Additive manufacturing process

Abstract

Additive manufacturing process, wherein an object (19) is manufactured by applying powder (17) layer by layer onto a base (20) along a build surface (A) via an application device (3, 11) and combining it in certain areas to form a matrix (18), wherein the position of the base (20) is checked by at least one measurement using a sensor device (7) designed as a tactile sensor (7) and the position is automatically corrected at least relative to the application device (3, 11) depending on the at least one measurement, characterized in that the sensor device (7) is arranged on a robot articulated arm (6) by which it is moved into a measuring position for the respective measurement, and at least one measurement is carried out on a prefabricated base body (22) which is arranged on a build platform (21) from which the object (19) is removed after its completion.and which remains connected to the matrix (18) as part of the finished object (19).

Description

[0001] The invention relates to an additive manufacturing process.

[0002] There are various processes available today by which, based on design data, three-dimensional models can be produced from formless or form-neutral materials such as powders (possibly with the addition of a binder) or liquids (which also includes temporarily molten solids). These processes are also known under collective terms such as "rapid prototyping", "rapid manufacturing" or "rapid tooling". Often, a primary forming step takes place in which the starting material is either liquid from the outset or is liquefied temporarily and hardens at the intended location. A well-known process in this regard is fused filament fabrication (FFF), in which a workpiece is built up layer by layer from thermoplastic material. The plastic is, for example,supplied in powder or strand form, melted and applied in molten form by a print head, which successively applies individual, usually horizontal layers of the object to be produced.

[0003] In addition, processes are known in which a powdered material, e.g., a plastic, is applied layer by layer and selectively cured using a locally applied or printed binder. In yet other processes, such as selective laser sintering (SLS), a powder is applied layer by layer to a build platform, e.g., using a squeegee. The powder is selectively heated and sintered using suitable focused radiation, e.g., a laser beam. After a layer has been built up, the build platform is lowered slightly, and a new layer is applied. The powder can be plastics, ceramics, or metals.

[0004] According to the current state of the art, numerous steps in additive manufacturing processes, especially powder bed processes such as SLS, still require manual execution. For example, the alignment of the build platform must be manually measured and corrected for the successful formation of the powder bed. If separately manufactured components are to be integrated into the corresponding part, additive manufacturing must be interrupted to insert the corresponding component, which is also done manually. Such manual processes not only increase the process time but also expose the production area to the ambient air, which, depending on the type of powder used, could lead to its oxidation, possibly even combustion or explosion.

[0005] WO 2016 / 088048 A1 discloses a device for melt coating, in which an object is built from plastic dispensed from a nozzle cartridge. To temperature-control the nozzle cartridge and thus the plastic to be dispensed, the cartridge can be transferred from a build-up area to a flow regulator, which exposes the cartridge to a temperature-controlled gas flow. The transfer can be performed by a robot arm. Optionally, the cartridge can also be guided by a robot arm during melt coating, or the finished object can be removed from the build-up area by a robot arm.

[0006] WO 2016 / 088049 A1 discloses a similar device, which can additionally be provided with a robotic arm for removing a nozzle cartridge from a cartridge holder and inserting it into an extrusion head or returning it to the cartridge holder. A robotic arm can also replace a plastic thread within the nozzle cartridge.

[0007] US 2016 / 0243759 A1 shows a self-contained device for manufacturing a product in multiple work steps. At least part of the product is manufactured using an additive manufacturing device. Furthermore, it is provided that the product is transferred from one manufacturing device to another by a transfer mechanism, e.g., a robot arm. Robot arms can also be used to assemble parts of the product. In one embodiment, a movable extruder and a robot arm are arranged within a housing. Scanners, which can be moved on rails and are used to monitor the product, are arranged on the walls of the housing.

[0008] DE 10 2014 213 888 A1 shows a device for additive manufacturing, comprising a coating device with a coating element and an adjusting device in which a contact switches when a vertical position of an underside of an actuating element is equal to a vertical position of an underside of the coating element or has a predetermined offset therefrom.

[0009] DE 20 2015 103 932 U1 discloses a 3D printing device which is designed to print several layers of material on top of each other and to print at least one layer such that it has a different thickness in at least two places, wherein the thickness is selected such that it at least partially compensates for an unevenness of a base support or a support for a workpiece.

