JP2002098505A - Method and apparatus for measuring thickness of paint film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and apparatus continuously and efficiently measuring the thickness of a paint film on a painted tube inner surface with high accuracy by completely removing the magnetic effect during the measurement. SOLUTION: An apparatus for measuring thickness of paint film A is composed of plural pairs of rotational rollers 12, 12 supporting tubes P that can be freely rotated, and a means for measuring the thickness of film 20 that includes a carriage 21 on which plural pairs of layer thickness measuring units 22 are mounted. A film thickness meter 27 attached on the edge of an arm 26 supported by a lifting guide 24 of the unit is inserted to inner surface of the tube P, and the film thickness meter 27 comes in contact with the surface to be measured at a determined position in the tube. After measuring the film thickness, the film thickness meter 27 is moved from the surface to be measured to a position having a determined distance where no magnetic effect occurs. A treatment for removing factors that deteriorate the accuracy of film thickness measurement is carried out in the condition without the magnetic effect while the tube P is turned to next measurement position, and then the next film thickness is measured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for measuring a coating film thickness applied to an inner surface of a pipe such as a cast iron pipe.

[0002]

2. Description of the Related Art Ductile cast iron pipes (hereinafter abbreviated as iron pipes) and the like are generally coated with an epoxy resin powder on the inner surface of the iron pipe for rust prevention treatment. This coating thickness is
In the S standard (JIS G 5528), the thickness is set to 0.3 mm or more, and the minimum film thickness is specified, but the maximum film thickness is not specified, and the optimum film thickness is determined from an economical (minimum necessary paint) viewpoint. Has been adopted. Therefore, it is necessary to measure the coating film thickness and secure an appropriate coating film thickness.

[0003] As a device for measuring whether or not the coating film thickness is appropriate, a film thickness meter having an electromagnetic film thickness probe is generally used. This electromagnetic film thickness meter consists of a coil wound around a ferromagnetic core, and when a predetermined current is passed through this coil to bring the tip of the magnetic core close to the surface of the painted metal body, Utilizing the fact that the self-inductance of the coil increases or decreases in accordance with the distance of the coil, the change is detected by a detection circuit to measure the thickness of the film. As one of the film thickness meters utilizing such a measurement principle, a "single-pole, two-point adjustment type electromagnetic film thickness meter" is known.

In general, the thickness gauge is used by an inspector holding a hand and pressing a tip of a magnetic core of the thickness gauge against a surface to be measured. For this reason, the film thickness meter is limited to measurement on the surface of the object to be measured, and can be used only within an allowable range that can be reached by an inspector. In particular, a painted surface applied as a rust preventive treatment to the inner surface of a steel pipe, a cast iron pipe, or the like is inaccessible and cannot be measured at all in a depth that cannot be visually recognized.
For this reason, Japanese Patent Application Laid-Open No. H10-304122 proposes a method and an apparatus for measuring the thickness of a film capable of coping with the measurement of the coating film on the inner surface of the tube.

[0005] The method for measuring the film thickness according to this patent publication is
A film thickness gauge having a film thickness probe similar to the film thickness probe based on the above measurement principle is attached to the tip of the robot arm so that it can be freely moved in the depth direction inside the tube and in a direction perpendicular thereto. The tip of the core is pressed at right angles to the inner surface of the tube to detect that the tip of the magnetic core is in contact with the inner wall and is in a measurable state, activate the circuit, and measure the film thickness.

[0006]

By the way, the film thickness measuring method according to the above-mentioned patent publication is an excellent film thickness measuring method in that the coating film thickness on the inner surface of the pipe can be automatically measured without manual operation. However, actually measuring the coating film thickness on the inner surface of the tube using the film thickness measuring device according to this publication still has the following problems.

In the above-mentioned film thickness measuring method, as described above, a unipolar two-point adjustment type film thickness probe is used. The two-point adjustment type uses a metal plate of the same type as the object to be measured. Adjust the scale of the film thickness meter to “0 point” and then place a standard thick plate of non-magnetic material on the same metal plate, or coat the same metal plate with a coating of a known thickness. The base plate is fixed and the tip of the film thickness probe is brought into contact with it, and the thickness at this time is 2 mm
In this case, the actual value of the film thickness is measured after adjusting two points in advance by setting the measured value of the film thickness meter to 2 mm.

