JP2014048183A - Gap measuring device, method, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a measurement error due to a position shift of an object when the object is arranged shifting in an axial direction of a pipe.SOLUTION: There is provided a gap measuring device 1 which measures distances from an outer peripheral surface of a pipe to a plurality of objects arranged along a peripheral direction of the pipe, the gap measuring device 1 including: a signal acquisition part 11 which acquires an inspection signal when an eddy current flaw detection probe which does not have resolution in the peripheral direction of the pipe is scanned along an axis of the pipe; a feature quantity calculation part 15 which calculates an amplitude integrated value of an inspection signal; and a gap quantity determination part 16 which determines a gap quantity corresponding to the amplitude integrated value calculated by the feature quantity calculation part 15 using first information to which the amplitude integrated value and the gap quantity are related in advance.

Description

  The present invention relates to a gap measuring device and method for measuring a distance from an outer peripheral surface of a pipe to an object using a pipe insertion type probe, for example, as in a gap measurement between a heat transfer pipe surface and a steady rest fitting in a nuclear power plant. , And programs.

In a heat exchanger used in a nuclear power plant, a large number of heat transfer tubes are densely arranged inside a trunk, and a primary coolant flowing inside the heat transfer tube and a secondary coolant flowing outside the heat transfer tube are arranged. Heat exchange takes place between them.
In the heat exchanger, an inverted U-shaped curved pipe near the top of the heat transfer tube has, for example, a V-shaped steadying bracket (in order to suppress vibration of the heat transfer tube caused by the flow of the secondary coolant ( AVB) is inserted (see, for example, Patent Documents 1 and 2).
Since this steady-state fitting is inserted between the rows of the heat transfer tubes, each heat transfer tube is supported by two steady-state fittings from a position facing each other across the tube.

  By the way, it is desirable that the steady rest metal fitting and the surface of the heat transfer tube are in contact with each other, and it is necessary to confirm whether or not a gap exceeding the allowable range is generated between them. This is because if the gap exceeds the allowable range, friction with the steady-state fitting occurs due to vibration of the heat transfer tube due to the flow of the secondary coolant, leading to thinning of the heat transfer tube and the like.

Conventionally, methods disclosed in Patent Documents 1 and 2 are known as methods for measuring a gap between a heat transfer tube and a steady rest fitting.
In Patent Document 1, an ultrasonic probe inserted into a heat transfer tube is positioned offset from the central axis of the heat transfer tube, and ultrasonic waves are transmitted at an angle at which ultrasonic waves that are orthogonal to the support surface of the steady-state fitting are emitted. A method of measuring a gap by making it enter the inner surface of a heat tube is disclosed.
Patent Document 2 discloses that the gap is measured by using a measurement probe that is rotatable along the inner peripheral surface of the heat transfer tube.

JP-A-64-75907 JP-A-2-259405

By the way, about the heat exchanger tube of a heat exchanger, a crack and damage inspection are performed at the time of manufacture or a maintenance inspection. For this crack / damage inspection, a bobbin coil type eddy current flaw probe (hereinafter referred to as a “bobbin coil type probe”) that can generally perform high-speed flaw detection and is excellent in insertion into a bent tube portion is used.
Therefore, if the bobbin coil type probe can be used for the clearance measurement of the steady rest metal fitting, the inspection signal acquired in the crack / damage inspection can be diverted, and there is no need to separately perform an inspection for the clearance measurement, Inspection time can be greatly shortened.

  However, since the bobbin coil type probe forms an ECT coil by winding a conducting wire in the circumferential direction of the cylindrical probe, it does not have resolution in the circumferential direction of the heat transfer tube. Therefore, when the gap amount is measured using the calibration curve from the amplitude of the inspection signal acquired by the generally known bobbin coil probe, sufficient measurement accuracy cannot be obtained due to the following reason. was there.

FIGS. 13 to 15 show the positional relationship between the heat transfer tubes 20 and the steady rests 21a and 21b supported from both sides of the heat transfer tubes 20 (see (a)), and the inspection signals obtained by the bobbin coil type probe 23 (( b)) and a gap amount Y (= α + β) (see (c)) detected based on the amplitude of the inspection signal.
13 (a), 14 (a), and 15 (a), α is the amount of clearance between the steady rest 21a and the outer peripheral surface of the heat transfer tube 20, and β is the rest bracket 21b and the outer peripheral surface of the heat transfer tube. The gap amounts Y and Y indicate the sum of the gap amounts α and β, and the steady rests 21a and 21b are arranged so that the value of Y (= α + β) is the same in any figure.

  As shown in FIG. 13 (a), when the steady rests 21a and 21b are opposed to each other with the heat transfer tube 20 interposed therebetween, and the gap amounts α and β are not biased (when α = β), the inspection is performed. The amplitude A1 of the signal is a value corresponding to the gap amount Y (see FIG. 13B), and a relatively accurate gap amount Y1 can be measured (see FIG. 13C).

  On the other hand, as shown in FIG. 14 (a), when the steady rests 21a and 21b are displaced along the axial direction of the heat transfer tube 20, as shown in FIG. 14 (b). The amplitude A2 of the inspection signal is smaller than the amplitude A1 of the inspection signal shown in FIG. 13B (A2 <A1). Therefore, in this case, as shown in FIG. 14C, the gap amount Y2 obtained from the amplitude A2 becomes larger than the gap amount Y1, and the gap amount is overestimated.

