A method for forming a mold of a nuclear power tube plate

Abstract

The present invention discloses a die forming method for nuclear power tube plates, the die forming method comprising the following steps: designing and manufacturing a mold and determining a forging forming process through simulation technology; the mold comprises an outer ring mold and an upper pad; upsetting and drawing a metal ingot to form a blank; forming a membrane: placing the blank in the outer ring mold, using a flat anvil on a press to repeatedly press down until the blank fills the inner cavity of the outer ring mold to form a forging blank, placing an upper pad on the forging blank, and aligning the upper pad with the forging blank, using a flat anvil on a press to repeatedly press down on the upper pad until the upper end surface of the upper pad is flush with the forging blank to form a forging; separating the forging from the mold. The die forming method for nuclear power tube plates provided by the present invention can significantly improve the compaction effect of the die by using a mold with a constraining effect to form forgings, effectively reduce the occurrence of defects such as looseness and density in the die center, and ensure that the die size is more accurate.

Description

Technical Field

[0001] The invention relates to a die forming method for a nuclear power tube plate forging. Background Art

[0002] Tube sheets are core components in chemical containers such as steam generators, heat exchangers, boilers, pressure vessels, steam turbines, and large central air conditioners. They are mainly responsible for supporting and fixing tubes and sealing media. In the field of nuclear power, tube sheets are generally used in steam generator equipment. As a key part of supporting U-shaped heat exchange tubes, they play a key role in ensuring the barrier function between the primary and secondary circuits. The steam generator tube sheet has a specific shape design, presenting a pancake-shaped structure with flanges at both ends. It is usually made of low-alloy steel material, and its wall thickness is usually not less than 200mm. However, during the forging process, if the control is not proper, it is easy to cause quality problems such as loose center and intensive defects, which may lead to product scrapping. Therefore, the quality control of tube sheet forgings has always been one of the technical difficulties faced by the field of nuclear power forging manufacturing.

[0003] In recent years, with the continuous advancement of nuclear power technology, new generation nuclear power technologies such as high temperature gas-cooled reactors, sodium fast-cooled reactors and other fourth-generation nuclear power units have proposed innovative solutions using special materials such as stainless steel and nickel-based high-temperature alloys as tube sheet materials. However, due to the high cost of these special materials, higher requirements are also placed on the dimensional accuracy and yield rate of tube sheet manufacturing, which undoubtedly increases the technical difficulty and quality control challenges of tube sheet manufacturing. Summary of the invention

[0004] In view of the above-mentioned shortcomings of the current nuclear power tube sheets, the present invention provides a mold forming method for nuclear power tube sheets. By adopting a mold with a constraining effect to perform forging forming, the compaction effect of the mold can be significantly improved, the occurrence of defects such as looseness and density in the center of the mold can be effectively reduced, and the mold size can be ensured to be more precise.

[0005] To achieve the above object, the embodiments of the present invention adopt the following technical solutions:

[0006] A method for forming a mold of a nuclear power tube plate, the mold forming method comprising the following steps:

[0007] Design and manufacture the die and determine the forging forming process through simulation technology; the die includes an outer ring die and an upper pad;

[0008] Upsetting and drawing forging of metal ingots into billets;

[0009] The blank is placed in the outer ring die, and the flat anvil on the press is used to repeatedly press down until the blank fills the inner cavity of the outer ring die to form a forging blank, an upper pad is placed on the forging blank, and the upper pad is aligned with the forging blank, and the flat anvil on the press is used to repeatedly press down the upper pad until the upper end surface of the upper pad is flush with the forging blank to form a forging;

[0010] Separate the forging from the die.

[0011] According to one aspect of the present invention, the tire mold forming method further comprises the following steps: performing rough machining on the forging before heat treatment and performing property heat treatment on the forging.

[0012] According to one aspect of the present invention, the performance heat treatment is a solution heat treatment, the solution heat treatment temperature is 1050-1100°C, and during the performance heat treatment, rapid cooling is performed after the insulation is completed.

[0013] According to one aspect of the present invention, the performance heat treatment includes low-temperature preheating, medium-temperature preheating and high-temperature rapid heating.

[0014] According to one aspect of the present invention, the low-temperature preheating temperature is 600°C, the medium-temperature preheating temperature is 900°C, and the high-temperature rapid heating temperature is 1050-1100°C.

[0015] According to one aspect of the present invention, the following steps are performed after the forging is subjected to the performance heat treatment: physical and chemical testing is performed.

