JPH05340708A - Instrument for automatically measuring thickness of film in small-diameter pipe by remote control - Google Patents

Abstract

PURPOSE:To improve the accuracy of the thickness of a metallic film formed in a small-diameter pipe by fitting an eddy-current film thickness sensor to a head fixed in the pipe. CONSTITUTION:A paste thickness discriminating curve is obtained by correcting a previously prepared correlation curve between actually measured thicknesses by means of a dial gauge and voltage values detected by means of a sensor 17 by performing calibration tests. A head 11 is fixed on the axis of a pipe by advancing a head fixing pin 15 in the radial direction of the pipe. Under such a condition, the thickness of a metallic film 7 at the fixing point is obtained by advancing the sensor 17 in the radial direction of the pipe. Then, after the head 11 is released from the fixed state by retreating the sensor 17 and pin 15, the thickness of the film 7 is measured at numerous points by moving the head 11 in the inner peripheral and axial directions of the pipe by means of a driving mechanism 13. The measuring interval is set at about 1mm in the axial direction and 1 deg. in the peripheral direction and measured results are displayed by controlling the movement of the sensor 17 and pin 15 by means of a personal computer 31. Namely, fluctuation-free measured values can be obtained by freely moving the eddy-current film thickness sensor 17.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring the thickness of a metal film formed on the inner wall surface of a small-diameter pipe, and particularly to a small-diameter pipe capable of increasing the detection accuracy of the thickness of the metal film. The present invention relates to an in-tube remote automatic film thickness measuring device.

[0002]

2. Description of the Related Art An in-core housing is provided at the bottom of a reactor vessel to guide instrumentation for detecting neutrons. As shown in FIG. 8, this in-core housing is composed of a stainless small-diameter tube 3 inserted and supported in a lower mirror 2 forming the bottom of the reactor vessel 1. It is inserted into the opening 4 formed in and is attached by welding. Since the small diameter pipe 3 is welded from the outer peripheral portion and attached to the opening 4, the inner wall surface 6 of the small diameter pipe 3 in the vicinity of the welded portion 5 is made of Cr, Ni or the like in order to prevent the progress of deterioration or the like. The mixed powder is applied in a paste form, and the paste-like metal film 7 is irradiated with laser to become a hard metal film.

When the paste of mixed powder is applied to the inner wall surface 6 of the tube and the paste is irradiated with a laser beam as described above, a final metal film cannot be obtained unless the thickness of the paste is controlled. It costs.

[0004]

Conventionally, the pasty metal film 7 has been measured by an electromagnetic sensor. In this electromagnetic sensor, when an alternating current is applied to a probe in contact with the metal film 7, a magnetic field is generated around it. Since a current proportional to this flows in the secondary coil, the film thickness is measured from the change in the secondary current of the secondary coil according to the paste thickness. In the measurement of the film thickness by the electromagnetic sensor, the contact portion of the probe becomes unstable, the measured value of the secondary current varies, and there is a problem of lack of reliability.

The present invention was devised to effectively solve the above problems.

An object of the present invention is to provide a remote automatic film thickness measuring apparatus for small-diameter pipes capable of enhancing the detection accuracy of the metal film thickness formed in the small-diameter pipes.

[0007]

SUMMARY OF THE INVENTION The present invention is an apparatus for measuring the thickness of a metal film formed on the inner wall surface of a small-diameter pipe, which is moved in the small-diameter pipe in the pipe axial direction and in the pipe inner peripheral direction. A head that is freely inserted, and a head that is arranged in the head in the circumferential direction and is movable in the pipe radial direction so that the tip portion abuts the inner wall surface to fix and hold the head in the pipe. A pin, and an eddy current type film thickness detection sensor that is provided on the head so as to be movable back and forth in the pipe radial direction, and contacts the metal film formed on the inner wall surface to detect the film thickness. is there.

[0008]

Since the eddy current type film thickness detection sensor is attached to the head fixed in the small-diameter pipe as described above, the film thickness detection accuracy can be improved.

[0009]

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 lower mirror 2 forming the bottom of a reactor vessel 1 is vertically inserted with a small-diameter stainless steel pipe 3 as an in-core monitor housing. It is held in an opening 4 formed in the mirror 2. The inner wall surface 6 of the small-diameter pipe 3 near the welded portion 5 is covered with C in order to cover the inner wall surface 6 and prevent the progress of deterioration.
A metal coating 7 is formed by applying a mixed powder of r, Ni or the like in a paste form, and the metal film 7 is irradiated with a laser to be cured. That is, a paste-like magnetic metal film is formed on the non-magnetic metal.

