BE1025700B1 - METHOD AND DEVICE FOR REPLACING A DIVISION ELEMENT IN ADDITIVELY MANUFACTURING A PRODUCT IN A POWDER BED - Google Patents

Abstract

Method and device for manufacturing a three-dimensional product starting from a powder (8) by an additive manufacturing technique, with a powder distributor (2) for applying a powder layer (5) on a horizontal building surface (6) in order to successively connect layers of the product, wherein said powder distributor (2) comprises at least two distribution elements (3,4,4 '), each of these distribution elements (3,4,4') being movable between a retracted position and an operational position, in said operational position the distribution element (3) extends opposite said building surface (6) and parallel to the latter at a distance thereof corresponding to the height of the powder layer (5) to be formed, while in said retracted position, the distribution element (4 4 ') is removed from the powder layer (5) to be formed.

Description

METHOD AND DEVICE FOR REPLACING A DIVISION ELEMENT IN ADDITIVELY MANUFACTURING A PRODUCT IN A POWDER BED

The invention relates to a device for the layer manufacture of at least a three-dimensional product starting from a powder, in particular a metal powder, by an additive manufacturing technique, with a building chamber in which a building platform is provided on which said product is produced, and with a powder distributor for the applying a powder layer to a horizontal building surface extending above the building platform to form successive interconnected layers of said product.

The powder distributor is herein movable to and fro over the building surface according to a horizontal distribution direction in order to provide successive powder layers. Furthermore, this powder distributor comprises at least one distribution element which extends parallel to said building surface and, preferably, also substantially transversely of the distribution direction to distribute powder over the building surface in order to form said layer.

The invention also relates to a method for manufacturing a three-dimensional product by an additive manufacturing technique, in which successive powder layers of a powder bed are distributed over a building surface above a building platform.

Herein, powder for manufacturing the product is deposited on the building surface, for example by allowing powder to flow from a powder distributor, to apply a layer to the building surface and a dividing element is moved over the building surface to smooth the layer off and the powder. of the layer evenly. The powder can also be supplied from a

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BE2017 / 5822 2 powder container underneath before it is layered over the building surface.

The distribution element will show wear over time, so that it must be replaced in order to guarantee its proper functioning. Such wear depends on, for example, the duration of the manufacturing process and the roughness of the surface of the building surface.

The dividing element may, for example, consist of a scraper, a dividing strip, a dividing roller or a brush, and may be made of, for example, metal, plastic, flexible or rigid material. The choice can be determined by a person skilled in the art according to the specific additive manufacturing process.

The processes for manufacturing a three-dimensional product by an additive manufacturing technique starting from a powder are known to those skilled in the art. These processes are often carried out in a sealed building room under a protective atmosphere, or in general under a modified atmosphere. Generating the desired atmosphere in the building room is quite time-consuming because this has to be done in various steps. For example, the building chamber must first be made vacuum to remove all oxygen. Subsequently, the building chamber is flushed by introducing nitrogen gas, after which this space with the nitrogen atmosphere is again made vacuum before the desired inert gas is introduced to form a modified atmosphere, in the form of an inert or protective atmosphere, in the building chamber. Depending on the process used, the atmosphere in the building chamber may also be changed by flushing it with the desired inert gas without necessarily having to make the chamber vacuum first.

Replacing a distribution element in the building room is therefore also very time-consuming because the generated or modified atmosphere of the building room must be disturbed. In many cases, the production process even needs to be interrupted for this. For production processes that run for a long period of time, the dividing element may also have to be replaced during the production process itself, and thus the, for example,

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BE2017 / 5822 3 inert atmosphere during a potentially critical production phase of the product to be manufactured.

The European patent application EP3 168 033 A1 describes a mechanism for automatically replacing a distributor element formed by a distributor strip. The distribution strip is hereby removed from a holder of the powder distributor and, subsequently, a spare distribution strip is clamped in the holder. To allow this, the powder distributor must be moved from above the building surface to a location adjacent to this building surface where the spare dividing strip is located and where the used dividing strip to be removed can be deposited. This is a fairly complex mechanism for which the surface of the building room must be increased. Moreover, here too the building process is interrupted for at least a short time.

