A forming method and product of multi-material mechanical functional parts in additive manufacturing
By using single-cell structures to form a dot matrix structure in multi-material mechanical functional components and using additive manufacturing technology to replace multi-material components, the problems of stress concentration and high cost are solved, and the smooth transition of mechanical properties and the improvement of material utilization are achieved. , obtain a single material component of high precision and complex shape.
Patent Information
- Application Number
- CN202010977123.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2020-09-17
- Publication Date
- 2025-01-03
- Estimated Expiration
- 2040-09-17
AI Technical Summary
Multi-material mechanical functional components have problems of stress concentration and high production cost in microstructure, making it difficult to achieve lightweight and efficient mechanical performance conversion.
By selecting single-cell structures to form a dot matrix structure, using additive manufacturing technology to replace multi-material mechanical functional components, avoiding the bonding of different materials, using a single material to prepare dot matrix structures with multiple mechanical properties, and combining finite element simulation and experiments to determine mechanical properties , optimize the assembly and connection method of dot matrix structure.
It realizes a smooth transition of mechanical properties, reduces part quality, improves material utilization, avoids stress concentration, simplifies the manufacturing process, reduces costs, and obtains a single material mechanical functional component with high precision and complex shapes.
Smart Images
Figure CN112163291B_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field related to additive manufacturing, and more specifically, relates to a forming method and product of a multi-material mechanical functional part in additive manufacturing. Background Art
[0002] With the continuous progress of mechanical engineering, the types of functional components are endless, but the requirements for materials are also constantly increasing. Multi-material mechanical functional components achieve mechanical properties changes in different parts by changing the types of materials and the combination of methods, so they are widely used. However, the bonding of different materials in the microstructure of multi-material mechanical functional components is prone to cause stress concentration and increase the production cost.
[0003] The lattice structure has mechanical properties such as high specific strength, and controllable mechanical properties can be achieved by controlling the type, size and periodic arrangement of the lattice unit cells. In recent years, additive manufacturing technology has developed rapidly, and lattice structures with high precision and good surface quality can be prepared. Therefore, additive manufacturing can be used to prepare a variety of lattice structures with different mechanical properties using a single material to combine and replace multi-material mechanical functional components. There is no heterogeneous material bonding inside, which makes the transition of mechanical properties smooth, avoids stress concentration, and reduces costs and achieves lightweight. Summary of the invention
[0004] In response to the above defects or improvement needs of the prior art, the present invention provides a forming method and product of multi-material mechanical functional parts in additive manufacturing, by selecting a unit cell structure and then using the unit cell structure to form a lattice structure of each part. Compared with the solid structure of the part to be formed, the lattice structure meets the mechanical properties of the product on the one hand, and on the other hand, the structure of the lattice structure is equivalent to the solid structure and is more lightweight, which greatly reduces the mass of the original parts and improves the utilization rate of the material.
[0005] To achieve the above object, according to one aspect of the present invention, a forming method of a multi-material mechanical functional part in additive manufacturing is provided, characterized in that the forming method comprises the following steps:
[0006] S1: for an object to be formed including multiple materials, the object to be formed is divided into multiple parts according to different types of materials, and the mechanical properties of each part are analyzed and measured; a database including multiple unit cell structures, i.e., a unit cell library, is constructed;
[0007] S2: for each part of the object to be formed, a unit cell structure is selected from the unit cell library, and a lattice structure is formed using the unit cell structure, so as to obtain a lattice structure corresponding to each part of the object to be formed;
[0008] S3: selecting the raw materials of the lattice structure, measuring the mechanical properties of each lattice structure, and comparing them with the mechanical properties of each part of the object to be formed in step S1; when the mechanical properties of the lattice structure corresponding to each part are not less than the mechanical properties of each part of the object to be formed in step S1, the lattice structure is the desired lattice structure; otherwise, returning to step S2;
[0009] S4 assembles the lattice structures corresponding to each part obtained in step S3 into a three-dimensional model of the object to be formed, and forms the three-dimensional model using an additive manufacturing method to obtain the desired object to be formed.
[0010] Further preferably, in step S1, the method used for determining the mechanical properties of each part is through experimental determination or finite element simulation.
