Method and system for controlling manufacturing process of additively manufacturing components

Abstract

The invention relates to a method for controlling a manufacturing process for additive manufacturing of a component (2) in a device (1), in which a construction material (13) is cured on a construction zone (8) in a process chamber (3) by irradiating the construction material (13) with at least one energy beam (22), the process gas (G) laden with impurities (A) is discharged from the process chamber (3) via a gas line (9), filtered and returned back into the process chamber (3), comprising the following steps: detecting a number of measured values (M) by means of a contamination measuring unit (18), wherein each measurement value (M) permits an inference of a degree of impurity of the process gas (G) flowing through the gas line (9) that is present during the detection,-evaluating the number of measurement values (M),-controlling the device (1) and / or an output device (39), which is connected to the manufacturing process in terms of data technology, as a function of the evaluation of the number of measurement values (M). The invention also relates to a corresponding system and to a manufacturing installation.

Description

Technical Field

[0001] The invention relates to a method and a system for controlling a manufacturing process for an additively manufactured component in a device, wherein, on a building zone, a building material is built up layer by layer, in particular between two material layers to which the building material is applied, by irradiating the building material with at least one energy beam and thereby in particular selectively solidifying the building material. Background Art

[0002] Additive manufacturing processes are becoming increasingly important in prototype production and now also in series production. In general, an "additive manufacturing process" is understood to be a manufacturing process in which a manufactured product ("component") is constructed by depositing material ("building material"), usually based on digital 3D structural data. The construction is usually, but not necessarily, layer by layer. As a synonym for additive manufacturing, the term "3D printing" is also often used, and the production of models, samples and prototypes using additive manufacturing processes is often referred to as "rapid prototyping", the production of tools as "rapid tooling", and the flexible production of series production components as "rapid manufacturing". As mentioned at the beginning, a key point is the selective solidification of the building material, wherein in many manufacturing processes this solidification is carried out by irradiation with radiation energy, for example electromagnetic radiation, in particular light and / or heat radiation, but if necessary, also by means of particle radiation, such as electron radiation. Examples of methods that work with irradiation are "selective laser sintering" or "selective laser melting". In this case, thin layers of a mostly powdered construction material are repeatedly applied one on top of the other, and in each layer, the construction material is selectively solidified by spatially limited irradiation of locations that are to belong to the component to be produced after production in a "welding process" by partially or completely melting the powder particles of the construction material at this location with the energy introduced locally by radiation. During the cooling process, these powder particles then solidify with each other to form a solid body. In most cases, the energy beam is guided through the construction zone along a solidification path, and the remelting or solidification of the material in the respective layer takes place in the form of "weld paths" or "weld strips", so that a large number of such layers formed by weld paths are ultimately present in the component. In this way, components of very high quality and breaking strength can now be produced.

[0003] The manufacturing process usually takes place in a protective gas atmosphere. For this purpose, a process gas (e.g. argon) flows through the process chamber. Usually, the process gas is not then released into the environment, but is fed back into the process chamber. In particular in additive manufacturing with metallic construction materials, the process gas in this gas circuit is contaminated with particles. These can be particles of the construction material or particles generated during the solidification process. In addition, additional particles can be introduced into the process gas flow, for example passivators, such as lime, which can be added to the process gas flowing out of the process chamber for fire protection reasons in the case of metallic construction materials.

[0004] In order to clean the process gas, it is usually filtered. However, it can still happen that the process gas introduced into or returned to the process chamber is contaminated with particles, for example due to filter ruptures, which leads to a reduction in the quality of the manufactured component. In general, permeability at the filter stage can lead to major problems in the quality of the manufactured component and can also lead to machine damage, especially because it can remain undetected for a long time.

[0005] In order to reduce the risk of contamination due to filter ruptures, the process gas is filtered, for example, through a two-stage filter system. A filter rupture at the main filter (or prefilter) can be compensated for and detected indirectly by means of a downstream fine filter (usually a non-purgable storage filter), because once it ruptures, it will block relatively quickly, resulting in an increase in the pressure difference at the filter, which can be detected by a differential pressure sensor or can thus actuate a pressure switch, which in turn leads to a production interruption. In trouble-free operation, the first filter stage allows a small fraction of particles to pass. For example, the fine filter reduces this fraction to a minimum value of the fine fraction (condensate), which reaches the clean gas side of the process gas circuit.

[0006] In another frequently used filter unit, the filtrate is first mixed with lime powder immediately upstream of the filter, wherein a downstream fine filter or storage filter is omitted. The problem that arises from this is that, even if the filter is permeable, lime can also pass unnoticed into the clean gas side of the process gas circuit and be introduced into the process chamber during the ongoing construction process. The lime can settle as dust on the powder bed or on the solidified areas and be integrated into the structure of the component. As a result, the component properties, such as its strength, can be impaired. Summary of the invention

[0007] The object of the present invention is to provide a method and a system for controlling a manufacturing process of an additively manufactured component, which overcome the disadvantages of the prior art and in particular enable automatic detection of filter ruptures.

[0008] This object is achieved by a method according to claim 1 , a system according to claim 10 and a device according to claim 13 .

[0009] The method according to the invention is used to control a manufacturing process of an additively manufactured component in a device, wherein, at a building zone, a building material is solidified in a process chamber by irradiating the building material with at least one energy beam, and wherein a process gas laden with impurities is conducted out of the process chamber via a gas line, filtered and fed back into the process chamber. The method comprises the following steps:

[0010] - detecting a certain number of measured values ​​by means of the contamination measuring cell, wherein each measured value allows conclusions to be drawn about the degree of impurities of the process gas flowing through the gas line which are present at the time of the detection,

[0011] - evaluate a certain number of measurements,

[0012] - controlling the device and / or an output device connected to the production process in terms of data technology as a function of the evaluation of a certain number of measured values.

