Temperature measuring device, sheet metal speed control device, temperature measuring method, and sheet metal speed control method

Abstract

To measure the temperature of a test specimen with greater accuracy.SOLUTION: A temperature measuring device according to the present invention comprises: a first housing; a detection unit provided to the inside of the first housing, which detects spontaneous emission from a test specimen and outputs an electric signal that corresponds to the intensity of the spontaneous emission; a multipath reflection mirror provided in an optical path between the test specimen inside of the first housing and the detection unit, which is composed of curved mirrors that cause the spontaneous emission to be reflected in multiple paths and formed into an image in the detection unit; a second housing which is provided in the inside of the detection unit; an optical filter provided in the inside of the second housing, which passes light of a wavelength band through that is free of absorption by disturbances present in the surroundings of the test specimen; a cooling mechanism provided in the second housing, which cools the optical filter; and a temperature calculation unit that calculates the temperature of the test specimen on the basis of the electric signal outputted from the detection unit. The detection unit detects the spontaneous emission from the test specimen via the optical filter that is cooled by the cooling mechanism, and the temperature calculation unit calculates the temperature of the test specimen on the basis of the electric signal outputted from the detection unit.SELECTED DRAWING: Figure 13

Description

[Technical Field]

[0001] The present invention relates to a temperature measuring device, a sheet metal speed control device, a temperature measuring method, and a sheet metal speed control method. [Background technology]

[0002] Cold-rolled steel sheets are manufactured by cold-rolling a thick plate, which is the material to be rolled, using a cold tandem rolling mill that has multiple cold-rolling stands arranged in a continuous line, and rolling the plate to a predetermined thickness. This cold-rolling process is carried out smoothly by the presence of an oil film formed by the rolling oil supplied as a lubricant between the work rolls and the material to be rolled.

[0003] Such cold-rolled steel sheets may develop surface defects called heat scratches as the rolling speed (which can also be considered as the speed at which the rolled material passes through) and the reduction amount in the cold rolling stand increase. These heat scratches occur when rolling at high speed or high pressure causes the temperature of the interface between the rolled material and the work rolls to rise, particularly within the roll bite (the section where the rolled material is held between the work rolls), which destroys the oil film and causes the rolled material to come into metal-to-metal contact with the work rolls.

[0004] When heat scratches occur, it becomes difficult to commercialize the affected portion of the cold-rolled steel sheet being manufactured. Furthermore, if scratches occur on the surface of the work roll, these scratches will be transferred to subsequent cold-rolled steel sheets, significantly impacting the manufacturing cost of the cold-rolled steel sheets. Therefore, cold rolling under conditions that prevent heat scratches is crucial.

[0005] Conventionally, various technologies have been proposed to perform cold rolling while preventing the occurrence of heat scratches. For example, Patent Document 1 below proposes a technique for a cold tandem rolling mill in which the crack length at the plate-side edge of the steel plate is detected at least at the entry side of the final rolling stand, the tension of the rolling stand is controlled based on the detected crack length, and a non-contact plate thermometer is installed at the exit side of the rolling stand to measure the plate temperature, and the rolling speed is controlled from the obtained measurement results so that it is below the temperature at which heat scratches occur.

[0006] Furthermore, Patent Document 2 below proposes a technique for predicting the temperature of the rolled material at each stand using a draft schedule that defines the reduction load, roll gap, and rolling speed at each stand before starting cold rolling using a cold tandem rolling mill, and a temperature change calculation formula for predicting the temperature change of the rolled material in cold tandem rolling. Based on this predicted temperature, the rolling speed during cold rolling is then controlled.

[0007] In actual cold rolling, techniques such as those described above are used to measure or predict the actual temperature of the material being rolled, and cold-rolled steel sheets are manufactured under rolling conditions that ensure sufficient safety and eliminate the risk of heat scratches. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 9-239405 [Patent Document 2] Japanese Patent Publication No. 2009-106975 [Overview of the project] [Problems that the invention aims to solve]

[0009] In cold rolling lines, including cold tandem rolling mills as described above, it is common practice to roll materials that are at a temperature of around 100-200°C while cooling them with cooling water. As a result, a large amount of disturbance, such as steam, is present around the cold rolling line. Therefore, even if the temperature of the rolled material is measured using a non-contact plate thermometer, as proposed in Patent Document 1, measurement errors caused by such disturbances must be taken into account. Consequently, it becomes necessary to ensure a sufficient safety margin, which necessitates operating at a reduced rolling speed.

[0010] Furthermore, when estimating the temperature of the rolled material based on a temperature change calculation formula, as in the technology proposed in Patent Document 2, there is a possibility of discrepancies between the estimated temperature and the actual temperature. Therefore, similar to the technology disclosed in Patent Document 1, it becomes necessary to ensure a sufficient safety margin, which necessitates operating at a reduced rolling speed.

[0011] As described above, in a cold rolling line operating under the presence of external disturbances, there is room for further improvement in temperature measurement of the rolled material. If the accuracy of temperature measurement of the rolled material can be improved, it is expected that the rolling speed can be further increased, thereby improving the productivity of cold-rolled steel sheets.

[0012] Therefore, the present invention has been made in view of the above circumstances, and the object of the present invention is to provide a temperature measuring device and a temperature measuring method that can measure the temperature of an object to be measured with greater accuracy, and a sheet speed control device and a sheet speed control method that can control the sheet speed of a rolled material in a cold rolling line with greater precision. [Means for solving the problem]

[0013] To solve the above problems, according to one aspect of the present invention, a temperature measuring device is provided for measuring the temperature of an object to be measured by detecting self-illumination radiated from the object to be measured, comprising: a first housing; a detection unit provided inside the first housing which detects the self-illumination and outputs an electrical signal corresponding to the intensity of the self-illumination; a multiple reflection mirror made of a curved mirror provided on the optical path between the object to be measured and the detection unit inside the first housing which multiple reflections the self-illumination and images it toward the detection unit; a second housing provided inside the detection unit; an optical filter provided inside the second housing which transmits light in a wavelength band that is not absorbed by disturbances present around the object to be measured; a cooling mechanism provided in the second housing for cooling the optical filter; and a temperature calculation unit which calculates the temperature of the object to be measured based on the electrical signal output from the detection unit, wherein the detection unit detects the self-illumination radiated from the object to be measured via the optical filter cooled by the cooling mechanism, and the temperature calculation unit calculates the temperature of the object to be measured based on the electrical signal output from the detection unit.

[0014] To solve the above problems, according to another aspect of the present invention, a sheet passing speed control device that measures the temperature of a sheet to be measured by detecting self-illumination radiated from the sheet to be measured as it passes through a cold rolling line composed of a plurality of cold rolling stands, and controls the sheet passing speed of the cold rolling line according to the temperature, comprising: a first housing; a detection unit provided inside the first housing which detects the self-illumination and outputs an electrical signal corresponding to the intensity of the self-illumination; a multiple reflection mirror made of a curved mirror provided on the optical path between the sheet to be measured and the detection unit inside the first housing which multiple-reflects the self-illumination and forms an image of it to the detection unit; a second housing provided inside the detection unit; and an optical filter provided inside the second housing which transmits light in a wavelength band that is not absorbed by disturbances present around the sheet to be measured. A temperature measuring device is provided, which includes a cooling mechanism for cooling the optical filter provided in two housings, a temperature calculation unit that calculates the temperature of the object to be measured based on the electrical signal output from the detection unit, and a sheet speed control unit that controls the sheet speed of the cold rolling line, wherein the temperature measuring device is provided between adjacent cold rolling stands, the detection unit detects the self-illuminating light radiated from the object to be measured via the optical filter cooled by the cooling mechanism, the temperature calculation unit calculates the temperature of the object to be measured based on the electrical signal output from the detection unit, and the sheet speed control unit controls the sheet speed of the cold rolling line so that the temperature calculated by the detection unit is below a predetermined threshold temperature, using a relationship between the temperature of the rolled material and the sheet speed determined in advance.

[0015] To solve the above problems, according to yet another aspect of the present invention, a temperature measurement method for measuring the temperature of an object to be measured by detecting self-illumination radiated from the object to be measured, comprising: a first housing; a detection unit provided inside the first housing and which detects the self-illumination and outputs an electrical signal corresponding to the intensity of the self-illumination; a multiple reflection mirror made of a curved mirror provided on the optical path between the object to be measured and the detection unit inside the first housing and which causes the self-illumination to undergo multiple reflections and form an image on the detection unit; a second housing provided inside the detection unit; and a front A temperature measurement method is provided, using a temperature measuring device having an optical filter that transmits light in a wavelength band that is not absorbed by disturbances present around the object to be measured, a cooling mechanism provided in the second housing for cooling the optical filter, and a temperature calculation unit that calculates the temperature of the object to be measured based on the electrical signal output from the detection unit, wherein the detection unit is used to detect the self-illuminating light radiated from the object to be measured through the optical filter cooled by the cooling mechanism, and the temperature calculation unit calculates the temperature of the object to be measured based on the electrical signal output from the detection unit.

[0016] In order to solve the above problems, according to another aspect of the present invention, there is provided a sheet passing speed control method for measuring the temperature of a measurement object by detecting spontaneous light radiated from the measurement object passing through a cold rolling line composed of a plurality of cold rolling stands, and controlling the sheet passing speed of the cold rolling line according to the temperature, comprising: a first housing; a detection unit provided inside the first housing for detecting the spontaneous light and outputting an electrical signal corresponding to the intensity of the spontaneous light; a multiple reflection mirror composed of a curved mirror provided on the optical path between the measurement object and the detection unit inside the first housing for multiple-reflecting the spontaneous light and forming an image on the detection unit; a second housing provided inside the detection unit; an optical filter provided inside the second housing for transmitting light in a wavelength band without absorption due to disturbances existing around the measurement object; a cooling mechanism for cooling the optical filter provided on the second housing; a temperature calculation unit for calculating the temperature of the measurement object based on the electrical signal output from the detection unit; a temperature measurement device having these components; and a sheet passing speed control device having a sheet passing speed control unit for controlling the sheet passing speed of the cold rolling line. The temperature measurement device is provided between adjacent cold rolling stands, and the detection unit is used to detect the spontaneous light radiated from the measurement object through the optical filter cooled by the cooling mechanism. The temperature calculation unit calculates the temperature of the measurement object based on the electrical signal output from the detection unit, and the sheet passing speed control unit is used to control the sheet passing speed of the cold rolling line so that the temperature calculated by the detection unit is below a predetermined threshold temperature using the previously obtained relationship between the temperature of the rolled material and the sheet passing speed.

