Unit cell and 3D printing structure

Abstract

The utility model provides a unit cell and a 3D printing structure, the unit cell is used for 3D printing, the unit cell comprises a plurality of faces, the areas of all the faces are equal, every two adjacent faces are perpendicular to each other, and every two opposite faces are parallel to each other; wherein each face is provided with a containing cavity, and each containing cavity is provided with a vertex and a plurality of supporting faces. By means of the unit cell and the preparation method thereof, the unit cell meeting self-supporting performance and isotropy is provided, the 3D printing cost can be reduced, and the 3D printing effect can be improved.

Description

Technical Field

[0001] This application belongs to the field of 3D printing technology, and particularly relates to a unit cell and a 3D printed structure. Background Technology

[0002] 3D printing is an additive manufacturing technology that uses digital model files as a basis and employs special waxes, powdered metals or plastics and other adhesive materials to create three-dimensional objects by printing layers of adhesive materials.

[0003] In related technologies, to avoid using redundant support structures inside 3D printed structures, a lattice structure is used to fill the interior of the 3D printed structure during the printing process. This increases the infill density and achieves the required strength. However, this method increases printing costs and affects the 3D printing results. Utility Model Content

[0004] This application provides a unit cell and 3D printing structure to solve the problems of high cost and poor effect of 3D printing.

[0005] This application provides a unit cell for 3D printing. The unit cell includes multiple faces, each face having an equal area. Adjacent faces are perpendicular to each other, and opposite faces are parallel to each other. Each face has a receiving cavity, and the receiving cavity has a vertex and multiple supporting surfaces.

[0006] In some embodiments, each face comprises a rectangular face; or, each face contains cavities of the same volume; or, the cavity comprises a square pyramid; or, a plurality of cavities have the same vertex.

[0007] In some embodiments, each support surface extends from the vertex along the diagonal direction of the receiving cavity.

[0008] In some embodiments, each support surface extends from the vertex along the midline direction of the corresponding surface of the receiving cavity.

[0009] In some embodiments, each support surface has a perforated hole.

[0010] In some embodiments, the plurality of unit cells include at least two layers of first unit cells and second unit cells, wherein the accommodating cavity of the first unit cell is connected to the accommodating cavity of the second unit cell.

[0011] In some embodiments, if the projection of the second cell is located within the projection range of the first cell along the arrangement direction of the first cell and the second cell, then the supporting surface of the second cell toward the first cell and several surfaces of the second cell perpendicular to the first cell both extend into the receiving cavity of the first cell toward the second cell.

[0012] In some embodiments, if the second cell is located in the vertical direction of the first cell, then two faces of the second cell perpendicular to the first cell are selected and extend into the receiving cavity of the first cell facing the second cell; if the second cell is located in the horizontal direction of the first cell, then one face of the second cell perpendicular to the first cell is selected and extend into the receiving cavity of the first cell facing the second cell.

[0013] Secondly, embodiments of this application provide a 3D printed structure, the 3D printed structure including an outer contour layer and an inner filling layer, wherein the inner filling layer is a unit cell as described in any of the above claims.

[0014] In some embodiments, the cell filling density ranges from 10% to 100%.

[0015] In some embodiments, the fill density near the outer contour layer is greater than the fill density away from the outer contour layer, and the size of the cell near the outer contour layer is smaller than the size of the cell away from the outer contour layer.

[0016] In some embodiments, the filling density and size of the unit cell are set according to the field of influence of the object to be printed.

[0017] The unit cell provided in this application embodiment includes multiple faces, each face having an equal area, adjacent faces being perpendicular to each other, and opposite faces being parallel to each other; wherein each face has a receiving cavity, and the receiving cavity has a vertex and multiple supporting surfaces. The unit cell can satisfy self-support and isotropy, thereby enhancing the strength of the 3D printed structure of the object to be printed without increasing printing costs. Using unit cells for 3D printing can improve the 3D printing effect. Attached Figure Description

[0018] Figure 1A This is a schematic diagram of the unit cell structure provided in the first embodiment of this application;

[0019] Figure 1B This is a schematic diagram of the unit cell structure provided in the second embodiment of this application;

[0020] Figure 1C This is a schematic diagram of the unit cell structure provided in the third embodiment of this application;

[0021] Figure 1D This is a schematic diagram of the unit cell structure provided in the fourth embodiment of this application;

[0022] Figure 1E This is a schematic diagram of the unit cell structure provided in the fifth embodiment of this application;

[0023] Figure 1F This is a schematic diagram of the unit cell structure provided in the sixth embodiment of this application;

[0024] Figure 2 This is a schematic diagram of the unit cell structure provided in another embodiment of this application;

[0025] Figure 3 This is a cross-sectional schematic diagram of the 3D printed structure provided in the embodiments of this application;

[0026] Figure 4 This is a schematic diagram of the unit cell stacking provided in the embodiments of this application;

[0027] Figure 5 This is a schematic diagram of the structure of the compatible unit cell provided in the first embodiment of this application;

[0028] Figure 6 This is a schematic diagram of the structure of the compatible unit cell provided in the second embodiment of this application;

[0029] Figure 7 This is a schematic diagram of the 3D printing path provided in the embodiments of this application.