It is an object of the invention to propose an apparatus and method which can overcome these disadvantages and which make it possible to automatically replace the distributor of the powder distributor without interrupting or interrupting the building process and / or the protective or modified atmosphere in the building room. to disturb.

For this purpose, the powder distributor comprises at least two distribution elements, each of these distribution elements being movable between a retracted position and an operational position, wherein in said operational position the distribution element extends opposite said building surface and parallel to the latter at a distance thereof corresponding to the height of the powder layer to be formed, while in said retracted position, the distribution element is removed from the powder layer to be formed and thus extends at a distance from the building surface which is greater than the height of a powder layer.

The powder distributor expediently comprises a movable holder to which the distribution elements are attached. In this case, each of the at least two distribution elements is preferably attached to the same movable holder.

In particular, the dividing elements and the movable holder have a longitudinal direction that is parallel to the building surface. Preferably, the longitudinal directions of the divider elements and the movable holder extend parallel to each other.

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In an advantageous manner, the movable holder has a central axis and is rotatably mounted with respect to this central axis.

In a very advantageous manner, the distribution elements are distributed over the surface of the movable holder, wherein, preferably, the movable holder is cylindrical and has a central axis which extends substantially transversely to the distribution direction and parallel to the building surface.

According to a preferred embodiment of the device, the distribution elements have a free edge which extends parallel to the building surface and which, preferably, extends substantially transversely to the distribution direction.

According to a special embodiment of the invention, the distribution elements have a longitudinal axis and these distribution elements are rotatable about their longitudinal axis.

The invention also relates to a method in which at least one operational distribution element and one or more spare distribution elements are attached to a movable holder of the powder distributor. Herein, on the one hand, an operational divider is placed in an operational position in which the operational divider strikes the layer and distributes the powder evenly over this layer and, on the other hand, other spare divider elements each in a retracted, non-operational position in which the spare divider elements do not participate in the completion of the layer. Furthermore, the movable holder is moved and thereby, preferably, simultaneously, on the one hand, one of the spare distribution elements is moved to the operational position and, on the other hand, the operational distribution element to a retracted position to replace this operational distribution element, as also claimed in the attached conclusions.

Other details and advantages of the invention will be apparent from the following description of some specific embodiments of the device and method according to the invention. This description is only given as an example and does not limit the scope of the protection claimed; the reference numerals used hereinafter refer to the attached figures.

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Figure 1 is a schematic representation of a cross-section of a powder distributor with holder and distribution elements according to an embodiment of the invention.

Figure 2 is a schematic representation of a cross-section of an alternative embodiment of a holder with dividing elements each of which is formed by a tubular body.

Figure 3 is a schematic representation of a cross-section of another alternative embodiment of a holder with divider elements, each comprising a strip.

Figure 4 is a schematic representation of a cross-section of yet another alternative embodiment of a holder with divider elements each formed by a flap.

Figure 5 is a schematic representation of a cross-section of yet another alternative embodiment of a holder with divider elements wherein these comprise rotatable rollers.

Figure 6 is a schematic representation of a cross-section of a holder with various alternative embodiments of divider elements formed from strips with a beveled free edge.

In the various figures, the same reference numerals refer to the same or analogous elements.

The invention relates generally to a device and a method for replacing a distribution element in a powder distributor. By means of this dividing element, a powder layer is spread to provide a, preferably, homogeneous powder layer with a uniform thickness on a building surface in a building chamber. This is to build up a three-dimensional product layer by layer by allowing an energetic bundle to fall on the successive powder layers that are applied to the building surface according to a pattern corresponding to successive cross-sections of the product. This allows the powder of these successive layers to be melted, layer by layer, completely or partially and then solidified to form successive interconnected layers of the product.

