Apparatus and method for producing metal strips and / or metal fibres

Abstract

The invention relates to an apparatus (1) for producing metal strips and / or metal fibres, comprising at least one production chamber (2), at least one reservoir (3) for the metal to be processed, at least one nozzle (4), at least one movable, preferably rotatable region (5), and at least one collection apparatus (6). The invention is characterized in that at least one passive cooling structure (15) having an enlarged surface is provided on an underside (5b) of the movable region (5) facing away from the surface (5a) of the movable region (5). Alternatively, the invention relates to an apparatus (1) for producing metal strips and / or metal fibres, comprising a coaxial drive. The invention further relates to a corresponding method with passive cooling.

Description

[0001] title

[0002] Device and method for producing metal strips and / or metal fibers

[0003] Description

[0004] The invention relates to a device for producing metal strips and / or metal fibers according to the preamble of claim 1 and to a method for producing metal strips and / or metal fibers according to the preamble of claim 13.

[0005] A well-known process for producing metal ribbons and / or metal fibers is melt spinning. Melt spinning is a metalworking technique in which molten metal impacts a moving surface, causing the metal to expand and solidify.

[0006] Typically, the molten metal is deposited onto a rotating roller or plate, which is then cooled. The process is usually carried out in a vacuum or under process gas.

[0007] Various melt-spinning processes are known from the prior art. For example, one such process is described in WO 2020 / 229400 A1.

[0008] Typically, in melt spinning, the metal is first melted in a reservoir (also called a crucible). The molten metal is typically directed from a nozzle at the bottom of the reservoir as a jet of molten metal onto a rotating surface, such as a rotating cylinder or rotating plate. Once the molten metal touches the rotating surface, it is entrained by the rotation and simultaneously cooled by contact with the surface.

[0009] This causes metal bands or metal fibers to form and the molten metal to solidify.

[0010] In previously known melt spinning systems, the rotating surface is usually actively cooled with water to achieve rapid cooling of the molten metal when it hits the surface and to ensure that the surface temperature of the rotating surface remains consistently low during operation. The water cooling is usually designed in such a way that water is forced through the axis of the rotating surface from outside the production chamber, and thus from outside the process conditions, through vacuum seals and the rotating surface is washed around from the inside or below. This places high demands on the axis, particularly with regard to a certain minimum thickness, and makes multiple sealing stages of the water circuit and the axis necessary against the vacuum in the production chamber. The required minimum thickness of the axis results in an increased radial speed at the vacuum seal and leads to imbalances, e.g.through deep holes in the axis for the cooling water or air bubbles in the water. The correspondingly higher rotational speeds lead to high pressure on the outside of the rotating surface, which stresses the seals due to the centrifugal force acting on the water column. Furthermore, a minimum pressure is required for the cooling circuit. This is because the water must flow from the outside to the inside, which at high speeds represents a significant pressure drop due to the centrifugal force.

[0011] The invention is therefore based on the object of proposing an improved cooling for the movable surface.

[0012] This object is achieved by a device for producing metal strips and / or metal fibers according to claim 1. Advantageous embodiments of the device according to the invention can be found in claims 2 to 5, 7, 8, 10 and 12. Alternative embodiments of the device according to the invention can be found in claims 6, 9 and 11. The object according to the invention is further achieved by a method for producing metal strips and / or metal fibers according to claim 13. An advantageous embodiment of the method according to the invention can be found in claim 14. The wording of all claims is hereby explicitly incorporated into the description by reference.

[0013] The device according to the invention for producing metal strips and / or metal fibers comprises, as known per se, at least one production chamber, preferably a vacuum chamber, at least one storage container for the metal to be processed, at least one nozzle, at least one movable, preferably rotatable surface, and at least one collecting device. At least the nozzle and the movable surface are arranged in the production chamber. The nozzle is designed to eject the molten metal from the storage container by means of the nozzle and to deposit it onto a surface of the movable surface. The movable surface is designed to entrain and cool the molten metal in a plane of the surface of the movable surface, so that solidified metal strips and / or metal fibers are formed from the molten metal.

