Nuclear power plant anti-vibration branch pipe and processing method thereof

Abstract

The present invention discloses a vibration-resistant branch pipe for a nuclear power plant and a processing method thereof. The vibration-resistant branch pipe for a nuclear power plant includes a branch pipe body and a pipe seat integrally formed with the branch pipe body. The processing method of the vibration-resistant branch pipe for a nuclear power plant is simple in design, convenient for batch implementation, and has a wide range of applications. This optimized design and processing method can be used to process vibration-resistant branch pipes of nuclear power plants of different specifications. Since the vibration-resistant branch pipe for a nuclear power plant adopts an integrally formed design, butt welds are eliminated, and the power reduction or shutdown of the unit caused by vibration fatigue fracture of the welds is completely solved, greatly reducing the risk of fatigue fracture of the branch pipe due to vibration. The integrally formed design avoids welding connections, simplifies the on-site installation process, improves installation efficiency, reduces the number of welding joints, and reduces maintenance and overhaul costs. Therefore, the present invention has significant advantages in improving the vibration fatigue safety of nuclear power plant branches and improving the reliability and economy of power plant operation.

Description

Technical Field

[0001] The present invention relates to the field of nuclear power plant safety, and in particular to an anti-vibration branch pipe of a nuclear power plant and a processing method thereof. Background Art

[0002] Nuclear power plants use a large number of small branch pipes (outer diameter less than 50mm) for pressure measurement, flow measurement, draining, or exhaust. These small branch pipes are typically connected to the main pipe using a nozzle socket, which is welded to the main pipe at one end and to the branch pipe at the other, forming a "main pipe-weld-pipe socket-weld-branch pipe" structure. When the main pipe vibrates, the branch pipes are stimulated by the main pipe and vibrate accordingly. Because the nozzle socket has a much larger outer diameter and wall thickness than the branch pipe, its structural strength is high and it is not prone to cracking and failure. The connecting weld between the nozzle socket and the branch pipe is often where vibration stress is greatest, and the transition between the connection is often a right-angle transition, resulting in high local stress concentration. This makes it a weak area in the entire pipe. If fatigue cracking occurs, it can cause the piping system to malfunction and even cause unit shutdown.

[0003] To address this issue, existing technologies mainly involve adding integrated brackets to small branch pipes to limit their displacement and performing non-destructive testing on welds during overhauls. However, there are the following problems: (1) When the main pipe has a large displacement, excessively high average stress will be formed at the weld between the pipe seat and the branch pipe, reducing the fatigue resistance of the branch pipe; (2) When the main pipe vibrates at high frequency, the high-frequency vibration is transmitted to the branch pipe through the additional bracket, turning the original single-point excitation into multi-point excitation, and the vibration response is actually worsened; (3) Non-destructive testing of welds during overhauls requires a lot of service cooperation work, such as building scaffolding and removing insulation, which has high economic costs.

[0004] In the prior art, the design of branch pipe seats is often based on experience or simple mechanical calculations, which cannot ensure the optimal performance of the structure. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a vibration-resistant branch pipe for a nuclear power plant and a processing method thereof.

[0006] The technical solution adopted by the present invention to solve the technical problem is: a method for processing a vibration-resistant branch pipe of a nuclear power plant, wherein the vibration-resistant branch pipe of the nuclear power plant includes a branch pipe body and a pipe seat integrally formed with the branch pipe body, and the method comprises the following steps:

[0007] S1: Determine the interface dimensions between the pipe seat and the mother pipe, as well as the outer diameter, wall thickness, and length parameters of the branch pipe body, use a topology optimization method to achieve a smooth transition between the pipe seat and the branch pipe body, obtain the optimal structure of the pipe seat, and draw a processing diagram for the anti-vibration branch pipe of the nuclear power plant;

[0008] S2: heat treating the workpiece for manufacturing the anti-vibration branch pipe of the nuclear power plant;

[0009] S3: performing deep hole drilling on the workpiece after heat treatment;

[0010] S4: performing rough machining on the workpiece after deep hole drilling using a CNC lathe;

[0011] S5: removing residual stress from the workpiece after rough machining;

[0012] S6: using a CNC lathe to perform finish machining on the workpiece after residual stress removal;

[0013] S7: Performing quality control and inspection on the workpiece after processing.