[0016] According to one aspect of the present invention, the slopes of the outer ring mold and the upper pad are both 3 to 8 degrees, and the slope is the angle between the inner wall of the outer ring mold or the side wall of the upper pad and the vertical direction.

[0017] According to one aspect of the present invention, the tire mold forming method further comprises the step of machining the forging.

[0018] According to one aspect of the present invention, the steps of the tire mold forming method further include the following steps: performing finished product inspection on the machined forging, wherein the finished product inspection adopts liquid penetration monitoring and overall ultrasonic inspection.

[0019] According to one aspect of the present invention, the hot forging is carried out in three steps. In the first step, the metal ingot is stretched, chamfered, and hot cut; in the second step, the billet is roughened and stretched with a large deformation amount to break the grains; in the third step, the billet is roughened and stretched for the second time to further refine the grains.

[0020] According to one aspect of the present invention, the simulation technology is to use computer simulation and numerical analysis methods to predict the forging process, and the simulation and numerical analysis include the flow of metal materials, stress and strain distribution, temperature changes and die forces.

[0021] According to one aspect of the present invention, the simulation method of the simulation technology includes the following steps: establishing a geometric model according to the shape of the nuclear power tube sheet and the mold, the geometric model includes the initial shape of the nuclear power tube sheet, the cavity shape of the mold, the shape of the upper pad, the heating device and the cooling system; establishing a material model according to the material used for the nuclear power tube sheet; meshing the geometric model; setting loading and boundary conditions; performing numerical solution; analyzing relevant data, and optimizing the process parameters, mold design and forging forming process according to the analysis results.

[0022] The advantages of the implementation of the present invention are as follows: through rough processing before heat treatment, the dimensional accuracy of the forgings can be controlled to be finer; through three hot forging billets and performance heat treatment processes, the finer grain size of the metal material can be effectively retained, thereby improving its overall performance; through physical and chemical testing, the high quality and reliability of materials and molds can be ensured, thereby effectively improving the utilization rate of materials and realizing efficient utilization of resources; by using a mold with a constraining effect to form forgings, an excellent compaction effect can be achieved, and the occurrence of quality defects such as looseness and density in the center of the forgings can be significantly reduced. The mold forming method of the nuclear power tube plate of the present invention can significantly improve the compaction effect of the mold by using a mold with a constraining effect to form forgings, effectively reduce the occurrence of defects such as looseness and density in the center of the mold, and ensure that the mold size is more accurate, and realize accurate control of the material surplus, thereby effectively reducing production costs and improving production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 It is a process flow chart of a fetal membrane forming method of a fetal mold forming method of a nuclear power tube plate according to the present invention;

[0025] Figure 2 This is a process flow chart of the fetal membrane forming method according to Embodiment 2 of the present invention;

[0026] Figure 3 It is a schematic diagram of forging forming of a die forming method of a nuclear power tube plate according to the present invention;

[0027] Figure 4 A schematic diagram of a hot forging process of a mold forming method for a nuclear power tube plate according to the present invention;

[0028] Figure 5The present invention is a performance heat treatment process curve diagram of a tire mold forming method for a nuclear power tube plate.

[0029] Figure 6 The product process flow of the nuclear power tube plate of the tire mold forming method of the nuclear power tube plate;

[0030] Figure 7 This is a mold process flow chart of the present invention;

[0031] Figure 8 This is the strain cloud diagram in the traditional forging simulation technology;

[0032] Fig. 9 The present invention is a strain cloud diagram in the simulation technology of a mold forming method for a nuclear power tube plate.

[0033] Numbers in the figure: 1. upper anvil of press; 2. blank; 3. outer ring die; 4. upper pad; 5. forging. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] Embodiment 1:

[0036] like Figure 1 , Figure 3 , Figure 4 and Figure 7 As shown, a tire mold forming method for a nuclear power tube plate, the tire mold forming method comprises the following steps:

[0037] S1: Design and manufacture dies and determine forging forming processes through simulation technology

[0038] Finite element simulation technology is used to accurately simulate the forging forming process, so as to scientifically and reasonably determine the forging forming technology plan and mold design plan. The mold is divided into two modules, including the outer ring mold 3 and the upper pad 4. According to the size of the finished forging blank, simulation technology is used to simulate and verify and design the mold cavity size and the upper pad size. The mold is manufactured according to the designed size to ensure the accuracy and stability of the mold. In order to further improve the durability of the mold, we also professionally modulate the mold to enhance its toughness, thereby effectively extending the service life of the mold.

