JP2002162217A - Radiation type pipe wall thickness meter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radiation type pipe wall thickness meter capable of highly accurately measuring the wall thickness of a pipe in a simple structure by a single radiation generator. SOLUTION: In the radiation type pipe wall thickness meter, the pipe to be measured (3) is irradiated with a radiation (10) contracted from the radiation generator (1), and a radiation dose transmitting the pipe 3 is detected by a radiation detector (4) to measure the wall thickness of the pipe (3). The radiation type pipe wall thickness meter is provided with a storage circuit part (8) storing radiation transmittance characteristics for various reference thickness obtained by combining a plurality of flat reference plates, and a thickness calculation processing part (7) comparing the radiation dose detected by the radiation detector (4) with a radiation transmittance characteristic curve to calculate the wall thickness of the pipe, and correcting measured errors due to a circular arc-shaped curvature in accordance with the pipe diameter of the calculated wall thickness.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation tube thickness gauge, and more particularly, to a tube to be measured which is conveyed in an axial direction in a first direction perpendicular to the axial direction. The present invention relates to a radiation-type pipe thickness gauge provided with a radiation generator that irradiates radiation and a radiation detector that detects a radiation amount irradiated from the radiation generator and transmitted through a tube.

[0002]

2. Description of the Related Art FIG. 5 is an explanatory view for explaining the principle of a conventional radiation tube thickness gauge. This radiation-type pipe thickness gauge is a pipe 3 to be measured which is conveyed in an axial direction perpendicular to the plane of the drawing.
To irradiate the radiation in a first direction perpendicular to the axial direction, and the pipe 3 being conveyed is perpendicular to the axial direction and perpendicular to the first direction. A plurality of radiation generators 1a, 1b, 1c arranged side by side to irradiate the entire tube 3 so that the amount of radiation transmitted therethrough does not change even if a lateral shake occurs in the second direction, and a tube In order to improve the S / N ratio even when the diameter or radius of the tube 3 changes, the size variable collimator 12 that cuts unnecessary radiation unnecessary for thickness measurement and the radiation that has passed through the tube 3 and flowed through the window of the collimator 12. A radiation detector 4 for detecting an amount.

In the apparatus shown in FIG. 5, a function curve diagram 50 showing the received radiation dose with respect to the position x in the moving direction of the tube 3 is obtained according to the diameter (or radius) and the thickness of the tube 3 existing in the radiation path. . According to this function curve diagram 50, the average thickness of the pipe 3 is calculated by the average thickness calculator 11 and the calculation result is transmitted to the host computer 9. The average thickness calculating unit 11 has previously received various setting values for the average thickness calculation from the host computer 9.

[0004]

The conventional radiation-type pipe thickness gauge shown in FIG. 5 requires a plurality of radiation generators 1a, 1b, and 1c to irradiate the entire pipe 3, and the apparatus cost is reduced. It will be expensive. In addition, a variable size collimator 12 for cutting extra radiation according to the size (diameter or radius) of the tube 3 is required, and the structure becomes complicated. On the other hand, when a part of the tube 3 is to be irradiated with the radiation narrowed down in advance by a single radiation generator, there is a disadvantage that the lateral deflection of the tube 3 directly affects the measurement accuracy.

Accordingly, an object of the present invention is to provide a radiation-type pipe thickness gauge capable of measuring the wall thickness of a pipe with high accuracy with a simple structure using a single radiation generator.

[0006]

In order to achieve the above-mentioned object, a radiation-type pipe thickness gauge according to the first aspect of the present invention is arranged so that a pipe to be measured which is conveyed in an axial direction is arranged in the axial direction. In a radiation-type pipe thickness gauge having a radiation generator that irradiates radiation in a first direction perpendicular to the radiation detector and a radiation detector that detects the amount of radiation transmitted from the radiation generator and transmitted through the tube, a plurality of A storage circuit for storing radiation transmission characteristics for various reference thicknesses obtained by combining flat reference plates of the thickness, and comparing the radiation dose detected by the radiation detector with the radiation transmission characteristic curve to determine the wall thickness of the tube. And a thickness calculation processing unit for correcting a measurement error of the calculated thickness due to an arc-shaped bend corresponding to the pipe diameter. This makes it possible to accurately measure the wall thickness of the tube with an inexpensive and simplified configuration.

According to a second aspect of the present invention, there is provided the radiation type pipe thickness gauge according to the first aspect, wherein the thickness calculation processing unit is perpendicular to the axial direction with the movement of the pipe and in the first direction. It is characterized in that a means is provided for inputting the amount of lateral vibration occurring in a second direction perpendicular to the direction in real time, and for correcting an error due to the inputted amount of lateral vibration. Thus, when the tube behaves in the width direction during its conveyance, the wall thickness of the tube can be accurately measured without causing radiation to follow the tube.

The invention according to claim 3 is the invention according to claim 1 or 2
The thickness calculation unit of the radiation type pipe thickness meter described in (1) is characterized by comprising means for correcting an error due to scattering of radiation inside the pipe. Accordingly, it is possible to correct an error due to internal scattering of radiation that cannot be corrected by the pipe bending R and the lateral shake error correction calculation.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS <First Embodiment>
FIG. 1 is a block diagram showing a first embodiment of a radiation tube thickness gauge according to the present invention.