[0030] Component symbol description: Cell 10, Face 11, First side 111, Second side 112, Third side 113, Fourth side 114, Fifth side 115, Sixth side 116, First connection line 117, Second connection line 118, Third connection line 119, Receiving cavity 12, Vertex 121, Cavity surface 122, Support surface 123, Cell 20, Side surface 21, 3D printed structure 30, Outer contour layer 31, Internal filling layer 32. Detailed Implementation

[0031] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0032] In the description of this application, it should be understood that the terms indicating orientation or location information are based on the orientation or location information shown in the accompanying drawings and are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, it should be noted that "a plurality of" means two or more, unless otherwise explicitly specified.

[0033] The following will describe some embodiments of this application in detail with reference to the accompanying drawings.

[0034] 3D printing is an additive manufacturing technology that uses digital model files as a basis and employs special waxes, powdered metals, or plastics as bindable materials to create three-dimensional objects by printing layers of these binders. 3D printing technologies can include Stereo Lithography Apparatus (SLA), Selective Laser Sintering (SLS), Fused Deposition Modeling (FDM), 3D Printing (3DP), and Poly-Urethan-Guss (PUG) technology. The specific principles of these 3D printing technologies can be found in related technologies and will not be elaborated upon here. This application uses FDM technology as an example for illustration.

[0035] FDM (Film Making) technology is a layer-based additive manufacturing technique where the printing of the upper layer relies on the support of the lower layer. In related technologies, to avoid using redundant support structures within the 3D printed structure, a lattice structure is used to fill the interior of the 3D printed structure during the printing process. This increases the infill density to achieve the required strength. Infill methods can include uniform infill and adaptive infill. With uniform infill, increasing the infill density to achieve the required strength increases printing costs, and excessively high infill density can affect the smoothness and detail of the model surface, impacting the 3D printing effect. With adaptive infill, for example, a Triply Periodic Minimal Surfaces (TPMS) type lattice can be gradually filled along the Z-axis. However, because TPMS type lattices are represented by globally implicit functions, accurately controlling the gradual filling process of the TPMS type lattice throughout the space is difficult, making it impossible to guarantee the 3D printing effect. For example, a filling structure that satisfies the maximum overhang angle and manufacturability of wall thickness can be automatically generated based on rhombic elements. This filling structure can meet the self-support conditions and achieve adaptive filling inside the 3D printed structure. However, this structure itself is anisotropic, which may cause significant differences in strength in different directions of the 3D printed structure, affecting the 3D printing effect. Another example is a self-supporting hollow filling structure. Redundant internal pillars and pillars that do not meet the self-support constraints are eliminated through sparsity optimization, and the angle between internal pillars is optimized through an overhang angle optimization step, resulting in a better internal self-supporting frame. However, this self-supporting method is based on a rod-like structure, resulting in low printing efficiency when using FDM technology and failing to guarantee the 3D printing effect. Yet another example is adaptive filling based on a porous structure similar to a skeleton or an elliptical hollow structure. However, the above structures suffer from a lack of connectivity, and due to numerous cross-sectional fractures, the printing efficiency when using FDM technology is low, and the 3D printing effect cannot be guaranteed.

[0036] Therefore, it is necessary to provide a unit cell to solve the problems of high cost and poor printing quality in 3D printing.

[0037] Please see Figures 1A to 1F , Figure 1A , 1B 1C, 1D, 1E, and 1F are schematic diagrams of the unit cell structure provided in the embodiments of this application. Figures 1A to 1FAs shown, the unit cell 10 has a cubic structure and contains six faces 11, denoted as faces 11a, 11b, 11c, 11d, 11e, and 11f. Each face 11 has an equal area, adjacent faces 11 are perpendicular to each other, and opposite faces 11 are parallel to each other. For example, faces 11a and 11b are parallel, faces 11c and 11d are parallel, and faces 11e and 11f are parallel. Face 11a is perpendicular to faces 11c, 11d, 11e, and 11f, respectively. In some embodiments, each face 11 includes a rectangular face; for example, each face 11 can be a square. Based on this, the unit cell 10 includes 12 edges, each of equal length. The unit cell 10 includes eight vertices, each vertex being the intersection of three edges.