In particular, prior to laser irradiation, the inner wall surface 6 of the pipe is
As a device for detecting the thickness of the paste-like metal film 7 formed in the above, a head 11 is inserted into the small diameter tube 3 so as to be movable in the tube axis direction and in the tube inner peripheral direction at a predetermined pitch.
A rod 12 extends downwardly from the head 11, and a motor (not shown) or the like for moving the head 11 in the small-diameter pipe 3 in the pipe axis direction and the pipe inner peripheral direction at a predetermined pitch is provided on the rod 11. A drive mechanism 13 having is provided. A controller 14 for remotely controlling the movement of the head 11 is connected to the drive mechanism 13.

Specifically, as shown in FIG. 2, at the tip of the head 11 inserted into the small-diameter tube 3, the head 1 is also inserted.
As shown in FIG.
A head fixing pin 15 is provided so as to be capable of advancing and retracting in order to hold the inside of the small diameter tube 3. The head fixing pins 15 are provided at equal pitches in the circumferential direction of the head 11, as shown in FIG.
As shown in FIG. 3, three head fixing pins 15 are arranged every 120 degrees in the circumferential direction of the head 11. 2 and 3
In order to move the head fixing pins 15 back and forth, the air cylinders 16 are respectively provided at the upper and lower ends in the head 11.
The air cylinder 16 is housed in the air supply pipe 16a.
The head fixing pins 15 are simultaneously moved forward or backward by the same amount by the pressure air supplied from Therefore, when the head fixing pin 15 is moved forward, the head fixing pin 1 is attached to the inner wall surface 6 of the small diameter tube 3.
When the head 11 is fixedly held in the small-diameter tube 3 by abutting the tip portion of the head 5 and the head fixing pin 15 is retracted, the head 1
The fixation of 1 will be released.

Further, the head 11 is provided with an eddy current type film thickness detection sensor 17 for detecting the thickness of the metal film 7 formed on the inner wall surface 6 of the small diameter tube 3, and this sensor 17 is the head 11 Is provided so as to be movable back and forth in the pipe radial direction.
That is, as shown in FIGS. 2 and 5, the head 11 is provided with an opening 18 for allowing the sensor 17 to move back and forth, and is provided with a guide 19 for guiding the movement of the sensor 17, and the sensor 17 is also provided. There is provided a moving mechanism for moving the tube in the radial direction. The moving mechanism is the head 11
There is a lever member 22 supported swingably around the pin 21 and an air cylinder 23 connected to the lever member 22. The lever member 22 engages with a pin 25 in an elongated hole 24 formed at one end portion of the sensor member 17 and
The lever member 22 is connected to the rear end portion thereof, and the other end portion of the lever member 22 is folded back into an L shape so that the rod 2 of the air cylinder 23.
It is connected to 6. Therefore, when the rod 26 retreats due to the compressed air supplied from the air supply pipe 27 connected to the air cylinder 23, the lever member 2 is rotated about the pin 21.
2 rotates counterclockwise in the figure, the sensor 17 moves toward the pipe inner wall surface 6 and comes into contact with the paste-like metal film 7. On the contrary, the forward movement of the rod 26 causes the sensor 1 to move forward.
7 will be set back. In FIG. 5, 28 is a spring, and this spring 28 urges the sensor 17 in the backward direction.

As shown in FIG. 1, a personal computer 31 is connected to the drive mechanism 13 in order to control the forward / backward movement of the head fixing pin 15 and the sensor 17. A record of the metal film thickness is displayed on the personal computer 31 in real time, and the record is displayed on the recording paper by the printer 32.

Next, the operation of the above embodiment will be described.

A calibration test is performed prior to measuring the actual metal film thickness. First, reference test pieces having different paste-like metal film thicknesses are prepared, and the actual thickness is measured with a dial gauge. Next, measure the voltage near the actual thickness measurement point with an eddy current type film thickness detection sensor, create a correlation curve between the actual thickness by the dial gauge and the voltage value by the sensor, correct this value to a predetermined value and determine the paste thickness. Use a curved line.

