Methods for constructing layers using various raw material powders and the equipment for doing so

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 using 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 to carry out the method. [Background technology]

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

[0003] Equipment for producing workpieces using a layer-by-layer build process is often not limited to operating with only one type of raw material powder. Some multi-material equipment can produce workpieces from two or more different raw material powders, but the different raw material powders are guided separately through the equipment (see, for example, WO 2014 / 111072). Regardless of whether it is a single-material or multi-material equipment, different types of raw material powder can be used for different build jobs. However, to allow a new build job to use a different raw material powder in the same raw material powder guide of the equipment from the previous build job, the corresponding raw material powder guide of the equipment must be thoroughly cleaned to prevent an unacceptably high percentage of the previous raw material powder remaining in the new workpiece. To ensure high material quality of the workpieces, the corresponding contamination limits for some raw material powders may be very strict.

[0004] However, thoroughly cleaning equipment often requires significant manual labor, with many components 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 personnel. In addition to the corresponding cleaning costs, there are additional shutdown costs for the time the equipment is out of operation. [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 object 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 a production layer build method, at least one first workpiece from at least one first raw material powder; and and forming at least one second workpiece from at least one second raw material powder in a second build job using the layer-by-layer build method. A facility for manufacturing 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 has a cleaning mode of operation, in which a predetermined cleaning amount of second raw material powder passes through at least one section of the raw material powder guide between a first build job and a second build job, and a raw material powder mixture containing a residue of the first raw material powder is discharged from the section of the raw material powder guide.

[0009] The raw powder guide includes all components 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 cleaning amount of the second raw powder passes in the cleaning mode of operation can extend over the entire raw powder guide, only a portion thereof, or several portions thereof. The raw powder guide can optionally include a recycling system, whereby at least a portion of the raw powder is circulated through the raw powder guide. The section of the raw powder guide through which the cleaning amount of the second raw powder passes in the cleaning mode of operation particularly extends over the recycling system. A multi-material equipment can have multiple raw powder guides that are widely spaced apart from each other. In this case, the cleaning mode of operation can be individually provided for at least one section of one, several, or all raw powder guides. In particular, sections of the raw powder guide that fluidly transport raw powder along the piping by positive or negative pressure are difficult or impossible to clean manually without first disassembling and subsequently reassembling the raw powder guide components. Therefore, the cleaning mode of operation is particularly advantageous for such sections of the raw powder guide.

[0010] In particular, the section of the raw material powder guide to be cleaned in the cleaning operating mode passes through a process chamber in which raw material powder is selectively melted layer by layer as a powder bed during a build job. Optionally, in the cleaning operating mode, a second cleaning amount of raw material powder is supplied layer by layer as a powder bed to the process chamber, and the raw material powder mixture is discharged from the process chamber. However, unlike a 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 perform the cleaning operating mode according to the invention simply by regenerating or executing a software update, without having to adapt or modify the equipment's hardware.

[0011] That is, in the cleaning mode of operation, the second feedstock powder is transported through the equipment exactly as it is during a build job, except that the laser is not operated to selectively melt the powder bed. Therefore, the cleaning mode of operation can be referred to as a "no-power" dummy build job, or a "0-watt build job." The second feedstock powder in the cleaning volume cleans at least the section of the feedstock powder guide to be cleaned in the cleaning mode of operation by carrying away any remaining first feedstock powder and mixing it into the cleaning volume. Any remaining first feedstock powder present in the section of the feedstock powder guide to be cleaned in the cleaning mode of operation is thereby discharged together with the second feedstock powder as a feedstock powder mixture. That is, the cleaning mode of operation automates cleaning between two build jobs using different feedstock powders, thereby significantly reducing cleaning time and costs. Particularly in relatively large equipment and / or equipment with automatic feedstock powder recycling, i.e., a circulating feedstock powder guide, the advantages of the cleaning mode of operation compared to manual cleaning can be significant.

