Methods and equipment for constructing layers using various raw material powders

Abstract

The present disclosure relates to an apparatus (1) for producing at least one first workpiece (25) from at least one first raw material powder (9) in a first build job using a selectively-generated layer build method, and at least one second workpiece (33) from at least one second raw material powder (23) in a second build job using a selectively-generated layer build method, the apparatus (1) having at least one raw material powder guide for guiding the first raw material powder and / or the second raw material powder (9, 23) during the build job, characterized in that the apparatus (1) has a cleaning operation mode, in which in the cleaning operation mode, between the first build job and the second build job, a predetermined cleaning amount of the second raw material powder (23) passes through at least one section of the raw material powder guide, and raw material powder (9, 23) comprising a residual portion of the first raw material powder (9) is discharged from the section of the raw material powder guide.

Description

[Technical field]

[0001] The present disclosure relates to a method for building product layers with different raw material powders, in particular by selective laser melting (Laser Powder Bed Fusion (LPBF)), and to an installation therefor. The present disclosure also relates to a control program in the form of software and / or hardware for such an installation for carrying out the method. [Background technology]

[0002] The production of three-dimensional workpieces using the generative layer build method is often called 3D printing. A special form of the generative layer build method is selective laser melting, in which the material to be processed, which is a powdered raw material, is applied in the form of a thin layer on a base plate. The powdered raw material is selectively, i.e. site-specifically, melted or sintered by laser irradiation and forms a layer of the workpiece after solidification. As soon as a workpiece layer is completed, the base plate is lowered by one layer thickness and the raw material powder for the next layer is deposited, which is then selectively melted or sintered again by laser irradiation. This is repeated during a so-called "build job" until all melted workpiece layers together form a three-dimensional workpiece. During the build job, a base plate is lowered step by step into the workpiece space, which is surrounded by the workpiece space's enclosure. That is, the workpiece space expands as the three-dimensional workpiece becomes larger in the course of the build job, and the volume of the workpiece space that is not filled by the three-dimensional workpiece is filled with unmelted raw material powder. For example, ceramic, metallic or plastic materials, or mixtures of these materials, or mixtures of different types of ceramic, metallic or plastic materials, can be used as material powders.

[0003] Installations of the generative layer building method for creating workpieces are often not limited to being able to operate with only one type of raw material powder. Some multi-material installations can produce workpieces from two or more different raw material powders, but the different raw material powders are guided separately in the installation (see, for example, WO 2014 / 111072). Regardless of whether it is a single-material installation or a multi-material installation, different types of raw material powders can be used for different build jobs. However, to be able to use a different raw material powder in the same raw material powder guide of the installation in a new build job than in the previous build job, the corresponding raw material powder guide of the installation must be thoroughly cleaned in order to prevent an unacceptably high proportion of the previous raw material powder remaining in the new workpiece. In order to be able to guarantee a high material quality of the workpiece, the corresponding contamination limits may be very strict depending on the raw material powder.

[0004] However, thorough cleaning of equipment often requires significant manual labor, with many parts of the equipment having to be disassembled, individually vacuumed and / or cleaned manually, and finally reassembled. Depending on the size of the equipment, this can take hours or even days for specially trained and experienced employees. In addition to the corresponding cleaning costs, there are additional shutdown costs for the time the equipment cannot be operated. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2014 / 111072 Summary of the Invention [Problem to be solved by the invention]

[0006] Therefore, an objective of the present disclosure is to reduce the time and cost of cleaning equipment between two build jobs that use different feedstock powders.

[0007] The object is achieved by an apparatus, a method for constructing a generating layer, and a control program according to any of the independent claims. Preferred embodiments can be seen from the dependent claims, the following description and the drawings. [Means for solving the problem]

[0008] According to a first aspect of the present disclosure, optionally, In a first build job using the production layer build method, at least one first workpiece is produced from at least one first raw material powder; and In a second build job using the productive layer build method, at least one second workpiece is produced from at least one second raw material powder. A facility for producing The installation has at least one raw material powder guide for guiding a first raw material powder and / or a second raw material powder during a build job, The installation is characterized in that it has a cleaning operating mode, in which, between a first build job and a second build job, a predetermined cleaning amount of second raw material powder passes through at least one section of the raw material powder guide, and a raw material powder mixture comprising residual portions of the first raw material powder is discharged from the section of the raw material powder guide.