[0011] Further preferably, in step S1, the mechanical parameters of the unit cell structure in the unit cell library are known, and the mechanical parameters include Young's modulus, bulk modulus and shear modulus.
[0012] Further preferably, in step S1, the unit cell structure in the unit cell library is preferably a simple cube, a face-centered cube, a body-centered cube, a regular octahedron, an eight-fold truss or a three-dimensional minimal surface.
[0013] Further preferably, in step S3, the raw material of the selected lattice structure is one material, that is, the raw material of the lattice structure corresponding to each part is the same, which is the selected material.
[0014] Further preferably, in step S4, when the lattice structure is assembled into a three-dimensional model of the object to be formed, it also includes setting a connection structure at the connection interface of different parts so that the three-dimensional model obtained after assembly meets the mechanical property requirements of the overall object to be formed.
[0015] Further preferably, in step S4, the additive manufacturing method is selected according to the selected raw materials. For metal materials, laser selective sintering or laser sintering technology is selected; for engineering plastics, fused deposition molding is used; and for photosensitive materials, photocuring is selected.
[0016] According to another aspect of the present invention, there is provided a product prepared by the above-mentioned forming method.
[0017] In general, compared with the prior art, the above technical solution conceived by the present invention provides the following beneficial effects:
[0018] 1. In the present invention, a unit cell structure is selected and then used to form a lattice structure of each part. Compared with the solid structure of the part to be formed, the lattice structure meets the mechanical properties of the product on the one hand, and on the other hand, the structure of the lattice structure is lighter than the solid structure, which greatly reduces the mass of the original part and improves the utilization rate of the material;
[0019] 2. In the present invention, the parts are divided into multiple parts according to the materials of the parts, and each part is prepared into a different lattice structure. During the forming process, the appearance of heterogeneous materials inside different parts, as well as the adhesion and stress concentration of heterogeneous materials in different parts are avoided;
[0020] 3. In the present invention, the parts to be formed are formed by 3D printing, mainly because the 3D printing process is formed according to slices, and different parts of each layer structure can be formed at the same time, not partitioned, so the final product has excellent overall performance, avoids connection defects at the joints between different parts, produces high precision, and obtains excellent surface quality of the material mechanical functional component;
[0021] 4. The materials of all lattice structures selected in the method of the present invention are the same, that is, the original multi-material parts to be formed are printed with one material, and the single-material mechanical functional components prepared by additive manufacturing replace the traditional multi-material mechanical functional components. The various parts of the single-material mechanical functional components are formed by the periodic superposition of multiple lattice unit cells, so that different parts of the component have different mechanical properties. According to the mechanical properties of the multi-material mechanical functional components, the lattice unit cells of the corresponding positions of the single-material mechanical functional components are designed and periodically arranged to form a lattice structure, thereby achieving the mechanical properties of the multi-material mechanical functional components. Compared with the multi-material mechanical functional components, the single-material mechanical functional components are simple to manufacture and have lower costs; there is no bonding of dissimilar materials at the microscopic level, and the transition of mechanical properties is smooth, which avoids stress concentration at the internal connection parts when the multi-material mechanical functional components bear external forces. The additive manufacturing technology is used to replace traditional processing methods to prepare single-material mechanical functional components with complex shapes and precise internal structures. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Figure 1 It is a flow chart of a forming method of a multi-material mechanical functional part in additive manufacturing constructed according to a preferred embodiment of the present invention;
[0023] Figure 2 It is a schematic diagram of the direct connection between the face-centered cubic lattice structure and the eight-fold truss lattice structure constructed according to the preferred embodiment of the present invention;
[0024] Figure 3It is a diagram of the direct connection between the side of the simple cubic lattice structure and the modified regular octahedron lattice structure constructed according to the preferred embodiment of the present invention, wherein (a) is a connection schematic diagram; (b) is a view of the connection surface after the modification of the regular octahedron lattice structure connected to the simple cubic structure;
[0025] Figure 4 It is a schematic diagram of the indirect connection of the side of a simple cubic lattice structure and a regular octahedral lattice structure constructed according to a preferred embodiment of the present invention through a solid solid plate;
[0026] Figure 5 It is a schematic diagram of a multi-material mechanical functional component to be formed constructed according to a preferred embodiment of the present invention;
[0027] Figure 6 It is constructed according to the preferred embodiment of the present invention Figure 5 The schematic diagram of a single material functional component prepared by the method of the present invention is shown as a multi-material mechanical functional component;
[0028] Figure 7 It is constructed according to the preferred embodiment of the present invention Figure 6 Top view of the . DETAILED DESCRIPTION
[0029] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.
