A forming method for large-sized thin-walled cylinders

Abstract

The present invention discloses a forming method for a large-sized thin-walled cylinder, belonging to the technical field of processing thin-walled cylinder-shaped parts; the tooling shaft adopted in the present invention includes an integrally formed cylinder section, and end plates are hermetically arranged at both ends of the cylinder section; the difference between the design of the present invention and the traditional structural design is that the cylinder tooling shaft structure is adopted to realize synchronous outward expansion. Through the design of the tooling shaft with a thin-walled cylinder, the entire structure can be synchronously expanded outward. According to the corresponding expansion coefficient, the approximate water pressure required can be calculated. Through the water pressure, the contact area between the thin-walled structure of the cylinder and the inner side wall of the thin-walled cylinder sample is larger and more complete, resulting in a better support effect. Especially during processing, the overall support force is evenly distributed, and it is not easy to have missed parts, thereby further ensuring the processing accuracy of the thin-walled cylinder-shaped parts of the nuclear pump and solving the processing problems of the current thin-walled cylinder-shaped structural parts of the nuclear pump.

Description

Technical Field

[0001] The present invention relates to a forming method for a large-sized thin-walled cylinder, belonging to the technical field of processing thin-walled cylinder parts. Background Art

[0002] The nuclear main pump is one of the most difficult-to-manufacture equipment in nuclear power technology, and the thin-walled cylinder is a key component for the nuclear main pump. The nuclear main pump includes a stator thin-walled cylinder and a rotor thin-walled cylinder. The stator thin-walled cylinder is used to protect the stator winding and insulation, and the rotor thin-walled cylinder is used to isolate the rotor copper bar from the system. Due to the different installation positions and assembly structures of the two thin-walled cylinders, the assembly and processing of the rotor thin-walled cylinder are relatively mature. Therefore, this thin-walled cylinder forming method is only applicable to the stator thin-walled cylinder. The conventional technical route for preparing the stator thin-walled cylinder is to form it by a spinning integrated process. Generally, the outer diameter of conventional thin-walled cylinder products is below Φ200mm, and the wall thickness varies from 0.4 to 0.5mm. Its diameter-thickness ratio (which is related to the stability of spinning forming) is generally less than 500, and the spinning forming difficulty is relatively controllable.

[0003] The outer diameter of the large-sized thin-walled cylinder is much higher than 200mm of the conventional thin-walled cylinder, and the wall thickness is close to that of the conventional thin-walled cylinder. As the diameter of the thin-walled cylinder increases, its diameter-thickness ratio continuously increases, the stability of the pipe material drops sharply, and the spinning forming difficulty increases exponentially. It is understood that there is currently no spinning process for such large-sized thin-walled cylinders in China. At the same time, due to the increase in size, the new equipment and tooling required for the spinning process bring high risks and high costs to the processing and manufacturing of this project's thin-walled cylinders.

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

[0005] The invention objective of the present invention is: aiming at the above problems, to provide a forming method for a large-sized thin-walled cylinder, which can effectively provide full-region support for the nuclear pump thin-walled cylinder parts, can further improve the outer wall processing accuracy of the overall thin-walled cylinder sample, and thus further ensure the product quality of the nuclear pump.

[0006] The technical solution adopted by the present invention is as follows:

[0007] A forming method for a large-sized thin-walled cylinder includes the following steps:

[0008] S1, prepare a thin-walled cylinder sample, and select a tooling shaft with a matching size according to the thin-walled cylinder sample;

[0009] S2. Fill the selected tooling shaft with the specified water pressure as required to expand the outer wall of the tooling shaft outward. After expansion, maintain the water pressure inside the tooling shaft and machine the outer diameter of the tooling shaft so that the outer diameter of the tooling shaft matches the inner diameter of the thin-walled cylinder sample.

[0010] S3. After the machining of the tooling shaft is completed, remove the water pressure inside the tooling shaft to make the inside of the tooling shaft in a pressureless state, and then slip on the thin-walled cylinder sample.

[0011] S4. After the thin-walled cylinder sample is sleeved on the tooling shaft, continue to add water pressure to the tooling shaft and fill in the corresponding water pressure as required to expand the tooling shaft, thereby realizing the assembly between the thin-walled cylinder sample and the tooling shaft.

[0012] Further, in step S4, when the inner diameter of the thin-walled cylinder sample needs to be made circular, after the inner wall of the thin-walled cylinder sample is formed after the expansion of the tooling shaft, the pressure is relieved.

[0013] Further, in step S4, when the outer wall of the thin-walled cylinder sample needs to be machined, the tooling shaft expands to the specified condition and then maintains the water pressure inside the tooling shaft, and machine the outer wall of the thin-walled cylinder sample. After machining, relieve the pressure and remove the formed part of the thin-walled cylinder sample.

