JP2859659B2 - Ultrasonic flaw detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Industrial Field of the Invention The present invention relates to an apparatus for flaw-detecting an object with an ultrasonic probe by rotating the object having a substantially cylindrical shape.

B. Conventional technology Water shown in the Journal of the Japan Society of Mechanical Engineers, vol. 90, No. 826, p5-9 (conventional document 1) and Nondestructive Inspection Vol. 37, No. 2, p152-153 (conventional document 2) An automatic immersion flaw detection method is known. In this method, an ultrasonic probe is scanned on the surface of a subject in water in which the subject is immersed for the purpose of precise ultrasonic testing. In this automatic water immersion flaw detection method, in order to know the size and position of a flaw (defect) accurately, the distance between the ultrasonic probe and the subject is kept constant, and the direction of the center axis of the ultrasonic beam is Must be matched with the normal direction of the surface of the subject.

The device disclosed in the related art 1 can detect an object having a flat surface, but when the surface is curved, the direction of the center axis of the ultrasonic beam can be made to coincide with the normal direction of the surface of the object. Because of the difficulty, it was not possible to detect flaws on a subject having a curved surface.

On the other hand, the apparatus disclosed in the prior art document 2 first measures the shape of the entire subject using a laser range finder, and then scans the ultrasonic probe using the shape data. An object having a surface shape of can be detected.

C. Problems to be Solved by the Invention However, it is impossible for the conventional apparatus 2 to detect a flaw in a columnar subject as it is.

Therefore, as shown in FIG. 20, when the subject W is a cylinder, the subject W is rotated by the rotary driving device 101, and the ultrasonic probe moves in the X, Y, and Z axis directions by the driving device 102. Using the probe 103, flaw detection is performed in one of the following procedures, for example.

(1) The X, Y, and Z driving devices 102 are moved, and the ultrasonic probe is moved in the direction normal to the surface of the subject at the scanning start end (for example, point A in FIG. 20).
Match 103. The X-axis is driven to move the ultrasonic probe 103 to the end of scanning (point B in FIG. 20) to perform flaw detection. The subject W is rotated by a small angle using the rotation drive device 101. The flaw detection is performed by repeating the operation of driving the X axis to move the ultrasonic probe 103 to the point A.

(2) After aligning the ultrasonic probe 103 in the normal direction of the surface of the subject, the flaw detection is performed while rotating the subject W by one rotation. The ultrasonic probe 103 is minutely moved in the X-axis direction. The operation of detecting the flaw while rotating the subject W once again is repeated.

However, if the center of the subject W and the center of rotation are slightly deviated, or if the subject W is a rotating body having a complicated shape, it is impossible to detect a flaw.

It is a technical object of the present invention to enable flaw detection of a rotating body having a complicated shape to be performed in parallel with shape measurement.

D. Means for Solving the Problems To be described with reference to FIG. 1 which is a diagram corresponding to claims and FIG. 2 and FIG. 3 showing one embodiment of the present invention, the present invention is described in a predetermined three-dimensional coordinate system. The present invention is applied to an ultrasonic flaw detector that searches for a flaw in the subject W mounted rotatably about a predetermined rotation axis. The supporting unit 8D movably provided in the three-dimensional coordinate system, the driving device 504 (1, 3, 6) for moving the supporting unit 8D along the three-dimensional coordinate system, and the rotating subject W The ultrasonic probe 502 provided on the support portion 8D so as to emit an ultrasonic flaw detection signal toward the
(9), a distance detection probe 503 (10) provided on the support portion 8D so as to scan on a scanning run preceding the ultrasonic probe 502 (9), and a distance detection probe Child 503 (10) -3
Position detecting means 505 for detecting a position in the three-dimensional coordinate system; and distance detecting means 503 for calculating a distance from a distance measuring point on the subject W based on a signal detected by the distance detecting probe 503 (10). (11) Based on the detection result of the distance detecting means 503 (11) and the detection result of the position detecting means 505, the position information of the distance measurement point on the subject W is calculated, and the ultrasonic The position and orientation of the probe 502 (9) are calculated, and based on the calculation results, the ultrasonic test signal is input so that the ultrasonic flaw detection signal enters the subject W at a predetermined angle from a predetermined distance.
The signal for controlling the position and orientation of (9) is transmitted to the driving device 50.
4 (1, 3, 6), the position and orientation calculation means 506, the circumferential scanning of the subject W by the distance detecting means 503, and the circumferential flaw scanning of the subject W by the ultrasonic probe 502 (9). The above-mentioned technical problem is solved by providing a control unit 507 for outputting a signal for causing the driving device 504 (1, 3, 6) to operate in parallel.

The apparatus according to claim 2, further comprising a storage unit configured to divide the surface of the subject into small regions divided by the rotation angle and the position in the rotation axis direction, and to store only one piece of position information calculated for each small region,
The position and orientation of the ultrasonic probe are calculated based on position information in a small area corresponding to each circumferential flaw detection scan.