  Further, as shown in FIG. 15 (a), when the steady rests 21a and 21b are opposed to each other, but the gap amounts α and β are biased, as shown in FIG. 15 (b). The amplitude A3 of the inspection signal is larger than the amplitude A1 of the inspection signal shown in FIG. 13B (A3> A1). Therefore, in this case, as shown in FIG. 15C, the gap amount Y3 obtained from the amplitude A3 is smaller than the gap amount Y1, and the gap amount is underestimated.

The present invention has been made in view of such circumstances, and one of the purposes thereof is a measurement error caused by the displacement when the object is displaced in the axial direction of the tube. It is to provide a gap measuring device, method, and program capable of reducing the above.
Another object is to measure gaps that can reduce measurement errors due to deviations in gaps between multiple objects when gaps between each object and the outer peripheral surface of the pipe are biased. An apparatus, method, and program are provided.

  The present invention is a gap measuring device that measures the sum of distances from the outer peripheral surface of a pipe to a plurality of objects arranged along the circumferential direction of the pipe as a gap amount, and has a resolution in the circumferential direction of the pipe. A signal acquisition unit that acquires an inspection signal when a non-eddy current flaw detection probe is scanned along the axis of the tube, a feature amount calculation unit that calculates an amplitude integral value of the inspection signal, an amplitude integral value, and a gap amount Is provided with a gap amount determining unit that determines a gap amount corresponding to the amplitude integral value calculated by the feature amount calculating unit using the first information associated with.

According to such a configuration, the inspection signal when the eddy current flaw detection probe having no resolution in the circumferential direction of the tube is scanned along the axis of the tube is acquired by the signal acquisition means, and the amplitude integral value of the inspection signal is The gap amount is calculated by the feature amount calculation means, and the gap amount is determined by the gap amount determination means based on the amplitude integral value.
Here, since the amplitude integral value is not affected by the positional deviation of the object in the axial direction of the tube, as will be described later, even if the target is displaced in the axial direction of the pipe, it is caused by the positional deviation. Measurement error can be reduced. Thereby, it becomes possible to improve the precision of the distance measurement to a target object.

  In the inspection signal acquired by the signal acquisition unit, the gap measuring device includes a measurement target range setting unit that sets a measurement target range in an axial direction in which the object can exist, and a measurement target range from the inspection signal to the measurement target range. Signal extraction means for extracting a corresponding inspection signal, and the calculation means may calculate the integrated amplitude value using the inspection signal extracted by the signal extraction means.

  In this way, not all the inspection signals acquired by the signal acquisition means are used, but the inspection signals corresponding to the measurement target range are extracted from the inspection signals, and the amplitude integral value is obtained only for the extracted inspection signals. It is good also as calculating and detecting the amount of gaps. Thus, by specifying the range in the axial direction in which the object can exist, the amount of signal used for the measurement of the gap amount is limited, so that the error can be reduced.

  In the gap measurement device, when the sampling width of signal acquisition by the signal acquisition unit is constant, the calculation unit calculates an amplitude integration value instead of the amplitude integration value, and the gap amount determination unit Instead of the first information, the gap information corresponding to the amplitude integrated value calculated by the calculating means may be determined using second information in which the amplitude integrated value and the gap amount are associated in advance.

  The integrated amplitude value, like the integrated amplitude value, is not affected by the displacement of the object in the axial direction of the tube, so even if the object is displaced in the axial direction of the tube, the measurement based on the displacement is performed. The error can be reduced. Thereby, it becomes possible to improve the precision of the distance measurement to a target object.

  In the gap measurement device, the calculation means calculates an average amplitude value of a predetermined fixed section length instead of the amplitude integral value, and the gap amount determination means replaces the first information, The gap amount corresponding to the average amplitude value of the fixed section length calculated by the calculation unit may be determined using the third information in which the average amplitude value of the fixed section length and the gap amount are associated in advance. .

  The average amplitude value of a certain section length is not affected by the positional deviation of the object with respect to the axial direction of the tube, similarly to the integral value of the amplitude, so even if the target object is displaced in the axial direction of the pipe, Measurement errors due to misalignment can be reduced. Thereby, it becomes possible to improve the precision of the distance measurement to a target object.

  The present invention is a gap measuring device for measuring the distance from an outer peripheral surface of a tube to a plurality of objects arranged in the circumferential direction of the tube, and an eddy current flaw detection probe having no resolution in the circumferential direction is provided on the tube. When scanning along the axis, signal acquisition means for acquiring a plurality of inspection signals obtained by a plurality of different excitation frequencies, and a plurality of feature quantities related to amplitude or phase are calculated for each of the inspection signals. A feature amount calculation unit, and a plurality of feature amounts and fourth information in which distances to the objects are associated in advance, and the fourth information and each feature amount calculated by the feature amount calculation unit And a gap amount determining means for obtaining a distance from the outer peripheral surface of the pipe to each of the objects or a total of the distances.

  According to the present invention, a feature amount is calculated using a plurality of inspection signals obtained at different excitation frequencies, and the feature amount is used for fourth information prepared in advance to obtain a gap amount. When the excitation frequency is different, the attenuation rate with respect to the distance is different, so that the relationship between the gap amount and the amplitude shows independent characteristics. Therefore, by using a plurality of inspection signals having different attenuation rates with respect to such distances, even when the distance between each object arranged along the circumferential direction and the outer peripheral surface of the pipe is uneven, the gap It is possible to obtain the gap amount without being greatly affected by the amount deviation.