[0008] Such zero adjustment and adjustment work using a standard thick plate (or an adjustment base plate) are important in performing high-accuracy measurement, but other than that, a film constituting a film thickness gauge is also required. It is also important to suppress as much as possible the effects of temporal changes in the operation of various parts such as electronic components of the thickness measuring circuit, fluctuations in the power supply voltage supplied from the outside, and the effects of external disturbance factors.
Here, the external disturbance factor is an external factor such as fluctuation of geomagnetism, except that the magnetic change of the film thickness probe with respect to the electromagnetic coil at the time of contact with the measurement object is not based solely on the physical properties of the measurement object. Is a factor that causes measurement errors due to the influence of However, the above publication does not specifically describe how to suppress the above-mentioned effects.

As a countermeasure for suppressing such an effect, a process for automatically eliminating the above-mentioned effect while the film thickness probe is separated from the object to be measured is generally performed. However, the above publication does not describe how far the film thickness probe should be separated from the inner surface of the pipe to be measured to eliminate the effect and perform high-precision measurement. It is described in principle only that it is movable in the depth direction and the orthogonal direction in the measured object. Although the publication does not describe the transmission of the measurement signal, when the tip of the magnetic core of the film thickness probe is correctly pressed against the surface to be measured at the time of measurement and the measurement can be performed, the switch in the film thickness meter is activated, and the film is operated. The signal of "Probe pressure ON" is transmitted from the gage to the external central processing unit. When the central processing unit receives this signal, it sends a signal of "waiting for input of measured value" to the film thickness meter, and immediately transmits the measured value to the central processing unit when the film thickness meter receives this signal. The central processing unit sends an instruction to move the film thickness probe away from the surface to be measured when receiving the measurement value, and sends a signal of "probe pressure off" when the film thickness probe is more than a predetermined distance away from the surface to be measured. It has become.

Therefore, when the tip of the magnetic core of the film thickness probe moves away from the surface to be measured, the film thickness meter transmits a signal of "probe pressure contact off", and a process for eliminating a factor that reduces the measurement accuracy is performed. On the other hand, if the distance from the surface to be measured is kept short, the processing is performed while the magnetism generated from the magnetic core is disturbed, so that the measurement accuracy is reduced.

When measuring the coating film thickness on the inner surface of the tube, the film thickness is measured at a plurality of points in the length direction of the tube and at a plurality of points along the inner surface of the tube at each point in each length direction. However, in the above publication, the thickness gauge at the tip of the robot arm is
No specific description is given of the case where the film thickness probe is kept facing in a fixed direction in the pipe and a plurality of measurement points in the pipe length direction or a plurality of measurement points on the inner circumferential surface of the pipe are measured as described above.

In view of the above problems, the present invention measures the coating film thickness on the inner surface of a pipe such as a cast iron pipe or a steel pipe coated on the inner surface by a magnetic effect on a film thickness probe at the time of measurement. It is an object of the present invention to provide a method and an apparatus for measuring the thickness of a coating film, which can perform a process for completely eliminating an error and continuously and efficiently measure the same at a predetermined position on the inner surface of the tube.

[0013]

According to the present invention, as a means for solving the above-mentioned problems, there is provided an electromagnetic coil having an inner surface coated with a rotatable tube and an electromagnetic coil extending from the end of the tube in the longitudinal direction thereof. When the coating thickness probe is inserted into a predetermined length position, the thickness gauge is moved to the surface to be measured in the tube, and brought into contact with it to measure the coating thickness with the thickness gauge from the magnetic change detected by the thickness probe. Then, after measuring the film thickness with the film thickness probe, the film thickness probe is separated from the surface to be measured to a predetermined distance position that is not magnetically affected, and the tube is rotated to the next surface to be measured,
In the meantime, in the absence of magnetic influence, after processing to eliminate the factors that reduce the accuracy of the measured value for the film thickness meter, the next film thickness measurement is performed, and the above measurement is repeated to measure the coating film thickness at multiple locations in the pipe This is the method of measuring the coating film thickness.

