KR101157361B1 - Radiation thickness meter - Google Patents

Abstract

A radiation thickness gauge according to the present invention comprises a C-type frame 1d provided so as to sandwich a measured object in a direction perpendicular to a path line plane for carrying a measured object 3, and a C- A main detector 1b provided on the arm portion for detecting transmission radiation provided on the other arm portion and a main detector 1b for detecting a scattered line scattered from the measured object around the main detector 1b, A detection section 1 having a detector 1c and a correction coefficient which is obtained in advance so that an output change due to the increase or decrease of the radiation detected by the main detector and an output change of the scattered ray component detected by the sub- And a correction operation unit for selecting a correction coefficient from the output of the sub-detector and multiplying the output of the sub-detector when the measured object moves in the optical axis direction perpendicular to the pass line plane, (2) having a thickness calculating section (2a) and a thickness calculating section (2b) for obtaining a thickness.

Description

{RADIATION THICKNESS METER}

The present invention relates to a radiation thickness gauge for measuring the thickness of an object to be measured from the dose of radiation transmitted through the object by irradiating the object to be measured such as a steel plate with radiation generated from the radiating optics or X-ray generator, And a thickness measuring technique in the case where the measured object moves in the direction of the optical axis of the irradiation radiation.

Conventionally, for measuring the thickness of a steel sheet in a rolling line and a conveying line of a steel sheet such as a thick plate or a thin plate, it is necessary to use a? -Ray thickness measuring system using a radiation isotope or an X- And a radiation gauge such as a gauge is used.

Such a radiation thickness gauge has a limitation in improvement of spatial resolution because the beam diameter of the radiation to be irradiated on the measured object is comparatively large. However, since it is necessary to manage the radiation based on laws and ordinances, A distance measuring system using the high laser beam is installed on the upper and lower arm portions of the C-shaped frame which sandwich the steel plate in the vertical direction, and a laser type thickness measuring system for measuring the thickness from the distance change of the two distance measuring systems is also adopted have.

However, the thickness measurement accuracy of the steel sheet is important in ensuring the quality assurance and yield of the steel sheet. However, in the rolling line and its conveyance line, there is a change in shape such as upward and downward movement and warping and deflection of the steel sheet, There was a limit.

For example, in a radiation thickness gauge, when a steel sheet moves in a direction perpendicular to the pass line surface with respect to a conveyance reference surface (hereinafter referred to as a pass line surface) of the steel sheet to be conveyed, the scattering component of the radiation transmitted through the steel sheet changes Measurement error occurs.

As a method of correcting the measurement error due to the inclination of the steel sheet in the carrying direction with respect to the pass line surface of the steel sheet, there is a thickness measuring method in which the inclination of the steel sheet is detected using the laser distance meter to improve the measurement accuracy of the thickness . For example, Japanese Patent Application Laid-Open No. 2007-263819 (hereinafter referred to as Patent Document 1) is known.

Generally, in a rolling line or a conveying line of a steel sheet, warpage or sagging occurs at the leading end or rear end of the steel sheet to be conveyed, but in the other central portion, mainly upward and downward fluctuations occur.

In the radiation thickness gauge, there is a problem that a measurement error occurs when the steel sheet moves up and down during measurement. The reason for this will be described with reference to Figs. 1A and 1B.

FIG. 1A is a diagram showing the X-ray thickness measurement system using X-rays when the reference thickness of the steel sheet is 0.1 mm and 3.15 mm and the steel sheet is moved up and down with respect to the pass line plane PL- (Deviation%) with respect to the reference thickness.

1B is an optical model diagram of a detection part of the X-ray thickness measuring system. X-rays emitted from one point of the radiation source 1a are transmitted through the measured object (steel plate) 3, And the range of the solid angle? M is detected in the detector 1b provided at the rear portion.

