An in-situ eddy current method for measuring the wall thickness of an aero-engine turbine support shroud.

Abstract

This invention discloses an in-situ eddy current thickness measurement method for the turbine support cowling wall thickness of an aero-engine. A comparative sample is fabricated; a line is marked on the polished inlet front edge, and each mark is sequentially measured using CT and recorded as d2. The thickness d2 value of the rear half of the comparative sample at the 1 / 2 position of the plate wall thickness is marked and recorded as the original plate thickness H; the frequency f of the plate thickness H is calculated, and the parameters of the eddy current flaw detector are adjusted so that the flaw detection frequency is less than the frequency f; an impedance diagram is determined; the eddy current flaw detector parameters are adjusted again so that the gate alarm frame amplitude value is located at the 1 / 2 position of the plate wall thickness, and the parameters are saved and the file name is labeled; then a correspondence table is created to match the thickness d2 value with the position of the impedance diagram amplitude point; the thickness of the inlet flange of the part is measured by opening the file from step 5 and adjusting the parameters of the eddy current flaw detector. This method is fast and accurate, fully utilizes the functions of the eddy current flaw detector, and solves the problem that conventional ultrasonic thickness measurement cannot measure the thickness.

Description

Technical Field

[0001] This invention belongs to the field of aerospace technology, specifically relating to an in-situ eddy current method for measuring the wall thickness of an aero-engine turbine support shroud. Background Technology

[0002] Currently, during the manufacturing process of aero-engine turbine support cowlings, sheet metal needs to be bent into the shape of the part, then uneven areas are ground off and polished to make the inlet front edge of the turbine support cowling a smooth arc. Wall thickness measurement is not required; it is directly welded and installed onto the turbine support housing. However, due to issues such as extrusion damage and over-grinding during the bending process, the inlet front edge of the turbine support cowling is prone to cracking during use, potentially leading to engine failure. Therefore, measurements need to be taken on the finished turbine support part to determine if the wall thickness of the inlet front edge of the turbine support cowling meets the requirements. Since the inner cavity is closed, traditional caliper measurement methods are ineffective, and ultrasonic thickness measurement methods are also difficult to use for cases where the internal bottom surface is not flat, such as those involving extrusion damage.

[0003] Chinese invention patent CN102620625B discloses a rapid detection tool and method for the axial dimension of the opening edge of an aircraft fairing. The method uses a lower detection step shaft to detect the axial dimension of the opening edge after the aircraft fairing 2 has been trimmed: the lower positioning shaft 1d of the lower detection step shaft is pressed tightly against the end face of the trimming fixture 3. At this time, a gap δ3 appears between the lower detection shaft 1e of the lower detection step shaft and the end face of the aircraft fairing 2. The lower positioning shaft 1d is then wrapped around the end face of the trimming fixture 3, and the gap δ3 is measured using a feeler gauge. If 0.3mm < δ3 < 0.5mm, the axial dimension of the opening edge after the aircraft fairing 2 has been trimmed is acceptable; if δ3 ≤ 0.3mm or 0.5mm ≤ δ3, the axial dimension of the opening edge after the aircraft fairing 2 has been trimmed is unacceptable. This method uses auxiliary tools, making the detection cumbersome.

[0004] Therefore, a wall thickness measurement method is needed that can be measured from the outside and is not affected by the shape of the bottom surface, so as to quickly determine whether the wall thickness of the turbine support fairing at the air inlet front meets the requirements. Summary of the Invention

[0005] To address the aforementioned problems, this invention aims to provide an in-situ eddy current thickness measurement method for the turbine support shroud wall thickness of an aero-engine.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: an in-situ eddy current thickness measurement method for the turbine support shroud wall thickness of an aero-engine, comprising the following steps.

[0007] Step 1: Process and manufacture a comparison sample. The comparison sample has a recessed air inlet flange. The maximum depth of the recess is greater than 1 / 2 of the wall thickness of the raw material plate.

[0008] Step 2: Grind and polish the front half of the front end of the comparison sample according to the processing technology. Draw a line mark on the front edge of the air intake after grinding and polishing, and record the thickness of each mark as d2 by CT measurement. Mark the position of 1 / 2 of the plate wall thickness and record the thickness d2 of the rear half of the comparison sample as the original plate thickness H.

