JPH06258295A - Welding seam inspection equipment - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a welding seam inspection device capable of inspecting a seam formed over a wide range in a short time and in detail and easily operating. [Structure] Eddy current flaw detection sensor 6 and ultrasonic flaw detection sensor 9 mounted on sensor unit 3 traveling along welding seam 5, and eddy current flaw detection sensor 6 detects a defect of a certain size or more from welding seam 5 Then, the traveling control means 41 for stopping the sensor unit 3, the scanning means 43 for scanning the ultrasonic flaw detection sensor 9 at this stop position, and the measurement result of the ultrasonic flaw detection sensor 9 are used to determine whether the defect is at a significant level. The determination means 49 for determination is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-destructive inspection apparatus for welded joints, and in particular, a welder capable of inspecting joints formed over a wide area in a short time and in detail and easily operated. The present invention relates to a seam inspection device.

[0002]

2. Description of the Related Art A thin steel sheet called a membrane is attached as a lining to a tank for storing gas and other fluids. In addition to the tank, the surface of other structures is often formed by stretching a thin plate of metal or the like. Since a tank or a building has a large surface, a thin plate having an appropriate size can be joined by welding so that the membrane can be stretched over the large surface. Weld seams are formed in the membrane.

Inspection of weld seams is important to ensure the strength of the structure. Above all, the membrane of the tank is intended to prevent leakage of gas and the like, and therefore the joint thereof should not be defective. Therefore, the inspection of the seam of the welding of the membrane is very important.

[0004] Conventionally, in general, for inspection of welding seams, in addition to visual inspection, a eddy current flaw detection test or an ultrasonic flaw detection test is employed. The eddy current flaw detection test is a test that utilizes the fact that when an eddy current is generated in an object by the action of a magnetic field, the difference between the sound part and the defective part of the object can be discriminated from the state of the eddy current. Further, the ultrasonic flaw detection test is a test that utilizes the fact that when ultrasonic waves are propagated to an object, the difference between a sound portion and a defective portion of the object can be discriminated from the propagation state. All of the tests are non-destructive tests and can be performed from one side of the object, and therefore are suitable test methods for the membrane stretched on the surface of the tank or the building.

[0005]

However, each of the conventional inspection methods has problems.

In human inspection such as visual inspection, a large number of manpower is required when the inspection object covers a wide range. On the other hand, it cannot be carried out in large numbers because the inspection contents vary depending on the skill level. Further, an inspection method that causes such individual differences is not industrially preferable.

The eddy current flaw detection test can detect the presence and size of defects quantitatively to some extent. Moreover, there is an advantage that the inspection can be performed while moving the inspection location and the inspection speed is high. However, the detailed state of the defect cannot be detected. Since the detailed state of the defect cannot be detected, it is difficult to determine whether the defect requires repair.

The ultrasonic flaw detection test allows detailed examination of the shape, size, etc. of the defect by changing the scanning method of ultrasonic waves, etc., but it is necessary to stay in only one place, and only one place It takes time to inspect. For this reason, when the inspection target covers a wide range such as a tank, it takes a lot of time to inspect all of them.

The eddy current flaw detection test and the ultrasonic flaw detection test are
The result of detection of the defect by the sensor is taken into the equipment as a signal and the signal is displayed. Whether the defect needs to be repaired by looking at the display result, whether it is necessary to record / report It is a person who decides whether or not. Individual differences appear here.

In any of the inspection methods, it is necessary to keep an inspection record and leave a mark on the defective portion so that repair can be performed after the inspection, and the work involved in such inspection is complicated. .

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above problems and to provide a welding seam inspection device capable of inspecting a seam formed over a wide range in a short time and in detail and easily operating. is there.

[0012]

SUMMARY OF THE INVENTION To achieve the above object, the present invention provides a eddy current flaw detection sensor and an ultrasonic flaw detection sensor mounted on a sensor unit traveling along a welding seam, and the eddy current flaw detection sensor is welded. When a defect of a certain size or more is detected from the seam of the traveling control means for stopping the sensor unit, a scanning means for scanning the ultrasonic flaw detection sensor at this stop position, and a defect due to the measurement result of the ultrasonic flaw detection sensor. A determination means for determining whether or not the level is significant is provided.