  The present invention is a gap measurement method for measuring a sum of distances from an outer peripheral surface of a pipe to a plurality of objects arranged in the circumferential direction of the pipe as a gap amount, and has a resolution in the circumferential direction of the pipe. An inspection signal obtained by scanning a non-eddy current flaw detection probe along the axis of the tube is obtained, an amplitude integrated value of the inspection signal is calculated, and first information in which the amplitude integrated value and the gap amount are associated in advance is obtained. And a gap measuring method for determining a gap amount corresponding to the amplitude integral value.

  In the gap measuring method, when the sampling width of the inspection signal is constant, the amplitude integrated value is calculated instead of the amplitude integrated value, and the amplitude integrated value and the gap amount are previously calculated instead of the first information. A gap amount corresponding to the integrated amplitude value may be determined using the second information associated with the second information.

  In the gap measurement method, instead of the amplitude integral value, a predetermined average amplitude value of a certain section length is calculated, and the third information in which the average amplitude value of the certain section length is associated with the gap amount in advance. May be used to determine the gap amount corresponding to the average amplitude value of the certain section length.

  The present invention is a gap measurement method for measuring the distance from the outer peripheral surface of a tube to a plurality of objects arranged along the circumferential direction of the tube, and an eddy current flaw detection probe having no resolution in the circumferential direction is provided on the tube. When scanning along the axis, obtain a plurality of inspection signals obtained by a plurality of different excitation frequencies, respectively, and in each of the inspection signals, calculate a plurality of feature quantities related to amplitude or phase, respectively, A feature amount and a distance to each target object have fourth information associated in advance, and the distance from the outer peripheral surface of the tube to each target object using the fourth information and each feature amount. Alternatively, a gap measuring method for obtaining the sum of the distances is provided.

  The present invention is a gap measurement program for causing a computer to execute a gap measurement that measures the sum of distances from a peripheral surface of a pipe to a plurality of objects arranged along the circumferential direction of the pipe as a gap amount, A process of obtaining an inspection signal when an eddy current flaw detection probe having no resolution in the circumferential direction of the tube is scanned along the axis of the tube, a process of calculating an amplitude integral value of the inspection signal, and an amplitude integral value And a gap measurement program including processing for determining a gap amount corresponding to the amplitude integral value using first information in which a gap amount and a gap amount are associated in advance.

  When the sampling width of the inspection signal is constant, the gap measurement program includes a process for calculating an amplitude integrated value instead of the amplitude integrated value, an amplitude integrated value and a gap amount instead of the first information. May include a process of determining a gap amount corresponding to the integrated amplitude value using the second information previously associated.

  In the gap measurement program, instead of the integrated amplitude value, a process for calculating a preset average amplitude value of a certain section length, an average amplitude value of a certain section length, and a gap amount are associated in advance. 3 information may be used to determine a gap amount corresponding to the average amplitude value of the certain section length.

  The present invention is a gap measurement program for causing a computer to execute gap measurement for measuring the distance from the outer peripheral surface of a pipe to a plurality of objects arranged along the circumferential direction of the pipe, and having a resolution in the circumferential direction. A process for obtaining a plurality of inspection signals obtained by a plurality of different excitation frequencies when a non-eddy current flaw detection probe is scanned along the axis of the tube, and a plurality of amplitude or phase in each of the inspection signals A plurality of feature amounts and distances to the respective objects are pre-associated with each other, and using the fourth information and each feature amount, And a clearance measurement program including a process of obtaining a distance from the outer peripheral surface of the pipe to each of the objects or a sum of the distances.

  According to the present invention, when an eddy current flaw detection probe having no resolution in the circumferential direction of the tube is used to measure the amount of clearance between a plurality of objects arranged along the circumferential direction of the tube and the outer peripheral surface of the tube In addition, the measurement accuracy can be improved.

It is a figure showing an example of hardware constitutions of a crevice measuring device concerning a 1st embodiment of the present invention. It is the functional block diagram which expanded and showed the function with which the gap measuring device concerning a 1st embodiment of the present invention is provided. It is a figure for demonstrating an example of pre-processing. It is a figure for demonstrating an example of pre-processing. It is a figure for demonstrating an example of pre-processing. It is the figure which showed the conceptual diagram of the inspection signal when the position shift in the axial direction of the heat exchanger tube has not arisen in two steady rests, and its amplitude integral value. It is the figure which showed the conceptual diagram of the inspection signal when the position shift in the axial direction of the heat exchanger tube has arisen in two steady rests, and its amplitude integral value. It is the figure which showed an example of 1st information. It is a figure for demonstrating the production method of 1st information. It is a functional block diagram of the gap measuring device concerning a 2nd embodiment of the present invention. It is a figure for demonstrating the production method of 4th information. It is a figure for demonstrating the procedure of the clearance measurement by the clearance measuring device which concerns on 2nd Embodiment of this invention. It is a figure for demonstrating the problem in the case of measuring the amount of gaps based on amplitude. It is a figure for demonstrating the problem in the case of measuring the amount of gaps based on amplitude. It is a figure for demonstrating the problem in the case of measuring the amount of gaps based on amplitude.

FIG. 1 is a plan view showing an embodiment of a gap measuring device, method, and program according to the present invention applied to a case where a gap amount between a heat transfer tube in a nuclear power plant and a steady metal fitting supporting the heat transfer tube is detected. Will be described with reference to FIG.
The gap measuring device, method and program according to the present invention are applied when detecting the gap amount between the heat transfer tube and the steady rest described in detail below, and from the outer circumferential surface of the tube to the circumferential direction of the tube. It is widely applied when measuring the distance to a plurality of objects arranged along the line.

