A method for manufacturing medium to large-sized complex curved surface structural components made of double-layer stainless steel thick plates.

Abstract

This invention relates to a manufacturing method for a complex curved surface structure of a medium-to-large-sized double-layer stainless steel thick plate, comprising the following steps: forming an outer shell, an inner shell, stiffening plates, support columns, and a conical sleeve respectively; machining the inner shell, the four sides of the outer shell, welding bevels, and mounting holes for the support columns; machining the welding bevels of the stiffening plates, wherein the stiffening plates include outer stiffening plates near the outer side and T-shaped stiffening plates located inside; welding the T-shaped stiffening plates to the inner side of the inner shell; performing low-temperature annealing treatment on the welded inner shell and T-shaped stiffening plates; welding the conical sleeve to the inner shell, and then welding a shielding block to the conical sleeve; precision machining the bevels on the T-shaped stiffening plates where they are welded to the outer shell; riveting the outer shell and support columns, and spot welding for fixation; welding the outer shell and support columns, first using laser welding for the root pass, and then using TIG welding for the fill pass; vibration aging; grinding and polishing the inner and outer surfaces. This method improves welding efficiency, reduces welding deformation, and ensures overall surface accuracy.

Description

Technical Field

[0001] This invention belongs to the field of manufacturing processes, and in particular relates to a method for manufacturing complex curved surface structures of medium and large-sized double-layer stainless steel thick plates. Background Technology

[0002] In fields such as nuclear power and chemical equipment, there are numerous stainless steel double-walled irregularly curved containers. Due to their large size, these components require segmented fabrication. The resulting segmented double-walled stainless steel thick-plate complex curved surface structures have intricate shapes and require high weld quality and surface precision, making them highly challenging to manufacture.

[0003] Taking a nuclear fusion vacuum chamber as an example, the chamber is a double-layered, D-shaped cross-section annular spherical structure with supporting columns and shielding blocks welded to them in the middle. After segmented fabrication, each individual component is a complex curved surface structure made of double-layered thick stainless steel plates. This structure is an inner and outer double-layered complex curved surface structure, connected by stiffening plates and supporting columns. Shielding blocks are located in the middle and welded to the supporting columns. The inner and outer shells are generally made of 316 series stainless steel plates with a thickness of not less than 40mm. The surface accuracy of the complex curved surfaces is required to be within ±3mm, and the welds must achieve full penetration and meet the highest ISO5817 Class B standard.

[0004] For the ISO 5817 Class B standard weld quality requirements of this double-layer stainless steel thick plate complex curved surface structure, conventional MAG welding (gas-shielded arc welding) is insufficient to meet the weld quality requirements, resulting in a very high weld rework rate. While TIG welding (non-consumable electrode inert gas welding) offers high weld quality, it is extremely inefficient and causes significant welding deformation for plates 40mm thick and above. This is particularly true when welding the outer shell, where structural limitations necessitate single-sided welding with double-sided forming, further increasing the difficulty of controlling welding deformation. Achieving a surface accuracy of ±3mm for complex curved surface structures on the order of 10 meters is also extremely challenging.

[0005] Based on the above requirements for surface accuracy and weld quality, there is an urgent need for a manufacturing method for complex curved surface structures made of double-layer stainless steel thick plates to solve the above problems. Summary of the Invention

[0006] To overcome the shortcomings of the prior art, this invention provides a manufacturing process for medium and large-sized double-layer stainless steel thick plate complex curved surface structural parts, which solves the problem of controlling the surface accuracy of double-layer stainless steel thick plate complex curved surface structural parts after welding, and avoids the technical problems of low welding efficiency, excessive deformation, or difficulty in controlling the quality of single MAG welds on thick plates.

[0007] The technical solution of the present invention to solve the above-mentioned technical problems is as follows:

[0008] A method for manufacturing medium to large-sized double-layer stainless steel thick plate complex curved surface structural components includes the following steps:

[0009] Step 1: Form the outer shell, inner shell, stiffening plate, support column and conical sleeve respectively. The outer shell is cut and formed in sections, and the inner shell is integrally molded. The stiffening plate includes an outer stiffening plate near the outside and a T-shaped stiffening plate located inside.