As an apparatus for carrying out the above-described measuring method, there are provided a rotation supporting means for rotatably supporting a pipe having an inner surface coated thereon, and a bogie movable in the longitudinal direction of the pipe, and mounted on the bogie. An arm and an elevating means for holding the arm so as to be able to move up and down are provided.A film thickness gauge having an electromagnetic film thickness having an electromagnetic coil is attached to the tip of the arm. The film thickness probe is brought into contact with the surface to be measured, and the coating film thickness is measured from the magnetic change signal detected by the film thickness probe. A factor that reduces the accuracy of the measured value for the thickness gauge in the absence of magnetic influence, while moving the tube to the next measured surface position by rotating and supporting the tube to a predetermined distance position that is not magnetically affected Eliminate It can be a sense to adopt a coating film thickness measuring apparatus that is configured to the following thickness measurements.

According to the method and the apparatus for measuring the film thickness, the coating film thickness applied to the inner surface of the tube is continuously measured. The thickness gauge is inserted into the inner surface of the tube by moving along the length of the tube,
The film is lowered in a direction perpendicular to the surface to be measured and contacts the surface to be measured, and the film thickness is measured. When the measurement is completed, the film thickness gauge moves away and rises, and stops at a predetermined distance from the surface to be measured which is not magnetically affected. While stopping at the predetermined distance position, the tube was rotated so that the next position to be measured was opposed to the film thickness probe, and a process for eliminating a factor that reduced the accuracy of the measurement value for the film thickness meter was performed. Thereafter, the measurement for the next surface to be measured is repeated.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic layout diagram including devices in processes before and after a coating film thickness measuring device according to an embodiment. The illustrated coating film thickness measuring apparatus A is an epoxy resin powder coating apparatus (not shown) on the inner surface of a ductile cast iron pipe (hereinafter referred to as an iron pipe) manufactured by an upstream cast iron pipe manufacturing apparatus (not shown). After coating, a large number of iron pipes arranged side by side on the stock table D are first inspected for the presence or absence of pinholes by the pinhole inspection device B, and then the coating thickness on the inner surface is measured to determine whether the coating thickness is normal. ing.

A defective coating film marking device S (shown by a dotted line) is provided within the installation range of the coating film thickness measuring device A shown in the figure. Further, a coating film defective product conveying device C is provided downstream of the measuring device A. Incidentally, another conveying device C ₀ for conveying the steel pipe over between the lower the stock table D~ pinhole inspection apparatus B~ paint film thickness measuring device A~ coating film defective conveying apparatus C each apparatus provided Have been.
The symbol R indicates a return path of the reworked product.

FIG. 2 shows (a) an enlarged plan view and (b) an enlarged side view of the coating film thickness measuring device A. The illustrated measuring device A is:
Rotation support means 1 for rotatably supporting a plurality of (three in the example shown) iron pipes P, P, P sent in parallel at a position shown in FIG.
0 and a pair of left and right film thickness measuring means 20 for measuring the film thickness on the surface to be measured on the inner surface of the iron pipe by providing a film thickness meter at the end of the arm provided on the carriage. The rotation support means 10 includes the support table 1
Each of the three iron pipes P, P, and P is placed on top of FIG.
As shown in FIG. 4 which is a cross-sectional view taken from the line -A, the pair of rotating rollers 12, 12 are provided so as to be rotatably supported by each of three sets.

In FIG. 1, when the three iron pipes P, P, P are supported by the pair of left and right rotation support means 10, 10, the right end of the iron pipes P, P, P from the left end is more than the rotation support means 10. Although it is supported in a state of protruding a little longer, as described later, there are two types of iron pipes P having a length of 4 m and 5 m, and the iron pipe P is fed so that the left end of the short iron pipe P also comes. This is a state in which the illustrated iron pipe P supports the longer iron pipe P. Therefore, the film thickness measuring means 20 on the left side
The moving table is installed so that the film thickness measuring means 20 on the right side can move a longer moving distance than the moving distance. When receiving and supporting the iron pipes P having different lengths, the centers of the iron pipes of the respective lengths are supported so as to coincide with the centers of the left and right rotation support means 10 and 10, and the left and right film thickness support means 20, 20 are supported. The moving distance may be designed symmetrically with respect to the iron pipes P having different lengths.

