Multi-structure composite manufacturing method

Abstract

The invention relates to the technical field of metal 3D printing, and discloses a multi-structure composite manufacturing method in order to solve the technical problems that multi-structure parts are single, the machining mode period is long, the machining cost is high and the material utilization rate is low. The middle flange is fixed to the forming base plate; the forming substrate is fixed on the 3D printing platform; first-time 3D printing is carried out, a large barrel and a small barrel are formed, and a first-state structural body is formed; taking out the first state structural body; cleaning powder; performing vacuum heat treatment; removing the fastener and the forming substrate; the reverse structural body is provided with a fastener and is fixed; arranging a cylindrical cushion block; fixing on the 3D printing platform again and printing, and forming a bottom barrel to form a second state structural body; taking out the second state structural body; cleaning powder; performing vacuum heat treatment; the fastener, the cylindrical cushion block and the forming base plate are removed; linearly cutting the allowance of the intermediate flange; and polishing the cutting surface and the surface of the barrel.

Description

Technical Field

[0001] The present invention relates to the technical field of metal 3D printing, and in particular to a multi-structure composite manufacturing method. Background Art

[0002] As an important branch of 3D printing, Selective Laser Melting (SLM) technology discretizes the three-dimensional digital model into two-dimensional plane geometric figures, and uses special slicing software to spread powder and sinter layer by layer until parts are formed. This process can achieve rapid response and short-cycle forming of products without molds. The mold-free characteristics of SLM technology give it unique advantages in the manufacture of complex structures, especially in some shapes and structures that are difficult to achieve with traditional manufacturing methods. However, in the actual production and manufacturing field, there are some challenges that make it difficult to prepare complex structures at one time by relying solely on a certain manufacturing technology, or lead to poor metallurgical properties after preparation, which cannot meet strict strength and performance requirements.

[0003] In actual production, the manufacture of complex structural parts often involves a combination of multiple manufacturing methods. Some processing methods themselves have significant advantages, such as high precision or material adaptability, but relying solely on a single processing method for preparation usually exposes obvious shortcomings. Specifically, it manifests in the disadvantages of long manufacturing cycle, high processing cost, low material utilization rate, etc., which brings many difficulties to actual production.

[0004] In the field of aircraft, the manufacturing difficulties of such multi-structure parts are particularly prominent. With the continuous promotion of the concept of integrated design, it is often necessary to design a combination of multiple structures in aircraft to improve the functional integration and overall performance of the parts. However, this also brings about the complexity and manufacturing difficulty of the preparation of multi-structure parts. Traditional manufacturing methods are difficult to cope with this complexity, and a single manufacturing technology is difficult to achieve the forming of all structures in a single processing process. In addition, since multi-structure parts have high requirements on material properties and metallurgical quality, ensuring the reliability and durability of parts in extreme environments has also become a major challenge.

[0005] These manufacturing challenges have severely restricted the service and operation of aircraft. With the continuous advancement of aircraft design and manufacturing technology, the demand for multi-structure parts is also increasing. The increased difficulty in manufacturing complex structural parts not only affects the production efficiency of aircraft, but also puts higher demands on its overall performance and reliability. In this context, how to effectively solve the manufacturing problems of multi-structure parts has become an important issue that needs to be urgently addressed in the manufacturing industry. Further research and exploration is needed to improve manufacturing efficiency, reduce costs, and ensure high performance and reliability of parts. Summary of the invention

[0006] The purpose of the present invention is to provide a multi-structure composite manufacturing method to solve the technical problems of single multi-structure parts, long processing cycle, high processing cost and low material utilization rate.

[0007] To achieve the above object, the present invention provides a multi-structure composite manufacturing method, comprising the following method steps:

[0008] Step S1, selecting a forging blank for preparing an intermediate flange;

[0009] Step S2, preparing the middle flange by mechanical addition, and opening a plurality of step holes on both sides of the middle flange;

[0010] Step S3, using fasteners to fix the intermediate flange to the forming base plate through the step hole;

[0011] Step S4, fixing the formed substrate on the 3D printing platform;

[0012] Step S5, performing a first 3D printing to form a large cylinder and a small cylinder on a first flange plane of the middle flange to form a first state structure;

[0013] Step S6, taking the first state structure out of the forming chamber;

[0014] Step S7, cleaning the powder on the first state structure;

