An FDM 3D printing method using a sparse and dense drawing method and targeting rod plates

Abstract

The present invention relates to an FDM 3D printing method for rod plates using a sparse-density drawing method, comprising the following steps: (1) using a slicing software to identify the shape of a model and divide it into sparse areas and dense areas; (2) using a plane sparse-density drawing method to increase the density of easily breakable parts and reduce the density of redundant parts; (3) using a spatial sparse-density drawing method to achieve spatial 3D printing; and by allowing a user to define a sparse-density area in space, the slicing software will repeat the plane sparse-density drawing method on this area. The present invention reduces the printing weight of the model and improves the mechanical properties of the model. By using a spatial sparse-density drawing method to identify and define the sparse-density area of ​​the model or allowing the user to define the sparse-density area, combined with a plane sparse-density drawing method, the printing weight of the model can be effectively reduced and the printing speed of the model can be improved.

Description

Technical Field

[0001] The invention belongs to the technical field of 3D printing, and relates to an FDM 3D printing method that adopts a sparse-dense drawing method and targets rod and plate blocks. Background Art

[0002] The most popular 3D printing technology currently, FDM (fused deposition modeling), uses only a uniform density during the printing process, without considering the stress-bearing areas and overall dimensions of the part. This leaves significant room for improvement in the mechanical properties and weight of parts printed with FDM technology. Some parts of a model have small cross-sectional areas, resembling rods or plates. These areas are prone to fracture if printed at low density. If printed at high density, following the mainstream uniform density printing method, other parts of the model, such as those with concentrated mass and less stress, are prone to mass redundancy.

[0003] At the same time, there is no unified data exchange method between current stress analysis software such as Abaqus and 3D printing slicing software, and the model stress analysis situation cannot be applied to the FDM3D printing process. Summary of the Invention

[0004] In response to the shortcomings of the existing technology, the present invention aims to provide an FDM 3D printing method that adopts the sparse and dense drawing method and targets rod plates, thereby reducing the printing weight of the model and improving the mechanical properties of the model. By allowing the user to mark the sparse and dense areas in the Cura software and combining the plane sparse and dense drawing method, the printing weight of the model can be effectively reduced and the printing speed of the model can be improved.

[0005] The present invention is achieved through the following technical solutions.

[0006] An FDM 3D printing method using a sparse-dense drawing method and targeting a rod plate includes the following steps:

[0007] (1) The slicing software identifies the shape of the model and divides it into sparse areas and dense areas. The identification method is as follows: first, the shape of the part is detected, and the area of ​​all triangles is calculated and extracted by using the numpy-stl library of the Python language to integrate and calculate the total volume of the model; then, the part is sliced ​​along the Z direction according to the conventional XY plane, and the area of ​​each slice and the maximum area of ​​the slice are recorded. The area of ​​each slice and the maximum area are compared, and the slicing software calculates the sparse area and dense area defined by the slice area ratio;

[0008] (2) Use the plane density drawing method to increase the density of the easily broken parts and reduce the density of the redundant parts; the plane density drawing method is as follows: the easily broken parts are the dense area, and the redundant parts are the sparse area. When the nozzle moves from the dense area to the sparse area, the distance between the nozzle movement trajectories will become larger and larger;

[0009] (3) Achieve spatial 3D printing through spatial density drawing; users can define the density area in space, and the slicing software will repeat the plane density drawing in this area.

[0010] Furthermore, in step (2), the nozzle motion trajectory is a straight line, and the distance between the lines is 0-10mm. The straight lines here not only represent the nozzle motion trajectory, but also the accumulation position of the filler in the linear filling method. The filler is located on each straight line. The distance between adjacent straight lines will gradually increase from dense areas to sparse areas. In addition, users can customize the distance between adjacent straight lines in dense or sparse areas using the spatial density drawing method.

[0011] Furthermore, step (2) further includes: calculating the volume of the model, inferring the characteristics of the model, and dividing the model into rods, plates, and blocks; the characteristics of the rod and plate are defined as follows: the rod has very small values ​​in two directions; the plate has a very small value in one direction; the block has a similar value in three directions; the three directions refer to the X direction, the Y direction, or the Z direction respectively;

[0012] For rods and rods in a torsional state, users can set the rod filling method according to the stress state and switch the printing method to non-linear filling.

