JPS6091254A - Apparatus for inspecting metal surface - Google Patents

Abstract

PURPOSE:To make it possible to perform the inspection of a metal surface easily and accurately, by constituting the titled apparatus from a main sensor for detecting the crack of the metal surface, first and second sensors for detecting the approach of the main sensor to the metal surface and a control apparatus thereof. CONSTITUTION:A main sensor 7 for detecting the defect such as the crack or corrosion of a metal surface and a sensor support stand 3 having said sensor attached thereto in an up-and-down movable manner. In addition, a first sensor 5 of which the length is set so as to be shorter than the predetermined distance between the main sensor 7 and the metal surface and a second sensor 6 of which the length is set so as to be longer than the distance therebetween are provided in order to detect the approach of the main sensor to the metal surface and a control apparatus 4 of said sensors is provided. Electromagnetic induction coils are mounted in all sensors 5, 6, 7 and a magnetic field due to a high frequency current is exerted upon the metal surface to detect the change in the voltage thereof while the main sensor 1 is allowed to swing reciprocally in the surface crossing the running direction of the machine stand at right angles. By this mechanism, inspection becomes easy and an actual condition can be accurately determined.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved device ρ for detecting abnormalities such as corrosion and cracks on metal surfaces such as metal pipes and plates.

2. Description of the Related Art Inspection devices have conventionally been used that detect abnormalities on metal surfaces using electromagnetic induction coils. This involves applying a magnetic field to the metal surface through a high-frequency current through a coil, generating eddy currents, and detecting changes in induced voltage due to disturbances in the eddy currents at defective locations to determine the presence of defects.

In this inspection method, it was necessary to maintain a constant height (lift-off) from the metal surface to be inspected to the coil. This is because if the lift-off is not kept constant, it becomes unclear whether the output change is due to a defect in the metal surface or a lift-off fluctuation, which impairs the reliability of the data.

The sensor of the inspection device is placed 2 to 5+++ meters away from the inspection surface, and this height is maintained during the inspection to detect fluctuations in induced voltage due to scratches on the metal surface, but due to the surface condition and vibration during sensor scanning. Some variation in lift-off is always present, making it difficult to identify defects in the metal surface from the detected data.

The present invention discloses an inspection device that can eliminate as much as possible coil lift-off fluctuations when inspecting metal surfaces using electromagnetic induction coils.

In the present invention, a main sensor for detecting defects on a metal surface and first and second sensors for detecting proximity to the metal surface are attached to a sensor support base, and the first and second sensors each detect proximity to the metal surface. The distance is set slightly shorter on one side and slightly longer on the other than the predetermined distance range between the main sensor and the metal surface, and the sensor support is placed on the machine base so as to be able to move downward relative to the metal surface for control. When both the first and second sensors simultaneously detect approaching a metal surface, the control device operates in the direction of raising the sensor support base, and both the first and second sensors are in a non-detecting state. When this occurs, the control device operates to lower the sensor support base, and maintains the lift-off within a predetermined range by performing an inspection with only one of the first and second sensors in the detection state and the other in the non-detection state. It is possible.

The drawing shows an inspection system in which the inspection device of the present invention is attached to the front of a self-propelled vehicle that automatically travels inside the pipe, and the sensor is moved back and forth in the circumferential direction of the pipe while moving in the axial direction of the pipe in order to find abnormalities on the inner surface of the pipe. Although an example in which a surface is scanned is shown, the present invention is not limited to this, and the present invention is not limited to this, but the present invention can be used to inspect the surface of a continuously conveyed gutter-shaped or flat-shaped strip by attaching the device to a fixed stand and moving the sensor back and forth. You can also do that.

The self-propelled vehicle (1) equipped with an inspection unit is further equipped with a video camera (10) and a lighting device (11) in front, and monitors the tube surface with an imaging device installed outside the tube while monitoring the inspection unit. Data is automatically recorded on a recording device (12J) that can be loaded onto a self-propelled vehicle or installed in a motor control room.

The self-propelled vehicle (1) has wheel rows (131 (13)
), and a rotation adjustment device (16) that finely adjusts the difference in rotational speed between the left and right wheel trains by switching the rotation of the loading motor (14) using a transmission (15) in response to a remote control signal from the monitoring room. The signal is then transmitted to the left and right wheel trains.
Controls forward, stop, and reverse driving of self-propelled vehicles.

An inspection device is attached to the front of the self-propelled vehicle (1) and is driven by the transmission (15).