[0014] Further, 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 reaches the same effect.

[0015] Further, in step S2, before filling the water pressure, obtain the dimensions of the inner diameter of the thin-walled cylinder sample and the outer diameter of the tooling shaft, monitor the outer diameter dimension of the tooling shaft when filling the water pressure, and stop filling the water pressure when the dimension is greater than the inner diameter dimension of the thin-walled cylinder sample.

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

[0017] Further, the tooling shaft includes an integrally formed cylinder section, and end plates are hermetically arranged at both ends of the cylinder section.

[0018] Further, an inlet for filling water pressure is provided on the end plate at any one end.

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

[0020] A method for forming a large-sized thin-walled cylinder of the present invention is different from the traditional structural design in that a cylinder tooling shaft structure is adopted to achieve synchronous outward expansion. Through the design of the tooling shaft of the thin-walled cylinder, the entire structure can be expanded outward synchronously. According to the corresponding expansion coefficient, the approximate required water pressure can be calculated. Through the water pressure, the contact area between the tooling shaft cylinder and the inner side wall of the thin-walled cylinder sample is larger and more complete, so that the supporting effect is better. Especially during processing, the overall supporting force is uniform and it is not easy to miss parts, thereby further ensuring the processing accuracy of the nuclear pump thin-walled cylinder-shaped parts and solving the processing problems of the current nuclear pump thin-walled cylinder-shaped structural parts. Brief Description of the Drawings

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

[0022] Figure 1 is a schematic structural diagram of the thin-walled cylinder sample of the present invention before being sleeved on the tooling shaft;

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

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

[0025] Figure 4 is a schematic structural diagram of the tooling shaft after assembling and expanding the thin-walled cylinder sample of the present invention.

[0026] Reference numerals in the drawings: 1 - thin-walled cylinder sample, 2 - tooling shaft. Detailed Description of the Invention

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

[0028] Any feature disclosed in this specification, unless specifically stated, can be replaced by other equivalent or similar-purpose alternative features. That is, unless specifically stated, each feature is only an example of a series of equivalent or similar features.

[0029] Embodiment

[0030] A method for forming a large-sized thin-walled cylinder, as Figures 1 to 4 shown, includes the following steps:

[0031] S1, prepare the thin-walled cylinder sample 1, and select the tooling shaft 2 with a matching size according to the thin-walled cylinder sample 1;

[0032] S2, fill the selected tooling shaft 2 with a specified water pressure as required, causing the outer wall of the tooling shaft 2 to expand outwards. After the expansion, maintain the water pressure inside the tooling shaft 2 and machine 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 sample 1;

[0033] S3, after the machining of the tooling shaft 2 is completed, remove the water pressure inside the tooling shaft 2 to make the inside of the tooling shaft 2 in a non-pressurized state, and then slip on the thin-walled cylinder sample 1;

[0034] S4, after the thin-walled cylinder sample 1 is sleeved on the tooling shaft 2, continue to add water pressure to the inside of the tooling shaft 2 and fill in the corresponding water pressure according to the requirements to cause the tooling shaft 2 to expand, thereby realizing the assembly between the thin-walled cylinder sample 1 and the tooling shaft 2.

[0035] In this embodiment, different from the traditional structure, the clamping method adopted in this design is different from the traditional technology. What this application adopts is an integral cylindrical structure. With the help of the balanced effect of water pressure, it can effectively provide a balanced outward expansion force. The main reason for not using other media is mainly that water is relatively easier to control, the relevant parameters are easier to obtain, the water pressure control effect provided is relatively better than others, there is no need to consider the water pressure detection in the cavity, and by means of this method, it further ensures that the force provided to the sample is more uniform and comprehensive, which is more conducive to the machining of the thin-walled cylinder sample 1 and ensures that the machining of each detail can be fully supported.

[0036] On the basis of the above specific design, in step S4, when the inner diameter of the thin-walled cylinder sample 1 needs to be made round, after the tooling shaft 2 expands and the inner wall of the thin-walled cylinder sample 1 is formed, the pressure is relieved.

[0037] In terms of the specific function, it is more for the machining of the outer wall of the thin-walled cylinder sample 1. As a specific design, in step S4, when the outer wall of the thin-walled cylinder sample 1 needs to be machined, the tooling shaft 2 expands to a specified condition and then maintains the water pressure inside the tooling shaft 2, and machine the outer wall of the thin-walled cylinder sample 1. After the machining is completed, relieve the pressure and remove the formed part of the thin-walled cylinder sample 1.

