level of the molten metal in the measuring furnace is measured and adjusted between preset limits, and the gas pressure of the protective gas in the measuring furnace is adjusted in the riser. Molten metal level is casting Prior to each supply of the melt to the machine or mold, it is adjusted to be approximately equal irrespective of the bath level in the dosing furnace, the metering amount of the melt and the casting temperature are supplied as operating and disturbance quantities. Metals characterized by the fact that the heating process, the amount of charge supplied and the amount of melt removed are kept between selectable limits and the casting process is carried out in a casting machine or mold under protective gas. A method for treating molten metal, especially light metal molten metal. 2. The gas pressure of the protective gas in the holding furnace is measured and adjusted according to a predetermined function as a function of the bath level of the molten metal in the holding furnace. the method of. 3. The method according to claim 1, wherein the molten metal supplied to the casting machine or the mold is heated in a rising pipe. 4. The method according to claim 3, wherein the temperature of the molten metal in the riser is measured and adjusted to a preset temperature value by heating power supplied to the riser. 5. The process as claimed in claim 1, wherein the supplied charge is preheated before it is introduced into the holding furnace. 6. The method according to claim 5, wherein the temperature of the preheated charge is measured and adjusted to a preset temperature value by heating power supplied during the preheating. . 7. The method according to claim 1, wherein the molten metal is induction-heated. 8. The method according to claim 7, wherein the heating power is frequency adjusted. 9. The bath level of the molten metal is adjusted between a maximum level value and a minimum level value during the charging of the solid alloy material so that the variation in the volume of the molten metal is at most about 2%. The method according to one of claims 1 to 8, characterized in that: 10. The bath level of the molten metal is adjusted between the highest level value and the lowest level value during charging of the liquid alloy material, so that the variation of the molten metal volume is at most about 50%. The method according to one of claims 1 to 8, characterized in that: 11. The method as claimed in claim 1, wherein the gas pressure in the holding furnace is always maintained above the external atmospheric pressure. 12. The method as claimed in claim 1, wherein the solid alloy material is held in the upper region of the melt during charging. 13. The method according to claim 1, wherein the melt is always supplied against gravity. 14. The method as claimed in claim 1, wherein the front chamber to be placed in the casting machine or the mold is filled with molten metal for metering in a time-independent manner in the casting process. Method. 15. The method as claimed in claim 1, wherein argon is used as protective gas. 16. The method as claimed in claim 1, wherein the individual control circuits are connected to a programmable control device. 17. A closed-type holding furnace which is connected to a casting machine or a mold (27) via a riser pipe (18), is provided with a heating device (11, 28), and is pressurized by a protective gas. In order to carry out the method according to one of the claims 1 to 16, a replenishment charging device for a solid or liquid charging material (1) and a heating device (11, 28) acting via a regulator (13) on a heating device (11, 28) Temperature (T _s )
Acting on the replenishment charging device via a thermocouple (12) and a regulator (3), via a level sensor (17) for the bath level (H) of the molten metal and / or via a regulator (25) Pressure sensor (24) in the holding furnace and / or which also acts on the pressure generator for the protective gas (16) and, in the event of a failure of the level sensor (17), on the regulator (3) for refilling. Or a level sensor (56) in the riser pipe (18). 18. The controller according to claim 1, wherein the bath level of the molten metal measured by the level sensor is supplied to the controller as a disturbance amount.
7. The measuring and holding furnace according to 7. 19. A charging device for replenishing a solid charging material (1), wherein the charging device cooperates with a sluice (5) provided with a tubular packing (4) and a level sensor (17). 19. The measuring and holding furnace according to claim 17, further comprising a feed drive section (3) according to (1). 20. Material chamber in which a replenishment charging device for a solid charging material (1) is controlled via a material chamber (36) shiftable by a slider cylinder (31) and a displacement sensor (2). A sluice (30) with a feed device (3) for the upper position of (36) and a gas pressure regulator (34, 35), the material chamber (36) having an open end in its upper and lower positions. 19. The holding furnace according to claim 17, further comprising a slider (32, 33) which is alternately opened and closed. 21. A support rail (25) partially immersed in the melt and connected to the sluice (5, 30) for self-locking and supporting the solid charge (1).
21. The measuring and holding furnace according to claim 17, further comprising (14). 22. The metering device according to claim 17, wherein the sluice (5, 30) is provided with a temperature-controlled heating device (6) for the charge (1). Holding furnace. 23. A replenishing charging device for a liquid charging material (1) comprises a molten metal container (37) connectable to an injection pipe (38) of a measuring and holding furnace, the molten metal container comprising a level sensor (17) and a molten metal container. 19. The measuring and holding furnace according to claim 17, further comprising a synergistic molten metal feeder. 24. A heating device in which a riser pipe (18) is temperature-controlled for molten metal.
24. The measuring and holding furnace according to claim 17, further comprising (19). 25. The holding furnace according to claim 17, wherein the crucible of the holding furnace is made of steel. 26. The measuring and holding furnace according to claim 25, wherein the steel crucible (9) is arranged in the molten metal storage tank (23). 27. The steel crucible (9) with induction-heated refractory material (29) is placed in an induction heating means (28).
6. The measuring and holding furnace according to one of 6. 28. Weighing furnace according to one of claims 17 to 27, characterized in that the riser pipe (18) has a volume of at least the entire casting. 29. The holding furnace according to claim 17, wherein the riser has an inner diameter of at least 30 mm. 30. The riser pipe (18) is connected directly from below to a die casting machine or a casting chamber (45) of a mold.
9. The weighing and holding furnace according to one of 9. 31. A riser pipe (18) opens into the front chamber (51), which is connected to the injection chamber (45) of the die casting machine via a short pipe (52). 31. The weighing and holding furnace according to any one of claims 17 to 30. 32. The holding furnace according to claim 31, wherein the front chamber (51) has an overflow port (54). 33. A riser pipe (18) is connected from below to the injection chamber (45) of the die casting machine and has a second connection channel opening into the injection chamber at the height of the intended injection level. A measuring and holding furnace according to any one of claims 17 to 32. 34. The central control unit (49) of the die-casting machine is connected to the central furnace control unit (48) via signal lines (50) for transmission of process parameters. 34. The weighing furnace according to any one of 17 to 33.