How to influence a structural part or group of structures in a 3D printer

Abstract

The present invention relates to a method for influencing a structural part or a group of structures in a 3D printer (1), and the object of the present invention is to provide a method for influencing a structural part or a group of structures in a 3D printer, whereby an automatic readjustment or altered control of the structural part or a group of structures in the 3D printer is achieved. [Solution] This problem is solved by the following process steps (15): control data (8) comprising parameters according to which the generation of a 3D structure (10) in a 3D printer (1) is controlled are generated from input data (9), generating the 3D structure (10), measuring the generated 3D structure (10), determining actual dimensions of the generated 3D structure (10) and storing them as data, comparing the input data (9) comprising said predefined dimensions with the data of the actual dimensions and determining differences, and modifying at least one parameter of the control data (8) if such differences are determined or if such differences exceed predefined tolerance thresholds.

Description

[Technical field]

[0001] The present invention relates to a method for influencing a structural part or a group of structures in a 3D printer, whereby deviations from a 3D structure generated in the 3D printer are determined and subsequently the structural part or group of structures is influenced in the 3D printer. [Background technology]

[0002] Here, the term affecting a structure or structures in a 3D printer is understood to mean, for example, both a re-adjustment of a structure or structures in a 3D printer and a change in the control of a structure or structures in a 3D printer, for example, a parameter for controlling a structure or structures in a 3D printer, such as the time at which a nozzle in a print head of the 3D printer is activated, can be changed.

[0003] Furthermore, the speed of movement of the 3D printer's construction group moving over the surface of the construction area of ​​the 3D printer can also be changed. Such construction group can be a working device of the 3D printer, such as a means for discharging or applying particulate construction material, a means for smoothing the discharged particulate construction material, a means for compressing the particulate construction material, or a print head for applying a binder.

[0004] Additionally, the amount to be dispensed using the print head, e.g., the amount of binder, can be increased or decreased, or a cleaning process can be initiated, for example, if it is determined that a change in the binder dispensed is not producing the expected results.

[0005] The term influencing structural portions or groups also includes changes in the amount of particulate structural material applied to a structural area.

[0006] Additionally, the selection or number of nozzles to be used or not used in the printhead to which the binder is applied may be altered.

[0007] The invention notably provides a solution that makes it possible to realize automated influences on structural parts or groups of structures in a 3D printer.

[0008] For the production of individual or mass-produced parts, workpieces or moulds, it is known to use so-called 3D printing or so-called 3D printing methods, in which a three-dimensional part or workpiece is built up and produced layer by layer.

[0009] The construction is numerically controlled from one or more types of liquid or solid material according to predetermined dimensions and shapes. The reference dimensions of the parts or workpieces to be printed can be provided, for example, by so-called computer-aided design systems (CAD, English computer-aided design).

[0010] When printing a 3D structure or part, a physical or chemical hardening or melting process takes place in the particulate construction material, also called molding material. Materials used for this type of 3D printing process include construction or molding materials, such as unhardened precipitates of plastics, synthetic resins, ceramics, minerals or sand, and metals.

[0011] When implementing 3D printing, various manufacturing sequences are known.

[0012] However, some of these method sequences include the following exemplary method steps. applying a particulate construction material, also called particulate material or powdered building material, partially or fully onto the construction area to form a layer of unhardened particulate material, the partially or fully applying of the particulate construction material including draining and smoothing the particulate construction material. selectively hardening the applied layer of unhardened particulate structural material in predetermined partial areas, for example by selectively compressing, printing or applying a treatment such as a binder using a printer head or by using a laser, Building up a part or workpiece layer-by-layer by repetition of the previous method steps in another layer plane, for which it is provided that the part or workpiece which is built up or printed layer-by-layer on the construction area is lowered together with the construction area by one layer plane or layer thickness, respectively, or the 3D printing device is raised relative to the construction area by one layer plane or layer thickness, respectively, before the new layer is applied partially or completely. Subsequent removal of the unhardened, loose particulate structural material surrounding the manufactured part or workpiece.

[0013] Particulate construction materials are generally understood to be aggregates of individual particles of a substance or mixture, each particle having a three-dimensional extent. These particles can be mainly considered as round, ovoid or elongated particles, so that it is possible to show an average diameter of the particles, which is usually in the range of 0.1 mm to 0.4 mm. This type of particulate construction material can have the properties of a fluid.

