Molding method and structure of metal-based sweating and cooling control surface with complex appearance

Abstract

The invention discloses a forming method and structure of a complex-shape metal-based sweating and cooling control surface, relates to the technical field of thermal protection of hypersonic aircrafts, and is used for realizing connection of a front edge structure of a control surface and a main body structure of the control surface. A defocusing electron beam is adopted to preheat the welding part; after the preheating process is ready, an electromagnetic lens is adjusted to focus an electron beam to a welding area of the workpiece, it is ensured that energy of the electron beam can be concentrated on a welding point, and welding of a control plane front edge structure and a control plane main body structure is started; welding pores are eliminated using electron beam modification welding. A complex-shape metal-based sweating cooling control surface structure is manufactured by adopting a complex-shape metal-based sweating cooling control surface forming method, the complex-shape metal-based sweating cooling control surface structure is composed of a control surface front edge structure and a control surface main body structure, and the control surface front edge structure is provided with micro channels. According to the method, the welding connection is realized by adopting a process of combining electron beam defocusing preheating before welding, vacuum electron beam welding and electron beam modification welding, so that the permeability and the pressure-bearing performance of the control surface are ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal protection for hypersonic vehicles, and more particularly to a forming method and structure of a metal-based transpiration cooling rudder surface with a complex shape. Background Art

[0002] During the high-speed flight and atmospheric reentry phases, the leading edge of the rudder surface of the vehicle will be in an extreme thermal environment. The extremely high heat flux density acts on the leading edge of the rudder surface, causing material ablation, which seriously affects the aerodynamic performance and control performance of the vehicle. The thermal protection problem has become one of the core factors restricting the development of hypersonic vehicles, and the development of efficient cooling technologies has become the key to solving the thermal protection problem. Currently, the active cooling thermal protection technologies mainly include film cooling, regenerative cooling, and transpiration cooling. Among them, the transpiration cooling structure based on microporous media can effectively cool the rudder surface with a small amount of coolant. Compared with gaseous coolant, liquid coolant can bring additional latent heat of vaporization due to phase change, which can greatly improve the cooling effect. Therefore, transpiration cooling is an effective measure to solve the thermal protection problem of the leading edge of the hypersonic vehicle rudder surface.

[0003] The transpiration cooling structure of the hypersonic vehicle rudder surface generally consists of two parts: the leading edge structure of the rudder surface with micropores and the dense rudder surface main structure. The main function of the leading edge structure of the rudder surface with micropores is to exude coolant through the microchannels therein. The coolant vaporizes at high temperature to achieve cooling of the leading edge of the rudder surface, while the dense rudder surface main structure is mainly used to provide basic mechanical strength. At the same time, the coolant enters the leading edge of the rudder surface through the cavity inside the rudder surface main structure. Since the pores at the leading edge are relatively small, generally in the micron range, in order to ensure the rapid discharge of the coolant, high-pressure coolant (in the order of megapascals) needs to be introduced into the cavity of the rudder surface main structure, which requires good connection performance between the leading edge of the rudder surface and the rudder surface main body.

[0004] The processing and preparation of this structure usually face various problems. When machining the leading edge of the rudder surface, due to the existence of microchannels, the traditional cutting processing method causes plastic deformation of the material, which will seriously damage the surface pore structure and cause microchannel blockage. When connecting the porous leading edge structure of the rudder surface and the dense rudder surface main structure, since the leading edge structure of the rudder surface is a loose porous structure and the thermal expansion coefficients of the dense rudder surface main material are quite different, using the traditional tungsten inert gas welding (TIG) method will result in large welding stresses, and usually faces serious problems such as cracking, deformation, and delamination, which seriously affect the connection strength between the two and cannot meet the usage requirements; while vacuum electron beam welding will also appear welding defects such as surface pores and internal cold laps, which will also seriously affect the pressure-bearing capacity of the welded structural parts.