[0015] Step S8, performing vacuum heat treatment on the first state structure;

[0016] Step S9, removing the fastener and the formed substrate;

[0017] Step S10, reverse the structure consisting of the large cylinder, the small cylinder and the middle flange so that the large cylinder and the small cylinder face downward, install fasteners in the step holes and fix them to the forming base plate;

[0018] Step S11, a cylindrical spacer is arranged between the middle flange and the forming base plate,

[0019] Step S12, fixing the formed substrate on the 3D printing platform;

[0020] Step S13, performing a second 3D printing to form the bottom cylinder on the second flange plane of the middle flange to form a second state structure;

[0021] Step S14, taking the second state structure out of the forming chamber;

[0022] Step S15, cleaning the powder on the second state structure;

[0023] Step S16, performing vacuum heat treatment on the second state structure;

[0024] Step S17, removing the fasteners, cylindrical spacers and formed substrate;

[0025] Step S18, performing wire cutting on the remaining portion of the middle flange;

[0026] Step S19, grinding the line-cut surface and the surfaces of each cylinder.

[0027] Furthermore, the first 3D printing includes the following steps:

[0028] Step S201, filling powder into the 3D printing forming chamber;

[0029] Step S202, compacting the powder using a metal spatula;

[0030] Step S203, adjusting the lifting and lowering of the forming cylinder until a predetermined thickness of metal powder is left on the top of the middle flange;

[0031] Step S204, importing the three-dimensional models of the large cylinder and the small cylinder into a 3D printing dedicated process software;

[0032] Step S205, slicing the large cylinder and the small cylinder according to a predetermined layer thickness d;

[0033] Step S206, assigning forming parameters to perform laser light printing;

[0034] Step S207, after the laser sintering of the current layer profile section is completed, the forming chamber is lowered to a predetermined layer thickness d, the scraper spreads the powder, and the laser sinters again, and the cycle is repeated in sequence until the large cylinder and the small cylinder printing program are completely printed; through multiple cycles of powder spreading and sintering, the interlayer bonding of the printed part is ensured to be firm, and finally a high-precision cylinder structure is formed;

[0035] Step S208, stop heating the forming substrate, and when the temperature of the forming substrate drops to room temperature, open the door of the laser selective melting equipment, thereby avoiding thermal stress on the printed part and reducing the risk of deformation and cracks.

[0036] Furthermore, the second 3D printing includes the following steps:

[0037] Step S301, filling powder into the 3D printing forming chamber;

[0038] Step S302, compacting the powder with a metal scraper, and manually operating a powder spreading scraper to spread the powder;

[0039] Step S303, adjusting the lifting and lowering of the forming cylinder until a predetermined thickness of metal powder is left on the top of the middle flange;

[0040] Step S304, closing the forming chamber door, inflating the forming chamber, and starting heating of the forming substrate;

[0041] Step S305, importing the three-dimensional model of the bottom cylinder into a 3D printing dedicated process software, and slicing the bottom cylinder according to a predetermined layer thickness d;

[0042] Step S306, assigning forming parameters, and when the oxygen content in the forming chamber reaches a predetermined value and the temperature of the forming substrate reaches a predetermined temperature, laser light printing is performed, and the laser scanning path is closely observed when scanning the first layer to confirm that the scanning format is at the corresponding position of the middle flange to ensure the accuracy and consistency of the printing process;

[0043] Step S307, after the laser sintering of the current layer profile section is completed, the forming chamber is lowered to a predetermined layer thickness d, the scraper spreads the powder, and the laser sintering is repeated again, and the cycle is repeated until the large cylinder and the small cylinder printing program are completely printed;

[0044] Step S308, stopping heating of the forming substrate, and opening the door of the laser selective melting equipment when the temperature of the forming substrate drops to room temperature.

[0045] This multi-structure composite manufacturing method significantly improves manufacturing accuracy, reduces manufacturing costs, enhances structural strength, improves surface quality, enhances flexibility and customizability, reduces subsequent processing requirements, and saves time through detailed step design and optimization.

[0046] Furthermore, in step S1, the thickness of the forged blank has a single-side margin of 1 to 5 mm, and the single-side margins in the length and width directions are 10 to 50 mm, thereby ensuring the sufficiency of materials for subsequent processing and reducing processing difficulty and cost.