[0013] As already mentioned, during the manufacturing process, the construction material is constructed in the construction zone layer by layer, i.e. successively in a plurality of material application planes or material layers. The construction material is preferably a metal powder. However, the invention is not limited thereto and can also be used with other preferably powdered construction materials, such as plastics or ceramics or mixtures of different materials. In this case, in particular between the application of two material layers, the construction material is solidified (in particular selectively) by irradiating the construction material with at least one energy beam (this means an energy beam consisting of photons or particles, such as a light beam or an electron beam) generated by an irradiation unit of the manufacturing device. In this case, not only is the construction material in the topmost newly applied material layer captured by the energy beam and melted or remelted, but the energy beam usually penetrates a certain distance into the material bed and reaches the already remelted material located below from the previously applied material layer.

[0014] "Impurities" are in principle any solid or liquid particles which contaminate the process gas. This includes in particular emission materials or other impurities from the process chamber, but can also include impurities arising downstream of the process chamber, in particular due to added passivating agents. Impurities may be understood, for example, to mean smoke particles or particles of construction material (emission materials) or lime (passivating agent), or mixtures of these particles.

[0015] The degree of impurities refers to the amount of impurities in the process gas. This degree can usually be expressed by the proportion of particles or "impurity elements", but it is also possible to classify the materials that contaminate the process gas by proportion.

[0016] Impurities in the process gas can be caused by a variety of processes. Impurities depend, for example, on the flow rate of the process gas, in particular on blowing in or sucking out, but also on the dosing process (powder can escape from the dosing device due to excessively long rotation of the rollers or due to defects in the powder seal), coater travel (powder that has not yet settled on the powder bed after coating is caught by the gas flow and further swept up), construction processes or laser activity, collisions between the coater and the component (powder sweeping up), malfunctions or structural defects (dust accumulates on the coater and is swept up by blowing in), operating errors (for example, forgetting to install the sealing lip on the dosing device) or also neglected cleaning cycles (dust settles on the surface).

[0017] To detect the measured values, a contamination measuring unit is used, which can be, for example, a dust sensor known from the prior art. The measurement can be carried out in particular optically, for example by turbidity according to the smoke detector principle, acoustically, for example by ultrasound, for example triboelectrically according to the ionization smoke detector principle, electrochemically or electromagnetically, for example by means of a microwave Doppler sensor. Preferably, any existing thermo-optical measuring devices for process monitoring can also be used to obtain characteristic measured values ​​caused by the interaction of the laser beam with the impure process atmosphere or by the changed processes in the molten pool caused by this interaction. It is also preferred to monitor the optical recordings made of the possibly turbid process atmosphere, in particular with regard to its brightness and contrast. Preferred measuring units are minimally invasive, structurally easy to integrate into the system, wear-free, reliable and cost-effective.

[0018] The pollution measuring unit measures the particle load of the process gas flowing through, in particular on the clean gas side of the process gas circuit, i.e. between the filter and the inlet to the process chamber. The measurement can be carried out continuously or intermittently. The sensor of the pollution measuring unit is preferably arranged in the machine so that the sensor can detect almost the entire inner diameter of the pipe in which it is located. If the sensor is arranged in the area of ​​the outlet pipe, the sensor should be arranged where the pipe extends straight as long as possible, in particular when the area is divided into three parts, preferably two thirds of the section downstream of the nearest bend and one third of the section upstream of the nearest bend. During the measurement, the flow in the pipe should be as uniform as possible and proceed freely. Regarding the orientation of the sensor relative to the pipe cross section (360°), the sensor is preferably 90° to the main flow direction and detects the load mass flow As wide a spectrum as possible, i.e. it should be positioned along the largest diameter of the pipe.

[0019] The measured values ​​detected by the contamination measuring unit should enable inferences to be made about the degree of impurities in the process gas flowing through the gas pipeline at the time of detection. This means that each measured value directly indicates the degree of the corresponding impurity, or provides a value with the help of which the degree of impurities can be determined, for example based on powder bed monitoring. Preferred measured values ​​indicate, for example, the total number of particles per unit time, but can also indicate the mass or charge of a single particle, wherein additional measurement of the flow rate may also be helpful here. In addition, it may also be advantageous to measure the uniformity or inhomogeneity of the flow, i.e., whether the flow rate across the inner cross section of the pipe is approximately the same or different. Further preferred measured values ​​indicate the distribution of particles in the flow across the inner cross section of the pipe. For example, after a bend in the wall region of the maximum arc length, the concentration of particles, in particular heavier particles, may be higher due to the influence of centrifugal forces. In short, all measurements that can provide information about how many particles flow back into the process chamber with the process gas are preferred.

[0020] It is emphasized that it is entirely possible to measure only the degree of impurities at the gas outlet of the process chamber (in the raw gas line). Preferably, however, the degree of contamination in the clean gas line (at the gas inlet to the process chamber, or in other words in the process gas after filtration) can be measured. However, it is also very advantageous to measure in the raw gas line and in the clean gas line, since in this way also differential values ​​can be formed, which can give good information about filter changes.

[0021] Preferably, a certain number of measured values ​​are evaluated for the quality of the component. If the impurities of the process gas are too severe, they should be overcome so that these impurities do not cause excessive damage to the process chamber and the components to be manufactured therein. For example, it is possible to simply check whether the degree of impurities in the process gas is higher than a predetermined limit value, in particular the lime content of the particles. However, other indicators are also possible, such as a sudden increase in the degree of impurities, or an increase in the specific concentration of specific particles, such as larger particles or lime particles. For this purpose, the contamination measurement unit can be integrated into a diagnostic system, for example, in which the measured values ​​are also combined with the measured values ​​from another sensor mechanism (for example, in the context of "differential diagnosis"). For example, the measured values ​​can be associated with the control data of the manipulation of all movable elements (coating machines, including individual parts, etc.) in the process chamber and the gas blowing or gas extraction, or the time relationship between the increase of powder emission and the activity of a specific event, or a specific component, can be formed. It is also possible to form a correlation between fault events through other sensor mechanisms, or to weight and interpret the signals, thereby limiting the components or events that cause the fault.