[0014] The movable surface is designed to detach the solidified metal strips and / or metal fibers from the surface by moving the movable surface. The movable surface has a cooling device. The at least one collecting device is designed to collect the solidified metal strips and / or metal fibers.

[0015] It is essential that at least one passive cooling structure with an enlarged surface is arranged on a side of the movable surface facing away from the surface of the movable surface.

[0016] The increased surface area of ​​the passive cooling structure dissipates heat from the moving surface, thus cooling the surface of the moving surface that the molten metal hits.

[0017] The object of the invention is further achieved by a method according to claim 13. The method according to the invention for producing metal strips and / or metal fibers is carried out, as is known per se, by means of a device with at least one storage container for the metal to be processed, at least one nozzle, at least one movable surface and at least one collecting device, wherein the method comprises the following method steps:

[0018] A depositing molten metal from the reservoir onto a surface of the movable surface by means of the nozzle;

[0019] B Carrying the molten metal along a surface of the movable surface so that metal bands and / or metal fibers are formed from the molten metal; C Cooling the metal bands and / or metal fibers;

[0020] D Collecting the metal strips and / or metal fibers using the collecting device.

[0021] It is essential that the surface of the movable surface is cooled passively.

[0022] This offers the advantage that complex sealing devices for water cooling are no longer necessary and less space is required, as water no longer needs to be channeled beneath the surface of the movable surface. The axis of the rotating surface can therefore be made significantly thinner, allowing seals to be smaller and simpler, thus extending service life. Furthermore, friction losses are reduced and the design is simplified. In particular, despite a reduction in the diameter of the axis, space is created in the axis of the rotating surface, which can be used for other functions, as no cooling fluid needs to be channeled.

[0023] In a preferred embodiment of the invention, the passive cooling structure is designed as a lamellar structure, preferably as nested cylindrical surfaces, to increase the surface area. It is also within the scope of the invention for the lamellar structure to be formed with sections of cylindrical surfaces. Particularly preferably, the lamellar structure is formed with circular cylindrical surfaces or sections. Preferably, several passive cooling structures are provided. A lamellar structure allows a significant increase in surface area to be achieved simply and in a space-saving manner.

[0024] Preferably, the surface will be provided with a highly emissive coating (e.g. soot) in order to better dissipate the heat that is transported purely by thermal radiation.

[0025] In a preferred embodiment of the invention, a second stationary cooling structure, preferably an active cooling structure, is arranged in cooperation with the passive cooling structure to increase the surface area. The passive cooling structure, for increasing the surface area of ​​the underside of the rotatable surface, rotates during operation and is therefore also referred to below as a rotating cooling structure. The second cooling structure is stationary.

[0026] Preferably, the rotating and stationary cooling structures are arranged offset from one another, most preferably in the form of lamella structures. The rotating and stationary parts of the cooling structure are thus arranged opposite each other, so that the stationary part absorbs the heat released by the rotating part. This results in the advantage of being able to achieve higher cooling performance.

[0027] The finned structure of the passive cooling system allows for a significant increase in surface area in a simple and space-saving manner, creating large interaction surfaces through which heat can be dissipated. This results in the advantage of higher cooling performance.

[0028] Preferably, the stationary cooling structure is connected to an active cooling device, so that the fin structure of the stationary cooling structure is actively cooled. It is particularly advantageous to provide an active cooler for the stationary cooling structure outside the vacuum chamber. The vacuum chamber wall is used as a cooling surface, e.g., made of aluminum or copper. This offers the advantage of allowing higher cooling performance.

[0029] In an alternative embodiment, particularly according to the preamble of claim 1, the movable surface is designed as a rotatable surface, wherein the drive for the rotatable surface is designed as a rotor of an electric motor and / or as a tool spindle. Preferably, the rotatable surface is designed in the form of a plate on a rotatable axis.

