JP2005241394A - Temperature measurement probe for molten metal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance oxidation resistivity of non-dipped part of a temperature measurement probe for molten metals, enhance the mechanical strength of neck part of the temperature measuring probe and prolong the usable lifetime of the probe. <P>SOLUTION: Around the base end 6a of the non-dipped part 6 of a fireproof protection sleeve 4, the lower end of a cap-shaped cylinder 12 of a fixing metal 11 is put over, and inside the cap-shaped cylinder 12 above the base-end 6a of the non-submergence part 6, castable refractory 22 superior in oxidation resistance and the strength to the fireproof protection sleeve 4 is charged, and so oxidation resistance of the non-dipped part 6 above a slag line is surely improved and airtightness of shielding from surrounding oxidation atmosphere and mechanical strength are maintained. Therefore, the progress of oxidation inside a molybdenum-zirconia tube 3 and resulting embrittlement is suppressed, and bending is prevented. Also the trouble of bending of the molybdenum-zirconia tube 3 at a stress-concentrated part, near a screw-fitting part to fixing metal 11 due to vibration and mechanical stress during operation, can be prevented. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a temperature measuring probe for molten metal that continuously or intermittently measures the temperature of a molten metal such as molten metal.

  An alumina protective tube enclosing a thermocouple, a bottomed alumina protective tube into which the alumina protective tube is inserted, a bottomed molybdenum / zirconia tube into which the alumina protective tube is inserted, and a bottomed end of the molybdenum / zirconia tube Japanese Patent Application Laid-Open No. 8-271347 discloses a molten metal temperature sensor including a fireproof protective sleeve that protects the outer periphery excluding the tip. The temperature sensor for molten metal having the above-described configuration is continuously measured by immersing in a molten metal such as molten metal. In the fireproof protective sleeve, the portion that is immersed in the high-temperature molten metal and the portion where the slag is immersed have the fastest melting damage. For this reason, it is considered that this part is made of a highly corrosion-resistant material and has excellent thermal shock resistance and temperature resistance cycle.

However, if the fireproof protective sleeve is made of a single material with high corrosion resistance as described above, the oxidation resistance of the upper non-immersed part from the slag line is not sufficient, and if the oxidation proceeds to the inside, Oxidation may occur up to molybdenum and zirconia tubes. As a result, the mechanical strength of the oxidized portion is remarkably deteriorated and the portion is easily broken. In addition, since the mechanical strength of the protective sleeve is relatively low, the molybdenum / zirconia pipe breaks at the stress-concentrated part in the vicinity of the screwed part with the fixing bracket due to vibration and mechanical stress during operation. There is also a problem.
JP-A-8-271347

  The problem to be solved is to increase the oxidation resistance of the non-immersed part of the molten metal temperature probe and to increase the mechanical strength of the neck of the molten metal temperature probe, thereby extending the service life of the molten metal temperature probe. It is to become.

  A temperature measuring probe for a molten metal according to claim 1 for solving the above-mentioned problems, an alumina protective tube containing a thermocouple is inserted into a high melting point protective tube, and a bottomed tip of the high melting point protective tube is inserted. The outer periphery is protected by a fireproof protective sleeve, and the outer cap-shaped tube portion is covered from the base end of the fireproof protective sleeve, and the inner tube portion is screwed to the outer periphery of the base end portion of the high melting point protective tube. In the molten metal temperature measurement probe comprising the fixed metal fitting, the molten metal immersion portion of the fireproof protective sleeve is made of ceramic / carbon-based refractory such as alumina / carbon-based, which gives priority to molten metal and slag. The non-immersed part from the molten metal immersion part to the base end part was formed with ceramics and carbon-based refractories such as alumina and carbon, giving priority to oxidation resistance and mechanical strength. To.

  Moreover, the molten metal temperature-measurement probe according to claim 2 is the configuration according to claim 1, wherein the lower end portion of the cap-shaped cylindrical portion of the fixing bracket is provided on the outer periphery of the base end portion of the non-immersed portion of the fireproof protective sleeve. And a capable refractory having better oxidation resistance and strength than the fireproof protective sleeve is filled from the base end portion of the non-immersed portion to the inside of the cap-shaped tube portion.

  According to the temperature measuring probe for molten metal according to claim 1, the molten metal immersion portion of the refractory protective sleeve is made of ceramic / carbon-based refractory such as alumina / carbon-based which gives priority to melting resistance against molten metal and slag. Because the non-immersed part from the molten metal immersion part to the base end part is made of ceramics and carbon refractories such as alumina and carbon, giving priority to oxidation resistance and mechanical strength, from the slag line The oxidation resistance of the upper non-immersed portion is ensured, and the function of covering the internal high melting point protective tube with airtightness is maintained, so that the high melting point protective tube can be prevented from being oxidized and broken.

