Method for forming TA15 titanium alloy cabin section through selective laser melting

Abstract

The invention relates to a method for forming a TA15 titanium alloy cabin section through selective laser melting, belongs to the field of titanium alloy additive manufacturing, and solves the problems of cracking, deformation and difficult support removal caused by lack of an effective support adding method in selective laser melting forming of a large cabin section structure in the prior art. A method for forming a TA15 titanium alloy cabin section through selective laser melting comprises the following steps that S1, a model is designed, and solid supports are arranged, specifically, solid plate-shaped supporting assemblies distributed at equal intervals in the annular direction are designed according to the structural characteristics of the inner profile of the titanium alloy cabin section to be machined, and the solid plate-shaped supporting assemblies are connected with a base plate; triangular plate group supporting structures which are distributed at equal intervals are designed below a suspension surface which cannot be self-formed on the outer profile of the cabin section; s2, model processing; s3, selective laser melting forming; s4, powder cleaning; and S5, linear cutting. And the selective laser melting forming quality of the part is ensured through supporting design and optimization of the part, and the post-treatment period is shortened.

Description

Technical Field

[0001] The present invention relates to the technical field of titanium alloy additive manufacturing, and in particular to a method for forming a TA15 titanium alloy cabin section by laser selective melting. Background Art

[0002] With the rapid development of additive manufacturing technology, more and more products are being manufactured through additive manufacturing. Selective laser melting (SLM) technology is widely used in aerospace, automotive, medical and other fields due to its high precision.

[0003] TA15 titanium alloy, as a near-α-type titanium alloy, has good comprehensive mechanical properties and good welding process performance. It is a material that is widely used in laser additive manufacturing technology and has been widely used in various load-bearing structural parts in the aerospace field.

[0004] As the aerospace industry places increasingly higher demands on flight speed and range, lightweighting has become an important design concept. As an important large-scale load-bearing structure, cabin structures have a significant impact on the realization of overall lightweighting. Compared with the traditional casting skeleton + machining + welding skin, the laser selective melting integrated forming cabin structure can not only greatly reduce the processing cycle, but also optimize the rib structure and form a thinner-walled skin, achieving lightweight integrated forming of the cabin structure.

[0005] The process of laser selective melting is a process in which the laser melts the powder layer by layer and path by path along a specific trajectory. This process will continuously accumulate thermal stress, especially for large-sized thin-walled parts. The accumulated thermal stress will cause the parts to deform and crack during the forming process, seriously affecting product delivery. The internal support structures of large-sized parts commonly used at present are usually composed of dense solid supports and grid supports. There are many support materials, which make it difficult to achieve the purpose of support, easy removal and anti-deformation, which restricts the additive manufacturing of large-sized complex cabin structures.

[0006] In addition, the overhanging surface area is very likely to sag as a whole due to the pull of gravity during the printing process, and certain supports must be set to ensure the printing quality. Although the existing support method can ensure the printing quality, the support structure is difficult to remove, which increases the difficulty of post-processing. Summary of the invention

[0007] In view of the above analysis, an embodiment of the present invention aims to provide a method for laser selective melting of TA15 titanium alloy cabin sections, so as to solve at least one of the problems in the existing additive manufacturing process of large-scale complex cabin structures, such as cracking and deformation of parts or long production cycle caused by insufficient or excessive support, and high consumption and difficulty in removing support materials in the overhanging surface area.

[0008] The embodiment of the present invention provides a method for forming a TA15 titanium alloy cabin section by laser selective melting, comprising the following steps:

[0009] S1. Design the model and set up the solid support: According to the structural characteristics of the inner profile of the titanium alloy cabin to be processed, design a solid plate support component with equal spacing distributed along the circumference and connect it to the base plate; design a triangular plate group support structure with equal spacing distributed below the overhanging surface on the cabin outer profile that cannot be self-formed;

[0010] S2. Model processing: Slice the cabin model after setting the solid support;

[0011] S3, laser selective melting forming: the cabin section with the triangle plate group support structure and the inner surface solid plate support component added in the design model is treated as a complete part and the laser selective melting forming operation is performed, wherein the process parameters of the support structure are the same as those of the cabin section body;

[0012] S4, powder cleaning: After the laser selective melting is completed, the powder is sent to the powder cleaning equipment to complete the inner cavity powder cleaning;

[0013] S5, wire cutting: Use wire cutting to separate the cabin from the substrate after the powder is cleaned, and remove all solid supports by wire cutting.