Advantages of the Invention

[0017] As described above, according to the present invention, it is possible to provide a temperature measurement device and a temperature measurement method capable of more accurately measuring the temperature of a measurement object, and a sheet passing speed control device and a sheet passing speed control method capable of more precisely controlling the sheet passing speed of a rolled material in a cold rolling line.

Brief Description of the Drawings

[0018] [Figure 1]This graph illustrates the infrared wavelength band of focus in the temperature measuring device according to an embodiment of the present invention. [Figure 2] This is an explanatory diagram illustrating internal stray light caused by optical filters. [Figure 3] This is an explanatory diagram illustrating internal stray light caused by optical filters. [Figure 4A] This is a schematic diagram illustrating an example of the configuration of a photodetector used in the temperature measuring device according to the same embodiment. [Figure 4B] This is a schematic diagram illustrating another example of the configuration of a photodetector used in the temperature measuring device according to the same embodiment. [Figure 5] This is an explanatory diagram showing an example of a two-dimensional luminance image generated by the photodetector according to the same embodiment. [Figure 6] This is an explanatory diagram illustrating a photodetector used in a temperature measuring device according to the same embodiment. [Figure 7] This is an explanatory diagram showing an example of a two-dimensional luminance image generated by the photodetector according to the same embodiment. [Figure 8] This is an explanatory diagram for describing the simulation conditions related to multiple reflection mirrors. [Figure 9] This graph shows the relationship between the radius of curvature R of a multiple reflection mirror and the amplification factor α of the radiated energy. [Figure 10] This graph shows the relationship between the radius of curvature R of the multiple reflection mirror and the installation height d of the mirror, and the amplification factor α of the radiated energy. [Figure 11] This graph shows the relationship between aperture diameter L and effective emissivity εm. [Figure 12] This graph shows the relationship between the diameter 2r of a multiple reflection mirror and its effective emissivity εm. [Figure 13] This is a schematic diagram showing an example of the configuration of the detection device in the temperature measuring device according to the same embodiment. [Figure 14] This is a schematic diagram showing an example of the configuration of the processing unit in the temperature measuring device according to the same embodiment. [Figure 15]This is a block diagram showing an example of the configuration of the arithmetic processing unit in the arithmetic processing unit of the temperature measuring device according to the same embodiment. [Figure 16] This is an example of a temperature calibration graph showing the relationship between output voltage and temperature. [Figure 17] This is a schematic diagram illustrating the mechanism of an electronically cooled detector. [Figure 18] This graph shows the relationship between the cooling voltage applied to the photodetector and the output voltage ratio from the photodetector. [Figure 19] This flowchart shows an example of the flow of the temperature measurement method in the temperature measuring device according to the present embodiment. [Figure 20A] This graph shows the temperature measurement results of cold-rolled steel sheets being transported along the cold-rolling line during the cold-rolling process. [Figure 20B] This graph shows the temperature measurement results of cold-rolled steel sheets being transported along the cold-rolling line during the cold-rolling process. [Figure 21] This is an explanatory diagram illustrating sheet metal speed control in the cold rolling process. [Figure 22] This is a block diagram showing an example of the configuration of a plate speed control device according to the same embodiment. [Figure 23] This is a block diagram showing an example of the hardware configuration of the arithmetic processing unit according to the same embodiment. [Modes for carrying out the invention]

[0019] Preferred embodiments of the present invention will be described in detail below with reference to the attached drawings. In this specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant descriptions will be omitted.

[0020] (The infrared wavelength range that temperature measuring devices focus on) The temperature measuring device focused on in the embodiment of the present invention is a device that measures the temperature of an object to be measured by detecting self-luminescence (more specifically, self-luminescence whose wavelength belongs to the infrared wavelength band) radiated from the object to be measured.

[0021] Here, it is assumed that disturbances exist around the object under consideration in this embodiment, such as scatterers that scatter the self-luminescence radiated from the object under consideration (for example, so-called fumes such as steam (water droplets) or oil droplets) and absorbers that absorb the self-luminescence radiated from the object under consideration (for example, water or rolling oil used in the rolling process in the steel industry).

[0022] The temperature measuring device described in detail below, which is the focus of this embodiment, can be used even in environments where such disturbances exist. Examples of environments where such disturbances exist include cold rolling processes in the steel industry, sintering ore manufacturing processes in the steel industry, various processes in the paper industry, and various chemical processes in the chemical industry.

[0023] In the following explanation, we will use the cold rolling process in the steel industry as an example. In this cold rolling process, a steel sheet at a temperature between 100°C and 200°C is rolled as it passes through a cold rolling line to produce a cold-rolled steel sheet.

[0024] As described above, the temperature measuring device focused on in this embodiment detects self-luminescence from the object to be measured whose wavelength belongs to the infrared wavelength band, and measures the temperature of the object based on the detection result of this self-luminescence. In this case, since disturbances such as those described above exist around the temperature measuring device, it is preferable that the wavelength used when detecting self-luminescence with the temperature measuring device is a wavelength that is not affected by the disturbances.

[0025] In the cold rolling process in the steel industry, disturbances that should be considered include absorbers that absorb self-luminescence, such as water and rolling oil, which may be present on the surface of the steel sheet (cold-rolled steel sheet) being rolled. Figure 1 is a graph illustrating the infrared wavelength band that the temperature measuring device according to this embodiment focuses on. The upper part of Figure 1 shows the spectrum of the transmission characteristics of a typical rolling oil used in the cold rolling process, and the lower part of Figure 1 shows the spectrum of the transmission characteristics of water. In both spectra of Figure 1, the vertical axis represents transmittance and the horizontal axis represents wavelength.

[0026] Referring to the spectra in Figure 1, it can be seen that there are infrared wavelength bands with extremely low absorption by absorbers, such as the infrared wavelength band with a central wavelength of 2.0 μm and the infrared wavelength band with a central wavelength of 4.0 μm. Comparing the infrared wavelength band with a central wavelength of 2.0 μm and the infrared wavelength band with a central wavelength of 4.0 μm, when focusing on a subject to be measured at low temperatures between 100°C and 200°C, the thermal radiation is greater in the infrared wavelength band with a central wavelength of 4.0 μm. Therefore, considering this difference in thermal radiation, it can be said that it is more preferable for temperature measurement devices to focus on the infrared wavelength band with a central wavelength of 4.0 μm. Furthermore, since the infrared wavelength band with a central wavelength of 4.0 μm has a longer wavelength compared to the infrared wavelength band with a central wavelength of 2.0 μm, it is less affected by scattering materials that scatter self-luminescence such as steam, and can be said to be a wavelength band that is unaffected by external disturbances.

[0027] (Consideration of photodetectors) <Regarding the items under consideration> Based on the above-mentioned findings regarding noteworthy infrared wavelength bands, the inventors attempted to image a blackbody furnace using an infrared camera as shown in Figure 2, an example of a photodetector, ensuring that blackbody furnaces set to temperatures of 100°C and 200°C were included within the same field of view. Figure 2 is an explanatory diagram for explaining internal stray light caused by the optical filter, and schematically shows the configuration of the infrared camera used for the above-mentioned imaging. The infrared camera used in this verification employs a two-dimensional detection element capable of detecting the distribution of light intensity (luminance) in two dimensions (vertical × horizontal). By using such an infrared camera, it is possible to visualize the distribution of light intensity in two dimensions and generate a two-dimensional luminance image. As schematically shown in Figure 2, this infrared camera has a two-dimensional detection element for infrared light detection (for example, InSb, PbSe, PbS, InGaAs, HgCdTe (commonly known as MCT), QWIP (Quantum Well Infrared Photodetector), etc.) housed in a casing with a lens. Based on the above findings, an optical filter that transmits light with a central wavelength of 4.0 μm was installed in the optical path before the two-dimensional detection element.

[0028] The obtained two-dimensional luminance image is shown in Figure 3. Figure 3 is an explanatory diagram to illustrate the internal stray light caused by the optical filter, and shows an example of a two-dimensional luminance image obtained with the infrared camera described above.

[0029] As is clear from Figure 3, the obtained two-dimensional luminance image contains not only two regions corresponding to thermal radiation from the blackbody furnace (the white regions near the right and left edges in Figure 3), but also internal stray light from the infrared camera, located approximately in the center. As a result, the luminance values ​​of the regions corresponding to thermal radiation from the blackbody furnace are superimposed with luminance values ​​originating from this internal stray light as background luminance. The distribution shape of the internal stray light seen in Figure 3 closely matches the shape of the optical filter, suggesting that it is due to thermal radiation from the optical filter itself (thermal radiation caused by the optical filter being heated by thermal radiation from the blackbody furnace).

[0030] More specifically, in the two-dimensional luminance image shown in Figure 3, the luminance value of the region corresponding to the 200°C blackbody furnace was 7683, the luminance value of the region corresponding to the 100°C blackbody furnace was 7008, while the luminance value of the internal stray light in the center of the image was 6925. In other words, the luminance difference between the luminance value of the region corresponding to the 100°C blackbody furnace and the luminance value of the internal stray light is (7008-6925) / 6925 ≈ 1% of the luminance value of the internal stray light.

[0031] Normally, internal stray light caused by thermal radiation inside an infrared camera can be offset by subtracting the brightness value of an image captured with a cover in front of the lens as the background brightness value. However, as shown in Figure 3, when imaging an object under measurement at low temperatures such as 100°C to 200°C with an infrared camera with a narrowed wavelength band of interest, the ratio of the brightness value of interest to the brightness value of internal stray light is only 1%, as described above. Based on this verification, the inventors concluded that if an optical filter to limit the wavelength band to which the 2D detection element is imaged is placed immediately next to the 2D detection element, the effect of internal stray light becomes extremely large, making imaging with an infrared camera in a wavelength-limited state difficult.

[0032] <About photodetectors> Based on the above findings, the inventors diligently studied methods for suppressing the internal stray light described above and arrived at the photodetector 110, as shown in Figure 4A, which is applicable to the temperature measuring device according to this embodiment. Hereinafter, an example of a photodetector used in the temperature measuring device according to this embodiment will be described in detail with reference to Figure 4A. Figure 4A is a schematic explanatory diagram showing an example of the configuration of a photodetector used in the temperature measuring device according to this embodiment.

[0033] The photodetector 110 used in the temperature measuring device according to this embodiment mainly comprises, as schematically shown in Figure 4A, a detection unit 115 in which a detection unit 111 for detecting infrared light is provided inside a housing 113, an optical filter 121, an optical filter housing 123 (second housing described later) which is mounted on the infrared camera 115 via a lens and houses the optical filter 121, and a cooling mechanism 131 provided in the optical filter housing 123.

