Ultra-thin weak rigid box body assembly deformation control and welding method

Abstract

The application provides a kind of ultra-thin weak rigid box body on the assembly deformation control and welding method, comprising the following steps: S1, before the assembly of the cylinder section of the ultra-thin weak rigid box body, the cylinder section is fixed by using a horizontal shape-retaining tool to improve the rigidity of the product; S2, a fastening chain is installed on the welding side of the to-be-welded cylinder section to pre-tighten the periphery of the to-be-welded cylinder section; S3, an internal support tool is installed inside the to-be-welded cylinder section to support the contour of the to-be-welded cylinder section; S4, when the to-be-welded cylinder section is installed to the to-be-welded position, reciprocating retreat and installation are performed to make the fitting gap between the to-be-welded cylinder section and the to-be-welded position uniform; and S5, after uniform positioning by a welding device, welding is performed. The ultra-thin weak rigid box body assembly deformation control and welding method provided by the application proposes a 3.35m diameter ultra-thin common bottom storage tank assembly welding deformation control technical idea and method, and solves the welding seam quality problems such as welding misjoint caused by unstable assembly quality and assembly precision fluctuation of the thin-walled common bottom storage tank.

Description

Technical Field

[0001] This invention belongs to the field of rocket propellant tank manufacturing, and in particular relates to a deformation control and welding method during assembly on an ultra-weak rigid tank frame. Background Technology

[0002] For the assembly and welding of the hydrogen-oxygen final-stage common-bottom tank, the current manufacturing challenges are as follows: the tank body adopts a weakly rigid cylindrical section structure, which has a large diameter-to-thickness ratio and the lowest rib height compared to the existing products, making the assembly of the tank body circumferential seam and the control of welding deformation extremely difficult. At the same time, compared with conventional single-chamber structure tanks, the tank body assembly and welding process is more complex, and the control of the tank body's dimensional accuracy and stability is more difficult.

[0003] Specifically, this manifests as follows:

[0004] Challenge 1: To achieve weight reduction targets, the cylindrical sections of the housing have weak rigidity, making it difficult to control the precision of horizontal assembly.

[0005] The hydrogen-oxygen final stage cylinder has a diameter of 3350mm, a minimum skin thickness of 1.6mm, and a cylinder length of 2234mm. It is a typical weakly rigid structure. Compared with the existing 3000mm diameter common bottom tank, the diameter is larger and the thickness is thinner, which further increases the difficulty of assembly precision caused by deformation during horizontal assembly of the tank.

[0006] Challenge 2: The dual-chamber storage tank involves a secondary sealing and welding process, making the assembly and welding workflow complex.

[0007] Compared to traditional tank structures, dual-chamber tanks involve a combination of hydrogen and oxygen tanks. The assembly and welding of the tanks requires separate sealing welding of the hydrogen and oxygen tanks, making the overall assembly and welding process complex. The overall dimensional control during assembly is also more challenging.

[0008] Challenge 3: Thin weld thickness and stringent requirements for one-time weld quality formation.

[0009] The technical object has a welding thickness as thin as 4mm, and the diameter-to-thickness ratio is much larger than that of all existing tank structures. For aluminum alloy materials, the welding process of ultra-thin products has to overcome difficulties such as welding deformation and welding consistency control. In order to avoid the risk of product repair welding, the requirements for the one-time forming quality of the weld are more stringent.

[0010] Challenge 4: Controlling the dimensional accuracy of thin-part storage tank welding is extremely difficult.

[0011] During the welding process of large-diameter ultra-thin storage tank structural components, there is a high risk of exceeding the tolerance of product shape and position dimensions, such as welding misalignment and surface deformation. Welding misalignment will directly affect the load-bearing strength of the weld and reduce the reliability of the welded structure. Typical phenomena caused by surface deformation include tank skin dents and bulges, which not only affect the product appearance and installation benchmark of parts, but also have an adverse effect on the construction of insulation layer foaming.

