Method for producing 3D structures, in which the speed of movement of the working means, in particular the squeegee, is reduced in critical areas

Abstract

The present invention relates to a method for producing 3D structures, where the problem is to be solved by building up layers reliably and accurately in a 3D printing process. The task is to analyze the data of the 3D structure to be fabricated, identify critical regions within the 3D structure to be fabricated, and When a critical area identified in the creation of the 3D structure is reached, the speed of movement of the working implement of the 3D printer across the build area is at least temporarily reduced; This can be solved by:

Description

Technical Field

[0001] The present invention relates to a method for producing a 3D structure in which a 3D structure is constructed in layers in a 3D printer.

Background Art

[0002] It is known to use so-called 3D printing or so-called 3D printing methods to manufacture individual or mass-produced parts, workpieces, or molds. In such printing methods, three-dimensional parts or workpieces are manufactured by being constructed in layers.

[0003] The construction is computer-controlled and is performed from one or more liquid materials or solid materials according to predetermined dimensions and shapes. The reference values of the part or workpiece to be stereolithographically printed can be provided, for example, by a so-called computer-aided design system (CAD).

[0004] When printing a 3D structure or 3D part, a physical or chemical curing process or melting process occurs within the particulate shaping material, also referred to as the molding material. As materials for such 3D printing methods, for example, shaping materials or molding materials such as plastics, synthetic resins, ceramics, and metals are used.

[0005] When implementing 3D printing methods, various manufacturing method sequences are known.

[0006] However, some of these method sequences include the following exemplary method steps. · A step of partially or fully applying a particulate shaping material, also referred to as a particulate construction material or a particulate shaping material, to a so-called shaping area to form a layer made of a non-curable particulate material. · A step of selectively curing the applied layer made of a non-curable particulate shaping material in a predetermined partial area by selective compression, printing, or application of a treatment agent such as an adhesive, or use of a laser. - A step of repeating a preceding method step in another layer in order to construct a part or workpiece in layers. For this purpose, it is intended that the part or workpiece constructed or printed in layers on the build area descends by one layer plane or layer thickness along with the build area, or that the 3D printer rises by one layer plane or layer thickness relative to the build area, before the new layer is applied partially or entirely. - A step of subsequently removing loose, non-curing, particulate molding material surrounding the finished part or workpiece.

[0007] In the prior art, various methods for fabricating 3D structures or various methods for applying particulate material to a fabrication area in order to fabricate a 3D structure are known.

[0008] Patent Document 1 describes a coater and method for applying a powder layer in an apparatus for manufacturing a three-dimensional object by curing a layer of powder material at points corresponding to each cross-section of the object.

[0009] The problem to be solved is to provide an apparatus and method for manufacturing a three-dimensional object by solidifying a layer of powdered molding material, which can shorten the molding time of the three-dimensional object.

[0010] For this purpose, the apparatus includes a coater that is movable across the build area for applying layers of powdered build material within the build area. The coater consists of rigid blades fixed to and connected to the coater. To preheat the powdered build material, the coater is provided with a heating device that is at least partially integrated within the coater. This makes it possible to preheat the powder during or before application as layers, and thus reduce the overall build time of three-dimensional objects.

[0011] Patent Document 2 describes a method for manufacturing three-dimensional molded parts using layered fabrication technology, in which the water content of the fabrication material mixture can be adjusted.

[0012] The goal is to provide a method and material system that can guarantee certain material properties, particularly the flow properties of the molding material, during the construction process.

[0013] Therefore, the particulate material is intended to be applied to the build area in a predetermined layer thickness using a coater. Furthermore, a binder liquid is selectively applied to the build material via a print head, during which the binder liquid is polymerized using at least one activator introduced into the sand. The build area is then lowered by the thickness of the layer, or the coater is raised by the thickness of one layer, and these steps are repeated until the desired molded part is produced, during which a chemical agent is introduced into the build material, binder liquid, and / or activator, and the chemical agent is intended to control the water content of the build material mixture.

[0014] In this method, the moisture content in the sand is controlled. In particular, the moisture content and liquid content are regulated or at least stabilized. In this way, essentially, the same chemical and physical properties should always be achieved during the manufacturing of three-dimensional molded parts.

[0015] In such prior art 3D printers, it is common for one or more layers to be constructed at a constant speed or at the same speed for each layer. In this case, it refers to the speed at which the 3D printer's working mechanism moves across the so-called build area where the 3D structure is created.

[0016] To enhance the effectiveness of such 3D printers, the speed is also increased to enable 3D printing in shorter time units. In this case, the speed or transition speed of the workpiece is achieved at 500 mm / s or more across the build area.

[0017] However, in this case, especially as the speed gradually increases, there are problems in accurately constructing small-scale structures.

