JPS6411143B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to an ultrasonic flaw detection method, particularly an ultrasonic pulse flaw detection method. [Prior art] Ultrasonic flaw detection using the pulse method has various advantages such as ease of handling.
It is widely used for detecting defects in steel materials. A conventional ultrasonic pulse flaw detection method for detecting defects in steel materials will be explained below. In FIG. 1, a reflector (defect) 12 is present in an object (steel material) 10 to be inspected. The probe 14 is connected to the scanning line L ₁ shown in FIG.
L ₂ , L... _j , L _j+1 , ... An ultrasonic pulse beam is transmitted toward the object to be inspected 10 at wave transmitting/receiving positions determined at predetermined intervals on the object 10 to be detected. The reflected pulse beam from the reflector 12 can be received. In this example, it is assumed that the object to be inspected 10 is plate-shaped, and its width direction is y as shown in FIGS. 1 and 2.
The length direction is defined as the x direction, and the depth direction is defined as the z direction. As shown in FIG. 1, the ultrasonic pulse beam is transmitted from the probe 14 toward the object to be inspected 10 at a refraction angle θ, and its waveform is rectangular as shown by T in FIG. The beam spread at that time is as shown in FIG. h is the strength of the probe sound field, and δ is the deflection angle of the central beam. In order to detect the reflector 12 present in the object to be inspected 10, the probe 14 moves along the scanning line L in FIG. Ultrasonic beams are transmitted and received at the location. At this time, the waveform of the reflected pulse received by the probe 14 is triangular as shown in FIG. 3, and at the transmitting and receiving position U _i on the scanning line L _j , the reflected pulse becomes R _ij , At U _i+1 , it becomes R _i+1,j , and the peak values of the reflected pulses R _ij and R _i+1,j are respectively
P _ij , P _i+1,j . In this example, the waveform of FIG. 3 is displayed on the A scope, and this display provides information regarding the reflector 12,
For example, its position and size can be determined as follows. That is, the display screen of the A scope is observed while repeatedly moving the probe 14, and the change in the peak value P of the reflected pulse R at that time is observed. At this time, the peak value P is maximum (P _i+1,j in Figure 3)
Then, as shown in FIG. 1, the probe 14 is located at the transmitting/receiving position where its center beam irradiates the reflector 12, so the position y _i+1 and the propagation time at this time are
The coordinates where the reflector 12 is located are determined from t _i+1,j ,
Further, the size of the object to be inspected 12 is determined from the peak value P _i+1,j . As described above, according to the conventional method, the object to be inspected 1
It is possible to know the position and size of the reflector 12 that exists within 0. [Problem to be Solved by the Invention] However, conventionally, when there are multiple reflectors inside the object to be inspected, the peak value envelope 200 of the reflected pulse (see FIG. 3) is drawn on multiple A scopes. Therefore, it was difficult to detect the maximum peak value of the reflected pulse. For this reason, in the past, the probe had to be moved repeatedly to get an idea of which reflector was causing the damage, which made it difficult to obtain accurate information about the reflectors that existed inside the body being inspected, and because of this it took a long time to move the probe. There was a problem that required . In addition, in an ultrasonic flaw detector that automatically reads reflector information, the strength h of the probe sound field shown in Fig. 4 is a function of the declination angle δ of the central beam. Although the position of the reflector is determined, there are disadvantages in that this requires deep specialized knowledge and the calculation formula is extremely complex, requiring a long calculation time. As explained above, the conventional ultrasonic pulse flaw detection method has a drawback in that when a plurality of reflectors are present in the body to be inspected, information regarding the reflectors cannot be obtained accurately and easily. The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to accurately and easily obtain information regarding the reflectors even when a plurality of reflectors exist inside the body to