Thermal measuring and testing – Temperature measurement – Of molten metal
Reexamination Certificate
1999-06-21
2001-05-08
Gutierrez, Diego (Department: 2859)
Thermal measuring and testing
Temperature measurement
Of molten metal
C374S131000, C266S088000, C266S099000
Reexamination Certificate
active
06227702
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a temperature measuring device and a level measuring device using the temperature measuring device.
2. Description of the Related Arts
In a continuous casting process, for example, accurate measurement of temperature and surface level of molten steel during casting is necessary for improving the product quality and the production yield. A conventional technique for measuring the temperature of molten steel in a tundish and a mold involves preparing a solidification chamber inside of a carbon sleeve to introduce the molten steel, and determining the temperature in the solidification chamber using a contact thermometer of a consumable immersion thermocouple type or a thermocouple covered with a ceramic protective tube. As for the method to determine the level of molten steel, conventional art uses an eddy-current distance detector.
The above-described consumable immersion thermocouple degrades after only one measurement because it directly contacts the molten steel. Therefore, the probe to measure the temperature is detachable at the tip of the thermometer, and the tip probe is replaced in every measurement. Since such probes are expensive and are discarded in every measurement, an increase of the number of measurements is difficult.
In the case that the thermocouple is covered with a ceramic tube, the thermocouple does not contact directly with the molten steel. Consequently, a continuous measurement is possible. In this case, however, the durability of ceramic protective tube has a limitation because of heat shock and erosion caused by slag. As a result, even if an expensive protective tube is used, it is generally durable only to 40 to 50 hrs., and repeated use for a long time is impossible.
Still further, with respect to the eddy-current distance detector which is used to determine the level of molten steel, it is useful to achieve level control in accordance with a precise measurement under a steady state condition. The conventional range of measurement, however, is as narrow as 200 mm or less, so such detectors can not be used to determine the level during an automatic start-up. Consequently, automatization to achieve an automatic start-up mode is difficult.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a temperature measuring device which accurately determines the temperature of molten metal at an elevated temperature and to provide a level measuring device which determines an arbitrary level using the temperature measuring device.
The present invention provides a temperature measuring device comprising:
(a) an optical fiber;
(b) a metallic protective tube for covering the optical tube to form a metal-covered optical fiber, a tip of the metal-covered optical fiber being a temperature measuring element; and
(c) a radiation thermometer connected to the metal-covered optical fiber.
Moreover, the present invention provides a level measuring device comprising:
(a) an optical fiber;
(b) a metallic protective tube for covering the optical tube to form a metal-covered optical fiber, a tip of the metal-covered optical fiber being a temperature measuring element;
(c) a radiation thermometer connected to the metal-covered optical fiber;
(d) transfer means for sending the metal-covered optical fiber to a surface of a molten metal to be measured and retracting to wind the metal-covered optical fiber from the surface; and
(e) level determination means for determining a level of the surface of the molten metal based on a temperature change detected by the radiation thermometer and an amount of feed of the optical fiber through the transfer means.
The present invention provides another temperature measuring device comprising:
(a) an optical fiber;
(b) a protective tube for covering the optical fiber;
(c) a heat insulation coating for covering the protective tube, the optical fiber being covered with the protective tube and the heat insulation coating to form a double-covered optical fiber, and a tip of the double-covered optical fiber being a temperature measuring element;
(d) the optical fiber having a corrosion temperature of higher than a temperature of a molten metal to be measured; and
(e) the protective tube and the heat insulation coating having a heat resistant temperature of lower than a temperature of the molten metal to be measured.
The present invention provides still another temperature measuring device comprising:
(a) an optical fiber;
(b) a metallic protective tube for covering the optical fiber;
(c) a heat insulation coating for covering the protective tube, the optical fiber being covered with the protective tube and the heat insulation coating to form a double-covered optical fiber, and a tip of the double-covered optical fiber being a temperature measuring element; and
(d) said heat insulation coating containing particles as an additive having a melting point higher than a temperature of a molten metal to be measured.
The present invention provides yet another temperature measuring device comprising:
(a) an optical fiber;
(b) a metallic protective tube for covering the optical fiber; and
(c) a heat insulation coating for covering the metallic protective tube, the heat insulation coating comprising cellulose.
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English Abstract of JP 62-19727, Published Jan. 28, 1997.
Kaneda Yasushi
Miyahara Hiroaki
Yamada Takeo
Frishauf, Holtz Goodman, Langer & Chick, P.C.
Goodwin Jeanne-Marguerite
Gutierrez Diego
NKK Corporation
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