[0014] In some embodiments, the topology optimization method includes:

[0015] S11: Based on the interface dimensions between the pipe socket and the main pipe, as well as the outer diameter, wall thickness, and length parameters of the branch pipe body, a finite element model is established. Constraints on the size of the pipe socket are set, and material structural parameters are defined. The material structural parameters include elastic modulus, Poisson's ratio, structural damping, and material density.

[0016] S12: setting a preset bending moment load, performing static calculation and modal calculation of the initial model of the pipe socket under the preset bending moment load, and obtaining the structural strength, stress, and first-order modal characteristics of the initial model of the pipe socket under the preset bending moment load;

[0017] S13: Topological optimization of the initial model of the pipe socket is performed using the variable density method. A preset material retention rate is set to obtain an optimized pipe socket model with maximum structural strength, minimum stress, and highest first-order modal frequency under a preset bending moment load.

[0018] S14: According to the structural performance and production process requirements of the tube socket, the optimization model is geometrically optimized, and the optimization model is fitted and optimized using the spline curve method to obtain the optimal model of the tube socket.

[0019] In some embodiments, in step S2, the workpiece is a forging, the forging is made of stainless steel, and the heat treatment temperature is 1040°C to 1065°C.

[0020] In some embodiments, step S3 includes:

[0021] S31: Fixing the heat-treated workpiece on a workbench of a drilling machine and clamping it with a fixture;

[0022] S32: setting a suitable rotation speed, feed rate and cutting depth according to the workpiece material and the type of drill bit;

[0023] S33: Start the drilling machine and start deep hole drilling;

[0024] S34: perform chip removal;

[0025] S35: After drilling is completed, use measuring tools to measure and inspect the machined holes of the anti-vibration branch pipes of the nuclear power plant to ensure that their size and position accuracy meet the requirements;

[0026] S36: Cleaning the coolant and chips on the surface of the workpiece.

[0027] In some embodiments, step S4 includes:

[0028] S41: Mounting the workpiece on a CNC lathe, ensuring that the workpiece is stable and correctly aligned;

[0029] S42: selecting a suitable first tool according to the material of the workpiece and the requirements of rough machining;

[0030] S43: setting a feed path of the first tool and cutting parameters of the workpiece in a programming system of a CNC lathe;

[0031] S44: adjusting a suitable cutting speed and feed rate according to the material of the workpiece and the performance of the first tool;

[0032] S45: Start the CNC lathe to perform rough processing;

[0033] S46: After the rough machining is completed, check whether there is any residual oxide layer, rust or scratches on the surface of the workpiece. If the rough machining requirements are not met, perform rough machining again;

[0034] S47: Cleaning iron filings and oil stains on the surface of the workpiece.

[0035] In some embodiments, in step S5 , the heat treatment temperature for removing residual stress of the workpiece after rough machining is 300° C. to 350° C.

[0036] In some embodiments, step S6 includes:

[0037] S61: Mounting the workpiece on a CNC lathe;

[0038] S62: Select the appropriate second tool and grinding wheel according to the processing requirements;

[0039] S63: Setting a feed path of the second tool and cutting parameters of the workpiece in a programming system of the CNC lathe;

[0040] S64: adjusting a suitable cutting speed and feed rate according to the material of the workpiece and the performance of the second tool;

[0041] S65: Start the CNC lathe for finishing;

[0042] S66: After finishing, the workpiece is measured and inspected using a measuring tool to ensure that its size and shape accuracy meet the requirements. If the finishing requirements are not met, further finishing is performed.

[0043] S67: cleaning the grinding fluid and iron chips on the surface of the workpiece and performing rust prevention treatment.

[0044] In some embodiments, step S7 includes:

[0045] S71: Dimension and shape accuracy inspection: Use measuring tools such as outside micrometers and roundness gauges to inspect the dimension and shape accuracy of the finished workpiece to ensure that it meets the design requirements;

[0046] S72: Surface quality inspection, observe whether there are scratches, cracks, rust and other defects on the surface of the workpiece, and take corresponding measures;

[0047] S73: Handling of unqualified products. Products that fail the inspection will be scrapped to ensure that all processed nuclear power plant anti-vibration branches meet the quality standards.

