JP2013088346A - Three-dimensional ultrasonic flaw inspection method for turbine rotor blade fork - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a three-dimensional ultrasonic flaw inspection method for inspecting ultrasonic flaws of a stress part of a turbine rotor blade thoroughly and reducing a time for flaw inspection.SOLUTION: In the three-dimensional ultrasonic flaw inspection method for a turbine rotor blade fork which rotates and scans a sector scanning surface scanning an angle of refraction in an arch shape, with an angle of rotation of the sector scanning surface where a pin hole is detected by providing a step for detecting pin holes as a starting point, three-dimensional rotation scanning is performed to the sector scanning surface at angle pitch smaller than 2.7°, and the angle of rotation of the scanning surface where a step is detected by providing a step for detecting steps is regarded as an end point or rotation scanning.

Description

  The present invention relates to an ultrasonic flaw detection method for a turbine blade fork, and more particularly to an ultrasonic flaw detection method capable of shortening a flaw detection time while maintaining high flaw detection accuracy.

  As shown in FIGS. 11 and 12, in the turbine of the power plant, the rotating shaft 4 and the moving blade 2 are separately manufactured to improve the manufacturability and maintainability, and the turbine having the disk 3 on the rotating shaft 4 and the step 8 is provided. A rotor blade fork (hereinafter referred to as a fork) is combined, and a pin 7 is inserted into a pin hole 6 of the disk 3 and the fork 5 to fix them.

  As shown in FIG. 13, stress is generated at the position 100 of the pin hole 6 with the rotation of the turbine. For this reason, the soundness of the stress part 100 is inspected by an ultrasonic flaw detection method (Ultrasonic Testing: UT). UT is an inspection method in which ultrasonic waves are transmitted into an inspection object and a reflected wave (echo) from a defect is received, and the presence or absence of an echo corresponds to the presence or absence of a defect.

  In the conventional UT of the pin hole stress portion, as shown in FIG. 14, an ultrasonic sensor (UT sensor) is provided on the sensor installation surface 101 which is a side plane portion of the fork 5 provided perpendicular to the rotation axis of the turbine and parallel to the rotation direction. 1 was installed, and ultrasonic waves were incident on the stress portion 100 while rotating and translating the UT sensor 1 (Patent Document 1). In this flaw detection method, as shown in the reference sample flaw detection example in FIG. 15A, a shape signal around the pin hole is detected as a reference signal. 15A, a defect signal is detected in the vicinity of the shape signal as shown in the flaw detection example of FIG. 15B.

Japanese Patent No. 4474395

  In the above-mentioned Patent Document 1, since the UT sensor is mechanically moved manually or by an actuator, there is a possibility that an area in which ultrasonic waves are not transmitted / received due to a deviation in sensor direction may occur. Further, since the UT sensor is mechanically moved, there is a problem that it takes time for inspection.

  An object of the present invention is to provide a three-dimensional ultrasonic flaw detection method capable of reducing flaw detection inspection time and flaw detection throughout a stress portion of a fork.

  The present invention rotates an ultrasonic sector scan surface that scans a refraction angle in an arc shape by an ultrasonic sensor, an ultrasonic flaw detector, and a control device with respect to a fork having a pin hole and a step for pin joining to a turbine body. In a three-dimensional ultrasonic flaw detection method for a turbine blade fork that scans and flaws, a pin hole detection step that detects a pin hole of the fork, an ultrasonic flaw detection step that executes a three-dimensional ultrasonic flaw of the fork, A step detecting step for detecting a step of the fork, wherein the pin hole detecting step includes a pin hole echo detection confirming step for detecting the pin hole echo of the fork, and the ultrasonic flaw detection step is performed on the fork. And a step of determining a rotation angle of rotation for determining an angular pitch for rotationally scanning the sector scanning plane to be less than 2.7 °. -Up is characterized by having a step echo detection confirmation step of detecting a step echoes of the fork.

  In the three-dimensional ultrasonic flaw detection method for a turbine blade fork, the rotation angle of the sector scanning surface in which the pinhole echo is detected in the pinhole echo detection confirmation step is set as the start point or the end point of the rotational scanning of the sector scanning surface. It is characterized by.

  In the three-dimensional ultrasonic flaw detection method for a turbine blade fork, the rotation angle of the sector scanning surface in which the step echo is detected in the step echo detection confirmation step is set as the end point or start point of the rotational scanning of the sector scanning surface. It is characterized by.

  Further, in the three-dimensional ultrasonic flaw detection method for a turbine blade fork, the rotation angle of the sector scanning surface in which the pin hole is detected in the pin hole echo detection confirmation step is set as the start point or the end point of the rotational scanning of the sector scanning surface, The rotation angle of the sector scanning surface in which the step is detected in the step echo detection confirmation step is defined as the end point or start point of the rotational scanning of the sector scanning surface.

  In the three-dimensional ultrasonic flaw detection method for a turbine blade fork, the pin hole detection step includes a UT sensor installation step, a measurement start signal input step, a pin hole echo detection confirmation step, and a flaw detection start point determination step. The ultrasonic flaw detection step includes a rotation angle pitch determination step of a sector scanning surface, a delay time determination step, and an ultrasonic flaw detection step, and the step detection step includes an ultrasonic flaw detection result processing / display step, It has a step echo detection confirmation step.

