Device for the separation and treatment of metallic particles

Abstract

Device for the separation and treatment of metallic particles which, in a generative powder-based manufacturing process, are formed from a powder bed with a deflectable energy beam and are fed to at least one filter element (2) with an extracted raw gas, wherein the metallic particles separated with the at least one filter element (2) are deposited on the bottom of a collecting container (6) arranged vertically below the at least one filter element (2), characterized in that a treatment chamber (8) is connected or can be connected there in the region of the bottom of the collecting container (6) and a gas-tight sealable first opening is formed at the bottom of the collecting container (6), through which metallic particles separated from the raw gas enter the treatment chamber (8) when a first closure element opens the first opening and the treatment chamber (8) is designed such thatthat the metallic particles reduce their chemical reactivity when the first opening is closed again at least to such an extent that no spontaneous oxidation reaction occurs when the treatment chamber (8) is opened and comes into contact with oxygen.

Description

[0001] The invention relates to a device for the separation and treatment of metallic particles which are formed in a powder bed in a generative powder-based manufacturing process using a deflectable energy beam, in particular a laser beam, and are fed to at least one filter element with an extracted raw gas, wherein the particles separated by the at least one filter element are deposited at the bottom of a collecting container arranged vertically below the at least one filter element.

[0002] In these powder-based manufacturing processes, particles are locally fused or sintered together using energy. This process creates very fine, very small particles from metal that has been temporarily transferred into the gas phase. These particles are conveyed to a separation device with the raw gas stream extracted from the component manufacturing device, separated from the raw gas using a filter element, and then stored in a container. Due in particular to their small particle size, the particles are highly chemically reactive, and spontaneous oxidation reactions occur upon contact with oxygen. To counteract this problem, the raw gas is extracted and the separated metallic particles are stored in an oxygen-free, inert atmosphere. Typically, the atmosphere is created using argon as a suitable noble gas, which is associated with correspondingly high costs.

[0003] However, since the temporarily stored and separated particles have to be removed from the separation device from time to time and contact with oxygen is unavoidable, the temporarily stored particles are covered with an inert substance and, if necessary, mixed so that the concentration of particles is reduced and the distances between particles are increased.

[0004] Nevertheless, disposal of metallic particles treated in this way is not possible without problems.

[0005] It is therefore an object of the invention to provide possibilities for a problem-free or safe disposal of fine metallic particles arising during separation in the generative powder-based production of components.

[0006] According to the invention, this object is achieved by a device having the features of claim 1. Advantageous embodiments and further developments of the invention can be realized with features specified in subordinate claims.

[0007] In the separation and treatment device according to the invention, metallic particles formed in a generative manufacturing process from a powder bed using a deflectable energy beam are fed to at least one filter element with an extracted raw gas. The metallic particles separated by the at least one filter element are deposited at the bottom of a collection container arranged vertically below the at least one filter element.

[0008] A treatment chamber is connected to the bottom of the collection container or can be connected there. A gas-tight, sealable first opening is formed at the bottom of the collection container, through which metallic particles separated from the raw gas enter the treatment chamber when a first closure element releases the first opening.

[0009] The treatment chamber is designed in such a way that the metallic particles reduce their chemical reactivity when the first opening is closed again, at least to such an extent that no spontaneous oxidation reaction occurs when the treatment chamber is opened and comes into contact with oxygen.

[0010] During the treatment of the metallic particles, the treatment chamber should be completely closed so that no substances can escape from the treatment chamber during the treatment and, for most suitable treatments, no substances can enter the treatment chamber, or at least not in an uncontrolled manner.

[0011] Advantageously, the treatment chamber can have a second opening that can be sealed gas-tight with a second closure element, through which the treated and rendered harmless metallic particles can then be removed from the treatment chamber. The first and second closure elements should be activated in such a way that at least one closure element seals the treatment chamber gas-tight at all times. The treatment chamber can thus function like a lock into which hazardous metallic particles enter. After the treatment chamber is closed, the respective treatment of the metallic particles is carried out. Following this successful completion, the second opening is opened and the treated particles are sent for disposal or further downstream processing.