[0030] like Figure 1 As shown, a forming method of multi-material mechanical functional parts in additive manufacturing includes measuring the mechanical properties of different parts in the multi-material mechanical functional parts; selecting raw materials for preparing single-material mechanical functional components; constructing a unit cell library, selecting appropriate unit cell types, sizes, and lattice structures formed by periodic arrays; measuring the mechanical properties of the formed lattice structure, if not meeting the requirements, returning to the previous step, and reselecting the unit cell type, size, and lattice structure formed by periodic arrays; if meeting the requirements, using additive manufacturing technology to prepare single-material mechanical functional components.
[0031] Further, determining the mechanical properties of each part of the multi-material mechanical functional component, including determining the mechanical properties by experiment or finite element simulation (FEM);
[0032] Different parts of a multi-material mechanical functional component have different mechanical properties, and the parts with the same mechanical properties are set as a whole. Therefore, a multi-material mechanical functional component has a (a = 1, 2, 3, 4, ..., n) different mechanical properties of the whole, and the mechanical properties of the a whole parts divided by the multi-material mechanical functional component are calculated directly by experimental measurement or CAD modeling and then imported into FEM software.
[0033] Further, a raw material for preparing a single-material mechanical functional component is selected, including reasonable selection based on the mechanical properties of each part of the multi-material functional component, the cost of the raw material and the application scenario of the functional component;
[0034] The mechanical properties of the lattice unit cell prepared based on a single material are lower than those of the solid material. Therefore, the range of controllable mechanical properties of the lattice structure prepared by a single material is lower than that of the solid single material. Therefore, the corresponding mechanical properties of the selected single material must be higher than any of the a wholes divided by the multi-material mechanical functional components. If there is more than one raw material that meets the above requirements, it can be reasonably selected based on the cost of the raw materials and the application scenario of the single-material mechanical functional components.
[0035] Furthermore, the unit cell library is constructed by selecting the appropriate unit cell type, size and periodic array method to form a lattice structure, including designing unit cells by oneself or referencing existing unit cells and making reasonable combinations;
[0036] The material library needs to contain a variety of lattice unit cells. The lattice unit cell types are independently designed using CAD. The mechanical properties of the unit cell are calculated in the finite element simulation (FEM) software, including mechanical parameters such as Young's modulus, bulk modulus, and shear modulus. Based on the calculation results, the curves and equations of the mechanical parameters changing with conditions (truss size, unit cell diameter, etc.) are summarized and imported into mathematical calculation software such as MATLAB. Mathematical calculation software such as MATLAB can artificially change the unit cell size and periodic array mode and calculate the change law of the mechanical parameters after the change; use the lattice unit cells designed by scientific researchers, such as simple cube (SC), face-centered cubic (FCC), body-centered cubic (BCC), octahedron, octet truss, and three-dimensional minimal surface (TPMS), and store the corresponding formulas of mechanical properties changing with unit cell size and periodic array mode in mathematical calculation software such as MATLAB;
[0037] According to the input multi-material functional components, the size, mechanical properties and mechanical parameters of the selected single material are divided into the first overall design of the unit cell type, size and unit cell periodic array mode, and the corresponding unit cell type, size and periodic arrangement mode form a lattice structure. 1(b=1, 2, 3, 4, ..., n) types, select one of the lattice structures to replace the first whole divided by the multi-material mechanical functional components of the multi-material, and the remaining b 1 -1 is used as a backup; similarly, the second, third, fourth, ..., ath wholes divided from the multi-material mechanical functional component are all treated with the above method. Finally, a lattice structure is selected to replace a whole divided from the multi-material mechanical functional component. The remaining b 2 -1, b 3 -1, b 4 -1, ..., b a -1 for alternative.