[0030] A drive is required to move the movable surface. The drive must be extremely smooth, offer sufficient torque, and precisely controllable speeds. State-of-the-art technology in melt-spinning systems typically uses synchronous or asynchronous motors coupled to the shaft of the movable surface via a belt drive, chain, or gear. The disadvantage of these drive systems is that a radial force is constantly acting on the shaft, resulting in vibrations and increased bearing wear.

[0031] The inventive design of the drive for the rotating surface as a tool spindle allows for an alternative drive to be realized cost-effectively and with a few readily available components. The coaxial drive means that the shaft of the rotating surface is not subjected to radial loads as is the case with the belt drives described above and known from the prior art. Instead, the shaft of the rotating surface experiences pure torque. This improves bearing wear and smooth running.

[0032] In a preferred embodiment of the invention, the drive is designed such that an axis of the rotatable surface runs coaxially with the tool spindle, or such that the axis of the rotatable surface is designed as a tool spindle, preferably as the rotor of an electric motor. This results in both assembly advantages and cost savings.

[0033] The above-described embodiments with a tool spindle as the drive can also be advantageously combined with a device for producing metal strips and / or metal fibers according to claim 1 or a preferred embodiment. This results in the advantage that the rotating surface can be mounted directly on the shaft of the tool spindle, since there is no liquid cooling along the rotation axis. The drive and cooling of the rotating surface can thus be combined in a simple and cost-effective manner.

[0034] In a preferred embodiment of the invention, the device is designed with a closed cooling circuit, preferably with water-air cooling. Due to the aforementioned disadvantages, known melt-spinning devices require an external cooling water unit, as large amounts of heat are generated that cannot be dissipated directly at the device by water-air cooling. This results in significant disadvantages, such as the corresponding building equipment and dimensioning when installing a large number of melt-spinning devices in a production hall. Furthermore, air bubbles in the system of such external cooling water units are problematic.

[0035] Typically, these external cooling water units are designed as a shared cooling water circuit for multiple melt-spinning devices. In the event of contamination, this poses a significant risk because, for example, contaminants due to machine failures and operator errors are shared among all connected melt-spinning devices.

[0036] In a preferred embodiment of the invention, the production chamber and / or the storage container are designed to suit the process speed. In particular, the production chamber is preferably designed without dead space. Known melt-spinning devices are large, heavy, and cost-intensive both to manufacture and to operate. Evacuating the production chamber takes a very long time, and heating the crucible takes a long time, and with previously known melt-spinning devices, this is necessary during every interruption, particularly for filling with metal to be melted. The previous strategy for increasing production with previously known melt-spinning devices was to continually enlarge them. The present invention has shown that this strategy is not effective, since the bottleneck in production, the nozzle, cannot grow with the previously known design to increase production.This results in a reduction in downtime at best. The process itself remains exactly the same speed, regardless of the size of the system. Therefore, it is actually advantageous to miniaturize the components of the device as much as possible. Reducing the size of the production chamber and crucible is particularly beneficial, especially by generally eliminating dead space.

[0037] In a preferred embodiment of the invention, means are provided for filling the storage container for the metal to be processed during ongoing operation. Furthermore, means are provided for removing the solidified metal strips and / or metal fibers from the collecting device during ongoing operation.

[0038] This has the advantage that interruptions to the melt spinning process are eliminated by adding material during operation. The vacuum and / or the process conditions in the production chamber are maintained. The device does not cool down due to an interruption in the process and therefore does not need to be reheated for continued operation. This saves time and energy and increases the efficiency of the device, as times for cooling and heating the storage container and for creating and adjusting the process conditions in the production chamber are eliminated. Preferably, a pressure gradient is formed between the interior of the storage container and the interior of the production chamber at an opening in the nozzle, and a pressure lock is provided for filling the storage container, which keeps the pressure gradient essentially constant during the filling process.