[First Embodiment]
FIG. 1 is a diagram illustrating an example of a hardware configuration of a gap measuring device 1 according to the first embodiment of the present invention. As shown in FIG. 1, a gap measuring device 1 according to this embodiment is a computer system (computer system), a CPU (Central Processing Unit) 2, a main storage device 3 such as a RAM (Random Access Memory), and an auxiliary device. A storage device 4, an input device 5 such as a keyboard and a mouse, a display device 6 for displaying data, a communication device 7 for exchanging information by communicating with external devices, and the like are provided. These units are connected to each other via a bus 8.

  The auxiliary storage device 4 is a computer-readable recording medium, such as a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, or a semiconductor memory. Various programs (for example, a gap measurement program) are stored in the auxiliary storage device 4, and the CPU 2 reads out the programs from the auxiliary storage device 4 to the main storage device 3 and executes them to implement various processes.

  FIG. 2 is a functional block diagram showing the functions provided in the gap measuring device 1 in an expanded manner. As shown in FIG. 2, the gap measuring device 1 mainly includes a signal acquisition unit 11, a measurement target range setting unit 12, a signal extraction unit 13, a preprocessing unit 14, a feature amount calculation unit 15, and a gap amount determination unit 16. It is provided as a configuration.

  The signal acquisition unit 11 acquires an inspection signal when an eddy current flaw detection probe having no resolution in the circumferential direction of the heat transfer tube is scanned along the axis of the heat transfer tube. Here, as an eddy current flaw detection probe having no resolution in the circumferential direction of the heat transfer tube, a bobbin coil type probe can be mentioned. For example, when a crack / damage inspection of a heat transfer tube at the time of manufacturing a nuclear plant or during a periodic inspection is performed using a bobbin coil probe, a flaw detection signal obtained in the inspection is sent to the signal acquisition unit 11. It may be input. Further, instead of diverting the inspection signal for the crack / damage inspection of the heat transfer tube, a separate test may be performed for gap measurement, and the inspection signal at that time may be input to the signal acquisition unit 11.

The measurement target range setting unit 12 sets a measurement target range in the axial direction of the tube in the inspection signal acquired by the signal acquisition unit 11.
Here, the support position of the steady rest fitting in the axial direction of the heat transfer tube may be specified by a structure position recognition function that specifies the position on the corresponding signal based on the known position information, or the analyst may You may specify the position on a signal manually. A measurement target range is determined based on the position information. In addition, since the support position of the steady rest metal fitting is assumed to be deviated with respect to the axial direction of the pipe, the measurement target range is long enough to allow for the maximum amount of deviation, and other adjacent It is preferable to set the length not to reach the structure signal. In particular, when only one pair of steady rests is measured as the inspection range, the entire range of the inspection signal may be set as the measurement target range.

The signal extraction unit 13 extracts an inspection signal in a range corresponding to the measurement target range from the inspection signal acquired by the signal acquisition unit 11.
The preprocessing unit 14 performs preprocessing on the inspection signal extracted by the signal extraction unit 13. Examples of pre-processing include zero point correction and drift removal processing. These processes are processes for setting the inspection signal in the range having no significant signal to zero.

  Hereinafter, an example of the preprocessing will be described with reference to FIGS. In the graphs shown in FIGS. 3 to 5, the vertical axis represents the inspection signal value, the horizontal axis represents time, in other words, the position of the heat transfer tube in the axial direction.

[Pretreatment 1]
As shown in FIG. 3, in the inspection signal V1 (L) before application of preprocessing, two points (P1, P2) having no significant signal are specified, and a straight line V0 (L) passing through the two points is calculated. Then, the inspection signal V (L) after the preprocessing is obtained by subtracting the straight line V0 (L) from the inspection signal V1 (L) before the preprocessing application.

[Pretreatment 2]
As shown in FIG. 4, a test signal V2 (L) is obtained by applying a median filter to a test signal V1 (L) before application of preprocessing, and this test signal V2 (L) is used as a test signal V1 before application of preprocessing. By subtracting from (L), the pre-processed inspection signal V (L) is obtained. At this time, the window width of the median filter is sufficiently longer than the assumed length of the steady rest in the axial direction.

[Pretreatment 3]
Further, as shown in FIG. 5, when the inspection signal V1 (L) before the preprocessing is applied is a self-comparison signal, that is, a signal whose polarity shifts to both negative and positive, the above preprocessing is performed. After performing drift removal using the method 1 or 2, the negative signal is inverted to become positive. In general, the self-comparing sensor interval is set to a distance suitable for detecting a minute defect, and a signal that is long in the axial direction, such as a steady rest metal signal, is not stored in its entirety. In the case where both an absolute comparison type signal and a self comparison type signal can be used, an absolute comparison type signal may be used as the inspection signal.

  The preprocessing described above may be performed before integration processing by the feature amount calculation unit 15 described later, and may be performed immediately after the signal acquisition unit 11, for example. It is desirable to select an appropriate order for the processing order according to the preprocessing method. For example, when the preprocessing is [Preprocessing 1], it is necessary to individually perform the preprocessing for each measurement target section. In the case of [Pre-processing 2], the window width of the median filter is determined in advance, and the processing including the peripheral signal in the target section is more effective without being affected by the discontinuity at the boundary. Therefore, it is more suitable to perform immediately after signal acquisition.