[0009] Step 3: Calculate the frequency f of the plate thickness H and adjust the parameters of the eddy current flaw detector so that the flaw detection frequency is less than the frequency f;

[0010] Step 4: Determine the impedance diagram. Position "A" is the zero point. Values ​​above "A" are positive, and values ​​below "A" are negative. Position "A" is determined as follows: Couple the eddy current probe to any point near the rear end of the comparison sample, and press the "balance" button on the eddy current flaw detector to make the amplitude point of the impedance diagram of the eddy current flaw detector located at the zero point "A" of the impedance diagram.

[0011] Step 5: Readjust the eddy current flaw detector parameters so that the gate alarm frame amplitude value is located at 1 / 2 of the plate wall thickness. Save the parameters and label the file name. Then create a correspondence table to match the thickness d2 value with the position of the impedance diagram amplitude point.

[0012] Step 6: Measure the thickness of the air inlet flange of the part. Open the file from Step 5 and adjust the parameters of the eddy current flaw detector to measure the thickness of the air inlet flange of the part.

[0013] Preferably, d2 uses Arabic numerals or English letters as its marking method.

[0014] The in-situ eddy current thickness measurement method for the turbine support shroud wall thickness of an aero-engine, as described in claim 1, is characterized in that the material of the comparative sample 2 is a high-temperature alloy.

[0015] Preferably, in step 2, the grinding process ensures that the air inlet front edge of the comparison sample meets the requirements of the design drawings; the rear half of the comparison sample is not ground or polished, remaining in its original state as a raw material.

[0016] Preferably, the frequency f of the plate thickness H in step 3 is obtained as follows: first, the conductivity of the plate material used in the comparison sample is measured using a conductivity meter, or the conductivity is found in the material manual of the plate material used, and then the frequency f of the plate thickness H is calculated according to the eddy current standard penetration depth formula.

[0017] Preferably, in step 4, after determining the zero point "A" position, the eddy current probe is coupled to the front end of the comparison sample 2, the gain value of the eddy current flaw detector is adjusted so that the amplitude point of the impedance diagram of the eddy current flaw detector is at most full screen and does not exceed the display screen, the phase value is adjusted so that the amplitude point display is rotated to the vertical direction, that is, the amplitude point is located in the vertical axis direction of the impedance diagram, and the positions are recorded respectively. The "A" position is the zero point, the number above the "A" position is positive, and the number below the "A" position is negative.

[0018] Preferably, step 6 is performed as follows: The eddy current probe is coupled to any point near the rear end of the comparison sample. The "balance" button on the eddy current flaw detector is pressed so that the amplitude point of the impedance diagram is located at position "A" (zero point). Then, the eddy current probe is coupled to the air inlet flange of the part. The impedance diagram is observed. If the amplitude point is above position "A", it indicates that the wall thickness at that position is greater than the wall thickness at the rear end of the comparison sample 2. If the amplitude point is below position "A", it indicates that the wall thickness at that position is less than the wall thickness at the rear end of the comparison sample 2. This is recorded. If the amplitude point is below the alarm frame, the wall thickness at that position is unqualified.

[0019] Preferably, after the measurement is completed, the eddy current probe needs to be coupled to any point near the rear end of the comparison sample, and the amplitude point of the eddy current flaw detector impedance chart needs to be observed to see if it is located at the zero point "A" of the impedance chart. If not, step 6 needs to be repeated.

[0020] Compared with the prior art, the present invention has the following advantages: by using existing eddy current flaw detection equipment and eddy current probe, it can measure from the front edge of the turbine support fairing air intake, and is not affected by the bottom surface shape, so as to improve the detection efficiency and reduce the scrap of parts by judging whether the wall thickness meets the requirements. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the specific embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the comparative sample of the present invention;

[0023] Figure 2 This is a schematic diagram of the parts of the present invention;

[0024] Figure 3 This is a schematic diagram of an impedance diagram.

[0025] In the diagram, 1-part; 2-comparison sample; 3-air intake flange; 4-marker; 5-front end; 6-rear end. Detailed Implementation

[0026] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, it should not be construed that the scope of the subject matter of the present invention is limited to the following embodiments. All modifications, substitutions and alterations made based on ordinary technical knowledge and common practices in the art without departing from the above-described technical concept of the present invention are included within the scope of the present invention.