[0048] In this embodiment, a vibration-resistant branch pipe for a nuclear power plant is constructed, which includes a branch pipe body and a pipe seat integrally formed with the branch pipe body, and a smooth transition between the branch pipe body and the pipe seat.

[0049] In some embodiments, the branch tube body has a diameter of 14 mm to 27 mm, a wall thickness of 2 mm to 4 mm, and a length of 100 mm to 1200 mm;

[0050] The length of the tube seat is 70mm to 80mm, the inner diameter is 8mm to 15mm, and the maximum outer diameter is 40mm to 60mm.

[0051] The implementation of the present invention has the following beneficial effects: the processing method of the anti-vibration branch pipe of the nuclear power plant is simple in design, easy to implement in batches, and has a wide range of applications. For nuclear power plant anti-vibration branch pipes of different specifications, this optimized design and processing method can be used for processing. Since the anti-vibration branch pipe of the nuclear power plant adopts an integrated forming design, compared with the existing "branch seat-butt weld-branch pipe" structure, the butt weld is eliminated, and the power unit power reduction or shutdown caused by weld vibration fatigue fracture is completely solved, and the risk of fatigue fracture of the branch pipe due to vibration is greatly reduced. The integrated forming design avoids welding connections, simplifies the on-site installation process, and improves installation efficiency. The integrated forming design reduces the number of welding joints and reduces maintenance and overhaul costs. Therefore, the present invention has significant advantages in improving the vibration fatigue safety of nuclear power plant branches and improving the reliability and economy of power plant operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] In order to more clearly illustrate the technical solution of the present invention, the present invention will be further described below with reference to the accompanying drawings and embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be considered as limiting the scope. A person of ordinary skill in the art can derive other relevant drawings based on these drawings without inventive effort. In the drawings:

[0053] Figure 1 is a schematic structural diagram of an anti-vibration branch pipe in a nuclear power plant in some embodiments of the present invention;

[0054] Figure 2 is a schematic flow chart of a method for processing anti-vibration branch pipes for nuclear power plants in some embodiments of the present invention;

[0055] Figure 3 Schematic diagram of a finite element model of an anti-vibration branch pipe of a nuclear power plant in some embodiments of the present invention. DETAILED DESCRIPTION

[0056] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific embodiments of the present invention are now described in detail with reference to the accompanying drawings. In the following description, it should be understood that the directions or positional relationships indicated by "front", "back", "up", "down", "left", "right", "longitudinal", "horizontal", "vertical", "horizontal", "top", "bottom", "inside", "outside", "head", "tail", etc. are based on the directions or positional relationships shown in the accompanying drawings and are constructed and operated in specific directions. They are only for the convenience of describing the technical solution and do not indicate that the devices or components referred to must have specific directions. Therefore, they should not be understood as limiting the present invention.

[0057] It should also be noted that, unless otherwise clearly specified and limited, terms such as "installed", "connected", "connected", "fixed", and "set" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integrated connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. When an element is referred to as being "on" or "under" another element, the element can be "directly" or "indirectly" located on the other element, or there may be one or more intervening elements. The terms "first", "second", "third", etc. are only for the convenience of describing the present technical solution, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first", "second", "third", etc. may explicitly or implicitly include one or more of such features. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0058] See also Figure 1 , is a vibration-resistant branch pipe for a nuclear power plant in some embodiments of the present invention, comprising a branch pipe body 1 and a pipe seat 2 integrally formed with the branch pipe body 1, with a smooth transition between the branch pipe body 1 and the pipe seat 2. It is understandable that in conventional technology, small branches are connected to the mother pipe, and the vibration of the mother pipe generates an excitation force on the small branches. This excitation force is generally unavoidable, and vibration fatigue cracking is prone to occur at the connecting weld between the pipe seat 2 and the branch pipe body 1. In this embodiment, the branch pipe body 1 and the pipe seat 2 are designed as an integrated structure, eliminating the original weld structure. The integrated smooth transition between the pipe seat 2 and the branch pipe body 1 greatly reduces stress concentration and eliminates discontinuities in material properties, completely resolving the problem of branch pipe vibration fatigue failure. It also reduces on-site welding work and the work of non-destructive testing of welds after installation and during overhaul. At the same time, it simplifies the bracket layout and is highly economical.

