Method for transferring particulate structural materials in a 3D printer

Abstract

In a method for transporting particulate construction material in a 3D printer, optical monitoring of a construction material curtain (6) of particulate construction material (2) is performed in the region of the construction material curtain (6) between the application device (1) and the construction field (4) within a working step of transporting the particulate construction material (2), an image of the construction material curtain (6) is formed and / or at least one dimension of the construction material curtain (6) is determined, the image and / or the at least one dimension is compared with a corresponding reference image and / or a predefined reference value, and at least one transport variable of the transport of the particulate construction material (2) is changed when the image deviates from the reference image and / or when the dimension deviates from the corresponding reference value.

Description

Technical Field

[0001] The present invention relates to a method for transferring particulate structural material in a 3D printer, in which the particulate structural material is transferred from an application machine in the form of a curtain of structural material onto a structural field.

Background Art

[0002] The so-called application of particulate structural material onto a structural field is understood to mean both the transfer of the particulate structural material onto the surface of the structural field and the smoothing of the transferred particulate structural material on the structural field.

[0003] The present invention particularly affects the transfer of particulate structural material onto a structural field.

[0004] In particular, in a 3D printer, it is desirable to monitor the uniform transfer of particulate structural material on a structural field and to recognize irregularities when transferring the particulate structural material transferred from an application device. When such non-uniformities are recognized, the non-uniformities are automatically reduced or eliminated by appropriate measures. For this purpose, the corresponding variables for the transfer of the particulate structural material are affected.

[0005] It is known to use so-called 3D printing or so-called 3D printing methods for the production of parts, workpieces or moldings by single or mass production. In such printing methods, three-dimensional parts or workpieces are produced in a form that is formed layer by layer.

[0006] This formation is carried out in a computer-controlled manner from one or more types of fluid or solid materials according to predetermined means and forms. The reference values for the part or workpiece to be printed may be provided, for example, by a so-called computer-aided design system (CAD).

[0007] During the printing of 3D structures or 3D parts, a physical or chemical curing or melting process is performed on the particulate structural material, also known as the molding material. Materials used in such 3D printing methods include structural and molding materials such as plastics, synthetic resins, ceramics, minerals, sand, and metals.

[0008] When implementing 3D printing, various manufacturing processes are publicly known.

[0009] However, some of the processes in these methods include method steps illustrated below. - Partial or complete application of particulate structural material, also known as particulate material or powdered forming material, onto a so-called structural field. This forms a layer of uncured particulate material, and the partial or complete application of particulate structural material includes transporting and smoothing the particulate structural material. For example, selective curing of an attached layer consisting of uncured particulate structural material in a predetermined subregion by selective compression, coating, attachment, or use of a laser, such as a binder. - Repeating a preceding method step on another layer plane for forming a part or workpiece in layers. For this purpose, the part or workpiece formed or coated in layers on the structural field descends with the structural field by one layer plane or layer thickness each time, or the 3D printing apparatus rises relative to the structural field by one layer plane or layer thickness each time, after which a new layer is applied partially or entirely. • The subsequent removal of uncured, loose, particulate structural material surrounding the manufactured part or workpiece.

[0010] From the prior art, various methods are known for forming 3D structures or for transferring and coating particulate structural materials onto a structural field in order to form 3D structures.

[0011] A method and apparatus for applying a fluid, as well as its use, are publicly known in German Patent No. 10117875.

[0012] A method for applying a fluid, particularly with respect to a particulate material applied to an area to be covered, in which case the fluid is applied to the area to be covered in front of the blade when viewed in the direction of the blade's forward movement, and then the blade moves over the applied fluid.

[0013] The objective is to provide an apparatus, method, and use of apparatus that can achieve the most even distribution of a fluid material on an area to be covered.

[0014] To solve this problem, it is envisioned that the blade will perform a certain type of rotational vibration. The vibrational rotation of the blade will fluidize the fluid attached to the area to be coated. This will not only allow for the application of particulate materials that tend to aggregate as flat and smooth as possible, but it will also be possible to influence the compression of the fluid by the vibration.

[0015] In a preferred embodiment, it is assumed that excess fluid is applied to the area to be covered. Therefore, as a blade vibrates with a certain rotational motion, the excess fluid is homogenized in a roller formed from the fluid or particulate material by the forward movement of the blade, in front of the blade as viewed in the direction of the blade's forward movement. This can fill any resulting cavities between individual clumps, and larger clumps of particulate material are broken up by the movement of the roller.

[0016] The drawback of this known prior art is that when transferring particulate structural material onto a structural field, the amount of particulate structural material needed to form layers is not adequately controlled. As a result, the amount of particulate structural material before the means for smoothing the particulate structural material varies, and consequently, the pressure conditions on layers below the layer currently to be coated vary. This impairs the uniform formation of layers and degrades the quality of the 3D structure to be formed.

[0017] Therefore, there is a need to improve conventional technology and, consequently, to improve the method of transporting particulate structural materials in 3D printers. [Prior art documents] [Patent Documents]

[0018] [Patent Document 1] German Patent No. 10117875 [Overview of the project] [Problems that the invention aims to solve]

[0019] The object of the present invention is to provide a method for transporting particulate structural material in a 3D printer, in which the particulate structural material is transported uniformly.

