JPS60135758A - Method and device for flaw detection of metallic surface - Google Patents

Abstract

PURPOSE:To detect defects on surfaces of a metallic pipe and a metallic plate with less noises by moving plural parallel arranged detectors and preventing them from oscillating. CONSTITUTION:Plural parallel detectors 20 are arranged on the machine table 1 of a flaw detector A and adjusted upward and downward by a fitting device 41 to approach the metallic surface. Further, the machine table 1 is equipped with a running machine 10 having caterpillars and it is driven forth and back by a centralized controller 17. Further, a television camera 11 and a lighting lamp 12 are provided atop of the machine table 1 and an image is displayed on a cathode-ray tube 16. This flaw detector A is loaded in the metallic pipe 3 and the detector 20 is advanced over a lock through the television camera 11 to display a defect in the metallic pipe surface on an output device 6. The detector 20 uses an ultrasonic wave, laser light, etc. Therefore, there is no mechanically movable part which makes a sweep on the inspected surface and inspection is carried out by advancing the detectors 20 which are arranged closely in parallel simultaneously, so the inspection is performed with less noise and the inspecting device is reduced in weight.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for inspecting defects such as corrosion and cracks occurring on the surface of metal pipes or metal plates. □ In order to detect defects on the surface of a metal tube, the applicant pivots a swinging rod with a magnetic flaw detector attached to the tip to a machine base equipped with a traveling mechanism, and swings the swinging rod inside the tube. We have already proposed a device that inspects metal surfaces by running the machine while moving the machine and moving the detector in the axial direction of the tube while swinging back and forth in the circumferential direction of the tube (Japanese Patent Laid-Open No. 57-14'444'4). ). □ This device has the advantage of being able to automatically inspect the inner surface of chopsticks.
,, :)1 However, since the machine base is equipped with a rocking device to drive the rocking rod and the rocking rod is made to reciprocate, the vibrations associated with the rocking motion are detected. This is transmitted to the detector and causes noise to be included in the detected data. Furthermore, the motor and link mechanism that make up the swinging device make the inspection device itself larger and heavier, making it cumbersome to transport the inspection device and insert it into the pipe to be inspected. Furthermore, do not leak on the pipe surface.
<Condolences only. , there is a simple constant relationship between the reciprocating speed of the detector, the running speed of the machine, and the
The maximum distance the machine can travel per shake is limited to the diameter of the detector.

In order to improve the efficiency of inspection work, it is necessary to increase the reciprocating speed of the detector, but the speed at which the swinging rod can be driven back and forth by the swinging device is at most 400 rpm, and the speed of inspection work is limited due to the speed of the swinging device. up was constrained by the rocking speed of the detector.

The present invention is directed to a method of inspecting a metal surface without shaking a flaw detector and with fewer mechanically moving parts, and to an apparatus used to carry out the method.

In the flaw detection method of the present invention, a plurality of detectors for detecting abnormalities on a metal surface are arranged in parallel in a track perpendicular to the inspection direction of the surface to be inspected, and the surface to be inspected and the detectors are aligned in the inspection direction. The output of each detector is displayed on an output device by relatively moving the detector.

The flaw detection device of the present invention includes a detection device (2) in which a plurality of detectors (2O) are arranged close to each other in parallel, and the detection device (2) is attached to a mechanism [1] so that it can be raised and lowered. Detector (20
) inspection surface 0870↑79 ;J: L r ;7i
(oJ 6E ft l, "17" Inspect the mounting device (4), the detection device (2), and the surface to be inspected. Drive,
and an output device (6) that simultaneously outputs the outputs of the respective detectors (additionally) to a display screen.

The present invention does not have mechanical movable parts to sweep the inspection surface, and inspection can be performed simply by moving the detectors arranged closely in parallel at the same time. Therefore, detection data with less noise can be obtained, and the inspection equipment can be lightweight. Moreover, it has the excellent effect of shortening the inspection time by increasing the advancing speed of the inspection device.

As shown in FIGS. 1 and 2, the device of the present invention includes a machine base (
1) A detection device (2), a television camera (11) for photographing the inspection area, and a lighting lamp +121 are installed in the front of the machine.
The machine (1) is inserted into the pipe (3) to be inspected, and the detection device (2) is moved through the pipe by driving the traveling mechanism (10).
,) ζKyote inspection, at the same time 1 TV camera til)
i Photograph the inspection range.