As shown in FIG. 3, the output of the motor 13 as a driving unit is transmitted to the two rotation rollers 12 and 12 via the transmission means 14 including a sprocket and a chain, and the tube is connected to the rotation support means 10 on one side. Rotate while supporting. The rotation support means 10 on the opposite side (the right side in FIGS. 2 and 3) does not have a driving unit, and the rotation roller 12 rotates by rotating the iron pipe P. Carriage of the transport apparatus C ₀ between the pair of rotary support means 10 and 10 are provided so as to travel on a rail by the wheel, and lower the iron pipe P came conveyed lift in support of the upper part of the carriage The iron pipe P is mounted on the rotation supporting means 10, 10.

The film thickness measuring means 20, in the example of FIG. 2, one truck 21 on the three sets of the film thickness measuring unit 22 to move to the direction perpendicular separately is provided a carriage transport device C ₀ Consisting of As shown in FIGS. 5 to 7, the carriage 21 is provided with two sets of driving sources on a fixed base 21a,
1b is provided, and wheels for traveling are provided below the fixed base 21a. One of the driving sources is for self-running by rotating wheels, and the other is for raising and lowering the elevator 21b.

The film thickness measuring unit 22 on the elevator 21b
Is constituted by attaching a film thickness gauge 27 to the tip of an arm 26 held via an angle adjusting means 25 on an elevating guide 24 attached to a bracket 23 fixed to an elevating table 21b.
The elevating guide 24 is provided so that a linear guide is provided along the vertical end of the bracket 23, and the moving member 24a is moved up and down by a hydraulic cylinder at the upper end. Moving member 24
A horizontal member 25a of the angle adjusting means 25 is attached to an end of the line a. The arm 26 is located at an intermediate position of the horizontal member 25a.
Is rotatably mounted, and the angle of the arm 26 with respect to the horizontal member 25a is adjusted and set by a spring and a screw rod. An elevating means is formed by the elevating table 21b and the elevating guide 24.

A limit switch 25b is provided at the tip of the horizontal member 25a. When the tip of the arm 26 is inserted into the iron tube, the moving member 24a is lowered due to an erroneous operation or the like and the angle of the moving member is lowered. A signal for stopping the operation is output to prevent damage due to erroneous operation. By the angle adjusting means 25, the base of the arm 26 is normally set to be approximately 4 degrees upward with respect to the horizontal, so that even if the tip of the cantilevered arm 26 is lowered by its own weight, the base of the arm 26 remains at the tip end position. Adjustments are made so that they are at the same level (horizontal).

FIG. 8 shows a schematic configuration of the film thickness meter 27. The configuration of the film thickness meter 27 is basically the same as disclosed in
This is the same as that disclosed in No. 2 and will be briefly described here. An electromagnetic induction type film thickness probe 30 comprising a magnetic core 31 of a ferromagnetic material and a coil 33 wound around the magnetic core 31 at a position near the tip of the film thickness meter 27 is fixed to a fixing member 34 together with a coil case 32. It is provided to be able to move up and down freely. The film thickness probe 30 is provided so as to always be projected downward by being pressed by the elastic member 37, and a terminal block 36 provided via a coil mount 35 on the opposite side to the magnetic core 31 is connected (signal detection). When the film thickness probe 30 is pressed against the surface to be measured and is immersed in the fixed member 34, a switch 39 for generating a probe pressure signal is turned on, and the coil of the film thickness probe 30 is turned on. The coating thickness of the surface to be measured is measured from a change in current or voltage generated in the coil 33 based on the change in self-inductance.

The film thickness signal measured by the film thickness probe 30 is sent to a measuring circuit, where it is converted into a binary signal, and further sent to an external central processing unit computer (not shown), where the film thickness is measured. Measured. The film thickness measured by the film thickness probe is measured according to the two-point adjustment type measurement principle, as in the case of the conventional example.

