Method for repairing inclined flange plane of squint window of low-pressure cylinder of steam turbine

Abstract

The invention discloses a turbine low-pressure cylinder squint window inclined flange plane repairing method and belongs to the technical field of mechanical repairing. The problems that in the prior art, when a machine tool is used for repairing a squint window inclined flange, a measuring instrument or equipment needs to be used for measuring a space angle value, use cost is high, and operation is complex are solved. According to the method, punching positioning is used, complex space plane machining is converted into quantifiable mathematical calculation and automatic machining processes, coordinate calculation is used for replacing special measuring equipment, the machining and repairing steps of the workpiece are simplified, operation is easy and convenient, the repairing cost is reduced, professional personnel allocation is reduced, and the repairing targets of high efficiency, high precision and low cost are achieved. The method is mainly used for plane repair of the turbine low-pressure cylinder squint window inclined flange.

Description

Technical Field

[0001] The present invention relates to the technical field of mechanical repair, and particularly relates to a method for repairing the inclined flange plane of the viewing window of a steam turbine low-pressure cylinder. Background Art

[0002] As the core component of a large rotating power equipment, the low-pressure cylinder structure of a steam turbine unit operates under harsh conditions of high temperature, high pressure and high speed for a long time, which easily causes damages such as deformation and wear of the flange plane of the viewing window. As a key component for cylinder body sealing, the flatness of the viewing window flange directly affects the assembly sealing performance of the viewing cover plate and the operation stability of the equipment. The traditional repair process mainly has the following technical bottlenecks: First, when returning to the factory for major repairs, the deformed flange needs to be removed by gas cutting and a new component needs to be welded again. This process not only takes up to 3 - 5 days, but also the high-temperature cutting is likely to cause deterioration of the performance of the base material in the heat-affected zone, increasing the risk of secondary damage. Second, when using manual scraping for repair, it depends on highly skilled fitters to grind repeatedly based on experience. The repair period exceeds 48 hours, and the flatness error is difficult to meet the assembly precision requirements between the flange surface and the cover plate. Moreover, manual operation is likely to cause deviation in the perpendicularity between the axis of the screw hole and the plane, resulting in seal failure. Using a numerical control machine tool for repair is the current mainstream method, but it is necessary to obtain the flange space angle parameters by means of special equipment such as a coordinate measuring machine or a laser tracker and other auxiliary measuring tools. The use cost of professional measuring equipment is high and the operation is complex. The production cycle of other auxiliary measuring tools is long, and the use and installation affect the efficiency, making it difficult to meet the requirements of rapid repair and batch maintenance of steam turbines. Therefore, there is an urgent need to develop an efficient repair method that does not require special measuring equipment and can adaptively calculate the space plane angle to break through the technical barriers of traditional processes. Summary of the Invention

[0003] Aiming at the problem that when using a numerical control machine tool to repair the inclined flange of the viewing window of a steam turbine low-pressure cylinder, it is necessary to obtain the flange space angle parameters by means of special equipment such as a coordinate measuring machine or a laser tracker and other auxiliary measuring tools, and the use cost of professional measuring equipment is high and the operation is complex, and the production cycle of other auxiliary measuring tools is long, and the use and installation affect the efficiency, the present invention provides a method for repairing the inclined flange plane of the viewing window of a steam turbine low-pressure cylinder.

[0004] The present invention is realized through the following technical solutions:

[0005] A method for repairing the inclined flange plane of the viewing window of a steam turbine low-pressure cylinder, comprising the following steps:

[0006] Step S1: Taking the square window contour line of the inclined flange of the viewing window as the reference to draw a cross center line, and at a position preset distance from the outer edge of the square window along the cross center line direction, mark four center punches A, B, C, D in an orthogonal and symmetric manner;

[0007] Step S2: Fix the low-pressure cylinder of the steam turbine on the workbench of the CNC boring machine. Take the horizontal mid-plane as the X-Z plane and the vertical end-face as the X-Y plane. Use their intersection line as the X-axis and the midpoint of the intersection line as the origin O of the coordinate system to establish a reference coordinate system (X, Y, Z). Install a center point on the boring machine spindle and align it with the punch marks A, B, C, and D in turn. Measure and record the spatial coordinate values of each punch mark in the reference coordinate system as A(x1, y1, z1), B(x2, y2, z2), C(x3, y3, z3), and D(x4, y4, z4). According to the spatial coordinate values of the four punch marks, calculate the spatial coordinates O(x o , y o , z o ) of the center point O of the inclined flange square window of the viewing window;