[0012] It is also conceivable that the section of the raw powder guide to be cleaned passes through the process chamber, but no powder bed is built in the cleaning operation mode. Unlike the build job, in the cleaning operation mode, the cleaning amount of second raw powder can be dropped and / or transferred directly into an overflow or collection container. For this purpose, the coater laying the powder bed in the build job can be controlled accordingly so that it is transported directly to the overflow or collection container in the cleaning operation mode. In some installations, an overflow or collection container is located on one or both sides of the powder bed, directly below an 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 cleaning amount of second raw powder 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 to be flushed as well, or moved away from the raw powder guide to prevent flushing. Alternatively or additionally, it is conceivable that in the cleaning mode of operation the cleaning amount of second raw material powder is transferred directly to a workpiece container positioned below the process chamber, for example if a base 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 material powder is transferred as an upward 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 feedstock powder guide that are difficult or impossible to clean manually without first disassembling and then reassembling the equipment. These are, for example, the piping that transports the feedstock powder. That is, depending on the structure and accessibility of the process chamber, it may be relatively easy to manually clean the process chamber, possibly including the intermediate reservoir, coater, and overflow, without removing any parts. Therefore, in the cleaning mode of operation, it is not necessary to pass the cleaning amount of second feedstock powder through the process chamber. For example, a cleaning bypass can be provided to pass the cleaning amount of second feedstock powder by the process chamber, thus shortening the duration of the cleaning cycle.

[0014] It may happen that the second raw material powder in the cleaning volume is contaminated with residuals from the first raw material powder to the extent that the raw material powder mixture discharged after passing through must be discarded and cannot be reused. However, because the cost of many raw material powders has dropped significantly in recent years, the cost of the second raw material powder in the cleaning volume is now much lower than the cleaning costs and shutdown costs. Furthermore, in addition to the cleaning mode, to minimize the amount of residual first raw material powder, a quick, manual, rough cleaning of all easily accessible equipment parts, especially the process chamber, can be performed in advance without removing any parts. This can be done in just a few minutes by employees with little expertise or experience, for example, by suction. If the contaminants in the raw material powder mixture discharged from the raw material powder guide section are below the acceptable limit, the raw material powder mixture can even be used for a second build job or other purposes.

[0015] Optionally, the equipment can be configured to hold the bottom plate of the workpiece space at a specified position in the cleaning mode. Unlike a build job, the workpiece space does not expand downward in the cleaning mode. The specified position can be the top-most zero position, in which the workpiece space remains virtually closed and no powder bed forms on the bottom plate. In this case, the cleaning amount of second raw material powder is transported directly to an overflow or collection container. If the specified position is, for example, lower than one layer thickness, a powder bed is formed, but the additional layer applied to the powder bed after the first layer is almost completely removed from the powder bed in the cleaning mode and discharged from the process chamber. Because the raw material powder is not selectively melted between layer placements in the cleaning mode, the period between layer placements in the cleaning mode is much shorter than in a build job. Layer placement and layer removal can be performed seamlessly one after the other, which accelerates the cleaning mode. In the cleaning mode, the cleaning operation can be further accelerated if the powder bed is not placed on the bottom plate but is directly transferred to an overflow or collection container. If the specified 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, direct transfer to the workpiece space can be performed in the cleaning mode, 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 material powder can be up to 30%, preferably up to 10%, of the amount of second raw material powder required for the second build job. This cleaning amount can depend on the equipment and the first and / or second raw material powder. In this case, an empirical value can be specified that indicates a cleaning amount sufficient to ensure that the residual amount of first raw material powder in the raw material powder mixture is below an acceptable level, depending on the equipment and the first and / or second raw material powder. Optionally, the cleaning amount of the second raw material powder can be an absolute minimum cleaning amount defined for the equipment, for example 5 liters.

[0017] Optionally, an upper limit for the residual content of the first raw material powder in the raw material powder mixture discharged from the section of the raw material powder guide in the cleaning operation mode can be predetermined. This can even be a zero tolerance, i.e., the upper limit can only be achieved by thorough manual cleaning, making the cleaning operation mode impossible for certain combinations of first and second raw material powders. The higher the contamination tolerance, the better the cleaning operation mode can be applied with the smallest possible cleaning volume and shortest possible transit time. The smaller the contamination tolerance, the longer the cleaning operation mode can be run and / or the larger the cleaning volume can be selected.

[0018] Optionally, the equipment can be configured to re-feed the raw powder mixture discharged from the section of the raw powder guide in the cleaning mode back into the section of the raw powder guide once or several times, for example, by a recycling system or manually. This increases the duration of the cleaning mode but allows for better utilization of the cleaning volume. Since only a small portion of the cleaning volume is actively cleaning, i.e., carrying away the first raw powder, during each pass, the amount of first raw powder remaining in the section of the raw powder guide can be significantly reduced. It is also possible to clean the raw powder mixture between passes. Such intermediate cleaning is particularly useful when the first and second raw powders, for example, have significantly different particle sizes and can be easily and reliably separated by sieves or filters, or when, for example, one of the raw powders exhibits higher ferromagnetic properties than the other and can be easily and reliably separated by magnetic separation.

