Slotted nut for selective additive manufacturing device

Abstract

A nut (1) having a threaded hole (2) extending along a first axis (A) for moving a strip to deliver powder to a selective additive manufacturing device, the nut (1) comprising slots (3a, 3b) extending through the thickness of the nut from an outer surface (4) of the nut (1) to an inner surface (5) of the threaded hole (2), the slots extending along a plane passing through the first axis (A) across at least one thread pitch (6) of the threaded hole (2).

Description

[Technical field]

[0001] The present invention relates generally to the field of selective additive manufacturing. [Background technology]

[0002] Selective additive manufacturing involves the formation of a three-dimensional object by consolidating selected areas in successive layers of powder material (metal powder, ceramic powder, etc.). The consolidated areas correspond to successive cross sections of the three-dimensional object. Consolidation is performed layer-by-layer by, for example, full or partial selective melting using an energy source.

[0003] The powder material or powder can be transported from the powder container to the production zone using a strip designed to slide within a slide.

[0004] Some powder may enter the surrounding atmosphere in a suspended state, creating a working environment that is harmful to the mechanical components of the equipment, especially those involved in the movement transmission equipment, such as the movement of the strip in the slide.

[0005] It is known from the prior art to use a screw-nut system to move the strip. The gap between the screw and the nut is blocked by substances suspended in the environment. The accumulation of these powders reduces the mechanical play of the screw-nut system, eventually resulting in its loss. Frequent replacement of components is required. Summary of the Invention [Problem to be solved by the invention]

[0006] Thus, there is a need for a system for moving the strip that exhibits a longer service life when operating in an environment containing suspended material powder. [Means for solving the problem]

[0007] A general object of the present invention is to overcome the limitations of the prior art. In particular, the object is to provide a system for moving a strip that exhibits a longer service life when operating in an environment containing suspended material powder.

[0008] Specifically for this purpose, the present invention provides a nut for moving a strip to deliver powder to a selective additive manufacturing apparatus, the nut having a threaded hole extending along a first axis, the nut comprising a slot extending through a thickness of the nut from an outer surface of the nut to an inner surface of the threaded hole, the slot extending along a plane passing through the first axis, across at least one thread pitch of the threaded hole.

[0009] Such a nut may advantageously be provided with various additional features, either alone or in combination: - a slot extending along a first axis (A) from an end of the nut perpendicular to the first axis; - two slots, each extending from one end of the nut along a first axis; the slot has a width along a third axis perpendicular to the first and second axes that is at least three times greater than a maximum size of a particle suspended in the operating environment; the slot has a width along a third axis of between 500 micrometers and 10,000 micrometers; the slot has a width along a third axis of between 1000 micrometers and 2000 micrometers; the outer surface of the nut is cylindrical extending along the first axis; the outer surface of the nut is cylindrical and further has two grooves extending along a first axis, each of the grooves being formed by a first rectangle parallel to the second axis and a second rectangle parallel to a third axis, the two grooves being located in 180 degree opposite sections of the slot.

[0010] The present invention provides a system for moving a strip for a selective additive manufacturing device, comprising the above-mentioned nut and a strip to which the nut is fixed to prevent the nut from rotating relative thereto, wherein the system for moving the strip comprises a screw including a thread that engages with a threaded hole in the nut, and the slot in the nut is located 180 degrees opposite the strip relative to a first axis.

[0011] This system for moving the strip may advantageously be supplemented with various features, either alone or in combination: a pin designed to be received in a slot in the nut so as to prevent the nut from rotating about a first axis relative to the strip; the strip comprises, at its lower part, a recess designed to receive the part of the nut located between the two grooves; - A half shell (12) which is fixed firmly to the strip and which is designed to surround the nut with sufficient mechanical play to allow the nut to self-align when it is attached to the screw.

[0012] The invention relates to an apparatus for selective additive manufacturing of three-dimensional objects, comprising a system for moving the strip as described above, and also to a method of use of such an apparatus, in which the additive manufacturing is carried out on the basis of an additive manufacturing powder, and in which the slot has a width along a third axis, perpendicular to the first and second axes, at least three times greater than the maximum size of the particles of the additive manufacturing powder.