[0010] CN 205 033 598 U shows a leveling system for 3D-printed substrates comprising a support substrate, a mold substrate mounted on the support substrate, four distance sensors, a numerical control unit, a drive device, and a mold cylinder. The distance between the four corners of the molded substrate and the reference plane is measured to output four distance signals. The numerical control unit is configured to receive the four distance signals and calculate four distance deviations between the four distance signals and the preset distance.

[0011] DE 11 2016 001 314 T5 shows a processing machine that enables subtractive and additive machining for a workpiece. US 6 363 606 B1 shows a method for manufacturing a structure using 3D printing techniques.

[0012] Given the current state of the art, the efficiency of additive powder bed processes still offers room for improvement. In particular, it would be desirable to shorten the process time and reduce the risk of contamination of the powder used.

[0013] The invention is based on the object of providing an efficient additive manufacturing process.

[0014] According to the invention, the object is achieved by an additive manufacturing method having the features of claim 1, wherein the subclaims relate to advantageous embodiments of the invention.

[0015] It should be noted that the features and measures listed individually in the following description can be combined with one another in any technically reasonable manner and demonstrate further embodiments of the invention. The description further characterizes and specifies the invention, particularly in conjunction with the figures.

[0016] The invention provides an additive manufacturing process. This process can be classified as rapid prototyping or rapid manufacturing. However, it is suitable not only for the production of prototypes or individual models, but also, in particular, for series production.

[0017] In the method according to the invention, an object is manufactured by applying powder layer by layer to a base along a construction surface using an application device and bonding it regionally to form a matrix. Overall, this can also be referred to as a powder bed process. Examples of powders that can be used are plastic powder, ceramic powder, or metallic powder. A metallic powder is any powdery or particulate material that contains at least one metal. It can also be an alloy or a mixture of particles of different metals. The powder can also contain semi-metals or non-metals, for example as a component of an alloy. Possible metals include aluminum, titanium, and iron.

[0018] The application device applies a layer of this powder along a build-up surface. The layer thickness can be, for example, between 10 µm and 500 µm. Other layer thicknesses are also conceivable. Such an application device can have one or more discharge openings from which the powder emerges, for example, following the force of gravity. Typically, the application device or its discharge openings are moved back and forth in an oscillating manner along the build-up surface. To enable a smooth and even layer build-up, the application device can comprise a smoothing device, e.g. a doctor blade, brush or blade, which is moved parallel to the build-up surface and smooths the surface of the powder. As a rule, the build-up surface is flat, which can also be referred to as a build-up plane. The application takes place layer by layer on a base, i.e.The first layer is applied directly onto the base, after which the subsequent layers are applied successively on top of each other.

[0019] Once a layer of powder has been applied, or at least part of it, the powder is bonded in certain areas to form a matrix. This bonding can be achieved, for example, by selectively applying a binder. The binder is usually liquid when applied and subsequently solidifies or hardens. This bonds the powder particles in the corresponding area together and, together with the binder, forms the matrix. Alternatively, the powder particles can also be sintered or melted. Corresponding processes include selective laser sintering (SLS), selective electron beam melting (SEBM), or selective laser melting (SLM).

[0020] The latter method, in particular, can be used. After each layer has been applied, the powder is melted in certain areas by a laser beam and then solidified. This process transforms the powder into a coherent solid, which serves as the matrix. At the same time, the powder of the last layer added is fused with the solid structures of the underlying layer or several underlying layers, thereby creating a cohesive bond between the layers. Depending on the layer thickness, among other things, it is possible for the laser beam to melt the material to a depth corresponding to several layer thicknesses.