  The feature amount calculation unit 15 integrates the amplitude of the inspection signal after the preprocessing is applied, and calculates an amplitude integral value as the feature amount. Here, in FIG. 6, when the two steady rests 21 a and 21 b are arranged at the same position in the axial direction of the heat transfer tube 20, in other words, the two steady rests 21 a and 21 b have the axial direction of the heat transfer tube 20. The conceptual diagram of the test signals V1a and V1b and the amplitude integral value S1 in the case where the positional deviation in FIG. FIG. 7 shows a conceptual diagram of the inspection signals V2a and V2b and the amplitude integral value S2 when the two steady rests 21a and 21b are displaced in the axial direction of the heat transfer tube 20.

  6 and 7, the gap amounts α and β from the outer peripheral surface of the heat transfer tube 20 to the steady rests 21a and 21b are the same (α = β). 6 and 7, the signals V1a and V2a are provided with only the steady-state fitting 21a, and the signals obtained when the steady-state fitting 21b is not provided, and the signals V1b and V2b are provided with the steady-state fitting 21a. The signal V1ab and the signal V2ab that are obtained when only the steady-state fitting 21b is provided are the inspection signals obtained when both the steady-state fitting 21a and the steady-state fitting 21b are provided. Show. The inspection signal obtained when both the steady rest 21a and the steady rest 21b are provided is the inspection signal obtained when only the steady rest 21a and the steady rest 21b are provided. It becomes a signal substantially equal to the signal obtained by adding the inspection signals obtained in this case.

  As shown in FIGS. 6 and 7, even if the gap amount Y (= α + β) is the same, the inspection signal V1a and the inspection signal V1b are added according to the relative positional relationship between the steady rests 21a and 21b. The amplitude peak value A1 of the inspection signal V1ab substantially equal to the obtained signal is different from the amplitude peak value A2 of the inspection signal V2ab substantially equal to the signal obtained by adding the inspection signal V2a and the inspection signal V2b (A2 <A1). However, the amplitude integrated value S1 of the inspection signal V1ab and the amplitude integrated value S2 of the inspection signal V2ab have the same value regardless of whether or not there is a positional deviation if the value of the gap amount Y (= α + β) is the same ( 6 and 7, S1 = S2).

  In other words, when the amplitude integrated value of the inspection signals V1a and V2a related to the steady-state fitting 21a and the amplitude integrated value of the inspection signals V1b and V2b related to the steady-state fitting 21b are set to S0, as shown in the following formula (1), The amplitude integral value S1 when there is no deviation and the amplitude integral value S2 when there is a position deviation are both twice the value of S0.

  S1 = S2 = 2 × S0 (1)

  As described above, it can be seen from FIGS. 6 and 7 that the amplitude integral values S1 and S2 show values corresponding to the gap amount Y (= α + β) without being affected by the positional deviation. Therefore, by evaluating the gap amount using the amplitude integral value, the gap amount Y (α + β) can be accurately estimated without being affected by the positional deviation.

  Specifically, the feature amount calculation unit 15 (see FIG. 2) obtains the amplitude integral value S by the following equation (2).

  In equation (2), L1 is the start position of the measurement target range set by the measurement target range setting unit 12, and L2 is the end position of the measurement target range. V (L) is the inspection signal after the preprocessing is applied, and ΔL is the sampling width.

  The gap amount determination unit 16 determines the gap amount based on the amplitude integral value S calculated by the feature amount calculation unit 15. Specifically, the gap amount determination unit 16 has first information indicating the relationship between the amplitude integral value S and the gap amount Y. FIG. 8 shows an example of the first information. In FIG. 8, the horizontal axis represents the gap amount Y, and the vertical axis represents the amplitude integral value S. This first information is obtained as follows, for example.

First, a signal sample (teacher data) whose gap amount is known is acquired by a preliminary test using mock-up or the like in advance, and a correspondence relationship between the gap amount Y (= α + β) and the amplitude integral value S is obtained. Subsequently, as shown in FIG. 9, a signal sample whose gap amount is known is plotted in a coordinate space in which the gap amount Y is shown on the horizontal axis and the amplitude integrated value S is shown on the vertical axis. A curve is derived. This optimum curve corresponds to, for example, an evaluation formula that associates the gap amount Y with the amplitude integral value S.
For the derivation of the optimum curve, a known method such as multiple regression analysis, least square method, or neural network is used.
The gap amount determination unit 16 acquires a gap amount corresponding to the amplitude integrated value calculated by the feature amount calculation unit 15 from the first information obtained in this way.

According to the gap measuring apparatus 1 having the above configuration, an inspection signal when the bobbin coil probe is scanned along the axial direction of the heat transfer tube 20 is input to the signal acquisition unit 11, and the measurement target range setting unit 12 performs the axial direction. The measurement target range at is set. Subsequently, the signal extraction unit 13 extracts an inspection signal corresponding to the measurement target range from the inspection signal obtained by the signal acquisition unit 11.
The extracted inspection signal is subjected to preprocessing such as zero point correction and drift removal processing by the preprocessing unit 14 and then output to the feature amount calculation unit 15.

  The feature amount calculation unit 15 calculates the amplitude integral value of the inspection signal after the preprocessing, and the gap amount corresponding to the amplitude integration value is determined by the gap amount determination unit 16 using the first information. The gap amount Y (= α + β) determined by the gap amount determination unit 16 is provided to the user by being displayed on the display device 6 (see FIG. 1), for example.