Furthermore, in the three-dimensional ultrasonic flaw detection method for a turbine rotor blade fork in which the fork is flaw-detected by rotationally scanning the sector scanning surface with an ultrasonic sensor, an ultrasonic flaw detection device and a control device with respect to the fork,
A fork shape data input step for inputting the fork shape to the control device, a sensor position measuring step for determining the position of the ultrasonic sensor on the fork, and an ultrasonic flaw detection step for three-dimensional flaw detection of the fork. The sensor position measuring step further includes a sector scanning rotation angle pitch determining step for rotationally scanning the sector scanning surface at an angle pitch equal to or less than the angle φ described by the following equation on the fork:
φ = cos ⁻¹ [(a ² + b ² −2r ² ) ÷ (2 · a · b)]
a = √ [(Δy−r) ² + Δx ² ]
b = √ [Δy ² + (Δx−r) ² ]
Δx: Fork width [m]
Δy: Distance between upper end of fork and pin hole center [m]
r: Pin hole radius [m]
An ultrasonic transmission / reception step of rotationally scanning the sector scanning surface at an angular pitch φ;
A sensor position analyzing step for determining the position of the ultrasonic sensor is provided.

  Further, in the three-dimensional ultrasonic flaw detection method for a turbine blade fork, the ultrasonic flaw detection step for three-dimensional flaw detection of the fork determines the rotation angle range of the sector scanning surface and sets the rotation angle pitch of the sector scanning surface to 2.7. A rotation angle pitch determination step of the sector scanning plane determined within a range of less than 0 °, an ultrasonic delay time determination step, and an ultrasonic flaw detection step for executing the three-dimensional ultrasonic flaw detection of the fork.

  Furthermore, the sensor position measuring step is characterized in that an area where the ultrasonic sensor exists is determined by measuring a distance between two pin holes of the pin hole of the fork and the ultrasonic sensor.

  Further, the sensor position measuring step measures a distance between the pin hole of the fork and the step of the fork and the ultrasonic sensor, and determines a first curve where the ultrasonic sensor exists in the area. It is characterized by doing.

  Further, the sensor position measuring step measures a distance between the pin hole of the fork and the step different from the step and the ultrasonic sensor, and determines a second curve in which the ultrasonic sensor exists, The intersection of the first curve and the second curve is the ultrasonic sensor position.

  Further, the rotation angle of the sector scanning surface where the pin hole is detected, measured in the sensor position measuring step, is set as the start point or the end point of the rotational scanning of the sector scanning surface.

  Further, the scanning direction of the sector scanning surface where the step is detected, which is measured in the sensor position measuring step, is set as the end point or the starting point of the rotational scanning of the sector scanning surface.

  Further, the sector scan in which the step is detected by using the rotation angle of the sector scanning surface where the pin hole measured in the step of evaluating the installation position of the ultrasonic sensor is detected as the start or end point of the rotational scanning of the sector scanning surface. The scanning direction of the surface is the end point or the starting point of the rotational scanning of the sector scanning surface.

According to the present invention, in a three-dimensional ultrasonic flaw detection method for a turbine blade fork in which a fork having a pin hole and a step is rotated and scanned by an ultrasonic sensor, an ultrasonic flaw detector, and a control device. , A pin hole detection step, an ultrasonic flaw detection step for performing three-dimensional ultrasonic flaw detection, and a step detection step, the pin hole detection step has a pin hole detection confirmation step for detecting the pin hole of the fork, The ultrasonic flaw detection step has a scanning rotation angle pitch determination step for determining the ultrasonic sector scanning plane with respect to the fork as a rotation angle pitch of less than 2.7 °, and the step detection step detects the step of the fork. By having a confirmation step
Since the stress range of the fork hole can be detected at an angle pitch equal to or less than a predetermined value, the reliability of the three-dimensional ultrasonic inspection is improved. In addition, since the ultrasonic flaw detection scan of the fork is executed by electrical control, the inspection time is reduced compared with the conventional ultrasonic flaw detection method in which the UT sensor is mechanically moved, and the data processing amount is reduced by setting the accurate scan range. This can reduce the inspection time.

1 is a block diagram showing an ultrasonic flaw detection system according to Embodiment 1 of the present invention. 1 is a schematic diagram showing the structure of an ultrasonic sensor according to a first embodiment of the present invention. The schematic diagram which shows the three-dimensional ultrasonic flaw detection method of Example 1 of this invention. The graph which shows the example of evaluation of the delay time of Example 1 of this invention. BRIEF DESCRIPTION OF THE DRAWINGS Explanatory drawing which shows the ultrasonic three-dimensional scanning method of Example 1 of this invention. BRIEF DESCRIPTION OF THE DRAWINGS Explanatory drawing which shows the ultrasonic three-dimensional scanning method of Example 1 of this invention. 1 is a flowchart showing an ultrasonic flaw detection method according to Embodiment 1 of the present invention. The schematic diagram which shows the sector scanning surface rotation angle of the receiving intensity of Example 1 of this invention. 6 is a graph showing the sector scan plane rotation angle dependency of the reception intensity according to the first embodiment of the present invention. 7 is a flowchart showing an ultrasonic flaw detection method according to Embodiment 2 of the present invention. Explanatory drawing which shows the sector scanning surface rotation scanning pitch determination method in the sensor position measurement step of Example 2 of this invention. Explanatory drawing which shows the sensor position evaluation method of Example 2 of this invention. Explanatory drawing which shows the sensor position evaluation method of Example 2 of this invention. Explanatory drawing which shows the sensor position evaluation method of Example 2 of this invention. Explanatory drawing which shows the sensor position evaluation method of Example 2 of this invention. Explanatory drawing which shows the turbine of a prior art example. The perspective view which shows the turbine bucket fork of a prior art example. The perspective view which shows the stress part of the turbine rotor blade fork of a prior art example. The schematic diagram which shows the ultrasonic flaw detection method of the turbine rotor blade fork of a prior art example. Explanatory drawing which shows the example of ultrasonic flaw detection of the healthy part of the turbine blade fork of a prior art example. Explanatory drawing which shows the example of ultrasonic flaw detection of the defective part of the turbine rotor blade fork of a prior art example.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a block diagram illustrating an ultrasonic flaw detection system according to the first embodiment. The ultrasonic flaw detection system according to the first embodiment includes a UT sensor 1 including a phased array ultrasonic sensor, an ultrasonic flaw detection apparatus 10, a data processing apparatus, a personal computer 9 as a control apparatus for determining ultrasonic flaw detection conditions, and various types used in the same. Consists of a computer program.

