Reversible deformation clamping method for nuclear power low-pressure outer cylinder

Abstract

The invention belongs to the technical field of clamping of nuclear power low-pressure outer cylinders, and particularly relates to a reversible deformation clamping method of a nuclear power low-pressure outer cylinder. The method comprises the following steps that S1, an assembly station datum plane is machined; s2, the workpiece is turned over to a clamping station with the horizontal split facing downwards, the low-pressure outer cylinder is arranged on a supporting pad, and the distance size of a second datum plane after turning over is measured; s3, a thrust pad is arranged at one end of the workpiece, the other end of the workpiece is supported through a jack, and a dial indicator is installed on the outer wall of the jack side table and zeroed; s4, the jack is used for slowly jacking the outer wall of the side table on the jack side of the workpiece, the change of the indicating value of the percentage is observed, jacking is stopped when the indicating value reaches B-A, and at the moment, the dead weight deformation of the workpiece is counteracted reversely; and the low-pressure outer cylinder is pressed and fixed to a supporting pad of a machine tool workbench through a pressing plate, and clamping is completed. The clamping rigidity can be improved, self-weight deformation is compensated, and the machining efficiency is greatly improved.

Description

Technical Field

[0001] The present invention belongs to the clamping technical field of nuclear power low-pressure outer cylinders, and particularly relates to an anti-deformation clamping method for nuclear power low-pressure outer cylinders. Background Art

[0002] As a key component of a nuclear power unit, the nuclear power low-pressure outer cylinder is composed of six half cylinders. The single half size is up to 12 meters long, 3 - 4 meters wide, and about 4 meters high. Its structure is in a hollow form, with the inner cylinder installed inside. However, the supporting plinths at both ends are relatively thick, while the middle area is thin and empty, resulting in a significant reduction in overall rigidity. Especially under its own weight, the deformation amount in the lower half of the middle part can reach nearly 10 mm, seriously affecting the machining accuracy.

[0003] Traditional machining methods require finish machining at the assembly and use station. However, the supporting plinths at this station are located at both ends, up to 2.7 meters above the bottom surface. It is necessary to use supporting pads with a height exceeding 2.7 meters, and the span exceeds 10 meters.

[0004] The existing clamping methods for nuclear power low-pressure outer cylinders have the following problems: First, the rigidity of the support system is insufficient, and the workpiece is prone to tremor during the machining process, so a small cutting amount needs to be adopted, resulting in low machining efficiency; second, the clamping stability is poor, and it is difficult to meet the requirements of high-precision machining. In addition, the existing clamping methods for nuclear power low-pressure outer cylinders cannot effectively offset the self-weight deformation of the workpiece, resulting in a large deviation between the machined surface and the theoretical design, and repeated adjustments are required, further prolonging the machining cycle. Therefore, there is an urgent need for a new clamping method that can improve the clamping rigidity, compensate for the self-weight deformation, and improve the machining efficiency. Summary of the Invention

[0005] In order to solve the problems that the existing clamping methods for nuclear power low-pressure outer cylinders cannot effectively offset the self-weight deformation of the workpiece, resulting in a large deviation between the machined surface and the theoretical design; the rigidity of the support system is insufficient, the workpiece is prone to tremor during the machining process, the clamping stability is poor, it is difficult to meet the requirements of high-precision machining, repeated adjustments are required, and the machining efficiency is low, the present invention proposes an anti-deformation clamping method for nuclear power low-pressure outer cylinders, including the following steps:

[0006] S1: Machining of the reference plane at the assembly station:

[0007] At the assembly and use station, place the table surfaces on both sides of the workpiece on equal-height pads to make the workpiece suspended, machine the measurement reference plane and record the first reference plane distance dimension A;

[0008] S2: Workpiece flipping and adjustment of the clamping station:

[0009] Flip the workpiece to the clamping station with the horizontal middle plane facing down, place the low-pressure outer cylinder on the supporting pad, and measure the second reference plane distance dimension B after flipping;

[0010] S3: Deformation amount detection and reverse compensation:

[0011] A thrust pad is set at one end of the workpiece, and the other end is supported by a jack. A dial indicator is installed on the outer wall of the side platform of the jack and zeroed.

[0012] S4: Workpiece clamping and precision verification:

[0013] Slowly press the workpiece against the outer wall of the side platform of the jack using the jack, and observe the change in the dial indicator reading. Stop pressing when the reading reaches B - A. At this time, the self-weight deformation of the workpiece is counteracted in the reverse direction.

