Method for producing cast parts, and foundry plant

Abstract

The invention relates to a method for producing cast parts (1) from titanium-containing scrap metal (2) in a foundry plant (100) using an electrode (5) in a crucible (22a; 22b), in which method the electrode (5) and the scrap metal (2) are melted in a vacuum atmosphere in a smelting chamber (20) in the crucible (22a; 22b), wherein the scrap metal (2) is brought from at least one storage container (18) into the crucible (22a; 22b), wherein a crucible (22a; 22b) is used which has a cooled inner wall (55) at which components of the melted metal partially solidify, and wherein the liquefied metal is poured from the crucible (22a; 22b) into at least one casting mould (26) to produce the cast parts (1).

Description

[0001] Processes for producing castings and foundry equipment

[0002] Technical area

[0003] The invention relates to a method for producing castings by means of self-consumable electrodes and titanium-containing metal scrap in a foundry plant and to a foundry plant designed to carry out the method according to the invention.

[0004] State of the art

[0005] The production of castings from titanium-containing metal scrap and self-consumable electrodes in a foundry plant places special demands on the process management. In particular, it is desirable or desirable to completely dissolve the inclusions in the electrode and the titanium scrap, which have low or identical densities, such as titanium nitrides, as well as foreign particles with a relatively high density, when melting the metal scrap in the melt or to bind them by gravity segregation in an inert crucible so that they do not, or only to a limited extent, enter the castings. One possible approach is to melt the metal scrap in a crucible with a cooled inner wall.This process, which takes place under vacuum, causes the undesirable components of the liquid melt in the castings to either evaporate or dissolve, or those components with a higher density than the remaining components to sink into the melt pool and adhere to the shell of already solidified melt formed on the inner wall of the crucible in a liquid / pasty manner and become bound within the transient zone. Thus, when the remaining liquefied metal is poured, it cannot enter a casting mold or similar material, and thus also cannot enter the castings. The metallic shell that has solidified on the inner wall of the crucible is referred to in the art as the "skull."

[0006] Such a method is known from US 6,006,821 A. The known method, which has the features of the preamble of claim 1, is further characterized in that the metal scrap is fed or provided once from a storage container before the start of the production cycle. In other words, only a single storage container is arranged in the storage space, from which the scrap is removed during a process cycle. Furthermore, it should be mentioned that the foundry plant known from US 6,006,821 A1 only uses melting pots and thus also storage containers, which allow a maximum casting quantity of approximately 50 kg. The plant known from the cited document and the method used therein are therefore not designed to allow larger casting quantities or castings during a production process.It should also be noted that the handling of storage containers for metal scrap with increasing volume places ever greater demands on the machinery due to their increasingly larger size and increasing mass, including the larger mass of the scrap. Therefore, the amount of scrap stored in the storage container in other foundry plants for processing metal scrap is limited, typically to a few tons, for example, a maximum of 6 tons. Larger castings could therefore only be produced gradually, if at all, or through several consecutive production processes with intermediate evacuation processes within the foundry plant. This is not only time-consuming, costly, and energy-intensive, but also considered critical in terms of quality.

[0007] Disclosure of the invention

[0008] The method according to the invention for producing castings from titanium-containing metal scrap and a self-consumable electrode with the features of claim 1 has the advantage that it enables particularly high productivity in batch production of the castings in the foundry plant or the processing of large quantities of titanium-containing metal scrap into one or more castings.

[0009] The invention is based on the idea of ​​storing a relatively large quantity of metal scrap prepared for melting within a vacuum atmosphere required for processing to achieve the high quality of the castings. The metal scrap is stored in several storage containers. This allows metal scrap from the storage containers to be processed or refilled in portions into the melting crucible, while molten metal scrap is poured out of the crucible intermittently, until all of the metal scrap provided has been used up. This allows large quantities of metal scrap to be processed into castings in batches, in conjunction with an electrode with a correspondingly large volume or mass.In particular, the use of multiple scrap storage bins allows for the plant technology (drive and storage bin bearings) to be designed relatively simply, cost-effectively, and with low mass, while still allowing a large mass or quantity of scrap to be processed during a single production cycle, even to produce high-mass castings. Scrap with possibly varying titanium concentrations can also be stored in the storage bins, making it very easy to produce castings with different compositions by selectively selecting or using storage bins for individual castings, with the castings then being produced in different molds.