[0027] Reference Figure 1-3 An in-situ eddy current method for measuring the wall thickness of an aero-engine turbine support shroud is described below, including the following measurement method and steps:

[0028] 1. Fabricate comparison sample 2. For comparison sample 2, select a part with a deep extrusion damage on the air intake edge 3. First, visually inspect the degree of extrusion damage. The deepest point of the depression should be greater than 1 / 2 of the wall thickness of the raw material plate. Otherwise, additional extrusion is required to make the deepest point of the depression greater than 1 / 2 of the wall thickness of the raw material plate. Then, grind and polish the front half of the front end 5 according to the processing technology. Grind to make the air intake front edge of comparison sample 2 meet the requirements of the design drawings. The rear half of the rear end 6 is not ground or polished, and remains in the original state of the raw material plate. Then, draw lines and marks on the air intake front edge of comparison sample 2, and mark 4 in the order of "1", "2", "3"... Then, perform CT thickness measurement on comparison sample 2 and record the thickness d2 value at different positions of "1", "2", "3"... of the marking 4. At the same time, mark the plate wall thickness 1 / 2 position, and the thickness d2 value at the positions of "6", "7", "8"... is the original plate thickness H.

[0029] 2. Calculate the standard penetration depth of eddy current testing. First, use a conductivity meter to measure the conductivity of the plate material used in the comparison sample 2, or find the conductivity according to the material manual of the plate material. Then, calculate the frequency f of the plate thickness H according to the formula for standard penetration depth of eddy current testing.

[0030] 3. Adjust the parameters of the eddy current flaw detector so that the flaw detection frequency is less than the frequency f with the standard penetration depth based on the plate thickness H.

[0031] 4. Couple the eddy current probe to any of the positions "6", "7", "8"... on the comparison sample 2. Press the "balance" button on the eddy current flaw detector to make the amplitude point of the impedance diagram of the eddy current flaw detector located at the zero point "A" of the impedance diagram. Then couple the eddy current probe to the positions "1", "2", "3", "4"... on the comparison sample 2 respectively. Adjust the gain value of the eddy current flaw detector so that the amplitude point of the impedance diagram is at most full screen and does not exceed the display screen. Adjust the phase value so that the amplitude point display rotates to the vertical direction, that is, the amplitude points "B", "C", "D", etc. are located in the vertical axis of the impedance diagram. Record the positions respectively. The position "A" is the zero point. The value above the position "A" is positive and the value below the position "A" is negative.

[0032] 5. Readjust the eddy current flaw detector parameters so that the gate alarm frame amplitude value is located at 1 / 2 of the plate wall thickness. Save the parameters and label the file name.

[0033] 6. Create a mapping table to match the thickness d2 value with the position of the impedance map amplitude point.

[0034] 7. To measure the thickness of the air inlet flange 3 of part 1, first adjust the parameters, then couple the eddy current probe to any of the positions "6", "7", "8"... on the comparison sample 2. Press the "balance" key on the eddy current flaw detector to make the amplitude point of the impedance diagram of the eddy current flaw detector located at the zero point "A" of the impedance diagram. Then couple the eddy current probe to the air inlet flange 3 of part 1 and observe the impedance diagram display. If the amplitude point is above position "A", it means that the wall thickness at this position is greater than the wall thickness at positions "6", "7", "8"... on the comparison sample 2. If the amplitude point is below position "A", it means that the wall thickness at this position is less than the wall thickness at positions "6", "7", "8"... on the comparison sample 2. This should be recorded. If the amplitude point is below the alarm box, the wall thickness at this position is unqualified.

[0035] 8. After the measurement is completed, the eddy current probe needs to be coupled to any of the positions "6", "7", "8"... on the comparison sample 2, and observe whether the amplitude point of the impedance diagram of the eddy current flaw detector is located at the zero point "A" of the impedance diagram. If not, step 7 needs to be repeated.