[0013] For bending deformation of plates, rods, and plates, dense areas are defined where concentrated forces act to increase the density of the force-bearing parts of the parts. The location of the concentrated force is determined by the user through the spatial density drawing method. For bending of plates, the filling method is set to mesh filling in the force-bearing area or the characteristic part of the plate.

[0014] For blocks, reduce the density of the blocks to 15% or 20%. At the same time, combine the sparse and dense painting method to reduce the printing density in the sparse areas of the blocks and increase the density in the dense areas of the blocks.

[0015] Furthermore, for the identification method in which two or three of the rods, plates or blocks exist in the model at the same time: the software first identifies the specific features of the model parts one by one through the feature definition of the rod plate, and then applies the printing method for the rod, plate and block to each part.

[0016] Compared with the prior art, the advantages of the present invention are:

[0017] 1. This invention reduces the printing weight of the model and improves the mechanical properties of the model. By marking the sparse and dense areas in the Cura software by the user and combining the plane sparse and dense drawing method, it can effectively reduce the printing weight of the model and increase the printing speed of the model;

[0018] 2. The present invention adds a stress-bearing part to the model, sets the internal filling method of the stress-bearing part and increases the printing density of the part to improve the mechanical properties of the part;

[0019] 3. Considering the characteristics of the rod plate and the stress conditions of the model, such as tension, compression and torsional deformation, the mechanical properties of the printed parts can be improved by combining sparse and dense drawing methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Print the internal structure diagram of the parts using the density drawing method;

[0021] Figure 2 This is the isometric view of the internal structure of the part printed using the sparse-dense drawing method;

[0022] Figure 3 This is a model diagram for the spatial density drawing method;

[0023] Figure 4 is the cross-section of the plate (using the mesh filling method at the stressed parts);

[0024] Figure 5 This is the isometric view of the cross section of the plate. DETAILED DESCRIPTION

[0025] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0026] An FDM 3D printing method using a sparse-dense drawing method and targeting a rod plate includes the following steps:

[0027] (1) The slicing software identifies the shape of the model and divides it into sparse areas and dense areas. The identification method is as follows: first, the shape of the part is detected, and the area of ​​all triangles is calculated and extracted by using the numpy-stl library of the Python language to integrate and calculate the total volume of the model; then, the part is sliced ​​along the Z direction according to the conventional XY plane, and the area of ​​each slice and the maximum area of ​​the slice are recorded. The area of ​​each slice and the maximum area are compared, and the slicing software calculates the sparse areas and dense areas defined by the ratio;

[0028] (2) Use the plane density drawing method to increase the density of the easily broken parts and reduce the density of the redundant parts; the plane density drawing method is as follows: the easily broken parts are the dense area, and the redundant parts are the sparse area. When the nozzle moves from the dense area to the sparse area, the distance between the nozzle movement trajectories will become larger and larger;

[0029] (3) Achieve spatial 3D printing through spatial density drawing; users can define the density area in space, and the slicing software will slice the area in the XY direction and repeat the plane density drawing along the Z axis.

[0030] Furthermore, in step (2), the movement trajectory of the nozzle is a straight line, and the distance between the straight lines is 0-10 mm.

[0031] The lines here represent not only the nozzle's trajectory but also the location of filler accumulation in the linear fill method. Filler is located along each line. The distance between adjacent lines increases from dense to sparse areas. Furthermore, users can customize the distance between adjacent lines in dense or sparse areas using the spatial density method.

[0032] Furthermore, step (2) further includes: calculating the volume of the model, inferring the characteristics of the model, and dividing the model into rods, plates, and blocks; the characteristics of the rod and plate are defined as follows: the rod has very small values ​​in two directions; the plate has a very small value in one direction; the block has a similar value in three directions; the three directions refer to the X direction, the Y direction, or the Z direction respectively;

[0033] For rods and rods in a torsional state, users can set the rod filling method according to the stress state and switch the printing method to non-linear filling.