[0014] Use a pressing plate to tightly fix the low-pressure outer cylinder on the support pad of the machine tool workbench to complete the clamping.

[0015] According to the anti-deformation clamping method of a nuclear power low-pressure outer cylinder described above, the material of the equal-height pad described in step S1 is high-hardness alloy steel, and the surface roughness ≤ Ra1.6.

[0016] According to the anti-deformation clamping method of a nuclear power low-pressure outer cylinder described above, the processing of the measurement reference surface described in step S1 uses a vertical milling machine, and the milling depth ≤ 0.2 mm.

[0017] According to the anti-deformation clamping method of a nuclear power low-pressure outer cylinder described above, the distribution spacing of the support pads described in step S2 ≤ 500 mm to enhance the uniformity of the support on the bottom surface of the workpiece.

[0018] According to the anti-deformation clamping method of a nuclear power low-pressure outer cylinder described above, the measuring range of the dial indicator described in step S3 ≥ 15 mm, and the accuracy grade is 0.01 mm.

[0019] According to the anti-deformation clamping method of a nuclear power low-pressure outer cylinder described above, the contact surface of the thrust pad described in step S3 is provided with anti-slip lines, and the fitting degree with the end surface of the workpiece ≥ 95%.

[0020] According to the anti-deformation clamping method of a nuclear power low-pressure outer cylinder described above, the lifting speed of the jack described in step S4 ≤ 0.5 mm / s to ensure the accuracy of deformation compensation.

[0021] According to the anti-deformation clamping method of a nuclear power low-pressure outer cylinder described above, the pressing force of the pressing plate described in step S4 is controlled by a torque wrench, and the torque value is 200 - 300 N·m.

[0022] According to the anti-deformation clamping method of a nuclear power low-pressure outer cylinder described above, step S4 also includes collecting the dial indicator data in real time during the pressing process and automatically adjusting the stroke of the jack through the control system.

[0023] According to the above-mentioned anti-deformation clamping method for a nuclear power low-voltage outer cylinder, after step S4 is completed, a laser tracker is used to re-measure the deformation of the workpiece reference surface to ensure that the error is ≤0.05mm.

[0024] The beneficial effects of the present invention are as follows:

[0025] 1. The present invention pre-processes the measurement reference surface at an assembly station with weaker rigidity to provide a basis for subsequent deformation detection; secondly, the workpiece is turned over to a station with stronger rigidity for clamping, and combined with a short support pad and a thrust pad, the clamping stability is greatly improved to avoid processing vibration.

[0026] 2. The present invention uses a jack for reverse support and a dial indicator to monitor the deformation in real time, accurately compensates for the deformation caused by the workpiece's own weight, returns the deformation to zero, and then presses and fixes it, ensuring that the processing reference surface is consistent with the theoretical design.

[0027] This method breaks through the limitations of traditional processes, allowing efficient finishing in non-assembly stations, and can increase cutting parameters by about 30%, significantly improving processing efficiency. At the same time, the enhancement of clamping rigidity reduces tool wear, extends tool life, and reduces processing costs. It has been verified in practice that the dimensional accuracy of the nuclear power low-voltage outer cylinder processed by this method fully meets the requirements of the drawings, and the surface quality is stable. It effectively solves the problem of deformation control in the processing of large thin-walled parts and has important engineering application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The present invention is a schematic diagram of a nuclear power low-pressure outer cylinder assembly use station of a reverse deformation clamping method of the nuclear power low-pressure outer cylinder.

[0029] Figure 2 The invention discloses a schematic diagram of a nuclear power low-pressure outer cylinder anti-deformation station of a nuclear power low-pressure outer cylinder anti-deformation clamping method.