[0012] For the assembly, welding, and dimensional control of common-bottom tanks, the current methods are as follows: During tank assembly and welding, a horizontal welding frame is used, employing a welding process from the front bottom to the rear bottom. The hydrogen tank is sealed at the common-bottom locking weld; the oxygen tank is sealed at the rear bottom and oxygen tank section weld. Traditional internal support and external pressure fixtures are used for support and deformation control during assembly and welding. For post-weld misalignment, manual correction is typically required. There is no completely effective method to control skin dents caused by surface deformation. Summary of the Invention

[0013] In view of this, the present invention aims to propose a deformation control method during assembly on an ultra-weak rigid tank frame, in order to solve the problem that the assembly process of existing common bottom tanks mainly relies on the rigidity of the equipment and human experience to control the accuracy of the assembly process. The accuracy of the assembly process of different batches of products is greatly affected by human factors, resulting in unstable quality. Fluctuations in assembly accuracy often cause fluctuations in welding quality.

[0014] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0015] A deformation control method during assembly on an ultra-weak rigid box frame, characterized by the following steps: S1, before assembling the cylindrical section of the ultra-weak rigid box frame, a horizontal conforming fixture is used to fix the cylindrical section to improve the product rigidity;

[0016] S2. Install fastening chains on the welding side of the section to be welded to pre-tighten the periphery of the section to be welded;

[0017] S3. Install internal support fixtures inside the section to be welded to support the outer contour of the section to be welded;

[0018] S4. When installing the section to be welded to the welding position, reciprocate the back-and-forth installation to ensure that the fit gap between the section to be welded and the welding position is uniform.

[0019] S5. Weld after uniform positioning using welding equipment.

[0020] Furthermore, in step S1, after the product is installed into the horizontal shaping fixture, it is necessary to ensure that the product and the horizontal shaping fixture rotate synchronously when the product is flipped.

[0021] Furthermore, the ultra-weak rigid housing includes a front short shell, a front bottom, a liquid hydrogen tank section, a rear bottom, a common bottom, and a rear short shell. One end of the outer edge of the front bottom is fixedly connected to the inner ring of the front short shell, and one end of the front short shell is fixedly connected to one end of the liquid hydrogen tank section. The other end of the liquid hydrogen tank section is fixedly connected to one end of the rear short shell. One end of the outer edge of the common bottom is fixedly connected to the inner ring of the rear short shell. The inner ring of the liquid hydrogen tank section is provided with the rear bottom, and there is a space between the rear bottom and the common bottom. The space is used to fill liquid oxygen, and the space between the front bottom and the rear bottom is used to fill liquid hydrogen.

[0022] Compared with existing technologies, the deformation control method for assembly on an ultra-weak rigid box frame described in this invention has the following beneficial effects: Before the cylindrical section is assembled on the frame, a horizontal conforming fixture is used to fix the cylindrical section, improving the product's rigidity. During flipping, the product is flipped with the conforming fixture, reducing the product's roundness deviation caused by free deformation during the flipping process; before welding, fastening chains are installed on the welding side of the cylindrical section to be welded, pre-tightening the cylindrical section's circumference by 6-8mm to ensure it is in a good elastic binding state; the welding inner support fixture is used to push the welding side of the cylindrical section into place, ensuring that the welding part is in a good rigid support state, and the assembly misalignment is well controlled; by appropriately retracting the bed tail box, the gap between the cylindrical sections is made uniform, avoiding excessive tightness in localized areas and excessive assembly stress; the automatic welding program provides uniform positioning, reducing the accumulation of misalignment caused by deformation during the formal welding process.

[0023] Another objective of this invention is to propose a refined welding method for the circumferential seam of ultra-weak rigid box bodies, in order to solve the problem that existing technologies lack welding reference processes for welding thicknesses below 4mm for 2219 aluminum alloy materials.

[0024] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0025] A method for refining the circumferential welds of an ultra-weak rigid tank, wherein the ultra-weak rigid tank is a φ3.35m hydrogen-oxygen final-stage common-bottom tank. The circumferential welds connecting the front short shell and the front bottom, the front short shell and the liquid hydrogen tank section, the common-bottom locking circumferential weld between the liquid hydrogen tank section and the rear short shell, the common-bottom weld and the rear short shell, and the rear bottom weld and the liquid hydrogen tank section are all 4mm circumferential welds. These 4mm circumferential welds employ a variable polarity TIC refining welding process, including...

