JPS58210522A - Equipment for measuring molten metal level - Google Patents

Abstract

PURPOSE:To measure exactly a molten metal level by conducting the constant current to the molten metal through a conductive wire rod and measuring a voltage between a suitable part position of the wire rod and a point of substantially of equipotential to the molten metal. CONSTITUTION:The wire 14 is inserted into the molten steel 11 at constant velocity while holding exactly the contact with two electrodes 17, 18 at an electrode part 122. A positive pole and a negative pole of a constant electric current source 19 are connected to the electrode 17 and the part e.g. a mold 10 of substantially equipotential to the steel 11 respectively. One terminal and the other terminal of a voltage measuring circuit 20 are connected to the electrode 18 and a connection point 21 of the source 19 and the mold 10 respectively. Denoted the resistance value of the wire 14 as (x), current value as I and measured value of the circuit 20 as E, x=E/I is satisfied. Since (x) is proportional to the length from the electrode 18 of the wire 14 to the surface of the molten steel bath and an electric current I is constant, the measured value E is the value giving the molten steel level, and the influence of variation of the contact resistance is prevented, the exact measurement can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for measuring the level of molten metal in containers containing molten metal, such as molds of continuous casting machines.

Controlling the molten steel level in the mold to a constant level is extremely important for stable continuous casting machine operation and stabilizing quality, and for this purpose, it is essential to measure the level. Generally, radiation is used to measure the level, but this is not preferable in terms of work safety, so methods that use eddy current, microwaves, a thermometer, or similar to the present invention, A device has been developed that detects level fluctuations by feeding a wire into molten steel and measuring the change in resistance up to the surface of the molten steel.

The continuous casting hot water level detection device according to Japanese Patent Publication No. 55-46268, as indicated in its claims, ``During detection, a wire is continuously sent to the hot water surface, electricity of a constant voltage is passed through the wire, The abstract is ``a metal level detection device for continuous casting that controls the height of the metal surface by detecting the current value due to the change in electrical resistance due to the change in the length of the wire between the fixed power supply point and the metal surface.'' However, when using this device, the influence of the contact resistance at the feeding point with respect to the wire is large, and the contact resistance also fluctuates, making it impossible to obtain sufficient measurement accuracy.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a highly accurate molten metal level measuring device that eliminates the factors that reduce measurement accuracy as described above.

The Kibatsu 131J will be described in detail below based on drawings showing examples thereof. FIG. 1 is a schematic diagram showing the overall configuration of the apparatus of the present invention.

The mold of a 10-piece continuous casting machine is shown. Molten #411 is injected from the upper tundish (not shown), while it exits from the mold 10 in the form of unsolidified slabs from the lower side, and is passed through the pinch rolls (not shown). During the extraction process, it undergoes the necessary cooling and solidifies.

A wire guide part 12 is fixed to the part where the sliding nozzle (not shown) hanging down from the tundish is removed, and the wire 14 fed out from the wire supply cap 13 passes through this guide part 12 and enters the molten steel. It is inserted almost vertically.

Wire supply unit 131/'i Wire drum 131 wound with wire 14, pinch roll 132 for taking out wire 141Pc, motor 133 for driving pinch roll, motor 1
Gear group 13 that transmits deceleration from 33 to pinch roll 132
A switch 16 is interposed between the motor 133 and the driving power source 15. The power supply 15 is provided with a speed regulating circuit, and by running the motor 133 at a set speed, the pinch roll 132 is moved at a corresponding speed [ff1l>, and the wire 14 is inserted into the molten steel 11 at a constant speed. It will be done. Needless to say, the wire 14 melts immediately within the molten steel 11. The wire 14 is preferably one that has little effect even if melted into molten steel and has high resistance.
Generally, it is best to use straight stainless steel.

The wire guide section 12 consists of a beak section 121 and an electrode section 122 for stably sending out the wire 14, and both may be configured as an integral structure as shown in the figure, or both may be configured as separate bodies.
A configuration may also be adopted in which both are connected by a flexible tube.

In the electrode part 122, there are two
Two electric wires w1.17.18 are installed opposite each other, and wire 14
Both electrodes 17 are biased by a spring or the like toward the passage area of
．． 18 and the wire 14 are ensured to be in contact with each other. Further, the parts other than the contact between the electrode 17 and the electrode 18 and the wire 14 are electrically insulated with an insulator.

The electrode 17Fi is connected to the positive electrode of the constant current power source 19.