[0034] For bending deformation of plates, rods, and plates, dense areas are defined where concentrated forces act to increase the density of the force-bearing parts of the parts. The location of the concentrated force is determined by the user through spatial density drawing. For bending of plates, the filling method is set to grid filling in the force-bearing area or the characteristic parts of the plate.

[0035] For blocks, reduce the density of the blocks to 15% or 20%. At the same time, combine the sparse and dense painting method to reduce the printing density in the sparse areas of the blocks and increase the density in the dense areas of the blocks.

[0036] Furthermore, a method for identifying rods and plates in multiple parts of a model is provided: this method first identifies the specific features of each part of the model one by one through the feature definition of the rod and plate, and further applies the printing method for rods, plates, and blocks to each part.

[0037] Example

[0038] The present invention proposes a novel FDM 3D printing method that applies a sparse-dense drawing method and is targeted at rod and plate panels.

[0039] The method of drawing density is as follows:

[0040] First, the slicing software identifies the model's shape and divides it into sparse and dense areas.

[0041] The recognition method is as follows: first, detect the shape of the part. Since the surface of the part in the stl format is a closed surface, the format represents the shape of a three-dimensional object by describing a series of small triangles on the surface of the model. This method uses the numpy-stl library of the python language to calculate and extract the area of ​​all triangles to integrate and calculate the total volume of the model. Then, slice along the Z direction according to the conventional XY plane, record the area of ​​each slice and the maximum area of ​​the slice, and compare the area of ​​each slice with the maximum area. For example Figure 1 The maximum area is a1 and the minimum area is a2. The software defines sparse and dense areas based on the ratio of the slice area to the average slice area, or the user can define sparse and dense areas using the spatial density method.

[0042] Furthermore, the density of the easily broken parts can be increased and the density of the redundant parts can be reduced by using the sparse and dense drawing method, thereby reducing the quality of the model and improving the mechanical properties of the model. The sparse and dense drawing method of the plane is shown below. Figure 2 As shown, the a1 area is the easily broken part, and the a2 area is the redundant part. This is the sparse and dense grid drawing method shown in the plane. Figure 2 Each line in the diagram represents the nozzle's trajectory. These straight lines conserve nozzle movement time. During movement, the nozzle's trajectory follows the path of abdc. Lines ab and dc are parallel or nearly parallel. As the nozzle moves in the direction f, from dense to sparse areas, the distance between the lines increases. This distance is limited to a certain range, typically 0-10mm. The specific distance depends on the current mainstream Cura slicing software.

[0043] The density and sparseness of space:

[0044] By defining the area in space by the user, the slicing software will repeat the plane density drawing method in this area. Figure 2 A2 is a spherical area. By moving the spherical area A2 to the model A1 with the mouse, the part of the model that contacts the spherical area can be customized by the user as a sparse area or a dense area.

[0045] After defining the density area, the printer will repeat the plane density drawing method in each direction of the Z-axis slice from the xy direction according to the mark of the density area.

[0046] The printing methods for the three characteristics of the rod plate and the model under tension, compression and torsion are as follows:

[0047] By calculating the volume of the model, the characteristics of the model are inferred and the model is divided into rods, plates and blocks.

[0048] The characteristics of rod and plate are as follows: rods are characterized by small values ​​in two directions. Plates are characterized by small values ​​in one direction. Blocks are characterized by similar values ​​in three directions (the three directions refer to the X, Y, or Z directions).

[0049] For rods or rods in a torsional state, users can set the rod fill method based on the load state. This method switches the printing method to a non-linear fill method, such as a grid printing method. Non-linear fill methods include grid fill and honeycomb fill. The non-linear fill method used in this method is primarily grid fill.

[0050] This method also avoids linear infill along the rod's axis. Furthermore, during printing, the density of the torsion zone is set to 100% or higher than the overall average density of the model. Linear infill along the axis is avoided because it creates a linear internal structure within the rod. Linear infill directed parallel or nearly parallel to the rod's axial direction can easily loosen the internal linear infill structure when the part is torsionally subjected.

[0051] For bending deformation of plates, bars, and panels (including models subjected to tension or compression, referred to as tension and compression), this method defines a dense region where the concentrated force is applied, increasing the density of the stressed area. This effectively reduces the risk of fracture in this area. The location of the concentrated force is determined by the user using a spatial density drawing technique.