E. Action The subject W is rotated by the rotating means 501 around a predetermined time. The distance detecting unit 503 measures a distance to a distance measuring point on the rotating subject. Until the flaw detection operation is started, for example, the shape of the object is scanned by scanning the surface of the object while controlling the position and orientation of the distance detecting means 503 based on the known shape of the object. If the surface shape of the subject is not known, scanning may be performed along the surface with the distance detecting means 503. The position and orientation of the ultrasonic probe 502 are calculated based on the position information of the measurement points of the subject W thus measured, and the ultrasonic probe 502 is controlled to such a position and orientation. In this state, an ultrasonic flaw detection signal is emitted toward the subject W at a desired incident angle, and the subject W is flaw-detected by a reflected wave therefrom.

In parallel with this flaw detection operation, the distance detecting means 503 detects a distance to a shape measurement point on a line preceding the flaw detection scanning line. Based on the result of the preceding shape measurement, the position and orientation when the ultrasonic probe 502 next performs flaw detection scanning on the scanning line or on a line near the scanning line are calculated.

In the apparatus according to the second aspect, the position and orientation for the flaw detection operation are calculated from the position information in the small area. Therefore,
The position and orientation of the ultrasonic probe 502 can be calculated so as to perform flaw detection on a scan line different from the shape measurement scan line on the subject surface.

F. Embodiment -First Embodiment- [Explanation of the Entire Apparatus] The entire flaw detection apparatus to which the present invention is applied will be described with reference to FIGS.

As shown in FIGS. 2 (a) and 2 (b),
For example, a gate-shaped traveling body 2 that travels in the X-axis direction by an X-axis driving device 1 and a Y-axis traveling body 4 that travels on the portal traveling body 2 in a Y-axis direction by a Y-axis driving device 3, A Z-axis arm 7 that moves up and down in the Z-axis direction by a Z-axis driving device 6 is provided on a bracket 5 integrated with the Y-axis traveling body 4. Z-axis arm 7
A robot wrist 8 is attached to a lower end of the robot. Then, the columnar subject W is placed on the turntable TB, and is rotatable around the rotation center in the Z-axis direction.

As shown in FIG. 3, the wrist portion 8 includes a β-axis rotation driving device 8B provided in a housing 8A fixed to the lower end of the Z-axis 7, and a rotation shaft of the β-axis driving device 8B. A bracket 8C, and an α-axis rotation driving device 8E mounted on the bracket 8C and having a bracket 8D mounted on a rotating shaft, and one ultrasonic probe for detecting a flaw of the subject W on the bracket 8D. The touch element 9 and one distance sensor unit 10 for detecting the surface position of the subject W are mounted in a positional relationship separated by L in the Z-axis direction. The distance sensor unit 10 can be composed of, for example, an ultrasonic probe, and its detection signal is input to a distance detection circuit 11 shown in FIG.

As shown in FIG. 4A, the distance detection circuit 11 is an ultrasonic probe.
It comprises a transmitter 11a for transmitting an ultrasonic signal to 10, a receiver 11b for receiving an ultrasonic signal reflected from the subject W, and a timing circuit 11c. The clock circuit 11c measures the time interval between the transmission signal from the transmitter 11a and the ultrasonic reflection signal from the surface of the subject W, and outputs the result to the control device 12.

Here, the time intervals t _0, when the underwater sound speed to is V, the distance M between the ultrasonic probe 10 and the object W surface is calculated by _{M = Vt 0/2 ... (} 1).

2, the control device 12 is a microprocessor including a CPU, a ROM, a RAM, and the like.
, And the SW indicating the time interval from the distance detection circuit 11 are input, and are incorporated in the X, Y, Z, β, and α axis driving devices 1, 3, 6, 8B, and 8E. Signal SX, S from a position or angle detector such as a potentiometer (not shown)
Y, SZ, Sβ, and Sα are also input. 13X, 13Y, 13Z, 13α, 13β are servo amplifiers for driving each axis drive unit 1, 3, 6, 8B, 8E, 1
4 is an input device for inputting a flaw detection range and the like, and 15 is a recorder for recording flaw detection results. The driving device for each axis has, for example, an electric motor. Reference numeral 16 denotes a drive device for rotating the turntable TB, and controls a rotation angle of the turntable TB in accordance with a command signal from the control device 12. Reference numeral 17 denotes an angle detector built in the driving device 16, and the angle signal Sγ is input to the control device 12.

[Calculation Process of Control Device 12] In the present embodiment, the center position of the turntable TB is set as the coordinate origin O, and γo, γa, and Dl are defined as shown in FIG. 4B. Here, γo is an angle between the detection direction of the distance sensor unit 10 at an arbitrary time and the X axis, and γa is a measurement point and a coordinate origin at which the ultrasonic signal from the distance sensor unit 10 hits the surface of the subject W at that time. The angle between the line connecting O and the detection direction of the distance sensor unit 10, and Dl is the distance between the measurement point indicated by (Xa, Ya, Za) and the coordinate origin.

