JP2009204368A - Blade groove inspection method of turbine rotor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a blade groove inspection method of a turbine rotor, accurately detecting the lug part in the T route type blade groove part provided in the peripheral direction of the turbine rotor, or the side entry type blade groove part provided in the axial direction of the turbine rotor without drawing out a turbine blade. <P>SOLUTION: The echo waveform of a health part in the echo produced by the reflection reaching the lug part in the T route type blade groove part is compared with the echo waveform of a flaw part in the echo in the case of a T route type implanted part while focusing an ultrasonic wave on a point using a phase array type ultrasonic probe, a transmission part and a receiving part are arranged in the diametric direction of the turbine rotor in the case of a side entry type implanted part and the ultrasonic wave is point-focused to the side entry type implanted part, so that the ultrasonic wave reflected from the flaw part is reflected from the other surface being an opposed surface to detect a rotor blade groove shaped echo and a flaw leading end part echo to evaluate the presence of the flaw. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a turbine rotor blade groove inspection method, and more particularly to a turbine rotor blade groove inspection method that can accurately inspect a turbine rotor blade groove having a complicated shape by ultrasonic flaw detection.

  A rotor disk provided in a plurality of stages in a general turbine rotor is provided with a balance hole 32 in a rotor shaft 31 provided with a center hole 30 as shown in an example viewed from the axial direction in FIG. A disk 33 is mounted, and a turbine blade mounting implantation part having a blade groove part called a T-root type or tree-like side entry type on the outer peripheral surface of the disk 33 is provided in the circumferential direction or the rotor axial direction. As a result, the turbine rotor blade 34 is coupled and fixed.

  FIG. 4 is a perspective view showing an example of a T-route type blade groove portion 40 provided in the circumferential direction and a turbine blade 41 attached to the blade groove portion 40. In FIG. 4, X indicates the axial direction of the turbine rotor 42, Y indicates the circumferential direction of the turbine rotor 42, the blade groove 40 is provided in the circumferential direction of the turbine rotor 42, and the turbine rotor blade 41 is substantially T A blade-shaped blade root 43 is provided, and the blade root 43 is inserted into a turbine blade mounting implantation portion constituted by a blade groove portion 40 to be supported by the turbine rotor 42.

  The blade root 43 is configured by a neck portion 44 and an enlarged portion 45 that engages with the blade groove portion 40 of the turbine rotor 42, and the neck portion 44 is provided on the surface of the enlarged portion 45 on the side where the neck portion 44 is provided. A pair of concave grooves 46 are formed so as to sandwich 44, and each concave groove 46 extends along the longitudinal direction of the boundary portion, that is, the tangent line of the turbine rotor 42, at the boundary portion with the neck portion 44 in the enlarged portion 45. It is provided along the direction Y.

  On the other hand, FIG. 5 is a schematic perspective view of an example in which a turbine rotor blade 51 is fixedly installed in a turbine blade mounting implant portion constituted by side entry type blade groove portions 50 provided in the rotor axial direction. 4, X indicates the rotor axial direction, Y indicates the circumferential direction of the rotor disk 52, and the turbine rotor blade 51 includes a blade base 53 that supports the turbine rotor blade 51, and the blade base 53. It has a tree-shaped blade root 54 formed on the bottom surface. Further, the rotor disk 52 has a blade groove portion 50 having a shape corresponding to the blade root portion 54 formed in the implanted portion of the turbine rotor blade 51 in the rotor axial direction, and the rotor disk 52 positioned between the blade groove portions 50. A groove 55 that is semicircular in the radial direction is formed on the outer peripheral surface, and this semicircular groove 55 matches with the semicircular groove 56 provided in the blade base 53 to form a circular groove.

  When the turbine rotor blades 51 are implanted into the rotor disk 52, the blade root parts 54 of the turbine rotor blades 51 are fitted one by one into the blade groove part 50 of the rotor disk 52 along the rotor axial direction. At this time, the semicircular groove 55 of the rotor disk 52 and the semicircular groove 56 of the blade base 53 coincide with each other, and the blade retaining pin 57 is inserted into the formed circular groove to fix the turbine rotor blade 51.

