JPH0712904Y2 - Molten metal level detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to an apparatus for measuring the level of molten metal poured or filled in a container. More specifically, the principle of buoyancy from a detected object is used. The present invention relates to a simple molten metal level detection device.

(Prior Art) A molten metal level detection method utilizing the buoyancy of a float of molten metal poured or filled in a container is disclosed in, for example, JP-A-49-106436 and JP-A-49-52563. Vacuum / level measurement "(published by Nikkan Kogyo Shimbun, published May 31, 1965,
This is a technique already known in the field of industrial measurement technology, 4, etc. In the detection method described in the above publication, the molten metal level is detected by converting the movement amount of the float floated on the object to be detected or the movement amount due to the difference between the weight of the float and the buoyancy into an electrical signal. These are the same principles that are usually applied to water level measurement in water tanks, and there are many practical examples.

(Problems to be solved by the invention) In the float type molten metal level detection method, in particular, the molten metal level of a mold in continuous casting is continuously poured into a container and the solidified slab is pulled out from the lower part of the container. When measuring, it is inevitable that slag or molten metal adheres to the float and solidifies and grows over time. That is, in addition to the occurrence of a measurement error due to the fluctuation of the float weight, because of the structure that freely moves up and down so as to follow the surface of the molten metal, it becomes trapped in the molten steel flow with the growth of the adherent metal and measurement becomes impossible. In addition, the change over time is large, and it is difficult to reliably and accurately detect the molten metal surface.

In the method described in JP-A-49-106436, the float material is simply a refractory material, but the growth of the adherent metal is prevented, and the melting loss characteristic (durability) at high temperature affects the detection performance. It has been a big problem from the past.

From the above, the present invention provides an apparatus capable of reliably and accurately detecting the molten metal level, and particularly a simple and improved buoyancy type molten metal level detecting apparatus.

(Means for Solving the Problems) According to the present invention, one end of a heat-resistant ceramic hollow cylindrical rod is closed, a pressure sensor is provided at the other end, and a coil spring and an initial stress adjusting screw are provided on the back surface of the pressure sensor. , A pressure detection unit consisting of a pressure guide mechanism that applies the external pressure transmitted from the hollow cylindrical rod to the pressure sensor surface in the vertical direction, amplification of the detection signal from the pressure detection unit, and the specific gravity of the material to be detected. It is a molten metal molten metal level detection device including a calculation processing unit that performs level correction according to. A plurality of pressure sensors are provided on the external pressure detection surface, and the biased pressure is compensated by the sum-average processing of the sensor output values. The heat-resistant ceramic material of the hollow cylindrical bar contains boron nitride as the main component, and after normal pressure molding It is preferably sintered.

(Operations and Examples) The present invention will be described in detail below based on the illustrated embodiments.

FIG. 1 is a diagram showing the configuration of a molten steel molten metal level detection device according to an embodiment of the present invention, FIG. 2 (a) is a detailed cross-sectional view of a pressure detection portion, and FIG. 2 (b) is C- of FIG. It is C sectional drawing. E is a pressure detection unit including a pressure sensor 1, a hollow cylindrical rod K, a guide mechanism, and the like, A is a support arm for supporting and fixing the pressure detection unit E, and K is a buoyancy force immersed in a solution to be detected (molten steel). Hollow cylindrical rod for transmitting (pressing), 10, 11 and 12 are pressure sensors 1
An amplifier having a zero adjustment function for amplifying the signal from the amplifier, 13 is an arithmetic mean calculator for processing the signals from the amplifiers 10 to 12, and 14
Is a gain adjuster for correcting the specific gravity of the object to be detected, and S is molten steel filled in the mold M.

The pressure detection unit E is fixedly installed on the support arm A above the mold M, and the output of the pressure sensor 1 is adjusted in advance in a state where the hollow cylindrical rod K is not immersed in the molten steel S. The pressure sensor 1 is a semiconductor sensor or a wire strain. It is a known technique to adjust the output balance of the Wheatstone bridge circuit by using a gauge or the like. Further, after the outputs of the amplifiers 10 to 12, in the present embodiment, addition calculation and specific gravity compensation calculation are performed in an analog manner, but this can be easily realized by a computer.

The buoyancy F received by the hollow cylindrical rod K when immersed in the molten steel S or when the molten metal surface rises is expressed by the following equation.