Main Flowchart FIG. 5 is a main flowchart of the arithmetic processing executed by the control device 12.

First, in step S10, initial processing such as a memory is performed, and then, in step S20, the ultrasonic probe 10 is positioned at a control start position. FIG. 6 shows a state in which the positioning operation has been completed. Then, the process proceeds to the shape measuring operation in step S30, and the object W known in advance from design specifications or the like is used.
The ultrasonic probe 10 based on the surface shape data of the subject W
The turntable TB is rotated while being directed in the normal direction on the measurement point, and the surface of the subject W is rotationally scanned. This rotational scanning is performed a plurality of times at a predetermined pitch in the Z direction, and at least the surface shape data in the range of the distance L shown in FIG. 3 is collected in advance of the flaw detection in more detail than the design data given in advance. That is, the signals SX, SY, SZ, Sα, S from the detection of the position or angle built in the square axis driving device
The calculation is performed for each scanning line based on β and the signal SW from the ultrasonic probe 10. The detailed procedure is shown in FIG.

Next, when this shape measurement operation is completed, the process proceeds to step S40, and the procedure proceeds to a flaw detection operation procedure. Here, based on the surface shape data of the subject W obtained in step S30, position information at a plurality of control points for causing the ultrasonic probe 9 to face a flaw detection point on the subject W is calculated, Ultrasonic probe 9
Captures an ultrasonic inspection signal from the ultrasonic probe 9 into the control device 12 at a timing controlled by each control point. Further, during this flaw detection operation, the distance between the ultrasonic probe 10 and the subject W is calculated by the ultrasonic probe 10 scanning several lines (distance L in FIG. 3) ahead of the ultrasonic probe 9. Then, the surface shape data of the preceding scan line is collected together with the position data from the position or angle detector described above. When the ultrasonic probe 9 reaches the scanning run, position information of the control point of the ultrasonic probe 9 corresponding to the flaw detection point on the preceding scan line is calculated from the collected data, and the position of the line is calculated. Perform flaw detection.
In the detailed procedure, when the flaw detection operation shown in FIG. 12 is completed, the ultrasonic probe 9 is moved to the end position in step S50, and the process ends.

 Next, the shape measurement operation and the flaw detection operation will be described in detail.

Flowchart of Shape Measurement Operation FIG. 7 shows details of the shape measurement operation in step S30.

First, in step S31, a command value for one rotation of each drive device (hereinafter, referred to as each axis command value) is fetched and stored in a memory. Each axis command value for this one rotation is expressed by Equation (2)
This is a data group shown in (6).

_{Xr = (Xs, X 1,} ......, Xn, ......, Xmax) ... (2) Yr = (Ys, Y 1, ......, Yn, ......, Ymax) ... (3) Zr = (Zs, Z ₁ ,..., Zn,..., Zmax) (4) αr = (αs, α ₁ ,..., Αn..., Αmax) (5) βr = (βs, β ₁ ,. ......, βmax) ... (6) γr = (γs, γ 1, ......, γn, ......, γmax) ... (7) where, .gamma.r is the angle command value of the turntable TB.

Since each axis command value does not require more precision than a command value at the time of a flaw detection operation described later, the position of a representative point on a single rotation scan line is obtained based on the design data of the subject W, and interpolation is performed between the positions. Required.

Next, in step S32, positioning is performed to the scanning start point. That is, Xr = Xs, Yr = Ys, Zr = Zs, αr = αs, βr = βs,
γr = γs (= 0 °), and each axis is positioned. After this positioning is completed, the variable N is set to 1 in step S33, and the process proceeds to step S34 to output the subject rotation command.
The timer interrupt program shown in the figure operates at regular intervals.

In FIG. 8, first, in step S341, it is determined whether or not the command is a subject stop command. First moves to step S342 because it is subject rotation command, N-th command value, i.e. Xr = X ₁ which is a command value of _{N = 1, Yr = Y 1} , Zr = Z 1, αr = α 1, βr =
β ₁ and γr = γ ₁ are taken in. Then, the signals SX, SY, SZ, Sα, Sβ, Sγ indicating the current position of each axis described above are fetched from each detector, and the current values X ₀ , Y ₀ , Z ₀ , α ₀ , β ₀ , seeking gamma _0, the current axis X ₀ of the command value and the respective _{axes, Y 0, Z 0, α} 0, β 0, calculates the difference between the gamma _0, performs so-called servo operations such multiplying the coefficient in the deviation , And outputs the calculation results to the servo amplifiers 13X to 13β, 13T in FIG. Thereby, the distance sensor unit 10 moves to the commanded first position. At this time, the ultrasonic probe 10 faces in the normal direction of the surface of the measurement point on the subject W. And step S3
In step 43, the distance la between the ultrasonic probe 10 and the surface of the subject W is fetched by a signal SW from the distance detection circuit 11. Next, in step S344, the signals SX, S from the detector of each axis driving device
Y, SZ, Sα, Sβ, Sγ are fetched, and the current values X ₀ , Y ₀ , Z ₀ , α ₀ , β ₀ , γ ₀ of each axis are obtained in step S345, and the ultrasonic beam of the ultrasonic probe 10 is obtained. Then, the position (Xa, Ya, Za) of a point on the surface of the subject W to which the ultrasonic beam is applied and the angle γa of the turntable TB at the point where the ultrasonic beam is applied are calculated. Here, Xa to Za and γa are calculated from the following relational expressions.