[0039] The simulation technology is an advanced technology that uses computer simulation and numerical analysis methods to predict the flow of metal materials, stress and strain distribution, temperature changes, and die stress during the forging process. Forging simulation technology can simulate different forging schemes virtually before actual production, thereby optimizing process parameters, improving die design, improving the quality and production efficiency of forged products, and reducing production costs.

[0040] The simulation method of the simulation technology is as follows:

[0041] Step 1: Geometry Modeling

[0042] According to the shape of nuclear power tube sheet and mold, use 3D modeling software to build an accurate geometric model. The model needs to include the initial shape of nuclear power tube sheet, the cavity shape of mold, the shape of upper pad, and the geometry of possible auxiliary equipment such as heating device and cooling system.

[0043] Step 2: Material model establishment

[0044] The mechanical behavior of metal materials during forging is described based on the material model used for nuclear power tube plates (such as steel, nickel-based high-temperature alloys, etc.). Common material models include elastic-plastic models, rigid-plastic models, etc. The material model needs to consider the stress-strain relationship, thermophysical properties (such as thermal conductivity, specific heat capacity, etc.) of metal materials, and the softening and flow characteristics of materials at high temperatures.

[0045] Step 3: Meshing

[0046] Divide the geometric model into a finite number of small units to form a grid structure. In forging simulation, a fine grid is usually required to accurately describe the flow and deformation of metal materials in the mold cavity. At the same time, in order to improve calculation efficiency, a coarser grid can be used away from the deformation area.

[0047] Step 4: Set up loading and boundary conditions

[0048] First, the loading conditions in the forging process are defined, including the loading method of the press, the friction conditions between the die and the part, etc.

[0049] Then, set the boundary conditions, such as the fixed constraints of the mold, the initial temperature of the part, the preheating temperature of the mold, etc.

[0050] Step 5: Numerical solution

[0051] In the first four steps, we have established the geometry model, material model, meshed, and set loading boundary conditions. Now, we will use numerical analysis methods, such as finite element method or finite difference method, to solve the mechanical and thermal equations involved in the forging process.

[0052] Through numerical solution, we can obtain key information such as the stress and strain distribution of metal materials at each moment in the forging process, temperature changes, forces borne by the die, and changes in part shape.

[0053] Step 6: Result Analysis and Optimization

[0054] The relevant data obtained during the digital solution process will be analyzed to evaluate the feasibility of the forging process and product quality. By observing the flow of metal materials, it is possible to determine whether there are defects such as folding and insufficiency; analyze the stress and strain distribution to evaluate the strength and life of the parts; check the force on the mold to ensure that the strength and life of the mold meet the requirements. Based on the analysis results, the process parameters, mold design and forging forming process are optimized to ensure the efficiency of the production process and the high quality of the product.

[0055] By repeatedly executing the simulation steps of the above simulation technology, we can continuously adjust the process parameters, optimize the die design and forging forming process until the best state is achieved. In this way, the die designed and manufactured using this die, combined with the corresponding process parameters and forging forming process, the nuclear power tube plates produced will fully meet the standard requirements.

[0056] S2: Hot forging

[0057] The metal ingot is roughened and stretched to form a blank. The metal ingot can be a steel ingot, a nickel-based high-temperature alloy or other metal material. The hot forging blank is generally carried out in three steps. The first step is to stretch and chamfer the metal ingot and hot cut it. The second step is to roughen and stretch the blank after the first step with a large deformation to break the grains. The third step is to roughen and stretch the blank after the second step for a second time to further refine the grains.

[0058] S3: Formation of membranes

[0059] The blank is placed in the outer ring die, and the flat anvil on the press is used to repeatedly press down until the blank fills the inner cavity of the outer ring die to form a forging blank; an upper pad is placed on the forging blank, and the upper pad is aligning with the forging blank, and the flat anvil on the press is used to repeatedly press down on the upper pad until the upper end surface of the upper pad is flush with the forging blank to form a forging.

[0060] S4: Demolding

[0061] The forging and the die are turned upside down on the pad, and the forging blank is lightly pressed to separate the forging from the die. The slope of the outer ring die and the upper pad is 3 to 8 degrees, and the slope is the angle between the inner side wall of the outer ring die or the side wall of the upper pad and the vertical direction, so that the forging is easier to demould after compaction.