[0047] Furthermore, in step S2, a 0.1-0.2 mm margin is reserved on one side of the intermediate flange in the thickness direction, and a 5-45 mm margin is reserved in the length and width directions, so that the dimensional accuracy can be effectively controlled during machining and subsequent processing, and material waste can be avoided.

[0048] Furthermore, the fastener is a fixing bolt. Using the fixing bolt as the fastener ensures a stable connection between the intermediate flange and the forming base plate, and effectively avoids structural deviation and printing failure caused by looseness during the printing process.

[0049] The multi-structure composite manufacturing method provided by the present invention has the following advantages:

[0050] Improve manufacturing accuracy. Ensure the alignment accuracy between components by performing multiple fixations and adjustments during machining and 3D printing, thereby improving the manufacturing accuracy of the final product. Reduce manufacturing costs. The combination of forging blanks and 3D printing can reduce material waste and processing time, thereby reducing manufacturing costs. Enhance structural strength. The mechanical properties and durability of structural parts can be improved through multiple heat treatments and the use of fasteners. Improve surface quality. Cleaning and polishing between each manufacturing step can significantly improve the surface quality of the final product, making it smoother and more beautiful. Flexibility and customizability. This method is suitable for the manufacture of complex structural parts and can be adjusted according to different design requirements. It has high flexibility and customizability. Reduce subsequent processing. Through a multi-step manufacturing process, most of the structural forming and surface treatment can be completed during the manufacturing process, reducing the need for subsequent processing. Save time. Comprehensively utilize the advantages of machining and 3D printing to shorten the manufacturing cycle and improve production efficiency. This makes the multi-structure composite manufacturing method have significant advantages in the production of high-precision and complex structural parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 A three-dimensional diagram of a multi-structure provided by the present invention;

[0052] Figure 2 A front view of a multi-structure provided by the present invention;

[0053] Figure 3 A three-dimensional diagram of the intermediate flange provided by the present invention after being fixed;

[0054] Figure 4 A longitudinal cross-sectional view of the intermediate flange provided by the present invention after being fixed;

[0055] Figure 5 A three-dimensional model diagram of the large cylinder and the small cylinder provided by the present invention;

[0056] Figure 6 A three-dimensional image of the large cylinder and the small cylinder provided by the present invention after printing and forming;

[0057] Figure 7 A stereoscopic diagram of the large cylinder and the small cylinder provided by the present invention after assembly;

[0058] Figure 8 A longitudinal cross-sectional view of the large cylinder and the small cylinder provided by the present invention after assembly;

[0059] Fig. 9 A three-dimensional model diagram of the bottom cylinder provided by the present invention;

[0060] Fig.10 This is a schematic diagram of the bottom cylinder provided by the present invention after printing and forming.

[0061] In the figure: 1, small cylinder; 2, large cylinder; 3, middle flange; 4, bottom cylinder; 10, forming base plate; 31, step hole; 32, fixing bolt; 33, screw part; 34, cylindrical pad; 35, residual part. DETAILED DESCRIPTION

[0062] In order to make the purpose, technical solution 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 used to limit the present invention.

[0063] The present invention is described by taking a certain type of multi-structure part as an example. Due to its complex structure, the present invention uses its simplified form as an example for the convenience of description. However, the present invention is not limited to the specific cases shown in the figure. All cases derived from the design ideas and methods of the present invention are the protection points of the present invention. Its structural morphology schematic diagram is shown in FIG. Figure 1 and Figure 2 As shown, it is defined as a multi-structure.

[0064] Figure 1 and Figure 2 This is only a schematic diagram of the present invention. In actual products, different cylinders may represent different structures such as pipelines, lugs, cylinders, node balls, connecting valves, etc., and are interconnected with other structural components. The intermediate flange itself can also play the role of sealing connection. Due to the variety of structural forms of actual parts, the present invention is based on Figure 1 and Figure 2 The simplified structures shown are described for illustrative purposes only to facilitate understanding of the basic principles and implementations of the invention.

