A Phased Array Ultrasonic Focusing Method for the Counterbore of the Tie Bolt of the Gas Turbine Turbine Disk

Abstract

The invention discloses a phased array ultrasonic focusing method for the counterbore of the tie rod bolt of a gas turbine turbine disk, which includes: fixing a phased array ultrasonic probe on a coded scanning tooling and coupling it to the outer surface of the turbine disk; calculating the focusing depth and lateral deflection angle of the phased array ultrasonic probe at each position; and setting a focusing rule. The invention can ensure that the focusing depth of the sound beam of the phased array ultrasonic probe is always at the fillet position of the counterbore of the tie rod bolt and the incident direction is always within the normal plane of the fillet of the counterbore of the tie rod bolt, improving the detection sensitivity and the defect quantification accuracy.

Description

Technical Field

[0001] The present invention belongs to the field of ultrasonic testing, and particularly relates to a phased array ultrasonic focusing method for the counterbore of the tie bolts of the turbine disk of a gas turbine. Background Art

[0002] The turbine disks of each stage of a gas turbine are generally fixed together by circumferential tie bolts, serving as the main body of the turbine rotor and transmitting the torque generated by the turbine blades. The tie bolts not only have to bear the tensile force and pre-tightening force generated by the gravity of the turbine rotor itself, but also have to bear the air flow impact force and vibration stress during operation, making the tie bolts always in a relatively high stress state. The stress of the tie bolts is mainly borne by the joint surface between the tie bolt nut and the counterbore part of the turbine disk, resulting in a highly concentrated stress at the counterbore part of the turbine disk. In particular, the stress state at the fillet position of the counterbore of the tie bolt is the worst, and it is easy to generate harmful defects such as cracks at the counterbore position of the turbine disk, which damage the structural integrity of the turbine disk.

[0003] For the cracks at the fillet of the counterbore of the tie bolt, generally, a phased array ultrasonic testing method with higher precision is preferred. Due to the limited coupling position, the coupling surface of the phased array ultrasonic probe can only be the outer surface of the turbine disk. When using the outer surface of the turbine disk as the coupling surface to scan the fillet of the counterbore of the tie bolt, in order to ensure that the focusing depth of the phased array ultrasonic probe beam is always at the fillet position of the counterbore of the tie bolt and the incident direction is always within the normal plane of the counterbore of the tie bolt to obtain the highest detection sensitivity and higher quantitative accuracy, extremely high requirements are put forward for the phased array ultrasonic focusing method. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the deficiency that the focusing depth and the beam incident direction in the existing focusing method cannot be continuously adjusted with the change of the scanning position, and provide a phased array ultrasonic focusing method for the counterbore of the tie bolts of the turbine disk of a gas turbine, so as to improve the detection sensitivity and quantitative accuracy.

[0005] The present invention is realized by adopting the following technical solutions:

[0006] A phased array ultrasonic focusing method for the counterbore of the tie bolts of the turbine disk of a gas turbine includes the following steps:

[0007] (1) Fix the phased array ultrasonic probe on a coded scanning tooling, couple the phased array ultrasonic probe to the outer surface of the turbine disk, and take the position on the outer surface of the turbine disk corresponding to the connecting line between the center of the counterbore of the tie bolt and the center of the turbine disk as the starting point;

[0008] (2) Calculate the focusing depth and the lateral deflection angle of the phased array ultrasonic probe;

[0009] (3) Set the focusing depth and lateral deflection angle corresponding to different lateral movement distances of the phased array ultrasonic probe, and input them as the focusing rule into the phased array ultrasonic detector;

[0010] (4) During the circumferential scanning along the outer surface of the turbine disk, the scanning speed matches the switching speed of the focusing rule. At the same time, according to the near-field region limitation of the focusing depth of the phased array ultrasonic probe and the energy attenuation law of the deflection angle, determine the lateral movement range of the phased array ultrasonic probe.

[0011] A further improvement of the present invention lies in that in step (2), the focusing depth and lateral deflection angle of the phased array ultrasonic probe are calculated through parameters such as the outer surface radius of the turbine disk, the eccentricity between the center of the pull rod bolt counterbore and the center of the turbine disk, the lateral movement distance of the phased array probe, and the radius of the pull rod bolt counterbore.

