Method and system for nearly clean blank making of integral bottom of launch vehicle tank

Abstract

The present invention provides a near-net blank making method and system for the integral bottom of a launch vehicle tank, comprising: step S1: determining the structure and preparation process of a tailor-welded plate according to a bottom design drawing; step S2: preparing a single-layer tailor-welded plate by electron beam welding; step S3: performing solid solution quenching on the single-layer tailor-welded plate; step S4: assembling two single-layer tailor-welded plates, sealing the edges by argon arc welding, and obtaining a double-layer tailor-welded plate; step S5: performing hydraulic bulging on the double-layer tailor-welded plate; step S6: cutting off the margins of the upper and lower flange edges, and simultaneously obtaining two bottom blanks without welds. The present invention adopts a thin plate with a thickness of only 6-15 mm, and adopts electron beam welding of a single-layer plate to achieve a welding coefficient of more than 90%, ensure the uniformity and high ductility of the hydraulic bulging process, fundamentally realize near-net forming, and the formed bottom does not need to be machined, and can be directly used for tank structure assembly, saving a large amount of raw materials and processing costs.

Description

Technical Field

[0001] The invention relates to the technical field of metal forming of space launch vehicles, and in particular to a near-net blank making method and system for the integral bottom of a launch vehicle tank. Background Art

[0002] The tank bottom is an important component of the launch vehicle tank. It is a typical large, complex, thin-walled part. Its curved surface configuration is generally a rotating ellipsoid rotating around a short axis, and the designed effective thickness is only 2-6mm. Traditionally, the "petal forming + welding" method is adopted, but because the tank bottom is an important pressure-bearing component, it is subjected to high internal pressure, axial pressure and vibration loads during flight. The presence of a large number of welds affects the improvement of rocket launch reliability. The "integrated" manufacturing of the launch vehicle tank bottom has become a development trend.

[0003] A literature search of the prior art revealed that the overall forming of the box bottom requires the use of ultra-wide plates that are rolled. Currently, the width of the most advanced rolling lines at home and abroad does not exceed 4.5 meters, and the maximum size of ultra-wide plates that can be rolled in batches is 4.2-4.3 meters. The maximum diameter of the tank ring that can be formed by this wide plate is 3.5-3.8 meters. If the size exceeds this, welded plates must be used.

[0004] The actual problem is that for large-scale circular rings with a diameter of more than 3.8 meters, the process route of "two-by-two thick plate welding + heating spinning + rough turning + quenching + finishing" is generally adopted at home and abroad, which has several major problems: 1. The welding seam is located on the cross-section of the center of the part, and the first damage occurs in this weak area during service; 2. The weld undergoes long-term thermal cycle loading during the heating spinning process, and the microstructure and performance deteriorate; 3. The actual part thickness is 4-8mm. The spinning forming process combines deformation factors such as heat treatment and mechanical processing, requiring a raw material thickness of 40-50mm. The material removed by turning is as high as 90%, and the process flow is complicated, and the forming, welding and flaw detection cycles are long. 4. The cooling amount of the core of the thick plate during quenching is significantly less than that of the surface, resulting in low mechanical properties of the core, while the core is ultimately used for the evaluation of the service performance of the part, and the surface is removed by turning. In the real environment, the existing literature has left enough turning allowance in the thickness direction in the public cases, which will increase the risk of material hardenability. At the same time, the deformation during quenching heat treatment destroys the dimensional accuracy of the blank. If the deformation exceeds tens of millimeters, it is very easy to cause the entire part to be scrapped. Summary of the invention

[0005] In view of the defects in the prior art, the object of the present invention is to provide a method and system for nearly clean blank making of the integral bottom of a launch vehicle tank.

[0006] The method for nearly clean blanking of the integral bottom of a launch vehicle tank provided by the present invention comprises:

[0007] Step S1: Determine the structure and preparation process of the tailor-welded blank according to the box bottom design drawing;

[0008] Step S2: preparing a single-layer tailor-welded blank by electron beam welding;

[0009] Step S3: performing solution quenching on the single-layer tailor-welded blank;

[0010] Step S4: assembling two single-layer tailor-welded blanks and sealing the edges by argon arc welding to obtain double-layer tailor-welded blanks;

[0011] Step S5: hydraulically bulging the double-layer tailor-welded blank;

[0012] Step S6: cutting off the margins of the upper and lower flange edges, and obtaining two box bottom blanks without welds.