[0038] Further, determining the mechanical properties of the selected a-type lattice structure, including verifying whether the mechanical properties of the lattice structure meet the requirements;
[0039] After the lattice unit cell array is formed, an irregular lattice structure may be formed. The mechanical properties calculated based on the lattice unit cell in MATLAB may deviate from the actual application and need to be further verified by finite element simulation (FEM). If the mechanical properties meet the requirements of the corresponding a multi-material whole, the a lattice structures can be directly combined in three-dimensional space. If the mechanical properties do not meet the requirements, return to the lattice unit cell library to select a spare lattice structure until a single-material mechanical functional component with mechanical properties similar to those of the multi-material mechanical functional component is formed.
[0040] Further, the a-type lattice structures are combined in three-dimensional space, including direct superposition combination and indirect superposition combination;
[0041] The sides of the two structures are directly superimposed along the longitudinal or vertical direction. When the two structures have similar unit cell sizes, they can be directly connected at the sides. Figure 2 As shown, taking the face-centered cubic lattice structure (FCC) and the octet truss lattice structure (Octet truss) as examples, the side frames of the FCC structure are directly combined with the side frames of the octet truss. The sides of the two structures are directly superimposed along the longitudinal or vertical direction. When the two structures have similar unit cell sizes, direct connection of the sides cannot be achieved. Taking the combination of the simple cubic lattice structure (SC) and the regular octahedron lattice structure (Octahedron) lattice structure as an example, the two structures cannot be directly combined in the horizontal or vertical direction, that is, the side of the FCC lattice structure is a square frame, and there is no solid structure inside the frame. The solid part of the side of the regular octahedron lattice structure (Octahedron) is located in the center of the square frame, and there is no solid structure outside the square frame, so a united whole cannot be formed. As shown Figure 3As shown in (a) and (b), by removing part of the octahedron lattice structure (Octahedron) and changing the solid position of the side of the octahedron lattice structure (Octahedron), the solid position of the side of the modified octahedron lattice structure (Octahedron) can be combined with the solid framework of the square edge of the simple cubic lattice structure (SC). The corresponding mechanical parameters of the modified combined lattice structure will fluctuate, so this method can only obtain approximate mechanical properties;
[0042] The sides of the two structures are directly superimposed along the longitudinal or vertical direction. When the unit cell sizes of the two structures are greatly different, direct superposition or modification of the lattice structure sides cannot form a stable combination. Solid plates are added to the sides for connection. The connection method of the simple cubic lattice structure (SC) with a larger unit cell size and the regular octahedron lattice structure (Octahedron) with a smaller unit cell size is taken as an example. Figure 4 As shown, a solid solid plate is added at the connection for indirect connection. The thickness of the solid solid plate is selected according to the needs. This method can only obtain approximate mechanical properties. The purpose of adding a solid solid plate is to ensure a smooth transition of the mechanical properties of the joint part of the two lattice structures and reduce the possibility of stress concentration.
[0043] The above methods are all connected directly or indirectly. The connection methods are relatively rigid. In some cases, there are obvious sharp corners, which can easily cause stress concentration. The sharp corners of the connection can be removed or smoothed as needed, or the connection method of the connection can be designed by yourself.
[0044] Furthermore, a single-material mechanical functional component having a mixture of multiple lattice structures is manufactured, including selecting a reasonable additive manufacturing method according to the type of material.
[0045] Single-material functional components based on a mixture of multiple lattice structures have complex shapes. Large components can be manufactured through investment casting, molten gas injection, physical vapor deposition, sheet metal technology and other processing methods. However, multi-material mechanical functional components have the characteristics of small size and complex shape. The above processing technologies are difficult to obtain good internal lattice unit cells, and there are obvious stress fluctuations when bearing external forces. Therefore, additive manufacturing technology (AM) that can produce high precision and obtain good surfaces is selected to replace the above traditional processing technologies. Reasonable additive technology means are selected according to the type of material. Laser selective melting (SLM) and laser sintering technology (SLM) are suitable for metal materials such as titanium alloys, stainless steel, and aluminum alloys; fused deposition modeling (FDM) is suitable for engineering plastics such as PLA and nylon, and stereolithography (SLA) is suitable for photosensitive materials such as photosensitive resins.