  The shroud 58 is attached in order to increase the vibration resistance by adjusting the natural frequency of the turbine blade 51 while maintaining the distance from the seal fin at the tip of the turbine blade 51 to form a steam passage. When the shroud 58 is attached to the turbine blade 51, a circular or rectangular protrusion (tenon) provided on the top of the turbine blade 51 is passed through the hole of the shroud 58 and fixed to the turbine blade 51 by caulking. Usually, about 5 to 10 turbine blades 51 are attached to one shroud 58 as a set.

  FIG. 6 shows an example in which the turbine rotor blade 60 is attached to a turbine blade mounting implantation portion composed of side entry type blade groove portions 62 provided in the circumferential direction of the turbine rotor 61. In order to mount the plurality of turbine rotor blades 60 around the disc-shaped turbine rotor 61, a blade implantation portion 62 in which first to third dovetail portions 63 to 65 project from the tip edge at a predetermined interval is provided. The base end portion 66 of the turbine blade 60 is engaged with the rotor 61 in the circumferential direction.

  Such turbine blade attachments to the turbine rotor may crack during operation due to corrosion fatigue or stress corrosion cracking (SCC). Therefore, the operation of the turbine rotor 1 is periodically stopped, and the turbine rotor blade implantation part is usually flaw-detected using an ultrasonic flaw detector.

  However, as shown in FIGS. 4 to 6, the implanted portion of the turbine blade in the turbine rotor has a complicated shape. For example, in the T-root type blade groove 70 shown in FIG. The thin-walled portion called the ear portion shown with a sudden change in shape, and the generated crack is not directional, such as the axial direction of the turbine rotor 72 or the circumferential direction of the turbine rotor 72, When a straight crack occurs on the surface of the ear, it is difficult to detect, and it is difficult to inspect without removing the wing.

  Further, even in the side entry type blade groove portion 50 provided in the rotor axial direction as shown in FIG. 5, it is very difficult to detect a defect generated in the blade groove portion 50 as shown in FIG. Become. FIG. 8A is a schematic view of the defects 82, 83, and 84 generated in the side entry type turbine blade mounting implant 81 in the turbine rotor 80 as viewed from above, and FIG. 8B is the turbine rotor 80. The figure is viewed from the axial direction, and the defects 82, 83, 84 are not visible because they are in the turbine rotor 80, but are drawn so that they can be seen for explanation. Reference numeral 85 denotes an ultrasonic probe for transmitting / receiving ultrasonic waves, 86 is an ultrasonic probe for transmitting ultrasonic waves, and 87 is an ultrasonic probe for receiving ultrasonic waves.

  For example, when an ultrasonic wave is emitted from an ultrasonic probe 85 placed on one axial surface of the turbine rotor 80 and received by the same ultrasonic probe 85, the surface of the rotor disk 80 is shown in FIG. As shown in FIG. 8 (B), the crack 82 generated at an angle of about 45 degrees with respect to the horizontal direction in the blade groove R portion at the center of the disk width direction is the rotor disk surface (access at the time of flaw detection). The angle at which the ultrasonic wave can travel is substantially coincident with the crack generation direction, and it is difficult to obtain a reflection echo from the crack surface with the ultrasonic wave traveling in the direction indicated by 88.

  Further, the ultrasonic wave from the ultrasonic transmission probe 86 placed on one surface in the axial direction of the turbine rotor 80 is reflected by the ultrasonic reception probe 87 placed on the other surface in the axial direction of the turbine rotor 80. The so-called pitch catch type method also receives the ultrasonic wave in the direction indicated by 89, and it is difficult to determine whether the echo is caused by the defect 83 or the echo from the groove of the turbine blade mounting implant 81. Further, in this method, it is necessary to move the ultrasonic transmission probe 86 and the ultrasonic reception probe 87 together, and a device for that purpose becomes a large scale. A defect such as 84 in the turbine rotor 80 that is close to one surface in the axial direction has a high possibility of becoming a dead zone of ultrasonic waves, so that flaw detection is difficult.