[0012] A further improvement of the present invention lies in that during the circumferential scanning of the phased array ultrasonic probe along the outer surface of the turbine disk, the sound beam of the phased array ultrasonic probe is always focused on the fillet of the pull rod bolt counterbore, and the sound beam of the phased array ultrasonic probe is always within the normal plane of the fillet of the pull rod bolt counterbore.

[0013] A further improvement of the present invention lies in that considering that the focusing depth and the lateral deflection angle of the sound beam of the phased array ultrasonic probe are constantly changing during the detection process, it is necessary to calculate and obtain the focusing depth and lateral deflection angle of the phased array ultrasonic probe at each scanning position in real time through the following calculations:

[0014] Step A: Calculate the focusing depth d of the phased array ultrasonic probe

[0015]

[0016] In the formula, R is the outer surface radius of the turbine disk, S is the eccentricity between the center of the pull rod bolt counterbore and the center of the turbine disk, p is the lateral movement distance of the phased array probe, and r is the radius of the pull rod bolt counterbore;

[0017] Step B: Calculate the lateral deflection angle θ of the sound beam of the phased array ultrasonic probe

[0018]

[0019] A further improvement of the present invention lies in that if the coupling position of the phased array ultrasonic probe is on the right side of the starting point, the calculated lateral deflection angle of the sound beam of the phased array ultrasonic probe is the angle deflected to the left.

[0020] A further improvement of the present invention lies in that in step (3), during the detection process, the corresponding focusing rule stored in the phased array ultrasonic detector is triggered in real time according to the lateral movement distance of the phased array ultrasonic probe recorded by the encoded scanning tooling.

[0021] The present invention has at least the following beneficial technical effects:

[0022] In order to reduce the influence of the changes in the focusing depth and the incident direction of the sound beam during phased array ultrasonic testing on the testing sensitivity and the defect quantification accuracy, the present invention proposes a phased array ultrasonic focusing method for the counterbore of the tie rod bolt of the turbine disk of a gas turbine, ensuring that the focusing depth of the sound beam of the phased array ultrasonic probe is always at the fillet position of the counterbore of the tie rod bolt and the incident direction is always within the normal plane of the fillet of the counterbore of the tie rod bolt, thereby improving the testing sensitivity and the defect quantification accuracy. Description of the Drawings

[0023] Figure 1 It is a schematic diagram of a phased array ultrasonic testing device for the counterbore of the tie rod bolt of the turbine disk of a gas turbine according to the present invention;

[0024] Figure 2 It is a schematic diagram for calculating the phased array ultrasonic focusing method for the counterbore of the tie rod bolt of the turbine disk of a gas turbine according to the present invention.

[0025] Description of the Reference Numerals:

[0026] 1 - Phased array ultrasonic detector, 2 - Phased array ultrasonic probe, 3 - Encoded scanning tooling, 4 - Counterbore of tie rod bolt, 5 - Turbine disk.

[0027] Figure 2 For each symbol in it: R - Outer surface radius of the turbine disk, S - Eccentric distance between the center of the counterbore of the tie rod bolt and the center of the turbine disk, p - Lateral movement distance of the phased array probe, r - Radius of the counterbore of the tie rod bolt, d - Focusing depth of the phased array ultrasonic probe, θ - Lateral deflection angle of the sound beam of the phased array ultrasonic probe. Detailed Embodiment

[0028] Hereinafter, exemplary embodiments of the present disclosure will be described in more detail with reference to the drawings. Although the exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present disclosure can be more thoroughly understood and the scope of the present disclosure can be fully conveyed to those skilled in the art. It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other. Hereinafter, the present invention will be described in detail with reference to the drawings and in conjunction with the embodiments.

[0029] As Figure 1As shown in the figure, the phased array ultrasonic testing device for the counterbore of the tie rod bolt of the gas turbine turbine disk includes a phased array ultrasonic detector 1, a phased array ultrasonic probe 2, a coded scanning tooling 3, and the counterbore 4 of the tie rod bolt of the gas turbine turbine disk. On the premise of considering the phased array ultrasonic focusing method, the focusing depth d and the lateral deflection angle θ of the sound beam at each scanning position are calculated. The corresponding focusing law is set through the phased array ultrasonic detector 1 to excite the phased array ultrasonic probe 2, and the focusing law at the corresponding position is triggered in real time through the position information transmitted back by the coded scanning tooling 3 to achieve real-time and accurate focusing on the counterbore 4 of the tie rod bolt.

