JPH0365845B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for measuring the liquid level of a molten metal in a melting furnace that accommodates molten metal such as aluminum having conductivity.

[Prior art]

Conventionally, the measurement of the liquid level of the molten metal has been carried out as follows, taking advantage of the fact that the molten metal is electrically conductive. That is, a rod-shaped negative electrode is always immersed in the molten metal, and a positive electrode is fixed to the negative electrode so as to be shallowly immersed in the molten metal by a specific length, and the positive electrode and the negative electrode are connected to each other. When the positive electrode is immersed in the molten metal, current flows; however, when the liquid level of the molten metal falls and the positive electrode is away from the liquid level, no current flows. By detecting changes in current, it is possible to measure whether the liquid level is above or below a preset liquid level.

However, in the conventional molten metal liquid level measuring device described above, the positive electrode is fixed and conducts current only when immersed in the molten metal, resulting in the following problems. First of all, it is impossible to measure when the liquid level changes continuously, and only a liquid level with a limited upper and lower limit can be measured. Therefore, when the number of measurement points increases, the number of positive electrodes and detection electric circuits increases by the same number, which complicates the structure and increases cost. Second, the positive electrode is melted and damaged by the molten metal, causing an error in the liquid level measurement results by the amount of melting. To prevent this, periodic inspection or replacement is required. Third, oxides or the like may adhere to the positive electrode, preventing current from flowing and making measurement impossible.

[Problem that the invention seeks to solve]

As mentioned above, the present invention solves various problems that have arisen in conventional molten metal level measuring devices and measuring methods, and is capable of continuously measuring the molten metal level, as well as using scene detection electrodes. The purpose of this invention is to provide a method for measuring the liquid level of molten metal in a melting furnace without melting damage.

[Means for solving problems]

As a result of intensive research into specific means for solving the above-mentioned problems, the present inventors have discovered that the above-mentioned problems can be solved by using the measuring device and measuring method described below, and have devised the present invention. It is completed. That is, the method for measuring the liquid level of molten metal in a melting furnace of the present invention includes: an immersed electrode immersed in the molten metal; a liquid level sensor that is movable up and down on the molten metal liquid surface and is opposite to the immersed electrode; , using a molten metal liquid level measuring device equipped with a current detector that detects the current flowing between the two electrodes and a position detector that detects the position of the vertically movable counter electrode, the immersed electrode is placed in the molten metal. By applying a high voltage to the liquid level sensor and moving it up and down on the liquid surface of the molten metal, a discharge occurs between the liquid level sensor and the molten metal surface, or a current change immediately before the discharge occurs. is detected by the current detector, and the position of the liquid level sensor at that time is detected.

[Function] In the method for measuring the molten metal liquid level in a melting furnace of the present invention, the liquid level sensor is movable up and down on the liquid surface, and there is a gap between the tip of the liquid level sensor and the molten metal liquid surface. By detecting current changes when discharge occurs or just before discharge occurs, continuous measurement of the molten metal level becomes possible. Furthermore, since the liquid level sensor is of a non-contact type that does not come into contact with the molten metal, the liquid level sensor will not be damaged by erosion, allowing highly accurate and long-life measurement.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a schematic diagram of a molten metal level measuring device used in the method of the present invention.

The molten metal liquid level measuring device 1 used in the method of the present invention includes an immersion electrode 2 which is a negative electrode, a liquid level sensor 3 which is a positive electrode, and a position sensor 4.
It includes a drive mechanism 5 and a control calculation circuit 6.

The immersion electrode 2 is formed into a rod shape from a conductive material such as platinum, and is constantly immersed in a molten metal 9 of a light alloy such as aluminum, which is housed in a melting furnace 8.
It is connected to the negative pole of a high-voltage power supply 10 via a resistor 11 and a conducting wire 12 . Branch line 13 branched from conductor 12 between high voltage power supply 10 and resistor 11
An amplifier 14 which is grounded by a conductive wire 12 is connected to the servo amplifier 15 , and a servo amplifier 15 is connected to the amplifier 14 by a conductive wire 12 .

The liquid level sensor 3 is made of a conductive material such as platinum and is formed into a rod shape, and is connected to the positive terminal of the high voltage power source 10 via a resistor 18 with a conductor 12, and is connected to the drive mechanism 5 by moving it upward and downward above the molten metal liquid level 9a. It is now possible to move in any direction. The encoder 4, which is an example of a position sensor, is mounted on a mounting base 19 placed above the molten metal surface 9a to detect the position of the liquid level sensor 3.
The output pulses from are counted by a counter 20.

As shown in FIG. 2, the drive mechanism 5 includes a servo motor 22 and a guide rail 23.
The servo motor 22 is mounted on a mounting base 19 on the lower left side of the encoder 4, and includes a rotary body 25 such as a pulley or sprocket fixed to a rotating shaft 24 of the servo motor 22, and a rotary body 25 of the encoder 4 below the rotary body 25. A winding transmission member 30 of a belt or chain is wound between the small diameter portion of the rotating body 28 of a pulley or sprocket rotatably supported on the mounting base 19 on a vertical line passing through the axis of the rotating shaft 26. ing. Further, the servo motor 22 is
It is connected to a servo amplifier 15 by a conductor 12.

