A method for fabricating 3D structures in which the working means, particularly the squeegee's movement speed, 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 parts or workpieces 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 modeling material, also referred to as the shaping 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 modeling material, to a so-called modeling area to form a layer composed of a non-curable particulate material. · A step of selectively curing the applied layer composed 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 powdered 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 adjusted 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 faster and faster, cracks or displacements can occur in sub-areas of the layer that is currently to be constructed or the layer beneath 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 ensuring a reliable and accurate construction of the layer by the 3D printing method.

[0022] In particular, in important areas where cracks or displacements can occur in the sub-structure of the 3D structure in the layer that is currently to be constructed or the layer beneath 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 developments 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, particularly 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 for controlling 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 three-dimensional 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 analyze the 3D structure to be fabricated so as to find so-called critical regions within the 3D structure to be fabricated or within a layer of the 3D structure to be fabricated.

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

[0029] The regions to be directly coated on the surface of the sub-structure of the 3D structure to be fabricated are, in this case, classified as critical regions because insufficient adhesion may occur between the sub-structure to be coated and the substrate. In this case, the substrate Material The regions to be directly coated on the surface of the sub-structure of the 3D structure to be fabricated are, in this case, classified as critical regions because insufficient adhesion may occur between the sub-structure to be coated and the substrate. In this case, the substrate Material The regions to be directly coated on the surface of the sub-structure of the 3D structure to be fabricated are, in this case, classified as critical regions because insufficient adhesion may occur between the sub-structure to be coated and the substrate. In this case, the substrate MaterialThe build area is the surface on which the 3D structure to be created is built in layers, and is also called the build bed or build area of ​​a 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] 3 D printer In the field of modeling The means of operation are moving. vinegar An angle of 90 degrees with respect to the direction. long This elongated substructure has a portion that extends in the direction of the hand. of , orientation doIf it should be built layer by layer, 3 D printer In the field of modeling When the movement speed of the workpiece is too high, problems arise in layer construction along the entire region of this elongated substructure.

[0034] Another important area is the substructure of the 3D structure to be fabricated. 、3D printer In the field of modeling This is an area where the coating is applied to a base that does not provide sufficient support when the movement speed of the work tool is too high.

[0035] Such One of the foundations This is a particulate material for fabrication. In this case, after constructing one of the multiple layers of the 3D structure to be fabricated, the particulate material is used. molding At a certain location on the material, a substructure is formed, and at the location of this substructure, particulate molding When fabricated by selective solidification or bonding of materials, the above situation arises 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 has a greater gap to the build bed and is to be fabricated later.

[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 compares the current position of the 3D structure with the position data of important regions, and if a match is detected, 、3 D printer In the field of modeling The intention is to change the movement speed of the work instrument.

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

[0042] Change in movement speed Change In addition, the discharge of the substrate, i.e., the molding area. Above Controlling the amount of particulate substrate applied to each drive meter, or controlling the amount of particulate substrate 、 The aim is to adapt to changing movement speeds. In this way, the height of the coated particulate substrate is adjusted or kept constant.

[0043] Furthermore, such comparisons In advance, in terms of time Acid 、3 D printer In the field of modeling The movement speed of the work instrument is also intended to decrease just before it reaches a critical area. In this case, Do it in advanceThe time can be determined. Alternatively, the distance over which the speed of movement decreases before reaching a critical area can be determined.

[0044] 3 D printer In the field of modeling If the movement speed of the work instrument falls below the specified speed limit, it is intended that this will not result in a reduction in movement speed.

[0045] Similarly, the control unit is intended to recognize when to leave such critical areas by comparing the current position of the 3D structure with the positional data of the critical areas. 、3 D printer In the field of modeling The movement speed of the workpiece can be changed again, for example, by increasing it. Such an increase in movement speed can be continued until the movement speed of the 3D printer's workpiece reaches the speed it was moving at before reaching a critical area. Alternatively, the increase in movement speed can be continued until the maximum possible movement speed of the workpiece is reached.

[0046] Furthermore, during the analysis of important areas, That The probability of defects occurring in the 3D final product is to be determined. If this probability is high, the movement speed of the 3D printer's working means across the build area is to be reduced compared to when the probability is lower. Therefore, the 3D structure in particular delicate It is possible to reliably fabricate a specific subregion, and in doing so, delicate In areas that are not part of the region, the movement speed of the working means of Smaller decrease but This enables a time advantage in the fabrication of 3D structures.

[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, namely areas susceptible to mechanical damage (where substructures may crack or become misaligned, 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 domain coordinate system. Alternatively, the build domain The above One X-coordinate and one Y-coordinate, as well as the number of the corresponding layer in which the important region found is 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 3D printer In the field of modeling working means movement The dynamic speed 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] Control unit 、3 D printer In the field of modeling In parallel with controlling the movement speed of the work instrument, 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 、3 D printer In the field of modeling To ensure more continuous movement of the work instrument, it is also possible to reduce the movement speed of the work instrument for the entire current layer if a certain number of critical areas are being analyzed.

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

[0064] In one example... 、3 D printer In the field of modeling The travel speed of the working means can be 1000 mm / s, while the travel 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. A method for fabricating a 3D structure, In a method for constructing a 3D structure in layers on the build area using a 3D printer, using provided data of the 3D structure to be manufactured, The data of the 3D structure to be fabricated is analyzed, and important areas within the 3D structure to be fabricated are identified, and these important areas are mechanically susceptible to damage, such as areas where cracks or displacements may occur in the substructure, and When a critical region identified during the fabrication of a 3D structure is reached, the movement speed of the 3D printer's working mechanism within the build area decreases, at least temporarily. In that case, the means of work is a scraping element, and In this case, the important area has dimensions with a length of less than 5 mm and / or a width of less than 5 mm, or dimensions with a length of less than 1 mm and / or a width of less than 1 mm. Location data is generated and stored for the identified important regions. The generated position data is transmitted to a control unit, which controls 3D printing using the provided data of the 3D structure to be manufactured, and controls the movement speed of the workpiece using the position data. The control unit, in parallel with controlling the movement speed of the work means, adjusts parameters to control the amount of particulate material to be applied to the build area per unit time, thereby ensuring a uniform layer thickness of the particulate material. A method characterized by the following:

2. The important areas are the areas where particulate material is directly applied to the build area at the location of the substructure of the 3D structure to be fabricated, and / or The critical area is the region where particulate material is applied to a base made of particulate material, at the location of the substructure of the 3D structure to be fabricated. The method according to feature 1.

3. The method according to 1 or 2, characterized in that the position data includes information on the layer number and one X coordinate and one Y coordinate in the coordinate system on the build area, or the position data includes one X coordinate, one Y coordinate and one Z coordinate in the coordinate system on the build area.

4. The reduction in the movement speed of the 3D printer's working tool is terminated after it leaves the critical area, and The movement speed of the work instrument is restored to the movement speed before it reached the critical area, or The method according to any one of claims 1 to 3, characterized in that the maximum possible travel speed of the working means is reached.

5. The method according to any one of claims 1 to 4, characterized in that the reduction in the movement speed of the working means is performed before reaching a critical area, and a distance or time unit for this is predetermined.

6. The method according to any one of claims 1 to 5, characterized in that the data and positional data of the 3D structure to be fabricated are provided in a machine-readable format.

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