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

Abstract

The application discloses a kind of turbine low-pressure cylinder sight window inclined flange plane repair method, belongs to mechanical repair technical field.The application is to solve the problem of high cost and complex operation in prior art when using machine tool to repair the inclined flange of sight window, which needs to measure the space angle value with the help of measuring instruments or equipment.The application uses the positioning of ocean punch hole to convert the complex space plane processing into quantifiable mathematical calculation and automatic processing flow, uses coordinate calculation instead of special measuring equipment, simplifies the processing and repair steps of workpiece, is easy to operate, reduces the repair cost and reduces the number of professional personnel, realizes the repair target of high efficiency, high precision and low cost.The application is mainly used for the plane repair of turbine low-pressure cylinder sight window inclined flange.

Description

Technical Field

[0001] This invention relates to the field of mechanical repair technology, specifically to a method for repairing the oblique flange plane of the inspection window of a steam turbine low-pressure cylinder. Background Technology

[0002] As a core component of 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 extended periods, which can easily lead to deformation and wear on the flange surface of the inspection window. As a key component for cylinder sealing, the flatness of the inspection window flange directly affects the assembly sealing performance of the inspection cover and the operational stability of the equipment. Traditional repair processes suffer from the following technical bottlenecks: First, during major overhauls, the deformed flange must be removed by gas cutting and new components welded on. This process not only takes 3-5 days, but the high-temperature cutting can also degrade the performance of the heat-affected zone of the base material, increasing the risk of secondary damage. Second, when using manual scraping for repair, it relies on highly skilled fitters to repeatedly grind based on experience, resulting in a repair cycle exceeding 48 hours. The flatness error is difficult to meet the assembly accuracy requirements between the flange surface and the cover plate, and manual operation can easily lead to deviations in the perpendicularity of the bolt hole axis to the plane, causing sealing failure. Currently, CNC machine tools are the mainstream approach for repair, but this requires specialized equipment such as coordinate measuring machines or laser trackers, as well as other auxiliary tooling, to obtain the flange's spatial angle parameters. Specialized measuring equipment is costly and complex to operate, while other auxiliary measuring tooling has long production cycles and its use and installation impact efficiency, making it difficult to meet the needs of rapid rework and mass maintenance of steam turbines. Therefore, there is an urgent need to develop a highly efficient repair method that does not require specialized measuring equipment and can adaptively calculate spatial plane angles, in order to overcome the technical barriers of traditional processes. Summary of the Invention

[0003] To address the problems of existing methods for repairing the oblique flange of the inspection window of a steam turbine's low-pressure cylinder using CNC machine tools, which require specialized equipment such as a coordinate measuring machine or laser tracker, as well as other auxiliary measuring fixtures to obtain the flange's spatial angle parameters, resulting in high costs and complex operations for specialized measuring equipment, and long production cycles and inefficiencies for other auxiliary measuring fixtures, this invention provides a planar repair method for the oblique flange of the inspection window of a steam turbine's low-pressure cylinder.

[0004] This invention is achieved through the following technical solution:

[0005] The repair method for the oblique flange plane of the inspection window of the low-pressure cylinder of a steam turbine includes the following steps:

[0006] Step S1: Using the outline of the square window of the viewing window flange as a reference, draw a cross center line. Mark four eyelets A, B, C, and D at a predetermined distance from the outer edge of the square window along the direction of the cross center line in an orthogonal and symmetrical manner.