[0008] Step S3: Regard the inclined flange of the viewing window as a spatial plane, which is obtained by rotating the reference plane twice. The first rotation is to rotate the reference plane EFGH by an angle β around the midline AL of this plane to obtain the intermediate plane E'F'G'H'. The second rotation is to rotate the intermediate plane E'F'G'H' by an angle α around its internal side line E'F'. Take the center point O(x o , y o , z o ) as the workpiece machining zero point, write a CNC program using the angles β and α, input the CNC program into the CNC system of the boring machine, and generate a milling surface program;

[0009] Step S4: Compare and verify the coordinate system in the milling surface program with the coordinate system of the actual workpiece. If the verification is consistent, use this milling surface program to mill and repair the surface of the inclined flange of the viewing window. If the verification is inconsistent, adjust the angle of the universal milling head of the boring machine and then mill and repair the surface of the inclined flange of the viewing window.

[0010] Further, in step S1, mark the four punch marks A, B, C, and D in an orthogonal symmetry manner, specifically:

[0011] The connection line of punch marks A and C coincides with the cross center line inside the contour of the inclined flange square window, and the connection line of punch marks B and D coincides with the cross center line inside the contour of the inclined flange square window.

[0012] Preferably, the distance between the punch marks A, B, C, and D and the outer edge of the square window is 10 - 12 mm.

[0013] Further, in step S2, the specific steps for calculating the spatial coordinates O(x o , y o , z o ) of the center point O of the inclined flange square window of the viewing window include:

[0014] Take the midpoint coordinates of punch marks A and C Then take the midpoint coordinates of punch marks B and D Finally, the spatial coordinates of the center point O are determined as

[0015]

[0016] Furthermore, the method for determining the angle β in step S3 is as follows:

[0017]

[0018] Furthermore, the method for determining the angle α in step S3 is as follows:

[0019]

[0020] Furthermore, the specific steps for comparing and verifying the machine tool program coordinate system and the workpiece plane coordinate system in step S4 include:

[0021] S411: Install a dial indicator on the universal milling head of the boring machine, ensure that the measuring head of the dial indicator is perpendicular to the flange surface, and gently touch the flange surface;

[0022] S412: Start the numerical control system and make the universal milling head move along a straight path at the border position parallel to the cross center line in the flange plane;

[0023] S413: During the movement of the milling head, observe the pointer of the dial indicator. If the pointer does not move, it proves that the machine tool program coordinate system and the workpiece plane coordinate system are consistent; if the pointer deflects, it proves that the machine tool program coordinate system and the workpiece plane coordinate system are inconsistent.

[0024] Furthermore, the specific steps for adjusting the universal milling head in step S4 include:

[0025] S421: Install a large-sized face milling cutter on the spindle, and the milling cutter surface covers four center punches;

[0026] S422: Adjust the Z-axis according to the rotated coordinate system;

[0027] S423: Measure the clearance distance between the milling cutter at the four center punch positions and the flange plane through gauge blocks;

[0028] S424: Adjust the A-axis and C-axis of the universal milling head to make the clearance distances between the milling cutter at the above four positions and the flange plane consistent, and the angle adjustment of the universal milling head is completed;

[0029] S425: Record the angles of the adjusted A-axis and C-axis, and rewrite the numerical control program using these two angle values.

[0030] Furthermore, the gauge block specification used in the process of comparing and verifying the machine tool program coordinate system and the workpiece plane coordinate system is 20 mm.

[0031] Advantages of the present invention:

[0032] The repair method for the inclined flange plane of the peephole of the low-pressure cylinder of a steam turbine according to the present invention, when using a machine tool to repair the inclined flange plane of the peephole of the low-pressure cylinder of a steam turbine, by punching alignment marks, it converts the processing of a complex spatial plane into quantifiable mathematical calculations and an automated processing process, uses coordinate calculations to replace special measuring equipment, simplifies the processing and repair steps of the workpiece, is easy to operate, reduces the repair cost, reduces the allocation of professional personnel, and achieves the repair goals of high efficiency, high precision, and low cost. The present invention can also provide guidance for similar inclined plane processing work. Description of the Drawings

[0033] Figure 1 is a schematic diagram of the inclined flange of the peephole of the low-pressure cylinder of a steam turbine in an embodiment of the present invention;

[0034] Figure 2 is a sectional view of the inclined flange of the peephole of the low-pressure cylinder of a steam turbine along Figure 1 k-k in;

