A coil arrangement for heating an atomization platform for ultrasonic atomization of metals, in a metal powder making device, a two-coil arrangement and a working assembly for such a device, and an ultrasonic method of atomizing metals

Abstract

The invention relates to a coil arrangement for heating an atomization platform for ultrasonic atomization of metals, in a metal powder making device, characterized in that it comprises a U-coil (1) in the shape of an incomplete circle, made of tubing; tubes (2) supplying the cooling medium to the U-coil (1); and guide tubes (3); wherein the tubes (2) are inserted into the guide tubes (3) so that they run along their entire length and fit tightly therein, and their ends protruding from the guide tubes (3) are fixed to the ends of the U-coil (1) and in fluid connection therewith, and in side view the coil arrangement is bent downwards so that the U- coil (1) is angled downwards with respect to the guide tubes (3). The invention relates to a two-coil arrangement for a metal powder making device comprising a spiral coil (4) for melting the feedstock and a coil arrangement according to the invention. The invention relates to a working assembly for a metal powder making device comprising an arrangement of two coils and an atomisation platform (7), and to an ultrasonic method for atomising metals.

Description

[0001] A coil arrangement for heating an atomization platform for ultrasonic atomization of metals, in a metal powder making device, a two-coil arrangement and a working assembly for such a device, and an ultrasonic method of atomizing metals

[0002] The subject of the invention is a coil arrangement for heating an atomisation platform for ultrasonic atomisation of metals, in a metal powder making devices, a two-coil arrangement, and a working assembly for such a device, and an ultrasonic method for atomising metals.

[0003] From the state of the art, various metal atomisation methods and devices are known for the production of metal powders, including gas atomisation and water atomisation methods and devices. These solutions are based on the use of a liquid metal source and an atomisation medium fed through a nozzle at high pressure. An alternative method for producing powders is ultrasonic atomisation, where the liquid metal is atomised by ultrasonic vibration and no gas flow is required. The emission velocity of liquid metal droplets, in the case of the ultrasonic atomisation process, is many times lower than in the methods using water and gas atomisation, which translates into smaller required working chamber dimensions and higher energetic efficiency. This type of solution is known for example from DE1558356, where liquid metal is poured onto a sonotrode and solidifies in a working chamber; DE3032785, where material in the form of a wire or rod is vibrated and then melted using an electron source or plasma arc; PL423410, where material is melted directly on the surface of a cooled sonotrode and material is fed from an independent feeder.

[0004] The process of producing powders by ultrasonic atomisation, for example, proceeds in such a way that the liquid metal is fed onto a vibrating atomisation platform; the platform material should be at a temperature at which the liquid metal does not turn into a solid state, and should not react with the metal. The liquid metal forms a thin layer on the platform. When a certain value of the platform's vibration amplitude is exceeded, an unstable capillary wave is created, causing droplets of liquid metal to break off, which then solidify as fine lumps, i.e. powder.

[0005] In ultrasonic atomisation, the the length of the atomisation platform heated to operating temperature (where atomisation occurs) is dependent on the resonant frequency of the vibrating system, the platform material and the operating temperature. It will vary for different resonance frequencies of the vibrating system, depending on the platform material and operating temperature. Heating the platform surface increases the surface energy of the surface layer, which consequently increases the adhesion of the liquid metal to the platform surface. Heat transfer from the molten metal to the platform causes the liquid metal or metal alloy to cool down and transition to the solid state. This makes it impossible to achieve atomisation. The reason for this is the effect of changing the geometry of the atomisation platform by the build-up of a layer of material to be atomised, which leads to untuning of the oscillating system, cessation of resonance and, consequently, deactivation of the resonant system. Heating the metal atomisation platform also increases its size. Thus, the geometrical dimensions of the atomisation platform are chosen so that the resonant frequency of the oscillating system (ultrasonic system - mechanical part - converter, waveguide booster, atomisation platform) is reached at the operating temperature - the temperature at which atomisation is effective.

[0006] The purpose of the present invention is to solve the problems known from the state of the art by means of induction heating of the platform, which is realised by means of the coil arrangement according to the invention. The function of the coil arrangement is furthermore to maintain the temperature of the molten metal at the interface with the atomisation platform, thus nullifying the effect of cooling the liquid metal on the atomisation platform and shutting down the resonant system. In addition, induction heating allows for 'local' - limited in range, heating of the atomisation platform. Only its upper part is heated to the level necessary for effective atomisation. The top section is structurally limited by an area of physical undercut made in the atomisation platform.