[0013]

With the above structure, the sensor unit can travel along the seam, so that the eddy current flaw detection sensor and the ultrasonic flaw detection sensor mounted on the sensor unit can always inspect the seam. First, the sensor unit is caused to travel along the joint while operating the eddy current flaw detection sensor. When the eddy current flaw detection sensor detects a defect of a certain size or larger, the traveling control means stops the sensor unit. When the sensor unit stops, the scanning means in turn scans the ultrasonic flaw detection sensor. That is, the ultrasonic flaw detection sensor reciprocates with respect to the joint to measure the details of the defect. The determination means determines whether or not the defect is at a significant level based on this measurement result.

Until a defect of a certain size or larger is detected, the inspection is advanced by eddy current flaw detection while the sensor unit is running. Since most welding seams are normal, the sensor unit rarely stops.
Even if the seam covers a wide range, the inspection time is short. In addition, since a defect having a certain size or more is inspected in detail by ultrasonic flaw detection, it can be correctly determined whether or not the defect is at a significant level. Moreover, since this determination is performed by the determination means, there is no individual difference.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

As shown in FIG. 1, a welding seam inspection apparatus 1 has a sensor unit 3 which can be self-propelled on a plate 2 which is seamed by welding. The plate 2 is, for example, a membrane lined on the side or bottom of the tank, while
The sensor unit 3 includes wheels 4 having a suction mechanism, and can travel on the plate 2 even if the plate 2 is not horizontal. The weld seam 5 is shown in cross section. Sensor unit 3
Can run along this seam 5. In order to drive the sensor unit 3 along the joint 5,
A guide rail for guiding the wheels 4 may be provided, or a signal from an eddy current flaw detection sensor, which will be described later, may be used to control so as not to come off the joint 5.

A part of the sensor unit 3 has a joint 5
The eddy current flaw detection sensor 6 is mounted on that portion. The eddy current flaw detection sensor 6 includes a coil 7a that generates a constant magnetic field and a coil 7 that detects the magnetic field.
b is wound around the same core 8. Core 8
Are arranged so as to face the joint 5 to be detected. The magnetic field generated by the coil 7a generates an eddy current at the joint 5, and the magnetic field generated by the eddy current is detected by the coil 7b. Since the magnitude and the phase of the detected magnetic field differ depending on the state of the seam 5, the eddy current flaw detection sensor 6 can extract a signal indicating the feature of the defect of the seam 5.

An ultrasonic flaw detection sensor 9 is mounted on the portion of the sensor unit 3 located on the plate 2. The ultrasonic flaw detection sensor 9 is arranged so that its detection surface 9 a is in contact with the plate 2, and is configured to be able to move on the plate 2 at a right angle to the traveling direction of the sensor unit 3. The ultrasonic flaw detection sensor 9 includes an ultrasonic wave generator facing the detection surface 9a and a receiver, and the plate 2 from the detection surface 9a.
Ultrasonic waves can be sent out at a constant angle. This ultrasonic wave has a straight traveling property and is reflected by the opposite surface of the plate 2, so that it can reach the joint 5. In the joint 5, different reflected waves are obtained depending on the shape and the defect. Then, the reflected wave returned to the detection surface 9a can be detected. Since the reflected wave is disturbed by the state of the seam 5, the ultrasonic flaw detection sensor 9 can detect the state of the seam 5. Further, the ultrasonic flaw detection sensor 9 can send out ultrasonic waves so as to scan the entire joint 5 by reciprocating with respect to the joint 5. The signal obtained from the reciprocating ultrasonic flaw detection sensor 9 is a scanning signal in the cross section of the seam 5 and indicates a detailed state such as the shape and size of the defect.