[0005] Therefore, how to process and prepare a transpiration cooling rudder surface structure with good mechanical properties without affecting the performance of the rudder front edge structure with microchannels is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0006] In view of this, the present invention provides a method for forming a complex-shaped metal-based transpiration cooling rudder surface and its structure, aiming to solve the above technical problems.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] A method for forming a complex-shaped metal-based transpiration cooling rudder surface, used to realize the connection between the rudder front edge structure and the rudder surface main structure, specifically includes the following steps:

[0009] Vacuum treatment of the processing chamber;

[0010] Preheat the welded parts using a defocused electron beam;

[0011] After the preheating process is ready, adjust the electromagnetic lens to focus the electron beam on the welding area of the workpiece, ensure that the energy of the electron beam can be concentrated on the welding point, and start welding the rudder front edge structure and the rudder surface main structure;

[0012] Use an electron beam to modify the weld to eliminate welding pores.

[0013] Through the above technical solutions, the present invention combines pre-weld electron beam defocusing preheating, vacuum electron beam welding, and electron beam modification welding to connect the porous rudder front edge structure and the dense rudder surface main structure. The porous rudder front edge structure and the dense rudder surface main structure have different thermal expansion coefficients. The conventional argon arc TIG welding process has a high heat input, resulting in welding stress due to thermal expansion mismatch at the welding joint, and a serious cracking tendency. For the porous rudder front edge structure, conventional electron beam welding is prone to welding defects such as pores on the surface of the welding joint and cold laps inside, seriously affecting the ability of the welded structural part to withstand the pressure of the internal coolant. By using the method of preheating with an electron beam before welding, the welding stress can be reduced. Combining with electron beam welding, the problems of large cold laps and cracking in the heat-affected zone after welding in the conventional welding process are solved. For the occasional micro-porosity defects on the surface of the weld seam after pre-weld electron beam defocusing preheating and vacuum electron beam welding, use electron beam modification welding to eliminate the welding pores, achieve good forming on the surface of the weld seam, and ensure the penetration performance and pressure-bearing performance of the rudder surface.

[0014] Preferably, in the above method for forming a complex-shaped metal-based transpiration cooling rudder surface, the processing method of the rudder front edge structure is:

[0015] Use TC4 (Ti6AL4V) powder to press into a blank through a mold and sinter in a vacuum furnace to obtain a porous medium cylindrical blank;

[0016] The obtained porous medium cylindrical blank is subjected to wire cutting processing to obtain a material having a rudder front edge shape;

[0017] The obtained material with the rudder surface front edge shape is processed into grooves by adopting an electric spark machining process to form a rudder surface front edge structure.

[0018] The cylindrical porous medium blank is processed into a complex rudder front edge shape structure by using a combination of wire cutting and electric spark processing technology. This avoids the problem that the cutting surface of the porous material is easily deformed during the processing by the traditional cutting method, thereby blocking the pore structure on the surface. The processing technology of the porous medium material is optimized, and the performance of the porous medium material after processing is guaranteed.

[0019] Preferably, in the above-mentioned complex-shaped metal-based sweat-generating cooling rudder forming method, the processing method of the rudder main body structure is: the rudder main body structure is processed by 3D printing technology, the interior of which is a hollow cavity, and the rudder main body structure is formed with a liquid inlet and a liquid outlet connected to the groove of the front edge structure of the rudder.

[0020] Preferably, in the above-mentioned complex-shaped metal-based sweat-cooling rudder forming method, the rudder main body structure is made of TC4 alloy material.

[0021] Preferably, in the above-mentioned complex-shaped metal-based sweat-cooling rudder forming method, before the processing chamber is evacuated, the workpiece to be processed is cleaned and installed and positioned. The parts to be welded are cleaned to remove the oxide layer and pollutants on the surface.

[0022] Preferably, in the above-mentioned complex-shaped metal-based sweat-cooling rudder forming method, in the installation and positioning step, the cleaned workpiece is fixed on a rotating or moving platform so that the workpiece can be evenly moved or rotated during the welding process.

[0023] Preferably, in the above-mentioned complex-shaped metal-based sweat-cooling rudder forming method, the vacuum degree of the processing chamber is 10 -4 The range of Pa to 10Pa is to prevent air molecules from scattering the electron beam.

[0024] Preferably, in the above-mentioned complex-shaped metal-based sweat-cooling rudder surface forming method, in the step of preheating the weldment with a defocused electron beam, the temperature of the weldment is preheated to 400-500° C. This can reduce the subsequent welding cooling rate, increase the welding pore overflow of the porous material, and achieve good surface and internal forming.