[0007] Step S2: Fix the low-pressure cylinder of the steam turbine onto the CNC boring machine table. Using the horizontal midline as the XZ plane and the vertical end face as the XY plane, establish a reference coordinate system (X, Y, Z) with their intersection as the X-axis and the midpoint of the intersection as the origin O. Install centers on the boring machine spindle and align them sequentially with the punches A, B, C, and D. Measure and record the spatial coordinates of each punch in the reference coordinate system: A(x1, y1, z1), B(x2, y2, z2), C(x3, y3, z3), and D(x4, y4, z4). Based on the spatial coordinates of the four punches, calculate the spatial coordinates O(x1, y1, z1), O(x2, y2, z2), O(x3, y3, z3), O(x4, y4, z4) of the center point O of the oblique flange square window of the inspection window. o ,y o ,z o );

[0008] Step S3: Consider the peephole flange 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 center line AL of this plane by an angle β to obtain the intermediate plane E′F′G′H′; the second rotation is to rotate the intermediate plane E′F′G′H′ around its inner edge line E′F′ by an angle α; with the center point O(x o ,y o ,z o ) is the zero point for workpiece machining. A CNC program is written using angles β and α. The CNC program is then input into the CNC system of the boring machine to generate a milling program.

[0009] Step S4: Compare and verify the coordinate system in the milling program with the coordinate system of the actual workpiece. If the verification is consistent, use the milling program to perform milling repair on the surface of the peephole flange. If the verification is inconsistent, adjust the angle of the universal milling head of the boring machine before performing milling repair on the surface of the peephole flange.

[0010] Furthermore, in step S1, the four ocean eyes A, B, C, and D are marked in an orthogonal symmetrical manner, specifically as follows:

[0011] The line connecting eyelets A and C coincides with the center line of the cross inside the outline of the oblique flange square window, and the line connecting eyelets B and D coincides with the center line of the cross inside the outline of the oblique flange square window.

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

[0013] Further, in step S2, the spatial coordinates O(x) of the center point O of the oblique flange square window of the viewing window are calculated. o ,y o ,z o The specific steps include:

[0014] Take the coordinates of the midpoints of points A and C in the ocean. Next, take the coordinates of the midpoints of points B and D in the Yangchong eye. Finally, the spatial coordinates of the center point O were determined as follows:

[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 in step S4 for comparing and verifying the machine tool program coordinate system and the workpiece plane coordinate system include:

[0021] S411: Install a dial indicator on the universal milling head of the boring machine, ensuring that the probe of the dial indicator is perpendicular to the flange surface and lightly touches the flange surface;

[0022] S412: Start the CNC system and make the universal milling head move a straight path along the edge of the flange plane parallel to the cross center line;

[0023] S413: During the movement of the milling head, observe the dial indicator pointer. 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 deviates, 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: A large-size face milling cutter is added to the spindle, with the cutter face covering four punch holes;

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

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

[0028] S424: By adjusting the A-axis and C-axis of the universal milling head, the clearance distance between the face milling cutter and the flange plane at the above four positions is made consistent, and the angle adjustment of the universal milling head is completed;

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

[0030] Furthermore, the gauge blocks used in the comparison and verification process between the machine tool program coordinate system and the workpiece plane coordinate system are 20mm in size.

[0031] The beneficial effects of this invention are:

[0032] This invention relates to a method for repairing the oblique flange plane of the inspection window of a steam turbine low-pressure cylinder. When repairing the oblique flange plane of the inspection window of a steam turbine low-pressure cylinder using a machine tool, the method uses a punch hole for positioning, transforming the complex spatial plane machining into a quantifiable mathematical calculation and automated machining process. Coordinate calculation is used to replace dedicated measuring equipment, simplifying the machining and repair steps of the workpiece, making the operation simple, reducing repair costs, and reducing the number of professional personnel required. This achieves the repair goals of high efficiency, high precision, and low cost. This invention can also provide guidance for similar oblique surface machining work. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the oblique flange of the inspection window of the low-pressure cylinder of a steam turbine in one embodiment of the present invention;

[0034] Figure 2 In one embodiment of the present invention, the oblique flange edge of the inspection window of the low-pressure cylinder of the steam turbine is... Figure 1 A cross-sectional view of kk;

[0035] Figure 3 This is a schematic diagram of the oblique flange of the inspection window of the low-pressure cylinder of a steam turbine according to an embodiment of the present invention;

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

[0037] Figure 5 This is a schematic diagram of angle calculation on the isometric side in one embodiment of the present invention. Detailed Implementation

[0038] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Specific Implementation Method 1

[0040] Combination Figures 1 to 5 This embodiment describes the method for repairing the oblique flange plane of the inspection window of the steam turbine low-pressure cylinder. The specific process is as follows:

[0041] Step S1: As Figure 3 As shown, draw a cross center line based on the outline of the square window of the viewing window's oblique flange. Mark four eyelets in an orthogonal symmetrical manner at a distance of 10mm from the outer edge of the square window along the direction of the cross center line.