[0013] Other characteristics and advantages of the invention will become apparent from the following description, which is given by way of example only and is non-limiting, and which must be read in conjunction with the accompanying drawings, in which: [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic diagram of an embodiment of a system for distributing powder material in an additive manufacturing device. [Figure 2A]FIG. 1 shows a diagram for a selective additive manufacturing apparatus according to one embodiment of the present invention. [Figure 2B] FIG. 1 shows a diagram for a selective additive manufacturing apparatus according to one embodiment of the present invention. [Figure 2C] FIG. 1 shows a diagram for a selective additive manufacturing apparatus according to one embodiment of the present invention. [Figure 2D] FIG. 1 shows a diagram for a selective additive manufacturing apparatus according to one embodiment of the present invention. [Diagram 3] FIG. 1 is a schematic diagram of an embodiment of a system for moving a strip for a selective additive manufacturing apparatus according to one aspect of the present invention. [Figure 4] FIG. 1 is a schematic diagram of a selective additive manufacturing device having a system for moving a strip according to one possible embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] System for moving the strip FIG. 1 illustrates one embodiment of a system 26 for moving a strip 33 . The system 26 includes a metering device 31 adapted to meter the amount of powder passing through the nozzle 36 .

[0016] The strip 33 can move in the slide 32 under the action of a screw 35. The strip 33 is adapted to translate in the direction of the screw 35. By means of a system 30 comprising in particular a nut for moving the strip, the rotation of the screw 35 causes a translational movement of the strip 33 in the slide 32.

[0017] A slide 32 is located near the production zone and extends between the metering device 31 and an end 37 which limits the translational movement of the strip. During the filling stage, the strip 33 moves under the nozzle 36. While the nozzle 36 dispenses a predetermined amount of powder, the strip 33 moves towards the end 37 such that a layer of powder builds up on the strip 33.

[0018] Once the powder has been deposited over the entire strip 33 provided for this purpose, the strip moves to abut against the end 37. In this position, the powder layer covering the strip 33 faces the production zone and the object to be produced and can be distributed over the last produced layer of the object.

[0019] Nuts for selective additive manufacturing equipment 2A, 2B, 2C, and 2D show nuts for a selective additive manufacturing device. The nut 1 has a threaded hole 2 extending along a first axis A. Figure 2A is a view of an end 7a of the nut 1 perpendicular to the axis A.

[0020] FIG. 2A shows a second axis B perpendicular to the first axis A, and a third axis C perpendicular to the second axis B and the first axis A. The two arrows D in figure 2A indicate a section through the nut 1 along the second axis B. This section is shown in figure 2B.

[0021] 2B shows the first axis A and the threaded hole 2, the thread of which is indicated. The distance 6 between two successive points in the thread represents the thread pitch 6. The outer surface 4 of the nut 1 is the surface of the nut 1 that is radially outward with respect to the first axis A. The inner surface 5 of the nut 1 is radially inward with respect to the first axis A and is the surface of the nut 1 which corresponds to the surface defined by the threads of the screw hole.

[0022] The nut 1 has slots 3a, 3b extending along a first axis A across at least one thread pitch 6 of the threaded hole 2, and the slots extend through the nut along a second axis B from an outer surface 4 of the nut 1 to an inner surface 5 defined by the threaded hole 2. The slots 3a, 3b place the internal space of the screw hole 2 in communication with the external space of the nut 1 in the direction of the second axis B.

[0023] Inside the additive manufacturing device, the nut 1 can be placed on the screw 35 so that the slots 3a, 3b are positioned in a vertical plane towards the bottom of the nut 1. The deposit of powder material, in other words the powder grains filling the gap between the screw 35 and the nut 1, can be carried along the surface 5 towards the slots 3a, 3b. The deposit then falls under gravity into the slots 3a, 3b and leaves the gap. This limits the reduction and elimination of the mechanical play of the screw-nut system. This extends the service life of the screw-nut system in an environment containing suspended additive manufacturing powder.

[0024] The slots 3a, 3b may advantageously not extend along the entire length of the nut thread so as not to impede the conversion of part of the rotational energy of the screw into translational energy of the nut.