[0007] The advantages of the invention in relation to the state of the art are:

[0008] Tuning of the platform to the operating point - alignment with the resonant system and directly with the oscillating system due to heating.

[0009] Maintaining the operating temperature of the atomisation platform - effective ultrasonic atomisation.

[0010] Limiting the intense heating of the atomisation platform to a structurally separate area of it.

[0011] Maintaining reproducible process conditions for ultrasonic atomisation of metals and their alloys with respect to scalable process conditions.

[0012] The invention relates to a coil arrangement for heating an atomisation platform for the ultrasonic atomisation of metals, in a metal powder manufacturing device, comprising: an incomplete circle-shaped U-coil made of tubing; tubing supplying the coolant to the U-coil; and guide tubes; wherein the tubes are inserted into the guide tubes so that they run along their entire length and fit tightly into them, and their ends protruding from the guide tubes are fixed to the ends of the U-coil and in fluid connection therewith, and in the side view, the coil arrangement is bent downwards so that U-coil is angled downwards in relation to the guide tubes.

[0013] Preferably, the U-coil has a substantially square or concentric cross-section.

[0014] Preferably, the cross-section of the tube forming the U-coil is between 4 and 16 mm, the wall thickness of this tube is between 0,2 and 3 mm and the outer diameter of the U-coil is between 15 and 160 mm.

[0015] Preferably, the coil arrangement is made of copper.

[0016] Preferably, the ends of the U-coil and the ends of the tubes to which the U-coil is attached are directed in opposite directions so that the closed side of the U-coil faces away from the guide tubes.

[0017] Preferably, the ends of the tubes to which the U-coil is attached are bent downwards, and the U-coil is attached to them at an angle so that the closed side of the U-coil faces towards the guide tubes.

[0018] Preferably, there is only one tube, which constitutes the U-coil, wherein both ends of the tube are inserted into the guide tubes.

[0019] More preferably, the U-coil is formed from a tube by bending it into the shape of a two- or multi-level incomplete circle.

[0020] The invention also relates to a two-coil arrangement for a metal powder making device, comprising a spiral coil for melting the feedstock and a coil arrangement for heating the atomisation platform in one of the variants described above, the spiral coil being positioned above the U-coil and, in side view, closer to the guide tubes than the U-coil. Preferably, one of the tubes connected to the U-coil is bent and spirally wrapped so that it constitutes a spiral coil positioned above the U-coil and, when viewed from the side, closer to the guide tubes than the U-coil.

[0021] Preferably, the spiral coil is part of a spiral coil arrangement comprising second tubes, second guide tubes and a spiral coil, the spiral coil arrangement being arranged so that the spiral coil is above the U-coil and, when viewed from the side, closer to the guide tubes than the U-coil. More preferably, the spiral coil arrangement is made of copper.

[0022] Also preferably, the spiral coil has 2-12 turns and a height in the range of 5-75 mm and an internal diameter in the range of 5-50 mm.

[0023] More preferably, the spiral coil has four coils with an internal diameter of 35 mm and a height of 30 mm.

[0024] It is also preferred if the spiral coil is made of a tube with a circular cross-section and an external diameter of 4 to 16 mm and a wall thickness of 0,2 to 3 mm.

[0025] The invention also relates to a working assembly for a metal powder making device, comprising an arrangement of two coils in one of the variants described above, and an atomisation platform, the atomisation platform being made of metal or metal alloys and having the shape of a cylinder of diameter D and height L, with an undercut 8 at the top at a level of about3 / s to Uo of the height L, with the U-coil located adjacent the upper surface of the atomisation platform.

[0026] Preferably, the U-coil is situated above the top surface of the atomisation platform at a distance having 1-20% of the height L and at about the full circumference to the4 / s of the circumference of the upper surface of the atomisation platform 7, while maintaining an angle of inclination of the U-coil 1 to the upper surface of the atomisation platform 7 in the range of -30° to 45°.

[0027] Preferably, the U-coil surrounds the upper part, above the undercut, of the atomisation platform.

[0028] Preferably, the atomisation platform 7 has a diameter D between 15-90 mm and a height L between 25-130 mm.

