Disclosure of Invention
The invention aims to solve the technical problem of providing a method for inspecting a forked blade root of a nuclear power plant aiming at least one defect in the prior art.
The technical scheme adopted by the invention for solving the technical problems is as follows: method for checking a forked root for a nuclear power plant, said forked root comprising a blade body and at least one root, said root comprising a first rivet hole, characterized in that it comprises the following steps:
s1: placing a preset probe at a blade body or a tooth root platform corresponding to the first riveting hole area to be detected;
s2: in the detection process, receiving a reflected signal of the blade root, and displaying the reflected signal in the global focusing imaging of the ultrasonic detector on the first riveting hole area to be detected;
s3: and judging whether the first riveting hole has defects according to the position information of the reflection signal in the global focusing image.
Preferably, in the method for inspecting a forked blade root of a nuclear power plant according to the present invention, the step S1 includes:
s11: presetting a plurality of probes with different scanning ranges;
s12: and selecting probes in corresponding scanning ranges according to structures of a first riveting hole area on the inner arc side of the tooth to be detected and a first riveting hole area on the outer arc side of the tooth, and placing the probes at a blade body or a root platform corresponding to the first riveting hole area on the inner arc side of the tooth and the first riveting hole area on the outer arc side of the tooth.
Preferably, in the method for inspecting a forked blade root of a nuclear power plant according to the present invention, the reflection signal of the blade root includes a reflection signal of a geometrical structure inherent to the blade root; or the natural geometry reflection signals of the blade root and the reflection signals generated by other changes in the blade root.
Preferably, in the method for inspecting a forked blade root of a nuclear power plant according to the present invention, the performing global focus imaging on the first rivet hole region to be inspected by an ultrasonic detector includes:
dividing the first riveting hole area image to be detected into a plurality of grid areas at preset intervals;
focusing and imaging each grid point;
and carrying out superposition imaging on the focused images of the grid points to obtain a global focused image of all grid points of the first riveting hole area to be detected.
Preferably, in the method for inspecting a forked blade root of a nuclear power plant according to the present invention, the probe is scanned in a zigzag manner during the inspection.
Preferably, in the method for inspecting a forked blade root of a nuclear power plant according to the present invention, the displaying of the reflection signal in the global focus imaging performed by the ultrasonic detector on the first rivet hole region to be inspected includes:
and the reflected signal is displayed in the global focusing imaging of the first riveting hole area to be detected by the ultrasonic detector through the horizontal distance and the vertical distance.
Preferably, in the method for inspecting a forked blade root of a nuclear power plant according to the present invention, the step S3 includes:
and judging whether other reflection signals exist in the global focused image or not by taking the horizontal distance and the vertical distance of the inherent geometric structure reflection signal of the blade root in the global focused image as the reference, and if so, judging that the first riveting hole has defects.
Preferably, in the method for inspecting a forked blade root of a nuclear power plant according to the present invention, the method further includes:
s4: and if the blade root is judged to have defects, acquiring the signal reflection equivalent of the defects, comparing the signal reflection equivalent with the signal reflection equivalent of the preset reference defects, and judging the sizes of the defects.
Preferably, in the method for inspecting a forked blade root of a nuclear power plant according to the present invention, the preset signal reflection equivalent of the reference defect includes:
presetting a reference block, and forming at least one defect notch groove in the first riveting hole area;
placing a probe at a blade body or a root platform corresponding to the first riveting hole area to be detected;
and adjusting the gain value of the ultrasonic detector, adjusting the amplitude to a preset value of full screen, taking the gain value as the reference sensitivity of detection, and taking the reflection equivalent of the defect notch as the signal reflection equivalent of a preset reference defect.
Preferably, in the method for inspecting a forked blade root of a nuclear power plant, before each detection, the ultrasonic detector is initially calibrated, intermediately calibrated and finally calibrated; the initial calibration, the middle calibration and the end calibration are used for adjusting the gain value of the ultrasonic detector and adjusting the amplitude to a preset value of full screen.
