JP2013057681A - Ultrasonic flaw detector of rotor disk for turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic flaw detector of a rotor disk for a turbine, which is applicable even in the case of a middle or small-sized rotor having a small blade groove and a rotor disk having the blade groove carved in a peripheral direction.SOLUTION: An ultrasonic flaw detector has a pair of ultrasonic measurement probes 9 disposed on both end surfaces of a rotor disk for a turbine facing each other, and performs ultrasonic flaw detection while moving the pair of probes in a peripheral direction of a turbine shaft. The ultrasonic flaw detector includes; arcuate guide bodies 18 and 19 which are provided on both surface sides of the rotor disk respectively and circulate concentrically with the turbine rotor shaft; and probe fixing parts 24 and 26 which are attached to the arcuate guide bodies 18 and 19 and have the ultrasonic measurement probes 9 fixed thereto. The arcuate guide bodies 18 and 19 are configured to be able to circulate via a driving body 32 provided in a rotor hole piercing the rotor disk. The probe fixing parts 24 and 26 include adjustment jigs 34 capable of positional adjustment of the ultrasonic measurement probes 9 in a rotor radial direction.

Description

  The present invention relates to an ultrasonic flaw detector for a turbine rotor disk, and more particularly to an ultrasonic flaw detector for a turbine rotor disk using probes provided on both end faces of a facing rotor disk.

  An ultrasonic flaw detection inspection is known as one of non-destructive inspections for detecting a crack or the like inside a material without physically destroying an inspection object.

As an example of the usage pattern of the ultrasonic flaw detection inspection, detection of a crack generated in the steam turbine blade groove portion can be mentioned.
One form of a rotor disk for a turbine is one in which blade grooves are carved in the circumferential direction. In such a rotor disk, since it is easy to receive reflected waves, it is not difficult to carry out ultrasonic flaw detection inspection. In a turbine blade with blade grooves carved in the circumferential direction of the rotor disk, cracks and Ultrasonic inspection for detecting defects such as corrosion has been put into practical use.

However, it is difficult to directly receive reflected waves when performing an ultrasonic flaw detection for detecting defects such as cracks and corrosion in a rotor disk in which blade grooves are carved in the radial direction of the rotor disk. . For this reason, it is difficult to detect defects such as cracks by ultrasonic flaw detection in a rotor disk in which blade grooves are carved in the radial direction.
For example, when carrying out the oblique flaw detection method from the upper part of the blade groove, it is necessary to install a probe between the moving blades, so the probe can be installed only within the reach of the inspector. . For this reason, ultrasonic flaw detection can be performed only within the reach of the inspector's hand, and the entire blade groove cannot be detected. In particular, with medium and small turbine rotors, there are even cases where the spacing between the rotor blades is so narrow that a probe cannot be installed.

Therefore, for example, Patent Document 1 discloses a technique for detecting defects such as cracks and corrosion by ultrasonic flaw detection even in a rotor disk having a blade groove carved in the circumferential direction.
The technique disclosed in Patent Document 1 is a technique related to ultrasonic flaw detection by a pitch catch method from a blade groove end portion using two probes, and more specifically, a blade groove tooth portion having a defect parallel to the length direction. A transmission-side longitudinal wave oblique angle probe having a refraction angle of 10 to 40 ° is installed on one of the blade groove end faces of the blade, and a similar receiving-side longitudinal wave oblique angle probe is installed on the other side, and reflected once on the blade groove wall surface. Propagation time of wall reflected wave propagating as back longitudinal wave, and wall surface defect reflected wave which is reflected once by blade groove wall surface and converted to transverse wave is reflected by defect and propagates to blade groove wall surface, then mode conversion to longitudinal wave again Thus, the defect is detected based on the time difference from the propagation time until it is received.

  Patent Document 2 discloses a technique in which an ultrasonic flaw detection test is semi-automated by fixing the probe position and rotating the rotor to relatively move the probe along the circumferential direction of the rotor. ing.