[0018] The disadvantages of this known prior art are, for example, that in areas that are susceptible to this influence or areas that are mechanically susceptible to influence, as the speed of printing a single layer with a 3D printer becomes increasingly faster, cracks or displacements may occur in sub-regions of the layer that is currently to be constructed or in the layer below the layer that is to be constructed. This results in defects in the three-dimensional final product that reduce quality and, in the worst case, lead to defective products.

[0019] Therefore, there is a need to improve the known technology, and thus, there is a need for an improved method for producing 3D structures in a 3D printer.

Prior Art Documents

Patent Documents

[0020]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0021] The problem of the present invention is to provide a method for producing a 3D structure or a layer of a 3D structure in a 3D printer, thereby enabling reliable and accurate construction of layers by the 3D printing method.

[0022] In particular, in important areas where cracks or displacements may occur in the sub-structure of the 3D structure in the layer that is currently to be constructed or in the layer below the layer that is currently to be constructed, the quality of 3D printing should be guaranteed.

Means for Solving the Problems

[0023] The problem is solved by a method having the features described in claim 1 of the independent claims. The development forms are described in the dependent claims.

[0024] The method of fabricating a 3D structure with a 3D printer is intended to be used in all 3D printers or 3D printing machines where substrate coating and / or fluid coating is performed, especially in 3D printers or 3D printing machines where the construction of the 3D structure is computer-controlled.

[0025] Such a 3D printer comprises a control unit that controls the construction of layers during 3D printing, and this control unit receives control commands in machine-readable form or machine-readable code.

[0026] To control the fabrication of layers in 3D printing, a machine-readable code having control commands can be produced by a computer-aided design system (CAD) from the reference values of the part or workpiece to be printed and transmitted to the control unit of the 3D printer. Usually, this machine-readable code is a digital code corresponding to ordinary standards or specifications such as, for example, the international standard ICE 61131 or the international standard ICE 61499.

[0027] It is contemplated to perform an analysis of the 3D structure to be fabricated so as to find so-called critical areas within the 3D structure to be fabricated or within the layers of the 3D structure to be fabricated.

[0028] In this analysis, in particular, when applying the current layer, areas where there is a risk of defects occurring in the 3D structure to be fabricated are classified as critical areas. In this case, a defect in the 3D structure to be fabricated means that a crack or misalignment occurs in an area or sub-area of the 3D structure to be fabricated in one or more layers.

[0029] The area where the sub-structure of the 3D structure to be fabricated is directly applied onto the surface of the substrate is classified as a critical area in this case because insufficient adhesion may occur between the sub-structure to be applied and the substrate. In this case, the substrate is the surface on which the 3D structure to be fabricated is constructed layer by layer and is also called the shaping area or shaping bed of the 3D printer.

[0030] Such critical areas are also areas where substructures of the 3D structure to be fabricated should be applied to smaller substructures of the layers beneath them. Such small substructures arise, for example, when the dimensions of substructures stacked in layers are so small that, for example, the laminated structure of these substructures can only be expected to have low mechanical strength. For example, substructures with the smallest possible dimensions, ranging from within a range of 0.1 mm in length and width to a range of 5 mm or more in length and width, will have such low strength. These dimensions depend on the molding material, the processing speed of the molding material, and the fluid properties. Furthermore, such critical areas may comprise part of the current layer, or even the entire layer, for example, if the 3D structure to be fabricated is difficult or complex.

[0031] In this case, the length does not, of course, need to be the same as the width of the substructure. In particular, even long or very narrow substructures within the specified dimensions will also have low mechanical strength during construction. In this case, the orientation of such thin and long structures is also crucial. For example, if an elongated substructure with dimensions of 20 mm in length and 0.3 mm in width has a longitudinal extension in the direction in which the 3D printer's working mechanism moves across the build area, problems will arise in the layer structure, for example, if the speed at which the 3D printer's working mechanism moves across the build area is too high, problems will only occur at the beginning and end of this substructure.

[0032] Such working tools for 3D printers include scraping elements such as squeegees, blades, or vibrating blades.

[0033] This elongated substructure, having its longitudinal extension at a 90-degree angle to the direction in which the 3D printer's working means is moved across the build area, should be oriented and constructed layer by layer, When the movement speed of the 3D printer's working mechanism across the build area is too high, problems arise in layer construction along the entire region of this elongated substructure.

[0034] Another important area is where the substructure of the 3D object to be fabricated is applied to a base that does not provide sufficient support if the movement speed of the 3D printer's working means across the build area is too high.