The detection device (2) is a feature of the present invention, in which a plurality of detectors (20) for detecting abnormalities on metal surfaces are attached to a mounting plate (40) that is curved to match the curved surface of the pipe. Figure 4a
They are arranged closely in rows or in a staggered pattern as shown in Figure 4, and each detector emit ultrasonic waves, laser beams, radio waves, etc. to the inspection surface and analyze the reflected signals. 6" type or °゛'1 High frequency! Generates an alternating magnetic field to generate an overcurrent on the tube wall. 1. Measures the back electromotive force generated in the coil due to self-induction or mutual induction of the coil, and detects corrosion or cracks in the tube wall. A pair of guide rods +411 (
411 and a screw shaft (42) rotatably supported at both ends are arranged parallel to each other, and the mounting plate (40) is connected to the guide rod (41).
It is equipped with a screw shaft (44) that has a bracket and throat that fits into the screw shaft (44), and is installed by turning the screw shaft (42). The board (4″o) is the guide rod +
41+ +2 Move up and down while being guided, detecting device (
2) Adjust the distance between the tube and the surface, that is, the lift-off. The rotation of the screw shaft (42) is achieved by connecting a rotary drive device (13) such as a pulse motor provided on the machine base (1) to a rotating shaft (14) that is horizontally supported on the machine base. Attachment for coupling the other end of the shaft (14) to said threaded shaft (42) by means of a gear train (15) to adjust the lift-off of the controlled royal rotation sensing device (2) of the retrospective drive (13). The device (4) is
It goes without saying that the configuration is not limited to the above configuration, and that various configurations can be used. The lift-off adjustment can also be performed by forming a detection □ off signal from the detection device (2) during the inspection and transmitting it to the rotary drive machine (13) to keep the lift-off constant at all times. Alternatively, the lift-off of the detection device can be manually set in advance and the lift-off can be fixed during the inspection.

The machine base (1) is loaded with storage batteries or connected to a power line from the outside to energize a drive device composed of a motor or the like to drive the traveling mechanism (10) and move it through the pipe. Also, when the object to be inspected is a strip-shaped or irregularly shaped metal plate, fix the machine base and
The metal plate is inspected while being transported by a drive device.

The output of each detector of the detection device (2) can be displayed and recorded on the output device (6) provided in the monitor room outside the tube through the signal line connected to each detector, but in this case,
The number of signal lines required is equal to the number of detectors, and the cables connected to the machine stand are too thick.

Furthermore, there is a risk that non-destructive inspection signals such as magnetic fields and ultrasonic waves emitted from two adjacent detectors +20) +20) may interfere with each other and produce erroneous detection signals.

FIG. 3 shows a configuration in which detection signals from each detector (2O) are transmitted to an output device (6) in an external monitoring room using a single cable line based on a time-sharing method.

The detection device (2) has a plurality of eddy current flaw detectors arranged, and an excitation coil (21) and a detection coil (22) of each detector (20).
) are respectively the first and second multiplexers t23) +24
) are connected to each multiplexer (23+ +24
) of the plurality of detectors (20) by controlling them by a common clock pulse generator (25).
21) and the detection coil (22) are operated simultaneously to generate an eddy current on the inspection surface and detect a flaw signal. Multiplexer +23) (24) is the clock pulse generator (
Since the detector (2O) to be activated is switched every time a clock pulse from 25) is manually applied, mutual interference does not occur between adjacent detectors.

The switching speed of the detector is determined by the period of the clock pulse. The detectors (20) were switched one after another, and when all the detectors had been switched, the detector was swung once along the tube wall i in the inspection device previously proposed by the applicant. It corresponds to that. And since the period of the clock pulse can be set arbitrarily by adjusting the clock pulse generator (25), the rocking speed of the detector was limited to 400 rpm in the previous inspection equipment, but it is now possible to The metal surface can be scanned by switching the detector at any of the above high speeds, and therefore the inspection efficiency is significantly improved by increasing the relative movement speed between the machine and the metal surface.