[0038] In some embodiments, each surface 11 has a receiving cavity 12, and the volumes of the receiving cavities 12 within the multiple surfaces 11 can be the same. The receiving cavity 12 can be a square pyramid with an open bottom, the area of ​​the bottom opening being equal to the area of ​​the surface 11. In some embodiments, the receiving cavity 12 includes a vertex 121 and four cavity surfaces 122, the four cavity surfaces 122 having the same vertex 121, and each cavity surface 122 being an isosceles triangle. In some embodiments, such as Figures 1A to 1F As shown, each of surfaces 11a, 11b, 11c, 11d, 11e, and 11f is provided with a cavity 12, that is, the unit cell 10 includes 6 cavities 12, and the 6 cavities 12 can have the same vertex 121.

[0039] In some embodiments, the receiving cavity 12 is provided with a plurality of support surfaces 123, for example, the receiving cavity 12 is provided with two support surfaces 123. In some embodiments, the two support surfaces 123 have the same shape and area. Each support surface 123 extends from the vertex 121 along the diagonal direction of the receiving cavity 12. Each support surface 123 can be an isosceles triangle. In other embodiments, each support surface 123 extends from the vertex 121 along the midline direction of the corresponding surface 11 of the receiving cavity 12. Taking surface 11a as an example, surface 11a includes four edges. The midpoint of each edge is selected, and the line connecting the midpoints of two opposite edges in surface 11a is determined as the midline of surface 11a. Thus, two midlines of surface 11a can be obtained, and the two midlines are perpendicular to each other. The receiving cavity 12 in surface 11a includes two support surfaces 123, each support surface 123 extending from the vertex 121 along the midline direction of the corresponding surface 11a of the receiving cavity 12. Thus, the two support surfaces 123 are perpendicular to each other. This application embodiment is illustrated by taking the example of each support surface 123 extending from the vertex 121 along the diagonal direction of the receiving cavity 12.

[0040] In some embodiments, the length of the straight line from vertex 121 perpendicular to its opposite side in each support surface 123 is taken as the extension length, and the length of the straight line from vertex 121 perpendicular to the plane containing its bottom in the receiving cavity 12 is taken as the cavity height, with the extension length being the same as the cavity height. For each receiving cavity 12, the opposite side of vertex 121 in one support surface is taken as the first side, and the opposite side of vertex 121 in the other support surface is taken as the second side, with the surface formed by the intersection of the first and second sides coinciding with the surface containing the bottom of the receiving cavity 12. The unit cell 10 provided in this embodiment possesses self-support and isotropy, wherein self-support indicates a good gradual transition between adjacent 3D printing paths, preventing any 3D printing paths from being suspended. Isotropy indicates that the unit cell 10 has the same performance in all directions.

[0041] In some embodiments, each support surface 123 may also have a plurality of perforated holes (not shown in the figure). The shape of the perforated holes may include circles, polygons (e.g., triangles, quadrilaterals, pentagons, etc.), and the shape of the perforated holes may also be irregular shapes, without limitation. The size, position, and number of perforated holes can also be set according to the 3D printing requirements, without limitation. By providing perforated holes in the support surface 123, this embodiment of the application can reduce printing costs while ensuring that the unit cell 10 satisfies self-support and isotropy.

[0042] In some embodiments, the plurality of unit cells 10 includes at least two layers of first unit cells and second unit cells, wherein the receiving cavity 12 of the first unit cell is connected to the receiving cavity 12 of the second unit cell. The second unit cell may be located above, below, or to the side of the first unit cell. The size of the second unit cell may be less than or equal to the size of the first unit cell, or it may be larger than the size of the first unit cell, without limitation herein.

[0043] In some embodiments, if the projection of the second cell is located within the projection range of the first cell along the arrangement direction of the first cell and the second cell, indicating that the size of the second cell is smaller than the size of the first cell, then the support surface 123 of the second cell facing the first cell and several surfaces 11 of the second cell perpendicular to the first cell extend into the receiving cavity 12 of the first cell facing the second cell, until they contact the cavity surface 122 in the receiving cavity 12. The first cell after the compatibility processing is called a compatible cell. The second cell has four surfaces 11 perpendicular to the first cell, and one or two surfaces 11 can be selected from the four surfaces for extension based on the positional superposition information of the first and second cells. Along the arrangement direction of the first cell and the second cell, the projection of the selected surface 11 is inside the projection of the first cell, not at the edge of the projection of the first cell.