be inspected. The purpose of the present invention is to provide an ultrasonic pulse flaw detection method that can be used. [Means for Solving the Problems] In order to achieve the above object, the present invention provides a probe for transmitting and receiving waves at respective wave transmitting/receiving positions determined at predetermined intervals on a plurality of scanning lines aligned on the surface of an object to be inspected. The ultrasonic pulse beam is transmitted toward the object to be inspected and the reflected pulse beam is received from the reflector inside the object, and information on the transmitting/receiving position of the probe and the waves of each reflected pulse are obtained. In an ultrasonic pulse flaw detection method for obtaining information about the reflector based on a high value,
Each ultrasound beam is transmitted and received by setting the interval between each transmission/reception position and the interval between each scanning line so that the adjacent ultrasound beams overlap sufficiently on the scanning line and between the scanning lines. The difference in the reflected pulse beam path length at the transmitting and receiving positions is predetermined in the interval between the two transmitting and receiving positions, and the ratio of the distance between the probes Δd to the beam path difference Δl of the reflected pulses that should be in the same group under that condition is Δl/ The difference in reflected pulse beam path length at two adjacent transmitting/receiving positions between scanning lines that is less than or equal to the value multiplied by an intra-line grouping constant which is Δd is predetermined as the scanning line interval,
Ratio of the distance between the probes Δd and the beam path difference Δl of the reflected pulses that should be in the same group under that condition Δl/Δd
A reflected pulse group that satisfies the condition of being less than or equal to the value multiplied by the inter-line grouping constant is determined to be obtained from the same reflector, and the peak value of the reflected pulse group obtained by this determination and the reflected pulse The present invention is characterized in that the center position and size of the reflector are detected based on the position information of the probe for the group. [Operation and Examples] The operation and preferred embodiments of the present invention will be described below based on the drawings. FIG. 5 shows a block configuration of an ultrasonic flaw detector to which the method of the present invention is applied. In the figure, the probe 14 is controlled to move as shown in FIG. 2, and its position is detected by a position detector 20. The probe 14 is connected to a wave transmitting/receiving circuit 22, and the wave transmitting/receiving circuit 22 transmits an ultrasonic pulse beam to the probe 14 and sends an ultrasonic pulse beam to the reflector 12.
It is possible to receive the reflected pulse beam from the The wave transmitting/receiving circuit 22 is supplied with the reflected pulse R received by the probe 14, the wave transmitting/receiving circuit 22 can detect the reflected pulse R, and the digitizing circuit 24 can detect the reflected pulse R. can be digitized and output. The output data of the position detector 20 and the digitization circuit 24 are supplied to a data memory 26,
The data memory 26 can store the position (x, y) of the probe 14 detected by the position detector 20 and the reflected pulse R. In addition, the data memory 26
The refraction angle θ of the probe 14, the thickness H of the object to be inspected 10, the propagation velocity V of the ultrasonic beam, and an intra-line grouping constant C ₁ and an inter-line grouping constant C ₂ , which will be described later, are stored in . There is. This data memory 26 stores the position (x, y) of the probe 14 and the reflected pulse R received at that position.
The wave height value P and the propagation time t of the reflected wave of the wave height value P
are stored in a sequential array. The arithmetic processor 28 can appropriately select and read out the contents of the data memory 26 and perform processing according to a series of flowcharts shown in FIGS. 6, 7, and 8. The operation of the preferred embodiment of the present invention will be described in detail below. The probe 14 scans each scanning line L ₁ , L ₂ ... L _j , L _j+1 from the starting point (x ₀ , y ₀ ) to the ending point (x _n , y _o ) in FIG.