[0030] The specific steps are as follows:

[0031] (1) Fix the phased array ultrasonic probe 2 on the coded scanning tooling 3, couple the phased array ultrasonic probe 2 to the outer surface of the turbine disk, and take the position on the outer surface of the turbine disk corresponding to the connecting line between the center of the counterbore of the tie rod bolt 4 and the center of the turbine disk 5 as the starting point;

[0032] (2) Calculate the focusing depth and lateral deflection angle of the phased array ultrasonic probe 2. Through parameters such as the radius of the outer surface of the turbine disk, the eccentricity between the center of the counterbore of the tie rod bolt and the center of the turbine disk, the lateral movement distance of the phased array probe, and the radius of the counterbore of the tie rod bolt, the focusing depth and lateral deflection angle of the phased array ultrasonic probe are calculated to ensure that during the circumferential scanning of the outer surface of the turbine disk by the phased array ultrasonic probe, the sound beam of the phased array ultrasonic probe is always focused on the fillet of the counterbore of the tie rod bolt, and the sound beam of the phased array ultrasonic probe is always within the normal plane of the fillet of the counterbore of the tie rod bolt;

[0033] Considering that the focusing depth and the lateral deflection angle of the sound beam of the phased array ultrasonic probe 2 are constantly changing during the detection process, it is necessary to obtain the focusing depth and lateral deflection angle of the phased array ultrasonic probe 2 at each scanning position in real time through the following calculations:

[0034] Step A: Calculate the focusing depth d of the phased array ultrasonic probe

[0035]

[0036] In the formula, R is the radius of the outer surface of the turbine disk, S is the eccentricity between the center of the counterbore of the tie rod bolt and the center of the turbine disk, p is the lateral movement distance of the phased array probe, and r is the radius of the counterbore of the tie rod bolt.

[0037] Step B: Calculate the lateral deflection angle θ of the sound beam of the phased array ultrasonic probe

[0038]

[0039] It should be noted that if the coupling position of the phased array ultrasonic probe 2 is on the right side of the starting point, the calculated lateral deflection angle of the sound beam of the phased array ultrasonic probe 2 is the angle of left deflection;

[0040] (3) Set the focusing depth and lateral deflection angle corresponding to different lateral movement distances of the phased array ultrasonic probe 2, and input them as the focusing rules into the phased array ultrasonic detector 1. During the detection process, the corresponding focusing rules stored in the phased array ultrasonic detector 1 are triggered in real time according to the lateral movement distance of the phased array ultrasonic probe 2 recorded by the encoded scanning tooling 3;

[0041] (4) During the circumferential scanning along the outer surface of the turbine disk 5, the scanning speed should match the switching speed of the focusing rules. At the same time, the lateral movement range of the phased array ultrasonic probe 2 should be reasonably determined according to the near-field region limitation of the focusing depth of the phased array ultrasonic probe 2 and the energy attenuation law of the deflection angle.

[0042] Specific embodiments of the present invention:

[0043] A phased array ultrasonic focusing method for the counterbore of the tie bolt of the turbine disk of a gas turbine provided by the present invention can improve the detection sensitivity and quantitative accuracy. Taking a certain foreign F-class gas turbine as an example, the outer surface radius of the turbine disk of this type of gas turbine is 800 mm, the eccentricity between the center of the counterbore of the tie bolt and the center of the turbine disk is 740 mm, and the radius of the counterbore of the tie bolt is 50 mm. A phased array ultrasonic detector and a phased array ultrasonic probe produced by a certain company. The phased array ultrasonic detector has a sector scanning and a linear scanning mode. The phased array ultrasonic probe is a two-dimensional matrix phased array ultrasonic probe, which can achieve beam focusing in both the longitudinal and lateral directions. According to the phased array ultrasonic focusing method provided by the present invention, calculate the focusing depth and the lateral deflection angle of the phased array ultrasonic probe at different scanning positions according to the above parameters.

[0044] Step A. Calculate the focusing depth d of the phased array ultrasonic probe

[0045]

[0046] In the formula, R = 800 mm, S = 740 mm, r = 50 mm. Taking the starting position O point on the outer surface of the turbine disk as the zero point, define the lateral movement distance of the phased array ultrasonic probe at this time as 0. When scanning left from the zero point position, the arc length between the position of the phased array ultrasonic probe and the zero point is the lateral movement distance p of the phased array ultrasonic probe.