[0014] Specifically, the titanium alloy cabin section includes a cabin section main body wall panel and an overhang surface, and the overhang surface is located on the outer surface of the cabin section main body wall panel.

[0015] Furthermore, each group of solid plate-like support components includes a web and three wing plates evenly distributed on the web, and the cross-sectional shape of each group of solid plate-like support components is E-shaped; the E-shaped opening faces the inner surface to be supported, and the edge is in contact with the inner surface.

[0016] It should be noted that the height of each set of solid plate-shaped support components is 1 / 2 to 2 / 3 of the cabin height;

[0017] An arched through hole is provided at the bottom of the wing plate of each group of solid plate-shaped support components, and the arch base of the arched through hole is connected to the base plate.

[0018] Furthermore, the angle between the overhanging surface area and the cabin section outer surface is greater than or equal to 45°.

[0019] Specifically, the triangular plate group support structure in step S1 is a plurality of evenly distributed thin-walled triangular solid plates, and the triangular solid plates are printed self-forming structures; the thin-walled triangular solid plates include two triangular main faces, two side edges and one hypotenuse, and the two side edges are respectively fitted with the overhanging surface and the outer surface of the cabin.

[0020] The angle between the hypotenuse and the vertical direction is greater than 45°.

[0021] Furthermore, the ratio of the length to thickness of the thin-walled triangular solid plate along the plane direction under the overhanging surface is (35-50):1.

[0022] Exemplarily, one side of the triangular solid plate is connected to the overhanging surface, and the other side is connected to the outer surface of the cabin, and through the array, a triangular plate group with a spacing of 1-2 mm is formed.

[0023] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0024] 1. The present invention arranges solid plate-shaped support components (such as E-shaped) that are periodically distributed along the annular direction at equal intervals on the inner surface of the cabin main body wall panel. After the three vertical plates are connected into a whole by a horizontal vertical plate, the stability during the printing process is enhanced, and the shaking of a single support sheet with a large height during the forming stage, which causes powder rebound and thus printing failure, is avoided.

[0025] 2. The E-shaped solid plate support component designed in the present invention is a whole, and the support component is connected to the base plate to achieve faster heat transfer, better control the deformation and cracking caused by the accumulation of thermal stress during the cabin printing process, and effectively solve the cracking and deformation problems in the laser selective melting of large thin-walled structures.

[0026] 3. The E-shaped solid plate support components designed in the present invention are arranged regularly along the circumferential direction of the cabin body and can be automatically removed by wire cutting, which significantly improves the post-processing efficiency.

[0027] 4. The present invention adopts a thin-walled solid triangular plate group support structure with equal spacing to support the cabin section overhang surface structure, which is not easy to deform and meets the lightweight requirements. The ratio of the length to thickness of the thin-walled triangular solid plate along the plane under the overhang surface is optimized to (35-50): 1, which ensures the supporting effect and is easier to remove during post-processing, and solves the problems of excessive supporting material and serious material loss in the laser selective melting forming of the overhang surface structure.

[0028] 5. The present invention achieves the synergistic effect of the reinforcing ribs arranged in the inner cavity structure of the upper part of the titanium alloy cabin and the periodically distributed solid plate support components in the lower part of the titanium alloy cabin to control the overall surface accuracy of the cabin to be ≤±1mm, of which the surface accuracy of 80% of the area reaches ≤±0.6mm.

[0029] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0031] Figure 1 A schematic diagram of a TA15 titanium alloy cabin section provided in an embodiment of the present invention;

[0032] Figure 2 A schematic diagram of a TA15 titanium alloy cabin section structure support structure provided in an embodiment of the present invention;

[0033] Figure 3 A schematic diagram of a thin-walled triangular solid plate provided in an embodiment of the present invention;

[0034] Figure 4 Schematic diagram of the TA15 titanium alloy cabin section structure and supporting structure provided in an embodiment of the present invention.