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The invention allows a distribution element to be replaced without having to open the building chamber while maintaining the atmosphere in this chamber. In particular, an inert, protective or other atmosphere in the building chamber can be maintained undisturbed while a worn-out manifold is replaced by a spare manifold.

In addition to the distribution element, which is used to smooth the layers and thus is operational, the powder distributor also comprises at least one spare distribution element. The dividing elements are herein attached to at least one movable holder that allows each dividing element to be displaceable between an operational position in which the dividing element can spread the layer and distribute the powder evenly over this layer and a non-operational or withdrawn position in which the dividing element does not participate at the finish of the layer.

Figure 1 schematically shows a preferred embodiment of a powder distributor 2 with a holder 1, according to the invention, for use in a device for the manufacture of three-dimensional products by an additive production technique.

The powder distributor 2, the holder 1 and the distribution elements 3, 4, 4 'are located in a building chamber of a device which is normally hermetically sealed during the production of a product and which contains an inert atmosphere or is brought under low pressure.

A construction platform is provided in the building chamber which, preferably, is vertically displaceable and on which the product is manufactured. For the sake of clarity of the figures, the construction room and this platform are not shown.

The powder distributor 2 is provided in the building chamber for applying the successive powder layers 5, 5 'to a building surface 6. In this embodiment, the powder distributor 2 comprises a powder compartment 7 with powder 8 for manufacturing the product. The powder 8 flows from this powder compartment 7 to the powder layer 5 on the building surface 6. A system for an automatic supply of powder 8 to the powder compartment 7 can be provided by a person skilled in the art. Alternatively, the powder can, for example, also be deposited directly on the building surface, after which it is distributed by the powder distributor 2. That is possible

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BE2017 / 5822 7 also the powder 8 is supplied directly to the building surface 6 from a powder reservoir with a powder piston, not shown in the figures.

The building surface 6 is a horizontal surface on which the powder layer 5 is to be applied which is covered by the energetic bundle. This building surface 6 extends above the building platform and parallel to the latter. Between the building surface 6 and the building platform there may be previously laid layers 5 '. After the energetic bundle has been moved over the powder layer 5 to form a layer of the product, the building platform is moved down a distance corresponding to the thickness of the powder layer 5. The upper side of the already applied powder layer 5 'with the formed layer of the product then extends into the building surface 6. Subsequently, a subsequent powder layer 5 is applied to the building surface 6 to form a next layer of the three-dimensional product with the aid of said energetic bundle. In this way, successive interconnected layers of the product are formed until the entire product has been built.

The powder distributor 2 comprises the holder 1 which is provided with an operational distribution element 3 and several spare distribution elements 4, 4 '. The operational distribution element 3 is located above the building surface 6 at a distance from this building surface 6 which corresponds to the thickness of the powder layer 5.

The holder 1 with the operational distribution element 3 cooperates with the powder distributor 2, as schematically shown in Figure 1, to smooth the powder layer 5 horizontally and to distribute the powder evenly over this layer 5. The powder distributor 2 is thereby movable over the building surface 6 for applying the successive powder layers 5 to this building surface 6.

The distribution elements herein have a free edge 13 that is parallel to the construction surface 6. Preferably, this free edge 13 also extends transversely to the distribution direction 9. The distance between the free edge 13 of the operational distribution element 3 in the operational position and the construction surface 6 is here substantially equal to the thickness of the powder layer 5. When the powder distributor 2 is moved over the building surface 6, the distribution element 3, which is in the operational position, scrapes with this free edge 13 over the powder which is applied around a powder layer 5.

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By thus moving the powder distributor 2 with the operational distribution element 3 horizontally over the construction surface 6 according to the distribution direction 9, the powder 8 is distributed on the construction surface 6 and the layer 5 is smoothed by this operational distribution element 3. In this way a homogeneous flat layer 5 is obtained with a constant thickness. The powder distributor 2 is thus displaceable according to a reciprocating movement, as indicated by arrow 9 in figure 1.