[0009] The raw powder guide includes all parts of the equipment that come into contact with the corresponding raw powder. The raw powder can be transported along the raw powder guide, for example, by gravity, mechanically and / or fluidically. The section of the raw powder guide through which the second raw powder of the cleaning amount passes in the cleaning mode of operation can extend over the entire raw powder guide, or only a part of it, or several parts thereof. The raw powder guide can optionally include a recycling system, whereby at least a part of the raw powder is circulated through the raw powder guide. The section of the raw powder guide through which the second raw powder of the cleaning amount passes in the cleaning mode of operation can extend in particular over the recycling system. The multi-material equipment can have several raw powder guides that are widely spaced apart from each other. In this case, the cleaning mode of operation can be provided individually for at least one section of one, several or all raw powder guides. In particular, the section of the raw powder guide that fluidly transports the raw powder along the piping by positive or negative pressure is difficult or impossible to clean manually without having to previously disassemble and subsequently reassemble the parts of the raw powder guide. Therefore, the cleaning mode of operation is particularly advantageous for such sections of the feed powder guide.

[0010] In particular, the section of the raw powder guide to be cleaned in the cleaning mode of operation passes through a process chamber in which the raw powder is selectively melted layer by layer as a powder bed during a build job. Optionally, in the cleaning mode of operation, a second raw powder of the cleaning amount is fed into the process chamber layer by layer as a powder bed, and the raw powder mixture is discharged from the process chamber. However, unlike the build job, the powder bed is not selectively melted in the cleaning mode. This has the advantage that existing conventional equipment can be adapted to be able to carry out the cleaning mode of operation according to the invention by simply regenerating or executing a software update, without having to adapt or modify the hardware of the equipment.

[0011] That is, in the cleaning mode of operation, the second raw material powder is transported through the installation in exactly the same way as it is done during a build job, but with the difference that the laser is not operated to selectively melt the powder bed. The cleaning mode of operation can therefore be called a "dummy" build job "without power", or a "0 watt build job". The second raw material powder of the cleaning volume cleans at least the section of the raw material powder guide to be cleaned in the cleaning mode of operation, by carrying away any residues of the first raw material powder with the second raw material powder and mixing them into the cleaning volume. Thereby, the residues of the first raw material powder present in the section of the raw material powder guide to be cleaned in the cleaning mode of operation are discharged together with the second raw material powder as a raw material powder mixture. That is, the cleaning mode of operation automates the cleaning between two build jobs with different raw material powders, which significantly reduces the time and costs of cleaning. In particular, in relatively large installations and / or installations with automatic raw material powder recycling, i.e. circulating raw material powder guides, the advantages of the cleaning mode of operation compared to manual cleaning can be very large.

[0012] It is also conceivable that in the cleaning operation mode, the section of the raw powder guide to be cleaned passes through the process chamber, but no powder bed is built up. In the cleaning operation mode, unlike the build job, the second raw powder of said cleaning amount can be dropped and / or transported directly into an overflow or collection container. For this, the coater laying the powder bed in the build job can be controlled accordingly to be transported directly into the overflow or collection container in the cleaning operation mode. In some installations, on one or both sides of the powder bed, the overflow or collection container is located directly below the intermediate reservoir that fills the coater to lay the powder bed in the build job. In such installations, it is conceivable that in the cleaning operation mode, the second raw powder of said cleaning amount falls directly from the intermediate reservoir into the overflow or collection container. In that case, the coater can be positioned between them and open downwards in order to be flushed as well, or it can be moved away from the raw powder guide in order not to be flushed. Alternatively or additionally, it is conceivable that in the cleaning mode of operation the cleaning amount of second raw powder is directly conveyed to a workpiece container positioned below the process chamber, for example when a bottom plate for the powder bed is positioned in a lowered position in the workpiece container. The cleaning mode of operation can also be applied in installations where raw powder is conveyed as an upwardly facing pile of powder next to the powder bed during a build job and a coater in the form of a doctor blade laterally smooths the pile of powder into a powder bed.

[0013] However, the main purpose of the cleaning mode of operation is to clean sections of the equipment's raw powder guide that are difficult or impossible to clean manually without having to disassemble parts of the equipment beforehand and then reassemble them. These are, for example, the pipes that transport the raw powder. That is, depending on the structure and accessibility of the process chamber, it may be possible to relatively easily clean the process chamber, possibly including intermediate reservoirs, coaters and overflows, manually without removing parts. In the cleaning mode of operation, it is therefore not necessary to pass the second raw powder of the cleaning amount through the process chamber. For example, a cleaning bypass can be provided in order to pass the second raw powder of the cleaning amount by the process chamber and thus shorten the duration of the cleaning cycle.

