A method for cutting a window line of a sleeve of a sliding valve based on a trial cutting mode

Abstract

A kind of sliding valve sleeve window linear cutting processing method based on trial cutting mode, it relates to a kind of sliding valve sleeve window linear cutting processing method.To solve the problem of machining error caused by discharge gap and wire error when linear cutting processing window of turbine sliding valve sleeve in prior art, the method is as follows: the present application successively carries out drilling wire hole, linear cutting trial processing window, detects window actual size, analyzes wire error and actual discharge gap, corrects linear cutting program, corrects wire position, linear cutting processes accurate window, in the step of trial processing window, wire error and actual discharge gap can be obtained, then linear cutting program is corrected using wire error and actual discharge gap, avoid the problem of machining error caused by wire inaccuracy, diameter deviation of electrode wire, material difference of sleeve and other factors, which leads to difference between actual discharge gap and theoretical discharge gap data during linear cutting, and wire error, so that sleeve window with qualified size can be obtained.

Description

Technical Field

[0001] This invention relates to a method for wire cutting the window of a slide valve sleeve. Background Technology

[0002] The slide valve sleeve in the steam turbine has a multi-row window structure. The window size and inter-window dimensions require high precision, with a tolerance of 0.05mm. The windows of the slide valve sleeve play a crucial role in sealing oil, making their dimensions critical. Originally, the slide valve sleeve windows were machined using wire EDM, programmed according to the dimensional tolerances on the drawings and the empirical values ​​of the discharge gap for the material. However, this method frequently resulted in out-of-tolerance issues with the window size and inter-window dimensions, leading to sleeve scrap. The main reasons were inaccurate wire alignment or deviations in wire diameter during sleeve machining, causing machining errors. Additionally, slight differences in the material of each sleeve resulted in a different discharge gap during wire EDM compared to the theoretical data, ultimately leading to out-of-tolerance issues in the finished product. Based on the analysis and research of these problems, a trial-cut machining method was adopted to determine the actual discharge gap and wire alignment errors, correct the program, and successfully machine sleeve windows with acceptable dimensions. Summary of the Invention

[0003] To address the machining errors caused by discharge gap and wire alignment errors when machining the window of a turbine valve sleeve using wire EDM, this invention proposes a wire EDM machining method for valve sleeve windows based on trial cutting.

[0004] The wire cutting method for machining the valve sleeve window based on trial cutting of the present invention is carried out according to the following steps:

[0005] 1. Drilling through-wire holes: Use a coordinate boring machine to drill through-wire holes at the center of each window of the slide valve sleeve, and insert electrode wires into the through-wire holes;

[0006] 2. Wire EDM trial machining window: Use a fixture to clamp and align the slide valve sleeve. Use the left end face of the sleeve as the wire alignment reference surface to perform wire EDM. After wire alignment, record the wire alignment point position data on the machine tool. Wire EDM is performed in the largest area to be machined on the slide valve sleeve to obtain a small window.

[0007] 3. Check the actual size of the small window: Remove the sliding valve sleeve, but do not remove the tooling. Measure the actual axial dimension Ls of the right side of the small window from the reference surface of the wire; measure the width A and length B of the small window.

[0008] IV. Analysis of wire alignment error and actual discharge gap:

[0009] The discharge gap λ1 in the width direction and the discharge gap λ2 in the length direction of the electrode wire are calculated according to Formula 1 and Formula 2:

[0010] λ1=(Aa-φs ) / 2; (Formula 1)

[0011] λ2=(Bb-φ s ) / 2; (Formula 2)

[0012] In Formulas 1 and 2, A—discharge gap in the width direction of the electrode wire, mm; B—discharge gap in the length direction of the electrode wire, mm; a—theoretical width programmed for small window wire EDM, mm; b—theoretical length programmed for small window wire EDM, mm; φ s — Diameter of molybdenum wire, mm;

[0013] The wire error ε is calculated according to formula 3:

[0014] ε=L c -L s ;(Formula 3)

[0015] In Formula 3, L c —The theoretical distance from the wire point to the right edge of the small window, in mm; L s —Measured distance from the wire point to the right side of the small window, mm;

[0016] V. Correcting the wire EDM program: The simplified wire EDM program diagram is corrected by using the discharge gap λ1 in the width direction of the electrode wire and the discharge gap λ2 in the length direction of the electrode wire, and the wire EDM program is rewritten to obtain an accurate and true wire EDM program.