When the measured object 3 moves from the pass line plane PL-0 to the upward direction PL + 50, for example, when the scattered line from the point P1 is within the range of the received light solid angle detected by the main detector 1b Is expanded from the solid angle &thetas; d0 to the solid angle &thetas; d1. That is, the amount of the scattered ray received by the main detector 1b is changed in proportion to the square of the distance between the measured object 3 and the main detector 1b.

Therefore, as shown in Fig. 1A, when the measured object 3 moves upward, the scattered ray component received by the detector 1b is increased, and the thickness of the measured object 3 becomes larger than the scattered ray component Is assumed to be thickened by an increased amount, and a deviation with respect to the reference thickness is output in a minus (thin) direction.

For example, when the steel sheet 3 having a thickness of 3.5 mm moves 100 mm from the pass line surface 0 mm toward the detector, the deviation becomes -1.5%.

As a method of correcting the measurement error due to the fluctuation of the steel sheet, there are a method of measuring and correcting the position of the steel sheet using a laser distance meter as disclosed in Patent Document 1, and a method of mechanically measuring the position of the steel sheet, Or a method of correcting a measurement error due to up-and-down movement is known.

However, the method of obtaining and correcting the position of the steel plate with such another position detector requires a space for installing a new facility in the steel plate conveyance line, and a problem that the time response of the radiation thickness measurement system and the position detector is different, There is a problem in that it becomes difficult to correct the measurement points on the dynamically varying steel plate by matching them.

In addition, since the method using the laser distance meter according to Patent Document 1 can only be used in an environment in which the measurement space through which the laser beam passes is cleaned, there is a problem that a unique environmental countermeasure facility for cleaning the measurement space is required have.

An object of the present invention is to provide a radiation thickness gauge capable of correcting an error caused by a vertical movement of an object without installing a new facility and improving the measurement accuracy.

In order to achieve the above object, a radiation thickness gauge according to the present invention has the following configuration. In other words,

There is provided a radiation thickness gauge for measuring the thickness of a workpiece from a radiation dose of the radiation transmitted through the workpiece by irradiating the moving workpiece with radiation,

(1) a C-shaped frame provided so as to sandwich the measured object in a direction perpendicular to a pass line plane for carrying the object to be measured,

(2) (i) a radiation source provided on one of the opposite arm portions of the C-shaped frame,

(ii) a main detector provided on the other arm portion for detecting the above-mentioned transmission radiation,

(iii) a sub-detector for detecting a scattering line scattered from the above-mentioned object to be measured in the vicinity of the above-described main detector provided at the center of the optical axis of a solid angle formed by the above-mentioned center point of the irradiation surface of the radiation source and the light-

And a control unit

(3) (i) a correction coefficient, which is obtained in advance so that the output change caused by the increase or decrease of the radiation detected by the above-described main detector coincides with the output change of the scattered ray component detected by the sub-detector described above, When the measured object moves in the direction of the optical axis perpendicular to the above-described pass line plane, the aforementioned correction coefficient is selected and multiplied from the output of the sub-detector described above, and the above- A correction calculation unit for obtaining a difference,

(ii) a thickness calculating section for obtaining the thickness from the output of the above-

And

Lt; / RTI >

The measurement error is corrected in real time by detecting a change in the scattering component when the object to be measured moves from the pass line surface to the vertical axis direction.

In order to achieve the above object, a radiation thickness gauge according to the present invention has the following configuration. In other words,

A radiation thickness gauge for measuring the thickness of a portion to be measured from a radiation dose of a transmitted radiation which is irradiated to a moving object to be measured and transmitted through the object,

(1) a C-shaped frame provided so as to sandwich the measured object in a direction perpendicular to a pass line plane for carrying the object to be measured,

(2) (i) a radiation source provided on one of the opposite arm portions of the C-type frame described above for irradiating the surface of the object to be measured in a direction perpendicular to the surface,

(ii) a main detector provided on the other arm portion for detecting the above-mentioned transmission radiation,