[0020] The method should improve both the uniformity of the height of the transferred particulate structural material layer and the uniformity of the density within the transferred particulate structural material layer. In this way, after the transferred particulate structural material has been smoothed, an improvement in the quality of the coated particulate structural material layer is achieved. [Means for solving the problem]

[0021] This problem is solved by a method having the features described in claim 1 of the independent claim. An advanced form is described in the dependent claim.

[0022] According to the method of the present invention, it is envisioned that an optical control system will be used when transferring particulate structural material onto the structural field in a 3D printer.

[0023] For this purpose, it is assumed that in the work step of transferring the particulate structural material using a coating device, optical monitoring of the particulate structural material is carried out. This optical monitoring is performed in the region between the coating device and the structural field formed by the particulate structural material arriving from the coating device, so-called structural material curtain. This structural material curtain consisting of particulate material moving or falling from the coating device to the structural field by gravity has a width that depends on the coating device. In one form where the coating device can supply the particulate structural material over the entire width of the structural field, the structural material curtain has the width of the entire usable structural field.

[0024] In an alternative form, the coating device has only a part of the width of the structural field. In this case, the work can be carried out using a plurality of coating devices, and the plurality of coating devices can cooperate to cover the entire width of the structural field or transfer the particulate structural material over the entire width of the structural field. In this case, the structural material curtain also has only a part of the width of the structural field.

[0025] This structural material curtain further has a thickness that also depends on the coating device. Furthermore, the structural material curtain has a height that may correspond to the shortest distance between the coating device and the surface of the structural field. Since the coating device moves on the surface of the structural field when transferring the particulate structural material, the structural material curtain can have an angle different from perpendicular across the structural field rather than being perpendicular to the surface of the structural field. In this case, the height of the structural material curtain is greater than the shortest distance between the coating device and the surface of the structural field.

[0026] As is known from the prior art, the transferred particulate structural material is smoothed by means of smoothing the particulate structural material, whereby a uniform thickness or thickness of the particulate structural material occurs when applying the current layer on the surface of the structural field.

[0027] The means for smoothing such particulate structural material may be a squeegee blade, a swing blade, a knife, a doctor, or an equivalent of a 3D printer, by which the transported particulate structural material is smoothed.

[0028] As known from the prior art, the aforementioned means moves horizontally across the structural field at a constant distance from the structural field. Simultaneously, the coating device also moves horizontally across the structural field at a constant distance from the structural field. In this case, it can be assumed that the coating device is positioned at a constant distance from the smoothing means that does not change when they move together across the structural field.

[0029] The height or thickness of the layer of the applied particulate structural material may be between 0.5 and 6 times the average particle size of the particulate structural material. To achieve a height or thickness of 0.5 times the average particle size of the particulate structural material, the particulate structural material must be transported onto the structural field and compressed.

[0030] The average particle size of the particulate structural material is, for example, approximately 0.14 mm.

[0031] Particulate structural materials are generally understood as aggregates of individual particles of a material or mixture of materials, where each particle has a three-dimensional extent. These particles can be understood as mainly round or oval particles, or as elongated particles, and for such particles, it is usually possible to represent an average diameter in the range of 0.1 mm to 0.4 mm. Such particulate structural materials are fluid.

[0032] The particulate structural material to be transferred from the coating apparatus forms a so-called structural material curtain between the coating apparatus and the surface of the structural field. The width of the structural material curtain usually corresponds to the width of the exit opening or gap in the coating apparatus. The thickness of the structural material curtain is affected by the amount of particulate structural material transferred by the coating apparatus per unit time. As the amount of particulate structural material transferred by the coating apparatus per unit time increases, the thickness of the structural material curtain also increases, and vice versa.

[0033] Therefore, by determining the thickness of the structural material curtain, it is possible to estimate the amount of particulate structural material currently being transferred from the coating device, and consequently, by determining the thickness of the structural material curtain, it is possible to control the amount of particulate structural material transferred by the coating device.

[0034] When the structural material curtain collides with or contacts the surface of the structural field, it usually forms a triangular geometric shape in a side view at the so-called collision point, with one side of this triangle aligned horizontally, that is, parallel to the surface of the structural field, and facing this surface of the structural field. This state is hereafter referred to as the structural material deposit. Spatially, this structural material deposit has, for example, the shape of a hypothetical triangular prism, in which the three rectangular sides are positioned perpendicular to the direction of movement of the coating device on the structural field, with their longitudinal spread. Furthermore, the longitudinal spread is oriented parallel to the surface of the structural field.

[0035] This structural material deposit is formed depending on the amount of particulate structural material being transported. Therefore, when a larger amount of particulate structural material is transported by the coating device, the structural material deposit will have at least greater height and / or width than when a smaller amount of particulate structural material is transported.

[0036] Therefore, by identifying the dimensions of the structural material deposits, it is possible to estimate the amount of particulate structural material currently being transported from the coating device, and consequently, to control the amount of particulate structural material transported by the coating device by identifying the dimensions of the structural material deposits.

[0037] The dimensions of such a prismatic structural material deposit having a triangular base and an upper base include the maximum width and maximum height in the lower region of the structural material deposit. Furthermore, at least one angle between the triangular base and the upper base of the triangular structural material deposit may also be used as a dimension. Such an angle may be, for example, a so-called inclination angle representing the inclination of the structural material deposit with respect to the flat surface of the structural field.

[0038] By precisely influencing the amount of structural material to be transferred per unit time, it is possible to improve the uniformity of the layer to be applied to the structural field. Such improvement in the uniformity of the particulate structural material layer, when a corresponding level of precision or quality is achieved, has a favorable effect on the quality of the 3D structure to be formed. In this case, in special circumstances, the smoothing process may be omitted for specific applications of 3D printing.