[0065] Figure 1 and Figure 2The multi-structure shown in the figure has very high strength requirements. If it is only judged from the appearance, it can be processed by casting. However, the casting method often has casting defects such as sand holes and looseness, which cannot meet the strength requirements of the product. Especially for pipeline parts, sand holes and loose parts often become the starting point of stress corrosion in the case of long-term service. After long-term work, it is easy to break the wall and leak, which cannot meet the functional requirements of the product. If the conventional forging blank is prepared and the machining method is used, due to the limitation of the bending and torsion structure of the large cylinder, the small cylinder and the bottom cylinder, the tool cannot go deep into the inner cavity of the cylinder for processing. Even if it can be processed, a larger blank is required, and it is processed little by little by the tool through the CNC machining center. It is time-consuming and labor-intensive, the processing cost is high, and the material utilization rate is extremely low. If 3D printing is used for preparation, although it can be prepared without a mold at one time, no matter how the placement angle is adjusted, a large amount of support needs to be added to the suspended part before printing. And the subsequent auxiliary processes such as support removal and grinding are also cumbersome. If the above parts are split into multiple parts, they are welded after separate processing. The weld penetration is too deep, the welding stress is extremely large, and welding deformation and welding cracks are very likely to occur. Therefore, although traditional processing methods or new technology 3D printing have their own advantages for multi-structure parts, they still cannot be effectively prepared for such parts.

[0066] See also Figures 1 to 10 , the present invention provides a multi-structure composite manufacturing method:

[0067] A forged blank is selected, and its overall size is larger than that of the intermediate flange 3, with a single-side margin of 1 to 5 mm in the thickness direction and a single-side margin of 10 to 50 mm in the length and width directions. Then, according to the three-dimensional model and two-dimensional drawing of the intermediate flange 3 of the multi-structure part, its length, width and height dimensions are determined. Then, the intermediate flange 3 is prepared by mechanical processing, but a single-side margin of 0.1 to 0.2 mm is retained in the thickness direction, and a margin of 5 to 45 mm is retained in the length and width directions. In this way, a high-strength intermediate flange 3 is prepared efficiently and quickly.

[0068] The reason why mechanical processing is used is that the intermediate flange 3 has a simple structure, is convenient for clamping, is easy to process, and has a higher cutting efficiency. It should be noted that four step holes 31 are opened in the margin area 35 around the intermediate flange 3 to facilitate fixation during subsequent processing. Its structural form is as follows Figure 3 to Figure 4 shown.

[0069] This method not only improves the processing efficiency of the intermediate flange 3, but also ensures its strength and quality, providing a reliable basis for subsequent processing and assembly.

[0070] Figure 3 and Figure 4In the figure, the middle flange 3 is tightly fixed to the forming base plate 10 by fixing bolts 32. The forming base plate 10 is used to carry the powder for printing and filling of parts, and its size is basically consistent with the size of the forming cylinder of the 3D printing equipment.

[0071] Figure 4 In the figure, the middle flange 3 of the multi-structure is provided with a margin portion 35, and the margin portion 35 is provided with a step hole 31, specifically a double-ended step hole 31, that is, both sides of the flange are step holes 31, because it is necessary to turn over and print later. In order to avoid the nut part protruding from the flange plane when the screw is fixed, a double-ended step hole 31 is designed.

[0072] As described above, the machined intermediate flange 3 is tightly fixed on the forming base plate 10 by the fixing bolts 32, creating conditions for the subsequent preparation of the large cylinder and the small cylinder 1 on the upper part of the flange.

[0073] The fixed intermediate flange 3 and the forming substrate 10 are installed together in the 3D printing equipment, and placed and fixed on the 3D printing platform. Powder is filled into the 3D printing forming chamber. The powder can be metal powder or non-metallic, ceramic and other powders. Considering that conventional materials are generally metals, the present invention is described by taking metal materials as an example. The material of the metal powder is consistent with that of the intermediate flange, and can be aluminum alloy, titanium alloy, high temperature alloy, stainless steel, iron-nickel alloy, etc. This article takes TC4 titanium alloy as an example for description.

[0074] After the TC4 metal powder is loaded, a metal scraper is used to compact the powder and fill any gaps. Then the powder spreading scraper is manually operated to spread the powder and level the powder. By adjusting the lifting of the forming cylinder, only a thin layer of metal powder is left on the top of the middle flange, with a powder thickness of 0 to 0.06 mm.

[0075] Then, the forming chamber door is closed, the forming chamber is inflated, and the forming substrate 10 is turned on for heating.