Specifically, a reference test piece 41 as shown in FIG. 6 is produced. In this test piece 41, a ring groove 44 is formed in a circumferential direction on an inner wall surface 43 of a tubular base material 42 made of a non-magnetic metal similar to that of a small-diameter tube, and the ring groove 44 has a magnetic property equal to the inner diameter of the tubular base material 42. A body metal paste 45 is applied. A measuring hole 46 for measuring with a dial gauge is formed in the paste 45. After the dial gauge is set at the measurement point A and the paste thickness d is measured in the test piece 41 configured as described above, the eddy current sensor is applied to the measurement point B to measure the generated voltage. Can be converted to voltage. When a voltage value is obtained from a large number of measured values of the paste thickness by a dial gauge, a calibration curve as shown in FIG. 7 can be obtained.

FIG. 7 shows the correlation curve between the actual thickness of the dial gauge and the voltage value of the sensor, with the vertical axis representing the paste thickness obtained with the dial gauge and the horizontal axis representing the measured value obtained with the eddy current sensor. A paste thickness determination curve obtained by correcting this with a predetermined value is also shown. The case where the paste thickness is within the predetermined range is the acceptable paste thickness. Based on such a calibration test, the voltage value obtained by the eddy current type film thickness detection sensor 17 actually set in the small-diameter tube 3 is converted into the measured value by the dial gauge obtained in the calibration test, and this is converted into The metal film thickness.

To actually measure the metal film thickness, as shown in FIG. 1, the head fixing pin 15 is advanced in the pipe radial direction to fix and hold the head 11 on the pipe axis. With the head 11 fixedly held, the sensor 17 is advanced in the pipe radial direction to obtain the metal film thickness at the head fixed / holding point. Next, the sensor 17 and the head fixing pin 15 are retracted to release the fixation of the head 11, and then the head 11 is moved to a measurement position in the pipe inner peripheral direction and the pipe axial direction to remove a large number of points in the pipe inner peripheral direction and the pipe axial direction. Measure the metal film thickness. For example,
It is measured at a pitch of 1 mm in the axial direction and at a pitch of 1 degree in the inner circumferential direction of the pipe. Since the strength of the eddy current changes according to the change of the metal film thickness, the detected voltage value also increases as the film thickness increases. The forward / backward movement of the sensor 17 and the head fixing pin 15 is operated by the personal computer 31, and the detection result is displayed on the personal computer 31 and recorded on the recording paper 32 as necessary.

When the actual paste-like metal film thickness is detected outside the acceptable range, the metal film 7 is removed, and the paste-like metal film 7 is again formed on the inner wall surface 6 of the small diameter pipe 3.
Will be applied.

As described above, according to the present invention, the head fixing pin 15 and the eddy current type film thickness detection sensor 17 can be moved forward and backward in the small diameter tube 3 from the head 11 which is movable in the tube axial direction and the tube inner peripheral direction. Since the eddy current type film thickness detection sensor 17 can be stably fixed and held, the eddy current type film thickness detection sensor 17 can obtain a measured value without variation, thereby improving the measurement accuracy of the metal film thickness. be able to.

[0022]

In summary, according to the present invention, the head fixing pin and the eddy current type film thickness detection sensor can be moved back and forth in the pipe diameter direction from the head movable in the pipe axis direction and the pipe inner peripheral direction in the small diameter pipe. Since the sensor is provided, the sensor can be stably fixed and held, and the eddy current type film thickness detection sensor can obtain a measured value without variation, and the film thickness measurement accuracy can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a film thickness detection device of the present invention.

FIG. 2 is a cross-sectional view showing a tip portion of a head.

FIG. 3 is a diagram showing a base end portion of a head.

FIG. 4 is a view taken along line XX of FIG.

5 is a view taken along the line YY of FIG.

FIG. 6 is a diagram showing a test piece.

FIG. 7 is a diagram showing a calibration curve.

FIG. 8 is a view showing a small diameter tube.

[Explanation of symbols]

 3 Small diameter tube 6 Inner wall surface 7 Metal film 11 Head 15 Head fixing pin 17 Eddy current type film thickness detection sensor

Claims (1)

[Claims] 1. An apparatus for measuring the thickness of a metal film formed on an inner wall surface of a small-diameter pipe, comprising a head movably inserted into the small-diameter pipe in a pipe axial direction and in a pipe inner peripheral direction. A head fixing pin that is arranged in the head in the circumferential direction and is movable in the tube radial direction so as to move forward and backward, and a tip portion abuts against the inner wall surface to fix and hold the head in the tube; It is installed so that it can move back and forth in any direction.
An eddy-current type film thickness detection sensor for contacting the metal film formed on the inner wall surface to detect the film thickness, and a remote automatic film thickness measuring apparatus for small-diameter pipes.