[0044] In some embodiments, if the second cell is located in the vertical direction of the first cell, then two faces 11 of the second cell perpendicular to the first cell extend into the receiving cavity 12 of the first cell facing the second cell. If the second cell is located in the horizontal direction of the first cell, then one face 11 of the second cell perpendicular to the first cell extends into the receiving cavity 12 of the first cell facing the second cell. The vertical direction can represent the direction of gravity of the cell 10, and can include above and below; for example, the second cell is located above or below the first cell. The horizontal direction can represent the direction perpendicular to gravity, and can include left, right, front, and rear; for example, the second cell is located to the left of the first cell, or to the right of the first cell, or in front of the first cell, or behind the first cell. For example, when the second cell is located on the side of the first cell (e.g., left, right, front, and rear), since the horizontal surface cannot be supported, one surface 11 is selected from the four surfaces for extension. When the second cell is located above or below the first cell, two surfaces 11 can be selected from the four surfaces for extension. The cell 10 provided in this embodiment is isotropic, and when the first cell and the second cell are connected, by extending the supporting surface 123 of the second cell towards the first cell and several surfaces 11 of the second cell perpendicular to the first cell into the receiving cavity 12 of the first cell towards the second cell, self-support can be achieved when cells of different sizes are stacked together.

[0045] Please see Figure 2 , Figure 2 This is a schematic diagram of the unit cell structure provided in another embodiment of this application. For example... Figure 2 As shown, the unit cell 20 can be a hollow triangular prism structure, including three sides 21, namely the first side, the second side, and the third side, each side 21 being rectangular. The first side, the second side, and the third side, connected sequentially, can form a triangle, wherein the included angle between the first side and the second side can be 60 degrees, and the included angle between the first side and the third side can be 60 degrees. Based on this, the first side, the second side, and the third side, connected sequentially, form an equilateral triangle. By setting the unit cell 20 as a hollow triangular prism structure, and by setting the three sides connected sequentially to form an equilateral triangle, the unit cell 20 can satisfy isotropy.

[0046] In some embodiments, the plurality of unit cells 20 may include at least two layers of third and fourth unit cells, wherein the side edges of the third and fourth unit cells have the same length. When the fourth unit cell is above the third unit cell, the size of the fourth unit cell must be less than or equal to the size of the third unit cell, and the hollow cavity of the third unit cell is connected to the hollow cavity of the fourth unit cell. When the fourth unit cell is below the third unit cell, the size of the fourth unit cell must be greater than the size of the third unit cell, and the hollow cavity of the third unit cell is connected to the hollow cavity of the fourth unit cell. When the fourth unit cell is on the side of the third unit cell, the size of the fourth unit cell may be greater than, less than, or equal to the size of the third unit cell, and the side surface of the third unit cell is connected to the side surface of the fourth unit cell. In this application, when the fourth unit cell is above the third unit cell, a compatibility processing is performed on the third unit cell to obtain a compatible unit cell.

[0047] In some embodiments, if the projection of the fourth unit cell is located within the projection range of the third unit cell along the arrangement direction of the third unit cell, indicating that the size of the fourth unit cell is smaller than the size of the third unit cell, then several side surfaces 21 of the fourth unit cell are extended into the cavity of the third unit cell until the extension length is equal to the side edge length of the third unit cell, so that the compatible third unit cell can support the fourth unit cell. The third unit cell can support four fourth unit cells. This application, by performing compatibility processing on the unit cell 20, enables the lower compatible unit cell to provide support for the adjacent upper unit cell 20, enhancing the strength of the 3D printed structure and improving the 3D printing effect.

[0048] This application uses the example of using unit cell 10 for 3D printing. After determining the structure of unit cell 10, 3D printing can be performed using the aforementioned unit cell 10. Combined with... Figure 3 This application provides a schematic diagram illustrating the cross-sectional view of the 3D printed structure in its embodiments. Figure 3 As shown, the 3D printed structure 30 of the object to be printed includes an outer contour layer 31 and an inner filling layer 32. The outer contour layer 31 is used to define the external shape and size of the object to be printed, and the inner filling layer 32 is used to fill the unit cell 10. The object to be printed can represent the object that needs to be 3D printed, and may include, but is not limited to, automotive parts, aircraft parts, prostheses, orthotics, surgical guides, artworks or sculptures, household items, and toys.