[0076] Will be like Figure 5 The three-dimensional models of the large cylinder 2 and the small cylinder 1 shown are exported separately in .stl format files and named as large cylinder 2, small cylinder 1.stl. Then, use 3D printing special process software, such as magics, to import large cylinder 2 and small cylinder 1.stl. According to the position and coordinate system of large cylinder 2 and small cylinder 1 on the multi-structure, adjust the coordinate system of large cylinder 2 and small cylinder 1.stl in magics software so that the two are consistent. Then slice according to the predetermined layer thickness d.

[0077] The slices are imported into the 3D printing special process software, and given predetermined forming parameters such as laser power, laser scanning speed, layer thickness, laser scanning spacing, etc. In this way, the printing program of the large cylinder 2 and the small cylinder 1 is formed.

[0078] The above program is imported into the 3D printing device. When the oxygen content in the forming chamber reaches a predetermined value and the temperature of the forming substrate 10 reaches a predetermined temperature, the laser emits light for printing. When scanning the first layer, closely observe the laser scanning path to confirm that the scanning area is at the corresponding position of the middle flange 3.

[0079] After the laser sintering completes the current layer profile section, the forming chamber drops to the preset layer thickness d, the scraper spreads the powder, and the laser sintering is performed again. This cycle is repeated until the printing process of the large cylinder 2 and the small cylinder 1 is completely completed.

[0080] Stop heating the forming substrate 10, and when the temperature of the forming substrate 10 drops to room temperature, open the door of the laser selective melting equipment, disassemble the forming substrate 10, and take out the printed large cylinder 2, small cylinder 1, middle flange 3 and the forming substrate 10 from the forming chamber of the 3D printing equipment.

[0081] Clean the powder on the large cylinder 2, the small cylinder 1, the middle flange 3 and the forming base plate 10 to ensure that the powder is cleaned up.

[0082] Then, a vacuum heat treatment furnace is used to heat treat the large cylinder 2, the small cylinder 1, the middle flange 3 and the forming substrate 10. The purpose of heat treatment is to eliminate the stress generated during the 3D printing process and to regulate the internal organization. The internal metallographic structure of the printed part is basically consistent with the internal metallographic structure of the middle flange 3. In this way, the printed part and the middle flange 3 can be prevented from being cracked and scrapped due to excessive stress from 3D printing, resulting in stress concentration. The metallographic structures of the two can also be homogenized by heat treatment to reduce tissue stress. The heat treatment should be carried out within 12 hours after the large cylinder 2 and the small cylinder 1 are printed.

[0083] Then loosen the fixing bolts 32, remove the large cylinder 2, the small cylinder 1 and the middle flange 3 from the forming base plate 10, so that the multi-structure middle flange 3 and the upper large cylinder 2 and the small cylinder 1 can be obtained. Figure 6 shown.

[0084] Then, the large cylinder 2, the small cylinder 1, and the intermediate flange 3 are turned over and fastened to the forming base plate 10 by fixing bolts 32. Figures 7-8 shown.

[0085] Figure 7In the figure, the forming substrate 10 is used to carry the middle flange 3, the large cylinder 2 and the small cylinder 1, and to carry the powder filled in the forming cylinder when the lower cylinder is printed. The back step hole 31 of the middle flange 3 after turning over is used to pass the fixing bolt 32 shown by the arrow 4. The back of the middle flange 3 after turning over is used to form the bottom cylinder 4 through 3D printing technology based on this part. The fixing bolt 32 passes through the step hole 31 of the middle flange 3 to fix the large cylinder 2, the small cylinder 1 and the middle flange 3 on the forming substrate 10. A cylindrical pad 34 is provided, which is made of stainless steel or titanium alloy. Its height is consistent with or slightly higher than the height of the large cylinder 2 and the small cylinder 1, that is, greater than or equal to the height of the highest cylinder among the large cylinder 2 and the small cylinder 1, and is evenly distributed at the four corners of the middle flange 3, and is relatively close to the fixing bolt 32. Its function is to provide normal support to prevent the large cylinder 2 and the small cylinder 1 from being squeezed when the fixing bolt 32 is tightened, and to prevent the plane of the middle flange 3 from being bent, twisted, deformed and uneven. The heights of the four cylindrical pads 34 are basically the same. By adjusting the appropriate height, the top surface of the fixed middle flange 3 can be flush with the plane on the forming substrate 10, so that the scraper can spread the powder evenly during the subsequent printing of the bottom cylinder 4. If the bottom of the large cylinder 2 and the small cylinder 1 is a plane, it can fit with the forming substrate 10, thereby providing a support force consistent with the cylindrical pads 34. If the bottom is not a plane, its top is kept at a certain distance from the forming substrate 10, generally 1 to 10 mm. The screw portion 33 of the fixing bolt 32 matches the threaded hole of the forming substrate 10.