[0042] The line connecting eyelets A and C coincides with the center line of the cross inside the outline of the oblique flange square window, and the line connecting eyelets B and D coincides with the center line of the cross inside the outline of the oblique flange square window.

[0043] In this embodiment, the distance between the eyelet and the edge of the viewing window flange is 10mm. This distance is not intended to limit the invention; in practice, other values ​​can be selected based on the specific specifications of the flange.

[0044] The edge area of ​​the square window of the angled flange may experience slight deformation due to long-term thermal expansion or mechanical vibration. The grommets, serving as a crucial reference point during the repair process, should be placed at a certain distance from the edge of the square window to avoid positioning errors caused by direct edge operations. Symmetrically punching grommets on both sides of the centerline ensures the symmetry of the repaired angled flange plane, preventing sealing leaks caused by unilateral deviation. Angled flanges typically have bolt holes; leaving sufficient distance prevents accidental damage to the bolt hole edges (such as thread threads) during the grommet process. Furthermore, after repairing the angled flange, if the viewing window or other components need to be reinstalled, leaving sufficient edge allowance provides necessary space for subsequent tool operations, preventing interference.

[0045] Step S2: As Figure 1 and Figure 3 As shown, the low-pressure cylinder of the steam turbine is fixed on the CNC boring machine table. The horizontal midpoint is taken as the XZ plane, and the vertical end face as the XY plane. Their intersection is taken as the X-axis, and the midpoint of the intersection is taken as the origin O of the coordinate system, establishing a reference coordinate system (X,Y,Z). A center is installed on the boring machine spindle and aligned sequentially with the punches A, B, C, and D. The spatial coordinates of each punch in the reference coordinate system are measured and recorded: A(x1,y1,z1), B(x2,y2,z2), C(x3,y3,z3), and D(x4,y4,z4). Based on the spatial coordinates of the four punches, the spatial coordinates O(x1,y1,z1), O(x2,y2,z2), O(x3,y3,z3), and O(x4,y4,z4) of the center point O of the oblique flange square window of the inspection window are calculated. o ,y o ,z o The specific process includes:

[0046] Take the coordinates of the midpoints of points A and C in the ocean. Next, take the coordinates of the midpoints of points B and D in the Yangchong eye. Finally, the spatial coordinates of the center point O were determined as follows:

[0047]

[0048] Step S3: Consider the peephole flange 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 center line AL of this plane by an angle β to obtain the intermediate plane E′F′G′H′; the second rotation is to rotate the intermediate plane E′F′G′H′ around its inner edge line E′F′ by an angle α; with the center point O(xo ,y o ,z o The zero point for workpiece machining is set as β and α. A CNC program is written using angles β and α. The CNC program is then input into the CNC system of the boring machine to generate a milling program.

[0049] Specifically, the steps for determining angles β and α include:

[0050] like Figure 4 and Figure 5 As shown, the spatial plane of the low-pressure cylinder can be decomposed into a reference plane EFGH, which is the region enclosed by points E, F, G, and H. The reference plane is rotated by an angle β around its centerline AL to adjust its horizontal tilt, transforming it into the intermediate plane E′F′G′H′. Then, the intermediate plane E′F′G′H′ is rotated by an angle α along the straight line E′F′, transforming it into the target spatial plane, which is the spatial plane where the turbine's low-pressure cylinder inspection window is located, i.e., the region enclosed by E′, F′, G″, and H″. The process of transforming the intermediate plane E′F′G′H′ into the target spatial plane is called... Figure 2 The process of rotating the oblique flange of the central viewing window by an angle α along KK. Taking point A as an example, connecting points A and O can determine the diagonal AO of the spatial cuboid, and the reference plane is the upper plane of the spatial cuboid in the XZ coordinate plane.