Xa = f ₁ (X ₀ , Y ₀ , Z ₀ , α ₀ , β ₀ , la)… (7) Ya = f ₂ (X ₀ , Y ₀ , Z ₀ , α ₀ , β ₀ , la)… ( 8) Za = f ₃ (X ₀ , Y ₀ , Z ₀ , α ₀ , β ₀ , la) (9) γa = f ₄ (Xa, Ya, γ ₀ ) (10) The flow Dl of the point on the surface of the subject w from the Z-axis coordinate axis is calculated by the following equation.

Next, in step S346, equations (7) to (10),
The surface position of the subject W obtained in (100) is stored. One row of the storage method of this position will be described with reference to FIG.

FIG. 9 shows an area division for position storage, in which the horizontal axis is the angle γ of the turntable TB and the vertical axis is the Z-axis coordinate. In the figure, the hatched area is the Z of the subject W.
This is a flaw detection range in coordinates. The position storage region is a region slightly larger than the flaw detection region, and the region (γ axis is 0 to 0)
360 °, the Z axis is an area surrounded by Zth _{1 to} Zth ₂ ) divided into (P + 1) in the γ axis direction and (S + 1) in the Z axis direction to form a plurality of small areas.

Then, Za and γa obtained by the equations (9) and (10)
It is checked which small area the figure belongs to, and Za, Dl, γa and a flag indicating the completion of storage are stored as position data of the small area to which the small area belongs.

Here, in each scan of one rotation in the shape measurement operation, since the angle in the γ-axis direction of the small area divided by (P + 1) is larger than the scan pitch angle in the γ-axis direction, measurement data is stored for each scan. Then, two or more data are stored in each small area, and the meaning of partitioning the small area is lost. Therefore, the position data obtained by the current scan (for example, the scan when N = q) belongs to the small area in which the position data has already been stored in the previous scan (for example, the scan when N = q-1). Is determined, only one position data needs to be stored in each small area. (1) The storage content is updated using the new position data obtained this time as storage data.

(2) The stored content is not updated with the old position data already obtained as storage data.

(3) Update the storage content using the average value of new data and old data as new storage data.

Such a method may be used.

Next, the procedure of the program proceeds to step S347 in FIG. 8, and adds 1 to the variable N, that is, ends as N = 2.

When the operation of the timer interrupt program of FIG. 8 is completed, the program procedure returns to step S35 of FIG.
It is determined whether or not one rotation scan is completed based on whether or not is (max + 1). Since N = 2 at this stage, step S3
5 is repeated, during which the timer interrupt program of FIG. 8 operates at certain time intervals, and the subject W is rotated and scanned by the turntable TB as shown in FIG. Along with this scanning, the Dl, Z, and γ position coordinates of the surface shape of the subject W are stored by the storage method described above.

When one rotation scan is completed and N = ma + 1, the program proceeds from step S35 to step S36, and outputs a scan stop command. In response to this stop command, the procedure of the timer interrupt program shown in FIG. 8 proceeds to step S348, where Xmax, Ymax, Zmax, αmax, βma, which are the last command values in one scan.
x, γmax (= 360 °) is taken and servo calculation is performed.
The calculation result is output to the servo amplifiers 13X to 13β, 13T.

When the scanning of one rotation is completed in this way, the process proceeds to step S37 in FIG. 8, and it is determined whether or not the shape measuring operation is completed. In this embodiment, the ultrasonic probe 10 collects surface shape data on a rotary scanning line preceding by a distance L in the Z direction, and controls scanning of the flaw detecting ultrasonic probe 9 based on the result. The point is calculated. Therefore, in order to sequentially drive and control the ultrasonic probe 9 to a plurality of control points on a certain rotational scan line in accordance with the position data obtained by such a shape measurement operation, and to perform flaw detection of the subject W, At least until the ultrasonic probe 9 on the first rotational scanning line of the ultrasonic probe 10 reaches the position, that is, the ultrasonic probe 9 moves downward in the Z direction by L shown in FIG. It is necessary to repeat the rotation scanning for shape measurement until this. Accordingly, the program is not completed by one shape measurement scan, and the program proceeds from step S37 to step S31,
Fetch each axis position command for the next one rotation scan,
Steps S32 to S37 are repeated.