[0029] The invention also relates to an ultrasonic method for atomising metals in a device for producing metal powders, wherein the feedstock material introduced into the device is melted and the melted material is ultrasonically atomised on the atomisation platform 7, the upper part of the atomisation platform 7 being heated by means of a coil arrangement in one of the variants described above to reach the atomisation temperature.

[0030] Preferably, the feedstock is melted using a spiral coil.

[0031] Preferably, the method is carried out using a work unit in one of the variants described above.

[0032] The subject of the invention is explained in the embodiments in the drawings, in which figs. 1-3 show in perspective view of the coil arrangement according to the invention in various embodiments, figs. 4-7 show a two-coil arrangement according to the invention in various embodiments, figs. 8-10 show schematically possible positioning of the coil arrangement according to the invention in relation to the atomisation platform in a metal powder making device, figs. 11-12 show schematically the working assembly according to the invention, in various embodiments, fig. 13 shows a cross-sectional view of a part of a metal powder making device.

[0033] In figs. 1-3 it can be seen that the coil arrangement according to the invention comprises a U-coil 1 in the shape of an incomplete circle, tubes 2 supplying the cooling medium to the U-coil 1 and guide tubes 3. The tubes 2 are inserted into the guide tubes 3 so that they run along their entire length and fit tightly into them, while their ends protruding from the guide tubes 3 are firmly attached to the ends of the U-coil 1 and are in fluid connection therewith. In the side view, the coil arrangement is bent downwards so that the U- coil 1 is angled downwards in relation to the guide tubes 3. In the embodiments shown in fig. 1 and fig. 2 the U-coil 1 has a substantially square cross-section, preferably the cross-section of the tube forming the U-coil 1 is between 4 and 16 mm, the wall thickness of this tube is between 0,2 and 3 mm, the outer diameter of the U-coil 1 is between 15 and 160 mm, and the entire assembly is made of copper. It will be obvious that other conductive material can also be used to make the coil, which will meet the requirements necessary for the device to function properly. The coil arrangement is placed near the top of the atomisation platform in order to heat it by induction.

[0034] In the embodiment shown in fig. 1, the ends of the U-coil 1 and the ends of the tubes 2 to which the U-coil 1 is attached are directed in opposite directions so that the closed side of the U-coil 1 faces away from the guide tubes 3.

[0035] In another embodiment (fig. 2) the ends of the tubes 2 to which the U-coil 1 is attached are bent downwards, and the U-coil 1 is attached to them at an angle so that the closed side of the U-coil 1 faces towards the guide tubes 3.

[0036] Fig. 3 shows an embodiment where there is only one tube 2, which constitutes the U- coil 1, while both ends of tube 2 are inserted into guide tubes 3. The U-coil 1 in this embodiment is formed from the tube 2 by by bending it into the shape of a two-level incomplete circle, but it will be obvious that the coil so made can have only one level of incomplete circle, and then the coil arrangement resembles that of fig. 1, or more than two levels (not shown).

[0037] The coil arrangement can be used on its own in a metal powder making device, with appropriate positioning in relation to the atomisation platform 7. The possible positioning of the coil arrangement in different embodiments in the device is shown in figs. 8-10 - the U-coil can be placed above the top surface of the atomisation platform or surround the top of the platform.

[0038] Figs. 4-7 show a two-coil arrangement according to the invention, which comprises a spiral coil 4 for melting the feedstock and a coil arrangement for heating the atomisation platform. The spiral coil 4 is positioned above the U-coil 1 and, in side view, closer to the guide tubes 3 than the U-coil 1.

[0039] Fig. 4 and 5 show embodiments of a two-coil arrangement in which one of the tubes 2 connected to the U-coil 1 is bent and spirally wrapped so that it forms a spiral coil 4. As can be seen in these two figures, the U-coil 1 in this arrangement can be in different configurations - normal (as in fig. 1) or inverted (as in fig. 2). It can also be configured similarly as in fig. 3 (an arrangement with this configuration I snot shown in the figures).

[0040] In certain embodiments, the spiral coil 4 may be part of a separate spiral coil arrangement comprising the second tubes 5, the second guide tubes 6 and the spiral coil 4, wherein, as in the above-described examples, the spiral coil arrangement is positioned such that the spiral coil 4 is above the U-coil 1 and, when viewed from the side, closer to the guide tubes 3 than the U-coil 1. Such examples are shown in fig. 6-7, of course here also the U-coil can be configured similarly as in fig. 3 (not shown). The spiral coil arrangement, like the U- coil arrangement, can be made of copper or other suitable material.

