WO2017014344A1

WO2017014344A1 - Automatic calibration device for non-destructive ultrasound inspection device, and control method therefor

Info

Publication number: WO2017014344A1
Application number: PCT/KR2015/007782
Authority: WO
Inventors: 이명호; 김효섭
Original assignee: (주)윤택이엔지
Priority date: 2015-07-23
Filing date: 2015-07-27
Publication date: 2017-01-26

Abstract

The present invention relates to an automatic calibration device for a non-destructive ultrasound inspection device, and a control method therefor, wherein an XY table (10) is fixed onto a pipe (200) being produced and is moved in the X-axis or Y-axis direction under the control of a main controller (60), and a turntable (20) is provided on the XY table (10) so as to be rotatable. A specimen fixing plate (40) is provided on the turntable (20) so as to fix a specimen (210). A plurality of ultrasound sensors (50) detect defects such as cracks and holes formed in the specimen (210); the main controller (60) controls the XY table (10) so as to move the specimen (210) and controls the ultrasound sensors (50) such that the ultrasound sensors (50) detect cracks, holes, and the like of the specimen (210) and display the detected cracks, holes, and the like on an input and display means (70); and, additionally, the defects of the specimen (210) detected by the plurality of ultrasound sensors (50) are displayed on the input and display means (70). Thus, the calibration device can be quickly and accurately installed, thereby improving the reliability and efficiency of calibration. In addition, the size of a specimen is small, carrying is convenient, and manufacturing is simple, such that installation is easy and the time required therefor is saved, thereby improving productivity, and enabling even an ultrasound sensor provided at any angle to be calibrated by an XY table and a turntable.

Description

Automatic calibration device for nondestructive ultrasonic inspection device and its control method

The present invention relates to an automatic calibration device for a non-destructive ultrasonic inspection apparatus and a control method thereof. More particularly, a pipe specimen having a turn table and an XY table installed on a pipe under inspection and a defect portion such as a crack or a hole is formed on the XY table. An automatic calibration apparatus for a non-destructive ultrasonic inspection apparatus capable of calibrating an ultrasonic inspection apparatus by displaying a signal for detecting a bad state of the oligomer and a control method thereof.

Non-destructive ultrasonography sends sound waves above the audible range, usually ultrasound frequencies of 0.5 to 15 Mc, to the specimen to be inspected by defects caused by internal confusion or by the presence of uneven layers. How to detect.

In this method, electric vibration of radio frequency is applied to both ends of a quartz plate or barium titanate plate of appropriate thickness, and the plate generates mechanical vibration.In contrast, when ultrasonic wave is subjected to mechanical vibration, positive and negative electricity is generated at both ends to generate electric vibration. Ultrasound is a method that uses the changing properties.

Ultrasonic waves have a short wavelength and go straight. Ultrasonic speed is about 330m / s in air, about 1500m / s in water, and about 6000m / s in river. do.

In order to penetrate the ultrasonic wave into the cavity, water or glycerin is coated on the surface of the steel to bring the ultrasonic oscillator into contact. In addition, the ultrasonic wave is detected by detecting the strongest reflection of the ultrasonic wave from the internal defect.

Defects present in the welds of spiral welded pipes always include problems of shortening the life of the product or deteriorating the safety of the welded product. There are many non-destructive testing methods for detecting weld defects, but they are examined using ultrasonic flaw detection.

The welding beads may have welding defects such as pin holes or blow holes caused by the mixed gas, and shrinkage holes caused by shrinkage during solidification. At this time, the pin hole is a pore having a diameter of 2-3mm or less and usually exists in a state in which a plurality of holes are gathered, and the blow hole is a pore generated in the weld metal. It is a hole of.

The inspection method using ultrasonic waves is advantageous because only one side of the weld can be accessed and is less affected by heat, light and electromagnetic fields generated during welding.

However, in the case of using ultrasonic waves, there are difficulties in that the ultrasonic sensor is closely adhered to the surface of the base material by continuously supplying a flaw solution and the characteristics of the ultrasonic waves are severely changed with temperature.

In addition, it is produced by inspecting ultrasonically to find the defect formed in the spiral pipe during spiral pipe production. 9 is a schematic perspective view of a pipe having defects or defects of the pipe.