As shown in FIG. 4, the sensor unit 3 includes an actuator for driving the wheels 4, a travel control means 41 for running / stopping the sensor unit 3, a distance meter 42 for measuring the travel distance, A scanning means 43 composed of an actuator for reciprocating the ultrasonic flaw detection sensor 9, a marker 44 for marking a defect position with paint or the like, and an actuator 45 thereof are mounted.

The control device is a device for running / stopping the sensor unit 3, monitoring the eddy current flaw detection sensor 6, reciprocating / stopping the ultrasonic flaw detection sensor 9, monitoring the ultrasonic flaw detection sensor 9 and determining a significant level of a defect. Is. In this embodiment, the structure is as shown in FIG.

As shown in FIG. 2, the controller 20 includes
The caster 21 is configured to be movable on a floor surface 22 such as the bottom of the tank. The control device 20 includes an operation panel 23 for an operator, a screen display device (CRT) 24 for displaying operation contents and inspection data, and a recording device (FDD: floppy disk drive) 25 for writing and referring to inspection data. A printer 27 for printing a report (O / P sheet) 26 of the determination result, and other display lamps 28 are provided. These input / output devices are controlled by the microcomputer in the control device 20.

The control unit 20 is composed of the blocks shown in FIG. That is, the ET device 46 that processes the output of the eddy current flaw detection sensor 6, the first comparison circuit 47 that compares the detection signal of the ET device with a threshold value, the UT device 48 that processes the output of the ultrasonic flaw detection sensor 9, and the UT device Second comparison circuit (significance level determination means) 4 for comparing the detection signal with a threshold value 4
9. A built-in interface 51 interposed between these comparison circuits and the microcomputer 50. Each input / output device is also connected to the microcomputer 50 via the interface 51.

An extendable cable 2 for transmitting and receiving signals and power is provided between the control device 20 and the sensor unit 3.
It is tied at 9. Since the cable 29 is expandable and contractible, the sensor unit 3 can freely move within a certain fixed range.

Next, the operation of the embodiment will be described.

FIG. 3 shows an example of the screen of the CRT 24. This screen 30 shows the progress of the inspection of the seam of welding. Magnitude signal 31 representing the size of the defect by voltage
And a defect level signal 32 representing the level of the defect in voltage are displayed over time. In addition, each signal 3
The thresholds 33 and 34 are also displayed in 1 and 32, respectively.

The control device 20 firstly detects the eddy current flaw detection sensor 6
While operating, the traveling control means 41 causes the sensor unit 3 to travel along the joint 5. Sensor unit 3
When the vehicle runs along the seam, the eddy current flaw detection sensor 6 sends a sensor signal along the seam 5 to the control device 20. This sensor signal is converted into a size signal 31 by the ET device 46 and displayed on the CRT 24. During this period, the first comparison circuit 47 in the control device 20 outputs the magnitude signal 31 to the threshold 33.
We are monitoring whether or not it exceeds. This threshold value is empirically determined from the correspondence relationship between the output of the eddy current flaw detection sensor 6 and the actual defect state. Therefore, when the magnitude signal 31 exceeds the threshold value 33, it indicates that there is a defect of a certain magnitude or more that requires a detailed inspection. In the example of FIG. 3, defects 35a, 35b, 35c
Of these, 35b and 35c exceed the threshold value 33. On the other hand, the defect 35a is considered to have a negligible size. In this way, the presence or absence of defects of a certain size or more is detected.