[0049] In some embodiments, the fill density of the unit cell 10 includes 10% to 100%, for example, it can be 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or 100%. The fill density can represent the proportion of the internal space of the 3D printed structure 30 occupied by the unit cell 10. The fill density can be expressed as a percentage; for example, when the fill density of the unit cell 10 is 10%, it means that the internal space of the 3D printed structure 30 is filled by the unit cell 10, which accounts for 10% of the total space.

[0050] In some embodiments, the filling density and size of the cell 10 are both related to the distance from the cell 10 to the outer contour layer 31. For example, the filling density of the cell closer to the outer contour layer 31 is greater than that of the cell farther from the outer contour layer 31, and the size of the cell closer to the outer contour layer 31 is smaller than that of the cell farther from the outer contour layer 31.

[0051] In some embodiments, the filling density and size of the unit cell 10 are set according to the action field of the object to be printed. The action field represents the effect of the field on the object to be printed. The action field includes at least one of a scalar field and a vector field; for example, the action field is a scalar field; another example is a vector field; yet another example is that the action field includes both a scalar field and a vector field. A scalar field can represent a field that can be completely characterized by its magnitude, and may include a temperature field, a density field, a distance field, etc. A vector field can represent a function of one vector corresponding to another, and may include a stress field, an electromagnetic field, etc. This application embodiment uses an example where the action field includes both a scalar field and a vector field, with the scalar field being a distance field and the vector field being a stress field.

[0052] The distance field information describes the geometry and boundaries of the surface of the object to be printed. This information can include the set of minimum distances from any point in the spatial region of the object to its surface. The shape of the spatial region can be a cube, cylinder, etc., and its dimensions can be determined based on the 3D printing system's platform and the size of the object. A 3D printing system, also known as a three-dimensional printer or stereo printer, is a rapid prototyping process that typically uses digital technology to print materials. 3D printing systems are commonly used in mold making, industrial design, and other fields to manufacture models or parts. In some embodiments, the spatial region is discretized into a series of regularly arranged grid points, dividing a continuous space into small voxels (volume pixels), each representing a small region within the spatial region. The boundary coordinates of the object's surface are obtained by parsing the 3D model file. The method for determining the distance field information of the object includes: using a distance function to determine the minimum distance between any voxel in the spatial region of the object and the boundary coordinates of the object; and using these multiple minimum distance values ​​as the distance field information. The distance function may include the Euclidean distance function, the Manhattan distance function, or other distance metrics suitable for a specific application.

[0053] The forces exerted on the object to be printed may vary in different directions. Stress field information is used to describe the stress distribution within the object, where stress can represent the force per unit area. In some embodiments, the stress field information of the object to be printed can be determined by constructing a finite element model and applying boundary conditions to it. For example, first, a finite element model is constructed. To simulate the stress distribution of the object under actual conditions, boundary conditions can be applied to the finite element model. Then, the established finite element model is mathematically discretized, dividing it into a finite number of elements. Finally, by determining the stress and strain of each element, the stress and strain distribution of the entire object to be printed can be obtained. The finite element model accurately reflects the actual physical structure of the object to be printed, including its geometry, material properties, and assembly relationships. Boundary conditions may include displacement constraints, force loads, or pressure.

[0054] In some embodiments, the method for determining the 3D printed structure 30 of the object to be printed may include: determining an initial 3D printed structure of the object to be printed; determining the evaluation index value of each initial cubic mesh in the initial 3D printed structure based on the distance field and stress field; splitting the initial cubic mesh based on the evaluation index value until the initial 3D printed structure meets the splitting termination condition to obtain the 3D printed structure. The initial 3D printed structure contains multiple initial cubic meshes of the same shape and size. The evaluation index values ​​of different initial cubic meshes may be the same or different. For example, the initial cubic mesh with a larger stress value and distance field value is set to have a larger evaluation index value, and the initial cubic mesh with a smaller stress value and distance field value is set to have a smaller evaluation index value. The initial cubic mesh with a large evaluation index value is split to obtain multiple smaller cubic meshes; the evaluation index value of each smaller cubic mesh is determined, and the evaluation index variance of the initial 3D printed structure is determined based on the evaluation index values ​​of the multiple smaller cubic meshes and the evaluation index values ​​of the multiple initial cubic meshes; if the index variance is less than or equal to a preset variance threshold, or the size of the smaller cubic mesh is the minimum size, then the initial 3D printed structure is determined to meet the splitting termination condition. The mesh structure that meets the splitting termination condition is taken as the 3D printed structure. The evaluation index variance is used to describe the degree of difference in the evaluation index of the cubic meshes within the initial 3D printed structure. The smaller the evaluation index variance, the smaller the degree of difference in the evaluation index of the cubic meshes within the initial 3D printed structure; the larger the evaluation index variance, the greater the degree of difference in the evaluation index of the cubic meshes within the initial 3D printed structure. A preset variance threshold can be set according to actual needs and is not limited here. Based on the 3D printed structure 30, the mesh position, mesh size, and adjacency relationship with other cubic meshes of each cubic mesh can be determined. Based on the distance field and stress field of the object to be printed, this application obtains an adaptive cell filling method, which can optimize the internal mesh structure of the 3D printed structure 30, thereby enhancing the strength of the 3D printed structure 30 corresponding to the object to be printed and improving the 3D printing effect without increasing printing costs.

