NL2013860B1

NL2013860B1 - Apparatus for producing an object by means of additive manufacturing.

Info

Publication number: NL2013860B1
Application number: NL2013860A
Authority: NL
Inventors: Johannes Magielsen Mark; Peter Albert Van Haendel Rob; Patrick Webb Chris
Original assignee: Additive Ind Bv
Priority date: 2014-11-24
Filing date: 2014-11-24
Publication date: 2016-10-11

Abstract

The invention relates to an apparatus for producing an object by means of additive manufacturing. The apparatus comprises a process chamber for receiving a bath of material which can be solidified; a structure for positioning the object in relation to the surface level of the bath of material; and a solidifying device for solidifying a layer of the material on the surface. The apparatus further comprises an extraction device fluidly connected to the process chamber and arranged for extracting material out of the process chamber; and blowing means for inducing a gaseous flow in the process chamber effecting the material to be extracted. According to the invention, said blowing means comprise a plurality of blow nozzles fluidly connected to the process chamber and directed in a plurality of different directions.

Description

Title: Apparatus for producing an object by means of additive manufacturing

Description

The present invention relates to an apparatus for producing an object by means of additive manufacturing, comprising a process chamber for receiving a bath of material which can be solidified; a structure for positioning the object in relation to the surface level of the bath of material; a solidifying device for solidifying a layer of the material on the surface; and an extraction device fluidly connected to the process chamber and arranged for extracting material out of the process chamber. 3D printing or additive manufacturing refers to any of various processes for printing a three-dimensional object. Traditional techniques like injection molding can be less expensive for manufacturing, for example, polymer products in high quantities, but 3D printing or additive manufacturing can be faster, more flexible and less expensive when producing relatively small quantities of three-dimensional objects.

It is anticipated that additive manufacturing becomes more and more important in the future, as the increasing competitive pressure forces companies to not only manufacture more economically with a constant high product quality but also to save time and costs in the area of product development. The life span of products is continuously shortened. In addition to product quality and product costs, the moment of market introduction is becoming increasingly important for the success of a product.

The three-dimensional object may be produced by using a directed energy beam to selectively sinter a powder, or liquid material to produce a three-dimensional, 3D, object. In particular, a computer controlled additive manufacturing apparatus may be used which sequentially sinters a plurality of layers to build the desired object in a layer-by-layer fashion. Primarily additive processes are used, in which successive layers of material are laid down under computer control. These objects can be of almost any shape or geometry, and are produced from a 3D model or other electronic data source.

In order to print a three-dimensional object, a printable model is to be created with a computer design package or via a 3D scanner, for example.

Usually, the input is a 3D CAD file such as an STL file, a STEP file or a IGS file. Before printing the object from a CAD file, the file is to be processed by a piece of software called a sheer, which converts the model into a series of thin subsequent layers. Further, apparatus settings and vectors are generated for controlling the creation of each of the subsequent layers. A laser comprised in the computer controlled additive manufacturing apparatus follows these settings and vectors to lay down successive layers of liquid, powder, paper or sheet material to build the 3D object from a series of cross sections. These layers, which correspond to the virtual cross sections from the CAD model, are then joined or fused to create the final 3D object.

To reduce operational costs of the apparatus, it is an object to fully utilize the capacity of the apparatus and, at the same time, make sure that the total production lead time of a three dimensional object is minimized, i.e. the production queue is minimized.

One of the challenges in the manufacturing of three dimensional objects, in particular in additive manufacturing of metal objects, is related to the deposition of the layer to be solidified. According to prior art practice, powdered layer of material is removed from the process chamber by means of a suction device after having solidified selective parts of said layer of material. Then, a new bath of material to be solidified is deposited in the process chamber. Removing of powder takes a lot of time, and is relatively difficult when complex objects are being produced.

The accuracy and speed of production of the known apparatus, and in particular of the powder extraction, do not satisfy the current additive manufacturing demands.