[0035] Reference numerals:

[0036] 1-cabin overhang plane; 2-cabin inner cavity structure; 3-inner cavity powder outlet hole; 4-E-shaped solid plate support component; 41-web; 42-wing plate; 43-arched through hole; 44-matching groove; 5-thin-walled triangular plate; 6-reinforcement rib plate; 7-inner cavity outer wall plate. DETAILED DESCRIPTION

[0037] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0038] A specific embodiment of the present invention discloses a method for forming a TA15 titanium alloy cabin section by laser selective melting, comprising the following steps:

[0039] S1. Design the model and set up the solid support: According to the structural characteristics of the inner profile of the titanium alloy cabin to be processed, design a solid plate support component with equal spacing distributed along the circumference and connect it to the base plate; design a triangular plate group support structure with equal spacing distributed below the overhanging surface on the cabin outer profile that cannot be self-formed;

[0040] S2. Model processing: Slice the cabin model after setting the solid support;

[0041] S3, laser selective melting forming: the cabin section with the triangle plate group support structure and the inner surface solid plate support component added in the design model is treated as a complete part and the laser selective melting forming operation is performed, wherein the process parameters of the support structure are the same as those of the cabin section body;

[0042] S4, powder cleaning: After the laser selective melting is completed, the powder is sent to the powder cleaning equipment to complete the inner cavity powder cleaning;

[0043] S5, wire cutting: Use wire cutting to separate the cabin from the substrate after the powder is cleaned, and remove all solid supports by wire cutting.

[0044] Specifically, the titanium alloy cabin section includes a cabin section main body wall plate and an overhang surface, wherein the overhang surface is located on an outer surface of the cabin section main body wall plate;

[0045] The overhang surface divides the cabin main body wall panel into two parts. During the laser selective melting forming process, the cabin is designed to be placed in a manner that one end face of the cabin main body wall panel is connected to the base plate, the cabin axis is perpendicular to the base plate, the cabin main body wall panel above the overhang surface is the upper half, and the part below the overhang surface is the lower half;

[0046] The titanium alloy cabin section also includes an inner cavity outer wall plate, and the inner cavity outer wall plate, the overhanging surface and the upper half of the outer surface of the cabin main body wall plate constitute an inner cavity structure;

[0047] The inner cavity structure is provided with reinforcing ribs which are distributed at equal intervals along the circumferential direction, and the reinforcing ribs divide the inner cavity structure into a plurality of chambers.

[0048] As a large-sized thin-walled part, the thermal stress accumulated during the laser selective melting forming process of the titanium alloy cabin section may cause deformation and cracking of the part during the forming process; for parts with complex inner cavity structures, powder holes should be designed to facilitate the cleaning of powder, and the internal support structure of large-sized parts commonly used at present is usually composed of dense solid support and grid support, with more support materials, and it is not easy to remove and avoid the inner cavity powder outlet holes. Based on this, the present invention arranges a solid plate-shaped support component (such as an E-shaped) that is periodically distributed along the annular direction at equal intervals on the inner surface of the cabin body wall panel, and supports the cabin overhang surface structure by using a thin-walled solid triangular plate group support structure with equal intervals, thereby enhancing the stability of the printing process, avoiding the shaking of a single high support sheet during the forming stage, resulting in powder rebound and then causing printing failure, ensuring the support effect while being easier to remove during post-processing, and solving the problem of excessive support material and serious material loss in the laser selective melting forming of the overhang surface structure.

[0049] It should be noted that the model processing in step S2 is performed using Magics software; and during the model processing, an inner cavity structure powder outlet hole is set on the overhanging surface.

[0050] Furthermore, the solid plate-shaped support component includes a web and three wing plates perpendicular to the web and evenly distributed on the web, and the cross-sectional shape of the solid plate-shaped support component is an E-shaped shape; the E-shaped opening faces the inner surface to be supported, and the edge is in contact with the inner surface;

[0051] Through the synergistic effect of the reinforcing ribs set in the inner cavity structure of the upper part of the titanium alloy cabin and the periodically distributed solid plate support components in the lower part of the titanium alloy cabin, the overall surface accuracy of the control cabin is achieved to be ≤±1mm, of which the surface accuracy of 80% of the area reaches ≤±0.6mm.

[0052] In a possible design, a circle of boss structures is provided at the lower edge of the cabin section inner profile, and the wing plates in the opening direction of the E-shaped plate are provided with grooves matching the boss structures at their lower ends in order to fully fit with the inner profile.

