Vacuum chamber shell sector forming and welding process

Abstract

This invention relates to the field of vacuum chamber shell fabrication technology, specifically a forming and welding process for sector-shaped segments of a vacuum chamber shell. Before mass production of the sector-shaped segments, test pieces are pre-treated according to the process steps to determine the range of magnetic permeability variation throughout the entire process. The forming and welding process steps are as follows: splice design; mold preparation; material cutting: laser cutting of raw materials according to the forming requirements of the sector-shaped segments, with a forming allowance reserved, and recording the magnetic permeability before and after cutting; cold pressing: placing the cut plates on the mold for pressing; beveling: cutting the forming allowance of the pressed splice plates using plasma cutting; welding assembly. This process, when used for the fabrication of sector-shaped segments of vacuum chamber shells, effectively avoids problems such as excessive material stress and uneven deformation during the overall forming process, and maintains a low magnetic permeability throughout the entire forming process.

Description

Technical Field

[0001] This invention relates to the field of vacuum chamber shell manufacturing technology, and in particular to a process for forming and welding sector-shaped segments of a vacuum chamber shell. Background Technology

[0002] As one of the world's largest, most technologically complex, and most integrated international large-scale scientific projects, the International Thermonuclear Experimental Reactor (ITER) carries the important mission of verifying the scientific and engineering feasibility of the peaceful use of fusion energy. In this fusion device system, the vacuum chamber is at the core. It not only needs to provide a stable ultra-high vacuum operating environment for the extremely high temperature plasma, but also undertakes the functions of supporting and precisely aligning the internal components, and forms the first nuclear radiation shielding barrier for the nuclear fusion reaction. This places extremely stringent requirements on material properties, structural precision, and manufacturing reliability. For example, existing published documents CN107020439B - A method for forming a ring of a sector segment in a large double-layer thin-walled D-section vacuum chamber and CN107020474B - A tooling and process method for forming an integral ring of a large double-layer thin-walled D-section vacuum chamber both disclose a forming process for a sector segment. Although the existing process can achieve the forming of the sector segment, it still has the following shortcomings in actual use. The manufacturing process of the sector segment of the vacuum chamber shell involves several key technologies, including large-scale complex curved surface forming, high-precision welding and assembly, and low magnetic permeability control throughout the entire process. It is extremely difficult to manufacture and has long been one of the key bottlenecks restricting the construction cycle and cost of the main fusion equipment. When preparing the sector segment using existing processes, a one-piece molding process is generally adopted, which is prone to problems such as excessive material stress and uneven deformation. This results in a low pass rate of finished products and unsatisfactory overall quality. Moreover, because magnetic permeability has a significant impact on the use of the vacuum shell, and processing methods such as cutting and welding can change the magnetic permeability of the sheet metal, it will affect the performance of the vacuum shell after it is formed. Therefore, it is necessary to improve the existing technology to solve the above-mentioned technical problems. Summary of the Invention

[0003] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0004] In view of the problems of low quality and high magnetic permeability of the existing vacuum chamber shell sector segment after forming, a new process for forming and welding the sector segment of the vacuum chamber shell is proposed.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a forming and welding process for a sector segment of a vacuum chamber shell, wherein the test piece is pre-treated according to the process steps before the mass production of the sector segment, so as to determine the range of change of magnetic permeability of the sector segment in the entire process. The forming and welding process steps are as follows: Splice design: Model the fan-shaped segments and complete the modeling of the vacuum chamber shell by splicing multiple fan-shaped segments. After modeling, simulate the forming process using finite element analysis; Mold preparation: Simulate the working conditions before mold preparation using finite element analysis, and prepare the mold using at least CNC machining and laser forming methods; Material cutting: Laser cut the raw materials according to the forming requirements of the fan-shaped segments, recording the magnetic permeability before and after cutting; Cold pressing: Place the cut plates on the mold for pressing and forming; Beveling: Cut the forming allowance of the pressed splice plates using plasma cutting and create a butt bevel; Welding assembly: Weld the splice plates into fan-shaped segments.

[0006] As a preferred embodiment of the forming and welding process of the sector segment of the vacuum chamber shell of the present invention, the plates used for forming the sector segment and the test piece are both made of S31603 stainless steel, and the plates should be placed away from carbon steel and / or magnetic environments before use.

[0007] As a preferred embodiment of the forming and welding process of the sector segment of the vacuum chamber shell of the present invention, the test piece is scaled down proportionally during the blanking step.