  Therefore, the conventional inspection by ultrasonic flaw detection was performed by extracting the turbine blades, inspecting the probe at a position where the flaws can be detected, and then returning the turbine blades to their original positions. In addition, it requires a large amount of incidental work costs for inspection, such as pre-treatment work for the turbine, and the turbine blade groove has a large dead zone due to its complicated shape and narrow part, and relies on visual inspection without sufficient inspection. There was a case.

  For ultrasonic flaw detection of defects generated in the turbine rotor attachment portion of the turbine blade, for example, Patent Document 1 discloses a blade groove tooth portion having a defect parallel to the length direction (turbine rotor axial direction) (for example, A transmission side longitudinal wave oblique angle probe having a refraction angle of 10 to 40 ° is arranged on one of both blade groove end faces of the side entry type), and a similar reception side longitudinal wave oblique angle probe is disposed on the other side. The propagation time of the wall reflected wave that propagates as a longitudinal wave after being reflected once by the wall surface, and the wall surface defect reflected wave that has been reflected once by the blade groove wall and then converted to the transverse wave is reflected by the defect and propagates to the blade groove wall surface A pitch catch type ultrasonic flaw detection method in which a defect is detected by using a time difference from a propagation time until it is received after being converted into a longitudinal wave again is shown.

  Further, in Patent Document 2, in a turbine rotor having a blade groove part in which a turbine blade is mounted in the circumferential direction of the turbine rotor, in an ultrasonic probe having an ultrasonic wave transmitting part and an ultrasonic wave receiving part for receiving an echo, The direction of the transmitted ultrasonic wave and the direction of the reflected echo coincide with the radial direction of the turbine rotor, and the ultrasonic wave transmitted from the ultrasonic wave transmitting part is directed to the opposite side surface of the wing implanted part, and the tip of the wing implanted part The ultrasonic probe is arranged so as to apply the ultrasonic wave reflected on the opposite side surface with respect to the part to be inspected near the edge, and the ultrasonic probe is arranged along the circumferential direction of the turbine rotor. A turbine rotor blade implantation unit ultrasonic flaw detection apparatus and a flaw detection method using the apparatus are disclosed in which scanning is performed by relative movement.

JP-A-5-288723 Japanese Patent No. 3390748

  However, in the pitch catch type ultrasonic flaw detection method disclosed in Patent Document 1, the transmitting side probe and the receiving side probe are arranged on both sides in the axial direction of the rotor disk as described in FIG. However, a large-scale device is required to move the probes arranged on both sides while accurately synchronizing them, which is very difficult.

  Further, the flaw detection method disclosed in Patent Document 2 is intended for the case of a turbine rotor having blade groove portions 62 for mounting turbine blades 60 in the circumferential direction of the turbine rotor 61 as shown in FIG. In order to apply to the side entry type blade groove portion 50 provided in the rotor axial direction as shown in FIG. 1, it is necessary to extract the turbine blade 51, and the direction of the transmitted ultrasonic wave and the direction of the reflected echo are determined by the turbine rotor. Therefore, it cannot be applied to the inspection of the side entry type blade groove portion 50 provided in the rotor axial direction.

  Therefore, in the present invention, as shown in FIG. 7, it is provided in the ear portion of the T-route type blade groove portion 70 provided in the circumferential direction of the turbine rotor or in the axial direction of the turbine rotor as shown in FIG. Turbine rotor blade groove inspection that can accurately detect defects 82 to 84 and the like generated in the axial direction in the turbine blade mounting implantation portion including the side entry type blade groove portion 81 that is formed without removing the turbine blade. The challenge is to provide a method.

In order to solve the above problems, the turbine rotor blade groove inspection method according to the present invention is as follows.
An ultrasonic probe is installed on a surface perpendicular to the axis of the turbine rotor, and a method for inspecting a defect generated in a T-root type implant portion provided in a circumferential direction of the peripheral edge of the turbine rotor,
The ultrasonic probe is a phased array type ultrasonic probe, and the T-route type implantation is performed by reflecting ultrasonic waves from the ultrasonic probe on a surface facing the ultrasonic probe installation surface. It is characterized in that the point is focused on the ear of the part, the sector is scanned, the echo waveform of the healthy part is compared with the echo waveform of the defective part, and the presence or absence of the defect is evaluated by the difference.