Then, as shown in FIG. 11, when the ultrasonic beam of the ultrasonic probe 9 reaches the vicinity where the position of the surface of the subject W is stored by the shape measuring operation according to FIG. It is determined that the operation has been completed, and the program shifts from step S37 in FIG. 7 to the flaw detection operation in step S40 in FIG.

By the above-described operation of only the shape measurement before the flaw detection operation, the position coordinates of the surface of the subject W in the region indicated by the one-dot chain line in FIG. 11 are stored by the storage method shown in FIG.

Next, the flaw detection operation processing in step S40 of FIG. 5 will be described.

FIG. 12 is a detailed flowchart of the flaw detection operation procedure S40, which is the same process as the flowchart of the shape measurement operation in FIG. First, in step S41, each axis position command value for one rotation scan of the probe for flaw detection 9 is calculated. The calculation will be described in detail with reference to FIGS. 13 and 14.

FIG. 13 is a flowchart of a calculation procedure of each axis position command value for one rotation scan in step S41. FIG. 14 is a flowchart of the stored position data of the surface of the subject W when calculating each axis position command value. FIG. 6 is a diagram illustrating which data is used. The thick solid line in FIG. 14 is a flaw detection scanning line by the ultrasonic probe 9, and the processing in FIG. 13 is for calculating each axis command value of the control point position indicated by ●.

In FIG. 13, a normal vector of the surface of the subject W near the control point position is calculated in step S411. For example, in the case of the control point position indicated by ● in FIG.

Areas near (1, P), (1,0), including the first ●,
When a normal vector is calculated from the data of (2,0) and (2, P), it is determined that there is an error in detection of the surface position of the subject W when the data of the four regions are all very close to ●. The operation error of the vector becomes large, which is not preferable. Therefore, the outer regions (0, P-1), (0,1), (3,1), (3, P-
The data of 1) will be used. The data of the area (0, P-1) is X1, Y1, Z1, the data of the area (0,1) is X2, Y2, Z2,
Assuming that the data of the area (3, 1) is X3, Y3, Z3 and the data of the area (3, P-1) is X4, Y4, Z4, the normal point near the control point position on the surface of the subject W The vector N (= Nx, Ny, Nz) is obtained by the following equation.

However, if i ≠ 4, j = i + 1, and if i = 4, j = 1.

Note that X1 to X4 and Y1 to Y4 are obtained by converting the angle γa and the length Dl by the following equation before performing the normal vector calculation.

X1 = Dlsin (γa−γ) (101) Y1 = Dlcos (γa−γ) (102) Next, the position of the control point is calculated in step S412. Assuming that the position of the control point ● in FIG. 14 is (Xk, Yk, Zk), Zk is a value given for setting the storage area,
Is known. Also, the center coordinates of the turntable TB are set to (0,
(0,0), Yk = 0, and Yk is also known.
Therefore, the position calculation of the control point position in step S412 is a calculation for obtaining Xk.

Now, as shown in FIG. 15, a plane PL including a control point position in a certain coordinate system is expressed by the following plane equation.

NxX + NyY + NzZ + d = 0 (14) Therefore, the normal vector N (=
When Nx, Ny, Nz) are obtained, the coefficient d of the plane equation of the plane PL is given by the following equation from the coordinates (Xm, Ym, Zm) of the position around the circle in FIG.

d = − (NxXm + NyYm + NzZm) (15) By using this coefficient d, the position Xk of the black circle, which is the first control point, is obtained as follows.

Xk = − (d + NyYk + NzZk) / Nx (16) Next, (Xm, Ym, Zm) used for calculating the coefficient d will be described.

The calculation of the normal vector is performed in the region (0, P−
1), (0,1), (3,1), and (3, P-1) were performed using the stored data, but the stored data used for the calculation of the coefficient d was closer to the control position indicated by ●. Is close to the true value. Therefore, the storage data of the areas (1, P), (1, 0), (2, 0), and (2, P) are used. That is, the storage data of the area (1, P) and the expression (1
1) - (a normal vector obtained in 13) is calculated by substituting the equation (15), and its value as d _1. In the same way, the area (1,
The value calculated from the stored data of the area (0) is d ₂ , the value calculated from the stored data of the area (2,0) is d ₃ , and the value calculated from the stored data of the area (2, P) is d _4. To obtain a coefficient d as an average value.

d = (d ₁ + d ₂ + d ₃ + d ₄ ) / 4 (17) In this way, by averaging the coefficients obtained from the four regions, the coefficient d of the control point is determined to be close to the true value. Become.