[0021] In the sense of a targeted manufacturing process, the laser beam normally acts according to a specific pattern. One could also say that a predetermined area is irradiated. In this case, it is possible, for example, for the area to be scanned by a tightly focused laser beam or for a specific radiation pattern to be projected all at once. Various scanning patterns are possible; for example, the contour of a surface can be scanned first, followed by its interior, or vice versa. The alignment of the laser beam with respect to the build surface is generally not achieved by moving the laser itself, but by deflecting a beam generated by the laser using at least one movable mirror. It goes without saying that the spatial or temporal radiation pattern of the laser beam can be controlled according to predetermined data (e.g. CAM data) of an object to be manufactured.The irradiated area corresponds to a (usually flat) cross-section of the object. This type of process can also be referred to as "cladding." In electron beam melting, an electron beam is used instead of a laser beam to melt the powder particles. In selective laser sintering, a lower amount of energy is applied by the laser beam, so that the powder particles are not completely melted but only sintered.

[0022] The base typically comprises a build platform, which generally has a flat surface onto which the first layer of powder is applied. Walls may be arranged on the side of the build platform to prevent uncontrolled powder falling off. The base may also comprise a base body, which is arranged or fixed on the build platform and is intended to form part of the finished object. This means that the aforementioned matrix is ​​created at least partially directly on the base body, typically forming a material bond and / or form fit. This can also be referred to as a hybrid process, in which, for example, a "conventional" manufacturing process for producing the base body can be combined with an additive manufacturing process. Of course, the base body itself could also have been manufactured in advance using an additive manufacturing process.

[0023] During the layer-by-layer application, melting, and solidification, the base with the object is normally moved away from the build surface along a transport direction. The transport direction is of course at an angle to the build surface, typically perpendicular to the build surface. In a typical build, the build surface is horizontal (i.e. at right angles to the direction of gravity) and the transport direction is vertical. This means that during the production process, the base is successively lowered by one layer thickness for each layer that is applied by the application device. Transport is normally intermittent, i.e. discontinuous, with a layer being applied while the base is stationary, and the base with the object is only transported further (corresponding to one layer thickness) once the layer has been completely applied. The effect of the laser beam orThe application of an electron beam or the application of a binding agent usually occurs while the base body is stationary. However, continuous transport would also be theoretically conceivable, in which case the movement of the application device, as well as the control of the laser beam, etc., would have to be adapted to the movement of the base. The described layer-by-layer construction and the successive transport of the base body with the object continues until the object is finally completed (e.g., according to the underlying CAM data).

[0024] Alternatively, it would also be possible for the base to be held stationary while the applicator is moved away from the build surface. This means that after applying a layer, the applicator would be moved, usually raised. Here, too, continuous transport would be possible as an alternative to intermittent transport of the applicator.

[0025] According to the invention, a position of the base is checked by at least one measurement using a sensor device, and the position is automatically corrected, at least relative to the application device, depending on the at least one measurement. At least one measurement is therefore carried out by means of the sensor device, by means of which a position of the base can be checked. The sensor device can be arranged stationary or, preferably, movable, so that it is moved into a predetermined measuring position for the respective measurement. Typically, the at least one measurement is carried out on the base itself; however, it would also be possible to carry out the measurement on another element from whose position the position of the base can be deduced. A plurality of measurements can also be carried out. In this case, position measurements could be carried out spatially continuously, for example by scanning a surface.In particular, a plurality (e.g. exactly two) of discrete position measurements could also be carried out at different points.

[0026] The measurement checks the position of the base, i.e. an actual value is compared with a target value. If there is a deviation or if the deviation exceeds a specified threshold, an automatic correction is made which at least approximates the position to the target value and ideally sets it to the target value. This makes it possible to detect and rectify any misalignment of the base that could impair the quality of the manufacturing process. One possible consequence of misalignment would be, for example, that the powder layers are applied incorrectly relative to the base. For error-free manufacturing, precise application of the first layer is particularly crucial, e.g. to ensure correct connection to the base. In many cases, it is not the absolute position of the base that is important, but rather the position relative to the application device.In this respect, the correction is at least made relative to the application device, which includes the possibility of adjusting the position of the application device rather than the (absolute) position of the base. Normally, however, a correction of the absolute position of the base is easier to implement. A particular advantage of the method according to the invention is that the position correction is performed automatically, i.e., no manual intervention is necessary. This has a positive effect on the process time, and it also prevents contamination of the production area, which could be caused by manual intervention.

[0027] Typically, at least one measurement is taken before the first powder layer is applied. Usually, in addition to this, or possibly alternatively, it is also possible to take at least one measurement during the production of the workpiece.