A winding transmission member 33 of a belt or chain is wound between the large diameter portion of the rotating body 28 and a rotating body 32 of a pulley or sprocket fixed to the rotating shaft 26 of the encoder 4. Since the large diameter portion and the rotating body 32 are set to have the same diameter, the left and right sides of the winding transmission member 33 are arranged perpendicularly to the molten metal surface 9a.

The guide rail 23 sandwiches the winding transmission member 33 and connects the winding transmission member 33 to the opposite side of the servo motor.
It is fixed to the mounting base 19 in parallel with both left and right end portions of. A guide bush 38 is slidably inserted into the guide rail 23 and is integrally fixed via an insulator 36 to an electrode support 35 supporting and fixing the liquid level sensor 3.
Bracket 39 integrally formed on the left end of 8
is fixed to the winding transmission member 33.

The control calculation circuit 6 is a central processing unit (hereinafter referred to as CPU).
) 40, and the CPU 40 is connected to a servo amplifier 15, a counter 20, and a display 41, respectively. And CPU40 is
The servo motor 2 of the drive mechanism 5 detects a current change when or just before a discharge occurs between the tip of the liquid level sensor 3 and the molten metal liquid surface 9a.
A stop command and a reverse movement command of the liquid level sensor 3 to the encoder 2, a reading command to the encoder 4, and a result display are output as control signals.

Next, the operation of the embodiment of the present invention will be explained.

In FIG. 1, the immersion electrode 2 is fixedly immersed in the molten metal 9, while the liquid level sensor 3 is connected to a high voltage (e.g.
1 kV) is applied, and the tip of the liquid level sensor 3 is located above the molten metal liquid level 9a.

In this state, when the rotating body 25 of the servo motor 22 rotates in the direction of arrow A in response to a control signal from the CPU 40, the winding transmission member 30, the rotating body 28, the winding transmission member 33, and the bracket 39 are rotated.
The guide bush 38 connects to the guide rail 23 via
The liquid level sensor 3 also descends accordingly.

Here, the CPU 40 detects a current change when a discharge occurs or just before a discharge occurs between the tip of the liquid level sensor 3 and the molten metal liquid surface 9a,
A control signal output from the CPU 40 causes the servo motor 22 to be stopped via the servo amplifier 15, that is, the lowering of the liquid level sensor 3 is stopped, and at the same time, the high voltage power supply 1 to the liquid level sensor 3 is stopped.
Power supply from 0 is stopped. The position of the liquid level sensor 3 at this time is determined by the encoder 4 and counter 2.
0, the CPU 40 calculates the pulse signal from the counter 20 to the molten metal level, and displays this calculated value on the display 41.

After the molten metal level is stored in the CPU 40 in this way, a control signal from the CPU 40 drives the servo motor 22 through the servo amplifier 15.
The rotating body 25 rotates in the direction of arrow B, and the liquid level sensor 3 rises again to the position shown in FIG. Then, the molten metal level measurement command is sent to CPU4.
When it is emitted from 0, the liquid level sensor 3 descends to measure the molten metal liquid level as described above.

In addition, the descending stop signal of the liquid level sensor 3 is as follows.
The signal may be emitted by a change in current after the tip discharge occurs.

〔effect〕

In the molten metal liquid level measurement method of the present invention, the liquid level sensor is movable in the vertical direction, so even when performing multi-point control, only one liquid level sensor and measurement circuit is required. Cost can be reduced. In addition, since the liquid level sensor is not immersed in the molten metal in a non-contact manner with the liquid surface of the molten metal, there is no measurement error due to erosion of the liquid level sensor, and highly accurate measurements can be maintained for a long period of time. The durability of the liquid level sensor is improved, and the frequency of periodic inspection of the liquid level sensor can be reduced. Furthermore, since it becomes possible to continuously measure the molten metal level, fine control becomes possible. Furthermore, since a high voltage is applied to the liquid level sensor, highly accurate measurement is possible even when the liquid level 9a of the molten metal 9 is covered with a substance with low conductivity, such as an oxide film of the molten light alloy.

[Brief explanation of drawings]

The drawings relate to embodiments of the device used in the present invention,
FIG. 1 is a block diagram of the molten metal liquid level measuring device, and FIG. 2 is a schematic front view of the drive mechanism. 1... Molten metal liquid level measuring device, 2... Immersed electrode,
3...Liquid level sensor, 4...Encoder as an example of position sensor, 5...Drive mechanism, 6...Control calculation circuit, 8...Melting furnace, 9...Molten metal, 9a... Molten metal liquid level, 1
0...Power supply.

Claims (1)

[Claims] 1. An immersed electrode immersed in the molten metal, a liquid level sensor that is movable up and down on the molten metal surface and is opposite to the immersed electrode, and a current detector that detects the current flowing between the two electrodes; In a method of measuring a molten metal liquid level in a melting furnace using a molten metal liquid level measuring device comprising a position detector that detects the position of a counter electrode that can move up and down, the immersion electrode is immersed in the molten metal. At the same time, by applying a high voltage to the liquid level sensor and moving it up and down on the liquid surface of the molten metal, a discharge occurring between the liquid level sensor and the liquid surface of the molten metal or a current change immediately before the discharge can be suppressed. A method for measuring a liquid level of a molten metal in a melting furnace, characterized in that the current detector detects the current and the position of the liquid level sensor at that time is detected.