Device for manipulating particles

Abstract

A device for manipulating particles includes a rotating screen on which a particle structure can be formed and at least one scraper. At least one support element supports the screen at the scraper. The device further includes a particle reservoir and a blower, which is located inside the screen and under the reservoir and which blows a gas in order to fluidize the particles present in the reservoir.

Claims

1. A device for manipulating particles comprising: a screen having a first surface on which a particle structure can form, the first surface being configured to be moved, a first scraper located on a first side of the screen, at a non-zero distance from the first surface, and configured to scrape the particle structure on a first part of the screen, and a first support element located on a second side of the screen and arranged to support the first part of the screen, the second side of the screen and the first side of the screen being separated by the screen, the first surface being configured to be moved so as to move the particle structure in a direction parallel to the tangent to the first surface.

2. The device according to claim 1, further comprising a suction device configured to hold the particles on the first surface.

3. The device according to claim 1, wherein the first support element is configured to tension the first part of the screen.

4. The device according to claim 1, wherein the first support element extends from one side of the screen to the other at the first part of the screen.

5. The device according to claim 1, wherein the first scraper comprises a scraping part intended to be in contact with the particles, the device being configured so that the scraping part can be moved in a direction opposite to the direction of movement of the particle structure on the first part of the screen.

6. The device according to claim 1, wherein the first scraper is a cylinder.

7. The device according to claim 1, wherein the first support element comprises a support cylinder.

8. The device according to claim 1, wherein the support cylinder is configured to be rotated by the screen.

9. The device according to claim 1, further comprising: a second scraper located on the first side of the screen and configured to scrape the particle structure on a second part of the screen, and a second support element located on the second side of the screen and configured to support the second part of the screen.

10. The device according to claim 1, comprising a blower configured to expel a gas through the screen into a particle reservoir.

11. The device according to claim 1, further comprising an ejection device configured to eject the particles from the first surface.

12. The device according to claim 11, wherein the ejection device is located on the second side of the screen and is configured to generate a transport fluid flow which only passes through predetermined parts of the first surface of the screen.

13. A three-dimensional printing system comprising at least once the device according to claim 1, and a means of agglomeration.

14. A method for manipulating particles comprising the steps of: providing a device for manipulating particles, the device comprising: a screen having a first surface on which a particle structure can form, the first surface being configured to be moved, a first scraper located on a first side of the screen, at a non-zero distance from the first surface, and configured to scrape the particle structure on a first part of the screen, and a first support element located on a second side of the screen and configured to support the first part of the screen, the second side of the screen and the first side of the screen being separated by the screen, the first surface being configured to be moved so as to move the particle structure in a direction parallel to the tangent to the first surface; supplying particles on the first surface, moving the particles to the first part of the screen, and scraping the particles, wherein the supply of the particles to the first surface precedes the scraping.

15. A three-dimensional printing method comprising, in this order: the method according claim 14, an ejection of the particles from at least parts of the particle structure, and an agglomeration of said particles.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) Other characteristics and advantages of the invention will appear when reading the following detailed description, for the understanding of which reference is made to the figures annexed hereto, among which are:

(2) FIG. 1 illustrates a sectional view of a part of a device for manipulating particles according to an embodiment of the invention,

(3) FIG. 2 illustrates a device for manipulating particles according to an embodiment of the invention,

(4) FIG. 3 shows a sectional view of a device for manipulating particles according to an embodiment of the invention,

(5) FIG. 4 illustrates a system comprising at least two devices for manipulating particles according to an embodiment of the invention,

(6) FIG. 5 illustrates a system comprising at least two devices for manipulating particles according to an embodiment of the invention,

(7) FIG. 6 shows a sectional view of a part of a device for manipulating particles according to an embodiment of the invention, and

(8) FIG. 7 shows a sectional view of a part of a device for manipulating particles according to an embodiment of the invention.

EMBODIMENTS OF THE INVENTION

(9) The present invention is described with particular embodiments and references to figures, but the invention is not limited by them. The drawings or figures described are only schematic and are not limiting.

(10) For the purpose of this document, the terms “first” and “second” serve only to differentiate between the different elements and do not imply any order between these elements.

(11) In figures, the identical or similar elements may bear the same references.

(12) Although the particles are represented as spherical, the present invention may refer to particles of any shape. In addition, the size of the particles and of the particle structure is generally exaggerated in the figures.

(13) According to a first aspect of the invention, the device comprises a first scraper and a first support element. The first scraper and the first support element are illustrated in FIGS. 1, 2, 3 and 4. According to a second aspect of the invention, the device comprises a reservoir and a blower. The reservoir and the blower are illustrated in FIGS. 2, 3, 5 and 6. The elements illustrated in all the figures of this document are compatible with both aspects of the invention. In addition, a feature presented in an embodiment of one of the two aspects may be present in an embodiment of the other of the two aspects of the invention.