As shown in FIG. 9, defects in the pipe T can be identified according to their position. Accordingly, the inner or outer surface defects include longitudinal defects LD and circumferential (or transverse or intersecting or transverse) defects CD, and tilted or oblique direction defects ID, and the ultrasonic sensor By means of different arrangements, the defects may be standard requirements, specification requirements, or customer requirements (e.g., the length value of the defects mentioned in the standard is ½ at a depth of approximately 5% of the thickness of the product being inspected). Attempts to detect them immediately beyond the range of lengths and depths specified in inches or approximately 12.7 mm).

In addition, defects in the "pipe wall" of interest, that is, defects in the mass (not shown in Figure 1), are often formed in the inclusions and cracked distal ends, and their detection is due to the measurement of thickness and Tried together Ultrasonic beams are shown scanning at one point in FIG. 9 to illustrate detection of defects. In practice, the ultrasound beams converge at almost one point.

Conventionally, in the non-destructive inspection by ultrasonic, one of the following three types of installations is used, namely, a 'rotation head' installation type, a so-called 'rotation pipe' installation type, and a detector installation surrounded by multiple elements. All of these installation types are known to those of ordinary skill in the art.

However, in order to inspect a pipe using an ultrasonic test apparatus, a calibration process is required every 8 hours to test whether the ultrasonic tester and the ultrasonic sensor are in a normal state.

Conventionally, since the installation of the equipment for stopping and calibrating the production line and calibrating the ultrasonic inspection device, the calibration time is consumed a lot, there is a problem that the productivity is lowered.

The present invention is to solve the above problems, an object of the present invention is to provide an automatic calibration device for a non-destructive ultrasonic inspection apparatus and a control method thereof that can simplify and speed up the calibration (calibration) process of the ultrasonic inspection apparatus. will be.

Another object of the present invention is to provide a non-destructive ultrasonic inspection device that can be easily and quickly calibrated by manufacturing the specimens that can be calibrated to be easily handled and installed so that the specimens can be rotated and moved in the XY axis direction on the pipe being produced. It is to provide a calibration device and a control method thereof.

In order to achieve the above object, an automatic calibration device for a non-destructive ultrasonic inspection apparatus according to the present invention includes an XY table fixed on two pipes being produced and moving in the X-axis or Y-axis direction; A turn table rotatably mounted on the XY table; A specimen fixing plate installed on the turn table to fix the specimen; A plurality of ultrasonic sensors for detecting defects formed in the specimen; A main controller controlling the XY table, the turn table, and the Y-axis table to move the specimen so that the ultrasonic sensor detects a defect of the specimen and displays the input and display means; It characterized in that it comprises an input and display means for displaying a defect of the specimen detected by the plurality of ultrasonic sensors.

According to an embodiment of the present invention is installed between the turn table and the specimen fixing plate, Y-axis table for adjusting the position of the specimen by moving in the transverse direction (Y-axis direction) across the pipe under the control of the main controller It characterized in that it further comprises.

According to an embodiment of the present invention, the XY table includes a plurality of fixed legs to which a plurality of hinges are attached to both ends and is attached to the outer surface of the pipe by attachment means that are defective by hinges attached to the lower ends of the fixed legs. By being attached, the XY table is configured to be fixed to the pipe.

According to an embodiment of the present invention, the XY table has a top plate body formed in a rectangular plate shape; Four fixed legs rotatably installed at four corners of the upper plate body by an upper hinge and having a “s” shape; It characterized in that it comprises a mounting means rotatably installed by the lower hinge to the lower end of the fixed leg.

According to an embodiment of the present invention, the upper plate body of the XY table is horizontally maintained by the upper hinge, the four fixing legs and the lower hinge so that the specimen fixed to the specimen fixing plate is horizontal so that ultrasonic inspection is stable. And configured to be executable.

According to an embodiment of the present invention, the turn table is installed on the upper plate body of the XY table, and rotates around a rotation axis; It characterized in that it comprises a rectangular support plate in the form of a square plate integrally attached to the upper surface of the rotating disk.

According to an embodiment of the present invention, the rotating disc of the turn table is configured to be adjusted by the locking device after the rotation by rotating the specimen so that the ultrasonic wave emitted from the ultrasonic sensor is incident to the direction of the defect. It features.

According to an embodiment of the present invention, the specimen holding plate is formed in a flat horizontal plane so that the specimen is placed on a horizontal plane, and a plurality of “a” shaped fixing pieces are fixed to the specimen holding plate by the fixing bolts. It is characterized in that it is configured to.

