X-ray thickness meter

Abstract

To provide an X-ray thickness meter with which measurement errors attributable to the fouling of an X-ray transmission window can be suppressed.SOLUTION: The X-ray thickness meter according to an embodiment comprises: an X-ray generation unit capable of generating an X-ray; a housing for accommodating the X-ray generation unit; an X-ray transmission window disposed on a wall surface of the housing and capable of transmitting an X-ray; an X-ray detection unit located facing the outer surface of the X-ray transmission window and capable of detecting the dosage of an X-ray radiated via the X-ray transmission window; an air purge device capable of spraying a gas along the outer surface of the X-ray transmission window; a liquid purge device capable of spraying a liquid toward the outer surface of the X-ray transmission window; and a control unit for executing, on the basis of X-ray dosages detected by the X-ray detection unit before and after measurement is taken of the thickness of a measurement object, control on spraying of a liquid toward the outer surface of the X-ray transmission window by the liquid purge device and / or control on spraying of a gas along the outer surface of the X-ray transmission window by the air purge device.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] Embodiments of the present invention relate to an X-ray thickness gauge.

Background Art

[0002] Conventionally, a technique for measuring the thickness of an object to be measured from the amount of attenuation when X-rays are irradiated onto the object to be measured and the X-rays are attenuated as they pass through the object to be measured is known. Such a technique for measuring thickness using X-rays is used, for example, in the rolling process of steel plates and the like to measure the thickness of steel plates.

[0003] Generally, an X-ray thickness gauge irradiates an object to be measured with X-rays through an X-ray transmission window provided in a housing that houses an X-ray generator. Therefore, when dirt adheres to the X-ray transmission window, the X-rays are attenuated by the dirt, resulting in an error in the measurement.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0005] As described above, the conventional X-ray thickness gauge has a problem that a measurement error may occur when dirt adheres to the X-ray transmission window provided in the housing that houses the X-ray generator. An object of embodiments of the present invention is to provide an X-ray thickness gauge capable of suppressing a measurement error caused by dirt on the X-ray transmission window.

Means for Solving the Problems

[0006] The X-ray thickness gauge according to the embodiment irradiates a plate-shaped object to be measured with X-rays to measure the thickness of the object to be measured. The X-ray thickness gauge according to the embodiment includes an X-ray generation unit capable of generating X-rays, a housing that houses the X-ray generation unit, an X-ray transmission window disposed on a wall surface of the housing and capable of transmitting X-rays, an X-ray detector disposed to face an outer surface of the X-ray transmission window and capable of detecting the dose of X-rays radiated through the X-ray transmission window, an air purge device capable of injecting gas along the outer surface of the X-ray transmission window, a liquid purge device capable of injecting liquid toward the outer surface of the X-ray transmission window, and a control unit that executes at least one of control of injecting liquid toward the outer surface of the X-ray transmission window by the liquid purge device and control of injecting gas along the outer surface of the X-ray transmission window by the air purge device based on the dose of X-rays detected by the X-ray detector before and after measuring the thickness of the object to be measured.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0008] (Configuration of Embodiment) Hereinafter, with reference to the drawings, the X-ray thickness gauge according to the embodiment will be described in detail. FIG. 1 is a view showing the external appearance of the X-ray thickness gauge 1 according to the embodiment. FIG. 2 is a block diagram showing the configuration of the X-ray thickness gauge 1 according to the embodiment.

[0009] As shown in FIG. 1, the X-ray thickness gauge 1 according to the embodiment includes a housing 11, an X-ray detector 12, an X-ray transmission window 13, and a purge device 30.

[0010] The housing 11 is a structure that houses the functional elements of the X-ray thickness gauge and enables the irradiation of the object to be measured with X-rays. The housing 11 is configured to be open in the moving direction T of the object to be measured so that the object to be measured can pass through the space G irradiated with X-rays. The housing 11 is configured to be reciprocally movable, for example, in one direction (M direction) orthogonal to the moving direction (T direction) in which the object to be measured flows. The housing 11 holds the X-ray detector 12 on one side in the thickness direction of the object to be measured passing in the T direction. Similarly, the housing 11 houses the X-ray generator 14 on the other side in the thickness direction of the object to be measured passing in the T direction.