The powder distributor 2 can be moved back and forth over the building surface 6 according to a horizontal distribution direction 9 over at least the full width of the building platform. The longitudinal direction of the holder 1 here extends transversely to the distribution direction 9. The operational distribution element 3 also extends with its longitudinal direction transversely to the distribution direction 9, as is also the case for the spare distribution elements 4, 4 '.

The holder 1 in this embodiment is rotatably mounted with respect to a rotation axis 10 which is parallel to the longitudinal direction of the powder distributor 2 and which is transverse to the direction 9 in which the powder distributor 2 can be moved back and forth across the building surface 6. The rotation axis 10 in this embodiment is also parallel to the building surface 6.

In this case, the holder 1 is preferably cylindrical and the dividing elements 3, 4, 4 'are mounted on or partially sunk in the cylindrical surface of the holder 1. The axis of rotation 10 of the holder 1 herein coincides, preferably, with its central axis.

When the holder 1 rotates around said axis of rotation 10, as shown by the arrow 11 in the figure 1, the distance between the cylindrical surface of the holder 1 and the building surface 6 remains constant.

During the rotation of the holder 1, the operational distribution element 3 is moved from the operational position to a retracted, non-operational position. At the same time, a spare distribution element 4 is hereby moved from the retracted position to the operational position. The spare distribution element 4 therefore takes the place of the operational distribution element 3. With a further rotation the next spare distribution element 4 'is successively moved to the operational position for

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BE2017 / 5822 replacement of the operational distribution element 3. Thus, in each case one distribution element 3, 4 or 4 'is placed in the operational position while the remaining distribution elements are placed in a retracted position.

During the replacement of the operational distribution element 3 by a spare distribution element 4, the powder distributor 2 can remain above the building surface 6 and / or the powder compartment 7 can also be supplemented with powder 8. Also, if desired, this replacement can take place during the placing of the powder layer 5, filling the powder compartment 7 and / or allowing an energetic bundle to fall on the layer 5, without having to interrupt the building process.

The device can furthermore also be provided with detection means, not shown in the figures, for detecting wear on the distribution element. These means are known per se to the person skilled in the art.

The detection means then cooperate, for example, with drive means of the powder distributor 2, not shown in the figures, to move a distribution element 3, for which wear has been determined, by moving the drive means from the operational position to the retracted position and simultaneously a distribution element 4, 4 'from the retracted position to the operational position.

According to the embodiment in figure 1, the drive means subject the holder 1 to the rotation movement for this purpose.

According to this embodiment of the invention represented in Figure 1, the dividing elements 3,4,4 'are each formed by a cylindrical silicone strip which are fixed in longitudinal recesses in the casing of the cylindrical holder 1. The dividing elements 3,4,4 'can be clamped in these recesses by, for example, providing a tongue and groove system, not shown in the figures.

According to alternative embodiments of the invention, the dividing elements 3,4,4 'are formed by beam-shaped strips, as schematically represented in Figure 3, or hollow round tubes, as schematically represented in Figure 2. These strips and hollow round tubes can also be made from silicone or other suitable materials known to those skilled in the art.

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The free edge 13 of the dividing element 3,4,4 'can also be formed by a free side or a free rib of, for example, a beam-shaped strip as shown, for example, in Figures 3 and 6. The beam-shaped strip from Figure 6 has a chamfered surface that ends on the free edge 13, so that in the operational state this surface is inclined with respect to the building surface at an angle ranging from 0 ° to 90 °.

According to an interesting embodiment of the invention, the dividing elements are formed by raised parts of a corrugated surface that extends over the outer circumference of the container. For example, a silicone jacket with a corrugated surface can be applied over the cylindrical holder, not shown in the figures. The waves are herein preferably parallel to the surface of the cylinder jacket of the holder.

According to another interesting embodiment, the holder consists of a cylindrical body with different, whether or not rigid, upright flaps which extend in the longitudinal direction of the holder and which can each be brought to an operational position, as shown in Figure 4.

According to yet another interesting embodiment, the dividing elements 3, 4, 4 'consist of dividing cylinders which are attached to the holder 1 and which can thereby each rotate about their central axis 12, as shown in Figure 5.

