Zero-expansion structure based on invar alloy and SLM forming method
Through the SLM process parameters, the printing and forming of an Inwa alloy structure with different thermal expansion coefficients is solved, and the existing zero-expansion structure failure or damage in special environments is realized, and the efficient manufacturing and lightweight application of an Inwa alloy zero-expansion structure is realized.
Patent Information
- Application Number
- CN202510393647.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-31
- Publication Date
- 2025-06-27
AI Technical Summary
The existing zero-expansion structure may fail or be damaged under temperature changes or mechanical stresses under certain special environments, and due to the high density of the tile alloy material, it cannot fully meet the needs of lightweight applications of high-end equipment.
The Inwa alloy structure with different thermal expansion coefficients is formed through SLM process parameters, and the zero-expansion configuration of isomeric materials is integrated, so as to achieve accurate control and optimization of the performance of Inwa alloy materials.
It realizes efficient manufacturing of Inwa alloy zero-expansion structure, has sufficient load-bearing capacity and lightweight level, is suitable for high-end precision equipment, and improves manufacturing convenience and efficiency.
Smart Images
Figure CN120205818A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a method for SLM forming process of a zero-expansion structure based on invar alloy, belonging to the technical field of additive manufacturing of metal functional structures. Background Art
[0002] Thermal expansion and contraction is an inherent physical property of natural materials. In complex service environments, high-end precision equipment (such as aerospace, microelectronic devices, optical instruments, etc.) will be affected by various interferences, which may cause thermal expansion and contraction or local thermal stress, thus having an adverse impact on its function. The zero-expansion structure can resist these interferences, has no obvious size effect, can maintain the dimensional accuracy and position accuracy of the payload structure, thereby ensuring the stability of its performance. At the same time, the zero-expansion structure also has sufficient load-bearing capacity and lightweight level, and can solve the stability and reliability of high-end precision equipment.
[0003] The existing forms of zero-expansion structures mainly include composite materials, invar alloys, and heterogeneous material structures. Composite materials adopt a multi-layer material structure and are combined together by means of hot pressing, bonding, etc., and have high strength and elastic properties. Invar alloy is an alloy with a low expansion coefficient itself, which can adapt to temperature changes, and its low expansion coefficient characteristics have wide applications in many fields. The heterogeneous structure is a structure formed by combining different materials, and the zero-expansion of the structure is achieved by controlling the strength of the heterogeneous materials.
[0004] However, these structural forms face some problems in practical applications. First of all, although composite materials have the advantages of light weight and high strength, temperature changes in some special environments may cause the composite materials to fail, or the composite materials may be damaged under some mechanical stresses; invar alloy, as a material with low expansion characteristics, however, the material density is large, and there is currently no invar alloy that fully meets the lightweight application requirements of high-end equipment; the heterogeneous structure, as a new type of zero-expansion structure form, although it has high performance potential, its implementation is difficult and is restricted by various factors, such as material selection, manufacturing process, interface performance, structural stability, etc. Therefore, the existing forms of zero-expansion structures and implementation methods still have certain limitations and need further research and exploration to achieve more extensive practical applications. Summary of the Invention
[0005] The technical problem solved by this application is: overcoming the deficiencies of the prior art, providing a zero-expansion structure and SLM forming method based on invar alloy, an invar alloy structure with different thermal expansion coefficients formed by regulating printing and forming based on SLM process parameters, and adopting two different process parameters to complete the integrated manufacturing of a zero-expansion configuration based on homogeneous isomeric materials.
[0006] The technical solution provided by this application is as follows:
[0007] In a first aspect, a zero-expansion structure based on invar alloy is provided, including two invar alloy structures with the same material, different relative densities, and different thermal expansion coefficients.