[0025] The present invention also provides a metal matrix transpiration cooling rudder surface structure with a complex shape, which is made by using the above-mentioned forming method of a metal matrix transpiration cooling rudder surface with a complex shape, and is composed of a rudder surface leading edge structure and a rudder surface main body structure. The rudder surface leading edge structure has microchannels.

[0026] Through the above technical solution, the present invention provides a metal matrix transpiration cooling rudder surface structure with a complex shape, which is mainly composed of two parts: a rudder surface leading edge structure with microchannels and a dense rudder surface main body structure. The rudder surface leading edge structure and the rudder surface main body structure are welded and connected by a process combining electron beam defocus preheating before welding, vacuum electron beam welding and electron beam dressing welding, so as to ensure the penetration performance and pressure-bearing performance of the rudder surface.

[0027] Preferably, in the above-mentioned metal matrix transpiration cooling rudder surface structure with a complex shape, the interior of the rudder surface main body structure is a hollow cavity, which serves as the flow channel for the coolant. There are grooves on the joint surface between the rudder surface leading edge structure and the rudder surface main body structure, which are used to introduce the coolant supplied from the hollow cavity into the microchannels through the grooves, and precipitate and evaporate on the surface of the rudder surface leading edge structure. The rudder surface main body structure is a hollow cavity structure. The high-pressure coolant flows from the internal cavity of the rudder surface main body structure into the grooves of the rudder surface leading edge structure, and seeps out to the outer surface of the leading edge through the microchannels of the rudder surface leading edge, and the cooling effect is achieved by the vaporization of the coolant.

[0028] It can be seen from the above technical solution that compared with the prior art, the present invention discloses a forming method and structure of a metal matrix transpiration cooling rudder surface with a complex shape, which has the following beneficial effects:

[0029] 1. Improve the connection performance: By adopting the process combining electron beam defocus preheating before welding, vacuum electron beam welding and electron beam dressing welding, the connection problem between the porous rudder surface leading edge structure and the dense rudder surface main body structure is solved, the connection strength is improved, and the use requirements are met.

[0030] 2. Reduce the welding stress: By means of electron beam preheating, the welding stress is reduced, the cracking tendency caused by different thermal expansion coefficients is reduced, and the welding quality is improved.

[0031] 3. Reduce welding defects: Aiming at the welding defects such as surface pores and internal cold laps that may occur during the electron beam welding process, these defects are eliminated by electron beam dressing welding, and good forming of the weld surface is achieved.

[0032] 4. Ensure the penetration performance and pressure-bearing performance: Through the above welding process, the penetration performance and pressure-bearing performance of the rudder surface are ensured, and the requirements for thermal protection of the leading edge of the rudder surface of a hypersonic vehicle are met.

[0033] 5. Optimize the processing technology: The leading edge structure of the rudder surface adopts wire cutting and electric discharge machining processes, avoiding the problem of pore blockage that may be caused by traditional cutting methods, and ensuring the service performance of the porous medium material after processing.

[0034] 6. Improve the cooling effect: The interior of the rudder surface main structure is a hollow cavity, serving as the flow channel for the coolant. The coolant is introduced into the microchannels through grooves, and precipitates and evaporates on the surface of the leading edge structure of the rudder surface. The cooling effect is achieved by the vaporization of the coolant, improving the cooling efficiency.

[0035] 7. Adapt to high-pressure coolant: Since it is necessary to introduce high-pressure coolant into the cavity of the rudder surface main structure, the structural design and welding process of the present invention can withstand the pressure of the high-pressure coolant, ensuring the stability and reliability of the cooling system.

[0036] 8. Rational structural design: The rudder surface main structure is a hollow cavity structure. The high-pressure coolant flows from the internal cavity of the rudder surface main structure to the grooves of the leading edge structure of the rudder surface, and seeps out to the outer surface of the leading edge through the microchannels of the leading edge of the rudder surface. Such a design is conducive to achieving effective cooling. Description of the Drawings

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on the provided drawings without creative efforts.

[0038] Figure 1 The drawings are the structural schematic diagrams of the complex-shaped metal matrix transpiration cooling rudder surface structure provided by the present invention;

[0039] Figure 2 The drawings are the structural sectional views of the complex-shaped metal matrix transpiration cooling rudder surface structure provided by the present invention;

[0040] Figure 3 The drawings are the structural schematic diagrams of the leading edge structure of the rudder surface provided by the present invention;

[0041] Figure 4 The drawings are the sectional views of the leading edge structure of the rudder surface provided by the present invention.