[0014] In the prior art, various methods are known for discharging and applying particulate construction material onto a construction area to manufacture or create 3D structures.

[0015] From US Pat. No. 5,399,543 a method and device for applying a fluid and its uses are known.

[0016] The method of applying a fluid particularly relates to particulate material being applied to the area to be coated, in which, in front of the blade as seen in the direction of advancement of the blade, a fluid is applied to the area to be coated, and then the blade moves over the applied fluid.

[0017] The object is to provide an apparatus, a method and an arrangement with which it is possible to achieve a distribution of the fluid material as even as possible on the area to be coated.

[0018] A solution is envisaged in which the blade undergoes a certain kind of pivoting vibration, which causes the fluid applied to the area to be coated to be fluidised, thereby not only allowing the particulate material, which has a strong tendency to agglomerate, to be applied as evenly and smoothly as possible, but also making it possible to affect the compaction of the fluid by the vibration.

[0019] In a preferred embodiment, the application of the fluid to the area to be coated is carried out in excess, so that by the continuous movement of the blade, which oscillates like a kind of rotational movement, the excess of fluid is homogenized in front of the blade, seen in the forward movement direction of the blade, in a roll formed by the forward movement of the blade from the fluid or particulate material, whereby any voids between the individual particulate aggregates that may arise are filled and the particulate material of the larger aggregates can be broken up by the roll movement.

[0020] A drawback of these known prior art techniques is that there is usually no testing or quality checking of the generated 3D structures for deviations from predetermined dimensions.

[0021] If a quality inspection of the generated 3D structure is performed, for example, by measuring the generated 3D structure, detected deviations from predetermined dimensions of the 3D structure can usually only be corrected by mechanically readjusting structural parts or structural groups of the 3D printer.

[0022] However, such mechanical readjustments are often complicated, since they require, for example, partial disassembly of the 3D printer in order to reach the structure or structures to be adjusted, and in addition, such readjustments also stop the 3D printer, i.e. interrupt the production of the 3D structure in the 3D printer.

[0023] This is particularly disadvantageous in fields where very tight tolerances are applied in the manufacture of 3D structures, for example with a given maximum deviation between +0.3 mm and -0.3 mm. Thus, for example, the length of the manufactured 3D structure may be up to 0.3 mm longer or shorter in order to fit the given narrow tolerance.

[0024] In patent document 2, a system and method for improved additive manufacturing are known. During manufacturing, problems may occur in producing a 3D object based on multiple factors, which may result in the 3D object becoming unusable. To avoid such problems, a device is provided that communicates directly or indirectly with one or more additive manufacturing machines using one or more building parameters. The device is configured to analyze multiple building information regarding the part or 3D object. The device is also configured to check whether one or more differences between existing data and data other than the existing data result in a deviation or improvement of the 3D object. In addition, one or more building parameters of the 3D object can be automatically modified as a result of the tests performed.

[0025] US Pat. No. 5,399,433 discloses a method for imaging at least one three-dimensional part manufactured by a generative manufacturing process. US Pat. No. 5,399,433 also relates to an apparatus for implementing such a method. The problem of this document is to provide a method for imaging at least one part manufactured by a generative manufacturing process, which method allows an improved assessment of the quality of the manufactured part. Another problem is to provide a suitable apparatus for implementing this method.

[0026] One embodiment of a method for imaging at least one three-dimensional part manufactured by generative manufacturing comprises at least the following steps: determining at least two layer images of the part during its production by a detection device configured to ascertain in a spatially resolved manner a measurement variable characterizing the energy input into the part; generating, by a computing device, a three-dimensional image of the part based on the determined layer images; displaying the image by a display device; Includes.

[0027] The method therefore makes it possible to know in a spatially resolved manner the energy input into a part during its manufacture. The part may for example be a part for a thermal gas turbine, an aircraft engine, etc.

[0028] US Patent No. 5,999,943 discloses a system, apparatus, and method for monitoring a three-dimensional printing process. The three-dimensional printing process can be monitored in-situ and / or in real-time. The monitoring of the three-dimensional printing process may be performed non-intrusively. A computer control system can be coupled to one or more detectors and a signal processing unit to control the generation of the three-dimensional object being formed by the three-dimensional printing.