[0010] Step 2: Machining the inner shell, the four sides of the outer shell, the welding bevels, the mounting holes for the support columns, and the welding bevels for the stiffening plates;

[0011] Step 3: Weld T-shaped stiffeners to the inner side of the inner shell;

[0012] Step 4: Perform low-temperature annealing on the welded inner shell and T-shaped stiffeners;

[0013] Step 5: Weld a conical sleeve onto the inner shell, and then weld a shielding block onto the conical sleeve;

[0014] Step 6: Perform precision machining on the bevel where the T-shaped stiffener is welded to the outer shell;

[0015] Step 7: Rivet the outer shell and support columns, and spot weld them in place;

[0016] Step 8: Weld the outer shell and support columns. First, use laser welding for the root pass, and then use TIG welding for the fill pass.

[0017] Step 9, vibration aging;

[0018] Step 10: Grind and polish the inner and outer surfaces.

[0019] Compared with the prior art, the technical solution of this application has the following beneficial technical effects:

[0020] The manufacturing method provided in this application solves the problems of full penetration of stiffener welds and welding and fixing of support column sequence and shielding block under spatial curved surface structure by segmenting the outer shell, using a conical sleeve structure and positioning the inner shell with special tooling. By using laser welding for the root pass and laser welding for the fill pass, and using laser welding for the root pass with less deformation, and a rigid body of a certain thickness, TIG welding is then performed, which improves welding efficiency, reduces welding deformation, and ensures the overall surface accuracy.

[0021] Based on the above solution, this application can be further optimized and improved as follows:

[0022] Preferably, in step 2, machining allowance is left at the welding bevel between the two sides of the T-shaped stiffener and the outer shell.

[0023] Preferably, in step 3, the inner shell is pre-fixed with rigid tooling, and then T-shaped stiffeners are welded.

[0024] Preferably, in step 4, the inner shell and the T-shaped stiffener are annealed at the temperature recommended by the RCC-MR standard, and the temperature is not higher than 425℃.

[0025] Preferably, in step 5, the axial direction of the support column is consistent with the normal direction of the corresponding contact area between the inner shell and the outer shell.

[0026] Preferably, in step 5, after the tapered sleeve is welded, 100% VT and PT tests are performed. After the tests are passed, the interlayer between the inner shell and the outer shell is cleaned, and then the shielding block is welded. After the shielding block is welded, the interlayer is cleaned again.

[0027] Preferably, in step 6, the beveling accuracy of the T-shaped stiffener is within 0.2mm.

[0028] Preferably, in step 7, the outer shell and the support column are riveted to ensure that the assembly gap between the outer shell and the T-shaped stiffener is within 0.5mm, the step difference is within 1mm, and the gap between the support column and the mounting hole is within 0.5mm.

[0029] Preferably, in step 8, laser welding is first used to perform the root pass welding, with a welding thickness of not less than 20mm.

[0030] Preferably, after filling with TIG welding, 100% VT, PT and PAUT tests are performed, and the weld quality requirements must meet the ISO5817 Class B standard. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the structure of a medium-to-large-sized double-layer stainless steel thick plate complex curved surface structure after fabrication, provided in an embodiment of the present invention.

[0032] Figure 2 for Figure 1 A structural diagram from another perspective;

[0033] Figure 3 A schematic diagram of the weld bevel structure for laser welding root pass and TIG filler. Detailed Implementation

[0034] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.

[0035] This application provides a method for manufacturing medium to large-sized double-layer stainless steel thick plate complex curved surface structural parts, which includes the following steps:

[0036] Step 1: Based on the part structure and the requirement for full weld penetration, the components of the complex curved surface structure of the medium and large-sized double-layer stainless steel thick plate are formed, namely, the outer shell 1, inner shell 2, stiffeners, support columns 5 and conical sleeves 7 are formed respectively. The outer shell 1 is cut and formed in sections to form multiple independent sheet structures. The inner shell 2 is integrally molded. The stiffeners include the outer stiffeners 3 near the outside and the T-shaped stiffeners 4 located inside.

[0037] Step 2: Machining the four sides of the inner shell 2 and the outer shell 1, welding bevels, support column mounting holes, and machining the welding bevels of the stiffening plates.

[0038] Among them, the welding bevels of the T-shaped stiffener 4 on both sides and the outer shell 1 are left with machining allowance to ensure the riveting accuracy of the remaining outer shell 1 through subsequent precision machining.

[0039] Step 3: Weld T-shaped stiffeners 4 onto the inner side of the inner shell 2. A schematic diagram of the structure of the T-shaped stiffeners 4 welded onto the inner side of the inner shell 2 is shown below. Figure 1 and 2 As shown.

[0040] The inner shell is pre-fixed with rigid fixtures. Specifically, anti-deformation fixtures are spot-welded to the inner side of the inner shell 2 for rigid fixation and to control welding deformation. After welding, 100% VT, PT and PAUT tests are performed, and the weld quality requirements meet the ISO5817 Class B standard.