[0019] Optionally, the equipment may further comprise an analysis unit configured to detect the residual amount of the first raw material powder in the raw material powder mixture discharged from the section of the raw material powder guide in the cleaning operation mode, which is useful for detecting or measuring the cleaning effect. The analysis unit can be used to check whether the equipment has been sufficiently cleaned.

[0020] Optionally, the installation can be configured 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 predetermined upper limit. This can be checked, for example, using an analytical unit once, periodically, or continuously during the cleaning mode of operation, 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 material powder if the residual amount of the first raw material powder in the raw material powder mixture discharged from the section of the raw material powder guide exceeds a predetermined upper limit in the cleaning operation mode. To reduce the consumption of the cleaning amount of the second raw material powder, it may be advantageous to first use a relatively small cleaning amount for the cleaning operation mode and determine the residual amount of the first raw material powder in the raw material powder mixture discharged from the section of the raw material powder guide to check the success of the cleaning. If the cleaning amount is insufficient, the upper limit has been exceeded and the cleaning amount can be increased. However, rather than first increasing the cleaning amount, it is preferable to increase the number of times the cleaning amount passes through the section of the raw material powder guide of the equipment to be cleaned.

[0022] Optionally, the system can be operated using preselected different raw materials as the first and / or second raw material powders, respectively, and a measure (degree Maβ) of the residue compatibility between each of the different raw materials as the first and / or second raw material powders can be stored and / or accessed in a predefined allocation matrix. Empirical values, standardized tolerances, upper limits, and / or restrictions 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 exhibit similar or identical behavior with respect to residue compatibility, so that the residue compatibility applies to the entire group of 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 particle size, allocation of particle size groups to each other, and corresponding residue compatibility. The allocation matrix may be stored on the equipment itself and / or stored externally, for example on an external server or cloud, and may be retrieved by the equipment via a data connection.

[0023] The residue compatibility as an entry in 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 a first raw material powder in the raw material powder mixture discharged from the section of the raw material powder guide in the cleaning mode of operation. This can be, for example, a volume fraction, a weight fraction, or a quantity fraction. The residue compatibility between two raw materials can also be zero, meaning that when a specific second raw material follows a specific different first raw material, the cleaning mode of operation may not be sufficient for cleaning. If the residue compatibility is very low or zero, thorough manual cleaning may be 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 - at least one second workpiece from at least one second feedstock powder in a second build job; In a method for constructing a generation layer using equipment for manufacturing A production layer building method is provided, characterized in that the equipment is cleaned between a first build job and a second build job by passing a predetermined cleaning amount of second raw material powder through at least one section of the equipment's raw material powder guide in a cleaning operating mode, and discharging a raw material powder mixture containing residual amounts 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 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 cleaning volume of the second raw material powder can be set to an absolute minimum cleaning volume defined for the facility, for example 5 liters.

[0029] Optionally, an upper limit for the residual content of the first raw material powder in the raw material powder mixture discharged in the cleaning mode of operation can be predetermined.

[0030] Optionally, in a cleaning mode of operation, the raw powder mixture discharged from the section of the raw powder guide can be re-fed to 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 can be detected.

[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, 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, the cleaning amount of the second raw material powder can be increased.

[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, there is provided a control program for the aforementioned equipment for carrying out the aforementioned method. The control program may be installable and / or executable in the equipment as software and / or hardware. The control program includes control instructions, particularly for a cleaning operation mode. The control program may be designed as an update and / or an add-on module to an existing control program of the equipment. An already existing equipment can be modified to have the cleaning operation mode according to the present invention disclosed herein simply by installing and / or running the control program as an update and / or add-on module, without modifying the equipment hardware.

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

[0037] [Figure 1] FIG. 1 is a schematic diagram of an exemplary embodiment of an installation disclosed herein at the start of a first build job. [Figure 2] FIG. 1 is a schematic diagram of an exemplary embodiment of an installation disclosed herein at the end of a first build job. [Figure 3] FIG. 1 is a schematic diagram of an exemplary embodiment of an installation disclosed herein after a first build job. [Figure 4] FIG. 1 is a schematic diagram of an exemplary embodiment of the equipment disclosed herein in a cleaning mode of operation before a second build job. [Figure 5] FIG. 1 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 installation disclosed herein at the start of a second build job. [Figure 7] FIG. 1 is a schematic diagram of an exemplary embodiment of an installation 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 INVENTION

