Fused deposition 3D printing method considering zone performance

Abstract

The application discloses a fused deposition 3D printing method considering regional performance, and is realized through internal and external regional segmentation and layering algorithm and internal regional segmentation and variable density filling algorithm, wherein the internal and external regional segmentation and layering algorithm is to divide the printing model into two parts of an external contour and an internal region, the adaptive layering algorithm is used for the external contour to ensure the side printing precision, the minimum line width printing is adopted for the upper and lower surfaces to improve the precision of the upper and lower surfaces; the internal region is printed by using the superimposed thickness of the adaptive layering algorithm to improve the printing efficiency. The internal regional segmentation and variable density filling algorithm is to divide the regions according to the stress distribution of the printing model, and then to fill the density according to the stress size of the regions, so as to improve the stress distribution of the printed part, reduce the maximum stress of the printing model, and improve the mechanical properties of the printed part.

Description

Technical Field

[0001] This invention belongs to the field of 3D printing technology, specifically relating to a fused deposition modeling 3D printing method that takes into account regional performance. Background Technology

[0002] 3D printing technology has undergone more than 30 years of development since its inception. Currently, there are many 3D printing technologies, mainly categorized as selective laser melting (SLM), selective laser sintering (SLS), direct laser sintering (DLS), electron beam melting (EFL), fused deposition modeling (FDM), and selective thermal sintering (STS). FDM has developed the most rapidly and has the widest range of applications, making it the most widely used printing technology in 3D printers. However, it is undeniable that FDM has many drawbacks, such as low precision and low strength of printed parts.

[0003] First, due to the limitations of fused deposition modeling (FDM) technology, the step effect is an unavoidable drawback, significantly impacting the accuracy of printed parts. Therefore, reducing the step effect is one of the key research areas. Second, studies have shown that the strength of printed parts is related to the infill density and structure within the part. Higher infill density results in higher strength, but also requires more material. Therefore, improving the mechanical properties of printed parts without increasing material consumption is a current research focus.

[0004] Currently, to improve accuracy, adaptive layering is mainly used instead of traditional equal-thickness layering. This not only reduces the impact of the step effect on accuracy but also eliminates the dimensional deviation caused by equal-thickness layering. However, if the initial layer thickness and the final layer thickness are too large, the printed linewidth will also be large, and the accuracy of the upper and lower surfaces will also be reduced. In terms of improving mechanical properties, the mechanical properties of the printed parts are mainly improved by changing the internal filling shape. However, for irregular plates, there are still problems of excessive stress distribution difference and excessive local stress. Based on this, a fused deposition modeling method that considers regional performance is proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a fused deposition modeling (FDM) 3D printing method that takes into account regional performance, thereby solving the problems of excessive stress distribution differences and excessive local stress in existing irregular plates.

[0006] The technical solution adopted in this invention is a fused deposition modeling 3D printing method considering regional performance, and the specific operation steps are as follows:

[0007] Step 1: Save the 3D model of the printed part generated by the 3D modeling software as an STL file for slicing and G-code file generation;

[0008] Step 2: Perform the first region segmentation and layering processing on the STL format file. By reading the outer contour of the STL model and performing offset processing, the outer contour portion is obtained. An adaptive layering algorithm is used to layer the sides of the outer contour, and the top and bottom surfaces are printed with minimum layer thickness and minimum line width to achieve optimal print accuracy. For the internal areas after removing the outer contour, an adaptive layering stacking thickness is used to layer them to improve printing efficiency.

[0009] Step 3: Perform a second region segmentation and fill path determination on the STL format file. Perform a stress analysis on the entire part, and based on the stress distribution, segment the internal region (region n). Then, determine the fill density based on the stress magnitude in each region.

[0010] Step 4: Perform path planning and set printing parameters, then generate a G-code file and print it.

[0011] The invention is further characterized in that,

[0012] Step 2 is as follows:

[0013] The existing STL file was analyzed, and the contour offset algorithm was used to offset the side contour of the 3D model drawing by an offset distance of C. a C a The extrusion linewidth is set to the minimum thickness for printing, and then the upper and lower surfaces are adjusted by layer height h. min Perform layering, h min This is the minimum thickness that the printer can print.

[0014] The STL file is divided into two parts: Region 1 and Region 2. Region 1 is the outer contour, and Region 2 is the part after removing the outer contour. The thickness of the upper and lower surfaces of Region 1 is h. min h min The minimum printable thickness of the printer is given by the offset distance C for the side profile thickness. a Then, region 1 is adaptively layered based on the curvature of the side profile, with the layer thickness denoted as h. i To achieve optimal printing accuracy, the thicknesses of adjacent layers obtained from layering region 1 are then superimposed, and the resulting thickness must be less than H. max H max To determine the maximum layer thickness that the printer can print, a new set of layer thicknesses H is obtained. c The new layer thickness H c The region 2 is layered to obtain the contour curve of the layered region 2.