Since the self-propelled vehicle (1) transports the inspection equipment, a suitable structure has been selected and the motor (14) of the trolley equipped with it has been selected.
As a power source for the motor, a battery (1η) is loaded, but it is not limited to this, and a power line is installed in parallel to the cable (19) of the cable reel (18) installed on the trolley, and the motor (14) is driven by an external power source. Also possible.

The inspection device is installed on the mounting base (2) at the front of the self-propelled vehicle, and the sensor support base (3) is fitted to the guide post (21) installed on the mounting base (2) so that it can move up and down. ing.

Various mechanisms are possible for controlling the height of the sensor support (3), the drawings and the following description being one example thereof.

A control shaft (34) with a screw shaft (31) at the top and two bevel gears (3 (2), (33) at the bottom) is freely rotatably erected on the mounting base (2) to form a sensor support base. (3), is attached to the sensor support stand (3), and has a threaded surface on its inner surface.The sensor is supported by engaging the threaded shaft (31) of the control shaft (:!A). Political integration of platform (3) (2)
The sensor is supported by connecting the control device (4) to the two bevel gears +321 and +33) provided at the bottom of the control shaft (-) and driving the control shaft (-) forward and reverse rotation. The height of the stand (3) from the mounting base (2) can be controlled.

The control device (4) has an output shaft (42) of a control motor (41).
1 is connected to two rotating shafts (43) and (44), and a control gear (47 ) +48) and meshed with the bevel gear (33) on the control shaft -).

Since each rotating shaft (4 (to) (44)) rotates in opposite directions, by switching the clutch (45) (461), the rotation of either one of the rotating shafts (43) (44) is controlled by the control shaft ( The height of the sensor support base (3) is adjusted by controlling the rotation and rotation direction of the control shaft (3).

The sensor support stand (3) has the upper end of a rotating rod (361) supported by a bearing device (screw) so as to be swingable in a direction perpendicular to the traveling direction of the self-propelled vehicle.

The rotating rod (36) has a main sensor (7) at its lower end that detects defects on the metal surface, and a first and second sensor that detects when the distance to the metal surface approaches a predetermined distance in front of the main sensor. +
51 (6).

The distance between the main sensor (7) and the metal surface is determined by the control device (
It is determined to be constant (approximately 2 hours) by the operation of 4).

The main sensor (7) is equipped with an induction magnetic coil to which a high-frequency current is applied, and generates an eddy current in the tube wall due to magnetic lines of force.If the tube wall has any abnormalities such as cracks or corrosion, the magnetic By recording the change in voltage or current in the magnetic coil, it creates a back emf in the coil.
The tubes are examined for abnormalities.

The first and second sensors (5+ +6+ are the main sensor - (7
), and like the main sensor (7), it has a built-in electromagnetic induction coil and detects when the distance between it and the metal surface approaches a predetermined degree and emits an output signal. It is.

The first sensor (5) is connected at a distance (approximately 1,8
++111), and a detection signal is output when the object comes closer to a metal surface than this.

The second sensor (6) is set at a distance slightly longer (approximately 2.2 runs) than the set distance of the main sensor (7), and outputs a detection signal when it approaches a metal surface beyond this set distance. do.

Therefore, when the main sensor (7) is within the set distance or ±10% range from the metal surface, the first sensor (5) is not detecting and only the second sensor (6) is in the detecting state.

If the main sensor (7) gets too close to the metal surface beyond the allowable range and approaches below 1.8 tone, 1. 17th Noser (5)
starts detection, both the first and second sensors are turned on, and the clutch (45) that rotates the control shaft (34) in the direction of raising the sensor support base (3) is excited.
The rotation of the output shaft (42) is transmitted to the control shaft (34), which rotates and drives the sensor support base (3) until the ON-ON state of the first and second sensors disappears.

Similarly, if the main sensor (7) is too far away from the metal surface, the first and second sensors are turned off, and the clutch (46) rotates the control shaft in the direction of lowering the sensor support (3). ) is excited to rotate the control shaft (), and lower the sensor support base (3) until the OFF-OFF state of the first and second sensors disappears.

The related operations of the first and second sensors (51 (6) and the control device (4) are as follows.

The inspection device connects the swinging mechanism (8) to the other end of the pivot (38) at the upper end of the rotating rod (3G), and reciprocates the rotating rod (A) in the circumferential direction.