[0053] After the three wing panels are connected into a whole through a transverse web, the stability during the printing process is enhanced, avoiding the shaking of a single high support sheet during the forming stage, which may cause powder rebound and thus printing failure; at the same time, after becoming a whole, the contact area with the base plate and the inner surface of the cabin is expanded three times, achieving faster heat transfer and better controlling the deformation of the cabin during the printing and heat treatment stages.

[0054] In one possible design, the solid plate support is connected as a whole by three wing plates through a web plate larger than the wing plates, for example, wing plates with a thickness of 0.8 mm and a width of 25.5 mm are connected as a whole by a web plate with a thickness of 1.7 mm and a width of 38.5 mm.

[0055] Specifically, a plurality of solid plate-shaped support components may be provided, and according to the distribution of the reinforcing ribs of the inner cavity structure, the spacing between adjacent solid plate-shaped support components is not greater than the spacing between the reinforcing ribs;

[0056] When the distance between the two is the same, it is preferred to align them, which is beneficial to the transfer of loads and higher stability. When the distance between adjacent solid plate support components is smaller than the distance between the reinforcing ribs, since the support is dense enough, simulation shows that the positional relationship between the two has almost no effect on the structural stability, and they can be arranged in separate arrays.

[0057] The height of each set of solid plate-shaped support components is 1 / 2 to 2 / 3 of the height of the cabin section, which can effectively prevent deformation during the printing process.

[0058] An arched through hole is provided at the bottom of the wing plate of each group of solid plate-shaped support components, and the arch base of the arched through hole is connected to the base plate.

[0059] The design of the arched through hole reduces material loss on the one hand, and serves as an inner circle for reference of the inner cavity support for efficient removal by wire cutting and machining on the other hand;

[0060] Due to the regular distribution of the inner surface annular support structure, most of the structure can be automatically removed by setting the path program of the wire cutting equipment without damaging the part body. The remaining support roots can be removed and polished to a smooth transition by an angle grinder and a pneumatic grinding head, reducing the post-processing cycle of the TA15 titanium alloy large cabin structure.

[0061] Furthermore, the overhang surface area includes an upper plane of the overhang surface, a lower plane of the overhang surface and a side surface of the overhang surface, and the angle between the upper plane of the overhang surface and the outer surface of the cabin section is ≥45°;

[0062] In a possible design, the angle between the overhanging surface area and the cabin section outer profile surface is 90°;

[0063] During the 3D printing process, the area with an angle greater than 45° with the vertical plane and without support from the underlying structure is the overhanging surface. The overhanging surface is very likely to sag as a whole due to the pull of gravity during the printing process, so certain supports must be provided to ensure the printing quality. Compared with block + conical supports, supporting roofs, etc., the support structure of the present invention is easier to remove, reducing the difficulty of post-processing.

[0064] Specifically, the triangular plate group support structure in step S1 is a plurality of evenly distributed thin-walled triangular solid plates, and the triangular solid plates are printed self-forming structures; the thin-walled triangular solid plates include two triangular main faces, two side edges and one hypotenuse, and the two side edges are respectively fitted with the overhanging surface and the outer surface of the cabin.

[0065] Furthermore, the angle between the hypotenuse of the thin-walled triangular solid plate and the vertical direction is greater than 45°; the lengths of the two side edges of the thin-walled triangular solid plate are equal to the cantilever widths of the upper and lower planes of the overhanging surface area; the ratio of the length to the thickness of the thin-walled triangular solid plate along the lower plane of the overhanging surface is (35-50):1;

[0066] Determine the gravity of the overhang surface area according to the cantilever width of the upper and lower planes and the thickness of the side edges; determine the pressure on the connection between the thin-walled triangular solid plate and the cabin's outer surface according to the gravity of the overhang surface area and the angle between the plane on the overhang surface and the cabin's outer surface, and decompose the force to obtain the horizontal and vertical components of the pressure. Determine through simulation calculation that the support requirements can be met when the angle between the hypotenuse of the thin-walled triangular solid plate and the vertical direction is greater than 45°;

[0067] If the angle between the bevel and the vertical direction is too small, printing will be difficult and it will be difficult to remove during post-processing. If the angle between the bevel and the vertical direction is large, it will be beneficial to load dispersion, and the support structure will be more stable, effectively avoiding sagging due to gravity. The loss of support material must be taken into account during design. The larger the angle between the bevel and the vertical direction, the more support material will be lost.