[0015] The adjacent layer thickness h is obtained by dividing region 1 into layers. i with h i+1 The superposition is performed to obtain the superposition thickness H. c, H c With H max Comparison, if H c >H max , will H c Subtract layer thickness h i+1 Then update and save H c If H c <H max Then the next layer of thickness h i+2 Continue stacking, then make a judgment, and repeat this step to obtain a new set of layer thicknesses H. c .

[0016] Step 3 is as follows: The contour curve obtained from the area layering in Step 2 is divided into n regions based on the stress distribution. The filling density is determined by the stress magnitude corresponding to each region. Specifically:

[0017] Convert the STL file obtained in step 1 into an X_T format file and import it into ANSYS software for stress analysis to obtain the stress distribution diagram of the model. Export the stress values ​​of each node, divide the difference between the maximum and minimum stress values ​​into n equal parts, and then use the contour curve obtained by the region layering method in step 2 to divide the printed part into n regions. Each region has a corresponding stress value range. Here, the mode of the stress at the nodes in the region is taken to represent the stress value of the region. Under the same load, the stress value of the cuboid plate is different with different infill densities. By changing the infill size d, different stress values ​​σ are obtained. By fitting, the relationship between size and stress is obtained as σ = Ae. -d / t +b, where A,t,b are constants; through the above relationship, the filling size d of each region is obtained, and the variable density filling is completed.

[0018] Step 4 is as follows:

[0019] Based on the layer thickness obtained in step 2 and the fill density obtained in step 3, a path planning algorithm is used to find the optimal printing trajectory. Then, the printing parameters are set by using the layer thickness and the printing trajectory. The upper and lower surfaces of region 1 are printed with the minimum line width. For the internal regions, the line width is matched with the layer thickness for printing. Finally, a G-code file is generated.

[0020] The beneficial effects of this invention are that the fused deposition modeling (FDM) 3D printing method, which considers regional performance, firstly improves printing accuracy and efficiency. The outer contour of the printed model is separated from its internal regions. The outer contour is printed using an adaptive layering method, ensuring printing accuracy on the outer surface of the model. The internal regions of the printed model are layered using adaptive layering thickness, shortening printing time and improving printing efficiency.

[0021] Secondly, it improves the mechanical properties of the printed parts. Within the printed model, the area is divided according to the stress distribution of the printed part, and then density filling is applied based on the stress magnitude of each area. This reduces localized stress in the printed part, making the stress distribution more uniform, minimizing deformation, and improving the mechanical properties of the printed part. Attached Figure Description

[0022] Figure 1 This is a flowchart of the present invention.

[0023] Figure 2 This is a flowchart of the algorithm for segmenting and layering internal and external regions.

[0024] Figure 3 This is a flowchart of the internal region segmentation and variable density filling algorithm.

[0025] Figure 4 This is a comparison chart showing the effects of the traditional slicing algorithm and the slicing algorithm of this invention.

[0026] Figure 5 This is a comparison chart showing the effects of the traditional filling algorithm and the filling algorithm of this invention. Detailed Implementation

[0027] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0028] Example 1

[0029] This invention considers the performance of fused deposition modeling (FDM) 3D printing methods, such as... Figure 1 As shown, the specific operation steps are as follows:

[0030] Step 1: Save the 3D model of the printed part generated by the 3D modeling software as an STL file;

[0031] Step 2: Perform the first region segmentation and layering process on the STL format file;

[0032] Step 3: Perform a second region segmentation and fill path determination on the STL format file;

[0033] Step 4: Perform path planning and set printing parameters, then generate a G-code file and print it.

[0034] Example 2

[0035] like Figure 1 As shown, based on Example 1, step 2 is as follows:

[0036] The existing STL file was analyzed, and the contour offset algorithm was used to offset the side contour of the 3D model drawing by an offset distance of C. a C aThe extrusion linewidth is set to the minimum thickness for printing, and then the upper and lower surfaces are adjusted by layer height h. min Perform layering, h min This is the minimum thickness that the printer can print.

[0037] The STL file is divided into two parts: Region 1 and Region 2. Region 1 is the outer contour, and Region 2 is the part after removing the outer contour. The thickness of the upper and lower surfaces of Region 1 is h. min h min The minimum printable thickness of the printer is given by the offset distance C for the side profile thickness. a Then, region 1 is adaptively layered based on the curvature of the side profile, with the layer thickness denoted as h. i To achieve optimal printing accuracy, the thicknesses of adjacent layers obtained from layering region 1 are then superimposed, and the resulting thickness must be less than H. max H max To determine the maximum layer thickness that the printer can print, a new set of layer thicknesses H is obtained. c The new layer thickness H c The region 2 is layered to obtain the contour curve of the layered region 2.