[0026] A1. A small beam current positioning process is used for the connecting ring seam;

[0027] A2. Perform DC helium arc welding on the circumferential direction of the connecting ring seam for the root pass;

[0028] A3. Perform AC pulse argon arc capping welding on the connecting circumferential seam after the circumferential root weld is completed;

[0029] A4. The common-bottom lock-bottom circumferential weld adopts a high-current, filler wire helium-argon mixed AC pulse argon arc welding process.

[0030] Furthermore, the welding wire used for the connecting ring seam and the common bottom locking ring seam is φ1.6mm 2325 bright welding wire.

[0031] Compared with existing technologies, the refined welding method for ultra-weak rigid tank circumferential seams described in this invention has the following advantages: it proposes a refined welding process technology for thin-walled common-bottom tanks with variable polarity TIG welding, and fully realizes reliable parameter setting for circumferential seam welding technology of 4mm thick 2219 aluminum alloy common-bottom tanks, achieving near-defect-free welding of products.

[0032] Another objective of this invention is to propose a method for controlling the consistency of the dimensional alignment of ultra-weak rigid tank bodies. This addresses the problem that existing technologies for common-bottom tanks typically rely on post-weld correction and repair for deformations such as misalignment, skin depressions, and bulges, which are usually only addressed through post-weld straightening and repair, lacking online control methods.

[0033] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0034] A method for controlling the consistency of dimensional alignment in an ultra-weak rigid box, including...

[0035] Methods for controlling the roundness of the box body: The theoretical perimeter of the box body is preset, and the perimeter data of the welding end of the box body cylindrical section is quantitatively matched. The quantitative perimeter data is 2-4mm smaller than the theoretical value. During the assembly of the box body, the amount of support is controlled by the internal support tooling. The radial deformation of the cylindrical section and the welding angle deformation are offset by the preset radial deformation amount, so as to ensure the roundness of the box body after welding.

[0036] Methods for controlling the external dimensions of the box body: When a depression is generated during the welding process, a shallow process groove is opened in the corresponding circumferential seam to release stress. The depression is eliminated by secondary weld shrinkage and stress distribution readjustment at the groove. At the same time as the repair, an external force is applied to the depression of the body panel.

[0037] Compared with the prior art, the method for controlling the uniformity of the dimensions of an ultra-weak rigid box described in this invention has the following advantages: by controlling the elastic quantification of the box perimeter, the wall panel depression is eliminated by the secondary weld shrinkage and stress distribution readjustment at the slot, and external force is applied to the wall panel depression during the repair, thus achieving good control of the shape and dimensions of the product object. Attached Figure Description

[0038] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0039] Figure 1 This is a schematic cross-sectional view of the φ3.35m hydrogen-oxygen final stage common bottom tank according to an embodiment of the present invention;

[0040] Explanation of reference numerals in the attached figures:

[0041] 1-Front short shell; 2-Front bottom; 3-Liquid hydrogen tank section; 4-Rear bottom; 5-Common bottom; 6-Rear short shell. Detailed Implementation

[0042] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0043] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention 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, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0044] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0045] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0046] like Figure 1 As shown, the deformation control method and welding method are used when assembling on an ultra-weak rigid box frame:

[0047] S1. Before assembling the cylindrical section of the ultra-weak rigid box body, use a horizontal conforming tool to fix the cylindrical section to improve the rigidity of the product.

[0048] In step S1, after the product is installed into the horizontal conforming fixture, it is necessary to ensure that the product and the horizontal conforming fixture rotate synchronously during the flipping process to reduce the product roundness deviation caused by free deformation during the flipping process.

[0049] S2. Install fastening chains on the welding side of the section to be welded, and pre-tighten the perimeter of the section to be welded by 6-8mm in advance to ensure it is in a good elastic binding state.

[0050] S3. Install internal support fixtures inside the section to be welded to support the outer contour of the section to be welded, ensuring that the welding part is in a good rigid support state and that the assembly misalignment is well controlled.