[0011] In the example shown in FIG. 1, the housing 11 includes an upper frame 11a that extends horizontally in the installed state of the housing 11, a lower frame 11b arranged in parallel with the upper frame 11a, and a vertical frame 11c that connects the upper frame 11a and the lower frame 11b at one end thereof. That is, the housing 11 is configured to surround the object to be measured moving in the T direction by the upper frame 11a, the lower frame 11b, and the vertical frame 11c.

[0012] In the example shown in FIG. 1, the housing 11 has, for example, an X-ray detector 12 disposed on the lower wall surface of the upper frame 11a. Similarly, the housing 11 has an X-ray generator housed in the lower frame 11b. An X-ray transmission window 13 is disposed on the wall surface (upper wall surface) of the lower frame 11b facing the X-ray detector 12 disposed on the upper frame 11a. That is, the parallel upper frame 11a and the lower frame 11b have the opposed X-ray transmission window 13 and the X-ray detector 12, enabling X-ray radiation (X in the figure) perpendicular to the object to be measured passing therebetween in the T direction.

[0013] The X-ray thickness gauge 1 irradiates X-rays through the X-ray transmission window 13 onto a predetermined range of the object to be measured that passes through the space G in the T direction. The X-rays that have passed through the object to be measured are detected by the X-ray detector 12. The X-ray thickness gauge 1 calculates the thickness of the object to be measured based on the detected X-ray dose. The object to be measured is exemplified by, for example, a plate-shaped steel plate. Such an X-ray thickness gauge 1 is disposed, for example, on the manufacturing line of the steel plate that is the object to be measured and on the conveyance path along which the steel plate is conveyed in one direction.

[0014] The X-ray detector 12 is a functional element capable of detecting the X-ray dose. The X-ray detector 12 is configured to convert the detected X-ray dose into a detection signal and transmit it to the control device 20. The X-ray detector 12 is disposed opposite to the outer surface of the X-ray transmission window 13 on the lower wall surface of the upper frame 11a. The X-ray detector 12 can be realized by, for example, an ionization chamber or the like.

[0015] The X-ray transmission window 13 is a window member made of a material that can transmit X-rays. In this embodiment, the X-ray transmission window 13 is disposed on the upper wall surface of the lower frame 11b and on the straight line connecting the X-ray generator 14 and the X-ray detector 12, which will be described later.

[0016] As shown in FIG. 2, the X-ray generator 14 is a functional element housed in the lower frame 11b of the housing 11 and capable of generating X-rays. The X-ray generator 14 is disposed at a position where it can irradiate X-rays toward the X-ray detector 12 through the X-ray transmission window 13. The X-ray generator 14 is configured to be able to irradiate X-rays with a predetermined reference dose when a predetermined tube voltage and tube current are supplied. The X-ray dose generated by the X-ray generator 14 can be controlled by an X-ray generator control signal Xg from the outside.

[0017] The purge device 30 is a functional element that cleans the outer surface of the X-ray transmission window 13 facing the object to be measured. The purge device 30 cleans (purges) the outer surface of the X-ray transmission window 13 using at least one of a gas (air) and a liquid (water). In the following description, the cleaning using air is referred to as air purge, and the cleaning using water is referred to as water purge. The purge device 30 includes an air purge device 30a that performs air purge and a water purge device 30b that performs water purge.

[0018] The air purge device 30a includes an air supply source 31, an air purge nozzle 32, an air pipe 33, and a solenoid valve 34. The water purge device 30b includes a water supply source 35, a water purge nozzle 36, a water pipe 37, and a solenoid valve 38.

[0019] The air supply source 31 is, for example, a tank that stores a gas (air) for air purging. The air supply source 31 is filled with air at a predetermined pressure in order to supply air at a predetermined pressure during air purging. The air supply source 31 can be accommodated, for example, within the housing 11.