According to the above description, the normal vector N (= N
x, Ny, Nz) and position (Xk, Yk, Zk).

The procedure of the program in FIG. 13 then proceeds to step S413, where the calculation and storage of the position command value for each axis is performed. here,
When the distance between the ultrasonic probe 9 between the subject W surface is set to be l _0, the position command value for each axis (Xr, Yr, Zr, αr , β
r) is calculated from the following relational expression and stored.

_{Xr = f 5 (Xk, Yk} , Zk, Nx, Ny, Nz, l 0) ... (18) Yr = f 6 (Xk, Yk, Zk, Nx, Ny, Nz, l 0) ... (19) Zr = _{f 7 (Xk, Yk, Zk} , Nx, Ny, Nz, l 0) ... (20) αr = f 8 (Nx, Ny, Nz) ... (21) βr = f 9 (Nx, Ny, Nz) ... ( 22) At this time, the angle command value γr of the turntable TB at the control point is also stored.

Next, the process proceeds to step S414, and it is determined whether the calculation for one rotation scan is completed. As a matter of course, in the above description, only the control points indicated by ● in FIG. 14 have been calculated, so the flow returns to step S411 to perform the normal vector calculation near the next O control point. Thus, step S411
By repeatedly performing the processing of steps 414 to 414, the calculation is performed up to the control point positions indicated by the circles in FIG. 15, and the procedure of FIG. 13 is completed, and the process proceeds to step S42 of FIG. At this time, each axis position command value for one rotation scan is a data group represented by equations (23) to (26).

_{Xr = (Xrs, Xr 1,} ... Xrn, Xrmax) ... (23) Yr = (Yrs, Yr 1, ... Yrn, Yrmax) ... (24) Zr = (Zrs, Zr 1, ... Zrn, Zrmax) ... (25 _{) αr = (αrs, αr 1} , ... αrn, αrmax) ... (26) βr = (βrs, βr 1, ... βrn, βrmax) ... (27) γr = (γrs, γr 1, ... γrn, γrmax) ... ( 28) The processing in steps S42 to S45 in FIG. 12 is performed using the data group of the position command values represented by the equations (23) to (28) obtained in step S412 in FIG. As in the case of the shape measurement operation, steps S42 and S43 are executed. When the subject rotation command, that is, the scan start command is output in step S44, the timer splitting program in FIG. 16 is started.

In step S441 of the program shown in FIG. 16, it is determined whether or not the rotation has stopped. If the result is negative, in step S442, the Nth axis position command value is fetched, and servo calculation and output are performed. Thereafter, the process proceeds to step S443, where the output of the ultrasonic probe 9 is fetched, and the detection result of the flaw detection is used as the control point position (Zr,
γr) is output to the recording device 15. Next, steps S444 to S448 similar to steps S343 to S347 in FIG.
Are sequentially executed, and in parallel with the flaw detection operation, the shape of the scanning line preceding by the distance L in FIG. 3 is measured.

When one rotation scan is completed by repeating such a procedure, the process proceeds from step S45 to S46 to output a subject stop command. Then, if it is determined in step S441 that the scanning is stopped, in step S449, the Nmax-th axis position command values are taken in, and the servo calculation and output are performed. Then, the process proceeds to step S47 to check whether the flaw detection operation is completed.
That is, it is checked whether or not the entire range shown by the thick solid line in FIG. 9 has been scanned.
Returning to step 1, the calculation of each axis position command value for the next one scan, for example, the line marked with X in FIG. 14, is performed.

After scanning the entire flaw detection area shown in FIG. 9,
The program moves from step S47 to step S50 in FIG. 6, positions each axis at a predetermined end position, and the control is completed.

As described above, in the embodiment described with reference to FIGS. 2 to 16, the measurement of the surface shape of the subject W and the flaw detection operation are performed as follows.

(A) The subject is rotated.

(B) The attitude of the distance sensor unit is controlled based on the data of the surface shape of the object given in advance, and the ultrasonic signal for distance detection is emitted toward the rotating object. Then, the distance from the reflected wave to the distance measurement point on the object surface is measured, and from the distance data and the current position of the distance sensor unit, the position information of the measurement point on the object, that is, the shape measurement data is obtained. Is calculated.

(C) The shape measurement data is stored as data of any one of the small regions divided by the rotation angle of the turntable and the Z-axis coordinates. However, only one data is stored in the small area.

(D) The steps (b) and (c) are performed for the distance L shown in FIG.

(E) A position command value (position and attitude of the probe) of the control point of the flaw detection probe is obtained from the surface shape data of the subject W stored in each small area in (b) to (d). .

(F) The position and posture of the flaw-detecting probe are controlled by controlling each axis driving device with the position command value so that the ultrasonic flaw detection signal is directed in the normal direction of the surface of the subject and at a predetermined distance. .

(G) At the position and orientation, an ultrasonic flaw detection signal is emitted from the flaw detection probe to flaw-detect the subject.