[0059] The branch pipe body 1 has a diameter of 14 mm to 27 mm, a wall thickness of 2 mm to 4 mm, and a length of 100 mm to 1200 mm. The branch pipe body 1 preferably has a diameter of 16 mm, a wall thickness of 3 mm, and a length of 1000 mm. The tube base 2 has a length of 70 mm to 80 mm, an inner diameter of 8 mm to 15 mm, and a maximum outer diameter of 40 mm to 60 mm. The tube base 2 preferably has a length of 74 mm, an inner diameter of 10 mm, and a maximum outer diameter of 46 mm.

[0060] In this embodiment, if Figure 2 As shown, a design and processing method for anti-vibration branch pipes of nuclear power plants is also constructed, which includes the following steps:

[0061] S1: Determine the interface dimensions between the pipe base 2 and the mother pipe, as well as the outer diameter, wall thickness, and length parameters of the branch pipe body 1. Use topology optimization methods to achieve a smooth transition between the pipe base 2 and the branch pipe body 1, obtain the optimal structure of the pipe base 2, and draw a machining diagram for the anti-vibration branch pipe of the nuclear power plant.

[0062] S2: Heat treatment of workpieces used to manufacture anti-vibration branch pipes for nuclear power plants;

[0063] S3: deep hole drilling of the heat-treated workpiece;

[0064] S4: Use a CNC lathe to perform rough machining on the workpiece after deep hole drilling;

[0065] S5: Remove residual stress from the workpiece after rough machining;

[0066] S6: Use CNC lathe to finish-process the workpiece after residual stress removal;

[0067] S7: Perform quality control and inspection on the workpiece after processing.

[0068] Specifically, in step S1, the topology optimization method includes:

[0069] S11: Based on the interface dimensions between the pipe base 2 and the mother pipe, and the outer diameter, wall thickness, and length parameters of the branch pipe body 1, a finite element model is established, constraints on the size of the pipe base 2 are set, and material structural parameters are defined. The material structural parameters include elastic modulus, Poisson's ratio, structural damping, and material density.

[0070] S12: Setting a preset bending moment load, performing static calculation and modal calculation of the initial model of the pipe base 2 under the preset bending moment load, and obtaining the structural strength, stress, and first-order modal characteristics of the initial model of the pipe base 2 under the preset bending moment load;

[0071] S13: Topological optimization is performed on the structure of the initial model of the pipe base 2 using a variable density method, and a preset material retention rate is set to obtain an optimized model of the pipe base 2 with maximum structural strength, minimum stress, and highest first-order modal frequency under a preset bending moment load;

[0072] S14: geometrically optimizing the optimization model according to the structural performance and production process requirements of the tube socket 2 , and fitting and optimizing the optimization model using a spline curve method to obtain an optimal model of the tube socket 2 .

[0073] like Figure 3As shown, the left side is the initial model of the pipe socket 2, and the right side is the optimal model of the pipe socket 2. It can be understood that the topology optimization method is a mathematical method for optimizing the material distribution in a given area according to given load conditions, constraints and performance indicators. It is a type of structural optimization. Using this topology optimization method, the optimal shape of the pipe socket 2 can be obtained to ensure the mechanical properties of the anti-vibration branch pipe of the nuclear power plant as a whole during use. Specifically, in step S11, the material can be specifically defined as 316L stainless steel, and the elastic modulus, Poisson's ratio, structural damping and material density corresponding to 316L stainless steel can be input. In step S12, the preset bending moment load can be set according to actual production needs. The static calculation and modal calculation are algorithms based on the existing technology of finite element software. Through this static calculation and modal calculation, the structural strength, stress and first-order modal characteristics of the initial model of the pipe socket 2 under the preset bending moment load can be obtained. In addition, in step S13, variable density topology optimization is a density-based topology optimization method. It optimizes the topological structure by defining any point within the design area as a material or void with different densities. The basic idea is to treat the material density distribution within the initial area as a set of multidimensional data, and then use various mathematical methods and algorithms to process this data to generate the optimal structure. In this embodiment, the preset material retention rate is set to 50%, and the preset material retention rate can be adjusted according to actual conditions. In step S14, the optimization model can be geometrically optimized and fitted and optimized using a spline curve method to obtain the optimal model of the tube socket 2. That is, the specific dimensions of the tube socket 2 are finally determined to ensure that the shape transition of the tube socket 2 is smooth, avoid stress concentration, meet the structural performance and production process requirements, and have manufacturability.