[0029] US Patent No. 5,399,633 discloses a method for in-process inspection of 3D printed parts in a 3D printer that is a filament extrusion printer. For substantially every shell volume, a tool path can be generated for depositing a printing material shell corresponding to the shell volume. The tool path defining the printing material shell can be transferred with an identification for application by the 3D printer. In another aspect, a method for in-process printing calibration of a 3D printer can include mounting a distance measuring scanner on a shared carriage with the printing material deposition head.

[0030] Thus, according to the prior art, there are no sufficiently accurate and effective possibilities for proper quality inspection or quality assurance during the production of 3D structures.

[0031] Therefore, there is a need for improvements over the known prior art and thus an improved method for influencing a structure or structures of a 3D printer. [Prior art documents] [Patent documents]

[0032] [Patent Document 1] German Patent No. 10117875 [Patent Document 2] DE 102018115432 [Patent Document 3] US Patent Application Publication No. 2013 / 314504 [Patent Document 4] International Publication No. 2016 / 094827 [Patent Document 5] US Patent Application Publication No. 2019 / 009472 Summary of the Invention [Problem to be solved by the invention]

[0033] The object of the present invention is to provide a method for influencing a structural part or a group of structures in a 3D printer, whereby an automatic readjustment or altered control of the structural part or group of structures in the 3D printer is achieved. The method also reduces the downtime of the 3D printer and improves the quality of the generated 3D structure. [Means for solving the problem]

[0034] This problem is solved by a method for influencing structural parts or structural groups of a 3D printer having the features of independent claim 1. Developments are given in the dependent claims.

[0035] According to the prior art, a 3D structure generated in a 3D printer can be measured after generation in the 3D printer to determine the deviation between the predetermined dimensions of the 3D structure and the dimensions generated by the 3D printer of the 3D structure. Such deviation represents the difference between the data of the dimensions of the 3D structure to be generated, generated for example by a computer-aided design system, and the actual dimensions of the 3D structure to be generated.

[0036] Such sources of difference could be, for example, the mechanical tolerances of the 3D printer, or even caused by variations in the quality of the construction material on the particles, which may have agglomerates or "gaps" due to uneven compression.

[0037] In addition, one or more clogged nozzles in the print head that is supposed to apply the binder can lead to differences between the dimensions. Warping of the 3D structure during curing or drying, or improper cleaning of the 3D structure after fabrication can also cause differences between the dimensions.

[0038] When measuring the generated 3D structure, for example the dimensions of the external or internal contour of the 3D structure can be determined using conventional measuring devices and methods known from the prior art. Such measurements may be performed over one or more dimensions of the generated 3D structure, such as its height, its width, and its length.

[0039] According to the prior art, for example, several measurements or dimensions are determined and noted in the form of a predefined table. These dimensions of the generated 3D structure, noted in the predefined table, are then compared with comparative or reference dimensions. Such reference dimensions correspond, for example, to predefined dimensions of a computer-aided design system.

[0040] In some cases, such determined dimensions and reference dimensions may be so-called 3D data, which are also checked for deviations from one another.

[0041] Such a comparison of a certain number of, for example, actual dimensions with reference dimensions can be performed by an appropriately qualified operator of the 3D printer, who must then determine, for example, whether the difference between these dimensions exceeds a certain tolerance, while adhering to known tolerance limits, and whether the required quality of the generated 3D structure has been achieved.

[0042] If this required quality is not achieved, appropriate measures must be taken to readjust the structural part or groups of structures within the 3D printer in order to accommodate the given quality requirements.

[0043] The disadvantage of this method known from the prior art is that this comparison or evaluation of the dimensions by the operator can lead to erroneous interpretations, as a result of which the 3D printer is stopped, dismantled, inspected or newly adjusted, even though there is no need for readjustment.

[0044] Thus, the method contemplates that the comparison of a constant actual dimension with a reference dimension is performed automatically, regardless of whether each dimension is a single value, such as height, width, or length, or whether the dimension is in the form of three-dimensional data. For example, such three-dimensional data has values ​​such as X, Y, and Z components in a three-dimensional coordinate system, starting from a reference point or reference coordinate system. For example, a specific point on the surface of a generated 3D structure can be described by specifying the 3D data, i.e., X, Y, and Z components.