[0012] This allows hazards to be avoided because the metallic particles deposited in the collection container can be kept in an inert atmosphere after separation, which can also be maintained upon entry through the first opening in the treatment chamber, since the treatment chamber should be connected to the collection container in a gas-tight manner and a gas-tight seal against the environment should also be maintained.

[0013] If a treatment chamber only has a first opening, it is advantageous to detachably attach the treatment chamber to the collection container. After the metallic particles have been successfully treated, the treatment chamber can be removed and emptied. The emptied treatment chamber can be reinserted. However, it is also possible to exchange treatment chambers.

[0014] Closure elements can be formed with at least one flap that can be rotated about an axis and has a suitable sealing element. They can be held in the closed position by a spring.

[0015] The metallic particles can fall from the collection container into the treatment chamber due to gravitational forces when the first opening is open. However, it is also possible to support this with at least one pressure surge, as is common when cleaning filter elements.

[0016] The treatment chamber may contain a spray device for spraying the metallic particles falling into the treatment chamber with a liquid, solution, emulsion, or suspension, and / or a bath of a liquid, solution, emulsion, or suspension. This seals the metallic particles at least on their surface, preventing direct contact of the metallic particles with oxygen.

[0017] With the appropriate selection of a liquid, solution, or emulsion, it can act as a binding agent. This can be advantageously utilized for pelletizing. For this purpose, a pelletizing device can be connected to the second opening of the treatment chamber. The treated metallic particles can also be fed from the treatment chamber to a pelletizing device.

[0018] The liquid can be, for example, paraffin, glycerin, or a solution, emulsion, or suspension containing paraffin or glycerin. Aqueous solutions or emulsions are preferred. An organic chemical compound contained therein can be used as a binding or pressing aid during pelleting.

[0019] However, the treatment in the treatment chamber can also be carried out in such a way that a laser beam for agglomerating, sintering and / or melting metallic particles is directed through a window into the treatment chamber onto the metallic particles arranged in the treatment chamber.

[0020] In a further alternative, a heating device, in particular an electrical resistance heater, with which agglomeration, sintering and / or melting of the metallic particles can be achieved, can be present in / on the treatment chamber.

[0021] It is also possible to connect a metered supply of oxygen or an oxygen-containing gas mixture to the treatment chamber, allowing a predefined oxygen content or oxygen concentration to be set in the treatment chamber, which exclusively results in oxide formation on the surfaces of the metallic particles contained in the treatment chamber. The supply should be arranged and designed so that the oxygen or gas mixture flows around the metallic particles. This can be done to the extent that the metallic particles are swirled in the supplied gas stream.

[0022] Since oxygen is consumed as a result of oxidation, continuous supply is preferable. For this purpose, at least one oxygen sensor can be installed in the treatment chamber to ensure controlled supply. Depending on the type of metallic particles to be separated, the oxygen content in the treatment chamber should be maintained during treatment at a level that allows only partial oxidation. This means that a maximum of an oxide layer should form on the particle surfaces, and the oxygen should be consumed during oxidation, preventing any further oxidation reactions. The type of particle is essentially determined by the particle material and particle size.

[0023] The treatment options for metallic particles mentioned and explained here can also be combined with each other, so that the treatment can be carried out using several methods simultaneously or sequentially one after the other.

[0024] The invention will be explained in more detail below using examples.

[0025] It shows: Fig. 1 shows in schematic form an example of a device according to the invention.

[0026] In Fig.Figure 1 shows an example of a device according to the invention. Two filter elements 2 are arranged side by side in a housing 1, which can be used simultaneously or sequentially for separating metallic particles. Vertically below the filter elements 2, which can be cleaned by pressure pulses, is a collecting container 6 into which metallic particles cleaned by the filter elements 2 can fall due to gravitational force.

[0027] The collection tank 6 also has an inlet 5 for raw gas containing metallic particles. A portion of the metallic particles contained in the raw gas also falls into the collection tank 6. Another portion of the metallic particles contained in the raw gas reaches the filter elements 2 via the suction effect of a compressor (not shown) connected to the housing 1 and is thus separated from the raw gas.