[0010] As a result, in practice, using a suitable foundry plant within a single production cycle, castings can be produced in multiple castings which can have a total weight of up to 18t, whereas with the prior art process it is usually only possible to produce one large casting with a much lower weight of a maximum of 6t. The quantities that can be withdrawn from the melting pot thanks to the multiple storage containers for the metal scrap are typically between 500kg and 2500kg, but in any case less than 5000kg, in order to enable easy handling and the low weight of the storage containers and melting pot. The weight of the castings produced is made up of the weight of the electrode and the weight of the metal scrap, reduced by the mass of the skull remaining in the melting pot. This skull can, if necessary,be processed or used as an electrode for a subsequent melting process.

[0011] Against the background of the above explanations, a method according to the invention for producing castings from titanium-containing metal scrap and a self-consumable electrode in a foundry plant with the features of claim 1 therefore provides that an electrode is used, that the metal scrap is stored in a storage room of the foundry plant in several storage containers, that the metal scrap from the storage containers is introduced into the melting crucible in partial quantities or portions, and that the quantities removed from the melting crucible each amount to more than 500 kg, preferably between 500 kg and 2500 kg.

[0012] By portions we mean that either the individual storage containers are emptied completely one after the other and / or that a partial quantity of the scrap contained in a storage container is removed successively from the storage container.

[0013] Advantageous further developments of the method according to the invention for producing castings from metal scrap containing titanium are listed in the subclaims.

[0014] As already explained above, it is particularly advantageous if liquefied metal from the melting crucible is poured into at least one casting mold at least between filling operations with the scrap metal from the storage containers. This allows the use of a melting crucible with a relatively small mass or volume, which reduces its handling in the melting chamber, particularly the requirements for the required drives, for example, for tilting the liquefied metal into the casting mold.

[0015] Furthermore, it is particularly preferred if the metal scrap or, if applicable, additives for correcting the composition of the metal components are deposited into the trough-like, elongated oval-shaped melting crucible during the melting process, next to the electrode immersed in the cross-section of the melting crucible. This has the advantage that the electrode does not have to be lifted or removed from the melting crucible to refill the metal scrap into the melting crucible, which simplifies handling and enables particularly easy refilling of metal scrap or additives.In particular, this means that the melting process in the crucible does not need to be interrupted while refilling with scrap metal. This is advantageous with regard to the desired melting process and the separation of undesirable components from the scrap metal, and can thus lead to improved quality of the castings. Furthermore, the elongated oval shape of the crucible has the advantage that a horizontal relative movement between the electrode and the crucible ensures a homogeneous temperature transfer into the metal, since the electrode can also be moved in the lateral (corner) areas of the crucible at a constant distance from the wall of the crucible.

[0016] A further, additional measure to improve quality involves agitating the molten metal in the crucible using an electromagnetic stirring device. This particularly promotes homogenization of the molten metal and improved dissolution of undesirable, low-density titanium nitrides in the melt.

[0017] The melting process can also be improved or optimized by moving the crucible horizontally beneath the consumable electrode during the melting process to homogenize the energy input via the electrode. This allows the electrode to gradually overlap the entire cross-section of the crucible, thus covering the scrap metal and the molten metal contained therein, and ensures a homogeneous temperature input into the metal.

[0018] A further, particularly preferred embodiment of the method provides for the vacuum atmosphere to be generated in at least two sub-areas separated from one another by a vacuum lock or similar device, wherein a first sub-area serves to accommodate the storage containers in the storage space and to form the melting chamber, and a second sub-area serves to accommodate the at least one casting mold in a casting chamber. This makes it possible to remove the castings produced in the casting chamber from the casting chamber by connecting them to the outside atmosphere and to introduce new casting molds into the casting chamber without having to remove the vacuum atmosphere in the melting chamber.