(14) FIG. 1 shows a sectional view of a part of a device 1 for manipulating particles according to an embodiment of the invention. The device 10 comprises a screen 10, a first scraper 86 and a first support element 88.

(15) The screen 10 has a first surface 11 located on a first side 201 of the screen 10 and a second surface 12, opposite to the first surface 11 and located on a second side 202 of the screen 10 opposite to the first side 202. The screen 10 can be arranged to move. In particular, it may be arranged to rotate, for example, according to a closed curve of any shape.

(16) The first side 202 is preferably under-pressurized with respect to the first side 201, by suction device, so that the particles are held on the surface of screen 10 by suction.

(17) A particle structure 30 may form on the first surface 11. It moves with the first surface 11. It generally moves in a direction that is parallel to the tangent to the first surface 11. This direction is illustrated by the arrow 203 at the first scraper 86. The particle structure 30 is scraped by the first scraper 86, so it is generally thicker upstream of the first scraper 86 than downstream of it. The part of the screen 10 on which the scraping is carried out can be called the first part 51 of the screen. It is preferably essentially a straight line tangential to the first surface 11 and perpendicular to the direction 203 of the movement of the structure 30.

(18) The first scraper 86 is located on the first side 201 of the screen 10, at a distance 206 from the screen. The first scraper 86 comprises a scraping part 187 which is designed to be in contact with the particles. It can also be referred to as the first scraping part. Preferably, the scraping part 187 comprises a scraping line 186, perpendicular to the plane of FIG. 1.

(19) The first support element 88 is located on the second side 202 of the screen 10, preferably directly opposite the first scraper 86.

(20) In general, there is a plane, called the first plane 150, which comprises the scraping line 186 and is perpendicular to the first surface 11 at the level of the first scraper 86.

(21) Preferably, the first support element 88 comprises a contact part 188 which is in mechanical contact with the screen 10, in particular with the second surface 12. This contact part can for example be a line parallel to the scraping line 186. The contact part 188 is preferably at least partially in the first plane 150.

(22) According to an embodiment of the invention, the device 1 is arranged so that the scraping part 187 can be set in motion in a direction 204 opposite to the direction 203 of motion of the particle structure on the first part 51 of the screen 10.

(23) FIG. 2 shows a device 1 for manipulating particles according to an embodiment of the invention.

(24) In the embodiment shown in FIG. 2, the screen 10 is cylindrical and the first support element 88 is a support cylinder. The axis of rotation of the screen and that of the first support element 88 are parallel and in the first plane 150. The rotation of the screen 10 causes the first support element 88 to rotate by contact.

(25) FIG. 2 shows that the device 1 can comprise a particle reservoir 80 with a wall 81 formed by a part of the screen 10. Another wall of the reservoir 80 is formed by the first scraper 86. In addition, the device 1 comprises a blower arranged to blow a gas through the screen 10 into a reservoir 80. The blower may comprise, for example, a purge nozzle 91.

(26) FIG. 2 also shows a width 205 of the screen 10, which is a dimension of the screen perpendicular to its direction of movement 203. It can be seen that the first scraper 86 and the first support element 88 extend from one side of the screen 10 to the other.

(27) FIG. 3 shows a sectional view of a device 1 for manipulating particles in a manner embodying the invention. In the embodiment shown in FIG. 3, the screen 10, the first scraper 86 and the first support element 88 are cylindrical. Their axes of rotation are parallel and in the first plane 150.

(28) In the embodiment shown in FIG. 3, the device 1 further comprises a second scraper 87 located on the first side 201 of the screen 10 and arranged to scrape the particle structure 30 from a second part 52 of the screen 10 and a second support element 89 located on the second side 202 of the screen 10 and arranged to support the second part 52 of the screen 10. The second scraper 87 and the second support element 89 are cylindrical, but they could have another shape while remaining within the scope of the present invention. Their axes of rotation are parallel to that of the screen 10 and are in a second plane 152. The second plane 152 is defined with respect to the second scraper 87 as the first plane 150 is defined with respect to the first scraper 86.

(29) A second scraping part 189 is defined with respect to the second scraper 87 as the first scraping part 187 is defined with respect to the first scraper 86.

(30) The second scraper 87 and the second support element 89 are used, in particular, to be able to reverse the direction of rotation of the screen 10 while maintaining the characteristics of the device 1. The second scraper 87 can also be used as a wall for the reservoir 80.