[0039] Therefore, in such applications, immediately after the particulate structural material is transferred by the coating device, selective curing of the attached, uncured particulate structural material layer may be performed in a predetermined sub-region.

[0040] Optical monitoring of a structural material curtain consisting of particulate structural material is envisioned to be performed during the work step of transferring the particulate structural material onto the structural field. In this case, for example, one or more cameras are used to capture the structural material curtain from at least one direction or viewpoint.

[0041] Similarly, optical monitoring of triangular prismatic structural material deposits can be envisioned to be performed at the collision sites of particulate structural material on the structural field. In this case, for example, one or more cameras are used to capture the structural material deposits from at least one direction or viewpoint. This direction or viewpoint may be a lateral or oblique view of the triangular prismatic structural material deposits at the collision site.

[0042] Generally speaking, in the work step of transporting particulate structural material, an image of the structural material curtain and / or structural material deposit at the collision site is formed by appropriate means for optically monitoring the particulate structural material to be transported. Such means may be, for example, at least one camera, laser, projector and / or a combination of laser and / or camera, or an equivalent image recording device.

[0043] In one alternative, it is assumed that an image is formed of a portion of the structural material curtain and / or structural material deposit. In one alternative of the method, in order to optically monitor the particulate structural material to be transported according to the method, it is sufficient that an image is formed in part or a portion of the structural material curtain and / or structural material deposit and processed according to the method.

[0044] For example, such an image of a structural material curtain and / or structural material deposit may be shown in a side view or front view of the structural material curtain and / or structural material deposit. Alternatively, an oblique view or perspective view of the structural material curtain and / or structural material deposit may be formed as the image.

[0045] For example, a 3D recording device consisting of multiple cameras or 3D cameras utilizing structured optical scanners may be used.

[0046] If multiple suitable means for optically monitoring the particulate structural material to be transported, i.e., the structural material curtain and / or structural material deposit, are positioned at various locations, each directed toward the structural material curtain, then, for example, one optical monitoring means is selected according to the method. Furthermore, it is conceivable that, controlled by the method according to the present invention, another optical monitoring means, such as a camera, may be selected or switched to another means to form an image of the structural material curtain. Moreover, it is envisioned that multiple optical monitoring means may be used simultaneously. Thus, for example, images of the structural material curtain can be formed from various viewpoints simultaneously. This provides a means for simultaneously determining multiple dimensions of the structural material curtain. The same applies to the structural material deposit.

[0047] For example, a camera that captures a front view can determine the width of a structural material curtain, but it cannot determine the angle at which the structural material curtain deviates from the vertical line. To determine this angle of the structural material curtain, a camera that captures a side view of the structural material curtain is selected, but this camera cannot determine the width of the structural material curtain.

[0048] A camera that captures an image of the structural material curtain from an oblique angle can determine both the width and angle of the structural material curtain. However, to obtain accurate values ​​for the width and angle of the structural material curtain, it is necessary to implement an image processing algorithm that handles, for example, oblique correction.

[0049] The resolution and recording speed of the camera used must be sufficiently high so that the coating apparatus, and consequently the structural material curtain, can form a sufficiently accurate image at any speed as it moves across the structural field. In this case, a sufficiently accurate image of the structural material curtain is understood to be an image that can be post-processed according to the method of the present invention, i.e., suitable for, for example, image comparison or for determining the dimensions of the structural material curtain, such as the height and / or width and / or angle of the structural material curtain.

[0050] Depending on the mounting position, the camera may be fitted with a wide-angle lens or provide an appropriate field of view to record or image as complete an area as possible of the structural material curtain and / or structural material deposit.

[0051] It may be assumed that appropriate software can be used to normalize the recording or imaging, or to enable post-processing in terms of contrast or filtering. In any case, the objective is to ensure that the imaging of the structural material curtain and / or structural material deposit is of sufficient quality for subsequent method steps.

[0052] For example, it is conceivable that the geometric dimensions of a structural material curtain and / or structural material deposit, which consists of particulate structural material, may be determined based on images such as individual images or videos from one or more observation directions of the structural material curtain and / or structural material deposit, formed during optical monitoring.

[0053] In this case, for example, information about the basic dimensions of the structural material curtain or the outer contour of the structural material curtain can be identified.

[0054] The basic dimensions of structural material curtains include, for example, dimensions such as the width, height, or angle of the structural material curtain.

[0055] With respect to the outer contour of the structural material curtain, for example, its shape and thickness can be specified. An exemplary shape of the structural material curtain may be a rectangular parallelepiped. Alternatively, the structural material curtain may be a truncated pyramid, in which case, for example, the width of the particulate structural material transferred onto the structural field is greater than the width of the particulate structural material exiting the coating device. Similarly, the thickness of the particulate structural material transferred onto the structural field may be greater than the thickness of the particulate structural material exiting the coating device.

[0056] In addition to such dimensions, the dimensions along the structural material curtain, i.e., its longitudinal spread, can be determined. In this case, for example, different thicknesses of the structural material curtain can be determined at various points along the curtain. Furthermore, the maximum and / or minimum thickness of the structural material curtain, or the average thickness of the structural material curtain, may be determined.