[0062] Advantages of this embodiment:

[0063] The membrane of nuclear power tube sheet can achieve excellent compaction effect by using a constrained die to forge, significantly reducing the occurrence of quality defects such as looseness and density in the center of the forging. At the same time, this method helps to improve the dimensional accuracy of forgings and achieve precise control of material allowance, thereby effectively reducing production costs.

[0064] Embodiment 2:

[0065] like Figure 2 , Figure 3 , Figure 4 , Figure 6 and Figure 7 As shown, a tire mold forming method for a nuclear power tube plate, the tire mold forming method comprises the following steps:

[0066] S1: Design and manufacture dies and determine forging forming processes through simulation technology

[0067] Finite element simulation technology is used to accurately simulate the forging forming process, so as to scientifically and reasonably determine the forging forming technology plan and mold design plan. The mold is divided into two modules, including the outer ring mold 3 and the upper pad 4. According to the size of the finished forging blank, simulation technology is used to simulate and verify and design the mold cavity size and the upper pad size. The mold is manufactured according to the designed size to ensure the accuracy and stability of the mold. In order to further improve the durability of the mold, we also professionally modulate the mold to enhance its toughness, thereby effectively extending the service life of the mold.

[0068] The simulation technology is an advanced technology that uses computer simulation and numerical analysis methods to predict the flow of metal materials, stress and strain distribution, temperature changes, and die stress during the forging process. Forging simulation technology can simulate different forging schemes virtually before actual production, thereby optimizing process parameters, improving die design, improving the quality and production efficiency of forged products, and reducing production costs.

[0069] The simulation method of the simulation technology is as follows:

[0070] Step 1: Geometry Modeling

[0071] According to the nuclear power tube sheet parts and mold shape, use 3D modeling software to build an accurate geometric model. The model needs to include the initial shape of the nuclear power tube sheet, the cavity shape of the mold, the shape of the upper pad, and the geometry of possible auxiliary equipment such as heating devices and cooling systems.

[0072] Step 2: Material model establishment

[0073] The mechanical behavior of metal materials during forging is described based on the material model used for nuclear power tube plates (such as steel, nickel-based high-temperature alloys, etc.). Common material models include elastic-plastic models, rigid-plastic models, etc. The material model needs to consider the stress-strain relationship of metal materials, thermophysical properties (such as thermal conductivity, specific heat capacity, etc.), and softening and flow characteristics of materials at high temperatures.

[0074] Step 3: Meshing

[0075] Divide the geometric model into a finite number of small units to form a grid structure. In forging simulation, a fine grid is usually required to accurately describe the flow and deformation of metal materials in the mold cavity. At the same time, in order to improve calculation efficiency, a coarser grid can be used away from the deformation area.

[0076] Step 4: Set up loading and boundary conditions

[0077] First, the loading conditions in the forging process are defined, including the loading method of the press, the friction conditions between the die and the part, etc.

[0078] Then, set the boundary conditions, such as the fixed constraints of the mold, the initial temperature of the part, the preheating temperature of the mold, etc.

[0079] Step 5: Numerical solution

[0080] In the first four steps, we have established the geometry model, material model, meshed, and set loading boundary conditions. Now, we will use numerical analysis methods, such as finite element method or finite difference method, to solve the mechanical and thermal equations involved in the forging process.

[0081] Through numerical solution, we can obtain key information such as the stress and strain distribution of metal materials at each moment in the forging process, temperature changes, forces borne by the die, and changes in part shape.

[0082] Step 6: Result Analysis and Optimization

[0083] The relevant data obtained during the digital solution process will be analyzed to evaluate the feasibility of the forging process and the quality of the product. By observing the flow of the metal material, it can be determined whether there are defects such as folding and insufficiency; the stress and strain distribution can be analyzed to evaluate the strength and life of the parts; the mold force can be checked to ensure that the strength and life of the mold meet the requirements. Based on the analysis results, the process parameters and mold design are optimized to ensure the efficiency of the production process and the high quality of the product.

[0084] By repeatedly executing the simulation steps of the above simulation technology, we can continuously adjust the process parameters, optimize the die design and forging forming process until the best state is achieved. In this way, the die designed and manufactured using this die, combined with the corresponding process parameters and forging forming process, the nuclear power tube plates produced will fully meet the standard requirements.