[0086] As described above, the large cylinder 2, the small cylinder 1 and the middle flange 3 are turned over and tightly fixed on the forming base plate 10 by fixing bolts 32, creating conditions for the subsequent preparation of the bottom cylinder 4.

[0087] Then, the fixed intermediate flange 3, large cylinder 2, small cylinder 1 and forming substrate 10 are installed together in the 3D printing equipment, placed and fixed on the 3D printing platform. Powder is filled into the 3D printing forming chamber. At this time, the powder can be metal powder, or non-metallic powder, ceramic powder, etc. Considering that conventional materials are generally metals, the present invention is described by taking metal materials as an example. The material of the metal powder is consistent with that of the intermediate flange 3, and can be aluminum alloy, titanium alloy, high temperature alloy, stainless steel, iron-nickel alloy, etc. The present invention is described by taking TC4 titanium alloy as an example.

[0088] After the TC4 metal powder is loaded, a metal scraper is used to compact the powder and fill any gaps. Then the powder spreading scraper is manually operated to spread the powder and level the powder. By adjusting the lifting of the forming cylinder, a thin layer of metal powder is left on the top of the middle flange 3, with a powder thickness of 0 to 0.06 mm.

[0089] Then, the forming chamber door is closed, the forming chamber is inflated, and the forming substrate 10 is turned on for heating.

[0090] Will be like Fig. 9 The three-dimensional model of the bottom cylinder 4 shown is exported as a .stl format file, named cylinder.stl. Then, cylinder.stl is imported into a 3D printing special process software such as magics. The coordinate system of cylinder.stl in magics software is adjusted according to the position and coordinate system of the cylinder on the multi-structure so that the two are consistent. Then, it is sliced ​​according to the predetermined layer thickness d.

[0091] The slices are imported into the 3D printing special process software, and given the predetermined forming parameters such as laser power, laser scanning speed, layer thickness, laser scanning spacing, etc. In this way, the printing program of the cylinder is formed.

[0092] The above program is imported into the 3D printing device. When the oxygen content in the forming chamber reaches a predetermined value and the temperature of the forming substrate 10 reaches a predetermined temperature, the laser emits light for printing. When scanning the first layer, closely observe the laser scanning path to confirm that the scanning area is at the corresponding position of the middle flange 3.

[0093] After the laser sintering completes the current layer profile section, the forming chamber drops to the preset layer thickness d, the scraper spreads the powder, and the laser sintering is performed again. This cycle is repeated until the printing process of the large cylinder 2 and the small cylinder 1 is completely completed. Fig.10 shown.

[0094] Stop heating the forming substrate 10, and when the temperature of the forming substrate 10 drops to room temperature, open the door of the laser selective melting equipment, disassemble the forming substrate 10, and take out the printed large cylinder 2, small cylinder 1, middle flange 3, bottom cylinder 4 and the forming substrate 10 from the forming chamber of the 3D printing equipment.

[0095] Clean the powder on the large cylinder 2, the small cylinder 1, the middle flange 3, the bottom cylinder 4 and the forming base plate 10 to ensure that the powder is cleaned up.

[0096] Then, a vacuum heat treatment furnace is used to heat treat the large cylinder 2, the small cylinder 1, the middle flange 3, the bottom cylinder 4 and the forming substrate 10. The purpose of heat treatment is to eliminate the stress generated during the 3D printing process and to regulate the internal organization. The internal metallographic structure of the printed part is basically consistent with the internal metallographic structure of the middle flange 3. In this way, the printed part and the middle flange 3 can be prevented from being cracked and scrapped due to excessive 3D printing stress, resulting in stress concentration. The metallographic structures of the two can also be homogenized by heat treatment to reduce tissue stress. The heat treatment should be carried out within 12 hours after the bottom cylinder 4 is printed.