[0035] Figure 3 is a schematic diagram of drawing lines on the inclined flange of the peephole of the low-pressure cylinder of a steam turbine in an embodiment of the present invention;

[0036] Figure 4 is a schematic diagram of the rotation angle of a spatial plane in an embodiment of the present invention;

[0037] Figure 5 is an isometric schematic diagram of angle calculation in an embodiment of the present invention. Detailed Embodiments

[0038] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention. Detailed Embodiment 1

[0040] Combined with Figures 1 to 5 to illustrate this embodiment. The repair method for the inclined flange plane of the peephole of the low-pressure cylinder of a steam turbine in this embodiment is specifically as follows:

[0041] Step S1: As Figure 3 shown, taking the square window contour line of the inclined flange of the peephole as the reference, draw a cross center line, and at a position 10 mm away from the outer edge of the square window along the cross center line direction, mark four alignment marks in an orthogonal and symmetric manner.

[0042] The line connecting the center punches A and C coincides with the cross center line within the contour of the inclined flange square window, and the line connecting the center punches B and D coincides with the cross center line within the contour of the inclined flange square window.

[0043] In this embodiment, the distance between the center punch and the edge of the flange square window of the viewing window is 10 mm. The setting of this distance is not a limitation on the present invention. In actual operation, other values can be selected according to the specific specifications of the flange.

[0044] There may be slight deformation in the edge area of the inclined flange square window due to long-term thermal expansion or mechanical vibration. As a key reference mark during the repair process, the center punch being at a certain distance from the edge of the square window can avoid positioning errors caused by direct operation on the edge. Punching center punches symmetrically on both sides of the center line can keep the plane of the repaired inclined flange symmetrical and avoid seal leakage problems caused by unilateral deviation. The inclined flange usually has bolt holes, and leaving a distance can prevent the center punch operation from accidentally damaging the edge of the bolt hole (such as the thread). At the same time, after the inclined flange is repaired, the viewing window or other components need to be reinstalled. Leaving a margin at the edge can provide necessary space for subsequent tool operations and avoid interference.

[0045] Step S2: As Figure 1 and Figure 3 shown, fix the low-pressure cylinder of the steam turbine on the workbench of the CNC boring machine. Take the horizontal middle plane as the X-Z plane and the vertical end face as the X-Y plane. Use their intersection line as the X-axis and the midpoint of the intersection line as the origin O of the coordinate system to establish a reference coordinate system (X, Y, Z). Install a center point on the boring machine spindle and align it with the center punches A, B, C, and D in turn. Measure and record the spatial coordinate values of each center punch in the reference coordinate system as A(x1, y1, z1), B(x2, y2, z2), C(x3, y3, z3), D(x4, y4, z4). According to the spatial coordinate values of the four center punches, calculate the spatial coordinates O(x o , y o , z o ) of the center point O of the inclined flange square window of the viewing window. The specific process includes:

[0046] Take the midpoint coordinates of the center punches A and C Then take the midpoint coordinates of the center punches B and D Finally, determine that the spatial coordinates of the center point O are

[0047]

[0048] Step S3: Consider the inclined flange of the viewing window as a spatial plane, which is obtained by rotating the reference plane twice; the first rotation is to rotate the reference plane EFGH around the midline AL of the plane by an angle β to obtain the intermediate plane E′F′G′H′, and the second rotation is to rotate the intermediate plane E′F′G′H′ around its internal side line E′F′ by an angle α; with the center point O(xo , y o , z o ) is the workpiece machining zero point. The numerical control program is written using the β and α angles, and the numerical control program is input into the numerical control system of the boring machine to generate a milling surface program.

[0049] Specifically, the steps to determine the angles β and α include:

[0050] As Figure 4 and Figure 5 shown, the spatial plane of the low-pressure cylinder can be decomposed into the reference plane EFGH enclosed by the four points E, F, G, and H. The reference plane is rotated by the β angle around the midline AL of this plane to adjust the horizontal inclination direction of the reference plane, and the intermediate plane E'F'G'H' is obtained through transformation; then the intermediate plane E'F'G'H' is rotated by the α angle along the straight line E'F', and the target spatial plane, that is, the spatial plane where the viewing window of the steam turbine low-pressure cylinder is located, namely the region enclosed by E', F', G'', and H'', is obtained through transformation. The process of converting the intermediate plane E'F'G'H' into the target spatial plane is the same as Figure 2 the process of the inclined flange of the viewing window rotating by the α angle along K-K in

[0051] The specific steps to determine the angle β include:

[0052]

[0053] The specific steps to determine the angle α include:

[0054]

[0055] Taking the center point O(x o , y o , z o ) as the workpiece machining zero point, the numerical control program is written using the β and α angles, and the numerical control program is input into the numerical control system of the boring machine to generate a milling surface program.