[0052] To deal with the bending of the plate, set the filling method to grid filling in the stress area or the characteristic part of the plate to avoid the straight line filling direction of the density drawing method being parallel to the stress direction.

[0053] For blocks, the method of the present invention reduces the density of the blocks to 15% or 20%, and at the same time combines the above-mentioned sparse and dense drawing method to reduce the printing density in the sparse areas of the blocks and increase the density in the dense areas of the blocks.

[0054] Method for identifying rod plates in multiple parts of the model:

[0055] For the case where two or three of the following types of rods, plates or blocks exist in the model at the same time, the software first identifies the specific features of each part of the model one by one through the above feature recognition method, and then further applies the printing method for rods, plates, and blocks to each part.

[0056] Again, using the Python numpy-stl library, we calculated and extracted the areas of all triangles, integrating them to determine the total volume of the model. We then sliced ​​the model along the Z direction, following the conventional XY plane. The area of ​​each slice and the maximum area of ​​each slice were recorded, and the average slice area was calculated. The ratio of the slice area to the average slice area was used to define rods and blocks. This method, similar to the rod and block characteristics defined above, combined the calculated area ratios to identify possible rod and block locations.

[0057] At the same time, combined with the spatial density drawing method, the three characteristics of the rod plate and the printing method for the model under tension, compression and torsion are implemented according to the possible characteristics of the rod plate.

[0058] The above description is only a preferred embodiment of the present invention and does not limit the implementation mode and protection scope of the present invention. For those skilled in the art, it should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the description and illustrations of the present invention should be included in the protection scope of the present invention.

Claims

1. An FDM 3D printing method using a sparse and dense drawing method and targeting a rod plate, characterized in that: The steps include: (1) The slicing software identifies the shape of the model and divides it into sparse areas and dense areas. The identification method is as follows: first, the shape of the part is detected, and the area of ​​all triangles is calculated and extracted by using the numpy-stl library of the Python language to integrate and calculate the total volume of the model; then, the model is sliced ​​along the Z direction according to the conventional XY plane, and the area of ​​each slice and the maximum area of ​​the slice are recorded, and the area of ​​each slice and the maximum area are compared. The slicing software will define sparse areas and dense areas by the ratio of the slice areas, or the user can customize sparse areas and dense areas by using the spatial density drawing method; (2) Use the plane density drawing method to increase the density of the easily broken parts and reduce the density of the redundant parts; the plane density drawing method is as follows: the easily broken parts are dense areas, and the redundant parts are sparse areas. The nozzle moves from the dense area to the sparse area, and the distance between the nozzle movement trajectories will become larger and larger within a certain range; By calculating the model volume, the model characteristics are inferred and the model is divided into rods, plates, and blocks. The characteristics of rods and plates are defined as follows: rods have very small values ​​in two directions; plates have a very small value in one direction; blocks have similar values ​​in three directions; the three directions refer to the X direction, Y direction, or Z direction. For rods and rods in a torsional state, users can set the rod filling method according to the stress state and switch the printing method to non-linear filling. For bending deformation of plates, rods, and plates, dense areas are defined where concentrated forces act to increase the density of the force-bearing parts of the parts. The location of the concentrated force is determined by the user through spatial density drawing. For bending of plates, the filling method is set to grid filling in the force-bearing area or the characteristic parts of the plate. For blocks, reduce the density of the blocks to 15% or 20%. At the same time, combine the sparse and dense painting method to reduce the printing density in the sparse areas of the blocks and increase the density in the dense areas of the blocks. (3) Achieve spatial 3D printing through spatial density drawing; users can define the density area in space, and the slicing software will repeat the plane density drawing in this area.

2. The FDM 3D printing method using a sparse and dense drawing method and targeting a rod plate according to claim 1, characterized in that: In step (2), the movement trajectory of the nozzle is a straight line, and the distance between the straight lines is 0-10mm.

3. The FDM 3D printing method using a sparse and dense drawing method and targeting a rod plate according to claim 1, characterized in that: Identification method for models with two or three of the following: rods, plates, or blocks: The software first identifies the specific features of each model part one by one through the feature definition of the rod plate, and then applies the printing method for rods, plates, and blocks to each part.

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