[0051] S4. When installing the section to be welded to the welding position, reciprocate back and forth to ensure that the gap between the section to be welded and the welding position is uniform, thus avoiding excessive tightness in some areas and excessive assembly stress. The automatic welding program provides uniform positioning and reduces the accumulation of misalignments caused by deformation during the formal welding process. The automatic welding program is a built-in program of the existing welding machine.

[0052] The ultra-weak rigid enclosure includes a front short shell, a front bottom, a liquid hydrogen tank section, a rear bottom, a common bottom, and a rear short shell. One end of the outer edge of the front bottom is fixedly connected to the inner ring of the front short shell, and one end of the front short shell is fixedly connected to one end of the liquid hydrogen tank section. The other end of the liquid hydrogen tank section is fixedly connected to one end of the rear short shell. One end of the outer edge of the common bottom is fixedly connected to the inner ring of the rear short shell. The rear bottom is located within the inner ring of the liquid hydrogen tank section, and a space is provided between the rear bottom and the common bottom. The space is used to fill liquid oxygen, and the space between the front bottom and the rear bottom is used to fill liquid hydrogen.

[0053] A refined welding method for the circumferential seams of an ultra-weak rigid tank, specifically a φ3.35m hydrogen-oxygen final-stage common-bottom tank, was developed. The circumferential seams connecting the front short shell and the front bottom, the front short shell and the liquid hydrogen tank section, the common-bottom locking seam between the liquid hydrogen tank section and the rear short shell, the common-bottom seam and the rear short shell, and the rear bottom and the liquid hydrogen tank section are all 4mm seams. These 4mm seams are welded using a variable polarity TIC refined welding process.

[0054] A1. A small beam current positioning process is used for the connecting ring seam;

[0055] A2. Perform DC helium arc welding on the circumferential direction of the connecting ring seam for the root pass;

[0056] A3. Perform AC pulse argon arc capping welding on the connecting circumferential seam after the circumferential root weld is completed;

[0057] A4. The common-bottom lock-bottom circumferential weld adopts a high-current, filler wire helium-argon mixed AC pulse argon arc welding process.

[0058] The welding wire used for connecting the circumferential seam and the common-bottom lock seam is φ1.6mm 2325 bright welding wire.

[0059] The following is an example of how, in this embodiment, new welding technical parameters were developed and invented based on the existing 2A14 aluminum alloy common bottom tank material, using 2219 aluminum alloy material.

[0060] Table 1. Parameters for Butt Joint Welding of Tube Sections

[0061]

[0062] A method for controlling the consistency of dimensions of ultra-weak rigid box slabs, including: control of box slab roundness and control of box slab external surface dimensions.

[0063] Methods for controlling the roundness of the box body: The theoretical perimeter of the box body is preset, and the perimeter data of the welding end of the box body cylindrical section is quantitatively matched. The quantitative perimeter data is 2-4mm smaller than the theoretical value. During the assembly of the box body, the amount of support is controlled by the internal support tooling. The radial deformation of the cylindrical section and the welding angle deformation are offset by the preset radial deformation amount, so as to ensure the roundness of the box body after welding.

[0064] Methods for controlling the external dimensions of the box body: When a depression is generated during the welding process, a shallow process groove is opened in the corresponding circumferential seam to release stress. The depression is eliminated by secondary weld shrinkage and stress distribution readjustment at the groove. At the same time as the repair, an external force is applied to the depression of the body panel.

[0065] This embodiment has the following beneficial effects:

[0066] (1) A technical approach and method for controlling welding deformation during assembly of a 3.35m diameter ultrathin common-bottom tank were proposed, which solved the welding quality problems such as weld misalignment caused by unstable assembly quality and fluctuations in assembly accuracy of the thin-walled common-bottom tank.

[0067] (2) A refined welding process technology for thin-walled common-bottom tanks with variable polarity TIG was proposed, and technical parameters for circumferential welding of 4mm thick 2219 aluminum alloy common-bottom tanks were formulated and invented, achieving near-defect-free welding of products.

[0068] (3) An ultra-thin box body shape and size consistency control technology was proposed. The box body perimeter was elastically quantified and controlled. The wall panel depression was eliminated by secondary weld shrinkage and stress distribution readjustment at the slot. At the same time as the repair, external force was applied to the wall panel depression of the production line, thus achieving good control of the product object shape and size.

