Particle Separation Apparatus for Additive Manufacturing or Additive Manufacturing Apparatus

Abstract

The present invention relates to a separation device and a selective additive manufacturing device for separating particles for additive manufacturing. The particles are contained in a gas stream. The separation device includes at least one dry gas stream separator, the dry gas stream separator including a separation turbine with a variable rotational speed. The dry gas stream separator selects particles contained in the gas stream according to a particle size determined by the rotational speed of the separation turbine. The separation device for separating particles also includes an extractor for extracting particles contained in the gas stream. The dry gas stream separator and the extractor are in fluid communication such that the gas stream exiting the dry gas stream separator circulates through the extractor, and the gas stream exiting the extractor circulates through the dry gas stream separator. The separation device for separating particles also includes a device for circulating the gas stream between the gas stream separator and the extractor.

Description

[Technical field]

[0001] The present invention relates to the general field of additive manufacturing, and more particularly to the field of manufacturing objects, for example metal objects. [Background technology]

[0002] Selective additive manufacturing creates three-dimensional objects by solidifying selected zones in successive layers of a powder material (e.g., metal or ceramic powder). The solidification zones correspond to successive cross sections of the three-dimensional object. Solidification is performed layer-by-layer by, for example, total or partial selective melting using an energy source.

[0003] Powders, for example metal powders, consist of an agglomeration of particles which need to be separated, particularly by size, to achieve optimal production. To effect this particle separation, it is known to use physical sieves with a certain mesh, typically 63 μm (230 US mesh). The physical sieves have the disadvantage that the size of the particles to be separated cannot be adjusted, and furthermore, there is a problem that the air permeability of the particles on the sieve is low. Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention therefore aims to remedy these drawbacks by proposing a particle separation device for additive manufacturing and additive manufacturing devices. [Means for solving the problem]

[0005] A general object of the present invention is to overcome the limitations of the prior art. In particular, for this purpose, the invention proposes a separation device for separating particles for additive manufacturing. The particles are comprised in a gas stream. The separation device comprises at least one dry gas stream separator, which comprises a separation turbine with a variable rotation speed. The dry gas stream separator selects the particles comprised in the gas stream according to a particle size determined by the rotation speed of the separation turbine. The separation device for separating particles also comprises an extraction device for extracting the particles comprised in the gas stream. The dry gas stream separator and the extraction device are in fluid communication such that the gas stream leaving the dry gas stream separator circulates through the extraction device and the gas stream leaving the extraction device circulates through the dry gas stream separator. The separation device for separating particles also comprises a device for circulating the gas stream between the gas stream separator and the extraction device.

[0006] The invention also proposes an assembly comprising a selective additive manufacturing device and a separation device, the selective additive manufacturing device comprising or connected to the separation device.

[0007] In one embodiment, the assembly further comprises a distribution system for distributing the powder material, the distribution system being configured to receive the particles coming from the separating device.

[0008] In one embodiment, the assembly further comprises a collector for collecting unused particles, the collector being connected to an inlet of a separator for separating the particles.

[0009] In one embodiment, the assembly further comprises a filtration device mounted between the collection device and the inlet of the separation device for separating particles.

[0010] In one embodiment, the filtration device comprises a protective sieve having a mesh size between 300 μm and 1500 μm. Further characteristics and advantages of the invention will become apparent from the following description, which is purely illustrative and non-limiting and which must be read in conjunction with the accompanying drawings, in which: [Brief description of the drawings]

[0011] [Figure 1] 1 shows a first embodiment of a separation device. [Figure 2a] A separation turbine is shown. [Figure 2b] 2 illustrates, in graphical form, the relationship between the rotational speed of a separation turbine and the diameter of particles separated by the turbine. [Diagram 3] 2 shows a second embodiment of a separation device. [Figure 4] 3 shows a third embodiment of a separation device. [Diagram 5] 4 shows a fourth embodiment of a separation device. [Figure 6] 5 shows a fifth embodiment of a separation device. [Figure 7a] 1 illustrates an embodiment of a selective additive manufacturing apparatus. [Figure 7b] 1 illustrates an embodiment of a selective additive manufacturing apparatus. [Figure 8] 1 illustrates an embodiment of a selective additive manufacturing apparatus. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] 1 shows a first embodiment of a separation device for separating particles, for example metal particles, contained in a gas stream and intended to be used in additive manufacturing. The device comprises at least one dry airflow separator 101, which comprises a separation turbine with variable rotation speed and which selects the particles contained in the gas stream according to their particle size, which is determined by the rotation speed of the separation turbine.

