Large-size thin-walled cylinder forming method

Abstract

The invention discloses a large-size thin-walled cylinder forming method, and belongs to the technical field of thin-walled cylinder part machining. The tool shaft comprises an integrally-formed cylinder section, and end plates are arranged at the two ends of the cylinder section in a sealed mode. Different from a traditional structural design in design, a barrel tool shaft structure is adopted to achieve synchronous outward expansion, the whole structure can conduct synchronous outward expansion through the barrel thin-wall tool shaft design, and the roughly needed water pressure can be calculated according to the corresponding expansion coefficient; through the water pressure, the contact area of the cylinder thin-wall structure and the inner side wall of the thin-wall cylinder sample piece is larger and more complete, the supporting effect is better, particularly, during machining, overall supporting stress is uniform, and missing parts are not prone to occurring, so that the machining precision of the nuclear pump thin-wall cylindrical piece is further guaranteed, and the machining problem of an existing nuclear pump thin-wall cylindrical structural piece is solved.

Description

Technical Field

[0001] The invention relates to a large-size thin-walled tube forming method, belonging to the technical field of thin-walled tube-shaped parts processing. Background Art

[0002] The nuclear main pump is one of the most difficult equipment to manufacture in nuclear power technology, and the thin-walled cylinder is a key component for the nuclear main pump. The nuclear main pump contains a stator thin-walled cylinder and a rotor thin-walled cylinder, of which the stator thin-walled cylinder is used to protect the winding and insulation of the stator, and the rotor thin-walled cylinder is used to isolate the rotor copper bars from the system. Due to the different installation positions and assembly structures of the two thin-walled cylinders, the assembly processing of the rotor thin-walled cylinder is relatively mature, so this thin-walled cylinder forming method is only for the stator thin-walled cylinder. The conventional technical route for the preparation of stator thin-walled cylinders is spinning integrated process molding, and the outer diameter size of conventional thin-walled cylinder products is generally less than Φ200mm, with a wall thickness ranging from 0.4 to 0.5mm, and its diameter-to-thickness ratio (related to the stability of spinning molding) is generally less than 500, and the difficulty of spinning molding is relatively controllable.

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

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

[0005] The purpose of the present invention is to provide a large-size thin-walled cylinder forming method to address the above-mentioned problems. The method can effectively provide full-area support for the thin-walled cylindrical parts of nuclear pumps, and can further improve the outer wall processing accuracy of the overall thin-walled cylinder sample, thereby further ensuring the product quality of the nuclear pump.

[0006] The technical solution adopted by the present invention is as follows: A large-size thin-walled tube forming method comprises the following steps: S1, preparing a thin-walled tube sample, and selecting a tooling shaft with a matching size according to the thin-walled tube sample; S2, filling the selected tooling shaft with a specified water pressure as required, so that the outer wall of the tooling shaft expands outwards, and after expansion, maintaining the water pressure inside the tooling shaft, processing 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; 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 pressure-free state, and then the thin-walled cylinder sample is inserted; S4, after the thin-walled tube sample is mounted on the tooling shaft, water pressure is continued to be added to the tooling shaft, and the corresponding water pressure is filled in as required to expand the tooling shaft, thereby achieving assembly between the thin-walled tube sample and the tooling shaft.

[0007] Furthermore, in step S4, when the inner diameter of the thin-walled tube sample needs to be a perfect circle, the pressure is released after the tooling shaft is expanded and the inner wall of the thin-walled tube sample is formed.

[0008] Furthermore, in step S4, when the outer wall of the thin-walled tube sample needs to be processed, the tooling shaft expands to a specified state and maintains the water pressure inside the tooling shaft, and the outer wall of the thin-walled tube sample is processed. After the processing is completed, the pressure is released and the molded part of the thin-walled tube sample is removed.

[0009] Furthermore, in step S4, the water pressure used matches the water pressure in step S2 so that the expansion amount of the tooling shaft achieves the same effect.

[0010] Furthermore, in step S2, before filling with water pressure, the inner diameter of the thin-walled tube sample and the outer diameter of the tooling shaft are obtained, and the outer diameter of the tooling shaft is monitored when filling with water pressure. When the size is larger than the inner diameter of the thin-walled tube sample, the filling with water pressure is stopped.

[0011] Furthermore, in step S2, after the outer wall of the tooling shaft is processed, the outer diameter of the tooling shaft matches the inner diameter of the thin-walled sample while maintaining the water pressure.