[0039] Furthermore, the continuous addition of metal allows the dimensions of the storage container to be significantly reduced. This reduction in size not only reduces the material required to manufacture the storage container, but also significantly reduces energy loss, primarily due to heat radiation during operation of the device. In particular, the reduction in heat radiation has further positive effects. Namely, the heating system for heating the metal in the storage container needs to be significantly less powerful. The cooling system for cooling the movable surface also needs to be significantly smaller, since the temperature in the production chamber is lower due to the reduction in heat radiation. Furthermore, the production chamber can be significantly reduced in size, as the aforementioned components arranged in the production chamber are smaller.Accordingly, smaller pumps and components can be used to generate the atmosphere inside the production chamber. This significantly reduces the space required and both production and operating costs of the device.

[0040] By providing means for removing the solidified metal strips and / or metal fibers from the collecting device during ongoing operation, interruptions to operation for removing the metal strips and / or metal fibers are eliminated. As described above, this saves time and energy and increases the efficiency of the device, as the times for cooling and heating the device and for creating and adjusting the process conditions in the production chamber are eliminated. The collecting container can also be made smaller, which leads to material savings and further miniaturization of the connected components such as pumps and other parts. By providing means for filling and emptying both the storage container for the metal to be processed and the collecting device for the solidified metal strips and / or metal fibers during ongoing operation,The appropriate filling and removal during ongoing operation not only avoids interruptions in operation, but these measures also enable the overall device to be optimized with regard to size, component performance requirements, energy loss and heat radiation.

[0041] The measures described above significantly reduce the heat energy radiated from the storage container, crucible, and connected components. With a significantly reduced amount of heat, the use of the passive cooling device described above is particularly advantageous.

[0042] As described, the inventions lie in the field of melt spinning. All of the embodiments of the invention described above can be combined particularly advantageously in a device according to the application DE102024105394.1 of the applicant Sensific GmbH. This particularly applies to the advantageous embodiment according to claim 12, which is described in detail in the cited application. A further advantageous combination is the combination with the camera monitoring of the fill level of the molten metal and / or temperature of the molten metal and / or temperature distribution of the molten metal in the storage container and / or a distance measurement of the distance between the nozzle opening and the surface of the movable surface, as well as a corresponding control system, as described in the cited application.

[0043] Further preferred features and embodiments of the device according to the invention and the method according to the invention are explained below with reference to embodiments and the figures.

[0044] Figure 1 shows a first embodiment of a device according to the invention with a passive and an active cooling structure;

[0045] Figure 2 shows a further embodiment of a device according to the invention with a coaxial drive.

[0046] Figure 1 shows a schematic representation of a first embodiment of the device 1 according to the invention. The device 1 comprises a production chamber 1, a storage container 3 for the metal to be processed, with at least one nozzle 4, a movable, in this case rotatable surface 5 and a collecting device (not shown).

[0047] The storage container 3, in this case designed as a crucible, the nozzle 4, the rotatable surface 5, and the collecting device are at least partially arranged in the production chamber 2. The production chamber 2 is evacuated.

[0048] The rotatable surface 5 is designed as a rotatable plate and has a surface 5a. The diameter of the plate is 8 cm in this case. For example, the surface of the plate is made of copper when aluminum is being processed or of molybdenum when copper is being processed.

[0049] To melt the metal, a heating wire 9 is provided, located at the bottom of the crucible. The temperature of the molten metal, in this case copper, is approximately 1150°C.

[0050] On the underside 5b of the rotatable surface 5 is a passive cooling structure in the form of a lamellar structure 6, in this case in the form of interlocking cylindrical surfaces arranged concentrically. The lamellar structure significantly increases the surface area, allowing heat to be dissipated. This cools the plate 5, and in particular the surface 5a.

[0051] The nozzle 4 is arranged and designed to deposit molten metal from the storage container 3 onto the surface 5a of the plate 5. In this case, the width of an opening in the nozzle from which the molten material emerges is 100 pm. The plate rotates and is designed to entrain and cool the molten metal in a plane of the surface 5a. The rotational speed in this case is 150 Hz. The surface speed of the rotatable surface 5 at the outer edge is in the range between 10 and 100 m / s, in this case 30 m / s. Solidified metal bands and / or metal fibers form from the molten metal. The actual geometric design of the metal bands and / or metal fibers depends on the metal, the temperature and thus the viscosity of the melt, the speed of the surface 5a, and the temperature of the surface 5a.