(H) In parallel with this flaw detection operation, an ultrasonic signal is received and emitted from the distance sensor unit to the subject, and shape measurement data on a scanning line preceding the flaw detection probe by a distance L is collected. The shape measurement data is used for calculating the position and attitude when the flaw detection probe reaches or near the scanning line.

Therefore, the probe for flaw detection can always be accurately and accurately directed to the predetermined distance and normal direction from the surface of the rotating subject, and flaw detection of a rotating body having an irregular surface shape is easy. Further, since the flaw detection operation and the shape measurement operation are performed in parallel, the measurement time is shortened.

Further, the area for storing the position data is divided into small areas based on the rotation angle of the turntable and the Z coordinate, and only one position data is stored in each area, and the position data of each small area is used to arbitrarily scan a flaw detection scanning line. The control point of the probe is determined. The memory capacity can be reduced.

B. A flaw detection can be performed by freely setting a scanning line different from the shape measurement scanning line. As a result, the degree of freedom of the flaw detection operation is increased, and the arrangement of the flaw detection probe and the distance measurement probe is not restricted.

In the configuration of the above embodiment, the bracket 8D corresponds to the support portion 8D, the X-axis drive 1, the Y-axis drive 3 and the Z-axis drive 6 correspond to the drive 504, and the ultrasonic probe 9 corresponds to the The acoustic wave probe 502 (9), the distance sensor unit 10 performs a distance detection probe 503 (10), the position or angle detector of each axis driving device detects the position detecting means 505, and the distance sensor unit 10
The distance detection circuit 11 and the distance detection circuit 503 constitute the distance detection means 503, and the control device 12 constitutes the position and orientation calculation means 506 and the control means 507.

<Modified Example> In the above example, at the start of flaw detection scanning of an arbitrary line, the position command value of each control point of the line scanning is calculated. Therefore, there is a loss time during which the ultrasonic probes 9, 10 are stopped before the actual flaw detection operation is started. Therefore, in this modification, the position command value for the next line scan is calculated in advance during each flaw detection operation, and the loss time is eliminated.

 This will be described with reference to FIGS. 17 to 19.

FIG. 17 shows a hardware configuration when two central processing units are used. Reference numeral 31 denotes a central processing unit, which is responsible for calculating each axis command value for one scan in the flaw detection operation, and performing other processing by the central processing unit 32. A memory 33 stores the position data of the surface of the subject and a calculation start flag for each axis command value for one scan, and a memory 34 stores each axis command value and a calculation completion flag calculated by the central processing unit 31. is there.

FIG. 18 is a detailed flowchart of the flaw detection operation (instead of FIG. 12) in the central processing unit 32, and FIG. 19 is a flowchart of the central processing unit 31.

 Next, the operation of this modified embodiment will be described.

First, in step S101, the scan counter CN is set to 1, and a command calculation start flag is set in the memory 33. Then, it waits until the calculation completion flag is set in step S102.

The process of FIG. 19 first waits until the calculation start flag is set in step S201. And the steps in Figure 18
If the calculation start flag is set in S101, the process proceeds to step S202, where the count value of the scanning counter is read,
In the next step S203, the operation start flag and the operation completion flag are reset. As a matter of course, initially, the operation completion flag is reset.

Then, the process proceeds to step S204, in which the respective axis command values of the scan line corresponding to the value of CN, that is, first, the first scan line are calculated. This calculation is performed in steps S411 to S411 in FIG.
This is exactly the same as the calculation in S414. Then, in step S205, the obtained axis command values are written in the memory 34,
In step S206, the calculation completion flag is set in the memory 34, and the process returns to step S201 to wait for a command value calculation start command for the next scan line.

The program shown in FIG. 18 proceeds from step S201 to step S103 by setting the operation completion flag, and fetches each axis command value from the memory. Then, in step S104, the count value CN of the scanning counter is incremented by 1, and a command value calculation start flag is set. Further, a flaw detection operation of the first scan line is performed in steps S105 to S109. During this flaw detection operation, the central processing unit 31 performs a command value calculation for the second scanning line.

As described above, according to the present embodiment, since the flaw detection and the command value calculation can be performed in parallel, the time from the start to the completion of the flaw detection can be further reduced.

In the above description, the flaw detection is performed while directing the ultrasonic beam from the flaw detection probe in the normal direction of the surface of the subject.
Make the ultrasonic beam have a certain angle to the normal direction,
For example, the present invention can also be applied to a device that detects an ultrasonic beam by directing an ultrasonic beam in the critical angle direction of a surface wave.

In the above description, at the time of the shape measurement operation prior to the flaw detection operation, the measurement point of the distance sensor unit is commanded using the setting data of the subject, but, for example, two distance sensor units are provided and the sensor unit is used. The shape measurement may be performed while imitating the surface shape of the subject.