. . . During this movement, the ultrasonic beam is transmitted and received at each transmission and reception position on each line L. In the present invention, the interval between each line L and each transmitting/receiving position are set so that adjacent ultrasonic beams sufficiently overlap. Therefore, in FIG. 2, adjacent ultrasound beams on each line L (x value is constant) overlap sufficiently, and between each line L (y value is constant) adjacent ultrasound beams overlap sufficiently. are overlapping. As described above, when scanning is performed such that the ultrasonic beams sufficiently overlap on each line L and between each line L, the reflected pulse R and the transmission/reception position at that time are stored in the data memory 26. In this embodiment, the arithmetic processor 28 first performs the flowchart process shown in FIG. 6, then the flowchart process shown in FIG. 7, and finally the flowchart process shown in FIG. In other words, after completing the flaw detection of the object to be inspected by the flaw detection equipment, all transmitted waves,
After the reflected waves and the probe position are stored in the data memory, arithmetic processing is performed to detect and display the position and size of the reflector. In the flowchart of FIG. 6, a determination operation is performed in which the reflected pulses R within the same line L are grouped according to the reflectors 12 present in the object 10 to be inspected. In step 100 of FIG. 6, the wave transmitting/receiving position (probe position) y _ij (the y coordinate _of U _{ij is}
Express the coordinates as x _ij . When the problem is in the y direction, the position is represented by the y coordinate, and when the problem is in the x direction, the position is represented by the x coordinate. ) is read out, and in the next step 101, the reflected pulse R at the transmitting/receiving position (y _i+1,j ) on the same scanning line L _j is read out. The probe state at this time is 9th.
Figure 10 shows the waveform of the reflected pulse R when the probe 14 is at the transmitting/receiving position U _ij , and the waveform of the reflected pulse R when the probe 14 is at the transmitting/receiving position U _i+1,j. The waveform of pulse R is shown in FIG. Therefore, in the case of FIG. 10, reflected pulses from a plurality of reflectors at different positions, for example R _ij,1 , R _ij,2 ,
A reflected pulse train R of R _ij,3 is obtained, which in the case of FIG. 11 is similarly reflected from a plurality of reflectors (not necessarily the same as in the case of R _ij ), e.g.
Reflected pulse train R of R _i+1j,1 , R _i+1j,2 , R _i+1j,3 , R _i+1j,4
are obtained and read out. In step 102, adjacent wave transmitting/receiving positions U _ij ,
From the position information obtained in steps 100 and 101 for U _i+1,j, the amount of movement Δy of the probe 14 is determined by the following (1)
It is determined by the formula. Δy=y _i+1,j −y _ij ...Equation (1) In the next step ₁₀₃ , the first
The propagation time difference between the pulse R _ij,1 and the reflected pulse train R _i+1,j is determined by the following equation (2). Δt _n = t _i,1 −t _i+1,n ...Equation (2) However, m = 1 to n, n is the number of pulses of the pulse train R _i+1,j This Δt _n is the number of pulses transmitted at a certain position. It shows the difference between the propagation time of each of the multiple reflected waves of the ultrasonic beam emitted at a distance of Δy from that position, and the propagation time of each of the multiple reflected waves of the ultrasonic beam emitted at a position Δy away from that position. As described above, in order for the two compared reflected waves to be reflected from the same reflector, this Δt _n must be less than or equal to a certain value. In the next step 104, the amount of movement Δy of the wave transmitting/receiving position obtained by the above equations (1) and (2) and the reflected pulse R are calculated.
