JPH0357958A - Ultrasonic flaw detection apparatus - Google Patents

Abstract

PURPOSE:To automatically set the distance between the position of a probe to the center of rotation of an object to be inspected and the upper surface of said object to be inspected by providing a Z-axis distance setting means, an operation means and a reference value setting means. CONSTITUTION:A probe 5 is moved to the center part of the upper surface 4' of a master work by X- and Y-axis scanning means 7, 8. Subsequently, a Z-axis distance setting means 10 controls a Z-axis scanning means 9 so that the distance between the probe 5 and the upper surface 4' becomes the focal distance of the probe to automatically set the distance in a Z-axis direction. When the probe 5 is allowed to scan in the X- and Y-axis directions at the arbitrary position of the upper surface 4a' through the means 7, 8, and operation means 11 calculates the middle point between two points where an echo peak is dropped by 6dB in the respective directions and calculates the intersecting point of the straight line in an X-axis direction crossing said point at a right angle and the straight line in a Y-axis direction as the center XO, YO of the circle of the upper surface 4a'. A reference value setting means 12 sets the distance between the set probe 5 and the upper surface 4a' and the center XO, YO calculated by the means 11 as reference values. By this method, the position of the probe 5 can be set instantaneously and accurately.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an ultrasonic flaw detection device that automatically inspects flaws such as welded parts of a test object by water immersion flaw detection, and particularly relates to an ultrasonic flaw detection device that automatically inspects flaws such as welded parts of a test object by water immersion flaw detection. When testing a cylindrical or cylindrical object placed on a cylinder from the circular surface side of the object, the position of the probe relative to the center of rotation of the object and the distance between the top surface of the object and the probe can be automatically determined. The present invention relates to a device suitable for setting.

[Prior art] When performing ultrasonic flaw detection, flaw detection conditions such as the position of the probe with respect to the object, gain, gate, etc. are determined by comparing the flaw detection results when testing multiple objects with the same size and shape. It is desirable to set the same conditions, and it is essential to keep the flaw detection conditions constant, especially when a large number of objects of the same shape are to be inspected in succession.

A rotating body with a circular or cylindrical cross section is an example of a large number of objects to be examined with the same shape. Conventionally, such objects are placed on the circular surface of the object (a surface perpendicular to the axis of rotation of the object). To set the probe position when performing flaw detection from
Operate the axis scanning means to measure the Z distance between the probe and the top surface of the subject.
Set the axial distance to a certain distance, for example, to match the focal length of the probe, and then operate the X-axis and Y-axis scanning means to move the probe to an arbitrary position on the top surface of the subject.
Scan in the axial and Y-axis directions, find two points where the echo height drops by 6 dB in each axial direction, and find the intersection of straight lines in the X-axis direction and the Y-axis direction that are orthogonal to the midpoint between the two points. The obtained intersection becomes the center of the circle on the upper surface of the subject, that is, the reference position during probe scanning, and becomes the so-called origin. Next, the distance from the origin of the position to be inspected on the object and the depth dimension from the top surface of the object are input to the scanning means, and the probe is scanned by a scanning signal based on the input values to position the probe relative to the area to be inspected. The settings had been made.

The position of the probe is set so that the rotary table on which the subject is placed is usually circular, and the center of rotation of the table and the center of rotation of the subject are precisely aligned.
Sometimes it is performed on a rotating table. [Problems to be Solved by the Invention] Setting of the probe position with respect to the object is performed manually by the inspector while looking at the A scope on the oscilloscope of the ultrasonic flaw detection device. ,
Since it is necessary to operate the scanning means of each axis while adjusting the gain and gate of the ultrasonic flaw detection device, a certain level of skill is required. Due to the manufacturing accuracy of the mounting part and the mounting part of the rotating device that rotates the water tank and the subject,
The movement accuracy of the probe is 1/10, which is the desired position accuracy.
It is a time-consuming and troublesome task to get within ~1/100m, and there is a problem in that it is difficult to always position accurately. In view of the above-mentioned problems of the prior art, the present invention provides a method for rotating a cylindrical or cylindrical test object placed on a rotary table in a water tank when detecting flaws from the circular surface side of the test object. It is an object of the present invention to provide an ultrasonic flaw detection device that can automatically set the position of a probe with respect to the center and the distance between the probe and the upper surface of a subject.