By implementing the invention, the following beneficial effects are achieved:
according to the invention, the preset probe is arranged at the blade body or the root platform corresponding to the first riveting hole area to be detected, the reflection signal of the root of the blade is received in the detection process, the reflection signal is displayed in the global focused imaging of the ultrasonic detector on the first riveting hole area to be detected, and whether the first riveting hole has defects or not is judged according to the position information of the reflection signal in the global focused image, so that the crack defects of the first riveting hole can be effectively found, the defects in the detection process are easier to identify, and the detection sensitivity and the detection efficiency are higher.
Detailed Description
For a more clear understanding of the technical features, objects and effects of the present invention, embodiments of the present invention will now be described in detail with reference to the accompanying drawings.
It should be noted that the flow charts shown in the drawings are only exemplary and do not necessarily include all the contents and operations/steps, nor do they necessarily have to be executed in the order described. For example, some operations/steps may be decomposed, and some operations/steps may be combined or partially combined, so that the actual execution sequence may be changed according to the actual situation.
The invention discloses a method for inspecting a forked blade root of a nuclear power plant, such as a pressurized water reactor nuclear power plant. Specifically, as shown in fig. 2, the fork blade root of the steam turbine in the nuclear power plant is generally designed with four tooth roots, the four tooth roots from the steam inlet side a to the steam outlet side B are numbered sequentially from 1# -4 # tooth roots, and each tooth root is provided with two through rivet holes, including a first rivet hole 1 and a second rivet hole 2. According to the finite element analysis result of the stress distribution of the forked blade, the first riveting hole 1 positioned above is an area with the largest load and is also the part which is most prone to failure, and the inspection method of the forked blade root of the nuclear power plant is used for inspecting the first riveting hole area.
As shown in fig. 1, the method for inspecting a forked blade root of a nuclear power plant comprises the following steps:
step S1: placing a preset probe at a blade body or a root platform corresponding to a first riveting hole area to be detected;
step S2: in the detection process, receiving a reflected signal of a blade root, and displaying the reflected signal in global focusing imaging of an ultrasonic detector on a first rivet hole area to be detected; wherein, the global focusing image can be obtained by global focusing imaging;
step S3: and judging whether the first riveting hole has defects according to the position information of the reflection signal in the global focusing image.
Specifically, step S1 includes:
step S11: presetting a plurality of probes with different scanning ranges;
step S12: and selecting probes in corresponding scanning ranges according to structures of the first riveting hole area on the inner arc side of the tooth to be detected and the first riveting hole area on the outer arc side of the tooth, and placing the probes at blade bodies or root platforms corresponding to the first riveting hole area on the inner arc side of the tooth and the first riveting hole area on the outer arc side of the tooth. Wherein fig. 2, 3 and 4 show the inner tooth arc side C and the outer tooth arc side D. The first rivet hole area comprises a tooth inner arc side first rivet hole area E and a tooth outer arc side first rivet hole area F. The blade bodies corresponding to the first riveting hole area E on the inner arc side of the tooth and the first riveting hole area F on the outer arc side of the tooth are scanning positions 2 and 3, and the corresponding root platform is divided into platform scanning positions 1, 4, 5, 6, 7 and 8.
In some embodiments, three probes of different scanning ranges are preset, including a first probe, a second probe, and a third probe. In some embodiments, for example, comprising: the wedge longitudinal wave detecting device comprises a first probe, a second probe and a third probe, wherein the wedge longitudinal wave incidence angle is larger than 8 degrees and smaller than 9 degrees, the wedge longitudinal wave incidence angle is larger than 37 degrees and smaller than 39 degrees, and the wedge longitudinal wave incidence angle is larger than 35 degrees and smaller than 37 degrees.
Preferably, the first probe parameters are: the main frequency is 5MHz, 10 array elements are arranged, the specification of the array elements is 0.5mm multiplied by 6mm, and the longitudinal wave incident angle of a wedge block is 8.4 degrees;
the second probe parameters were: the dominant frequency is 5MHz, 10 array elements are provided, the specification of the array elements is 0.5mm multiplied by 6mm, and the transverse wave incident angle of a wedge block is 38 degrees;
the third probe parameters were: the main frequency is 5MHz, 12 array elements are 12, the specification of the array elements is 0.5mm multiplied by 6mm, and the transverse wave incident angle of a wedge block is 36 degrees.