The excitation coil (21) of each detector (20) is connected in parallel with the oscillation circuit (2) via the first multiplexer (2), and the oscillation circuit (21) is connected in parallel by switching the multiplexer.
A high frequency voltage of about 5'0 KH2 is applied to the excitation coil 4 which is in conduction to generate an alternating magnetic field and an eddy current on the metal surface. The detection coil (221) is connected in parallel with the differential amplifier (2) via the second multiplexer (24), and by switching the second multiplexer,
An induced current is generated corresponding to the excitation coil (21) conducting to the oscillation circuit (26), and this output signal is input to a synchronous detector for synchronous detection. Synchronous detection utilizes the phenomenon that the output signal □ of the detection coil (22) is further out of phase at a defective location on the metal surface than at a normal location on the metal surface, and is output from the oscillation circuit (A). The phase of the excitation current is set by the phase shifter (29) in a direction in which the phase at the normal part of the metal surface is shifted by 90', and the flaw signal in the output signal of the differential amplifier fin is detected. L/Flaw signal 0"; Fuji defect/Comparison 4%, )51) and 1/0 A flaw signal indicating a defect on the surface is output. The flaw signal output from the detection device (2) is an optical signal 1. .The signal is modulated into a microwave signal or an electric signal and transmitted to a monitor room outside the area through the transmission circuit (5).The monitor room demodulates the signal transmitted from the machine and converts it into an s/ p conversion circuit (60)
The flaw signals for each detector are separated and displayed on the output device.

The output device (6) is as shown in Fig. 5 (with the horizontal axis being the inspection surface □
By setting the width of the detector to the width of The shape of the tube surface can be expressed by the shape of the line.

As another example of the output device (6), the flaw signal is again divided into outputs for each detector by the S/P conversion circuit (60), and the sixth
As shown in the figure, the outputs of each detector can be expressed simultaneously with the horizontal axis as the time axis.

The flaw signal data displayed on the output device (6) is simultaneously recorded in the recording device (61), and the surface condition of the inspection surface photographed by the television camera (11) is sent to the monitor room via the transmission circuit (5). Monitor the metal surface by displaying it on a monitor TV f16).

For the machine (1) loaded into the pipe, the traveling mechanism t is controlled by the operation of the central control device (17) in the monitor room.
It is also possible to command and control the drive device 101 to advance, stop, and retreat, and also adjust the lift-off setting of the detection device mounting device (4) by external operation.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the implementation status of the present invention, and FIG.
3 is a signal processing circuit diagram of the detection device, FIGS. 4a and b are explanatory diagrams showing the arrangement of the detectors in the detection device, and FIGS. 5 and 6 are diagrams of the output device. It is an output diagram on a display screen.

Claims (1)

[Claims] ■ Multiple detectors for inspecting abnormalities on metal surfaces are arranged closely in parallel, and the surface to be inspected and the detectors are moved relative to each other in a direction orthogonal to the direction in which the detectors are arranged in parallel. A flaw detection method for a metal surface, characterized in that the output of each detector is displayed on an output device. (2) The flaw detection method according to claim 1, wherein the output of each detector is arranged in the vertical or horizontal direction of the display surface of the output device, and the output amount is expressed in a direction orthogonal thereto. (2) The flaw detection method according to claim 1, wherein the outputs of the respective detectors are arranged in the vertical axis direction on the display surface of the output device and are simultaneously swept and displayed with the horizontal axis as the time axis. ■ A detection device with multiple detectors arranged close together in parallel,
a mounting device that mounts the detection device on a machine base so that it can be raised and lowered so that the inspection surface of the detection device faces the metal surface and adjusts lift-off; 1. A flaw detection device for a metal surface, characterized in that it is constituted by a drive device that moves orthogonally relative to each other, and an output device that simultaneously outputs the output of each detector to a display screen. (2) The inspection device according to claim 4, wherein the detectors of the inspection device are arranged in a line. (2) The inspection device according to claim 4, wherein the detectors of the inspection device are arranged in a staggered manner with alternating shifts. (2) The inspection device according to claim 4, wherein the machine base is equipped with a traveling mechanism, and the drive device drives the traveling device.