[Means for Solving the Problems] In order to achieve the above object, the present invention is directed to a columnar or cylindrical test object placed on a rotary table in a water tank, relative to a circular surface side of the test object. The probe placed with x,
In an ultrasonic flaw detection device that automatically detects flaws through scanning means that moves in the directions of the y and z axes, between the probe and the top surface of a circular master work for initial setting of flaw detection conditions placed on the rotary table. A two-axis distance setting means that can automatically set the distance of When scanning in the axial direction, find the midpoint between two points where the echo height drops by 6 dB in each axis direction, and use the master work to find the intersection of the straight line in the X-axis direction and the straight line in the Y-axis direction that are perpendicular to the midpoint. calculation means for calculating the center of the circle on the top surface (xo, y-); the distance between the probe and the top surface of the master workpiece set by the Z-axis distance setting means; and the center of the top surface of the master workpiece calculated by the calculation means ( The apparatus further includes a reference value setting means for setting the values (Xo, Yo) as reference values.

[Operation] With the above structure, the distance between the probe and the top surface of the masterwork is automatically set to the focal length of the probe by the Z-axis distance setting means, and the distance between the probe and the top surface of the masterwork is automatically set to the focal length of the probe, and the distance between the probe and the top surface of the masterwork is automatically set to the focal length of the probe, n), that is, the origin is automatically calculated by the calculation means and both are set as reference values in the reference value setting means, but the inspector must calculate the distance from the origin to the position on the object to be inspected, and the distance from the object to be inspected. By simply inputting the depth dimension from the top surface to the position to be inspected, the scanning means of each axis can be opened in response to an operation signal corresponding to the input value, and the probe can be set at a predetermined inspection position.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. In the figure, 1 is a water tank for water immersion testing;
Reference numeral 2 denotes a rotary table placed in the water tank 1; 3 a rotating device for rotating the rotary table 2; the rotating device 3 is attached to the water tank 1;

4' is a cylindrical master work for initial setting of flaw detection conditions placed on the rotary table 2.
The upper surface 4'a of ' is formed into a circular shape. Reference numeral 4 indicates an object to be inspected that has the same dimensions and shape as the master work 4', and 4a is the upper surface of the object to be inspected. 5 is the top surface 4' of the master work 4'
The probe is placed immersed in water in the water tank 1 facing the probe a, and is connected to the ultrasonic flaw detector 6. 7 is an X-axis scanning means for scanning the probe 5 in the X-axis direction; 8;
Reference numeral 9 denotes Y-axis and two-axis scanning means for respectively scanning the probe 5 in the Y- and Z-axis directions, and each scanning means is equipped with a driving device and a related signal generator. Reference numeral 10 denotes a two-axis distance setting means capable of automatically setting the distance of the probe 5 in the Z-axis direction, which is connected to the Z-axis scanning means 9 and includes a Z-axis distance memory comparator, a Z-axis distance setting device, and the like. Reference numeral 11 denotes a calculation means for calculating the center of the circle (xo=yo) on the top surface 4'a of the master workpiece, which includes an echo level memory, a comparator, a calculation machine, etc. The midpoint between two points (the intersection of the scanning line of the probe 5 and the circumference of the master work 4'a) where the echo height drops by 6 dB when scanning in the arbitrary X-axis direction of 'a', and the Y
The axis scanning means 8 moves the probe 5 to the top surface 4 of the master workpiece.
The echo height is 6 dB by scanning in the arbitrary Y-axis direction of 'a.
The midpoints between the two points to be dropped are determined, and the intersection between the straight line in the X-axis direction and the straight line in the Y-axis direction perpendicular to each of the midpoints is calculated as the center (x0, y.) of the circle. ■2 is 2
The fixed distance between the probe 5 and the master work top surface 4'a set by the axial distance setting means 10 (in this case, matched to the focal length of the probe 5) and the master work top surface 4' calculated by the calculation means 11. The center of the circle of a (x0=
yo) as a reference value. The positioning of the probe 5 is performed with respect to 4'a on the top surface of the master work, and the procedure will be explained with reference to the flowchart in FIG. 2. First, the probe 5 is moved onto the center of the upper surface 4'a of the master work by the X-axis and Y-axis scanning means 7, 8. Next, the beam path lengths are compared by the beam path count in the Z-axis distance setting means 10,
The comparison signal causes the probe 5 and the master work upper surface 4' to
a, and the two-axis scanning means 9 is controlled so that the distance becomes the focal length of the probe 5, and the distance in the Z-axis direction is automatically set. Next, the X-axis and Y-axis scanning means 7,
8 to move the probe 5 in the X-axis direction and the Y-axis direction, and the echo height is 6 dB in the X-axis direction.
6dB in the Y-axis direction and the midpoint between the two drop points
A calculation means 11 calculates the midpoint between the two dropping points, and calculates the intersection of the straight line in the Y-axis direction perpendicular to the midpoint in the X-axis direction and the straight line in the X-axis direction perpendicular to the midpoint in the Y-axis direction. Yo? It is calculated as the center (x0, y,) of the circle on the top surface 4'a of the master work, that is, the origin. The calculated origin is set as a reference value in the reference value setting means 12 together with the set distance in the Z-axis direction.

