JP2011208978A - Ultrasonic inspection method and device for turbine blade fitting section - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic inspection method and a device for a turbine blade fitting section capable of improving defect detectability furthermore than the case where a search probe of a single element is used, and also performing defect sizing.SOLUTION: The device includes: an ultrasonic flaw detector having a phased array search probe 15 for transmitting/receiving an ultrasonic wave and performing electronic scanning with an ultrasonic beam, a control signal processing part 20 and a transmission/reception part 40; a scanner 11 for holding the phased array search probe, and scanning it in the circumferential direction; and a display part 34 for displaying an inspection result by the ultrasonic flaw detector. An ultrasonic wave of a beam pattern for focusing loosely the ultrasonic wave so that a focusing diameter of the ultrasonic beam becomes larger than a radius of curvature of a hook shoulder part of the blade fitting section is transmitted/received by using the phased array search probe 15.

Description

  TECHNICAL FIELD The present invention relates to an ultrasonic inspection method and apparatus for a turbine blade implantation portion that inspects the soundness of a turbine rotor blade implantation portion for power generation using ultrasonic waves.

  In order to confirm the soundness of the blade implantation part of the turbine rotor for power generation, the rotor blade is extracted from the turbine wheel, and the blade implantation part can be visually observed. The penetrant flaw detection method (PT method) and the magnetic component flaw detection method (MT method) Inspecting methods have been applied. However, since it takes time to extract the blade, there has been proposed a method for confirming the soundness of the rotor blade implantation portion by an ultrasonic flaw detection method (UT method) that does not require extraction of the blade (for example, Patent Document 1). , See Patent Document 2).

Japanese Examined Patent Publication No. 7-78491 JP 2009-244079 A

  Patent Document 1 performs defect detection or sizing by paying attention not only to a defect echo but also to a shape echo reduction due to shielding. However, it does not mention the focusing of the ultrasonic beam. At the time of filing of Patent Document 1, the UT method using a phased array probe is not yet common, and a single-element probe that transmits an ultrasonic beam with a certain divergence angle is assumed. I guess that.

  Patent Document 2 focuses on both defect echo intensity and shape echo intensity in ultrasonic inspection of a wing implant using a phased array probe. The main purpose of using the phased array probe is presumed to be to change the refraction angle of the ultrasonic beam by electronic scanning. The beam focusing property is not explicitly stated in the text, but the drawing shows that the beam is focused at the origin of the defect. It is assumed that priority is given to the viewpoint of improving the detection sensitivity of defect echoes.

  Here, when a point-focused beam is applied to ultrasonic inspection of the blade implant portion of the turbine rotor, the defect detectability is improved, but there is a problem that it is not suitable for sizing.

  It is an object of the present invention to provide an ultrasonic inspection method and apparatus for a turbine rotor blade implantation part that is capable of defect sizing while improving defect detection performance compared to when a single element probe is used. It is in.

(1) In order to achieve the above object, according to the present invention, ultrasonic waves are transmitted and received in a direction perpendicular to the axial direction and an oblique angle in the radial direction from the side surface of the turbine wheel toward the blade implantation portion. , An ultrasonic inspection method for detecting a circumferential defect starting from the hook corner portion of the wing implantation portion, using a phased array probe, than the radius of curvature of the hook shoulder portion of the wing implantation portion, The ultrasonic wave of the beam pattern that gently focuses the ultrasonic wave is transmitted and received so that the focused diameter of the ultrasonic beam becomes large.
By this method, defect sizing is also possible while improving defect detectability compared to when a single element probe is used.

  (2) In the above (1), preferably, from the propagation time of the ultrasonic reception waveform, a defect echo generated when there is a defect starting from the hook corner portion and a crack defect at the hook corner portion In addition, the shape echo of the hook shoulder portion where the ultrasonic wave is shielded by a defect and the echo intensity is reduced, and the shape echo of the hook rising portion irrelevant to the presence or absence of the defect of the hook corner portion, respectively, The echo intensity is obtained independently.

  (3) In the above (2), preferably, the ratio of both is calculated by dividing by the defect echo intensity from the defect starting from the hook corner part and the shape echo intensity of the hook shoulder part, and the division result From this, the presence or absence of cracks is determined.

  (4) In the above (3), it is preferable that the defect size is obtained by comparing the division result with the relationship between the division result prepared in advance and the defect size.

  (5) In the above (1), preferably, the flaw detection sensitivity is adjusted so that the shape echo intensity of the hook rising portion becomes a constant value, and ultrasonic waves are transmitted and received.

  (6) In the above (1), preferably, when inspecting the wing implantation portion having a plurality of hooks, the diameter of the ultrasonic beam is at least in the range from the lowermost hook rising portion to the uppermost hook shoulder. The phased array probe is mechanically scanned in the circumferential direction while electronically scanning in the direction.

  (7) In the above (1), preferably, when inspecting a wing implantation portion having a plurality of hooks, an ultrasonic beam is electronically transmitted in a radial direction in a range from a rising portion to a shoulder portion for one step of the hook. The scanning of the phased array probe in the circumferential direction is repeated by the number of steps of the hook while scanning in the same manner.

  (8) In the above (7), preferably, the ultrasonic transmission / reception position is changed by the inspected hook so that the refraction angle of the ultrasonic beam to the inspected hook corner is 45 °. .

  (9) In the above (8), preferably, when a straight path with a 45 ° refraction angle of the ultrasonic beam to the inspected hook corner portion cannot be taken due to structural restrictions of the turbine rotor, a straight path The ultrasonic transmission / reception position is such that the refraction angle is close to 45 ° within the range where the light can be removed.

  (10) In the above (8), preferably, the inspection results divided and recorded by the number of times of the hook step are simultaneously displayed on the same screen.

  (11) In the above (1), preferably, the phased array probe and the phased array probe are arranged so that an ultrasonic beam pattern transmitted and received from the phased array probe is symmetric with respect to a center axis of the probe. A pair of shoes is used to transmit and receive oblique ultrasonic waves.