[0097] Then, loosen the fixing bolts 32, remove the large cylinder 2, the small cylinder 1, the bottom cylinder 4 and the middle flange 3 from the forming base plate 10, so that the middle flange 3, the upper large cylinder 2, the small cylinder 1, and the bottom cylinder 4 can be obtained.

[0098] Although the overall shape of the multi-structure has been obtained at this time, there are still a lot of margins in the length and width directions of the middle flange 3. These margins can be removed by wire cutting, which is low-cost and efficient. Subsequently, the wire cutting surface, the small margin added in the thickness direction of the middle flange 3, and the outer surfaces of the large cylinder 2, the small cylinder 1, and the bottom cylinder 4 formed by 3D printing are polished by bench grinding to prepare a complete multi-structure.

[0099] The structural strength and mechanical properties of the large cylinder 2, small cylinder 1 and bottom cylinder 4 prepared by 3D printing are basically consistent with the middle flange 3 prepared by forging, and the middle flange 3 is used as the forming plane. A complete metallurgical bond can be formed at the joint surface, and the organization can be significantly improved by subsequent heat treatment for organization regulation, which can significantly improve the organization uniformity between the three parts and reduce organization stress.

[0100] When printing the large cylinder 2, the small cylinder 1 and the bottom cylinder 4, the middle flange 3 is used as the forming plane, so that the cylinder part can be placed vertically for forming, avoiding the need to add a large amount of support when forming multiple structures in one piece, significantly reducing the workload of subsequent support removal and grinding, and saving a lot of powder consumption. After the preparation of the multiple structures, the excess of the middle flange 3 can be removed only by wire cutting, which is low-cost, efficient and agile. This significantly reduces the manufacturing cost and equipment procurement costs, and greatly reduces the pressure on the supply chain.

[0101] The large cylinder 2, small cylinder 1, middle flange 3 and bottom cylinder 4 in the multi-structure are all made of the same material. Considering that the large cylinder 2, small cylinder 1 and bottom cylinder 4 can be prepared by 3D printing, the two can be printed with different materials, so the materials of the three can be completely different. In this way, different materials can be selected in a targeted manner according to the use conditions, structural strength and functional requirements of different structures, or composite processing can be prepared by forging or printing. In this way, a multi-structure with a functional gradient can be prepared, which greatly expands the application range of the multi-structure.

[0102] In summary, the multi-structure composite manufacturing method provided by the present invention has the following advantages:

[0103] Improve manufacturing accuracy. Ensure the alignment accuracy between components by performing multiple fixations and adjustments during machining and 3D printing, thereby improving the manufacturing accuracy of the final product. Reduce manufacturing costs. The combination of forging blanks and 3D printing can reduce material waste and processing time, thereby reducing manufacturing costs. Enhance structural strength. The mechanical properties and durability of structural parts can be improved through multiple heat treatments and the use of fasteners. Improve surface quality. Cleaning and polishing between each manufacturing step can significantly improve the surface quality of the final product, making it smoother and more beautiful. Flexibility and customizability. This method is suitable for the manufacture of complex structural parts and can be adjusted according to different design requirements. It has high flexibility and customizability. Reduce subsequent processing. Through a multi-step manufacturing process, most of the structural forming and surface treatment can be completed during the manufacturing process, reducing the need for subsequent processing. Save time. Comprehensively utilize the advantages of machining and 3D printing to shorten the manufacturing cycle and improve production efficiency. This makes the multi-structure composite manufacturing method have significant advantages in the production of high-precision and complex structural parts.