[0020] The air purge nozzle 32 is an injection nozzle that purges the outer surface of the X-ray transmission window 13. The air purge nozzle 32 is configured to be able to blow out air along the outer surface of the X-ray transmission window 13. The air purge nozzle 32 is disposed at the outer peripheral portion of the outer surface of the X-ray transmission window 13 on the upper wall surface of the lower frame 11b. The air purge nozzle 32 functions to blow off the dirt on the outer surface of the X-ray transmission window 13 along the outer surface of the X-ray transmission window 13. The air purge nozzle 32 is connected to the air supply source 31 via the air pipe 33.

[0021] The solenoid valve 34 is a valve device disposed in the air pipe 33 that connects the air purge nozzle 32 and the air supply source 31. The solenoid valve 34 can be controlled to open and close from the outside by an air valve control signal a. Further, the solenoid valve 34 can control the amount of air supplied to the air purge nozzle 32 by the air valve control signal a.

[0022] The water supply source 35 is, for example, a tank that stores a liquid (water) for water purging. The water supply source 35 may have a pump (not shown) or the like in order to supply water at a predetermined pressure during water purging. The water supply source 35 can be accommodated, for example, within the housing 11.

[0023] The water purge nozzle 36 is an injection nozzle that purges the outer surface of the X-ray transmission window 13 with water. The water purge nozzle 36 is configured to be able to blow out water toward the outer surface of the X-ray transmission window 13 from a direction at a predetermined angle θ with respect to the outer surface of the X-ray transmission window 13. That is, the water purge nozzle 36 is disposed at the peripheral edge of the outer surface of the X-ray transmission window 13 on the upper side wall surface of the lower frame 11b. Further, the water purge nozzle 36 is disposed at a position and in a direction such that it can inject water at a predetermined angle θ toward the X-ray transmission window 13. The water purge nozzle 36 functions to blow off dirt by the liquid directed toward the outer surface of the X-ray transmission window 13. The water purge nozzle 36 is connected to a water supply source 35 via a water pipe 37.

[0024] The angle θ formed by the water purge nozzle 36 and the X-ray transmission window 13 may be any angle as long as the water sprayed from the water purge nozzle 36 can be directly sprayed onto the outer surface of the X-ray transmission window 13.

[0025] The electromagnetic valve 38 is a valve device disposed in the water pipe 37 connecting the water purge nozzle 36 and the water supply source 35. The electromagnetic valve 38 can be controlled to open and close from the outside by a water valve control signal w. Further, the electromagnetic valve 38 can control the amount of water supplied to the water purge nozzle 36 by the water valve control signal w.

[0026] In air purge, if air is directly blown onto the X-ray transmission window 13, there is a possibility that surrounding dirt may be involved and dust etc. cannot be dropped from the outer surface of the X-ray transmission window 13. Therefore, the air purge nozzle 32 is disposed at a position and in a direction such that air can be blown along the outer surface of the X-ray transmission window 13 in parallel. That is, the air purge nozzle 32 is configured such that air does not directly blow onto the outer surface of the X-ray transmission window 13.

[0027] On the other hand, in water purge using water, it is possible to drop heavy dirt by using water having a larger mass than air. Therefore, the water purge nozzle 36 is disposed at a position and in a direction such that water can be directly blown onto the outer surface of the X-ray transmission window 13.

[0028] In the X-ray thickness gauge 1 of the embodiment, in addition to air purge, water purge can be performed for the X-ray transmission window 13. According to the X-ray thickness gauge 1 of the embodiment, by adding water purge, it is possible to remove oil and scale stains that could not be removed only by air.

[0029] The control device 20 shown in FIG. 2 is a functional element that realizes measurement control as an X-ray thickness gauge and purge control by the purge device 30. As shown in FIG. 2, the control device 20 includes a dose acquisition unit 21, a calculation unit 22, a storage unit 23, and a valve control unit 24. The control device 20 is electrically connected to the X-ray detector 12, the X-ray generator 14, and the electromagnetic valves 34 and 38. The control device 20 can be realized by a computer including a CPU, a main storage device, an auxiliary storage device, and the like.