The coating thickness on the inner surface of the iron pipe is measured by the coating thickness measuring device of the embodiment having the above-described configuration. In the iron pipe measured by the illustrated coating film thickness measuring device A, the coating film thickness is measured immediately behind the above-described cast iron pipe manufacturing line. In this line, the iron pipe diameters are 75, 100, 150, and 20.
It is intended for five types of 0, 250 mm, and these iron tubes have a length of 75 m and a diameter of 100 mm.
For 00 and 250φ, the length is 5 m. At the time of measuring the coating film thickness, three iron pipes P, P, P
2 is fixed on each of the two supports. Since the distance between the supports 11 and 11 is constant, one side of the iron tube is measured when measuring a 5 m long iron tube as compared with the case of a 4 m long iron tube as described above. The measurement is performed in a state where the end is supported at the same position and the other end is projected extra 1 m from the support base 11.

As shown in FIG. 9A, the measuring position in the length direction of each iron pipe P is 100, 900 m from both ends of the pipe.
(a), (b), (c), and (d) where m is entered. However, on the socket side of the iron pipe, positions (a) and (b) are 100 and 900 mm from the position where the socket length PJIS is included. Then, at each length position, the film thickness is measured at four points having a phase difference of 90 ° along the inner diameter of the tube as shown in FIG. When measuring the measurement point ~
In this embodiment, the iron pipe P is rotated by rotating the rotating roller 12 instead of rotating the film thickness meter 27, and the surface to be measured to which the film thickness measuring device 27 faces is changed to ~.
(However, the rotation direction may be opposite to the illustrated direction, and is arbitrary).

The rotating rollers 12 and 12 of the supports 11 and 11
When the three iron pipes P, P, P are respectively placed on the iron pipe P, the carriage 21 of the film thickness measuring means 20 waiting at the standby position is brought close to both ends of the iron pipe P, and the film thickness at the end of the arm 26 is set. The total 27 is inserted into the tube and stopped at a predetermined length position. In this case, the protruding end of the film thickness gauge 27 is inserted along the length direction of the iron tube at a position at least 20 mm or more away from the surface to be measured in the iron tube. When the pipe diameter changes largely from, for example, a large diameter to a small diameter with respect to the surface to be measured in the iron pipe, the lifting and lowering carriage 21b of the carriage 21 is previously adjusted to be at the predetermined distance position, and the adjustment distance is adjusted. The holding height of the arm 26 is adjusted by the elevating guide 24 in the small range.

When the thickness gauge 27 is inserted on the surface to be measured in the iron tube as described above, the arm 26 is further lowered by the elevating guide 24 so that the protruding end of the thickness gauge 27 is moved to the surface to be measured. The film thickness is measured by abutting in a direction perpendicular (perpendicular) to the film thickness. In this case, when the magnetic core 31 contacts the surface to be measured and the lower end of the coil case 32 is pushed into the lower end of the fixing member 34, the switch 39 is turned on, and the measuring circuit 38 is turned on.
Operates. Therefore, a signal of a current or voltage change measured based on a change in self-inductance generated in the coil 33 is sent from the terminal block 36 to the measurement circuit 38, and the film thickness is measured. Needless to say, the film thickness is measured based on the two-point adjustment data.

The measured film thickness measuring signal is converted into a binary signal by the measuring circuit 38, and this signal is sent to an external central processing unit to measure the film thickness as described above. When this measurement is completed, a control signal from the main measurement circuit is sent to the elevating guide 24, and the thickness meter 2 at the tip of the arm 26 is used.
7 rises away from the surface to be measured. The distance position is at least 20 mm or more from the surface to be measured, and it is important to ascend to this distance position and stop. The reason is as follows.