[0013] The separator also includes an extractor 102 for extracting particles contained in the gas stream. The dry air stream separator 101 and the extractor 102 are in fluid communication such that the gas stream exiting the dry air stream separator 101 circulates through the extractor 102 and such that the gas stream exiting the extractor 102 circulates through the dry air stream separator 101. The separation device also comprises a device 103 for circulating the gas stream between the gas stream separator 101 and the extraction device 102 .

[0014] In the separation device, the dry air stream separator 101 separates particles smaller than a first size Dc1 by removing particles larger than Dc1 from the gas stream introduced into the separator. The particles larger than Dc1 removed from the gas stream will be rejected by the dry air stream separator 101 through the outlet 104. Thus, at the outlet of the dry air separator 101, the gas stream will substantially only contain particles with a size smaller than Dc1. The extractor 102 can then extract particles from the gas stream. The particles extracted by the extractor 102 have a size smaller than Dc1. The particles rejected by the air stream separator 101 have a size larger than Dc1.

[0015] In this embodiment, the loading of particles, e.g. metal particles, into the separator can be accomplished in two different ways. Two solid arrows 105 and 106 indicate these two ways, 105 via the top of the airflow separator 101 and 106 via a chute 107 of the airflow separator 101. In this separator 101, the size of the particles separated, known as the "cut size", will be determined by the rotational speed of the separation turbine, which is variable by a control device.

[0016] Such a separation turbine is shown in Figure 2a, while Figure 2b shows the relationship between the rotational speed of the separation turbine and the diameter of the particles separated by the turbine. This device has the advantage of being able to dynamically select the size of the particles to be extracted, which also allows for better aeration, drying, and decohesion of the particles than is possible with prior art devices, particularly sieve-based devices. More specifically, dry airflow separators have the advantage of being able to vary the size of the separated particles, and do not clog like traditional sieves.

[0017] In one embodiment, the device 103 for circulating the gas flow is a fan. In one embodiment, the device 102 for extracting particles comprises a bag filter. For example, it is possible to use a bag filter with anti-clogging properties. Bag filters have the advantage that they work better than other types of filters for extracting particles from a gas stream.

[0018] 3, the apparatus 102 for extracting particles comprises a cyclone 301 and a bag filter 302. The cyclone 301 and the bag filter 302 are in fluid communication such that the gas stream exiting the cyclone 301 circulates through the bag filter 302. For example, a bag filter having an anti-clogging function can be used.

[0019] A cyclone is a device that imparts rapid rotation to a gas stream in order to separate solid particles entrained in the gas stream. Cyclones have the advantage of reducing the stress on the bag filter. In this embodiment, the loading of particles, e.g. metal particles, into the separator can be accomplished in two different ways. Two solid arrows 105 and 106 indicate these two ways, 105 via the top of the airflow separator 101 and 106 via a chute 107 of the airflow separator 101.

[0020] In one embodiment, shown in Figure 4, the separation device comprises a device 401 for purifying and / or dehumidifying and / or deoxidizing a gas stream. The device 401 for purification and / or dehumidifying and / or deoxidizing makes it possible to limit the consumption of inert gas. In this embodiment, the loading of particles, e.g. metal particles, into the separator can be accomplished in two different ways. Two solid arrows 105 and 106 indicate these two ways, 105 via the top of the airflow separator 101 and 106 via a chute 107 of the airflow separator 101.

[0021] In one embodiment shown in FIG. 5, the separation device comprises a device 501 for selectively connecting the outlet of the extractor 102 to an inlet 502 of the dry airflow separator 101 or to a device 503 for collecting the separated particles. This inlet 502 of the dry airflow separator 101, sometimes known as the airflow separator chute, allows for the introduction of particles that will mix with particles already present in the circulating gas stream and be processed by the dry airflow separator 101.