[0069] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for controlling the consistency of product dimensions after welding using a refined welding method for the circumferential seam of an ultra-weak rigid box, characterized in that: include: Methods for controlling the roundness of the box body: The theoretical perimeter of the box body is preset, and the perimeter data of the welding end of the box body cylindrical section is quantitatively matched. The quantitative perimeter data is 2-4mm smaller than the theoretical value. During the assembly of the box body, the amount of support is controlled by the internal support tooling. The radial deformation of the cylindrical section and the welding angle deformation are offset by the preset radial deformation amount, so as to ensure the roundness of the box body after welding. Methods for controlling the external dimensions of the box: When a depression is generated during the welding process, a shallow process groove is opened in the corresponding circumferential seam to release stress. The depression in the wall panel is eliminated by the secondary weld shrinkage and stress distribution readjustment at the groove. At the same time as the repair, an external force is applied to the depression in the box wall panel. The refined circumferential welding method implemented for the ultra-weak rigid tank, fixed according to the deformation control method during assembly on the ultra-weak rigid tank frame, is as follows: The ultra-weak rigid tank is a φ3.35m hydrogen-oxygen final stage common-bottom tank, with a diameter of 3350mm for the hydrogen-oxygen final stage cylinder section, a minimum skin thickness of 1.6mm, and a cylinder section length of 2234mm. The circumferential welds connecting the front short shell and the front bottom, the front short shell and the liquid hydrogen tank cylinder section, the common-bottom locking circumferential weld between the liquid hydrogen tank cylinder section and the rear short shell, the common-bottom weld between the common-bottom and the rear short shell, and the rear bottom weld between the liquid hydrogen tank cylinder section and the liquid hydrogen tank cylinder section are all 4mm circumferential welds. The 4mm circumferential welds employ a variable polarity TIG refined welding process, including... A1. A small beam current positioning process is used for the connecting ring seam; A2. Perform DC helium arc welding on the circumferential direction of the connecting ring seam for the root pass; A3. Perform AC pulse argon arc capping welding on the connecting circumferential seam after the circumferential root weld is completed; A4. The common-bottom lock-bottom circumferential weld adopts a high-current, filler wire helium-argon mixed AC pulse argon arc welding process. The welding wire used for connecting the circumferential seam and the common-bottom lock-bottom circumferential seam is φ1.6mm 2325 bright welding wire; The ultra-weak rigid box includes a front short shell, a front bottom, a liquid hydrogen tank section, a rear bottom, a common bottom, and a rear short shell. One end of the outer edge of the front bottom is fixedly connected to the inner ring of the front short shell, and one end of the front short shell is fixedly connected to one end of the liquid hydrogen tank section. The other end of the liquid hydrogen tank section is fixedly connected to one end of the rear short shell. One end of the outer edge of the common bottom is fixedly connected to the inner ring of the rear short shell. The inner ring of the liquid hydrogen tank section is provided with the rear bottom, and there is a space between the rear bottom and the common bottom. The space is used to fill liquid oxygen, and the space between the front bottom and the rear bottom is used to fill liquid hydrogen. The deformation control method during assembly on an ultra-weak rigid box frame includes the following steps: S1. Before assembling the cylindrical section of the ultra-weak rigid box body, use a horizontal conforming tool to fix the cylindrical section to improve the rigidity of the product. S2. Install fastening chains on the welding side of the section to be welded, and pre-tighten the perimeter of the section to be welded by 6-8mm in advance. S3. Install an internal support fixture inside the section to be welded to support the outer contour of the section to be welded, and use the welding internal support fixture to push the welding side of the section into place. S4. When installing the section to be welded to the welding position, reciprocate the back-and-forth installation to ensure that the fit gap between the section to be welded and the welding position is uniform. S5. Welding is performed after uniform positioning using welding equipment and automatic welding programs; In step S1, after the product is installed into the horizontal shaping fixture, it is necessary to ensure that the product and the horizontal shaping fixture rotate synchronously when the product is flipped.

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