It is therefore an object of the invention to provide an apparatus for producing an object by means of additive manufacturing, with which improved speed and accuracy of manufacturing may be obtained, and in particular wherein the powder extraction can be performed with increased speed and increased effectivity.

Thereto, the invention provides an apparatus according to claim 1. The apparatus comprises, a process chamber for receiving a bath of material which can be solidified, in particular a bath of powdered material that can be solidified in order to make metal products. A structure is provided for positioning the object in relation to the surface level of the bath of material. A solidifying device, such as a laser device, for solidifying a layer of the material on the surface, in particular by means of electromagnetic radiation, is provided. To remove powder of the bath of material, for example after having solidified selective parts of the layer of material, an extraction device is provided which is fluidly connected to the process chamber and arranged for extracting material out of the process chamber. According to the invention, the apparatus comprises blowing means for inducing a gaseous flow in the process chamber effecting the material to be extracted. By using a gaseous flow in the process chamber, the material to be extracted is affected and blown around in the process chamber, and the possibility of the extraction device being able to extract said material is increased.

To further improve the possibility of extraction of material from the process chamber, said blowing means comprise a plurality of blow nozzles fluidly connected to the process chamber and directed in a plurality of different directions. By providing a plurality of nozzles, having a plurality of different directions, it is possible to induce a flow over the support structure which is able to better reach the various parts of the support structure. This way, the coverage of the blowing means is improved, such that an improved part of material in the process chamber is subjected to the gaseous flow, and is picked up by this gaseous flow, such that extraction of material is improved, both in speed and in amount. The use of a plurality of nozzles having a plurality of directions decreases the chance of formation of so called “lee” sides behind the object being produced, said “lee” sides being parts of the bath of material where the object to be produced provides a shelter from the gaseous flow. Thus, the apparatus according to the invention is able to extract more material in less time, and thus the goal of the invention is achieved.

In an embodiment, at least one of the plurality of blow nozzles is a movable nozzle. The apparatus may be arranged, for instance by means of drive means connected to a control unit, for moving the movable nozzle during blowing of the blowing means, such that the flow induced in the process chamber is subject to changes in directions. This means that the nozzle is able to reach a bigger part of the process area, such that more material to be solidified is affected by the flow induced. Thus, material extraction, in particular powder extraction, may be improved by using one or more movable nozzles. In particular, the plurality of nozzles may be movable nozzles, or a combination of stationary nozzles and movable nozzles may be used.

In an embodiment, the at least one movable nozzle is arranged to be moved by the flow discharged by said movable nozzle. Rather than being moved by drive means and a control unit, it is possible to arrange the nozzle in such a way that the nozzle is moved by the forces exerted by the flow discharged by said nozzle. For instance, the nozzle end may be arranged in the form of a flexible hose or tube being provided with a freely movable end. In such an embodiment, flow discharged through the nozzle will automatically lead to movement of the freely movable end of the flexible hose or tube, such that a movable nozzle is obtained. Advantageous of this embodiment is that it delivers a relatively randomized pattern of movement of the flow directions discharged by said movable nozzle. Furthermore, this embodiment is relatively cheap.

In an embodiment, the plurality of nozzles are arranged for inducing gaseous flows having different pressures. One of the nozzles may then be arranged for providing a flow having a relatively low pressure, and the other may be arranged for providing a flow having a relatively large pressure, which may be used to induce turbulences in the flow pattern.

In an embodiment, the plurality of nozzles are arranged for inducing gaseous flows having different volume flows. One of the nozzles may be arranged for inducing a gaseous flow having a relatively large volume flow, in particular that substantially corresponds to the volume flow being extracted by the extraction means. The other nozzle may then be arranged for inducing a relatively small flow, affecting a relatively small area of the process chamber. This, in particular in combination with the different pressures as described above, improves the amount of material extracted by the apparatus.

In an embodiment, the extraction device comprises an extraction tube connected to a pumping unit, wherein an inlet opening of the extraction tube is positioned within the process chamber. This allows for extraction of material from the process chamber.