[0068] In a possible design, the angle between the hypotenuse of the triangular solid plate and the vertical direction is 60°.

[0069] Specifically, the ratio of the length of the overhanging surface to the thickness of the support plate is (35-50): 1, which has a better support effect, is not prone to deformation and meets the lightweight requirements;

[0070] In a possible design, the thickness of the support plate is designed. The length of this compartment section in the overhanging surface direction is 38.5 mm, and the thickness is set to 0.8 mm, satisfying a ratio of about 48. It can ensure the support effect while being easier to remove in post-processing. A larger thickness will affect production efficiency.

[0071] Exemplarily, one side of the triangular solid plate is connected to the overhanging surface, and one side is connected to the outer surface of the cabin, and they are arranged in an array to form a triangular plate group with a spacing of 1-2 mm;

[0072] The contact area is increased by chamfering the edges of the triangle plate and the workpiece to support the entire overhanging surface;

[0073] It should be noted that the triangle plate groups are arranged in an array so as to avoid the powder outlet holes in the inner cavity by setting the spacing.

[0074] Exemplarily, in step S3, the laser selective melting forming process parameters are: laser power 160-200 W, scanning rate 600-1000 mm / s, scanning spacing 0.08-0.12 mm, and powder layer thickness 30-40 μm.

[0075] In a possible design, the laser selective melting forming process parameters are: laser power 180W, scanning rate 800mm / s, scanning spacing 0.10mm, and powder layer thickness 30μm.

[0076] Specifically, in the wire cutting process described in step 5, the wire cutting program is set according to the contour and size of the inner and outer surface supports to complete the removal of the solid support.

[0077] A three-coordinate measuring machine is used to measure the external dimensions of the TA15 titanium alloy cabin formed by laser selective melting, and the dimensions are compared with the design model to evaluate the dimensional deviation. By using the support method of the present invention, the deformation during the forming process can be controlled within ±1 mm.

[0078] The present invention designs and optimizes the solid support of the cabin structure. By using E-shaped solid plate support components that are periodically and evenly distributed along the annular direction, the stability of the printing process is enhanced and faster heat transfer is achieved. A thin-walled solid triangular plate group support structure that is evenly distributed is used to support the cabin overhang surface structure, which is not prone to deformation while meeting the lightweight requirements. The quality of the parts laser selective melting molding is ensured and the post-processing cycle is shortened.

[0079] The support structure design of the present invention is described below through specific embodiments.

[0080] Example 1

[0081] The steps of laser selective melting to form the TA15 titanium alloy cabin section in this embodiment are as follows:

[0082] S1. Design the model and set up the solid support: the inner diameter of the cabin section is 650mm, the spacing between the longitudinally periodically arranged reinforcing ribs in the inner cavity structure is 100mm; the cantilever width of the upper and lower planes in the overhanging surface area is 38.5mm, and the angle with the vertical direction is 90°.

[0083] According to the internal surface structural characteristics of the titanium alloy cabin section to be processed, solid plate support components with equal spacing along the circumferential direction are designed and connected to the base plate; the spacing between every two solid plate support components is 36mm, and the height is 197.5mm; the wing plate thickness of the solid plate support component is 0.8mm, and the width is 25.5mm; the transverse web thickness of the solid plate support component is 1.7mm, and the width is 38.5mm; the diameter (span) of the arched hole under the wing plate of the solid plate support component is 9mm, and the total height is 16mm, of which the arch height is 4.5mm.

[0084] A triangular plate group support structure with equal spacing is designed under the overhanging surface on the cabin section's outer surface that cannot be self-formed; the thickness of the triangular solid plate is 0.8 mm, and the angle between the hypotenuse of the triangular solid plate and the vertical direction is 60°.

[0085] S2. Model processing: Slice the cabin model after setting the solid support;

[0086] S3, laser selective melting forming: the cabin section with the triangle plate group support structure and the inner surface solid plate support component added in the design model is treated as a complete part and the laser selective melting forming operation is performed, wherein the process parameters of the support structure are the same as those of the cabin section body;

[0087] The process parameters of laser selective melting are as follows: laser power 180 W, scanning rate 800 mm / s, scanning spacing 0.10 mm, and powder layer thickness 30 μm.