[0034] The infrared light detection unit 111 has a detection element that functions as a conversion element that converts the intensity of infrared light imaged on the detection unit 111 into the intensity of an electrical signal. The detection element can output an electrical signal corresponding to the intensity of the detected infrared light. Such a detection element is not particularly limited, and known detection elements for infrared light detection such as InSb, PbSe, PbS, InGaAs, HgCdTe, QWIP, etc. can be used. The detailed configuration of the detection unit 111 having such a detection element will be described again below.

[0035] Furthermore, the material of the housing 113 is not particularly limited; any known material that prevents infrared light present in the outside from penetrating into the inside of the housing may be used.

[0036] In the photodetector 110 according to this embodiment, based on the findings described with reference to Figures 2 and 3, the optical filter 121, which can cause internal stray light, is placed inside the optical filter housing 123 so as to be separated from the detection unit 111, which can be a cause of temperature changes.

[0037] The optical filter 121 is positioned in the optical path between the object to be measured and the detection unit 115 (more specifically, the detection unit 111), and transmits self-luminescence emitted from the object to be measured in a wavelength band that is not absorbed by disturbances present around the object to be measured. In this embodiment, the optical filter 121 is preferably an optical filter 121 that transmits self-luminescence in the infrared wavelength band with a central wavelength of 4.0 μm, based on the findings described in more detail with reference to Figure 1. This optical filter 121 is housed inside the optical filter housing 123 and isolated from the outside world. Furthermore, as shown in Figure 4A, the optical filter 121 is preferably positioned inside the optical filter housing 123 so as to be tilted at a predetermined angle with respect to the optical axis of the detection unit 115 (for example, at approximately 45 degrees with respect to the optical axis). The transmission bandwidth of the optical filter 121 is not particularly limited and can be appropriately determined according to the required measurement accuracy and the detection resolution of the detection element, but for example, it can be about 200 nm.

[0038] The optical filter housing 123 corresponds to the second housing described later and is provided to separate the optical filter 121 from the outside world. Preferably, the optical filter housing 123 is made of a material with excellent thermal conductivity (for example, various metal materials including alloys of iron, aluminum, copper, and stainless steel).

[0039] As shown in Figure 4A, the optical filter housing 123 is equipped with a cooling mechanism 131, which cools the optical filter housing 123. When the cooling mechanism 131 is activated during detection, the optical filter housing 123 itself is cooled, and as the optical filter housing 123 cools, the gas present in the internal space of the optical filter housing 123 is also cooled. As a result, heating of the optical filter 121 is suppressed, and it is possible to reduce internal stray light caused by thermal radiation from the optical filter 121. Furthermore, by installing the optical filter 121 at an angle as shown in Figure 4A, and so that thermal radiation from the cooled internal space of the optical filter housing 123 is imaged onto the detection unit 111, it is possible to further improve the signal-to-noise ratio of the detection unit 111.

[0040] Such a cooling mechanism 131 is not particularly limited, and known cooling mechanisms can be used. For example, a simple cooling mechanism 131 can be made by using a combination of a Peltier element 133 and a heat sink 135.

[0041] The extent to which the cooling mechanism 131 cools the optical filter housing 123 should be appropriately set according to the detection sensitivity of the detection element used, the required measurement accuracy, the environment in which the photodetector 110 is installed, and the performance of the cooling mechanism 131 used. By using a typical Peltier element 133 and heat sink 135 to cool the metal optical filter housing 123, it is possible to cool the walls of the optical filter housing 123 to, for example, about 15°C.

[0042] Furthermore, while Figure 4A illustrates a case where the optical filter housing 123 containing the optical filter 121 is provided outside the detection unit 115, it is also possible to use a photodetector 110 as shown in Figure 4B. Figure 4B is a schematic explanatory diagram showing another example of the configuration of a photodetector used in the temperature measuring device according to this embodiment.

[0043] In the photodetector 110 shown in Figure 4B, the optical filter housing 123, which houses the optical filter 121, is located inside the housing 113 of the detection unit 115. In this case, it is preferable to design the heat dissipation mechanism, such as the heat sink 135, to be located outside the infrared camera housing 113 in order to prevent the heat generated by the operation of the cooling mechanism 131 from reaching the detection unit 111.

[0044] In this embodiment, the photodetector 110 may use either a two-dimensional detection element capable of two-dimensional processing as the detection element provided in the detection unit 111, or a one-dimensional detection element that detects only the intensity of the imaged light may be used.

[0045] Figure 5 shows a two-dimensional luminance image obtained by imaging blackbody furnaces set to 100°C and 200°C in the same manner as in Figure 2, while cooling the optical filter housing 123 (i.e., optical filter 121) using the photodetector 110 shown in Figure 4A. As is clear from Figure 5, the obtained two-dimensional luminance image contains only regions with high luminance values ​​originating from the two blackbody furnaces, indicating that internal stray light caused by thermal radiation from other components is extremely suppressed. Furthermore, it can be seen that the region corresponding to the 200°C blackbody furnace is whiter (i.e., has higher luminance) than the region corresponding to the 100°C blackbody furnace.

[0046] More specifically, in the two-dimensional luminance image shown in Figure 5, the luminance value of the region corresponding to the 200°C blackbody furnace was 9262, the luminance value of the region corresponding to the 100°C blackbody furnace was 5335, while the luminance value of the internal stray light in the center of the image was 4797. In other words, the luminance difference between the luminance value of the region corresponding to the 100°C blackbody furnace and the luminance value of the internal stray light is (5335-4797) / 4797 ≈ 11% relative to the luminance value of the internal stray light, which shows a dramatic improvement in the signal-to-noise ratio compared to the case shown in Figure 3.

[0047] We attempted to capture a two-dimensional brightness image by installing the photodetector 110 described above on a cold rolling line in the steel industry. Specifically, as schematically shown in Figure 6, the photodetector 110 shown in Figure 4A was installed on the side between adjacent cold rolling stands on the cold rolling line. In this case, in order to capture the surface of the cold-rolled steel sheet, which is the object to be measured and has a temperature of about 100°C to 200°C, within the same field of view, the photodetector was positioned to look down on the cold-rolled steel sheet from diagonally above (for example, so that the angle between the cold-rolled steel sheet and the plane of the cold-rolled steel sheet was about 30 to 45 degrees).

[0048] In the cold rolling process, water is used as a coolant to cool cold-rolled steel sheets, which have a surface temperature of around 100°C to 200°C, and rolling oil is used for lubrication during rolling. The steam (water droplets) and oil droplets generated from this water and rolling oil function as scatterers (i.e., disturbances) that scatter the thermal radiation from the cold-rolled steel sheet. In addition, rolling oil used in the cold rolling process and water used as a coolant may adhere to the surface of the cold-rolled steel sheet, and these rolling oils and waters function as absorbers (i.e., disturbances) that absorb the thermal radiation from the cold-rolled steel sheet.

[0049] A general-purpose camera (not shown) that captures visible light images is placed near the photodetector 110 shown in Figure 6, and the visible light image obtained from this camera is shown in Figure 7(a). In Figure 7(a), cold rolling stands are visible at the left and right edges of the image, and steam can be seen rising between the cold rolling stands. Furthermore, cold-rolled steel sheets should be being transported in the area enclosed by the dashed line between the cold rolling stands, but due to the rising steam, the cold-rolled steel sheets cannot be seen in a normal visible light image.

[0050] Furthermore, instead of the photodetector 110 in Figure 6, a general infrared camera with an optical filter with a central wavelength of 4.0 μm located near the detection element, as shown in Figure 2, was used to image the cold-rolled steel sheets located on the cold-rolling stand and between the stands. The results are shown in Figure 7(b). As is clear from the infrared brightness image shown in Figure 7(b), only internal stray light caused by thermal radiation from the optical filter is visible in the image, and thermal radiation from the cold-rolled steel sheets is completely obscured by the internal stray light and cannot be detected at all.

[0051] Figure 7(c) shows an infrared brightness image generated using the photodetector 110 shown in Figure 4A. As is clear from Figure 7(c), the two-dimensional brightness image generated using the photodetector 110 according to this embodiment clearly shows the cold rolling stand, the cold-rolled steel sheet, and the roll on which the cold-rolled steel sheet is wound.

[0052] Thus, by using the photodetector 110 according to this embodiment, it becomes possible to clearly image an object to be measured at a low temperature of 100°C to 200°C, even in an environment with disturbances.

[0053] (Considerations regarding multiple reflection mirrors) The inventors separately observed the temperature of cold-rolled steel sheets being transported between cold-rolling stands using a general radiation thermometer with an observation wavelength of 4.0 μm, and found that there was an error of ±10°C from the actual temperature of the cold-rolled steel sheets. The inventors investigated this ±10°C error and found that it was due to the small emissivity ε of the cold-rolled steel sheet surface (approximately 0.25), which is greatly affected by fluctuations in this emissivity. In actual cold-rolling operations, a measurement error of ±10°C would result in insufficient precision in controlling the sheet feeding speed during the cold-rolling process.

[0054] From these findings, the inventors have discovered that in order to perform more accurate temperature measurement in environments where stray light (light generated outside the expected optical path) is present, it is important to increase the effective emissivity by causing multiple reflections of thermal radiation light from the cold-rolled steel sheet, thereby suppressing measurement errors caused by stray light and errors caused by fluctuations in the emissivity of the rolled material (more specifically, the cold-rolled steel sheet) being measured.

[0055] Furthermore, in order to perform even more accurate temperature measurements, it was found that it is preferable to perform air purging to ensure that there are no disturbances in the optical path of the thermal radiation light, in order to suppress the effects of scattering by scatterers such as steam (i.e., disturbances).

[0056] Based on the above findings, the inventors investigated the configuration of a multiple reflection mirror for achieving multiple reflections by conducting simulations using a commercially available numerical computation application and the ray tracing method. For these simulations, the inventors modeled a detection device equipped with a multiple reflection mirror as shown in Figure 8. Figure 8 is an explanatory diagram illustrating the simulation conditions for the multiple reflection mirror.

[0057] As schematically shown in Figure 8, the inventors envisioned a model detection device comprising a detector for detecting thermal radiation in the infrared wavelength band and a multiple reflection mirror for multiple reflection of the thermal radiation. As shown in Figure 8, this multiple reflection mirror is a curved mirror that has the function of reflecting the thermal radiation multiple times to focus it onto the detector, while preventing stray light present in the surroundings from being focused onto the detector. Furthermore, these detector, multiple reflection mirror, and focusing lens are housed inside a housing, and an aperture is formed on the end face of the housing facing the cold-rolled steel sheet, which is the object to be measured.