The invention is of course not limited to the above-described devices and methods and the embodiments thereof represented in the accompanying figures, according to the invention. The different features of these embodiments and variants can thus be combined with each other.

The operational distribution element can thus be formed by a plurality of distribution elements placed one behind the other.

For example, in the operational position the distribution element can extend transversely to said distribution direction or also extend slightly obliquely with respect to this distribution direction to distribute powder over the building surface. For example, the dividing elements in the retracted position may or may not be parallel

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BE2017 / 5822 extend on the building surface and / or extend transversely or otherwise with respect to the distribution direction.

The holder can thus consist of a conveyor belt which extends parallel to the building surface in the distribution element. The holder optionally comprises a caterpillar with transverse upright ribs which form the dividing elements. This conveyor belt or caterpillar can thus extend over substantially the full length of the distribution element, which in turn can extend over the full width of the building surface. In general, the holder should not have a cylindrical shape as represented in the accompanying figures, but can be formed by any member that allows to move a divider between said retracted position and said operational position.

The device and method according to the invention can be used with a large number of different techniques for the additive manufacturing of a product.

The invention can thus be applied to, for example, selective laser melting ("selective laser melting" or SLM), selective laser sintering ("selective laser sintering" or SLS), "Electron beam additive manufacturing (EBM)", multi-jet processing. fusion and other techniques in which successive powder layers are covered by an energetic beam, such as a laser beam, or by using a 2D radiation array, to melt or partially powder powder in these layers and then to solidify or sinter successive layers form interconnected layers of the product. Optionally, this can be combined with the addition of binders or selective radiation absorbing or reflecting materials.

In such production methods, after applying each powder layer, at least one energy beam, such as a laser beam, is moved over the powder layer to at least partially melt and solidify or sinter powder from this powder layer to form a layer of the product. The building platform is then moved downwards over a distance corresponding to the thickness of a powder layer in order to

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BE2017 / 5822 12 to distribute the following powder layer on the building surface and thus to form successive interconnected layers of the product.

It is obvious that in an alternative embodiment of the invention, the building platform can be fixed while the powder distributor is moved upwards as the different successive layers are built up.

The invention can be applied in the same way to additive manufacturing techniques in which a binder or selective energy absorber or energy reflector is printed on the powder, whether or not in combination with irradiating the powder layer through a radiation source. In general, the invention can be applied in any production technique where successive powder layers are to be deposited.

Claims (20)