[0030] In the figure: 1- low-pressure outer cylinder, 2- equal height pad, 3- support pad, 4- thrust pad, 5- jack, 6- dial indicator. DETAILED DESCRIPTION

[0031] Preferred Embodiments

[0032] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0033] like Figure 1 , Figure 2 As shown: In this embodiment, a method for anti-deformation clamping of a nuclear power low-pressure outer cylinder includes the following steps:

[0034] S1: Machining the reference plane of the assembly station:

[0035] On the assembly station, place the two side table surfaces of the workpiece on the equal-height pads 2 so that the workpiece is suspended, machine the measurement reference plane and record the distance dimension A of the first reference plane;

[0036] S2: Workpiece flipping and clamping station adjustment:

[0037] Flip the workpiece to the clamping station with the horizontal mid-plane facing down, place the low-pressure outer cylinder 1 on the support pads 3, and measure the distance dimension B of the second reference plane after flipping;

[0038] S3: Deformation measurement and reverse compensation:

[0039] Set a thrust pad 4 at one end of the workpiece, support the other end with a jack 5, and install a dial indicator 6 on the outer wall of the side table of the jack and zero it;

[0040] S4: Workpiece clamping and accuracy verification:

[0041] Slowly press the outer wall of the side table of the jack of the workpiece with the jack 5, observe the change of the dial indicator value, and stop pressing when the value reaches B - A. At this time, the self-weight deformation of the workpiece is offset in the reverse direction;

[0042] Use a pressing plate to tightly fix the low-pressure outer cylinder on the support pads of the machine tool workbench to complete the clamping.

[0043] In step S1, the material of the equal-height pad 2 is high-hardness alloy steel, and the surface roughness ≤ Ra1.6.

[0044] In step S1, the machining of the measurement reference plane uses a vertical milling machine, and the milling depth ≤ 0.2 mm.

[0045] In step S2, the distribution spacing of the support pads 3 ≤ 500 mm to enhance the uniformity of the workpiece bottom support.

[0046] In step S3, the measuring range of the dial indicator 6 ≥ 15 mm, and the accuracy grade is 0.01 mm.

[0047] In step S3, the contact surface of the thrust pad 4 is provided with anti-slip lines and the fit with the workpiece end face

[0048] ≥ 95%.

[0049] In step S4, the lifting speed of the jack 5 ≤ 0.5 mm / s to ensure the accuracy of deformation compensation.

[0050] In step S4, the clamping force of the pressing plate is controlled by a torque wrench, and the torque value is 200 - 300 N·m.

[0051] Step S4 also includes collecting dial gauge data in real time during the jacking process and automatically adjusting the jack stroke through the control system.

[0052] After step S4 is completed, the deformation of the workpiece reference surface is re-measured using a laser tracker to ensure that the error is ≤0.05 mm.

[0053] The implementation process of the present invention is described in detail below with reference to the accompanying drawings:

[0054] Step 1: Assembly station reference surface processing

[0055] like Figure 1 As shown, the low-pressure outer cylinder 1 is hoisted to the assembly station, and the two side table surfaces are placed on the equal height pad 2 with a height of 2.8 meters to ensure that the workpiece is level. Use a vertical milling machine to process and measure the reference surface, and record the distance dimension A from the reference surface to the reference point. During processing, the milling depth is controlled within 0.2mm to avoid additional deformation caused by cutting force.

[0056] Step 2: Workpiece flipping and clamping station adjustment

[0057] Turn the workpiece 180° so that the horizontal center face is facing downward and transfer it to the non-assembly station. This station uses a support pad 3 with a height of 50 mm, which is made of hardened steel and has a surface that is ground to a roughness of Ra1.6. The support pads 3 are evenly arranged at a spacing of 500 mm to ensure that the support force on the bottom surface of the workpiece is evenly distributed. Adjust the position of the workpiece so that one end of it is close to the thrust pad (4). The contact surface of the thrust pad 4 is designed with cross anti-slip patterns to enhance friction.

[0058] Step 3: Deformation detection and reverse compensation

[0059] Install a hydraulic jack (5) at the other end of the workpiece, and install a dial indicator (6) on the reference surface on the jack side, with a range of 15mm and an accuracy of 0.01mm. After adjusting the dial indicator to zero, slowly start the jack and lift the workpiece at a speed of 0.5mm / s. Use the dial indicator 6 to monitor the deformation in real time. When the indicated value changes to BA, that is, the height difference between the reference surface of the assembly station and the non-assembly station, stop lifting. At this time, the sinking deformation caused by the deadweight of the workpiece has been reversely compensated, and the overall geometry has been restored to the theoretical state.

[0060] Step 4: Workpiece clamping and accuracy verification

[0061] Use a pressure plate to press the workpiece onto the machine tool table. The clamping force is controlled by a torque wrench with a torque value of 250N·m to avoid deformation of the workpiece caused by over-tightening. After clamping, use a laser tracker to re-measure the deformation of the reference surface to ensure that the error is ≤0.05mm. If the tolerance is exceeded, the jack stroke needs to be fine-tuned and re-tightened.

