Method for forming large-size thin-walled cylinder

Abstract

A method for forming a large-size thin-walled cylinder, the method comprising the following steps: S1, preparing a thin-walled cylinder specimen (1), and selecting, on the basis of the thin-walled cylinder specimen (1), a tooling shaft (2) with dimensions matching those of the thin-walled cylinder sample (1); S2, filling the selected tooling shaft (2) with a specified water pressure according to requirements, so that the outer side wall of the tooling shaft (2) expands outward, and after expansion, maintaining the water pressure inside the tooling shaft (2), and machining the outer diameter of the tooling shaft (2), so that the outer diameter of the tooling shaft (2) matches the inner diameter of the thin-walled cylinder specimen (1); S3, after the machining of the tooling shaft (2) is completed, removing the water pressure inside the tooling shaft (2), so that the inside of the tooling shaft (2) is in a pressure-free state, and then sleeving the thin-walled cylinder specimen (1) on the tooling shaft; and S4, after the thin-walled cylinder specimen (1) is sleeved on the tooling shaft (2), continuing to apply a water pressure to the tooling shaft (2), and filling the tooling shaft (2) with a corresponding water pressure according to requirements to expand the tooling shaft (2), so as to realize the fitting between the thin-walled cylinder specimen (1) and the tooling shaft (2). By means of the water pressure, the tooling shaft (2) expands outward synchronously, such that the contact area between the tooling shaft (2) and the inner side wall of the thin-walled cylinder specimen (1) is larger, the support effect is better, the entire thin-walled cylinder specimen (1) is supported with a uniform force during machining, and no portion is prone to being left unsupported, thereby ensuring the processing accuracy of the thin-walled cylindrical component of a reactor coolant pump.

Description

A method for forming large-size thin-walled cylinders Technical Field

[0001] This invention relates to a method for forming large-size thin-walled cylinders, belonging to the field of thin-walled cylinder processing technology. Background Technology

[0002] The nuclear main pump is one of the most difficult pieces of equipment to manufacture in nuclear power technology, and thin-walled cylinders are key components used in it. The nuclear main pump contains stator and rotor thin-walled cylinders. The stator thin-walled cylinder protects the stator windings and insulation, while the rotor thin-walled cylinder isolates the rotor copper bars from the system. Due to the different installation positions and assembly structures of the two types of thin-walled cylinders, and the relatively mature assembly and processing of the rotor thin-walled cylinder, this thin-walled cylinder forming method only applies to the stator thin-walled cylinder. The conventional technical route for manufacturing stator thin-walled cylinders is a one-piece spinning process. The outer diameter of conventional thin-walled cylinder products is generally below Φ200mm, with a wall thickness ranging from 0.4 to 0.5mm. Their diameter-to-thickness ratio (which is crucial for the stability of spinning) is generally less than 500, making spinning relatively controllable.

[0003] The outer diameter of the large-sized thin-walled cylinder is much larger than the 200mm of a conventional thin-walled cylinder, while its wall thickness is similar. As the diameter of the thin-walled cylinder increases, its diameter-to-thickness ratio also increases, leading to a sharp decrease in the stability of the pipe and a significant increase in the difficulty of spin forming. It is understood that there is currently no domestic process for spin forming such large-sized thin-walled cylinders. Furthermore, the increased size necessitates new equipment and tooling for the spin forming process, bringing high risks and high costs to the manufacturing of this thin-walled cylinder project.

[0004] The published document CN110561270A discloses an auxiliary tooling for preventing the honing deformation of the inner hole of a large-diameter thin-walled part (application number: 201910800447.X). Its main structure uses an inflatable ring as a support to process the inner hole of the product. There are gaps between the inflatable rings, and this part of the product structure cannot meet the processing accuracy requirements of the nuclear pump during processing. Summary of the Invention

[0005] The purpose of this invention is to provide a method for forming large-size thin-walled cylinders, which can effectively provide full-area support for the thin-walled cylindrical parts of nuclear pumps, further improve the outer wall processing accuracy of the overall thin-walled cylinder sample, and thus further ensure the product quality of nuclear pumps.

[0006] The technical solution adopted in this invention is as follows:

[0007] A method for forming large-size thin-walled cylinders includes the following steps:

[0008] S1. Prepare a thin-walled cylinder sample and select a tooling shaft with matching dimensions based on the thin-walled cylinder sample.