As shown in FIG. 1, the radiation type pipe thickness gauge according to this embodiment irradiates a narrowed radiation 10 from a single radiation generator 1 and changes the radiation amount transmitted through the tube 3 to radiation. The detector 4 receives and outputs an electric signal corresponding to the received radiation dose.

On the other hand, an absorption characteristic curve obtained by combining a plurality of flat reference plates 2 is stored in the storage circuit section 8, and the radiation output actually measured by the thickness calculation processing section 7 is used as the absorption characteristic curve. Compare and calculate the wall thickness.

Since the thickness obtained here assumes a flat plate, as shown in FIG. 2, the front and rear portions corresponding to the thick portion of the pipe 3 having an arc-shaped curved surface having a predetermined radius of curvature are used. The thickness error ΔT caused when the plate is irradiated with radiation from a direction inclined by an angle θ with respect to the radial direction is ΔT = T′−T (where T ′ is the measured thickness and T is the true thickness) And a measurement error Δε due to an arc-shaped bend corresponding to the pipe diameter to be corrected by integration as described below, assuming that the angle θ is diffused from the center of the radiation 10 to the left and right from 0 to θ.
Is calculated as a ratio to the true thickness T.

[0013]

(Equation 1) Here, θ is determined by the beam width of the radiation and the diameter of the tube 3.

As described above, the true thickness T can be obtained from T = T '/ (Δε + 1).

<Second Embodiment> (Corresponding to claim 2) This embodiment has the same configuration as the radiation tube thickness gauge according to the first embodiment, but here, the amount of lateral deflection Is input in real time, and means for correcting an error due to lateral shake is added.

As shown in FIG. 4, when the tube 3 moves from the center of the radiation beam in the direction perpendicular to the axial direction and the radiation direction of the tube 3 by an amount of Δx,
When the error Δε due to the tube curvature to be corrected is obtained by the ratio to the true wall thickness T, the following is obtained.

[0017]

(Equation 2) By solving this integral equation in the same manner as in claim 1,
The true thickness T can be determined.

Here, θ1 and θ2 are determined by the lateral shake amount Δx input from the radiation detector 4 in real time, the radiation beam width, and the diameter of the tube 3.

<Third Embodiment> (corresponding to claim 3) In this embodiment, the structure is the same as that of the radiation-type pipe thickness gauge according to the first embodiment. Means for correcting an error due to radiation scattering is provided in the thickness calculation processing unit 7. The amount of error with respect to the tube wall thickness is obtained from the measured data when there is radiation inside the tube and when it does not exist, and corrects (compensates) it.
By registering the amount of correction to be performed as a correction table in advance, the wall thickness of the tube can be accurately measured even if there is scattering of radiation inside the tube.

[0020]

As described above, according to the present invention, radiation focused from a single radiation generator is received by a radiation detector through a tube to be measured, and errors due to the curvature of the tube are corrected. In addition, it is possible to provide an inexpensive, accurate and simplified structure of a radiation-type pipe thickness gauge.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an example of a radiation tube thickness gauge according to a first embodiment of the present invention.

FIG. 2 is a diagram showing an example of correcting a pipe bending R according to the embodiment.

FIG. 3 is a view showing an example of a concept when calculating a correction amount of a pipe bending R according to the embodiment.

FIG. 4 is a diagram illustrating an example of correcting a lateral shake according to a second embodiment of the present invention.

FIG. 5 is an explanatory view illustrating the principle of a conventional radiation-type pipe thickness gauge.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Radiation generator 2 Reference plate 3 Tube 4 Radiation detector 5 Amplification part 6 A / D conversion part 7 Thickness calculation processing part 8 Storage circuit part 9 High-order computer 10 Radiation

Claims (3)

[Claims] 1. A radiation generator for irradiating a tube to be measured conveyed in an axial direction in a first direction perpendicular to the axial direction, and a tube irradiated from the radiation generator. A storage circuit for storing radiation transmission characteristics for various reference thicknesses obtained by combining a plurality of flat reference plates in a radiation-type pipe thickness gauge having a radiation detector that detects a radiation dose transmitted through Part, the thickness of the pipe is calculated by comparing the radiation dose detected by the radiation detector with the radiation transmission characteristic curve, and the calculated thickness has a measurement error due to an arc-shaped bend corresponding to the pipe diameter. And a thickness calculating unit for correcting the thickness. 2. A radiation-type pipe thickness gauge according to claim 1, wherein said thickness calculation processing section is at right angles to said axial direction with movement of said pipe and to said first direction. A radiation type pipe thickness gauge, comprising: means for inputting a lateral shake amount generated in a second direction at right angles in real time and correcting an error caused by the inputted lateral shake amount. 3. A radiation-type pipe thickness gauge according to claim 1, wherein said thickness calculation processing unit includes means for correcting an error due to radiation scattering inside said pipe. Radiation tube thickness gauge.