Calibration jig for fiber optic radiation thermometer and calibration method for fiber optic radiation thermometer

Abstract

This invention provides a calibration jig for fiber optic radiation thermometers that enables proper calibration of fiber optic radiation thermometers using an infrared light emission device. [Solution] An infrared light emitter 21 is attached to a light emitter mounting section 3 provided at the lower end of a rectangular parallelepiped housing 2, and a detection unit 11 of a radiation thermometer is attached to a detection unit mounting section 4 provided at the opposite end, i.e., the upper end. As a result, the detection surface 14 and the infrared light emitting surface 22 of the detection unit 11 are positioned parallel to each other with a predetermined distance apart, so that the conditions for calibrating the radiation thermometer with infrared light emitted from the infrared light emitter 21 are met.

Description

Technical Field

[0001] The present invention relates to a fiber-type radiation thermometer calibration jig and a calibration method for a fiber-type radiation thermometer, particularly to a jig suitable for calibrating a fiber-type scanning radiation thermometer and its calibration method.

Background Art

[0002] In Patent Document 1 below, for example, a fiber-type radiation thermometer capable of measuring the temperature of a measurement object even in a dense production line in a steelworks is described. The fiber-type radiation thermometer described in this Patent Document 1 scans the temperature of a welded joint of a steel strip passed through a production line together with the movement of a seam welder (welding electrode wheel) to continuously or discretely measure a plurality of temperature measurement points in the scanning direction. This fiber-type scanning radiation thermometer detects (receives) infrared light radiated from the welded joint of the steel strip, which is the measurement object, by a detection unit (light receiving unit), and transmits the infrared light to a temperature conversion unit by an optical fiber group of a transmission unit for each temperature measurement point. In the temperature conversion unit, the transmitted infrared light is imaged by an imaging element, and the intensity of the infrared light at each temperature measurement point is converted into temperature to detect the temperature profile in the steel strip width direction at the welded joint. Note that a condenser lens is provided in the detection unit (detection surface) of the radiation thermometer, and the received infrared light is condensed by the condenser lens onto the optical fiber group.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] This fiber-optic scanning radiation thermometer is actually installed on the production line of a steel mill, and the transmission unit containing the fiber optic cables is intricately routed between equipment and facilities. Furthermore, each piece of equipment and device that makes up the temperature conversion unit is incorporated into control panels and operation panels, and cannot be easily removed. In addition, the detection unit itself is installed near the welding electrode ring as described in Patent Document 1 above, and cannot be approached during operation.

[0005] A radiation thermometer converts the intensity of infrared light emitted from the object being measured into temperature. This conversion formula is based on an ideal object that absorbs 100% of incoming infrared light and emits 100% of it—a perfect blackbody. In this case, the infrared emissivity of a blackbody is defined as 1.0. To ensure the reliable operation of a radiation thermometer over a long period, calibration using infrared light with an emissivity of 1.0 is necessary.

[0006] The fiber-optic scanning radiation thermometer described above allows for the removal of the detection unit when not in operation. Therefore, a (simple) infrared light emitter that emits infrared light with an emissivity of 1.0 is used to irradiate the removed detection unit with the infrared light emitted by the infrared light emitter, thereby calibrating the radiation thermometer. Considering the focusing characteristics of the focusing lens in the detection unit of the radiation thermometer, the distance between the infrared light emitting surface of the infrared light emitter and the focusing surface (focusing lens) of the detection unit must be a predetermined constant distance. Similarly, considering the diffusion of infrared light emitted from the infrared light emitting surface of the infrared light emitter, the detection surface of the radiation thermometer's detection unit and the infrared light emitting surface of the infrared light emitter must be parallel to each other. However, during actual calibration, both the removed detection unit and the infrared light emitter are held by the operator, who irradiates the detection unit with infrared light. Therefore, the distance between the infrared light emitting surface of the infrared light emitter and the focusing surface of the detection unit is not necessarily a predetermined constant distance. Similarly, the detection surface of the detection unit of a radiation thermometer and the infrared light emission surface of an infrared light emission device are not necessarily parallel to each other. In other words, when calibrating a fiber optic radiation thermometer using an infrared light emission device, a calibration jig that can properly calibrate the radiation thermometer is desired.