[0008] As a preferred embodiment of the forming and welding process of the sector segment of the vacuum chamber shell of the present invention, the finite element analysis parameters in the splicing part design step include at least the deformation path, material flowability, stress concentration area, forming defects, stamping speed, stamping pressure and friction coefficient during the cold forming process.

[0009] As a preferred embodiment of the forming and welding process of the sector segment of the vacuum chamber shell of the present invention, the finite element analysis parameters in the mold preparation step include at least the material, thickness and forming temperature.

[0010] As a preferred embodiment of the forming and welding process of the sector segment of the vacuum chamber shell of the present invention, in the cold pressing forming step, when an increase in magnetic permeability is detected, a solution treatment should be used to reduce the magnetic permeability of the material.

[0011] As a preferred embodiment of the forming and welding process of the sector segment of the vacuum chamber shell of the present invention, in the beveling step, the deformed part of the splicing plate is trimmed and the forming allowance is manually removed.

[0012] As a preferred embodiment of the forming and welding process of the sector segment of the vacuum chamber shell according to the present invention, the welding of the test piece is also used to provide a basis for adjusting the welding materials and welding parameters for the welding of the sector segment.

[0013] As a preferred embodiment of the forming and welding process of the sector segment of the vacuum chamber shell according to the present invention, the parameter changes of the sector segment during the welding process should be monitored in real time by an online detection system.

[0014] The present invention has the following beneficial effects: 1. When this process is used to prepare the sector segment of the vacuum chamber shell, the test piece is first pre-treated according to the process flow. With the help of finite element analysis, stress concentration and forming defects during the preparation of the sector segment can be effectively analyzed and reduced. In addition, the forming of the sector segment itself and the forming of the vacuum chamber shell as a whole adopt segmented welding, which can effectively avoid problems such as excessive material stress and uneven deformation during the overall forming process. The overall practicality is good and the quality is effectively improved.

[0015] 2. When this process is used to prepare the sector segment of the vacuum chamber shell, the test piece is first pretreated according to the process flow. This allows for effective monitoring and analysis of the permeability change throughout the forming process, thereby reducing the permeability change of the sector segment during preparation and ensuring that the vacuum chamber shell maintains a low permeability during forming. At the same time, the test piece is welded before the sector segment is welded, which allows for adjustment of the welding materials and parameters, reducing the cost of subsequent sector segment welding. Overall, this process is highly practical. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein: Figure 1 This is a simulation diagram before mold preparation in this invention.

[0017] Figure 2 This is a schematic diagram of the overall structure of the test piece in this invention.

[0018] Figure 3 This is a schematic diagram of the overall structure of the sector segment in this invention.

[0019] Figure 4 This is a diagram of the sector segment to be welded in this invention.

[0020] Figure 5 This is a welding indicator diagram of the test piece in this invention. Detailed Implementation

[0021] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0022] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0023] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0024] Secondly, the present invention is described in detail with reference to the schematic diagrams. When detailing the embodiments of the present invention, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged, not according to the usual scale. Furthermore, the schematic diagrams are merely examples and should not limit the scope of protection of the present invention. In addition, actual fabrication should include three-dimensional spatial dimensions of length, width, and depth. Example 1

[0025] This invention relates to a forming and welding process for a sector-shaped segment of a vacuum chamber shell. Before mass production of the sector-shaped segment, the test piece is pre-treated according to the process steps to determine the range of magnetic permeability variation of the sector-shaped segment throughout the entire process. The plates used for forming the sector-shaped segment and the test piece are both made of S31603 stainless steel, and the plates should be placed away from carbon steel and / or magnetic environments (especially strong magnetic environments) before use to avoid affecting the magnetic permeability of the plates. The magnetic permeability of the vacuum chamber shell should be ≤1.05. The magnitude of the magnetic permeability of the test piece during the entire preparation process is not required; only the change in magnetic permeability during the process steps is detected and recorded.

[0026] The forming and welding process steps are as follows; Splice design: Modeling of sector segments is performed, and the vacuum chamber shell is modeled by splicing multiple sector segments. After modeling, finite element analysis is used to simulate the forming process. The finite element analysis parameters in the splice design step include at least the deformation path, material flowability, stress concentration zone, forming defects, stamping speed, stamping pressure, and friction coefficient during the cold forming process. The focus is on analyzing stress and strain behaviors to avoid forming defects such as springback and cracking, thereby improving the accuracy and performance of the shell and finally obtaining optimized forming process parameters. After the simulation is completed, a scaled-down verification experiment is conducted. Based on the experimental results, the mathematical model and process parameters are improved to prepare for the preparation of test pieces.