[0057] With respect to structural material deposits, dimensions may include the maximum width in the lower region of the structural material deposit, i.e., the length of the approximately horizontal side of a hypothetical triangle, and the maximum height of the triangular prism-shaped structural material deposit, such as the height of the hypothetical triangle, where height means the height above the length of the horizontal side. Furthermore, for example, the interior angles of the lower and upper bases of the triangle of the triangular prism-shaped structural material deposit, or the inclination angle of the structural material deposit, can be specified as dimensions and used later for comparison with predetermined values ​​for such dimensions.

[0058] The particulate structural material particles in the structural material curtain are constantly moving as they transfer from the coating device to the structural field. This particle movement causes dynamic changes within the structural material curtain. These changes are due to the varying velocities, falling speeds, and collisions of the particulate structural material particles. Similar dynamic changes occur in the structural material deposits.

[0059] These dynamic changes or interfering particle movements in structural material deposits and / or structural material curtains can affect the quality of the layer of particulate structural material being transported on the surface of the structural field. Once the relationship between interfering particle movements and, for example, the amount of particulate structural material to be transported per unit time is recognized during test runs, the method can accurately influence the amount of particulate structural material to be transported per unit time as a transport variable. This influence is exerted when unwanted displacements within the structural material curtain and / or structural material deposit are detected when comparing the image of the formed structural material curtain and / or structural material deposit with a related reference image.

[0060] It is envisioned that the longitudinal extent of a structural material curtain be divided into sub-regions or multiple sub-regions, and corresponding images be formed within these sub-regions. The same may be done with structural material deposits. From these images, dimensions related to the sub-regions, such as the height and / or thickness and / or angle of the structural material curtain, can be identified. In this case, all sub-regions, when added together or when placed side by side, can image the entire length of the structural material curtain or structural material deposit in terms of their longitudinal extent.

[0061] It is also envisioned that, in order to determine or analyze the displacement, the image of a subregion may be compared with a related reference image.

[0062] It is further assumed that a comparison will be performed between a specific dimension and a predetermined value or reference value for that dimension. In this comparison, the deviation between the dimension and the predetermined value or reference value for that dimension will be identified, and if this deviation exceeds a predetermined tolerance limit, at least one variable (substrate coating variable) relating to the transport of the particulate structural material will be changed. This variable will also be referred to below as the transport variable.

[0063] Alternatively, or in addition to, a comparison between a specific dimension and a predetermined or reference value for that dimension, it is possible to compare the formed image with a related reference image. If a deviation exceeding a predetermined tolerance limit is detected in such a comparison, such as image comparison, at least one variable relating to the transport of the particulate structural material, i.e., the transport variable, is changed so that the amount of particulate structural material to be transported is controlled or changed in a closed-loop or open-loop manner. The objective is to make the currently formed image match the reference image, thereby improving the quality when coating layers of particulate structural material, i.e., improving the uniformity of the height or thickness of the transported particulate structural material layer.

[0064] For example, when comparing dimensions with a reference value, if it is confirmed that the thickness of the structural material curtain is below a predetermined reference value for the thickness of the structural material curtain, the transfer variable that determines, for example, the amount of particulate structural material to be transferred per unit time or area is increased. Consequently, a larger amount of particulate structural material arriving from the coating device is released or transferred. As a result, the thickness of the structural material curtain is expected to increase again, because the thickness is directly related to the amount of particulate structural material to be transferred.

[0065] For alternative comparisons between specified dimensions and their reference values, the length, height, or required angle of a structural material curtain, or the length, width, height, interior angle, or inclination angle of the lower or upper base of a structural material deposit triangle may be used.

[0066] When a so-called fluidizer is used to transfer particulate structural material, the transfer variable of the amount of particulate structural material to be transferred per unit time or per unit area is affected, and this effect is assumed to be exerted by the control or pressurization of a number of so-called porous gas exit means in the fluidizer by a gas under pressure. Another means of affecting this transfer variable is to change the pressure of the gas. Another alternative example is that the change in gas pressure is performed over time and periodically, and this can be done, for example, at an adjustable frequency.

[0067] It is also anticipated that one or more deviations between one or more dimensions and their corresponding predetermined values ​​may simultaneously affect multiple transfer variables.

[0068] Therefore, for example, it is possible to change the transfer variable of the movement speed of the 3D printer's working means on the surface of the structural field, while simultaneously increasing the amount of particulate structural material transferred from the coating device.

[0069] These working means of a 3D printer include, in particular, dispensing devices for particulate structural materials, as well as means for smoothing the transferred structural material, such as squeegee blades, swing blades, knives, or doctors.

[0070] By dividing the optical monitoring of the structural material curtain into sub-regions, it is possible to change the transport variables for each sub-region in accordance with the dimensional deviation from a predetermined value in that sub-region. This assumes that the means for transporting the particulate structural material, such as coating devices, are arranged in a correspondingly divided or proportionally multiple manner. Such multiple arrangements of these means may be such that multiple coating devices are arranged side by side in a single row or at least in two rows offset from each other. As will be apparent to those skilled in the art, such arrangements of means must always ensure that the particulate structural material is applied uniformly to the layer and to all necessary areas on the structural field.

[0071] Similarly, it is assumed that the structural material curtain will be analyzed with respect to the dynamic properties of the particles. The particulate structural material moves or flows within the structural material curtain during the work steps of transporting the particulate structural material. During this time, the basic dimensions and / or outer contour of the structural material curtain change continuously. This dynamic change can be captured, for example, over time, using video recording, continuous images, or image streams.