[0036] An embodiment of an in-situ eddy current thickness measurement method for the turbine support shroud of an aero-engine is provided, and the measurement method and steps are as follows:

[0037] Comparison Sample 2 was fabricated using a high-temperature alloy. The sample was made from a part with a deep extrusion scratch on the air intake edge 3. The extent of the scratch was first visually assessed; the deepest depression should be greater than half the wall thickness of the raw material sheet. Otherwise, further extrusion was required to ensure the deepest depression was greater than half the wall thickness. Then, the front half of the front end 5 was ground and polished according to the processing procedure. Grinding ensured the air intake front edge of Comparison Sample 2 met the design drawings. The rear half of the rear end 6 was left unpolished, retaining the original state of the raw material sheet. Lines were then drawn on the air intake front edge of Comparison Sample 2, and markings were made in the order of "1", "2", "3", etc., to create markings 4. The thickness of Comparison Sample 2 was then measured using CT, and the thickness d2 values ​​at different positions of marking 4 ("1", "2", "3", etc.) were recorded. Simultaneously, the thickness d2 values ​​at positions marked with half the sheet wall thickness ("6", "7", "8", etc.) were recorded as the original sheet thickness of 1.2 mm.

[0038] 2. Calculate the standard penetration depth of eddy current testing. First, use a conductivity meter to measure the conductivity of the plate material used for comparison sample 2, which is 0.65 MS / m. Calculate the frequency f of the standard penetration depth with a plate thickness H of 1.2 mm according to the eddy current standard penetration depth formula, which is approximately 266 kHz.

[0039] 3. Adjust the parameters of the eddy current flaw detector to make the flaw detection frequency 200KHz, which is less than the frequency of 266KHz for the standard penetration depth with a plate thickness H of 1.2mm.

[0040] 4. Couple the eddy current probe to position "8" of the comparison sample 2, press the "balance" button on the eddy current flaw detector to make the amplitude point of the impedance diagram of the eddy current flaw detector located at position "A" of the zero point of the impedance diagram. Then couple the eddy current probe to positions "1", "2", "3", "4"... of the comparison sample 2 respectively. Adjust the gain value of the eddy current flaw detector so that the amplitude point of the impedance diagram of the eddy current flaw detector is at most full screen and does not exceed the display screen. Adjust the phase value so that the amplitude point display rotates to the vertical direction, that is, the amplitude points "B", "C", "D" etc. are located in the vertical axis of the impedance diagram, and record the positions respectively. Position "A" is the zero point, the number above position "A" is positive, and the number below position "A" is negative.

[0041] 5. Readjust the parameters of the eddy current flaw detector so that the amplitude value of the gate alarm frame is located at 1 / 2 of the plate wall thickness. Save the parameters and label the file as "ZLZ001".

[0042] 6. Create a mapping table to match the thickness d2 value with the position of the impedance map amplitude point.

[0043] 7. To measure the thickness of the air inlet flange 3 of part 1, first select parameter "ZLZ001", then couple the eddy current probe to position "8" of the comparison sample 2. Press the "balance" key on the eddy current flaw detector to make the amplitude point of the impedance diagram of the eddy current flaw detector located at position "A" of the zero point of the impedance diagram. Then couple the eddy current probe to the air inlet flange 3 of part 1 and observe the impedance diagram display. If the amplitude point is above position "A", it means that the wall thickness at this position is greater than 1.2mm. If the amplitude point is below position "A", it means that the wall thickness at this position is less than 1.2mm and should be recorded. If the amplitude point is below the alarm box, the wall thickness at this position is unqualified.

[0044] 8. After the measurement is completed, the eddy current probe needs to be coupled to position "8" of the comparison sample 2, and observe whether the amplitude point of the impedance diagram of the eddy current flaw detector is located at position "A" of the zero point of the impedance diagram. If not, step 7 needs to be repeated.

[0045] The foregoing has provided a detailed description of the in-situ eddy current thickness measurement method for the turbine support shroud of an aero-engine, as provided by this invention. Specific examples have been used to illustrate the structure and working principle of this invention. The descriptions of the embodiments above are merely for the purpose of helping to understand the method and core ideas of this invention. It should be noted that those skilled in the art can make various improvements and modifications to this invention without departing from its principles, and these improvements and modifications also fall within the scope of protection of the claims of this invention.