[0058] In the configuration shown in Figure 8, the design parameters to be considered are as follows, as shown in the figure.

[0059] • The distance between the cold-rolled steel sheet and the position where the multiple reflection mirror is installed (the position of the innermost part of the multiple reflection mirror as viewed from the cold-rolled steel sheet side): D • Height from the end face of the cold-rolled steel sheet on the enclosure side to the position where the multi-reflection mirror is installed (installation height): d • The measurement gap (Dd) is the gap between the end of the enclosure and the cold-rolled steel sheet: • Aperture diameter: L • Radius of curvature of the multiple reflection mirror: R • Diameter of the multi-reflection mirror: 2r

[0060] Of these, to prevent contact with the cold-rolled steel sheet being measured, it is preferable to ensure a measurement gap of approximately 100 mm, and to prevent contamination of the multiple reflection mirror, it is preferable to ensure a distance D between the mirror steel sheets of approximately 300 mm. Based on these requirements, it is preferable to ensure an installation height d of approximately 200 mm for the multiple reflection mirror. Furthermore, in order to sufficiently guide thermal radiant light into the housing, it is preferable to ensure an aperture diameter L of approximately 50 mm. In addition, having an aperture diameter L of approximately 50 mm makes it possible to sufficiently remove disturbances such as steam present around the aperture from the optical path when performing the air purging described above.

[0061] Based on the above, the inventors maintain the conditions regarding the three parameters (d, D, L) as described above, while considering the effective emissivity ε m We explored the design parameters that result in a desirable state using ray tracing simulation. Here, the effective emissivity ε m This is the emissivity ε (=0.25) of the cold-rolled steel sheet multiplied by the amplification factor α of the radiant energy (i.e., ε m =ε × α = 0.25 × α).

[0062] Furthermore, in this simulation, it was assumed that a detection aperture with a diameter of 5 mm was located at the top of the multiple reflection mirror, and light (rays) were emitted from the surface of the steel plate. The simulation calculated how the amplification factor α of the radiated energy passing through the detection aperture changes with and without the multiple reflection mirror.

[0063] <Radius of curvature R of a multiple reflection mirror> First, the inventors conducted simulations regarding the radius of curvature R of the multiple reflection mirror, which is an important design parameter when considering the miniaturization of the detection device. In this simulation, the diameter of the multiple reflection mirror was set to 2r = 120 mm, the aperture diameter L = 50 mm, the distance between the mirror steel plates D = 300 mm, and the installation height d = 100 mm. The radiant energy amplification factor α was then calculated while varying the radius of curvature R in the range of 100 mm to 600 mm.

[0064] The results obtained are shown in Figure 9. Figure 9 is a graph showing the relationship between the radius of curvature R of the multiple reflection mirror and the amplification factor α of the radiated energy. In Figure 9, the horizontal axis represents the radius of curvature R of the multiple reflection mirror (unit: mm), and the vertical axis represents the amplification factor α of the radiated energy.

[0065] As is clear from Figure 9, when the radius of curvature R of the multiple reflection mirror is 100 mm, the amplification factor of radiant energy α = 1 (i.e., the emissivity ε of the cold-rolled steel sheet remains unamplified). Here, the relationship f = radius of curvature R / 2 of the mirror generally holds. When the radius of curvature R = 100 mm, the focal length of the mirror becomes f = 50 mm, and the focal position of the mirror is near the multiple reflection mirror. As a result, the light reflected by the multiple reflection mirror is dissipated, meaning that multiple reflection was not realized.

[0066] Furthermore, as the radius of curvature R of the multiple reflection mirror increases from 100 mm (in other words, as the multiple reflection mirror approaches a flat mirror from a curved mirror), the amplification factor α also increases, reaching its maximum (α ≈ 2) when the radius of curvature R = 400 mm, and thereafter gradually decreasing.

[0067] When the radius of curvature R of the multiple reflection mirror is 400 mm, the focal position of the mirror is f = 200 mm, based on the relationship f = radius of curvature R / 2, and the focal position of the mirror coincides with the position of the aperture of the housing. From this, it was found that (1) the amplification factor α increases as the focal position of the multiple reflection mirror approaches the position of the aperture, and the amplification factor α is maximized when the focal position of the mirror coincides with the position of the aperture, and (2) as the focal position of the mirror moves outside the housing and approaches the cold-rolled steel sheet, the amount of multiple reflected light that is deflected by the aperture and does not reach the multiple reflection mirror increases, resulting in a decrease in the amplification factor α.

[0068] The results shown in Figure 9 are plotted with the horizontal axis of the graph changed from the radius of curvature R of the multiple reflection mirror to (radius of curvature R of the multiple reflection mirror / installation height d of the mirror), and this is shown in Figure 10. Figure 10 is a graph showing the relationship between (radius of curvature R of the multiple reflection mirror / installation height d of the mirror) and the amplification factor α of the radiated energy.

[0069] As is clear from Figure 10, when the (radius of curvature R of the multiple reflection mirror / installation height d of the mirror) is within the range of 1.75 to 2.75, the amplification factor α of the radiated energy becomes an extremely high value of over 1.8. From these results, it is preferable that the (radius of curvature R of the multiple reflection mirror / installation height d of the mirror) be within the range of 1.75 to 2.75.

[0070] <Aperture diameter L> Next, the inventors determined the effective emissivity ε when the aperture diameter L is varied within the range of 30 mm to 70 mm, with a multiple reflection mirror having a diameter 2r = 120 mm, a radius of curvature R = 400 mm, a distance D between mirror steel plates = 300 mm, and an installation height d = 100 mm. m This was calculated using the same simulation as described above. The results are shown in Figure 11. Figure 11 shows the aperture diameter L and the effective emissivity ε. m This graph shows the relationship between the two factors. In Figure 11, the horizontal axis represents the aperture diameter L (unit: mm), and the vertical axis represents the effective emissivity ε. mIt is.

[0071] As is clear from FIG. 11, within the range where the aperture diameter L is 50 mm or more and 70 mm or less, the effective emissivity ε m is found to be 0.5 or more. From this perspective, the aperture diameter L is preferably 50 mm or more and 70 mm or less. At this time, when the aperture diameter L becomes larger than the diameter 2r of the multiple reflection mirror, there is a high possibility that disturbances such as steam will enter the inside of the housing. Therefore, it is preferable to set the aperture diameter L while paying attention to the size of the diameter 2r of the multiple reflection mirror. Also, when performing air purge, the smaller the aperture diameter L, the stronger the momentum of the gas jetted from the aperture, and it becomes possible to more surely eliminate disturbances such as steam existing on the optical path. From this perspective, in the simulation shown below, the aperture diameter L was set to 50 mm for examination.

[0072] <Diameter 2r of the multiple reflection mirror> Next, the inventors set the radius of curvature R of the multiple reflection mirror to 400 mm, the aperture diameter L to 50 mm, the distance D between the mirror steel plates to 300 mm, and the installation height d to 100 mm, and then changed the diameter 2r of the multiple reflection mirror within the range of 30 mm to 150 mm, and calculated the effective emissivity ε m by the same simulation as above. The obtained results are shown in FIG. 12. FIG. 12 is a graph showing the relationship between the diameter 2r of the multiple reflection mirror and the effective emissivity ε m In FIG. 12, the horizontal axis is the diameter 2r (unit: mm) of the multiple reflection mirror, and the vertical axis is the effective emissivity ε m It is.

[0073] As is clear from FIG. 12, within the range where the diameter 2r of the multiple reflection mirror is 120 mm or more and 150 mm or less, the effective emissivity ε mIt can be seen that this is 0.5 or greater. From this viewpoint, it is preferable that the diameter 2r of the multiple reflection mirror be between 120 mm and 150 mm. On the other hand, as the diameter 2r of the multiple reflection mirror increases, the detection device becomes larger, which imposes many constraints on the installation location when installing the detection device on an actual cold rolling line. From this viewpoint, it is preferable that the diameter 2r of the multiple reflection mirror be around 120 mm.

[0074] (Regarding the configuration of the detection device in a temperature measuring device) Based on the results of the studies on the photodetector 110 and the multiple reflection mirror described above, the inventors have conceived of the detection device shown in Figure 13 as a detection device for self-illumination from cold-rolled steel sheets in the temperature measuring device according to this embodiment. Figure 13 is a schematic diagram showing an example of the configuration of the detection device in the temperature measuring device according to this embodiment.

[0075] As shown in Figure 13, the detection device 100 in the temperature measuring device according to this embodiment mainly comprises a housing 101 (first housing 101), a photodetector 110, and a multiple reflection mirror 151, and detects self-illumination from the rolled material (more specifically, cold-rolled steel sheet) which is the object to be measured.

[0076] The photodetector 110 is a photodetector equipped with a cooling mechanism for an optical filter, as illustrated in Figures 4A and 4B, and is located inside the housing 101. The photodetector 110 detects self-illumination from the cold-rolled steel sheet and converts the detected self-illumination into an electrical signal corresponding to its intensity. The photodetector 110 is controlled by a processing unit (not shown), and the electrical signal corresponding to the detected self-illumination is output to this processing unit.

[0077] As shown in Figures 4A and 4B, the photodetector 110 houses a detection unit 111 for detecting self-illumination and an optical filter housing 123 (second housing) that is provided independently of the detection unit 111. The optical filter housing 123 (second housing) contains an optical filter 121 that transmits self-illumination in wavelength bands where there is no absorption due to disturbances present around the object being measured, and a cooling mechanism 131 for cooling the optical filter 121.

[0078] The detection unit 111 detects self-illumination from the object being measured and converts the detected self-illumination into an electrical signal corresponding to the intensity of the self-illumination. As mentioned earlier, the detection element provided in the detection unit 111 is not particularly limited, and known detection elements for infrared light detection such as InSb, PbSe, PbS, InGaAs, HgCdTe, QWIP, etc., can be used. Furthermore, by using an electronically cooled detector as the detection unit 111, as described later, the measurement accuracy of the temperature of the object being measured can be further improved.

[0079] Furthermore, based on the findings described with reference to Figure 1, the optical filter 121 is preferably an optical filter that transmits self-luminescence in the infrared wavelength band with a central wavelength of 4.0 μm. The transmission bandwidth of the optical filter 121 is not particularly limited and can be appropriately determined according to the required measurement accuracy and the detection resolution of the detection unit 111, but it can be, for example, about 200 nm.