  Here, the personal computer 9 includes an HDD 22, a RAM 23, and a ROM 24 connected to the CPU 21, and the CPU 21, the keyboard 26, the recording medium 27, and the monitor 28 are connected to the ultrasonic flaw detector 10 via the I / O port 25a. The ultrasonic flaw detector 10 has an I / O port 25b connected to the I / O port 25a of the personal computer 9, and an A / D converter 29 and a D / A converter 30 connected to the I / O port 25b. The flaw detection apparatus 10 is connected to the UT sensor 1.

  Among these, as shown in FIG. 2, the UT sensor 1 has rectangular parallelepiped ultrasonic elements 31 arranged in two directions and accommodated in a protective case 34. The individual ultrasonic elements 31 constituting the UT sensor 1 include an electrode 32 provided on the bottom surface facing the inspection target and a signal line (not shown) that applies a voltage to the electrode 32B provided on the upper surface of each ultrasonic element 31. And a damper 33 provided on the electrode 32B for absorbing the energy of the oscillated ultrasonic wave. The damper 33 can reduce the after vibration during ultrasonic oscillation and improve the S / N ratio.

As the material of the ultrasonic element 31, a piezoelectric element such as PZT (piezoelectric ceramic: Pb (Zr, Ti) O ₃ ), LiNbO ₃ , PVDF (polymer piezoelectric element: Polyvinylidene Fluoride) can be used. The electrodes 32 and 32B are made of a highly conductive metal such as Au, Ag, or Cu, a copper wire as the signal line, and a heavy metal such as Hf, W, or Ta mixed in the resin as the damper 33. Is preferably used. The protective case 34 is preferably molded and used from one or more materials of resin and metal.

  FIG. 3 is a schematic diagram showing a method of performing ultrasonic flaw detection using the UT sensor 1. As shown in FIG. 3, when performing an ultrasonic flaw detection, a delay time between the ultrasonic elements 31 so that the ultrasonic waves simultaneously reach the focal point 36 from a plurality of ultrasonic elements 31 arranged in parallel in the UT sensor 1. Adjust.

  Here, the maximum distance between the ultrasonic element 31 and the focal point 36 is max (L) [m], and the distance between the i-th ultrasonic element 31 in the x-axis direction and the j-th ultrasonic element 31 in the y-axis direction and the focal point 36 in the figure. Lij [m], the ultrasonic wave propagation speed (sound velocity) is V [m / s], the X coordinate of the ultrasonic element 31 is xij [m], the Y coordinate of the ultrasonic element 31 is yij [m], and the focal point 36. Xf [m], and the Y coordinate of the focal point 36 is yf [m].

At this time, the distance Lij [m] between the i-th ultrasonic element 31 in the x-axis direction and the j-th ultrasonic element 31 in the y-axis direction and the focal point 36, and the ultrasonic oscillation start time difference dt [s] (hereinafter, referred to as each ultrasonic element 31). Are expressed by the following equations (1) and (2).
[Equation 1]
Lij = ((xij−xf) ² + (yij−yf) ² ) ^1/2 [m] (1)
[Equation 2]
dt = (max (L) −Lij) / V [s] (2)

FIG. 4 is a graph showing the element position of the UT sensor 1 on the horizontal axis and the delay time dt [s] on the vertical axis. In the example of FIG. 4, three element rows composed of eight elements are installed, and the time difference when the focus is placed on the position closest to the element in the second row and the fifth position is represented. Specifically, the total number of ultrasonic elements 31 is 24, V = 5780 [m / s], xi = (0.5i−0.25) × 10 ⁻³ [mm], yi = 0 [m], xf The delay time dt [s] is shown when = 0 [m] and yf = 3 × 10 ⁻² [m].

  When the ultrasonic elements far from the focal point are oscillated quickly with the delay time of FIG. 4, the ultrasonic wave arrival time from each element to the focal point is uniform, so that the signal intensity can be increased.

  Next, the fork UT method using the three-dimensional ultrasonic flaw detection according to the first embodiment will be described with reference to FIGS. 5A and 5B. In this flaw detection method, as shown in FIG. 5A, a UT sensor is provided on the sensor installation surface 101, and scanning is performed by changing the refraction angle and the focal length of the ultrasonic wave within a predetermined range within the sector surface, corresponding to the refraction angle and the focal length. The reflected ultrasonic echo intensity is displayed on a two-dimensional plane (generation of a sector scan image).

