A combined bending die and bending method for forming a storage tank wall panel

Abstract

The present invention provides a combined bending die and a bending method for forming a storage tank wall panel. The combined bending die is composed of an upper die and a lower die; both the upper and lower dies are composed of N sub-dies in the length direction; where N is determined by the length of the wall panel to be formed. The upper die sub-die is composed of an upper die base, an intermediate pressing block, and two side pressing blocks. Through a variety of cooperation and usage methods, the upper die and the lower die can achieve the bending forming of the ribbed skin in the middle of the wall panel and the thickened skin at both ends, as well as the shape correction of the local deformation insufficient area and the over-deformation area. The present invention provides a combined bending die and a bending method for precision forming of a storage tank wall panel, which can solve the problem of difficult control of the bending forming accuracy of the wall panel and effectively improve the forming accuracy of the wall panel; the present invention can solve the problems that two sets of integral dies are required for traditional wall panel bending, which is time-consuming and laborious during the die replacement process, and the problem that it is time-consuming and laborious to repeatedly turn over the wall panel during shape correction, effectively improving the forming efficiency of the wall panel and the manufacturing efficiency of the storage tank of the launch vehicle.

Description

Technical Field

[0001] The present invention relates to the technical field of metal plastic forming, and particularly relates to a combined bending die and a bending method for forming a storage tank wall panel. Background Art

[0002] The cylindrical section is the main structural component of the storage tank of a launch vehicle. Generally, it is formed by longitudinally welding and splicing 4 circular arc-shaped wall panels. The storage tank wall panel generally uses an equal-thickness flat plate as the blank, and can be manufactured by a method of first machining a grid structure and then bending it. For the storage tank wall panel, its four sides are thickened skin areas, the middle is a ribbed skin area, and there are often discrete boss structures in the ribbed skin area. When using a conventional integral bending die to gradually bend it from a plane to an arc surface, the following problems exist: (1) At both ends of the wall panel in the generatrix direction, there are thickened skins, and in the middle, there are ribbed skins and bosses. During the bending process, the deformation amounts of the above different structures in the generatrix direction are inconsistent. When the length of the wall panel generatrix is up to 5 - 10 meters, the straightness of the generatrix cannot be guaranteed; (2) In the middle ribbed skin area in the arc edge direction of the wall panel, it is suitable to use a wide die for bending to avoid rib instability or cracking, while in the thickened skin areas at both ends, it is suitable to use a narrow die for bending to avoid interference between the die pressing process and the ribs, resulting in the inability to press the local thickened skin. Therefore, in the past, two sets of integral dies were often used during bending, and die replacement was involved during the bending process, which was time-consuming and laborious; (3) Local over-pressing is likely to occur during the wall panel bending process, that is, the bending deformation exceeds the expected deformation. In this case, usually, the wall panel needs to be turned over and then bent and corrected in the reverse direction, and this process has a large workload.

[0003] Limited by the current manufacturing limit of the straight edge length of the wall panel, the length of the cylindrical section is generally not more than 2 meters, resulting in the need for 3 - 10 cylindrical sections to be axially circumferentially welded and spliced to manufacture a single storage tank. During this period, a large amount of welding operations are required, and the resulting circumferential welds have an adverse impact on the reliability and shape accuracy of the storage tank structure. Using 5 - 10-meter-level ultra-long wall panels to manufacture ultra-long cylindrical sections to replace the current cylindrical sections can effectively reduce the number of circumferential welds of the storage tank, which is an effective way to solve this problem. However, with the increase in the length of the wall panel, the problems existing in the above-mentioned bending process become more severe. Summary of the Invention

[0004] The purpose of the present invention is to provide a combined bending die and a bending method for forming a storage tank wall panel. Using this combined bending die can not only meet the bending of the ribbed skin in the middle of the wall panel and the thickened skins at both ends, but also realize the deformation correction of the local deformation deficiency or over-deformation area, and achieve the precision forming of the wall panel. It effectively improves the forming accuracy and efficiency of the storage tank wall panel.

[0005] The technical solution of the present invention is: to provide a combined bending die for forming a storage tank wall panel, which is composed of an upper die and a lower die; the upper die is composed of N upper die sub-molds in the length direction, and the lower die is composed of N lower die sub-molds in the length direction; where N is determined by the length of the storage tank wall panel to be formed, and the upper die and the lower die are used in cooperation;

[0006] The upper die is composed of an upper die base, an intermediate pressing block, and two side pressing blocks. The intermediate pressing block and the two side pressing blocks are both fixedly connected to the upper die base by bolts; the intermediate pressing block and the two side pressing blocks can be used in cooperation with the lower die together or separately for bending;

[0007] When bending the storage tank wall panel, according to the internal structure of the storage tank wall panel, using the combined upper die and lower die as a whole, or splitting them into upper die sub-molds and lower die sub-molds and installing them on a large numerical control bending machine, a bending die for the ribbed skin in the middle of the wall panel, a bending die for the thickened skin at both ends, a calibration die for the insufficiently deformed area locally, and a calibration die for the over-deformed area locally can be formed.

