JP2000258146A - Radiation thickness measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively use the radiation beam of a radiation unit for detection and to perform highly accurate measurement. SOLUTION: A frame 10 is provided with the radiation unit 11 and a sensor unit 40 so as to hold an object 20 to be measured therebetween, the object 20 to be measured is irradiated with the radiation beam 30 generated from the radiation unit 11, a transmitted radiation beam accompanying the irradiation is detected by the sensor unit 40 and the thickness of the object 20 to be measured is computed based on the detection signal by an arithmetic unit 14. In this case, the sensor unit 40 is constituted of plural sensors 40a and one thickness measured value is obtained by the plural sensors 40a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation thickness measuring apparatus for measuring the thickness of an object to be measured such as a steel plate using a radiation beam.

[0002]

2. Description of the Related Art Conventionally, this type of radiation thickness measuring apparatus has a configuration as shown in FIG. That is, in FIG. 14, a radiation unit 11 having a radiation source 11a for irradiating a radiation beam 30 to an upper portion is provided below the frame 10, and the radiation beam 3 from the radiation unit 11 is provided.
A sensor unit 12 that receives 0 and converts it into an electric signal is arranged on the upper part of the frame 10.

The device under test 20 is inserted between the radiation unit 11 and the sensor unit 12. The radiation beam 30 generated from the radiation unit 11 is applied to the device under test 20. Here, the radiation beam 30 is attenuated by the device under test 20, the transmitted radiation beam is detected by the sensor unit 12, and the detection signal is sent to the arithmetic unit 13. The thickness of the beam irradiation position on the DUT 20 is obtained based on the following equation.

[0004]

However, in the above-mentioned conventional radiation thickness measuring apparatus, the object to be measured 20
Even if the radiation unit 11 and the sensor unit 12 are arranged to face each other in a predetermined positional relationship, even if the radiation unit 11 and the sensor unit 1
In some cases, the relative positional relationship with No. 2 changed.

The change in the relative positional relationship between the radiation unit 11 and the sensor unit 12 is caused by the change in the radiation unit 11.
This hinders the effective use of the radiation beam generated from the device, and hinders the high-precision measurement of the DUT 20.

[0006] It is an object of the present invention to provide a radiation thickness measuring apparatus capable of high-accuracy measurement.

[0007]

In the present invention, the sensor unit is divided into, for example, four equal parts in the horizontal direction. A radiation beam emitted from the radiation unit is directly received by the sensor unit without an object to be measured. If the signal of each sensor of the sensor unit at this time is the same, it means that the center of the sensor unit coincides with the center of gravity of the radiation beam. Further, when there is a variation in the signals of the sensors of the sensor unit, the center of gravity is shifted relative to the variation. Since the center of gravity is shifted, it is possible to detect a relative position shift between the sensor unit and the radiation unit and an abnormality of the radiation beam.

In addition, the displacement of the center of gravity between the sensor unit and the radiation unit is detected, and the sensor unit is moved by the moving unit, so that the position of the sensor unit can be adjusted so that the center always coincides with the center of gravity of the radiation beam. .

Further, when the object to be measured is inclined in the width direction,
By dividing the sensor unit in the width direction, the ratio of the transmitted radiation beam changes according to the inclination of the measured object. From this, conversely, the inclination of the object to be measured can be obtained from the ratio of the transmitted radiation beam, and the thickness measurement value can be corrected.

In order to detect the edge of the object to be measured, the sensor unit is divided in the moving direction of the object to be measured. The sensor can measure the position of the end of the measured object based on the attenuation of the radiation beam.

Further, when there is a change in the thickness of the object to be measured, the movement of the object to be measured is measured by an encoder so that the length of the object to be measured can be measured, and a pulse is input from the encoder. By dividing the sensor unit into two equal parts in the width direction of the measured object, when the measured object has a thickness change, the thickness change point can be accurately obtained.

In the case where the sensor unit is composed of sensors divided into a plurality of parts in the moving direction of the object to be measured, the measured value of the sensor corresponding to the foreign object among the sensors is adopted. The thickness can be measured by using the measurement value of the sensor that does not correspond to the foreign matter.

Further, when the object to be measured is a steel plate, when it is desired to detect a minute thickness change such as a roll roll flaw,
By dividing the sensor unit, the rate of change of the radiation beam increases, so that a minute thickness change can be easily detected.

Further, in a situation where the object to be measured is intruding, by using a finely divided sensor on the intruding side of the object to be measured, for example, by using a combination of a scintillator and a semiconductor photosensor, the smaller the sensor, the higher the response. Is obtained, and the thickness of the object to be measured can be measured with little time delay at the time of entry.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. 1 to 13,
The same parts as those in FIG. 14 are denoted by the same reference numerals.