  As described above, according to the gap measuring device 1 according to the present embodiment, the inspection signal when the bobbin coil probe 23 having no resolution in the circumferential direction of the heat transfer tube 20 is scanned along the axial direction of the heat transfer tube. Since the gap amount is determined using the integral value of the amplitude of the inspection signal as a feature value, as shown in FIG. 7, the position of the steady-state fitting is shifted with respect to the axial direction of the heat transfer tube. However, the gap amount Y (= α + β) can be detected without being affected by the positional deviation.

  In the above-described embodiment, when the eddy current flaw detection probe is scanned at a constant speed and data is acquired at equal time intervals, the amplitude integral value S is calculated using the time T instead of the axial position L. It is good to do. This is because if the time is T, the relationship between the time T and the position L in the axial direction is linear (L = u × T + L0, where u and L0 are constants). This is because the integral value can be obtained. In this case, the amplitude integral value S is obtained by the following equation (3).

In equation (3), t1 is the start time of the measurement target range set by the measurement target range setting unit 12, t2 is the end time of the measurement target range, V (T) is the inspection signal after applying the preprocessing, and ΔT is Sampling time u is the scanning speed of the probe, ΔT × u is the sampling width in the axial direction, in other words, the moving distance of the eddy current flaw detection probe in the sampling unit time.
Normally, since the inspection signal is sampled at equal time intervals, it is easier to use the time T than the axial position L. However, even if the setting is constant, if there is a substantial local speed change, or if an error between the set speed and the actual speed is assumed, the sampling width is corrected so that it approaches the actual speed. It is desirable. Examples of the correction include a method in which an actual average sampling width is obtained based on the distance between structures with known distances and the number of sampling points, and this average sampling width is used for integration calculation. In this case, the sampling width varies corresponding to the elapsed time from the start time.

  Further, in the present embodiment, the gap amount is determined based on the amplitude integral value. For example, when the sampling width ΔL in the axial direction of the heat transfer tube is constant, instead of the amplitude integral value, the amplitude is determined. The integrated value S ′ may be used. For example, the integrated amplitude value S ′ is obtained by the following equation (4).

In the equation (4), L1 is the start position of the measurement target range set by the measurement target range setting unit 12, and L2 is the end position of the measurement target range. V (L) is an inspection signal after the preprocessing is applied.
In this case, the gap amount determination unit 16 has second information in which the amplitude integrated value and the gap amount are associated in advance, and the gap amount corresponding to the amplitude integrated value is detected using this second information. . In this case, the method for creating the second information is the same as the method for creating the first information described above. Similarly to the amplitude integrated value, the integrated amplitude value is not affected by the positional deviation of the steady rest in the axial direction of the pipe, and therefore, accurate clearance evaluation can be performed.

When the measurement target range is set to a constant value, an average amplitude value in a preset fixed section length may be used instead of the amplitude integral value S. In this case, the gap amount determination unit 16 has the third information in which the average amplitude value of the certain section length and the gap amount are associated in advance, and the average information of the certain section length is obtained using this third information. A corresponding gap amount is detected. Note that the third information creation method in this case is the same as the first information creation method described above.
Like the amplitude integral value, the average amplitude value of a certain section length is not affected by the position shift of the steady rest in the axial direction of the pipe, and therefore, accurate gap evaluation can be performed.

  Note that the inspection signal obtained by the eddy current flaw detection probe is a complex value and has a real part and an imaginary part, but either one is displayed for simplicity. The “amplitude” of the inspection signal has various types such as the real part amplitude, the imaginary part amplitude, and the total amplitude (maximum length on the Lissajous display). Which amplitude should be used depends on the calibration method, but it is desirable to use the amplitude at which the signal of the object is prominent.

[Second Embodiment]
In the gap measuring device 1 according to the first embodiment described above, the influence due to the positional deviation of the steady rests 21a and 21b with respect to the axial direction of the heat transfer tube 20 could be eliminated. However, as shown in FIG. If α and β are biased, the error may not be eliminated. In order to eliminate such an error due to the deviation of the gap amounts α and β, in the second embodiment, a plurality of inspections obtained by a plurality of excitation frequencies by scanning the bobbin coil probe along the axial direction of the heat transfer tube. The signal is acquired, and the gap amount Y (α + β) is detected using the acquired plurality of inspection signals.

Hereinafter, a gap measuring device, method, and program according to the present embodiment will be described with reference to the drawings.
FIG. 10 is a functional block diagram of the gap measuring device 1 ′ according to the present embodiment. As illustrated in FIG. 10, the gap measurement device 1 ′ according to the present embodiment includes a signal acquisition unit 51, a measurement target range setting unit 52, a signal extraction unit 53, a preprocessing unit 54, a feature amount calculation unit 55, and a gap amount. A determination unit 56 is provided.
The signal acquisition unit 51 acquires a plurality of inspection signals obtained by a plurality of mutually different excitation frequencies by scanning the bobbin coil probe along the axis of the heat transfer tube.
The measurement target range setting unit 52 sets the measurement target range in the axial direction of the heat transfer tube in each inspection signal acquired by the signal acquisition unit 51. The method for setting the measurement target range is the same as in the first embodiment described above.
The signal extraction unit 53 extracts the inspection signal corresponding to the measurement target range from each inspection signal.