[0038] In the above specific structural design, in step S4, the water pressure adopted is matched with the water pressure in step S2 so that the expansion amount of the tooling shaft 2 reaches the same effect. Theoretically speaking, the water pressure in this step S2 and step S4 is the same, but based on actual applications, the water pressure rate in step S4 is greater than the water pressure in step S2. For example, the extra margin is 1 / 10 - 1 / 15 of the water pressure. The main purpose is to ensure the fitting effect of the tooling shaft 2 on the thin-walled cylinder sample 1 to ensure the supporting force.

[0039] Based on the design of the above specific embodiments, a more specific design is as follows. 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 measured. During the filling of water pressure, the outer diameter of the tooling shaft 2 is monitored. When the size is greater than the inner diameter size of the thin-walled cylinder sample 1, the filling of water pressure is stopped. This method is to provide machining allowance and maintain the smoothness of the entire outer surface of the tooling shaft 2 through machining.

[0040] A more specific design is that in step S2, after machining the outer wall of the tooling shaft 2, the outer diameter of the tooling shaft 2 under the condition of maintaining water pressure matches the inner diameter of the thin-walled sample.

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

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

[0043] In terms of material use, the cylindrical section of the tooling shaft 2 is made of thin-walled stainless steel material and is welded and sealed with the short plate.

[0044] In the above operation, first expand the tooling shaft 2, then perform machining after expansion, and finally clamp and machine the sample. The difference between this method and the traditional structure is that it can fully ensure the consistency of the effects before and after filling with water pressure, ensure the clamping effect, and guarantee the machining accuracy.

[0045] In summary, a method for forming a large-size thin-walled cylinder according to the present invention is different from the traditional structural design in that it adopts a cylindrical tooling shaft structure to achieve synchronous outward expansion. Through the design of the tooling shaft with a thin-walled cylinder, the entire structure can be synchronously expanded outward. According to the corresponding expansion coefficient, the approximate required water pressure can be calculated. Through the water pressure, the contact area between the thin-walled cylinder structure and the inner side wall of the thin-walled cylinder sample is larger and more complete, resulting in a better support effect. Especially during machining, the overall support force is evenly distributed, and it is not easy to miss any parts, thereby further ensuring the machining accuracy of the nuclear pump thin-walled cylinder-shaped parts and solving the machining problems of the current nuclear pump thin-walled cylinder-shaped structural parts.

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

Claims

1. A forming method for a large-sized thin-walled cylinder, characterized in that: It includes the following steps: S1. Prepare a thin-walled cylinder sample and select a tooling shaft with a matching size according to the thin-walled cylinder sample. S2. Before filling the selected tooling shaft with water pressure, obtain the inner diameter of the thin-walled cylinder sample and the outer diameter of the tooling shaft. Monitor the outer diameter of the tooling shaft when filling with water pressure. Stop filling with water pressure when the size is greater than the inner diameter of the thin-walled cylinder sample. Fill the selected tooling shaft with the specified water pressure as required to expand the outer wall of the tooling shaft. After expansion, maintain the water pressure inside the tooling shaft and machine the outer diameter of the tooling shaft to match the inner diameter of the thin-walled cylinder sample. After machining the outer wall of the tooling shaft, the outer diameter of the tooling shaft under the condition of maintaining water pressure matches the inner diameter of the thin-walled sample. S4. After the machining of the tooling shaft is completed, relieve the water pressure inside the tooling shaft to make the inside of the tooling shaft in a non-pressure state, and then sleeved with the thin-walled cylinder sample. S5. After the thin-walled cylinder sample is sleeved on the tooling shaft, continue to add water pressure to the tooling shaft and fill it with the corresponding water pressure as required to expand the tooling shaft, so as to realize the assembly between the thin-walled cylinder sample and the tooling shaft. The water pressure used is matched with the water pressure in step S2 to make the expansion amount of the tooling shaft reach the same effect, and make the water pressure greater than the water pressure in step S2, and the extra margin is 1 / 10 - 1 / 15 of the water pressure. The tooling shaft includes an integrally formed cylinder section, the cylinder section is made of thin-walled stainless steel material, and end plates are hermetically arranged at both ends of the cylinder section. An inlet for filling water pressure is arranged on the end plate at any one end. In step S4, when it is necessary to make the inner diameter of the thin-walled cylinder sample round, relieve the pressure after the inner wall of the thin-walled cylinder sample is formed after the tooling shaft expands; or, in step S4, when it is necessary to machine the outer wall of the thin-walled cylinder sample, maintain the water pressure inside the tooling shaft after the tooling shaft expands to the specified condition, and machine the outer wall of the thin-walled cylinder sample. After machining is completed, relieve the pressure and remove the formed part of the thin-walled cylinder sample.

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