  Next, as shown in FIG. 5B, the sector scanning surface is rotationally scanned to scan the fork 5 three-dimensionally with ultrasonic waves. In the UT of the fork according to the first embodiment, as shown in FIG. 5B, the sector scanning surface scanning direction in which the pinhole echo is detected is started, and the sector scanning surface perpendicular to the paper surface is rotationally scanned in the step direction. The point where the step echo is detected is set as the scanning end point. By rotating and scanning the sector scanning surface until the echo from the step is detected, it is possible to inspect all the stressed portions of the pin hole 6 shown in FIG.

  Next, referring to the flowchart of the ultrasonic flaw detection method for the turbine blade fork shown in FIG. 6 using the ultrasonic flaw detection system of FIG. 1, a method for carrying out the three-dimensional ultrasonic flaw detection of FIGS. 5A and 5B will be described.

First, an outline of the flowchart will be described. The flowchart of FIG. 6 is roughly divided into a pin hole echo detection step S101, an ultrasonic flaw detection step S102, and a step echo detection step S103. Among these, the pin hole detection step S101 is used to determine the flaw detection start point. In the ultrasonic flaw detection step S102, ultrasonic flaw detection is performed by three-dimensional scanning. The scanning angle pitch at this time is determined to be a predetermined value or less so that the flaw can be detected throughout the stressed portion. The step echo detection step S103 is used to determine the flaw detection end point. Hereinafter, all the steps executed sequentially will be described.
(1) Pinhole echo detection step S101
First, the pin hole detection step S101 will be described. First, in S101a, the operator installs the UT sensor 1 on the sensor installation surface 101 so that the front direction of the UT sensor 1 is substantially opposed to the pin hole 6. Here, the front direction of the UT sensor 1 is a perpendicular direction in the short direction of the ultrasonic element shown in FIG. 2 on the sensor installation surface 101.

  Next, in S101b, the operator inputs a pin hole detection start signal from the keyboard 26 of the personal computer 9 in FIG. The pin hole detection start signal is transmitted to the CPU 21 through the I / O port 25a of the personal computer. After inputting the detection start signal, the ultrasonic wave is sector-scanned in the front direction of the UT sensor 1. The scanning range of the refraction angle of the sector surface is a range including 35 to 55 ° where the reflection efficiency of the ultrasonic wave is high, and the focal length of the ultrasonic wave is an approximate distance from the position where the UT sensor 1 is installed in S101a to the pin hole 6. To do.

  The sector scan delay time for pin hole detection is analyzed before installing the UT sensor on the sensor installation surface 101 and stored in advance in at least one storage device of the HDD 22 and RAM 23 of the personal computer 9. When the detection start signal is input, the CPU 21 reads it and applies a voltage to the UT sensor 1 via the I / O port 25a of the personal computer 9, the I / O port 25b of the ultrasonic flaw detector 10 and the D / A converter 30. Send ultrasound.

  Echoes from the irregularities in the fork 5 are converted into voltage by the UT sensor 1 and transmitted to the CPU 21 via the A / D converter 29, the I / O port 25b of the ultrasonic flaw detector 10 and the I / O port 25a of the personal computer 9. Is done. The CPU 21 records the echo detection distance and the refraction angle in at least one storage device of the HDD 22 and RAM 23, and displays the echo generation angle, generation distance, and intensity on the monitor 28 via the I / O port 25a.

  Next, based on the display on the monitor in S101b, whether or not a pin hole signal is detected is confirmed in S101c. Since the approximate position of the UT sensor is known and the approximate refraction angle and distance at which the pin hole signal is detected are determined, the operator determines whether the shape signal is detected in the vicinity of the refraction angle / distance. Determine whether a signal is detected. When the pin hole signal is not detected, the orientation and position of the UT sensor 1 are readjusted until the pin hole signal is detected.

After confirming the detection of the pin hole signal in S101c, in S101d, the operator inputs a signal for setting the pin hole signal detection point as the starting point of the rotational scanning of the sector scanning surface from the keyboard 26, and through the I / O port 25a of the personal computer 9. Are transmitted to the CPU 21 and stored in at least one storage device of the HDD 22 and the RAM 23.
(2) Ultrasonic flaw detection step S102
In step S102, UT using the ultrasonic flaw detector 10 is executed. First, in S102a, the rotation angle (rotation angle pitch) per scan of the rotation scan of each sector scan plane is determined. Increasing the rotation angle speeds up flaw detection by reducing the number of scanning points, but there may be a location where ultrasonic waves do not reach between the sector scanning surfaces. For this reason, the rotation angle pitch of the sector scanning surface must be determined within a range in which a portion where the ultrasonic wave does not reach does not occur.

  7A and 7B explain the dependency of the signal detection intensity on the rotation angle of the sector scanning plane. As shown in FIG. 7A, the rotation angle here is the rotation angle of the sector scanning surface with respect to the reference position when the scanning surface angle is 0 ° when the inspection target position is on the sector scanning surface. As shown in FIG. 7B, since the echo detection intensity becomes 0 when the sector scanning plane rotates about 2.7 ° from the inspection position, the rotation angle pitch of the sector scanning plane needs to be less than 2.7 °. That is, the rotation angle of the sector scanning surface is determined at a rotation angle pitch of less than 2.7 ° from the scanning start angle of the sector scanning surface determined in S101c.