(12) In order to achieve the above object, the present invention provides an ultrasonic flaw detector having a phased array probe for electronically transmitting / receiving ultrasonic waves and an ultrasonic beam, a control signal processing unit, and a transmission / reception unit. Scanning means for gripping the phased array probe and scanning in the circumferential direction; means for displaying the inspection result by the ultrasonic flaw detector; and from the side surface of the turbine wheel toward the blade implantation portion, in the axial direction Transmitting and receiving ultrasonic waves in the vertical direction and the oblique direction in the radial direction, flaw detection in the circumferential direction starting from the hook corner portion of the wing implantation portion, and using the phased array probe, Ultrasound of a beam pattern that gently focuses the ultrasonic wave is transmitted and received so that the focal diameter of the ultrasonic beam becomes larger than the radius of curvature of the hook shoulder of the wing implantation part.
With such a configuration, defect sizing can be performed while improving defect detectability compared to when a single-element probe is used.

  (13) In the above (12), preferably, in order to compare the curvature radius of the hook shoulder and the focused diameter of the ultrasonic beam, the frequency of the ultrasonic wave, the number of elements of the phased array probe, the element pitch, and the focal point Calculation means for calculating the ultrasonic beam diameter by sound field calculation from the distance value and display means for displaying the beam diameter calculated by the calculation means are provided.

  (14) In the above (12), preferably, an echo from the hook rising portion, an echo from the hook corner portion, and three or more time gates for independently extracting the echo from the hook shoulder portion; , Intensity calculating means for obtaining the echo intensity in each gate is provided.

  (15) In the above (12), preferably, the ratio calculation means for dividing the echo intensity of the hook corner part and the echo intensity of the hook shoulder part to obtain the ratio between them, and the division result prepared in advance The storage means for storing the relationship between the defect size, the division result stored in the storage means, the relationship between the defect size, and the division result calculated by the ratio calculation means to obtain the defect size And a calculation display means for displaying.

  (16) In the above (12), preferably, the measurement recording means for accurately measuring and recording the scanning position in the circumferential direction of the phased array probe, and the inspection result divided and recorded by the number of times of the hook stage And a display means for displaying the result of superposition by the superposition means.

  (17) In the above (12), preferably, means capable of exchanging the shoe in accordance with the shape of the turbine wheel to be inspected is provided with means capable of combining the phased array probe and the shoe. .

According to the present invention, in ultrasonic inspection of a blade rotor embedded portion, defect sizing can be performed while improving defect detectability compared to when a single element probe is used.

It is a perspective view which shows the schematic shape of the turbine rotor which is a test object of the ultrasonic inspection apparatus by the 1st Embodiment of this invention. It is a block diagram of the scanner used with the ultrasonic inspection apparatus by the 1st Embodiment of this invention. It is sectional drawing which shows the shape of the blade | wing implantation part which consists of a three-stage hook of the turbine rotor which is a test object of the ultrasonic inspection apparatus by the 1st Embodiment of this invention. It is explanatory drawing of the relationship between the focusing property of an ultrasonic beam and echo intensity in the ultrasonic inspection apparatus by the 1st Embodiment of this invention. It is explanatory drawing of the intensity non-uniformity in the beam at the time of using the case where a shoe is not used in an ultrasonic inspection apparatus. 1 is a block diagram showing a configuration of an ultrasonic inspection apparatus according to a first embodiment of the present invention. It is a flowchart which shows the determination and operation procedure at the time of test | inspecting 1 step | paragraph of the hook of a wing implantation part using the ultrasonic inspection apparatus by the 1st Embodiment of this invention. It is explanatory drawing of the example of the screen display referred when determining the incident position of the ultrasonic beam at the time of test | inspecting a two-stage hook with the ultrasonic inspection apparatus by the 1st Embodiment of this invention. It is explanatory drawing of the example of the screen display referred when determining the incident position of the ultrasonic beam at the time of test | inspecting a two-stage hook with the ultrasonic inspection apparatus by the 1st Embodiment of this invention. It is explanatory drawing of the example of a flaw detection result in case there is no defect in a wing implantation part by the ultrasonic inspection apparatus by the 1st Embodiment of this invention. It is explanatory drawing of the example of a flaw detection result in case the wing implantation part has a defect by the ultrasonic inspection apparatus by the 1st Embodiment of this invention. It is explanatory drawing of the example of the change of the echo intensity | strength and echo intensity ratio during the mechanical scanning to the circumferential direction by the ultrasonic inspection apparatus by the 1st Embodiment of this invention. It is explanatory drawing of the flaw detection condition setting method when the linear path | route which makes the refraction angle of an ultrasonic beam 45 degrees cannot be taken, when test | inspecting 1 step | paragraph hook with the ultrasonic inspection apparatus by the 1st Embodiment of this invention. . It is explanatory drawing of the flaw detection condition setting method when the linear path | route which makes the refraction angle of an ultrasonic beam 45 degrees cannot be taken, when test | inspecting 1 step | paragraph hook with the ultrasonic inspection apparatus by the 1st Embodiment of this invention. . It is explanatory drawing of the example of the example of a screen which displayed simultaneously the B-scope image of the test result of a certain circumferential direction angle (theta) among the results of the test | inspection by three times by the ultrasonic inspection apparatus by the 1st Embodiment of this invention. is there. It is explanatory drawing of the example of the test | inspection method by the ultrasonic inspection apparatus by the 2nd Embodiment of this invention. It is explanatory drawing of the example of the inspection method by the ultrasonic inspection apparatus by the 3rd Embodiment of this invention. It is explanatory drawing of the example of the inspection method by the ultrasonic inspection apparatus by the 4th Embodiment of this invention.

Hereinafter, the configuration and operation of the ultrasonic inspection apparatus according to the first embodiment of the present invention will be described with reference to FIGS.
First, the schematic shape of the turbine rotor that is the inspection target of the ultrasonic inspection apparatus according to the present embodiment will be described with reference to FIG.
FIG. 1 is a perspective view showing a schematic shape of a turbine rotor which is an inspection target of the ultrasonic inspection apparatus according to the first embodiment of the present invention.

  The turbine rotor 1 has a structure in which a rotor shaft 2 and a rotor wheel 3 are combined. A moving blade 4 is implanted in a blade implantation portion 5 on the outer periphery of the rotor wheel 3. In the present embodiment, ultrasonic inspection is applied to inspect the soundness of the blade implantation part 5 on the rotor wheel 3 side without removing the rotor blade 4.