[0028] Preferably, the sensor device is mounted on a robotic articulated arm, which moves it into a measuring position for the respective measurement. Thus, a robotic articulated arm is provided that supports the sensor device. The sensor device is normally mounted at the end of the robotic articulated arm.

[0029] The latter usually has at least two arm segments that are articulated to one another. Furthermore, a first arm segment can be articulated to a stationary base, and the sensor device can be articulated to a second arm segment. The robot articulated arm is preferably designed to position the sensor device as desired, both in three-dimensional terms and in three angles of rotation. In this way, it is possible to bring the sensor device into an optimal measuring position relative to the base for a measurement. After the measurement, the sensor device can be moved either to a further measuring position for a subsequent measurement or to a position that can be referred to, for example, as a standby position. The standby position is normally selected such that neither the robot articulated arm nor the sensor device interfere with the operation of the application device.

[0030] In principle, there are no restrictions on the type and design of the sensor device within the scope of the invention. For example, the position of the base could be determined contactlessly using sound waves or electromagnetic waves by evaluating the travel time of a signal emitted by the sensor device and reflected by the object to be measured. However, the accuracy of the measurement should be on the order of magnitude of a layer thickness, which, as described above, can be, for example, between 10 µm and 500 µm. Such accuracies cannot be achieved using travel time measurements (at least with sound waves), or only with great effort. Alternatively, the measurement could be based on triangulation, e.g., in which a laser beam is sent to the object and the point of impact is recorded by a camera arranged offset from the laser.With the methods mentioned, it is advantageous if the sensor device can be moved into an optimal measuring position by the robot's articulated arm, which can reduce measurement errors. At least one measurement is carried out by contact with a sensor device designed as a tactile sensor. The corresponding contact measurement can be carried out optimally using the aforementioned robot articulated arm. This means that a tactile sensor is arranged on the robot's articulated arm and is moved towards the object to be measured, usually the base, until physical contact is established. In this way, one or more points can be targeted and their three-dimensional coordinates determined. From this, the position of the base is in turn derived.

[0031] The position of the base is generally given by 6 degrees of freedom, namely 3 degrees of freedom of translation and 3 degrees of freedom of rotation. In the simplest case, for example, the height, i.e. the vertical position, of the base can be determined by a single measurement and corrected if necessary. If necessary, the horizontal position could also be corrected. In particular, however, it is also possible that there is an unforeseen inclination of the base which would have a detrimental effect on the manufacturing process. Therefore, it can be provided in particular that at least one angle of inclination of the base is automatically corrected depending on the at least one measurement. Normally, it is necessary to carry out at least two measurements to determine an angle of inclination. For example,A tactile sensor could be placed at two different points on the surface of a platform, with a deviation in the vertical positions indicating an inclination of the platform. This would create an angle of inclination relative to the horizontal, which could be reduced or eliminated by suitable actuators connected to the base. Of course, two angles of inclination in different directions could be determined, for example, through three (or more) individual measurements.

[0032] The advantages of the method according to the invention are particularly noticeable when the object is manufactured in an inert gas atmosphere. This is normally necessary when using metallic powder, as this could oxidize, burn, or even explode in ambient air. In this case, the method is carried out at least partially in a housing that can, for example, at least partially (normally completely) enclose the base, the application device, and the robotic articulated arm. The term "inert gas atmosphere" in this context also includes an atmosphere that contains a reduced amount of reactive gases such as oxygen, but is enriched with inert gas compared to normal air. Immediately before and during the actual production, no manual intervention in the production area is necessary, as the measurements and corrections are carried out automatically. This meansthe inert gas atmosphere remains stable (although this usually requires a certain supply of inert gas, e.g. due to leaks that are difficult to avoid or due to the need to extract smoke generated by the laser).

[0033] As already indicated above, the base typically has a build platform. According to a preferred embodiment of the method, at least one measurement is performed on a build platform from which the object is removed after its completion. For example, a surface of the build platform can be measured non-contact or, as described above, using a tactile sensor. The tactile sensor can be moved by the robot's articulated arm until it touches one or more points on the surface, from which the vertical position of the build platform and one or more angles of inclination can be determined.