The preprocessing unit 54 performs preprocessing on each inspection signal extracted by the signal extraction unit 53. The preprocessing method and the like are the same as those in the first embodiment described above.
The feature amount calculation unit 55 calculates a preset feature amount in each inspection signal after the preprocessing is applied. The feature quantity is related to amplitude or phase. Examples of the feature quantity related to amplitude include amplitude peak value, average amplitude, amplitude integral value, and the like. Examples of the feature quantity related to phase include phase angle and the like. Can be mentioned.
Note that the type of feature amount used for the gap amount measurement may be changed according to each inspection signal. For example, the phase angle may be calculated as a feature amount for one inspection signal, and the average amplitude may be calculated as a feature amount for the other inspection signals. Thus, the feature quantity to be calculated can be arbitrarily determined.

The gap amount determination unit 56 calculates the gap amount Y using each feature amount calculated for each inspection signal. Specifically, the gap amount determination unit 56 has fourth information in which each combination of feature amounts is associated with a gap amount.
The fourth information is created as follows, for example.
First, signal samples (teacher data) in which the gap amounts α and β are known are obtained by a preliminary test using mockup or the like, and the amplitude integral value X1 of the inspection signal at the gap amounts α and β and the excitation frequency F1, And the correspondence relationship of the amplitude integral value X2 of the inspection signal at the excitation frequency F2. Further, using the amplitude integral values X1 and X2, the square of the amplitude integral value X1 (X3), the square of the amplitude integral value X2 (X4), and a value obtained by multiplying the amplitude integral values X1 and X2 (X5) Is also calculated.
By such a calculation process, for example, as shown in FIG. 11, the gap amounts α, β, Y (= α + β), the amplitude integral values X1, X2, and the parameters X3, X4, X5 based on the amplitude integral values X1, X2 Can be obtained.

Subsequently, an evaluation formula of Y (α + β) = f (X1, X2, X3, X4, X5) is derived using a known method such as multiple regression analysis, least square method, neural network, and the like. This is fourth information.
Instead of the above evaluation formula, for example, the fourth information may be included as a multidimensional map having coordinate axes corresponding to the number of feature quantities.

  The gap amount determination unit 56 uses the fourth information obtained in this way, and the gap amount Y (= α + β) corresponding to the amplitude integral values X1 and X2 at each excitation frequency acquired by the feature amount calculation unit 55. To get.

  According to such a gap measuring apparatus 1 ′, as shown in FIG. 12, the inspection signal J1 with the excitation frequency F1 and the inspection signal J2 with the excitation frequency F2 are input, and then these inspection signals J1 and J2 are input. Is set (step SA1), and inspection signals j1 and j2 in the set measurement target range are extracted from the inspection signals J1 and J2 (step SA2).

  Subsequently, pre-processing is performed on each of the extracted inspection signals j1 and j2 (step SA3), and the amplitude integral values X1 and X2 that are feature amounts using the inspection signals j1 ′ and j2 ′ after application of the preprocessing. Is calculated (step SA4). When the amplitude integrated value X1 of the inspection signal J1 and the amplitude integrated value X2 of the inspection signal J2 are calculated in this way, these amplitude integrated values X1 and X2 are converted into an evaluation expression (third information) prepared in advance. By substituting, the gap amount Y is calculated (step SA5).

As described above, according to the present embodiment, the feature amounts are calculated using a plurality of inspection signals obtained at different excitation frequencies, and the feature amounts are used for the third information prepared in advance. The quantity Y is obtained. When the excitation frequency is different, the attenuation rate with respect to the distance is different, so that the relationship between the gap amount and the amplitude shows independent characteristics. Therefore, by using a plurality of inspection signals having different attenuation rates with respect to such distances, as shown in FIG. 15, even when the gap amount is biased, it is not significantly affected by the bias of the gap amount, A gap amount Y (= α + β) can be obtained.
In the above description, the evaluation formula for the gap amount Y (= α + β) is obtained as the fourth information. However, according to the present embodiment, the evaluation formula for the minimum value of the gap amounts α, β, It is also possible to derive an evaluation formula for the maximum value of the gap amounts α and β, respectively, and use these evaluation formulas to obtain the smaller distance or the larger distance of the gap amounts α and β, respectively. It is. As described above, according to the gap measuring apparatus according to the present embodiment, not only the gap amount Y (= α + β) but also the gap amount α and the gap amount β can be measured.

  In the first embodiment and the second embodiment described above, the case where two objects are arranged in the circumferential direction of the tube and the sum of the distances from the outer peripheral surface of the tube to each object has been described. The number of objects to be arranged is not limited to this, and for example, three or more objects may be arranged in the circumferential direction of the tube. In this case, what is necessary is just to produce the 1st information etc. which were mentioned above according to the target object to measure, respectively.