[0052] In the present case, the plate 5 and in particular the surface 5a is cooled by means of the passive cooling structure 6 on the underside 5b.

[0053] In this case, the passive cooling structure 6 is designed as a lamellar structure in the form of nested cylindrical surfaces, exemplified by 6a, 6b, to increase the surface area. The cylindrical surfaces 6a, 6b extend downward from the underside 5b and are arranged concentrically.

[0054] The passive cooling structure for increasing the surface area of ​​the underside of the rotating surface rotates during operation and is therefore also referred to as the rotating cooling structure.

[0055] A second stationary cooling structure 7, which is also designed in the form of a lamella structure, is arranged offset in an interlocking manner within the lamella structure 6 of the passive cooling structure. The stationary cooling structure is designed in the form of nested cylindrical surfaces, exemplified by 7a, 7b. The cylindrical surfaces 7a, 7b extend upward from a cooling surface 8 and are arranged concentrically. The mounting plate 8, with the surface 8a with the lamellae, is equipped on the underside 8b with a downstream (active) cooling system 11 (in this case, a water cooling system).

[0056] The stationary and rotating cooling structures are arranged opposite each other so that the stationary cooling structure absorbs the heat released by the rotating cooling structure.

[0057] With the described combination of stationary and rotating cooling structure, the rotating plate is cooled to approximately 200° Celsius. At least one collecting device (not shown) is designed to collect the solidified metal strips and / or metal fibers. Due to the speed of over 100 km / h, the metal fibers automatically fly toward a baffle plate 6d of the collecting device. An angle can be adjusted using the movable storage container.

[0058] The collection device is designed as a two-chamber device with a collection chamber and a removal chamber. The metal strips and / or metal fibers fall into a first collection chamber of the collection device. This first collection chamber is open to the production chamber 2 and thus has the same process conditions. To remove the metal strips and / or metal fibers, the removal chamber is closed off from the environment and brought to the same process conditions as the collection chamber. In this case, this concerns the gas composition inside the chamber and the prevailing pressure. In this case, the pressure in the production chamber is < 1 mbar, preferably < 0.1 mbar. The production chamber is filled with argon.

[0059] Figure 2 shows a schematic representation of a first embodiment of the device 1 according to the invention with a coaxial drive.

[0060] In the following, only the differences to Figure 1 will be discussed. The same reference numerals denote identical or equivalent elements.

[0061] The drive for the rotating surface, in this case in the form of a plate 5, is designed as a tool spindle 9. The plate 5 is mounted on the tool spindle as a rotation axis 10.

[0062] In the present case, the axis 10 of the rotatable surface is designed as a rotor of an electric motor 9.

[0063] Since the device 1 is designed with a cooling system, as described in Figure 1, no cooling water needs to be pumped through the axis 10 into the plate 5, so that the axis can be used as part of the drive.

[0064] device

[0065] Production chamber

[0066] storage container

[0067] nozzle

[0068] Plate, movable surface a Surface b Bottom Rotating cooling structure Stationary cooling structure

[0069] Mounting plate for stationary cooling structure

[0070] Tool spindle 0 Rotary axis 1 Further cooling

Claims

Claims 1. A device (1) for producing metal strips and / or metal fibers, comprising at least one production chamber (2), at least one storage container (3) for the metal to be processed, at least one nozzle (4), and at least one movable, preferably rotatable, surface (5), wherein at least the nozzle (4) and the movable surface (5) are arranged in the production chamber (2), and the nozzle (4) is configured to deposit molten metal from the storage container (3) onto a surface (5a) of the movable surface (5), and the movable surface (5) is configured to entrain and cool the molten metal in a plane of the surface, so that solidified metal strips and / or metal fibers are formed from the molten metal, and the movable surface (5) is configured to detach the solidified metal strips and / or metal fibers from the surface by moving the movable surface (5), and the at least one collecting device (6) is configured,to collect the solidified metal strips and / or metal fibers, characterized in that at least one passive cooling structure (15) with an enlarged surface is provided on an underside (5b) of the movable surface (5) facing away from the surface (5a) of the movable surface (5).