As shown in FIGS. 1 and 2, in the radiation thickness measuring apparatus according to the present embodiment, a steel plate moving in a certain direction is used as the object 20 to be measured. A radiation unit 11 is provided below the C-shaped frame 10, and a sensor unit 40 having a plurality of sensors 40a is provided above the frame 10.

Further, as shown in FIG. 2, the thickness on the measurement line 50 can be continuously measured by moving the device under test 20 in a constant manner.

In the embodiment shown in FIGS. 3 and 4,
The sensor unit 60 is divided into four equal parts in the horizontal direction, and has four sensors 60a, 60b, 60c, and 60d. The four sensors 60a, 60b, 60c, and 60d convert the radiation beam generated from the radiation unit 11 into electric signals. The sensor unit 60 includes a scintillator for converting radiation into visible light and a photodiode.

Normally, if the center of gravity of the radiation beam and the center of the sensor unit 60 coincide with each other without the device under test 20, the signals of the sensors 60a, 60b, 60c, and 60d are equivalent.

If the center of gravity of the radiation beam deviates from the center of the sensor unit 60 in a state where the object to be measured 20 is not present, the signals of the sensors 60a, 60b, 60c, and 60d differ according to the deviation.

In this case, by aligning the center of gravity of the radiation beam with the center of the sensor unit 60 as much as possible,
Each of the beams 0a, 60b, 60c, and 60d has the beam characteristics shown in FIG. 4, and it is possible to acquire a radiation beam with the largest amount of the sensor units 60, thereby enabling more accurate measurement.

Also, the initial sensor signal state is stored in, for example, the arithmetic unit 14 and compared with the subsequent signal values to detect the displacement of the center of gravity of the radiation beam and to determine the displacement between the center of gravity of the radiation beam and the center of the sensor unit 60. It is possible to determine the beam abnormality due to the mismatch.

Next, another embodiment will be described with reference to FIG. As shown in FIG. 5, in the present embodiment, a moving unit 70 is provided in the sensor unit 50. With this configuration, the sensor unit 50 is moved by the operation of the moving unit 70 so that the center of gravity of the radiation beam coincides with the center of the sensor unit 50, so that the largest amount of radiation beam is always obtained, and more accurate measurement is performed. It is possible to do.

Next, another embodiment will be described with reference to FIG. As shown in FIG. 6, in this embodiment, as shown in FIGS. 6A and 6C, the sensor unit is divided into three sensors at the left, right, and center in the moving direction of the measured object. The left sensor is S1, the center sensor is S2, and the right sensor is S3. Sensor S1 and sensor S3 are made small. As shown in FIG. 6B, if there is no inclination of the measured object, the calculated value L1a of the sensor S1 and the calculated value L3a of the sensor S3 are usually equal. In this case, the calculated value L2a of the sensor S2 is equal. And the average of the three values is taken as the measured thickness value La of the measured object.

La = (L1a + L2a + L3a) / 3 As shown in FIG. 6 (c), if the object to be measured is inclined, the thickness calculation value L1b by the sensor S1 and the calculation value L3b by the sensor S3 are: There is a difference. By obtaining the difference and the inclination θ in advance and storing them in the arithmetic unit 14, the inclination θ can be obtained from the difference. If there is an inclination, the measured value of the thickness of the measured object increases. Sensor S2
The thickness Lb of the measured object is obtained from the calculated value L2b × cos θ ((d) in FIG. 6).

Next, another embodiment will be described with reference to FIG. As shown in FIG. 7, in the present embodiment, the sensor unit 60 is divided into two equal parts in the moving direction of the device 20 to be measured, and is the sensors 60 a and 60. When the radiation beam of the sensor 60b starts to attenuate, the thickness of the device under test 20 is measured by the sensor 60a. Assuming that the thickness is t, the sensor 60b
The incident radiation beam can be calculated at the position X at the end of the measured object 20 if the thickness t of the measured object 20 is known.
That is, the position of the end of the DUT 20 can be calculated from the amount of the radiation beam.

If only the position at the center of the sensor is used,
When the radiation beam is attenuated by the sensor 60a and the radiation beam of the sensor 60b is attenuated, it can be measured that the end of the device under test 20 is substantially at the center of the sensor.

Next, another embodiment will be described with reference to FIG. As shown in FIG. 8, in the present embodiment, in the case of the DUT 20A having a change in thickness, an example in which the thickness change point can be accurately obtained. The sensor unit 60 of the present embodiment is divided into two equal parts in the width direction of the device under test 20A to obtain sensors 60a and 60b.

