Launch vehicle propellant tank dome and method of assembly

Abstract

The application provides a launch vehicle storage tank short shell and a combined manufacturing method, a milling of a one-size-fits-all plane combined short shell wall plate can directly avoid the manufacturing cost of a special tooling for milling of a curved short shell wall plate, and a three-axis numerical control milling machine or a machining center can be used instead of a five-axis machining center, while a large amount of loading and unloading, tool changing and polishing time is reduced, the processing efficiency is effectively improved, and the processing cost is reduced; the combined manufacturing method of multiple short shells can batch produce the short shells, the forming loading and unloading, machining tool changing and polishing time of each short shell wall plate under the current single-piece production mode of the short shell can be saved, the use efficiency of a longitudinal seam friction stir welding equipment is greatly improved, the production efficiency of the short shell is significantly improved, the manufacturing period is reduced, and the labor intensity of workers is reduced.

Description

Technical Field

[0001] This invention belongs to the field of metal plastic forming technology, specifically, it relates to a short shell of a launch vehicle propellant tank and a method for assembling and manufacturing it. Background Technology

[0002] Currently, the short shell panels of domestic launch vehicle propellant tanks are generally produced in single-piece form. A short shell is made up of 3 to 4 curved short shell panels welded together on a longitudinal seam friction stir welding machine. The production process of each short shell panel mainly includes aluminum alloy flat plate roll bending, machine milling of grid ribs, repeated hammering and mechanical straightening, panel welding, and cutting.

[0003] Patent CN119057210A provides a manufacturing process for a large stainless steel rocket short tube, including obtaining a first sub-steel plate, placing the stainless steel plate on a welding platform and cutting it into multiple rectangular first sub-steel plates; obtaining a second sub-steel plate, sequentially butt-jointing the long sides of the multiple first sub-steel plates and laser welding the butt joints of adjacent first sub-steel plates to form a second sub-steel plate containing multiple first welds; obtaining a third sub-steel plate, cutting the second sub-steel plate to form a rectangular third sub-steel plate; when cutting the second sub-steel plate, the angle between one long side of the third sub-steel plate and one long side adjacent to the second sub-steel plate is A, and the angle between one short side of the third sub-steel plate and one short side adjacent to the second sub-steel plate is B; obtaining a short tube flat plate, sequentially butt-jointing the short sides of the multiple third sub-steel plates and laser welding the butt joints of adjacent third sub-steel plates to form a second weld, thus forming the rocket short tube.

[0004] The traditional process and patent CN119057210A have the following problems: (1) Milling is used to process aluminum alloy curved panels, so a five-axis machining center must be used, which has low processing efficiency and high cost; and special curved surface fixtures are required to fix the sheet material. Different special fixtures are required for short shell wall panels with different curvatures and heights, which greatly increases the manufacturing and management costs. (2) Due to the complexity of the structure of some complex structures (such as radial rib structures), the undesirable deformation of the forming process of short shell wall panels is more significant, the forming accuracy is poor, and subsequent correction can only be solved by more time and labor. (3) After roll bending, the residual stress inside the sheet material is large. During the milling of the mesh ribs, a large amount of material is removed, and the residual stress is released in large quantities. The resulting curved wall panel will have obvious undesirable deformation, with three different types of deformation forms: bending, twisting and warping. The correction workload is large and it is difficult to find a unified correction criterion. The correction labor intensity is high and the efficiency is low. (4) Short shell wall panels are produced in single pieces, and the manufacturing process is complicated. The manufacturing cycle of a single short shell is long. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this invention is to provide a short shell for a launch vehicle propellant tank and a method for its assembly and manufacturing.

[0006] A method for manufacturing a short shell assembly of a launch vehicle propellant tank according to the present invention includes: S1, unfold the three-dimensional model of the short shell panel into a planar short shell panel, and splice N identical short shell panels along the axial direction to form a planar composite short shell panel model; in the spliced ​​composite short shell panel model, there is a cutting allowance area between every two short shell panels, and a machining allowance area is left around the composite short shell panel model. S2, the flat blank is machined according to the combined short shell wall panel model to mill out the grid structure and obtain the combined short shell wall panel. On the same machine tool, a row of scribing lines is scribed in the machining allowance area at both ends of the length direction of the combined short shell wall panel, and a number is marked next to the scribing lines. S3, Conduct finite element simulation calculations for the equidistant bending forming of the combined short shell panel, and set the equidistant bending process parameters based on the finite element simulation results; S4. On a CNC bending machine, the engraved lines at both ends of the combined short shell panel are used as the positioning reference for the bending path. The panel is bent at equal intervals according to the equal interval bending process parameters to obtain a curved combined short shell panel. S5, remove the machining allowance area around the curved composite short shell wall panel; S6, The combined short shell wall panels are welded into a combined short shell cylinder in a longitudinal seam friction stir welding equipment; S7, cut off the cutting allowance area between the short shell panels in the combined short shell cylinder to obtain N individual launch vehicle propellant tank short shells.