[0022] With regard to the control of the device, or rather the control of the output device, the production process can be interrupted until the level of impurities returns to a tolerable range. However, a warning can also be output, for example, that a filter may be broken. For example, if a threshold value is exceeded, for example, if the total amount of discharged powder is too large, or if a defined limit value of a local maximum / minimum or a curve gradient is exceeded, a warning signal is output. Between control and evaluation, a fault diagnosis can also be performed here, in which it is determined where a fault may be located.

[0023] The system according to the invention is used to control a manufacturing process of an additively manufactured component in a device, wherein, at a building zone, a building material is solidified in a process chamber by irradiating the building material with at least one energy beam, and wherein a process gas loaded with impurities is conducted out of the process chamber via a gas line, filtered and fed back into the process chamber. The system is designed in particular for carrying out the method according to the invention and comprises the following components:

[0024] a contamination measuring unit which is designed to detect a certain number of measured values, wherein each measured value enables a conclusion to be drawn about the degree of a corresponding impurity in the process gas flowing through the gas line,

[0025] an evaluation unit, which is designed to evaluate a certain number of measured values,

[0026] A control unit which is designed to control the device and / or an output device which is connected to the production process in terms of data technology as a function of a certain number of measured values.

[0027] The invention has the advantage that a particle-laden process gas can be detected and, if necessary, the process can be stopped or a warning output can be issued. This can prevent component defects caused by a poorly filtered process atmosphere, which can remain undetected for a long time. Impurities can directly impair the manufacturing process by interfering with the laser beam, and can also lead to powder contamination, which can cause difficult-to-detect damage to the parts produced therefrom even if the powder is subsequently sieved. In particular, the invention can reliably determine the smallest filter rupture that does not lead to a termination of the operation due to other control mechanisms (for example, due to a sudden significant drop in the back pressure that is not related to the purification process). As a result, it is possible to prevent the quality of the components from being impaired during a long period of time when the process gas cleaning system should be operating perfectly, in particular due to excessive lime input (passivating agent).

[0028] The invention relates to a device for additively manufacturing a component in a manufacturing process ("manufacturing device"), in which a building material is solidified in a process chamber on a building zone by irradiating the building material with at least one energy beam, the device comprising the following components:

[0029] a gas line for conducting process gas from the process chamber through the filter unit and back again into the process chamber,

[0030] - A system according to the invention, wherein the contamination measuring unit of the system is arranged in the gas line, preferably on the clean gas side of the gas line.

[0031] Preferably, the filter unit is designed to be at most two-stage, preferably at most single-stage. "Single-stage" here means that the filter unit can include filter elements connected in parallel, but no filter elements connected in series. Preferably, at least one filter element, preferably all filter elements of the filter unit are designed to be cleaned before, during or after the manufacturing process. This means that the filter is not a storage filter. Preferably, a particle separation unit (Partikelabscheideeinheit) is connected upstream of the filter unit.

[0032] It should be noted here that the device according to the invention can also have a plurality of irradiation devices, which are then controlled accordingly in coordination with the control data, as described above. It should also be mentioned again that in this regard, the energy beam can also consist of a plurality of superimposed energy beams, or the energy beam can involve both particle radiation and electromagnetic radiation, such as light radiation or preferably laser radiation.

[0033] The control device according to the invention is used to control an apparatus for a production process for additively manufactured components, wherein, at a construction zone, a construction material is solidified in a process chamber by irradiation with at least one energy beam, and wherein a process gas loaded with impurities is conducted out of the process chamber via a gas line, filtered and fed back into the process chamber again. The control device is designed to operate the production apparatus according to the method according to the invention or it comprises a system according to the invention.

[0034] The system according to the invention can be implemented in particular in the form of a computer unit, in particular in a control device, with suitable software. For example, the computer unit can have one or more cooperating microprocessors or the like for this purpose. In particular, it can be implemented in the form of suitable software program parts in the computer unit. The implementation based mainly on software has the advantage that the computer units used so far in the manufacturing plant, in particular in the control device, can also be converted in a simple manner by software or firmware updates to work in the manner according to the invention. In this regard, the object is also achieved by a corresponding computer program product, which has a computer program that can be directly loaded into the storage device of the computer unit, and has program sections so that when the program is executed in the computer unit, all steps of the method according to the invention are performed. In addition to the computer program, such a computer program product can include additional components such as documents and / or additional components, as well as hardware components such as hardware keys (dongles, etc.) for the use of the software. For transmission to the computer unit and / or for storage on or in the computer unit, a computer-readable medium can be used, such as a memory stick, a hard disk or other portable or permanently installed data carrier, on which program sections of the computer program readable and executable by the computer unit are stored.

[0035] Other particularly advantageous designs and improvements of the invention are derived from the dependent claims and the following description, wherein an independent claim of one claim category may also be improved similarly to a dependent claim or an embodiment of another claim category, and in particular individual features of different embodiments or variants may also be combined into new embodiments or variants.

[0036] According to a preferred method, if, when evaluating a certain number of measured values, it is found that the level of impurities in the process gas flowing through the gas line is greater than a predefined maximum impurity level (limit value for the level, for example a particle concentration), at least one of the following steps is performed:

[0037] - outputting information, in particular a warning notification (of a message) or a warning signal (for example an acoustic or optical signal), on an output device,

[0038] - interrupt (i.e. stop or pause) the manufacturing process,

[0039] - automatically entering information about the degree of impurities in the process gas flowing through the gas line, determined from a certain number of measured values, into a quality data record,

[0040] - Determine the status of a certain number of components manufactured in a manufacturing process and assess which (which) of the certain number of components are usable or which (which) are not usable.