[0022] The presence of this device 501, which makes it possible to selectively connect the outlet of the extraction device 102 to the inlet 502 of the dry airflow separator 101, has the advantage of being able to ensure recirculation of the gas flow and therefore of ensuring good dispersion of the particles, including when wet. This device 501 making it possible to selectively connect the outlet of the extractor 102 to the inlet 502 of the dry air stream separator 101 can be, for example, a flap. In this embodiment, the loading of particles, e.g. metal particles, into the separator can be accomplished in two different ways. Two solid arrows 105 and 106 indicate these two ways, 105 via the top of the airflow separator 101 and 106 via a chute 107 of the airflow separator 101.

[0023] In one embodiment shown in FIG. 6, the separation apparatus comprises at least two dry airflow separators 101 and 601 . The two dry air stream separators 101 and 601 are in fluid communication with each other such that the gas flow exiting one dry air stream separator 101 circulates through the other dry air stream separator 601 . Each of the dry airflow separators 101 and 601 comprises a separation turbine, the rotational speed of which is independently variable.

[0024] Each of the two dry gas stream separators 101 and 601 selects particles contained in the gas stream according to their size, which is determined by the rotational speed of the separation turbine. In this embodiment, it is possible to optionally add a device 602 for selectively connecting the outlet of the downstream dry airflow separator 601 to the inlet of the upstream dry airflow separator 101, or a device 603 for collecting the separated particles. This embodiment makes it possible to select particles, for example metal particles, whose size lies within a range of values, which makes it possible to exclude particles having a diameter larger than a first predetermined diameter and particles having a diameter smaller than a second predetermined diameter.

[0025] In detail, the upstream dry airflow separator 101 selects particles smaller than a first size Dc1 by separating particles larger than Dc1. The downstream dry airflow separator 601 then adjusts the turbine speed to select particles smaller than a second size Dc2, selecting particles with a size smaller than Dc2. Thus, if the size Dc2 is smaller than the size Dc1, the particles rejected by the downstream dry airflow separator 601 will have a size between Dc2 and Dc1. Optionally, it is possible to recirculate these particles with a size between Dc2 and Dc1 through the inlet 502 of the dry airflow separator 101. This recirculation allows for improved drying. It is also possible to direct these particles with a size between Dc2 and Dc1 towards the collector 603 for use. The particles extracted by the extractor 102 will have a size smaller than Dc2. The metal particles rejected by the upstream dry airflow separator 101 will have a size larger than Dc1.

[0026] In application to metal additive manufacturing powders, this embodiment allows for the removal of metal particles that are too small (typically 3 microns 5 / 15) and therefore allows for less generation of fumes and suspended particles and for better focusing of the energy source during the subsequent use of these metal particles in an additive manufacturing device. In this embodiment, the loading of particles, e.g. metal particles, into the separator can be accomplished in two different ways. Two solid arrows 105 and 106 indicate these two ways, 105 via the top of the airflow separator 101 and 106 via a chute 107 of the airflow separator 101.

[0027] One embodiment of the invention relates to a selective additive manufacturing apparatus comprising or connected to an apparatus as described above for separating particles, for example metal particles. Thus, the selective additive manufacturing device and the device for separating particles form an assembly.

[0028] In one embodiment shown in Figures 7a and 7b, the selective additive manufacturing apparatus 701 further comprises a system 702 for dispensing a powder material comprising particles, e.g. metal particles, the dispensing system adapted to receive the particles from the separation apparatus. In one embodiment, the selective additive manufacturing apparatus 701 has an apparatus 703 for collecting unused particles, e.g. unused metal particles, which is connected to an inlet of a separation apparatus for separating the particles, e.g. metal particles. Preferably, the selected inlet is the top of one of the dry airflow separators.

[0029] In one embodiment, a filter 704 is installed between the collector 703 and the inlet of the separator 101. This filter is, for example, a protective sieve with a preferred mesh size of 500 μm. The presence of this filter has the advantage of trapping coarse dross that may damage the separator 101.