[0051] The specific steps for determining angle β include:

[0052]

[0053] The specific steps for determining angle α include:

[0054]

[0055] With center point O(x) o ,y o ,z o The zero point for workpiece machining is set as β and α. A CNC program is written using angles β and α. The CNC program is then input into the CNC system of the boring machine to generate a milling program.

[0056] Step S4: Compare and verify the coordinate system in the milling program with the coordinate system of the actual workpiece. If the verification is consistent, use the milling program to perform milling repair on the surface of the peephole flange. If the verification is inconsistent, adjust the angle of the universal milling head of the boring machine before performing milling repair on the surface of the peephole flange.

[0057] Specifically, the steps for comparing and verifying the machine tool program coordinate system and the workpiece plane coordinate system include:

[0058] S411: Install a dial indicator on the universal milling head of the boring machine, ensuring that the probe of the dial indicator is perpendicular to the flange surface and lightly touches the flange surface;

[0059] S412: Start the CNC system and make the universal milling head move a straight path along the edge of the flange plane parallel to the cross center line;

[0060] S413: During the movement of the milling head, observe the dial indicator pointer. 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 deviates, it proves that the machine tool program coordinate system and the workpiece plane coordinate system are inconsistent.

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

[0062] S421: A large-size face milling cutter is added to the spindle, with the cutter face covering four punch holes;

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

[0064] S423: Measure the clearance distance between the milling cutter and the flange plane at the four punch positions using gauge blocks;

[0065] S424: By adjusting the A-axis and C-axis of the universal milling head, the clearance distance between the face milling cutter and the flange plane at the above four positions is made consistent, and the angle adjustment of the universal milling head is completed;

[0066] S425: Record the adjusted angles of the A-axis and C-axis, and rewrite the CNC program using these two angle values.

[0067] 20mm gauge blocks are a common standard specification in the machining industry. They are easy to purchase and inexpensive, eliminating the need for customized special measuring tools and lowering the threshold for process implementation. They are compatible with the probe stroke and fixture opening and closing space of CNC boring machines, avoiding interference caused by excessively large gauge blocks or positioning difficulties caused by excessively small gauge blocks. Their moderate weight makes it easy for fitters to manually place and adjust them, reducing labor intensity.

[0068] If the screw holes are misaligned during the installation of the peephole cover, use a drill bit to enlarge the hole in the direction of the misalignment. This operation will not affect the installation and use.

[0069] As can be seen from the above embodiments, this application discloses a method for repairing the oblique flange plane of the inspection window of a steam turbine low-pressure cylinder. In this application, a perforated eyelet positioning method is used to transform complex spatial plane machining into a quantifiable mathematical calculation and automated machining process. Coordinate calculation is used to replace dedicated measuring equipment, simplifying the machining and repair steps of the workpiece, making the operation simple, reducing repair costs, and reducing the need for professional personnel. This achieves the repair goals of high efficiency, high precision, and low cost. This invention can also provide guidance for similar oblique surface machining work.