[0041] According to a preferred method, for controlling the device, a certain number of measured values ​​are evaluated taking into account a certain number of process parameters of the device, which characterize the additive manufacturing of the component. This is done in particular under the assumption that the detected impurities are process-induced emissions, in particular powdered emissions, and / or passivating agents, in particular lime. Alternatively or additionally, the device is controlled by controlling or regulating a certain number of process parameters, in particular automatically, based on the evaluation of the certain number of measured values, wherein preferably, with respect to the control or regulation of the certain number of process parameters, at least one process parameter is optimized and / or faults are detected based on the evaluation of the certain number of measured values. The optimization or fault detection of at least one process parameter can be carried out based on targeted tests or based on evaluations. For example, when measuring the building material in the process gas flow, the flow of the process gas through the process chamber can be changed in a targeted manner, or when measuring smoke particles, the energy beam can be adjusted.

[0042] According to a preferred method, a process parameter of a number of process parameters characterizes at least one of the following criteria:

[0043] - the throughput, flow intensity, direction, area of ​​action and / or velocity of the process gas in the process chamber, in particular in each case relative to the uppermost layer of the building material,

[0044] - geometric and / or temporal uniformity of the throughput, flow intensity, direction, area of ​​action and / or velocity of the process gas in the process chamber, in particular in relation to the uppermost layer of the building material,

[0045] - the area, thickness, position and / or shape of the area to be cured on the construction zone for producing the component,

[0046] - input and / or selective curing of construction materials,

[0047] - distribution of the building material (especially layer-by-layer application),

[0048] at least one energy beam which causes selective solidification of the building material, in particular its wavelength, intensity, intensity distribution, beam diameter, beam cross section, deflection direction, direction of movement or speed of movement in the building zone,

[0049] - filling and / or overfilling of an overflow container which is provided for receiving excess construction material in the process chamber,

[0050] - Increased or uncontrolled emissions of construction materials into the atmosphere of the process chamber.

[0051] According to a preferred method, it is determined within the scope of the evaluation whether the trend of a measured value or a plurality of measured values ​​lies within a predetermined value range. Preferably, a certain number of measured values ​​are evaluated in a special manner for this purpose, for example

[0052] - comparing a measurement value to at least one predefined threshold value, and / or

[0053] - comparing the change in a certain number of measured values ​​with at least one predefined threshold value, and / or

[0054] - checking a plurality of measured values ​​for a recurring measured value trend pattern, wherein checking a certain number of measured values ​​for a recurring measured value trend pattern preferably comprises identifying recurring measured value anomalies (e.g. temporary measured value fluctuations), in particular measured value anomalies that occur shortly compared to a predetermined time period for measuring the measured values. In this case, the evaluation of the certain number of measured values ​​preferably comprises forming a time correlation between the results of measuring the certain number of measured values ​​and at least one process parameter of the device, which process parameter characterizes the additive manufacturing of the component. Examples of such process parameters have already been mentioned above.

[0055] According to a preferred method, during the additive production of the component, a number of measured values ​​are detected, preferably continuously or at regular time intervals, and a control or regulation of process parameters is preferably also performed.

[0056] According to a preferred method, the construction material is at least partially in powder form and preferably comprises metal powder.

[0057] According to a preferred method, a passivating agent, preferably lime particles, is added to the process gas flowing through the gas line downstream of the process chamber and / or upstream of the filter unit. As mentioned above, the passivating agent can cause quality losses when it enters the process chamber. Therefore, it is particularly advantageous to use the method according to the invention here.

[0058] According to a preferred method, the building material is conveyed into a process chamber for the production of the component. A metering device and / or a coater is arranged in the process chamber (for this purpose), which applies the building material layer by layer within the building zone. Preferably, during the control of the device, the building material is metered by means of the metering device and / or the coater as a function of a certain number of measured values, which can optionally also be done in a modified manner (i.e. in a manner different from that predetermined in advance) based on the measured values. Alternatively or additionally, the movement of the metering device and / or the coater is preferably also done in a modified manner as necessary.

[0059] The contamination measuring unit preferably comprises a filter rupture sensor, in particular a filter rupture sensor based on the triboelectric effect, and / or an optical turbidity sensor, and / or a camera, in particular for monitoring the brightness of images taken of the process atmosphere, and / or a thermo-optical measuring device, and / or a system designed for powder bed monitoring, and / or a measuring device for comparatively measuring the pressure (pressure difference) at two parallel filter stages.

[0060] Filter rupture sensors are usually arranged downstream of the particle filter to check or indicate the extent of its cleaning effect. Such filter rupture sensors usually operate according to the triboelectric principle, that is, the particles are charged by friction. Such sensors can be constructed as metal rods, which penetrate the pipeline of the gas circulation system with process gas. Here, the penetration can only be carried out at one part of the wall. The contact between the metal rod and the metal pipe can be avoided by the insulation. The electromagnetic shielding of the sensor is very helpful to avoid interference. The charged metal particles charged by friction contact the conductive metal rod and transfer their charge to the metal. For example, the total charge can be measured as a current ("total mass flow (Gesamtmassenstrom)"). BRIEF DESCRIPTION OF THE DRAWINGS

[0061] The present invention will be further described below in conjunction with the embodiments with reference to the accompanying drawings. In this regard, the same components are provided with the same reference numerals in different drawings. The accompanying drawings show:

[0062] Figure 1 A schematic, partly cross-sectional view of an embodiment of an apparatus for additive manufacturing is shown,

[0063] Figure 2 A block diagram showing a possible method flow according to an embodiment of the method of the present invention is shown,

[0064] FIG3 shows a circulating air filtration system according to the prior art,

[0065] Figure 4 A manufacturing facility with a circulating air filtration system and a particle separator is shown. DETAILED DESCRIPTION

[0066] The following embodiments are described with reference to a device 1 for additively manufacturing components in the form of a selective laser sintering or laser melting device, wherein it is once again explicitly pointed out that the present invention is not limited to selective laser sintering or laser melting devices. Therefore, the device is referred to below (without limiting the generality) as a "manufacturing device" 1.