[0042] Among them:

[0043] 1 - Leading edge structure of the rudder surface;

[0044] 11 - Groove;

[0045] 2 - Rudder surface main structure;

[0046] 21 - Liquid inlet; 22 - Liquid outlet. Specific embodiments

[0047] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0048] See the attached Figure 1 , the embodiments of the present invention disclose a complex - shaped metal - matrix transpiration - cooled rudder - surface structure, which is composed of a rudder - surface leading - edge structure 1 and a rudder - surface main - body structure 2. The rudder - surface leading - edge structure 1 has micro - channels.

[0049] See the attached Figure 2 to the attached Figure 4 , the inside of the rudder - surface main - body structure 2 is a hollow cavity, serving as the flow channel for the coolant. There is a groove 11 on the joint surface between the rudder - surface leading - edge structure 1 and the rudder - surface main - body structure 2, which is used to introduce the coolant supplied from the hollow cavity into the micro - channels through the groove 11, and precipitate and evaporate on the surface of the rudder - surface leading - edge structure 1.

[0050] The rudder - surface main - body structure 2 is formed with a liquid inlet 21 and a liquid outlet 22 that is docked with the groove 11 of the rudder - surface leading - edge structure 1.

[0051] The coolant enters the cavity of the rudder - surface main - body structure 2 from the liquid inlet 21, then enters the groove 11, and seeps out to the outer surface of the leading edge through the micro - channels on the leading edge of the rudder, achieving a cooling effect by the vaporization of the coolant.

[0052] The forming method of the complex - shaped metal - matrix transpiration - cooled rudder - surface structure provided in this embodiment specifically includes the following steps:

[0053] (1) Using TC4 (Ti6AL4V) powder, press it into a blank through a mold, and sinter it in a vacuum furnace to make a cylindrical blank, controlling its porosity at 20.1% ± 0.3%.

[0054] (2) Perform wire - cutting on the porous - medium cylindrical blank obtained in step (1) to obtain a material with the shape of the rudder - surface leading edge.

[0055] (3) For the material with the leading edge shape of the rudder surface obtained by wire cutting in step (2), the groove 11 is machined by the electric discharge machining process. During the electric discharge machining process, the electrode is accurately aligned in the fixture of the spindle head, so that the perpendicularity of the electrode to the machine tool table is less than 0.01 / 100. The upper and lower end faces of the workpiece are kept parallel to the workpiece table. During machining, down-flushing is used, and two standards of rough machining and finish machining are adopted, and a high-voltage and low-voltage composite pulse power supply is used to finally obtain the leading edge structure 1 of the rudder surface. The machining parameters are shown in the following table.

[0056]

[0057] (4) The dense main structure 2 of the rudder surface is machined by the 3D printing process, and its interior is a hollow cavity, serving as the flow channel for the coolant.

[0058] (5) A process combining pre-welding electron beam defocusing preheating and vacuum electron beam welding technology is adopted to weld the leading edge structure 1 of the rudder surface with micropores and the dense main structure 2 of the rudder surface obtained in steps (3) and (4). The specific process route is as follows:

[0059] A: Workpiece preparation: The parts to be welded are cleaned to remove the oxide layer and contaminants on the surface;

[0060] B: Fixing the workpiece: The cleaned parts are fixed on a rotating or moving platform in the vacuum chamber so that the workpiece can be evenly moved or rotated during the welding process;

[0061] C: Vacuum treatment: The vacuum chamber is pumped to a certain vacuum degree, usually in the range of 10 -4 Pa to 10 Pa, to prevent air molecules from scattering the electron beam;

[0062] D: Electron beam defocusing preheating: After conventional vacuum electron beam welding, dense pores and cold laps appear inside the weld and on one side of the heat-affected zone of the porous material, and serious welding cracks are prone to appear in the heat-affected zone on the porous side. In order to reduce the occurrence of welding cracks, before formal welding, the welded parts are preheated with a defocused electron beam, and the temperature of the welded parts is preheated to 400 - 500 °C, which can reduce the subsequent welding cooling rate, improve the overflow of welding pores in the porous material, and achieve good forming on the surface and inside.