[0038] The adjacent layer thickness h is obtained by dividing region 1 into layers. i with h i+1 The superposition is performed to obtain the superposition thickness H. c , H c With H max Comparison, if H c >H max , will H c Subtract layer thickness h i+1 Then update and save H c If H c <H max Then the next layer of thickness h i+2 Continue stacking, then make a judgment, and repeat this step to obtain a new set of layer thicknesses H. c .

[0039] Step 3 is as follows: The contour curve obtained from the area layering in Step 2 is divided into n regions based on the stress distribution. The filling density is determined by the stress magnitude corresponding to each region. Specifically:

[0040] Convert the STL file obtained in step 1 to an X_T format file and import it into ANSYS software for stress analysis to obtain the stress distribution diagram of the model. Export the stress values ​​of each node, divide the difference between the maximum and minimum stress values ​​into n equal parts, and then use the contour curve obtained by the region layering method in step 2 to divide the printed part into n regions. Each region has a corresponding stress value range. Here, the mode of the node stresses in the region is taken to represent the stress value of the region. Under the same load, the stress value of the cuboid plate is different with different infill densities. By changing the infill size d, different stress values ​​σ are obtained. By fitting, the relationship between size and stress is obtained as σ = Ae. -d / t +b, where A,t,b are constants; through the above relationship, the filling size d of each region is obtained, and the variable density filling is completed.

[0041] Step 4 is as follows:

[0042] Based on the layer thickness obtained in step 2 and the fill density obtained in step 3, a path planning algorithm is used to find the optimal printing trajectory. Then, the printing parameters are set by using the layer thickness and the printing trajectory. The upper and lower surfaces of region 1 are printed with the minimum line width. For the internal regions, the line width is matched with the layer thickness for printing. Finally, a G-code file is generated.

[0043] Example 3

[0044] Step 1: Obtain the model's STL format file

[0045] Using 3D modeling software, the desired 3D model is obtained, generating an STL format file for subsequent slicing, layering, and area filling.

[0046] Step 2: Inner and outer region segmentation and hierarchical algorithm

[0047] The process of dividing and layering internal and external regions is as follows: Figure 2 As shown, the existing STL file is first analyzed, and the side profile of the STL model is offset using a contour offset algorithm with an offset distance of C. a (C a (The line width extruded when printing at minimum thickness), then the upper and lower surfaces are layered with a layer height h. min (h min The STL file is divided into two parts: Region 1 (outer contour) and Region 2 (the printable model excluding Region 1), based on the minimum thickness the printer can print. Figure 4 As shown on the right. The thickness of the upper and lower surfaces of region 1 is h. min The thickness of the side profile is the offset distance C. aBased on existing adaptive layering algorithms, adaptive layering is performed according to the curvature of the side profile to obtain a set of layer thicknesses h. i This is to obtain the optimal printing accuracy. The thickness h of adjacent layers obtained by dividing region 1 into layers is... i with h i+1 The layers are stacked, with a thickness of H. c , H c With H max (H max Compare H to the maximum layer thickness that the printer can print. c >H max , will H c Subtract layer thickness h i+1 Then save H c If H c <H max Then the next layer of thickness h i+2 Continue stacking, then continue the judgment. Repeat this process to obtain a new set of layer thicknesses H. c The new layer thickness is applied to region 2 to create a layered profile curve for region 2.

[0048] Step 3: Internal Region Segmentation and Variable Density Filling Algorithm

[0049] The process of internal region segmentation and variable density filling algorithm is as follows: Figure 3 As shown, the STL file obtained in step 1 is converted into an X_T format file and imported into ANSYS software for stress analysis to obtain the stress distribution diagram of the model. ANSYS provides stress contour lines for the printed part, clearly showing the range of different stress values ​​in various regions. However, this method results in too many segmented regions, reducing printing efficiency. Therefore, the stress values ​​of the nodes are exported from ANSYS, and the difference between the maximum and minimum stress values ​​is divided into n equal parts (the number of regions to divide the printing area). Then, the contour curve obtained from the region layering algorithm in step 2 is used to segment the printed part into n regions, as shown below. Figure 5 As shown. Each region has a corresponding stress value range. Here, the mode of the nodal stresses within a region represents the region's stress value. For a cuboid plate under the same load, different infill densities result in different stress values. By changing the infill size d (i.e., the size of the infill pattern; the higher the infill density, the smaller the infill size), different stress values ​​σ are obtained. Through fitting, the relationship between size and stress is obtained as σ = Ae. -d / t +b, where A, t, and b are constants (the function type can be changed as long as it conforms to the relationship between stress value and fill size). Using the above relationship, the fill size d of each region is obtained, such as... Figure 5 (As shown on the right). Variable density filling is complete.