In the measuring circuit of the film thickness meter 27, the tip is brought into contact with the surface to be measured, and further pressed (with a stroke of 5 m during pressing).
m) When it rises in the opposite direction even if it is a small distance (when the stroke becomes 4 mm or less) from the state in which the switch is operated, the switch 39 is operated, and the film thickness meter 27 transmits a signal of "probe pressure contact OFF" to the central processing unit. A predetermined current always flows through the coil 33 in the probe 30, and a magnetic field is generated from the magnetic core 31. When the measured object is near the magnetic core 31, the magnetic field is disturbed by the measured object. Film thickness meter 2
7 starts a process of eliminating the influence of a factor that reduces the measurement accuracy when the magnetic core 31 is separated from the object to be measured, but in order to keep the measurement accuracy high, a magnetic field is applied during this process. Is not disturbed. Therefore, if this process is started with the magnetic field being disturbed, the influence of the magnetic disturbance is still included, and the measurement accuracy is reduced.

In order to reduce such an influence so as not to affect the measured value, the tip of the magnetic core 31 of the film thickness probe 30 is stopped at a distance of at least 20 mm or more from the surface to be measured. Depending on the setting conditions of the measurement accuracy, it may be 10 mm or more. However, during actual film thickness measurement, the iron tube bends due to its own weight, or partial bending due to manufacturing errors has occurred.
Even if it is set at a distance of at least 10 mm or more, the tip of the thickness gauge 27 is actually 10 mm.
It is also anticipated that they are approaching: For this reason, the value is set to be at least 20 mm or more including the setting error at the time of the actual measurement, so that the influence of the magnetic disturbance can be stably cut off.

When the tip of the film thickness meter 27 rises and stops at a predetermined distance position determined as described above, the rotating roller 1
2 and 12 rotate, and the iron pipe P is rotated to a position where the measurement point faces the film thickness probe 30 and stopped. Therefore, the rotation of the iron pipe P is an intermittent operation. The same measurement as described above is performed at the measurement points, and when the film thickness probe 30 rises again, it stops at a predetermined distance position and rotates the pipe P, and the measurement points are measured one after another.

If the film thickness measured at any one of the above-mentioned measuring points 1 and 2 is not more than a predetermined thickness (0.3 mm), the central processing unit determines a defective product and outputs a signal based on the determination. A signal is sent to the coating film defective article marking device S, and a mark indicating the defective article is stamped. In addition, the above-described measurement is based on the length of each of (a) and (c) in FIG. 9 (a) and (b) and (d) in FIG. Parallel processing is performed almost simultaneously at the left and right positions.

In the film thickness measuring process described above, it is assumed that the long iron pipes P, P, P are linear, but among these iron pipes, for example, a small diameter pipe of 75 mm has a poor manufacturing accuracy and a long length. In some cases, undulation in the vertical direction may be included. In this case, even if the film thickness probe 30 is inserted into the iron pipe P as shown in FIG.
May be located to the right or left of the center of the iron tube, for example, being shifted by about 10 mm.

In the illustrated film thickness probe 30, when the magnetic core 31 comes into contact with the surface to be measured and is pushed into the film thickness meter 27 by a stroke of 4 mm, the measuring circuit is activated, and the fixing member 34 does not sink the stroke of 5 mm or more. Designed for
Therefore, as shown in FIG.
Is shifted from the center of the iron tube P, even if the film thickness probe 30 is lowered, the corner portion of the fixing member 34 contacts the inner surface of the iron tube P, and the magnetic core 31 does not move as much as the necessary stroke. No signal to start measurement. In such a case, the central processing unit outputs a signal for processing the iron tube as a defective product. 9 and 10, the bold line on the inner periphery of the iron pipe P indicates the painted surface.

In the above embodiment, the tube is rotatably supported and rotated by the two rotating rollers, but the rotating support means may not be a rotating roller type. For example, a half-split type bearing means or a bearing means fitted in the longitudinal direction of the pipe may be used. Further, the thickness gauge is not limited to the thickness gauge 27 of the above embodiment, but may be any two-point adjustment type electromagnetic thickness gauge.

[0038]

As described above in detail, in the film thickness measuring method and apparatus according to the present invention, the electromagnetic film thickness probe is brought into contact with the surface to be measured to measure the film thickness. The thickness gauge is moved away from the position where it cannot reach, and processing to eliminate the cause of the decrease in measurement accuracy without magnetic influence on the thickness gauge is performed. As a result, the film thickness can be measured more efficiently and the measurement can be performed without the influence of magnetic disturbance.