[0035] One such substrate is a particulate material. In this case, after constructing one of the multiple layers of the 3D structure to be fabricated, a substructure is fabricated at a certain location on the particulate material by selective solidification or adhesion of the particulate material at the location of the substructure, because the substructure does not yet have a connection or connection point with the 3D structure to be fabricated. In this case, such a connection to the 3D structure is established only during the 3D printing process in a later layer that is fabricated and has a greater distance from the build bed.

[0036] Furthermore, it is possible to specify additional criteria for important areas and include them in the analysis.

[0037] During the analysis of the 3D structure to be fabricated, if a critical area in the structural construction is recognized, data or movement data for this recognized critical area is generated, stored, or documented. This data includes at least one piece of information regarding the location or position of the recognized critical area. Thus, its position on or across the structural bed is known in corresponding coordinates (e.g., the X, Y, and Z directions of the coordinate system on the build domain).

[0038] Furthermore, this data may include, in addition to the X and Y coordinates of a significant area or sub-area manufactured in the current layer, information regarding the dimensions or extent of the sub-structure, referred to as a bounding box, which includes, for example, the track curve or outer contour of the sub-structure and / or its length and width.

[0039] The intention is to transmit analysis data or movement data, i.e., recognized critical regions, to the control unit. Such transmission of data for recognized critical regions can be done to the control unit independently or together with data that the control unit uses to control the layer-by-layer formation of the 3D structure.

[0040] The control unit is intended to compare the current position of the 3D structure being built with positional data of key areas, and if a match is detected, to change the movement speed of the 3D printer's working means across the build area.

[0041] This change could result in a significant decrease in movement speed in important or particularly important areas. Alternatively, this change could result in a smaller decrease in movement speed in less important areas.

[0042] In addition to changes in the moving speed, the aim is to control the discharge of the substrate, i.e., the amount of particulate substrate applied to each drive meter across the build area, or to adapt the amount of particulate substrate to the changing moving speed. In this way, the height of the applied particulate substrate is adjusted or kept constant.

[0043] Furthermore, such comparisons are performed using lead time, and it is intended that the movement speed of the 3D printer's working tool across the build area decreases just before reaching a critical area. In this case, a time can be determined relative to this lead time. Alternatively, the distance over which the movement speed decreases before reaching a critical area can be determined.

[0044] The design aims to prevent a reduction in movement speed if the movement speed of the 3D printer's working tools across the build area falls below a specified speed limit.

[0045] Similarly, the control unit is intended to recognize when to leave such critical areas by comparing the current position of the 3D structure being built with the position data of the critical areas. In this case, the movement speed of the 3D printer's working means across the build area can be changed again, for example, increased. Such an increase in movement speed can be continued until the movement speed of the 3D printer's working means reaches the speed it was moving at before reaching the critical area. Alternatively, the increase in movement speed can be continued until the maximum possible movement speed of the working means is reached.

[0046] Furthermore, during the analysis of critical areas, the probability of defects occurring in these critical areas in the final 3D product is to be determined. If this probability is high, the movement speed of the 3D printer's working mechanism across the build area is to be reduced compared to when the probability is lower. Thus, particularly sensitive areas of the 3D structure can be reliably fabricated, while in non-sensitive areas, a smaller reduction in the movement speed of the working mechanism allows for a time advantage in the fabrication of the 3D structure.

[0047] Furthermore, it is intended that the so-called substrate coating parameters be adjusted accordingly in response to changes in the movement speed of the work means. In this case, for example, the amount of particulate substrate to be coated in a layer is affected depending on the speed. Therefore, the amount of particulate substrate to be coated per unit time increases as the speed increases in order to achieve a certain layer thickness of particulate substrate, and vice versa.

[0048] The features and advantages of the present invention described above can be better understood and appreciated after careful consideration of the following detailed description of preferred, non-limiting exemplary embodiments of the present invention, along with the relevant drawings. [Brief explanation of the drawing]

[0049] [Figure 1] Exemplary process flow of the method according to the present invention for fabricating 3D structures using a 3D printer [Modes for carrying out the invention]

[0050] Figure 1 shows an illustrative process flow of the method according to the present invention for fabricating 3D structures using a 3D printer.

[0051] Step 1 begins the process of creating a 3D structure or layers of a 3D structure using a 3D printer.

[0052] In the second step, the analysis of the 3D structure to be fabricated is carried out to identify so-called critical areas within the 3D structure or within the layers of the 3D structure to be fabricated. The data used to fabricate the 3D structure that forms the basis of the analysis can be generated, for example, using a computer-aided design system and exists in a machine-readable form such as digital code.

[0053] This analysis identifies critical areas, i.e., mechanically susceptible areas (where substructures may crack or shift as described above). In step 3, positional data is determined and stored for these areas. For example, this positional data can correspond to the X, Y, and Z directions of the build area's coordinate system. Alternatively, one X-coordinate and one Y-coordinate across the build area, as well as the corresponding layer number where the identified critical areas are located, can also be determined.