(31) The rotation of the screen 10 causes the first support element 88 and the second support element 89 to rotate by contact.

(32) The first scraper 86 preferably rotates so that the scraping part 187 describes a movement in the opposite direction 204 to the direction 203 of movement of the particle structure on the first part 51 of the screen 10. This rotation is preferably driven by a motor. This rotation allows particles to be returned to the reservoir 80. The device 1 is preferably arranged so that the first scraper 86 can also be rotated in the opposite direction.

(33) The second scraper 87 preferably rotates so that particles are returned to reservoir 80. This rotation is preferably driven by a motor.

(34) In the embodiment illustrated in FIG. 3, the device 1 comprises a blower with a first zone 92 located on the second side 202 of the screen 10 and at an overpressure with respect to the reservoir 80. The blower blows gas through the part of the screen 81 which forms a wall of the reservoir 80. The reservoir 80 is preferably located above the screen 10, so that the particles tend to go to the first surface 11 of the screen 10 due to gravity, despite the blower.

(35) The blower for the device 1 shown in FIG. 3 could comprise the purge nozzle 91 shown in FIG. 2, in addition to the first overpressure area 92.

(36) In the embodiment shown in FIG. 3, the device 1 also comprises a feed element 90. Preferably, the blower also blows into the feed element 90.

(37) The device 1 preferably also comprises a second zone 94, which is at a reduced pressure compared to the pressure on the first side 201 of the screen 10 thanks to a suction device. This reduced pressure keeps the particles on the screen 10. The first 92 and the second 94 zones can be separated by a gas-tight partition wall 93.

(38) In the embodiment illustrated in FIG. 3, the device 1 also comprises an ejection device 121 arranged to eject the particles from the first surface 11 of the screen 10.

(39) For example, the device 1 can operate as follows. The feed element 90 feeds particles into the reservoir 80. The particle structure 30 forms in the reservoir 80 and is driven by the rotation of the screen to form a layer on the first surface 11. On reaching the first scraper 86, the particles are compacted and scraped and some of them remain in the reservoir 80. The particles that continue the movement form a continuous part 31 of the structure 30, i.e. a regular particle layer. On reaching the ejection device 121, some parts of the particle structure 30 are ejected, for example to form a part of a particle stratum. The parts of the particle structure 30 that are not ejected remain on the first surface 11 and form discontinuous parts 32 of the structure 30. These parts pass between the second scraper 87 and the first surface 11 and are reintegrated into the particles in the reservoir 80. The blower is particularly interesting to remove these particles from the first surface 11 so that the structure 30 formed again on these parts of the first surface 11 is as regular as possible and does not keep track of the previous ejections.

(40) FIGS. 4 and 5 illustrate a system 100 comprising at least two devices 1a, 1b for manipulating particles according to an embodiment of the invention. This system can for example be used for a three-dimensional printing. It is possible, while remaining within the scope of the invention, for the system 100 to comprise more than two devices 1 according to the invention. The screens 10a, 10b are arranged parallel to each other, preferably with their axes in the same horizontal plane. In the illustration in FIGS. 4 and 5, the system 100 is printing a three-dimensional printing structure 72 which may comprise particles already agglomerated or not yet agglomerated.

(41) FIG. 4 illustrates that the scrapers 86a, 86b, 87a, 87b can be tilted with respect to the foreground, while the support elements 88a, 88b 89a, 89b are in the foreground.

(42) Preferably, the particles 3a arranged by the first device 1a are particles 3a of a first type, for example capable of being agglomerated by a specific method. Preferably, the particles 3b arranged by the second device 1b are particles 3b of a second type, for example not capable of being agglomerated by this specific method.

(43) Preferably, the screens 10a, 10b rotate with their axis of rotation fixed when a stratum 35 is deposited, and a first substrate 60, which serves as a support for the three-dimensional printing structure 72, advances in one direction or the other. It is also possible, while remaining within the scope of the invention, that the screens 10a, 10b have their axis of rotation moving parallel to the first substrate 60 and that the latter is fixed. It is also possible that the screens 10a, 10b and the first substrate 60 move in a coordinated manner.

(44) The ejection devices 121a, 121b are controlled so as to obtain the desired three-dimensional printing structure 72. Preferably, they are controlled so that the stratum 35 formed by the particles 3a, 3b deposited by the devices 1a, 1b is continuous, i.e. has no holes.

(45) When a particle stratum 35 has been deposited, and before depositing the next stratum 35, the screens 10a, 10b are moved away from the three-dimensional printing structure 72 by a distance preferably equal to the thickness of the stratum 35. This allows the next stratum 35 to be deposited. It is possible for successive stratum 35 to have different thicknesses.

