JP2763719B2 - Flow velocity / flow direction detector in the level detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring the level and flow rate of molten metal poured or filled into a container, and more particularly, to detecting the buoyancy of a float from molten metal and based on the detected buoyancy. The present invention relates to a flow velocity / flow direction detecting device for calculating a molten metal level and a flow vector.

[0002]

2. Description of the Related Art An apparatus for detecting a molten metal level utilizing the buoyancy of a float of a molten metal injected or filled into a container is disclosed in, for example, Japanese Patent Application Laid-Open No. 49-106436 and Japanese Utility Model Application Laid-Open No. 49-52563.
This technique is already known in Japanese Unexamined Patent Publication (Kokai) No., "Pressure / Vacuum / Level Measurement" (published by Nikkan Kogyo Shimbun, published on May 31, 1965, Kogyo Keizai Gijutsu 4, p. 359). In the detection method described in the above publications, the level of the molten metal is detected from the amount of movement of the float floating on the object to be detected or by converting the amount of movement due to the difference between the weight of the float and the buoyancy into an electrical signal. . These are applied to water level measurement and the like, particularly liquid level measurement of rectified liquid, and there are many practical examples.

[0003]

In the above-mentioned apparatus for detecting the molten metal level of a floating type molten metal, in particular, the molten metal molten metal in a mold is continuously cast by continuously pouring the molten metal into a container and pulling out a solidified slab from a lower portion of the container. When measuring the surface, it is inevitable that slag or molten metal adheres to and solidifies on the float and grows with time. That is, in addition to the occurrence of measurement error due to the weight fluctuation of the float, the float moves up and down freely to follow the surface of the molten metal. . Further, there is no device for compensating for the lateral force (dynamic pressure) applied to the float, and it is difficult to reliably and accurately detect the molten metal surface. In the apparatus described in JP-A-49-106436, the float material is simply a refractory material, but in addition to the prevention of growth of deposited metal, the durability at high temperatures, and the buoyancy in the measurement of turbulent liquid level. It is easy to receive external force, and good detection performance cannot be obtained, and improvement of detection accuracy has been a major problem.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an improved buoyancy type measuring apparatus which can solve the above-mentioned drawbacks and can accurately measure the flow velocity and flow direction as well as the molten metal level.

[0005]

SUMMARY OF THE INVENTION According to the present invention, a hollow cylindrical rod made of a heat-resistant ceramic is closed at one end and a pressure sensor is provided at the other end. A measuring device comprising: a pressure detecting unit for detecting an external pressure; an arithmetic processor for amplifying a detection signal from the pressure detecting unit, correcting a level based on a density of a material to be detected, and calculating a flow velocity and a flow direction (flow vector). It is. The hollow cylindrical rod is mainly composed of boron nitride, which eliminates the adhesion of metal and the like.Also, to reduce the initial stress release and increase the resistance of the force applied to the pressure transmission rod in the lateral direction, the pressure near the maximum allowable pressure The structure is such that the initial pressure of the sensor can be set. A plurality of pressure sensors are provided on the detection surface of the external pressure, a level signal for compensating for the partial pressure is obtained by addition processing of the sensor outputs, and a vector sum calculation of each sensor output is performed. By compensating for the flow rate of the object
Enables azimuth detection.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the embodiments shown in the drawings. FIG. 1 is a diagram showing a configuration of a molten metal flow velocity / flow direction detecting device according to one embodiment of the present invention. FIG. 2A is a detailed sectional view of a pressing detection unit, and FIG.
(A) It is DD sectional drawing of a figure. E is the pressure sensor S
_i , a pressure detecting unit composed of an initial stress adjusting unit F, a hollow cylindrical bar K, etc., A is a supporting arm for supporting and fixing the pressing detecting unit E, K is a hollow cylindrical bar transmitting buoyancy (pressing), B
Is an arithmetic processing unit that amplifies the signal from the pressure sensor and outputs the molten steel level L, the flow velocity υ, and the azimuth θ. C is the molten steel filled in the mold M. Support arm A on top of mold M
The press detection unit E fixed installed, adjusts the output of the pressure sensor S _1, S _2, S ₃ in a state where pre hollow cylinder rod K is not侵積molten steel C. It is a known technique to use a semiconductor sensor or a wire strain gauge as the pressure sensor and to perform output balance adjustment by a Wheatstone bridge circuit. The buoyancy F received by the hollow cylindrical rod K when immersed in the molten steel C or when the molten metal surface rises can be expressed by the following equation (1).