  The rotation angle dependency of the detection intensity on the sector scanning plane is determined by the ultrasonic element size, the distance between the defect and the sensor, the size of the defect, and the like, and is determined from the actual flaw detection inspection conditions.

  In S102b, the formula stored in at least one storage device among the HDD 22, RAM 23, and ROM 24 from the distance between the pin hole 6 measured in 101c and the UT sensor 1 and the rotation angle scanning condition of the sector scanning surface obtained in 102a. In accordance with (1) and equation (2), the CPU 21 calculates the delay time using a delay time calculation program for determining the delay time of each ultrasonic element.

In S102c, a voltage is applied to the UT sensor 1 via the I / O port 25a of the personal computer 9, the I / O port 25b of the ultrasonic flaw detector 10 and the D / A converter 30 based on the delay time obtained in S102b. Send ultrasonic waves and perform ultrasonic flaw detection. The echo from the fork 5 is converted into a voltage by the UT sensor 1 and transmitted to the CPU 21 via the A / D converter 29, the I / O port 25b of the ultrasonic flaw detector 10 and the I / O port 25a of the personal computer 9. The The CPU 21 records the intensity, angle of refraction, and distance of the echo in at least one storage device of the HDD 22 and RAM 23, and displays it on the monitor 28 via the I / O port 25a.
(3) Step echo detection step S103
Finally, in step S103, it is confirmed whether a step echo that is an inspection end signal is detected. First, in S103a, the echo intensity obtained in the ultrasonic flaw detection step in S102c is displayed in color tone with respect to the refraction angle and distance.

  Next, in S103b, the operator confirms the presence or absence of a step echo from the flaw detection image displayed in S103a. Since the position of the step 8 with respect to the pin hole 6 is determined, the relative position of the step echo with respect to the detection position of the pin hole signal is also determined. Whether or not a step echo is detected is confirmed from whether or not a shape signal is detected at that position. If the step echo is not detected, the flaw detection is performed again from step S101.

  After confirming the detection of the step echo, an inspection end signal is input from the keyboard 28 and transmitted to the CPU 21 via the I / O port 25a of the personal computer 9 to complete the ultrasonic flaw detection.

  Since the first embodiment is configured as described above, it is possible to detect flaws by rotational scanning of the sector scanning plane throughout the stress range of the turbine rotor blade fork. Further, conventionally, ultrasonic scanning is mechanically performed. However, since scanning is performed electronically, the speed can be increased.

  Next, Embodiment 2 of the present invention will be described with reference to the drawings. The configuration diagram of the ultrasonic flaw detection system used is the same as that shown in FIG. 1, and the flowchart of the ultrasonic flaw detection method is configured as shown in FIG.

  In the first embodiment, the operator determines the rotational scanning start point and end point of the sector scanning surface based on the flaw detection image, whereas in the second embodiment, the sensor position installed on the fork is automatically measured by transmitting and receiving ultrasonic waves. And a starting point and an ending point for rotational scanning of the sector scanning surface are automatically determined.

Hereinafter, a three-dimensional ultrasonic flaw detection method for a turbine rotor blade fork according to the second embodiment will be described with reference to FIGS. 1 and 8. The flowchart of the inspection step in the embodiment 2 of FIG. 8 is roughly divided into four steps of a fork shape data input step S201, a sensor position measurement step S202, an ultrasonic flaw detection step S203, and a flaw detection range confirmation step S204.
(1) Fork shape data input step S201
In step S201, fork shape data is input from the recording medium 27 of the personal computer 9 and stored in at least one storage device of the HDD 22 and RAM 23 via the I / O port 25a of the personal computer 9 and the CPU 21. As the recording medium 27, a Blu-ray disc, DVD or the like is used. Further, the shape data can be stored in advance in an HDD or the like in the personal computer.
(2) Sensor position measurement step S202
In S202a, the operator inputs a measurement start signal from the keyboard 28 of FIG. 2 and transmits it to the CPU 21 via the I / O port 25a of the personal computer 9. The CPU 21 recognizes this and measures the sensor position on the fork 5. Start.

  The measurement of the sensor position in S202b is performed by rotationally scanning the sector scanning surface at a constant angular pitch φ.

FIG. 9 is an explanatory diagram of the rotational scanning angle pitch φ of the sector scanning plane necessary for detecting the pin holes 6. When the UT sensor 1 is installed on the sensor installation surface 101 and the sector scanning surface is rotationally scanned, in order to make any sector scanning surface enter the pin hole, the rotational scanning angle pitch is set to the upper end 103 of the pin hole 6, the pin It is necessary to make the angle φ or less between the point 104 on the pin hole rotated 90 ° from the upper end 103 of the hole 6 about the axis of the pin hole and the UT sensor 1. When the sensor is installed at the end point 102 of the sensor installation surface 101, φ is minimized. When the UT sensor is installed at another position on the sensor installation surface 101, the angle formed between the two ends 103 and 104 on the pin hole and the UT sensor is larger than the angle φ. When the surface is rotationally scanned, one of the sector scanning surfaces enters the pin hole 6. This angular pitch φ is described by the following equations (3) to (5).
[Equation 3]
φ = cos ⁻¹ [(a ² + b ² −2r ² ) ÷ (2 · a · b)] (3)
[Equation 4]
a = √ [(Δy−r) ² + Δx ² ] (4)
[Equation 5]
b = √ [Δy ² + (Δx−r) ² ] (5)
here,
Δx: Fork width [m]
Δy: Distance between upper end of fork and pin hole center [m]
r: Pin hole radius [m]
Represents.