[0008] In a second aspect, an SLM forming method for a zero-expansion structure based on invar alloy is provided, including:
[0009] S1. Using the same invar alloy powder, adjusting the forming process parameters of the SLM equipment, forming under each different forming parameter to obtain multiple corresponding formed parts, measuring the thermal expansion coefficient of each formed part at the required service temperature, and obtaining the mapping relationship between the forming process parameters and the thermal expansion coefficient at the required service temperature;
[0010] S2. Fixing the substrate in the forming chamber of the SLM equipment to make the substrate flush with the SLM processing plane;
[0011] S3. Processing the zero-expansion structure model through three-dimensional modeling software, slicing and filling the path of the zero-expansion structure model, and generating the corresponding path file for transmission to the SLM equipment control system;
[0012] S4. Based on the zero-expansion structure of heterogeneous materials, extracting the thermal expansion coefficients of different materials at the required service temperature to obtain two sets of thermal expansion coefficients; according to the mapping relationship between the forming process parameters and the thermal expansion coefficient at the required service temperature, selecting the forming process parameters corresponding to the thermal expansion coefficient;
[0013] S5. Setting the parameters of the SLM equipment according to the selected forming process parameters and forming one layer of slices;
[0014] S6. Repeating S5 until the SLM processing is completed according to the path to obtain the product.
[0015] Further, the forming process parameters of the SLM equipment include: laser power, scanning speed, scanning line spacing, and layer thickness.
[0016] Further, in S3, slicing and filling the path of the zero-expansion structure model and generating the corresponding path file for transmission to the SLM equipment control system includes: dividing the parts of the invar alloy structure with a small expansion coefficient and the invar alloy structure with a large expansion coefficient into two part models, respectively slicing and filling the path, and generating the corresponding path file for transmission to the SLM equipment control system.
[0017] Further, in S5, set the parameters of the SLM device according to the selected forming process parameters, and form one layer of slices, including: the selected forming process parameters include SLM forming parameter 1 and SLM forming parameter 2. For the same layer of slices, print and form an Invar alloy structure with a small coefficient of thermal expansion using SLM forming parameter 1, and print and form an Invar alloy structure with a large coefficient of thermal expansion using SLM forming parameter 2.
[0018] Further, after S6, it also includes: S7. After the SLM forming is completed, naturally cool to room temperature, and take out the product together with the substrate as a whole; and perform heat treatment on the formed product, and perform wire cutting after heat treatment to obtain a zero-expansion structure of Invar alloy with the same composition but different structures.
[0019] Further, the heat treatment is carried out at 300 °C for long-time low-temperature heat treatment.
[0020] The method for regulating the coefficient of thermal expansion of Invar alloy based on the SLM forming process can achieve precise control and optimization of the material properties of Invar alloy. By precisely regulating the core process parameters such as the powder bed layer thickness, laser power, energy density, scanning spacing, and scanning speed, the microstructure of Invar alloy can be orderly regulated. By precisely controlling the microstructure of the SLM-formed Invar alloy, the mapping relationship between the laser forming parameters, the microscopic characteristic structure, and the coefficient of thermal expansion is established, so that the regulation range of the coefficient of thermal expansion of Invar alloy can reach a change of 2-3 orders of magnitude.
[0021] On this basis, form a zero-expansion lattice material, use the interaction between different thermally expanding materials when the temperature changes to regulate the deformation, and form various adjustment mechanisms for realizing the zero expansion of the material, such as tensile deformation, bending deformation, and Poisson's ratio effect. Improve the structural bearing capacity through the optimization of the cell structure of the lattice material, so as to realize that the zero-expansion structure of Invar alloy with the same composition but different structures has sufficient bearing capacity and lightweight level, which is conducive to the engineering application for high-end precision equipment. Since this method uses the same material for additive integrated forming, without subsequent assembly, it can be realized by existing printers, with high material utilization rate, high production efficiency, and low production cost, greatly improving the convenience and efficiency of manufacturing. In addition, the structural complexity can also be significantly improved.
[0022] In summary, the present application at least includes the following beneficial technical effects:
[0023] (1) Through the precise regulation of the microstructure of Invar alloy by the SLM process, two different coefficients of linear expansion are printed and formed from a powder raw material, and are applied to the zero-expansion lattice structure based on heterogeneous materials to realize the zero-expansion performance of the structure.