[0070] The above embodiments of the present invention are merely illustrative of the operational process of the present invention and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description; it is impossible to exhaustively list all embodiments here. Any obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A method for repairing the oblique flange plane of the inspection window of a steam turbine low-pressure cylinder, characterized in that, Includes the following steps: Step S1: Using the outline of the square window of the viewing window's angled flange as a reference, draw a cross center line. Along the direction of the cross center line, at a predetermined distance from the outer edge of the square window, mark four eyelets in an orthogonal and symmetrical manner. ; Step S2: Fix the low-pressure cylinder of the steam turbine onto the CNC boring machine table. Take the horizontal mid-plane as the XZ plane and the vertical end face as the XY plane. Take their intersection as the X-axis and the midpoint of the intersection as the origin of the coordinate system. Establish a reference coordinate system Centers are installed on the boring machine spindle and aligned sequentially with the punch holes. Measure and record the spatial coordinates of each ocean vent in the reference coordinate system. , , , Based on the spatial coordinates of the four ocean-viewing eyes, calculate the center point of the oblique flange square window of the viewing window. spatial coordinates ; Step S3: Treat the viewing window angled flange as a spatial plane, which is obtained by rotating the reference plane twice; the first rotation is to rotate the reference plane... Around the reference plane rotation angle of the plane midline AL Obtain the intermediate plane The second rotation is to rotate the middle plane. The edge around its interior Rotation angle ; With the center point To machine the zero point of the workpiece, use , Write a CNC program at an angle, input the CNC program into the CNC system of the boring machine, and generate a milling program; Step S4: Compare and verify the coordinate system in the milling program with the coordinate system of the actual workpiece. If the verification is consistent, use the milling program to perform milling repair on the surface of the peephole flange. If the verification is inconsistent, adjust the angle of the universal milling head of the boring machine before performing milling repair on the surface of the peephole flange.

2. The method for repairing the oblique flange plane of the inspection window of a steam turbine low-pressure cylinder according to claim 1, characterized in that, In step S1, the four ocean eyes are marked in an orthogonal symmetrical manner. Specifically: Yangchongyan The connecting line coincides with the center line of the cross inside the outline of the angled flange square window, and the eyelet is... The connecting line coincides with the center line of the cross inside the outline of the angled flange square window.

3. The method for repairing the oblique flange plane of the inspection window of the steam turbine low-pressure cylinder according to claim 2, characterized in that, In step S1, Yangchongyan The distance between the window and the outer edge of the square window is 10-12mm.

4. The method for repairing the oblique flange plane of the inspection window of a steam turbine low-pressure cylinder according to claim 3, characterized in that, In step S2, the center point of the oblique flange square window of the viewing window is calculated. spatial coordinates The specific steps include: Take foreign eye midpoint coordinates Then take the foreign eye Midpoint coordinates Finally, the center point was determined. Spatial coordinates are .

5. The method of claim 4, wherein, The angle mentioned in step S3 The method for determining it is as follows: 。 6. The method for repairing the oblique flange plane of the inspection window of a steam turbine low-pressure cylinder according to claim 5, characterized in that, The angle in step S3 The determination method is as follows: 。 7. The method of claim 6, wherein, 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, ensuring that the probe of the dial indicator is perpendicular to the flange surface and lightly touches the flange surface; S412: Start the CNC system and make the universal milling head move a straight path along the edge of the flange plane parallel to the cross center line; S413: During the movement of the milling head, observe the dial indicator pointer. 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 deviates, it proves that the machine tool program coordinate system and the workpiece plane coordinate system are inconsistent.

8. The method of claim 7, wherein, The specific steps for adjusting the universal milling head in step S4 include: S421: A large-size face milling cutter is added to the spindle, with the cutter face covering four punch holes; S422: Adjust the Z-axis according to the rotated coordinate system; S423: Measure the clearance distance between the milling cutter and the flange plane at the four punch positions using gauge blocks; S424: By adjusting the universal milling head shaft and The shaft is adjusted so that the clearance distance between the milling cutter and the flange plane at the above four positions is consistent, and the angle of the universal milling head is adjusted. S425: Record after adjustment axis, The angle of the axis; rewrite the CNC program using these two angle values.

9. The method for repairing the oblique flange plane of the inspection window of a steam turbine low-pressure cylinder according to claim 8, characterized in that, The gauge blocks used in the process of comparing and verifying the machine tool program coordinate system and the workpiece plane coordinate system are 20mm in size.

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