[0054] If, in step 2, no important regions are determined during the analysis of the 3D structure to be fabricated, the method for fabricating the 3D structure ends in step 6. In parallel, 3D printing is performed and controlled by a control unit that converts the machine-readable data produced by the computer-aided manufacturing system and controls the 3D printing.

[0055] The position data determined in step 3 is transmitted to a control unit that controls 3D printing, such as a programmable logic controller (SPS), and incorporated according to the 3D printing control sequence.

[0056] In Step 4, during the 3D printing process, if a location identified as a critical area in the previous analysis is reached, In step 5, the movement speed of the 3D printer's working means across the build area is changed or reduced by the control device.

[0057] This decrease in the working device's speed may occur as early as just before reaching the critical area in step 5. After leaving the critical area, the working device's speed is increased again in step 5. This increase in speed may also be accompanied by a time delay.

[0058] The speed of the working means is increased, for example, until it reaches the speed driven before reaching the critical area or the maximum possible speed.

[0059] In parallel with the control unit controlling the movement speed of the 3D printer's working means across the build area, parameters related to changes in movement speed, such as the amount of particulate material to be applied to a layer per unit time, or the pressure of the blade (which can attract and / or solidify the particulate material), are adjusted by the control unit according to the speed.

[0060] Alternatively, the movement speed of the work instrument can be reduced by the control unit for areas that spatially extend far beyond the critical area.

[0061] Similarly, if one or more important areas are found in the analysis within a particular layer, it is possible to reduce the speed of the work being done on that entire layer.

[0062] Furthermore, for example, if a certain number of critical areas have been analyzed to ensure more continuous movement of the 3D printer's working tool across the build area, it is also possible to reduce the working tool's movement speed across the entire current layer.

[0063] Once 3D printing is complete, the process for creating the 3D structure ends in step 6.

[0064] For example, the movement speed of the 3D printer's working means across the build area can be 1000 mm / s, while the movement speed of the working means within or in front of a critical area is reduced to 300 mm / s. [Explanation of symbols]

[0065] 1 start 2. Analysis of the 3D structure to be created 3. Determining and storing location data 4. 3D printing 5. Adjusting movement speed 6. End

Claims

1. 1. A method of fabricating a 3D structure, comprising: The method comprises using provided data of a 3D structure to be produced to build a 3D structure layer by layer on a build area using a 3D printer, The data of the 3D structure to be created is analyzed to identify critical regions within the 3D structure to be created; and and at least temporarily reducing the speed of movement of a working implement of the 3D printer across the build area when the determined critical area in the creation of the 3D structure is reached. A method characterized by:

2. The critical areas are those areas where the substructures of the 3D structure to be produced are applied directly onto the surface of the substrate, and / or The critical areas are those areas where substructures of the 3D structure to be created are applied onto smaller substructures of the underlying layer, and / or The critical areas are those where the substructure of the 3D structure to be created is applied on a base that does not provide sufficient support.

2. The method of claim 1 .

3. 3. A method according to claim 1 or 2, wherein location data is generated and stored for the areas of interest found.

4. The method according to claim 3, wherein the position data includes information on a layer number and one X coordinate and one Y coordinate in a coordinate system on the build area, or the position data includes one X coordinate, one Y coordinate, and one Z coordinate in a coordinate system on the build area.

5. The reduction in the movement speed of the working implement of the 3D printer is terminated after leaving the critical area, and The current speed of movement of the work vehicle before it reached the critical area is restored, or 5. The method according to claim 1, wherein the maximum possible travel speed of the working means is reached.

6. 6. The method according to claim 1, wherein the reduction of the movement speed of the working means is carried out before the critical area is reached, and a distance or time unit for this is preset.

7. 7. The method according to claim 3, wherein the generated position data is transmitted to a control unit, which controls the 3D printing with the provided data of the 3D structure to be generated and controls the movement speed of the working means with the position data.

8. 8. The method according to claim 7, wherein the control unit performs adjustment of parameters for controlling the amount of particulate substrate to be applied per unit time in parallel with controlling the movement speed of the working means, thereby ensuring a uniform layer thickness of the particulate substrate.

9. 9. The method according to any one of claims 1 to 8, characterized in that the area of ​​interest has dimensions with a length of less than 5 mm and / or a width of less than 5 mm, in particular dimensions with a length of less than 1 mm and / or a width of less than 1 mm.

10. 10. The method according to any one of claims 1 to 9, wherein the data and the position data of the 3D structure to be created are provided in a machine-readable format.

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