[0014] It may happen that the second raw powder of the cleaning volume is contaminated by the residues of the first raw powder so that the raw powder mixture discharged after the passage must be discarded and cannot be reused. However, the cost of the second raw powder of the cleaning volume is nowadays much lower than the cleaning cost and the shutdown cost, since the cost of many raw powders has dropped significantly in recent years. Furthermore, in addition to the cleaning operation mode, a quick, manual, rough cleaning of all easily accessible equipment parts, especially the process chamber, can be performed in advance without parts removal in order to minimize the amount of the first raw powder residue. This can be done in just a few minutes by employees with little expertise and experience, for example by suction. If the contaminants in the raw powder mixture discharged from the section of the raw powder guide are below the permissible limit, the raw powder mixture can even be used for the second building job or other things.

[0015] Optionally, the installation can be set to hold the bottom plate of the workpiece space in a defined position in the cleaning mode of operation. Unlike a build job, the workpiece space does not expand downwards in the cleaning mode of operation. The defined position can be a zero position located at the top, in which the workpiece space remains practically closed and no powder bed is formed on the bottom plate. The second raw powder of the cleaning amount is then directly conveyed to an overflow or collection container. If the defined position is, for example, lower than one layer thickness, a powder bed is formed, but another layer that is applied to the powder bed after the first layer is in the cleaning mode of operation, in particular, almost completely dropped from the powder bed and discharged from the process chamber. Since in the cleaning mode of operation the raw powder is not selectively melted between the laying of layers, in the cleaning mode of operation the period between the laying of layers is much shorter than in a build job. The laying of layers and the removal of layers can be performed seamlessly one after the other, which accelerates the cleaning mode of operation. The cleaning mode can be further accelerated if, in the cleaning mode, no layer is placed on the bottom plate as a powder bed, but is transported directly to an overflow or collection container. If the defined position of the bottom plate is relatively deep in the workpiece container, i.e. the workpiece space forms an upwardly open volume in the cleaning mode, then in the cleaning mode, direct transport can be made to the workpiece space, i.e. the workpiece space can be used as a collection container for the raw powder mixture in the cleaning mode.

[0016] Optionally, the cleaning amount of the second raw powder can be up to 30%, preferably up to 10% of the amount of the second raw powder required for the second building job. This cleaning amount can depend on the equipment and on the first and / or second raw powder. In this case, depending on the equipment and on the first and / or second raw powder, an empirical value can be specified that indicates a sufficient cleaning amount to ensure that the residual amount of the first raw powder in the raw powder mixture is below an acceptable range. Optionally, the cleaning amount of the second raw powder can be an absolute minimum cleaning amount defined for the equipment, for example 5 liters.

[0017] Optionally, an upper limit for the residual fraction of the first raw powder in the raw powder mixture discharged from the section of the raw powder guide in the cleaning mode of operation can be predefined. This can also be a zero tolerance, i.e. the cleaning mode of operation is not possible for certain combinations of first and second raw powders, since the upper limit can only be achieved by thorough manual cleaning. The higher the contamination tolerance, the better the cleaning mode of operation can be applied with the smallest possible cleaning volume and short transit time. The smaller the contamination tolerance, the longer the cleaning mode of operation can be run and / or the larger the cleaning volume can be selected.

[0018] Optionally, the installation can be set up so that the raw powder mixture discharged from the section of the raw powder guide in the cleaning operating mode is re-fed once or several times to the section of the raw powder guide, for example by a recycling system or manually. This increases the duration of the cleaning operating mode but makes better use of the cleaning volume. Since only a small part of the cleaning volume is actively cleaning, i.e. carrying away the first raw powder, at each pass, the first raw powder remaining in the section of the raw powder guide can thereby be significantly reduced. It is also possible to clean the raw powder mixture between passes. Such intermediate cleaning is especially sensible if the first and second raw powders, for example, have very different grain sizes and can be easily and reliably separated by sieves or filters, or if, for example, one of the raw powders exhibits a higher ferromagnetic property than the other raw powder and can be easily and reliably separated by magnetic separation.

[0019] Optionally, the equipment may further comprise an analysis unit, which is configured to detect the residual amount of the first raw powder in the raw powder mixture discharged from the section of the raw powder guide in the cleaning operation mode, which is useful for being able to detect or measure the cleaning effect. The analysis unit allows checking whether the equipment is sufficiently cleaned.

[0020] Optionally, the installation can be set to re-feed the raw powder mixture discharged from the section of the raw powder guide in the cleaning mode of operation multiple times or until the residual amount of the first raw powder in the raw powder mixture falls below a predefined upper limit. This can be checked, for example, by an analytical unit once during the cleaning mode of operation, periodically or continuously or at the end of the cleaning mode of operation. Alternatively, this can be checked by randomly taking samples in a laboratory.