[0024] (2) Based on the SLM forming process method, the integrated manufacturing of complex multi-feature zero-expansion structures can be achieved. The interfacial bonding performance of homogeneous isomeric materials is good, and the reliability and stability of the overall zero-expansion structure are greatly improved.
[0025] (3) By SLM forming a homogeneous isomeric zero-expansion lattice structure, through means such as lattice structure design, process optimization of the mechanical properties of the material itself, the controllable (from negative to positive) thermal expansion performance can be obtained, and at the same time, it can also have a certain load-bearing performance. Description of the Drawings
[0026] Figure 1 It is a zero-expansion configuration of a tetrahedral lattice.
[0027] Figure 2 Square checkerboard zero-expansion configuration;
[0028] Explanation of the reference numerals in the drawings: 1 - Invar alloy structure with a small coefficient of thermal expansion, 2 - Invar alloy structure with a large coefficient of thermal expansion. Detailed Implementation Modes
[0029] To make the objectives, technical solutions, and advantages of the present invention clearer, the following will further describe in detail the disclosed implementation modes of the present invention in conjunction with the drawings.
[0030] For the traditional zero-expansion structure realized by using dissimilar materials, the Invar alloy regulation parameter table provided in Table 1 can be referred to. Table 1 shows the corresponding relationship between the SLM process parameters obtained by regulating the SLM process parameters using Invar alloy Invar36 metal powder and the coefficient of thermal expansion at the required service temperature. The process parameters are selected according to Table 1 and the required coefficient of thermal expansion. It is not limited to this grade of Invar alloy. If other grades of Invar alloy are used, the method introduced in the present invention can be adopted to obtain the mapping relationship between the laser forming parameters, the microscopic characteristic structure, and the coefficient of thermal expansion by adjusting the SLM process parameters.
[0031] The embodiment of the present application discloses a zero-expansion structure based on Invar alloy. The zero-expansion structure is integrally formed by SLM. The zero-expansion structure includes two Invar alloy structures. The two Invar alloy structures have the same material, different relative densities, and different coefficients of thermal expansion. The two Invar alloy structures are respectively the Invar alloy structure 1 with a small coefficient of thermal expansion and the Invar alloy structure 2 with a large coefficient of thermal expansion. The coefficient of thermal expansion of the Invar alloy structure 1 with a small coefficient of thermal expansion is less than that of the Invar alloy structure 2 with a large coefficient of thermal expansion. The coefficients of thermal expansion of the Invar alloy structure 1 with a small coefficient of thermal expansion and the Invar alloy structure 2 with a large coefficient of thermal expansion at the required service temperature are determined according to the product design.
[0032] The structure of the zero - expansion structure of this application can be the same as that of any existing zero - expansion structure. Currently, all existing zero - expansion structures are zero - expansion structures of heterogeneous materials, while the zero - expansion structure of this application is of the same material. Corresponding to the different material parts of the existing zero - expansion structures of heterogeneous materials, by controlling the forming parameters in this application, the relative densities of different parts of the zero - expansion structure of this patent are made different, so that the thermal expansion coefficients are the same as those of the different material parts of the zero - expansion structure of heterogeneous materials. The following takes two zero - expansion structures with different configurations as examples for illustration:
[0033] As Figure 1 shown, the zero - expansion structure includes multiple unit cells, and each unit cell includes six connecting rods. The ends of the 6 connecting rods are connected in sequence to form a regular tetrahedron configuration. The six connecting rods are of the same material. Among them, three connecting rods in the same plane are Invar alloy structure 1 with a small expansion coefficient, and the other three rods are Invar alloy structure 2 with a large expansion coefficient; or three connecting rods in the same plane are Invar alloy structure 2 with a large expansion coefficient, and the other three rods are Invar alloy structure 1 with a small expansion coefficient.