[0080] The multiple reflection mirror 151 is a curved mirror installed inside the housing 101. It reflects the self-illuminating light radiated from the object to be measured in multiple ways to form an image on the detection unit 111, while preventing stray light present around the object to be measured from being imaged on the detection unit 111. The material of this multiple reflection mirror 151 is not particularly limited; any material capable of creating a highly reflective mirror that can achieve specular reflection can be used. Furthermore, from the viewpoint of preventing contamination as described above, it is preferable that the multiple reflection mirror 151 be installed at a distance D from the object to be measured, and at a height d from the end face of the housing 101 on the object to be measured side.

[0081] Here, as mentioned earlier, the radius of curvature R of the multiple reflection mirror 151 is preferably such that the value of (R / D), which is the radius of curvature R divided by the installation height d of the mirror, is between 1.75 and 2.75. By setting the radius of curvature to satisfy this condition, it becomes possible to set the amplification factor α achieved by the multiple reflection by the multiple reflection mirror 151 to 1.8 or higher.

[0082] Furthermore, it is preferable that the diameter 2r of the multiple reflection mirror 151 be between 120 mm and 150 mm. By setting the mirror diameter 2r of the multiple reflection mirror 151 to between 120 mm and 150 mm, it becomes possible to achieve an extremely high effective emissivity while miniaturizing the detection device 100.

[0083] An opening 153 is provided approximately in the center of the multiple reflection mirror 151 described above. This opening 153 is a space provided to guide the self-illuminating light from the object to be measured, which has been reflected multiple times, to the photodetector 110. A suitable size for such an opening 153 is, for example, a diameter of φ = 5 mm.

[0084] Furthermore, it is preferable that an air inlet 103 for introducing purging air into the housing 101 is provided on the end face of the housing 101 on the photodetector 110 side. Gas (air) is introduced from the air inlet 103 via an air supply line (not shown) as an example of a blowing mechanism and ejected from the aperture 105, thereby eliminating disturbances that may exist in the optical path between the object to be measured and the detection device 100. In addition, in order to efficiently direct the gas (air) introduced into the housing 101 toward the aperture 105, it is preferable that an air impact plate 161 is provided near the air inlet 103 inside the housing 101 to move the introduced gas (air) along the inner wall of the housing 101.

[0085] Here, the diameter of the air inlet 103 is not particularly limited and can be appropriately determined according to the size of the diameter L of the aperture 105, the air pressure to be achieved, etc. Similarly, the separation distance between the photodetector 110 and the air impact plate 161, and the separation distance between the air inlet 103 and the air impact plate 161 are not particularly limited and can be appropriately determined.

[0086] Furthermore, an aperture 105 is provided at the end of the housing 101 on the side facing the object to be measured. This aperture 105 is provided in the optical path between the multiple reflection mirror 151 and the object to be measured, with a diameter smaller than the diameter of the multiple reflection mirror 151. It guides the self-illuminating light from the cold-rolled steel sheet, which is the object to be measured, into the housing 101, and also discharges the gas (air) supplied into the housing 101 from the air inlet 103 towards the side facing the object to be measured.

[0087] The aperture diameter L is preferably 50 mm to 70 mm, in accordance with the simulation results explained earlier. By setting the aperture diameter L to 50 mm to 70 mm, it is possible to achieve excellent air purging performance while also achieving an extremely high effective emissivity.

[0088] Furthermore, it is preferable that at least the end face of the housing 101 on which the aperture 105 is provided, facing the object to be measured, be coated with a blackbody coating (not shown), made of blackbody paint. The bottom surface of the housing 101 facing the object to be measured is heated by thermal radiation from the object to be measured, which can cause stray light. Therefore, by providing a blackbody coating on the bottom surface of the housing 101 on the side where the aperture 105 is provided, stray light errors can be further suppressed, making it possible to perform temperature measurement with even greater accuracy. In addition, the blackbody coating may be provided not only on the end face of the housing 101 on the side where the aperture 105 is provided, but also on the entire wall surface of the housing 101.

[0089] (Regarding the configuration of the processing unit in a temperature measurement device) Next, with reference to Figure 14, the configuration of the processing unit in the temperature measuring device according to this embodiment will be described in detail. Figure 14 is a schematic diagram showing an example of the configuration of the processing unit in the temperature measuring device according to this embodiment.

[0090] As shown in Figure 14, the arithmetic processing unit 200 of the temperature measuring device 10 according to this embodiment includes a detection control unit 201, an arithmetic processing unit 203, a display control unit 205, and a storage unit 207.

[0091] The detection control unit 201 is implemented by, for example, a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), communication device, etc. The detection control unit 201 comprehensively controls the detection process of self-illumination from the cold-rolled steel sheet, which is the object to be measured, by the detection device 100 according to this embodiment.

[0092] More specifically, when the detection control unit 201 starts detecting self-illumination from the cold-rolled steel sheet being measured, it sends a control signal to the detection device 100 to activate the light detection unit 110, causing the detection of self-illumination to start in an appropriate state according to the installation environment of the detection device 100. In addition, each time the detection control unit 201 acquires a PLG signal (for example, a PLG signal output every time the cold-rolled steel sheet moves 1 mm) periodically sent from the drive mechanism or the like that controls the transport of the cold-rolled steel sheet being measured, it sends a trigger signal to the detection device 100 to output an electrical signal corresponding to the intensity of the detected self-illumination.

[0093] The arithmetic processing unit 203 is implemented by, for example, a CPU, ROM, RAM, communication device, etc. The arithmetic processing unit 203 calculates the temperature of the object to be measured by performing calculations as described below, using the electrical signal relating to the intensity of self-illumination from the object to be measured, which is detected by the detection device 100. The arithmetic processing unit 203 will be described in more detail below.

[0094] The display control unit 205 is implemented by, for example, a CPU, ROM, RAM, output device, etc. The display control unit 205 controls the display of information regarding the temperature of the object being measured, output from the arithmetic processing unit 203, on an output device such as a display provided by the arithmetic processing unit 200, or on an output device provided outside the arithmetic processing unit 200. As a result, users of the temperature measuring device 10 can immediately grasp information regarding the temperature of the object being measured.

[0095] The memory unit 207 is implemented, for example, by a RAM or storage device provided in the arithmetic processing unit 200 according to this embodiment. The memory unit 207 appropriately records various parameters, intermediate processing results, and various databases and programs that the arithmetic processing unit 200 according to this embodiment needs to save when performing some processing. The detection control unit 201, arithmetic processing unit 203, display control unit 205, and the higher-level computer can freely read and write data from this memory unit 207.

[0096] <About the arithmetic processing unit 203> Next, with reference to Figure 15, the configuration of the arithmetic processing unit 203 of the arithmetic processing unit 200 according to this embodiment will be described in detail. Figure 15 is a block diagram showing an example of the configuration of the arithmetic processing unit in the arithmetic processing unit of the temperature measuring device according to this embodiment.

[0097] The calculation processing unit 203 according to this embodiment is a processing unit that calculates the temperature of the object to be measured based on an electrical signal corresponding to the intensity of self-illumination from the object to be measured, detected by the detection device 100. As shown in Figure 15, the calculation processing unit 203 according to this embodiment includes a temperature calculation unit 211 and a result output unit 213.

[0098] The temperature calculation unit 211 is implemented by, for example, a CPU, ROM, RAM, etc. The temperature calculation unit 211 calculates the temperature of the object to be measured by using the electrical signal corresponding to the intensity of the self-illumination detected by the detection device 100 and the relationship between the magnitude of the electrical signal and the temperature, which has been determined in advance.

[0099] More specifically, the detection device 100 detects the self-luminescence radiated from the object being measured via an optical filter 121 cooled by a cooling mechanism 131, and the temperature calculation unit 211 calculates the magnitude (e.g., voltage value) of the electrical signal corresponding to the intensity of the detected self-luminescence, using the effective emissivity ε of the object being measured, which has been determined in advance. m Divide by this to calculate the true intensity of the self-luminescence from the object under consideration. Here, the effective emissivity ε of the object under consideration is used. m The effective emissivity ε of such an object may be determined in advance by measuring the object using a known method, calculated by various simulations including ray tracing simulations as previously used, or obtained by using various literature values. m It is preferable that information relating to this be stored, for example, as emissivity data in the memory unit 207.

[0100] Subsequently, the temperature calculation unit 211 calculates the temperature of the object being measured using the obtained true intensity and the relationship between the magnitude of the electrical signal and temperature, which has been determined in advance. As an example of the relationship between the magnitude of the electrical signal and temperature used by the temperature calculation unit 211, one can cite a temperature calibration graph that shows the relationship between the output voltage value and temperature, as schematically shown in Figure 16. Figure 16 is an example of a temperature calibration graph that shows the relationship between the output voltage value and temperature. A temperature calibration graph like the one shown in Figure 16 can be prepared in advance by detecting the self-illumination from an object with a known temperature (for example, a blackbody furnace set to a specific temperature) using the photodetector 110 and plotting the voltage value of the electrical signal output from the photodetector 110. The temperature calibration graph shown in Figure 16 plots the voltage value of the electrical signal from the photodetector 110 when a blackbody furnace set to a temperature of 75 to 225°C is detected by the photodetector 110 as shown in Figure 4A.

[0101] As shown in Figure 16, the output voltage value and temperature show an extremely good correlation (R 2 =0.9985), output voltage value, and the relationship formula ((temperature) = 152.32 × (output voltage) 0.3094 It can be seen that the temperature can be calculated using ). It is preferable that such a relation is stored as relation data in the storage unit 207, for example.

[0102] As mentioned earlier, in order to improve the measurement accuracy of the temperature of the object to be measured, it is preferable to use an electronically cooled detector as the detection unit 111. This is because, in this embodiment, in order to detect self-luminescence in the infrared wavelength band, the detector itself may be heated by the self-luminescence being detected, which could reduce the detection accuracy. Figure 17 is a schematic diagram illustrating the mechanism of an electronically cooled detector. As shown in Figure 17, an electronically cooled detector is provided with a photodetector 141 that detects self-luminescence and an element cooling mechanism 143 that cools the photodetector 141 according to the applied cooling voltage. By applying a cooling voltage to the element cooling mechanism 143, such as a Peltier element, according to the installation environment of the detector, the element cooling mechanism 143 cools the photodetector 141, thereby ensuring the detection accuracy of the photodetector 141.