[0072] For example, evaluating this time-varying dimension, such as the thickness of a structural material curtain, provides information about the range of thickness variation, i.e., the minimum and maximum values ​​of the thickness dimension. Furthermore, such thickness variation can be analyzed over time. In this way, for example, it can be confirmed that the thickness variation is obtained periodically between its minimum and maximum values. From this change over time, for example, the average frequency at which the thickness variation process is repeated in a structural material curtain can be identified.

[0073] The changes in reference thickness identified in a series of experiments allow for a frequency comparison between the frequency of thickness changes and a specific reference frequency, which can inform us about the influence of the quality of the coated particulate structural material layer on the frequency of thickness changes.

[0074] For example, values ​​related to such thickness changes and associated reference frequencies identified in test runs may be relevant to the quality to be achieved in the layer of particulate structural material to be formed. Therefore, at a particular thickness change or frequency of such thickness changes, it is possible to influence the transport variables so that the thickness change becomes smaller or the frequency of the thickness change changes, thereby improving the quality of the current layer of particulate structural material to be applied in this manner.

[0075] Examples of variable transport variables include the amount of particulate structural material to be transported per unit time. Furthermore, the amount of particulate structural material per unit area can be varied. Moreover, such changes in transport amounts per unit time and / or per unit area can be varied over time, in which case this change can be made at a specific, variable, or time-varying frequency. Thus, for example, the set frequency value may increase or decrease over time, or increase and decrease sequentially. For example, it is assumed that the amount of particulate structural material per unit time acts against the time-varying thickness change in the structural material curtain due to the time-varying change in the transport variable, so that the time-varying thickness change is at least reduced or eliminated.

[0076] Therefore, in order to prevent the quality of the application of particulate structural materials from being compromised, the particle motion or motion mechanism of the particulate structural materials can be precisely altered. When optical monitoring is already performed individually in this sub-region, the particle motion of the particulate structural materials can be influenced differently not only for the entire structural material curtain but also for each sub-region of the structural material curtain.

[0077] The aforementioned features and advantages of the present invention can be better understood and appreciated by carefully examining the following detailed description of preferred but non-limiting exemplary embodiments of the invention, together with the accompanying drawings. [Brief explanation of the drawing]

[0078] [Figure 1] The diagram shows means for transporting particulate structural material and means for smoothing the particulate structural material on a structural field. [Figure 2] This illustrates exemplary means for transporting particulate structural materials, such as coating devices in 3D printers. [Figure 3] This shows another example unit for transporting particulate structural materials in a 3D printer. [Figure 4] A partially enlarged view of the structural material curtain and structural material deposit areas on the structural seat field is shown. [Modes for carrying out the invention]

[0079] Figure 1 shows means 1 for transporting particulate structural material 2 and means 3 for smoothing the particulate structural material 2 on a structural field 4.

[0080] Such means 1 for transporting the particulate structural material 2 may be, for example, a so-called coating apparatus 1, while the means 3 for smoothing the particulate structural material 2, as shown in the figure, may be, for example, a blade.

[0081] The coating apparatus 1 has a storage container 15 (not shown in Figure 1) in which particulate structural material 2 to be transferred is stored. A discharge port 5 for dispensing the particulate structural material 2 may be located at the lower end of the coating apparatus 1. To prevent the particulate structural material 2 from leaving the coating apparatus 1 uncontrolled, the coating apparatus 1 has a corresponding closing mechanism (not shown in Figure 1). This closing mechanism is configured to open and close the discharge port 5 or a corresponding opening located in the lower region of the coating apparatus 1.

[0082] When particulate structural material 2 is to be discharged from the coating device 1 and thus transferred onto the structural field 4, the closing means is opened. The particulate structural material 2 is transferred and reaches the surface of the structural field 4 in the form of a so-called structural material curtain 6. This process of transferring particulate structural material 2 is shown in Figure 1. The amount of particulate structural material 2 to be transferred is affected and controlled by changing the transfer variable. In this case, one transfer variable may be the amount of particulate structural material 2 to be transferred per unit time, while another transfer variable may be the amount of particulate structural material to be transferred per unit area.

[0083] For example, if the amount of particulate structural material 2 to be transferred per unit time and the moving speed of the coating device 1 in the moving direction 7 over the structural field 4 are appropriately controlled, the transfer of particulate structural material 2 to the surface of the structural field 4 will be extremely uniform and, consequently, of high quality.

[0084] As can be seen from Figure 1, more particulate structural material 2 is transported than is required to achieve the layer thickness 8. The smoothing means 3 is also moved along the structural field 4 in the direction of movement 7, so the excess particulate structural material 2 that is transported causes sediment to form.

[0085] For example, an optically monitoring means 9, such as a camera 9, is directed towards the structural material curtain 6 within its recording range 10, and the structural material curtain 6 is optically monitored by the monitoring means 9, and an appropriate image is created by recording an image or video. In Figure 1, the camera 9 is positioned to provide a front view of the structural material curtain 6. Alternatively, the camera 9 may be positioned to provide a side view or an oblique view, contrary to the drawing in Figure 1. It is also possible to arrange multiple cameras 9 to provide multiple views, such as a front view and a side view of the structural material curtain 6.

[0086] These images, using appropriate image processing software, allow for the identification of dimensions such as, for example, the thickness 11 or the angle 12 between the surface of the structural field 4 and the structural material curtain 6. These dimensions are related to the amount of particulate structural material 3 to be transported or the speed of movement in the direction of movement 7. Generally, an increase in the value for thickness 11 is assumed to indicate an increase in the amount of particulate structural material 2 during the transport work step. Also, generally, a decrease in the value for angle 12 is assumed to indicate an increase in the speed of movement of the coating device 1 during the transport work step.