[0034] As Figure 2 shown, the zero - expansion structure includes multiple monomer components. The monomer components are arranged in a horizontal and vertical array, and adjacent monomer components are connected by connecting parts. Each monomer component includes a frame - shaped part and plate bodies connected to each inner side of the frame - shaped part. The connecting parts are connected between the frame - shaped parts. Among them, the frame - shaped parts and the connecting parts are Invar alloy structure 2 with a large expansion coefficient, and the plate bodies are Invar alloy structure 1 with a small expansion coefficient.
[0035] An LSM forming method for a zero - expansion structure based on Invar alloy includes:
[0036] Step 1: Use the same kind of Invar alloy powder, adjust the forming process parameters of the SLM equipment, perform forming under each different forming parameter to obtain multiple corresponding formed parts, measure the thermal expansion coefficient of each formed part at the required service temperature, and obtain the mapping relationship between the forming process parameters and the thermal expansion coefficient at the required service temperature; as shown in Table 1;
[0037] Among them, the forming process parameters of the SLM equipment include: laser power, scanning speed, scanning line spacing, and layer thickness;
[0038] Step 2: Grind and clean the surface of the Invar alloy substrate or 304 stainless - steel substrate, fix it in the forming chamber of the SLM equipment, and make the substrate flush with the SLM processing plane;
[0039] Process the zero - expansion structure model through 3D modeling software, and take Figure 1 or Figure 2Among them, the low thermal expansion coefficient Invar alloy structure 1 and the high thermal expansion coefficient Invar alloy structure 2 are divided into two part models, and the low thermal expansion coefficient Invar alloy structure 1 and the high thermal expansion coefficient Invar alloy structure 2 are located in the same printing coordinate system and combined into the required zero-expansion structure. The part models of the low thermal expansion coefficient Invar alloy structure 1 and the high thermal expansion coefficient Invar alloy structure 2 are sliced and filled with paths respectively, and the corresponding path files are generated and transmitted to the SLM equipment control system;
[0040] Step 3: For the zero-expansion structure based on heterogeneous materials, extract the thermal expansion coefficients of different materials at the required service temperature to obtain two sets of thermal expansion coefficients; according to the mapping relationship between the forming process parameters and the thermal expansion coefficients at the required service temperature, select the forming process parameters corresponding to the thermal expansion coefficients. The low thermal expansion coefficient Invar alloy structure 1 corresponds to SLM forming parameter 1, and the high thermal expansion coefficient Invar alloy structure 2 corresponds to SLM forming parameter 2 to meet the final thermal expansion performance of the structure. The model of the low thermal expansion coefficient Invar alloy structure 1 adopts SLM forming parameter 1, and the model of the high thermal expansion coefficient Invar alloy adopts SLM forming parameter 2;
[0041] Step 4: Set the laser power of the laser of the SLM equipment, the scanning mode and scanning speed of the laser, the protective gas flow rate, and the scraper running speed. Control the SLM equipment by computer. For the same layer of slices, use SLM forming parameter 1 to print and form the low thermal expansion coefficient Invar alloy structure 1, and use SLM forming parameter 2 to print and form the high thermal expansion coefficient Invar alloy structure 2;
[0042] Step 5: Start the SLM equipment for processing until the SLM processing process is completed along the entire path;
[0043] Step 6: After the SLM forming of the part is completed, it is naturally cooled to room temperature, and the product together with the substrate is taken out as a whole;
[0044] Step 7: The post-forming heat treatment is carried out at 300 °C for long-term low-temperature heat treatment, and wire cutting is carried out after the heat treatment to obtain the zero-expansion structure of the homogeneous isomeric Invar alloy.