[0012] Furthermore, the tooling shaft comprises an integrally formed barrel section, and both ends of the barrel section are sealed with end plates.

[0013] Furthermore, the end plate at any end is provided with a water inlet for charging water pressure.

[0014] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: A large-size thin-walled cylinder forming method of the present invention is different from the traditional structural design in that it adopts a cylinder tooling shaft structure to achieve synchronous outward expansion. The tooling shaft design of the thin wall of the cylinder allows the entire structure to expand outward synchronously. The required water pressure can be calculated according to the corresponding expansion coefficient. The contact area between the tooling shaft cylinder and the inner wall of the thin-walled cylinder sample is made larger and more complete through the water pressure, so that the supporting effect is better, especially during processing, the overall support is evenly stressed and it is not easy 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 the thin-walled cylindrical structural parts of the nuclear pump. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The present invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 It is a structural schematic diagram of the thin-walled tube sample of the present invention being mounted in front of the tooling shaft; Figure 2 It is a schematic diagram of the structure of the tooling shaft after expansion of the present invention; Figure 3 It is a schematic diagram of the structure of the tooling shaft of the present invention after assembling the thin-walled cylinder sample; Figure 4 It is a schematic diagram of the structure of the tooling shaft of the present invention after the thin-walled cylinder sample is assembled and expanded.

[0016] Markings in the figure: 1-thin-walled cylinder sample, 2-tooling shaft. DETAILED DESCRIPTION

[0017] All features disclosed in this specification, or steps in all methods or processes disclosed, except mutually exclusive features and / or steps, can be combined in any manner.

[0018] Any feature disclosed in this specification, unless otherwise stated, can be replaced by other equivalent or alternative features with similar purposes. That is, unless otherwise stated, each feature is only an example of a series of equivalent or similar features.

[0019] Example A method for forming a large-size thin-walled tube, such as Figures 1 to 4 As shown, the following steps are included: S1, preparing a thin-walled tube sample 1, and selecting a tooling shaft 2 with a size matching the thin-walled tube sample 1; S2, filling the selected tooling shaft 2 with a specified water pressure as required, so that the outer wall of the tooling shaft 2 expands outward, and after expansion, maintaining the water pressure inside the tooling shaft 2, processing 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 tube sample 1; S3, after the processing of the tooling shaft 2 is completed, the water pressure inside the tooling shaft 2 is removed, so that the inside of the tooling shaft 2 is in a pressure-free state, and then the thin-walled cylinder sample 1 is inserted; S4, after the thin-walled tube sample 1 is mounted on the tooling shaft 2, water pressure is continued to be added to the tooling shaft 2, and corresponding water pressure is filled in as required to expand the tooling shaft 2, thereby achieving assembly between the thin-walled tube sample 1 and the tooling shaft 2.

[0020] In this embodiment, unlike the traditional structure, the clamping method adopted in this design is different from the traditional technology in that the present application adopts an overall cylindrical structure, which can effectively provide a balanced outward expansion force by means of the balancing effect of water pressure. The reason for not using other media is mainly because water is relatively easier to control, and the relevant parameters are easier to obtain. The water pressure control effect provided is better than others, and there is no need to consider the water pressure detection in the cavity. In addition, 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 tube sample 1, ensuring that the processing of each detail can be fully supported.

[0021] Based on the above specific design, in step S4, when the inner diameter of the thin-walled tube sample 1 needs to be a perfect circle, the tooling shaft 2 is expanded and the inner wall of the thin-walled tube sample 1 is formed and then the pressure is released.

[0022] In terms of specific function, it is more for processing the outer wall of the thin-walled tube sample 1. As a specific design, in the step S4, when the outer wall of the thin-walled tube sample 1 needs to be processed, the tooling shaft 2 expands to the specified situation and maintains the water pressure inside the tooling shaft 2, and processes the outer wall of the thin-walled tube sample 1. After the processing is completed, the pressure is released to remove the molded part of the thin-walled tube sample 1.

[0023] In the above specific structural design, in step S4, the water pressure used matches the water pressure in step S2, so that the expansion amount of the tooling shaft 2 achieves the same effect. Theoretically, the water pressure of step S2 and step S4 is the same, but based on practical application, the water pressure ratio of step S4 is greater than the water pressure of step S2, for example, the extra margin is 1 / 10-1 / 15 of the water pressure, the main purpose of which is to ensure the fitting effect of the tooling shaft 2 on the thin-walled tube sample 1 to ensure the supporting force.