[0038] 1 to 7 show an installation 1 for manufacturing three-dimensional workpieces 25, 33 using a layer-by-layer build method in the form of selective laser melting (laser powder bed fusion (LPBF)). The installation 1 includes a raw powder guide, shown here very simply, passing through the process chamber 3. The installation 1 also includes a workpiece space 5, 5' arranged below the process chamber 3. Furthermore, the installation 1 includes a refill container 7 for fresh and / or processed, i.e., recycled, raw powder 9, which feeds an intermediate storage 11. A horizontally movable coater 13 allows a powder bed 15 of raw powder 9 to be deposited above 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 transfers excess raw powder 9 from the process chamber 3 to a collection container 17. The raw powder 9 is transported downwards primarily 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 equipment 1 here optionally includes a recycling system 19, and the raw powder 9 that ultimately enters the collection container 17 is fed back to the replenishment container 7 via a filter and treatment element 21. The recycling system 19 can include 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 equipment 1; the collection container 17 can be manually removed and emptied, and the raw powder 9 contained therein can be treated with external filter and treatment equipment to fill a new replenishment container 7. For this purpose, the replenishment container 7 is connected so that it can be manually replaced. The advantages of the equipment 1 disclosed herein are more pronounced in relatively large equipment 1 incorporating a recycling system 19, but the effects of the present invention can also be obtained in small equipment 1 not incorporating a recycling system 19.

[0040] According to the present invention, the equipment 1 can operate with at least two different raw material powders 9, 23: a first raw material powder 9 shown in FIGS. 1-3 and a second raw material powder 23 shown in FIGS. 4-7. FIG. 1 shows the equipment 1 at the start of a first build job for producing a first workpiece 25 (see FIGS. 2 and 3) from the first raw material powder 9. The workpiece space 5 is formed by a portable workpiece container 27 that is positioned below 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 positioned in its uppermost position at the start of the first build job, such that 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 material powder 9 is then deposited on the bottom plate 29 by the coater 13. A laser beam 31 is then directed over the powder bed 15 using a laser light output coupling device 29 on the ceiling side of the process chamber 3 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 moves down one layer thickness into the workpiece container 27, and a new layer is deposited by the coater 13, which then selectively melts again using 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. To be able to produce straight layers for the powder bed 15, the coater 13 always deposits excess feedstock 9, which is then smoothed out 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, when the first workpiece 25 has just been completed. After the first build job, it is already recognized that the equipment's raw powder guide is contaminated with the first raw powder 9, specifically throughout all parts of the equipment 1 that have come into 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 as being positioned under the process chamber 3 to begin the new build job. The workpiece container 27 with the first workpiece 25 is transferred to an unloading station (not shown here) for unloading. FIG. 3 also shows that the equipment 1 still has many parts of the raw powder guide that are contaminated with the first raw powder 9. The process chamber 3, which is normally accessible through a service opening (not shown), can be manually suctioned and / or cleaned relatively easily and quickly. Optionally, the process chamber 3 can also be pre-cleaned, post-cleaned, or intermediately cleaned by automatic suction. Furthermore, it is useful to transport the raw powder guide of the equipment 1 as empty as possible after the first build job in order to remove as much of the first raw powder 9 as possible. However, certain sections of the equipment's raw powder guide, 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 component removal. If a subsequent build job is performed using the same raw powder 9, cleaning may not be necessary. However, even in this case, a cleaning mode may be useful, for example, to remove agglomerates of the first raw powder 9 or sintering residues. If at least a different second raw powder 23 for the subsequent build job is used in the same raw powder guide, sections of the equipment's raw powder guide that were contaminated by the first raw powder 9 may need to be cleaned before the second build job.

[0042] According to the present invention, this cleaning of the contaminated section of the equipment's feedstock powder guide is performed in an automatic cleaning mode of operation, as shown in FIG. 4, to avoid laborious manual thorough cleaning, including part removal. For this purpose, the refill container 7 is filled with a predetermined cleaning amount of second feedstock powder 23, and the equipment 1 is operated in a "no-power" dummy build job or "0-watt build job." This means that the cleaning amount of second feedstock powder 23 is transported through the equipment 1 as in a normal build job, but the laser light output coupling device 29 is not activated and the bottom plate 28 is not lowered. In particular, the cleaning mode of operation is performed in an environmentally closed feedstock powder guide under an inert atmosphere, just like 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 layer layings, after each laying the entire laid layer is sent back to the collection container 17. That is, the passage of the cleaning amount of second raw powder 23 through the raw powder guide of the installation 1 can be much quicker in the cleaning mode of operation than in a normal build job.