Next, the configuration of the scanner used in the ultrasonic inspection apparatus according to the present embodiment will be described with reference to FIG.
FIG. 2 is a configuration diagram of a scanner used in the ultrasonic inspection apparatus according to the first embodiment of the present invention. 2A is a view as seen from the axial direction of the rotor shaft, and FIG. 2B is a view as seen from a cross-sectional direction along the axis of the rotor shaft.

  The scanner 11 holds and scans the ultrasonic probe 15 according to the shape of the turbine rotor 3. The scanner 11 includes a magnetic wheel 12 for traveling while attracting to the cylindrical surface of the rotor shaft 2 and a magnetic wheel 13 for attracting the rotor wheel 3 to follow the wheel side surface. The phased array probe 15 attached to the scanner 11 transmits ultrasonic waves from one side of the wheel 3 at an oblique angle, and inspects the wing implantation part 5 on the facing side. The pedestal to which the phased array probe 15 is attached can change the setting of the radial position (height from the shaft surface) with the ball screw 14. Once the radial position is set, the same position (height from the shaft surface) can be maintained even if the scanner 11 travels in the circumferential direction. Further, the scanner 11 includes an encoder 17 for measuring a traveling distance on the shaft surface and calculating a circumferential angle θ that is ultrasonically inspected.

Next, with reference to FIG. 3, the shape of the blade implantation portion formed of the three-stage hook of the turbine rotor that is the inspection target of the ultrasonic inspection apparatus according to the present embodiment will be described.
FIG. 3 is a cross-sectional view showing the shape of a blade implantation portion including a three-stage hook of a turbine rotor that is an inspection target of the ultrasonic inspection apparatus according to the first embodiment of the present invention.

  The wing implantation part 5 is provided with a three-stage hook including a one-stage hook, a two-stage hook, and a three-stage hook. Each part when the hook is further divided may be referred to by various names. Here, they are referred to as a rising part 51, a corner part 52, and a shoulder part 53, respectively.

  When the phased array probe 15 and the shoe 19 are combined to transmit an ultrasonic wave toward the two-stage hook on the opposite side, a shape echo from the hook rising portion 51 indicated by a one-dot chain line 55 and a hook shoulder portion 53 indicated by a dotted line 57 are displayed. Shape echoes from can be received. Further, when there is a defect 54 in the hook corner portion 52, a defect echo indicated by a solid line 56 can also be received.

  Here, the case of inspecting the two-stage hook embedded with the wing with ultrasonic waves will be described. First, when the wing implantation portion is healthy and the defect 54 does not exist, the shape echo of the hook rising portion of the route indicated by the alternate long and short dash line 55 and the shape echo of the hook shoulder portion of the route indicated by the dotted line 57 can be received. On the other hand, when the defect 54 exists in the hook corner portion, the defect echo of the path as indicated by the solid line 56 is received, and at the same time, a part of the propagation path indicated by the dotted line 57 is shielded by the defect 54. The shape echo intensity of the hook shoulder is reduced.

Next, the relationship between the convergence of the ultrasonic beam and the echo intensity in the ultrasonic inspection apparatus according to the present embodiment will be described with reference to FIG.
FIG. 4 is an explanatory diagram of the relationship between the focusability of the ultrasonic beam and the echo intensity in the ultrasonic inspection apparatus according to the first embodiment of the present invention.

  In FIG. 4, the left half of the figure is an explanatory diagram when a beam 102 that is point-focused on the bottom surface of the test body 101 is used as a comparative example, and the right half is the bottom surface of the test body 101 according to the present embodiment. It is explanatory drawing at the time of using the beam 103 which converges loosely.

  Considering the beam 102 that is focused on the bottom surface of the test body 101, even if the size of the defect is different, almost the entire beam is reflected by the defect, so even if the defect size is as small as the defect 105a, Even if it is as large as the defect 105d, it is possible to receive echoes 106a, 106b, 106c, 106d having almost the same size regardless of the size of the defects 105a, 105b, 105c, 105d. That is, when the point focused beam is applied to the ultrasonic inspection of the turbine rotor blade implantation part, the defect detectability is improved. However, the sizes of the echoes 106a, 106b, 106c, and 106d are the same regardless of the size of the result, and are not suitable for sizing.

  On the other hand, as in the present embodiment, a case will be described in which a beam 103 that is gently focused on the bottom surface of the test body 101 is used. Although it is loose, since the ultrasonic beam is focused, the detectability of defects is improved. In addition, since the portions (104a, 104b, 104c, 104d) corresponding to the size of the defect of the beam are reflected, when the defect size is smaller than the beam, the intensity of the echo (107a, 107b, 107c) is the size of the defect. Corresponding to (However, if the size of the defect is larger than the beam diameter (105c, 105d), the echo intensity is saturated.) That is, in the case of a loosely focused beam, the detectability of the defect is improved as compared with the single element sensor. Is also possible.

  When considering the shape of the wing implantation part as shown in FIG. 3, the occurrence position of the defect 54 is the hook corner part 52, and the reflection position of the shape echo shielded by the defect is the part with the curvature of the hook shoulder part 53. It becomes. As indicated by the solid line 56 and the dotted line 57, the path to the hook shoulder 53 is longer than the path to the hook corner 52, so that the beam diameter at the hook corner 52 does not become smaller than the hook shoulder 53. . In addition, the shape echo from the hook shoulder 53 is obtained at a portion with a shoulder curvature. If the beam diameter at the hook shoulder 53 is larger than the curvature R of the shoulder, the reflected echo intensity will not be saturated. At the same time, since the beam diameter at the hook corner portion where the defect occurs is sufficiently large, defect sizing can be performed while improving the defect detectability as compared with the case of using a single element probe.