According to an embodiment of the present invention, the plurality of ultrasonic sensors are attached to an ultrasonic sensor support plate attached to an ultrasonic sensor support that moves under the control of the main controller, and injects ultrasonic waves into a specimen under the control of the main controller. And receiving ultrasonic waves reflected from the defect portions formed on the specimen and outputting the ultrasonic waves to the main controller to detect the defect portions formed on the specimen.

The control method of the automatic calibration device for a non-destructive ultrasonic inspection apparatus according to the present invention includes the steps of the main controller to check the specimen by moving the specimen detection sensor to a position corresponding to the position data input by the inspector through the input and display means; Aligning, by the main controller, the ultrasonic sensor and the specimen defective portion by the position data of the specimen and the position data of the defect portion input by the inspector; Checking, by the main controller, a scan zero point at which the ultrasonic sensor starts scanning, scanning and scanning an ultrasonic signal while advancing the ultrasonic sensor toward a defective portion input by the inspector; The main controller performing a zigzag scan around the defective portion near the defective portion input by the inspector; And storing, by the main controller, a reflection position where the ultrasonic signal is reflected during the scanning of the defective portion in the internal memory and displaying the level of the reflection signal on the display means.

According to the automatic calibration device for a non-destructive ultrasonic inspection apparatus according to the present invention, it is possible to quickly and accurately install the calibration device of the ultrasonic scanner has the effect of improving the reliability and efficiency of the calibration.

In addition, the size of the specimen is small, easy to carry and simple to manufacture, it is easy to install and save time accordingly, productivity is improved, and the ultrasonic sensor installed at any angle by XY table and turn table can be calibrated. There is an advantage to this.

1 is a perspective view showing the configuration of an automatic calibration device for a non-destructive ultrasonic inspection apparatus according to the present invention;

Figure 2 is a front view showing the configuration of the automatic calibration device for non-destructive ultrasonic inspection apparatus according to the present invention,

3 and 4 is a process of aligning the specimen and the ultrasonic sensor for calibration by the automatic calibration device according to the present invention,

5 to 7 is a process of scanning and calibrating the defect portion formed on the specimen by the automatic calibration device according to the present invention,

8 is a flowchart showing a control method of an automatic calibration device for a non-destructive ultrasonic inspection apparatus according to the present invention;

9 is a schematic perspective view of a pipe having defects or defects of the pipe.

Hereinafter, with reference to the embodiment shown in the drawings will be described in detail the configuration and operation effects of the present invention.

1 and 2 are a perspective view and a front view showing the configuration of an automatic calibration device for a non-destructive ultrasonic inspection apparatus according to the present invention.

The auto-calibration apparatus 100 for a non-destructive ultrasonic inspection apparatus according to the present invention is fixed on the production pipe 200, the XY table 10 to move in the X-axis or Y-axis direction under the control of the main controller 60 and; A turn table (20) rotatably mounted on the XY table (10); A Y-axis table 30 mounted on the turn table 20 to move in the Y-axis direction under the control of the main controller 60; A specimen fixing plate 40 installed on the Y-axis table 30 to fix the specimen 210; A plurality of ultrasonic sensors 50 for detecting defects such as cracks and holes formed in the specimen 210; The main controller controls the XY table 10 to move the specimen 210 so that the ultrasonic sensor 50 detects cracks, holes, etc. of the specimen 210 and displays them on the input and display means 70. A controller 60; It comprises an input and display means 70 for displaying a defect of the specimen 210 detected by the plurality of ultrasonic sensors 50.

XY table 10 according to the present invention and the top plate body 11 is formed in a rectangular plate shape; Four fixed legs (13) rotatably installed at four corners of the upper plate body (11) by an upper hinge (12) and having a “s” shape; It comprises a mounting means 15, such as a magnet rotatably installed by the lower hinge 14 in the lower end of the fixed leg (13).

Therefore, the XY table 10 is attached by rotating the upper hinge 12 and the lower hinge 14 to attach the four fixed legs 11 to the outer surface of the pipe 200 by four attachment means 14. The XY table 10 is fixed to the pipe 200 by being bonded by the magnetic force of the means 14.