Similarly,
An ultrasonic probe is installed on a surface orthogonal to the axis of the turbine rotor, and a method for inspecting a defect generated in a side entry type implantation portion provided in the turbine rotor axial direction at the periphery of the turbine rotor,
The ultrasonic probe is a phased array type ultrasonic probe, an oscillating unit and a receiving unit are arranged in a radial direction of the turbine rotor, and ultrasonic waves from the ultrasonic probe are transmitted to the side entry type implanter. It is characterized in that the focus is point-focused on the recessed portion, the ultrasonic wave reflected by the defective portion by sector scanning is reflected and detected by the other surface as the opposing surface, and the presence or absence of the defect is evaluated.

  In this way, using the phased array type ultrasonic probe and focusing the ultrasonic point, in the case of the T root type implantation part, the echo waveform and defect of the healthy part among the echoes generated by reflection reaching the ear part In the case of a side-entry implant, the transmitter and receiver are arranged in the radial direction of the turbine rotor, and the ultrasonic waves from the ultrasonic probe are applied to the side-entry implant. A turbine rotor that can accurately determine a defect without extracting the turbine blade by focusing the point and reflecting the ultrasonic wave reflected by the defective part on the other surface as an opposing surface and evaluating the presence or absence of the defect. It can be set as a blade groove inspection method.

  In the case of the T-route type implanting section, the probe is scanned in the circumferential direction while scanning the ultrasonic point focus position of the phased array type ultrasonic probe in the circumferential direction, and the overlapping range of scanning data In comparison with the data of the noise level, the presence or absence of the defect is evaluated from the amount of change in the noise level. The ultrasonic point focus position is scanned in the radial direction of the turbine rotor while sector scanning in the thickness direction of the turbine rotor, and the presence or absence of defects is evaluated from the amount of change in the noise level by comparing and referring to the data in the overlapping range of the scan data. This is a preferred embodiment of the present invention.

  As described above, according to the present invention, in the case of a T-root type implant, using a phased array type ultrasonic probe, the sound of the echoes generated by reflection reaching the ear is focused. The echo waveform of the part is compared with the echo waveform of the defective part, and in the case of the side entry type implanted part, the transmitting part and the receiving part are arranged in the radial direction of the turbine rotor, and the ultrasonic wave from the ultrasonic probe is By making point focus on the entry type implantation part and reflecting the ultrasonic wave reflected by the defect part on the other surface which becomes the opposite surface and evaluating the presence or absence of the defect, the ear part of the T root type implantation part is also a side entry type. As for the defect in the ultrasonic wave traveling direction of the implanted part, the reflected ultrasonic wave passes through the part of the defect with an angle, so the defect can be accurately determined without removing the turbine blade. It can be over data blade groove inspection method.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Not too much.

  FIG. 1 is a view for explaining the case of inspecting a T-route type turbine blade mounting implant using the turbine rotor blade groove inspection method according to the present invention, and FIG. 2 is also a side entry type turbine. It is a figure for demonstrating the case where the implantation part for wing | blade mounting | wearing is test | inspected.

  In the present invention, as an ultrasonic probe, a large number of ultrasonic transducers are arranged in the XY direction, and phase focusing is possible by adjusting the timing of ultrasonic oscillation from each transducer. An array type ultrasonic probe is used. And in the case of the T root type implantation part, the echo waveform of the healthy part and the echo waveform of the defective part among the echoes generated by the reflection reaching the ear part are compared, and in the case of the side entry type implantation part, The receiving part is arranged in the radial direction of the turbine rotor, the ultrasonic wave from the ultrasonic probe is point-focused on the side entry type implant part, and the ultrasonic wave reflected by the defective part is on the other surface as the opposite surface. Reflect and evaluate for defects.