  According to the temperature measuring probe for molten metal according to claim 2, the base end portion of the cap-shaped cylindrical portion of the fixing bracket is covered with the outer periphery of the base end portion of the non-immersed portion of the fireproof protective sleeve, and the base end portion of the non-immersed portion Since the inside of the cap-shaped tube part from the top to the top is filled with a castable refractory that is more resistant to oxidation and strength than the fire-resistant protective sleeve, the oxidation resistance of the non-immersed part from the slag line to the upper part is higher than that of the protective sleeve. It is possible to prevent the internal high melting point protective tube from being oxidized and broken. In addition, because it is protected by a castable refractory with excellent strength, the high melting point protective tube breaks in the vicinity of the threaded part with the fixing bracket, particularly at the stress concentration part, due to vibration and mechanical stress during operation. Occurrence can be prevented.

  The purpose is to increase the oxidation resistance of the non-immersed part of the molten metal temperature probe and to increase the mechanical strength of the neck of the molten metal temperature probe to prolong the service life of the molten metal temperature probe. The non-immersed part from the part to the base end part should be made of ceramics and carbon-based refractories such as alumina and carbon based on oxidation resistance and mechanical strength, and the non-immersed part of the fire-resistant protective sleeve This was realized by filling the inside of the cap-shaped cylindrical portion from the base end to a castable refractory material that was more resistant to oxidation and strength than the fireproof protective sleeve.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of a molten metal temperature measuring probe (hereinafter referred to as a temperature measuring probe) 1 according to the first embodiment. The body portion of the temperature measuring probe 1 is composed of a bottomed ceramic protective tube 2 made of alumina, silicon nitrogen or the like with a built-in thermocouple, a bottomed high melting point protective tube 3, a fireproof protective sleeve 4 and the like. . The ceramic protective tube 2 is inserted into the high melting point protective tube 3 from the bottomed portion.

  A male screw 3 a is formed at the base end of the high melting point protective tube 3. In this embodiment, a molybdenum zirconia cermet tube having a high melting point, a very high thermal conductivity, and chemically stable at a high temperature is used as the high melting point protective tube 3. A high-melting point protective tube (hereinafter referred to as a molybdenum / zirconia tube) 3 is fitted with a fireproof protective sleeve 4 on the outer periphery excluding the bottomed end portion.

  The molten metal immersion portion 5 of the fireproof protective sleeve 4 is formed of a ceramic / carbon refractory material such as alumina / carbon based on molten metal and slag giving priority to the melting resistance, and from the molten metal immersion portion to the base end portion. The non-immersed portion 6 is formed of a ceramic / carbon refractory material such as alumina / carbon based on which oxidation resistance and mechanical strength are prioritized. As for the molten metal immersion part 5, in addition to alumina / graphite, those made of magnesia / graphite, zirconia / graphite, spinel / graphite, etc. are also used.

  A fixture 11 is attached to the main body portion of the temperature measuring probe 1 having the above-described configuration. The fixing bracket 11 has a lower end formed in a double cylinder structure, and covers the outer cap-shaped cylinder part 12 on the base end part 6 a of the non-immersed part 6 of the fireproof protective sleeve 4 and the inner cylinder part 13. The female screw 13 a formed in the above is screwed into the male screw 3 a formed at the base end of the molybdenum / zirconia tube 3. A cap body 15 is formed on the outer periphery of the cylindrical portion 14 extended upward from the inner cylindrical portion 13.

  The outer periphery of the cylindrical portion 14 is covered with a heat insulating material 16, and the heat insulating material 16 is also filled inside the cap body 15. The upper end of the cylindrical portion 14 is sealed by fitting a terminal block 17, and a thermocouple conductor inserted into the ceramic protective tube 2 extended to the upper end portion of the cylindrical portion 14 is connected to the terminal block 17, To the compensation conductor.

  According to the temperature measuring probe 1 having the above-described configuration, the molten metal immersion portion 5 of the fireproof protective sleeve 4 is made of a ceramic / carbon-based refractory material such as alumina / carbon-based which gives priority to the melt resistance against molten metal and slag. The non-immersed part 6 from the molten metal immersion part to the base end part is formed of ceramics / carbon refractories such as alumina / carbon type with priority on oxidation resistance and mechanical strength. The oxidation resistance of the non-immersed portion 6 is ensured, and the airtightness and mechanical strength to be shielded from the surrounding oxidizing atmosphere are maintained. Accordingly, it is possible to prevent the internal molybdenum / zirconia tube 3 from being broken by being oxidized and becoming brittle. Thereby, the mechanical strength of the temperature measuring probe 1 itself, particularly against bending stress, can be improved.