[0041] VT stands for Visual Testing, a non-destructive testing method that uses the naked eye or auxiliary tools (such as magnifying glasses, microscopes, etc.) to observe the surface of a product to check for visible defects such as scratches, cracks, and deformation.

[0042] PT stands for Penetrant Testing, a non-destructive testing technique used to detect open defects on material surfaces, such as cracks and pores. It typically involves coating the material surface with a penetrant containing fluorescent or coloring agents, which then seeps into the open defects. Excess penetrant is then removed, and a developer is applied to reveal the penetrant within the defects, thus detecting them.

[0043] PAUT stands for Phased Array Ultrasonic Testing, an advanced ultrasonic testing technology that uses multiple ultrasonic transmitting and receiving elements to form and control the shape, direction, and focus of an ultrasonic beam, achieving more efficient testing.

[0044] ISO 5817 Class B standard specifies the quality requirements for molten metal welds in the welding of metallic materials. It is an international standard applicable to welding of metallic materials including steel, aluminum, titanium, and nickel alloys. ISO 5817 Class B weld inspection requirements stipulate that the weld should be free of defects in appearance, meet dimensional tolerances, be free of cracks, slag inclusions, and voids, have intermetallic inclusions that meet specifications, be free of internal defects, and have sufficient residual stress.

[0045] Step 4: Perform low-temperature annealing on the welded inner shell 2 and T-shaped stiffener 4. The temperature should be set in the range of 410±15℃ to eliminate some of the welding stress. It is preferable to perform annealing at the temperature recommended by the RCC-MR standard, with the temperature not exceeding 425℃. The RCC-MR standard provides design and construction rules for mechanical components used under high-temperature conditions and subject to significant creep, especially for the dimensional rules of thin shells.

[0046] Step 5: Weld the conical sleeve 7 onto the inner shell 2, and then weld the shielding block 6 onto the conical sleeve 7.

[0047] Specifically, a conical sleeve 7 is welded onto the inner shell 2 to fix the shielding block 6. The welding of the conical sleeve 7 is performed using specialized tooling for positioning, ensuring the positioning accuracy of the conical sleeve 7. After welding, the conical sleeve 7 undergoes 100% VT and PT testing. Once it passes the test, the interlayer is cleaned. Then, the shielding block 6 is welded onto the conical sleeve 7. After welding, the interlayer is cleaned again.

[0048] Among them, the axial direction of the support column on the complex curved surface is the normal direction of the curved surface. Due to structural limitations, the support column 5 needs to be welded last. The design of the cone sleeve 7 structure is used to weld the shielding block 6, and the design tooling is used for positioning.

[0049] Step 6: Perform precision machining on the bevel of the T-shaped stiffener 4 that is welded to the outer shell 1; wherein the machining accuracy of the bevel on the side of the T-shaped stiffener is within 0.2mm.

[0050] Step 7: Rivet the outer shell 1 and the support column 5, and spot weld them in place; specifically, rivet the outer shell 1 and the support column 5 to ensure that the assembly gap between the outer shell 1 and the T-shaped stiffener 4 is within 0.5mm and the step difference is within 1mm, and the gap between the support column 5 and the mounting hole is within 0.5mm, so as to ensure the requirements of the assembly gap and step difference for subsequent laser welding.

[0051] Step 8: Weld the outer shell 1 and support column 5. First, use laser welding for the root pass, then use TIG welding for the fill pass. After welding, perform 100% VT, PT, and PAUT tests. The weld quality must meet ISO5817 Class B standards. The weld bevel of the laser-welded root pass + TIG fill pass is V-shaped with an included angle of approximately 55°. Figure 3 As shown.

[0052] Step 9, Vibration Aging; Vibration aging (VSR) is a technique used to reduce and adjust residual stress within materials. It involves controlling the excitation frequency of the vibrator to induce resonance in the workpiece, generating appropriate alternating motion and absorbing some energy. This leads to microscopic viscoelastic-plastic mechanical changes within the workpiece, thereby reducing local peak stress and homogenizing the residual stress field, especially in stress concentration areas on the surface.

[0053] Step 10: Grind and polish the inner and outer surfaces.

[0054] The stiffening plates inside the interlayer between the inner shell 2 and the outer shell 1 are designed as T-shaped stiffening plates for butt welding with the outer shell, while the stiffening plates near the four sides can be welded from one side through the interlayer gap.