Then, as shown in FIG. 9, if the entry side is tapered and thereafter a flat portion, the change point is obtained by the movement of the DUT 20A by the pulse encoder 80, and the thickness of the sensor 60a is reduced. The length from the point where the measurement is started to the point where the thickness does not change by the sensor 60b is the change position. In FIG. 9, the sensor unit 60 has no division (1
(The number of sensors) and the signal values when the sensor unit 60 is divided into the sensors 60a and 60b, and a point at which the thickness of the DUT 20A changes due to a change in these signal values is detected. can do.

Further, as shown in FIG.
When B becomes a tapered portion from a flat place, the sensor 60
The length from the point where a starts measuring the thickness to the point where the thickness does not change with the sensor 60a is the change position. FIG.
Similarly, FIG. 10 also shows a signal value when the sensor unit 60 is not divided (one sensor) and a signal value when the sensor unit 60 is divided into sensors 60a and 60b, and changes in these signal values. The object to be measured 20A
The point at which the thickness has changed can be detected.

As shown in FIGS. 11 and 12, the sensor unit 40 is divided into three in the movement direction,
S3. For example, when the thickness measurement value of the sensor S2 becomes larger than the thickness measurement values of the sensor S1 and the sensor S3 due to the foreign matter 20c or the like as shown in FIG. 11, the measurement value of the sensor S2 is discarded and the sensor S1 and the sensor S3 The average value of the thickness data. The discard threshold is set by the arithmetic unit 14.

Also, as shown in FIG. 12, in the case of detecting the roll flaw 20d by the rolling roll, the use of the sensor 40 divided as described above is more effective than the case of using one sensor for measurement. , The detection capability is increased. Further, by calculating whether or not the flaw 20d is periodically generated along the longitudinal direction of the measured object 20, it is possible to determine that the flaw 20d of the measured object 20 is a roll flaw. .

Furthermore, in the present invention, FIG.
The sensor unit shown in (d) can be adopted.
The sensor unit 60A shown in FIG. 13A includes sensors 60e and 6 divided into two equal parts in the width direction of the measured object (not shown).
0f. Sensor unit 6 shown in FIG.
OB has sensors 60g and 60h equally divided in the longitudinal direction of the object to be measured (not shown). The sensor unit 60 shown in FIG. 13C is the same as that shown in FIGS. It has sensors 60g and 60h equally divided in the longitudinal direction of the object to be measured (not shown).

As shown in FIG. 13D, the sensor unit is divided in the longitudinal direction of the measured object, and the size of the sensor 60i on the entry side of the measured object is reduced. The sensor unit 60C is a combination of a scintillator and a photodiode. The smaller the photodiode, the quicker the response. This increases the responsiveness of the object to be measured when the object enters the plate. After the measurement, when the measured thickness of the large sensor 60j falls within a predetermined difference from the measured value of the small sensor 60i, the measured thickness of the large sensor 60j is measured. Is adopted. This is because the larger sensor 60j has lower responsiveness, but has a larger signal value and can obtain a more stable and accurate measurement value.

[0035]

As described above, according to the present invention, a sensor unit including a plurality of sensors is used, and a radiation beam generated from the radiation unit is sandwiched between the sensor unit and the radiation unit so as to sandwich an object to be measured. The object to be measured is irradiated, the transmitted radiation beam accompanying the irradiation is detected by the sensor unit, and the thickness of the object to be measured is calculated by the calculation unit based on the detection signal. Even if the positional relationship with the radiation unit changes, the changed positional relationship can be corrected by correcting the output of each sensor constituting the sensor unit, so that the radiation beam of the radiation unit can be used effectively for detection. Accordingly, it is possible to provide a radiation thickness measuring device capable of performing high-accuracy measurement.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an embodiment of a radiation thickness measuring apparatus according to the present invention.

FIG. 2 is a partial perspective view of one embodiment of the radiation thickness measuring apparatus of the present invention.

FIG. 3 is a diagram showing a configuration of another embodiment of the radiation thickness measuring apparatus of the present invention.

FIG. 4 is a view showing characteristics of beam intensity in the apparatus of FIG. 3;

FIG. 5 is a diagram showing a configuration of another embodiment of the radiation thickness measuring apparatus of the present invention.

FIG. 6 is a diagram showing a state of thickness measurement when an object to be measured is inclined.

FIG. 7 is a diagram showing a situation in which the position of an end of an object to be measured is detected by a two-division sensor. Example of sensor division

FIG. 8 is a diagram showing a situation in which a sensor which is divided into two equal parts in the width direction of an object to be measured and a movement of the object to be measured are pulse-detected by an encoder.