[0021] Optionally, the equipment can be configured to increase the cleaning amount of the second raw powder if the residual amount of the first raw powder in the raw powder mixture discharged from the section of the raw powder guide in the cleaning operation mode exceeds a predetermined upper limit. In order to reduce the consumption of the cleaning amount of the second raw powder, it may be advantageous to first use a relatively small cleaning amount for the cleaning operation mode and to determine the residual amount of the first raw powder in the raw powder mixture discharged from the section of the raw powder guide to check the success of the cleaning. If the cleaning amount is insufficient, the cleaning amount can be increased because the upper limit has been exceeded. However, it is preferable not to increase the cleaning amount first, but to increase the number of times the cleaning amount passes through the section of the raw powder guide of the equipment to be cleaned.

[0022] Optionally, the installation can be operated with preselected different raw materials as the first and second raw material powders, respectively, and a measure (degree Maβ) of the residual compatibility between each of the different raw materials as the first and / or second raw material powders is stored and / or can be called up in a predefined allocation matrix. Empirical values, standardized tolerances, upper limits and / or prohibitions can be stored in the allocation matrix. The allocation matrix can allocate precisely defined raw materials to each other or to groups of raw materials. For example, certain raw materials as a group can behave similarly or the same with respect to residual compatibility, whereby residual compatibility applies to the entire group of the raw materials. As an example, for example AlSi 10 a group of aluminum-based raw powders such as Mg, AlSi7Mg0.6, and AlSi9Cu3; a group of titanium-based raw powders such as Ti6Al4V ELI (grade 23), TA15,Ti (grade 2); a group of copper-based raw powders such as CuNi2SiCr, CuSn10, CuCr1Zr; a group of iron-based raw powders such as 316L (1.4404), 15-5PH (1.4545), 17-4PH (1.4542), 1.2709, H13 (1.2344); a group of nickel-based raw powders such as HX, IN625, IN718, IN939; and a group of cobalt-based raw powders such as CoCR28Mo6, SLM (registered trademark) MediDent. Alternatively or additionally, the allocation matrix may include grouping of ingredients by size, allocation of size groups to each other, and corresponding residue compatibility. The allocation matrix may be stored in the equipment itself and / or stored externally, for example on an external server or cloud, and may be called up by the equipment via a data connection.

[0023] The residue compatibility as an entry of the allocation matrix can be, for example, an absolute or relative value between 0 and 1, or a percentage that is a measure of the acceptable residue of the first raw powder in the raw powder mixture discharged from the section of the raw powder guide in the cleaning operation mode. It can be, for example, a volume fraction, a weight fraction, or a quantity fraction. The residue compatibility can also be zero between two raw materials, i.e., the cleaning operation mode is possibly not sufficient for cleaning when a certain second raw material follows a certain other first raw material. If the residue compatibility is very low or the residue compatibility is zero, a thorough manual cleaning is possibly absolutely necessary.

[0024] According to a second aspect of the present disclosure, selectively - at least one first workpiece from at least one first raw material powder in a first build job; and - producing at least one second workpiece from at least one second feedstock powder in a second build job; A method for constructing a generation layer using an equipment for producing A method for building a production layer is provided, characterized in that the equipment is cleaned between a first build job and a second build job in a cleaning operating mode by passing a predetermined cleaning amount of a second raw material powder through at least a section of a raw material powder guide of the equipment and discharging a raw material powder mixture including a residual portion of the first raw material powder from the section of the raw material powder guide.

[0025] Optionally, a section of the raw material powder guide passes through the process chamber and in a raw material operating mode the cleaning amount of the second raw material powder is supplied to the process chamber layer by layer as a powder bed, and in a cleaning operating mode the raw material powder mixture can be discharged from the process chamber without selectively melting the powder bed.

[0026] Optionally, in the cleaning mode of operation, the bottom plate of the workpiece space can be held in a defined position.

[0027] Optionally, the amount of second feedstock powder cleaned can be up to 30%, preferably up to 10%, of the amount of second feedstock powder required for the second build job.

[0028] Optionally, the amount of second raw powder cleaned can be an absolute minimum cleaned amount defined for the facility, for example 5 liters.

[0029] Optionally, an upper limit for the residual content of the first feedstock powder in the feedstock powder mixture discharged in the cleaning mode of operation may be predefined.

[0030] Optionally, in the cleaning operating mode, the raw powder mixture discharged from the section of the raw powder guide can be re-fed into the section of the raw powder guide once or several times.

[0031] Optionally, residual amounts of the first feedstock powder in the feedstock powder mixture discharged in the cleaning mode of operation may be sensed.