F = ρSL (1) ρ: density of liquid [g / cm ³ ] S: cross-sectional area of float [cm ² ] L: length of float in liquid [cm] Here, spring In the case where the float is suspended for example, the difference between the float weight W and the buoyancy F, that is, the apparent float weight (W
−F) decreases and the float floats, so that the level of the molten metal can be measured from the amount of movement. However, in the present invention, a pressure sensor provided on the fixed side and a pressure support plate provided at the end of the hollow cylindrical rod with a spring with a bushing are previously tightened to the maximum allowable range of the pressure sensor. As a result, the lateral drag applied to the hollow cylindrical rod K can be increased to eliminate uneven pressing, and the float does not seem to move up and down apparently, so that the molten steel can be prevented from being entangled and wobble, and stable buoyancy detection can be achieved. Becomes possible. As shown in FIG.
The pressure support plate 10 fixed to the other end of the hollow cylindrical rod K has pressure sensors S ₁ , S ₂ , and S ₃ on the fixed lower surface in the circumferential direction 12.
It is arranged and supported at intervals of 0 °, and is firmly mounted at three initial stress adjusting portions F corresponding to the sensors.

FIG. 3 shows a structural view of the stress adjusting section F. FIG.
F ₁ is adjustment screw, F ₂ is the spring, F ₃ is a bushing, with only the spring F ₂ friction coefficient at the wall resulting bending by compression is to issue change in. Therefore can reduce friction of the side wall surface with respect to the expansion and contraction of the spring F ₂ by the addition of bushings F _3, stable performance is extremely effective means obtained. The pressure sensors S ₁ , S ₂ , and S ₃ are adjusted with the pressure adjusting screw F ₁ so that equal pressure is applied to the pressure sensors S ₁ , S ₂ , and S ₃ via the pressure support plate 10. Press detection unit E is DD
It has a structure that can be divided in cross section, and is fitted and fixed with bolts 11. Water supply ports G ₁₁ and G ₁₂ and drain ports G ₂₁ and G ₂₂ are provided for cooling, so that the detection unit E is maintained at a constant temperature. Reference numeral 12 denotes a screw hole for fixing the stress adjusting portion F to the support arm A. FIG. 2B is a plan view showing the installation state of the pressure sensors, and the pressure sensors S ₁ , S ₂ ,
S3 is provided _three every 120 degrees, 13 is a groove for taking out the lead wire of the pressure sensor, and the lead wire is taken out from this groove to the outside. Reference numeral 11-1 denotes a screw hole for the bolt 11, which is used to fit and fix the upper and lower portions of the pressure detecting portion E. The hollow cylindrical rod K is preferably made of a heat-resistant ceramic such as alumina graphite, silicon nitride, and silica. Although they are used, according to the inventors, from the viewpoint of wettability and durability,
In particular, the best result was obtained by sintering after normal pressure molding with boron nitride as a main component.

FIG. 4 shows the functions of the arithmetic processing unit B. A plurality of pressure sensors, three in this embodiment, are provided.
As shown in (b), the signals of the pressure sensors installed at every 120 degrees are the signals of the Wheatstone bridge circuit 1a,
1b, 1c, and outputs a DC signal corresponding to the pressing force. Reference numeral 2 denotes an adder which outputs an added value of the outputs from the respective sensors. 6 is a gain adjuster for correcting the density of the fluid, 3 is a vector sum calculator, 4 is a liquid level converter, and 5 is a flow rate calculator. 4, the initial stress adjusting screw F ₁ in a state in which the hollow cylindrical bar K is not immersed in the liquid had been set so that the pressure equally to each sensor is applied, Wheatstone bridge circuit 1a, 1b, 1c Zero adjustment of. Next, the hollow cylindrical rod K is immersed in the liquid, and an output signal corresponding to the buoyancy is obtained from each pressure sensor, added by the adder 2, further converted into the immersion depth by the level converter 4, and the level signal is output. It goes without saying that a gain corresponding to the liquid density is set in advance by the gain adjustment 6. The signal from the pressure sensor can be represented as a vector quantity which is a voltage output at each 120-degree point. Therefore, the flow direction and velocity of the liquid can be known by taking the vector sum of the three pressure sensors. The signal from each pressure sensor is a vector sum calculator 3
Is calculated, and as a result, the vector shown in FIG. 5 is obtained. In FIG. 5, each pressure sensor S ₁ , S
_2, VS ₁ S ₃ output voltages respectively, VS _2, VS ₃
Then VS ₀ is obtained as the sum of the vectors,
Here Taking reference to the VS ₁ - [theta] [degrees] force VS ₀ in direction will be applied to the hollow cylindrical bar K can see the flow from the result + theta [degrees] direction.

On the other hand, VS ₀ changes depending on the immersion depth of the hollow cylindrical rod K and the dynamic pressure. The amount of change may be calculated the velocity υ [cm / sec] from the equation (2) based on (corresponding to VS ₀₎ the force f acting on an object placed in a liquid of density ρ flowing at a flow rate upsilon .