[0019] A further aspect of the invention relates to the requirement, particularly of the aerospace industry, for castings produced from molten metal scrap to reduce undesirable components from repeatedly melted metal. To this end, the invention provides for the castings to be produced using two electrodes: a first electrode, by means of which a first portion of the metal scrap is melted at the start of the process, and a second electrode, which is formed from a casting produced by the first electrode and the molten metal scrap in a melting crucible designed for this purpose, so that the material of the first electrode and the metal scrap is subsequently completely melted again by the second electrode.

[0020] Furthermore, the invention also encompasses a foundry plant, which is particularly designed for carrying out a method according to the invention as described so far. The foundry plant according to the invention has a melting crucible made of inert material and having a cooled inner wall for receiving metal scrap in a melting chamber. The inner wall encompasses both the area of ​​a bottom and that of a side wall of the melting crucible. Furthermore, a device for positioning a self-consumable electrode for melting the metal scrap and a storage space for receiving several storage containers for the metal scrap are provided. A casting chamber serves to accommodate at least one casting mold, which is used to receive liquefied metal from the melting crucible.Furthermore, the storage chamber, the melting chamber, and the casting chamber can be evacuated by means of a vacuum device, and the metal scrap can be transferred from one of the several storage containers into the melting pot by means of a feed device. The melting pot also has a size or volume that allows withdrawal quantities of more than 500 kg each, preferably between 500 kg and 2500 kg.

[0021] To improve the handling of casting molds in the casting chamber, at least the melting chamber and the casting chamber are separated or subdivided from each other by a vacuum lock or similar device for generating separate vacuum atmospheres.

[0022] A particularly homogeneous quality of the molten metal and thus also of the castings is achieved when the melting pot interacts with an electromagnetic stirring device for the molten metal.

[0023] The metal scrap stored in the multiple storage containers is preferably prepared for discharge into the melting pot by arranging the storage containers on a device that can rotate around an axis on a common pitch circle diameter. Thus, by rotating the device around the axis, the respective storage container to be emptied can be moved, for example, to overlap or close to the melting pot, or in operative connection with the transfer device, which can be designed as a downpipe, chute, or similar. Alternatively, rotary drum conveyors or vibrating conveyors can also be used.

[0024] In order to be able to produce multiple or different castings from the metal scrap, it is also preferred that several casting molds be arranged in a casting chamber, which can be positioned relative to the melting chamber by means of a platform. This allows the molten metal to be discharged into the respective casting mold simply by pivoting or tilting the crucible about a tilting axis.

[0025] As already explained at the beginning, the cooled inner wall of the crucible serves to ensure that the relatively dense components of the titanium-containing metal scrap and the electrode, which should ideally not be present in the castings, accumulate on the inner wall or adhere there. To prevent further, initially liquefied metal that is to be used for the castings from precipitating on the cooled inner wall or solidifying there, it is essential to pour the liquefied metal from the crucible into the casting mold as quickly as possible so that as much liquefied metal as possible is released from the crucible into the casting mold. To do this, it is necessary to first lift the electrode out of the area of ​​the crucible before tilting or swiveling the crucible.In order to make this possible as quickly as possible, a preferred development of the foundry plant provides that the electrode for lifting and / or immersing into the melting crucible is arranged so as to be adjustable by means of two separate drives, a first, electric motor drive for fine positioning of the electrode in the area of ​​the melting crucible for melting the metal scrap, and a second, hydraulic drive with a (significantly) increased lifting speed compared to the first drive.

[0026] Finally, a preferred structural design of the foundry plant comprises a melting chamber having a housing with an upper and a lower housing part, which, when connected to one another, form a diagonally extending parting plane. The upper housing part, together with the device for positioning the self-consumable electrode, is arranged so as to be adjustable in a housing part arranged laterally relative to the lower, stationary housing part and, in the lateral position, allows access to the melting crucible arranged in the lower housing part. This allows (easy) access to the melting crucible arranged in the lower housing part in the lateral position.