Based on the propagation time difference Δt, it is determined whether the reflected pulses R are from the same reflector 12 within the same line L _j . The above determination is obtained by the following equation (3). 0≦W _i ≦C ₁ Δy Equation (3) C ₁ : Intra-line grouping constant Next, the meaning of the above Equation (3) will be explained. In Fig. 9, the transmitting and receiving positions are moved on the same scanning line L, and the ultrasonic beam is incident at an oblique angle at a refraction angle θ, _but the beam spread range (, _i and
The range surrounded by B _i ) and the beam spread range at the transmitting/receiving position U _i+1,j ( _i+1,j , the range where the range surrounded by _i+1 and _i+1,j , _i+1 overlap) (, _i+1 and, _i
), that is, the first pulse R _ij of the reflected pulses R _ij , R _i+1, j from the same reflector 12 within the range where the ultrasonic beams overlap at the transmitting/receiving positions U _{ij , U i+} 1j _,1 , R _i+1j,1, the beam path lengths are l _ij , l _i+1j . At this time, it is understood that when the movement amount Δy is determined by equation (1), the difference between the beam path lengths l _ij and l _i+1j , that is, the beam path difference W _i falls within the range of the following equation. O≦W _i ≦Δy ... Equation (4) Therefore, when the condition of Equation (4) above is satisfied, it can be treated as a reflected pulse R from the same reflector 12. In the present invention, in view of the fact that if only the condition of formula (4) above is applied, the range of the same reflector 12 becomes wider due to the spread of the ultrasonic beam, and the resolution of position evaluation deteriorates, As shown in the formula, the amount of movement Δy
is multiplied by the intra-line grouping constant _C1 to narrow down the range that is determined to be the same reflector 12. The above in-line grouping constant C ₁ is the probe 14
The constant C 1 should be determined by taking into account the characteristics of , the refraction angle θ, the thickness H of the object to be inspected 10, etc. In this embodiment, this constant C ₁ is determined by the following equation (5). C ₁ = Δl/Δd ... Equation (5) Δd: Distance between probes where at least a portion of the ultrasound beams overlap Δl: The reflected waves of ultrasound beams emitted at an interval of Δd are the same This is the beam path difference between the reflected waves that are reflected from the reflector and should be determined to belong to the same group, and Δl≦Δd. Note that in Equation (5), the position evaluation resolution can be changed by arbitrarily selecting Δd and Δl. If we rewrite the above equation (5), Δl=C ₁ Δd. Since the amount of movement of the probe during flaw detection is determined so that the ultrasonic beams overlap, Δd=Δy. Furthermore, when the probe movement amount is Δd (=Δy), the beam path difference between the reflected waves considered to be reflected waves from the same reflector is less than Δl, so the reflected pulse train R _ij
Let W _i be the beam path difference between the first pulse R _ij,1 and the m-th pulse R _{i+1, j,n of the reflected pulse train R i+1,j} , then Δl≧
This is the condition that W _i is a reflected wave from the same reflector. Then, W _i ≦∆l=C ₁ ∆d=C ₁ ∆y O≦W _i /V≦C ₁ ∆y/V W _i /V is ∆t _n from the second equation, so O≦∆t _n ≦C ₁ ∆y/ V...Equation (6) is obtained, and in step 104, when this condition is satisfied, it is determined that the pulses are reflected from the same reflector 12. In the next step 105, intra-line grouping data G _ij grouped for each reflector 12 in each line L _i is stored in the data memory 26 . In step 106, all pulses R between the pulse trains R _ij and R _i+1,j are grouped for each reflector 12. For example, pulse R _ij,1 and pulse R _{ij+1,1 to 4} are executed, then pulse R _ij2 and pulse
Processing proceeds sequentially, with R _{ij+1,1 to 4} being executed. Then, in step 107, the above-mentioned intra-line grouping determination is performed for the total reflection pulses R of each line _Lj , and in step 108, the intra-line grouping determination is performed for all lines L. When the intra-line grouping determination of FIG. 6 is executed as described above and the reflected pulses R are grouped for each reflector 12 within each line L, the flowchart of FIG. 7 is executed. In the flowchart of FIG. 7, grouping determination of reflected pulses R is performed between each line. This judgment is made in the x direction, whereas the judgment in Fig. 6 was made in the y direction. Fig. 12 shows the cross section of the flaw detection state at this time, and Fig. 13 shows the The waveform of the reflected pulse R when the probe 14 is at the transmitting/receiving position U _ij is shown in FIG. 14, and the reflected pulse R when the probe 14 is at the transmitting/receiving position U _ij+1 is shown in FIG.