  It should be noted that if the convergence of the ultrasonic beam is made worse than that of a single-element probe, the detectability of defects becomes worse. In this embodiment, to gently focus an ultrasonic beam means a range in which the beam diameter at the hook corner is larger than the curvature R of the shoulder and the beam is focused rather than a single element. Further, when importance is attached to defect detectability, the same beam diameter as the curvature R of the shoulder is optimum. When emphasizing sizing, the same beam diameter as the sizing upper limit value is optimal. When emphasizing shortening of inspection time, three echoes of the hook rising part, hook corner part, and hook shoulder part are provided without electronic scanning. The beam diameter that can be received is optimal.

  Further, in the schematic diagram of FIG. 4, as a premise for considering the relationship between the convergence of the ultrasonic beam and the echo intensity, there is no significant intensity nonuniformity in the ultrasonic beam.

Here, the intensity non-uniformity in the beam when the shoe is not used and when the shoe is used in the ultrasonic inspection apparatus will be described with reference to FIG.
FIG. 5 is an explanatory diagram of intensity non-uniformity in the beam when a shoe is not used and when it is used in an ultrasonic inspection apparatus.

  FIG. 5A shows a case where a shoe is not used in the ultrasonic inspection apparatus, and FIG. 5B shows a case where a shoe is used.

  As shown in FIG. 5A, when the phased array probe 15 is brought into direct contact with the test body 101, the oblique beam 112 has a greater intensity non-uniformity in the beam than the vertical beam 111. .

  On the other hand, as shown in FIG. 5B, when the probe 15 and the shoe 19 are combined, an oblique beam with small intensity non-uniformity in the beam can be incident.

  Therefore, in the present embodiment, the phased array probe is not brought into direct contact with the rotor wheel side surface, but an ultrasonic wave is incident obliquely from the wheel side surface in a state where the probe and the shoe are combined.

Next, the configuration and operation of the ultrasonic inspection apparatus according to the present embodiment will be described with reference to FIGS.
FIG. 6 is a block diagram showing the configuration of the ultrasonic inspection apparatus according to the first embodiment of the present invention. FIG. 7 is a flowchart showing a determination / operation procedure when inspecting one hook of the wing implantation portion using the ultrasonic inspection apparatus according to the first embodiment of the present invention.

  In this embodiment, when inspecting the wing implantation portion of the three-stage hook, the one hook is inspected. As a result, there is a feature that even an apparatus that requires time for recording and signal processing of an ultrasonic waveform can be inspected.

  The ultrasonic inspection apparatus according to the present embodiment includes a control signal processing unit 20 configured by a personal computer or the like, a transmission / reception unit 40 that configures an electronic circuit with a board or the like on which electronic components are mounted, and the scanner 11 described in FIG. I have.

  The operator sets the flaw detection conditions using the setting means 21 including a keyboard and a mouse and stores them in the setting condition storage unit 22. In the flaw detection condition setting operation, first, the sound speed of the rotor material and the curvature R of the hook corner are input (procedure F11 in FIG. 7). Next, probe conditions such as the ultrasonic frequency, the number of elements of the phased array probe, and the element pitch are input (procedure F12 in FIG. 7). Further, the shoe conditions such as the sound speed and angle of the shoe material are input (procedure F13 in FIG. 7). These input data are automatically transmitted from the setting condition storage unit 22 to the delay pattern creation storage unit 23 and used for calculation by the simulator 24. From here, the operator determines the incident position of the ultrasonic beam while viewing the display screen of the simulator 24 (step F14 in FIG. 7).

Here, with reference to FIGS. 8 and 9, an example of a screen display to be referred to when determining the incident position of the ultrasonic beam when the two-stage hook is inspected by the ultrasonic inspection apparatus according to the present embodiment will be described.
FIG. 8 and FIG. 9 are explanatory diagrams of examples of screen display to be referred to when determining the incident position of the ultrasonic beam when inspecting the two-stage hook by the ultrasonic inspection apparatus according to the first embodiment of the present invention. is there.

  In the display screen shown in FIG. 8, when the operator clicks the hook corner portion with a mouse as a defect occurrence candidate for the two-stage hook, the marker 61 is displayed on the screen, and at the same time, the refraction at which the defect detection sensitivity is the best. A propagation path with an angle of 45 ° is also displayed as a dotted line 62. The operator confirms that there is no obstacle in the route indicated by the dotted line 62 (step F15 in FIG. 7), and clicks the intersection of the dotted line 62 and the wheel side surface.

  As a result, the display screen changes as shown in FIG. 9, and the marker 63 indicating the incident position of the ultrasonic wave is displayed. At the same time, the propagation path 65 to the hook rising part, the propagation path 66 to the corner part, and the shoulder part are displayed. The propagation path 67 is also displayed on the screen. When the operator first clicks the intersection of the propagation path 67 and the hook shoulder with a mouse (step F16 in FIG. 7) in order to examine the case where the geometric focus position is the shoulder, the geometric focus marker 64a is displayed. Is done. The simulator 24 calculates the sound field and displays the calculation result of the beam diameter at the shoulder at the display location 76. The operator compares the beam diameter 76 at the shoulder with the value 75 of the curvature R of the shoulder (step F17 in FIG. 7), and when the beam diameter is larger, the setting of the flaw detection conditions is completed (FIG. 7). Procedure F18). When the beam diameter 76 is smaller, the position of the geometric focus is changed to the position 64b or the position 64c, and the search is performed until the beam diameter 76 at the shoulder becomes larger than the curvature R at the shoulder. Further, since the radial position 71 of the ultrasonic beam incidence, the path 72 to the shoulder, the refraction angle 74 to the shoulder, and the geometric focal distance 74 are also displayed on the screen, the operator can set these values. The flaw detection conditions can be searched while checking.

  When the setting of the flaw detection conditions is completed, the ball screw 14 of the scanner 11 is operated to adjust the height of the phased array probe 15 so that the radial position of the ultrasonic beam incidence is the same as the setting conditions.

  The delay pattern control unit 25 of FIG. 6 controls the transmission circuit 41 with the delay pattern of the created / recorded setting condition. The signal transmitted from the transmission circuit 41 is amplified by the amplifier 42 and drives the fade array probe 15 via the connector 43 and the flaw detection cable 16. The ultrasonic beam is electronically scanned in the radial direction, the reflected wave from the wing implantation part 5 is received by the fade array probe 15, and amplified by the amplifier 44 via the flaw detection cable 16 and the connector 43. The amplified signal is stored with a time difference in the delay memory 45, the received waveform is synthesized by the adder circuit 26, and stored in the flaw detection result storage unit 28 (procedure F21 in FIG. 7 and procedure F22 in FIG. 7).