[0055] In some embodiments, the 3D printed structure 30 includes multiple cubic meshes, which have the same shape but different sizes. The minimum and maximum sizes of the cubic meshes can be determined based on the size information of the object to be printed, and the minimum size of the cubic mesh is larger than the diameter of the nozzle in the 3D printing system. In some embodiments, each cubic mesh is used to fill a unit cell (e.g., a compatible unit cell), and the size of the filled unit cell is the same as the size of the cubic mesh. Please continue reading. Figure 3Based on distance field and stress field information, the outer contour layer 31 of the 3D printed structure 30 closer to the object to be printed generates a smaller cubic mesh to fill smaller unit cells, with a higher fill density. The outer contour layer 31 of the 3D printed structure 30 farther from the object to be printed generates a larger cubic mesh to fill larger unit cells, with a lower fill density. The larger cubic mesh can be subdivided into multiple smaller cubic meshes; for example, the larger cubic mesh can be subdivided into eight smaller cubic meshes.

[0056] In some embodiments, each cube mesh has critical information, which may include mesh size and mesh position. The mesh size may represent the size of the cube mesh, and the mesh position may represent the position of the cube mesh in the 3D printed structure 30. For example, the mesh position may be the center coordinates of the cube mesh.

[0057] In some embodiments, adjacent cubic grids can be determined based on the grid positions in the critical information. For example, any one cubic grid is selected from multiple cubic grids as the first grid. Based on the grid positions, the cubic grids adjacent to the first grid can be determined as the second grids. For instance, the cubic grids located above, below, and to the sides (e.g., left, right, front, and back) of the first grid can be designated as the second grids. The size of the second grid can be less than or equal to the size of the first grid, or it can be larger than the size of the first grid. Multiple second grids can have the same size or different sizes; this is not limited here. The selection order of the first grids can be set according to actual needs; for example, selection can be from the boundary position of the object to be printed towards the center, or from the center position of the object to be printed towards the boundary position. The number of first grids selected each time can be determined based on the computing power of the computer device; for example, the number of first grids selected each time can be one or more.

[0058] In some embodiments, to enable self-support when unit cells of different sizes are stacked together, the unit cells corresponding to each cubic grid can be processed based on critical information to obtain compatible unit cells, so that the compatible unit cells located below can provide support for the adjacent upper unit cells. For example, taking adjacent cubic grids as a first grid and a second grid, the positional stacking information of the adjacent cubic grids is determined based on the grid positions. The positional stacking information can include the positional relationship between the first grid and the second grid, and the number of stacked second grids with the first grid. The positional relationship can represent the stacking position of the second grid in the first grid, including the second grid on the side of the first grid, the second grid above the first grid, and the second grid below the first grid. The number of stacked second grids can include the number of stacked second grids of the same size on the side of the first grid, the number of stacked second grids of the same size above the first grid, and the number of stacked second grids of the same size below the first grid. In some embodiments, based on the positional overlay information, adjacent first and second grids are selected from the plurality of cubic grids; if the first grid size of the first grid is larger than the second grid size of the second grid, then the surface of the unit cell in the first grid facing the second grid is subjected to compatibility processing to obtain the compatible unit cell; if the first grid size of the first grid is less than or equal to the second grid size of the second grid, then no compatibility processing is performed on the surface of the unit cell in the first grid facing the second grid. This embodiment compares the first grid size of the first grid with the second grid size of the second grid, and when the first grid size is larger than the second grid size, performs compatibility processing on the pre-filled unit cells in the first grid, so that the larger unit cell provides support for the smaller unit cell.