[0017] VI. Correcting wire alignment position: Adjusting the position of the molybdenum wire using the wire alignment error ε to eliminate axial error;

[0018] 7. Wire EDM Processing Window: When re-processing the sleeve, re-clamp and position it. Use a feeler gauge to check the contact between the right end face of the sleeve and the tooling to ensure the axial reset accuracy of the sleeve during the second clamping. Use the modified wire EDM program for processing.

[0019] The present invention has the following beneficial effects:

[0020] This invention provides a wire EDM machining method for valve sleeve windows based on a trial cutting approach. The method involves sequentially drilling the wire hole, wire EDM trial machining of the window, detecting the actual window size, analyzing wire alignment error and actual discharge gap, correcting the wire EDM program, correcting the wire alignment position, and wire EDM machining of the final window. During the trial machining step, the wire alignment error and actual discharge gap can be obtained. These errors are then used to correct the cutting program, avoiding problems such as discrepancies between the actual and theoretical discharge gaps caused by inaccurate wire alignment, electrode wire diameter deviations, and sleeve material differences, as well as machining errors caused by wire alignment errors. This method yields a sleeve window with acceptable dimensions. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the existing slide valve sleeve.

[0022] Figure 2 This is a schematic diagram illustrating the wire EDM machining principle of the valve sleeve window based on the trial cutting method in Example 1. Figure 1 ;

[0023] Figure 3 This is a schematic diagram illustrating the wire EDM machining principle of the valve sleeve window based on the trial cutting method in Example 1. Figure 2 . Detailed Implementation

[0024] The technical solution of the present invention is not limited to the specific embodiments listed below, but also includes any reasonable combination of the specific embodiments.

[0025] Specific Implementation Method 1: This implementation method, based on a trial-cutting approach, involves wire cutting of the valve sleeve window according to the following steps:

[0026] 1. Drilling through-wire holes: Use a coordinate boring machine to drill through-wire holes at the center of each window of the slide valve sleeve, and insert electrode wires into the through-wire holes;

[0027] 2. Wire EDM trial machining window: Use a fixture to clamp and align the slide valve sleeve. Use the left end face of the sleeve as the wire alignment reference surface to perform wire EDM. After wire alignment, record the wire alignment point position data on the machine tool. Wire EDM is performed in the largest area to be machined on the slide valve sleeve to obtain a small window.

[0028] 3. Check the actual size of the small window: Remove the sliding valve sleeve, but do not remove the tooling. Measure the actual axial dimension Ls of the right side of the small window from the reference surface of the wire; measure the width A and length B of the small window.

[0029] IV. Analysis of wire alignment error and actual discharge gap:

[0030] The discharge gap λ1 in the width direction and the discharge gap λ2 in the length direction of the electrode wire are calculated according to Formula 1 and Formula 2:

[0031] λ1=(Aa-φ s ) / 2; (Formula 1)

[0032] λ2=(Bb-φ s ) / 2; (Formula 2)

[0033] In Formulas 1 and 2, A—discharge gap in the width direction of the electrode wire, mm; B—discharge gap in the length direction of the electrode wire, mm; a—theoretical width programmed for small window wire EDM, mm; b—theoretical length programmed for small window wire EDM, mm; φ s — Diameter of molybdenum wire, mm;

[0034] The wire error ε is calculated according to formula 3:

[0035] ε=L c -L s ;(Formula 3)

[0036] In Formula 3, L c —The theoretical distance from the wire point to the right edge of the small window, in mm; L s —Measured distance from the wire point to the right side of the small window, mm;

[0037] V. Correcting the wire EDM program: The simplified wire EDM program diagram is corrected by using the discharge gap λ1 in the width direction of the electrode wire and the discharge gap λ2 in the length direction of the electrode wire, and the wire EDM program is rewritten to obtain an accurate and true wire EDM program.

[0038] VI. Correcting wire alignment position: Adjusting the position of the molybdenum wire using the wire alignment error ε to eliminate axial error;

[0039] 7. Wire EDM Processing Window: When re-processing the sleeve, re-clamp and position it. Use a feeler gauge to check the contact between the right end face of the sleeve and the tooling to ensure the axial reset accuracy of the sleeve during the second clamping. Use the modified wire EDM program for processing.

