Nuclear power low-pressure outer cylinder reverse deformation clamping tool
By combining high and low support pads and using a two-way limiting system of thrust pads and jacks, the problem of insufficient clamping rigidity of the low-pressure outer cylinder in nuclear power plants was solved, achieving efficient and high-precision machining results.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- DALIAN MARINE DIESEL
- Filing Date
- 2025-04-30
- Publication Date
- 2026-05-29
AI Technical Summary
The existing fixture for clamping the low-pressure outer cylinder of nuclear power plants lacks rigidity, making the workpiece prone to vibration during processing and resulting in poor clamping stability. This makes it difficult to meet the requirements of high-precision processing and cannot effectively counteract the deformation caused by the workpiece's own weight, leading to a large deviation between the processed surface and the theoretical design, and low processing efficiency.
The design employs a combination of high and low support pads, along with thrust pads and jacks to form a two-way limiting system. The reverse lifting force counteracts the deformation caused by its own weight, and the amount of deformation is monitored in real time by a dial indicator. The pressure plate system evenly distributes the clamping force, thereby improving the clamping rigidity and stability.
It significantly improves clamping rigidity and stability, reduces workpiece deformation, and increases machining efficiency and accuracy. Hole position accuracy reaches ±0.05mm, surface roughness Ra≤1.6μm, machining chatter is basically eliminated, and cutting parameters can be improved by 30%.
Smart Images
Figure CN224295284U_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of clamping technology for low-pressure outer cylinders in nuclear power plants, and specifically relates to a clamping fixture for anti-deformation of low-pressure outer cylinders in nuclear power plants. Background Technology
[0002] The low-pressure outer cylinder of a nuclear power plant, a key component of the unit, is composed of six half-cylinders. Each half is up to 12 meters long, 3-4 meters wide, and approximately 4 meters high. Its structure is hollow, housing the inner cylinder. However, the support plates at both ends are relatively thick, while the middle section is thin and hollow, resulting in a significant reduction in overall rigidity. Especially under its own weight, the deformation in the lower middle section can reach nearly 10 mm, severely impacting machining accuracy.
[0003] Traditional processing methods require precision machining at the assembly station, but the support platform at this station is located at both ends, up to 2.7 meters above the bottom surface, requiring support pads with a height of more than 2.7 meters and a span of more than 10 meters.
[0004] Existing clamping fixtures for low-pressure outer cylinders in nuclear power plants suffer from the following problems: First, the support system lacks rigidity, causing workpiece vibration during machining, necessitating small cutting depths and resulting in low machining efficiency. Second, the clamping stability is poor, making it difficult to meet high-precision machining requirements. Furthermore, existing clamping methods for low-pressure outer cylinders in nuclear power plants cannot effectively counteract workpiece deformation due to its own weight, leading to significant deviations between the machined surface and the theoretical design, requiring repeated adjustments and further extending the machining cycle. Therefore, a new type of clamping fixture is urgently needed that can improve clamping rigidity, compensate for deformation due to its own weight, and increase machining efficiency. Summary of the Invention
[0005] This invention addresses the problems of existing nuclear power plant low-pressure outer cylinder clamping fixtures, which fail to effectively counteract workpiece deformation due to its own weight, resulting in large deviations between the machined surface and the theoretical design; insufficient rigidity of the support system leads to workpiece vibration during machining, poor clamping stability, difficulty in meeting high-precision machining requirements, repeated adjustments, and low machining efficiency. The invention proposes a nuclear power plant low-pressure outer cylinder anti-deformation clamping fixture, comprising: a machine tool worktable; and a high support pad mounted on the machine tool worktable for supporting the two side plate surfaces of the low-pressure outer cylinder at the assembly station, with a height of 2m. -3m; a low support pad set on the machine tool worktable, used to support the low-pressure outer cylinder with its horizontal split surface facing downward in non-assembly stations, with a height of 50mm-800mm; a thrust pad, fixed to one end of the non-assembly station, used to limit the horizontal displacement of the low-pressure outer cylinder; a jack, set at the other end of the non-assembly station, used to apply a reverse lifting force to the low-pressure outer cylinder; a dial indicator, installed on the reference surface on the side of the jack, used to monitor the workpiece deformation in real time; and a pressure plate assembly, used to press and fix the low-pressure outer cylinder to the leveling pad on the machine tool worktable.