Once the distance in the Z-axis direction and the origin with respect to the master work 4' are set, the object 4 to be inspected is placed on the rotary table 2 instead of the master work 4', and the inspector determines the position of the object 4 to be inspected. The distance from the origin (diameter or radius of the flaw detection position) and the depth dimension from the upper surface 4a of the object 4 to the position to be flaw detected are input. With this input, the position of the probe 5 with respect to the flaw detection position (X, Y, Z) of the object 4 is automatically calculated, and each scanning means 7 of the X, Y, and Z axes is
, 8, , 9, the probe 5 is moved to the flaw detection position (x1, y, Z8). The position of the moved probe 5 will always be constant regardless of the manufacturing accuracy of the ultrasonic flaw detection device if the flaw detection positions (XE, Y, 2) are the same, so a large number of objects will be sequentially detected. Even in such a case, the position of the probe 5 can be immediately and accurately set.

[Effects of the Invention] Since the present invention is configured as described above, a cylindrical or cylindrical specimen placed on a rotary table in a water tank is inspected for flaws from the circular surface side of the specimen. In case,
It is possible to automatically set the position of the probe relative to the center of rotation of the subject and the distance between the top surface of the subject and the probe.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of the overall structure showing one embodiment of the present invention, Figure 2
This figure is a flowchart for explaining the procedure for setting the probe position using the apparatus shown in FIG. 1... Water tank, 2... Rotating table, 4... Subject, 4'... Master work, 4'a... Top surface of master work, 5... Probe, 7... X axis scanning means,
8... Y-axis scanning means, 9... 2-axis scanning means, 10.
...Two-axis distance setting means, 11...Calculating means, 12...
・Reference value setting means.

Claims (1)

[Claims] 1. Scanning in which a cylindrical or cylindrical test object placed on a rotary table in a water tank is moved in the X, Y, and Z axis directions with a probe placed facing the circular surface of the test object. In ultrasonic flaw detection equipment that automatically detects flaws through means,
Z-axis distance setting means capable of automatically setting a distance between the probe and the top surface of a circular master work for initial setting of flaw detection conditions placed on the rotary table to match the focal length of the probe; The midpoint between two points where the echo height drops by 6 dB in each axis direction when the probe is scanned in the X-axis and Y-axis directions at an arbitrary position on the upper surface of the master work via the axis and Y-axis scanning means. seek,
The intersection of the straight line in the X-axis direction and the straight line in the Y-axis direction perpendicular to the midpoint is the center of the circle on the top surface of the master work (X_o, Y_o
), the distance between the probe and the top surface of the master workpiece set by the Z-axis distance setting means, and the center (X_o, Y_o) of the top surface of the master workpiece calculated by the calculation means are set as reference values. An ultrasonic flaw detection device comprising: a reference value setting means for setting a reference value.