When a defect of a certain size or more is detected, the control device 20 displays the fact on the display lamp 28, and the traveling control means 41 stops the sensor unit 3. Then, on the spot, the ultrasonic flaw detection sensor 9 is used by the scanning means 43.
Is moved back and forth with respect to the seam 5. The ultrasonic flaw detection sensor 9 sends out ultrasonic waves so as to scan the entire seam 5 as shown by the solid line and the two-dot chain line arrow in FIG. 1 to measure the details of the defect. The result of the measurement is converted by the UT device 48 into a defect level signal 32 based on the size and shape of the defect and displayed on the CRT 24. Control device 2
The second comparison circuit (determination means) 49 in 0 monitors whether the defect level signal 32 exceeds the threshold value 34. This threshold value 34 is empirically determined from the correspondence relationship between the output of the ultrasonic flaw detection sensor 9 and the actual defect state. Therefore, the defect level signal 32 is equal to the threshold value 3
When the number exceeds 4, it means that the defect has a significant level that needs to be repaired or needs to be recorded and reported. In the example of FIG. 3, the defect 35b exceeds the threshold value 34. Although the defect 35c has a certain size, it does not reach the significant level.
In this way, it is determined whether the defect is at a significant level.

When the controller 20 determines that the defect is at a significant level, the controller 20 displays that fact on the display lamp 28, drives the marker 44 by the actuator 45, and places a mark such as paint in the vicinity where the defect is found. . Further, inspection data such as position data based on the distance meter 42, signal data detected by the sensors 6 and 9, determination content data, and the like are created, and the inspection data is displayed on the CRT 24 as necessary and recorded in the FDD 25. And printed on the O / P sheet 26. Then, the inspection by the eddy current flaw detection sensor 6 is restarted.

Until a defect of a certain size or more is detected, the inspection is advanced by eddy current flaw detection while the sensor unit 3 is running. Most of the normal welding seams 5 are normal, so the sensor unit 3 rarely stops. Therefore, the inspection time is short even if the seam 5 covers a wide range. In addition, since a defect having a certain size or more is inspected in detail by ultrasonic flaw detection, it can be correctly determined whether or not the defect is at a significant level. Moreover, since this determination is performed by the control device 20, there is no individual difference. And CRT24, FD
Since the input / output devices such as the D25 and the printer 27 are used only when necessary, there is no waste. Further, since the mark by the marker 44 and the record by the FDD 25 are left, the repair efficiency is improved.

In this embodiment, a threshold value is used to determine the significance level and the threshold values 33 and 34 are used.
The value obtained empirically was used for setting
It is also possible to utilize the fact that the control device 20 has a microcomputer and a recording device so that the determination method and the determination criterion are learned based on the past accumulated data.

[0031]

The present invention exhibits the following excellent effects.

(1) Since most of normal areas are quickly inspected by eddy current flaw detection and suspicious areas are inspected in detail by sonic flaw detection, the inspection time is shortened and precise inspection is possible. The inspection of the membrane of a large tank can be performed accurately in a short time.

(2) Since the presence / absence of a defect and the determination of the significant level are quantified and automated, there is no individual difference, the reliability of the inspection is enhanced, and the operation is simplified, and even an unskilled person can perform the inspection. .

(3) Since the sensor unit is run and inspected, it is simple and easy for a person to apply the sensor to the joint. In addition, people do not have to climb high places or travel long distances, and are safe and tired.

[Brief description of drawings]

FIG. 1 is an enlarged view of a sensor unit showing an embodiment of the present invention.

FIG. 2 is an external view of a welding seam inspection device showing an embodiment of the present invention.

FIG. 3 is a waveform diagram of a display screen of a control device showing an embodiment of the present invention.

FIG. 4 is an internal block diagram of a sensor unit and a control device showing an embodiment of the present invention.

[Explanation of reference numerals] 3 sensor unit 5 seam 6 eddy current flaw detection sensor 9 ultrasonic flaw detection sensor 41 traveling control means 43 scanning means 49 determination means

Claims (1)

[Claims] 1. An eddy current flaw detection sensor and an ultrasonic flaw detection sensor mounted on a sensor unit traveling along a welding seam, and a sensor unit when the eddy current flaw detection sensor detects a defect of a certain size or more from the welding seam. A traveling control means for stopping the operation, a scanning means for scanning the ultrasonic flaw detection sensor at the stop position, and a determination means for determining whether or not the defect is at a significant level based on the measurement result of the ultrasonic flaw detection sensor. Welding seam inspection device.