[0032] Optionally, in the cleaning operation mode, the raw material powder mixture discharged from the process chamber can be re-fed to the section of the raw material powder guide multiple times, or until the residual amount of the first raw material powder in the raw material powder mixture discharged in the cleaning operation mode falls below a predetermined upper limit.

[0033] Optionally, the cleaning amount of the second raw material powder may be increased if the residual amount of the first raw material powder in the raw material powder mixture discharged in the cleaning mode of operation exceeds a predetermined upper limit.

[0034] Optionally, a measure of residue compatibility between each two of the different raw materials as the first raw material powder and / or the second raw material powder can be retrieved from a predefined and stored assignment matrix.

[0035] According to a third aspect of the present disclosure, a control program for the aforementioned equipment for carrying out the aforementioned method is provided. The control program may be installable and / or executable in the equipment as software and / or hardware. The control program includes control instructions especially for a cleaning operation mode. The control program can be designed as an update to an existing control program of the equipment and / or as an additional module. An already existing equipment is modified to become an equipment with a cleaning operation mode according to the present invention disclosed herein, simply by the installation and / or executable of the control program as an update and / or additional module, without modifying the hardware of the equipment.

[0036] The present invention will now be described in more detail with reference to the accompanying drawings. [Brief description of the drawings]

[0037] [Figure 1] FIG. 1 is a schematic diagram of an exemplary embodiment of an equipment disclosed herein at the start of a first build job. [Diagram 2] FIG. 1 is a schematic diagram of an exemplary embodiment of an equipment disclosed herein at the end of a first build job. [Diagram 3] FIG. 2 is a schematic diagram of an exemplary embodiment of an equipment disclosed herein after a first build job. [Figure 4] FIG. 1 is a schematic diagram of an exemplary embodiment of an equipment disclosed herein in a cleaning mode of operation before a second build job. [Diagram 5] FIG. 2 is a schematic diagram of an exemplary embodiment of an apparatus disclosed herein in a cleaning mode of operation. [Diagram 5] FIG. 2 is a schematic diagram of an exemplary embodiment of an apparatus disclosed herein in a cleaning mode of operation. [Figure 6] FIG. 1 is a schematic diagram of an exemplary embodiment of an equipment disclosed herein at the start of a second build job. [Figure 7] FIG. 1 is a schematic diagram of an exemplary embodiment of an equipment disclosed herein at the end of a first build job. [Figure 8] FIG. 2 is a schematic diagram of an exemplary embodiment of an allocation matrix. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] 1 to 7 show an installation 1 for manufacturing three-dimensional workpieces 25, 33 using a layer-by-layer building method in the form of selective laser melting (laser powder bed fusion (LPBF)). The installation 1 has a raw powder guide passing through the process chamber 3, shown here very simply. The installation 1 also has a workpiece space 5, 5' arranged below the process chamber 3. Furthermore, the installation 1 has a refill container 7 of fresh and / or processed, i.e. recycled, raw powder 9, which feeds into an intermediate store 11. A horizontally movable coater 13 allows a powder bed 15 of raw powder 9 to be placed on the workpiece space 5. A doctor blade or squeegee (not shown), which may be part of the coater 13, smooths the surface of the powder bed and sends excess raw powder 9 from the process chamber 3 into a collection container 17. The raw powder 9 is transported downwards mainly by gravity. The raw powder guide includes all parts of the installation that come into contact with the corresponding raw powder.

[0039] The raw powder guide of the installation 1 here optionally comprises a recycling system 19, in which the raw powder 9 finally entering the collection container 17 is again fed to the refill container 7 via a filter and treatment element 21. The recycling system 19 can comprise a negative pressure conveying system, in which the raw powder 9 is fluidly transported through a line. However, the recycling system 19 does not have to be part of the installation 1, and the collection container 17 can be manually removed and emptied, and the raw powder 9 contained therein can be treated in an external filter and treatment facility to fill a new refill container 7. To that end, the refill container 7 is connected so that it can be replaced manually. The advantages of the installation 1 disclosed herein are more pronounced in a relatively large installation 1 incorporating a recycling system 19, but the effect according to the invention can also be obtained in a small installation 1 not incorporating a recycling system 19.