  Using the sector surface rotation scanning angle pitch calculation program for calculating the angle pitch φ based on the fork shape data input in step S201 and the equations (3) to (5) stored in the HDD 22, RAM 23, ROM 24, Ask for. The sector scanning plane is rotationally scanned at an angular pitch of φ or less with the front direction of the UT sensor 1 as a base point.

  The sector scanning angle range is a range including 35 to 55 ° where the reflection efficiency of the ultrasonic wave is high, and the focal length of the ultrasonic wave is the distance from the UT sensor 1 to the pin hole 6. The ultrasonic scanning delay time is calculated by the CPU 21 using a numerical calculation program for obtaining the delay time according to the equations (1) and (2) stored in at least one storage device of the HDD 22, RAM 23, and ROM 24. To do.

  In S202c, a voltage is applied to the UT sensor 1 via the I / O port 25a of the personal computer 9, the I / O port 25b of the ultrasonic flaw detector, and the D / A converter 30 based on the delay time calculation result of S202b. Send ultrasound. As a result, the echo generated in the fork 5 is received by the UT sensor 1 and transmitted to the CPU 21 via the A / D converter 29, the I / O port 25b of the ultrasonic flaw detector 10 and the I / O port 25a of the personal computer. , HDD 22, RAM 23 to be stored in one or more storage devices.

  In S202d, the sensor position on the fork 5 is automatically analyzed from the echo generation direction and generation distance acquired in S202c.

  10A to 10D are explanatory diagrams of the analysis method, and the sensor position is obtained using the distance between the pin hole 6A, the pin hole 6B and the step 8 and the UT sensor 1. FIG. Each figure shows a method of determining the sensor position, but each accuracy is different, and any method may be used according to the conditions.

  FIG. 10A is a method of analyzing the position where the UT sensor 1 can be calculated from the distance between the pin hole 6A and the UT sensor 1. For example, the center of any point a, b, c on the pin hole 6A is S203c. The UT sensor 1 exists on an arc group whose radius is the measured distance between the pin hole 6 </ b> A and the UT sensor 1.

  FIG. 10B is a sensor position analysis method in consideration of the distance between the pin hole 6A and the pin hole 6B and the UT sensor 1, and the radius between the distance between the pin hole 6A and the UT sensor 1 with the point on the pin hole 6A as the center. The UT sensor 1 exists in an area surrounded by the intersection of the arc group and the arc group with the point on the pin hole 6B as the center and the distance between the pin hole 6B and the UT sensor 1 as the radius.

  FIG. 10C shows a sensor position analysis method in consideration of the distance between one point on the pin hole 6 </ b> A and the step 8 and the UT sensor 1. In this method, the distance between the pin hole 6A and the sensor 1, and the distance between the step 8 and the sensor 1 are obtained in S202c. Further, the scanning direction in which the pin hole 6A is detected and the scanning direction in which the step 8 is detected are also obtained in S202c. Accordingly, a triangle having the vertexes of the sensor, the reflection point of the pin hole 6A, and the reflection point of the step 8 is uniquely determined. Curve 1 drawn when the vertex corresponding to the reflection point of this triangular pin hole 6A is moved so that the vertex corresponding to the step is in contact with the pin hole, and the vertex corresponding to the step 8 is in contact with the step. Sensor 1 is on the top.

  FIG. 10D shows a sensor position analysis method when the distance from the UT sensor 1 is taken into consideration by adding another point on the pin hole 6A and the step 8. FIG. Also in this method, the distance between the pin hole 6A and the sensor 1, and the distance between the step 8 and the sensor 1 are obtained in S202c. Further, the scanning direction in which the pin hole 6A is detected and the scanning direction in which the step 8 is detected are also obtained in S202c. Accordingly, a triangle having the vertexes of the sensor, the reflection point of the pin hole 6A, and the reflection point of the step 8 is uniquely determined. When the vertex corresponding to the reflection point of the triangular pin hole 6A is moved so as to be in contact with the pin hole and the vertex corresponding to the step 8 is in contact with the step, the curve 2 drawn by the remaining vertex and the curve 1 in FIG. 10C There is a sensor at the intersection. In this case, the sensor position is determined pinpointly.

The actual calculation is analyzed by the CPU 21 using a sensor position analysis program that analyzes the sensor position based on the evaluation steps of FIGS. 10A to 10D stored in at least one storage device of the HDD 22 and the RAM 23. The analysis result is stored in at least one storage device of the HDD 22 and the RAM 23.
(3) Ultrasonic flaw detection step S203
In step S203, the rotational scanning condition of the sector scanning plane is determined based on the UT sensor position obtained in step S202, and ultrasonic flaw detection is performed.

  In S203a, based on the UT sensor position measured in Step S202, the CPU 21 determines the rotation angle range of the sector scanning plane with the pin hole direction as the starting point of the rotational scanning of the sector scanning plane and the step as the ending point. The algorithm for determining the rotation angle pitch of the sector scanning plane is the same as in S102a. Thus, the rotational scanning condition of the sector scanning plane obtained by the CPU 21 is stored in at least one storage device of the HDD 22 and RAM 23.