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

  However, in the technique disclosed in Patent Document 1, since it is necessary to install a probe on the end face of the blade groove tooth portion, it is not possible to install the probe in a medium / small rotor having a small blade groove. . Therefore, the technique disclosed in Patent Document 1 is only applicable to a rotor disk having a large blade groove, and there remains a problem that the application range of the technique is narrow.

  Further, in the technique disclosed in Patent Document 2, in order to fix the probe position and rotate the rotor for flaw detection, an auxiliary instrument such as a gantry that can rotate the rotor is necessary. The tools and equipment necessary for performing ultrasonic flaw detection are large-scale.

  Therefore, in view of the problems of the prior art, the present invention can be applied even to a medium / small rotor having a small blade groove, and does not require a large auxiliary tool, and the blade groove is carved in the circumferential direction. It is an object of the present invention to provide an ultrasonic flaw detector for a turbine rotor disk that can be applied even to a rotor disk of a specified form.

  In order to solve the above-described problems, in the reference invention, in an ultrasonic flaw detector for a turbine rotor disk that detects cracks and corrosion of the turbine rotor disk using an ultrasonic flaw detection probe, both end faces of the rotor disks facing each other are detected. The transmitting / receiving probe capable of transmitting and receiving ultrasonic signals is arranged at symmetrical positions in the axial direction of the turbine, and the reflected wave of the ultrasonic signal from the transmitting / receiving probe on one side, the other side probe The transmitted waves are received by both probes, and the presence or absence of cracks and corrosion is determined based on at least four waveform signals received by the transmission / reception probe.

As a result, the position where the probe is provided is not limited to the blade groove tooth portion, and can be applied regardless of the size of the blade groove portion.
Further, by receiving a reflected wave and a transmitted wave of the ultrasonic signal transmitted from the one side using a transmission / reception probe, at least four waveform signals can be obtained, and cracks and Since the presence or absence of corrosion is determined, erroneous determination of the presence or absence of cracks or corrosion can be prevented.

Further, a database in which cracks or corrosion forms corresponding to the four waveform signals are stored in a database may be provided, and the crack or corrosion forms may be determined from the four waveform signals based on the database.
By discriminating the form of cracks or corrosion based on the database, erroneous determination of the form of cracks or corrosion can be prevented.

  Further, as an invention of the method of the above-mentioned reference invention for achieving the object, in the ultrasonic testing method of a turbine rotor disk for detecting cracks and corrosion of the turbine rotor disk by using an ultrasonic testing probe, they face each other. Both probes transmit the reflected wave of the ultrasonic signal transmitted from one side of the transmitter / receiver probe arranged at the turbine axis direction symmetrical position on both ends of the rotor disk, and the transmitted wave to the other probe. The presence / absence of cracks and corrosion is determined based on at least four waveform signals received by the transmission / reception probe.

  The crack or corrosion mode may be determined from the four waveform signals based on a database of crack or corrosion modes corresponding to the four waveform signals.

  In order to solve the above problems, the present invention arranges ultrasonic measurement probes on both end faces of a turbine rotor disk facing each other, and performs ultrasonic flaw detection while moving the probe pair in the circumferential direction of the turbine rotor. In the ultrasonic flaw detector for a turbine rotor disk to be inspected, the ultrasonic measurement is provided on each of both sides of the rotor disk and is concentric with the turbine rotor shaft, and is attached to the arc guide body. A probe fixing portion to which the probe is fixed, and the arcuate guide body is configured to be able to go around via a driving body provided in a rotor hole penetrating the rotor disk. To do.

As a result, ultrasonic flaw inspection over the entire circumference of the rotor disk can be performed while the positions of the probe pairs arranged on both sides of the rotor disk are moved synchronously. Furthermore, since the probe pair can be moved by using a driving body, the probe pair can be moved easily and in a short time, and the probe pair can be moved accurately and synchronously. In addition, position measurement and control can be performed, and defects can be detected with high accuracy.
Further, since the ultrasonic flaw detection inspection is performed by scanning the probe pair, it is not necessary to rotate the rotor at the time of inspection, and a large auxiliary device is not required.
Further, since the rotor hole provided in the rotor disk is generally used, it is not necessary to process the rotor disk such as making a new hole. Moreover, since the rotor hole penetrating the rotor disk is used, by providing the same mechanism (arc-shaped guide body, probe fixing portion) on both surfaces of the rotor disk 5, the probe pair can be formed on both surfaces of the rotor disk. It is easy to move in synchronization.