[0034] At least one measurement will be carried out on a prefabricated base body arranged on the build platform, which remains connected to the matrix as part of the finished object. As already explained, such a base body is manufactured in advance, e.g. conventionally or by an upstream additive manufacturing process, and further structures are added to the base body by the manufacturing process according to the invention. If the position of the base body deviates from a target value, this can be corrected either by correcting the position of the base body relative to the build platform or by changing the position of the build platform itself on which the base body is arranged. Under certain circumstances, a measurement on the base body can also be used to determine a position of the build platform that needs to be corrected, or vice versa.

[0035] If a base body is provided on the build platform, it is generally not possible to build a powder bed exclusively on the base body. Instead, the base body is usually embedded in the powder. In other words, the areas next to the base body must be filled with powder. This can be difficult or even impossible for an oscillating application device as described above, if it is designed to apply a continuous, even layer of powder. According to a preferred embodiment, powder is therefore applied to the build platform next to the base body by an application device arranged on an articulated robot arm. The application device can, for example, have a nozzle arranged at the end of the articulated robot arm, which is connected to a line via which the powder is supplied.Due to the high mobility of the robot's articulated arm, even with a complex base body design, all areas adjacent to the base body can be filled with powder, for example, even if there are undercuts. "Adjacent to the base body" means that this area is located within a plane running through the base body and parallel to the build surface. The application device mounted on the robot's articulated arm can, in a sense, be a secondary application device used solely for the purpose described here, while the actual buildup of closed powder layers is carried out by a primary application device. Alternatively, however, this could also be the sole application device.

[0036] Depending on the type of object being manufactured, it may be desirable to add components that cannot be manufactured using additive manufacturing in the powder bed process. These may include, for example, sensors, magnets, fastening elements, or other components. In a typical embodiment, such a component can be arranged in a recess formed within the matrix and held there, for example, by a form fit. Such a component can also be referred to as an "insert" or "insert part." According to a further development of the method according to the invention, a recess for receiving an insert part is created within the object by unbinding powder in an area provided for the recess, and this powder is subsequently removed by a cleaning device arranged on a robot articulated arm. This meansDuring the production of the object, in an area where the recess will later be arranged, the powder is not combined to form the matrix, but remains loose. Of course, the area must be at least partially surrounded by areas in which the powder is combined to form the matrix. In order to make space for the insert, the loose powder must be removed. However, to ensure optimal form closure between the insert and the surrounding matrix, it is advisable for the insert to be inserted into the recess during additive manufacturing. This in turn means that the recess must be freed of loose powder, or one could also say cleaned, during additive manufacturing. In the described variant of the process, this is done by a cleaning device that is arranged on an articulated robot arm. The cleaning device could, for example,be designed as a suction or blowing device that sucks in the loose powder using negative pressure or blows the powder away with a gas stream. Alternatively or additionally, the cleaning device could also have mechanical means for removing the powder, such as bristles or the like, which can be moved in a rotating or oscillating manner. It goes without saying that the control of the robot articulated arm and the cleaning device is preferably automatic. In any case, the recess can be cleaned and prepared for the insertion of the insert part without external, in particular manual, intervention being necessary. If too much powder has been removed, e.g. from adjacent areas, powder could be supplemented by an application device arranged on a robot articulated arm, as described above.

[0037] According to one process variant, before the insert part is inserted into the recess, an adhesive is applied to bond the insert part to the recess using an adhesive device mounted on a robotic articulated arm. The adhesive serves to firmly bond the insert part to the recess and can be applied to the insert part and / or into the recess. The adhesive device typically has some kind of nozzle for dispensing the adhesive.

[0038] Particularly when the insert part is to be received in the recess in a form-fitting manner and the matrix is ​​to a certain extent produced around the insert part, it is preferred that the insertion of the insert part during the production process also takes place without external intervention. The insert part is therefore preferably inserted into the recess by an articulated robot arm on which a holding device is arranged. This means that the articulated robot arm grips the insert part, which can be provided in a storage area, for example, by means of the holding device, transfers it to the recess and inserts it therein. The holding device can be designed as a gripper, as a switchable magnet or in another way, depending on the type of insert part.