[0045] This automatic comparison of the constant actual and reference dimensions determines the respective difference between the compared dimensions, which may be a positive or negative deviation.

[0046] The automatic comparison can also be performed taking into account predefined tolerances or tolerance limits. These tolerances or tolerance limits can also be predefined for positive and negative deviations. In one variant, these tolerance limits for positive deviations are of the same magnitude as the tolerance limits for negative deviations. In an alternative variant, these tolerance limits for positive deviations are not of the same magnitude as the tolerance limits for negative deviations. In this way, different conditions can be applied, for example, for so-called oversizes and for so-called undersizes, in order to correspond to predefined quality specifications.

[0047] The method further contemplates eliminating the detected deviation or the detected deviation that is beyond a predetermined tolerance limit by automatically influencing or readjusting a structural part or structures of the 3D printer.

[0048] It is contemplated that a reconditioning can be, for example, a mechanical change in the position or location or orientation of a structural part or group of structures.

[0049] For this reason, 3D printers must be equipped with suitable options for automatic realignment, in which case, for example, the position and / or orientation of the print head of the 3D printer can be realigned.

[0050] It is further contemplated that the thickness of the layer of particulate build material to be applied is changed or the amount of binder to be dispensed using the print head is increased or decreased in order to eliminate deviations beyond a given tolerance limit. The composition of the particulate build material or binder can also be changed. As an alternative to these measures, cleaning or intermediate cleaning of the print head can reduce the deviations that occur.

[0051] Alternatively, it is contemplated that no mechanical alteration of the position, location, or orientation of a structural part or group is made, but instead data generated by, for example, a computer-aided design system for generating a 3D structure is influenced.

[0052] For example, the time at which the nozzle of the print head is activated, i.e., the parameter of the control time, can be changed. If the print head is moved uniformly over the surface of the structure area at a constant distance from the surface of the structure area, the position at which the binder droplet ejected from this nozzle collides with the surface of the structure area varies depending on the time at which the nozzle of the print head is activated. In this way, by changing the parameter of the control time, the necessary readjustment of the dimensional accuracy of the generated 3D structure can be performed.

[0053] Thus, deviations detected according to the method or deviations exceeding predetermined tolerance limits result in a shift in the control points, which are parameters of one or more nozzles of one or more printheads of the 3D printer, to reduce or eliminate the deviations.

[0054] In addition to affecting the parameter control time, also contemplated is variation of the parameter speed at which a structure or group of structures, such as a print head, moves over the surface of the structured area.

[0055] In other cases, both the effect on the control point in time, which is a parameter, and the change in the speed of the printhead may be contemplated.

[0056] Another possibility is to change the selection of nozzles used in the print head, for example by switching nozzles on or off to increase, decrease or move the effective width when the print head is used to apply binder to particulate structure material on the structure area.

[0057] In order to determine the actual dimensions of the generated 3D structure, it is envisaged to carry this out by means of a three-dimensional measurement or a three-dimensional scan, whereby the data required for the comparison of the actual dimensions of the generated 3D structure with the predefined dimensions, i.e. the reference dimensions, are generated in the form of three-dimensional 3D data.

[0058] This provided 3D data (indicating the actual dimensions of the generated 3D structure at a selected point on the surface of the 3D structure) is compared with predefined or reference dimensions also present as 3D data, and thus the difference between the actual dimensions and the reference dimensions is determined.

[0059] Knowing the actual dimensions of the generated 3D structure using a three-dimensional scan offers the possibility of automatically generating the data digitally and thus immediately transferring it to a program that executes the current method. This program also realizes a dimensional comparison in digital form. The program monitors predefined tolerances during this comparison and outputs an error only if they are outside the predefined tolerances. Based on these detected errors, the control points, which are parameters of one or more nozzles of one print head or of several print heads, are modified in order to reduce or eliminate detected differences or deviations at specific points on the surface of the generated 3D structure.