[0028] A powder bed 9 containing the separated metallic particles forms in the collection container 6. A treatment chamber 8 is arranged in the powder bed 9 and is provided with a first opening through which separated metallic particles from the powder bed 9 can enter the treatment chamber 8. A second opening is provided on the treatment chamber 8, from which treated, no longer or only slightly reactive products formed with or from the metallic particles in the treatment chamber 8 can be removed. These can be transported in a closed transport container 7 for further post-treatment or disposal.

[0029] The first and second openings are each provided with a fluid-tight closure element which, like the first and second openings not shown, can also be temporarily closed in a fluid-tight manner at least during the treatment.

[0030] Flow guide or throttle elements 3 and 10 are arranged above the collecting tank 6 and vertically below the filter elements 2. These elements allow influencing the flow of the raw gas stream directed to the filter elements 2. These can also be used temporarily for complete closure.

[0031] The housing 1 and the collecting container 6 are connected to each other in a fluid-tight manner via flanges 4.

[0032] The treatment chamber 8 can be designed for compaction, in particular pelletizing or briquetting. For this purpose, an extruder or a pressing device can be provided inside, for example, with which the metallic particles can be compressed, optionally with the addition of a suitable binding agent.

[0033] As well as in the collection container 6, an inert atmosphere should also be maintained in the treatment chamber 8.

Claims

[1] Device for the separation and treatment of metallic particles which, in a generative powder-based production process, are formed from a powder bed with a deflectable energy beam and are fed to at least one filter element (2) with an extracted raw gas, wherein the metallic particles separated with the at least one filter element (2) are deposited on the bottom of a collecting container (6) arranged vertically below the at least one filter element (2), characterized bythat in the region of the bottom of the collecting container (6) a treatment chamber (8) is connected or can be connected there and at the bottom of the collecting container (6) a gas-tight sealable first opening is formed through which metallic particles separated from the raw gas reach the treatment chamber (8) when a first closure element opens the first opening and the treatment chamber (8) is designed such that the metallic particles reduce their chemical reactivity when the first opening is closed again at least to such an extent that when the treatment chamber (8) is opened and comes into contact with oxygen no spontaneous oxidation reaction occurs. [2] Device according to claim 1, characterized by that a second opening which can be closed gas-tight with a second closure element is provided on the treatment chamber (8). [3] Device according to claim 1 or 2, characterized bythat in the treatment chamber (8) there is / are a spray device for spraying the metallic particles falling into the treatment chamber (8) with a liquid, solution, emulsion or suspension and / or a bath of a liquid, solution, emulsion or suspension. [4] Device according to claim 1 or 2, characterized by that the treatment chamber (8) has a window through which a laser beam for agglomerating, sintering and / or melting metallic particles is directed onto the metallic particles arranged in the treatment chamber. [5] Device according to claim 1 or 2, characterized by that in / on the treatment chamber (8) there is a heating device, in particular an electrical resistance heater, with which agglomeration, sintering and / or melting of the metallic particles can be achieved. [6] Device according to claim 1, 2 or 5, characterized bythat a metered supply for oxygen or an oxygen-containing gas mixture is connected to the treatment chamber (8), with which a predeterminable oxygen proportion or a predeterminable oxygen concentration in the treatment chamber (8) can be set, with which exclusively an oxide formation on the surfaces of the metallic particles contained in the treatment chamber (8) can be achieved. [7] Device according to one of the preceding claims, characterized by that the first and second closure elements can be activated in such a way that at least one closure element closes the treatment chamber (8) in a gas-tight manner at any time. [8] Device according to one of the preceding claims, characterized by that a pelletizing device is connected to the second opening of the treatment chamber (8) or that metallic particles can be fed to a pelletizing device from the second opening. [9] Device according to claim 3 or 8, characterized by that the liquid used is a solution, emulsion or suspension containing paraffin, glycerin or glycerin.

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