The upper plate body 11 of the XY table 10 is formed in the form of a flat square plate and placed on the upper surface of the pipe 200, as shown in FIG. 2, the outer peripheral circle of the pipe 200, the upper plate body ( 11) is fixed to the upper surface of the pipe 200 in a horizontal state by the upper hinge 12 and four fixing legs 13 and the lower hinge 14 installed on the four corners.

Since the four fixed legs 13 are rotatably installed by the upper hinge 12 and the lower hinge 14 so as to circumscribe the outer circumferential circle of the pipe 200 and have a "S" shape, the upper plate body 11 is In the state circumferentially circumscribed to the outer circumferential circle of the round pipe 200, the angles of the four fixed legs 13 are adjusted twice by the upper hinge 12 and the lower hinge 14, so that the outer circumferential circle of the pipe 200. The upper plate body 11 may be fixed to the pipe 200 in a state in which the upper plate body 11 is attached in contact with the upper plate body 11.

The upper plate body 11 of the XY table 10 is horizontally maintained by the upper hinge 12, the four fixing legs 13, and the lower hinge 14, so that the specimen 210 is fixed to the specimen fixing plate 40. By keeping this level, the ultrasonic examination can be performed stably.

The turn table 20 is provided on the upper plate body 11 of the XY table 10, the rotation disk 21 for rotating around a rotation axis (not shown); It comprises a square support plate 22 of the square plate form integrally attached to the upper surface of the rotating disc 21.

The rotating disc 21 of the turn table 20 is rotated and then locked by a locking device (not shown), for example, by a locking device configured to hold a fixing pin on the teeth formed on the rotating disc 21. By rotating the 210, the ultrasonic wave emitted from the ultrasonic sensor 50 may be adjusted to be incident to the crack direction.

The diameter of the rotating disc 21 may be formed smaller than the upper plate body 11 of the XY table 10, the square support plate 22 installed on the rotating disc 21 is a transverse direction (crossing the pipe 200) And a rectangular plate formed longer in the Y-axis direction).

The Y-axis table 30 is formed on the turn table 20, and moves in the horizontal direction (Y-axis direction) across the pipe 200 under the control of the main controller 60 to adjust the position of the specimen 210. do.

Specimen fixing plate 40 is fixed on the Y-axis table 30 and the upper surface is formed in a flat horizontal plane so that the specimen 210 is placed on a horizontal plane, a plurality of fixing pieces 41 of the "b" shape is the specimen 210 ) Is fixed to the specimen fixing plate 40 by the fixing bolt (41a).

The plurality of ultrasonic sensors 50 are attached to the ultrasonic sensor support plate 55 attached to the ultrasonic sensor support 56 which moves under the control of the main controller 60, and the ultrasonic sensors 50 are controlled by the main controller 60. Scans the specimen 210, receives the ultrasonic wave reflected from the defect portion formed in the specimen 210 and outputs it to the main controller 60 to detect the defect portion formed in the specimen 210.

Specimen detection sensor 57 for detecting the specimen 210 is installed on the ultrasonic sensor support plate 55, the specimen detection sensor 57 may be composed of a laser sensor, an ultrasonic sensor or an electromagnetic wave sensor, the main controller According to the control of 60, the position of the specimen 210 is detected and the detection signal is output to the main controller 60.

The main controller 60 is embedded in the ultrasonic inspection apparatus 200 and is controlled by the ultrasonic sensor 50 while moving the specimen 210 by controlling the XY table 10 to detect a defective portion (eg, of the specimen 210). , Cracks, holes, etc.) are received and displayed on the input and display means 70.

The input and display means 70 may be a touch screen, a monitor, or the like. The input and display means 70 may be scanned by the ultrasonic sensor 50 under the control of the main controller 60 and reflected from the defective portion of the specimen 210 to display the detected signal on the screen. do.

3 and 4 illustrate a process of aligning the specimen and the ultrasonic sensor for calibration by the automatic calibration device according to the present invention.

The ultrasonic transducer 51 generating the ultrasonic signal from the ultrasonic sensor 50 is installed at a predetermined angle, for example, 60 °, 70 °, and the ultrasonic signal scanned by the ultrasonic transducer 51 is a specimen 210. The specimen 210 is moved by the XY table 10 so as to be scanned in the same direction as the longitudinal direction (the longitudinal direction in which the crack is formed) of the first crack 211 formed at the bottom surface.