[0050] Step 4: Path Planning and Parameter Setting

[0051] Based on the layer thickness and fill density obtained from the inner and outer region segmentation and layering algorithms and the inner region segmentation and variable density filling algorithm, an existing path planning algorithm is used to find the optimal printing trajectory. Then, printing parameters are set based on the layer thickness and printing trajectory. The upper and lower surfaces of region 1 are printed using the minimum line width to improve printing accuracy; for the inner regions, a line width matching the layer thickness can be used for printing. Finally, a G-code file is generated. A comparison of the effects of traditional slicing algorithms and the slicing algorithm of this invention is provided. Figure 4 As shown, the effects of the traditional filling algorithm and the filling algorithm of this invention are compared. Figure 5 As shown.

[0052] contrast Figure 4 Comparing the left and right sides reveals that the printing contour obtained based on the inner and outer region segmentation and layering algorithm takes into account the printing accuracy of the upper and lower surfaces, improving accuracy by reducing the printing linewidth of the upper and lower surfaces. Furthermore, the internal region is printed using the superimposed thickness of the outer contour, ensuring printing accuracy while improving printing efficiency. Figure 5 A comparison of the left and right sides reveals that the internal filling obtained through internal region segmentation and variable density filling algorithms is less effective in the outer areas of the printed part and in areas with smaller contour angles. Figure 5 The middle gear teeth can have a denser filling, thereby improving the mechanical properties of the printed parts.

Claims

1. A fused deposition 3D printing method taking into account the performance of the area, characterized in that, The specific operation steps are as follows: Step 1: save the three-dimensional model diagram of the printed part generated by the three-dimensional modeling software as an STL format; Step 2: perform first regional segmentation and layering processing on the STL format file; The existing STL file is analyzed, the profile offset algorithm is used to offset the side profile of the three-dimensional model graph, and the offset distance is , The minimum thickness printing extrusion line width, then the upper and lower surfaces are layered with layer height , The minimum thickness that the printer can print, the layering is as follows: The STL file is divided into two parts, region 1 and region 2, the region 1 is the outer contour, and the region 2 is the part removed from the outer contour; wherein the thickness of the upper and lower surfaces of region 1 is , the minimum thickness that the printer can print, and the thickness of the side contour is the offset distance ; then the region 1 is adaptively layered according to the curvature of the side contour, and the layer thickness is represented as , to obtain the optimal printing precision; then the adjacent layer thickness obtained by layering the region 1 is superimposed, and the thickness after superimposition is less than , the maximum layer thickness that the printer can print, thereby obtaining a new set of layer thicknesses , the new layer thicknesses are applied to region 2 for layering, and the contour curve after layering of region 2 is obtained; The adjacent layer thickness obtained by layering region 1 With Superimposed to obtain the superimposed thickness , will With If > , will Subtract the layer thickness , then update and save ; If < , then the next layer thickness Continue to superimpose, and then judge again, and execute this step in turn, to obtain a new set of layer thickness ; Step 3: perform second regional segmentation and filling path determination on the STL format file; the specific steps are as follows: The profile curve of the region after layering in step 2 is regionally segmented according to stress distribution, to obtain n a region ， The density to be filled is determined by the stress size corresponding to each region; specifically as follows: The STL file obtained in step 1 is converted into an X_T format file, imported into ANSYS software for stress analysis, and a stress distribution diagram of the model is obtained; the stress values of each node are exported, the maximum stress value and the minimum stress difference value are evenly divided into n parts, then the printed part is regionally segmented by combining the contour curve obtained in step 2 of the region layering method, n regions are obtained, each region has a corresponding stress value range, and here the mode value of the node stress in the region represents the stress value of the region; under the same load, the stress values of the cuboid plates with different filling densities are different, the filling size in the internal filling is changed , different stress values are obtained , the relationship between the size and the stress is obtained by fitting A , t , b is a constant; through the above relationship, the filling size of each region is obtained d , and the variable density filling is completed; Step 4: perform path planning and print parameter setting, then generate a G-code file and print.

2. The fused deposition 3D printing method considering zone performance according to claim 1, characterized in that, Step 4 is as follows: According to the layer thickness obtained in step 2 and the filling density obtained in step 3, a path planning algorithm is used to seek the best printing trajectory, and then the layer thickness and the printing trajectory are used to set the printing parameters. The upper and lower surfaces of region 1 are printed using the smallest line width; for the internal region, layer thickness matching line width is used for printing, and finally a G-code file is generated.

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