[0103] The inventors, seeking further improvements in measurement accuracy, investigated such electronically cooled detectors and realized that changes in cooling voltage due to changes in the measurement environment were one of the factors causing measurement errors. Therefore, the inventors used an electronically cooled detector to detect self-illumination in a blackbody furnace with a known temperature while maintaining a constant temperature and varying the cooling voltage. The results obtained are shown in Figure 18. Figure 18 is a graph showing the relationship between the cooling voltage applied to the photodetector and the output ratio of the voltage output from the photodetector.

[0104] In this case, the output voltage of the electrical signal obtained when the photodetector detects the self-luminescence from a blackbody furnace at a known temperature, with a cooling voltage corresponding to that temperature applied to the element cooling mechanism, is defined as the reference output voltage a (unit: V). The output voltage of the electrical signal obtained when the photodetector detects the self-luminescence from the blackbody furnace at a known temperature with a different cooling voltage is defined as a' (unit: V). The above output ratio R is defined as the ratio of output voltage a' to reference output voltage a (a' / a). The output ratio R of the photodetector when the reference output voltage a is applied is set to 1. When the electronically cooled detector shown in Figure 18 was installed in an environment with an ambient temperature of 25°C, the cooling voltage was 1.545V. This 1.545V corresponds to the reference output voltage a shown in Figure 18.

[0105] As is clear from Figure 18, when detecting the self-luminescence from a blackbody furnace maintained at the same temperature while varying the cooling voltage, the output ratio R was found to have the relationship (output ratio) = 1.6958 × (cooling voltage) - 1.6338, indicating that it changes linearly with respect to the cooling voltage. Therefore, in actual temperature measurements, by using this relationship to determine the output ratio R based on the cooling voltage applied to the element cooling mechanism, and then correcting the true intensity using the obtained output ratio R, it becomes possible to perform more accurate temperature measurements without being affected by the ambient temperature environment.

[0106] For example, suppose we measure the temperature of a steel plate with emissivity ε. Assume the output voltage from the photodetector is a''(V) and the cooling voltage is V'(V). Without such correction, the temperature T1 can be calculated using the relationship shown in Figure 16: T1 = 152.32 × (a'' / ε). 0.3094 However, when corrected using the relationship shown in Figure 18, the resulting temperature T2 is T2 = 152.32 × (a'' / εR) 0.3094 This is the result.

[0107] When the electronically cooled detector shown in Figure 18 was installed in an environment with an ambient temperature of 35°C, the cooling voltage became 1.500V. Therefore, the output ratio R1 in this case was R1 = 0.91, as shown in the relationship in Figure 18. This output ratio R1 means that the output decreased by 9%.

[0108] Let's assume that the temperature of a cold-rolled steel sheet with a temperature of 150°C and emissivity ε=0.25 is calculated by detecting its self-illumination. If no correction is made as described above, using the relationship shown in Figure 16 in reverse, the output voltage a1 from the photodetector is 150 = 152.32 × (a1 / 0.25). 0.3094 From this relationship, a1 = 0.238V. However, considering the correction using the output ratio R1 = 0.91 mentioned above, the corrected output value a2 = a1 × R1 = 0.216V. Using this corrected voltage value, the temperature can be calculated from the relationship shown in Figure 16 to be 145.6℃.

[0109] Similarly, suppose we detect the self-illumination of a cold-rolled steel sheet with a temperature of 200°C and emissivity ε=0.25 to calculate the temperature. If we do not perform the above correction, using the relationship shown in Figure 16 in reverse, the output voltage a3 from the photodetector is 200 = 152.32 × (a3 / 0.25) 0.3094 From this relationship, a3 = 0.601V. However, considering the correction using the output ratio R1 = 0.91 mentioned above, the corrected output value a4 = a3 × R1 = 0.548V. Using this corrected voltage value, the temperature can be calculated from the relationship shown in Figure 16 to be 194.1℃.

[0110] As described above, if the correction using cooling voltage is not considered, measurement errors will occur. However, by performing the correction using cooling voltage as described above, such measurement errors can be suppressed, and more accurate temperature measurement can be achieved.

[0111] Once the temperature calculation unit 211 calculates the temperature of the object to be measured as described above, it outputs information indicating the obtained temperature calculation result to the result output unit 213, which will be described later.

[0112] The result output unit 213 is implemented by, for example, a CPU, ROM, RAM, communication device, etc. The result output unit 213 outputs temperature information regarding the temperature of the object being measured, calculated by the temperature calculation unit 211, to, for example, the display control unit 205. The method of displaying the temperature in the display control unit 205 is not particularly limited; the temperature of the object being measured may be displayed as a numerical value, or the temperature may be converted to a hue and the temperature of the object being measured may be displayed as a color. The result output unit 213 may also output the calculated temperature information to an external device via various networks such as the Internet or a local area network. Furthermore, the result output unit 213 may output the calculated temperature information as a printed document using a printer or the like.

[0113] Furthermore, the result output unit 213 may associate the calculated temperature information with time information such as the date and time when the data was calculated, and record it in the storage unit 207 as history information.

[0114] The above describes an example of the functions of the arithmetic processing unit 200 according to this embodiment. Each of the above components may be composed of general-purpose materials and circuits, or it may be composed of hardware specialized for the function of each component. Furthermore, the functions of each component may all be performed by a CPU or the like. Therefore, it is possible to change the configuration used as appropriate according to the technological level at the time of implementing this embodiment.

[0115] Furthermore, it is possible to create computer programs to realize each of the functions of the arithmetic processing unit according to this embodiment as described above, and implement them in personal computers, process computers, etc. A computer-readable recording medium containing such a computer program can also be provided. Examples of recording media include magnetic disks, optical disks, magneto-optical disks, and flash memory. Alternatively, the above-mentioned computer program may be distributed, for example, via a network, without using a recording medium.

[0116] (Regarding temperature measurement methods) Next, an example of a temperature measurement method using a temperature measuring device 10 having the configuration shown in Figures 13 to 15 will be explained with reference to Figure 19. Figure 19 is a flowchart showing an example of the temperature measurement method according to this embodiment.

[0117] As shown in Figure 19, in the temperature measurement method according to this embodiment, first, a detection device having the configuration shown in Figure 13 is installed in a position where it can detect self-illumination from the object to be measured (step S101).

[0118] Subsequently, the self-illuminating light from the object to be measured is detected by a detection unit provided in the detection device while it is undergoing multiple reflections between the object and a multiple reflection mirror provided in the detection device (step S103). At this time, it is preferable to supply purging air into the housing of the detection device to ensure that there are no disturbances in the optical path, and to detect the self-illuminating light radiated from the object to be measured via the optical filter 121 cooled by the cooling mechanism 131.

[0119] Subsequently, the temperature calculation unit in the processing unit of the temperature measuring device calculates the temperature of the object being measured based on the electrical signal corresponding to the intensity of the self-illumination detected by the detection device, and uses this as the temperature measurement result for the object of interest.

[0120] More specifically, the temperature calculation unit preferably corrects the magnitude of the electrical signal corresponding to the intensity of self-illumination (more specifically, the voltage value output from the detection unit) by utilizing the relationship between the applied cooling voltage and the output ratio, as explained with reference to Figures 17 and 18 (step S105). Subsequently, the temperature calculation unit uses the corrected magnitude of the electrical signal to calculate the temperature of the object to be measured based on the relational expression shown in Figure 16 (step S107). Once the temperature calculation unit has calculated the temperature of the object to be measured in this manner, it outputs the obtained result to the result output unit.

[0121] Subsequently, the result output unit of the arithmetic processing unit outputs the calculated temperature as the temperature measurement result of the object of interest (step S109). This allows the user of the temperature measuring device to understand the temperature of the object of interest.

[0122] Figure 20A shows the measurement results when the temperature of cold-rolled steel sheets being transported along the cold-rolling line during the cold-rolling process is measured using a general radiation thermometer, and Figure 20B shows the measurement results of the temperature of cold-rolled steel sheets measured according to the temperature measurement method described above. Figures 20A and 20B are graphs showing the temperature measurement results of cold-rolled steel sheets being transported along the cold-rolling line during the cold-rolling process. In Figures 20A and 20B, the horizontal axis represents the elapsed time since the start of measurement (in seconds), and the vertical axis represents the difference from the average temperature calculated from the measurement results (in °C).

[0123] As shown in Figure 20A, the measurement error was ±10°C when measuring temperature using a general radiation thermometer. On the other hand, as shown in Figure 20B, the measurement error was ±1.8°C when measuring temperature using the temperature measurement method according to this embodiment while correcting the output value. In other words, it can be seen that the measurement error was reduced to about 1 / 5 compared to temperature measurement using a general radiation thermometer by using the temperature measurement device according to this embodiment.

[0124] (Regarding sheet metal speed control in the cold rolling process) By using the temperature measuring device described above, it becomes possible to achieve the following sheet metal speed control in the cold rolling process. This sheet metal speed control will be explained in detail with reference to Figure 21. Figure 21 is an explanatory diagram for explaining sheet metal speed control in the cold rolling process.

[0125] The graph shown in Figure 21 plots the results of an investigation into how the steel sheet temperature changes from a reference temperature (unit: °C) when the sheet feeding speed (unit: mpm) is changed from a reference temperature (unit: °C) in the cold rolling process. In Figure 21, the horizontal axis shows the difference from the reference sheet feeding speed, and the vertical axis shows the difference from the reference steel sheet temperature.

[0126] As is clear from the plot in Figure 21, there is a linear relationship between the change in sheet metal speed and the change in sheet metal temperature, indicating that as the sheet metal speed increases, the sheet metal temperature also increases. Furthermore, when the surface condition of the sheet metal in each of the conditions represented by each plot was examined, it was found that heat scratches occurred in the region where the sheet metal speed exceeded 350 mpm.

[0127] In the cold rolling process, the feed speed is controlled to ensure that heat scratches never occur on the cold-rolled steel sheets being manufactured. Heat scratches are defects that occur when the steel sheet temperature rises, causing the oil film between the cold-rolled steel sheet and the work roll to disappear. Therefore, to prevent heat scratches, it is necessary to control the feed speed so that the steel sheet temperature does not fall into the heat scratch occurrence range. In actual operation, the steel sheet temperature at the boundary between the heat scratch occurrence range and the non-heat scratch range is set as the threshold temperature, and a temperature with a sufficient safety margin above this threshold temperature is treated as the control temperature.