[0087] Even if Figure 1 only shows the case where the angle 12 is approximately 90 degrees, the angle 12 can take a smaller value. For example, it is assumed that the angle 12 decreases as the movement speed of the coating device 1 in the movement direction 7 increases.

[0088] Further dimensions of the structural material curtain 6, such as its length 13 or height 14, which should be specified according to the method, are not shown in Figure 1.

[0089] When comparing currently specified dimensions, i.e., values ​​for thickness 11 and / or angle 12, it is found that these dimensions deviate from corresponding predetermined values, and a change in the transfer variables is made. These transfer variables are, for example, the amount of particulate structural material 2 to be transferred per unit time and the speed of the 3D printer's working means in the direction of movement 7. Here, the working means are understood to be the coating device 1 and the smoothing means 3, i.e., a blade.

[0090] For example, if the value for thickness 11 is greater than a corresponding predetermined value, the speed in the direction of movement 7 may be increased. Alternatively, the transfer variable for the amount of particulate structural material 2 to be transferred per unit time may be reduced until the dimensions again correspond to a predetermined value, in which case the tolerance range is determined in the usual way. This reduction in quantity can be achieved, for example, by affecting the size of the discharge port 5 in the coating apparatus 1.

[0091] The method-dependent changes in the transfer variables described for the coating of the particulate structural material 2 may be carried out differently in different sub-regions. This, of course, assumes that, for example, the 3D printer is equipped with multiple coating devices 1 for transferring the particulate structural material 2, and / or multiple smoothing means 3.

[0092] Figure 1 also shows a structural material deposit 20, which is represented, for example, by the upper or lower base of a triangle. The illustrated triangle is shown as an aid to how an observer can imagine a triangular prism-shaped structural material deposit 20 with the lower and upper bases of a virtual triangle in the region of particulate structural material 2 that collides with the structural field 4. The sides of the illustrated triangle as an object are, of course, not recognizable in the particulate structural material 2, but can be identified by evaluating, according to the method, the records generated during optical monitoring of the structural material deposit 20 consisting of particulate structural material 2 using appropriate software. Thus, other dimensions of the structural material deposit 20 can be identified from there.

[0093] Figure 2 shows a means for transporting particulate structural material 2, such as a coating device 1 provided on a 3D printer, which can move horizontally in the direction of movement 7 on the structural field 4.

[0094] The coating apparatus 1 has a storage container 15 for particulate structural material 2 to be stored. The coating apparatus 1 has an elongated discharge port 4 in its lower region for dispensing the particulate structural material 2, which then moves or falls toward the surface of the structural field 4 in the form of a structural material curtain 6.

[0095] As mentioned above, it is assumed that an image of the structural material curtain 6 is formed using a camera 9 directed towards the structural material curtain 6 within its recording range 10. For this purpose, the camera 9 can be oriented, for example, towards the side or front of the structural material curtain 6. As shown in Figure 2, a further possibility for the orientation of the camera 9 is to be oriented to view the structural material curtain 6 from an oblique angle. For this purpose, the camera 9 is rigidly connected to, for example, the coating device 1 and therefore moves along the structural field 4 with the coating device 1.

[0096] Based on the image formed by the camera 9, for example, the dimensions of the structural material curtain 6 shown in the illustration, such as its thickness 11, width 13, height 14, or the angle 12 between the surface of the structural field 4 and the structural material curtain 6 can be determined.

[0097] In Figure 2, the structural material deposit 20 is also shown by its hypothetical upper or lower base. Furthermore, the length 21 of the structural material deposit 20 is also shown. This length 21 essentially corresponds to the length 13 of the structural material curtain 6.

[0098] Figure 3 shows a means 1 for transferring particulate structural material 2 in a 3D printer. The transfer means 1 can move horizontally on the structural field 4 in the direction of movement 7. Means 1, also called a fluidizing device, is illustrated in a moment-record of the particulate structural material 2 exiting through the discharge port 5 and reaching the surface of the structural field 4 as a structural material curtain 6, where a new layer of particulate structural material 2 with a layer thickness 8 is formed. Another means 3 necessary for this is not shown in Figure 3.

[0099] The coating apparatus 1 has a hopper-shaped storage container 15 for storing particulate structural material 2. This hopper-shaped storage container 15 is elongated, and in this case, its length is several times its width.

[0100] The storage container 15 has an opening or discharge port 5. Two shut-off means 16 are arranged in the lower region of the hopper-shaped storage container 15, and the discharge port 5 is formed by the shut-off means 16. In the drawing in Figure 3, the left shut-off means 16 forms a ventilation gap 17 above it.

[0101] This arrangement of the blocking means 16 forms a blocking wedge made of particulate structural material 2 at the discharge port 5, thereby preventing the particulate structural material 2 from unexpectedly reaching the structural field 4.

[0102] The application of particulate structural material 2 onto the structural field 4 is achieved by fluidizing the particulate structural material 2 in the area of ​​the discharge port 5. For this purpose, it is envisioned that at least one porous gas outlet means 18 be placed in this area. In Figure 3, two porous gas outlet means 18 are positioned on the side wall of the storage container 15. Each of these two porous gas outlet means 18 has a gas connection part 19, which is connected to an external unit (not shown) that generates a gas whose gas pressure can be controlled.