11, 51 Signal acquisition unit 12, 52 Measurement target range setting unit 13, 53 Signal extraction unit 14, 54 Preprocessing unit 15, 55 Feature amount calculation unit 16, 56 Gap amount determination unit

Claims (13)

A gap measuring device that measures the sum of distances from a peripheral surface of a pipe to a plurality of objects arranged along the circumferential direction of the pipe as a gap amount,
Signal acquisition means for acquiring an inspection signal when an eddy current flaw detection probe having no resolution in the circumferential direction of the tube is scanned along the axis of the tube;
A feature amount calculating means for calculating an amplitude integral value of the inspection signal;
A gap measuring device comprising: gap amount determining means for determining a gap amount corresponding to the amplitude integrated value calculated by the feature amount calculating means using the first information in which the amplitude integrated value and the gap amount are associated in advance. . In the inspection signal acquired by the signal acquisition means, a measurement target range setting means for setting a measurement target range in the axial direction in which the object can exist;
Signal extraction means for extracting an inspection signal corresponding to the measurement target range from the inspection signal;
The gap measuring device according to claim 1, wherein the calculating unit calculates the integrated amplitude value using the inspection signal extracted by the signal extracting unit. When the sampling width of signal acquisition by the signal acquisition unit is constant, the calculation unit calculates an amplitude integrated value instead of the amplitude integrated value,
The gap amount determining means uses the second information in which the amplitude integrated value and the gap amount are associated in advance instead of the first information, and the gap amount corresponding to the amplitude integrated value calculated by the calculating means. The gap measuring device according to claim 1 or 2, wherein the gap is determined. The calculation means calculates an average amplitude value of a predetermined fixed section length instead of the amplitude integral value,
The gap amount determination means is calculated by the calculation means using third information in which an average amplitude value of a predetermined section length and a gap amount are associated in advance instead of the first information. The gap measuring device according to claim 1 or 2, wherein a gap amount corresponding to an average amplitude value of a certain section length is determined. A gap measuring device that measures the distance from the outer peripheral surface of the tube to a plurality of objects arranged along the circumferential direction of the tube,
A signal acquisition means for acquiring a plurality of inspection signals obtained by a plurality of different excitation frequencies when an eddy current flaw detection probe having no resolution in the circumferential direction is scanned along the axis of the tube;
In each of the inspection signals, a feature amount calculating means for calculating a plurality of feature amounts related to amplitude or phase,
A plurality of feature quantities and distances to the respective objects have fourth information associated in advance, and using the fourth information and each feature quantity calculated by the feature quantity calculation means, the tube A gap measuring device comprising a gap amount determining means for obtaining a distance from the outer peripheral surface of each object to each of the objects or a sum of the distances. A gap measuring method for measuring a sum of distances from a peripheral surface of a pipe to a plurality of objects arranged along a circumferential direction of the pipe as a gap amount,
Obtaining an inspection signal when an eddy current flaw detection probe having no resolution in the circumferential direction of the tube is scanned along the axis of the tube;
Calculate the amplitude integral value of the inspection signal,
A gap measurement method for determining a gap amount corresponding to the amplitude integral value by using first information in which an amplitude integral value and a gap amount are associated in advance. When the sampling width of the inspection signal is constant, the integrated amplitude value is calculated instead of the integrated amplitude value,
The gap measurement method according to claim 6, wherein a gap amount corresponding to the amplitude integrated value is determined using second information in which an amplitude integrated value and a gap amount are associated in advance instead of the first information. In place of the amplitude integral value to calculate an average amplitude value of a predetermined fixed section length,
The gap measuring method according to claim 6, wherein the gap amount corresponding to the average amplitude value of the certain section length is determined using third information in which the average amplitude value of the certain section length and the gap amount are associated in advance. A gap measuring method for measuring distances from a peripheral surface of a pipe to a plurality of objects arranged along the circumferential direction of the pipe,
When scanning an eddy current flaw detection probe having no resolution in the circumferential direction along the axis of the tube, a plurality of inspection signals obtained by a plurality of different excitation frequencies are obtained,
In each inspection signal, a plurality of feature quantities related to amplitude or phase are calculated,
A plurality of the feature quantities and distances to the respective objects have third information associated in advance, and each of the objects from the outer peripheral surface of the pipe is used by using the third information and each of the feature quantities. Gap measurement method for obtaining the distance to the total or the total of the distance A gap measurement program for causing a computer to execute gap measurement that measures the sum of distances from the outer peripheral surface of a pipe to a plurality of objects arranged along the circumferential direction of the pipe as a gap amount,
Processing to obtain an inspection signal when an eddy current flaw detection probe having no resolution in the circumferential direction of the tube is scanned along the axis of the tube;
A process of calculating an amplitude integral value of the inspection signal;
A gap measurement program including a process of determining a gap amount corresponding to the amplitude integral value using first information in which an amplitude integral value and a gap amount are associated in advance. When the sampling width of the inspection signal is constant, a process of calculating an amplitude integrated value instead of the amplitude integrated value;
11. The method according to claim 10, further comprising: a process of determining a gap amount corresponding to the amplitude integrated value using second information in which an amplitude integrated value and a gap amount are associated in advance instead of the first information. Gap measurement program. A process of calculating an average amplitude value of a predetermined section length set in advance instead of the amplitude integral value;
The processing according to claim 10, further comprising: determining a gap amount corresponding to the average amplitude value of the certain section length using the third information in which the average amplitude value of the certain section length and the gap amount are associated in advance. Gap measurement program. A gap measurement program for causing a computer to execute gap measurement for measuring distances from a peripheral surface of a pipe to a plurality of objects arranged along the circumferential direction of the pipe,
A process of acquiring a plurality of inspection signals obtained by a plurality of different excitation frequencies when an eddy current flaw detection probe having no resolution in the circumferential direction is scanned along the axis of the tube;
In each of the inspection signals, a process of calculating a plurality of feature amounts related to amplitude or phase,
A plurality of the feature quantities and distances to the respective objects have third information associated in advance, and each of the objects from the outer peripheral surface of the pipe is used by using the third information and each of the feature quantities. And a clearance measurement program including a process for obtaining the total distance.

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