[0030] The dose acquisition unit 21 is a functional element that receives the detection result (detection signal Xd) of the X-ray detector 12. The dose acquisition unit 21 may include an amplifier that amplifies the detection signal Xd detected by the X-ray detector 12 and a conversion unit that converts the detection signal into a signal that can be processed by the calculation unit 22.

[0031] The calculation unit 22 is a functional element that executes a program developed in a memory serving as a main storage device (not shown). The calculation unit 22 can be realized by, for example, a CPU or the like. The storage unit 23 is an information storage medium serving as an auxiliary storage device. The storage unit 23 is a functional element that can store the dose of X-rays acquired by the dose acquisition unit 21, the detection signal, the measurement result as an X-ray thickness gauge, and the like. The storage unit 23 can be realized by, for example, a hard disk drive (HDD) or a solid state drive (SSD).

[0032] The calculation unit 22 has a function of calculating the thickness of the object to be measured by calculating the detection signal acquired by the dose acquisition unit 21. Specifically, the calculation unit 22 stores, in the storage unit 23 as a calibration curve, a calibration curve for the entire measurement range created in advance using a calibration reference plate as a calibration curve. The calculation unit 22 calculates the plate thickness of the object to be measured by applying the detection signal obtained by the X-ray detector 12 through the object to be measured to the calibration curve.

[0033] Further, the arithmetic unit 22 has a function of detecting dirt on the outer surface of the X-ray transmission window 13. The detection of dirt can be realized by comparing the doses (detection signals) before and after the measurement of the object to be measured. Specifically, the arithmetic unit 22 first causes the storage unit 23 to store a reference dose (detection signal X0). The reference dose (detection signal X0) is the dose (detection signal) detected by the X-ray detector 12 through the X-ray transmission window 13 for the X-rays emitted by the X-ray generator 14 in a state where the object to be measured is not passed through the space G in advance.

[0034] After the reference dose is stored in the storage unit 23, the arithmetic unit 22 measures (calculates) the thickness of the object to be measured. After the thickness measurement of the object to be measured is executed, the arithmetic unit 22 causes the X-ray detector 12 to detect the X-rays emitted by the X-ray generator 14 through the X-ray transmission window 13 again in a state where the object to be measured is not passed through the space G, and obtains the dose of the X-rays (detection signal X1). The arithmetic unit 22 compares the reference dose (detection signal X0) with the dose (detection signal X1) after the thickness measurement of the object to be measured. These difference values serve as an index indicating that the outer surface of the X-ray transmission window 13 is dirty in the thickness measurement of the object to be measured. The arithmetic unit 22 can determine that the X-ray transmission window 13 is contaminated when the difference value exceeds a predetermined value as a result of the comparison.

[0035] Furthermore, the arithmetic unit 22 has a function of controlling the X-ray dose generated by the X-ray generator 14. The arithmetic unit 22 can transmit an X-ray generator control signal Xg to control the tube voltage and tube current for generating X-rays in the X-ray generator 14.

[0036] The valve control unit 24 is a functional element that controls the opening and closing of the electromagnetic valves 34 and 38. The valve control unit 24 transmits an air valve control signal a to the electromagnetic valve 34 to control the opening and closing of the electromagnetic valve 34. For example, when performing air purge by the air purge nozzle 32, the valve control unit 24 transmits an air valve control signal a for opening the valve to the electromagnetic valve 34. When receiving the air valve control signal a for opening the valve, the electromagnetic valve 34 opens the valve and supplies the air from the air supply source 31 to the air purge nozzle 32.

[0037] Similarly, the valve control unit 24 transmits a water valve control signal w to the solenoid valve 38 to control the solenoid valve 38. For example, when performing water purge by the water purge nozzle 36, the valve control unit 24 transmits a water valve control signal w for opening the valve to the solenoid valve 38. Upon receiving the water valve control signal w for opening the valve, the solenoid valve 38 opens the valve and supplies water from the water supply source 35 to the water purge nozzle 36.