[0088] S4, powder cleaning: After the laser selective melting is completed, the powder is sent to the powder cleaning equipment to complete the inner cavity powder cleaning;

[0089] S5, wire cutting: Use wire cutting to separate the cabin from the substrate after the powder is cleaned, and remove all solid supports by wire cutting.

[0090] After adopting the laser selective melting forming of the present invention, there is no cracking or deformation problem in the cabin section; the triangular solid plate support group reduces material consumption by 60% compared with the traditional "block + cone" support structure; after detection by contour detection equipment, the surface accuracy is 0.6mm, which meets the surface accuracy control requirements.

[0091] In summary, the present invention designs and optimizes the solid support of the cabin structure. By using E-shaped solid plate support components that are periodically and evenly distributed along the annular direction, the stability during the printing process is enhanced, faster heat transfer is achieved, and the forming quality and accuracy of the cabin profile are improved. A thin-walled solid triangular plate group support structure that is evenly distributed is used to support the cabin overhang surface structure, which is not prone to deformation while meeting the lightweight requirements and effectively reducing the loss of support materials.

[0092] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for forming a TA15 titanium alloy cabin section by laser selective melting, characterized in that: The steps include: S1. Design the model and set up the solid support: According to the internal surface structural characteristics of the titanium alloy cabin to be processed, design the solid plate support components distributed at equal intervals along the annular direction and connect them to the base plate; Design a triangular plate group support structure with equal spacing under the overhanging surface that cannot be self-formed on the cabin outer surface; S2. Model processing: Slice the cabin model after setting the solid support; S3, laser selective melting forming: the cabin section with the triangle plate group support structure and the inner surface solid plate support component added in the design model is treated as a complete part and the laser selective melting forming operation is performed, wherein the process parameters of the support structure are the same as those of the cabin section body; S4, powder cleaning: After the laser selective melting is completed, it is sent to the powder cleaning equipment to complete the inner cavity powder cleaning; S5, wire cutting: Use wire cutting to separate the cabin from the substrate after the powder is cleaned, and remove all solid supports by wire cutting.

2. The method according to claim 1, characterized in that The titanium alloy cabin section comprises a cabin section main body wall panel and an overhanging surface, wherein the overhanging surface is located on the outer surface of the cabin section main body wall panel.

3. The method according to claim 1, characterized in that Each set of solid plate-like support components includes a web and three wing plates evenly distributed on the web. The cross-sectional shape of each set of solid plate-like support components is E-shaped; the E-shaped opening faces the inner surface of the main wall panel of the compartment section to be supported, and the edge is in contact with the inner surface.

4. The method according to claim 3, characterized in that The height of each set of solid plate-shaped support components is 1 / 2 to 2 / 3 of the height of the cabin.

5. The anti-deformation method according to claim 3, characterized in that: An arched through hole is provided at the bottom of the wing plate of each group of solid plate-shaped support components, and the arch base of the arched through hole is connected to the base plate.

6. The method according to claim 1, characterized in that: The overhang surface area includes an upper plane on the overhang surface, a lower plane on the overhang surface and a side surface of the overhang surface, and the angle between the upper plane on the overhang surface and the outer surface of the cabin section is ≥45°.

7. The method according to claim 1, characterized in that: The triangular plate group support structure in step S1 is a plurality of evenly distributed thin-walled triangular solid plates, and the triangular solid plates are printed self-forming structures; the thin-walled triangular solid plates include two triangular main faces, two side edges and one hypotenuse, and the two side edges are respectively fitted with the overhanging surface and the outer surface of the cabin.

8. The method according to claim 7, characterized in that: The angle between the hypotenuse of the thin-walled triangular solid plate and the vertical direction is greater than 45°.

9. The method according to claim 7, characterized in that: The ratio of the length to thickness of the thin-walled triangular solid plate along the plane direction under the overhanging surface is (35-50):

1.

10. The method according to claim 7, characterized in that: One side of the triangular solid plate is connected to the overhanging surface, and the other side is connected to the outer surface of the cabin. After being arrayed, a triangular plate group with a spacing of 1-2 mm is formed.

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