[0060] The program implementing the method is executed, for example, in a central control unit of a 3D printer. This central control unit also controls the process of generating the 3D structure based on transferred data on the dimensions of the 3D structure to be generated. Such data can be generated, for example, by a computer-aided design system and transferred to the central control unit. Thus, the central control unit uses or generates parameters for controlling the 3D printer, for example parameters of the control time of the nozzle or parameters of the movement speed of the structure group over the construction area. Thus, for example, a control time point, which is a parameter of the nozzle, can be influenced by the central control unit. The control time point of this parameter of the nozzle can be shifted in time by the central control unit compared to its predefined value of the control time point, so that the shifted control time point is before or after the predefined value of the control time point. The direction of this shift depends on the direction of the determined deviation of the dimensions.

[0061] It is contemplated that some or all of the 3D structures created will be measured by three-dimensional measurements or by using a 3D scan, as opposed to a single scan, to determine whether any errors or excessive deviations that occur were single random errors or systematic deviations.

[0062] In this way, for example, if a one-off error or a one-off too-large deviation occurs, a different error process can be initiated than if a systematic error or too-large deviation occurs.

[0063] For example, parameters such as the firing times of the nozzles of a printhead may be changed only if systematic errors occur.

[0064] It is also contemplated that in the event of systematic errors, an averaging of the detected deviations is carried out and parameters such as the control points of the printhead nozzles are automatically modified based on this determined average value.

[0065] The foregoing features and advantages of the present invention will be better understood and appreciated upon careful consideration of the following detailed description of the presently preferred, non-limiting, exemplary embodiments of the invention, taken in conjunction with the accompanying drawings. [Brief description of the drawings]

[0066] [Figure 1] 1 shows a schematic diagram of an embodiment of the present invention. [Diagram 2] 1 shows a diagram of the basic sequence of the method. [Figure 3a] A comparison of the 3D structures generated by the 3D printer with the relevant standards is shown. [Figure 3b] A comparison of the 3D structures generated by the 3D printer with the relevant standards is shown. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0067] A schematic diagram of an embodiment of the present invention is shown in FIG.

[0068] The 3D printer 1, which is only basically depicted, has a construction area 2. In the construction area 2 there is a particulate construction material 3 in loose form and, in a partial area, a selectively solidified form 4 of the particulate construction material 3. The 3D structure is generated in this partial area, where the particulate construction material 3 is present in solidified form 4.

[0069] Above the construction area 2, a working implement 5 of the 3D printer is moved, for example, in a depicted movement direction 6 at regular intervals up to the surface of the construction area 2. Such a working implement 5 of the 3D printer may, for example, be a means for discharging or applying a particulate construction material 3, a means for smoothing the conveyed particulate construction material 3, a means for compressing the particulate construction material 3 or a print head for applying a binder.

[0070] At least one print head having at least one nozzle is arranged in the area of ​​the working device 5, by means of which droplets of a binder for selectively solidifying, for example, the particulate construction material 3 are applied or dispensed onto the surface of the construction area 2.

[0071] A central control unit 7 controls all operation sequences in the 3D printer 1 and transmits control data 8 to the working implement 5 for generating the 3D structure 10. This control data 8 also contains parameters that determine, for example, the movement speed of the working implement 5 in an exemplary movement direction 6 or the control times of the nozzles of the print head of the working implement 5.

[0072] To generate the 3D structure 10, input data 9 describing, for example, the dimensions of the 3D structure 10 to be generated are sent to the central control unit 7. This input data 9 may also describe or include, for each layer of the 3D structure 10 to be generated, the dimensions of the 3D structure 10 to be generated. Using this input data 9, the central control unit 7 generates control data 8 with its parameters.

[0073] This can be done, for example, by using a three-dimensional scanning assembly 11, after the 3D structure 10 has been generated, to obtain data on the actual dimensions of the generated 3D structure. This measurement can be done, for example, by using a three-dimensional scanning assembly 11. For this purpose, the 3D scanning assembly 11 can for example have multiple sensors 12 which scan the generated 3D structure 10 from multiple directions, thus generating 3D data 13 for individual points on the surface of the generated 3D structure 10. This 3D data 13 is transmitted to the central controller 7.