[0074] In addition, in step S1, SolidWorks software can be used to draw a processing drawing of the anti-vibration branch pipe of the nuclear power plant.

[0075] In step S2, the workpiece is a forging made of stainless steel and heat-treated at a temperature of 1040°C to 1065°C. The anti-vibration branch pipes for nuclear power plants are made of forgings, heat-treated, and then machined. In this embodiment, 316L stainless steel is used, and the heat-treatment temperature is preferably set to 1050°C.

[0076] Furthermore, step S3 includes:

[0077] S31: Fix the heat-treated workpiece on the workbench of the drilling machine and clamp it with a fixture to ensure the accurate and stable position of the workpiece. Specific fixtures or auxiliary supports can be used;

[0078] S32: According to the workpiece material and the type of drill bit, set the appropriate speed, feed rate and cutting depth. In this embodiment, the speed is set to 1100, the feed rate is set to 20 mm, and the cutting depth is set to 0.1 mm;

[0079] S33: Start the drilling machine and begin deep hole drilling. During the machining process, the operator should closely monitor the status of the drill bit and the flow of coolant to ensure the stability of the machining process;

[0080] S34: Chip removal. Since the chips generated by deep hole drilling are long and difficult to be discharged naturally, it is necessary to effectively manage the discharge of chips to avoid clogging the drill bit and damaging the workpiece.

[0081] S35: After drilling is completed, use measuring tools to measure and inspect the machined holes of the anti-vibration branch pipes of the nuclear power plant to ensure that their size and position accuracy meet the requirements. The measuring tools can be internal diameter micrometers and depth gauges.

[0082] S36: Clean the coolant and chips on the workpiece surface to ensure the quality of the workpiece.

[0083] In addition, in step S4, the workpiece after deep hole drilling is rough-machined using a CNC lathe, that is, the workpiece is preliminarily machined on the CNC lathe, mainly to remove the oxide layer, rust, scratches, etc. on the surface of the workpiece, laying the foundation for subsequent fine machining. This step S4 includes:

[0084] S41: Install the workpiece on the CNC lathe, ensuring that the workpiece is stable and correctly aligned. The workpiece can be mounted on the chuck or fixture of the CNC lathe;

[0085] S42: Select the appropriate first tool based on the workpiece material and rough machining requirements. Rough machining usually uses a large amount of cutting, so a tool with good rigidity is required.

[0086] S43: setting a feed path of the first tool and cutting parameters of the workpiece in a programming system of the CNC lathe, where the cutting parameters may be a preset cutting speed, feed rate, and cutting depth;

[0087] S44: According to the material of the workpiece and the performance of the first tool, the appropriate cutting speed and feed rate are adjusted. A larger cutting depth and feed rate are usually used during roughing to improve processing efficiency. In step S4, the cutting speed of the CNC lathe is set to S600, the feed rate is 0.12 mm, and the cutting depth is 1 mm.

[0088] S45: Start the CNC lathe and perform rough machining. During the machining process, the operator should closely monitor the cutting process to ensure stable machining and avoid abnormalities.

[0089] S46: After the rough machining is completed, check whether there is any residual oxide layer, rust or scratches on the surface of the workpiece. If it does not meet the rough machining requirements, perform rough machining again;

[0090] S47: Clean the iron chips and oil stains on the surface of the workpiece to prepare for subsequent finishing.

[0091] In step S5, the heat treatment temperature for removing residual stress of the workpiece after rough machining is 300° C. to 350° C. It can be understood that machining residual stress will be formed on the surface of the workpiece after deep hole drilling and rough machining, so the workpiece needs to be heat treated to eliminate the residual stress.

[0092] In step S6, the workpiece is subjected to high-precision machining on a CNC lathe to obtain the desired final size, shape, and surface quality of the workpiece. Step S6 includes:

[0093] S61: Install the workpiece on the CNC lathe to ensure that the workpiece is installed on the lathe with accurate position and firm clamping, and can use the center hole or top support;

[0094] S62: Select the appropriate second tool and grinding wheel according to the processing requirements. Specifically, you can choose a high-precision turning tool and a fine-grained grinding wheel;

[0095] S63: Setting a feed path of the second tool and cutting parameters of the workpiece in the programming system of the CNC lathe. Specifically, inputting or selecting a suitable machining program in the programming system of the CNC lathe. The program should include the feed path of the tool, cutting parameters (such as cutting speed, feed rate, cutting depth), etc.;

[0096] S64: Adjust the appropriate cutting speed and feed rate according to the material of the workpiece and the performance of the second tool. Use a smaller cutting depth and feed rate during finishing to improve machining accuracy.