The probe fixing unit may include an adjustment jig capable of adjusting the position of the ultrasonic measurement probe in the rotor radial direction.
Thereby, the position adjustment of the ultrasonic measurement probe is facilitated.

  As described above, according to the present invention, the present invention can be applied even to a medium / small rotor having a small blade groove, and does not require a large auxiliary tool, and the blade groove is carved in the circumferential direction. It is possible to provide an ultrasonic flaw detection apparatus and an ultrasonic flaw detection method for a turbine rotor disk that can be applied even to a rotor disk of this type.

It is the perspective view which showed a part of blade blade periphery provided in the rotor disk which performs an ultrasonic flaw detection test, and has shown the mode of the transmission and reception of an ultrasonic wave. It is the perspective view which showed a part of blade blade periphery provided in the rotor disk which performs an ultrasonic flaw inspection, and has shown another mode of transmission and reception of an ultrasonic wave. It is a table | surface which shows an example of the database of the relationship between a crack, a corrosion pit, and a UT waveform. It is the figure which showed an example of the observed UT waveform. 1 is a schematic view of a turbine rotor to which an ultrasonic flaw detector of the present invention is applied. It is a front view of a rotor disk in a state where an ultrasonic flaw detector is attached. It is a partial side view of a rotor disk with an ultrasonic flaw detector attached. It is a perspective view of an expansion-contraction mechanism.

  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.

An embodiment according to an ultrasonic flaw detector of the present invention will be described.
FIG. 1 shows a part of the periphery of a blade groove provided in a rotor disk that performs ultrasonic flaw detection in an embodiment. In FIG. 1, the rotor disk 5 is configured with a blade groove tooth portion 6 formed by providing a blade groove for implanting a blade. In addition, the A direction in FIG. 1 has shown the axial direction of the turbine, and the B direction has shown the radial direction of the turbine rotor. That is, in FIG. 1, the blade groove tooth portion 6 is formed on the outer peripheral side of the rotor disk 5.

Further, ultrasonic flaw detectors 9a and 9b are provided on both end surfaces 8 of the inner peripheral side (hereinafter referred to as a disk portion) 7 of the blade groove tooth portion 6 in the rotor disk 5, respectively.
The two probes 9a and 9b are installed at symmetrical positions along the axial direction A of the turbine. Further, the two probes 9a and 9b can both transmit and receive ultrasonic waves.
The two probes 9a and 9b are capable of transmitting ultrasonic waves at an arbitrary incident angle in a range of 30 to 70 ° with respect to the axial direction A of the turbine. Accordingly, the positions of the probes 9a and 9b are determined and arranged.

Next, a procedure for detecting defects such as cracks and corrosion generated in the blade groove teeth 6 by ultrasonic flaw detection will be described with reference to FIGS.
First, the ultrasonic wave O is transmitted from the one probe 9a in the same direction as the axial direction A of the turbine. Whether the two probes 9a and 9b are installed at symmetrical positions along the axial direction A of the turbine by receiving the ultrasonic wave transmitted from one probe 9a by the other probe 9b Check. When the two probes 9a and 9b are not installed at symmetrical positions along the axial direction A of the turbine, the position of one (9a or 9b) or both the probes 9a and 9b is adjusted and The probe 9a transmits ultrasonic waves in the same direction as the axial direction A of the turbine, and confirms whether the two probes 9a and 9b are installed at symmetrical positions along the same direction as the axial direction A of the turbine. To do. Until it is confirmed that the two probes 9a and 9b are installed in the same direction as the axial direction A of the turbine, the position adjustment of the probes 9a and 9b and the shaft of the turbine from one of the probes 9a are confirmed. The position confirmation of the probes 9a and 9b by transmitting in the same direction as the direction A is repeated.