Claims

1. A method for in-situ eddy current thickness measurement of the turbine support shroud wall thickness of an aero-engine, characterized in that: Includes the following steps, Step 1: Process and manufacture a comparison sample (2). The comparison sample (2) has a recessed air inlet flange (3). The maximum depth of the recess is greater than 1 / 2 of the wall thickness of the raw material plate. Step 2: Grind and polish the front half of the front end (5) of the comparison sample (2) according to the processing technology, mark the front edge of the air intake (4) after grinding and polishing, and record the thickness of each mark (4) as d2 by CT measurement. Mark the position of 1 / 2 of the plate wall thickness and record the thickness d2 of the rear half of the comparison sample (2) near the rear end (6) as the original plate thickness H. Step 3: Calculate the frequency f of plate thickness H and adjust the parameters of the eddy current flaw detector. The flaw detection frequency is less than the frequency f. The frequency f of plate thickness H is obtained as follows: First, use a conductivity meter to measure the conductivity of the plate used in the comparison sample (2), or find the conductivity according to the material manual of the plate used. Calculate the frequency f of plate thickness H according to the standard penetration depth formula of eddy current. Step 4: Determine the impedance diagram. Position A is the zero point. The values ​​above position A are positive, and the values ​​below position A are negative. Position A is determined as follows: Couple the eddy current probe to any position near the rear end (6) of the comparison sample (2), press the "balance" key of the eddy current flaw detector, and make the amplitude point of the impedance diagram of the eddy current flaw detector located at the zero point A of the impedance diagram. Step 5: Readjust the eddy current flaw detector parameters so that the gate alarm frame amplitude value is located at 1 / 2 of the plate wall thickness. Save the parameters and label the file name. Then create a correspondence table to match the thickness d2 value with the position of the impedance diagram amplitude point. Step 6: Measure the thickness of the air intake flange (3) of part (1), open the file in step 5 and adjust the parameters of the eddy current flaw detector, couple the eddy current probe to any point on the rear end (6) of the comparison sample (2), press the balance key of the eddy current flaw detector so that the amplitude point of the impedance diagram is located at the zero point A of the impedance diagram, and then couple the eddy current probe to the air intake flange (3) of part (1) and observe the impedance diagram. If the amplitude point is above position A, it means that the wall thickness at this position is greater than the wall thickness at the rear end (6) of the comparison sample (2). If the amplitude point is below position A, it means that the wall thickness at this position is less than the wall thickness at the rear end (6) of the comparison sample (2). Record the value. If the amplitude point is below the alarm box, the wall thickness at this position is unqualified.

2. The in-situ eddy current thickness measurement method for the turbine support shroud wall thickness of an aero-engine according to claim 1, characterized in that: The marking method used in marking (4) includes Arabic numerals and English letters.

3. The in-situ eddy current thickness measurement method for the turbine support shroud wall thickness of an aero-engine according to claim 1, characterized in that: The material of the comparative sample (2) is a high-temperature alloy.

4. The in-situ eddy current thickness measurement method for the turbine support shroud wall thickness of an aero-engine according to claim 1, characterized in that: In step 2, grinding is performed to make the air inlet front edge of the comparison sample (2) meet the requirements of the design drawings; the rear half of the comparison sample (2) at the rear end (6) is not ground or polished, and is in the original state of the raw material plate.

5. The in-situ eddy current thickness measurement method for the turbine support shroud wall thickness of an aero-engine according to claim 1, characterized in that: In step 4, after determining the zero point A position, the eddy current probe is coupled to the front end (5) position of the comparison sample (2), the gain value of the eddy current flaw detector is adjusted so that the maximum amplitude point of the impedance diagram of the eddy current flaw detector is full screen and does not exceed the display screen, the phase value is adjusted so that the amplitude point display is rotated to the vertical direction, that is, the amplitude point is located in the vertical axis direction of the impedance diagram, and the position is recorded respectively. Position A is the zero point, the number above position A is positive, and the number below position A is negative.

6. The in-situ eddy current thickness measurement method for the turbine support shroud wall thickness of an aero-engine according to claim 1, characterized in that: After the measurement is completed, the eddy current probe needs to be coupled to any position on the rear end (6) of the comparison sample (2) and observe whether the amplitude point of the impedance diagram of the eddy current flaw detector is located at the zero point A of the impedance diagram. If not, step 6 needs to be repeated.

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