[0059] In some embodiments, a compatibility processing is performed on the surface of the unit cell in the first grid facing the second grid (hereinafter referred to as the "target surface" for ease of description). For example, if the second grid is above the first grid, the upper surface of the unit cell in the first grid is subjected to compatibility processing; if the second grid is below the first grid, the lower surface of the unit cell in the first grid is subjected to compatibility processing; if the second grid is located to the side of the first grid, the side surface of the unit cell in the first grid is subjected to compatibility processing. The upper surface can refer to the surface where the unit cells in the first grid and the unit cells in the second grid contact each other when the second grid is above the first grid. The lower surface can refer to the surface where the unit cells in the first grid and the unit cells in the second grid contact each other when the second grid is below the first grid. The side surface can refer to the surface where the unit cells in the first grid and the unit cells in the second grid contact each other when the second grid is located to the side of the first grid.

[0060] For example, Figure 4This is a schematic diagram of the unit cell stacking provided in an embodiment of this application. For example... Figure 4 As shown, the larger unit cell is designated as the unit cell in the first grid, denoted as the first unit cell, and the smaller unit cell is designated as the unit cell in the second grid, denoted as the second unit cell. The smaller unit cells are located above the larger unit cells, and up to four smaller unit cells can be placed above the larger unit cell. Figure 4 Let's take the example of a larger unit cell connected to a smaller unit cell. Since the upper surface of the larger unit cell is in contact with the smaller unit cell, this upper surface is considered the target surface. Before compatibility processing is applied to the target surface, the area where the smaller and larger unit cells meet will be unsupported, meaning the larger unit cell cannot provide stable support for the smaller unit cell.

[0061] In some embodiments, the target surface includes six edges: two intersecting edges in the middle and four surrounding edges. These six edges are denoted as edge 111, edge 112, edge 113, edge 114, edge 115, and edge 116, respectively. Edge 111 and edge 113 are parallel to each other, edge 112 and edge 114 are parallel to each other, and edge 115 and edge 116 are perpendicular to each other. The midpoints of each edge are determined, resulting in five midpoints. The midpoints of the two intersecting edges are the same, representing their intersection. Connecting these midpoints creates a midpoint line. If the second grid is located above the first grid, the target direction is vertically downwards. Extending the midpoint line vertically downwards creates a new surface. For example, Figure 5 This is a schematic diagram of the structure of a compatible unit cell provided in the first embodiment of this application. For example... Figure 5 As shown, the target surface of the first unit cell is fused with the lower surface of the second unit cell. The line connecting the midpoints of the first side 111 and the fifth side 115 is denoted as the first connecting line 117, the line connecting the midpoints of the second side 112 and the fifth side 115 is denoted as the second connecting line 118, and the line connecting the midpoints of the first side 111 and the second side 112 is denoted as the third connecting line 119. The first connecting line 117, the second connecting line 118, and the third connecting line 119 are extended vertically into the receiving cavity of the first unit cell facing the second unit cell, thereby achieving stable support for the unit cell in the upper second grid through the compatible unit cell in the lower first grid.

[0062] In some embodiments, if the second grid is located below the first grid, the target direction is vertically upward, and a new surface is created by extending the line connecting the midpoints vertically upward. The target surface of the unit cell in the first grid is compatible with the upper surface of the unit cell in the second grid, and the upper surface of the unit cell in the second grid provides support for the unit cell in the first grid.

[0063] In some embodiments, if the second grid is located on the side of the first grid, the target direction is horizontal, and extending the midpoint line along the horizontal direction creates a new surface. The target surface of the unit cell in the first grid is compatible with the side surface of the unit cell in the second grid, providing support for the unit cell in the second grid through the target surface. Since the horizontal surface cannot be supported, no new horizontal surface is added when extending the midpoint line along the horizontal direction to create a new surface. For example, Figure 6 This is a schematic diagram of the structure of a compatible unit cell provided in the second embodiment of this application. For example... Figure 6 As shown, the six faces of a larger unit cell can support four smaller unit cells, and compatibility is applied to all six faces of the unit cell. Since the horizontal faces cannot be supported, the side faces have fewer horizontal faces compared to the top and bottom faces. The number of reduced horizontal faces can be found by referring to... Figure 6 The dashed box in the middle.

[0064] In some embodiments, there is a correspondence between compatible unit cells and cubic meshes in the 3D printed structure 30. By querying this correspondence, multiple compatible unit cells are filled into the corresponding cubic meshes to obtain the 3D printed structure 30. The 3D printed structure 30 can simultaneously satisfy self-support, self-adaptation, and isotropy.

[0065] In some embodiments, after determining the infilled 3D printed structure 30, slicing software can be invoked to slice the infilled 3D printed structure 30. Each slice layer will only slice adjacent compatible cells on the left and right, not overlapping compatible cells. Based on this rule, multiple infilled slice layers can be determined. Each slice layer has its corresponding printing information, such as the color of the printing material, the shape and size of the model, and the model's contour features.