The waveform of is shown. In step 109 of FIG. 7, grouped data G _ij of line L _j is read out, and then in step 110, grouped data G _ij+1 of line L _j+1 adjacent to line L _j is read out. In the next step 111, these grouped data
G _ij , G _ij+1 wave transmitting/receiving position x _ij , moving amount Δx of x _ij+1 is the
It is obtained from equation (7). Δx＝x _ij+1 −x _ij ...Equation (7) Furthermore, in step 112, the grouped data
The propagation time difference Δt between the reflected pulses R _ij (see FIG. 13) and the reflected pulses R _{ij +1} (see FIG. 14) of G _ij and G ij+1 is obtained from the following equation (7). Δt=t _ij −t _ij+1 ...Equation (8) Here, the in-line transmission/reception positions y _ij and y _ij+1 of the reflected pulses R _ij and R _ij+1 are at the same position in the x direction. be. In addition, in this example, the above grouped data
If the same wave transmitting/receiving position does not exist at G _ij and G _ij+1 , it is determined that the reflector 12 is a different reflector 12 . In the next step 113, the reflected pulse R from the same reflector 12 between the lines L is calculated using the propagation time difference Δt and the movement amount Δx of the reflected pulse R obtained by the above equations (7) and (8). It is determined whether or not. The above judgment made in step 113 is made in the same manner as the judgment regarding the inside of line L, and will therefore be briefly explained below. FIG. 12 is a cross-sectional view regarding the scanning lines L _j and L _j+1 , and FIG. 12 is a cross-sectional view of the scanning lines L j and L j+1, and _FIG .
A case is shown in which the positions of x _ij+1 in the y direction are the same. Similar to the above-mentioned intra-line grouping, here, the range where the ultrasound beams overlap at the transmitting/receiving positions U _ij , U _ij+1 (the range surrounded by _i+1 and _i )
The reflected pulse R _ij of the same reflector 12 existing within
R _ij+1 is targeted for grouping determination, and in order to further improve the resolution of position estimation, an inter-line grouping constant C ₂ is used that determines the range of the beam path difference W _i from the movement amount Δx. Expressing this in a formula, O≦W _j ≦C ₂ Δx ...Equation (9). Note that the reflected pulses R _ij at the positions U _ij , U _ij+1 ,
The beam path difference W _j of R _ij+1 is smaller when compared with the case of in-line determination because both ultrasonic beams are parallel. If we rewrite the above equation (9), we get the following equation (10). O≦∆t≦C ₂ ∆x/V ...Equation (10) In the next step 114, each reflector 1
The grouped data G _i grouped by 2 is stored in the data memory 26, and in step 115,
This inter-line grouping determination is performed for all intra-line grouping data. When grouping within a line and between lines is determined as described above, the flowchart of FIG. 8 is executed, and the position and size of each reflector 12 is determined. In step 116 of FIG. 8, the line-to-line grouping data G _i is read out, and in step 117, if the number of reflected pulses R of the grouping data G _i is less than the reference number N, this is invalidated as a pulse due to noise or the like. Processing is executed. Then, in step 118, the above grouped data
Using G _i , the center position (X, Y, Z) of the reflector can be determined from the reflected pulse R having the maximum peak value using the following equation. X=x...Equation (11) Y=l sinθ+y...Equation (12) Z=l cosθ...Equation (13) In the above equation, x and y are the transmitted and received waves at which the maximum peak value was detected. are the x and y coordinates of the position,
l is the beam path degree obtained from the propagation time and propagation velocity. Also, in step 119, the size of the reflector is determined. That is, the positions of both ends of the reflector are determined from the reflected pulses R at both ends of a predetermined size of the peak value distribution using equations (11) to (13), and the magnitude thereof is determined. Table 1 shows an example of the calculation results of ultrasonic flaw detection performed by applying the present invention. This ultrasonic flaw detection
This was done with the intra-line grouping constant C ₁ = 0.8, the inter-line grouping constant C ₂ = 1.0, and Δd = 3.0 mm, and the group number of the reflected waves formed by the intra-line and inter-line grouping processing is Each number represents a detected reflector. For each reflector,
XMAX, YM, is the time at which the maximum wave height value P is detected
The coordinate and y-coordinate values are shown, and MAX% shows the maximum wave height value in DAC%. Also, x ₁ ~ x ₆ , y ₁ ~ _{y 6}