[0027] Mold fabrication: Finite element analysis is used to simulate the working conditions before mold fabrication, with parameters including at least material, thickness, and molding temperature, to find the optimal solution that can significantly reduce material waste and trial-and-error costs, and improve the reliability and accuracy of the entire molding process, as shown in the attached figure. Figure 1 As shown, the molds are prepared by at least CNC machining and laser forming to ensure the shape accuracy and surface finish of the molds. The high precision of the molds not only improves the quality of the splicing plates, but also significantly extends the service life of the molds and reduces the downtime for maintenance caused by mold wear during production, thereby improving production efficiency. To better understand the effectiveness of mold working condition simulation, the following specific set of simulation data is provided. For items 3 and 4: For the same mold size and the same holding time, different pressing temperatures have little effect on the curvature of the final workpiece. For items 2 and 3: For the same mold size and the same pressing temperature, different holding times have little effect on the curvature of the final workpiece. Serial numbers 1 and 4: For the same pressing temperature and the same holding time, different mold sizes have a great impact on the curvature of the final workpiece; Through simulation, the optimal set of data is summarized to guide the parameters such as mold profile and center of gravity distribution, thereby improving the accuracy of the mold and guiding mold manufacturing.

[0028] Material cutting: The raw material is laser-cut according to the forming requirements of the fan-shaped segment. During the cutting of the test piece, the area where the magnetic permeability increases is about 1 mm from the cut. The change range of magnetic permeability is small, so a corresponding forming allowance is reserved. The magnetic permeability, thickness, and size are recorded before and after cutting. The test piece in this step should be scaled down proportionally.

[0029] Cold pressing: The cut sheet is placed on the mold and pressed into shape. Before pressing, kraft paper is placed between the mold and the sheet to avoid abnormal increase in magnetic permeability due to mold contact contamination. In the cold pressing step, when an increase in magnetic permeability is detected, solution treatment (solution heat treatment process) should be used to reduce the magnetic permeability of the material.

[0030] Beveling: The formed splicing plate is cut off by plasma cutting to remove the forming allowance and create a butt bevel. In the beveling step, although plasma cutting is highly efficient, it can easily cause an increase in magnetic permeability (the area of ​​increased magnetic permeability is the area with a cut ≥60mm, and the range of change in magnetic permeability is relatively small). Therefore, after comprehensively considering factors such as cost and construction period, most of the forming allowance is first removed by plasma cutting, and then the deformed part of the splicing plate is trimmed and the forming allowance is manually removed. This improves efficiency while ensuring magnetic permeability and petal accuracy.

[0031] Welding and Assembly: The splicing plates are welded into sector-shaped segments. The entire vacuum chamber shell is composed of eight sector-shaped segments welded in a circumferential array. The test piece and the sector-shaped segments are both welded from nine splicing plates, as shown in the attached diagram. Figure 2-4 As shown, multi-panel welding can effectively avoid problems such as excessive material stress and uneven deformation during the overall forming process. By forming step by step, the material flow path can be better controlled, reducing stress concentration and deformation defects during processing. In addition, multi-panel welding can also achieve high dimensional accuracy by precisely controlling the processing path, thereby improving the overall forming quality of the vacuum chamber shell. Example 2

[0032] This embodiment is the second embodiment of the present invention. This embodiment is based on the previous embodiment. The difference is that the welding of the test piece is also used to provide a basis for adjusting the welding materials and welding parameters for the welding of the sector segment. This can effectively reduce the cost of welding the sector segment and improve production efficiency.

[0033] Specifically, the test piece consisted of 9 pieces, and the weld numbers and locations are as follows: Figure 5 As shown, the transverse seams at positions 1#, 2#, 3#, 4#, 5#, and 6# between ①, ②, ③, and ④ are all process test welds. Magnetic permeability testing is required before, during, and after welding. The longitudinal seams between the four ③-pieces and the two ④-pieces are all fixed by intermittent welding (full welding is used when manufacturing the fan-shaped section). The length of each weld is not less than 100mm, the thickness is not less than 20mm, and the intermittent length is not greater than 250mm.

[0034] In addition, during the welding process, the parameter changes of the test piece or / and the sector segment should be monitored in real time through an online detection system. By comparing the data monitoring results with the simulation results, it was found that the difference between the two is very small. The simulation result error is -2 to +2 mm, while the actual measurement error is 0 to +2.3 mm. The comparison results show that the simulation has great guiding significance for the forming process in terms of parameters such as stress, strain, thinning, and springback.