[0040] According to the invention, the installation 1 can operate with at least two different raw powders 9, 23, namely a first raw powder 9 as shown in Figs. 1-3 and a second raw powder 23 as shown in Figs. 4-7. Fig. 1 shows the installation 1 at the start of a first build job for producing a first workpiece 25 (see Figs. 2 and 3) from the first raw powder 9. The workpiece space 5 is formed by a portable workpiece container 27 which is positioned under the bottom opening of the process chamber 3 for the first build job. As shown in Fig. 1, the vertically movable bottom plate 28 of the workpiece space 5 is placed in its uppermost position at the start of the first build job, whereby the bottom plate 28 is aligned with the bottom of the process chamber 3 and substantially blocks the bottom opening of the process chamber 3. A first layer of the first raw powder 9 is then laid on the bottom plate 29 by the coater 13. Then, by means of a laser light output coupling device 29 on the ceiling side of the process chamber 3, a laser beam 31 is guided over the powder bed 15 so that the powder bed 15 is selectively melted at the desired locations. As soon as the laser melting is finished, the bed plate 28 is moved down one layer thickness into the workpiece container 27 and a new layer is deposited by the coater 13, which is then selectively melted again by means of the laser beam 31. The coater 13 is refilled after each layer from the intermediate reservoir 11, which is filled from the refill container 7. In order to be able to produce straight layers as the powder bed 15, the coater 13 always deposits an excess of feedstock 9, which is then smoothed over the powder bed 15 and the excess is transferred from the process chamber 3 to a collection container 17.

[0041] FIG. 2 shows the situation at the end of the first build job, where the first workpiece 25 has just been completed. After the first build job, it is already recognized that the raw powder guide of the equipment is contaminated with the first raw powder 9, precisely over all parts of the equipment 1 that have been in contact with the first raw powder 9. For the next build job, the workpiece container 27 is removed and replaced with a new workpiece container 27', which is shown in FIG. 3 to be positioned under the process chamber 3 to start the new build job. The workpiece container 27 with the first workpiece 25 is transferred to an unloading station (not shown here) for unloading. In FIG. 3 it is shown that the equipment 1 has many parts of the raw powder guide that are still contaminated with the first raw powder 9. The process chamber 3, which is usually accessible through a service opening (not shown), can be manually aspirated and / or cleaned relatively simply and quickly. The process chamber 3 can also be optionally pre-cleaned, post-cleaned or intermediately cleaned by automatic suction. Furthermore, it is sensible to transport the raw powder guide of the installation 1 as empty as possible after the first build job in order to remove the first raw powder 9 as single-type as possible. However, certain sections of the raw powder guide of the installation, such as the recycling system 19, the refill container 7, the intermediate storage 11, the coater 13 and the collection container 17, cannot be manually cleaned without significant effort and dismantling of parts. If a subsequent build job is carried out with the same raw powder 9, cleaning may not be necessary in some cases. However, even in that case, a cleaning mode may be sensible, for example, to remove agglomerates or sintering residues of the first raw powder 9. If at least another second raw powder 23 for the subsequent build job is used in the same raw powder guide, it may be necessary to clean the sections of the raw powder guide of the installation that have been contaminated by the first raw powder 9 before the second build job.

[0042] According to the invention, this cleaning of the contaminated sections of the raw powder guide of the installation is performed in an automatic cleaning mode of operation, shown in FIG. 4, in order to avoid laborious manual thorough cleaning, including part dismantling. For this purpose, the refill container 7 is filled with a predetermined cleaning amount of second raw powder 23 and the installation 1 is operated in a dummy build job "without power" or "0 watt build job". This means that said cleaning amount of second raw powder 23 is transported through the installation 1 as in a normal build job, but the laser light output coupling device 29 is not operated and the bottom plate 28 is not lowered. In particular, the cleaning mode of operation is performed in an environmentally closed raw powder guide under an inert atmosphere, as in a normal build job.

[0043] Without the laser melting step, the individual layers can be laid down relatively quickly one after the other by the coater 13. However, since the bottom plate 28 does not lower between the laying of the layers, after each laying the entire laid down layer is again sent to the collection container 17. That is to say, the passage of the second raw powder 23 of the cleaning amount through the raw powder guides of the installation 1 can be much quicker in the cleaning operating mode than for a normal build job.

[0044] In particular, the cleaning quantity of the second raw powder 23 passes through the section of the raw powder guide of the facility 1 to be cleaned several times. During the passage of the cleaning quantity of the second raw powder 23, the contaminants of the raw powder guide of the facility 1 are also carried away together with the first raw powder 9. Thus, a certain residual portion of the first raw powder 9 in the second raw powder 23 accumulates in the collection container 17, thereby forming a raw powder mixture 9, 23. After a certain flow rate of the second raw powder 23, which is determined by the cleaning quantity used and the number of passes through the raw powder guide of the facility 1, the residual portion of the first raw powder 9 in the raw powder mixture 9, 23 in the collection container 17 becomes stable. The cleaning movement in the cleaning mode of operation can then be ended and the raw powder guide of the facility 1 can be emptied into the collection container 17, as shown in FIG. 5.