Here, an example of a flaw detection result in the case where there is no defect in the blade implantation portion by the ultrasonic inspection apparatus according to the present embodiment will be described with reference to FIG.
FIG. 10 is an explanatory diagram of an example of a flaw detection result when there is no defect in the blade implantation portion by the ultrasonic inspection apparatus according to the first embodiment of the present invention.

  As shown in FIG. 10A, an ultrasonic beam loosely focused from the probe 15 and the shoe 19 is transmitted, and the beam is sector-scanned so that the two-stage hook can be inspected. When the beam is at the position 82, the received waveform shows a characteristic like a screen example 83a shown in FIG. In the screen example 83a, there are a time gate 34 corresponding to the shape echo at the hook rising portion, a time gate 35 corresponding to the defect echo at the hook corner portion, and a time gate 36 corresponding to the shape echo from the hook shoulder portion. It is displayed. These gates 36 are calculated by the gate generation circuit 31 based on the path length evaluation result of the simulator 24. When the beam is at the position 82 in FIG. 10A, the intensity of the shape echo 39a from the shoulder portion is large, and the shape echo 37a from the rising portion is small. Since there is no defect in the corner, the corner echo 38a is small.

  The received waveform when the beam shown in FIG. 10 (A) is at position 81 is large in the shape echo 37b from the rising part and the echo 38b from the corner part as shown in the screen example 83b shown in FIG. 10 (C). The echo 39b from the shoulder is small.

  When the result of sector scanning of the ultrasonic beam is combined so as to display the maximum value of the echo intensity in each path, the shape echo 37c at the rising portion and the shoulder portion are echoed as in the screen example 83c shown in FIG. The shape echo 39c is large and the defect echo 38c at the corner is small. Further, when the result of the sector scan is displayed on the B scope, an indication 87a at the hook rising portion and an indication at the hook shoulder in the inspection range 86 of interest as shown in a screen example 83d in FIG. 10 (E). 89a is displayed.

Next, an example of a flaw detection result in the case where there is a defect in the blade implantation part by the ultrasonic inspection apparatus according to the present embodiment will be described with reference to FIG.
FIG. 11 is an explanatory diagram of an example of a flaw detection result in the case where there is a defect in the blade implantation portion by the ultrasonic inspection apparatus according to the first embodiment of the present invention.

  As shown in FIG. 11A, when the beam is at the position 82, the received waveform shows a characteristic like a screen example 83d shown in FIG. Since there is a defect 54 at the corner, the intensity of the echo 38d at the corner increases, and the shape echo 39d from the shoulder is affected by the shielding of the defect 54, so that the intensity decreases. The shape echo 37a from the rising portion remains small.

  As shown in FIG. 11A, the received waveform when the beam is at the position 81 has a large shape echo 37e from the rising portion as shown in the screen example 83e shown in FIG. The feature that the echo 38e from the head and the echo 39b from the shoulder are small is the same regardless of the presence or absence of a defect.

  When the result of sector scanning of the ultrasonic beam is combined so as to display the maximum value of the echo intensity in each path, the intensity of the echo 38f at the corner increases as in the screen example 83f shown in FIG. 11D. The intensity of the shape echo 39f from the shoulder portion decreases. The intensity of the shape echo 37f from the rising portion is not affected by the presence or absence of defects. Further, when the result of the sector scan is displayed on the B scope, in addition to the indication 87d at the hook rising portion and the indication at the hook shoulder 89d as shown in the screen example 84d in FIG. The indication 88d is also displayed.

  From such a recorded waveform, the echo intensity calculation unit 32 shown in FIG. 6 generates echoes in the gates 34, 35, and 36 shown in FIG. 10B and FIG. The intensity is calculated automatically. Further, the echo intensity ratio calculation unit 33 divides the echo intensity in the gate 35 by the echo intensity in the gate 36 to calculate the intensity ratio of the defect echo at the corner and the shape echo at the shoulder. These flaw detection results are displayed on the display unit 34 and recorded in the recording unit 35 (procedure F22 in FIG. 7).

  As described above, the scanner 11 is mechanically scanned in the circumferential direction while repeating the electronic scanning of the ultrasonic beam in the radial direction (step F23 in FIG. 7). The travel distance of the scanner 11 is calculated from the encoder signal received by the signal converter 27 via the encoder cable 18, and waveform recording, signal processing, and result display are performed every time the distance corresponding to the recording pitch is scanned in the circumferential direction. (Procedures F24 and F25 in FIG. 7).

Next, an example of a change in echo intensity and echo intensity ratio during mechanical scanning in the circumferential direction by the ultrasonic inspection apparatus according to the present embodiment will be described with reference to FIG.
FIG. 12 is an explanatory diagram of an example of changes in echo intensity and echo intensity ratio during mechanical scanning in the circumferential direction by the ultrasonic inspection apparatus according to the first embodiment of the present invention.

  The screen 90 shows changes in echo intensity and echo intensity ratio during mechanical scanning in the circumferential direction. The upper part of the display example shows changes in the intensity change 91 of the shape echo from the hook rising part, the intensity change 92 of the defect echo from the hook corner part, and the intensity change 93 of the shape echo from the hook shoulder part. The shape echo of the rising portion should be constant regardless of the presence or absence of a defect, and when the echo height of the hook rising portion shape echo 91 has a large variation, a defect of the inspection apparatus must be suspected. For this reason, the upper limit 94a and the lower limit 94b of the normal range of the rising portion shape echo 91 are displayed on the display screen so that the operator can immediately notice the malfunction of the inspection apparatus. In the second half of the display screen, the strength of the corner defect echo 92 increases and the strength of the shoulder shape echo 93 decreases, so that it can be determined that a defect exists in the corner portion of the two-stage hook. If a change in the intensity ratio 95 between the corner defect echo 92 and the shoulder shape echo 93 is observed, the presence of the defect becomes easier to judge. If the threshold value 96 is determined in advance, automatic detection of defect detection is also possible. The echo intensity ratio calculation unit 33 stores the relationship between the defect size and the echo intensity ratio obtained in advance, and can also evaluate the defect size from the echo intensity ratio.