[0006] The contact surfaces of both the high support pad and the low support pad are provided with anti-slip textures. The thrust pad is a rigid positioning block. The jack is a hydraulic or mechanical adjustable stroke lifting device. The dial indicator has an accuracy of >0.01mm.
[0007] According to the above-described nuclear power low-pressure outer cylinder anti-deformation clamping fixture, the top of the high support pad is provided with a rubber buffer layer, and the bottom is connected to the assembly station machine tool worktable by bolts.
[0008] According to the above-described nuclear power low-pressure outer cylinder anti-deformation clamping fixture, the surface of the short support pad is ground, and the flatness error is ≤0.02mm.
[0009] According to the above-described nuclear power low-pressure outer cylinder anti-deformation clamping fixture, the thrust pad has a threaded hole on its side and is fixed to the machine tool table by bolts.
[0010] According to the above-described nuclear power low-pressure outer cylinder anti-deformation clamping fixture, the jack is equipped with a digital pressure gauge, and the lifting speed is controllable.
[0011] According to the above-described nuclear power low-pressure outer cylinder anti-deformation clamping fixture, the dial indicator is fixed with a magnetic base and has a measuring range ≥10mm.
[0012] According to the above-described nuclear power low-pressure outer cylinder anti-deformation clamping fixture, the pressure plate assembly includes multiple pressure plates with a spacing of ≤1 meter and a serrated structure on the pressing surface.
[0013] According to the above-described nuclear power low-pressure outer cylinder anti-deformation clamping fixture, the high support pad and the low support pad are made of high-strength cast iron.
[0014] According to the above-described nuclear power low-pressure outer cylinder anti-deformation clamping fixture, a positioning pin is provided between the leveling pad and the machine tool worktable, with a positioning accuracy of ±0.1mm.
[0015] According to the above-described nuclear power low-pressure outer cylinder anti-deformation clamping fixture, the end of the jack rod is provided with a polyurethane buffer pad to prevent damage to the workpiece surface.
[0016] The beneficial effects of the present invention are as follows:
[0017] 1. This fixture significantly improves the clamping performance of the low-pressure outer cylinder of nuclear power plants through structural innovation. The combination design of high support pads and low support pads adapts to the clamping requirements of assembly and non-assembly stations respectively, ensuring the accuracy of datum surface machining and deformation measurement.
[0018] 2. The thrust pad and jack of this invention form a two-way limiting system. The former fixes the horizontal displacement of the workpiece, while the latter accurately counteracts its own weight deformation through reverse lifting force. Combined with a dial indicator to monitor the deformation in real time, the workpiece is restored to a zero-deformation state. The pressure plate system evenly distributes the clamping force, further enhancing the clamping rigidity.
[0019] 3. The tooling of this invention improves the clamping stability of the workpiece in non-assembly stations by approximately 40%, essentially eliminates machining vibration, and can improve cutting parameters by 30%. Simultaneously, the low support pad reduces the clamping height difference, simplifying the operation process.
[0020] Tests show that after adopting this tooling, the maximum deformation of the workpiece is reduced from 9.8mm to 0.2mm, the hole position accuracy reaches ±0.05mm, and the surface roughness Ra≤1.6μm, effectively solving the technical problem of insufficient clamping rigidity of large thin-walled parts. Attached Figure Description
[0021] Figure 1 This is a schematic diagram of the assembly and use station of the nuclear power low-pressure outer cylinder according to the present invention, which describes a method for anti-deformation clamping of the outer cylinder of a nuclear power plant.
[0022] Figure 2 This is a schematic diagram of the anti-deformation workstation of the low-pressure outer cylinder of a nuclear power plant, which is a method for anti-deformation clamping of the low-pressure outer cylinder of a nuclear power plant according to the present invention.
[0023] In the diagram: 1-Low-pressure outer cylinder, 2-Equal height pad, 3-Support pad, 4-Thrust pad, 5-Jack, 6-Dial indicator, 200-Machine tool worktable. Detailed Implementation
[0024] Preferred Implementation
[0025] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.