  In S203b, the delay time is analyzed based on the rotational scanning condition of the sector scanning surface determined in S203a. The analysis method of the delay time is the same as S102b. Alternatively, the delay time calculated according to the ultrasonic propagation distance, the refraction angle, and the rotation angle of the sector scanning surface in advance may be stored in the HDD 22 or the RAM 23 as a database, and the delay time may be determined based on the database. The prior analysis of the delay time based on this database may be applied to the first embodiment.

In S203c, ultrasonic flaw detection is performed based on the delay time analyzed in S203b. The ultrasonic flaw detection method is the same as S102c.
(4) Flaw detection result confirmation step S204
Finally, in step S204, the validity of the ultrasonic flaw detection range is confirmed. First, in S204a, a calculation process is performed, and the flaw detection result is displayed on the monitor 28. The display method is the same as in S103a. From the displayed flaw detection image, the operator confirms the presence / absence of a signal of the pin hole 6 that is the starting point of the rotational scanning of the sector scanning surface and a signal of the step 8 that is the end point of the rotational scanning.

  After confirming that the signals of the pin hole 6 and the step 8 are detected in S204a, in S204b, an ultrasonic flaw detection end signal is input from the keyboard 26 and transmitted to the CPU 21 via the I / O port 25a of the personal computer 9. End the flaw detection.

  Further, the flaw detection may be performed with the step detection direction as the start point of the sector surface rotational scanning and the pin hole detection direction as the end point of the sector surface rotational scanning, with the sector surface rotational scanning direction reversed. This reverse rotation of the sector surface in the rotational scanning direction may be used in the first embodiment.

  Since the second embodiment is configured as described above, it is possible to automatically detect the entire stress range of the turbine blade fork by rotational scanning of the electronic sector scanning surface. Further, since the rotational scanning start point and end point of the sector scanning surface can be determined without moving the UT sensor, the rotational scanning start point is determined by mechanical movement of the sensor position as compared with the first embodiment. Furthermore, the inspection is speeded up.

  The ultrasonic flaw detection method in the present invention can improve the reliability of ultrasonic flaw detection of industrial equipment having the same configuration as a turbine blade fork, and can shorten the flaw detection time.

1: UT sensor 2: rotor blade 3: disk 4: rotating shaft 5: fork 6: pin hole 7: pin 9: personal computer
10: Ultrasonic flaw detector 21: CPU
22: HDD
23: RAM
24: ROM
25a, 25b: I / O port 26: keyboard 27: recording medium 28: monitor 31: ultrasonic element 100: stress portion 101: sensor installation surface 102: point 103 on the sensor installation surface end: upper end 104 of the pin hole 6: A point on the pin hole rotated 90 ° from the upper end 103 of the pin hole 6 about the axis of the pin hole S101: Pin hole echo detection step S101a: UT sensor installation step S101b: Measurement start signal input step S101c: Pin hole echo detection confirmation Step S101d: Flaw detection start point determination step S102: Ultrasonic flaw detection step S102a: Rotational angle pitch determination step S102b: Delay time determination step S102c: Ultrasonic flaw detection step S103: Step echo detection step S103a: Ultrasonic flaw detection result processing Display step S103b: step echo Output confirmation step S201: Fork shape data input step S202: Sensor position measurement step S202a: Measurement start signal input step S202b: Sector scanning angle pitch determination step S202c: Ultrasonic transmission / reception step S202d: Sensor position analysis step S203: Ultrasonic flaw detection step S203a : Sector scanning plane rotation angle pitch determination step S203b: Delay time determination step S203c: Ultrasonic flaw detection step S204: Flaw detection range confirmation step S204a: Ultrasonic flaw detection result processing / display step S204b: Flaw detection range validity confirmation step

Claims (13)