[0013] Preferably, the step S2 comprises:

[0014] The width of the first plate is ≥4200mm×(LD+2K), where LD is the diameter of the inscribed circle of the single-layer tailor-welded plate, and K is the width of the second plate; the second and third plates are cut from the length margin of the first plate, and the plate width is ≥4200mm×K;

[0015] The first plate and the second plate are welded by electron beam welding, and then the first plate and the third plate are welded, and non-destructive testing is performed. The electron beam power is 2000W and the feed speed is 300mm / min. The test plate is welded with the same parameters, and the test welding coefficient is not less than 0.9.

[0016] Preferably, step S3 comprises:

[0017] Holding temperature 470℃-530℃, holding time 30-60min, quenching transfer time ≤12s;

[0018] The single-layer tailor-welded blanks after quenching are leveled to optimize the plate shape and the outer gap between the upper and lower plates.

[0019] Preferably, the step S4 comprises:

[0020] Assembling the two single-layer welded blanks after quenching, so that the outer circle projections of the first single-layer welded blank and the second single-layer welded blank overlap; welding the pressure nozzle;

[0021] Inspect and leak test the welds and seals of double-layer tailor-welded blanks.

[0022] Preferably, the step S5 comprises:

[0023] Design a double-layer plate bulging die. The double-layer tailor-welded plate is located between the upper and lower circular ring dies. The inner diameter of the upper and lower circular rings is ≥3.8 meters. The die design adopts a structure that increases the flow resistance of the sheet metal.

[0024] Connect the liquid booster to the pressure nozzle, and the upper and lower rings clamp the mold to provide the clamping force. The booster pressurizes the double-layer welded blanks to fill the space with high-pressure liquid, forming a sealed cavity, and the double-layer plates are deformed.

[0025] The bulging is carried out step by step, and the upper and lower surfaces are scanned in three dimensions during the process and compared with the target surface. When the expected accuracy is reached, the bulging is stopped, and the liquid is unloaded and recovered.

[0026] The nearly clean blank making system for the integral bottom of a launch vehicle tank provided by the present invention comprises:

[0027] Module M1: Determine the structure and preparation process of the tailor-welded blank according to the bottom design drawing;

[0028] Module M2: Preparation of single-layer tailor-welded blanks by electron beam welding;

[0029] Module M3: Solution quenching of single-layer tailor-welded blanks;

[0030] Module M4: Assemble two single-layer tailor-welded blanks and seal the edges by argon arc welding to obtain double-layer tailor-welded blanks;

[0031] Module M5: hydraulic expansion of double-layer tailor-welded blanks;

[0032] Module M6: Cut off the upper and lower flange edge allowances and obtain two box bottom blanks without welds.

[0033] Preferably, the module M2 comprises:

[0034] The width of the first plate is ≥4200mm×(LD+2K), where LD is the diameter of the inscribed circle of the single-layer tailor-welded plate, and K is the width of the second plate; the second and third plates are cut from the length margin of the first plate, and the plate width is ≥4200mm×K;

[0035] The first plate and the second plate are welded by electron beam welding, and then the first plate and the third plate are welded, and non-destructive testing is performed. The electron beam power is 2000W and the feed speed is 300mm / min. The test plate is welded with the same parameters, and the test welding coefficient is not less than 0.9.

[0036] Preferably, the module M3 comprises:

[0037] Holding temperature 470℃-530℃, holding time 30-60min, quenching transfer time ≤12s;

[0038] The single-layer tailor-welded blanks after quenching are leveled to optimize the plate shape and the outer gap between the upper and lower plates.

[0039] Preferably, the module M4 comprises:

[0040] Assembling the two single-layer welded blanks after quenching, so that the outer circle projections of the first single-layer welded blank and the second single-layer welded blank overlap; welding the pressure nozzle;

[0041] Inspect and leak test the welds and seals of double-layer tailor-welded blanks.