[0063] E: Vacuum electron beam welding: After the preheating process is ready, the electromagnetic lens is adjusted to focus the electron beam on the welding area of the workpiece, ensuring that the energy of the electron beam can be concentrated on the welding point, and the welding process is started.

[0064] F: Electron beam dressing welding: For the occasional micro-porosity defects on the weld surface after electron beam defocusing preheating and vacuum electron beam welding, electron beam dressing welding is used to eliminate the welding pores, achieve good forming on the weld surface, and ensure penetration testing and test pressure.

[0065] The present invention optimizes the processing technology of the transpiration cooling rudder surface structure, ensuring its service performance; it also optimizes the welding technology of the transpiration cooling rudder surface structure, ensuring the mechanical properties after welding of the rudder front edge structure with microchannels and the dense rudder surface main structure, which facilitates filling the cavity of the rudder surface main structure with coolant under high pressure and seeping out through the microholes on the rudder front edge.

[0066] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. For the same or similar parts among the various embodiments, reference can be made to each other. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple. For related parts, reference can be made to the description in the method part.

[0067] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for forming a complex-shaped metal-based sweat-cooling rudder surface, characterized in that: The method is used to realize the connection between the rudder front edge structure and the rudder main body structure, and specifically comprises the following steps: Vacuuming the processing chamber; Use a defocused electron beam to preheat the weldment; After the preheating process is ready, adjust the electromagnetic lens to focus the electron beam on the welding area of ​​the workpiece to ensure that the energy of the electron beam can be concentrated on the welding point, and start welding the leading edge structure of the rudder and the main structure of the rudder surface; Eliminate weld porosity using electron beam touch-up welding.

2. The complex-shaped metal-based sweat-cooling rudder forming method according to claim 1 is characterized in that: The processing method of the front edge structure of the rudder is: TC4 (Ti6AL4V) powder is pressed into a blank through a mold and sintered in a vacuum furnace to obtain a porous medium cylindrical blank; The obtained porous medium cylindrical blank is subjected to wire cutting processing to obtain a material having a rudder front edge shape; The obtained material with the rudder surface front edge shape is processed into grooves by adopting an electric spark machining process to form a rudder surface front edge structure.

3. The method for forming a complex-shaped metal-based sweat-cooling rudder surface according to claim 2, characterized in that: The processing method of the rudder surface main structure is: the rudder surface main structure is processed by 3D printing technology, the interior of which is a hollow cavity, and the rudder surface main structure is formed with a liquid inlet and a liquid outlet connected with the groove of the front edge structure of the rudder surface.

4. The complex-shaped metal-based sweat-cooling rudder forming method according to claim 3 is characterized in that: The main structure of the rudder is made of TC4 alloy material.

5. The complex-shaped metal-based sweat-cooling rudder forming method according to claim 1 is characterized in that: Before the processing chamber is evacuated, the workpiece to be processed is cleaned and installed and positioned.

6. The complex-shaped metal-based sweat-cooling rudder forming method according to claim 5 is characterized in that: In the step of mounting and positioning, the cleaned workpiece is fixed on a rotating or moving platform.

7. The complex-shaped metal-based sweat-cooling rudder forming method according to claim 1 is characterized in that: The vacuum degree of the processing chamber is 10 -4 In the range of Pa~10Pa.

8. The complex-shaped metal-based sweat-cooling rudder forming method according to claim 1 is characterized in that: In the step of preheating the weldment using a defocused electron beam, the weldment is preheated to a temperature of 400-500°C.

9. A complex-shaped metal-based sweat-cooling rudder structure, characterized in that: The complex-shaped metal-based sweat-cooling rudder surface is made by the forming method of any one of claims 1 to 8, and consists of a rudder surface front edge structure and a rudder surface main body structure, wherein the rudder surface front edge structure has micro-channels.

10. A complex-shaped metal-based sweat-cooling rudder surface structure according to claim 9, characterized in that: The interior of the rudder surface main structure is a hollow cavity, which serves as a flow channel for the coolant. The joint surface between the rudder surface front edge structure and the rudder surface main structure is provided with a groove, which is used to guide the coolant supplied into the hollow cavity into the microchannel through the groove, and precipitate and evaporate on the surface of the rudder surface front edge structure.

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