An ultrasonic sector scan surface that scans the refraction angle in an arc shape by an ultrasonic sensor, ultrasonic flaw detector, and controller is rotated against a turbine blade fork that has a pin hole and a step for pin joining to the turbine body. In a three-dimensional ultrasonic flaw detection method for a turbine blade fork that scans and flaws,
A pin hole detecting step for detecting the pin hole of the fork, an ultrasonic flaw detection step for executing a three-dimensional ultrasonic flaw detection of the fork, and a step detecting step for detecting a step of the fork,
The pin hole detection step includes a pin hole echo detection confirmation step for detecting the pin hole echo of the fork,
The ultrasonic flaw detection step includes a rotational scanning angle pitch determining step for determining a rotational scanning angle pitch of the sector scanning surface to be less than 2.7 ° with respect to the fork,
The step detecting step includes a step echo detection confirming step for detecting a step echo of the fork, and a three-dimensional ultrasonic flaw detection method for a turbine rotor blade fork.   2. The method for detecting a three-dimensional ultrasonic flaw of a turbine blade fork according to claim 1, wherein the rotation angle of the sector scanning surface in which the pin hole echo is detected in the pin hole echo detection confirmation step is determined by the rotation scanning of the sector scanning surface. A three-dimensional ultrasonic flaw detection method for a turbine rotor blade fork characterized in that the point or end point is set.   2. The three-dimensional ultrasonic flaw detection method for a turbine rotor fork according to claim 1, wherein in the step echo detection confirmation step, the rotation angle of the sector scanning surface where the step echo is detected is set as the end point of the rotational scanning of the sector scanning surface or A three-dimensional ultrasonic flaw detection method for a turbine blade fork characterized by being a starting point.   2. The method of three-dimensional ultrasonic flaw detection for a turbine rotor fork according to claim 1, wherein the rotation angle of the sector scanning surface in which the pin hole is detected in the pin hole echo detection confirmation step is set as a rotation scanning start point of the sector scanning surface or The rotation angle of the sector scanning surface that has detected the step in the step echo detection confirmation step is set as the end point or the starting point of the rotational scanning of the sector scanning surface. Sonic flaw detection method. In the three-dimensional ultrasonic flaw detection method of the turbine rotor blade fork according to claim 1,
The pin hole detection step includes a UT sensor installation step, a measurement start signal input step, a pin hole echo detection confirmation step, and a flaw detection start point determination step,
The ultrasonic flaw detection step includes a rotation angle pitch determination step of a sector scanning plane, a delay time determination step, and an ultrasonic flaw detection step,
The step detection step includes an ultrasonic flaw detection result processing / display step and a step echo detection confirmation step. An ultrasonic sector scan surface that scans the refraction angle in an arc shape by an ultrasonic sensor, ultrasonic flaw detector, and controller is rotated against a turbine blade fork that has a pin hole and a step for pin joining to the turbine body. In a three-dimensional ultrasonic flaw detection method for a turbine blade fork that scans and flaws,
A step of inputting the fork shape into the control device; a sensor position measuring step for determining the position of the ultrasonic sensor on the fork; and an ultrasonic flaw detection step for three-dimensional flaw detection of the fork.
The sensor position measuring step further includes
A rotational scanning angle pitch determining step for rotationally scanning the sector scanning surface at an angular pitch equal to or smaller than an angle φ described by the following equation on the fork;
φ = cos ⁻¹ [(a ² + b ² −2r ² ) ÷ (2 · a · b)]
a = √ [(Δy−r) ² + Δx ² ]
b = √ [Δy ² + (Δx−r) ² ]
Δx: Fork width [m]
Δy: Distance between upper end of fork and pin hole center [m]
r: Pin hole radius [m]
An ultrasonic transmission / reception step of rotationally scanning the sector scanning surface at an angular pitch φ;
A three-dimensional ultrasonic flaw detection method for a turbine rotor blade fork, comprising a sensor position analyzing step for determining the ultrasonic sensor position. The three-dimensional ultrasonic inspection method for a turbine rotor fork according to claim 6, wherein the ultrasonic inspection step for three-dimensionally detecting the fork includes:
Determining a rotation angle range of the sector scanning surface, and determining a rotation angle pitch of the sector scanning surface to determine a rotation angle pitch of the sector scanning surface within a range of less than 2.7 °;
An ultrasonic delay time determining step and an ultrasonic flaw detection step for executing a three-dimensional ultrasonic flaw detection on the fork.   8. The three-dimensional ultrasonic flaw detection method for a turbine rotor fork according to claim 6 or 7, wherein the sensor position measuring step measures a distance between two of the pin holes of the fork and the ultrasonic sensor. Then, a three-dimensional ultrasonic flaw detection method for a turbine rotor blade fork, wherein an area where the ultrasonic sensor can exist is determined.   The three-dimensional ultrasonic flaw detection method for a turbine rotor fork according to claim 8, wherein the sensor position measuring step measures a distance between the pin hole of the fork and the step of the fork and the ultrasonic sensor. A three-dimensional ultrasonic flaw detection method for a turbine rotor fork, wherein a first curve in which the ultrasonic sensor may exist in the area is determined.   The three-dimensional ultrasonic flaw detection method for a turbine rotor fork according to claim 9, wherein the sensor position measuring step measures a distance between the pin hole of the fork and a step different from the step and the ultrasonic sensor. And determining a second curve in which the ultrasonic sensor exists, and an intersection of the first curve and the second curve of claim 9 as the ultrasonic sensor position. 3D ultrasonic flaw detection method.   11. The three-dimensional ultrasonic flaw detection method for a turbine rotor fork according to claim 6, wherein the rotation angle of the sector scanning surface where the pin hole is detected, measured in the sensor position measuring step, is sector scanned. A three-dimensional ultrasonic flaw detection method for a turbine blade fork, characterized in that the start point or end point of rotational scanning of a surface is used.   11. The three-dimensional ultrasonic flaw detection method for a turbine rotor fork according to claim 6, wherein a scanning direction of the sector scanning surface, which is measured in the sensor position measuring step and in which the step is detected, is set to the sector scanning surface. A three-dimensional ultrasonic flaw detection method for a turbine rotor blade fork, characterized in that the end point or start point of the rotational scanning of the turbine blade is set.   11. The three-dimensional ultrasonic flaw detection method for a turbine rotor fork according to claim 6, wherein the rotation of the sector scanning plane in which the pin hole measured in the step of evaluating the installation position of the ultrasonic sensor is detected. A turbine blade fork characterized in that an angle is a starting point or an ending point of rotational scanning of a sector scanning surface, and a scanning direction of the sector scanning surface where a step is detected is an ending point or starting point of rotational scanning of the sector scanning surface. 3D ultrasonic flaw detection method.

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