[0030] Figure 8 shows an example of such an additive manufacturing device, which comprises: A support such as a horizontal plate 801 on which various layers of additive manufacturing powder (metal powder, ceramic powder, etc.) can be successively deposited to produce a three-dimensional object (in the figure, an object 802 in the shape of a fir tree). A dispensing system 702 for dispensing powder material, designed to supply the production powder to a layer forming roller or spreader. The dispensing system 702 comprises a metering device 803, a slide 804 and a strip 805. - A device 806 for distributing a powder, for example a metal powder, on a plate. This device 806 comprises, for example, a spreader 807 and / or layering rollers for distributing various successive layers of the powder (moving along the double-headed arrow A). An assembly 808 with an energy source 809, for example a source emitting a laser beam and / or an electron beam, for fusing (fully or partially) the thinly dispersed layers. A control unit 810 which controls the various components of the device according to pre-stored information (memory M). A mechanism 811 for lowering the support of the plate 801 (movement along the double-headed arrow B) while the layer is being deposited.

[0031] The components of the apparatus are arranged in a sealed chamber 812 which can be connected to an inert gas circuit and / or at least one vacuum pump 813, for example if an electron beam is used. [Explanation of symbols]

[0032] 101 Dry air separator 102 Extraction device 103 Equipment 104 Exit 107 Shots

Claims

1. 1. A separation apparatus for separating particles for selective additive manufacturing, the particles being contained in a gas stream, the separation apparatus comprising: at least one dry air stream separator (101), comprising a separation turbine having a variable rotational speed, said dry air stream separator (101) selecting said particles contained in said gas stream according to a particle size determined by the rotational speed of said separation turbine; an extractor (102) for extracting the particles contained in the gas stream; Equipped with the dry gas stream separator (101) and the extractor (102) are in fluid communication such that a gas stream leaving the dry gas stream separator (101) circulates through the extractor (102) and such that the gas stream leaving the extractor (102) circulates through the dry gas stream separator (101); The separation apparatus for separating particles further comprises a device (103) for circulating the gas stream between the dry gas stream separator (101) and the extractor (102).

2. The separation apparatus of claim 1 , wherein the extractor (102) for extracting the particles comprises a bag filter.

3. 2. The separation apparatus of claim 1, wherein the extraction device (102) for extracting the particles comprises a cyclone (301) and a bag filter (302), the cyclone (301) and the bag filter (302) being in fluid communication such that a gas stream exiting the cyclone (301) circulates through the bag filter (302).

4. A separation apparatus according to any of the preceding claims, further comprising an apparatus (401) for purifying and / or dehumidifying and / or deoxidizing the gas stream.

5. 5. The apparatus of claim 1, further comprising a device (501) for selectively connecting an outlet of the extraction device (102) to an inlet (502) of the dry air separation unit (101) or to a device (503) for collecting separated particles.

6. At least two dry airflow separators (101, 601), The at least two dry air stream separators (101, 601) are in fluid communication with each other such that a gas flow from one of the dry air stream separators (101) located upstream circulates through the other dry air stream separator (601) located downstream; Each of the two dry airflow separators (101, 601) comprises a separation turbine whose rotational speed is independently variable; each of the two dry gas stream separators (101, 601) selects particles contained in the gas stream according to a particle size determined by the rotational speed of the separation turbine; A separation device according to any one of claims 1 to 4.

7. 7. The separation device according to claim 6, further comprising a device (602) for selectively connecting an outlet of the downstream dry airflow separator (601) to an inlet of the upstream dry airflow separator (101) or to a device (603) for collecting the separated particles.

8. 8. An assembly comprising a selective additive manufacturing apparatus (701) and a separation apparatus according to any one of claims 1 to 7, wherein the selective additive manufacturing apparatus comprises or is connected to the separation apparatus.

9. 10. The assembly of claim 8, further comprising a distribution system (702) for distributing powder material, said distribution system (702) configured to receive particles coming from said separating device.

10. 10. The assembly according to claim 8 or 9, further comprising a collector (703) for collecting unused particles, said collector (703) being connected to an inlet of said separator for separating particles.

11. 9. The assembly of claim 8, further comprising a filter (704) mounted between the collector (703) and an inlet of the separator for separating the particles.

12. The assembly of claim 11, wherein the filtering device (704) comprises a protective screen having a mesh size between 300 μm and 1500 μm.

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