[0103] Each porous gas exit means 18 has a gas-permeable porous material on the side facing the particulate structural material 2.

[0104] The gas, whose pressure can be controlled by an external unit, is uniformly distributed and exits through the porous gas exit means 18 from the porous gas exit means 18 towards the particulate structural material 2, and flows through the particulate structural material 2. This exiting gas is indicated in Figure 3 by several small arrows near the porous gas exit means 18. This exiting gas fluidizes the particulate structural material 2, causing it to be discharged through the discharge port 5 and reach the structural field 4 to form a structural material curtain 6.

[0105] Only a porous gas exit means 18 is required to fluidize the particulate structural material 2. Moreover, when gas flows from both sides to the particulate structural material 2 through the two porous structural materials 18, the fluidizing effect on the particulate structural material 2 is increased, and a larger amount of particulate structural material 2 is discharged through the discharge port 5.

[0106] To control the amount of particulate structural material 2 to be discharged, the pressure of the gas supplied to the porous gas discharge means 18 is changed. Therefore, for example, a higher gas pressure can enhance or improve the fluidization of the particulate structural material 2, and as a result, a larger amount of fluidized particulate structural material 2 can be discharged through the discharge port 5, increasing, for example, the thickness 11 of the structural material curtain 6.

[0107] Alternatively, a lower gas pressure can reduce or weaken the fluidization of the particulate structural material 2, resulting in the discharge of a smaller amount of particulate structural material 2.

[0108] Therefore, the dimension of the thickness 11 of the structural material curtain 6 may be controlled by controlling the gas pressure or by the number of porous gas venting means 18 used by this method. Thus, the method-dependent transfer variable of the amount of particulate structural material 2 to be transferred per unit time, or the method-dependent transfer variable of the amount of particulate structural material 2 to be transferred per area, can be controlled in a closed-loop or open-loop manner by the number of porous gas venting means 18 used. Another means of controlling the closed-loop or open-loop manner of these transfer variables is the gas pressure used for the porous gas venting means 18.

[0109] In a special modification, the gas pressure may be generated, for example, in a pulsed manner, which improves fluidity, and in this case, the amount of particulate structural material 2 discharged can also be changed over time.

[0110] Figure 4 shows a partial enlarged view of the structural material curtain 6 and the structural material deposit 20 on the structural field 4. The coating apparatus 1 is also shown in Figure 4 along with its discharge port 5. Furthermore, a means 9a for optically monitoring the structural material curtain 6 is shown along with its recording range 10a. The thickness 11 of the structural material curtain 6 is also illustrated.

[0111] Figure 4 shows another means 9b for optically monitoring the structural material deposit 20, in which case a single means 9 may monitor both the structural material curtain 6 and the structural material deposit 20. The drawing of means 9 in Figure 4 is merely a principle diagram and does not represent the exact dimensional ratio or exact position of means 9, which may be positioned as needed. Therefore, depending on its orientation, means 9 may be shown in a front view, side view, or perspective view facing the structural material curtain 6 and / or the structural material deposit 20.

[0112] The dimensions of a triangular prism-shaped structural material deposit 20 having a triangular lower or upper base, which can be specified according to the present invention, are expressed using a height 22, a width 25, an interior angle 23, and an inclination angle 24.

[0113] The length 21 of the structural material deposit 20 is not shown in Figure 4. This is because Figure 4 shows a side view of the structural material deposit 20, and in a side view, the length 21 of the structural material deposit 20 extends in the depth direction of the figure. This application relates to the invention described in the claims, but also includes the following other embodiments. 1. A method for transporting particulate structural material (2) in a 3D printer, In a method for transferring particulate structural material (2) from a coating device (1) onto a structural field (4) in the form of a structural material curtain (6), Optical monitoring of the structural material curtain (6) consisting of particulate structural material (2) is performed in the area of ​​the structural material curtain (6) between the coating device (1) and the structural field (4) during the work step of transferring the particulate structural material (2). An image of the structural material curtain (6) is formed, and in this process, the image of the structural material curtain (6) is an image, a sequence of images, or a video. From the image of the formed structural material curtain (6), at least one dimension of the structural material curtain (6) is identified. The image and / or at least one specified dimension are compared with the corresponding reference image and / or a predetermined reference value. When the image deviates from the reference image and / or when the dimensions specified deviate from the corresponding reference values, control or change at least one transport variable for the transport of the particulate structural material (2), and consequently the amount of particulate structural material (2) to be transported. A method characterized by the following features. 2. The method of claim 1, characterized in that optical monitoring of the structural material curtain (6) and / or structural material deposit (20) is performed in at least one direction toward the structural material curtain (6) and / or structural material deposit (20), and at that time, an image of the structural material curtain (6) and / or structural material deposit (20) or an image of a portion of the structural material curtain (6) and / or structural material deposit (20) is formed in a side view and / or front view and / or perspective view. 3. The method according to 1 or 2 above, characterized in that the dimensions of the structural material curtain (6) are length (13), height (14), thickness (11), or angle (12), and the dimensions of the structural material deposit (20) are length (21), height (22), width (25), interior angle (23), or inclination angle (24). 4. The variable for transporting the particulate structural material (2) is the amount of particulate structural material (2) to be transported per unit time, the amount of particulate structural material (2) to be transported per unit area, the speed at which the 3D printer's working means moves on the surface of the structural field (4), or the change over time of the amount of particulate structural material (2) to be transported, one of the methods described in 1 to 3 above. 5. A method any one of the above 1 to 4, characterized in that the amount of particulate structural material (2) to be transported is changed over time at a fixed frequency or at a frequency that changes over time. 6. One of the methods described in 1 to 5 above, characterized in that optical monitoring of the particulate structural material (2) to be transported is performed by dividing the area of ​​the structural material curtain (6) and / or the area of ​​the structural material deposit (20) into multiple sub-regions, wherein the sub-regions extend in the longitudinal or transverse direction of the structural material curtain (6) and / or the structural material deposit (20). 7. The method described in any one of the above 1 to 6, characterized in that the partial regions, when totaled, cover all areas of the structural material curtain (6) and / or all areas of the structural material deposit (20). 8. The method of 6 or 7 described above, characterized in that the transport variables for the transport of the particulate structural material (2) are changed differently in each sub-region. 9. A method any one of the above 1 to 8, characterized in that the transfer variables of the amount of particulate structural material (2) to be transferred per unit time and / or the amount of particulate structural material (2) to be transferred per area are controlled by changing the number of porous gas outlet means (18) used in the fluidizer (1) and / or the pressure of the gas applied to the porous gas outlet means (18) using the fluidizer (1). [Explanation of Symbols]