[0027] Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments of the invention and from the drawings.

[0028] Short description of the drawings

[0029] Fig. 1 shows a side view and a longitudinal section of a foundry plant for producing castings from metal scrap containing titanium with the aid of a self-consumable electrode, and Fig. 2 to Fig. 6 each show schematic representations of different, chronologically successive steps for producing castings by means of the foundry plant according to Fig. 1.

[0030] Embodiments of the invention

[0031] Identical elements or elements with the same function are provided with the same reference numbers in the figures.

[0032] The foundry plant 100 shown in Fig. 1 is used to produce castings 1, such as cast ingots, from titanium-containing metal scrap 2 with the aid of self-consumable metallic electrodes 5, which also contain titanium. The metal scrap 2 is preferably prepared in the form of chips or similar parts, shredded or crushed, in order to achieve the smallest possible gaps between the individual pieces of the metal scrap 2. The self-consumable electrode 5 contains titanium in a defined ratio to the remaining metal and can, for example, have a mass of up to 8 t. However, depending on the application, other masses or sizes of the electrode 5 are also conceivable.

[0033] The foundry plant 100 essentially has four functional areas 10 to 13. The first functional area 10 forms a storage space 16 for accommodating several, for example ten, storage containers 18 for the metal scrap 2. The second functional area 11, which is arranged laterally next to the first functional area 10, comprises a column-like device 19 for receiving or holding and positioning the self-consumable electrode 5. The third functional area 12, which is arranged below the second functional area 11 and laterally below the first functional area 10, forms a melting chamber 20 in which at least one crucible 22a, 22b is arranged. The at least one crucible 22a, 22b consists of an inert material, in particular copper. The fourth functional area 13, which is arranged below the third functional area 12, forms a casting chamber 24.At least one, preferably several, casting molds 26 are arranged in the casting chamber 24, particularly in the form of chills, which serve to form the castings 1 from the metal scrap 2 and the self-consumable electrode 5. The volume or size of the melting pot 22a, 22b is such that casting or withdrawal quantities of more than 500 kg, preferably between 500 kg and 2500 kg, but in any case less than 5000 kg, can be produced.

[0034] A vacuum atmosphere can be created both within the storage chamber 16 and within the melting chamber 20 and the casting chamber 24. For this purpose, these areas can be connected to a vacuum system 28, shown only symbolically in Fig. 1, with the necessary elements, such as control valves, lines, etc. Furthermore, a horizontally adjustable vacuum closure door 30 is arranged between the melting chamber 20 and the casting chamber 24. When opened, this door forms a passage opening between the melting chamber 20 and the casting chamber 24 for discharging molten metal from the crucible 22a, 22b into a casting mold 26. In the closed state of the vacuum closure door 30, however, the casting chamber 24 can be opened by means of a laterally movable holding device 31 for the casting molds 26 in order to remove the castings 1 or the casting molds 26 or to insert new casting molds 26, wherein the outside atmosphere then prevails in the casting chamber 24.At the same time, however, the vacuum atmosphere can continue to prevail in the melting chamber 20 and the storage space 16.

[0035] The holding device 31, with a side wall 32, forms part of a housing 34 of the casting chamber 24 and can be moved laterally in the direction of arrow 35 as shown in Fig. 1 to open the casting chamber 24. Within the casting chamber 24, there is a standing platform 38 that is rotatable about a vertically arranged axis 36, onto which the casting molds 26 can be placed by means of a lifting drive of the holding device 31 or can be picked up from the standing platform 38. The standing platform 38 serves to align a casting mold 26, which can be filled with the liquid metal, with the vacuum sealing door 30 and the melting crucible 22a, 22b.

[0036] Furthermore, the standing platform 38 can also optionally serve for the arrangement of additional elements for the casting molds 26, for example rotating devices, electromagnetic stirring devices or the like, as are known per se from the prior art.