  The echo intensity ratio calculation unit 33 can adjust the flaw detection sensitivity. That is, paying attention to the intensity of the shape echo of the hook rising portion 51 of the path indicated by the alternate long and short dash line 55 in FIG. 3, control is performed so as to transmit and receive ultrasonic waves so that this becomes a constant value.

  When the scanning of the probe 15 is continued and the scanner 11 travels once on the shaft surface and returns to the flaw detection start position (step F24 in FIG. 7), the inspection of the two-stage hook on one side of the blade implantation part is completed. To do. Further, when inspecting the three-stage hook of the wing implantation part, the flowchart showing the determination / operation procedure described in FIG. 7 is repeated in the same procedure as in the case of the inspection of the two-stage hook.

Next, with reference to FIGS. 13 and 14, flaw detection conditions when a straight path with a refraction angle of the ultrasonic beam of 45 ° cannot be taken when the one-stage hook is inspected by the ultrasonic inspection apparatus according to the present embodiment. A setting method will be described.
FIGS. 13 and 14 show flaw detection conditions when a straight path with an angle of refraction of an ultrasonic beam of 45 ° cannot be taken when inspecting a one-stage hook by the ultrasonic inspection apparatus according to the first embodiment of the present invention. It is explanatory drawing of the setting method.

  A flaw detection condition setting method in the case where the branch of the procedure F15 in FIG. 7 is No, that is, when a straight path with an ultrasonic beam refraction angle of 45 ° cannot be taken when a one-step hook is inspected will be described. .

  FIG. 13 is an example of a screen display that is referred to when determining the incident position of the ultrasonic beam when inspecting the first-stage hook. When the operator clicks the hook corner portion with a mouse as a defect occurrence candidate for the first-stage hook, the marker 61 is displayed on the screen, and at the same time, the propagation path of the refraction angle of 45 ° at which the defect detection sensitivity is the best is also the dotted line 62. Is displayed. The operator looks at the screen of FIG. 13 and determines that the route indicated by the dotted line 62 has a failure of the wing implantation groove, so that a straight route cannot be taken (step F15: No in FIG. 7). Click on the part below the intersection of the sides.

  As a result, the display screen changes as shown in FIG. 14, and a marker 63 indicating the ultrasonic incident position is displayed at the clicked point, and at the same time, a propagation path 65 to the hook rising part and a propagation path 66 to the corner part. The propagation path 67 to the shoulder is also displayed on the screen, and it can be confirmed that there is no obstacle in the next path (step F15 in FIG. 7: Yes).

  Next, in order to consider a case where the geometric focus position is the shoulder, when the intersection of the propagation path 67 and the hook shoulder is clicked with the mouse (step F16 in FIG. 7), the geometric focus marker 64a is displayed. . The simulator 24 calculates the sound field and displays the calculation result of the beam diameter at the shoulder at 76. The operator compares the shoulder curvature R value 75 of the beam diameter 76 at the shoulder (step F17 in FIG. 7), and when the beam diameter is larger, the setting of the flaw detection conditions is completed (FIG. 7). Procedure F18). When 76 is smaller, the position of the geometric focal point is changed to 64b or the like, and the search is performed until the beam diameter 76 at the shoulder becomes larger than the curvature R at the shoulder. After setting the flaw detection conditions in this way (procedure F18 in FIG. 7), the same procedure as in the case of the two-stage hook inspection (procedure F21 in FIG. 7 to procedure F25 in FIG. 7) is used. Check the health of the.

  As described above, when the transmission / reception destination of the ultrasonic beam is set to each step hook and the number of hook steps for rotating the scanner 11 in the circumferential direction is set (three rotations in the case of the three step hooks), the wing implantation is performed. Inspection on one side is completed.

Next, an example of a screen example that simultaneously displays a B scope image of an inspection result at a certain circumferential angle θ among the results of inspection performed three times by the ultrasonic inspection apparatus according to the present embodiment with reference to FIG. Will be described.
FIG. 15 is an example of a screen example that simultaneously displays a B-scope image of an inspection result at a certain circumferential angle θ among the results of inspection performed by the ultrasonic inspection apparatus according to the first embodiment of the present invention in three scans. It is explanatory drawing of.

  A first-stage hook is scanned as shown in FIG. 15 (A), a two-stage hook is scanned as shown in FIG. 15 (B), and a three-stage hook is scanned as shown in FIG. 15 (C). . FIG. 15D shows a screen example 97 that simultaneously displays the B scope image of the inspection result at a certain circumferential angle θ among the results of the inspection performed three times. Since the circumferential position θ of the scanner 11 can be accurately evaluated from the signal of the encoder 17, the inspection result of the same θ can be selected and displayed on the same screen from the inspection results of each stage hook scanned separately.

  When the inspection of the wing implantation part on one side is completed, the scanner 11 is moved to the opposite side of the turbine wheel 3 and installed on the opposite side. When the ultrasonic beam transmission / reception destination is set to each step hook and the operation of rotating the scanner 11 in the circumferential direction is performed three times, the reverse groove of the blade implantation part can be inspected, and the inspection of the blade implantation groove of the turbine wheel is completed. To do.

  As described above, according to the present embodiment, defect sizing can be performed while improving the defect detectability as compared with the case of using a single element probe.

Next, the configuration and operation of an ultrasonic inspection apparatus according to the second embodiment of the present invention will be described with reference to FIG. The configuration of the ultrasonic inspection apparatus according to this embodiment is the same as that shown in FIG.
FIG. 16 is an explanatory diagram of an example of an inspection method by the ultrasonic inspection apparatus according to the second embodiment of the present invention.

  In this embodiment, when inspecting the wing implantation part of the three-stage hook, the three hooks are inspected at a stretch. When an inspection device that can record and process ultrasonic waveforms in a short time can be used, it has the feature of reducing the overall time required for inspection of the wing implant.