[0008] Another technical solution of the present invention provides a bending method for the above-mentioned combined bending die for forming a storage tank wall panel, including the following steps:

[0009] S1. Bending of the ribbed skin in the middle:

[0010] Connect the intermediate pressing block and the two side pressing blocks to the upper die base by bolts to form an upper die sub-mold; according to the length of the wall panel to be bent, splice multiple upper die sub-molds and lower die sub-molds along the length direction on a large numerical control bending machine to form a bending die for the ribbed skin in the middle of the wall panel; use the bending die for the ribbed skin in the middle of the wall panel to perform step-by-step bending and forming on the ribbed skin area in the middle of the flat wall panel according to a preset path;

[0011] S2. Bending of the thickened skin at both ends:

[0012] Connect the intermediate pressing block to the upper die base by bolts to form an upper die sub-mold, and at the same time reduce the span of the lower die; according to the length of the wall panel to be bent, splice multiple upper die sub-molds and lower die sub-molds along the length direction on a large numerical control bending machine to form a bending die for the thickened skin at both ends of the wall panel; use the bending die for the thickened skin at both ends of the wall panel to perform step-by-step bending and forming on the thickened skin area at both ends of the flat wall panel according to a preset path;

[0013] S3. Calibration of the insufficiently deformed area locally:

[0014] According to the length of the insufficiently deformed area, adjust the number of upper die sub-molds in step S2 or S2 to adapt to the size of the insufficiently deformed area, and form a calibration die for the insufficiently deformed area locally with the lower die; perform secondary bending on the insufficiently deformed area to achieve deformation compensation;

[0015] S4. Calibration of the over-deformed area locally:

[0016] Two side pressing blocks are connected to the upper die base through bolts to form the upper die of the die. According to the length of the local over-deformed area, multiple upper dies and lower dies are spliced along the length direction on a large CNC press brake; the upper die, the lower die, and the area to be corrected of the wall panel are in the same vertical plane; the upper die presses down to perform reverse correction on the local over-deformed area of the wall panel, and the wall panel does not need to be turned over during the correction process.

[0017] Furthermore, according to the finite element simulation results of press bending forming, the intermediate pressing block and the side pressing blocks with different curvatures and widths can be replaced to realize the changes in the widths and curvatures of the upper and lower dies of the press bending, so as to adapt to the precision press bending forming of wall panel components with different structures.

[0018] Furthermore, in the steps S3 and S4, for the areas with insufficient deformation or excessive deformation caused by the difference in the wall panel structure during press bending, the structure and quantity of the upper die are changed to quickly and accurately adjust the upper die surface, and then the deformation correction of the areas with insufficient deformation or excessive press bending is realized, so as to realize the precision forming of the wall panel.

[0019] The beneficial effects obtained by the combined press bending die and press bending method for forming the tank wall panel provided by the present invention are as follows:

[0020] (1) The present invention provides a combined press bending die and press bending method for precision forming of a tank wall panel, which can solve the problem of difficult control of the press bending forming accuracy of the wall panel and effectively improve the forming accuracy of the wall panel; (2) It can solve the problem that two sets of integral dies are required during the traditional press bending of the wall panel, and the process of repeatedly replacing the dies is time-consuming and laborious; as well as the problem that the wall panel needs to be repeatedly turned over during the deformation correction of the traditional wall panel, which is time-consuming and laborious. It effectively improves the forming efficiency of the wall panel and the manufacturing efficiency of the tank of the launch vehicle. Brief Description of the Drawings

[0021] The present invention will be further described below with reference to the drawings:

[0022] Figure 1 It is an end view when press bending the ribbed skin in the middle of the wall panel

[0023] Figure 2 It is a schematic diagram of the integral press bending of the ribbed skin in the middle of the wall panel;

[0024] Figure 3 It is an end view when press bending the thickened skin at both ends of the wall panel;

[0025] Figure 4 It is a schematic diagram of the integral press bending of the thickened skin at both ends of the wall panel;

[0026] Figure 5 It is a schematic diagram of the secondary press bending of the local deformation insufficient area of the wall panel;

[0027] Figure 6It is an end view during reverse straightening of the local over-deformed area of the panel;

[0028] Figure 7 It is a schematic diagram of reverse straightening of the local over-deformed area of the panel.