[0042] Preferably, the module M5 comprises:

[0043] Design a double-layer plate bulging die. The double-layer tailor-welded plate is located between the upper and lower circular ring dies. The inner diameter of the upper and lower circular rings is ≥3.8 meters. The die design adopts a structure that increases the flow resistance of the sheet metal.

[0044] Connect the liquid booster to the pressure nozzle, and the upper and lower rings clamp the mold to provide the clamping force. The booster pressurizes the double-layer welded blanks to fill the space with high-pressure liquid, forming a sealed cavity, and the double-layer plates are deformed.

[0045] The bulging is carried out step by step, and the upper and lower surfaces are scanned in three dimensions during the process and compared with the target surface. When the expected accuracy is reached, the bulging is stopped, and the liquid is unloaded and recovered.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] (1) The present invention determines the structure and preparation process of the tailor-welded plate according to the design drawing of the tank bottom, and can achieve a completely seamless 4-meter-class integral tank bottom after the weld seam in the flange margin area is removed;

[0048] (2) The present invention uses a thin plate with a thickness of only 6-15 mm, which fundamentally achieves near-net forming. The formed tank bottom does not need to be machined and can be directly used for tank structure assembly, saving a lot of raw materials and processing costs;

[0049] (2) The present invention uses hydraulic bulging of double-layer tailor-welded plates to achieve self-sealing, which has low equipment requirements and high efficiency, and can simultaneously process two products in one bulging operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0051] Figure 1 is a flow chart of the method of the present invention;

[0052] Figure 2 It is a schematic diagram of the splicing of single-layer tailor-welded plates;

[0053] Figure 3 It is a schematic diagram of the assembly and hydraulic bulging process of two layers of double-layer tailor-welded blanks;

[0054] Figure 4 This is a schematic diagram of the product and trimming of the double-layer tailor-welded plate after bulging. DETAILED DESCRIPTION

[0055] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0056] Example 1

[0057] The raw material of this embodiment is 2219 aluminum alloy, the plate thickness is 8 mm, the initial heat treatment state of the plate is M state, and the material utilization rate reaches about 70%, highlighting the near-net forming characteristics of the present invention.

[0058] like Figure 1 As shown, the present invention provides a method for nearly clean blanking of the integral bottom of a launch vehicle tank, comprising:

[0059] Step S100: Determine the structure and preparation process of the tailor-welded blank according to the 4m-class box bottom design drawing;

[0060] Step S200: preparing a high-performance single-layer tailor-welded blank by electron beam welding;

[0061] Step S300: solution quenching of the tailor-welded blanks;

[0062] Step S400: preparing a double-layer tailor-welded blank;

[0063] Step S500: hydraulic bulging of double-layer tailor-welded blanks;

[0064] Step S600: cutting off the margins of the upper and lower flange edges, and obtaining two 4-meter-class box bottom blanks without welds.

[0065] According to the design drawings of the 4m-class box bottom, the structure and preparation process of the welded plate are determined. After the box bottom is finally formed and the flange is cut off, the weld is just cut off, and there is no weld in the effective service area. The diameter LD of the welded plate and the weld position are determined.

[0066] like Figure 2As shown, electron beam welding is used for single-layer flat welded plates. The width of the first plate 2-1 is ≥4200mm×(LD+2K), LD=4800mm, K=330mm. The second plate 2-2 and the third plate 2-3 are obtained by cutting the length margin of the first plate 2-1. The plate width is 4200mm×330mm to ensure that the plate thickness is consistent during welding and there is no connection difference. Electron beam welding is used to weld the first plate and the second plate, and then the first plate and the third plate, and non-destructive testing is performed. The electron beam power is 2000W and the feed speed is 300mm / min. The test plate with the same parameters is welded, and the test welding coefficient is not less than 0.9. The obtained welded plate is cut into a circle with a diameter of LD=4800mm.

[0067] The tailor-welded blanks obtained in step 300 are subjected to quenching heat treatment, with a holding temperature of 470°C-530°C, a holding time of 30-60 minutes, and a quenching transfer time of ≤12 seconds. The tailor-welded blanks after quenching are leveled, the plate shape and the outer clearance of the upper and lower plates are optimized, and the welding quality is improved.