[0067] Figure 1Schematically, such a manufacturing device 1 is shown in FIG. The device has a process chamber 3 or process room 3 with a chamber wall 4, in which the manufacturing process essentially takes place. In the process chamber 3, there is a container 5 open to the top, which has a container wall 6. The upper opening of the container 5 forms a correspondingly current working plane 7. The area of ​​this working plane 7 located within the opening of the container 5 can be used to construct the object 2 and is therefore called the construction area 8.

[0068] The container 5 has a base plate 11 which is movable in a vertical direction V and which is arranged on a carrier 10. The base plate 11 closes the container 5 downwards and thus forms its bottom. The base plate 11 can be formed integrally with the carrier 10, but it can also be a plate formed separately from the carrier 10 and fixed to the carrier 10 or simply supported on the carrier 10. Depending on the type of concrete building material (i.e., for example, the type of powder used) and the type of manufacturing process, a building platform 12 can be arranged on the base plate 11 as a building base, on which the object 2 is built. In principle, however, the object 2 can also be built on the base plate 11 itself, the base plate 11 then forming the building base.

[0069] The object 2 is constructed in principle by first applying a layer of construction material 13 to the construction platform 12, then - as described below - selectively curing the construction material 13 with a laser beam 22 as an energy beam at points that are to form parts of the object 2 to be manufactured, then lowering the substrate 11 with the aid of the carrier 10, thereby lowering the construction platform 12, and applying a new layer of construction material 13 and selectively curing it, etc. Figure 1 The object 2 constructed in the container on the construction platform 12 is shown in an intermediate state below the working plane 7. The object already has a plurality of cured layers surrounded by a still uncured construction material 13. As construction material 13, various materials can be used, preferably powders, in particular metal powders, plastic powders, ceramic powders, sand, filled or mixed powders, but also pasty materials, and optionally mixtures of a plurality of materials.

[0070] Fresh building material 15 is located in a supply container 14 of the production device 1. By means of a coating machine 16 which is movable in a horizontal direction H, the building material can be applied in the form of a thin layer in the working plane 7 or in the building zone 8.

[0071] Optionally, an additional radiation heating device 17 is located in the process chamber 3. This radiation heating device can be used to heat the applied building material 13, so that the irradiation device for selective curing does not have to introduce too much energy. In other words, for example, a certain amount of basic energy can be introduced into the building material 13 by means of the radiation heating device 17, which is of course still lower than the energy required for melting or sintering the building material 13. For example, infrared radiators or VCSEL radiators can be used as radiation heating devices 17.

[0072] For the selective curing, the manufacturing device 1 has an irradiation device 20 or a specific exposure device 20 with a laser 21. The laser 21 generates a laser beam 22, which is deflected by a deflection device 23 so as to sweep (abzufahren) an exposure path or track (hatch line) specified according to the exposure strategy in the layer to be selectively cured and selectively introduce energy. In addition, the laser beam 22 is focused in a suitable manner on the working plane 7 by a focusing device 24. The irradiation device 20 is preferably located outside the process chamber 3, and the laser beam 22 is guided into the process chamber 3 through a coupling window 25 arranged in the chamber wall 4 on the upper side of the process chamber 3.

[0073] The irradiation device 20 can, for example, include not only one laser, but a plurality of lasers. Preferably, this can be a gas laser or a solid-state laser or any other type of laser, for example a laser diode, in particular a VCSEL (Vertical Cavity Surface Emitting Laser) or a VECSEL (Vertical External Cavity Surface Emitting Laser) or a row of these lasers. Very particularly preferably, one or more unpolarized single-mode lasers, for example a 3 kW fiber laser with a wavelength of 1070 nm, can be used within the scope of the invention.

[0074] The manufacturing device 1 comprises a gas line 9, which introduces a process gas G into the process chamber 3 and leads it out of the process chamber 3, and a contamination measuring unit 18, which measures the degree of impurities in the process gas G flowing through the gas line 9. The gas flow flows through the gas-filled space above the container 5, and the energy beam 22 crosses the gas-filled space during operation. There is a gas outlet (right) opposite the gas inlet (left), so that the gas flow can completely pass through the construction area and can be led back if necessary (not shown). Here, the impurities A of the process gas G flowing out of the process chamber 3 are measured with the contamination measuring unit 18, but the contamination of the inflowing process gas G can also be measured. The contamination measuring unit 18 can, for example, include a filter rupture sensor, an optical turbidity sensor, a camera, a thermo-optical measuring instrument, or a system designed for powder bed monitoring.

[0075] The measured values ​​M detected by the contamination measuring unit 18 are transmitted to the control device 30 of the manufacturing device 1, which can draw conclusions about the degree of corresponding impurities in the process gas G flowing through the gas pipeline 9. The control device 30 is also used to control different components of the manufacturing device 1 in order to control the additive manufacturing process as a whole.

[0076] For recording the measured values ​​M, the control device 30 has an evaluation unit 32 which is designed to evaluate the measured values ​​M. The control unit 29 of the control device 30 serves to control the device 1 as a function of a certain number of measured values ​​M. The control unit 29 is designed to actuate the components of the irradiation device 20, namely here the laser 21, the deflection device 23 and the focusing device 24, and for this purpose sends irradiation control data BS designed as a function of the respective measured values ​​M to them.

[0077] The control unit 29 also controls the radiation heating device 17 by means of suitable heating control data HS, the coater 16 by means of coating control data ST and the movement of the carrier 10 by means of carrier control data TS and thus the layer thickness.