[0062] Finally, finishing is performed

[0063] After the clamping is completed, the CNC machine tool is started to perform fine machining of the outer cylinder surfaces and holes. Due to the high clamping rigidity and zero deformation, large cutting parameters can be used, such as increasing the feed speed to 1.3 times the conventional one, and the machining efficiency is increased by about 30%. During the machining process, the vibration amplitude of the machine tool is significantly reduced, and the tool life is extended by more than 15%.

[0064] The contour pad 2 and the support pad 3 adopt a modular design, and the layout can be quickly adjusted according to the size of the workpiece.

[0065] The thrust pad 4 has a built-in pressure sensor, which can feed back contact force data to the control system in real time.

[0066] Jack 5 is equipped with a servo motor drive, which supports remote control and automatic stroke adjustment.

[0067] Through the above steps, the present invention realizes efficient and high-precision processing of large thin-walled workpieces, and is particularly suitable for the manufacture of weakly rigid and easily deformed parts such as nuclear power low-pressure outer cylinders.

[0068] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A clamping method for anti-deformation of a low-pressure outer cylinder of a nuclear power plant, characterized in that, The following steps are involved: S1: Assembly station reference surface processing: At the assembly station, place the table surfaces on both sides of the workpiece on equal height pads, suspend the workpiece in the air, process and measure the reference surface and record the first reference surface distance dimension A; S2: Workpiece flipping and clamping station adjustment: Turn the workpiece over to the clamping station with the horizontal center plane facing downward, place the low-pressure outer cylinder on the support pad, and measure the distance dimension B of the second reference plane after turning over; S3: Deformation detection and reverse compensation: A thrust pad is set at one end of the workpiece, and the other end is supported by a jack, and a dial indicator is installed on the outer wall of the side table on the jack side and adjusted to zero; S4: Workpiece clamping and precision verification: Use the jack to slowly press the outer wall of the side table of the workpiece jack, observe the change of the percentage value, and stop pressing when the value reaches BA. At this time, the deformation of the workpiece by its own weight is reversed; Use a pressure plate to press and fix the low-pressure outer cylinder onto the support pad of the machine tool workbench to complete the clamping.

2. The anti-deformation clamping method of a low-pressure outer cylinder of a nuclear power plant according to claim 1, characterized in that: The material of the contour pad in step S1 is high-hardness alloy steel, and the surface roughness is ≤Ra1.

6.

3. A clamping method for anti-deformation of a low-pressure outer cylinder of a nuclear power plant according to claim 2, characterized in that: The measurement reference surface in step S1 is processed by a vertical milling machine, and the milling depth is ≤0.2mm.

4. A clamping method for anti-deformation of a low-pressure outer cylinder of a nuclear power plant according to claim 3, characterized in that: The distribution spacing of the support pads in step S2 is ≤500 mm to enhance the uniformity of support on the bottom surface of the workpiece.

5. A clamping method for anti-deformation of a low-pressure outer cylinder of a nuclear power plant according to claim 4, characterized in that: The measuring range of the dial indicator in step S3 is ≥15 mm, and the accuracy level is 0.01 mm.

6. A clamping method for anti-deformation of a low-pressure outer cylinder of a nuclear power plant according to claim 5, characterized in that: In step S3, the contact surface of the thrust pad is provided with anti-slip grooves, and the degree of fit with the end surface of the workpiece is ≥95%.

7. A clamping method for anti-deformation of a low-pressure outer cylinder of a nuclear power plant according to claim 6, characterized in that: The lifting speed of the jack in step S4 is ≤0.5 mm / s to ensure the accuracy of deformation compensation.

8. A method for anti-deformation clamping of a low-pressure outer cylinder of a nuclear power plant according to claim 7, characterized in that: The pressing force of the pressing plate in step S4 is controlled by a torque wrench, and the torque value is 200-300 N·m.

9. The anti-deformation clamping method of a nuclear power low-pressure outer cylinder according to claim 8, characterized in that: Step S4 also includes collecting dial gauge data in real time during the jacking process and automatically adjusting the jack stroke through the control system.

10. A method for anti-deformation clamping of a low-pressure outer cylinder of a nuclear power plant, as described in claim 9, wherein: After step S4 is completed, the deformation of the workpiece reference surface is re-measured using a laser tracker to ensure that the error is ≤0.05 mm.

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