JP2000035364A - Device for continuous temperature-measurement of melted metal device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the relationship of the thermal resistance of each part and to improve temperature measurement accuracy, for example, by filling at least two kinds of fillers with different thermal conductivity between the sheathing protection tube of a thermocouple temperature-measuring sensor and a ceramic protection tube in separate layers. SOLUTION: A temperature-measuring sensor 1A of a melted metal continuous temperature-measuring device is constituted by filling a filler 13 of a high thermal conductivity such as MoZrO2 powder in a part corresponding to a projecting part from a furnace bottom 14 of sheathing protection tube 9 between a ceramic protection tube 8 and the protection tube 9 and a filler 15 of a low-thermal conductivity such as alumina powder into the remaining part. As a result, thermal resistance from molten metal in the furnace to the temperature measurement point of a thermocouple 6 can be made fully smaller than thermal resistance from the temperature measurement point to the outer wall of the furnace bottom 14. Even if there is a gap between the protection tube 9 and the tip of the ceramic protection tube 8, temperature measurement accuracy scarcely changes since the filler 13 being filled between them has a high thermal conductivity. The sheathing protection tube where tubes with different thermal conductivity are joined may also be constituted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used when continuous temperature control is required, such as when melting at night, and is continuously immersed in a molten metal to measure the temperature of the molten metal continuously. The present invention relates to a continuous molten metal temperature measuring device for heating.

[0002]

2. Description of the Related Art In a foundry, in many cases, melting and pouring operations are performed in parallel, so that the working environment in the factory is a severe environment for workers such as a high-temperature atmosphere, a lot of dust, and a large amount of noise. It is in. One of the solutions is an automatic melting system using night power. Using this system, the cast iron melt required for the next morning can be automatically melted using nighttime power, improving the working environment, improving productivity, reducing power costs, improving safety, and saving labor in production management. Can be done. Therefore, it is necessary to control the temperature continuously, for example, when performing the above-mentioned nighttime melting.

[0003] At this time, the temperature of the melt, such as molten metal and molten slag, in the furnace of a melting furnace (for example, an induction heating furnace used in a nighttime melting system) greatly affects the operation and the quality of the product. It is necessary to measure the temperature continuously and with high accuracy. FIG. 5 is a configuration diagram of a conventional example, and FIG.
FIG. 6B is a vertical sectional view of the temperature sensor shown in FIG. 5, and FIG. 5 and 6, reference numeral 1 denotes a temperature sensor for continuously immersing in the molten metal 2 and continuously measuring the temperature of the molten metal 2, 3 denotes a furnace lid of a melting furnace for melting the molten metal 2, and 4 denotes Insertion holes 5 for immersing the furnace lid 3 in the molten metal 2 through the temperature measuring sensor 1 are provided, and oxides separated from the molten metal 2 or deposits (casting sand and the like) are dissolved and float on the surface of the molten metal 2. 6 is a thermocouple utilizing the fact that a voltage proportional to the temperature of the junction is generated at the other end by joining the tips of two different types of wires of the temperature measuring sensor 1, and 7 is the thermocouple. An insulating tube 8 for inserting the wires of the pair 6 into separate holes to insulate the wires from each other, 8 is a ceramic protective tube for incorporating and protecting the thermocouple 6 and the insulating tube, 9
When the ceramic protective tube 8 is immersed in the molten metal 2,
2 shows an outer protective tube for protecting the slag 5 from the slag 5. 5 and 6, in the temperature measuring sensor 1, a thermocouple 6 whose wires are insulated by inserting respective wires into an insulating tube 7 is inserted into a ceramic protection tube 8, and the outside thereof is further covered with an exterior protection tube 9. It is immersed in the molten metal 2 through an insertion hole 4 formed in the furnace lid 3 of the melting furnace. Then, the temperature of the molten metal 2 is transferred to the thermocouple 6 through the outer protective tube 9 and the ceramic protective tube 8 and is continuously measured.

FIG. 7 shows another configuration of the conventional example. In FIG. 7, the temperature sensor 1 is embedded in the furnace bottom of the crucible 11 of the melting furnace 10 so that the tip of the temperature measuring sensor 1 contacts the molten metal 2. Reference numeral 5 denotes a slag that is separated from and floats on the surface of the molten metal 2, and 12 denotes an induction coil of the melting furnace 10. 7, the sectional configuration of the temperature sensor 1 is shown in FIG.
Therefore, the description is omitted. In FIG. 7, the temperature sensor 1 is buried in the furnace bottom of the crucible 11 of the melting furnace 10 so that the tip thereof contacts the molten metal 2, and the molten metal 2 is wound around the outer periphery of the crucible 11. It is heated and melted by the induction coil 12. Foundry sand adhering to the molten material and slag 5 in which the metal oxide has been dissolved
And float on the surface of the molten metal due to the difference in specific gravity.

[0005] Therefore, in this case, the outer protective tube of the temperature measurement sensor 1 is less likely to be eroded by the slag 5, and there is almost no erosion by the slag 5, so that the temperature can be continuously measured.

[0006]

In general, a 24-hour operation of melting metal such as cast iron at a high temperature or melting at night (using a late-night electric power to melt and maintain a necessary amount of hot water on the next day and sequentially discharge hot water during the daytime) An immersion type temperature sensor that continuously measures the temperature of the melting furnace for producing a casting) must satisfy the following items.

The ability to stably measure a relatively high temperature of a molten metal such as cast iron over a long period of time. The temperature difference between the temperature of the molten metal and the temperature measuring point (the position where the temperature measuring element is located) is small, and the temperature can be measured with high accuracy. In order to prevent the outer protective tube from being eroded by the slag, the outer protective tube must not come into contact with the slag on the molten metal surface.

In order to prevent oxidation of the outer protective tube, the outer protective tube must not be exposed to the atmosphere at high temperatures. In order to measure the temperature of the molten metal accurately, the hot water around the sensor must be sufficiently stirred and have a uniform temperature. Hard to receive mechanical shock such as material input.

A temperature sensor can be easily replaced. In the case of a temperature sensor immersed through the furnace lid, the two conditions that the outer protective tube does not contact the slag on the surface of the molten metal and that the outer protective tube is not exposed to the atmosphere at high temperatures are impossible. It must satisfy that the outer protective tube is not corroded by the slag on the surface of the molten metal and that it does not oxidize at a high temperature, but it is difficult to satisfy both conditions.

In response to these demands, in the conventional configuration, a temperature measuring sensor is buried in the groove such as by providing a groove in the furnace bottom so that the tip sufficiently contacts the molten metal, and the molten metal is always left.
At high temperatures, the outer protective tube is not exposed to the atmosphere, the impact of material input is received at the furnace bottom, so that it does not directly reach the temperature sensor in the groove, or the material of the outer protective tube is made of mechanical strength Mo-Zr with excellent heat resistance and corrosion resistance
O2 is used to endure long-term temperature measurement. However, since the temperature is measured through an outer protective tube, a filler, and a ceramic protective tube, the temperature difference between the molten metal temperature and the measured temperature is low. There are problems that arise.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a continuous molten metal temperature measuring device capable of measuring the temperature of a molten metal with high accuracy.

[0012]

In order to solve the above-mentioned problems, the invention according to claim 1 is a method in which two wires of different types are joined at the tip and the other portion is inserted into separate insulating holes to make a ceramic. A thermocouple temperature sensor installed in a protective tube with a powder filler inside an external protective tube that protects against the erosion of molten metal, and immersed in the molten metal to continuously measure the temperature The filler filled between the outer protective tube and the ceramic protective tube is characterized in that two or more types of fillers having different thermal conductivity are layered and filled.

Considering the temperature from the molten metal to the outer wall of the temperature measuring sensor embedded in the furnace bottom with its tip protruding from the furnace bottom as a simple one-dimensional thermal analysis model (see FIG. 4), the temperature of the molten metal is Tm, and the temperature of the temperature measuring point (thermocouple) T is the outer wall temperature, To is the outer wall temperature, R1 is the thermal resistance between Tm and T, R2 is the thermal resistance between T and To, and Q is the heat flow from the molten metal to the outer wall. QxR1 = Tm-T, QxR2 = T-To,
R1 / R2 = (Tm-T) / (T-To) holds.
From this, in order to reduce Tm-T, R1 << R
Must be 2. This thermal resistance is inversely proportional to the thermal conductivity and the thermal conductive area and is proportional to the distance, but the distance needs a predetermined length to satisfy mechanical strength and the like.

Therefore, the space between the outer protective tube and the ceramic protective tube in the vicinity of the temperature measuring point is filled with a filler having a high thermal conductivity. By filling the filling material at a lower rate, the thermal resistance R1 from the molten metal to the temperature measuring point can be made smaller than that in the case of filling from the vicinity of the temperature measuring point to the outer wall with the same filler. It is possible to further reduce the size as compared with, and to improve the temperature measurement accuracy.

According to a second aspect of the present invention, there is provided a thermocouple temperature sensor in which two different types of wires are joined at the tip and the other portion is inserted into separate insulating holes and housed in a ceramic protective tube. In a continuous molten metal temperature measuring device that is mounted together with a powder filler in an outer protective tube that protects the molten metal from erosion, and is immersed in the molten metal and continuously measures the temperature, the outer protective tube is
It is characterized in that tubes made of materials having different thermal conductivities are joined up and down.

With the above construction, the outer protective tube from the molten metal to the vicinity of the temperature measuring point is made of a material having a high thermal conductivity, and the outer protective tube from the vicinity of the temperature measuring point to the outer wall is made of a material having a low thermal conductivity. The heat resistance R1 from the molten metal to the temperature measuring point is more
It becomes possible to further reduce the thermal resistance R2 from the temperature measuring point to the outer wall, and it is possible to improve the temperature measuring accuracy.

[0017] Further, the invention according to claim 3 is based on claim 2.
In the molten metal continuous temperature measuring device described above, the upper outer protective tube is an outer protective tube having a high thermal conductivity, and the outer protective tube to be joined to the lower portion is thinner than the upper outer protective tube and has a low thermal conductivity. It is characterized by doing. With the above configuration, the upper outer protective tube from the molten metal to the vicinity of the temperature measuring point is formed of a material having a high thermal conductivity, and the lower outer protective tube is formed of a material having a low thermal conductivity in which the thickness of the lower outer protective tube is reduced. The heat resistance R1 from the molten metal to the temperature measuring point can be made smaller than the thermal resistance R2 from the temperature measuring point to the outer wall, as compared with the case where the same material and the same thickness are used for the outer protective tube. Therefore, it becomes possible to improve the temperature measurement accuracy.

[0018]

FIG. 1 shows the structure of a main part of an embodiment of the present invention. FIG. 1 (a) is a cross-sectional view when there is no gap between an outer protective tube and a ceramic protective tube, and FIG. Shows a cross-sectional view when there is a gap between the outer protective tube and the ceramic protective tube. In FIG. 1, members denoted by the same reference numerals as those of the conventional example have approximately the same functions, and therefore description thereof will be omitted. In FIG. 1, reference numeral 6 denotes the temperature sensor 1A.
A thermocouple utilizing the fact that two different types of wires are joined at the other end and a voltage proportional to the temperature of the junction is generated at the other end, and the thermocouple 7 inserts the wires of the thermocouple 6 into separate holes. An insulating tube for insulating the wires between the wires, 8 is a ceramic protecting tube for protecting the thermocouple 6 and the insulating tube in a built-in manner, 9
When the ceramic protective tube 8 is immersed in the molten metal 2,
And an outer protective tube 13 for protecting from the slag 5, especially an outer protective tube 9 between the ceramic protective tube 8 and the outer protective tube 9.
Is filled into a portion corresponding to a portion protruding from the furnace bottom 14 with a high thermal conductivity filler (for example, MoZrO2 or the like);
Reference numeral 5 denotes a low-thermal-conductivity filler (for example, alumina or the like) which fills the remaining portion of the portion between the ceramic protective tube 8 and the outer protective tube 9 which is filled with the high-thermal-conductivity filler 13. In FIG. 1, a temperature measuring sensor 1 </ b> A inserts a thermocouple in which each wire is inserted into an insulating tube 7 and insulated between the wires into a ceramic protection tube 8, and further surrounds the outside with an exterior protection tube 9. A portion between the ceramic protection tube 8 and the exterior protection tube 9, particularly a portion corresponding to a portion where the exterior protection tube 9 protrudes from the furnace bottom 11, is filled with a filler 13 having a high thermal conductivity, and the remaining portion is provided with a low thermal conductivity. And the above-mentioned portion of the outer protective tube 9 is buried so as to protrude from the furnace bottom 14 of the melting furnace. The temperature of the molten metal 2 is transferred to the thermocouple 6 through the outer protective tube 9, the filler 13, and the ceramic protective tube 8, and is continuously measured.

Although FIG. 1B is not preferable, the tip of the ceramic protective tube 8 does not come into contact with the inner wall of the external protective tube and the filler is filled between the protective tube and the actual temperature measuring sensor. FIG. 2 is a cross-sectional view of an example, and the configuration is the same as FIG. In this case, since the filler 13 has a high thermal conductivity, the temperature measurement accuracy hardly changes. However, if the filler 13 has a low thermal conductivity, the accuracy of the temperature measurement may be affected.

FIG. 2 is a block diagram showing a main part of another embodiment of the present invention. In FIG. 2, reference numeral 6 denotes the temperature sensor 1
B is a thermocouple utilizing the fact that the ends of two different types of wires are joined and a voltage proportional to the temperature of the junction is generated at the other end. An insulating tube 8 is provided so as to insulate the wires by inserting the same, a ceramic protection tube 8 is provided for protecting the thermocouple 6 and the insulating tube therein, and 9a is used when the ceramic protection tube 8 is immersed in the molten metal 2. An outer protective tube (for example, MoZrO2 or the like) having an upper high thermal conductivity in which an outer protective tube for protecting the molten metal 2 and the slag 5 is bonded to the upper and lower materials, and 9b is bonded to a lower portion of the upper outer protective tube 9a. An outer protective tube (for example, alumina or the like) having a low thermal conductivity is castable (consisting of a refractory material) for facilitating attachment / detachment from the furnace bottom 14 when the temperature measuring sensor 1B is protruded from the furnace bottom 14 when it is buried. Do).

FIG. 2 is different from FIG. 1 in that the thermal conductivity of the filler filled between the outer protective tube and the ceramic protective tube in order to reduce the thermal resistance between the junction of the thermocouple and the molten metal. Instead of using the height, the outer protective tube is joined in two stages, and a protective tube with high thermal conductivity is arranged on the upper part and a protective tube with low thermal conductivity is arranged on the lower part. FIG. 3 shows a configuration diagram of a main part of another embodiment of the present invention. In FIG. 3, reference numeral 6 denotes a thermocouple using the fact that a voltage proportional to the temperature of the junction is generated at the other end by joining the tips of two different types of wires of the temperature measuring sensor 1C, and 7 is a thermocouple. An insulating tube configured to insulate between the wires by inserting the wires of the thermocouple 6 into separate holes, 8 is a ceramic protection tube that incorporates and protects the thermocouple 6 and the insulating tube, and 9c is the ceramic protection tube. Protective tube 8 is melted 2
An outer protective tube having a high thermal conductivity in which upper and lower outer protective tubes for protecting from the molten metal 2 and the slag 5 when immersed in the upper and lower materials are joined, and 9d is connected to a lower portion of the upper outer protective tube 9c. The outer protective tube 16 is made thinner than the upper outer protective tube 9c and made of a material having a low thermal conductivity. Show castables (comprising refractories) to be filled for ease.

FIG. 3 differs from FIG. 1 in that the thermal conductivity of the filler filled between the outer protective tube and the ceramic protective tube to reduce the thermal resistance between the junction of the thermocouple and the molten metal is reduced. Instead of using the height, the outer protective tube is joined in two steps, and a protective tube with high thermal conductivity is provided at the upper part and a protective tube with low thermal conductivity and thinner than the upper part is arranged at the lower part. Reducing the thickness of the outer protective tube in this way leads to a reduction in the heat conduction area, and the thermal resistance increases accordingly.

In FIGS. 2 and 3, as in the case of FIG. 1, the filler to be filled between the ceramic protective tube and the outer protective tube is made of two types of high and low thermal conductivity, and the upper and lower layers are filled. By doing so, it becomes possible to further improve the temperature measurement accuracy.

[0024]

According to the present invention, the thermal resistance from the molten metal to the temperature measuring point is reduced so that the temperature can be measured with high accuracy. It is possible to operate at a temperature low enough to prevent solidification and to raise the temperature to a predetermined temperature just before tapping, thereby shortening the time during which the refractory of the melting furnace is exposed to high temperatures and extending the life of the refractory. There is.

[Brief description of the drawings]

FIG. 1 shows a configuration of a main part of an embodiment of the present invention,
(A) is a cross-sectional view when there is no gap between the outer protective tube and the ceramic protective tube, and (b) is a cross-sectional view when there is a gap between the outer protective tube and the ceramic protective tube.

FIG. 2 is a configuration diagram of a main part of another embodiment of the present invention.

FIG. 3 is a configuration diagram of a main part of another embodiment of the present invention.

FIG. 4 is a diagram showing a simple one-dimensional thermal analysis model from the molten metal to the outer wall.

FIG. 5 is a configuration diagram of a conventional example.

6A is a cross-sectional configuration diagram of the temperature measurement sensor of FIG. 5,
(B) is a longitudinal sectional configuration diagram of the temperature measurement sensor of FIG. 5.

FIG. 7 is another configuration diagram of a conventional example.

[Explanation of symbols]

 1A, 1B, 1C Temperature sensor 6 Thermocouple 7 Insulation tube 8 Ceramic protection tube 9a, 9b, 9c, 9d Exterior protection tube 13, 15 Filler 14 Furnace wall 16 Castable

Claims (3)

[Claims] 1. A thermocouple sensor that is housed in a ceramic protective tube by joining two different types of wires at the tip and inserting the other part into separate insulating holes to protect the molten metal from erosion by molten metal. In the molten metal continuous temperature measuring device that is mounted together with the powder filler in the outer protective tube and immersed in the molten metal and continuously measures the temperature, the filler to be filled between the outer protective tube and the ceramic protective tube is: A continuous molten metal temperature measuring apparatus characterized in that two or more kinds of fillers having different thermal conductivity are layered and filled. 2. A thermocouple sensor which is housed in a ceramic protective tube by joining two different kinds of wires at the tip and inserting the other portion into separate insulating holes to protect the molten metal from erosion by molten metal. In a continuous molten metal temperature measuring device that is mounted together with a powder filler in an outer protective tube, immersed in molten metal and continuously measures the temperature, the outer protective tube is made by joining pipes of materials with different thermal conductivity up and down. A continuous molten metal temperature measuring device characterized by comprising: 3. The molten metal continuous temperature measuring device according to claim 2, wherein the upper outer protective tube is a high thermal conductivity outer protective tube, and the lower outer protective tube is thinner than the upper outer protective tube. A continuous molten metal temperature measuring device characterized by using an outer protective tube having a low thermal conductivity.