[0025] The length of the nut 1 along the first axis A, along which the slot does not extend, must be long enough to prevent the screw mounted in the screw hole 2 from further deforming or opening the nut 1, or to ensure that the rotational energy of the screw is converted into translational energy of the nut.

[0026] The screw hole 2 can be provided with one or more flights. In any case, the slots 3a, 3b extend along the first axis A across at least one thread pitch 6 of each flight of the screw hole 2. This makes it possible to fill the gap between the screw and the nut and to ensure that all trajectories of the powder particles conveyed along the surface 5 pass through the slots 3a, 3b.

[0027] 2B shows an end 7a and an opposite end 7b of the nut 1. The distance between the two ends 7a, 7b corresponds to the length of the screw hole 2 of the nut 1. The slots 3a, 3b of the nut 1 may conveniently extend along a first axis A from an end 7a or from an end 7b of the nut 1. Both ends 7a and 7b are planes perpendicular to the first axis A.

[0028] In this situation, the slots 3a, 3b appear as ends 7a or 7b. The slots 3a, 3b put the inner space of the screw hole 2 and the outer space of the nut 1 in communication along the second axis B but also obliquely in the cut plane of FIG. 2B.

[0029] This makes it possible to increase the number of deposits that can enter the slots 3a, 3b under gravity if the nut 1 is placed in the additive manufacturing apparatus so that the slots 3a, 3b lie in a vertical plane towards the floor or bottom of the additive manufacturing apparatus. The angle at which the deposits can be ejected outwards is more in this situation.

[0030] The nut may advantageously be provided with two slots 3a, 3b each extending along the first axis A from one end 7a, 7b of the nut 1. In situations where the nut 1 is placed inside an additive manufacturing device to expel powder deposits that have accumulated in the gap, the presence of the two slots increases the thread area through which the deposits can be expelled, thus increasing the number of deposits that can be expelled.

[0031] Such a nut is shown in figure 2B, where two slots 3a and 3b are shown, between which a material thickness 8 of the nut remains, which must be long enough so that a screw installed in the screw hole 2 does not further deform or open the nut 1, or to ensure that the rotational energy of the screw is converted into translational energy of the nut.

[0032] 2C shows a bottom view of the nut 1 along the second axis B from the side of the two slots 3a, 3b and the material thickness 8. Slot 3a is shown extending from end 7a and slot 3b is shown extending from end 7b. Figure 2D shows a perspective view of the nut 1 constructed in Figures 2A and 2C. The slots 3a, 3b have a width along a third axis C that accommodates the characteristics of the powder present in suspension within the working environment. Typically, the size of the powder particles suspended within the additive manufacturing machine environment, and therefore within the nut environment, is between 0 and 200 micrometers.

[0033] The slots 3a, 3b can be designed such that the width along the third axis C is greater than three times the maximum diameter of the powder grain. In this way, three particles present in the slot cannot be jammed in the direction of the third axis C. Furthermore, two particles present in the slot cannot be jammed in the direction of the third axis C. This feature can reduce the possibility of the slot being blocked by powder grains and increase the ability of the nut 1 to discharge powder grains accumulated in the screw-nut gap. Therefore, the width along the third axis C can be selected to be greater than 600 micrometers.

[0034] The width along the third axis C may also be chosen to be equal to a value between 500 and 10,000 micrometers, advantageously between 1,000 and 2,000 micrometers. The nut 1 may be cylindrical, in which case the outer surface 4 corresponds exactly to a cylinder extending along the first axis A.

[0035] The nut 1 can have any other shape. For example, a cylindrical shape extends along a first axis A and has two grooves 9a, 9b also extending along the first axis A. Each groove 9a, 9b defines a first rectangle parallel to a second axis B and a second rectangle parallel to a third axis C. The two grooves are located in 180° opposite areas of the slots 3a, 3b. Figures 2A and 2D show the two grooves 9a and 9b.