  Next, as shown in FIG. 1, the ultrasonic wave a is transmitted toward the defect 10 from one probe 9a. The reflected wave 1 from the defect 10 of the ultrasonic wave a is received by the probe 9a on the side where the ultrasonic wave a is transmitted, and the transmitted wave 2 at the defect 10 of the ultrasonic wave a is received by the probe 9b on the other side. To do.

  Further, the ultrasonic wave a is transmitted from one probe 9a as shown in FIG. 1, and the ultrasonic wave b is transmitted from the probe 9b toward the defect 10 as shown in FIG. The transmitted wave at the defect 10 of the ultrasonic wave b is received by the probe 9a, and the reflected wave 4 at the defect 10 of the ultrasonic wave b is received by the probe 9b.

That is, the reflected wave of the ultrasonic wave a transmitted from the probe 9a (received by the probe 9a), the transmitted wave of the ultrasonic wave a transmitted from the probe 9a (received by the probe 9b), the probe Four types of ultrasonic flaw detection: ultrasonic wave b transmitted from probe 9b (received by probe 9a) and reflected wave of ultrasonic wave b transmitted from probe 9b (received by probe 9b) A waveform (hereinafter referred to as a UT waveform) can be confirmed.
The defect 10 is evaluated by these four types of UT waveforms.

The evaluation of the defect 10 using the four types of UT waveforms will be described.
A test body imitating the periphery of the blade groove tooth portion 6 of the rotor disk 5 with defects such as cracks and corrosion pits is created in advance, and a database of the relationship between cracks, corrosion pits and UT waveforms is created in advance.

An example of a database of relations between cracks, corrosion pits and UT waveforms created in advance will be described with reference to FIG.
In FIG. 3, in the leftmost column, crack A, crack B, crack C, crack D, corrosion pit A, corrosion pit B, and corrosion pit C each have a defect corresponding to the defect diagram illustrated in the second column on the left. It means that.
In FIG. 3, the columns indicated by 1 waveform, 2 waveforms, 3 waveforms, and 4 waveforms indicate the UT waveforms of reflected wave 1, transmitted wave 2, transmitted wave 3, and reflected wave 4 shown in FIGS. In the column, a circle echo is observed in the UT waveform, and in the column x, a defect echo is not observed in the UT wave type.

  As shown in FIG. 1 and FIG. 2, the waveforms of the reflected wave 1, transmitted wave 2, transmitted wave 3 and reflected wave 4 are confirmed, and the waveform is checked against a database as shown in FIG. Thus, the defect 10 can be evaluated.

FIG. 4 is a diagram showing an example of a UT waveform observed when the reflected wave 1, the transmitted wave 2, the transmitted wave 3, and the reflected wave 4 are confirmed as shown in FIGS. 4A is a UT waveform of the reflected wave 1, FIG. 4B is a UT waveform of the transmitted wave 2, FIG. 4C is a UT waveform of the transmitted wave 3, and FIG. An example of a waveform is shown.
When a UT waveform as shown in FIG. 4 is observed, echoes can be confirmed from each of FIGS. 4A and 4B, not only FIGS. 4B and 4C. In FIG. 3, this waveform corresponds to 1 waveform × 2 waveforms ○, 3 waveforms ○, 4 waveforms ×, so that the defect can be evaluated as a crack B.

In the embodiment of the present invention, the two probes 9a and 9b are installed at symmetrical positions along the axial direction A of the turbine, and the defect 10 is evaluated using four types of UT waveforms. For example, it is possible to provide two ultrasonic flaw detectors on each end face 8 of the disk portion 7 of the blade groove tooth portion 6 in the rotor disk 5 and evaluate the defect 10 from 16 types of UT waveforms. In this case, although it takes time and labor to install the probe and to create a database corresponding to FIG. 3, the defect 10 can be more accurately evaluated. Further, it goes without saying that three or more probes may be provided on each of the both end faces 8.
When two or more probes are provided on each of the both end faces 8, it is necessary to install the same number on both end faces and symmetrical positions along the axial direction A of the turbine.