[0037] The melting chamber 20 has a diagonally divided, box-shaped housing 40 consisting of two housing parts 41, 42. When connected to one another, the two housing parts 41, 42 form a diagonally extending parting plane 44. The lower housing part 41 is arranged in a stationary manner together with the housing 34 of the casting chamber 24. In contrast, the upper housing part 42, together with the storage chamber 16 fastened to the upper housing part 42 and the device 19 for the electrode 5 for making the interior 45 of the housing 40 accessible, is arranged so as to be laterally movable according to the arrow 46. In the interior 45 of the housing 40, the melting crucible 22a, 22b is arranged on a platform 50 that is horizontally movable in the direction of the double arrow 48 in Fig. 1. Furthermore, the platform 50 for pouring liquid metal out of the melting pot 22a, 22b is arranged to be tiltable about an axis running perpendicular to the plane of the drawing in Fig. 1 in the direction of the rotation arrow 52.The metal is discharged via a pouring funnel 53 aligned with the vacuum sealing door 30 (when the vacuum sealing door 30 is open) into a casting mold 26 aligned with the pouring funnel 53. The horizontal mobility of the platform 50 serves in particular to align the melting crucible 22a, 22b with the electrode 5, in particular also to optimize the melting process.

[0038] In the embodiment shown in Fig. 1, the melting crucible 22a has a round cross-section, the inner diameter of which is typically only slightly larger than the outer diameter of the electrode 5 immersible into the melting crucible 22a. In contrast, the melting crucible 22b in Figs. 2 to 6 has a trough-shaped cross-section with an oval, elongated, or rectangular cross-section, wherein its greatest inner length can, for example, correspond to twice the inner width. The inner width of the melting crucible 22b corresponds to the inner diameter of the melting crucible 22a. The elongated oval cross-section of the melting crucible 22b has two parallel side walls with semicircular edge regions.

[0039] Particularly when processing metal scrap 5 containing titanium, the melting crucible 22a, 22b is equipped with a cooling device (not shown) in the form of a water cooling system, which enables cooling of the inner wall 55 of the melting crucible 22a, 22b, in particular the bottom and a side wall of the inner wall 55 or of the melting crucible 22a, 22b, to a temperature below the melting point of the metal scrap 5. Such cooling devices on melting crucibles 22a, 22b are known per se from the prior art (US 6,006,821). As a result, during the melting process, undesired components of the metal scrap 2 and the electrode 5, which have a higher density than the remaining metal scrap 2, can be drawn into the castings 1 to be formed in the direction of the inner wall 55 orsink towards the bottom or accumulate on the side wall and solidify there into a shell-shaped metal layer 7, called skull, so that the material of the metal layer 7 is not poured into the casting molds 26 or does not reach the casting molds 26.

[0040] In addition, the melting crucible 22a, 22b can be arranged in operative connection with an electromagnetic stirring device 56 also located on the platform 50, in order in particular to achieve an increase in quality or homogenization of the molten metal.

[0041] The storage containers 18 for the metal scrap 2 arranged in the storage space 16 are preferably arranged on a carousel-like device 58, visible only in Figs. 2 to 6, which is rotatable about a vertical axis of rotation 59. This enables alignment of a storage container 18 to be emptied with a transfer device 60. The transfer device 60, which is shown in simplified form in Fig. 1, can be designed in the form of an inclined downpipe or a chute or similar device, which discharges the metal scrap 2 into the melting pot 22a, 22b by gravity in the direction of arrow 62.

[0042] The device 19 for receiving or holding and positioning the self-consumable electrode 5 has an electrode chamber 64 for receiving the electrode 5, which is connected to the melting chamber 20, so that a vacuum atmosphere also prevails or can be generated in the electrode chamber 64 by means of the vacuum system 28. The cylindrically shaped electrode 5 is connected to a lifting device 70 via a holding rod 66, which passes through the electrode chamber 64 in a sealed manner in the region of an upper wall 67. The lifting device 70 has two independently controllable drives 72, 74, both of which effect a stroke adjustment of the holding rod 66 and thus of the electrode 5. The first drive 72 is in the form of an electric motor drive and is used for fine adjustment orPositioning of the electrode 5 relative to the metal scrap 2 during the melting process, in particular also for generating and maintaining the arc for melting the metal scrap 2 when applying different voltage potentials to the electrode 5 and the metal scrap 2, as is known per se from the prior art and is therefore not explained further. The second drive 74 is designed as a hydraulic drive and enables a significantly greater lifting speed of the electrode 5 than the first drive 72, for example a lifting speed that is at least ten times greater than that of the first drive 72. The second drive 74 serves to lift the electrode 5 as quickly as possible out of the tilting area of ​​the melting crucible 22a, 22b before the liquefied metal is poured out of the melting crucible 22a, 22b, in order to avoid or minimize solidification of liquefied metal on the inner wall 55.

