JPS60247451A - Method and device for following up molten metal surface in continuous casting mold - Google Patents

Abstract

PURPOSE:To suppress the fluctuation of a molten metal surface without delay and to avert the surface defect of a continuously cast billet by discriminating the fluctuating degree of the molten metal surface and subjecting the molten metal surface to the control for changing the phase at the neutral point of oscillation in the oscillation system of a casting mold. CONSTITUTION:The fluctuating level output oscillated from a level detector 15 for the molten metal surface is judged by a comparator 14. The level of the molten metal surface is controlled by operating only the opening degree controller 13 of a slide gate 2 provided to a tundish nozzle when the rate of the fluctuation is smaller than the prescribed value. The operation commander 16 of a hydraulic cylinder 15 is simultaneously operated in addition to the controller 13 to control relatively the level of the molten metal surface in the continuous casting mold 3 when the rate of the fluctuation is larger than the prescribed value. The fluctuation of the molten metal surface is thus effectively and adequately suppressed and the surface defect of the billet owing to slag intrusion is averted.

Description

[Detailed Description of the Invention] (Technical Field) The technical content described in this specification relates to the improvement of continuous casting operations mainly for steel strands in continuous casting (hereinafter referred to as continuous casting) in VS, which often occur in the early stages of the operations. The aim is to propose development results related to eliminating the man-hours required for full-scale maintenance due to slag surface defects caused by entrainment of continuous casting flux, and the resulting decrease in latching.

(Background technology) In conventional continuous casting operations, a level detector that monitors the situation inside the continuous casting mold feeds back fluctuations in the level to the tundish nozzle, that is, the slide gate of the hot water discharging nozzle. Controls have been used to adjust the opening of the slide gate depending on the situation.

However, due to the effects of looseness in the dummy bar chain and sometimes slippage of the pinch roll, scene changes can occur instantaneously.
Approximately 0IIIIl occurs, which is normal (usually 4oIllI)
It takes 5 to 6 seconds to return to (within I1).

For this reason, in the worst case scenario, surface defects in the slag occur due to encroachment of continuous casting black, which necessitates full-scale maintenance and causes a decline in continuous casting retention.

Fluctuations in the hot water level occur due to looseness in the dummy bar chain.
Due to the weight of the dummy bar itself, there is a gap at the top of each connecting bin when it is initially installed as a mold.
As the casting progresses, the pull-out resistance of the slab occurs and increases, so that the looseness of each connecting bottle is reversed from the upper side to the lower side, and since the area around it is in a balanced state, a slight decrease in resistance causes each connection to be reversed. The slab will fall by the amount that the bottle rattles.

Normally, each link of the dummy bar has about 10IIIL of play in the connecting bottle, and since the number of links is about 8, the hot water level will drop suddenly by about 80non, and in this state, the pull-out resistance and falling blade are large. This continues to the point where it becomes unbalanced.

When such a severe scene change occurs, only the slag bears remain on the mold surface just below the meniscus of molten steel when the scene is lowered, and when the scene rises, the shell rides on the slag bears and rolls into the surface, resulting in surface defects. .

This phenomenon occurs because the response speed of the slide gate opening adjustment was slow and could not follow the above-mentioned abnormality.

(Objective of the Invention) The object of the present invention is to appropriately suppress severe melt level fluctuations that have conventionally often occurred in the early stage of continuous casting operations as described above, and to effectively avoid casting defects that are prevented from occurring. be.

(Structure of the Invention) The present invention monitors the scene inside the continuous casting mold, determines the magnitude of the fluctuation in the mold level, and according to the determination result, when operating a continuous casting machine that controls the inflow amount according to fluctuations in the mold level. , a method for tracking the melt level in a continuous casting mold characterized by adding vibration neutral point phase change control in the vibration system of the continuous casting mold, and a scene level detector for monitoring the melt level in the connected casting mold. A comparator is installed in the control system that adjusts the opening of the tundish nozzle according to the output, and the vibration neutralization in the vibration system of the continuous casting mold is determined according to the output of the comparator. A hydraulic cylinder is installed on the bushing rod of Nicode Mold Oscillation 'a@, which is a continuous casting mold in-molten metal level tracking device characterized by having an operating system for changing the phase installed in the vibration system. Activation by the signal from the detector leads to immediate movement of the entire continuous casting mold to the side where the molten metal level fluctuates, that is, movement of the continuous casting mold that relatively eliminates the scene fluctuation. At this time, the following range for the melt level fluctuation is given by the sum of the amount of movement of the continuous casting mold and the amount of adjustment corresponding to the amount of molten metal by adjusting the opening of the slide gate. Therefore, the relative fluctuation of the melt level with respect to the continuous casting mold , it can be easily halved to within about 40n+m, eliminating troubles such as rising.