In an embodiment, the extraction device is provided with a filter unit for filtering a flow of liquid or powdered material extracted from the process chamber. For instance, it is possible to filter particles from the gaseous flow, in order to collect particles, which may, for instance, be re-used again in solidifying a further layer. It is furthermore possible to filter and collect unwanted particles, for instance particles having a specific dimension, such as particles exceeding a certain dimension.

In an embodiment, the filter unit is a cyclone filter. A cyclone filter is a very effective filter for filtering flows containing solid particles, and collecting these solid particles. The cyclone filter is thus effective for filtering powder material to be solidified.

In an embodiment, the extraction device comprises a holder for holding material extracted from the process chamber. The holder may be used for permanently or temporarily storing the extracted material. The holder may be connected to a recoating device, which uses part or all of the extracted material for laying down a further layer of material to be solidified in the process chamber.

In an embodiment, the extraction device comprises an exhaust tube for exhausting a gas flow associated with the material extracted from the process chamber. This allows for the gas flow to be exhausted to the environment.

In an embodiment, the cyclone filter is connected to the holder and the exhaust tube, for collecting material in the holder, and venting the gas through the exhaust tube. As indicated above, this allows the gas with material to be passed through the cyclone filter, in such a way that the particle material is collected and the gas is exhausted through the exhaust tube.

According to an aspect, the invention provides a method of using an apparatus according to the invention, in particular a method for extracting material out of the process chamber of said device, wherein the method comprises the step of inducing a gaseous flow in the process chamber for effecting the material to be extracted. According to the invention, the plurality of blow nozzles are used for inducing a plurality of jets that are directed in a plurality of different directions. The advantages of such a method and/or usage have already been described above with respect to the apparatus.

Embodiments of the invention will be described in the following in connection with the Figures. In the Figures:

Figure 1 is an overview of an apparatus according to the present invention for additive manufacturing an object;

Figure 2 is a schematic overview of an embodiment of the apparatus according to the invention; and

Figure 3 is a schematic overview of a further embodiment of the apparatus according to the invention.

Figure 1 shows an overview of an apparatus 1 for producing an object 2 by means of additive manufacturing. The apparatus 1 is build from several frame parts 11, 12, 13. The apparatus comprises a process chamber 3 for receiving a bath of material 4 which can be solidified. In a lower frame part 11, a shaft 50 is formed, wherein a support 5 is provided for positioning the object 2 in relation to the surface level L of the bath of material 4. The support 5 is movably provided in the shaft 50 , such that after solidifying a layer, the support 5 may be lowered, and a further layer of material may be solidified on top of the part of the object 2 already formed. In a top part 13 of the apparatus 1, a solidifying device 7 is provided for solidifying a selective part of the material. In the embodiment shown, the solidifying device 7 is a laser device, which is arranged for producing electromagnetic radiation in the form of laser light, in order to melt a powdered material provided on the support, which then, after cooling forms a solidified part of the object 2 to be produced. However, the invention is not limited to the type of solidifying device 7. As can be seen, the electromagnetic radiation 71 emitted by the laser device 7 is deflected by means of a deflector unit 74, which uses a rotatable optical element 75 to direct the emitted radiation 71 towards the surface L of the layer of material 4. Depending on the position of the deflector unit 74, radiation may be emitted, as an example, according to rays 72, 73.

The apparatus 1 shown further comprises an extraction device 9 fluidly connected to the process chamber 3 and arranged for extracting material 4 out of the process chamber. Blowing means 10 are provided on the opposite side of the process chamber 3 for inducing a gaseous flow in the process chamber 3 effecting the material to be extracted. Furthermore, a further blowing means 93 is provided above, and directed to, the level L of material 4. Thus, as follows from Fig. 1, the blowing means 10, 93 comprise a first blow nozzle 10 provided on the left hand side, as seen in Fig. 2, of the process chamber 3 and directed to the extraction means 9. The blowing means 10, 93 further comprise a second blow nozzle 93 provided on the top right hand side, as seen in Fig. 2, of the process chamber 3 and directed to the center of the level L of the material 4. It can thus readily be seen that the first blow nozzle 10 and the second blow nozzle 93 are directed in opposite directions. In effect, a plurality of blow nozzles 10, 93 are provided that are fluidly connected to the process chamber 3 and directed in a plurality of different directions.