  Next, the ultrasonic flaw inspection method described with reference to FIGS. 1 to 4 is applied, the two probes 9 are moved in synchronization, and an ultrasonic flaw detection test is performed over the entire circumference of the rotor disk. The acoustic flaw detector will be described.

First, the rotor disk 5 will be described.
FIG. 5 is a schematic view of a turbine rotor to which the ultrasonic flaw detector of the present invention is applied. The ultrasonic flaw detector of the present invention is applied to the rotor disk 5 constituting the turbine rotor 12 shown in part C in FIG.

  FIG. 6 is a front view of the rotor disk 5 with the ultrasonic flaw detector attached, and FIG. 7 is a partial side view of the rotor disk 5 with the ultrasonic flaw detector attached.

As shown in FIG. 6, the rotor disk 5 has a rotor shaft 36 extending through the center thereof. The rotor shaft 36 may be integrated with the rotor disk 5 in some cases.
Further, a plurality (four in FIG. 6) of rotor holes 16 are provided around the rotor shaft 36.

An ultrasonic flaw detector attached to such a rotor disk 5 will be described with reference to FIGS.
The ultrasonic flaw detector is mainly composed of a shaft 38 having gears 32 attached to both ends, a lower rail 18 and an upper rail 19, and a telescopic mechanism 24 to which the probe 9 is attached via a spring 26. Yes.

The lower rail 18 has a front circular shape, and is fixed to the rotor disk 5 concentrically with the rotor shaft 36 by fixing means such as a magnet. The lower rail 18 is fixedly installed on each side of the rotor disk 5.
The upper rail 19 has a front circular shape and is movably attached along the lower rail 18. Further, the inner peripheral side of the upper rail 19 has a gear shape and is formed so as to be capable of engaging with a gear 32 described later.
The lower rail 18 and the upper rail 19 have a front circular shape in this embodiment, but may have a front arc shape that forms a part of a circle, such as a front semicircle. In this case, installation of the lower rail 18 and the upper rail 19 is facilitated.

The shaft 38 has gears 32 attached to both ends and is installed through the rotor hole 16. The gears 32 attached to both ends of the shaft 38 are disposed so as to be able to engage with the gear-shaped portions on the inner peripheral side of the upper rail 19.
In order to enable engagement of the gear 32 with the inner peripheral side of the upper rail 19, the diameter of the lower rail 18 and the upper rail 19 and the diameter of the gear 32 are appropriately set in consideration of the position of the rotor hole 16. do it.

  Further, an expansion / contraction mechanism 24 is fixedly connected to the outer peripheral side of the upper rail 22 by connecting means 30 such as bolts and nuts. The probe 9 is attached to the expansion / contraction mechanism 24 via a spring 26. By using the spring 26 as a compression spring and attaching the probe 9 to the expansion / contraction mechanism 24 via the spring 26, the probe 9 is reliably brought into contact with the rotor disk 5 by the elastic force of the spring 26.

FIG. 8 is a perspective view of the telescopic mechanism 24 to which the probe 9 is attached via a spring 26.
The expansion / contraction mechanism 24 includes an inner cylinder 24a and an outer cylinder 24b. A male screw is formed on the outer side of the inner cylinder 24a and a female screw is formed on the inner side of the outer cylinder 24b. It can be expanded and contracted in the indicated D direction.

  The probe 9 corresponds to the probes 9a and 9b shown in FIGS. 1 and 2, and can transmit and receive ultrasonic waves.

A procedure for performing an ultrasonic flaw detection in the configuration described with reference to FIGS.
First, in the same manner as described with reference to FIG. 1, an ultrasonic wave is transmitted from one probe 9 to the other probe 9 in the same direction as the axial direction of the turbine. Is installed in a symmetrical position along the axial direction of the turbine, and if necessary, adjustment is made so that it is installed in the symmetrical position.