[0007] The present invention has been made in view of the above problems, and its purpose is to provide a fiber optic radiation thermometer calibration jig that can properly calibrate a fiber optic radiation thermometer using an infrared light emission device. [Means for solving the problem]

[0008] To achieve the above objective, a fiber optic radiation thermometer calibration jig according to one aspect of the present invention is a calibration jig for a fiber optic radiation thermometer that measures the temperature of an object by transmitting infrared light from an object to be measured detected by a detection unit to a temperature conversion unit via a group of optical fibers in a transmission unit, wherein a light-emitting device mounting portion is provided at one end of the main body, which is made of a rectangular parallelepiped, to which the infrared light-emitting device is mounted in a position where the infrared light-emitting surface of the infrared light-emitting device faces inward, and a detection unit mounting portion is provided at the end opposite to the end thereof, to which the detection unit is mounted in a position where the detection surface of the detection unit faces inward, and the detection unit is mounted at the detection unit mounting portion and the infrared light-emitting device is mounted at the light-emitting device mounting portion, wherein the detection surface of the detection unit and the infrared light-emitting surface are parallel to each other and the distance between the detection surface and the infrared light-emitting surface is a predetermined distance.

[0009] Furthermore, a further aspect of the present invention is characterized in that, with the infrared light emitting device attached to the light emitting device mounting portion and the detection unit attached to the detection unit mounting portion, the inside of the main body portion is made into a light-shielding space. Furthermore, a further aspect of the present invention is characterized in that the inside of the main body is painted black. Furthermore, the calibration method for the fiber-optic radiation thermometer of the present invention essentially involves calibrating the fiber-optic radiation thermometer using the fiber-optic radiation thermometer calibration jig described above. [Effects of the Invention]

[0010] In this invention, an infrared light emitter is attached to a light emitter mounting section provided at one end of the main body of a calibration jig consisting of a rectangular parallelepiped housing, and the detection section of a radiation thermometer is attached to a detection section mounting section provided at the opposite end. As a result, the detection surface and the infrared light emitter are positioned parallel to each other with a predetermined distance apart, thus satisfying the conditions for calibrating the radiation thermometer with infrared light emitted from the infrared light emitter. Therefore, by using the calibration jig of this invention, a fiber optic radiation thermometer can be properly calibrated using an infrared light emitter. [Brief explanation of the drawing]

[0011] [Figure 1] This is a front cross-sectional view showing one embodiment of the fiber-optic radiation thermometer calibration jig of the present invention in use. [Figure 2] This is a conceptual diagram illustrating the signs of deterioration in a radiation thermometer (temperature sensing element). [Modes for carrying out the invention]

[0012] The following describes in detail an embodiment of a fiber optic radiation thermometer calibration jig with reference to the drawings. The embodiments shown below are illustrative of devices and methods for realizing the technical concept of the present invention, and the technical concept of the present invention is not limited to the embodiments described below.

[0013] Figure 1 is a front cross-sectional view showing one embodiment of a fiber optic radiation thermometer calibration jig in use. The fiber optic radiation thermometer whose temperature measurement calibration is performed using this calibration jig 1 is a fiber optic scanning radiation thermometer described in Patent Document 1, which detects the temperature profile of the welded joint of steel strips passed through a continuous annealing line in a steel mill. Therefore, as described in Patent Document 1, a detection unit (light receiving unit) 11 for detecting (receiving) infrared light emitted from the welded joint is mounted near the electrode ring of the seam welding machine so as to be mounted in a predetermined position facing the welded joint. As mentioned above, it is not possible to approach the detection unit 11 during operation, but the detection unit 11 can be removed from the device (equipment) when not in operation. The fiber optic radiation thermometer is calibrated by irradiating the removed detection unit 11 with infrared light of a predetermined intensity emitted from an infrared light emitting device 21.