[0074] In the central control unit 7, the default or input data 9 is compared with the 3D data 13 generated in the scan. Thus, deviations between the predetermined dimensions for the 3D structure to be generated and the dimensions (generated by the 3D printer) of the generated 3D structure are determined. Such deviations represent the difference between the input data 9 generated by the computer-aided design system and the 3D data 13 generated in the scan of the actual dimensions of the generated 3D structure.

[0075] Based on the difference thus determined, it is possible, for example, to change the control instant of the nozzle of the print head in the 3D printer 1. By shifting the control instant of the nozzle in time, the partial areas in which the particulate construction material 3 is present in selectively solidified form 4 on the construction area 2 are changed or shifted. This shift also changes the dimensions of the internal or external contour of the 3D structure to be generated.

[0076] In this way, methodical influence on structural parts or groups of structures within the 3D printer is achieved in order to improve the accuracy of the 3D structure 10 to be produced.

[0077] During this process, a certain tolerance for the allowed difference or deviation can also be observed. For example, a movement of the control point of the nozzle is only contemplated if it exceeds the allowed tolerance or falls below the allowed tolerance. Different tolerances for different directions of the difference or deviation can also be taken into account here. For example, a different tolerance can be provided for oversize than for undersize.

[0078] FIG. 2 shows a diagram of the basic sequence of the method.

[0079] After the start of the method in step 14, the generation of the control data 8 with its parameters from the input data 9 is carried out in a subsequent process step 15. This generation of the control data 8 is carried out by a central control unit 7, which is not depicted in Fig. 2. The control data 8 thus generated is transmitted to the operating device 5 of the 3D printer 1.

[0080] This control data 8 is used to generate a 3D structure 10 in the 3D printer 1. The 3D printer 1, the control data 8, and the 3D structure 10 are not depicted in FIG.

[0081] In the next comparison 16 or comparison step 16, if the 3D structure 10 in the 3D printer 1 has not yet been generated, there is no change in the parameters or control data 8.

[0082] Then, in step 17, a 3D structure is generated.

[0083] In step 18, a three-dimensional measurement of the generated 3D structure 10 is performed. Such a measurement can be performed using methods known from the prior art, which can generate corresponding measurement data, which can be transmitted to the central control unit 7, for example as 3D data 13.

[0084] In the example of Figure 1, a three-dimensional scan is used to perform three-dimensional measurements. Such measurements generate corresponding 3D data 13, which are returned in step 16.

[0085] In step 19, the generation and measurement of the generated 3D structures is completed and the method ends in step 20. Alternatively, the method can be performed several times to generate several 3D structures in succession. The corresponding return to the start of this method is not depicted in FIG. 2.

[0086] If the corresponding 3D data 13 is returned in step 16, a comparison is made in step 16. During this comparison, the deviation between the predefined dimensions and the actual dimensions of the 3D structure 10 produced by the 3D printer is determined and stored as a difference or deviation. In such a comparison, data of the predefined dimensions is compared with data of the actual dimensions.

[0087] If the difference or deviation determined during this comparison exceeds a predetermined tolerance, at least one parameter of the control data 8 is modified in step 16 in order to reduce or eliminate the detected deviation. Such a parameter is, for example, the time at which the nozzles in the printhead that apply the binder are activated, although several times for several nozzles can also be modified.

[0088] Alternatively, if a deviation is detected between the predetermined dimensions and the actual dimensions of the 3D structure 10 produced by the 3D printer, at least one parameter of the control data 8 can be modified in step 16, without taking into account the tolerances, in order to reduce or eliminate the detected deviation.

[0089] In this case, in step 17 a further 3D structure is generated taking into account the control data 8 adjusted or modified in the comparison 16 and its adjusted or modified parameters.

[0090] 3a and 3b respectively depict at least a 3D structure 10 produced by three-dimensional printing and associated fiducials 21 in comparison with their external dimensions, with FIG. 3a showing a perspective view and FIG. 3b showing a top view.

[0091] The criterion 21 is the 3D structure that should be produced by the process of producing the 3D structure in a 3D printer, without any deviation from given dimensions.

[0092] The generated 3D structure 10 is the result of generating a 3D structure on a 3D printer and may have undesirable manufacturing related deviations from the predetermined dimensions.

[0093] Alternatively, the fiducial 21 can be understood as a data set or simply as data of predetermined dimensions for the 3D structure to be generated. For the purposes of the method and the comparison of data or 3D data, the fiducial 21 does not need to be physically present.