[0036] Thus defined, the shape of the outer surface 4 has a portion 10 located between the two grooves 9a, 9b and protruding from the remainder of the outer surface 4. This portion can be inserted into a housing of the strip, located below the strip. The nut thus takes and maintains a position with the slots 3a, 3 in a vertical plane towards the floor and the bottom of the additive manufacturing device. Furthermore, this shape, which defines the small volume of the nut 1, allows it to be easily installed and removed in the additive manufacturing device.

[0037] System for moving the strip FIG. 3 is a schematic diagram of an embodiment of a system for moving a strip for a selective additive manufacturing device. The system 30 for moving the strip comprises a strip 33 and the above-mentioned nut 1. The nut is attached to the strip such that the nut cannot rotate relative to the strip.

[0038] The strip movement system 30 comprises a screw 35 , the thread of which engages in the threaded hole 2 of the nut 1 . The system is designed so that the slots 3 a , 3 b in the nut are located in 180 degree opposite sections of the strip 33 relative to the axis of the screw 35 .

[0039] In order to control the translational movement of the strip by the rotation of the screw, it is necessary that the nut does not rotate relative to the strip. Such a rotation prevention allows the position of the slots 3a, 3b to always be maintained in the same area. Thus, the slots 3a, 3b can be maintained in a vertical plane towards the floor and bottom of the additive manufacturing device throughout the operation of the additive manufacturing device.

[0040] One possibility to prevent the nut from rotating relative to the strip is the use of a pin 11 designed to be received in the slots 3a, 3b of the nut 1. One end of the pin thus engages in the slots 3a, 3b in the direction of the first axis A. The pin can be chosen to be of sufficient length so that its other end protrudes from the slots 3a, 3b and can be received in a hole in the strip 33 or in a component fixed firmly to the strip 33.

[0041] The use of a cylindrical pin, with the pin diameter being smaller than the width of the slot in the direction of the third axis C, allows for mechanical play between the nut 1 and the pin. This can facilitate assembly and disassembly of the structure whilst ensuring that the nut 1 is prevented from rotating.

[0042] Another possibility for preventing the nut from rotating is to locate the portion 10 of the nut 1 between the two grooves 9a, 9b in a recess of the strip. In this way, the portion 10 comes into abutment against the recess and, as a result, the nut is prevented from rotating about the axis A relative to the strip.

[0043] Such a recess makes it possible to easily position the nut 1 in a position for discharging the powder deposit. Moreover, by choosing a recess that is slightly wider than the width of the part 10 of the nut 1 located between the two grooves 9a, 9b, it is possible to allow for mechanical play. This makes it possible to fix the nut 1 in a given angular position relative to the strip 33 without imposing an exact positioning in the direction of the first axis A and the second axis B.

[0044] The nut is surrounded by a half shell 12 which is fixedly secured to the strip 33. The internal dimensions of the half shell 12 are slightly larger than the external dimensions of the nut 1 and are designed so that there is mechanical play between the nut and the half shell. This mechanical play is sufficient to allow self-alignment of the nut on the threads 35. In this way the nut is mounted in a floating manner and the service life of the nut flights is increased.

[0045] The internal dimensions of the half shells 12 are slightly larger in all directions than the external dimensions of the nut 1. In particular, there is a mechanical play for the translational movement of the nut relative to the half shells along the first axis A. When the nut moves in one direction about the first axis A, the limit of the movement allowed by the mechanical play for this translational movement comes into abutment against the half shells, which prevents the nut from moving. This allows the strip 33 to move.

[0046] The half shells 12 are provided with notches 13 designed to be positioned opposite the slots 3a, 3b of the nut 1, so that any particle deposits that fall out of the slots 3a, 3b can continue to fall towards the floor and bottom of the additive manufacturing device.

[0047] Selective Additive Manufacturing Equipment The selective additive manufacturing apparatus 21 of FIG. a support such as a horizontal plate 23 on which various layers of additive manufacturing powder (metal powder, ceramic powder, etc.) are successively deposited, making it possible to produce a three-dimensional object (the fir-tree shaped object 22 in the figure), a system 26 for distributing powder material, designed to supply the production powder to a lamination roller or spreader, the distribution system 26 comprising a metering device 31, a slide 32 and a strip 33; a mechanism 24 for distributing the metal powder on the plate, this mechanism 24 having, for example, laminating rollers and / or spreaders 25 for distributing various successive layers of powder (moving along the double arrow A); - an assembly 28 with an energy source 211, for example a laser beam and / or an electron beam, for (totally / partially) melting the distributed thin layer. The energy generated by the energy source 211 comes into contact with the distributed thin layer in the powder plane; a control unit 29 controlling the various components of the device 21 on the basis of pre-stored information (memory M); a mechanism 210 (moving along the double arrow B) capable of lowering the support of the plate 23 as each layer is deposited, Equipped with.