[0038] That is, the valve control unit 24 can execute injection control for injecting air from the air purge nozzle 32 by the air purge device 30a and injection control for injecting water from the water purge nozzle 36 by the water purge device 30b in a switchable manner.

[0039] (Operation of the Embodiment) Next, with reference to FIGS. 1 to 3, the operation of the X-ray thickness gauge 1 of the embodiment will be described. FIG. 3 is a flowchart for explaining the operation of the X-ray thickness gauge according to the embodiment.

[0040] Dirt such as oil and scale that causes measurement errors on the surface of the X-ray transmission window 13 adheres during the measurement of steel materials. Therefore, in order to obtain a detection signal serving as a reference for detecting the dirt on the X-ray transmission window 13, the dose in a state where there is no object to be measured before thickness measurement is measured. The dose acquisition unit 21 acquires the X-ray dose of the X-ray generator 14 detected by the X-ray detector 12 through the X-ray transmission window 13 as a detection signal X0 (S110).

[0041] The calculation unit 22 stores the detection signal X0 acquired by the dose acquisition unit 21 in the storage unit 23 as a reference dose (detection signal) (S120).

[0042] Next, the thickness of the object to be measured 100 is measured while the object to be measured 100 moves in the T direction in the space G (while passing through the space G). The calculation unit 22 calculates the thickness of the object to be measured based on the detection signal Xd acquired by the dose acquisition unit 21 and the calibration curve stored in the storage unit 23 (S130). The calculation unit 22 stores the calculation result of the thickness in the storage unit 23 as a measurement result.

[0043] When the thickness measurement of the object to be measured is completed, the dose in the state where the object to be measured does not exist in the space G is measured. The dose acquisition unit 21 acquires, as a detection signal X1, the X-ray dose of the X-ray generator 14 detected by the X-ray detector 12 through the X-ray transmission window 13 (S140).

[0044] The calculation unit 22 reads out a reference dose (detection signal X0) from the storage unit 23 and compares it with the dose (detection signal X1) acquired in S140 (S150). When the difference between the detection signal X0 as a reference and the detection signal X1 acquired in S140 is equal to or less than a predetermined value (when the dose has not decreased by a predetermined amount) (No in S150), it is assumed that the contamination of the object to be measured is below the regulation, and the thickness measurement of the object to be measured is continued (S130).

[0045] When the difference between the reference dose (detection signal X0) and the dose (detection signal X1) acquired in S140 exceeds a predetermined value (when the dose has decreased by a predetermined amount) (Yes in S150), the valve control unit 24 transmits a water valve control signal w for opening the electromagnetic valve 38 to the electromagnetic valve 38. The electromagnetic valve 38 opens the valve in response to the water valve control signal w. The water purge nozzle 36 sprays the water sent from the water supply source 35 toward the outer surface of the X-ray transmission window 13 to perform water purge (S160). The valve control unit 24 transmits a water valve control signal w for closing the electromagnetic valve 38 to the electromagnetic valve 38 after a predetermined time has elapsed since the water injection. The electromagnetic valve 38 closes the valve in response to the water valve control signal w and stops the water supply.

[0046] When the water purge in S160 is completed, the valve control unit 24 transmits an air valve control signal a for opening the electromagnetic valve 34 to the electromagnetic valve 34. The electromagnetic valve 34 opens the valve in response to the air valve control signal a. The air purge nozzle 32 sprays the air sent from the air supply valve 31 along the outer surface of the X-ray transmission window 13 to perform air purge (S170). The valve control unit 24 transmits an air valve control signal a for closing the electromagnetic valve 34 to the electromagnetic valve 34 after a predetermined time has elapsed since the air injection. The electromagnetic valve 34 closes the valve in response to the air valve control signal a and stops the air supply.