[0085] S2: Hot forging: The metal ingot is roughened and stretched to form a billet. The metal ingot can be a steel ingot, a nickel-based high-temperature alloy or other metal material. The hot forging is generally carried out in three firings. In the first firing, the metal ingot is stretched, chamfered, and hot cut; the second firing: the billet after the first firing is roughened and stretched with a large deformation to break the grains; the third firing: the billet after the second firing is roughened and stretched for the second time to further refine the grains.

[0086] S3: Formation of membranes

[0087] The blank is placed in the outer ring die, and the flat anvil on the press is used to repeatedly press down until the blank fills the inner cavity of the outer ring die to form a forging blank; an upper pad is placed on the forging blank, and the upper pad is aligning with the forging blank, and the flat anvil on the press is used to repeatedly press down on the upper pad until the upper end surface of the upper pad is flush with the forging blank to form a forging.

[0088] S4: Demolding

[0089] The forging and the die are turned upside down on the pad, and the forging blank is lightly pressed to separate the forging from the die. The slope of the outer ring die and the upper pad is 3 to 8 degrees, and the slope is the angle between the inner side wall of the outer ring die or the side wall of the upper pad and the vertical direction, so that the forging is easier to demould after compaction.

[0090] S5: Rough machining before heat treatment

[0091] The forgings after demoulding are rough-processed to make the size of the forgings closer to the size requirements of the finished product and improve the heat treatment effect.

[0092] S6: Performance Heat Treatment

[0093] The forgings after rough machining are subjected to performance heat treatment, which is a solid solution heat treatment at a temperature of 1050-1100°C. After a suitable period of heat preservation, they are rapidly cooled. The cooling can be performed in water. The performance heat treatment is divided into three stages, namely low temperature preheating, medium temperature preheating, and high temperature rapid heating.

[0094] S7: Physical and chemical testing

[0095] Samples are taken from the heat-treated forgings for physical and chemical testing, and the physical and chemical testing items may include mechanical property testing, composition testing, etc.

[0096] S8: Machining

[0097] The forgings are machined to obtain the finished mold of the nuclear power tube plate; the machining process can be carried out by gantry milling machines, CNC machine tools, vertical drilling and boring machines and other equipment to ensure that the dimensional accuracy and smoothness meet the mold requirements of the nuclear power tube plate.

[0098] S9: Finished product inspection

[0099] The molds of nuclear power tube plates are inspected by liquid penetrant testing and full volume ultrasonic testing.

[0100] Advantages of this embodiment:

[0101] Through rough machining before heat treatment, the dimensional accuracy of forgings can be further controlled; through three-stage hot forging and performance heat treatment processes, the finer grain size of metal materials can be retained; through physical and chemical testing, the high quality and reliability of materials and molds can be ensured, thereby effectively improving the utilization rate of materials and achieving efficient use of resources. By using a constraining mold for forging forming, an excellent compaction effect can be achieved, significantly reducing the occurrence of quality defects such as looseness and density in the center of the forging. At the same time, this method helps to improve the dimensional accuracy of forgings and achieve precise control of material allowances, thereby effectively reducing production costs.

[0102] Embodiment 3:

[0103] like Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 and Figure 7 As shown, the device is applied to a high temperature gas-cooled reactor steam generator, the material is nickel-based high temperature alloy 800H, the forging blank has an outer dimension of φ1010mm and a maximum thickness of 500mm, and is used for forming a tire mold of a nuclear power tube plate. The tire mold forming method comprises the following steps:

[0104] S1: Design and manufacture dies and determine forging forming processes through simulation technology

[0105] Finite element simulation technology is used to accurately simulate the forming process of forgings, so as to scientifically and reasonably determine the forging forming technology and mold design scheme. Through simulation, it is finally confirmed that a combined mold is used. The mold is divided into two modules, including an outer ring mold and an upper pad. According to the size of the finished forging blank, simulation technology is used to simulate and verify and design the mold cavity size and the size of the upper pad. At the same time, considering the convenience of demoulding, the outer ring mold and the upper pad have a slope of 3°-8°, which is the angle between the inner wall of the outer ring mold or the side wall of the upper pad and the vertical direction. The mold is designed according to the above simulation size data to obtain the mold design drawing. The mold is forged according to the design size of the mold design drawing. In order to further improve the durability of the mold, the mold is modulated. The quenching and tempering treatment can be a heat treatment. The toughness of the mold can be enhanced through quenching and tempering treatment, thereby effectively extending the service life of the mold; after the quenching and tempering treatment, the mold is hardness tested. After the hardness test is qualified, the mold is processed after forging to ensure its accuracy.