F = ρs1 ρ: Density of liquid s: Cross-sectional area of float 1: Length of float in liquid Here, when the float is suspended by a spring etc., the difference between the weight W of the float and the buoyancy F, that is, the apparent Upper float weight (W
-F) decreases and the float floats, so the molten metal surface can be measured from the amount of movement. However, in the present invention, if the float is supported by the support arm A in advance, and further the initial stress adjustment screw 7 and the coil spring 8 are firmly attached to eliminate the initial stress release of the suspension mechanism of the hollow cylindrical rod, Is a structure that apparently does not occur. Therefore, the inclusion of molten steel can be prevented, and stable buoyancy can be detected.

As shown in FIG. 2A, a through hole is provided in the metal plate 2 fixed to the other end of the hollow cylindrical rod K, and is supported by the support arm A by the bolt 3. Also, the initial stress adjusting screw 7
The pressure sensor 1 is provided so as to be sandwiched between the coil spring 8 and the metal plate 2 provided below. Further, a guide cover 4 is provided so that the hollow cylindrical rod K does not swing to the left and right, and is fixed to the support arm A with fixing bolts 5-1 and 5-2. In addition, ventilation holes 6-1 and 6-2 are provided so that ventilation cooling can be performed from one side. There are heat resistant ceramics such as alumina graphite, silicon nitride, and silica for the hollow cylindrical rod K, but as a result of investigation, it was found that boron nitride is the main component due to its wettability and corrosion resistance characteristics, and ceramics that have been sintered after normal pressure molding are used. Is good.

A plurality of pressure sensors 1 are provided, and as shown in FIG.
Evenly distributed every 120 degrees. By summing and averaging the outputs of each sensor, errors due to unbalanced buoyancy can be reduced.

FIG. 3 is a diagram showing the results of molten metal surface measurement in this embodiment. Although the molten steel level is shown on the x-axis and the relative value of the sensor output is shown on the y-axis, good linear input / output characteristics were obtained, and highly accurate detection was realized with a simple device configuration.

(Advantages of the Invention) As described above, the present invention has a simple device configuration, and the molten metal level measurement can be easily realized simply by inserting and immersing the hollow cylindrical rod into the object to be detected as needed. In recent years, the mold has become smaller in cross section, and it is difficult to install it in the conventional level gauges such as electromagnetic type and radiation type due to its size and structure. The above restrictions have been resolved, the measurement can be performed easily and accurately, and it can also be used as a verification device for conventional level gauges, which greatly contributes to the stable operation of the continuous casting process and the improvement of slab quality. , Its effect is great.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a molten metal surface detection apparatus according to an embodiment of the present invention, FIG. 2 (a) is a detailed cross-sectional view of a pressure detection unit, and FIG. 2 (b) is C- of FIG. C sectional view and FIG. 3 are views showing the molten metal surface measurement result in the present embodiment. 1 ... Pressure sensor, 2 ... Metal plate, 3 ... Bolt, 4 ...
Guide cover, 5 ... Fixing bolt, 6 ... Vent hole, 7 ... Initial stress adjusting screw, 8 ... Coil spring, 10-12 ... Amplifier, 13 ... Addition / averaging calculator, 14 ... Gain adjuster, A ... Support arm, E ... Pressure detection part, K ... Hollow cylindrical rod, M ... Mold, S ... Molten steel.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP 62-33752 (JP, A) JP 57-46121 (JP, A) JP 59-36213 (JP, B2)

Claims (3)

[Scope of utility model registration request] 1. A heat-resistant ceramic hollow cylindrical rod is closed at one end, a pressure sensor is provided at the other end, a coil spring and an initial stress adjusting screw are provided on the back surface of the pressure sensor, and a hollow cylinder is provided against the pressure sensor surface. A pressure detection unit composed of a pressure guide mechanism in which the external pressure transmitted from the rod is applied in the vertical direction, and an arithmetic processing unit that amplifies the detection signal from the pressure detection unit and corrects the level by the specific gravity of the material to be detected. A molten metal level detector composed of and. 2. The molten metal level detecting device according to claim 1, wherein a plurality of pressure sensors are provided on the external pressure detection surface, and the uneven pressure is compensated by sum-average processing of the sensor output values. 3. The molten metal level detecting apparatus according to claim 1, wherein the heat-resistant ceramic material of the hollow cylindrical rod is composed of boron nitride as a main component, and is sintered after pressureless forming.