(46) In an embodiment of the invention, the system 100 further comprises at least one compaction roller 141 forming a means of uniforming the height of the powder stratum deposited on the three-dimensional printing structure. Preferably, the system 100 comprises two means of uniformization, each being located on one side of the screens 10a, 10b. In an embodiment of the invention, the system 100 further comprises at least a means of agglomeration 75. Preferably, the system 100 comprises two means of agglomeration 75, each being located on one side of the screens 10a, 10b, further than the means of uniformisation.

(47) The system 100 preferably operates as follows.

(48) A particle bed of the second type 3b, which are not capable of being agglomerated by the method carried out by the means of agglomeration 75, is deposited on the first substrate 60. The particle bed forms the starting three-dimensional printing structure 72.

(49) The reservoir 80a is filled with particles of the first type 3a, which are capable of being agglomerated by the method carried out by the means of agglomeration 75. The reservoir 80b is filled with particles of the second type 3b.

(50) The screens 10a, 10b each rotate about their own axis, which carries away particles from the reservoirs 80a, 80b which are held on the first surfaces by an air suction, e.g. by an external fan connected to the internal volumes of the screens. The air flow rate of the suction is chosen according to the type of powder. The thickness of the particle layer 3a, 3b on the screen 10 is preferably between 50 μm and 1000 μm. This is determined, in particular, by the position of the second scrapers 87a, 87b. The thickness of the stratum 35 may be different from the thickness of the layer on the screen 10. Indeed, the particles of the stratum 35 may spread after deposition. It is also possible to vary the thickness of the stratum 35 by varying the speed of rotation of the screen and/or translation of the three-dimensional printing structure 72.

(51) The screens 10a, 10b move horizontally in a direction perpendicular to their axis, so that they pass through the three-dimensional printing structure 72 while rotating on themselves. Preferably, the speeds of rotation and translation are synchronized so that the relative speed of the nearest point of the screen 10 and the three-dimensional printing structure 72 is zero. This ensures that the particles have no tangential velocity to the screen during transfer, which allows for more accurate deposition. Particles that have not been deposited will flow back to the reservoirs 80a, 80b and can be used later.

(52) Preferably, once the stratum 35 is deposited, it is uniformized by the compaction roller 141 and then agglomerated by the means of agglomeration 75 in order to integrate the three-dimensional printing structure 72. The next stratum 35 is then deposited.

(53) It is possible that the next stratum 35 is deposited on the return path from the stratum that has just been integrated into the three-dimensional printing structure 72. For example, the deposition of strata (as well as compaction and agglomeration) can be done from right to left and from left to right. In this case, it is preferred that the system has two means of uniformisation and two means of agglomeration 75 as shown in FIG. 16.

(54) FIG. 6 shows a sectional view of a part of a device 1 for manipulating particles according to an embodiment of the invention. FIG. 7 shows a sectional view of a part of a device 1 for manipulating particles in an embodiment of the invention. In the second aspect of the invention, the device 1 does not necessarily comprise a scraper, and if it comprises a scraper, it does not necessarily comprise a support element as described herein. The device 1 comprises a screen 10 having a first surface 11 on which a particle structure 30 may be formed. The screen is preferably similar to that described with reference to any of FIGS. 1 to 5. The device 1 also includes a blower arranged to blow a gas through the screen 10 into a particle reservoir 80. The blower may, for example, comprise a purge nozzle 91 located opposite the reservoir 80 with respect to the screen 10, or a first zone 92 located opposite the reservoir 80 with respect to the screen 10 and at an overpressure with respect to the reservoir 80.

(55) In other words, the invention relates to a device 1 for manipulating particles. The device 1 comprises a rotating screen 10 on which a particle structure 30 can be formed. According to a first aspect of the invention, the device 1 comprises at least one scraper 86, 87 and at least one support element 88, 89 supporting the screen 10 at the level of the scraper 86, 87. According to a second aspect of the invention, the device 1 comprises a particle reservoir 80 and a blower, preferably located inside the screen 10 and under the reservoir 80, and blowing a gas to lift the particles present in the reservoir 80.

(56) The various embodiments and aspects of the invention are combinable with the system described in international patent application PCT/EP2017/071039.

(57) The present invention has been described in relation to specific embodiments, which are purely illustrative and should not be considered as limiting. In general, the present invention is not limited to the examples illustrated and/or described above. The use of the verbs “comprise”, “include”, or any other variant, as well as their conjugations, can in no way exclude the presence of elements other than those mentioned. The use of the indefinite article “a”, “an”, or the definite article “the” to introduce an element does not exclude the presence of a plurality of such elements. The reference numbers in claims shall not limit their scope.