For example, the X-axis of the specimen 210 by the XY table 10 so that the ultrasonic signal generated by the ultrasonic sensor 50 lies on an extension line in the longitudinal direction (the cracked longitudinal direction) of the first crack 211. 5 as shown in FIG. 5 in the direction and Y-axis direction, so that the ultrasonic waves scanned by the ultrasonic sensor 50 lie in the longitudinal extension line of the first crack 211.

In addition, when the longitudinal direction (the lengthwise direction in which the crack is formed) of the first crack 211 formed on the specimen 210 is different from the scanning direction (same as the X axis direction) of the ultrasonic signal, as shown in FIG. By rotating the specimen 210 in the direction of the arrow by 20), the ultrasonic wave scanned by the ultrasonic sensor 50 is adjusted to lie in the longitudinal extension line of the first crack 211.

5 to 7 illustrate a process of scanning and calibrating a defect portion formed on a specimen by the automatic calibration device according to the present invention.

In order to scan and calibrate the first crack 211 formed in the same direction as the longitudinal axis of the specimen 210, as shown in Figure 5 in the zigzag or while scanning the extension line of the longitudinal axis of the specimen 210 in the ultrasonic sensor 50 The ultrasonic signal reflected from the first crack 211 is detected and displayed on the input and display means 70 while moving while moving a predetermined distance up and down about the first crack 211.

Ultrasonic sensor 50 so that the ultrasonic signal is placed on the extension line in the direction in which the second crack 212 is formed as described above to calibrate the second crack 212 formed in the transverse direction transverse to the longitudinal axis of the specimen 210 Sort it.

At this time, the main controller 60 selects the ultrasonic sensor 50 installed in a direction suitable for scanning in the transverse direction transverse to the longitudinal axis of the specimen 210 of the plurality of ultrasonic sensors 50, the second crack 212 As shown in FIG. 6, the center of the ultrasound signal reflected by the second crack 212 is displayed on the screen of the input and display means 70.

The main controller 60 selects a third ultrasonic sensor 50c installed in a direction suitable for scanning in a direction inclined with respect to the longitudinal axis of the specimen 210 among the plurality of ultrasonic sensors 50, and selects the longitudinal axis of the specimen 210. The XY table 10 and the turn table 20 are moved to calibrate with respect to the third crack 213 formed in the inclined direction transversely so that the ultrasonic signal is placed on an extension line in the direction in which the third crack 213 is formed. The third ultrasonic sensor 50c is aligned.

Subsequently, the main controller 60 examines the ultrasonic wave while scanning the ultrasonic wave while moving from side to side, as illustrated in FIG. 7, around the third crack 213, and inputs the level of the ultrasonic signal reflected from the second crack 212. It is displayed on the screen of the display means 70.

The inspector looks at the level of the first to third cracks 211-213 displayed on the input and display means 70, and if the level that does not meet the standard is displayed, the inspector calibrates the ultrasound inspection apparatus 100 so that the reference level comes out. Continue with the calibration process.

8 is a flowchart showing a control method of an automatic calibration device for a non-destructive ultrasonic inspection apparatus according to the present invention.

In step S1, the main controller 60 checks the specimen by moving the specimen detection sensor 57 to a position corresponding to the position data input by the inspector through the input and display means 70. In step S2, the main controller 60 determines the defective portion (eg, the first crack) of the ultrasonic sensor 50 and the specimen 210 by the position data of the specimen 210 and the position data of the defective portion that the inspector inputs. (211, holes, etc.).

In this case, the alignment is a process of matching the traveling direction of the ultrasonic signal scanned by the ultrasonic sensor 50 with the longitudinal axis direction of the first crack 211 formed on the specimen 210.

In step S3, the main controller 60 checks the scan zero point at which the ultrasonic sensor 50 starts scanning, scans and scans the ultrasonic signal while advancing the ultrasonic sensor 50 toward the defective portion.

In step S4, the main controller 60 performs a zigzag scan around the defective portion near the defective portion (for example, the first crack 211, the hole, etc.) (see FIGS. 5 to 7).

In step S5, the main controller 60 stores, in the internal memory (not shown), the reflection position where the ultrasonic signal is reflected during the scanning of the defective portion, and in step S6, displays the level of the reflected signal on the input and display means 70. do.

In step S7, it is determined whether there is a defective portion to be calibrated next, and if there is, the flow advances to step S2, and if not, the automatic calibration program ends.