(iii) scattering scattering in the direction opposite to the irradiation direction of the above-mentioned radiation around the center of the optical axis of the solid angle formed by the above-mentioned center point of the irradiation surface of the radiation source and the light receiving surface of the above- Sub-detector for detecting line

And a control unit

(3) (i) a correction coefficient, which is obtained in advance so that the output change caused by the increase or decrease of the radiation detected by the above-described main detector coincides with the output change of the scattered ray component detected by the sub-detector described above, When the measured object moves in the direction of the optical axis perpendicular to the above-described pass line plane, the aforementioned correction coefficient is selected and multiplied from the output of the above-described sub-detector, and further, A correction operation section for obtaining the sum of

(ii) a thickness calculating section for obtaining the thickness from the output of the above-

And

Lt; / RTI >

The measurement error is corrected in real time by detecting a change in the scattering component when the object to be measured moves from the pass line surface to the vertical axis direction.

According to the present invention, it is possible to provide a radiation thickness gauge which is capable of correcting an error caused by upward and downward movement of an object to be measured without installing a new facility and improving the measurement accuracy.

FIGS. 1A and 1B are explanatory views for explaining the reasons for the occurrence of errors in a conventional radiation thickness gauge.
2A and 2B are block diagrams of a first embodiment of the present invention;
Figs. 3A and 3B are schematic diagrams of a second embodiment of the present invention; Fig.
4A and 4B are block diagrams of a third embodiment of the present invention.
Fig. 5 is an optical model diagram of the detection part of the present invention. Fig.
DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[First Embodiment]
Before explaining the embodiment of the present invention, first, the principle of the present invention will be described with reference to an optical model diagram of the detection unit shown in Fig.
5, the object to be measured 3, the dimension position the pass line plane (PL-0) in the case where the output of the output of the main detector (1b), unit detector (1c), respectively Vm _0, Vs ₀ And the output of the main detector 1b and the output of the sub detector 1c when the measured object 3 fluctuates to the position of the pass line plane PL + i are Vm _i and Vs _i , respectively, The increase of the forward scattering line detected by the first detector 1b and the increase of the forward scattering line detected by the secondary detector 1c are in a constant proportional relationship,
[Equation 1]
Vm _{0 -} Vs ₀ = Vm _{i -}留_i Vs _i
Here,? _I is a change in the dose of the scattered ray detected by the main detector 1b when the position of the measured object 3 is changed, and a change in the dose of the scattered ray detected by the sub detector 1c is apparently the same Is a correction coefficient for correcting to be canceled.
The correction coefficient? _I is determined by the optical setting condition of the detector that receives the transmission radiation based on the arrangement of the radiation source 1a, the main detector 1b and the sub-detector 1c of the detection unit that is set in advance, 3 and the amount of movement of the object 3 from the pass line surface.
When the thickness detection signal is corrected by the right side of the expression (1), the difference in sensitivity between the main detector 1b and the sub detector 1c and the sensitivity difference between the scatterer of the radiation transmitted through the object 3 and the main detector 1b and the distance to the sub-detector 1c.
Therefore, in the radiation thickness gauge including the main detector 1b and the sub-detector 1c, when the correction coefficient? _I is obtained, when the measured object 3 is on the pass line surface, The thickness is calibrated based on the difference between the output Vm of the sub detector 1c and the output Vs of the sub detector 1c and then the thickness of the object 3 is measured so as to satisfy the relation of the equation (1) The correction coefficient (? _I ) for which the measurement error at the time of movement is zero is obtained in advance, and the material, thickness, and pathline position of the measured object are tabulated as parameters.
Then, when the reference plate thickness t _r is set, the correction coefficient α _i of the table corresponding to the reference plate thickness t _r is selected to correct the output of the main detector 1b, The thickness is calculated.