[0045] In that case, the collection vessel 17 contains the raw powder mixture 9, 23 consisting of the second raw powder 23 with residuals of the raw powder 9. The installation 1 is mostly contaminated by the second raw powder 23 and only slightly with residuals of contamination by the first raw powder 9. This residual can be detected in a separate laboratory or in an analysis unit (not shown) integrated in the installation 1 in order to determine whether the residual contamination by the residuals of the first raw powder 9 is acceptable. The collection vessel 17 containing the raw powder mixture 9, 23 consisting of the second raw powder 23 and residuals of the first raw powder 9 can be discarded and a new collection vessel 17' can be used. The raw powder guide of the installation 1 is in particular also transported as empty as possible at the end of the cleaning operating mode. Optionally, after the cleaning operating mode, the process chamber 3 can be cleaned manually or by automatic suction. For safety reasons, the cleaning operating mode can be configured such that it can only be operated under a protective atmosphere when the raw powder guide is closed, in particular when the door of the process chamber is closed, or such that opening of the raw powder guide, in particular opening of the door of the process chamber, is not possible during the cleaning operating mode.

[0046] Figure 6 shows the start of a second build job for producing a second workpiece 33 (see Figure 7) from the second raw powder 23 already used in the cleaning operating mode of Figure 4. Here, contamination with residuals of the first raw powder 9 is below acceptable limits. Figure 7 shows the result near the end of the second build job.

[0047] In FIG. 8 an allocation matrix 35 is exemplarily shown which can be stored and / or called up in the installation 1 or on an external server or cloud. In the illustrated exemplary embodiment, the allocation matrix 35 has six raw material groups, each of which can be used as the first raw material powder 9 or the second raw material powder 23. A residual compatibility of 100% means that no cleaning is required between build jobs. A residual compatibility of 0 means that the use of a cleaning operating mode is not allowed, since sufficient cleaning is only possible by removing individual parts of the installation 1 and cleaning them thoroughly manually. The allocation matrix 35 is preferably, but not necessarily, symmetrical. Instead of raw material groups, the allocation matrix 35 may also contain precisely defined raw material powders. For example, the groups are the following raw materials: AlSi 10 These may include the Al group of aluminum-based raw material powders Mg, AlSi7Mg0.6 and AlSi9Cu3; the Ti group of titanium-based raw material powders Ti6Al4V ELI (grade 23), TA15, Ti (grade 2); the Cu group of copper-based raw material powders CuNi2SiCr, CuSn10, CuCr1Zr; the Fe group of iron-based raw material powders 316L (1.4404), 15-5PH (1.4545), 17-4PH (1.4542), 1.2709, H13 (1.2344); the Ni group of nickel-based raw material powders HX, IN625, IN718, IN939; and the Co group of cobalt-based raw material powders CoCR28Mo6, SLM (registered trademark) MediDent. [Explanation of symbols]

[0048] 1 equipment 3. Process chamber 5, 5' workpiece space 7 Refill container 9. First raw powder 11 Intermediate storage tank 13 Coating 15 Powder bed 17, 17' Collection container 19 Recycling System 21 Filter and Processing Elements 23 Second raw powder 25 First workpiece 27, 27' Workpiece container 28, 28' floorboards 29 Laser light output coupling device 31 Laser Beam 33 Second workpiece 35 Allocation Matrix

Claims

1. Selectively In a first build job using a productive layer build method, at least one first workpiece (25) is produced from at least one first raw material powder (9), and In a second build job using the productive layer build method, at least one second workpiece (33) is produced from at least one second raw material powder (23). An installation (1) for producing The installation (1) having at least one raw powder guide for guiding the first raw powder and / or the second raw powder (9, 23) during the build job, The installation (1) has a cleaning mode of operation, in which a predetermined cleaning amount of second raw powder (23) passes through at least one section of the raw powder guide between the first build job and the second build job, and a raw powder mixture (9, 23) comprising a residual portion of the first raw powder (9) is discharged from the section of the raw powder guide.

2. 2. The installation (1) according to claim 1, wherein the section of the raw powder guide passes through a process chamber (3), and in the cleaning mode of operation the cleaning amount of the second raw powder (23) is supplied to the process chamber (3) layer by layer as a powder bed (15), and the raw powder mixture (9, 23) is discharged from the process chamber (3) without selectively melting the powder bed (15) in the cleaning mode of operation.

3. 3. The installation (1) according to claim 1 or 2, wherein the installation (1) is configured to hold a bottom plate (28, 28') of a workpiece space (5, 5') in a defined position in the cleaning mode of operation.

4. 10. The installation (1) according to any one of the preceding claims, wherein the cleaning amount of the second raw powder (23) is an absolute minimum cleaning amount defined for the installation (1).