[0068] like Figure 3 The figure shows the hydraulic bulging process and two-layer assembly diagram of the double-layer tailor-welded blank. The outer circle projections of the tailor-welded blank 3-2 and the tailor-welded blank 3-6 are overlapped, and the edges are reliably connected by manual argon arc welding. The pressure nozzle 3-3 is welded, and the double-layer plate weld and sealing conditions are inspected and leak-checked.

[0069] like Figure 3 As shown, the upper ring 3-1 of the bulging die and the lower ring 3-5 of the bulging die are installed on the press platform, the welded double-layer tailor-welded blank is placed between the upper ring 3-1 and the lower ring 3-5, and the liquid booster 3-4 is connected to the pressure nozzle 3-3. The upper and lower rings are closed to provide the clamping force, and the booster pressurizes the double-layer tailor-welded blank to fill the high-pressure liquid, forming a sealed cavity, and the double-layer plate is deformed.

[0070] In this embodiment, the bulging is performed in steps, and the upper and lower mold surfaces are scanned in three dimensions during the process and compared with the target mold surface. After the expected accuracy is achieved, the bulging is stopped, and the liquid is unloaded and recovered.

[0071] In this embodiment, the inner diameter of the upper and lower rings is 4050 mm, and the outer diameter is 4800 mm.

[0072] In this embodiment, the mold design adopts a structure that increases the flow resistance of the sheet material: rolling ribs with a rib height of 25 mm and a radius of 50 mm are set in the upper ring 3-1 and the lower ring 3-5 mold structure to increase the flow resistance of the weld and reduce the risk of wrinkling.

[0073] like Figure 4As shown, the product and trimming of the double-layer tailor-welded blank after bulging of the present invention are schematically shown in the figure. After bulging of the double-sided tailor-welded blank, the upper box bottom 4-1 and the lower box bottom 4-4 are obtained. The trimming line 4-3 is the separation line when the product is cut off. The weld 4-2 is located outside the trimming line 4-3 and does not exist on the final delivered box bottom product.

[0074] Example 2

[0075] The present invention also provides a near-net blank making system for the integral bottom of a launch vehicle tank. The near-net blank making system for the integral bottom of a launch vehicle tank can be realized by executing the process steps of the near-net blank making method for the integral bottom of a launch vehicle tank, that is, those skilled in the art can understand the near-net blank making method for the integral bottom of a launch vehicle tank as a preferred implementation of the near-net blank making system for the integral bottom of a launch vehicle tank.

[0076] The system for nearly net blanking of the integral bottom of a launch vehicle tank provided by the present invention comprises: module M1: determining the structure and preparation process of the tailor-welded plate according to the bottom design drawing; module M2: preparing the single-layer tailor-welded plate by electron beam welding; module M3: performing solid solution quenching on the single-layer tailor-welded plate; module M4: assembling two single-layer tailor-welded plates and sealing the edges by argon arc welding to obtain a double-layer tailor-welded plate; module M5: performing hydraulic expansion on the double-layer tailor-welded plate; module M6: cutting off the margins of the upper and lower flange edges to obtain two bottom blanks without welds at the same time.

[0077] The module M2 includes: the width of the first plate is ≥4200mm×(LD+2K), LD is the diameter of the inscribed circle of the single-layer tailor-welded plate, and K is the width of the second plate; the second plate and the third plate are obtained by cutting the length margin of the first plate, and the plate width is ≥4200mm×K; the first plate and the second plate are welded by electron beam welding, and then the first plate and the third plate are welded, and non-destructive testing is performed, the electron beam power is 2000W, and the feed speed is 300mm / min; the test plate with the same parameters is welded, and the test welding coefficient is not less than 0.9.

[0078] The module M3 includes: a heat preservation temperature of 470°C-530°C, a heat preservation time of 30-60min, and a quenching transfer time of ≤12s; leveling the single-layer tailor-welded plate after quenching, and optimizing the plate shape and the outer gap between the upper and lower plates.

[0079] The module M4 comprises: assembling two single-layer tailor-welded blanks after quenching, overlapping the outer circle projections of the first single-layer tailor-welded blank and the second single-layer tailor-welded blank; welding the pressure nozzle; and inspecting and leak-checking the weld and sealing conditions of the double-layer tailor-welded blanks.