[0128] Conventional steel plate temperature measurements using general-purpose radiation thermometers had a measurement error of approximately ±10°C, as illustrated in Figure 20A. Therefore, as a safety margin from the threshold temperature, it was necessary to ensure a safety margin of 10°C or more, taking into account the measurement error of ±10°C. Consequently, as schematically shown in Figure 21, even when attempting to increase the plate speed from the reference plate speed, the range of the speed increase had to be narrowed.

[0129] On the other hand, in steel sheet temperature measurement using the temperature measuring device according to this embodiment, the measurement error is suppressed to ±1.8°C, as illustrated in Figure 20B. Therefore, it becomes possible to reduce the safety margin from the threshold temperature compared to conventional methods, and as a result, the range of speed increases from the reference sheet feeding speed can be made wider. In this way, by using the temperature measuring device according to this embodiment, it becomes possible to control the sheet feeding speed of the cold rolling line more precisely and to further increase the speed of the cold rolling line.

[0130] (Regarding the plate speed control device) An example of the configuration of a sheet metal speed control device for achieving the sheet metal speed control described above will be explained with reference to Figure 22. Figure 22 is a schematic diagram showing an example of the configuration of a sheet metal speed control device according to this embodiment.

[0131] The sheet metal speed control device according to this embodiment measures the temperature of a cold-rolled steel sheet, which is an example of a rolled material, as it passes through a cold-rolling line composed of multiple cold-rolling stands, using a temperature measuring device that measures the temperature of the cold-rolled steel sheet by detecting the self-illuminating radiation emitted from the cold-rolled steel sheet, and controls the sheet metal speed of the cold-rolling line according to the temperature measurement result of the cold-rolled steel sheet.

[0132] As shown in Figure 22, the sheet metal speed control device 1 according to this embodiment includes a temperature measuring device 10 and a sheet metal speed control unit 20.

[0133] The detailed configuration and function of the temperature measuring device 10 have been explained earlier, so a detailed explanation will be omitted below. The detection device of the temperature measuring device 10 is installed between adjacent cold rolling stands, as shown in Figure 22, in order to detect the self-illumination from the cold-rolled steel sheet.

[0134] The temperature measuring device 10 detects the self-illumination from the cold-rolled steel sheet being transported and measures the temperature of the cold-rolled steel sheet based on this self-illumination. The data regarding the temperature measurement result of the cold-rolled steel sheet is output to the sheet feed speed control unit 20.

[0135] The sheet metal speed control unit 20 is implemented by, for example, a CPU, ROM, RAM, communication device, etc. The sheet metal speed control unit 20 uses a predetermined relationship between the temperature of the cold-rolled steel sheet and the sheet metal speed, as illustrated in Figure 21, to control the sheet metal speed so that the temperature measurement result of the cold-rolled steel sheet by the temperature measuring device 10 is below a predetermined threshold temperature. More specifically, the sheet metal speed control unit 20 controls the sheet metal speed of the cold-rolled steel sheet by controlling the rotation speed of the conveyor rolls and other components that constitute the cold-rolling line during the cold-rolling process.

[0136] As explained with reference to Figure 21, the use of the temperature measuring device 10 according to this embodiment makes it possible to measure the temperature of the cold-rolled steel sheet with greater accuracy. As a result, it becomes possible to secure a larger range for increasing the sheet feeding speed than in the conventional method, making it possible to further increase the speed of the cold-rolling line.

[0137] In Figure 22, for convenience, the sheet metal speed control unit 20 is shown as having a different configuration from the temperature measuring device 10. However, such a sheet metal speed control unit 20 may be implemented as a function of the arithmetic processing unit 200 of the temperature measuring device 10. Furthermore, the arithmetic processing unit 200 and the sheet metal speed control unit 20 of the temperature measuring device 10 may be implemented as a function of a process computer, which is a higher-level computing device that comprehensively controls the operation of the cold rolling process.

[0138] (Regarding the hardware configuration of the processing unit) Next, with reference to Figure 23, the hardware configuration of the arithmetic processing unit 200 in the temperature measuring device according to an embodiment of the present invention will be described in detail. Figure 23 is a block diagram illustrating the hardware configuration of the arithmetic processing unit 200 according to an embodiment of the present invention.

[0139] The arithmetic processing unit 200 mainly comprises a CPU 901, a ROM 903, and a RAM 905. Furthermore, the arithmetic processing unit 200 also comprises a bus 907, an input device 909, an output device 911, a storage device 913, a drive 915, a connection port 917, and a communication device 919.

[0140] The CPU 901 functions as the central processing and control unit, controlling all or part of the operations within the arithmetic processing unit 200 according to various programs recorded in the ROM 903, RAM 905, storage device 913, or removable recording medium 921. The ROM 903 stores programs and arithmetic parameters used by the CPU 901. The RAM 905 temporarily stores programs used by the CPU 901 and parameters that change as needed during program execution. These are interconnected by a bus 907, which is composed of internal buses such as the CPU bus.

[0141] Bus 907 is connected to an external bus, such as the PCI (Peripheral Component Interconnect / Interface) bus, via a bridge.

[0142] The input device 909 is, for example, an operating means operated by the user, such as a mouse, keyboard, touch panel, buttons, switches, and levers. Alternatively, the input device 909 may be, for example, a remote control using infrared or other radio waves (a so-called remote control), or an external connected device 923 such as a PDA that corresponds to the operation of the arithmetic processing unit 200. Furthermore, the input device 909 is composed of, for example, an input control circuit that generates an input signal based on information input by the user using the above-mentioned operating means and outputs it to the CPU 901. By operating this input device 909, the user can input various data to the arithmetic processing unit 200 or instruct it to perform processing operations.

[0143] The output device 911 is comprised of a device capable of visually or audibly notifying the user of acquired information. Such devices include display devices such as CRT displays, liquid crystal displays, plasma displays, EL displays, and lamps, as well as audio output devices such as speakers and headphones, printers, mobile phones, and facsimile machines. The output device 911 outputs, for example, the results obtained from various processes performed by the arithmetic processing unit 200. Specifically, the display device displays the results obtained from various processes performed by the arithmetic processing unit 200 as text or images. On the other hand, the audio output device converts the audio signal, consisting of reproduced audio data or sound data, into an analog signal and outputs it.

[0144] The storage device 913 is a data storage device configured as an example of the storage unit of the arithmetic processing unit 200. The storage device 913 is composed of, for example, a magnetic storage device such as an HDD (Hard Disk Drive), a semiconductor storage device, an optical storage device, or a magneto-optical storage device. This storage device 913 stores programs executed by the CPU 901, various data, and various data acquired from external sources.

[0145] The drive 915 is a reader / writer for recording media and is either built into or external to the arithmetic processing unit 200. The drive 915 reads information recorded on the removable recording media 921, such as a magnetic disk, optical disk, magneto-optical disk, or semiconductor memory, and outputs it to the RAM 905. The drive 915 can also write data to the removable recording media 921, such as a magnetic disk, optical disk, magneto-optical disk, or semiconductor memory. The removable recording media 921 is, for example, a CD media, DVD media, Blu-ray® media, etc. The removable recording media 921 may also be CompactFlash® (CF), flash memory, or an SD memory card (Secure Digital memory card), etc. The removable recording media 921 may also be, for example, an IC card (Integrated Circuit card) or electronic device equipped with a contactless IC chip.

[0146] The connection port 917 is a port for directly connecting devices to the processing unit 200. Examples of connection port 917 include USB (Universal Serial Bus) ports, IEEE1394 ports, SCSI (Small Computer System Interface) ports, RS-232C ports, and HDMI (High-Definition Multimedia Interface) ports. By connecting an external device 923 to this connection port 917, the processing unit 200 can directly acquire various data from the external device 923 or provide various data to the external device 923.

[0147] The communication device 919 is a communication interface composed of, for example, a communication device for connecting to the communication network 925. The communication device 919 may be, for example, a communication card for wired or wireless LAN (Local Area Network), Bluetooth (registered trademark), or WUSB (Wireless USB). Alternatively, the communication device 919 may be a router for optical communication, a router for ADSL (Asymmetric Digital Subscriber Line), or a modem for various types of communication. This communication device 919 can, for example, send and receive signals to and from the Internet or other communication devices in accordance with a predetermined protocol such as TCP / IP. The communication network 925 connected to the communication device 919 is composed of a network connected by wire or wireless, and may be, for example, the Internet, a home LAN, a company LAN, infrared communication, radio wave communication, or satellite communication.

[0148] The above describes an example of a hardware configuration capable of realizing the functions of the arithmetic processing unit 200 according to an embodiment of the present invention. Each of the above components may be made up of general-purpose materials, or it may be made up of hardware specialized for the function of each component. Therefore, it is possible to change the hardware configuration used as appropriate depending on the level of technology at the time of implementing this embodiment.

[0149] Although preferred embodiments of the present invention have been described in detail above with reference to the attached drawings, the present invention is not limited to these examples. It is clear to any person with ordinary skill in the art to which the present invention belongs that various modifications or alterations can be conceived within the scope of the technical idea described in the claims, and these are also understood to fall within the technical scope of the present invention. [Explanation of Symbols]

[0150] 1. Plate speed control device 10 Temperature measuring device 20. Track speed control unit 100 detection device 101 cabinets 103 Air Inlet 105 Aperture 110 Photodetectors 111 Detection Unit 113 cabinets 115 Detection Unit 121 Optical Filters 123 Optical filter housing 131 Cooling mechanism 133 Peltier element 135 Heatsink 141 Photodetector 143 Element Cooling Mechanism 151 Multiple Reflection Mirror 153 Opening 161 Air impact plate 200 Arithmetic Processing Unit 201 Detection Control Unit 203 Arithmetic Processing Unit 205 Display Control Unit 211 Temperature calculation section 213 Result Output Section

Claims

1. A temperature measuring device that measures the temperature of an object to be measured by detecting self-luminescence radiated from the object in an environment with disturbances, The first enclosure and A detection unit is provided inside the first housing and detects the self-illuminating light and outputs an electrical signal corresponding to the intensity of the self-illuminating light, A curved mirror is provided in the optical path between the object to be measured and the detection unit inside the first housing, and multiple reflections of the self-emitting light are made to form an image for the detection unit, A blowing mechanism for supplying gas into the first housing, On the end face of the first housing on the side of the object to be measured, an aperture is provided on the optical path between the multiple reflection mirror and the object to be measured, having a diameter smaller than the diameter of the multiple reflection mirror, for discharging the gas supplied into the first housing by the blowing mechanism toward the side of the object to be measured, A second housing is provided inside the aforementioned detection unit, An optical filter provided inside the second housing transmits light in a wavelength band that is not absorbed by disturbances present around the object to be measured, A temperature calculation unit calculates the temperature of the object to be measured based on the electrical signal output from the detection unit, It has, The detection unit detects the self-luminescence radiated from the object to be measured via the optical filter, The optical filter transmits the self-luminescent light having a central wavelength of 4.0 μm. The temperature calculation unit calculates the temperature of the object to be measured based on the electrical signal output from the detection unit. When the height from the end face of the first housing on the side of the object to be measured to the position where the multiple reflection mirror is installed is d (in mm), and the radius of curvature of the multiple reflection mirror is R (in mm), the relationship 1.75 ≤ R / d ≤ 2.75 is satisfied. When D is the distance between the innermost part of the multiple reflection mirror as viewed from the object being measured and the object being measured, the measurement gap (D-d) is 100 mm or more. A temperature measuring device in which the diameter of the aperture is 50 mm or more and 70 mm or less.