  FIG. 16 shows an outline of electronic scanning of an ultrasonic beam and a B-scope display example 98 of inspection results in this embodiment. When inspecting a wing implantation portion having a cross-sectional shape as shown in FIG. 16A, the propagation path of the ultrasonic beam to the shoulder portion of the first-stage hook is most easily damaged by the wing implantation groove. Therefore, referring to the screen display as shown in FIG. 13, the ultrasonic wave incident position is determined so that a straight path to the shoulder of the first-stage hook can be taken. Further, since the path to the shoulder of the first hook is the longest, the beam diameter at the shoulder of the first hook is larger than the curvature R of the shoulder while referring to the screen display as shown in FIG. Is set, the beam diameter at the shoulder portion of the 2-3 step hook is naturally larger than the curvature R of the shoulder portion.

  As shown in FIG. 16 (A), when a narrowly focused ultrasonic beam is transmitted from the probe 15 and the shoe 19 and the range from the third-stage hook rising portion to the first-stage hook shoulder is sector-scanned, 1 to 3 is obtained. The echoes of the rising part, corner part and shoulder part of the corrugated hook can be received.

  The B scope image at this time is as shown in a display example 98 in FIG. In the state where the electronic scanning of the ultrasonic beam in the radial direction is repeated in this way, the scanner 11 is mechanically scanned in the circumferential direction as in the first embodiment. When the scanner 11 travels once in the circumferential direction, the inspection on one side of the blade implantation part is completed. When the scanner 11 is moved to the opposite side of the turbine wheel 3 and the scanner 11 is caused to travel once in the circumferential direction, the inspection of the blade implantation groove of the turbine wheel is completed.

  As described above, according to the present embodiment, defect sizing can be performed while improving the defect detectability as compared with the case of using a single element probe.

  In addition, when an inspection apparatus that can record and process an ultrasonic waveform in a short time can be used, the entire time required for the wing implantation part inspection can be shortened.

Next, the configuration and operation of an ultrasonic inspection apparatus according to the third embodiment of the present invention will be described with reference to FIG. The configuration of the ultrasonic inspection apparatus according to this embodiment is the same as that shown in FIG.
FIG. 17 is an explanatory diagram of an example of the inspection method by the ultrasonic inspection apparatus according to the third embodiment of the present invention.

  In the present embodiment, the ultrasonic beam is narrowed down so gently that one step of the hook can be inspected at once, and the blade implant portion is inspected without radial electronic scanning (sector scanning). Although an ultrasonic probe having a large opening is required, it has a feature that the inspection time can be remarkably shortened as compared with the first and second embodiments.

  FIG. 17 shows an outline of ultrasonic beam transmission / reception when inspecting the two-stage hook of the wing implantation portion according to the third embodiment and a B scope display example 84g of the inspection result.

  As shown in FIG. 17 (A), the beam diameter is so large that an echo from the rising portion, corner portion, and shoulder portion of the two-stage hook can be received from the probe 15g having a large opening and the shoe 19g adapted thereto. Send and receive sound waves. The B scope image at this time is like a display example 84g shown in FIG. Since the electronic scanning (sector scanning) in the radial direction can be eliminated, the number of recorded waveforms can be reduced. In this state, similarly to the first embodiment, the scanner 11 is mechanically scanned in the circumferential direction. When the transmission / reception destination of the ultrasonic beam is set to each step hook and the operation of causing the scanner 11 to make one rotation in the circumferential direction is performed three times, the inspection on one side of the wing implantation part is completed. When the inspection of the wing implantation part on one side is completed, the scanner 11 is moved to the opposite side of the turbine wheel 3 and installed on the opposite side. When the ultrasonic beam transmission / reception destination is set to each step hook and the operation of rotating the scanner 11 in the circumferential direction is performed three times, the reverse groove of the blade implantation part can be inspected, and the inspection of the blade implantation groove of the turbine wheel is completed. To do.

  As described above, according to the present embodiment, defect sizing can be performed while improving the defect detectability as compared with the case of using a single element probe.

  In addition, the overall time for inspecting the wing implant can be further reduced.

Next, the configuration and operation of an ultrasonic inspection apparatus according to the fourth embodiment of the present invention will be described with reference to FIG. The configuration of the ultrasonic inspection apparatus according to this embodiment is the same as that shown in FIG.
FIG. 18 is an explanatory diagram of an example of an inspection method using an ultrasonic inspection apparatus according to the fourth embodiment of the present invention.

The inspection object of the first to third embodiments is a wheel without a taper as shown in FIG. 17A, but in this embodiment, a wheel with a taper as shown in FIG. Inspected. In terms of the hardware configuration of the inspection apparatus, the shoe 19 for the non-tapered wheel 3 used in the first to third embodiments can be changed to a shoe 19b for the tapered wheel 3b. Depending on the presence or absence of the taper, the beam refraction angle and the path to the inspection target hook change, but the first to third rewrite operations such as the delay pattern stored in the delay pattern creation storage unit 23 of the inspection apparatus shown in FIG. The tapered wheel can be inspected by the same method as in the above embodiment.

DESCRIPTION OF SYMBOLS 1 ... Turbine rotor 2 ... Shaft 3 ... Wheel 4 ... Moving blade 5 ... Blade implantation part 11 ... Scanner 12, 13 ... Magnetic wheel 14 ... Ball screw 15 ... Phased array probe 17 ... Encoder 19 ... Shoe 20 ... Control and signal Processing section 21 ... Setting means 22 ... Setting condition storage section 23 ... Delay pattern creation / storage section 24 ... Simulator 25 ... Delay pattern control section 26 ... Addition circuit 27 ... Signal conversion section 28 ... Flaw detection result storage section 31 ... Gate generation circuit 32 ... Echo intensity calculation unit 33 ... Echo intensity ratio calculation unit 34 ... Display unit 35 ... Storage unit 40 ... Transmission / reception unit 41 ... Transmission circuit 45 ... Delay memory 51 ... Hook riser 52 ... Hook corner 53 ... Hook shoulder

Claims (17)