It should be noted that the above-mentioned probe parameters are only preferred examples, and are not meant to be limiting only, and in other embodiments, the wedge longitudinal wave incident angle may be selected within a corresponding range.
The first probe is placed at a platform scanning position 1 and used for detecting a first riveting hole area on the outer arc side of a 1# tooth, the first probe is placed at a platform scanning position 4 and used for detecting a first riveting hole area on the outer arc side of a 4# tooth, and the first probe is placed at platform scanning positions 5-7 and used for detecting first riveting hole areas on the inner arc side of 1# to 3# teeth;
the second probe is placed at a platform scanning position 8 and used for detecting a first riveting hole area on the inner arc side of the 4# tooth;
and the third probe is placed at the leaf body scanning position 2-3 and used for detecting the first riveting hole area on the outer arc side of the 2# -3 # teeth.
In addition, as shown in fig. 5, in the detection process, the probe adopts sawtooth scanning to ensure that the sound beam can effectively cover the region to be detected in the detection process. Meanwhile, the ultrasonic detector used for detection needs to support full-focus array ultrasonic detection real-time imaging, defects found in the detection process can be displayed in the full-range focused image, the number of channels of the ultrasonic detector is not less than 12, and the number of the channels of the ultrasonic detector means that the detector supports probes with 12 array elements to be normally used.
It should be noted that, here, the probes adopt different incident angles, and are mainly influenced by the structure of the blade root, and the probes in corresponding scanning ranges can be selected according to the sizes of the structural scanning surfaces of the first rivet hole area on the inner arc side of the tooth to be detected and the first rivet hole area on the outer arc side of the tooth to be detected. The three incident angles of the three probes are determined values and are the optimal angles after field test verification. The number of array elements of the probe is too small, the sound velocity energy is low, the sound field range is small, and the situation that the region to be detected cannot be covered can occur; the number of the array elements is too large, the size of the probe is easily overlarge, and the probe cannot be placed on the detection surface of a workpiece to be detected, and the probe with the array element number of 10-12 is generally selected for the blade root structure.
In step S2, the reflection signal of the blade root includes a reflection signal of a geometry inherent to the blade root itself; or the natural geometry of the blade root itself and the reflection signals generated by other changes in the blade root. The reflection signals generated by other changes in the blade root are signals that the blade root has defects, so that the defect of the blade root, namely the crack, can be judged as long as the reflection signals generated by other changes in the blade root are detected.
In this embodiment, ultrasonic detector carries out the universe focus imaging to the first riveting hole region of waiting to examine, includes:
dividing a first riveting hole area image to be detected into a plurality of grid areas at preset intervals, as shown in fig. 6; wherein the preset interval is 1 mm;
focusing and imaging each grid point;
and carrying out superposition imaging on the focused images of the grid points to obtain a global focused image of all grid points of the first riveting hole area to be detected.
Specifically, the ultrasonic detector of the invention carries out global focusing imaging on a first riveting hole area to be detected and follows the following basic principle: the four tooth roots are inspected by adopting a full-focusing array ultrasonic detection technology, and the basic principle of the full-focusing array ultrasonic detection is as follows: and dividing the region to be detected defined by data reconstruction into grids, calculating a focusing rule for each point on the grids for all array elements of the full-focusing ultrasonic probe, and imaging. All recorded signals are correspondingly time shifted before summing the points of the grid. And after each point of the grid is reconstructed, the cycle is finished. The full-focusing ultrasonic detection technology can realize the combination optimization focusing and the spatial resolution at the position of one probe, and can complete the large-area direct imaging. The amplitude I (x, z) at a particular focus point (x, z) may be expressed as
In the formula, Aij(tij(x, z)) is amplitude information for representing a target focus point (x, z) in the ultrasonic echo signals of the excitation array element i and the receiving array element j. t is tij(x, z) is the delay time of the amplitude, including the time required for the array element i excitation to propagate to the target focal point (x, z) and be received by array element j.