[0047] Take different lateral movement distances. Taking lateral movement distances of 5 mm, 10 mm, 15 mm, 20 mm, 25 mm, 30 mm, 35 mm, 40 mm, 45 mm, and 50 mm as examples, the calculated focusing depths are shown in Table 1.

[0048] Table 1 Focusing depth of the phased array ultrasonic probe

[0049]

[0050] Step B: Calculate the lateral deflection angle θ of the phased array ultrasonic probe

[0051]

[0052] Take different lateral movement distances. Taking lateral movement distances of 5mm, 10mm, 15mm, 20mm, 25mm, 30mm, 35mm, 40mm, 45mm, and 50mm as examples, the calculated lateral deflection angles of the sound beam are shown in Table 2.

[0053] Table 2 Lateral Deflection Angles of the Phased Array Ultrasonic Probe Sound Beam

[0054]

[0055] Although the present invention has been described in detail above with general descriptions and specific embodiments, based on the present invention, some modifications or improvements can be made, which are obvious to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection required by the present invention.

Claims

1. A phased array ultrasonic focusing method for the counterbore of the tie bolts of a gas turbine turbine disk, characterized in that, It includes the following steps: (1) Fix the phased array ultrasonic probe on the coded scanning tooling, couple the phased array ultrasonic probe to the outer surface of the turbine disk, and take the position on the outer surface of the turbine disk corresponding to the connection line between the center of the pull rod bolt counterbore and the center of the turbine disk as the starting point; (2) Calculate the focusing depth and lateral deflection angle of the phased array ultrasonic probe; through the outer surface radius of the turbine disk, the eccentricity between the center of the pull rod bolt counterbore and the center of the turbine disk, the lateral movement distance of the phased array probe, and the radius of the pull rod bolt counterbore parameters, calculate the focusing depth and lateral deflection angle of the phased array ultrasonic probe; considering that the focusing depth and the lateral deflection angle of the sound beam of the phased array ultrasonic probe are constantly changing during the detection process, obtain the focusing depth of the phased array ultrasonic probe at each scanning position in real time through the following calculation: Calculate the focusing depth d of the phased array ultrasonic probe In the formula, R is the outer surface radius of the turbine disk, S is the eccentricity between the center of the pull rod bolt counterbore and the center of the turbine disk, p is the lateral movement distance of the phased array probe, and r is the radius of the pull rod bolt counterbore; Considering that the focusing depth and the lateral deflection angle of the sound beam of the phased array ultrasonic probe are constantly changing during the detection process, obtain the lateral deflection angle of the phased array ultrasonic probe at each scanning position in real time through the following calculation: Calculate the lateral deflection angle θ of the sound beam of the phased array ultrasonic probe (3) Set the focusing depth and lateral deflection angle corresponding to different lateral movement distances of the phased array ultrasonic probe, and input them into the phased array ultrasonic detector as the focusing rule; (4) During the circumferential scanning along the outer surface of the turbine disk, the scanning speed matches the switching speed of the focusing rule, and at the same time, determine the lateral movement range of the phased array ultrasonic probe according to the near-field region limitation of the focusing depth of the phased array ultrasonic probe and the energy attenuation law of the deflection angle.

2. The phased array ultrasonic focusing method for the counterbore of the tie bolt of the gas turbine turbine disk according to claim 1, wherein Ensure that during the circumferential scanning of the phased array ultrasonic probe along the outer surface of the turbine disk, the sound beam of the phased array ultrasonic probe is always focused on the fillet of the pull rod bolt counterbore.

3. A phased array ultrasonic focusing method for the counterbore of the tie bolts of a gas turbine turbine disk according to claim 1, characterized in that, Ensure that during the circumferential scanning of the phased array ultrasonic probe along the outer surface of the turbine disk, the sound beam of the phased array ultrasonic probe is always within the normal plane of the fillet of the pull rod bolt counterbore.

4. A phased array ultrasonic focusing method for the counterbore of the tie bolts of a gas turbine turbine disk, according to claim 1, characterized in that The coupling position of the phased array ultrasonic probe is on the right side of the starting point, and the calculated deflection angle of the sound beam of the phased array ultrasonic probe is the angle of left deflection.

5. A phased array ultrasonic focusing method for the counterbore of the tie bolts of the gas turbine turbine disk according to claim 1, characterized in that In step (3), during the detection process, the corresponding focusing rule stored in the phased array ultrasonic detector is triggered in real time through the lateral movement distance of the phased array ultrasonic probe recorded by the coded scanning tooling.

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