[0029] In the figure: 1. Upper die holder; 2. Intermediate pressing block; 3. Side pressing blocks; 4. Lower die mold; 5. Panel; 6. Locally thickened boss; A. Upper die mold for pressing and bending the ribbed skin in the middle or the upper die mold for compensating the insufficiently deformed area locally; B. Upper die mold for pressing and bending the thickened skins at both ends; C. Upper die mold for straightening the local over-deformed area. Specific implementation mode

[0030] The following further elaborates on the combined bending die and bending method for forming the storage tank panel proposed by the present invention in conjunction with the accompanying drawings and specific embodiments. According to the following description and claims, the advantages and features of the present invention will be clearer. It should be noted that the accompanying drawings are all in a very simplified form and use non-precise ratios, only for conveniently and clearly assisting in explaining the purpose of the embodiments of the present invention.

[0031] Embodiment 1

[0032] A combined bending die for precision forming of a storage tank panel described in this embodiment. The combined bending die is composed of an upper combined die and a lower combined die. Among them, the upper combined die is composed of several sub-dies in the length direction, and each sub-die is composed of multiple module components, including an upper die holder 1, an intermediate pressing block 2, and side pressing blocks 3. The pressing blocks are connected to the upper die holder by bolts; the lower combined die is composed of several sub-dies 4 in the length direction. The length of each upper die mold and lower die mold is 1000 mm. The panel 5 to be bent is an ultra-long panel with a length of 4800 mm, and there is a square locally thickened boss 6 on the ultra-long panel.

[0033] A method for precision forming and bending of a storage tank panel in this embodiment includes the following steps:

[0034] (a) Pressing and bending the ribbed skin in the middle: Connect the intermediate pressing block 2 and the side pressing blocks 3 to the upper die holder 1 by bolts to form the upper die mold A. The width of the upper die mold is 200 mm, and the assembly is as Figure 1 shown. The length of the ultra-long panel 5 to be bent is 4800 mm. Therefore, 5 upper die molds A and 5 lower die molds 4 are spliced along the length direction on a large CNC bending machine to form a die for pressing and bending the ribbed skin in the middle of the ultra-long plane panel. After assembly, the lengths of the upper and lower dies are both 5000 mm. Use this die to perform step-by-step bending and forming on the ribbed skin area in the middle of the ultra-long plane panel with a pre-milled grid structure according to a preset path. The bending process is as Figure 2 shown;

[0035] (b) Press bending of the skin with thickened ends: Connect the middle pressing block 2 to the upper die holder 1 with bolts to form the upper die B of the die. At the same time, reduce the span of the lower die. The width of the upper die is 50 mm, and the assembly is as shown in Figure 4 . The length of the ultra-long wall panel 5 to be press-bent is 4,800 mm. Therefore, 5 upper die Bs and 5 lower die Bs are spliced along the length direction on a large CNC press brake to form a die for press-bending the skin with thickened ends at both ends of the wall panel. After assembly, the lengths of the upper and lower dies are both 5,000 mm. Use this die to press-bend the skin with thickened ends at both ends of the ultra-long flat wall panel section by section according to the preset path. The press-bending process is as shown in Figure 5 ;

[0036] (c) Compensation for the insufficient deformation area of the local part: After press-bending, Figure 3 there is a problem of insufficient deformation at the dotted line. The length of this area is about 800 mm. Therefore, adjust the number of upper die As in step (a) to 1, and the lower die is the same as that in step (a). The upper and lower dies form a die for straightening the insufficient deformation area of the local part. The total length of the upper die is 1,000 mm, and the total length of the lower die is 5,000 mm. Press-bend the insufficient deformation area for the second time to reach the target size and achieve deformation compensation. The press-bending process is as shown in Figure 3 ;

[0037] (d) Straightening of the over-deformed area of the local part: The existence of the local thickened boss 6 causes over-press-bending in the boss area 6. The length of this area is about 700 mm. Connect the two pressing blocks 3 on both sides to the upper die holder 1 with bolts to form the upper die C of the die. The assembly is as shown in Figure 6 . According to the length of the local over-deformed area, splice 1 upper die C and 5 lower die Bs along the length direction on a large CNC press brake. The lower die only needs to be installed on one side. The total length of the upper die is 1,000 mm, and the total length of the lower die is 5,000 mm. The upper die, the lower die, and the area to be straightened of the wall panel are in the same vertical plane. Press down the upper die to perform reverse straightening on the local over-deformed area of the wall panel. It is not necessary to turn over the wall panel during the straightening process. The straightening process is as shown in Figure 7 .

[0038] In steps (c) and (d), for the areas of insufficient deformation or over-deformation caused by the structural differences of the wall panel during press-bending, the structure and quantity of the upper die are changed to quickly and accurately adjust the upper die surface, and then the deformation correction of the areas of insufficient deformation or over-press-bending is realized, so as to achieve the precision forming of the ultra-long wall panel and effectively improve the forming precision of the ultra-long wall panel.

