JPS63309852A - Ultrasonic flaw detecting method - Google Patents

Abstract

PURPOSE:To speed up flaw detection with high accuracy by storing a shape of a body to be measured, in a memory, calculating a controlled variable of a driving mechanism from a shape data stored in the memory, and bringing a driving part of each axis to an open loop control. CONSTITUTION:A distance sensor 2 and an alpha axis driving motor 3 are attached to the lower end of a three-dimensional scanner which can move in the directions of an (x) axis, a (y) axis and a (z) axis being orthogonal to each other, the sensor 2 is scanned at the upper part of a body to be measured 1, and a distance of the sensor in each point of the (x) and (y) axes is measured, and inputted to a computer. Subsequently, by the computer, a point being at a prescribed distance in the normal direction in a point of the surface of the body to be measured 1 is derived and a tip position of a probe 6 is moved, always, made vertical to the surface of the body to be measured 1, and also, allowed to hold a prescribed distance. Next, from a characteristic function which is provided in advance, a controlled variable of a driving mechanism is generated by an arithmetic processing part, and a driving part is brought to an open loop control.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an apparatus that automatically performs ultrasonic flaw detection in ice on curved objects made of ceramics, composite materials, or the like.

[Prior Art] Conventionally, as a general-purpose method for automatically performing ultrasonic flaw detection underwater on curved objects using a three-dimensional scanner, there is only one that performs automatic ultrasonic flaw detection on objects with simple shapes such as cylinders. For complex objects such as the interior of an engine, there is only a dedicated ultrasonic flaw detector, and it cannot be measured if the object to be measured changes.

When testing a simple curved object such as a cylinder using a general-purpose 3D scanner, manual teaching of the position and direction of movement is required to make the ultrasonic probe conform to that shape. Is this commonly done?

By the way, in ultrasonic flaw detection, the position and angle of the ultrasonic probe with respect to the object surface have an important influence on the flaw detection results. Therefore, in order to perform ultrasonic flaw detection automatically, it is necessary to maintain the position and angle of the probe with respect to the object to be measured constant during scanning.

In other words, if you want to accurately determine the internal flaws or conditions of the object to be measured, hold the ultrasonic probe perpendicular to the surface of the object at the point of incidence on the surface of the object. The probe must be held at a certain distance from the Unless the probe is held at a certain distance from the surface, the size of the internal flaw cannot be estimated from the reflected echo level.

In addition, when investigating flaws on the surface of an object to be measured, it is necessary to maintain the angle of incidence of the ultrasonic waves at a critical angle and to hold the probe at a certain distance from the point of incidence of the ultrasonic waves.

However, in manual teaching, there are few set points (trailing reference points), and when scanning, it is necessary to keep the incident angle of the ultrasonic waves constant with respect to the surface of the object to be measured and to adjust the distance between the object surface and the probe. It is not possible to hold the temperature constant, making it impossible to obtain accurate flaw detection results.

Therefore, there is an example in which the shape of an object with a curved surface was measured in advance, and automatic ultrasonic flaw detection of the object was performed using a robot hunt holding an ultrasonic probe ("inpleme").
ntation of a robotic mani
pulator for the ultrasonic
1nspection of coIlposite
Structures”Review of Pro
gress in Quantitative, n
onstructive evaluation
4B, July 8-13.1984). In this ultrasonic flaw detection device, a probe held by a robot hunt moves to a designated point (tracing reference point) while following the curved surface shape. However, the moving speed is slow because the robot performs feedback control of the hand position, etc., so in order to maintain the scanning speed to a certain degree, the number of tracing reference points must be limited. For this reason, in the middle of these tracing reference points, the probe moves linearly between two adjacent tracing reference points using the linear interpolation method, and the measurement accuracy of such areas will drop significantly. . Therefore, in order to perform flaw detection with high precision, a long interval is required, for example, 100gm pitch = 100m + lX 10
Considering the case of flaw detection in the 0+ns area, it takes 30II to move one point, 1. , if you need about 80
It takes time.

