JPH05320738A - Method for controlling sucking-up type vacuum refining apparatus - Google Patents

Abstract

PURPOSE:To enable automatic control of a sucking-up type vacuum refining apparatus by detecting the position of slag surface and the thickness of the slag in a ladle, calculating the molten steel surface with this detected result and adjusting the immersion depth of an immersed tube into the molten steel. CONSTITUTION:At first, the upper surface position of the slag layer 9 in the ladle 3 is detected by a slag surface position detecting sensor 11 fixed to a vacuum vessel 6 and a detecting bar 13 is inserted into the molten steel 8 by penetrating the slag layer 9 and immersed for the prescribed time and pulled up, and the detecting bar 13 surface is measured by a radiation temp. measuring meter 14 to obtain the slag thickness S. From data of the distance L1 between the slag surface position detecting sensor 11 and the slag surface and the slag thickness S, the distance L between the sensor 11 and the molten steel surface is decided. Feedback control is executed to an ascent/descent driving device 2 so that the distance L is equalized with a reference value L0 given to a comparator arranged in a control device 16, to adjust the height of the ladle 3 to the regulating position. By this method, the automatic control of the sucking-up type vacuum refining apparatus 1 can be executed and the productivity is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suction type vacuum refining apparatus control method for sucking molten steel in a pan into a vacuum tank and bringing the molten steel into contact with a vacuum.

[0002]

2. Description of the Related Art In the suction-type vacuum refining method in which molten steel in a pan is sucked into a vacuum tank and the molten steel is brought into contact with a vacuum to degas, a dipping pipe is rushed into the molten steel to circulate the molten steel. However, at this time, sucking up the slag generated on the surface of the molten steel adversely affects the quality of the steel, so it is absolutely necessary to avoid sucking up the slag.

Therefore, it is necessary to raise and lower the pot and the vacuum chamber relative to each other in accordance with the thickness of the slag to set the immersion depth of the immersion pipe. In particular, in the case of the DH method, since the molten steel is circulated by raising and lowering the pot and the vacuum chamber relatively at a constant cycle, data on the slag thickness is essential for setting the raising / lowering distance. Therefore, at the refining site, the operator inserted a steel bar or a steel pipe into the ladle at any time, and judged the position of the molten steel surface in the ladle and the thickness of the slag visually or on a scale. Said that automation was difficult.

[0004]

SUMMARY OF THE INVENTION The present invention has been devised in order to eliminate such disadvantages of the prior art,
Its main purpose is to provide a control method capable of automatically detecting the thickness of slag and automatically operating the suction type vacuum refining apparatus.

[0005]

According to the present invention, there is provided a method for controlling a suction-type vacuum refining apparatus for sucking molten steel in a pan into a vacuum tank and bringing the molten steel into contact with a vacuum according to the present invention. The process of detecting the slag surface position inside, the process of inserting the detection rod into the pan and measuring the temperature distribution of the detection rod pulled out after a predetermined time to detect the slag thickness, and the slag surface position and the slag thickness. And the step of calculating the molten steel surface position from the above, and the immersion depth of the immersion pipe in the molten steel is adjusted based on the data of the molten steel surface position.

[0006]

According to this structure, when the detection rod is inserted into the pot for a predetermined time and then pulled up, a clear temperature difference occurs between the portions in contact with the atmosphere, the slag, and the molten steel. The thickness of the slag can be measured by measuring the temperature distribution with a meter or the like. Since the molten steel surface can be known from this data and the data of a slag surface position detector such as a microwave sensor, the amount of plunge of the dipping pipe into the molten steel can be automatically controlled with this.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The construction of the present invention will be described in detail below with reference to specific embodiments shown in the accompanying drawings.

FIG. 1 shows the construction of a vacuum refining apparatus by the RH method constructed according to the present invention. The vacuum refining device 1 includes a ladle 3 configured to be capable of moving a predetermined stroke up and down by a lifting drive device 2,
Two dip pipes 4 project downward and a vacuum pump 5
And a vacuum chamber 6 configured so that the inside thereof can be set to a predetermined degree of vacuum. Then, the molten steel 8 is blown from one of the two immersion pipes 4 while blowing an argon gas through a gas introduction pipe (not shown) arranged in the immersion pipe and / or a lance 7 arranged immediately below the immersion pipe. To circulate.