[0039] When reference is made to “a robot articulated arm” in connection with the application device, the cleaning device and the holding device, the statements made in connection with the sensor device apply accordingly, i.e. the respective robot articulated arm can be designed in the same or a similar way. If several devices are used, a separate robot articulated arm can be used for each device. Alternatively, two devices selected from the sensor device, the secondary application device, the cleaning device and the holding device (and optionally the adhesive device) can be guided by the same robot articulated arm. In principle, two alternatives are conceivable. According to a first alternative, at least two devices are permanently arranged on the robot articulated arm.This has the advantage that the respective device can be permanently mounted and thus its position on the robot articulated arm can be easily determined with a high degree of accuracy. For example, permanent mounting on the robot articulated arm is preferred for the sensor device, since even the slightest misalignment could significantly influence the measurement results. According to a second alternative, at least two devices can be alternatively coupled to the robot articulated arm. This means that the devices essentially form modules that can be used as required. It is of course preferred that the robot articulated arm can automatically connect and disconnect the modules. This alternative has the advantage that the end of the robot articulated arm can be comparatively light, since only one device needs to be guided at a time. Furthermore, there is no problem that the devices could interfere with each other's function.

[0040] Further advantageous details and effects of the invention are explained in more detail below with reference to exemplary embodiments shown in the figures. Fig. 1 a schematic representation of a first method step of a first embodiment of the method according to the invention; Fig. 2 a schematic representation of a second process step; Fig. 3 a schematic representation of a third process step; Fig. 4 a schematic representation of a fourth process step; Fig. 5 a schematic representation of a first method step of a second embodiment of the method according to the invention; Fig. 6 a schematic representation of a second process step; Fig. 7 a schematic representation of a third process step; and Fig. 8 a schematic representation of a fourth process step.

[0041] In the different figures, identical parts are always provided with the same reference symbols, which is why they are usually only described once.

[0042] Fig. 1 shows a production plant 1 with which the method according to the invention can be carried out.

[0043] A construction platform 21 is arranged on vertically adjustable supports 2, on which an object 19 is produced by additive manufacturing. For this purpose, as shown in Fig. 4, metallic powder 17 is applied layer by layer along a horizontal build surface A onto the build platform 21 by a first application device 3. The first application device 3 can have a type of nozzle or valve for powder dispensing as well as a smoothing device, e.g. a squeegee. As shown by the double arrow, the first application device 3 can be moved parallel to the build surface A in order to distribute powder 17 along the entire build surface A. Side walls 5 adjoin both sides of the build platform 21, which prevent powder 17 from trickling off to the sides. To prevent oxidation or even an explosion of the powder 17, the entire production system 1 is arranged in a housing 16 that is filled with inert gas or into which inert gas is continuously blown, whereby the oxygen content is kept low. The laser 8 or the energy source is not necessarily arranged within the housing 16.

[0044] For proper application of the powder 17, the build surface A must be parallel to the surface of the build platform 21. As shown in Fig. 1 and Fig. 2, the construction platform 21 in the present case, however, has an inclination relative to the horizontal H and thus relative to the construction surface A. In order to detect such errors, the production system 1 has a robot articulated arm 6, on which a tactile sensor 7 is arranged at the end. The robot articulated arm 6 is arranged within the housing 16 and can - as schematically indicated - be pivotally attached thereto. The joints of the robot articulated arm are shown in a simplified manner in the figures, and in reality, it can be capable of positioning the tactile sensor 7 as desired with regard to all six degrees of freedom. As shown in Fig. 1 and Fig. As shown in Figure 2, the tactile sensor 7 is moved by the robotic articulated arm 6 to two different points on the surface of the construction platform 21, one could also say, to two different measuring positions. By determining the coordinates of these points, the vertical alignment of the construction platform 21 and an angle of inclination relative to the horizontal H can be determined. By detecting three or more points, two angles of inclination can also be detected. The necessary evaluation of the measured data can be carried out by an evaluation and control unit (not shown here), which, based on the detected inclination, controls the supports 2 in the opposite direction in order to eliminate the inclination. This process is described in Fig. 3 is indicated by arrows on the respective support 2, wherein the construction platform 21 is already in a horizontal position, while the robot articulated arm 6 has been moved into a standby position in which it does not disturb the movement sequence of the first application device 3.