[0009] S2, fill the selected tooling shaft with the specified water pressure as required, so that the outer wall of the tooling shaft expands outward. After expansion, maintain the water pressure inside the tooling shaft and process the outer diameter of the tooling shaft so that the outer diameter of the tooling shaft matches the inner diameter of the thin-walled cylindrical sample.

[0010] S3. After the tooling shaft is processed, the water pressure inside the tooling shaft is removed, so that the inside of the tooling shaft is in a pressureless state, and then the thin-walled cylindrical sample is inserted.

[0011] S4. After the thin-walled cylindrical sample is mounted on the tooling shaft, water pressure is continued to be applied to the tooling shaft. The tooling shaft is expanded by filling it with the appropriate water pressure as required, thereby realizing the assembly between the thin-walled cylindrical sample and the tooling shaft.

[0012] Furthermore, in step S4, when the inner diameter of the thin-walled cylindrical sample needs to be perfectly round, the pressure is released after the inner wall of the thin-walled cylindrical sample is formed after the tooling shaft expands.

[0013] Furthermore, in step S4, when it is necessary to process the outer wall of the thin-walled cylindrical sample, the tooling shaft expands to a specified level and maintains the water pressure inside the tooling shaft, and processes the outer wall of the thin-walled cylindrical sample. After processing, the pressure is released and the molded part of the thin-walled cylindrical sample is removed.

[0014] Furthermore, in step S4, the water pressure used is matched with the water pressure in step S2 so that the expansion amount of the tooling shaft achieves the same effect.

[0015] Furthermore, in step S2, before filling with water pressure, the inner diameter of the thin-walled cylinder sample and the outer diameter of the tooling shaft are obtained. When filling with water pressure, the outer diameter of the tooling shaft is monitored. When the outer diameter is larger than the inner diameter of the thin-walled cylinder sample, the water pressure is stopped.

[0016] Furthermore, in step S2, after the outer wall of the tooling shaft is machined, the outer diameter of the tooling shaft matches the inner diameter of the thin-walled sample while maintaining water pressure.

[0017] Furthermore, the tooling shaft includes an integrally formed cylindrical section, and end plates are sealed at both ends of the cylindrical section.

[0018] Furthermore, the end plate at either end is provided with a water inlet for filling with water pressure.

[0019] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0020] This invention discloses a method for forming large-size thin-walled cylinders. Unlike traditional structural designs, this method employs a cylinder tooling shaft structure to achieve synchronous outward expansion. The tooling shaft design of the thin-walled cylinder allows the entire structure to expand synchronously outward. The approximate required water pressure can be calculated based on the corresponding expansion coefficient. The water pressure increases the contact area between the tooling shaft cylinder and the inner wall of the thin-walled cylinder sample, resulting in better support. In particular, the overall support is evenly stressed during processing, making it less likely to miss any parts. This further ensures the processing accuracy of the thin-walled cylindrical parts for nuclear pumps and solves the current processing problems of thin-walled cylindrical structural parts for nuclear pumps. Attached Figure Description

[0021] The present invention will be described by way of example and with reference to the accompanying drawings, wherein:

[0022] Figure 1 is a schematic diagram of the thin-walled cylindrical sample of the present invention mounted in front of the tooling shaft;

[0023] Figure 2 is a schematic diagram of the structure of the tooling shaft after expansion according to the present invention;

[0024] Figure 3 is a schematic diagram of the structure of the tooling shaft of the present invention after assembling the thin-walled cylindrical sample;

[0025] Figure 4 is a schematic diagram of the structure of the tooling shaft of the present invention after assembly and expansion of the thin-walled cylindrical sample.

[0026] Markings in the figure: 1-thin-walled cylindrical sample, 2-tooling shaft. Embodiments of the present invention

[0027] All features disclosed in this specification, or all steps in all disclosed methods or processes, may be combined in any way, except for mutually exclusive features and / or steps.

[0028] Any feature disclosed in this specification, unless otherwise stated, may be replaced by other equivalent or similar features. That is, unless otherwise stated, each feature is merely one example of a series of equivalent or similar features.