  FIG. 2 is a cross-sectional view of the temperature measuring probe 21 according to the second embodiment. Since the basic configuration of the temperature measuring probe 21 is the same as that of the temperature measuring probe 1 of the first embodiment, the same components are denoted by the same reference numerals and detailed description thereof is omitted. The temperature measuring probe 21 covers the outer periphery of the base end portion 6 a of the non-immersed portion 6 of the fireproof protective sleeve 4 and covers the lower end portion of the cap-shaped cylindrical portion 12 of the fixing bracket 11 and from the base end portion 6 a of the non-immersed portion 6. The point that the castable refractory 22 having higher oxidation resistance and strength than the fireproof protective sleeve 4 is filled in the upper cap-shaped cylindrical portion 12 is different from the configuration of the temperature measuring probe 1.

  FIG. 3 is an explanatory view showing a breakage experiment method for the molybdenum / zirconia tube 3 of the temperature measuring probe 21. The ceramic protective tube 2 is extracted from the temperature measuring probe 21 and the heat insulating material 16 is removed. The upper end portion of the cylindrical portion 14 of the temperature measuring probe 21 is fixed and suspended, and a horizontal load F is applied to a substantially intermediate position of the fireproof protective sleeve 4.

  4 (a) to 4 (d) show materials subjected to the above breakage experiment, (a) to (c) show conventional examples, and (d) shows Example 2. FIG. is there. In each conventional example, the length of the cap-shaped cylindrical portion 12 of the fixing metal 11 is changed. The length of the cap-shaped cylinder part 12 is made the same in the conventional example (c) and Example 2. In each of the conventional examples, when the horizontal load F was approximately 135 kg, the molybdenum / zirconia pipe 3 was broken at the lower end portion of the cylindrical portion 13 of the fixture 11. On the other hand, the thing of Example 2 was not broken when the horizontal load F was about 240 kg.

  In the temperature measuring probe 21 of the second embodiment, the outer end of the base end portion 7 a of the non-immersed portion 6 of the fireproof protective sleeve 4 is covered with the lower end portion of the cap-shaped cylindrical portion 12 of the fixing bracket 11. Since the castable refractory 22 having higher oxidation resistance and strength than the fireproof protective sleeve 4 is filled into the upper cap-shaped cylindrical portion 12 from the end portion 6a, the oxidation resistance of the upper non-immersed portion 6 from the slag line is filled. Thus, the airtightness and mechanical strength to be shielded from the surrounding oxidizing atmosphere are maintained at a higher level than in the case of the first embodiment. Accordingly, it is possible to more reliably suppress the oxidation and weakening of the molybdenum / zirconia pipe 3 inside, and to reliably prevent the molybdenum / zirconia pipe 3 from being broken. Furthermore, it is possible to prevent the occurrence of inconvenience that the molybdenum / zirconia tube 3 breaks at a stress concentration portion in the vicinity of the screwed portion with the fixing bracket 11 due to vibration or mechanical stress during operation.

  As the material of the high melting point protective tube 3, in addition to the molybdenum / zirconia tube 3, a metal such as Inconel or stainless steel having a melting point higher than the molten metal to be immersed, or a ceramic such as silicon nitride can be used.

It is sectional drawing of the temperature measuring probe for molten metal which concerns on Example 1 of this invention. It is sectional drawing of the temperature measuring probe for molten metals which concerns on Example 2 same as the above. It is explanatory drawing which showed the fracture experiment method. It is explanatory drawing which showed the fracture experiment sample.

Explanation of symbols

1,21 ... Temperature probe 2.Ceramic protection tube 3.Molybdenum / zirconia tube (high melting point protection tube)
4 ... Fire-resistant protective sleeve 5 ... Molten metal immersion part 6 ... Non-immersion part 6a ... Base end part 11 ... Fixing bracket 12 ... Cap-shaped cylinder part 13 ... Inner cylinder Part 22 ... Castable refractories

Claims (2)

Insert an alumina protective tube with a built-in thermocouple into the high-melting point protective tube, and protect the outer periphery of the high-melting point protective tube except the bottomed end with a fire-resistant protective sleeve, and from the base end of the fire-resistant protective sleeve In the temperature measuring probe for molten metal, which is covered with an outer cap-shaped tube portion and is composed of a fixing fitting in which the inner tube portion is screwed to the outer periphery of the base end portion of the high melting point protective tube,
The molten metal immersion portion of the fireproof protective sleeve is formed of a ceramic / carbon refractory such as alumina / carbon based on molten metal, slag giving priority to erosion resistance,
The non-immersed part from the molten metal immersion part to the base end part is made of a ceramic / carbon refractory material such as alumina / carbon type with priority given to oxidation resistance and mechanical strength. .   Covering the outer periphery of the base end portion of the non-immersed portion of the fireproof protective sleeve with the lower end of the cap-shaped tube portion of the fixing bracket, and inside the cap-shaped tube portion at the upper part from the base end portion of the non-immersed portion, The temperature measuring probe for molten metal according to claim 1, which is filled with a castable refractory having superior oxidation resistance and strength than the fireproof protective sleeve.

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