2. The second housing has a cooling mechanism for cooling the optical filter, The temperature measuring device according to claim 1, wherein the detection unit detects the self-luminescence radiated from the object to be measured via the optical filter cooled by the cooling mechanism.

3. A temperature measuring device that measures the temperature of an object to be measured by detecting self-luminescence emitted from the object to be measured, The first enclosure and A detection unit comprising: a photodetector element provided inside the first housing that detects the self-illumination and outputs an electrical signal corresponding to the intensity of the self-illumination; and an element cooling mechanism that cools the photodetector element according to the applied cooling voltage; A curved mirror is provided in the optical path between the object to be measured and the detection unit inside the first housing, and multiple reflections of the self-emitting light are made to form an image for the detection unit, A second housing is provided inside the aforementioned detection unit, An optical filter provided inside the second housing transmits light in a wavelength band that is not absorbed by disturbances present around the object to be measured, A cooling mechanism for cooling the optical filter provided in the second housing, A temperature calculation unit calculates the temperature of the object to be measured based on the electrical signal output from the detection unit, It has, When the detection unit detects the self-illuminating light radiated from the object to be measured via the optical filter cooled by the cooling mechanism, the element cooling mechanism cools the photodetector element. The temperature measurement device comprises a temperature calculation unit that corrects the output of the electrical signal output from the photodetector based on the cooling voltage applied to the element cooling mechanism, and calculates the temperature of the object to be measured based on the corrected output of the electrical signal.

4. The output voltage of the electrical signal detected by the photodetector when the self-illuminating light from a blackbody furnace at a predetermined temperature is detected by the photodetector while the cooling voltage corresponding to that temperature is applied to the element cooling mechanism is defined as the reference output voltage a (unit: V). Let a' (in V) be the output voltage of the electrical signal when the self-illumination from the blackbody furnace, which is at the predetermined temperature, is detected by the photodetector while changing the cooling voltage. When the ratio of the output voltage a' to the reference output voltage a (a' / a) is defined as the output ratio, The relational expression representing the relationship between the output ratio and the cooling voltage is determined in advance. The temperature calculation unit is, When calculating the temperature of the object to be measured, the output ratio is calculated from the cooling voltage applied when the self-illumination from the object to be measured is detected, and the relational expression. The temperature measuring device according to claim 3, which corrects the output voltage of the electrical signal output from the detection unit based on the output ratio.

5. The temperature measuring device according to claim 3 or 4, wherein the temperature of the object to be measured is within the range of 100°C to 200°C at the time of temperature measurement.

6. A sheet metal speed control device that measures the temperature of an object to be measured by detecting self-illumination radiated from the object being passed through a cold rolling line composed of multiple cold rolling stands in an environment with disturbances, and controls the sheet metal speed of the cold rolling line according to the temperature, A temperature measuring device comprising: a first housing; a detection unit provided inside the first housing and detecting the self-illumination and outputting an electrical signal corresponding to the intensity of the self-illumination; a multiple reflection mirror made of a curved mirror provided on the optical path between the object to be measured and the detection unit inside the first housing and causing multiple reflections of the self-illumination to form an image on the detection unit; a blower mechanism for supplying gas into the first housing; an aperture provided on the end face of the first housing on the object to be measured side, on the optical path between the multiple reflection mirror and the object to be measured, having a diameter smaller than the diameter of the multiple reflection mirror, for discharging the gas supplied into the first housing by the blower mechanism toward the object to be measured; a second housing provided inside the detection unit; an optical filter provided inside the second housing and transmitting light in a wavelength band that is not absorbed by disturbances present around the object to be measured; and a temperature calculation unit that calculates the temperature of the object to be measured based on the electrical signal output from the detection unit. A sheet feed speed control unit that controls the sheet feed speed of the cold rolling line, It has, The temperature measuring device is installed between adjacent cold rolling stands. The detection unit detects the self-luminescence radiated from the object to be measured via the cooled optical filter, The optical filter transmits the self-luminescent light having a central wavelength of 4.0 μm. The temperature calculation unit calculates the temperature of the object to be measured based on the electrical signal output from the detection unit. The sheet-feeding speed control unit controls the sheet-feeding speed of the cold-rolling line using the relationship between the temperature of the object to be measured and the sheet-feeding speed, which has been determined in advance, so that the temperature calculated by the detection unit is below a predetermined threshold temperature. When the height from the end face of the first housing on the side of the object to be measured to the position where the multiple reflection mirror is installed is d (in mm), and the radius of curvature of the multiple reflection mirror is R (in mm), the relationship 1.75 ≤ R / d ≤ 2.75 is satisfied. When D is the distance between the innermost part of the multiple reflection mirror as viewed from the object being measured and the object being measured, the measurement gap (D-d) is 100 mm or more. The diameter of the aperture is 50 mm or more and 70 mm or less, in a plate speed control device.

7. A sheet metal speed control device that measures the temperature of an object to be measured by detecting self-illumination emitted from the object being passed through a cold rolling line composed of multiple cold rolling stands, and controls the sheet metal speed of the cold rolling line according to the temperature, A temperature measuring device comprising: a first housing; a detection unit having a photodetector element provided inside the first housing that detects the self-illumination and outputs an electrical signal corresponding to the intensity of the self-illumination; and an element cooling mechanism that cools the photodetector element according to an applied cooling voltage; a multiple reflection mirror made of a curved mirror provided in the optical path between the object to be measured and the detection unit inside the first housing that causes multiple reflections of the self-illumination to form an image on the detection unit; a second housing provided inside the detection unit; an optical filter provided inside the second housing that transmits light in a wavelength band that is not absorbed by disturbances present around the object to be measured; a cooling mechanism provided in the second housing that cools the optical filter; and a temperature calculation unit that calculates the temperature of the object to be measured based on the electrical signal output from the detection unit. A sheet feed speed control unit that controls the sheet feed speed of the cold rolling line, It has, The temperature measuring device is installed between adjacent cold rolling stands. When the detection unit detects the self-illuminating light radiated from the object to be measured via the optical filter cooled by the cooling mechanism, the element cooling mechanism cools the photodetector element. The temperature calculation unit corrects the output of the electrical signal output from the photodetector based on the cooling voltage applied to the element cooling mechanism, and calculates the temperature of the object to be measured based on the corrected output of the electrical signal. The sheet metal speed control unit controls the sheet metal speed of the cold rolling line using a relationship between the temperature of the object to be measured and the sheet metal speed, which has been determined in advance, so that the temperature calculated by the detection unit is below a predetermined threshold temperature.

8. A temperature measurement method for measuring the temperature of an object to be measured by detecting self-luminescence emitted from the object to be measured, A temperature measuring device is used, comprising: a first housing; a detection unit having a photodetector element provided inside the first housing that detects the self-illumination and outputs an electrical signal corresponding to the intensity of the self-illumination; and an element cooling mechanism that cools the photodetector element according to an applied cooling voltage; a multiple reflection mirror made of a curved mirror provided in the optical path between the object to be measured and the detection unit inside the first housing that causes multiple reflections of the self-illumination to form an image on the detection unit; a second housing provided inside the detection unit; an optical filter provided inside the second housing that transmits light in a wavelength band that is not absorbed by disturbances present around the object to be measured; a cooling mechanism provided in the second housing that cools the optical filter; and a temperature calculation unit that calculates the temperature of the object to be measured based on the electrical signal output from the detection unit. When using the detection unit to detect the self-luminescence radiated from the object to be measured via the optical filter cooled by the cooling mechanism, the element cooling mechanism cools the photodetector element. A temperature measurement method comprising: a temperature calculation unit correcting the output of the electrical signal output from the photodetector based on the cooling voltage applied to the element cooling mechanism, and calculating the temperature of the object to be measured based on the corrected output of the electrical signal.

9. A method for controlling the speed at which a sheet of material is passed through a cold rolling line composed of multiple cold rolling stands, wherein the temperature of the material is measured by detecting the self-illuminating light emitted from the material as it passes through the cold rolling line, and the speed at which the sheet of material is passed through the cold rolling line is controlled according to the temperature, A temperature measuring device comprising: a first housing; a detection unit having a photodetector element provided inside the first housing that detects the self-illumination and outputs an electrical signal corresponding to the intensity of the self-illumination; and an element cooling mechanism that cools the photodetector element according to an applied cooling voltage; a multiple reflection mirror made of a curved mirror provided in the optical path between the object to be measured and the detection unit inside the first housing that causes multiple reflections of the self-illumination to form an image on the detection unit; a second housing provided inside the detection unit; an optical filter provided inside the second housing that transmits light in a wavelength band that is not absorbed by disturbances present around the object to be measured; a cooling mechanism provided in the second housing that cools the optical filter; and a temperature calculation unit that calculates the temperature of the object to be measured based on the electrical signal output from the detection unit. A sheet feed speed control unit that controls the sheet feed speed of the cold rolling line, Using a plate speed control device having, The temperature measuring device is installed between adjacent cold rolling stands. When using the detection unit to detect the self-luminescence radiated from the object to be measured via the optical filter cooled by the cooling mechanism, the element cooling mechanism cools the photodetector element. The temperature calculation unit corrects the output of the electrical signal output from the photodetector based on the cooling voltage applied to the element cooling mechanism, and calculates the temperature of the object to be measured based on the corrected output of the electrical signal. A method for controlling the speed of a cold rolling line, using the speed control unit described above, to control the speed of the cold rolling line so that the temperature calculated by the detection unit is below a predetermined threshold temperature, using the relationship between the temperature of the object to be measured and the speed of the speed of the speed of the speed of the object, which has been determined in advance.

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