[0097] S65: Start the CNC lathe and perform finishing. During the machining process, the operator should closely monitor the cutting process to ensure stable machining and avoid abnormalities.

[0098] S66: After finishing, use measuring tools to measure and inspect the workpiece to ensure that its size and shape accuracy meet the requirements. If it does not meet the finishing requirements, then perform finishing. The measuring tool can be an outside micrometer, roundness meter, etc.

[0099] S67: Clean the grinding fluid and iron chips on the surface of the workpiece and perform rust prevention treatment.

[0100] Among them, in order to ensure the processing quality, fine processing can be done multiple times.

[0101] In step S6, the cutting speed of the CNC lathe is set to S800, the feed rate is set to 0.1 mm, and the cutting depth is set to 0.3 mm.

[0102] In step S7, in order to ensure the processing quality of the anti-vibration branch pipe of the nuclear power plant, strict quality control needs to be carried out after all processing is completed. This step S7 includes:

[0103] S71: Dimension and shape accuracy inspection: Use measuring tools such as outside micrometers and roundness gauges to inspect the dimension and shape accuracy of the finished workpiece to ensure that it meets the design requirements;

[0104] S72: Surface quality inspection, observe whether there are scratches, cracks, rust and other defects on the surface of the workpiece, and take corresponding measures;

[0105] S73: Handling of unqualified products. Products that fail the inspection will be scrapped to ensure that all processed nuclear power plant anti-vibration branches meet the quality standards.

[0106] It can be understood that the processing method of the anti-vibration branch pipe of the nuclear power plant is simple in design, easy to implement in batches, and has a wide range of applications. This optimized design and processing method can be used for processing anti-vibration branch pipes of nuclear power plants of different specifications. Since the anti-vibration branch pipe of the nuclear power plant adopts an integrated forming design, compared with the existing "branch seat-butt weld-branch pipe" structure, the butt weld is eliminated, which completely solves the power reduction or shutdown of the unit caused by vibration fatigue fracture of the weld, and greatly reduces the risk of fatigue fracture of the branch pipe due to vibration. The integrated forming design avoids welding connections, simplifies the on-site installation process, and improves installation efficiency. The integrated forming design reduces the number of welding joints and reduces maintenance and overhaul costs. Therefore, the present invention has significant advantages in improving the vibration fatigue safety of nuclear power plant branches and improving the reliability and economy of power plant operation.

[0107] It can be understood that the above embodiments only express the preferred implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the patent scope of the present invention. It should be pointed out that for ordinary technicians in this field, without departing from the concept of the present invention, the above technical features can be freely combined, and several deformations and improvements can be made, all of which fall within the scope of protection of the present invention. Therefore, all equivalent changes and modifications made to the scope of the claims of the present invention should fall within the scope of coverage of the claims of the present invention.

Claims

1. A method for processing a vibration-resistant branch pipe for a nuclear power plant, the vibration-resistant branch pipe for a nuclear power plant comprising a branch pipe body (1) and a pipe seat (2) integrally formed with the branch pipe body (1), characterized in that: Including steps: S1: Determine the interface dimensions between the pipe seat (2) and the mother pipe, as well as the outer diameter, wall thickness and length parameters of the branch pipe body (1), adopt a topology optimization method to make a smooth transition between the pipe seat (2) and the branch pipe body (1), obtain the optimal structure of the pipe seat (2), and draw a processing diagram of the anti-vibration branch pipe of the nuclear power plant; S2: heat treating the workpiece for manufacturing the anti-vibration branch pipe of the nuclear power plant; S3: performing deep hole drilling on the workpiece after heat treatment; S4: performing rough machining on the workpiece after deep hole drilling using a CNC lathe; S5: removing residual stress from the workpiece after rough machining; S6: using a CNC lathe to perform finish machining on the workpiece after residual stress removal; S7: Performing quality control and inspection on the workpiece after processing; The topology optimization method comprises: S11: Based on the interface dimensions between the pipe seat (2) and the mother pipe and the outer diameter, wall thickness and length parameters of the branch pipe body (1), a finite element model is established, constraints on the size limit of the pipe seat (2) are set, and material structural parameters are defined. The material structural parameters include elastic modulus, Poisson's ratio, structural damping and material density; S12: setting a preset bending moment load, carrying out static calculation and modal calculation of the initial model of the pipe seat (2) under the preset bending moment load, and obtaining the structural strength, stress and first-order modal characteristics of the initial model of the pipe seat (2) under the preset bending moment load; S13: topological optimization is performed on the structure of the initial model of the pipe seat (2) using a variable density method, a preset material retention rate is set, and an optimized model of the pipe seat (2) with the maximum structural strength, the minimum stress and the highest first-order modal frequency under a preset bending moment load is obtained; S14: According to the structural performance and production process requirements of the tube seat (2), the optimization model is geometrically optimized, and the optimization model is fitted and optimized using a spline curve method to obtain the optimal model of the tube seat (2).