The oscillating mechanism is configured such that a reduction gear (821) is connected to a transmission mechanism (81) from a constantly rotating shaft of the transmission (15).
The output rotation of the speed reducer (821) is connected to the belt (
83) rotates a rotary plate (84) bearing on the sensor support stand (3). Since the belt (83) is extendable and retractable through the intermediate boot (85), the height of the sensor support stand (3) is the same as that of the control device (4).
The rotary plate (circle) can be rotated by moving up and down within a predetermined range due to the drive of the cylinder, and even if the distance between the shafts changes, it is absorbed by the spring compression of the intermediate boob IJ f85+.

The rotating plate (84) has a plurality of mounting holes (86) at different radial distances from the center of rotation, and a projecting arm (871) is provided at the end of the pivot (38) of the rotating rod (361). Arm (87)
) and the mounting holes at a predetermined radial distance on the rotary plate (round) are connected by a crank rod (88), and the rotary plate (84
) causes the rotating rod (36) to reciprocate with a predetermined amplitude.

The swinging mechanism (8) is capable of various design changes,
It is to be understood that the structures shown in the drawings are merely illustrative.

However, when inspecting the pipe, a part of the pipe is removed and the self-propelled vehicle (1) is set into the pipe through the opening, and the motor (14) and transmission (15) are controlled by control signals from the monitor room.
to drive.

The self-propelled vehicle (1) moves along the inner surface of the tube at a speed of approximately 4 m/min with each drive wheel of the wheel train rotating.
) is oscillated by the oscillating mechanism (8) at a high speed of about 210 times per minute, and scans the inner surface of the tube within the range of the reciprocating width of the main sensor (7).

The pivot (381) of the rotation rod (36) is the sensor support stand (3
) is rotated supported by the bearing device (37) on the
Since the first and second sensors (5) and (6) always detect the distance to the metal surface and drive the control device (4), the sensor support stand (3) is moved back and forth by the rotating rod [313+]. The height is also controlled between the main sensor (7) and the distance between the main sensor (7) and the metal surface is within a set range.

Therefore, the main sensor (7) is always kept at a constant height from the inner surface of the pipe, regardless of the diameter of the pipe to be inspected, and the main sensor (7) can be used without any gaps within the width of the reciprocating range of the main sensor (7). The inner surface of the can be scanned.

In the present invention, it is not necessary to align the pivot axis (38) with the center of the tube, so inspection can be easily performed. When the main sensor (7) passes an abnormal point, a back electromotive force is generated in the coil, which appears as a pulse train on the output graph, and the height and length of the pulse train correspond to the depth of corrosion. By creating an output graph, it is possible to accurately grasp the actual nature of corrosion or cracks and make appropriate decisions.

If the inspection concludes that the pipe is dangerous, the pipe containing the defective part can be replaced with a new one to avoid an accident.

As described above, the present invention provides that when the device is set in the pipe, the central
It is not necessary to align the Il + f38) with the center of the tube, and the inspection can be started while the tube is in place, so the inspection work can be carried out easily and quickly.Moreover, even if the tube is deformed, the first and second sensors (5) ( 6) controls the height of the sensor support base (3), and the distance between the main sensor (7) and the metal surface is maintained within a certain range during inspection, so accurate data can be output, etc. It has advantages.

[Brief explanation of the drawing]

FIG. 1 is a side view showing the inspection device of the present invention installed in a self-propelled vehicle, FIG. 2 is an enlarged side view of the inspection device, and FIG. 3 is a side view of the same. (1)...Self-propelled vehicle (2)...Mounting stand (3)...Sensor support stand (4)...Control device (5)...First
Sensor (6)...Second sensor (7)...Main sensor Applicant Kubota Iron Works Co., Ltd.

Claims (1)

[Scope of Claims] ■ A main sensor that detects defects such as cracks and corrosion on metal surfaces, and a sensor support stand that is movably held on top of the machine base and is mounted with the main sensor facing the metal surface. The distance for detecting the approach to a metal surface that is attached to a sensor support stand near the main sensor is set to be slightly shorter on one side (and slightly longer on the other side) than the predetermined distance range between the main sensor and the metal surface. The first and second sensors are engaged with the sensor support base so as to be able to be driven up and down, and when both the first and second sensors are in the detection state at the same time, the sensor support base is driven in a direction away from the metal surface. , and a control device that drives the sensor support in the direction toward the metal surface when both are in the non-detection state at the same time. ■ The main sensor and the first and second sensors are all electromagnetic induction sensors. The device according to claim 1, which includes a built-in coil and generates an eddy current by applying a magnetic field caused by a high-frequency current to a metal surface, and detects a voltage change due to disturbance of the eddy current at an abnormal location. The platform is movable, and the main sensor and the first and second
3. The device according to claim 1, wherein the sensor reciprocates in a plane perpendicular to the running direction of the machine.