5. 10. The installation (1) according to any one of the preceding claims, wherein an upper limit for the residual fraction of the first raw powder (9) in the raw powder mixture (9, 23) discharged from the section of the raw powder guide in the cleaning operating mode is predefined.

6. 10. The installation (1) according to any one of the preceding claims, wherein the installation (1) is configured to re-supply the raw powder mixture (9, 23) discharged from the section of the raw powder guide into the section of the raw powder guide once or several times in the cleaning operating mode.

7. 10. The installation (1) according to any one of the preceding claims, further comprising an analysis unit, the analysis unit being configured to detect residual amounts of the first raw powder (9) in the raw powder mixture (9, 23) discharged from the section of the raw powder guide in the cleaning operation mode.

8. 10. The installation (1) according to any one of the preceding claims, wherein in the cleaning operation mode the installation is configured to re-feed the raw powder mixture (9, 23) discharged from the section of the raw powder guide back to the section of the raw powder guide multiple times or until a residual amount of the first raw powder (9) in the raw powder mixture (9, 23) discharged from the section in the cleaning operation mode falls below a predetermined upper limit.

9. 10. The apparatus (1) according to any one of the preceding claims, wherein the apparatus (1) is configured to increase the cleaning amount of the second raw powder (23) if a residual amount of the first raw powder (9) in the raw powder mixture (9, 23) discharged from the section of the raw powder guide in the cleaning operation mode exceeds a predetermined upper limit.

10. 10. The installation (1) according to any one of the preceding claims, wherein the installation is operable with different raw materials (9, 23) preselected as a first raw material powder and a second raw material powder (9, 23), respectively, and a measure of residual compatibility between each two of the different raw materials as the first raw material powder and / or the second raw material powder (9, 23) is stored in and / or can be recalled from a predefined assignment matrix (35).

11. Selectively At least one first workpiece (25) from at least one first raw material powder (9) in a first build job; and At least one second workpiece (33) is produced from at least one second raw material powder (23) in a second build job. A method for constructing a generation layer using an equipment (1) for producing A method for building a production layer, characterized in that the equipment (1) is cleaned between the first building job and the second building job in a cleaning operating mode by passing a predetermined cleaning amount of second raw powder (23) through at least one section of a raw powder guide of the equipment (1) and discharging a raw powder mixture (9, 23) containing residual portions of the first raw powder (9) from said section of the raw powder guide.

12. 12. The method according to claim 11, wherein the section of the raw powder guide passes through a process chamber (3), and in the raw operation mode, the cleaning amount of second raw powder (23) is supplied to the process chamber (3) layer by layer as a powder bed (15), and in the cleaning operation mode, the raw powder mixture (9, 23) is discharged from the process chamber (3) without selectively melting the powder bed (15).

13. 13. The method according to claim 11 or 12, wherein in the cleaning operating mode the bottom plate (28, 28') of the workpiece space (5, 5') is held in a defined position.

14. The method according to any one of claims 11 to 13, wherein the cleaning amount of the second raw powder (23) is an absolute minimum cleaning amount defined for the installation (1).

15. The method according to any one of claims 11 to 14, wherein an upper limit for the residual fraction of the first raw powder (9) in the raw powder mixture (9, 23) discharged in the cleaning mode of operation is predefined.

16. 16. The method according to any one of claims 11 to 15, wherein in the cleaning operating mode the raw powder mixture (9, 23) discharged from the section of the raw powder guide is re-fed to the section of the raw powder guide once or several times.

17. The method according to any one of claims 11 to 16, wherein the residual amount of the first raw powder (9) in the raw powder mixture (9, 23) discharged in the cleaning mode of operation is detected.

18. 18. The method according to any one of claims 11 to 17, wherein in the cleaning operation mode the raw powder mixture (9, 23) discharged from the section of the raw powder guide is re-fed to the section of the raw powder guide multiple times or until a residual amount of the first raw powder (9) in the raw powder mixture (9, 23) discharged in the cleaning operation mode falls below a predetermined upper limit.

19. 19. The method according to any one of claims 11 to 18, wherein the cleaning amount of the second raw powder (23) is increased if the residual fraction of the first raw powder (9) in the raw powder mixture (9, 23) discharged in the cleaning operation mode exceeds a predetermined upper limit.

20. 20. The method according to any one of claims 11 to 19, wherein the measure of residue compatibility between each two of the different raw materials as first and / or second raw material powders (9, 23) is called up from a predefined and stored assignment matrix (35).

21. A control program for an installation (1) according to any one of claims 1 to 10 for carrying out the method according to any one of claims 11 to 20.

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