G. Effects of the Invention According to the present invention, it is possible to accurately and efficiently detect a subject, which is a rotating body having a complicated surface shape, with high accuracy.

In particular, the storage area of the position information is divided into small areas as described in claim 2, and the position and orientation of the probe on an arbitrary scanning line are obtained based on the position information of each area, so that the storage capacity is reduced. In addition to this, flaw detection on an arbitrary scanning line different from the shape measurement scanning line becomes possible.

[Brief description of the drawings]

FIG. 1 is a diagram corresponding to claims. 2 to 16 illustrate one embodiment of the present invention.
FIG. 2 is an overall configuration diagram of the control system. FIG. 3 is a diagram showing the details of the mounting structure of the ultrasonic probe for flaw detection and the distance sensor unit. FIG. 4A is a block diagram showing details of the distance detection circuit. FIG. 4B is a diagram for explaining γo, γa, and Dl. FIG. 5 is a main flowchart. FIG. 6 is a perspective view showing the distance sensor unit and the subject at the initial position. FIG. 7 is a flowchart of the shape measurement. FIG. 8 is a flowchart showing details of the shape measurement flowchart. FIG. 9 is a view for explaining a flaw detection range and a storage area for position data. FIG. 10 is a perspective view showing the distance sensor unit during the shape measuring operation. FIG. 11 is a perspective view showing a flaw-detecting probe and a distance sensor unit at the start of a flaw detection operation. FIGS. 12, 13 and 16 are flowcharts showing the flaw detection operation. FIG. 14 is a view for explaining a flaw detection scanning line in a small area in which position data is stored. FIG. 15 is a diagram for explaining a coefficient d when calculating position data of a control point from position data of a small area. FIGS. 17 to 19 illustrate a modified embodiment, and FIG. 17 is a block diagram showing the hardware thereof. FIG. 18 and FIG. 19 are flowcharts showing the processing procedure. FIG. 20 is a view for explaining a conventional ultrasonic flaw detector. 1: X-axis driving device, 3: X-axis driving device 6: Z-axis driving device, 8B: β-axis driving device 8E: α-axis driving device, 9: probe for flaw detection 10: probe for distance detection 11: Distance detection circuit, 12: control device 16: rotation drive device 31, 32: central processing unit 33, 34: memory 501: rotation means, 502: ultrasonic probe 503: distance detection means, 504: position and attitude control means 505: position detection means, 506: position and orientation calculation means 507: control means, TB: turntable

Continued on the front page (72) Inventor Takeshi Yamaguchi 650, Kandamachi, Tsuchiura-shi, Ibaraki Prefecture Inside the Tsuchiura Plant, Hitachi Construction Machinery Co., Ltd. (72) Inventor Eiji Minamiyama 650 Kandate-cho, Tsuchiura-shi, Ibaraki Hitachi Construction Machinery Co., Ltd. Tsuchiura Works (56) References JP-A-1-292248 (JP, A) (58) Fields investigated (Int. ⁶ , DB name) GOIN 29/00-29/28

Claims (2)

(57) [Claims] 1. An ultrasonic flaw detector which searches for a flaw in a subject mounted rotatably about a predetermined rotation axis in a three-dimensional coordinate system, wherein the ultrasonic flaw detector is movable in the three-dimensional coordinate system. A supporting unit provided, a driving device for moving the supporting unit along the three-dimensional coordinate system, and emitting an ultrasonic inspection signal toward the rotating subject and receiving a reflected wave thereof. An ultrasonic probe provided on the support portion, a distance detection probe provided on the support portion so as to scan on a scan run preceding the ultrasonic probe, Position detecting means for detecting the position of the probe in the three-dimensional coordinate system; and distance detecting means for calculating the distance to a distance measurement point on the subject based on a signal detected by the distance detecting probe. And a detection result of the distance detecting means and a detection of the position detecting means. Based on the result, the position information of the distance measurement point on the subject is calculated, and the position and orientation of the ultrasonic probe are calculated from the calculation result. Based on the calculation result, the ultrasonic inspection signal is detected. Position and orientation calculation means for outputting a signal for controlling the position and orientation of the ultrasonic probe so as to be incident at a predetermined angle from a predetermined distance of the sample to the driving device; and a circumferential direction of the subject by the distance detection means An ultrasonic flaw detection apparatus comprising: a control unit that outputs a signal to the driving device for performing a scan and a flaw detection scan of a subject by the ultrasonic probe in parallel in the circumferential direction. 2. The apparatus according to claim 1, further comprising: storage means for dividing the surface of the subject into small areas divided by a rotation angle and a position in the direction of the rotation axis, and storing only one piece of the position information for each small area. An ultrasonic flaw detection apparatus, comprising: calculating a position and a posture of the ultrasonic probe based on position information in a small area corresponding to each circumferential flaw detection scan.