[0026] like Figure 1 , Figure 2As shown: In this embodiment, a nuclear power low-pressure outer cylinder anti-deformation clamping fixture includes: a machine tool worktable 200; a high support pad 2 set on the machine tool worktable 200 for supporting the two side table surfaces of the low-pressure outer cylinder 1 at the assembly station, with a height of 2m-3m; a low support pad 3 set on the machine tool worktable 200 for supporting the low-pressure outer cylinder 1 with its horizontal split surface facing downward at the non-assembly station, with a height of 50mm-800mm; a thrust pad 4 fixed at one end of the non-assembly station for limiting the horizontal displacement of the low-pressure outer cylinder 1; a jack 5 set at the other end of the non-assembly station for applying a reverse lifting force to the low-pressure outer cylinder 1; a dial indicator 6 installed on the reference surface on the side of the jack for real-time monitoring of the workpiece deformation; and a pressure plate assembly for pressing and fixing the low-pressure outer cylinder 1 onto the leveling pad of the machine tool worktable 200.
[0027] The contact surfaces of the high support pad 2 and the low support pad 3 are both provided with anti-slip textures. The thrust pad 4 is a rigid positioning block. The jack 5 is a hydraulic or mechanical adjustable stroke lifting device. The dial indicator 6 has an accuracy > 0.01 mm.
[0028] The top of the high support pad 2 is equipped with a rubber buffer layer, and the bottom is connected to the assembly station machine tool worktable 200 by bolts.
[0029] The surface of the low support pad 3 is ground, and the flatness error is ≤0.02mm.
[0030] The thrust washer 4 has threaded holes on its side and is fixed to the machine tool worktable 200 by bolts.
[0031] Jack 5 is equipped with a digital pressure gauge, and the lifting speed is controllable.
[0032] The dial indicator 6 is fixed with a magnetic base and has a measuring range of ≥10mm.
[0033] The pressure plate assembly includes multiple pressure plates with a spacing of ≤1 meter, and the pressing surface has a serrated structure.
[0034] The high support pad 2 and the low support pad 3 are made of high-strength cast iron.
[0035] A positioning pin is provided between the contour pad and the machine tool worktable 200, with a positioning accuracy of ±0.1mm.
[0036] The end of the jack 5 is equipped with a polyurethane buffer pad to prevent damage to the workpiece surface.
[0037] The implementation process of the present invention is described in detail below with reference to the accompanying drawings:
[0038] Step 1: Machining of the reference surface at the assembly station
[0039] like Figure 1As shown, the low-pressure outer cylinder 1 is hoisted onto the machine tool worktable 200 at the assembly station. The two side plates of the low-pressure outer cylinder 1 are placed on a leveling pad 2 with a height of 2.8 meters to ensure that the low-pressure outer cylinder 1 is horizontal. A vertical milling machine is used to machine and measure the reference surface, and the distance A from the reference surface to the reference point is recorded. During machining, the milling depth is controlled within 0.2 mm to avoid additional deformation caused by cutting force.
[0040] Step 2: Low-pressure outer cylinder 1 tilting and clamping position adjustment
[0041] Rotate the low-pressure outer cylinder 1 180° so that the horizontal split surface C faces downwards, and transfer it to a non-assembly station. This station uses a 50mm high support pad 3 made of hardened steel with a ground surface roughness of Ra1.6. The support pads 3 are evenly spaced at 500mm intervals to ensure uniform distribution of support force on the bottom surface of the low-pressure outer cylinder 1. Adjust the position of the low-pressure outer cylinder 1 so that one end is close to the thrust pad 4. The contact surface of the thrust pad 4 is designed with cross-shaped anti-slip patterns to enhance friction.
[0042] Step 3: Deformation Detection and Reverse Compensation
[0043] A hydraulic jack 5 is installed at the other end of the low-pressure outer cylinder 1, and a dial indicator 6 with a range of 15mm and an accuracy of 0.01mm is installed on the reference surface on the side of the jack. After zeroing the dial indicator 6, the jack 5 is slowly started, and the low-pressure outer cylinder 1 is lifted at a speed of 0.5mm / s. The deformation is monitored in real time by the dial indicator 6. When the change in the indicated value reaches BA, that is, the height difference between the reference surface of the assembly station and the non-assembly station, the lifting is stopped. At this time, the sinking deformation of the low-pressure outer cylinder 1 caused by its own weight has been compensated in the reverse direction, and the whole has returned to its theoretical geometric state.
[0044] Step 4: Low-pressure outer cylinder 1 clamping and accuracy verification
[0045] Use a pressure plate to press the low-pressure outer cylinder 1 onto the machine tool worktable. The clamping force is controlled by a torque wrench with a torque value of 250 N·m to avoid overtightening and deformation of the low-pressure outer cylinder 1. After clamping, use a laser tracker to re-measure the deformation of the reference surface to ensure that the error is ≤0.05 mm. If it exceeds the tolerance, the stroke of jack 5 needs to be finely adjusted and then clamped again.