[0078] The control device 30 is here coupled to an output device 39, such as a terminal with a display or the like, for example, via a bus 60 or another data connection. If the degree of contamination is too high, it can send a warning message to the output device 39 via the bus 60. Via the terminal, the operator can additionally control the control device 30 and thus the entire production plant 1, for example by transmitting process control data PS.

[0079] It is also pointed out here again that the invention is not limited to such a manufacturing device 1. It can be applied to other methods for the generative or additive manufacturing of three-dimensional objects by layer-by-layer application and selective curing of building materials, wherein an energy beam for curing is emitted to the building material to be cured. Therefore, the irradiation device can not only be the laser described here, but also any device with which energy can be selectively introduced as wave radiation or particle radiation onto or into the building material. For example, other light sources, electron beams, etc. can be used instead of lasers.

[0080] Even in Figure 1 Only a single object 2 or component 2 is shown, but it is also possible and usually common to produce a plurality of objects in parallel in a process chamber 3 or container 5. For this purpose, the building material is scanned layer by layer by an energy beam 22 at a position corresponding to the cross section of the object in the respective layer.

[0081] Figure 2A block diagram showing a possible method flow according to an exemplary embodiment of the method according to the invention for controlling a manufacturing process for additive manufacturing of a component 2 in a device 1, such as Figure 1 As shown. To this end, in the process chamber 3, on the construction zone 8, the construction material 13 is solidified by irradiating the construction material 13 with at least one energy beam 22. The process gas G loaded with impurities A is discharged from the process chamber 3 through the gas pipeline 9, filtered and introduced back into the process chamber 3 again. The construction material 13 is at least partially powdered and preferably includes metal powder. If metal powder is processed, a passivating agent, preferably lime particles, is added to the process gas G flowing through the gas pipeline 9 downstream of the process chamber 3 and / or upstream of the filter unit 40 (see the figure below) for fire protection reasons. All powdered materials may be present in the process gas as impurities. In particular, in the case of a tear or break in the filter or other components (such as seals) that should separate the clean gas and the impure gas from each other, a non-negligible amount of impurities is introduced into the process chamber 3 again with the process gas G, which leads to a quality loss of the manufactured component 2.

[0082] In step I, a certain number of measured values ​​M are detected by the contamination measuring unit 18, wherein each measured value M allows conclusions to be drawn about the degree of impurities of the process gas G flowing through the gas line 9 at the time of the detection. In this case, the measured value M can directly indicate the degree of the respective impurity, or can provide a value with the help of which the degree of impurities can be determined, for example based on turbidity optically recorded by a powder bed detection system. The detection of the measured values ​​M takes place during the additive manufacturing of the component 2, preferably continuously or at regular time intervals.

[0083] In step II, the measured value M is evaluated. Within the scope of the evaluation, it is determined whether the trend of a measured value M or a plurality of measured values ​​M lies within a preset value range. The measured value M can be evaluated in different ways. For example, a measured value M or its change is compared with at least one predefined threshold value. It is also possible to check a plurality of measured values ​​M for repeated measured value trend patterns, wherein, for example, such a check can include the identification of recurring measured value anomalies (e.g. temporary measured value fluctuations). The evaluation can also include the formation of a time correlation between the detection results of a certain number of measured values ​​M and at least one process parameter P of the device 1, which characterizes the additive manufacturing of the component 2.

[0084] For example, the process parameter P can be characterized by one of the following criteria:

[0085] a) the throughput, flow intensity, direction, area of ​​action and / or velocity of the process gas G in the process chamber 3 , in particular in relation to the uppermost layer of the building material 13 ,

[0086] b) geometric and / or temporal uniformity of the throughput, flow intensity, direction, area of ​​action and / or velocity of the process gas G in the process chamber 3, in particular in relation to the uppermost layer of the building material 13,

[0087] c) the area, thickness, position and / or shape of the region to be cured on the building zone 8 for producing the component 2,

[0088] d) input and / or selective curing of construction material 13,

[0089] e) distribution of the building material 13 (e.g. layer-by-layer application),

[0090] f) at least one energy beam 22 which causes the selective curing of the building material 13, in particular its wavelength, intensity, intensity distribution, beam diameter, beam cross section, deflection direction, movement direction and / or movement speed within the building zone 8,

[0091] g) filling and / or overfilling of an overflow container which is provided for receiving excess construction material 13 in the process chamber 3, or

[0092] h) Increased or uncontrolled emission of construction material 13 into the atmosphere of process chamber 3 .

[0093] In the steps shown here, an evaluation of a number of measured values ​​M is carried out taking into account a number of process parameters P of the device 1 which characterize the additive manufacturing of the component 2, in particular under the assumption that the detected impurities are process-induced emission materials and / or passivating agents.

[0094] In step III, the device 1 and / or an output device 39 connected to the production process in a data-technical manner is controlled based on the evaluation of a certain number of measured values ​​M. In this example, the control of the device 1 is carried out by means of the evaluation, control or regulation of a certain number of process parameters P based on the evaluation of a certain number of measured values ​​M, wherein optimization and / or fault detection with respect to at least one process parameter can be carried out based on the evaluation of the number of measured values ​​M. For example, in order to Figure 1 The device manufacturing component 2 can control the metering of the building material 13 by means of the coating machine 16 or its movement based on the measured value M.

[0095] If, when evaluating the measured values ​​M, it is determined that the degree of impurities in the process gas G flowing through the gas line 9 is greater than a predefined maximum impurity level, a warning message is output, for example, on the output device 39. In addition, the production process can be interrupted until the degree of contamination has fallen again, and the information about the degree of impurities can be automatically entered in the quality data record.