[0066] In some embodiments, the 3D printing system achieves 3D printing layer by layer, with each filled slice layer containing a 3D printing path. After the computer device determines the filling structure of the compatible cells in each filled slice layer, it can calculate the planar expression constituting each compatible cell. The planar expression describes the shape and position of the compatible cells, as well as the interconnection between compatible cells. The 3D printing path can be determined by calculating the intersection of the Z-plane with each compatible cell. After determining the intersection of the Z-plane with each compatible cell, these intersections can be connected to form the 3D printing path for that layer. The computer device sends the 3D printing path of the slice layer to the 3D printing system, enabling the 3D printing system to 3D print the object to be printed according to the 3D printing path. For example, Figure 7 This is a schematic diagram of the 3D printing path provided in an embodiment of this application. For example... Figure 7As shown, the object to be printed is a cylindrical model. The center of the cylindrical model is filled with larger compatible unit cells, and the boundary areas are filled with smaller compatible unit cells. The intersection lines within the circular region represent the 3D printing path of that slice layer.

[0067] Using the unit cell provided in the embodiments of this application for 3D printing, since the unit cell can satisfy self-support and isotropy, the strength of the 3D printed structure 30 corresponding to the object to be printed is enhanced without increasing the printing cost. Using the unit cell for 3D printing can improve the 3D printing effect.

[0068] It will be apparent to those skilled in the art that this application is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this application. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of this application is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be embraced within this application. No reference numerals in the claims should be construed as limiting the scope of the claims. Furthermore, it is clear that the word "comprising" does not exclude other elements or, and the singular does not exclude the plural. Multiple elements or devices recited in the specification may also be implemented by a single element or device through software or hardware. The terms "first," "second," etc., are used to indicate names and do not indicate any particular order.

[0069] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit it. Although this application has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this application without departing from the spirit and scope of the technical solutions of this application.

Claims

1. A unit cell for 3D printing, characterized in that, The unit cell comprises a plurality of faces, each face having an equal area, two adjacent faces being perpendicular to each other, and two opposite faces being parallel to each other; wherein each face is provided with a containing cavity, and the containing cavity is provided with a vertex and a plurality of support faces.

2. The unit cell of claim 1, wherein, Each face comprises a rectangular face; or, the volume of the containing cavity in each face is the same; or, the containing cavity comprises a square pyramid; or, the plurality of containing cavities have the same vertex.

3. The unit cell of claim 1, wherein, Each support face extends from the vertex along a diagonal direction of the containing cavity.

4. The unit cell of claim 1, wherein, Each support face extends from the vertex along a middle line direction of the corresponding face of the containing cavity.

5. The cell of claim 3 or 4, wherein, Each support face is provided with a hollow hole.

6. The unit cell of claim 1, wherein, The plurality of unit cells comprises at least two layers of first unit cells and second unit cells, and the containing cavity of the first unit cell is connected with the containing cavity of the second unit cell.

7. The unit cell of claim 6, wherein, In the arrangement direction of the first unit cell and the second unit cell, if the projection of the second unit cell is located within the projection range of the first unit cell, then the support face of the second unit cell facing the first unit cell and a plurality of faces of the second unit cell perpendicular to the first unit cell all extend into the containing cavity of the first unit cell facing the second unit cell.

8. The unit cell of claim 6, wherein, If the second unit cell is located in the vertical direction of the first unit cell, then in the faces of the second unit cell perpendicular to the first unit cell, 2 faces are selected to extend into the containing cavity of the first unit cell facing the second unit cell; if the second unit cell is located in the horizontal direction of the first unit cell, then in the faces of the second unit cell perpendicular to the first unit cell, 1 face is selected to extend into the containing cavity of the first unit cell facing the second unit cell.

9. A 3D printed structure, characterized by: The 3D printing structure comprises an outer contour layer and an internal filling layer, and the internal filling layer is used to fill the unit cell according to any one of claims 1 to 8.

10. The 3D printed structure of claim 9, wherein, The filling density of the unit cell comprises 10% to 100%.

11. The 3D printed structure of claim 10, wherein, The filling density close to the outer contour layer is greater than the filling density away from the outer contour layer, and the size of the unit cell close to the outer contour layer is smaller than the size of the unit cell away from the outer contour layer.

12. The 3D printed structure of claim 10, wherein, The filling density and size of the unit cell are set according to the action field of the object to be printed.

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