[0094] As can be seen in the example of FIG. 3a, the generated 3D structure 10 has a three-dimensional extension, where the depicted X-direction extension of the structure 10 is referred to as its length, the depicted Y-direction extension as its width, and the depicted Z-direction extension as its height.

[0095] In Fig. 3a, a basic diagram of the generated 3D structure 10 is shown with its associated fiducials 21. This is to illustrate that deviations occur due to manufacturing tolerances, which can only occur in one, two or all three dimensions.

[0096] Tolerance thresholds for the allowed deviations are set, as depicted with several dotted lines in Fig. 3b. These tolerance thresholds for positive and negative deviations can be, for example, +0.3mm and -0.3mm, as depicted in Fig. 3b, with no restrictions placed on either the value or symmetry of the deviations.

[0097] For example, if the generated 3D structure 10 has an oversize in its length in the X direction, this deviation may be up to +0.3 mm if predefined tolerance limits are used, otherwise the length of the generated 3D structure 10 is not within the predefined tolerance limits.

[0098] When predetermined tolerance limits are not used, each difference determined between the predetermined dimensions and the actual dimensions of the 3D structure 10 generated by the 3D printer is considered as a deviation to be corrected, and it is intended to modify at least one parameter of the control data 8 in order to reduce or eliminate such determined difference for the 3D structure 10 subsequently generated.

[0099] If the generated 3D structure 10 has an undersize, for example in the X-direction, in its length, this deviation may be up to -0.3 mm, otherwise the length of the generated 3D structure 10 does not fall within the predetermined tolerance threshold.

[0100] For example, if a tolerance threshold for the length of the generated 3D structure 10 exceeds a maximum of +0.3 mm, as depicted as deviation 22a in the left part of Fig. 3b, at least one parameter of the control data 8 is modified according to the method, such that the modification of this parameter is performed such that the difference in the 3D structure 10 to be subsequently generated is reduced or eliminated.

[0101] The deviation 22a is shown as a point on the left edge of the body of the generated 3D structure 10 depicted in Fig. 3b, because the method allows the comparison of the data or 3D data to be performed point-by-point. In this way, for example, various deviations on the left edge of the body of the 3D structure 10, which are not depicted in Fig. 3b, can be recognized point-by-point, processed point-by-point and corrected differently for each point.

[0102] A simplification of this method may be that only one point of a deviation, such as deviation 22a, or an average value formed from two, three or four deviations found at the left end of the body, is used to modify at least one parameter according to this method.

[0103] In the example of Fig. 3b, the time at which the nozzle of the print head is activated, i.e. the control time of the parameters of the nozzle, can be changed. In Fig. 3b, it is assumed that the print head (not shown) which applies the binder moves from left to right over the construction area during the generation of the 3D structure 10 and has a nozzle associated with the deviation 22a. In the case of Fig. 3b, if a later time is selected as the time at which the corresponding nozzle of the print head is activated, the left edge of the body or the deviation 22a in Fig. 3b is shifted to the right. This reduces the deviation 22a. In the case of a corresponding shift in the control time of the nozzle, not depicted in Fig. 3b, for example, the left edge of the body falls within the predetermined tolerance threshold with a deviation of +0.2 mm, so that the deviation 22a does not occur.

[0104] In addition, if deviations of points or body edges of the generated 3D structure 10 are within the tolerance threshold or are at some limit of the tolerance threshold, for example at +0.3 mm, a competent person may undertake to make changes in at least one parameter independent of the method.

[0105] Additionally, it is contemplated in the method that the comparison of the 3D printed 3D structure 10 with the associated reference 21 is performed layer by layer as the 3D structure is generated layer by layer. In this way, various deviations at different layers can be recognized and reduced or eliminated according to the method.

[0106] The difference in deviations in different layers during the creation of the three-dimensional structure 10 can be caused, for example, by the fact that the particulate construction material or a binder for selectively solidifying the particulate construction material is applied in different movement directions of the working implement of the 3D printer, for example when the particulate construction material and / or the binder is applied both in a first movement direction of the working implement of the 3D printer over the construction area and in a second movement direction of the working implement of the 3D printer over the construction area, the second movement direction being directed opposite to the first movement direction.