[0047] In the above description, the air purge is performed after the water purge, but it is not limited to this. If the result of the determination by the arithmetic unit 22 in S150 shows that the decrease in dose is relatively small, the water purge may be omitted and only the air purge may be performed.

[0048] However, when performing the water purge, there is a risk that the purge water may remain on the surface of the X-ray transmission window 13, leading to measurement errors. Therefore, when performing the water purge, it is desirable to subsequently perform the air purge to remove the water remaining on the surface of the X-ray transmission window 13.

[0049] Also, in the above description, the acquisition of the detection signals X0 and X1 of the X-ray detector 12 is performed before and after the measurement of the thickness of the object to be measured, but it is not limited to this. Even during the measurement of the thickness of the object to be measured, only the air purge may be performed at regular intervals. Note that since the water purge may cause X-ray attenuation and reduce the measurement accuracy, it is desirable not to perform it during the measurement of the thickness of the object to be measured.

[0050] The X-ray thickness gauge according to the embodiment has been described as having the X-ray generator 14 housed in the lower frame 11b of the housing 11 and the X-ray transmission window 13 disposed on the upper wall surface of the lower frame 11b, but it is not limited to this. The X-ray generator 14 may be exposed from the frame 11b of the housing 11, and the X-ray transmission window 13 may be disposed on the upper wall surface of the X-ray generator 14. Even in this case, the respective arrangements and positional relationships in the relationship between the air purge nozzle 32 and the water purge nozzle 36 and the X-ray transmission window 13 are common.

[0051] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention and are also included in the invention described in the claims and its equivalent scope.

Explanation of Reference Numerals

[0052] 1…X-ray thickness gauge 11…housing, 11a…upper frame, 11b…lower frame, 11c…vertical frame 12…X-ray detector 13…X-ray transmission window 14…X-ray detector 20…control device 21…dose acquisition unit, 22…calculation unit, 23…memory unit, 24…valve control unit 30…purge device, 30a…air purge device, 30b…water purge device 31…air supply source, 32…air purge nozzle, 33…air pipe, 34…solenoid valve 35…water supply source, 36…water purge nozzle, 37…water pipe, 38…solenoid valve 100…steel material G…space X…X-ray a…air valve control signal w…water valve control signal Xg…X-ray generator control signal Xd…X-ray detection signal

Claims

Claim 1 An X-ray thickness gauge that irradiates a plate-shaped object to be measured with X-rays to measure the thickness of the object to be measured, an X-ray generation unit capable of generating the X-rays, a housing that houses the X-ray generation unit, an X-ray transmission window disposed on a wall surface of the housing and capable of transmitting the X-rays, an X-ray detection unit disposed to face an outer surface of the X-ray transmission window and capable of detecting the dose of the X-rays radiated through the X-ray transmission window, an air purge device capable of injecting gas along an outer surface of the X-ray transmission window, a liquid purge device capable of injecting liquid toward an outer surface of the X-ray transmission window, a control unit that executes at least one of injection control of the liquid toward the outer surface of the X-ray transmission window by the liquid purge device and injection control of the gas along the outer surface of the X-ray transmission window by the air purge device based on the dose of the X-rays detected by the X-ray detection unit before and after measurement of the thickness of the object to be measured, An X-ray thickness gauge comprising the above components. Claim 2 The X-ray thickness gauge according to claim 1, wherein the thickness of the object to be measured is measured while the object to be measured is passing between the outer surface of the X-ray transmission window and the X-ray detection unit. Claim 3 The X-ray thickness gauge according to claim 1, wherein the control unit executes at least one of the injection control of the liquid and the injection control of the gas based on a difference value between the dose of the X-rays detected by the X-ray detection unit before measurement of the thickness of the object to be measured and the dose of the X-rays detected by the X-ray detection unit after measurement of the thickness of the object to be measured. Claim 4 The X-ray thickness gauge according to claim 1, wherein the control unit executes the injection control of the gas after executing the injection control of the liquid. Claim 5 The X-ray thickness gauge according to claim 1, wherein the gas is air and the liquid is water.

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