[0056] Step S4: Compare and verify the coordinate system in the milling surface program with the coordinate system of the actual workpiece. If the verification is consistent, use this milling surface program to perform milling repair on the surface of the inclined flange of the viewing window; if the verification is inconsistent, adjust the angle of the universal milling head of the boring machine and then perform milling repair on the surface of the inclined flange of the viewing window.

[0057] Specifically, the steps to compare and verify the coordinate system of the machine tool program and the workpiece plane coordinate system include:

[0058] S411: Install a dial indicator on the universal milling head of the boring machine to ensure that the measuring head of the dial indicator is perpendicular to the flange surface and gently touches the flange surface;

[0059] S412: Start the numerical control system to make the universal milling head move along a straight path at the position of the frame parallel to the cross center line on the flange plane;

[0060] S413: During the movement of the milling head, observe the pointer of the dial indicator. If the pointer does not move, it proves that the machine tool program coordinate system and the workpiece plane coordinate system are consistent; if the pointer deflects, it proves that the machine tool program coordinate system and the workpiece plane coordinate system are inconsistent.

[0061] When it is verified that the machine tool program coordinate system and the workpiece plane coordinate system are inconsistent, the angle of the universal milling head of the boring machine needs to be adjusted. The specific adjustment method is as follows:

[0062] S421: Install a large-size face milling cutter on the spindle, and the milling cutter surface covers four center punches;

[0063] S422: Adjust the Z-axis according to the rotated coordinate system;

[0064] S423: Measure the clearance distance between the milling cutter at the four-point position surface and the flange plane through gauge blocks at the positions of the four center punches;

[0065] S424: Adjust the A-axis and C-axis of the universal milling head so that the clearance distances between the milling cutter at the above four-point positions and the flange plane are the same, and the angle adjustment of the universal milling head is completed;

[0066] S425: Record the angles of the adjusted A-axis and C-axis, and use these two angle values to rewrite the numerical control program.

[0067] The 20mm gauge block is a common standard specification in the machining industry, which is easy to purchase and has a low cost. There is no need to customize special measuring tools, reducing the threshold of process implementation; it matches the probe stroke and fixture opening and closing space of the numerical control boring machine, avoiding interference caused by too large gauge block size or positioning difficulties caused by too small size; it has a moderate weight, which is convenient for fitters to manually place and adjust, reducing labor intensity.

[0068] If the screw holes are misaligned during the installation of the viewing window cover plate, use a drill bit to expand the hole in the direction of the misaligned teeth. This operation does not affect the installation and use.

[0069] As can be seen from the above embodiments, the present application discloses a method for repairing the inclined flange plane of the viewing window of a steam turbine low-pressure cylinder. In the present application, center punches are used for positioning, converting the complex space plane machining into a quantifiable mathematical calculation and an automated machining process, using coordinate calculation to replace special measuring equipment, simplifying the machining and repair steps of the workpiece, with simple operation, reducing the repair cost, reducing the professional staff, achieving the repair goals of high efficiency, high precision and low cost, and the present invention can also provide guidance for similar inclined plane machining work.

[0070] The above embodiments of the present invention are only for explaining in detail the operation process of the present invention, rather than limiting the embodiments of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made on the basis of the above description. It is impossible to list all the embodiments here. Any obvious changes or modifications derived from the technical solutions of the present invention still fall within the protection scope of the present invention.