[0043] The operation of the foundry plant 100 described so far is explained below with reference to the sequence of figures in Figs. 2 to 6 using a trough-shaped, cooled melting pot 22b as follows: To prepare for the production process according to Fig. 2, the storage containers 18 in the storage room 16 are filled with the metal scrap 2, for example, by filling each of the ten storage containers 18 with 500 kg of metal scrap 2. The melting pot 22b is further filled with an initial quantity of metal scrap 2, for example, 1,200 kg. The electrode 5 is provided by the device 19. It has a mass of, for example, approximately 8,000 kg. The mass of the electrode 5 is adapted to the masses of the metal scrap 2 in the storage containers 18 and the melting pot 22b in such a way that the electrode 5 enables complete processing or melting of the entire metal scrap 2 during the production process.Also, for example, three casting molds 26 are provided in the casting chamber 24, two casting molds 26 for producing castings 1 or casting blocks each weighing 2,500 kg, and one casting mold 26 for producing a casting 1 or casting block weighing 8,000 kg.

[0044] The latter casting mold 26 for producing the 8,000 kg cast part 1 can also be used, in particular, to produce another electrode 5 from it. As a result, the material of this electrode 5 is melted again in a subsequent production process, which enables an improvement in the quality or material composition of cast parts 1, particularly with regard to the requirements of the aerospace industry.

[0045] As soon as the preparations described so far have been completed, the vacuum atmosphere is created in the storage chamber 16, the melting chamber 20 and the casting chamber 24 by means of the vacuum system 28.

[0046] Subsequently, as shown in Fig. 3, the electrode 5 is lowered into the melting crucible 22b to generate the arc, and the metal scrap 2 is melted by means of the electrode 5, whereby the scrap metal is partially consumed and its mass is reduced by, for example, 1,800 kg. During the melting of the metal scrap 2, in order to optimize the melting process, on the one hand, the electrode 5 is moved by means of the first drive 72, and on the other hand, the melting crucible 22b is moved horizontally by means of the platform 50 in order to achieve optimal coverage between the electrode 5 and the metal scrap 2. The electromagnetic stirring device 56, if present, can also be activated. During the melting process, on the one hand, components of the titanium that have a relatively high density and are undesirable in the castings 1 sink in the melting crucible 22b or solidify on the cooled inner wall 55 of the melting crucible 22b.On the other hand, relatively light, undesirable components of the titanium are dissolved in the molten metal by the optimized melting process.

[0047] As soon as the initial amount of metal scrap 2 has been completely melted, the electrode 5 is quickly lifted from the crucible 22b by means of the second drive 74, as shown in Fig. 4, and the liquefied metal is poured into one of the casting molds 26 by tilting the crucible 22b. Fig. 4 shows that a solidified metal layer 7 (skull), mainly containing the undesirable components of the titanium, remains in the crucible 22b, which was created by the cooled inner wall 55.

[0048] Thereafter, according to Fig. 5, metal scrap 2 is discharged from one of the storage containers 18 into the melting pot 22b, for example with the electrode 5 raised. Subsequently, the steps according to Figs. 3 to 5 are repeated until all storage containers 18 have been emptied or the castings 1 have been produced.