Next, the configuration of the first embodiment based on the principle of the present invention will be described with reference to Fig. 2A. FIG. 2A is a block diagram of the present invention, and FIG. 2B is a plan view for explaining the arrangement of the main detector 1b and the sub-detector 1c.
2A, the radiation thickness gauge 10 is configured to irradiate the object 3 moving in the y-axis direction with radiation in the z-axis direction and to calculate the radiation dose from the radiation amount of the transmission radiation transmitted through the object 3 The thickness of the measured portion 3 is measured.
The C-type frame 1d has a C-type frame 1d and a C-type frame 1d. The C-type frame 1d has a z-axis direction perpendicular to the pass line plane for conveying the measured object 3, A main detector 1b provided on the other upper arm portion and a main detector 1b provided on the other lower arm portion of the main detector 1b and a central point of the irradiated surface of the radiation source 1a and a light receiving surface of the main detector 1b, And a sub-detector 1c for detecting a scattered ray of the radiation transmitted through the measurement object 3 in an annular structure around the main detector 1b provided at the center of the optical axis of the formed solid angle do.
Further, when the measured object 3 moves in the direction (z-axis direction) perpendicular to the pass line plane (xy plane), the output change due to the increase or decrease of the radiation detected by the main detector 1b, A correction operation section 2a for correcting the output of the sub-detector 1c so as to match the output variation of the scattered component detected by the main detector 1c and obtaining the difference between the main detector 1b and the sub-detector 1c, And a thickness calculating section (2b) for obtaining thickness from the output of the thickness measuring section (2a).
Next, the detailed configuration of each part will be described. When the X-ray is selected as the radiation, the radiation source 1a irradiates an X-ray tube capable of obtaining a dose necessary for measuring the thickness of the measurement object 3, and an X-ray tube having a high voltage power source for applying the X- The generator is selected.
The main detector 1a and the sub detector 1b are set so as to obtain a predetermined detection current by using an ionization box which is resistant to a temperature change and is easy to form in a form in which its shape and sensitivity are relatively flexible .
The sub-detector 1c is set so that scattered X-rays transmitted through the measured object 3 are obtained at a predetermined sensitivity around the main detector 1b. The sub-detector 1c may be constituted by one ionization box for detecting a scattering line in a specific region around the main detector 1b. However, a plurality of ionization chambers may be arranged around the main detector 1a in an annular shape Is preferable because spatial irregularity of scattered X-rays can be averaged.
The correction calculation unit 2a stores a table of correction coefficients? _I set in advance and outputs correction coefficients? ( _I ) from the outputs of the measured object 3 and the sub-detector 1b to the output of the sub- _i and a correction arithmetic circuit 2a2 for obtaining the difference between the output of the main detector 1b and the output of the correction coefficient circuit 2a1.
Next, from the output of the correction arithmetic circuit 2a2, the thickness calculating section 2b calculates a thickness deviation from the reference plate thickness t _r set from the outside with reference to a preset thickness calibration table.
The thickness calculation unit (2b) in, to the thickness (t _x) of the workpiece (3) blood from the output of the correction operation circuit (2a2) is obtained by the following equation.
&Quot; (2) "
t _x = 1 / μ? ln ((Vmn-Vsn) / (Vmx-Vsx))
Vmn and Vsn are outputs of the correction coefficient circuit 2a1 after correcting the output of the main detector 1b and the output of the sub detector 1c when the measured object 3 is not present and Vmx and Vsx Shows the output of the main detector 1b and the output of the correction coefficient circuit 2a1 when the measured object 3 exists, respectively.
Then, the thickness deviation output (Δt _x) at this time can be calculated by the following equation.
&Quot; (3) "
Δt _x = t _x -t _r
The calculation of the equation (1) is generally performed by digitizing the outputs of the main detector 1b and the correction calculating section 2a, respectively, and calculating the reference thickness t _r and (1) (T _x ) is obtained by referring to a previously obtained calibration table (also referred to as a calibration curve).
When the position of the measured object 3 is moved up and down in the direction of the optical axis, the radiation thickness gauge 10 corrected in this way automatically performs the thickness measurement by automatically correcting the change of the main detector from the output of the negative detector , It is possible to provide a radiation thickness meter which is corrected in real time.