[0080] The module M5 includes: designing a double-layer plate bulging mold, the double-layer tailor-welded plate is located between the upper and lower circular ring molds, the inner diameters of the upper and lower circular rings are ≥3.8 meters, and the structure of increasing the flow resistance of the sheet material is adopted in the mold design; connecting the liquid booster to the pressure nozzle, the upper and lower circular rings are clamped to provide the clamping force, and the booster is pressurized to fill the double-layer tailor-welded plate with high-pressure liquid to form a sealed cavity, and the double-layer plate is deformed; performing step-by-step bulging, performing three-dimensional scanning of the upper and lower surfaces during the process, and comparing them with the target surface, stopping the bulging after reaching the expected accuracy, and unloading and recovering the liquid.

[0081] In the description of the present application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0082] Those skilled in the art know that, in addition to implementing the system, device and its various modules provided by the present invention in a purely computer-readable program code, it is entirely possible to implement the same program in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers and embedded microcontrollers by logically programming the method steps. Therefore, the system, device and its various modules provided by the present invention can be considered as a hardware component, and the modules included therein for implementing various programs can also be considered as structures within the hardware component; the modules for implementing various functions can also be considered as both software programs for implementing the method and structures within the hardware component.

[0083] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A method for nearly clean blanking of the integral bottom of a launch vehicle tank, characterized in that: include: Step S1: Determine the structure and preparation process of the tailor-welded blank according to the box bottom design drawing; Step S2: preparing a single-layer tailor-welded blank by electron beam welding; Step S3: performing solution quenching on the single-layer tailor-welded blank; Step S4: assembling two single-layer tailor-welded blanks and sealing the edges by argon arc welding to obtain double-layer tailor-welded blanks; Step S5: hydraulically bulging the double-layer tailor-welded blank; Step S6: cutting off the margins of the upper and lower flange edges, and obtaining two box bottom blanks without welds.

2. The method for nearly clean blanking of the integral bottom of a launch vehicle tank according to claim 1, characterized in that: The step S2 comprises: The width of the first plate is ≥4200mm×(LD+2K), where LD is the diameter of the inscribed circle of the single-layer tailor-welded plate, and K is the width of the second plate; the second and third plates are cut from the length margin of the first plate, and the plate width is ≥4200mm×K; The first plate and the second plate are welded by electron beam welding, and then the first plate and the third plate are welded, and non-destructive testing is performed. The electron beam power is 2000W and the feed speed is 300mm / min. The test plate is welded with the same parameters, and the test welding coefficient is not less than 0.

9.

3. The method for nearly clean blanking of the integral bottom of a launch vehicle tank according to claim 1, characterized in that: The step S3 comprises: Holding temperature 470℃-530℃, holding time 30-60min, quenching transfer time ≤12s; The single-layer tailor-welded blanks after quenching are leveled to optimize the plate shape and the outer gap between the upper and lower plates.

4. The method for nearly clean blanking of the integral bottom of a launch vehicle tank according to claim 1, characterized in that: The step S4 comprises: Assembling the two single-layer welded blanks after quenching, so that the outer circle projections of the first single-layer welded blank and the second single-layer welded blank overlap; welding the pressure nozzle; Inspect and leak test the welds and seals of double-layer tailor-welded blanks.

5. The method for nearly clean blanking of the integral bottom of a launch vehicle tank according to claim 1, characterized in that: The step S5 comprises: Design a double-layer plate bulging die. The double-layer tailor-welded plate is located between the upper and lower circular ring dies. The inner diameter of the upper and lower circular rings is ≥3.8 meters. The die design adopts a structure that increases the flow resistance of the sheet metal. Connect the liquid booster to the pressure nozzle, and the upper and lower rings clamp the mold to provide the clamping force. The booster pressurizes the double-layer welded blanks to fill the space with high-pressure liquid, forming a sealed cavity, and the double-layer plates are deformed. The bulging is carried out step by step, and the upper and lower surfaces are scanned in three dimensions during the process and compared with the target surface. When the expected accuracy is reached, the bulging is stopped, and the liquid is unloaded and recovered.

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