[0029] Example

[0030] A method for forming large-size thin-walled cylinders, as shown in Figures 1 to 4, includes the following steps:

[0031] S1. Prepare thin-walled cylinder sample 1 and select tooling shaft 2 with matching size according to thin-walled cylinder sample 1.

[0032] S2, fill the selected tooling shaft 2 with the specified water pressure as required, so that the outer wall of the tooling shaft 2 expands outward. After expansion, maintain the water pressure inside the tooling shaft 2 and process the outer diameter of the tooling shaft 2 so that the outer diameter of the tooling shaft 2 matches the inner diameter of the thin-walled cylindrical sample 1.

[0033] S3, After the tooling shaft 2 is processed, the water pressure inside the tooling shaft 2 is removed, so that the tooling shaft 2 is in a pressureless state, and then the thin-walled cylindrical sample 1 is inserted.

[0034] S4. After the thin-walled cylindrical sample 1 is mounted on the tooling shaft 2, water pressure is continued to be applied to the tooling shaft 2. According to the requirements, the corresponding water pressure is filled to make the tooling shaft 2 expand, thereby realizing the assembly between the thin-walled cylindrical sample 1 and the tooling shaft 2.

[0035] In this embodiment, unlike traditional structures, the clamping method used in this design differs from traditional techniques. This application employs an integral cylindrical structure, which effectively provides a balanced outward expansion force by utilizing the balancing effect of water pressure. The reason for not using other media is mainly because water is relatively easier to control, relevant parameters are easier to obtain, and the water pressure control effect provided is better than others. There is no need to consider water pressure detection within the cavity. Furthermore, this method further ensures that the force provided to the sample is more uniform and comprehensive, which is more conducive to the processing of the thin-walled cylindrical sample 1 and ensures that the processing of every detail can be fully supported.

[0036] Based on the above specific design, in step S4, when the inner diameter of the thin-walled cylindrical sample 1 needs to be perfectly round, the pressure is released after the inner wall of the thin-walled cylindrical sample 1 is formed after the tooling shaft 2 expands.

[0037] In terms of specific function, it is mainly for processing the outer wall of the thin-walled cylindrical sample 1. As a specific design, in step S4, when it is necessary to process the outer wall of the thin-walled cylindrical sample 1, the tooling shaft 2 expands to a specified condition and maintains the water pressure inside the tooling shaft 2, and processes the outer wall of the thin-walled cylindrical sample 1. After processing, the pressure is released and the molded part of the thin-walled cylindrical sample 1 is removed.

[0038] In the specific structural design described above, the water pressure used in step S4 is matched with the water pressure in step S2 to ensure that the expansion of the tooling shaft 2 achieves the same effect. Theoretically, the water pressure in steps S2 and S4 is the same, but for practical applications, the water pressure in step S4 is greater than that in step S2, for example, the extra margin is 1 / 10 to 1 / 15 of the water pressure. The main purpose is to ensure the fit of the tooling shaft 2 to the thin-walled cylindrical sample 1, so as to ensure the support force.

[0039] Based on the design of the above specific implementation method, a more specific design is implemented in step S2. Before filling with water pressure, the inner diameter of the thin-walled cylinder sample 1 and the outer diameter of the tooling shaft 2 are obtained. During water pressure filling, the outer diameter of the tooling shaft 2 is monitored, and water pressure filling is stopped when the outer diameter exceeds the inner diameter of the thin-walled cylinder sample 1. This method provides machining allowance by maintaining the smoothness of the entire outer surface of the tooling shaft 2 through machining.

[0040] In a more specific design, in step S2, after the outer wall of the tooling shaft 2 is machined, the outer diameter of the tooling shaft 2 matches the inner diameter of the thin-walled sample while maintaining water pressure.

[0041] Based on the above specific structural design, more specifically, the tooling shaft 2 includes an integrally formed cylindrical section, and end plates are sealed at both ends of the cylindrical section.

[0042] More specifically, one end plate is provided with a water inlet for pressurizing water. In terms of structural design, the other end plate can be provided with a water outlet to ensure effective water pressure control.

[0043] In terms of materials, the cylindrical section of tooling shaft 2 is made of thin-walled stainless steel and is welded and sealed to the end plate.

[0044] In the above operation, the tooling shaft 2 is first expanded, then processed, and finally clamped and processed. This method is different from the traditional structure in that it can fully ensure the consistency of the effect after water filling and pressure, ensure the clamping effect, and ensure the processing accuracy.