[0114] 1. Coating apparatus / means for transferring particulate structural material / fluidizing apparatus 2. Particulate structural materials 3. Means / blades for smoothing 4. Structural Fields 5. Discharge port for particulate structural materials 6. Structural materials: Curtains 7 Direction of movement 8 layers thick 9, 9a, 9b Optical means of surveillance / camera 10, 10a, 10b recording range 11. Structural material: Curtain thickness 12. Angle of structural material curtains 13 Structural material Curtain length 14. Structural materials: Curtain height 15 Storage containers 16 Blocking means 17. Ventilation gap 18 Porous gas exit means 19 Gas connection part 20. Structural material deposits (a triangular prism-shaped structural material deposit with a hypothetical triangular base or upper base) 21 Length of structural material deposits 22 Height of structural material deposits 23 Interior angles of structural material deposits 24. Inclination angle of structural material deposits

Claims

1. A method for transporting particulate structural material (2) in a 3D printer, In a method for transferring particulate structural material (2) from a coating device (1) onto a structural field (4) in the form of a structural material curtain (6), Optical monitoring of the structural material curtain (6), which consists of particulate structural material (2), is performed in the region of the structural material curtain (6) between the coating apparatus (1) and the structural field (4) during the work step of transferring the particulate structural material (2). One or more cameras are used to form an image of the structural material curtain (6), and the image of the structural material curtain (6) is an image, a sequence of images, or a video. From the image of the formed structural material curtain (6), at least one dimension of the structural material curtain (6) is identified, which includes the thickness (11) of the structural material curtain and / or the height (22) and / or width (25) of the structural material deposit. The image and / or at least one specified dimension is compared with the corresponding reference image and / or a predetermined reference value. When the image deviates from the reference image and / or when the dimensions specified deviate from the corresponding reference values, control or change at least one transport variable for the transport of the particulate structural material (2), and consequently the amount of particulate structural material (2) to be transported. A method characterized by the following features.

2. The method according to claim 1, characterized in that optical monitoring of the structural material curtain (6) and / or structural material deposit (20) is performed in at least one direction toward the structural material curtain (6) and / or structural material deposit (20), and at that time, an image of the structural material curtain (6) and / or structural material deposit (20) or an image of a portion of the structural material curtain (6) and / or structural material deposit (20) is formed in a side view and / or a front view and / or an oblique view.

3. The method according to claim 1 or 2, characterized in that the dimensions of the structural material curtain (6) further include length (13), height (14), or angle (12), and the dimensions of the structural material deposit (20) further include length (21), interior angle (23), or inclination angle (24).

4. The method according to any one of claims 1 to 3, characterized in that the variables for the transport of the particulate structural material (2) are the amount of particulate structural material (2) to be transported per unit time, the amount of particulate structural material (2) to be transported per unit area, the moving speed of the 3D printer's working means on the surface of the structural field (4), or the change over time of the amount of particulate structural material (2) to be transported.

5. The method according to any one of claims 1 to 4, characterized in that the amount of particulate structural material (2) to be transported is changed over time at a fixed frequency or at a frequency that changes over time.

6. The method according to any one of claims 1 to 5, characterized in that optical monitoring of the particulate structural material (2) to be transported is performed by dividing the area of ​​the structural material curtain (6) and / or the area of ​​the structural material deposit (20) into a plurality of sub-regions, wherein the sub-regions extend in the longitudinal or transverse direction of the structural material curtain (6) and / or the structural material deposit (20).

7. The method according to any one of claims 1 to 6, characterized in that the partial regions, when totaled, cover all areas of the structural material curtain (6) and / or all areas of the structural material deposit (20).

8. The method according to claim 6 or 7, characterized in that the transport variables for the transport of the particulate structural material (2) are changed differently in each sub-region.

9. The method according to any one of claims 1 to 8, characterized in that the transfer variables of the amount of particulate structural material (2) to be transferred per unit time and / or the amount of particulate structural material (2) to be transferred per area are controlled by changing the number of porous gas outlet means (18) used in the fluidizer (1) and / or the pressure of the gas applied to the porous gas outlet means (18) using the fluidizer (1).

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