2. Device (1) for producing metal strips and / or metal fibers according to Claim 1, characterized in that the passive cooling structure (15), preferably a plurality of passive cooling structures (15), are designed as a lamellar structure, preferably as nested cylinder shells, to enlarge the surface of the underside (5b).

3. Device (1) for producing metal strips and / or metal fibers according to one of the preceding claims, characterized in that that a second cooling structure, preferably a stationary cooling structure, most preferably an actively cooled stationary cooling structure, is arranged in cooperation with the passive cooling structure (15) to enlarge the surface of the underside (5b).

4. Device (1) for producing metal strips and / or metal fibers according to one of the preceding claims, characterized in that the passive cooling structure (15) is designed as a lamellar structure, preferably as nested cylinder jackets, to enlarge the surface on the side (5b), and a second stationary cooling structure in the form of a lamellar structure, preferably an actively cooled cooling structure, in particular actively cooled nested cylinder jackets, is arranged offset and interlocking with the passive cooling structure.

5. Device (1) for producing metal strips and / or metal fibers according to one of the preceding claims, characterized in that the movable surface (5) is designed as a rotatable surface, preferably in the form of a plate, and the drive for the rotatable surface is designed as a tool spindle.

6. Device (1) for producing metal strips and / or metal fibers according to the preamble of claim 1, characterized in that the movable surface (5) is designed as a rotatable surface, preferably in the form of a plate, and the drive for the rotatable surface is designed as a rotor of an electric motor and / or as a tool spindle.

7. Device (1) for producing metal strips and / or metal fibers according to one of the preceding claims, characterized in that the drive is designed such that an axis of the rotatable surface runs coaxially with the tool spindle or that the axis of the rotatable surface is designed as a tool spindle, preferably as a rotor of an electric motor.

8. Device (1) for producing metal strips and / or metal fibers according to one of the preceding claims, characterized in that the device has a closed cooling circuit, preferably a water-air cooling system.

9. Device (1) for producing metal strips and / or metal fibers according to the preamble of claim 1, characterized in that the device has a closed cooling circuit, preferably a water-air cooling system.

10. Device (1) for producing metal strips and / or metal fibers according to one of the preceding claims, characterized in that the production chamber (2) and / or the storage container (3) is designed to be adapted to the process speed, preferably without dead space.

11. Device (1) for producing metal strips and / or metal fibers according to the Preamble of claim 1, characterized in that the production chamber (2) and / or the storage container (3) is designed to be adapted to the process speed, preferably without dead space.

12. Device (1) for producing metal strips and / or metal fibers according to one of the preceding claims, characterized in that at least one collecting device (6) is provided, preferably that means are provided to fill the storage container for the metal to be processed during operation and that means are provided to remove the solidified metal strips and / or metal fibers from the collecting device during operation, preferably that a pressure gradient prevails between the interior of the storage container (3) and the interior of the production chamber (2) at an opening of the nozzle (4), and that a pressure lock (6c) is provided for filling the storage container (3), which keeps the pressure gradient substantially constant during the filling process, particularly preferably that the storage container (3) is designed as a two-chamber device, wherein a first melting chamber (3b) with a tempering device for melting the newly filled material and a second nozzle chamber (3a) in operative connection with the nozzle are provided.

13. A method for producing metal strips and / or metal fibers by means of a device (1) with at least one storage container (3) for the metal to be processed, at least one nozzle (4), at least one movable surface (5) and at least one collecting device (6), the method comprising the following method steps: A depositing molten metal from the storage container (3) onto a surface (5a) of the movable surface (5) by means of the nozzle (4); B entraining the molten metal through a surface (5a) of the movable surface (5) so that metal bands and / or metal fibers are formed from the molten metal; C Cooling of the metal strips and / or metal fibers; D Collecting the metal strips and / or metal fibers by means of the collecting device (6), characterized in that the surface (5a) of the movable surface (5) is passively cooled.

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