[0007] Preferably, the number N of the short shell panels is 2 to 10.

[0008] Preferably, the short shell panels are spliced ​​along the axial direction to form a combined short shell panel model in a mirror arrangement of upright-reverse-upright-reverse.

[0009] Preferably, the width of the cutting allowance area is 10-20 mm.

[0010] Preferably, the width of the machining allowance area is 30–100 mm.

[0011] Preferably, the flat blank is machined using a three-axis machining center according to the combined short shell wall panel model.

[0012] Preferably, the engraving lines correspond one-to-one with the numerical designations.

[0013] Preferably, laser cutting is used to remove the machining allowance around the curved composite short shell wall panel.

[0014] Preferably, laser cutting is used to remove the cutting allowance between the short shell panels in the combined short shell cylinder.

[0015] The present invention also provides a short shell for a launch vehicle propellant tank, which is manufactured by any of the above-described methods for assembling and manufacturing a short shell for a launch vehicle propellant tank.

[0016] Compared with the prior art, the present invention has the following beneficial effects: (1) Milling a multi-in-one planar composite short shell wall panel can directly eliminate the manufacturing cost of special tooling for milling curved short shell wall panels, and can use a three-axis CNC milling machine or machining center instead of a five-axis machining center. At the same time, it can reduce a lot of loading, unloading, tool changing and grinding time, which can effectively improve processing efficiency and reduce processing costs. (2) For short shell panels with complex rib structure, by designing the stacking method of each short shell panel in a targeted manner, the undesirable deformation / uniform deformation of the short shell panels during the pressing and bending process can be mutually canceled, which is conducive to improving the pressing and bending accuracy, reducing the amount of correction, and reducing labor intensity. (3) By adopting the manufacturing method of "milling before bending", the combined short shell wall panel after equidistant bending can achieve the target accuracy without or with only a small amount of adjustment, which greatly reduces the labor intensity of workers. (4) The method of combining multiple short shells can mass-produce short shells, which can save the time of forming, unloading, machining, tool changing and grinding of each short shell panel under the current single-piece production method. It can greatly improve the efficiency of longitudinal seam friction stir welding equipment, significantly improve the production efficiency of short shells, reduce their manufacturing cycle and reduce the labor intensity of workers. Attached Figure Description

[0017] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 A schematic diagram illustrating the implementation process of an efficient assembly manufacturing method for the short shell of a launch vehicle propellant tank; Figure 2 This is a schematic diagram of a composite short shell panel structure. Figure 3 A schematic diagram of a combined short shell panel bent by a CNC bending machine; Figure 4 This is a schematic diagram of the structure after bending the combined short shell wall panel. Figure 5 A schematic diagram of a curved composite short shell wall panel for removing machining allowance areas; Figure 6 This is a schematic diagram of the structure of a combined short shell cylinder; Figure 7 A schematic diagram of the structure of multiple individual launch vehicle propellant tank short shells obtained by removing the cutting margin area.