The embodiments described above and illustrated in the drawings are only one embodiment for carrying out the present invention, and should not be construed as limiting the technical spirit of the present invention. The scope of protection of the present invention is defined only by the matters set forth in the claims below, and the embodiments which have been improved and changed without departing from the gist of the present invention will be apparent to those skilled in the art. It belongs to the protection scope of the present invention.

Claims

An XY table fixed on the pipe in production and moving in the X-axis or Y-axis direction;

A turn table rotatably mounted on the XY table;

A specimen fixing plate installed on the turn table to fix the specimen;

A plurality of ultrasonic sensors for detecting defects formed in the specimen;

A main controller controlling the XY table, the turn table, and the Y-axis table to move the specimen so that the ultrasonic sensor detects a defect of the specimen and displays the input and display means;

And an input and display means for displaying a defect of the specimen detected by the plurality of ultrasonic sensors.
The method of claim 1,

And a Y-axis table installed between the turn table and the specimen fixing plate and moving in the horizontal direction (Y-axis direction) across the pipe under the control of the main controller to adjust the position of the specimen. Automatic calibration device for non-destructive ultrasonic inspection device.
The method according to claim 1 or 2,

The XY table includes a plurality of fixed legs to which a plurality of hinges are attached to both ends and is attached to the outer surface of the pipe by an attachment means that is defective by a hinge attached to the lower end of the fixed leg so that the XY table is Auto-calibration device for a non-destructive ultrasonic inspection device, characterized in that configured to be fixed to the pipe.
The method of claim 3, wherein

The XY table has a top plate body formed in a rectangular plate shape; Four fixed legs rotatably installed at four corners of the upper plate body by an upper hinge and having a “s” shape; Auto-calibration device for a non-destructive ultrasonic inspection device, characterized in that it comprises an attachment means rotatably installed by a lower hinge to the lower end of the fixed leg.
The method of claim 4, wherein

The upper plate body of the XY table is horizontally maintained by the upper hinge, the four fixing legs and the lower hinge so that the specimen fixed to the specimen holding plate is horizontal so that the ultrasonic inspection can be stably executed. Automatic calibration device for non-destructive ultrasonic inspection device.
The method according to claim 1 or 2,

The turn table is installed on the upper plate body of the XY table, and rotates around the axis of rotation; Auto-calibration device for a non-destructive ultrasonic inspection device characterized in that it comprises a rectangular support plate in the form of a square plate integrally attached to the upper surface of the rotating disk.
The method of claim 6,

The rotating disk of the turn table is rotated by the locking device after the rotation by rotating the specimen so that the ultrasonic wave emitted from the ultrasonic sensor is configured to be adjusted so as to be incident in the direction of the defect for the non-destructive ultrasonic inspection device Autocalibration device.
The method according to claim 1 or 2,

The specimen fixing plate is formed so that the upper surface is a flat horizontal plane so that the specimen is placed on the horizontal plane, a plurality of "a" shaped pieces are configured to fix the specimen to the specimen fixing plate by fixing bolts Automatic calibration device for nondestructive ultrasonic inspection device.
The method according to claim 1 or 2,

The plurality of ultrasonic sensors are attached to an ultrasonic sensor support plate attached to an ultrasonic sensor support that moves according to the control of the main controller, and scans the ultrasonic waves onto the specimen under the control of the main controller, and reflects the defects formed on the specimen. Receiving the ultrasonic wave to be output to the main controller, the auto-calibration device for a non-destructive ultrasonic inspection device, characterized in that configured to detect the defective portion formed on the specimen.
Checking, by the main controller, the specimen by moving the specimen detection sensor to a position corresponding to the position data input by the inspector through input and display means;

Aligning, by the main controller, the ultrasonic sensor and the specimen defective portion by the position data of the specimen and the position data of the defect portion input by the inspector;

Checking, by the main controller, a scan zero point at which the ultrasonic sensor starts scanning, scanning and scanning an ultrasonic signal while advancing the ultrasonic sensor toward a defective portion input by the inspector;

The main controller performing a zigzag scan around the defective portion near the defective portion input by the inspector;

And the main controller storing the reflection position where the ultrasonic signal is reflected during the scanning of the defective portion in the internal memory and displaying the level of the reflected signal on the display means. Control method of the device.