[Second Embodiment]
A second embodiment of the present invention will be described with reference to Figs. 3A and 3B. In the second embodiment shown in Figs. 3A and 3B, the same parts as those in the first embodiment are denoted by the same reference numerals, and a description thereof will be omitted. The second embodiment differs from the first embodiment in that in the first embodiment, the sub-detector 1c is provided around the main detector 1b to detect the scattered X-rays of the X-rays transmitted through the measured object 3 The sub detector 1c is provided on the same arm portion of the radiation source 1a and the C-type frame 1d and the center point of the irradiation surface of the radiation source 1a and the center of the irradiation surface of the main detector 1. [ The scattering line scattering in the direction opposite to the irradiation direction of the radiation is detected around the center of the optical axis of the solid angle formed by the light receiving surface of the light receiving surface 1b.
In this case, when the measured object 3 moves in the direction of the main detector 1b, the scattered line component of the main detector Ib increases and the output of the sub detector 1b decreases inversely. Therefore, the correction coefficient (β _i), the correction coefficient (α _i), as shown below in place of the equation (1) is corrected using the correction coefficient (α _i) described in the first embodiment, equation (2) and Is obtained in advance by the same method, and added to the output of the main detector 1b.
&Quot; (4) "
Vm ₀ + Vs ₀ = Vm _i +? _I ? Vs _i
Since the direction of the scattered X-rays is different from that of the first embodiment with respect to the movement of the measured object 3 in the measurement space in this manner, the correction arithmetic operation unit 2a2 corrects the output of the main detector 1b And the output of the correction coefficient circuit 2a1 which corrected the output of the sub detector 1c.
Then, in the thickness calculating section (2b), the thickness (t _x) of the workpiece (3) blood from the output of the correction operation circuit (2a2), of the first embodiment (2) is obtained by the following (5) expression in place of expression .
&Quot; (5) "
t _x = 1 / μ? ln ((Vmn + Vsn) / (Vmx + Vsx))
The radiation thickness gage thus configured can reduce the space for installation when the space above the measured object 3 can not be made large.
[Third Embodiment]
A third embodiment of the present invention will be described with reference to Figs. 4A and 4B. 4A and 4B, the same parts as those of the first embodiment are denoted by the same reference numerals, and a description thereof will be omitted. The third embodiment is different from the first embodiment in that in the first embodiment, one sub-detector 1c is provided annularly around the main detector 1b to detect X Ray diffracted X-rays are detected. In Fig. 4B of the third embodiment, the sub-detector 1c1 and the sub-detector 1c2 are provided concentrically around the main detector 1b in a double-layered manner.
In this configuration, when the thickness measurement is performed on a multi-type product in which the scattering characteristics of the scattered X-rays from the measured object 3 are extremely different from each other as an object to be measured, based on the outputs of the two sub-detectors 1c1 and 1c2, The correction coefficient selection circuit 2a3 selects one of the sub-detector 1c1 or the sub-detector 1c2 in advance and outputs the output of the selected sub-detector 1c1 (or sub-detector 1c2) From the table and corrected by the correction coefficient selection circuit 2a3, and the correction calculation circuit 2a2 corrects the correction calculation based on the formula (1) and corrects it.
The radiation thickness gauge 10 thus configured can adjust the concentric diameter of the secondary detector in advance in accordance with the scattering characteristic of the scattered ray even when the forward scattering characteristic of the measured object 3 is extremely different, It becomes possible to correct the movement of the measurement object 3.
INDUSTRIAL APPLICABILITY As described above, according to the present invention, even when the scattering characteristic of the radiation of the measured object is extremely different, the measurement error when moving in the direction perpendicular to the pass line surface can be automatically corrected in real time.
In addition, the present invention is not limited to the above-described embodiment, and it is also possible to correct the increase or decrease in the output of the main detector when the measured object moves in the direction perpendicular to the plane of the pass line, And various modifications may be made without departing from the gist of the present invention.