[0045] Table 1 Invar alloy regulation parameter table
[0046]
[0047]
[0048] Preferably, the chemical composition of the invar alloy metal powder is verified, and the feasibility of selective laser melting forming is carried out. The SLM basic performance process test is carried out to establish the mapping relationship between the laser forming parameters, the microscopic characteristic structure and the coefficient of thermal expansion. Process parameters with a difference of 2-3 orders of magnitude in the coefficient of thermal expansion are selected, and the optimization design of the zero-expansion lattice structure based on the homo-structural and isomeric materials is carried out. Using two selected parameters, the invar alloy powder is accurately formed based on SLM to complete the integrated manufacturing of the zero-expansion lattice structure. After forming, heat treatment is carried out at 300 °C for long-time low-temperature heat treatment, and the product cannot be heat-treated anymore. After wire cutting, grinding and processing are carried out to complete the integrated manufacturing of the zero-expansion structure.
[0049] The content not described in detail in the specification of this application belongs to the well-known technology of those skilled in the art.
[0050] The above has described this application in detail in combination with specific embodiments and exemplary examples, but these descriptions should not be construed as limiting this application. Those skilled in the art understand that without departing from the spirit and scope of this application, various equivalent substitutions, modifications or improvements can be made to the technical solutions and their implementation manners of this application, and these all fall within the scope of this application. The protection scope of this application is subject to the appended claims.
Claims
1. A zero expansion structure based on Invar alloy, comprising two Invar alloy structures, characterized in that: The two Invar alloy structures are made of the same material, but have different relative densities and thermal expansion coefficients.
2. The SLM forming method of a zero expansion structure based on Invar alloy according to claim 1, characterized in that: include: S1. Using the same Invar alloy powder, adjusting the SLM forming process parameters, performing forming under each different SLM forming process parameter, obtaining a plurality of corresponding formed parts, measuring the thermal expansion coefficient of each formed part at the required service temperature, and obtaining a mapping relationship between the forming process parameters and the thermal expansion coefficient at the required service temperature; S2, processing the zero-inflation structural model, slicing the zero-inflation structural model and filling the path to generate a corresponding path file; S3. Based on the two Invar alloy structures included in the zero expansion structure, the thermal expansion coefficients of the two Invar alloy structures at the required service temperature are extracted to obtain two sets of thermal expansion coefficients; according to the mapping relationship between the SLM forming process parameters and the thermal expansion coefficients at the required service temperature, the forming process parameters corresponding to the thermal expansion coefficients are selected; S4, forming a layer of slices according to the forming process parameters selected in S3; S5. Repeat S4 until the SLM processing is completed according to the path file and the product is obtained.
3. The SLM forming method of a zero expansion structure based on Invar alloy according to claim 2, characterized in that: The SLM forming process parameters include: laser power, scanning speed, scanning line spacing and layer thickness.
4. The SLM forming method of a zero expansion structure based on Invar alloy according to claim 2, characterized in that: In S2, the zero expansion structure model is sliced and the path is filled to generate a corresponding path file, including: according to the expansion coefficient, the two Invar alloy structures included in the zero expansion structure are divided into two part models, and the two part models are sliced and the path is filled to generate a corresponding path file.
5. The SLM forming method of a zero expansion structure based on Invar alloy according to claim 2, characterized in that: In the above S4, a layer of slices is formed according to the forming process parameters selected in S3, including: the selected forming process parameters include corresponding to SLM forming parameters 1 and SLM forming parameters 2, and for the same layer of slices, the SLM forming parameters 1 are used to print the Invar alloy structure with a smaller expansion coefficient among the two Invar alloy structures, and the SLM forming parameters 2 are used to print the Invar alloy structure with a larger expansion coefficient among the two Invar alloy structures.
6. The SLM forming method of a zero expansion structure based on Invar alloy according to claim 2, characterized in that: After S5, the following further includes: S6, after the SLM forming is completed, the product is naturally cooled to room temperature, and the substrate is taken out as a whole; The formed product is heat treated and then wire cut to obtain a homogeneous and heterogeneous Invar zero expansion structure.
7. The SLM forming method of a zero expansion structure based on Invar alloy according to claim 2, characterized in that: The heat treatment adopts long-term low-temperature heat treatment at 300°C.