[0040] This embodiment has the following beneficial effects:

[0041] This embodiment of the wire EDM machining method for valve sleeve windows based on trial cutting involves the following steps: drilling through the wire hole, wire EDM trial machining of the window, checking the actual size of the window, analyzing wire alignment error and actual discharge gap, correcting the wire EDM program, correcting the wire alignment position, and wire EDM machining of the window. In the trial machining window step, the wire alignment error and actual discharge gap can be obtained. Then, the cutting program is corrected using the wire alignment error and actual discharge gap. This avoids problems such as inaccurate wire alignment, deviation in electrode wire diameter, and differences in sleeve material, which cause the actual discharge gap to differ from the theoretical discharge gap data during wire EDM, as well as machining errors caused by wire alignment error. This method can obtain a sleeve window with qualified dimensions.

[0042] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that: in step two, the edge of the small window obtained by wire cutting and the edge of the largest window to be processed in the slide valve sleeve are reserved for processing allowance.

[0043] Specific Implementation Method 3: This implementation method differs from Specific Implementation Method 1 or 2 in that the axial dimension Ls mentioned in step 3 is measured by a coordinate measuring machine.

[0044] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that the width A and length B of the small window described in step three are measured using a micrometer and gauge blocks.

[0045] Specific Implementation Method Five: This implementation method differs from one of the specific implementation methods one to four in that the derivation of ε is carried out according to Formula 4;

[0046] L c +λ1+φ s / 2=L s +ε+λ1+φ s / 2. (Formula 4)

[0047] Specific Implementation Method Six: This implementation method differs from one of the specific implementation methods one to five in that the electrode wire described in step one is a molybdenum wire.

[0048] Example 1:

[0049] This embodiment describes a wire EDM machining method for a valve sleeve window based on a trial cutting approach, which is performed according to the following steps:

[0050] 1. Drilling through-wire holes: Use a coordinate boring machine to drill through-wire holes at the center of each window of the slide valve sleeve, and insert electrode wires into the through-wire holes;

[0051] The electrode wire is a molybdenum wire;

[0052] 2. Wire EDM Trial Machining Window: Clamp and align the slide valve sleeve using a tooling. Use the left end face of the sleeve as the wire alignment reference surface for wire alignment. After wire alignment, record the wire alignment point position data on the machine tool. Wire EDM a small window within the largest area to be machined on the slide valve sleeve. The edge of the small window obtained by wire EDM and the edge of the largest area to be machined on the slide valve sleeve are reserved for machining allowance.

[0053] 3. Inspect the actual size of the small window: Remove the sliding valve sleeve, but do not remove the tooling. Measure the actual axial dimension Ls of the right side of the small window from the reference plane; measure the width A and length B of the small window; the axial dimension Ls is measured using a coordinate measuring machine; the width A and length B of the small window are measured using a micrometer and gauge blocks.

[0054] IV. Analysis of wire alignment error and actual discharge gap:

[0055] The discharge gap λ1 in the width direction and the discharge gap λ2 in the length direction of the electrode wire are calculated according to Formula 1 and Formula 2:

[0056] λ1=(Aa-φ s ) / 2; (Formula 1)

[0057] λ2=(Bb-φs ) / 2; (Formula 2)

[0058] In Formulas 1 and 2, A—discharge gap in the width direction of the electrode wire, mm; B—discharge gap in the length direction of the electrode wire, mm; a—theoretical width programmed for small window wire EDM, mm; b—theoretical length programmed for small window wire EDM, mm; φ s — Diameter of molybdenum wire, mm;

[0059] The wire error ε is calculated according to formula 3:

[0060] ε=L c -L s ;(Formula 3)

[0061] In Formula 3, L c —The theoretical distance from the wire point to the right edge of the small window, in mm; L s —Measured distance from the wire point to the right side of the small window, mm;

[0062] The derivation of ε is performed according to Formula 4;

[0063] L c +λ1+φ s / 2=L s +ε+λ1+φ s / 2; (Formula 4)

[0064] V. Correcting the wire EDM program: The simplified wire EDM program diagram is corrected by using the discharge gap λ1 in the width direction of the electrode wire and the discharge gap λ2 in the length direction of the electrode wire, and the wire EDM program is rewritten to obtain an accurate and true wire EDM program.