[0024] Based on the design of the above specific implementation, a more specific design is that in step S2, before the water pressure is charged, the inner diameter of the thin-walled tube sample 1 and the outer diameter of the tooling shaft 2 are obtained, and the outer diameter of the tooling shaft 2 is monitored when the water pressure is charged, and the water pressure is stopped when the size is larger than the inner diameter of the thin-walled tube sample 1. This method is to provide a processing allowance and maintain the smoothness of the outer side of the entire tooling shaft 2 through processing.

[0025] In a more specific design, in step S2, after the outer wall of the tooling shaft 2 is processed, the outer diameter of the tooling shaft 2 matches the inner diameter of the thin-walled sample while maintaining water pressure.

[0026] Based on the above specific structural design, more specifically, the tooling shaft 2 includes an integrally formed barrel section, and both ends of the barrel section are sealed with end plates.

[0027] More specifically, the end plate at any end is provided with a water inlet for charging water pressure. In terms of structural design, the end plate at the other end may be provided with a water outlet to ensure the effect of water pressure control.

[0028] In terms of material usage, the barrel section of the tooling shaft 2 is made of thin-walled stainless steel material and is welded and sealed with the short plate.

[0029] In the above operation, the tooling shaft 2 is expanded first, 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 effects after front and rear water pressure filling, ensure the clamping effect, and ensure the processing accuracy.

[0030] To sum up, a large-size thin-walled cylinder forming method of the present invention is different from the traditional structural design in that it adopts a cylinder tooling shaft structure to achieve synchronous outward expansion. The tooling shaft design of the thin wall of the cylinder allows the entire structure to expand outward synchronously. The required water pressure can be calculated according to the corresponding expansion coefficient. The water pressure makes the contact area between the thin-walled structure of the cylinder and the inner wall of the thin-walled cylinder sample larger and more complete, so that the supporting effect is better, especially during processing, the overall support is evenly stressed and it is not easy 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 the thin-walled cylindrical structural parts of the nuclear pump.

[0031] The present invention is not limited to the above-mentioned specific embodiments, but extends to any new features or any new combination disclosed in this specification, as well as any new method or process steps or any new combination disclosed.

Claims

1. A method for forming a large-size thin-walled tube, characterized in that: The following steps are involved: S1, preparing a thin-walled tube sample, and selecting a tooling shaft with a matching size according to the thin-walled tube sample; S2, filling the selected tooling shaft with a specified water pressure as required, so that the outer wall of the tooling shaft expands outwards, and after expansion, maintaining the water pressure inside the tooling shaft, processing 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; 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 pressure-free state, and then the thin-walled cylinder sample is inserted; S4, after the thin-walled tube sample is mounted on the tooling shaft, water pressure is continued to be added to the tooling shaft, and the corresponding water pressure is filled in as required to expand the tooling shaft, thereby achieving assembly between the thin-walled tube sample and the tooling shaft.

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

3. A method for forming a large-size thin-walled tube as claimed in claim 1, characterized in that: In step S4, when the outer wall of the thin-walled tube sample needs to be processed, the tooling shaft expands to a specified state and maintains the water pressure inside the tooling shaft, and the outer wall of the thin-walled tube sample is processed. After the processing is completed, the pressure is released and the molded part of the thin-walled tube sample is removed.

4. A method for forming a large-size thin-walled tube as claimed in claim 1, characterized in that: In step S4, the water pressure used matches the water pressure in step S2 so that the expansion amount of the tooling shaft reaches the same effect.

5. A large-size thin-walled tube forming method as claimed in claim 1, characterized in that: In step S2, before filling with water pressure, the inner diameter of the thin-walled tube sample and the outer diameter of the tooling shaft are obtained, and the outer diameter of the tooling shaft is monitored when filling with water pressure. When the size is larger than the inner diameter of the thin-walled tube sample, the filling with water pressure is stopped.

6. A method for forming a large-size thin-walled tube as claimed in claim 5, 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.

7. A method for forming a large-size thin-walled tube as claimed in claim 1, characterized in that: The tooling shaft comprises an integrally formed barrel section, and both ends of the barrel section are sealed with end plates.

8. A method for forming a large-size thin-walled tube as claimed in claim 7, characterized in that: The end plate at either end is provided with a water inlet for charging water pressure.

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