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

[0045] In this case, the collection container 17 contains the raw powder mixture 9, 23 consisting of the second raw powder 23 containing residues of the raw powder 9. The installation 1 is largely contaminated by the second raw powder 23, with only a small residue of contamination from the first raw powder 9. This residue can be detected in a separate laboratory or in an analysis unit (not shown) integrated into the installation 1 to determine whether the residual contamination from the residues of the first raw powder 9 is acceptable. The collection container 17 containing the raw powder mixture 9, 23 consisting of the second raw powder 23 and residues of the first raw powder 9 can be discarded and a new collection container 17' can be used. The raw powder guide of the installation 1 is transported, in particular, as empty as possible even 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 material powder guide is closed, in particular when the process chamber door is closed, or opening of the raw material powder guide, in particular opening of the process chamber door, is not possible during the cleaning operating mode.

[0046] Figure 6 shows the start of a second build job to produce a second workpiece 33 (see Figure 7) from the second feedstock powder 23 already used in the cleaning operating mode of Figure 4. Here, contamination with residuals of the first feedstock powder 9 is below acceptable limits. Figure 7 shows the results 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 retrieved from the equipment 1 or 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 cleaning mode of operation is not permitted, since sufficient cleaning is only possible by removing individual parts of the equipment 1 and thoroughly cleaning them 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 could be the following raw materials: AlSi 10 These may include the Al group of aluminum-based raw material powders such as Mg, AlSi7Mg0.6, and AlSi9Cu3; the Ti group of titanium-based raw material powders such as Ti6Al4V ELI (Grade 23), TA15, and Ti (Grade 2); the Cu group of copper-based raw material powders such as CuNi2SiCr, CuSn10, and CuCr1Zr; the Fe group of iron-based raw material powders such as 316L (1.4404), 15-5PH (1.4545), 17-4PH (1.4542), 1.2709, and H13 (1.2344); the Ni group of nickel-based raw material powders such as HX, IN625, IN718, and IN939; and the Co group of cobalt-based raw material powders such as CoCR28Mo6 and SLM (registered trademark) MediDent. [Explanation of symbols]

[0048] 1 equipment 3. Process chamber 5,5' workpiece spacing 7 Refill container 9. First raw powder 11 Intermediate storage tank 13 Coater 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 production 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 a 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) has 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) containing 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 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 the bottom plate (28, 28') of the workpiece space (5, 5') in a defined position in the cleaning mode of operation.

4. 2. The installation (1) according to claim 1, wherein the cleaning amount of the second raw powder (23) is an absolute minimum cleaning amount defined for the installation (1).

5. 2. The apparatus (1) according to claim 1, wherein an upper limit for the 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 is predetermined.

6. The installation (1) according to claim 1, 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. 2. The installation (1) according to claim 1, further comprising an analysis unit, the analysis unit being configured to detect the residual content 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. 2. The installation (1) according to claim 1, wherein in the cleaning mode of operation the installation is configured to re-feed the raw powder mixture (9, 23) discharged from the section of the raw powder guide 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 mode of operation falls below a predetermined upper limit.

9. 2. The apparatus (1) according to claim 1, wherein the apparatus (1) is configured to increase the cleaning amount of the second raw powder (23) if the 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. 2. The installation (1) according to claim 1, wherein the installation is operable with different raw materials (9, 23) preselected as the first raw material powder and the second raw material powder (9, 23), respectively, and wherein 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 (9, 23) is stored in and / or can be called up in 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) 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 material powder (23) through at least one section of the raw material powder guide of the equipment (1) and discharging a raw material powder mixture (9, 23) containing a residual portion of the first raw material powder (9) from said section of the raw material 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. A 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. 12. The method according to claim 11, wherein the cleaning amount of the second raw powder (23) is the absolute minimum cleaning amount defined for the installation (1).

15. 12. The method according to claim 11, wherein an upper limit for the residual content of the first raw powder (9) in the raw powder mixture (9, 23) discharged in the cleaning mode of operation is predetermined.

16. 12. The method according to claim 11, 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. 12. The method according to claim 11, wherein the residual content of the first raw powder (9) in the raw powder mixture (9, 23) discharged in the cleaning mode of operation is detected.

18. 12. The method according to claim 11, wherein in the cleaning mode of operation, 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 mode of operation falls below a predetermined upper limit.

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

20. 12. The method according to claim 11, 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 retrieved from a predefined and stored assignment matrix (35).

21. A control program for the equipment (1) described in claim 1 for carrying out the method described in claim 11.

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