[0014] Details are left to Patent Document 1 mentioned above, but the detection unit 11 and a temperature conversion unit (not shown) are connected by a cable 12 that constitutes a transmission unit, and a group of optical fibers is housed in this cable 12. The group of optical fibers is arranged in the cable 12 so that infrared light emitted from the welded joint of the steel strip can be transmitted to each pixel of the image sensor for each of the multiple temperature measurement points. The detection unit 11 has the cable 12 connected to one end of a cylindrical housing 13 made of a cylindrical body, and the opposite end (end face) is a detection surface (light-receiving surface) 14 that receives infrared light. This detection unit 11 is configured to have a focusing lens at least on the detection surface 14 so that the infrared light from the welded joint detected on the detection surface 14 is properly received by the group of optical fibers. A circular flange portion 15 that extends radially outward is provided at the longitudinal center of the outer circumference of the cylindrical housing 13, and is attached near the electrode ring via this flange portion 15. On the other hand, in order to calibrate the radiation thermometer by having the detection unit 11 receive infrared light of a predetermined intensity, this embodiment uses a (simplified) infrared light emitting device 21. The entire infrared light emitting device 21 is configured in a rectangular parallelepiped shape and is equipped with an infrared LED (light-emitting diode) (not shown) inside, which emits infrared light with an emissivity of 1.0 at a predetermined intensity from the infrared light emitting surface 22. The outer circumference of the infrared light emitting surface 22 is circular with a predetermined diameter when viewed from above. In this infrared light emitting device 21, it is possible to separate the power supply unit from the infrared light emitting unit, but in this embodiment, the power supply unit is used in an integrated state with the infrared light emitting unit.

[0015] Figure 2 is a conceptual diagram for diagnosing signs of deterioration in temperature-sensing elements such as radiation thermometers. For example, temperature-sensing elements such as radiation thermometers also deteriorate over time. When infrared light of a predetermined intensity is irradiated onto the detection unit 11 of a radiation thermometer, and the measured temperature is detected at predetermined intervals and displayed in a time series, a trend such as a gradual decrease in the measured temperature is observed, as shown in Figure 2. For example, if the control range for the measured temperature is the range between the two dashed lines in Figure 2, the trend in the time series of the measured temperature can predict that the measured temperature will exceed the control range at the next measurement. If a logic can be constructed to diagnose signs of deterioration in the temperature-sensing element from this trend in the measured temperature at the next measurement, the control range can be maintained by replacing or repairing the temperature-sensing element before the measured temperature exceeds the control range. Therefore, by using this logic, it is possible to ensure the quality of products such as steel plates. However, in order to do so, it is necessary to properly detect the temperature measurement characteristics of the radiation thermometer. In order to properly detect the temperature measurement characteristics of the radiation thermometer using the infrared light emission device 21, at least two measurement conditions are necessary, as described above. One requirement is that the distance between the detection surface 14 of the detection unit 11 and the infrared light emitting surface 22 is a predetermined distance, and the other is that the detection surface 14 and the infrared light emitting surface 22 are parallel.

[0016] The calibration jig 1 shown in Figure 1 is composed of a rectangular parallelepiped housing 2, which forms the main body. The four sides 5 in the front cross-sectional view of Figure 1 are closed with plate members. A light-emitting device mounting portion 3 is provided at the lower end (lower end face) of the rectangular parallelepiped housing 2, and a detection unit mounting portion 4 is provided at the opposite end, i.e., the upper end (upper end face) shown. A bottom plate portion 6 is attached to the lower end face of the rectangular parallelepiped housing 2, and an infrared light emitting device 21 is mounted in a rectangular recess 6a formed in this bottom plate portion 6. Furthermore, the infrared light emitting surface portion 22 is tightly inserted into a circular hole 6b formed in the bottom plate portion 6 within this recess 6a. In addition, a top plate portion 7 is attached to the upper end face of the housing 2, and the flange portion 15 of the detection unit 11 is inserted and mounted into a circular recess 7a formed in this top plate portion 7. Furthermore, the cylindrical housing 13 of the detection unit 11 is configured to be tightly inserted into the circular hole 7b formed in the center.