[0096] FIG3 shows a circulating air filter system 40, which has a pre-filter stage 42, a particle receiving container 44, a filling state sensor 43 for measuring the filling state in the particle receiving container 44, a fine filter stage 41 and a blower 45. As shown by the arrow, the process gas G flows from the process chamber 3 to the pre-filter 42 and is filtered there, wherein during the purification of the pre-filter 42, the filter (particles) are deposited in the particle receiving container 44 at specific time intervals. Subsequently, the pre-purified process gas G flows through the fine filter stage 41 and is then directed back to the process chamber 3 again through the blower 45. Such a circulating air filter system 40 is known in the prior art. If a tear or break that is not necessarily noticed occurs in the fine filter stage 41, impurities may remain in the process gas G and return to the process chamber 3. This may impair the manufacture of the component 2. Through the method of the present invention, damage to the filter can be noticed early and countermeasures or warnings can be automatically introduced.

[0097] Figure 4 The production plant 1 is shown with a circulating air filter system 40 and a particle separator 50. The process gas G is taken as a raw gas, ie, loaded with impurities, from the production plant 1 (see for example Figure 1 ) is led out (arrow above). Here, it flows through the first pollution measuring unit 18 (above). It can now be introduced directly into the pre-filter stage 42 and cleaned there (dashed arrow), but in this embodiment, it first flows through the particle separator 50, which removes particles from the process gas G by means of a cyclone separator and collects them in the particle receiving container 44. Now, the process gas G flows through the pre-filter stage 42 and the fine filter stage 41 and returns to the process chamber 3 of the manufacturing device 1 through the clean gas line 49. Here, it flows through the second pollution measuring unit 18 (below). By using a simple measurement of the second pollution measuring unit 18 or a comparative measurement of the two pollution measuring units 18, the degree of pollution of the process gas G returned through the clean gas line 49 can now be determined, and measures can be introduced according to the method of the present invention if necessary.

[0098] Finally, it is pointed out again that the above-described device in detail is only an embodiment and can be modified in various ways by a person skilled in the art without departing from the scope of the invention. For example, curing can also be carried out with other energy beams instead of lasers. Moreover, the use of the indefinite article "a" or "an" does not exclude that the relevant feature may also be present in plurality. Likewise, the term "unit" does not exclude that it consists of a plurality of cooperating subcomponents, which may also be spatially distributed if necessary. The expression "a certain number" is to be understood as "at least one".

[0099] Description of Reference Numerals

[0100] 1Equipment / manufacturing equipment for additive manufacturing

[0101] 2 Components / Objects

[0102] 3Process room / process cavity

[0103] 4 cavity wall

[0104] 5 Containers

[0105] 6 container walls

[0106] 7Working Planes

[0107] 8 Construction Area

[0108] 9 Gas pipeline

[0109] 10 carrier

[0110] 11 substrate

[0111] 12 Construction Platform

[0112] 13 (inside container 5) structural material

[0113] 14 Storage Containers

[0114] 15 Construction material (in storage container 14)

[0115] 16 Coating machine

[0116] 17 Radiant heating device

[0117] 18 pollution measurement units

[0118] 20Irradiation equipment / exposure equipment

[0119] 21 Lasers

[0120] 22 Laser beam / energy beam

[0121] 23 Deflection device / scanner

[0122] 24 Focusing device

[0123] 25 coupling window

[0124] 29Control Unit

[0125] 30 Control device

[0126] 31 Irradiation control interface

[0127] 32 evaluation units

[0128] 39 Terminal / output device

[0129] 40-cycle air filtration system

[0130] 41 fine filtration level

[0131] 42 pre-filtration stages

[0132] 43 Filling status sensor

[0133] 44 Particle receiving container

[0134] 45 Blower

[0135] 48 Crude Gas Line

[0136] 49 Net Gas Line

[0137] 50 Particle Separator

[0138] 60 bus

[0139] A impurity

[0140] BS control data / exposure control data

[0141] GProcess Gas

[0142] HHorizontal direction

[0143] HS heating control data

[0144] M measurement

[0145] P process parameters

[0146] PS process control data

[0147] ST coating control data

[0148] TS carrier control data

[0149] V vertical direction.

Claims

1. A method for controlling a manufacturing process of an additively manufactured component (2) in a device (1), wherein: The method comprises the following steps: curing a building material (13) in a process chamber (3) by irradiating the building material (13) with at least one energy beam (22), wherein a process gas (G) laden with impurities (A) is conducted out of the process chamber (3) via a gas line (9), filtered and fed back into the process chamber (3); - detecting a number of measured values ​​(M) by means of a contamination measuring unit (18), wherein each measured value (M) enables a conclusion to be drawn about the degree of the impurity of the process gas (G) flowing through the gas line (9) which is present at the time of the detection, - evaluating said certain number of measurements (M), - controlling the device (1) and / or an output device (39) connected to the production process in terms of data technology as a function of the evaluation of the certain number of measured values ​​(M).

2. The method according to claim 1, wherein: If, when evaluating the number of measured values ​​(M), it is determined that the degree of impurities in the process gas (G) flowing through the gas line (9) is greater than a preset maximum impurity degree, at least one of the following steps is performed: - outputting information, in particular a warning message or a warning signal, on the output device (39), - interruption of said manufacturing process, - automatically entering information about the degree of the impurity in the process gas (G) flowing through the gas line (9), determined from the number of measured values ​​(M), into a quality data record, - determining the status of a certain number of components (2) manufactured in the manufacturing process and assessing which of the certain number of components (2) are usable and / or which are not usable.

3. The method according to claim 1 or 2, wherein: To control the device (1): - the evaluation of the number of measured values ​​(M) is performed taking into account a number of process parameters (P) of the device (1), which process parameters are characteristic of the additive manufacturing of the component (2), and - Based on the evaluation of the certain number of measured values ​​(M), the device (1) is controlled by means of, in particular, automatically controlling or adjusting the certain number of process parameters (P), wherein, preferably, with respect to the control or adjustment of the certain number of process parameters (P), optimization and / or fault detection are performed for at least one process parameter based on the evaluation of the certain number of measured values ​​(M).