2. The method for processing anti-vibration branch pipes of nuclear power plants according to claim 1, characterized in that: In step S2, the workpiece is a forging, which is made of stainless steel and is heat treated at a temperature of 1040°C to 1065°C.

3. The method for processing anti-vibration branch pipes of nuclear power plants according to claim 1, characterized in that: Step S3 includes: S31: Fixing the heat-treated workpiece on a workbench of a drilling machine and clamping it with a fixture; S32: setting a suitable rotation speed, feed rate and cutting depth according to the workpiece material and the type of drill bit; S33: Start the drilling machine and start deep hole drilling; S34: perform chip removal; S35: After drilling is completed, use measuring tools to measure and inspect the machined holes of the anti-vibration branch pipes of the nuclear power plant to ensure that their size and position accuracy meet the requirements; S36: Cleaning the coolant and chips on the surface of the workpiece.

4. The method for processing anti-vibration branch pipes of nuclear power plants according to claim 1, characterized in that: Step S4 includes: S41: Mounting the workpiece on a CNC lathe, ensuring that the workpiece is stable and correctly aligned; S42: selecting a suitable first tool according to the material of the workpiece and the requirements of rough machining; S43: setting a feed path of the first tool and cutting parameters of the workpiece in a programming system of a CNC lathe; S44: adjusting a suitable cutting speed and feed rate according to the material of the workpiece and the performance of the first tool; S45: Start the CNC lathe to perform rough processing; S46: After the rough machining is completed, check whether there is any residual oxide layer, rust or scratches on the surface of the workpiece. If the rough machining requirements are not met, perform rough machining again; S47: Cleaning iron filings and oil stains on the surface of the workpiece.

5. The method for processing anti-vibration branch pipes of nuclear power plants according to claim 1, characterized in that: In step S5, the heat treatment temperature for removing residual stress of the workpiece after rough machining is 300°C to 350°C.

6. The method for processing anti-vibration branch pipes of nuclear power plants according to claim 1, characterized in that: Step S6 includes: S61: Mounting the workpiece on a CNC lathe; S62: Select the appropriate second tool and grinding wheel according to the processing requirements; S63: Setting a feed path of the second tool and cutting parameters of the workpiece in a programming system of the CNC lathe; S64: adjusting a suitable cutting speed and feed rate according to the material of the workpiece and the performance of the second tool; S65: Start the CNC lathe for finishing; S66: After finishing, the workpiece is measured and inspected using a measuring tool to ensure that its size and shape accuracy meet the requirements. If the finishing requirements are not met, further finishing is performed. S67: cleaning the grinding fluid and iron chips on the surface of the workpiece and performing rust prevention treatment.

7. The method for processing anti-vibration branch pipes of nuclear power plants according to claim 1, characterized in that: Step S7 includes: S71: Dimension and shape accuracy inspection: Use measuring tools such as outside micrometers and roundness gauges to inspect the dimension and shape accuracy of the finished workpiece to ensure that it meets the design requirements; S72: Surface quality inspection, observe whether there are scratches, cracks, rust and other defects on the surface of the workpiece, and take corresponding measures; S73: Handling of unqualified products. Products that fail the inspection will be scrapped to ensure that all processed nuclear power plant anti-vibration branches meet the quality standards.

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