[0046] like Figure 5As shown in the figure, a multi-material mechanical functional component is given, which is composed of a cubic periphery and a cylindrical core made of two different materials, as shown in Figure 6 As shown, two lattice structures are given to form a single material mechanical functional component of the cube periphery and the cylindrical core, such as Figure 7 As shown, it is a top view of the combination of two lattice structures. The appearance of the single-material mechanical functional component after the combination of the two lattice structures is similar to the multi-material mechanical functional component. The desired mechanical properties can be achieved later by adjusting the material type, unit cell type, size and array method.
[0047] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.
Claims
1. A forming method for multi-material mechanical functional parts in additive manufacturing, characterized in that: The forming method comprises the following steps: S1 For an object to be formed including multiple materials, the object to be formed is divided into multiple parts according to different types of materials, and the mechanical properties of each part are analyzed and measured; a database including multiple unit cell structures, i.e., a unit cell library, is constructed; S2 For each part of the object to be formed, a unit cell structure is selected from the unit cell library, and a lattice structure is formed using the unit cell structure, so as to obtain a lattice structure corresponding to each part of the object to be formed; S3: selecting the raw materials of the lattice structure, measuring the mechanical properties of each lattice structure, and comparing them with the mechanical properties of each part of the object to be formed in step S1; when the mechanical properties of the lattice structure corresponding to each part are not less than the mechanical properties of each part of the object to be formed in step S1, the lattice structure is the desired lattice structure; otherwise, returning to step S2; S4 assembling the lattice structures corresponding to each part obtained in step S3 into a three-dimensional model of the object to be formed, and forming the three-dimensional model by an additive manufacturing method, so as to obtain the desired object to be formed; In step S3, the raw material of the lattice structure is selected, and the raw material is one material, that is, the raw material of the lattice structure corresponding to each part is the same, which is the selected material; The materials of all selected lattice structures are the same, that is, the multi-material parts to be formed are printed with one material, and the single-material mechanical functional components prepared by additive manufacturing replace the traditional multi-material mechanical functional components. Each part of the single-material mechanical functional component is formed by the periodic superposition of multiple lattice unit cells, so that different parts of the component have different mechanical properties. According to the mechanical properties of the multi-material mechanical functional components, the lattice unit cells of the corresponding positions of the single-material mechanical functional components are designed and periodically arranged to form a lattice structure, thereby achieving the mechanical properties of the multi-material mechanical functional components.
2. A forming method for multi-material mechanical functional parts in additive manufacturing according to claim 1, characterized in that: In step S1, the method for determining the mechanical properties of each part is through experimental determination or finite element simulation.
3. The forming method of a multi-material mechanical functional part in additive manufacturing according to claim 1, characterized in that: In step S1, the mechanical parameters of the unit cell structure in the unit cell library are known, and the mechanical parameters include Young's modulus, bulk modulus and shear modulus.
4. The forming method of a multi-material mechanical functional part in additive manufacturing according to claim 1, characterized in that: In step S1, the unit cell structure in the unit cell library is a simple cube, a face-centered cube, a body-centered cube, a regular octahedron, an eight-fold truss or a three-dimensional minimal surface.
5. The forming method of a multi-material mechanical functional part in additive manufacturing according to claim 1, characterized in that: In step S4, when the lattice structure is assembled into a three-dimensional model of the object to be formed, it also includes setting a connection structure at the connection interface of different parts so that the three-dimensional model obtained after assembly meets the mechanical performance requirements of the overall object to be formed.
6. The forming method of a multi-material mechanical functional part in additive manufacturing according to claim 1, characterized in that: In step S4, the additive manufacturing method is selected according to the selected raw materials. For metal materials, laser selective sintering or laser sintering technology is selected; for engineering plastics, fused deposition molding is used; and for photosensitive materials, photocuring is selected.
7. A product prepared by the forming method according to any one of claims 1 to 6.