[0041] In a preferred embodiment, the spiral coil 4 has 2-12 turns and a height in the range of 5-75 mm and an internal diameter in the range of 5-50 mm, and preferably has four turns with an internal diameter of 35 mm and a height of 30 mm.

[0042] A spiral coil 4 in a two-coil arrangement can be made, for example, from a circular tube with an outer diameter of 4 to 16 mm and a wall thickness of 0,2 to 3 mm.

[0043] The coils in all embodiments can be made from a single, continuous section of tubing or from modules that are joined together in a way that ensures the tightness and continuity of the electrical circuit.

[0044] Fig. 11 and 12 show the working assembly for a metal powder making device. The assembly comprises an arrangement of two coils, in possible variants according to the invention, and an atomisation platform 7. Atomization platform 7 is made of metal or metal alloys and is cylindrical in shape, with a diameter D and a height L. Platform 7 has an undercut 8 at the top, at a level of approximately3 / s to Uo of the height L. The U-coil 1 is situated at the upper surface of the atomisation platform 7. In this example, U-coil 1 is located above the top surface of atomization platform 7, at a distance having 1-20% of the height L and at approximately from the full circumference to the4 / s the circumference of the top surface of atomisation platform 7. The angle of inclination of the U-coil 1 to the top surface of the atomisation platform 7 is between -30° and 45°. Platform 7 is provided with suitable means of fastening it to the device, such as a threaded connection at the bottom, or is an integral part of the vibration system. The height L of platform 7 is determined by the acoustic properties of the material when operating at elevated temperatures with the appropriate vibration frequency of the resonant system. When the upper part of platform 7 (above undercut 8) is heated by U-coil 1, to a temperature at which atomisation of the molten material takes place, the platform acquires sufficient characteristics to operate at the resonant frequency of the entire vibrating system.

[0045] Guide tubes 3 common to both coil arrangements or separate tubes 3, 6 (not shown) for each coil arrangement are fixed in the sealed holes of the Teflon passage 9, which is fixed to the process chamber of the device, as shown in fig. 13.

[0046] As in the situation where the U-coil arrangement is used alone, in the working assembly the U-coil 1 may surround the upper part, above the undercut 8, of the atomisation platform 7, as in fig. 3 (assembly in this configuration not shown).

[0047] In a preferred embodiment, atomisation platform 7 has a diameter D between 15-90 mm and a height L between 25-130 mm.

[0048] In the embodiment, the method of atomising metals in a metal powder making device is that the feedstock material introduced into the device is melted and the melted material is atomised ultrasonically on the atomisation platform 7, the upper part of the atomisation platform 7 being heated by means of a coil arrangement according to the invention until the atomisation temperature is reached. In the preferred embodiment, the feedstock is melted using spiral coil 4, but it will be obvious to the person skilled in the art that this can also be done by other, known methods. The feedstock - metal or metal alloy - can be introduced into the device in the form of a rod, wire, fibre, concentric casting, and fed onto the atomisation platform, either directly from a melting source, e.g. an induction-heated crucible, or by melting in the area above the surface of the atomisation platform 7. If a spiral coil 4 is used for melting, the material is fed concentrically with respect to its axis of symmetry. The molten material moving through the spiral coil 4 is additionally heated. The operating temperature depends on the metal or metal alloy being atomised. The operating temperature of the heated atomisation platform 7 can be measured directly on the surface of platform 7 or elsewhere in the geometry of platform 7. In the second case, the measurement is a reference measurement.

[0049] In a preferred embodiment, the method is carried out by means of a working assembly according to the invention.

[0050] Of course, the invention is not limited to the implementation examples described above, and the features indicated in the claims can be combined in any combination appropriate to the particular application of the solution.