4. The method according to claim 3, wherein: A process parameter (P) of the certain number of process parameters (P) characterizes at least one of the following criteria: - a throughput, flow intensity, direction, area of ​​action and / or velocity of the process gas (G) in the process chamber (3), in particular in relation to the uppermost layer of the building material (13), - geometric and / or temporal uniformity of the throughput, flow intensity, direction, area of ​​action and / or velocity of the process gas (G) in the process chamber (3), in particular in relation to the uppermost layer of the building material (13), - the area, thickness, position and / or shape of the area to be cured on the construction zone (8) for producing the component (2), - input and / or selective curing of the construction material (13), - the distribution of said construction material (13), the at least one energy beam (22) which causes the selective curing of the building material (13), in particular its wavelength, intensity, intensity distribution, beam diameter, beam cross section, deflection direction, movement direction and / or movement speed within the building zone (8), - filling and / or overfilling of an overflow container, which is provided for receiving excess of the construction material (13) in the process chamber (3), - increased or uncontrolled emission of the construction material (13) into the atmosphere of the process chamber (3).

5. A method according to any one of the preceding claims, wherein: In the context of the evaluation, it is determined whether the course of a measured value (M) or of a plurality of measured values ​​(M) lies within a predefined value range, Preferably, the certain number of measured values ​​(M) is evaluated in the following manner: - comparing a measurement value (M) with at least one predefined threshold value, and / or - comparing the variation of a certain number of measured values ​​(M) with at least one predefined threshold value, and / or - checking a plurality of measurement values ​​(M) for a repetitive measurement value trend pattern, wherein, preferably, the checking of the certain number of measurement values ​​(M) for the repetitive measurement value trend pattern comprises identifying repetitive measurement value anomalies, in particular measurement value anomalies that occur shortly compared to a predetermined time period for measurement value detection, and preferably, wherein the evaluation of the certain number of measurement values ​​(M) comprises forming a time correlation between the detection results of the certain number of measurement values ​​(M) and at least one process parameter (P) of the device (1), which process parameter characterizes the additive manufacturing of the component (2).

6. A method according to any one of the preceding claims, wherein: During the additive production of the component (2), a number of measured values ​​(M) are preferably detected continuously or at regular time intervals, and the process parameters are preferably also controlled or regulated.

7. A method according to any one of the preceding claims, wherein: The construction material (13) is at least partially powdered and preferably comprises metal powder.

8. The method according to claim 7, wherein: Downstream of the process chamber (3) and / or upstream of the filter unit (40), a passivating agent, preferably lime particles, is added to the process gas (G) flowing through the gas line (9).

9. A method according to any one of the preceding claims, wherein: In order to produce the component (2), the building material (13) is conveyed into the process chamber (3), and a metering device and / or a coating machine (16) is arranged in the process chamber (3), which applies the building material (13) layer by layer within the building area, and wherein, during the control of the device (1), depending on the certain number of measured values ​​(M), - the dosing of the construction material (13) is carried out or carried out in a modified manner by means of the dosing device and / or the coating machine (16), and / or - the movement of the metering device and / or the coating machine (16) is carried out or carried out in a modified manner.

10. A system for controlling a manufacturing process of an additively manufactured component (2) in an apparatus (1), wherein: In a process chamber (3), a building material (13) is solidified by irradiating the building material (13) with at least one energy beam (22) at a building area (8), and a process gas (G) laden with impurities (A) is conducted out of the process chamber (3) via a gas line (9), filtered and fed back into the process chamber (3), the system comprising: a contamination measuring unit (18) which is designed to detect a number of measured values ​​(M), wherein each measured value (M) enables a conclusion to be drawn about the degree of the respective impurity in the process gas (G) flowing through the gas line (9), an evaluation unit (32) designed to evaluate the number of measured values ​​(M), a control unit (29) which is designed to control the device (1) and / or an output device (39) which is connected to the production process in terms of data technology, as a function of the certain number of measured values ​​(M), The system is designed in particular to carry out the method according to one of the preceding claims.

11. The system according to claim 10 is designed as a conversion kit for an apparatus (1) for additive manufacturing of components (2), and is designed so that the contamination measurement unit (18) can be arranged in a gas pipeline (9) of the apparatus (1) and the evaluation unit (32) and the control unit (29) can be arranged or implemented in a control device (30) of the apparatus (1).

12. The system according to claim 10 or 11, wherein: The contamination measuring unit (18) comprises a filter rupture sensor, in particular a filter rupture sensor based on the triboelectric effect, and / or an optical turbidity sensor, and / or a camera, in particular for monitoring the brightness of images taken through the process atmosphere, and / or a thermo-optical measuring device, and / or a system designed for powder bed monitoring, and / or a measuring device for comparatively measuring the pressure at two parallel filter stages.

13. A device (1) for additively manufacturing a component (2) in a manufacturing process, in which, in a building zone (8), in a process chamber (3), the building material (13) is solidified by irradiating the building material (13) with at least one energy beam (22), the device (1) comprising: a gas line (9) for conducting process gas (G) from the process chamber (3) through a filter unit (40) and back into the process chamber (3), - System according to any of claims 10 to 12, wherein the contamination measuring unit (18) of the system is arranged in the gas line (9), preferably on the clean gas side of the gas line (9).

14. The device according to claim 13, wherein: The filter unit (40) is designed to be at most two-stage, preferably at most single-stage, and / or wherein at least one filter element, preferably all filter elements, of the filter unit (40) are designed to be cleaned before, during or after the manufacturing process, preferably wherein a particle separation unit is connected upstream of the filter unit (40).

15. A computer program that can be loaded into a programmable control device (30), the computer program having a program code so that when the computer program is executed on the control device (30), all steps of the method according to any one of claims 1 to 8 or 9 are executed.

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