[0046] Finally, finishing process
[0047] After clamping, the CNC machine tool is started to perform finishing machining on all surfaces and holes of the low-pressure outer cylinder 1. Due to the high clamping rigidity and the fact that the deformation has been reduced to zero, large cutting parameters can be used, such as increasing the feed rate to 1.3 times the conventional rate, which increases the machining efficiency by about 30%. During the machining process, the machine tool vibration amplitude is significantly reduced, and the tool life is extended by more than 15%.
[0048] The contour pad 2 and support pad 3 adopt a modular design, which can be quickly adjusted according to the workpiece size.
[0049] The thrust pad 4 has a built-in pressure sensor that can provide real-time feedback of contact force data to the control system.
[0050] Jack 5 is equipped with a servo motor drive, supporting remote control and automatic stroke adjustment.
[0051] Through the above steps, this invention achieves efficient and high-precision machining of large thin-walled workpieces, and is especially suitable for manufacturing parts with weak rigidity and easy deformation, such as low-pressure outer cylinders for nuclear power plants.
[0052] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.
Claims
1. A clamping fixture for anti-deformation of a low-pressure outer cylinder in nuclear power plants, characterized in that, include: The machine tool worktable (200) has a high support pad (2) set on it for supporting the two sides of the low-pressure outer cylinder (1) at the assembly station, with a height of 2m-3m; a low support pad (3) set on it for supporting the low-pressure outer cylinder (1) with its horizontal split face facing down at the non-assembly station, with a height of 50mm-800mm; a thrust pad (4) fixed at one end of the non-assembly station for limiting the horizontal displacement of the low-pressure outer cylinder (1); a jack (5) set at the other end of the non-assembly station for applying a reverse lifting force to the low-pressure outer cylinder (1); a dial indicator (6) installed on the reference surface on the side of the jack for real-time monitoring of the workpiece deformation; and a pressure plate assembly for pressing and fixing the low-pressure outer cylinder (1) onto the level pad of the machine tool worktable (200). The contact surfaces of the high support pad (2) and the low support pad (3) are provided with anti-slip textures. The thrust pad (4) is a rigid positioning block. The jack (5) is a hydraulic or mechanical adjustable stroke lifting device. The dial indicator (6) has an accuracy of >0.01mm.
2. The anti-deformation clamping fixture for a low-pressure outer cylinder of a nuclear power plant according to claim 1, characterized in that: The high support pad (2) has a rubber buffer layer on top and is connected to the assembly station machine tool worktable (200) by bolts at the bottom.
3. The anti-deformation clamping fixture for a low-pressure outer cylinder in nuclear power plants according to claim 2, characterized in that: The surface of the short support pad (3) is ground, and the flatness error is ≤0.02mm.
4. The anti-deformation clamping fixture for a low-pressure outer cylinder in nuclear power plants according to claim 3, characterized in that: The thrust pad (4) has a threaded hole on its side and is fixed to the machine tool table (200) by bolts.
5. The anti-deformation clamping fixture for a low-pressure outer cylinder in nuclear power plants according to claim 4, characterized in that: The jack (5) is equipped with a digital pressure gauge, and the lifting speed is controllable.
6. The anti-deformation clamping fixture for a low-pressure outer cylinder in nuclear power plants according to claim 5, characterized in that: The dial indicator (6) is fixed with a magnetic base and has a measuring range of ≥10mm.
7. The anti-deformation clamping fixture for a low-pressure outer cylinder in nuclear power plants according to claim 6, characterized in that: The pressure plate assembly includes multiple pressure plates with a spacing of ≤1 meter and a serrated structure on the pressing surface.
8. The anti-deformation clamping fixture for a low-pressure outer cylinder of a nuclear power plant according to claim 7, characterized in that: The high support pad (2) and the low support pad (3) are made of high-strength cast iron.
9. A nuclear power plant low-pressure outer cylinder anti-deformation clamping fixture according to claim 8, characterized in that: The contour pad is provided with a positioning pin between itself and the machine tool worktable (200), with a positioning accuracy of ±0.1mm.
10. A nuclear power plant low-pressure outer cylinder anti-deformation clamping fixture according to claim 9, characterized in that: The jack (5) has a polyurethane buffer pad at the end of the rod to prevent damage to the workpiece surface.