[0106] In this embodiment, if Figure 7 As shown, the design and manufacturing process of the mold includes forging drawing design, mold plan, design size and simulation, mold drawing design, mold forging, heat treatment, hardness testing, and mold processing.

[0107] The simulation technology is an advanced technology that uses computer simulation and numerical analysis methods to predict the flow of metal materials, stress and strain distribution, temperature changes, and die stress during the forging process. Forging simulation technology can simulate different forging schemes virtually before actual production, thereby optimizing process parameters, improving die design, improving the quality and production efficiency of forged products, and reducing production costs.

[0108] The simulation method of the simulation technology is as follows:

[0109] Step 1: Geometry Modeling

[0110] According to the shape of nuclear power tube sheet and mold, use 3D modeling software to build an accurate geometric model. The model needs to include the initial shape of nuclear power tube sheet, the cavity shape of mold, the shape of upper pad, and the geometry of possible auxiliary equipment such as heating device and cooling system.

[0111] Step 2: Material model establishment

[0112] The material model of nickel-based high-temperature alloy 800H used in nuclear power tube plates is used to describe the mechanical behavior of metal materials during forging. Common material models include elastic-plastic models, rigid-plastic models, etc. The material model needs to consider the stress-strain relationship of metal materials, thermophysical properties (such as thermal conductivity, specific heat capacity, etc.), and softening and flow characteristics of materials at high temperatures.

[0113] Step 3: Meshing

[0114] Divide the geometric model into a finite number of small units to form a grid structure. In forging simulation, a fine grid is usually required to accurately describe the flow and deformation of metal materials in the mold cavity. At the same time, in order to improve calculation efficiency, a coarser grid can be used away from the deformation area.

[0115] Step 4: Set up loading and boundary conditions

[0116] First, the loading conditions in the forging process are defined, including the loading method of the press, the friction conditions between the die and the part, etc.

[0117] Then, set the boundary conditions, such as the fixed constraints of the mold, the initial temperature of the part, the preheating temperature of the mold, etc.

[0118] Step 5: Numerical solution

[0119] In the first four steps, we have established the geometry model, material model, meshed, and set loading boundary conditions. Now, we will use numerical analysis methods, such as finite element method or finite difference method, to solve the mechanical and thermal equations involved in the forging process.

[0120] (2) Through numerical solution, we can obtain key information such as the stress-strain distribution of the metal material at each moment in the forging process, temperature changes, the force exerted on the die, and the shape changes of the parts.

[0121] Step 6: Result Analysis and Optimization

[0122] The relevant data obtained during the digital solution process will be analyzed to evaluate the feasibility of the forging process and product quality. By observing the flow of metal materials, it is possible to determine whether there are defects such as folding and insufficiency; analyze the stress and strain distribution to evaluate the strength and life of the parts; check the force on the mold to ensure that the strength and life of the mold meet the requirements. Based on the analysis results, the process parameters, mold design, forging forming process, etc. are optimized to ensure the efficiency of the production process and the high quality of the product.

[0123] By repeatedly executing the simulation steps of the above simulation technology, we can continuously adjust the process parameters, optimize the die design and forging forming process until the best state is achieved. In this way, the die designed and manufactured using this die, combined with the corresponding process parameters and forging forming process, the nuclear power tube plates produced will fully meet the standard requirements.

[0124] By simulating the high-temperature rheological data of nickel-based high-temperature alloy 800H, in the temperature range of 980 to 1180°C, when the strain rate is 0.03-0.1S -1The material has good hot working properties. The process parameter range of plastic deformation: forging temperature 980-1180℃, strain rate 0.03-0.1S -1 The reduction amount is between 30% and 55% to refine the grain size of the tube sheet to meet the standard requirements.

[0125] At the same time, the traditional method of preparing nuclear island tube sheet forgings was simulated, that is, using upper flat anvil and row anvil spinning to reduce the thickness of the forging and increase the outer diameter, and finally forming it into a forging by rolling. Figure 8 As shown, through simulation, this traditional forging scheme is subjected to compressive stress in the center and tensile stress around, the performance anisotropy is large, the deformation directions of the center and the outer circumference are inconsistent, and the performance uniformity is poor.