The negative electrode of the constant current power supply 19 is connected to the molten steel 1 in the mold IO.
In other words, it is connected to a portion that is electrically conductive to the molten steel 11, in other words, a portion that has substantially the same potential as the molten steel 11, for example, a mold frame. The electrode 18I'i is connected to one end of a voltage measurement circuit 20, and the other end of the voltage measurement circuit 20 is connected to a connection point 21 between the constant current power supply 19 and the mold 10.

Now, if we use 5US304 straight wire of 1.0'm, the standard distance from the electric TFI17, 18 to the molten steel surface is 200m, and the current from the constant current power supply 19 is IA, the electrode The voltage between 18 and connection point 21 is 0.15 to 0.15, assuming the molten steel level measurement range is ±50+m.
The voltage is about 0.25V, and the voltage measurement circuit 20 is capable of measuring voltages in this range with high precision. A low-pass filter with a variable cut-off frequency is provided in the voltage measurement circuit 20 to eliminate fluctuations in the measured voltage due to short-term fluctuations in the molten metal level, thereby preventing control based on instantaneous molten steel levels. There is.

FIG. 2 is an equivalent circuit diagram of the measurement system of the device of the present invention. The value of the current flowing from Saddenura and power supply 19 is ■.

The contact resistance between the electrode 17 connected to the positive electrode and the wire 14 is r2, and the resistance for energizing the wire 14 (constant current voltage, wiring from 19 positive wire to electric wire 4fi17 and connection point 21
The resistance of the wiring from to the negative electrode of the constant current power supply 19) is set as r,
Furthermore, the current flowing through the voltage measuring circuit 20 side is It, the contact resistance of the electrode 18 is r;, and the other resistance on the circuit 20 side (mainly the internal resistance of the circuit 20) is ry. Furthermore, the current flowing through the wire 14 is Ix, and its resistance (electrode 1
Let X be the resistance from 8 to the final steel surface (more precisely, the resistance up to the connection point 21). Then, 1 = Ix + IE (1), and the internal resistance ry of the voltage measurement circuit 20 is extremely large, that is, fv-)-f2-b00n>x=
・Since (2) is O in IE and IX in I, measurement of voltage measurement circuit 20 @E ke E = IX
@X...(3), so X = E/I...(4).

Since X is a value proportional to the length of the wire 14 from the electrode 18 to the molten steel level, and the current l is constant, the measured value E of the voltage measuring circuit 20 is a value giving the molten steel level.

FIG. 3 is an equivalent circuit diagram of the measurement system of the hot water level detection device disclosed in Japanese Patent Publication No. 55-46268 mentioned above.

The output voltage of the constant voltage power supply 31 is the E1 current (measurement current).
, r2 is the contact resistance between the wire 32 and the contact tube 33 that comes in contact with it, rl is the resistance of the current flow to the wire 32 (internal resistance of the ammeter 34 and resistance of the wiring),
Let the resistance of the wire 32 be X. In this case, I = E/ (x+r++rz) =-
(5), and the resistance X representing the length of the wire or the level of molten steel is as follows.

As is clear from the comparison between equations (4) and (6), the above-mentioned known technology would otherwise be affected by a significant contact resistance r2 of 1fdJ, making accurate measurement impossible, whereas the present invention In this case, there is virtually no shadow M at all.

As described above, according to the present invention, it is possible to accurately measure the level of molten steel, etc. in the mold of a continuous casting machine,
Therefore, the accuracy of level control is improved, and the present invention greatly contributes to the quality of continuous slabs. Note that the present invention is not limited to the level inside the mold, but can also be applied to other molten metal ladles,
It is no secret that it can also be used to measure levels in smelting furnaces, etc.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of the device of the present invention, FIG. 2 is an equivalent circuit diagram of the measurement system, and FIG. 3 is an equivalent circuit diagram of a conventionally known device. 10... Mold 11... Melt #l 14... Wire 17.18... Electrode 19... Constant current power supply 2
0...Voltage measurement circuit patent applicant: Sumitomo Metal Industries Co., Ltd. agent Patent attorney Noboru Kono

Claims (1)

[Claims] l. A means for feeding a conductive wire into the molten metal, a means for passing a constant current through the molten metal through the wire, and a point between an appropriate part of the wire and a point substantially equipotential with the molten metal. 1. A molten metal level measuring device, characterized in that the molten metal level measuring device is characterized in that the molten metal level is determined based on the voltage.