[0045] Then begins, as in Fig. 4 illustrates the layer-by-layer application of the metallic powder 17. Once the application device 3, which is connected to a storage container (not shown) via a feed line 4, has applied a layer of powder 17, a portion of the powder 17 is selectively melted by means of a laser beam 10, whereby the powder 17 is combined to form a matrix 18 and a layer of an object 19 to be manufactured is produced. The laser beam 10 is generated by a laser 8 and directed via a pivoting mirror 9 to a predetermined coordinate point within the build surface A. In the figures, the mirror 9 or the scanner system is shown in a very simplified manner. Of course, an arrangement inside or outside the housing 16 is possible. The activation of the laser 8 and the control of the mirror 9 are computer-controlled according to predetermined CAM data of the object 19.The supports 2 lower the build platform 21 along a transport direction T (which here runs parallel to the vertical V). In the present example, they are operated intermittently, i.e., they are stopped while a powder layer is applied and partially melted, and then transport the build platform 21 with the object 19 along the transport direction T away from the build surface A by a distance corresponding to the intended layer thickness. After the layer-by-layer build of the object 19 is completed, the loose powder is removed from the build platform 21, and the finished object 19 is separated.

[0046] In the embodiment in Fig. 1 - 4, the construction takes place on a base 20 which is formed exclusively by the construction platform 21. Fig. 5 - 8 show another embodiment in which a hybrid process is used. As in Fig. 1, a prefabricated base body 22 is arranged on the construction platform 21, to which further structures are added by means of additive manufacturing. The construction platform 21 and the base body 22 together form a base 20 onto which the powder 17 is applied. To ensure proper construction, the position of the base body 22 is first checked by the robotic articulated arm 6 with the tactile sensor 7 taking at least one measurement on the base body 22, as shown in Fig. 5. Normally, a number of measurements are taken, whereby, for example, the inclination of the base body 22 can be determined. If it is determined that the position needs to be corrected, the supports 2 are again controlled accordingly. Of course, under certain circumstances, alternatively or additionally, as in Fig. 1 and Fig. 2, the position of the construction platform 21 can be checked.

[0047] In order to enable a layer-by-layer application of the metallic powder 17 in the further course of the process, the areas arranged laterally of the base body 22 must be filled with powder 17. This is difficult to achieve with the first application device 3, since it is designed to apply thin layers along the construction surface A, being moved back and forth in an oscillating manner. To make the process more efficient, as shown in Fig. 6, a second application device 11, which is arranged at the end of a robotic articulated arm 6, can be used. This can, for example, also be guided specifically to or even into undercut areas near the base body 22 in order to add powder 17 there. After the lateral areas have been filled with powder 17, the further construction of the object 19 can take place by fusing the metallic powder 17 into a matrix 18.

[0048] Fig. 7 shows a further method step at a later stage of the manufacturing process, wherein a matrix 18 of considerable thickness has already been built onto the base body 22. In the present case, an insert part 15 (e.g., a sensor or the like), which cannot be additively manufactured, is to be integrated into the object 19. For this purpose, a recess 19.1 is provided, within which the powder 17 is not fused. In order to be able to place the insert part 15 there, however, the loose powder 17 must first be removed from the recess 19.1. This can be done using a suction device 12 serving as a cleaning device, which in turn is arranged on a robot articulated arm 6. The suction device 12 is connected via a suction line 13 to a vacuum source (not shown). Due to the mobility of the robot articulated arm 6, almost any area can be cleaned with the suction device 12.

[0049] Fig. Figure 8 shows a further process step after the recess 19.1 has been cleaned of loose powder 17. The insert part 15, which may previously have been stored, for example, in a storage area within the housing 16, is grasped by a gripper 14 arranged on a robot articulated arm 6, transferred to the recess 19.1, and inserted therein. The layer-by-layer construction of the object 19 can then be continued. During the cleaning of the recess 19.1 ( Fig. 7) and the insertion of the insert part 15 ( Fig. 8), both the application device 3 and the laser 8 can be temporarily switched off (as indicated in the figures). However, under certain circumstances, these steps can also be coordinated with the application of the powder 17 and its melting into the matrix 18, thereby enabling further time savings.