With this, the blowing means are able to affect a larger part of the surface level L of the material 4, such that in principle more material is taken up by the gaseous stream and may be extracted by means of the extraction device 9.

In particular, the first blow nozzle 10 is arranged to provide a relatively large volume flow at a relatively low pressure, and the second blow nozzle 93 is arranged for providing a relatively small volume flow at a relatively high pressure. The first blow nozzle 10 is arranged for providing a volume flow that substantially corresponds to the volume extracted by the extraction means 9. The second blow nozzle 93 is arranged for providing bursts of flow, provided at a relatively high pressure, for inducing local disturbances in the flowing pattern, for instance turbulences, to affect a larger amount of material on the surface level L of the process chamber 3.

In the embodiment shown in Fig. 1, the first 10 and second 93 blowing nozzles are connected, via lines 82 and 84, to a control unit 94, which may be used to start and/or stop the blowing nozzles 10, 93. The extraction device 9, for instance in the form of a suction device 9, is also connected to this control unit 94, such that operation thereof may be synchronized. It is, however, conceivable that the extraction device 9 is provided with a separate control unit. Fig. 2 further shows that the extraction device 9 is connected to a holder 90 for holding the material 4 extracted from the process chamber, for instance for later re-use.

The nozzles 10 in Fig. 1 is embodied as a stationary nozzle, and the nozzle 93 may be embodied as a movable nozzle. Driving means may be provided (not shown), which are known per se, and that may be used to aim the nozzle to different parts of the processing chamber 3, in particular during blowing of the nozzles. This way, the jet released by the nozzle may be aimed, randomly or deliberately, towards different parts of the surface level L of the bath of material 4. For instance, the nozzle may be tilted up and down, or moved from left to right, during deliberate aiming. In an embodiment, the free end of the movable nozzle is freely movable, for instance in the form of a freely movable flexible hose or tube, such that the least one movable nozzle is arranged to be moved by the flow discharged by said movable nozzle. This induces a randomized flow in the process chamber 3 during blowing of the nozzle, which leads to an improved chance of picking up and extracting more material. Further nozzles may be provided, which may be movable nozzles as described above.

Fig. 2 shows an embodiment of the apparatus according to the invention, having two additional nozzles 92, 93, which may be movable nozzles 92, 93, and in which in particular details of the apparatus downstream of the extraction device 9 are shown. The extraction device 9 comprises an extraction tube 121 comprising a pumping unit (shown as one unit 121), wherein an inlet opening of the extraction tube 121 is positioned within the process chamber 3. Furthermore, the extraction device 9 is fluidly connected, via line 87, to a filter unit 101, in particular a cyclone filter unit 101, which may be used to filter the extracted gaseous flow containing the material extracted from the process chamber. For instance, this allows powdered material contained in the flow to be filtered and collected for further usage. The cyclone filter unit 101 is connected, via line 111, to a first holder 103 or collector, for collecting powdered material filtered by the filter unit 101. The gaseous flow may, after having passed the filter unit 101, be exhausted by the apparatus by means of exhaust tube 114 and exhaust outlet 104. In this way, the gaseous flow may be vented through the exhaust tube 114 and outlet 104. In a preferred embodiment, the exhaust tube 114 is connected to the blowing means 10, such that the filtered gas flow may once again be introduced into the process chamber.

The first holder 103 is connected, via line 112, to a second holder 102, provided above the first holder 103. Material collected in the first holder 103 may be transferred via line 112 to the second holder 102, for later use. An overflow line 113 is provided between the second holder 102 and the filter unit 101, which may be used to filter the extracted material a plurality of times, by re-feeding said material back to the filter unit a number of times, for instance.

Thus, the extraction device 9 may be connected to one or more holders 103, 102 for holding material extracted from the process chamber. This material may be re-used, for instance for laying down a further layer of material to be solidified.