[0035] Additionally, it should be noted that components not described in detail in this article are existing technologies.

[0036] It is important to note that the constructions and arrangements of this application shown in several different exemplary embodiments are merely illustrative. Although only a few embodiments are described in detail in this disclosure, those who consult this disclosure will readily understand that many modifications are possible (e.g., variations in the size, dimensions, structure, shape, and proportions of various elements, as well as parameter values ​​(e.g., temperature, pressure, etc.), mounting arrangements, the use of materials, colors, orientations, etc.) without substantially departing from the novel teachings and advantages of the subject matter described in this application. For example, an element shown as integrally formed may be composed of multiple parts or elements, the position of elements may be inverted or otherwise altered, and the nature or number or position of discrete elements may be changed or altered. Other substitutions, modifications, alterations, and omissions may be made in the design, operation, and arrangement of the exemplary embodiments without departing from the scope of the invention. Therefore, the invention is not limited to the particular embodiments but extends to a variety of modifications that still fall within the scope of the appended claims.

[0037] Furthermore, in order to provide a concise description of exemplary embodiments, not all features of actual embodiments (i.e., those features that are not relevant to the currently considered best mode for carrying out the invention, or those features that are not relevant to implementing the invention) may be omitted.

[0038] It should be understood that numerous specific implementation decisions can be made during the development of any practical implementation, such as in any engineering or design project. Such development efforts may be complex and time-consuming, but for those skilled in the art who benefit from this disclosure, the development effort will be a routine work of design, manufacturing, and production without requiring much experimentation.

[0039] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A process for forming and welding a sector-shaped segment of a vacuum chamber shell, characterized in that: Before mass production of the sector segment, the test pieces are pre-treated according to the process steps to determine the range of change in magnetic permeability of the sector segment throughout the entire process. The forming and welding process steps are as follows; Assembly component design: Modeling of sector segments is carried out, and the vacuum chamber shell is modeled by splicing multiple sector segments. After the modeling is completed, finite element analysis is used to simulate the forming process. Mold preparation: The working conditions are simulated by finite element analysis before mold preparation, and the mold is prepared by at least CNC machining and laser forming. Material cutting: The raw material is laser-cut according to the forming requirements of the fan-shaped segment, and a forming allowance is reserved. The magnetic permeability is recorded before and after cutting. Cold pressing: The cut sheet is placed on a mold and pressed into shape; Beveling: The forming allowance of the pressed splicing plate is cut off by plasma cutting to create a butt bevel; Welding assembly: Weld the splicing plates into fan-shaped segments.

2. The forming and welding process for the sector-shaped segment of a vacuum chamber shell as described in claim 1, characterized in that: The plates used for forming the sector segment and the test piece are all made of S31603 stainless steel, and the plates should be placed away from carbon steel and / or magnetic environments before use.

3. The forming and welding process for the sector-shaped segment of a vacuum chamber shell as described in claim 2, characterized in that: The test specimens were scaled down proportionally during the blanking process.

4. The forming and welding process for the sector-shaped segment of a vacuum chamber shell as described in claim 3, characterized in that: The finite element analysis parameters in the splicing component design process should include at least the deformation path, material flowability, stress concentration zone, forming defects, stamping speed, stamping pressure, and friction coefficient during the cold forming process.

5. The forming and welding process for the sector-shaped segment of a vacuum chamber shell as described in claim 4, characterized in that: The finite element analysis parameters in the mold preparation process include at least the material, thickness, and molding temperature.

6. The forming and welding process for a sector-shaped segment of a vacuum chamber shell as described in claim 4 or 5, characterized in that: In the cold pressing process, when an increase in magnetic permeability is detected, solution treatment should be used to reduce the material's magnetic permeability.

7. The forming and welding process for a sector-shaped section of a vacuum chamber shell as described in claim 6, characterized in that: In the beveling process, the deformed parts of the spliced ​​plate are trimmed and the forming allowance is manually removed.

8. The forming and welding process for the sector-shaped segment of a vacuum chamber shell as described in claim 7, characterized in that: The welding of the test pieces also serves as a basis for adjusting welding materials and welding parameters for the welding of the sector segments.

9. The forming and welding process for a sector-shaped segment of a vacuum chamber shell as described in claim 8, characterized in that: During the welding process, the parameter changes of the sector segment during the welding process should be monitored in real time using an online detection system.

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