Claims

1. Repair method for inclined flange plane of peep window of steam turbine low-pressure cylinder, characterized in that, It includes the following steps: Step S1: Take the square window contour line of the peep window inclined flange as the reference to draw a cross center line. Along the direction of the cross center line, at a position preset distance from the outer edge of the square window, mark four center punches A, B, C, and D in an orthogonal symmetric manner; Step S2: Fix the low-pressure cylinder of the steam turbine on the workbench of the CNC boring machine. Take the horizontal mid-separation plane as the X-Z plane and the vertical end face as the X-Y plane. Use their intersection line as the X-axis and the midpoint of the intersection line as the origin O of the coordinate system to establish a reference coordinate system (X, Y, Z). Install a center point on the boring machine spindle and align it with the punch marks A, B, C, and D in sequence. Measure and record the spatial coordinate values of each punch mark in the reference coordinate system as A(x1, y1, z1), B(x2, y2, z2), C(x3, y3, z3), and D(x4, y4, z4). According to the spatial coordinate values of the four punch marks, calculate the spatial coordinates O(x o , y o , z o ) of the center point of the diagonal flange square window of the viewing window; Step S3: Consider the inclined flange of the peep window as a spatial plane, which is obtained by rotating the reference plane twice; the first rotation is to rotate the reference plane EFGH by an angle β around the midline AL of this plane to obtain the intermediate plane E'F'G'H', and the second rotation is to rotate the intermediate plane E'F'G'H' by an angle α around the internal side line E'F'; taking the center point O(x o , y o , z o ) as the workpiece machining zero point, write a numerical control program using the angles β and α, input the numerical control program into the numerical control system of the boring machine, and generate a milling surface program; Step S4: Compare and verify the coordinate system in the milling surface program with the coordinate system of the actual workpiece. If the verification is consistent, use this milling surface program to repair the surface milling of the peep window inclined flange; if the verification is inconsistent, adjust the angle of the universal milling head of the boring machine and then perform the surface milling repair of the peep window inclined flange.

2. The repair method of the inclined flange plane of the peephole of the low-pressure cylinder of the steam turbine according to claim 1, characterized in that, In step S1, marking the four center punches A, B, C, and D in an orthogonal symmetric manner specifically means: The connection line of center punches A and C coincides with the cross center line inside the square window contour of the inclined flange, and the connection line of center punches B and D coincides with the cross center line inside the square window contour of the inclined flange.

3. The repair method for the inclined flange plane of the peephole of the low-pressure cylinder of a steam turbine according to claim 2, characterized in that In step S1, the distance between center punches A, B, C, and D and the outer edge of the square window is 10 - 12 mm.

4. The method for repairing the inclined flange plane of the peephole of the low-pressure cylinder of the steam turbine according to claim 3, wherein, In step S2, the specific steps for calculating the spatial coordinates O(x o , y o , z o ) of the center point O of the inclined flange square window of the viewing window are as follows: Take the midpoint coordinates of the center punches A and C Then take the midpoint coordinates of the center punches B and D Finally, determine that the spatial coordinates of the center point O are 5. The method for repairing the inclined flange plane of the peephole of the low-pressure cylinder of a steam turbine according to claim 4, wherein, The determination method of the angle β in step S3 is:

6. The method for repairing the inclined flange plane of the peephole of the low-pressure cylinder of a steam turbine according to claim 5, characterized in that, The determination method of the angle α in step S3 is:

7. The repair method for the inclined flange plane of the peephole of the low-pressure cylinder of a steam turbine according to claim 6, characterized in that, The specific steps for comparing and verifying the machine tool program coordinate system and the workpiece plane coordinate system in step S4 include: S411: Install a dial indicator on the universal milling head of the boring machine to ensure that the measuring head of the dial indicator is perpendicular to the flange surface and gently touches the flange surface; S412: Start the numerical control system to make the universal milling head move along a straight path at the border position parallel to the cross center line in the flange plane; S413: During the movement of the milling head, observe the pointer of the dial indicator. If the pointer does not move, it proves that the machine tool program coordinate system and the workpiece plane coordinate system are consistent; if the pointer deflects, it proves that the machine tool program coordinate system and the workpiece plane coordinate system are inconsistent.

8. The method for repairing the inclined flange plane of the peephole of the low-pressure cylinder of a steam turbine according to claim 7, characterized in that, The specific steps for adjusting the universal milling head in step S4 include: S421: Install a large-size face milling cutter on the spindle, and the milling cutter surface covers the four center punches; S422: Adjust the Z-axis according to the rotated coordinate system; S423: Measure the clearance distance between the milling cutter at the four-point positions and the flange plane through gauge blocks at the positions of the four center punches; S424: Adjust the A-axis and C-axis of the universal milling head to make the clearance distances between the milling cutter at the above four-point positions and the flange plane consistent, and the adjustment of the universal milling head angle is completed; S425: Record the angles of the adjusted A-axis and C-axis, and use these two angle values to rewrite the numerical control program.

9. The method for repairing the inclined flange plane of the peephole of the low-pressure cylinder of a steam turbine according to claim 8, wherein The gauge block specification used in the process of comparing and verifying the machine tool program coordinate system and the workpiece plane coordinate system is 20 mm.

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