[Problems to be solved by the invention] As described above, with conventional ultrasonic flaw detection equipment, it is not possible to perform ultrasonic flaw detection with high precision when using the manual teaching method, and when using the automatic ultrasonic flaw detection method, However, if high-precision ultrasonic flaw detection is to be performed, a huge amount of time will be required. In the latter method, if you want to perform high-speed flaw detection, you will have to reduce the number of points to be traced, and in this case, the result will be the same as the manual teaching method, making it impossible to perform high-precision ultrasonic flaw detection. . That is, as shown in FIG. 5, when performing ultrasonic flaw detection with high precision, the tip of the ultrasonic probe must be moved smoothly while following the curved surface, as shown by the solid line. However, in manual teaching and robot hunting flaw detection methods, the robot moves as shown by the dotted line. Therefore, depending on the measurement position, it is not possible to maintain the angle and distance between the probe and the flaw detection surface at constant values, which are required for high-precision flaw detection.

In view of these problems, it is an object of the present invention to universally perform automatic ultrasonic flaw detection at high speed and with high precision on curved objects made of ceramics, composite materials, or the like.

[Means for Solving the Problems] In order to achieve this object, the present invention provides a three-dimensional scanner that moves in each direction of three different axes, that is, an X-axis, a y-axis, and a Z-axis; A drive mechanism consisting of a holder rotatably attached to the dimensional scanner; an ultrasonic probe installed in the holder; a pulsar receiver for transmitting and receiving ultrasonic waves from this ultrasonic probe; shape of the object to be measured. and a calculation processing unit for calculating the control amount of the drive mechanism from the shape data recorded in the memory.

[Operation] According to the present invention, by providing a memory for storing the shape of the object to be measured and an arithmetic processing unit for calculating the control amount of the drive mechanism from the shape data stored in the memory, the control amount of the drive mechanism can be calculated in advance. It becomes possible to generate data that gives the following information and perform open-loop control with the drive unit of each axis. Therefore, extremely high-speed movement is possible compared to the feedback control method that controls the robot's work while detecting the current position, etc., as in normal robot control.

[Example] Hereinafter, the present invention will be described in detail based on the drawings. FIG. 1 is a diagram showing an outline of a measuring section of an embodiment of an ultrasonic flaw detection apparatus according to the present invention, and FIG. 2 is a diagram showing an outline of the data flow and the entire apparatus in the same embodiment. In this figure, l is the object to be measured, 2 is the distance sensor, 3 is the α-axis motor,
4 is a θ-axis motor, 5 is a holder, 6 is an ultrasonic probe, 7 is a water tank for automatic underwater ultrasonic flaw detection, 11 is a computer as an arithmetic processing unit, and 12 is a measured object measured by the distance sensor 2 Distance data representing the shape of the body l, 13 is a measuring device of the distance sensor 2, 14 is a pulser receiver for transmitting and receiving ultrasonic waves from the ultrasound probe 6, 15 is an X-axis, a y-axis, a Z-axis,
16 is a pulse train for controlling the rotation amount of the motor for each axis; 17 is ultrasonic data; 18 is data on ultrasonic flaw detection results; 19 is This is a CRT display that displays the flaw detection results.

The distance sensor 2 and the α-axis motor 3 are the X-axis and the y-axis.

It moves in two axes (vertical axes) and is attached to the lower end (Z-axis direction) of the 3D scanner. Here, the X-axis, y-axis, and Z-axis are orthogonal to each other. Further, as the distance sensor 2, for example, a laser distance meter sensor is used.

Further, α and θ indicate rotation directions, α has a rotation axis in the Z-axis direction, and θ has a rotation axis in the plane (horizontal plane) direction formed by the X-axis and the y-axis.

Next, its operation will be explained. By scanning the distance sensor 2 above the object to be measured l placed in the water filled in the water tank 7, the
), the distance between the surface of the object to be measured l and the distance sensor 2 is measured, and the shape function z=f(x, y) of the object to be measured l is obtained. This distance data 12 is taken into the computer 11.

FIG. 3 shows an example of a mesh for scanning with a three-dimensional scanner. In this example, measurements are taken at N points along the X axis with a pitch of dx, and this operation is repeated M times in the Y direction with a pitch of cty (only the X coordinate is shown in the figure). That is, there are MN points to be measured.

In the calculator 11, using this shape function r(x, y),
A point U ij = (x ij
+ Y ij+ Z ij+ θij+ αij). Here, j+J+ θ, α are i=0, 1, 2. ......, N-1j = 0
, 1 , 2. ...9M-1cos O= (
Z+JZ+, +) /dCO5α” (x ij
ij) / '.