The vacuum refining apparatus 1 comprises a slag surface position detecting sensor 11 composed of, for example, a microwave sensor, a detection rod 13 linearly moved by a fluid pressure actuating actuator 12 for a predetermined distance, and a radiation thermometer 14. The thickness detection sensor 15 and the ladle 3 based on these data
Lifting device 2 for adjusting the relative position between the vacuum chamber 6 and the vacuum chamber 6.
And a control device 16 for controlling the.

First, the upper surface position of the slag layer 9 in the ladle 3 is detected by the slag surface position detection sensor 11 fixed to the vacuum tank 6, and the steel pipe is penetrated through the slag layer 9 and reaches the molten steel 8. The detection rod 13 including the above is inserted into the pot 3, soaked for a predetermined time, and then pulled out. The immersion time at this time is set such that the detection rod 13 does not melt at the temperature of the slag. When the surface temperature of the pulled-out detection rod 13 is measured by the radiation thermometer 14, there is a clear difference in temperature between the portion in contact with the molten steel 8, the portion in contact with the slag layer 9, and the portion in contact with the atmosphere. Therefore, the slag thickness S can be obtained by processing the temperature distribution data.

From the data of the distance L1 between the slag surface position detecting sensor 11 and the upper surface of the slag and the slag thickness S, the distance L between the slag surface position detecting sensor 11 and the molten steel surface can be known.

In order to set the immersion amount A of the immersion pipe 4 of the vacuum tank 6 into the molten steel 8 to a predetermined value, the distance L between the slag surface position detection sensor 11 and the molten steel surface is a predetermined reference value. L0
Need to be Therefore, the elevation drive device 2 is feedback-controlled to adjust the height of the ladle 3 to a specified position so that the reference value L0 given to the comparator provided in the control device 16 becomes equal to the measured value L. After that, the argon gas is blown into the gas introducing pipe arranged in the dipping pipe 4a to activate the vacuum pump 5 to reach a predetermined vacuum degree in the vacuum chamber 6 to circulate the molten steel 8 or After the inside of 6 reaches a predetermined degree of vacuum, the lance 7 is activated to circulate the molten steel 8 while blowing argon gas. Or do these at the same time.

FIG. 2 shows a DH refining apparatus.
This has one dip tube 4a, and the vacuum tank 6 and ladle 3
It is the same as the above embodiment except that the relative height position with respect to, that is, the immersion depth of the immersion pipe 4a into the molten steel 8 is changed in a predetermined cycle.

Incidentally, the ladle 3 and the vacuum chamber 6 in both the embodiments.
It goes without saying that any of them may be configured to be able to move up and down.

[0015]

As described above, according to the present invention, since the thickness of the slag can be automatically detected by a simple method,
The suction-type vacuum refining equipment can be automatically controlled, which has a great effect on improving productivity.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an RH refining device according to the present invention.

FIG. 2 is a schematic configuration diagram of a DH refining device according to the present invention.

[Explanation of symbols]

 1 Vacuum Refining Device 2 Lifting Drive Device 3 Ladle 4 Immersion Tube 5 Vacuum Pump 6 Vacuum Tank 7 Lance 8 Molten Steel 9 Slag Layer 11 Slag Surface Position Detection Sensor 12 Fluid Pressure Actuator 13 Detecting Rod 14 Radiation Thermometer 15 Slag Thickness Detection sensor 1 16 Control device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takatsugu Ueyama 20-1 Shintomi, Futtsu City Nippon Steel Corporation Technical Development Division

Claims (1)

[Claims] 1. A method of controlling a suction-type vacuum refining apparatus for sucking molten steel in a pot into a vacuum tank to bring the molten steel into contact with a vacuum, the process comprising: detecting a slag surface position in the pot; It has a process of detecting the slag thickness by measuring the temperature distribution of the detection rod that is inserted into the pan and pulled out after a predetermined time, and a process of calculating the molten steel surface position from the slag surface position and the slag thickness. A method for controlling a suction-type vacuum refining apparatus, which comprises adjusting a depth of immersion of a dipping pipe in molten steel based on surface position data.