Fig. 3 shows a further embodiment of the apparatus according to the invention, which mainly differs from the embodiment shown in Fig. 1 in that the blowing means 10 comprise a blowing unit 95 having a plurality of blowing nozzles 99 is. The nozzles 99 of this blowing unit 95 are directed towards the extraction device 9, in order to blow material 4 from the process chamber 3 towards the extraction device. The nozzles 99 are, in the embodiment shown, mainly directed in a horizontal direction. The nozzles 99 are, in an embodiment, arranged for being stationary, such that a generally horizontal flow towards the extraction device 9 is obtained. To improve the extraction of material 4, the nozzle 93 is provided and directed in a different direction relative to the nozzles 99 of the further blowing unit 95. This ensures that material positioned partly behind the object 2, when viewed in the blowing direction of the nozzles 99 of the further blowing unit 95, as indicated by region R in Fig. 3, may be affected by the nozzle 93, such that removal of material in this region R is also possible. To enhance the extraction of material 4, one or more of the nozzles 99, 92, 97 shown in Fig. 3, and in particular one of the nozzles 92 and 93, may be embodied as movable nozzles.

Furthermore, Fig. 3 schematically shows that the apparatus comprises a movable cover-element 120, which is arranged to be movable within the process chamber 3 for covering a top part of the process chamber during use of the blowing means 10 and extraction means 9. The movable cover-element 120 may then be used to divide the volume of the process chamber into two parts, such that the volume of the part comprising the bath of material is reduced. This increases the ease with which the powdered material can be removed from the process chamber, and ensures furthermore that the other part is protected by the cover-element, in such a way that damage to the apparatus in this other part due to moving powdered particles is prevented. The cover-element 120 may be embodied as a pivotable element, or a translatable element.

It will be clear to those skilled in the art, that the invention is described above by means of several embodiments. However, the invention is not limited to these embodiments. Combinations of individual parts of the several embodiments are conceivable. The desired protection is defined by the appended claims.

Claims

An apparatus for manufacturing an object by means of additive manufacturing, comprising: a process chamber for receiving a bath of powdered material that can be solidified; a support for positioning the object with respect to the surface level of the bath of material; a solidifying device for solidifying a layer of the material on the surface; an extraction device in fluid-flowing communication with the process chamber and adapted to extract material from the process chamber; and blowing means for inducing a gas flow in the process chamber, which influences the material to be extracted, the blowing means comprising a plurality of blowing nozzles that are fluidly connected to the process chamber and directed in a plurality of various directions.

The device of claim 1, wherein the at least one of the plurality of blow nozzles is a movable nozzle.

The device of claim 2, wherein the at least one movable nozzle is adapted to be moved by the flow issued by the movable nozzle.

Device as claimed in any of the foregoing claims, wherein the plurality of nozzles are adapted to induce gas flows with different pressures.

Device as claimed in any of the foregoing claims, wherein the plurality of nozzles are adapted to induce gas flows with different volume flows.

Device according to any of the preceding claims, wherein the extraction device comprises an extraction tube connected to a pump unit, an inlet opening of the extraction tube being positioned within the process chamber.

7. Device as claimed in any of the foregoing claims, wherein the extraction device is provided with a filter unit for filtering a flow of liquid or powdered material extracted from the process chamber.

The device of claim 7, wherein the filter unit is a cyclone filter.

The device of any one of the preceding claims, wherein the extraction device comprises a container for holding material extracted from the process chamber.

Device as claimed in any of the foregoing claims, wherein the extraction device comprises an outlet tube for outlet of a gas flow associated with the material extracted from the process chamber.

Device as claimed in claims 8, 9 and 10, wherein the cyclone filter is connected to the holder and the outlet tube, for collecting material in the holder, and for venting the gas through the outlet tube.

A method of using a device according to any one of the preceding claims, wherein the method comprises the step of inducing a gas flow in the process chamber to influence the material to be extracted, using the plurality of blow nozzles connected fluid-flowing with the process chamber and are directed in a plurality of different directions.