FIG. 9 is a diagram showing one situation in which the thickness of an object to be measured having a thickness change is measured by using two equally divided sensors.

FIG. 10 is a diagram showing another situation in which the thickness of a measurement object having a thickness change is measured by using equally divided sensors.

FIG. 11 is a diagram showing a situation in which a measured value due to a foreign substance and a measured value due to a roll flaw are obtained from each measured value of a sensor divided into three in the moving direction of the measured object.

FIG. 12 is a diagram showing a situation in which a measured value due to a foreign substance and a measured value due to a roll flaw are obtained from each measured value of the sensor divided into three in the moving direction of the measured object. .

FIG. 13 is a view showing various aspects of a sensor unit.

FIG. 14 is a diagram showing an example of a conventional radiation thickness measuring device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Frame 11 ... Radiation unit 14 ... Calculation unit 20 ... Measurement object 30 ... Radiation beam 40,60 ... Sensor unit 70 ... Moving unit

Claims (12)

[Claims] A radiation unit and a sensor unit are provided on a frame so as to sandwich an object to be measured, a radiation beam generated from the radiation unit is irradiated on the object, and a transmitted radiation beam accompanying the irradiation is transmitted to the sensor. A radiation thickness measuring device that detects by a unit and calculates the thickness of the object to be measured based on the detection signal by a calculation unit, wherein the sensor unit is configured by a plurality of sensors, and the thickness is determined by the plurality of sensors. A radiation thickness measuring device for obtaining a measured value. 2. The apparatus according to claim 1, further comprising means for relatively moving at least the radiation unit and the sensor unit and the object to be measured, wherein the thickness of the object at different positions is continuously measured. The radiation thickness measuring device according to claim 1, wherein 3. The radiation thickness measuring apparatus according to claim 1, wherein said sensor unit is divided into four equal parts vertically and horizontally when viewed from a beam irradiation direction. 4. A means for calculating a beam intensity barycentric position of a radiation beam from a difference in signal value of each sensor of the sensor unit when a radiation beam is generated from the radiation unit without the object to be measured. 4. The thickness measuring device according to claim 3, wherein: 5. The radiation thickness according to claim 4, further comprising means for comparing the positions of the center of gravity of the beam intensity measured at different times, and judging an abnormality when the position is shifted by a predetermined value or more. Measuring device. 6. A driving unit for moving at least one of the sensor unit and the radiation unit, wherein the driving unit is driven such that the beam intensity center of gravity is set at a predetermined position. Item 5
The radiation thickness measuring device according to the above. 7. The signal unit of each sensor of the sensor unit when a radiation beam is generated from the radiation unit without the object to be measured, and the radiation unit when the object to be measured is present. Calculating the inclination of the object to be measured based on the difference between the signal value of each sensor of the sensor unit and the signal ratio when the radiation beam is generated from the sensor unit, and correcting the thickness of the object to be measured based on the inclination. The radiation thickness measuring device according to claim 1, wherein: 8. The sensor unit has a sensor which is divided into two in a moving direction of the object to be measured, and calculates a thickness of the object to be measured in a state where the object to be measured is inserted into one of the sensors and to determine the thickness of the other one of the sensors. When the radiation beam amount A when the object to be measured is inserted into the sensor at a predetermined value is calculated in advance, and the radiation beam amount B when the object to be measured is inserted is calculated, and when A = B 3. The radiation thickness measuring apparatus according to claim 2, further comprising means for detecting that an end of the object is at a predetermined position. 9. The sensor unit has a sensor divided into two equal parts in the width direction of the object to be measured and a length measuring means for the object to be measured, and the thickness of the two equally divided sensors is measured. 3. The radiation thickness measuring apparatus according to claim 2, wherein a thickness change position of the measured object is measured based on a value and an output of the length measuring means. 10. The sensor unit is divided into two parts in the width direction of the object to be measured, and is configured so as to increase the responsiveness by reducing the size of the sensor on the entry side of the object to be measured. 3. The radiation thickness measuring apparatus according to claim 2, wherein the radiation thickness measuring apparatus is configured to obtain a signal that is slow but small in noise, and performs the thickness measurement by switching signals of both sensors. 11. The sensor unit has at least three sensors, and excludes a measurement value deviating from a mean value of the thickness measurement values of each sensor by a predetermined value to obtain an average value again.
2. The radiation thickness measuring apparatus according to claim 1, wherein the average value is a measured value. 12. The sensor unit has a plurality of sensors divided in a moving direction of the object to be measured, and a thickness measurement value is obtained by each sensor to detect a change in the thickness of the object to be measured. 3. The radiation thickness measuring apparatus according to claim 2, wherein: