JPH044976Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Purpose of the Invention] (Field of Industrial Application) The present invention relates to a protective tube for a molten metal level sensor.

(Prior Art) In casting molten metal, fluctuations in the level of the molten metal in the mold have an important effect on the quality of the cast billet. For this reason, it is necessary to keep the level of the molten metal constant, and a molten metal level sensor is installed several centimeters away from the surface of the molten metal, but the sensor is installed close to the molten metal. Therefore, the temperature is high, and the sensor itself has no heat resistance, so a ceramic protection tube is used to protect it, and air is sent into the protection tube to cool it.

(Problem that the invention aims to solve) However, with the ceramic protection tube that is the conventional protection method described above, even if air is sent to cool it, the protection tube may crack during use due to thermal stress and burn out the sensor. Furthermore, if the molten metal scatters and adheres to the surface of the protection tube, the temperature of the protection tube will rise, which will be detected by the sensor, and accurate level control may not be possible. Furthermore, it is difficult to scrape off the molten metal adhering to the protective tube, and since ceramic is not strong against impact, the protective tube is likely to be damaged if removed by hammering.

In view of this, the present invention eliminates the problems of the conventional technology by making the inner side a hard ceramic tube and covering the outer periphery with ceramic fiber to create a laminated structure tube, which eliminates the problem of cracking due to thermal stress. It is an object of the present invention to provide a protection tube for a molten metal level sensor that is free from erroneous detection by a sensor.

[Structure of the idea]

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a protection tube for a molten metal level sensor, in which a cylindrical container for protecting the sensor is replaced with a cylindrical body made of hard ceramic inside. The outer periphery of this cylindrical body is coated with ceramic fiber to form a laminated tube structure.

(Function) According to the present invention, the sensor protection cylindrical container in which the sensor is housed has a hard ceramic cylinder on the inside, and the outer periphery of this cylinder is covered with ceramic fiber to form a laminated structure tube. This allows the ceramic fiber on the outer periphery to prevent the ceramic cylinder from cracking due to thermal stress, and even if molten metal scatters and adheres to the ceramic fiber, the ceramic cylinder is connected to the sensor. is provided, so that the sensor does not sense the temperature increase in the cylinder caused by the deposited molten metal.

(Embodiments) The present invention will be described below with reference to embodiments shown in the drawings. FIG. 1 shows a cross section of a protective tube for a molten metal level sensor according to an embodiment of the present invention, and FIG. 2 shows an embodiment of a continuous casting machine using the present invention. In a continuous casting machine, as shown in FIG. 2, molten metal 4 is stored in a tundish 2 of a continuous casting machine 1 via an air seal pipe 3, and the molten metal 4 stored here is passed from an immersion nozzle 5 to a mold 6. The billet 7 is formed by being pulled under the mold 6.
In this case, in order to make the quality of the billet 7 uniform, it is necessary to adjust the level of the molten metal 4 in the mold 6 by operating the slide plate 8 with the hydraulic cylinder 9. In order to detect the hot water level of the metal 4, a level sensor 1 according to the present invention is installed at a position several cm away from the top of the hot water level.
0 is set.

As shown in FIG. 1, the level sensor 10 according to the present invention is constructed by housing a sensor main body 11 in a cylindrical container 12 for protecting the sensor.

The cylindrical container 12 has a laminated tube structure in which the inside is made of a hard ceramic cylinder 13 with a bottom, and a ceramic fiber outer skin 14 is laminated to cover the outer periphery of the cylinder. In this case, when the outer diameter of the cylinder 13 is 30 m/m and the wall thickness is 3 to 5 m/m, the thickness of the ceramic fiber outer skin 14 is about 2 to 5 m/m. The ceramic fiber outer shell 14 can be obtained by vacuum molding, and the cylindrical container 12 can be obtained by fitting it onto the cylindrical body 13.

The embodiment shown in FIG. 1 shows a case where an air cooling means is provided for cooling the sensor main body 11 housed in the cylindrical container 12 with cooling air. This air cooling means passes through a plug 16 that closes the opening of the cylindrical container 12 via a sealing material 15 and communicates with an external cooling air supply source (not shown). Air passages 19 and 20 are formed between an inner cylinder 18 made of a metal tube or the like that is inserted into the vicinity and whose lower end is open, the outer peripheral surface of this inner cylinder 18, and the inner peripheral surface of the cylindrical container 12. An air guide 21 made of a metal tube or the like is fitted to the inner cylinder 18 with a gap therebetween so as to span almost the entire length existing in the cylindrical container 12, and the upper end is firmly supported by the plug 16. configured, plug 16
An air vent hole 22 is provided therethrough.

The sensor main body 11 is attached to the outer periphery near the lower end of the inner cylinder 18.

Since the level sensor 10 according to the present invention is configured as described above, cooling air is introduced from the upper part of the inner cylinder 18 and hits the bottom part 17 of the cylindrical container 12, and the air passages 19, 20
During this time, the sensor body 11 attached to the inner cylinder 18 is cooled and discharged to the outside through the air vent hole 22, so that the sensor body 11 is kept at a temperature that can always maintain the desired performance, for example, 50°C. At the same time, the sensor body 11 is protected from the high temperature of the molten metal 4 by the ceramic fiber outer skin 14 and the cylinder body 13 that constitute the outer periphery of the cylindrical container 12, so that the sensor body 11 can be easily cooled down. There is no sensing, and the cylindrical body 13 is also prevented from cracking due to thermal stress.

In the embodiment described above, the ceramic fiber outer cover of the protection tube for the molten metal level sensor is 2
It is possible to have more than one layer, and it can also be implemented in fields such as non-ferrous metal industry, and is not limited to the above embodiments. Further, the air cooling means for the sensor main body 11 is not limited to the illustrated embodiment, and cooling means other than air cooling may be used.

[Effect of idea]

As explained above, in the present invention, the cylindrical container for protecting the sensor that houses the sensor is made of a laminated structure tube in which a ceramic fiber outer skin is laminated on the outer periphery of a hard ceramic cylindrical body. The outer ceramic fiber skin prevents cracking due to thermal stress, and even if molten metal adheres to the skin, it can be easily removed.
Ceramic fiber has elasticity, so it is easy to insert and attach the ceramic cylinder, and the ceramic fiber outer cover can be easily replaced, so the hard ceramic cylinder and sensor body can be used semi-permanently. It becomes possible. In addition, the ceramic fiber outer cover prevents the sensor from sensing errors due to adhesion of molten metal, so the sensor will not burn out, making it possible to provide a highly reliable level sensor with low maintenance costs. It has the following effects.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a protection tube for a molten metal level sensor according to an embodiment of the present invention, and FIG. 2 is an explanatory diagram showing an embodiment of a continuous casting machine using the present invention. 1... Continuous casting machine, 10... Level sensor, 1
1... Sensor body, 12... Cylindrical container, 13...
Cylindrical body, 14...Outer skin, 15...Sealing material, 16...
... Plug, 18 ... Inner cylinder, 19, 20 ... Air passage, 21 ... Air guide, 22 ... Air vent hole.

Claims (1)

[Scope of utility model registration request] In a protection tube for a level sensor of molten metal, the cylindrical container for protecting the sensor that houses the sensor has a hard ceramic cylinder on the inside, and the outer periphery of this cylinder is covered with ceramic fiber to form a laminated structure tube. A protection tube for a molten metal level sensor.