Υ = √ (2fg / sρC _d ) (2) s: cross-sectional area of hollow cylindrical rod in liquid [cm ² ] C _d : experimental coefficient [cm / sec ² ] ρ: liquid Density [g / cm ³ ] g: Gravitational acceleration [cm / sec ² ] Here, in order to obtain an experimental coefficient C _d (absolute number),
Traveling on a traveling carriage equipped with a detector, the equivalent of liquid
The unknown C _d is obtained by obtaining the flow velocity and the immersion depth.
It was derived from equation (2). In online measurement
Flow velocity calculation using the derived C _d value to execute equation (2)
VS _o (fluid force) and liquid level signal are input to the vessel 5, and the flow velocity value
Get. In this embodiment, the liquid level is sequentially detected and the level is detected.
These arithmetic processes for correcting the dust velocity by the bell signal can be easily realized by using a micro computer. Incidentally in the embodiment was used three pressure sensors, by increasing further
An improvement in detection accuracy can be expected.

FIG. 6 is a chart showing the output of each pressure sensor and the added output (liquid level) by immersing the hollow cylindrical rod K in the liquid at a certain depth and oscillating the liquid. As is clear from the figure, the added output always shows a constant level even when the dynamic pressure changes due to the swing. For example, looking at the behavior of the intersections a, b, and c with the Z axis in the figure, the amplitude value and the phase are different, but the addition output, the so-called liquid level, is constant. The force due to the flow of the liquid, that is, the fluid force (dynamic pressure change) is transmitted to each pressure sensor via the immersion rod and is output superimposed on the buoyancy value. However, only the level information can be obtained by the addition operation. Since each sensor is calibrated for its level, it is possible to extract the fluid component by subtracting the buoyancy value from each sensor output obtained sequentially. As a result, in addition to the flow velocity calculation based only on the flow force information, the flow velocity correction based on the immersion rod depth information is realized, so that the flow velocity can be measured accurately. FIG. 7 is a diagram showing a result of measuring the molten metal level in the present embodiment. The X-axis shows the molten steel surface and the Y-axis shows the relative value of the sensor output.
Flow direction measurement was realized with a simple device configuration.

[0013]

As described above, according to the present invention, a simple apparatus configuration is used to realize a level measurement that eliminates partial pressure by simply inserting and immersing a hollow cylindrical rod in an object to be detected as necessary. By adding a simple signal processor, the flow velocity and flow direction can be measured. Since dynamic pressure is usually generated in an actual process line, the applicable range of the conventional buoyancy method is limited, and in such an environment, there are many problems and there is no practical application. In recent years, the miniaturization of the mold has progressed,
At present, it has been abandoned because it is difficult to install other conventional electromagnetic gauges, radiation gauges and the like in terms of size and structure. According to the present invention, these drawbacks can be solved, and can be easily applied and new information on flow velocity and flow direction can be obtained. Therefore, the present invention greatly contributes to the management index of the slab quality of the continuous casting process or to stabilize the operation. The effect is great.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a molten steel flow velocity / flow direction detection device according to an embodiment of the present invention.

2A is a detailed cross-sectional view of a pressure detecting unit E shown in FIG. 1, and FIG. 2B is a cross-sectional view taken along a line DD in FIG.

FIG. 3 is a cross-sectional view showing a structure of an initial stress adjusting unit F shown in FIG.

FIG. 4 is a block diagram illustrating a configuration of an arithmetic processing unit B illustrated in FIG. 1;

FIG. 5 shows the pressure sensors S ₁ , S ₂ , S shown in FIG.
Sum operation result of the output of ₃ is a vector diagram showing a.

FIG. 6 is a graph showing output behavior and added output of each pressure sensor in the embodiment shown in FIG.

FIG. 7 is a graph showing a result of measuring a molten metal level according to the embodiment shown in FIG. 1;

[Explanation of symbols]

S ₁ , S ₂ , S ₃ : Pressure sensors 1a, 1b, 1c: Wheatstone bridge 2: Adder 3: Vector sum calculator 4: Fluid level converter 5: Flow velocity calculator 6: Gain adjuster 10: Pressure support plate 11: bolt 13: lead wire grooves A: supporting arm B: processing unit C: molten steel E: press detection unit F: pressure regulator G _11, G _12: water inlet G _21, G _22: water outlet K: hollow cylinder Rod M: Mold

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01F 23 / 60,1 / 30 G01P 5 / 02,13 / 02 B22D 46/00

Claims (2)

(57) [Claims] An apparatus for detecting a level of a molten metal from a sum of outputs of respective sensors provided with a plurality of sensors for detecting a pressing force due to buoyancy transmitted by a heat-resistant ceramic hollow cylindrical bar immersed in a molten metal. put the molten metal surface level detection device characterized in that it is an arithmetic unit and the arithmetic unit outputs to perform the vector sum operation of the respective sensor output arranged in distance from an arithmetic unit for correcting at bath level level signal
Speed / flow direction detector . Wherein the coil spring and the initial stress adjusting screws provided in pressure-sensitive surface side of the pressure sensor, molten metal surface level according to claim 1, characterized in that configured to reduce the pressure sensor output by the pressing force by buoyant Flow velocity and flow in the detector
Direction detector .