[0018] The diagram shows: 1. Short shell panel; 2. Cutting allowance area; 3. Machining allowance area; 4. Scribe line; 5. Composite short shell panel; 6. Upper bending die; 7. Lower bending die; 8. Composite short shell body; 9. Launch vehicle propellant tank short shell. Detailed Implementation The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0019] like Figures 1 to 7 As shown, this embodiment provides a method for manufacturing a short shell assembly of a launch vehicle propellant tank, the specific steps of which include: S1, unfold the three-dimensional model of the short shell wall panel into a planar short shell wall panel 1, and splice N identical short shell wall panels 1 along the axial direction to form a planar combined short shell wall panel model; in the spliced ​​combined short shell wall panel model, there is a cutting allowance area 2 between every two short shell wall panels 1, and a machining allowance area 3 is left around the combined short shell wall panel model. S2, the flat blank is machined according to the combined short shell wall panel model to mill out the grid structure and obtain the combined short shell wall panel 5. On the same machine tool, a row of scribing lines 4 are respectively scribed in the machining allowance area 3 at both ends of the length direction of the combined short shell wall panel 5 using scribing tools, and the numerical number is marked next to the scribing lines 4. S3, carry out finite element simulation calculation of equidistant bending forming of combined short shell wall panel 5, and set equidistant bending process parameters according to the finite element simulation results; S4, On the CNC bending machine, the engraved lines 4 at both ends of the combined short shell wall panel 5 are used as the positioning reference for the bending path. The equidistant bending is performed according to the equidistant bending process parameters to obtain the curved surface combined short shell wall panel. S5, laser cutting is used to remove the machining allowance area 3 around the curved composite short shell wall panel; S6, the combined short shell wall panel 5 is welded into a combined short shell cylinder 8 in a longitudinal seam friction stir welding equipment; S7. Laser cutting is used to remove the cutting allowance area 2 between each short shell wall plate 1 in the combined short shell body 8 to obtain multiple individual launch vehicle propellant tank short shells 9.

[0020] Since the short shell wall panel 1 has radial ribs, the arrangement of the short shell wall panel 1 adopts a mirror arrangement of upright-reverse-upright-reverse. Through this mirror arrangement, the uneven deformation between two adjacent short shell wall panels 1 can be mutually canceled during the bending process, thereby reducing the unwanted deformation / deformation unevenness during the bending process to a certain extent.

[0021] The number N of short shell panels 1 is 2 to 10. The width of the cutting allowance area 2 is 10 to 20 mm. The width of the machining allowance area 3 is 30 to 100 mm. The flat blank is machined using a three-axis machining center according to the combined short shell panel model. The engraving lines 4 correspond one-to-one with the numerical designations.

[0022] Example 1 The three-dimensional model of the short shell wall panel with radial rib structure is flattened into short shell wall panel 1. Four identical planar short shell wall panels 1 are spliced ​​together along the axis to form a combined short shell wall panel model. In the combined short shell wall panel model, a 20mm cutting allowance area 2 is left between every two short shell wall panels 1. A 50mm machining allowance area 3 is left around the perimeter of the combined short shell wall panel model. Since the short shell wall panel 1 has radial ribs, the arrangement of the short shell wall panel 1 adopts a mirror arrangement of upright-reverse-upright-reverse. Through this mirror arrangement, the uneven deformation between two adjacent short shell wall panels 1 can be mutually canceled during the bending process, thereby reducing the unwanted deformation / deformation unevenness during the bending process to a certain extent.

[0023] The flat blank is machined according to the combined short shell wall panel model to mill out the grid structure and obtain the combined short shell wall panel 5. On the same machine tool, a row of scribing lines 4 are scribed on the machining allowance area 3 at both ends of the combined short shell wall panel 5 along the length direction using a scribing tool, and a number is marked next to the scribing line 4. The scribing line 4 and the number are in a one-to-one correspondence between the machining allowance area 3 at both ends.

[0024] Finite element simulation calculations were carried out on the equidistant bending forming of the combined short shell panel to calculate the stress-strain distribution, springback, and other results under different process parameters. Based on the finite element simulation results, the equidistant bending process parameters were set.

[0025] On a CNC bending machine, the combined short shell panel 5 is placed between the upper bending die 6 and the lower bending die 7. The engraving lines 4 and the number on both ends of the combined short shell panel 5 are used as the positioning reference for the bending path. The combined short shell panel 5 is bent at equal intervals according to the set equal-interval bending process parameters to ensure that all areas of the combined short shell panel 5 are bent to the target curvature.

[0026] Laser cutting is used to remove the machining allowance 3 around the perimeter of the bent and shaped combined short shell wall panel 5.

[0027] The combined short shell wall panel 5 is welded into a combined short shell cylinder 8 in a longitudinal seam friction stir welding equipment, resulting in the combined short shell cylinder 8.

[0028] A laser cutting machine was used to remove the cutting allowance area 2 between the short shell wall panels 1 in the combined short shell body 8, resulting in multiple individual launch vehicle propellant tank short shells 9.