[0017] Therefore, when the detection unit 11 is attached to the detection unit mounting section 4 provided on the housing 2 of the calibration jig 1, and the infrared light emitter 21 is attached to the light emitter mounting section 3, the detection surface (focusing lens) 14 of the detection unit 11 and the infrared light emitter 22 are arranged parallel to each other. At the same time, the distance between the detection surface 14 of the detection unit 11 and the infrared light emitter 22 of the infrared light emitter 21 is set to a predetermined distance. Furthermore, the centers of the detection surface 14 of the detection unit 11 and the centers of the infrared light emitter 22 of the infrared light emitter 21 are positioned to face each other. As a result, it is possible to properly input the infrared light emitted from the infrared light emitter 21 to the detection unit 11 and properly calibrate the radiation thermometer. Furthermore, when the detection unit 11 is attached to the detection unit mounting section 4 of the calibration jig 1 and the infrared light emitter 21 is attached to the light emitter mounting section 3, the inside of the housing 2 of the calibration jig 1 becomes a light-shielding space (darkroom), and no light enters from the outside. This eliminates the influence of external light and allows for even more accurate calibration of the radiation thermometer. In addition, the inside of the housing 2 of the calibration jig 1 is painted black, which suppresses the reflection of infrared light emitted from the infrared light emitter 21 within the housing 2. This also enables even more accurate calibration of the radiation thermometer.

[0018] As described above, the fiber optic radiation thermometer calibration jig according to the embodiment has been described. However, the present invention is not limited to the configuration described in the above embodiment, and various modifications are possible within the scope of the gist of the present invention. For example, as described above, when the power supply unit in the infrared light emitting device 21 is separately arranged from the infrared light emitting unit, it is desired to be read as the infrared light emitting unit (a part of the infrared light emitting device 21) attached to the lower end portion of the housing 2, that is, one end portion.

[0019] Thus, in this embodiment, the infrared light emitting device 21 is attached to the light emitting device attachment portion 3 provided at the lower end portion of the housing 2, and the detection portion 11 of the radiation thermometer is attached to the detection portion attachment portion 4 provided at the opposite end portion, that is, the upper end portion. Thereby, since the detection surface 14 and the infrared light emitting surface portion 22 are arranged in parallel with a predetermined distance separating the detection surface 14 and the infrared light emitting surface portion 22, the conditions for calibrating the radiation thermometer with the infrared light emitted from the infrared light emitting device 21 are satisfied. Therefore, by using the calibration jig 1 of the present invention, the fiber optic radiation thermometer can be properly calibrated using the infrared light emitting device 21.

[0020] [[ID= 9]] Also, in a state where the detection portion 11 is attached to the detection portion attachment portion 4 of the housing 2 and the infrared light emitting device 21 is attached to the light emitting device attachment portion 3, the inside of the housing 2 which is the main body portion becomes a light shielding space, and light does not enter from the outside. Thereby, the influence of external light can be excluded and the radiation thermometer can be calibrated more properly. Further, by painting the inside of the housing 2 black, the reflection of the infrared light emitted from the infrared light emitting device 21 inside the housing 2 is suppressed, and further proper calibration of the radiation thermometer becomes possible.

Explanation of Reference Numerals

[0021] 1 Calibration jig 2 Housing (main body portion) 3 Light emitting device attachment portion 4 Detection portion attachment portion 11 Detection portion 14 Detection surface 21 Infrared light emission device 22 Infrared light emitting surface

Claims

1. A calibration jig for a fiber optic radiation thermometer that measures the temperature of an object by transmitting infrared light from the object to be measured, detected by the detection unit, to the temperature conversion unit via a group of optical fibers in the transmission unit, A mounting portion for an infrared light emitter is provided at one end of the main body, which is made up of a rectangular parallelepiped, so that the infrared light emitting surface of the infrared light emitter faces inward, and a mounting portion for a detection unit is provided at the end opposite to that end, so that the detection unit is mounted so that the detection surface of the detection unit faces inward. A fiber optic radiation thermometer calibration jig characterized in that, with the detection unit mounted on the detection unit mounting portion and the infrared light emitting device mounted on the light emitting device mounting portion, the detection surface of the detection unit and the infrared light emitting surface portion are parallel to each other, and the distance between the detection surface and the infrared light emitting surface portion is a predetermined distance.

2. The fiber optic radiation thermometer calibration jig according to claim 1, characterized in that the interior of the main body is a light-shielding space when the infrared light emitting device is attached to the light emitting device mounting portion and the detection unit is attached to the detection unit mounting portion.

3. The fiber-optic radiation thermometer calibration jig according to claim 2, characterized in that the inside of the main body is painted black.

4. A method for calibrating a fiber optic radiation thermometer using the fiber optic radiation thermometer calibration jig described in any one of claims 1 to 3.

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