As shown in Fig. 15, is the maximum wave height value detection position A
The distance on the x-axis and y-axis from the origin, and the peak value of the reflected wave belonging to each reflector is DAC%
, which shows distances of 20, 50, 100, 100, 50, and 20 in order. The size of the reflector is determined from this value. In addition, W ₁ to _{W 6} are wave height values in the y direction of 20,
The beam path differences of the reflected waves are shown as 50, 100, 100, 50, and 20. Figure 16 shows the grouped data

〔Effect of the invention〕

As explained above, according to the present invention, reflected pulse data is grouped by reflector with high position evaluation resolution using the intra-line grouping constant and the inter-line grouping constant. The position and size of the reflector in the arbitrary wave height distribution can be easily and accurately evaluated in a short time. In particular, the present invention is effective for an ultrasonic flaw detection device that regularly scans a probe for the purpose of scanning. Note that it is also suitable to use the present invention in an ultrasonic diagnostic device or the like.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of the operation of the conventional ultrasonic pulse flaw detection method, Figure 2 is a scanning locus diagram of the probe, and Figure 3 is A scope showing the waveforms of ultrasonic pulses and reflected pulses in the conventional method. 4 is a spread characteristic diagram of an ultrasonic pulse beam, FIG. 5 is a block configuration diagram of an ultrasonic flaw detection apparatus to which the ultrasonic flaw detection method according to the present invention is applied, FIGS. 6, 7, 8 is a flowchart of the arithmetic processor in FIG. 5, FIG. 9 is an explanatory diagram of the operation of the device in FIG. Figure 12 is a waveform diagram of the reflected pulse. Figure 12 is an explanatory diagram of the operation of the X-direction grouping of the device in Figure 5. Figures 13 and 14 are waveform diagrams of the ultrasonic pulse and reflected pulse in Figure 12. Figure 15. is the first
FIG. 16 is an explanatory diagram of the symbols shown in the table, and FIG. 16 is a developed diagram showing the results shown in Table 1 developed on a plane. 10...Test object, 12...Reflector, 14...
Probe, 20... position detector, 22... wave transmitting/receiving circuit, 24... digital circuit, 26... data memory, 28... arithmetic processor.

Claims (1)

[Claims] 1 Transmission of ultrasonic pulse beams toward the object to be inspected using a probe at transmitting/receiving positions determined at predetermined intervals on multiple scanning lines aligned on the surface of the object to be inspected, and ultrasonic pulse beams that are present inside the object to be inspected. In an ultrasonic pulse flaw detection method in which a reflected pulse beam is received from a reflector and information about the reflector is obtained based on the transmitting/receiving position information of the probe and the peak value of each reflected pulse, Each ultrasonic beam is transmitted and received by setting the interval between each transmitting/receiving position and the interval between each scanning line so that the ultrasound beams overlap sufficiently on the scanning line and between the scanning lines, and two adjacent transmitting/receiving waves on the scanning line are The difference in the path of the reflected pulse beam at the position is determined in advance by the distance between the transmitting and receiving positions, and is determined by the ratio Δl/Δd of the distance between the probes Δd and the beam path difference Δl of the reflected pulses that should be in the same group under that condition. The difference in reflected pulse beam path length at two adjacent transmitting/receiving positions between scanning lines that is less than or equal to a value multiplied by a certain intra-line grouping constant is predetermined as the scanning line interval, and the inter-probe distance Δd and its conditions A group of reflected pulses that satisfy the condition that the beam path difference Δl of the reflected pulses that should be in the same group is less than or equal to the value multiplied by the inter-line grouping constant, which is Δl/Δd, are considered to be obtained from the same reflector. and detecting the center position and size of a reflector based on the peak value of a group of reflected pulses obtained by the determination and position information of a probe regarding the group of reflected pulses. Pulse flaw detection method.