[0029] The efficient assembly manufacturing method for the short shell of a launch vehicle propellant tank directly eliminates the manufacturing cost of milling fixtures for curved wall panels, and uses a three-axis CNC milling machine or machining center instead of a five-axis machining center, reducing machining time by 30% and machining costs by 70%.

[0030] By designing the stacking method of the short shell wall panel 1 of the complex rib structure (such as the radial rib structure), the undesirable deformation / uniform deformation of the short shell wall panel 1 during the compression bending process can be mutually canceled, which can effectively improve the compression bending accuracy, reduce the amount of straightening, and reduce the labor intensity.

[0031] The equidistant bending forming process ensures that the wall panel accuracy directly meets the design target requirements after bending, eliminating the need for additional manual or mechanical correction.

[0032] It has enabled the mass production of the launch vehicle propellant tank short shell 9, increasing the manufacturing efficiency of the launch vehicle propellant tank short shell 9 by more than 50% and reducing the cost by more than 30%.

[0033] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0034] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A method for manufacturing a short-shell assembly of a launch vehicle propellant tank, characterized in that, include: S1, unfold the three-dimensional model of the short shell wall panel into a planar short shell wall panel (1), and splice N identical short shell wall panels (1) along the axial direction into a planar combined short shell wall panel model; in the spliced ​​combined short shell wall panel model, there is a cutting allowance area (2) between every two short shell wall panels (1), and a machining allowance area (3) is left around the combined short shell wall panel model. S2, the flat blank is machined according to the combined short shell wall panel model, and the grid structure is milled out to obtain the combined short shell wall panel (5). On the same machine tool, a row of scribing lines (4) are respectively scribed in the machining allowance area (3) at both ends of the length direction of the combined short shell wall panel (5), and the numbers are marked next to the scribing lines (4). S3, carry out finite element simulation calculation of equidistant bending forming of combined short shell wall panel (5), and set equidistant bending process parameters according to the finite element simulation results; S4, On the CNC bending machine, the engraved lines (4) at both ends of the combined short shell wall panel (5) are used as the positioning reference for the bending path. The equidistant bending is carried out according to the equidistant bending process parameters to obtain the curved surface combined short shell wall panel. S5, remove the machining allowance area (3) around the curved composite short shell wall panel; S6, the combined short shell wall panel (5) is welded into a combined short shell cylinder (8) in a longitudinal seam friction stir welding equipment. S7, cut off the cutting allowance area (2) between each short shell wall plate (1) in the combined short shell cylinder (8) to obtain N individual launch vehicle tank short shells (9).

2. The method for manufacturing a short-shell assembly of a launch vehicle propellant tank according to claim 1, characterized in that, The number N of the short shell wall panels (1) is 2 to 10.

3. The method for assembling and manufacturing a short shell of a launch vehicle propellant tank according to claim 1, characterized in that, The short shell panels (1) are spliced ​​together along the axial direction to form a combined short shell panel model, which adopts a mirror arrangement of upright-reverse-upright-reverse.

4. The method for manufacturing a short shell assembly of a launch vehicle propellant tank according to claim 1, characterized in that, The width of the cutting allowance area (2) is 10-20 mm.

5. The method for manufacturing a short shell assembly of a launch vehicle propellant tank according to claim 1, characterized in that, The width of the machining allowance area (3) is 30-100 mm.

6. The method for manufacturing a short shell assembly of a launch vehicle propellant tank according to claim 1, characterized in that, The flat blank is machined using a three-axis machining center according to the combined short shell wall panel model.

7. The method for manufacturing a short-shell assembly of a launch vehicle propellant tank according to claim 1, characterized in that, The engraving lines (4) correspond one-to-one with the numerical codes.

8. The method for manufacturing a short shell assembly of a launch vehicle propellant tank according to claim 1, characterized in that, Laser cutting was used to remove the machining allowance area (3) around the curved composite short shell wall panel.

9. The method for manufacturing a short shell assembly of a launch vehicle propellant tank according to claim 1, characterized in that, Laser cutting was used to remove the cutting allowance area (2) between the short shell wall plates (1) in the combined short shell cylinder (8).

10. A short shell for a launch vehicle propellant tank, characterized in that, It is manufactured by any one of the methods for assembling a short shell of a launch vehicle propellant tank according to claims 1 to 9.

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