[0045] In summary, the large-size thin-walled cylinder forming method of the present invention differs from traditional structural designs in that it adopts a cylinder tooling shaft structure to achieve synchronous outward expansion. Through the tooling shaft design of the thin-walled cylinder, the entire structure can expand synchronously outward. According to the corresponding expansion coefficient, the approximate required water pressure can be calculated. The water pressure makes the contact area between the thin-walled cylinder structure and the inner wall of the thin-walled cylinder sample larger and more complete, resulting in better support. In particular, during processing, the overall support is evenly stressed, and it is less likely to miss any parts, thereby further ensuring the processing accuracy of the thin-walled cylindrical parts of the nuclear pump and solving the current processing problems of thin-walled cylindrical structural parts for nuclear pumps.

[0046] This invention is not limited to the specific embodiments described above. The invention extends to any new feature or combination disclosed in this specification, as well as any new method or process step or combination disclosed herein.

Claims

1. A method of forming a large-size thin-walled cylinder, characterized by: Includes the following steps: S1. Prepare a thin-walled cylinder sample and select a tooling shaft with matching dimensions based on the thin-walled cylinder sample. S2, fill the selected tooling shaft with the specified water pressure as required, so that the outer wall of the tooling shaft expands outward. After expansion, maintain the water pressure inside the tooling shaft and process the outer diameter of the tooling shaft so that the outer diameter of the tooling shaft matches the inner diameter of the thin-walled cylindrical sample. S3. After the tooling shaft is processed, the water pressure inside the tooling shaft is removed, so that the inside of the tooling shaft is in a pressureless state, and then the thin-walled cylindrical sample is inserted. S4. After the thin-walled cylindrical sample is mounted on the tooling shaft, water pressure is continued to be applied to the tooling shaft. The tooling shaft is expanded by filling it with the appropriate water pressure as required, thereby realizing the assembly between the thin-walled cylindrical sample and the tooling shaft.

2. The method for forming a large-size thin-walled cylinder as described in claim 1, characterized in that: In step S4, when the inner diameter of the thin-walled cylindrical sample needs to be perfectly round, the pressure is released after the inner wall of the thin-walled cylindrical sample is formed after the tooling shaft expands.

3. The method for forming a large-size thin-walled cylinder as described in claim 1, characterized in that: In step S4, when it is necessary to process the outer wall of the thin-walled cylindrical sample, the tooling shaft expands to a specified level and maintains the water pressure inside the tooling shaft, and processes the outer wall of the thin-walled cylindrical sample. After processing, the pressure is released and the molded part of the thin-walled cylindrical sample is removed.

4. The method for forming a large-size thin-walled cylinder as described in claim 1, characterized in that: In step S4, the water pressure used is matched with the water pressure in step S2 so that the expansion of the tooling shaft achieves the same effect.

5. The method for forming a large-size thin-walled cylinder as described in claim 1, characterized in that: The water pressure in step S4 is greater than or equal to the water pressure in step S2.

6. The method for forming a large-size thin-walled cylinder as described in claim 1, characterized in that: In step S2, before filling with water pressure, the inner diameter of the thin-walled cylinder sample and the outer diameter of the tooling shaft are obtained. When filling with water pressure, the outer diameter of the tooling shaft is monitored. When the outer diameter is larger than the inner diameter of the thin-walled cylinder sample, the water pressure is stopped.

7. The method for forming a large-size thin-walled cylinder as described in claim 6, characterized in that: In step S2, after the outer wall of the tooling shaft is machined, the outer diameter of the tooling shaft matches the inner diameter of the thin-walled sample while maintaining water pressure.

8. The method for forming a large-size thin-walled cylinder as described in claim 1, characterized in that: The tooling shaft includes an integrally formed cylindrical section, and end plates are sealed at both ends of the cylindrical section.

9. The method for forming a large-size thin-walled cylinder as described in claim 8, characterized in that: The end plate at either end is provided with an inlet for filling with water pressure.

10. The method for forming a large-size thin-walled cylinder as described in claim 8, characterized in that: The cylindrical section of the tooling shaft is made of thin-walled stainless steel and is welded and sealed to the end plate.

Images