In this case, (xoo+ yoo+ f (xoo+
yoo) *(x+o, yIQ+ f(x+o, y
+o)) l (x20+ 3'20+fcx2o+
y2o)),..., (x o 11 yoH
, f (x o□.

yox)), ......, along the ultrasonic incident point of the object l, the tip position of the ultrasonic probe 6 is U. Or U10+ U20+...
By moving in the order of U o r +..., it becomes possible to perform flaw detection while always being perpendicular to the surface of the object to be measured l and maintaining a constant distance d.

In order to enable such flaw detection, a differential data string MiJ of these data strings U i j = (δX i 1 δY i J + δZij
, δθij+δαij). Here, δx, J is δX ij" X (i+I)j X ij,
δY l j + δZ i , δθiJ+ δα, J
The same is true.

A pulse train proportional to the value of these data sequences is used to drive and control the motor of each axis, but if the difference data sequence is used as is, the characteristics of the motor that moves each axis and the frictional dynamic characteristics of each axis will be affected. Since such factors are not taken into account, driving time delays, overshoots, etc. occur, and the probe 6 does not move to the specified position.

Therefore, as shown in FIG. 4, the characteristic function F (n) for the step input of the pulse train (0, 0, 0, 0, 10 ports 100, . . . ) is determined for each motor. A new data sequence p of the difference obtained using this characteristic function
, (δx',, δY'ij+δZ'jj+ δθ'
, J, δα′, J), then δX , :ΣFx(n)
Since δX iJ and Fx (n) are known in XδX'ij, it is possible to obtain the data string δX'ij.

Similarly, δY'ij+ δZ'ij+ δθ', J
.

It is also possible to obtain δα ij. This data string P,
By inputting a pulse train 16 proportional to J to the motor driver 15, the amount of rotation of each shaft motor is appropriately controlled, and the ultrasonic probe 6 is moved to a designated position at high speed and with high precision.

In the above embodiments, the ultrasonic probe always faces the normal direction to the curved surface of the object to be measured and is at a constant distance, that is, an example of internal flaw detection of the object to be measured is described. However, by using a similar method, it is also possible to perform surface wave flaw detection at high speed and with high precision while generating surface waves on the surface while maintaining a constant angle and distance from the surface.

Furthermore, in the above embodiments, the shape of the object to be measured was directly determined using the distance sensor 2, and the data obtained thereby was used. It goes without saying that shape information at the time may also be used. That is, for example, information created by CAD or the like or information such as the radius of a ball such as a bearing can be used as data for scanning.

[Effects of the Invention] As is clear from the above description, according to the present invention, there is provided a memory for storing the shape of the object to be measured, and an arithmetic processing section for calculating the control amount of the drive mechanism from the shape data stored in the memory. By providing this, it becomes possible to generate data in advance that gives the control amount of the drive mechanism, and to perform open loop control of the drive section of each axis. Therefore, it is possible to conduct ultrasonic flaw detection at high speed and with high precision while tracing an ultrasonic probe at a constant angle and at a constant distance from the surface of a curved object to be measured.

[Brief explanation of drawings]

Fig. 1 is a diagram showing an outline of the measurement section of an embodiment of the ultrasonic flaw detection device according to the present invention, Fig. 2 is a diagram showing an outline of the data flow and the entire device in the same embodiment, and Fig. FIG. 4 is a diagram showing an example of a mesh for scanning with a three-dimensional scanner in the embodiment, FIG. 4 is a diagram showing an example of a motor characteristic function, and FIG. 5 is a diagram showing an example of the trajectory of an ultrasound probe in a conventional example. It is. In the figure. l: Measured object 2: Distance sensor 3: α-axis motor 4: O-axis motor 5: Holder 6: Ultrasonic probe 7: Water tank

Claims (2)

[Claims] (1) A drive mechanism consisting of a three-dimensional scanner that can move in each direction of three different axes (x-axis, y-axis, and z-axis) and a holder rotatably attached to the three-dimensional scanner; An ultrasonic probe to be installed, a pulser receiver for transmitting and receiving ultrasonic waves from the ultrasonic probe, a memory that stores the shape of the object to be measured, and a drive mechanism based on the shape data recorded in this memory. An ultrasonic flaw detection device comprising: an arithmetic processing unit for calculating a control amount. (2) A distance sensor is installed at the lower end of the three-dimensional scanner in the z-axis direction, the distance sensor measures the shape data of the object to be measured, and the measurement results are stored in a memory. The ultrasonic flaw detection device described in (1).