[0049] Fig. 6 shows the pouring of the last liquefied metal scrap 2 into the last casting mold 26. Furthermore, it can also be seen that the electrode 5 has been consumed, except for a final, unusable stump. It should also be mentioned that the filling of the melting crucible 22b from a storage container 18 after the pouring of liquefied metal scrap 2 is described and illustrated in the figures. However, it is within the scope of the invention, and it has even proven advantageous, to carry out the refilling of metal scrap 2 from the storage containers 18 at least partially during the melting process of the metal scrap 2 itself. For this purpose, in particular when using the melting crucible 22b, the electrode 5 can be moved by means of the platform 50 to the area of ​​a side wall of the melting crucible 22b, so that sufficient space or free space is created laterally for the discharge of metal scrap 2 from a storage container 18 into the melting crucible 22b.This means that the melting process does not have to be interrupted, but refilling can take place during the melting process itself.

[0050] The foundry plant 100 described so far and the methods for producing the castings 1 from the titanium-containing metal scrap 2 and titanium-containing electrodes 5 can be modified or altered in a variety of ways without deviating from the inventive concept. Thus, the use of the foundry plant 100 is not limited to the processing of titanium-containing metal scrap 2 and electrodes 5. Rather, other metals or other metal scrap 2 can also be processed in principle.

[0051] Reference symbol

[0052] 1 casting

[0053] 2 scrap metal

[0054] 5 Electrode

[0055] 7 metal layer

[0056] 10-13 Functional area

[0057] 16 Storage room

[0058] 18 storage containers

[0059] 19 Facility

[0060] 20 melting chamber

[0061] 22a,

[0062] 22b Melting Pot

[0063] 24 casting chamber

[0064] 26 Casting mold

[0065] 28 Vacuum system

[0066] 30 Vacuum seal door

[0067] 31 Holding device

[0068] 32 side wall

[0069] 34 housings

[0070] 35 Arrow

[0071] 36 Axis

[0072] 38 Standing platform

[0073] 40 housings

[0074] 41 , 42 Housing part

[0075] 44 Parting plane

[0076] 45 Interior

[0077] 46 Arrow

[0078] 48 Double arrow

[0079] 50 Platform 52 Rotating arrow

[0080] 53 Pouring funnels

[0081] 55 Interior wall

[0082] 56 Stirring device 58 Device

[0083] 59 axis of rotation

[0084] 60 transfer device

[0085] 62 Arrow

[0086] 64 Electrode compartment 66 Holding rod

[0087] 67 Wall

[0088] 70 lifting device

[0089] 72, 74 drive

[0090] 100 foundry plant

Claims

Claims 1. A method for producing castings (1) from titanium-containing metal scrap (2) and a self-consumable electrode (5) in a melting crucible (22a; 22b) made of inert material within a foundry plant (100), wherein the foundry plant (100) has a casting chamber (24) for arranging at least one casting mold (26) for receiving liquefied metal from the melting crucible (22a; 22b), wherein a storage space (16), a melting chamber (20) and the casting chamber (24) can be evacuated by means of a vacuum device (28) for producing the castings (1), wherein the electrode (5) and the metal scrap (2) are melted in a vacuum atmosphere in the melting chamber (20) in the melting crucible (22a; 22b), wherein the metal scrap (2) is fed from at least one storage container (18) into the melting crucible (22a; 22b) is introduced, wherein a melting crucible (22a;22b) with a cooled inner wall (55) is used, on which components of the molten metal partially solidify and form a metal layer (7), and wherein the liquefied metal is poured from the melting crucible (22a; 22b) into at least one casting mold (26) for producing the castings (1), characterized in that a self-consumable electrode (5) made of titanium is used, that the metal scrap (2) is stored in the storage space (16) of the foundry plant (100) in several storage containers (18), that the metal scrap (2) from the storage containers (18) is introduced into the melting crucible (22a; 22b) in portions, and that the metal scrap removed from the melting crucible (22a; 22b); Quantities of more than 500kg each, preferably between 500kg and 2500kg.

2. Method according to claim 1, characterized in that liquefied metal from the melting pot (22a; 22b) is poured from the storage containers (18) into the at least one casting mold (26) at least between some filling operations of the metal scrap (2).