[0065] VI. Correcting wire alignment position: Adjusting the position of the molybdenum wire using the wire alignment error ε to eliminate axial error;

[0066] 7. Wire EDM Processing Window: When re-processing the sleeve, re-clamp and position it. Use a feeler gauge to check the contact between the right end face of the sleeve and the tooling to ensure the axial reset accuracy of the sleeve during the second clamping. Use the modified wire EDM program for processing.

[0067] This embodiment uses a trial-cutting method for wire cutting the valve sleeve window. The process involves drilling the wire hole, wire cutting the window, checking the actual window size, analyzing the wire alignment error and actual discharge gap, correcting the wire cutting program, correcting the wire alignment position, and finally wire cutting the window. In the trial-cutting window step, the wire alignment error and actual discharge gap can be obtained. Then, the cutting program is corrected using the wire alignment error and actual discharge gap. This avoids problems such as inaccurate wire alignment, deviations in the diameter of the electrode wire, and differences in the sleeve material, which can cause the actual discharge gap to differ from the theoretical discharge gap during wire cutting, as well as processing errors caused by wire alignment errors. This method can produce a sleeve window with acceptable dimensions.

Claims

1. A wire cutting method for machining a slide valve sleeve window based on trial cutting, characterized in that: The wire EDM machining method for valve sleeve windows based on trial cutting is carried out according to the following steps:

1. Drilling through-wire holes: Use a coordinate boring machine to drill through-wire holes at the center of each window of the slide valve sleeve, and insert electrode wires into the through-wire holes; 2. Wire EDM trial machining window: Use a fixture to clamp and align the slide valve sleeve. Use the left end face of the sleeve as the wire alignment reference surface to perform wire EDM. After wire alignment, record the wire alignment point position data on the machine tool. Wire EDM is performed in the largest area to be machined on the slide valve sleeve to obtain a small window.

3. Check the actual size of the small window: Remove the sliding valve sleeve, but do not remove the tooling. Measure the actual axial dimension Ls of the right side of the small window from the reference surface of the wire; measure the width A and length B of the small window. IV. Analysis of wire alignment error and actual discharge gap: The discharge gap λ1 in the width direction and the discharge gap λ2 in the length direction of the electrode wire are calculated according to Formula 1 and Formula 2: λ1 = (A - a - φ s ) / 2; (Equation 1) λ2=(Bb-φ s ) / 2; (Formula 2) In Formulas 1 and 2, A—discharge gap in the width direction of the electrode wire, mm; B—discharge gap in the length direction of the electrode wire, mm; a—theoretical width programmed for small window wire EDM, mm; b—theoretical length programmed for small window wire EDM, mm; φ s —Electrode wire diameter, mm; The wire error ε is calculated according to formula 3: ε=L c -L s ;(Formula 3) In Formula 3, L c —The theoretical distance from the wire point to the right edge of the small window, in mm; L s —Measured distance from the wire point to the right side of the small window, mm; V. Correcting the wire EDM program: The simplified wire EDM program diagram is corrected by using the discharge gap λ1 in the width direction of the electrode wire and the discharge gap λ2 in the length direction of the electrode wire, and the wire EDM program is rewritten to obtain an accurate and true wire EDM program. VI. Correcting the wire alignment position: Adjust the electrode wire position using the wire alignment error ε to eliminate axial error; 7. Wire EDM machining window: When re-machining the sleeve, re-clamp and position it. Use a feeler gauge to check the contact between the right end face of the sleeve and the tooling to ensure the axial reset accuracy of the sleeve during the second clamping. Use the modified wire EDM program for machining. The axial dimension Ls mentioned in step three is measured by a coordinate measuring machine; The width A and length B of the small window described in step three are measured using a micrometer and gauge blocks.

2. The wire cutting method for valve sleeve window based on trial cutting as described in claim 1, characterized in that: In step two, the edge of the small window obtained by wire cutting and the edge of the largest window to be processed in the valve sleeve are reserved for machining allowance.

3. The wire cutting method for valve sleeve window based on trial cutting as described in claim 1, characterized in that: The derivation of ε is performed according to Formula 4; L c +λ1+φ s / 2=L s +ε+λ1+φ s / 2 (Equation 4).

4. The wire cutting method for valve sleeve window based on trial cutting as described in claim 1, characterized in that: The electrode wire mentioned in step one is a molybdenum wire.

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