[0050] According to a process variant not shown here, an adhesive can be applied before inserting the insert part 15 into the recess 19.1, specifically by an adhesive device arranged on a robot articulated arm 6. The adhesive creates a connection between the insert part and the recess. The adhesive is normally applied into the recess 19.1, but alternatively or additionally, it can also be applied to the insert part 15. The adhesive device typically has a type of nozzle for dispensing the adhesive.

[0051] In Fig. 5 - 8, different devices 7, 11, 12, 14 are shown on a similarly designed robot articulated arm 6. The actual design and arrangement of the corresponding elements may differ from the representation chosen here. For example, several robot articulated arms 6 can be provided, each of which carries one of the devices 7, 11, 12, 14. It may also be possible for several devices 7, 11, 12, 14 to be permanently arranged on one and the same robot articulated arm 6. Finally, it is possible for a single robot articulated arm 6 to alternatively couple different devices 7, 11, 12, 14 to the ends in order to use them as needed. The coupling and uncoupling of the corresponding devices 7, 11, 12, 14 preferably takes place fully automatically within the housing 16. The options mentioned also relate to the optional adhesive device (not shown).

[0052] All in Fig.The process steps illustrated in Figures 1-8 (as well as the optional application of adhesive) can be performed fully automatically, without requiring manual intervention or opening of the housing 16. This makes the process shown fast and efficient, while also preventing contamination of the powder 17, particularly oxidation or even combustion. List of reference symbols 1 production facility 2 supports 3, 11 Application device 4 Supply line 5 Side wall 6 Robot articulated arm 7 tactile sensor 8 lasers 9 mirrors 10 laser beam 12 Suction device 13 Suction line 14 grippers 15 insert part 16 housings 17 metallic powder 18 Matrix 19 objects 19.1 Recess 20 Base 21 Construction platform 22 basic bodies A construction area V Vertical H Horizontal T Transport direction

Claims

[1] Additive manufacturing method, wherein an object (19) is manufactured by applying powder (17) layer by layer on a base (20) along a construction surface (A) by an application device (3, 11) and connecting said powder in regions to form a matrix (18), wherein a position of the base (20) is checked by at least one measurement by means of a sensor device (7) designed as a tactile sensor (7) and the position is automatically corrected at least relative to the application device (3, 11) depending on the at least one measurement, characterized byin that the sensor device (7) is arranged on a robot articulated arm (6), by means of which it is moved into a measuring position for the respective measurement, and at least one measurement is carried out on a prefabricated base body (22) which is arranged on a construction platform (21) from which the object (19) is removed after its completion, and which remains connected to the matrix (18) as part of the finished object (19). [2] Additive manufacturing process according to claim 1, characterized by that at least one angle of inclination of the base (20) is automatically corrected as a function of the at least one measurement. [3] Additive manufacturing process according to one of the preceding claims, characterized by that the production of the object (19) is carried out in an inert gas atmosphere. [4] Additive manufacturing process according to one of the preceding claims, characterized by that at least one measurement is carried out on the construction platform (21). [5] Additive manufacturing process according to one of the preceding claims, characterized by that powder (17) is applied to the construction platform (21) next to the base body (22) by an application device (3, 11) which is arranged on a robot articulated arm (6). [6] Additive manufacturing process according to one of the preceding claims, characterized by that a recess (19.1) for receiving an insert part (15) is created within the object (19) by not bonding powder (17) in an area provided for the recess (19.1) and this powder (17) is subsequently removed by a cleaning device (12) arranged on a robot articulated arm (6). [7] Additive manufacturing process according to one of the preceding claims, characterized by that the insert part (15) is inserted into the recess (19.1) by a robot articulated arm (6) on which a holding device (14) is arranged. [8] Additive manufacturing process according to one of the preceding claims, characterized by that at least two devices selected from the sensor device (7), the application device (11), the cleaning device (12) and the holding device (14) are guided by the same robot articulated arm (6).

Images