  By doing so, both the ears of the T-root type implant part and the defects in the ultrasonic traveling direction of the side entry type implant part, the reflected ultrasonic waves pass through the defect part at an angle. Therefore, it is possible to provide a turbine rotor blade groove inspection method that can accurately determine a defect without removing the turbine blade.

  First, a flaw detection method including an ear portion of a T-root type implantation portion provided in the circumferential direction of the peripheral edge of the turbine rotor shown in FIG. 1 will be described. In FIG. 1, 10 is a turbine rotor, 11 is a rotor blade, Is a T root type blade groove part, 13 is a blade groove part ear | edge part, As mentioned above, the T root type implantation part 12 in the case of this FIG. 1 is provided in the circumferential direction of the turbine rotor periphery.

  The phased array ultrasonic flaw detector 14 that performs flaw detection is installed on one surface orthogonal to the rotor axis of the turbine rotor 10. Then, the ultrasonic wave to be point-focused is directed to the surface 17 that is the opposing surface of the ultrasonic probe 14 through the path 15, reflected there, and further directed to the ear portion 13. At this time, the ultrasonic point focus position of the phased array type ultrasonic probe is sector-scanned, the echo waveform of the healthy part and the echo waveform of the defective part are compared, and the presence / absence of a defect is evaluated by the difference.

  In addition, by scanning the probe in the circumferential direction while scanning the ultrasonic point focus position of the phased array type ultrasonic probe in the circumferential direction, the data in the overlapping range of the scanned data is compared and referenced, and the noise level The presence or absence of defects may be evaluated from the amount of change.

  By doing in this way, the echo returns from the ear part 13, but when there is a defect 16 in the middle, the echo of the defect 16 returns. If the presence of the defect 16 is recognized in this way, the echo waveform of the healthy part without the defect and the echo waveform of the defect 16 are compared and evaluated, or the data in the overlapping range of the scanning data is compared and referenced to determine the amount of change in the noise level. The presence or absence of defects can be evaluated.

  At this time, since the ultrasonic path 15 is directed from the central direction of the turbine rotor 10 toward the surface 17 and toward the ear portion 13 at a large angle, the echo reflected by the defect 16 inside the ear portion 13 becomes clear. From this, defects can be found accurately.

  The case of the side entry type implantation portion provided in the axial direction of the turbine rotor shown in FIG. 2 is the same as that of the T root type implantation portion described above. In the case of the embedded part, the phased array ultrasonic flaw detector is divided into the ultrasonic oscillation probe and the ultrasonic receiving probe and arranged in the radial direction of the turbine rotor to increase the angle of the ultrasonic wave to the implanted part. Flaw detection.

  In FIG. 2, 20 is a turbine rotor provided with side entry type blade grooves 24 in the axial direction, 21 is an ultrasonic transmission phased array probe, 22 is an ultrasonic reception phased array probe, and 23 is a turbine. FIG. 2 shows the side entry type blade groove 24 indicated by a dotted line when the turbine rotor 20 is viewed from a direction perpendicular to the axis.

  The ultrasonic transmission phased array probe 21 and the reception phased array probe 22 are arranged in a radial direction on one surface orthogonal to the rotor axis, and the ultrasonic transmission phased array probe 21 is preferably a turbine rotor. Installed closer to the center of 20. Then, the ultrasonic wave emitted from the ultrasonic transmission phased array probe 21 is point-focused on the side entry type blade groove portion 24 through the path 25 and reflected by the surface facing the ultrasonic transmission phased array probe 21. Ultrasound is received by the receiving phased array probe 22.

  Then, the point focus position is scanned in the radial direction while performing sector scanning in the thickness direction in the turbine rotor 20, and the comparison is made with reference to the data in the overlapping range of the scanning data, for example, the rotor blade groove echo and the tip of the defect 23. The presence / absence of a defect is evaluated by detecting a partial echo, or the presence / absence of a defect is evaluated from the amount of change in the noise level by comparing and referring to data in the overlapping range of scanning data.

  By doing so, since the reflected ultrasonic waves pass through the defect portion at an angle, the turbine rotor blade groove inspection method can accurately determine the defect without extracting the turbine blade. It can be.