1:
1a: source of radiation
1b: main detector
1c, 1c1 to 1c4:
1d: C type frame
2:
2a: correction operation section
2a1: correction coefficient circuit
2a2: correction operation circuit
2a3: Correction coefficient selection circuit
2b:
3: Measured object

Claims (6)

There is provided a radiation thickness gauge for measuring the thickness of a workpiece from a radiation dose of the radiation transmitted through the workpiece by irradiating the moving workpiece with radiation,
(1) a C-shaped frame provided so as to sandwich the measured object in a direction perpendicular to a plane of the pass line for conveying the measured object,
(2) (i) a radiation source provided on one of the opposite arm portions of the C-shaped frame,
(ii) a main detector provided on the other arm portion for detecting the transmission radiation,
(iii) a sub-detector for detecting a scattering line scattered from the object around the main detector provided at the center of the optical axis of the solid angle formed by the center of the irradiation surface of the radiation source and the light receiving surface of the main detector
And a control unit
(3) a correction coefficient storage unit that stores (i) a correction coefficient that is obtained in advance so that an output change caused by the increase or decrease of the radiation detected by the main detector coincides with an output change of the scattered line component detected by the sub- Detector for selecting the correction coefficient from the output of the sub-detector and obtaining a difference between the main detector and the sub-detector when the light source moves in the optical axis direction perpendicular to the pass line plane,
(ii) a thickness calculating section for obtaining a thickness from the output of the correction calculating section
And
Lt; / RTI >
Wherein a change in the scattering component when the measured object moves in the vertical axis direction from the pass line surface is detected and the measurement error is corrected in real time. The radiation thickness gauge according to claim 1, wherein the correction coefficient is a table of the material and thickness of the measured object and the measured position of the measured object as parameters. The radiation gauge according to claim 1, wherein the sub-detector is provided with an annular light-receiving surface around the main detector to detect scattering lines of the transmission radiation. The sub-detector according to claim 1, wherein the sub-detector comprises two detectors having annular light receiving surfaces of different diameters around the center of the optical axis with respect to the center of the optical axis, and based on the outputs of the two detectors, And the output of one of the selected detectors is corrected by multiplying the corresponding correction coefficient. There is provided a radiation thickness gauge for measuring the thickness of a workpiece from a radiation dose of the radiation transmitted through the workpiece by irradiating the moving workpiece with radiation,
(1) a C-shaped frame provided so as to sandwich the measured object in a direction perpendicular to a plane of the pass line for conveying the measured object,
(2) (i) a radiation source provided on one of the opposite arm portions of the C-shaped frame for irradiating the surface of the object to be measured in a direction perpendicular to the surface,
(ii) a main detector provided on the other arm portion for detecting the transmission radiation,
(iii) a scattering line provided in the one arm portion and scattering in a direction opposite to the irradiation direction of the radiation around the center of the optical axis of the solid angle formed by the center of the irradiation surface of the radiation source and the light receiving surface of the main detector Secondary detector
And a control unit
(3) a correction coefficient storage unit that stores (i) a correction coefficient that is obtained in advance so that an output change caused by the increase or decrease of the radiation detected by the main detector coincides with an output change of the scattered line component detected by the sub- Detector for calculating the sum of the main detector and the corrected sub-detector when the correction coefficient is shifted in the direction of the optical axis perpendicular to the pass line plane,
(ii) a thickness calculating section for obtaining a thickness from the output of the correction calculating section
And
Lt; / RTI >
Wherein a change in the scattering component when the measured object moves in the vertical axis direction from the pass line surface is detected and the measurement error is corrected in real time. The radiation thickness gauge according to claim 5, wherein the sub-detector is provided with an annular light-receiving surface with respect to the center of the optical axis, and receives the scattering line of the radiation scattered from the object to be measured.

Images