  Next, in the same manner as described with reference to FIG. 1, ultrasonic waves are transmitted from both of the two probes 9, and reflected waves and transmitted waves are received by the two probes 9, respectively. Evaluate deficiencies using the database shown.

  Next, the gear rotation lever 34 is manually or automatically rotated while continuing to transmit ultrasonic waves from the probe 9, receive reflected waves and transmitted waves, and evaluate defects using a database. By rotating the gear rotation lever 34, the shaft 38 rotates, and the gears 32 provided at both ends of the shaft 38 also rotate. As the gear 32 rotates, the upper rail 22 moves along the lower rail 18, and the expansion / contraction mechanism 24 attached to the upper rail 22 and the probe 9 attached to the expansion / contraction mechanism 24 via a spring 26 are connected to the rotor shaft. It rotates concentrically with 36. That is, by rotating the gear rotation lever 34, the two probes 9 provided on both surfaces of the rotor disk 5 are rotated concentrically with the rotor shaft 36 in synchronization.

As a result, ultrasonic flaw detection can be performed over the entire circumference of the rotor disk 5 while the positions of the two probes 9 arranged on both surfaces of the rotor disk 5 are moved synchronously. Further, since the two probes 9 can be moved simply by turning the gear rotating lever 34, the two probes 9 can be moved easily and in a short time, and the two probes 9 can be moved in synchronism accurately. Therefore, the position can be measured and controlled accurately, and the defect can be detected with high accuracy.
Further, since the ultrasonic inspection is performed by scanning the probe 9, it is not necessary to rotate the rotor during the inspection, and a large auxiliary device is not necessary.
Furthermore, since the rotor hole 16 normally provided in the rotor disk 5 is used, it is not necessary to process the rotor disk 5 such as making a new hole. In addition, since the rotor holes penetrating the rotor disk 5 are used, the same mechanism (gear 32, lower rail 18, upper rail 22, extension mechanism 24, etc.) is provided on both sides of the rotor disk 5, so that the rotor disk It becomes easy to move the five-sided probes 9 in synchronization.

  The mechanism described with reference to FIGS. 5 to 8 is not limited to the ultrasonic flaw detection method of the present invention described with reference to FIGS. 1 to 4, and two or more probes are moved in conjunction with each other. It can be applied to ultrasonic flaw detection that needs to be performed. For example, the present invention can be applied even when one of the two probes 9 shown in FIG. 7 is dedicated to ultrasonic transmission and the other is dedicated to ultrasonic reception. Further, the present invention can also be applied to the flaw detection of a rotor that is blade-machined in the circumferential direction.

  Applicable even to medium and small rotors with small blade grooves, no need for large auxiliary tools, and applicable to rotor disks with blade grooves carved in the circumferential direction The present invention can be used as an ultrasonic flaw detection apparatus and an ultrasonic flaw detection method for a turbine rotor disk.

DESCRIPTION OF SYMBOLS 5 Rotor disk 6 Blade groove tooth part 7 Disk part 8 Both ends 9a and 9b of a disk part Probe 10 Defect 12 Turbine rotor 16 Rotor hole 18 Lower rail 22 Upper rail 24 Telescopic mechanism 26 Spring 32 Gear 34 Gear rotation lever 36 Rotor shaft 38 Shaft

Claims (2)

Place ultrasonic measuring probes on both end faces of the turbine rotor disk facing each other,
In an ultrasonic flaw detector for a turbine rotor disk that performs ultrasonic flaw detection while moving the probe pair in the circumferential direction of the turbine rotor axis,
An arcuate guide body provided on each side of the rotor disk and concentrically with the turbine rotor shaft;
A probe fixing portion attached to the arcuate guide body and to which the ultrasonic measurement probe is fixed;
An ultrasonic flaw detection apparatus for a rotor disk for a turbine, wherein the arcuate guide body is configured to be able to go around via a driving body provided in a rotor hole penetrating the rotor disk. The ultrasonic probe of the turbine rotor disk according to claim 1, wherein the probe fixing portion includes an adjustment jig capable of adjusting the position of the ultrasonic measurement probe in the rotor radial direction. apparatus.

Images