[Brief description of the drawings]

FIG. 1 is a schematic layout diagram in the vicinity of a coating film thickness measuring device of a cast iron pipe production line.

FIG. 2 is a plan view and a side view of a coating film thickness measuring device.

FIG. 3 is a partial side view taken along the line III-III in FIG. 2;

FIG. 4 is a partially enlarged sectional view taken along the line AA in FIG. 3;

FIG. 5 is a side view of a film thickness measuring means.

FIG. 6 is a front view of the same.

FIG. 7 is an enlarged perspective view of the same.

FIG. 8 is an external view of a film thickness gauge and an enlarged sectional view thereof.

FIG. 9 is an explanatory view of a measuring method.

FIG. 10 is an explanatory diagram of a measuring method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Rotation support means 11 Support stand 12 Rotary roller 13 Motor 14 Transmission means 20 Thickness measuring means 21 Cart 21b Elevating base 22 Thickness measuring unit 23 Bracket 24 Elevating guide 25 Angle adjusting means 26 Arm 27 Thickness gauge 30 Thickness probe 31 Magnetic core 32 Coil case 33 Coil 34 Fixing member 35 Upper flange 36 Terminal block 37 Elastic member 38 Measurement circuit 39 Switch

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Fumio Tsurugimo 1677 Kusue, Takatsu-ku, Kawasaki-shi, Kanagawa F-term in Sanko Electronic Research Laboratory Co., Ltd. 2F063 AA16 BA30 BB08 BC02 BD01 BD12 BD13 CA08 CA11 DA02 DA05 DD02 DD04 DD06 EB19 GA01 KA01 LA19 ZA03

Claims (5)

[Claims] 1. A thickness gauge provided with an electromagnetic thickness probe having an electromagnetic coil in the longitudinal direction thereof is inserted into a predetermined length position from an end of the pipe so as to rotatably support a pipe having an inner surface coated. Then, when moving the film thickness gauge to the surface to be measured in the tube and abutting the film thickness probe to measure the coating film thickness from the magnetic change detected by the film thickness probe, the film thickness was measured by the film thickness meter. After moving the film thickness meter away from the surface to be measured to a predetermined distance that is not magnetically affected, rotate the tube to the next surface to be measured, and then measure the film thickness with no magnetic effect. A coating film thickness measurement method in which the following film thickness measurement is performed after performing a process for eliminating a factor that lowers the value accuracy, and the above measurement is repeated to measure the coating film thickness at a plurality of locations in the pipe. 2. The method according to claim 1, wherein the predetermined distance position is at least 10 m.
2. The method according to claim 1, wherein the thickness is at least m. 3. The predetermined distance position is at least 20 m.
The coating thickness measuring method according to claim 2, wherein the thickness is not less than m. 4. A rotary support means for rotatably supporting a pipe having an inner surface coated thereon, and a truck movable in a longitudinal direction of the pipe, and an arm and an arm which can be moved up and down on the cart. A lifting and lowering means for holding is provided, and a film thickness meter equipped with an electromagnetic film thickness probe with an electromagnetic coil is attached to the tip of the arm. The film thickness meter is inserted into the tube and the arm is lowered to measure the film thickness probe The coating thickness is measured from the signal of the magnetic change detected by the film thickness probe, and the arm of the elevating means is raised after the film thickness measurement, so that the magnetic effect is not exerted on the film thickness probe. At the same time, and rotate the tube to the next surface to be measured by the rotation support means, and remove the factor that reduces the accuracy of the measurement value for the film thickness meter without magnetic influence. Take the next film thickness measurement Coating thickness measuring device configured as described above. 5. An elevating truck, wherein said elevating means is provided so as to be able to ascend and descend with respect to a fixed bogie which forms a movable bogie, and an arm elevating unit which makes an arm provided on said elevating cart capable of ascending and descending. 5. The coating film thickness measuring apparatus according to claim 4, wherein the lifting amount of the arm is adjusted by a lifting carriage and an arm lifting unit.