The imaging mode effectively solves the problem that the conventional phased array ultrasonic detection technology can only realize linear focusing in the projection direction, the horizontal direction or the equal sound path area, and effectively improves the detection sensitivity and the detection efficiency.
In this embodiment, the displaying of the geometry reflection signal in step S2 in the global focus imaging performed by the ultrasonic detector on the first rivet hole area to be detected includes: as shown in fig. 7, the reflected signal is displayed in the global focus imaging performed by the ultrasonic detector on the first rivet hole region to be detected through the horizontal distance and the vertical distance.
Accordingly, step S3 includes: and judging whether other shooting signals exist in the global focusing image or not by taking the horizontal distance and the vertical distance of the inherent geometric structure reflection signal of the blade root in the global focusing image as the reference, and if so, judging that the first riveting hole has defects, namely, reflection signals generated by other changes in the blade root exist.
In this embodiment, the method for inspecting a forked blade root of a nuclear power plant further includes:
step S4: and if the blade root is judged to have defects, acquiring the signal reflection equivalent of the defects, comparing the signal reflection equivalent with the signal reflection equivalent of the preset reference defects, and judging the sizes of the defects.
Wherein, the signal reflection equivalent of the default reference defect includes:
presetting a reference block, and forming at least one defect notch groove in the first rivet hole area; in some embodiments, as shown in fig. 8 and 9, on the reference block, two artificial defect notches are carved in the first rivet hole area of each tooth root, four tooth roots are carved, and two places of the first rivet hole center of each tooth root, which are horizontally 180 degrees, are carved with one notch respectively, the length is that the notch penetrates through the tooth root, the depth is 1.0mm, and the width is 0.2 mm;
placing the probe at a blade body or a tooth root platform corresponding to a first riveting hole area to be detected, and repeating the steps as above;
and adjusting the gain value of the ultrasonic detector, adjusting the amplitude to a preset value of full screen, taking the gain value as the reference sensitivity of detection, taking the reflection equivalent of the defect notch as the signal reflection equivalent of a preset reference defect, and taking the signal reflection equivalent as the basis for judging whether the detection system drifts or not, finds the defect or not and judges the size of the defect in the subsequent detection process. In some embodiments, the preset value is 80%.
In some embodiments, in order to ensure the accuracy of detection, the ultrasonic detector is initially calibrated, intermediately calibrated and finally calibrated before each detection; the initial calibration, the middle calibration and the end calibration are used for adjusting the gain value of the ultrasonic detector and adjusting the amplitude to a preset value of full screen. Specifically, before each detection, the performance of the instrument and the probe combination needs to be adjusted for initial calibration, so as to ensure that the reflection echo height of the artificial defect notch at each part reaches 80% of the full screen; within 4h of detection, intermediate calibration is required; after the inspection is completed, the end calibration is also required. The middle calibration and the end calibration are performed in the same process as the initial calibration, and if the gain values of the middle calibration and the end calibration exceed +/-2 dB compared with the gain value of the initial calibration, the detected blade needs to be detected again.
By implementing the invention, the following beneficial effects are achieved:
according to the invention, the preset probe is arranged at the blade body or the root platform corresponding to the first riveting hole area to be detected, the reflection signal of the root of the blade is received in the detection process, the reflection signal is displayed in the global focused imaging of the ultrasonic detector on the first riveting hole area to be detected, and whether the first riveting hole has defects or not is judged according to the position information of the reflection signal in the global focused image, so that the crack defects of the first riveting hole can be effectively found, the defects in the detection process are easier to identify, and the detection sensitivity and the detection efficiency are higher.
It is to be understood that the foregoing examples, while indicating the preferred embodiments of the invention, are given by way of illustration and description, and are not to be construed as limiting the scope of the invention; it should be noted that, for those skilled in the art, the above technical features can be freely combined, and several changes and modifications can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention; therefore, all equivalent changes and modifications made within the scope of the claims of the present invention should be covered by the claims of the present invention.