CONCLUSIONS Device for the layered manufacture of at least a three-dimensional product starting from a powder (8) by an additive manufacturing technique, with a building chamber in which a building platform is provided on which said product is produced, and with a powder distributor (2) for applying a powder layer (5) on a horizontal building surface (6) extending above the building platform to form successive interconnected layers of said product, said powder distributor (2) being movable back and forth across the building surface (6) according to a horizontal distribution direction (9) for applying successive powder layers (5), and wherein said powder distributor (2) comprises at least one distribution element (3) which extends parallel to said construction surface and, preferably, also substantially transversely of said distribution direction about powder (8) to distribute over the building surface (6) to form said layer (5), characterized in that the powder distributor (2) is at least t comprises two dividing elements (3,4,4 '), wherein each of these dividing elements (3,4,4') is movable between a retracted position and an operational position, wherein in said operational position the dividing element (3) is situated opposite said building surface (6) and extending parallel to the latter at a distance corresponding to the height of the powder layer to be formed (5), while in said retracted position, the divider (4,4 ') is removed from the powder layer to be formed (5) ). Device according to claim 1, wherein said distribution elements (3,4,4 ') have a free edge (13) which, in the operational position, is parallel to the construction surface (6) and, preferably, substantially transversely of said distribution direction (9) ). Device according to claims 1 or 2, wherein the distribution element (3,4,4 ') is cylindrical or beam-shaped. Device according to one of claims 1 to 3, wherein the dividing element (3,4,4 ') has a circular or polygonal cross section according to a vertical plane that extends in the dividing direction (9). 2017/5822 BE2017 / 5822 Device according to any of claims 1 to 4, wherein each of the divider elements (3,4,4 ') is rotatably mounted with respect to an axis (12) thereof. Device according to one of claims 1 to 5, wherein said dividing elements (3,4,4 ') are formed by a silicone strip, a silicone cord, a silicone tube, a cylindrical roller, a rigid flap, a flexible flap, a comb and / or a combination thereof. Device according to any of claims 1 to 6, wherein said dividing elements (3,4,4 ') are made from metal, ceramic material, polymer material, elastomeric material and / or a combination thereof. Device as claimed in any of the claims 1 to 7, wherein detection means are provided that allow to detect wear of a distribution element (3) which is in said operational position. Device as claimed in claim 8, wherein the powder distributor (2) has drive means which cooperate with said detection means to move a distribution element (3) for which wear has been determined, from said operational position to said retracted position, while a distribution element (4,4) ') is moved by the drive means from the retracted position to said operational position. Device according to one of claims 1 to 9, wherein the powder distributor (2) comprises a movable holder (1) to which said distribution elements (3,4,4 ') are attached. Device according to claim 10, wherein said movable holder (1) has a central axis (10) and is rotatably mounted around this axis (10). Device according to claim 10 or 11, wherein the dividing elements (3,4,4 ') and the movable holder (1) each have an axis (10,12) that is parallel to the construction surface (6). Device according to one of claims 10 to 12, wherein the dividing elements (3,4,4 ') are distributed along the surface thereof of the movable holder (1). 2017/5822 BE2017 / 5822 Device according to any of claims 10 to 13, wherein the movable holder (1) is cylindrical. Device according to one of claims 10 to 14, wherein the central axis (10) of said movable holder (1) extends substantially transversely of said distribution direction (9) and parallel to said construction surface (6). A method for replacing a manifold element (3) contained in a closed building chamber with a modified atmosphere in the manufacture of a three-dimensional product by an additive manufacturing technique, in which the modified atmosphere is retained and the building chamber remains closed, in which the product is produced in said building chamber by connecting successive layers of the product on a building surface (6), in which successive powder layers (5.5 ') on the building surface (6) are formed by powder (8) on this building surface (6) depositing and distributing this powder (8) evenly over the building surface (6) to form a powder layer (5) by smoothing this powder (8) with the divider (3) that is moved over the building surface (6), characterized in that at least two distribution elements (3,4,4 ') are attached to a movable holder (1) of a powder distributor (2), in which, on the one hand, a distribution element (3) is placed in an operation Each position allows this dividing element (3) to wipe the layer (5) and distributes the powder (8) evenly over the building surface (6) and, on the other hand, other dividing elements (4,4 ') are each placed in a retracted position in which these other distribution elements (4,4 ') do not participate in the coating of the layer (5), in which the movable holder (1) is moved together with the distribution elements (3,4,4') around at least one of the distribution elements (3) (4,4 ') between the operational position and the retracted position. A method according to claim 16, wherein the powder distributor (2) together with the movable holder (1) provided with the dividing elements (3,4,4 ') 2017/5822 BE2017 / 5822 16 is moved over the building surface (6) to smooth the layer (5) and distribute the powder (3) evenly over this layer (5). A method according to claim 16 or 17, wherein the movable holder (1) is rotated in the powder distributor (2) about an axis (10) which 5 is parallel to the building surface (6) and thus, on the one hand, one of the divider elements (3) is moved from the operational position to the retracted position and, on the other hand, one of the other divider elements (4,4 ') is displaced from the retracted position to the operational position. The method of any one of claims 16 to 18, wherein The distribution elements (4,4 ') are each moved separately and alternately to the operational position by moving and / or rotating the movable holder (1). Method according to one of claims 16 to 19, wherein powder (8) is deposited on the building surface (6) by flowing this powder (8) from the powder distributor (2) onto this building surface (6) and / or by this powder (8) 15 from a lower powder reservoir.