From the side of the turbine wheel toward the blade implantation part, an ultrasonic wave is transmitted and received in a vertical direction in the axial direction and in an oblique direction in the radial direction, and the circumferential direction starting from the hook corner part of the blade implantation part An ultrasonic inspection method for flaw detection,
Using a phased array probe, transmitting and receiving ultrasonic waves of a beam pattern that gently focuses ultrasonic waves so that the focal diameter of the ultrasonic beam becomes larger than the radius of curvature of the hook shoulder of the wing implantation part. The ultrasonic inspection method of the turbine blade implantation part characterized. The ultrasonic inspection method according to claim 1,
From the propagation time of the ultrasonic reception waveform, the defect echo generated when there is a defect starting from the hook corner part, and the echo intensity when the hook corner part has a split defect, the ultrasonic wave is shielded by the defect. The shape echo of the hook shoulder portion where the drop is reduced and the shape echo of the hook rising portion irrelevant to the presence or absence of defects in the hook corner portion are extracted, and the respective echo intensities are obtained independently. Ultrasonic inspection method for turbine blade implantation part. The ultrasonic inspection method according to claim 2,
Dividing by the defect echo intensity from the defect starting from the hook corner portion and the shape echo intensity of the hook shoulder portion to calculate the ratio between the two, and determining the presence or absence of cracks from the division result Ultrasonic inspection method for turbine blade implantation part. The ultrasonic inspection method according to claim 3,
An ultrasonic inspection method for a turbine blade implantation portion, wherein the defect size is obtained by comparing the division result with a relationship between the division result prepared in advance and the defect size. The ultrasonic inspection method according to claim 1,
An ultrasonic inspection method for a turbine blade implantation part, wherein ultrasonic detection is performed by adjusting flaw detection sensitivity so that the shape echo intensity of the hook rising part has a constant value. The ultrasonic inspection method according to claim 1,
When inspecting wing implants with multiple hooks,
The phased array probe is mechanically scanned in the circumferential direction while electronically scanning the ultrasonic beam in the radial direction at least in the range from the lowermost hook rising portion to the uppermost hook shoulder. The ultrasonic inspection method of the turbine blade implantation part characterized. The ultrasonic inspection method according to claim 1,
When inspecting wing implants with multiple hooks,
The phased array probe is mechanically scanned in the circumferential direction while electronically scanning the ultrasonic beam in the radial direction in the range from the rising portion to the shoulder portion of one step of the hook. An ultrasonic inspection method for a turbine blade implantation part, characterized in that it is repeated by the number of stages. The ultrasonic inspection method according to claim 7,
An ultrasonic inspection method for a turbine blade implantation portion, characterized in that an ultrasonic transmission / reception position is changed by a hook to be inspected so that a refraction angle of an ultrasonic beam to a corner to be inspected becomes 45 °. The ultrasonic inspection method according to claim 8,
When a straight path with a 45 ° refraction angle of the ultrasonic beam to the inspected hook corner portion cannot be taken due to structural restrictions of the turbine rotor, the refraction angle is close to 45 ° within the range where the straight path can be taken. An ultrasonic inspection method for a turbine blade implantation part, characterized in that the ultrasonic transmission / reception position is set as described above. The ultrasonic inspection method according to claim 8,
An ultrasonic inspection method for a turbine blade implantation part, wherein the inspection results divided and recorded as many times as the number of hook steps are simultaneously displayed on the same screen. The ultrasonic inspection method according to claim 1,
The oblique angle ultrasonic wave is transmitted / received by combining the phased array probe and the shoe so that the pattern of the ultrasonic beam transmitted / received from the phased array probe is symmetrical with respect to the central axis of the probe. An ultrasonic inspection method for a turbine blade implantation part. A phased array probe for electronically transmitting / receiving ultrasonic waves and an ultrasonic beam, an ultrasonic flaw detector having a control signal processing unit and a transmission / reception unit, and scanning means for holding the phased array probe and scanning in the circumferential direction And means for displaying an inspection result by the ultrasonic flaw detector,
From the side of the turbine wheel toward the blade implantation part, an ultrasonic wave is transmitted and received in a vertical direction in the axial direction and in an oblique direction in the radial direction, and the circumferential direction starting from the hook corner part of the blade implantation part Detect flaws,
Using the phased array probe, transmitting and receiving ultrasonic waves of a beam pattern that gently focuses the ultrasonic wave so that the focal diameter of the ultrasonic beam becomes larger than the radius of curvature of the hook shoulder of the wing implantation part. Ultrasonic inspection device for turbine blade implantation part. The ultrasonic inspection apparatus according to claim 12,
In order to compare the curvature radius of the hook shoulder and the focused diameter of the ultrasonic beam, the ultrasonic beam is calculated by calculating the sound field from the values of the ultrasonic frequency, the number of elements of the phased array probe, the element pitch, and the focal length. A calculating means for calculating a diameter;
An ultrasonic inspection apparatus for a turbine blade implantation section, comprising: display means for displaying a beam diameter calculated by the calculation means. The ultrasonic inspection apparatus according to claim 12,
Echo from the hook rising part, echo from the hook corner part, three or more time gates for independently extracting the echo from the hook shoulder part, and intensity calculation for obtaining echo intensity in each gate Means for Ultrasonic Inspection for Turbine Blade Implantation Part The ultrasonic inspection apparatus according to claim 12,
Ratio calculating means for dividing the echo intensity of the hook corner part and the echo intensity of the hook shoulder part to obtain a ratio between the two,
Storage means for storing the relationship between the division result prepared in advance and the defect size;
And a calculation display means for obtaining and displaying the defect size using the relationship between the division result stored in the storage means and the defect size and the division result calculated by the ratio calculation means. Ultrasonic inspection equipment for turbine blade implantation part. The ultrasonic inspection apparatus according to claim 12,
Measurement recording means for accurately measuring and recording the circumferential scanning position of the phased array probe;
Superimposing means for superimposing inspection results divided and recorded as many times as the number of hook steps;
An ultrasonic inspection apparatus for a turbine blade implantation portion, comprising: display means for displaying a result of superposition by the superposition means. The ultrasonic inspection apparatus according to claim 12,
An ultrasonic inspection apparatus for a turbine blade implantation section, comprising means capable of combining a phased array probe and a shoe in a manner in which a shoe can be exchanged according to the shape of a turbine wheel to be inspected.

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