[0048] The components of the apparatus 21 are disposed within a sealed chamber 217 which can be connected to an inert gas circuit and / or at least one vacuum pump 218 (if an electron beam is used).

Claims

1. A system (30) comprising a nut (1) for moving a strip (33) for a selective additive manufacturing device, comprising: The nut (1) has a screw hole (2) extending along a first axis (A), The nut (1) comprises slots (3a, 3b) extending through the thickness of the nut (1) from an outer surface (4) of the nut (1) to an inner surface (5) of the screw hole (2) along a second axis (B) perpendicular to the first axis (A); The slots (3a, 3b) extend along a plane passing through the first axis (A) across at least one thread pitch (6) of the threaded hole (2); The nut (1) is fixed to the strip (33) so as not to rotate relative to the strip (33); the system (30) comprises a screw (35) including a thread engaging the threaded hole (2) of the nut (1), the slots (3a, 3b) of the nut being located 180 degrees opposite the strip (33) with respect to the first axis (A); A system (30).

2. The slots (3a, 3b) extend along the first axis (A) from ends (7a, 7b) of the nut (1) perpendicular to the first axis (A); The system (30) of claim 1.

3. comprising two slots (3a, 3b) each extending from one end (7a, 7b) of said nut (1) along said first axis (A); A system (30) according to claim 1 or 2.

4. the slots (3a, 3b) have a width along a third axis (C) perpendicular to the first axis (A) and the second axis (B) that is at least three times greater than the maximum size of a particle suspended in the operating environment; A system (30) according to any one of claims 1 to 3.

5. said slots (3a, 3b) having a width along a third axis (C) perpendicular to said first axis (A) and said second axis (B) of between 500 micrometers and 10,000 micrometers; A system (30) according to any one of claims 1 to 3.

6. the slots (3a, 3b) have a width along a third axis (C) perpendicular to the first axis (A) and the second axis (B) of between 1000 and 2000 micrometers; A system (30) according to any one of claims 1 to 3.

7. The outer surface (4) of the nut (1) is a cylinder extending along the first axis (A). A system (30) according to any one of claims 1 to 6.

8. the outer surface (4) of the nut (1) is cylindrical and has two grooves (9a, 9b) extending along the first axis (A), each of the grooves (9a, 9b) being defined by a first rectangle parallel to the second axis (B) and a second rectangle parallel to a third axis (C) perpendicular to the first axis (A) and the second axis (B), the two grooves being located in 180° opposite zones of the slots (3a, 3b); The system (30) of claim 7.

9. a pin (11) designed to be received in the slot (3a, 3b) of the nut (1) so as to prevent the nut (1) from rotating about the first axis (A) relative to the strip (33), A system (30) according to any one of claims 1 to 8.

10. The nut (1) is the nut of claim 8, said strip (33) comprises, in its lower part, a recess designed to receive the part (10) of said nut (1) located between said two grooves (9a, 9b); A system (30) according to any one of claims 1 to 9.

11. a half shell (12) fixedly secured to said strip (33) and designed to surround said nut (1) with sufficient mechanical play and to allow self-alignment of said nut (1) when said nut is attached to said screw (35); A system (30) for moving according to any one of claims 1 to 10.

12. A selective additive manufacturing apparatus (21) comprising a system for moving (20) according to any one of claims 9 to 11.

13. 13. A method of use of a selective additive manufacturing device (21) according to claim 12, wherein additive manufacturing is performed on the basis of an additive manufacturing powder and the slots (3a, 3b) have a width along a third axis (C), perpendicular to the first axis (A) and the second axis (B), that is at least three times larger than the maximum size of a particle of the additive manufacturing powder.

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