[0126] Through simulation, the outer ring die and upper pad are used to prepare nuclear island tube sheet forgings, that is, the blank is placed in the outer ring die, and the flat anvil on the press is used to press down repeatedly until the blank fills the inner cavity of the outer ring die to form a forging blank; the upper pad is placed on the forging blank, and the upper pad is aligned with the forging blank, and the flat anvil on the press is used to press down repeatedly until the upper end surface of the upper pad is flush with the forging blank to form a forging. Fig. 9 As shown, the forgings of this method are formed in a relatively closed space, the material is subjected to strong triaxial stress, each position and direction is subjected to large triaxial stress, there is no tensile stress and shear stress, and the uniformity and compaction effect are better.

[0127] S2: Hot forging

[0128] The metal ingot is roughened and stretched to form a billet. The metal ingot can be a steel ingot, a nickel-based high-temperature alloy or other metal material. The hot forging billet is generally carried out in three steps. The first step: the metal ingot is stretched, chamfered, and hot-cut into an octagonal prism with a diameter of 590 mm and a height of 1490 mm. The second step: the billet after the first step is roughened with a large deformation amount, and after being roughened to a cylindrical shape with a diameter of 900 and a height of 750, it is stretched to an octagonal prism with a diameter of 590 mm and a height of 1490 mm, and the grains are broken by roughening and stretching. The third step: the billet after the second step is roughened for the second time, and after being roughened to a cylindrical shape with a diameter of 900 and a height of 750, it is stretched to an octagonal prism with a diameter of 590 mm and a height of 1490 mm, and the grains are further refined by roughening and stretching.

[0129] S3: Formation of membranes

[0130] The blank is placed in the outer ring die, and the flat anvil on the press is used to repeatedly press down until the blank fills the inner cavity of the outer ring die to form a forging blank; an upper pad is placed on the forging blank, and the upper pad is aligning with the forging blank, and the flat anvil on the press is used to repeatedly press down on the upper pad until the upper end surface of the upper pad is flush with the forging blank to form a forging.

[0131] S4: Demolding

[0132] The forging and the die are turned upside down on the pad, and the forging blank is lightly pressed to separate the forging from the die. The slope of the outer ring die and the upper pad is 3 to 8 degrees, and the slope is the angle between the inner side wall of the outer ring die or the side wall of the upper pad and the vertical direction, so that the forging is easier to demould after compaction.

[0133] S5: Rough machining before heat treatment

[0134] The forgings after demoulding are rough-processed to make the size of the forgings closer to the size requirements of the finished product and improve the heat treatment effect.

[0135] S6: Performance Heat Treatment

[0136] The forgings after rough machining are subjected to a performance heat treatment, which is a solid solution heat treatment at a temperature of 1050-1100°C. After a suitable holding time, they are rapidly cooled, which can be done by rapid cooling in water. Figure 5 As shown, the performance heat treatment (solution heat treatment) is first preheated at 600℃ in the low temperature zone for 1 hour, then preheated at 900℃ in the medium temperature zone for 1 hour, and then quickly heated to 1050-1100℃ in the high temperature zone, and kept warm for 0.5 / 1.5min / mm, and then quickly water cooled.

[0137] S7: Physical and chemical testing

[0138] Samples are taken from the heat-treated forgings for physical and chemical testing, and the physical and chemical testing items may include mechanical property testing, composition testing, etc.

[0139] The mechanical properties test results are shown in the following table:

[0140]

[0141] S8: Machining

[0142] The forgings are machined to obtain the finished mold of the nuclear power tube plate; the machining process can be carried out by gantry milling machines, CNC machine tools, vertical drilling and boring machines and other equipment to ensure that the dimensional accuracy and smoothness meet the mold requirements of the nuclear power tube plate.

[0143] S9: Finished product inspection

[0144] The molds of nuclear power tube plates are inspected by liquid penetrant testing and full volume ultrasonic testing.

[0145] like Figure 6 As shown, forgings are forged by the die forming method as described above, and the forgings are processed to obtain nuclear power tube plates. The processing flow of nuclear power tube plates specifically includes forging, rough processing before heat treatment, UT (ultrasonic test) self-inspection, performance heat treatment, sample cutting, sample processing, physical and chemical testing, rough processing after heat treatment, non-destructive testing, and finished product processing, so as to ensure the production of nuclear power tube plate finished products that meet the standards.