[0107] As a further example of the difference in dimensions of the 3D structure 10 generated in the 3D printer and the associated fiducials 21, a deviation 22b is shown in FIG. 3b by way of example. In this case, it is below the acceptable tolerance threshold of −0.3 mm for the width of the generated 3D structure 10. In this case too, a change in at least one parameter according to the method is carried out in order to shift the deviation 22b of the 3D structure 10 in FIG. 3b or the entire lower body edge and thus reduce or eliminate the difference for the 3D structure 10 to be generated thereafter. In this case, it may be envisaged that a nozzle of the print head that applies the binder is activated or switched on that was not previously used. This control of one or more additional nozzles increases the width of the 3D structure 10 to be generated and thus eliminates the undersizing that occurred in the width.

[0108] Switching the nozzles of the print head on or off for the 3D structure to be subsequently created is also a change in the control point in time of the nozzles when generating the 3D structure 10. [Explanation of symbols]

[0109] 1 3D printer 2 Structure area 3. Particulate structural materials 4. Selectively solidified forms of particulate structural materials 5. Working Equipment 6. Movement direction 7 Central control unit 8 Control Data / Parameters 9. Input Data 10 3D structures 11 3D Scanning Assembly 12 Sensors 13 3D Data 14 Start 15 Processing steps / control data generation 16 Comparison 17. Generating 3D Structures 18 Measurements 19 Manufacturing and measuring 3D structures 20 End 21 Standards 22a, 22b Deviation

Claims

Claim 1 A method for influencing a structural part or group of structural parts in a 3D printer (1), wherein in this method, a difference of a 3D structure (10) generated by the 3D printer (1) with respect to a predetermined dimension of this 3D structure (10) is determined, and subsequently the structural part or group of structural parts in the 3D printer (1) is influenced, in a processing step (15), control data (8) including parameters by which the generation of the 3D structure (10) in the 3D printer (1) is controlled is generated from input data (9) describing a predetermined dimension of the 3D structure (10) to be generated, and the 3D structure (10) is generated, after the 3D structure (10) is generated by the 3D printer (1), the 3D structure (10) is measured three-dimensionally to determine the actual dimensions of the generated 3D structure (10), and is stored as actual dimension data, the input data (9) including its predetermined dimension and the actual dimension data are compared, and a difference is determined, if such a difference is determined, or if such a difference exceeds a predetermined tolerance threshold, at least one parameter of the control data (8) is changed, this parameter is changed such that the difference with respect to the 3D structure (10) to be generated thereafter is reduced or eliminated, and subsequently, another 3D structure (10) is generated using at least one changed parameter of the control data (8), the parameters of the control data (8) are the control timing of the nozzles in the print head of the 3D printer (1), or the moving speed on the structural area (2) of the working device (5) of the 3D printer (1), the working device (5) of the 3D printer (1) is a means for discharging a particulate structural material (3), a means for smoothing the discharged particulate structural material (3), or a means for compressing the particulate structural material (3), A method characterized by the above. Claim 2 The method according to claim 1, characterized in that the input data (9) describes the predetermined dimension of the 3D structure (10) to be generated for each layer of the 3D structure (10) to be generated. Claim 3 The method according to claim 1 or 2, characterized in that the control data (8) produced in the processing step (15) controls the functional mode and operating mode of the working device (5). Claim 4 The measurement of the generated 3D structure (10) is performed by three-dimensional measurement, and 3D data (13) for a plurality of points on the surface of the generated 3D structure (10) is generated and stored. The method according to claim 1, characterized in that.

5. The comparison between the data of the predetermined dimension and the data of the actual dimension is performed as a comparison between the 3D data of the predetermined dimension and the 3D data of the actual dimension. The method according to claim 1, characterized in that.

6. The method according to claim 1, characterized in that the predetermined tolerance thresholds of the determined positive or negative differences are the same or different.

7. The method according to claim 1, characterized in that the predetermined tolerance threshold is in the range of +0.5 mm to -0.5 mm, particularly in the range of +0.3 mm to -0.3 mm.

8. The method according to claim 1, characterized in that the comparison between the input data (9) including the predetermined dimension and the data of the actual dimension is performed point by point.

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