[0039] According to the theoretical analysis or finite element simulation results of the bending forming of the ultra-long wall panel 5, the intermediate pressing block 2, the two-side pressing blocks 3, and the lower die 4 with corresponding widths and curvatures are selected to form the upper and lower dies. Then, according to the length of the ultra-long wall panel 5 and the bending steps, the number of the upper and lower die modules in the length direction is determined to form the bending die, which can increase the applicability of the bending die, realize the forming and shape correction of different structural areas inside the wall panel, and improve the accuracy of the wall panel bending forming. In addition, it also solves the problems that two sets of integral dies are required for bending the wall panel by the traditional method, involving die replacement in the middle, which is time-consuming and laborious, and the problem that the wall panel may need to be turned over repeatedly during the deformation correction process, which is time-consuming. It can effectively reduce the die replacement time and improve the forming efficiency of the wall panel. Taking the kerosene storage tank of a certain type of launch vehicle as an example, the straightness of the generatrix of its ultra-long wall panel after being bent and formed by the die described in the present invention is 4 times higher than that after being bent by the conventional die, and the efficiency is increased by more than 30%.

[0040] The content not described in detail in this specification belongs to the prior art well-known to those skilled in the art. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention.

Claims

1. A bending method for a combined bending die for forming a storage tank wall panel. The combined bending die for forming a storage tank wall panel is composed of an upper die and a lower die; The upper die is composed of N upper die sub - dies in the length direction, and the lower die is composed of N lower die sub - dies in the length direction; where N is determined by the length of the storage tank wall panel to be formed, and the upper die and the lower die are used in cooperation; The upper die sub - die is composed of an upper die base, an intermediate pressing block, and two side pressing blocks. The intermediate pressing block and the two side pressing blocks are both fixedly connected to the upper die base by bolts; the intermediate pressing block and the two side pressing blocks are used in cooperation with the lower die together or separately for bending; When bending the storage tank wall panel, according to the internal structure of the storage tank wall panel, using the combined upper die and lower die as a whole, or splitting them into upper die sub - dies and lower die sub - dies and installing them on a large - scale numerical control bending machine, a bending die for the ribbed skin in the middle of the wall panel, a bending die for the thickened skin at both ends, a straightening die for the insufficiently deformed area, and a straightening die for the over - deformed area can be formed; It is characterized in that It includes the following steps: S1. Bending of the ribbed skin in the middle: Connect the intermediate pressing block and the two side pressing blocks to the upper die base by bolts to form an upper die sub - die; according to the length of the wall panel to be bent, splice multiple upper die sub - dies and lower die sub - dies along the length direction on a large - scale numerical control bending machine to form a bending die for the ribbed skin in the middle of the wall panel; use the bending die for the ribbed skin in the middle of the wall panel to perform sectional bending and forming on the ribbed skin area in the middle of the flat wall panel according to a preset path; S2. Bending of the thickened skin at both ends: Connect the intermediate pressing block to the upper die base by bolts to form an upper die sub - die, and at the same time reduce the span of the lower die; according to the length of the wall panel to be bent, splice multiple upper die sub - dies and lower die sub - dies along the length direction on a large - scale numerical control bending machine to form a bending die for the thickened skin at both ends of the wall panel; use the bending die for the thickened skin at both ends of the wall panel to perform sectional bending and forming on the thickened skin area at both ends of the flat wall panel according to a preset path; S3. Straightening of the insufficiently deformed area: According to the length of the insufficiently deformed area, adjust the number of upper die sub - dies in step S2 or S2 to adapt to the size of the insufficiently deformed area, and form a straightening die for the insufficiently deformed area with the lower die; perform secondary bending on the insufficiently deformed area to achieve deformation compensation; S4. Straightening of the over - deformed area: Connect the two side pressing blocks to the upper die base by bolts to form an upper die sub - die. According to the length of the over - deformed area, splice multiple upper die sub - dies and lower die sub - dies along the length direction on a large - scale numerical control bending machine; the upper die, the lower die, and the area of the wall panel to be straightened are in the same vertical plane; the upper die presses down to perform reverse straightening on the over - deformed area of the wall panel, and the wall panel does not need to be turned over during the straightening process.

2. The bending method of the combined bending die for forming the storage tank wall panel according to claim 1, characterized in that, According to the finite - element simulation results of bending and forming, intermediate pressing blocks and side pressing blocks with different curvatures and widths can be replaced to realize the change of the width and curvature of the upper and lower bending dies, and adapt to the precision bending and forming of wall panel components with different structures.

3. The bending method of the combined bending die for forming the storage tank wall panel according to claim 2, characterized in that In steps S3 and S4, for the insufficiently deformed or over - deformed areas caused by the difference in the wall panel structure during bending, by changing the structure and number of the upper die sub - dies, the upper die surface can be quickly and accurately adjusted, thereby realizing the deformation correction of the insufficiently deformed or over - bent area and achieving the precision forming of the wall panel.

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