[0146] Advantages of this embodiment:

[0147] Through rough machining before heat treatment, the dimensional accuracy of forgings can be further controlled; through three-stage hot forging and performance heat treatment processes, the finer grain size of metal materials can be retained; through physical and chemical testing, the high quality and reliability of materials and molds can be ensured, thereby effectively improving the utilization rate of materials and achieving efficient use of resources. By using a constraining mold for forging forming, an excellent compaction effect can be achieved, significantly reducing the occurrence of quality defects such as looseness and density in the center of the forging. At the same time, this method helps to improve the dimensional accuracy of forgings and achieve precise control of material allowances, thereby effectively reducing production costs.

[0148] The advantages of the implementation of the present invention are as follows: through rough processing before heat treatment, the dimensional accuracy of the forgings can be controlled to be finer; through three hot forging billets and performance heat treatment processes, the finer grain size of the metal material can be effectively retained, thereby improving its overall performance; through physical and chemical testing, the high quality and reliability of materials and molds can be ensured, thereby effectively improving the utilization rate of materials and realizing efficient utilization of resources; by using a mold with a constraining effect to form forgings, an excellent compaction effect can be achieved, and the occurrence of quality defects such as looseness and density in the center of the forgings can be significantly reduced. The mold forming method of the nuclear power tube plate of the present invention can significantly improve the compaction effect of the mold by using a mold with a constraining effect to form forgings, effectively reduce the occurrence of defects such as looseness and density in the center of the mold, and ensure that the mold size is more accurate, and realize accurate control of the material surplus, thereby effectively reducing production costs and improving production efficiency.

[0149] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the art within the technical scope disclosed in the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A method for forming a mold of a nuclear power tube plate, characterized in that: The tire mold forming method comprises the following steps: Design and manufacture the die and determine the forging forming process through simulation technology; the die includes an outer ring die and an upper pad; Upsetting and drawing forging of metal ingots into billets; The blank is placed in the outer ring die, and the flat anvil on the press is used to repeatedly press down until the blank fills the inner cavity of the outer ring die to form a forging blank, an upper pad is placed on the forging blank, and the upper pad is aligned with the forging blank, and the flat anvil on the press is used to repeatedly press down the upper pad until the upper end surface of the upper pad is flush with the forging blank to form a forging; Separate the forging and the die, The forgings are subjected to performance heat treatment, which is a solution heat treatment at a temperature of 1050-1100°C. During the performance heat treatment, rapid cooling is performed after the insulation is completed. The performance heat treatment includes low-temperature preheating, medium-temperature preheating and high-temperature rapid heating. The low-temperature preheating temperature is 600°C and the low-temperature preheating time is 1 hour. The medium-temperature preheating temperature is 900°C and the medium-temperature preheating time is 1 hour. The high-temperature rapid heating temperature is 1050-1100°C and the high-temperature insulation time is 0.5-1.5min / mm. The temperature increase rate from the low-temperature preheating to the medium-temperature preheating does not exceed 100°C / hour, and the temperature process from the medium-temperature preheating stage to the high-temperature rapid heating stage does not exceed 1 hour.

2. The method for forming a mold of a nuclear power tube plate according to claim 1, characterized in that: The tire mold forming method also includes the following steps: performing rough processing on the forging before heat treatment.

3. The method for forming a mold of a nuclear power tube plate according to claim 2, characterized in that: After the forgings are heat treated for performance, the following steps are performed: Physical and chemical testing is performed.

4. The method for forming a mold of a nuclear power tube plate according to claim 1, characterized in that: The inclinations of the outer ring mold and the upper pad are both 3 degrees to 8 degrees, and the inclination is the angle between the inner side wall of the outer ring mold or the side wall of the upper pad and the vertical direction.

5. The method for forming a mold of a nuclear power tube plate according to claim 1, characterized in that: The tire mold forming method further comprises the following step: machining the forging.

6. The method for forming a mold of a nuclear power tube plate according to claim 5, characterized in that: The steps of the tire mold forming method also include the following steps: performing finished product inspection on the machined forging, wherein the finished product inspection adopts liquid penetration monitoring and overall ultrasonic inspection.

7. The method for forming a mold of a nuclear power tube plate according to any one of claims 1 to 6, characterized in that: The upsetting and drawing forging of the metal ingot into a blank is carried out in three steps. In the first step, the metal ingot is drawn, chamfered, and hot cut; in the second step, the blank is upset and drawn with a large deformation amount to break the grains; in the third step, the second upsetting and drawing is carried out to further refine the grains.

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