3. Method according to claim 1 or 2, characterized in that the metal scrap (2) is discharged into the trough-like melting crucible (22b) having an oval elongated shape laterally next to the electrode (5) immersed in the cross-section of the melting crucible (22b) during the melting process or between the pouring into the at least one casting mold (26).

4. Method according to one of claims 1 to 3, characterized in that the molten metal in the crucible (22a; 22b) is moved by an electromagnetic stirring device (56).

5. Method according to one of claims 1 to 4, characterized in that the melting crucible (22a; 22b) is moved in a horizontal direction below the self-consumable electrode (5) during the melting process.

6. Method according to one of claims 1 to 5, characterized in that the vacuum atmosphere is generated in at least two partial areas separated from one another by a vacuum lock (30) or similar device, wherein a first partial area serves to accommodate the storage containers (18) in the storage space (16) and to form the melting chamber (20) and a second partial area serves to accommodate the at least one casting mold (26) in a casting chamber (24).

7. Method according to one of claims 1 to 6, characterized in that the castings (1) are produced by means of two electrodes (5), a first electrode (5) by means of which a first portion of the metal scrap (2) is melted at the start of the process, and a second electrode (5) which is formed from a casting (1) produced by the first electrode (5) and the molten metal scrap (2) in a melting crucible designed for this purpose, so that the material of the first electrode (5) and the metal scrap (2) is then completely melted again by the second electrode (5).

8. Foundry plant (100), preferably designed to carry out a method according to one of claims 1 to 7, comprising a melting crucible (22a; 22b) made of inert material and having a cooled inner wall (55) for receiving metal scrap (2) in a melting chamber (20), a device (19) for positioning an electrode (5) for melting the metal scrap (2), a storage space (16) for receiving a plurality of storage containers (18) for the metal scrap (2), a casting chamber (24) for arranging at least one casting mold (26) for receiving liquefied metal from the melting crucible (22a; 22b), wherein the storage space (16), the melting chamber (20) and the casting chamber (24) can be evacuated by means of a vacuum device (28), wherein the metal scrap (2) from one of the plurality of storage containers (18) can be transferred into the melting pot (22a; 22b) by means of a feed device (58, 60), and that the melting pot (22a; 22b) has a size or a volume for a discharge quantity of more than 500 kg, preferably between 500 kg and 2500 kg.

9. Foundry plant according to claim 8, characterized in that at least the melting chamber (20) and the casting chamber (24) are separated or subdividable from one another by a vacuum lock (30) or similar device for generating separate vacuum atmospheres.

10. Foundry plant according to claim 8 or 9, characterized in that the melting crucible (22b) is arranged horizontally adjustable in the melting chamber (20). 11 . Foundry plant according to one of claims 8 to 10, characterized in that the melting crucible (22a; 22b) cooperates with an electromagnetic stirring device (56).

12. Foundry plant according to one of claims 8 to 11, characterized in that the storage containers (18) are arranged on a device (58) on a common pitch circle diameter so as to be rotatable about an axis (59).

13. Foundry plant according to one of claims 8 to 12, characterized in that a plurality of casting molds (26) are arranged in a casting chamber (24) and can be positioned relative to the melting chamber (20) by means of a platform (38).

14. Foundry plant according to one of claims 8 to 13, characterized in that the electrode (5) is arranged to be adjustable in or out of the direction of the melting crucible (22a; 22b) by means of two separate drives (72, 74), a first, electromotive drive (72) for fine positioning of the electrode (5) in the region of the melting crucible (22a; 22b) during the melting process and a second, hydraulic drive (74) with a stroke speed which is increased compared to the first drive (72).

15. Foundry plant according to one of claims 8 to 14, characterized in that the melting chamber (20) has a housing (40) with an upper and a lower housing part (41, 42) which, when connected to one another, form a diagonally extending parting plane (44), and in that the upper housing part (42) together with the device (19) for positioning the electrode (5) is arranged so as to be adjustable in a housing part (41) arranged laterally to the lower, stationary part, and in the lateral position allows access to the melting crucible (22a; 22b) arranged in the lower housing part (41).

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