[0055] The structural diagram of the medium-to-large-sized double-layer stainless steel thick plate complex curved surface structural component manufactured according to this application is as follows: Figure 1 As shown.

[0056] The above manufacturing method solves the problems of full penetration of stiffener welds and welding fixation of support column sequence and shielding block under spatial curved surface structure by segmenting the outer shell 1, using the conical sleeve 7 structure and positioning the inner shell 2 with special tooling. By using laser welding for the root pass and laser welding for the fill pass, and using laser welding for the root pass with small deformation, and a rigid body of a certain thickness, TIG welding is then performed, which not only improves welding efficiency but also reduces welding deformation and ensures the overall surface accuracy.

[0057] 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 manufacturing method of a medium-large size double-layer stainless steel thick plate complex curved surface structural member, characterized by, Includes the following steps: Step 1: Form the outer shell, inner shell, stiffening plate, support column and conical sleeve respectively. The outer shell is cut and formed in sections, and the inner shell is integrally molded. The stiffening plate includes an outer stiffening plate near the outside and a T-shaped stiffening plate located inside. Step 2: Machining the inner shell, the four sides of the outer shell, the welding bevel, the mounting holes of the support column, and machining the welding bevel of the stiffening plate, wherein the stiffening plate includes an outer stiffening plate near the outside and a T-shaped stiffening plate located inside. Step 3: Weld T-shaped stiffeners to the inner side of the inner shell; Step 4: Perform low-temperature annealing on the welded inner shell and T-shaped stiffeners; Step 5: Weld a conical sleeve onto the inner shell, and then weld a shielding block onto the conical sleeve; Step 6: Perform precision machining on the bevel where the T-shaped stiffener is welded to the outer shell; Step 7: Rivet the outer shell and support columns, and spot weld them in place; Step 8: Weld the outer shell and support columns. First, use laser welding for the root pass, and then use TIG welding for the fill pass. Step 9, vibration aging; Step 10: Grind and polish the inner and outer surfaces.

2. The manufacturing method of medium-to-large-sized double-layer stainless steel thick plate complex curved surface structural parts according to claim 1, characterized in that, In step 2, machining allowance is left for the welding bevels between the two sides of the T-shaped stiffener and the outer shell.

3. The manufacturing method of medium-to-large-sized double-layer stainless steel thick plate complex curved surface structural parts according to claim 1, characterized in that, In step 3, the inner shell is pre-fixed with rigid tooling, and then T-shaped stiffeners are welded on.

4. The manufacturing method of the medium-to-large-sized double-layer stainless steel thick plate complex curved surface structural component according to claim 1, characterized in that, In step 4, the inner shell and T-shaped stiffeners are annealed at the temperature recommended by the RCC-MR standard, not exceeding 425℃.

5. The manufacturing method of medium-to-large-sized double-layer stainless steel thick plate complex curved surface structural parts according to claim 1, characterized in that, In step 5, the axial direction of the support column is consistent with the normal direction of the corresponding contact area between the inner shell and the outer shell.

6. The manufacturing method of medium-to-large-sized double-layer stainless steel thick plate complex curved surface structural parts according to claim 1, characterized in that, In step 5, after the tapered sleeve is welded, 100% VT and PT tests are performed. After passing the tests, the interlayer between the inner shell and the outer shell is cleaned, and then the shielding block is welded. After the shielding block is welded, the interlayer is cleaned again.

7. The manufacturing method of medium-to-large-sized double-layer stainless steel thick plate complex curved surface structural parts according to claim 1, characterized in that, In step 6, the beveling accuracy of the T-shaped stiffener is within 0.2mm.

8. The manufacturing method of medium-to-large-sized double-layer stainless steel thick plate complex curved surface structural parts according to claim 1, characterized in that, In step 7, the outer shell and the support column are riveted together to ensure that the assembly gap between the outer shell and the T-shaped stiffener is within 0.5mm, the step difference is within 1mm, and the gap between the support column and the mounting hole is within 0.5mm.

9. The manufacturing method of medium-to-large-sized double-layer stainless steel thick plate complex curved surface structural parts according to claim 1, characterized in that, In step 8, laser welding is used to perform the root pass welding, with a welding thickness of not less than 20mm.

10. The manufacturing method of medium-to-large-sized double-layer stainless steel thick plate complex curved surface structural parts according to claim 9, characterized in that, After filling with TIG welding, 100% VT, PT and PAUT tests are performed, and the weld quality requirements must meet ISO5817 Class B standards.

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