[0104] 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 multi-structure composite manufacturing method, characterized in that: The method comprises the following steps: Step S1, selecting a forging blank for preparing an intermediate flange (3); Step S2, preparing the intermediate flange (3) by mechanical addition, and opening a plurality of step holes (31) on both sides of the intermediate flange (3); Step S3, using a fastener to fix the intermediate flange (3) to the forming base plate (10) through the step hole (31); Step S4, forming the substrate (10) and fixing it on a 3D printing platform; Step S5, performing a first 3D printing to form the large cylinder (2) and the small cylinder (1) on the first flange plane of the middle flange (3) to form a first state structure; Step S6, taking the first state structure out of the forming chamber; Step S7, cleaning the powder on the first state structure; Step S8, performing vacuum heat treatment on the first state structure; Step S9, removing the fastener and the formed substrate (10); Step S10, reverse the structure composed of the large cylinder (2), the small cylinder (1) and the intermediate flange (3), so that the large cylinder (2) and the small cylinder (1) face downward, install fasteners in the step hole (31) and fix them to the forming base plate (10); Step S11, a cylindrical spacer (34) is arranged between the intermediate flange (3) and the forming substrate (10), Step S12, fixing the formed substrate (10) on the 3D printing platform; Step S13, performing a second 3D printing to form the bottom cylinder (4) on the second flange plane of the middle flange (3) to form a second state structure; Step S14, taking the second state structure out of the forming chamber; Step S15, cleaning the powder on the second state structure; Step S16, performing vacuum heat treatment on the second state structure; Step S17, removing the fasteners, the cylindrical spacer (34) and the formed substrate (10); Step S18, performing wire cutting on the remaining portion of the middle flange (3); Step S19, grinding the line-cut surface and the surfaces of each cylinder.

2. The multi-structure composite manufacturing method according to claim 1, characterized in that: The first 3D printing process includes the following steps: Step S201, filling powder into the 3D printing forming chamber; Step S202, compacting the powder with a metal scraper, and manually operating a powder spreading scraper to spread the powder; Step S203, adjusting the lifting and lowering of the forming cylinder until a predetermined thickness of metal powder is left on the top of the middle flange (3); Step S204, importing the three-dimensional models of the large cylinder (2) and the small cylinder (1) into a 3D printing dedicated process software; Step S205, slicing the large cylinder (2) and the small cylinder (1) according to a predetermined layer thickness d; Step S206, assigning forming parameters, and when the oxygen content in the forming chamber reaches a predetermined value and the temperature of the forming substrate (10) reaches a predetermined temperature, laser light printing is performed; Step S207, after the laser sintering of the current layer profile section is completed, the forming chamber is lowered to a predetermined layer thickness d, the scraper spreads the powder, and the laser sintering is performed again, and the cycle is repeated in sequence until the printing procedures of the large cylinder (2) and the small cylinder (1) are completely completed; Step S208, stopping heating of the forming substrate (10), and opening the door of the laser selective melting equipment when the temperature of the forming substrate (10) drops to room temperature.

3. The multi-structure composite manufacturing method according to claim 2, characterized in that: The second 3D printing process includes the following steps: Step S301, filling powder into the 3D printing forming chamber; Step S302, compacting the powder with a metal scraper, and manually operating a powder spreading scraper to spread the powder; Step S303, adjusting the lifting and lowering of the forming cylinder until a predetermined thickness of metal powder is left on the top of the middle flange (3); Step S304, closing the forming chamber door, inflating the forming chamber, and turning on the forming substrate (10) for heating; Step S305, importing the three-dimensional model of the bottom cylinder (4) into a 3D printing dedicated process software, and slicing the bottom cylinder (4) according to a predetermined layer thickness d; Step S306, assigning forming parameters, and when the oxygen content in the forming chamber reaches a predetermined value and the temperature of the forming substrate (10) reaches a predetermined temperature, laser light printing is performed; Step S307, after the laser sintering of the current layer profile section is completed, the forming chamber is lowered to a predetermined layer thickness d, the scraper spreads the powder, and the laser sintering is performed again, and the cycle is repeated in sequence until the printing process of the large cylinder (2) and the small cylinder (1) is completely completed; Step S308, stopping heating of the forming substrate (10), and opening the door of the laser selective melting equipment when the temperature of the forming substrate (10) drops to room temperature.

4. The multi-structure composite manufacturing method according to claim 1, characterized in that: In step S1, the thickness margin of the forged blank is 1 to 5 mm, and the length and width margins are 10 to 50 mm.

5. The multi-structure composite manufacturing method according to claim 4, characterized in that: In step S2, a margin of 0.1 to 0.2 mm is reserved on one side of the intermediate flange (3) in the thickness direction, and a margin of 5 to 45 mm is reserved in the length and width directions.

6. The multi-structure composite manufacturing method according to claim 1, characterized in that: The height of the cylindrical pads (34) is greater than or equal to the height of the highest cylinder among the large cylinder (2) and the small cylinder (1), and is evenly distributed at the four corners of the middle flange (3).

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