Claims

AMENDED CLAIMS received by the International Bureau on 17 December 2024 (17.12.2024)1. A working assembly for a metal powder making device, characterised in that it comprises a) a two-coil arrangement comprising o a spiral coil (4) for melting the feedstock and o the coil arrangement for heating the atomisation platform, the coil arrangement comprising:■ U-coil (1) in the shape of an incomplete circle, made of tubing;■ tubes (2) supplying the coolant to the U-coil (1); and■ guide tubes (3); wherein the tubes (2) are inserted into the guide tubes (3) so that they run along their entire length and fit tightly therein, and their ends protruding from the guide tubes (3) are fixed to the ends of the U-coil (1) and in fluid connection therewith, and in the side view, the coil arrangement is bent downwards so that the U-coil (1) is at a downward angle in relation to the guide tubes (3) wherein the spiral coil (4) is positioned above the U-coil (1) and, in a side view, closer to the guide tubes (3) than the U-coil (1) and b) an atomization platform (7), the atomization platform (7) being made of metal or metal alloys and having the shape of a cylinder of diameter (D) and height (L), with an undercut (8) in the upper part at a level of about3 / s to Uo of the height (L), wherein the U-coil (1) is located adjacent the top surface of the atomisation platform (7).

2. Working assembly according to claim 1, characterised in that the U-coil (1) has an essentially square or concentric cross-section, preferably wherein the cross-section of the tube forming the U-coil (1) is between 4 and 16 mm, the wall thickness of this tube is between 0,2 and 3 mm and the outer diameter of the U-coil (1) is between 15 and 160 mm.

3. Working assembly according to claim 1, characterised in that the coil arrangement is made of copper.12AMENDED SHEET (ARTICLE 19)4. Working assembly according to claim 1, characterised in that the ends of the U-coil(1) and the ends of the tubes (2) to which the U-coil (1) is attached are directed in opposite directions so that the closed side of the U-coil (1) faces away from the guide tubes (3).

5. Working assembly according to claim 1, characterised in that the ends of the tubes (2) to which the U-coil (1) is attached are bent downwards, and the U-coil (1) is attached to them at an angle so that the closed side of the U-coil (1) faces towards the guide tubes (3).

6. Working assembly according to claim 1, characterised in that there is only one tube(2), which constitutes the U-coil (1), while both ends of the tube (2) are inserted into the guide tubes (3), preferably wherein the U-coil (1) is formed from a tube (2) by bending it into the shape of a two- or multi-level incomplete circle.

7. Working assembly according to claim 1, characterised in that in the two-coil arrangement one of the tubes (2) connected to the U-coil (1) is bent and spirally wound so as to form the spiral coil (4) positioned above the U-coil (1) and, when viewed from the side, closer to the guide tubes (3) than the U-coil (1).

8. Working assembly according to claim 1, characterised in that in the two-coil arrangement the spiral coil (4) is part of a spiral coil arrangement comprising second tubes (5), second guide tubes (6) and the spiral coil (4), the spiral coil arrangement being arranged so that the spiral coil (4) is above the U-coil (1) and, when viewed from the side, closer to the guide tubes (3) than the U-coil (1).

9. Working assembly according to claim 8, characterised in that the spiral coil arrangement is made of copper.

10. Working assembly according to claim 1, characterised in that the spiral coil (4) has 2- 12 turns and a height in the range of 5-75 mm, and an internal diameter in the range of 5-50 mm, preferably wherein the spiral coil (4) has four turns with an internal diameter of 35 mm and a height of 30 mm.

11. Working assembly according to claim 1, characterised in that the spiral coil (4) is made of a tube having circular cross-section with an external diameter of 4 to 16 mm and a wall thickness of 0,2 to 3 mm.

12. Working assembly according to one of claims 1-11, characterised in that the U-coil (1) is situated above the upper surface of the atomisation platform (7) at a distance having 1-20% of the height (L) and approximately from the full circumference to the4 / s13AMENDED SHEET (ARTICLE 19)of the circumference of the upper surface of the atomisation platform (7), while maintaining the angle of inclination of the U-coil (1) to the upper surface of the atomisation platform (7) in the range of -30° to 45°.

13. Working assembly according to claim 1-11, characterised in that the U-coil (1) surrounds the upper part, above the undercut (8), of the atomisation platform (7).

14. Working assembly according to claim 1-11, characterised in that the atomisation platform (7) has a diameter (D) between 15-90 mm and a height (L) between 25-130 mm.

15. An ultrasonic method for atomising metals in a metal powder making device, characterised in that the feedstock introduced into the device is melted by means of the spiral coil (4) of the working assembly according to claims 1-14, and the melted material is atomised ultrasonically on an atomisation platform (7), the upper part of the atomisation platform (7) being heated by means of the coil arrangement of the working assembly according to claims 1-14, until atomisation temperature is reached.14AMENDED SHEET (ARTICLE 19)

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