  According to the present invention, it has been difficult to remove, restore, and inspect the turbine blades for defects that have occurred in the ears of the T-route type implantation part and the side entry type implantation part provided in the rotor axial direction, which have been difficult in the past. Therefore, it is possible to accurately detect the pre-processing work for the inspection without incurring a large amount of incidental work or cost.

It is a figure for demonstrating the inspection method of the implantation part for T root type | mold turbine blade mounting | wearing using the turbine rotor blade groove | channel inspection method which becomes this invention. It is a figure for demonstrating the inspection method of the implantation part for side entry type turbine blade mounting | wearing using the turbine rotor blade groove | channel inspection method which becomes this invention. It is the figure which looked at an example of the turbine rotor disk from the axial direction. FIG. 2 is a schematic perspective view of an example of a T-route type blade groove provided in the circumferential direction of the turbine rotor disk and a turbine blade attached to the blade groove. FIG. 3 is a schematic perspective view of an example in which turbine blades are fixedly installed in side entry type blade grooves provided in the rotor axial direction. It is the front view which showed an example at the time of attaching a turbine rotor blade to the side entry type blade groove part provided in the circumferential direction of the turbine rotor. It is a figure for demonstrating the ear | edge part in the T root type blade groove part provided in the circumferential direction of the turbine rotor disk. It is a figure for demonstrating the defect which arose in the implantation part for side entry type turbine blade mounting | wearing, (A) is the schematic seen from the top, (B) is the figure seen from the axial direction of the turbine rotor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Turbine rotor 11 Rotor blade 12 T route type blade groove part 13 Blade groove part ear | edge part 14 Phased array ultrasonic probe 15 Ultrasonic path 16 Defect 17 Ultrasonic probe opposing surface 20 Turbine rotor 21 Phased array probe for ultrasonic transmission ,
22 Phased Array Probe for Ultrasonic Reception 23 Defect in Implanted Portion for Turbine Blade Installation 24 Side Entry Type Blade Groove 25 Ultrasonic Path

Claims (4)

An ultrasonic probe is installed on a surface perpendicular to the axis of the turbine rotor, and a method for inspecting a defect generated in a T-root type implant portion provided in a circumferential direction of the peripheral edge of the turbine rotor,
The ultrasonic probe is a phased array type ultrasonic probe, and the T-route type implantation is performed by reflecting ultrasonic waves from the ultrasonic probe on a surface facing the ultrasonic probe installation surface. A turbine rotor blade groove inspection method characterized in that a point focus is made on the ear of a part, a sector scan is performed, the echo waveform of a healthy part is compared with the echo waveform of a defective part, and the presence or absence of a defect is evaluated by a difference.   The probe scans the probe in the circumferential direction while scanning the ultrasonic point focus position of the phased array type ultrasonic probe in the circumferential direction, and changes the noise level by comparing and referring to the data in the overlapping range of the scan data. The turbine rotor blade groove inspection method according to claim 1, wherein the presence or absence of the defect is evaluated from an amount. An ultrasonic probe is installed on a surface orthogonal to the axis of the turbine rotor, and a method for inspecting a defect generated in a side entry type implantation portion provided in the turbine rotor axial direction at the periphery of the turbine rotor,
The ultrasonic probe is a phased array type ultrasonic probe, an oscillating unit and a receiving unit are arranged in a radial direction of the turbine rotor, and ultrasonic waves from the ultrasonic probe are transmitted to the side entry type implanter. A turbine rotor blade groove inspection method characterized in that a point focus is applied to a recessed portion, an ultrasonic wave reflected by a defective portion by sector scanning is reflected and detected by another surface serving as a facing surface, and the presence or absence of a defect is evaluated.   The ultrasonic oscillator is installed in the vicinity of the center of the turbine rotor, and the ultrasonic point focus position is scanned in the radial direction of the turbine rotor while performing sector scan in the thickness direction of the turbine rotor. 4. The turbine rotor blade groove inspection method according to claim 3, wherein the presence / absence of a defect is evaluated from the amount of change in the noise level by comparing and referring to the data.

Images