FIG. 1 shows a specific example of the embodiment of the present invention, in which 1 is a tundish, 2 is a slide gate of the tundish nozzle, 3 is a continuous casting mold, 4 is an immersion nozzle, 5 is a hot water level detector, and 6 is a tundish nozzle slide gate. is a slab, 7 is a dummy bar, 8 is an oscillation arm of continuous casting mold 3, 9 is its fulcrum, 1
0 is a bushing rod, 11 is an oscillation motor, 12 is an eccentric wheel, and 13 is an opening adjuster for the slide gate 2.

According to this invention, a comparison side 14 is provided in the control system that guides the operation of the opening adjuster 13 based on the output of the scene level detector 5, and the comparison side 14 is provided to determine the magnitude of the scene level change. A hydraulic cylinder 15 is installed in the bushlot 10 as an operating system for changing the vibration neutral point phase in the vibration system of the continuous casting mold when the surface changes. Note that 16 in the figure is an operation command device for the hydraulic cylinder 15.

In the continuous casting equipment, molten steel (2) injected from a tundish 1 forms a shell S in a continuous casting mold 3, and is drawn out by a dummy bar 7 as a slab 6.

At this time, a mold oscillation device is provided for proper inflow of continuous casting flux so as to prevent seizure between the mold surface of the continuous casting mold 3 and the molten steel m.

The continuous casting mold 3 is provided with a level detector 5 to monitor the level of the molten steel m, and the slide cage 2 of the tundish 1 is installed to keep the surface level in the continuous casting mold 3 constant. It is controlled by an opening adjuster 13.

Mold oscillation moves the continuous casting mold 3 up and down in a certain cycle, so the set position (neutral point) of the continuous casting mold 3 is
One end of the oscillation arm 8 is connected to the fulcrum 9, and an eccentric shaft 11 is connected to the opposite end of the fulcrum 9 via a bush rod 10, and the oscillation arm 8 is swung by the rotation of a motor 12.

According to this invention, a hydraulic cylinder 15 is incorporated into the bushing rod 10, and thereby the vibration neutral point phase is changed in a timely manner.This phase change command is issued when the output of the scene level detector 5 is abnormal. When the difference is greater than 1, the operation command device 16 operates based on the determination result of the comparator 14.

The hot water level according to the present invention is controlled by the scene level detector 5, the comparator 14, the opening adjuster 13 of the slide gate 2, and the operation command device 16 of the hydraulic cylinder 15. The oscillated fluctuation level output is judged by the comparator 14, and if the fluctuation amount is <40 mm, the opening adjuster 1 of the slide gate 2 of the tundish nozzle is
3 is activated to perform scene I novel control, while the amount of variation is > 4On+m, the slide gate opening adjuster 1
In addition to 3, the operation command device 16 of the hydraulic cylinder 15 is also operated at the same time to control the relative level of hot water in the continuous casting mold 3, thereby effectively and appropriately suppressing scene fluctuations due to slag entrainment. Slab surface defects can be avoided.

(Example) In continuous casting equipment, a mold oscillation device is usually installed to prevent the molten steel from seizing on the surface of the mold when pouring from the tundish into the continuous casting mold through the nozzle. . During continuous casting operations, especially in the early stages,
The molten steel surface fluctuates up and down by 80 to 100 mm in the continuous casting mold due to rattling of the dummy bar link, slip of the pinch rolls, etc. At this time, the scene control that adjusts the injection flow rate through the nozzle of tundish 1 alone cannot keep up with the sudden change in the scene level as described above, so in addition to this, it is necessary to control the vibration of the continuous casting mold. Changing the phase of the neutral point In other words, a hydraulic cylinder 15 is incorporated into the bushrot 10 of the mold oscillation device and controlled in parallel.

At this time, since there is not always a scene change of 80 to 100 mm, the output from the hot water level detector 5 is compared with the total 14.
Based on this, phase change control of the vibration neutral point of the continuous casting mold is added only when the fluctuation in the scene level exceeds, for example, 40 mm.By performing these steps, the speed of response to the fluctuation in the melt level is increased, and the amount of fluctuation in the scene is reduced. This makes it possible to reduce the amount of energy required and shorten the recovery time.

(Effects of the Invention) According to the present invention, excessive fluctuations in the molten metal level caused by the use of a dummy bar and the rattling of the connecting link bin, slip of the pinch rolls, etc., can be prevented in the early stage of continuous casting operation. Scene changes can be suppressed without delay even when
As a result, surface defects in the continuously cast slab can be avoided without cleaning the slab product or increasing manufacturing costs.

[Brief explanation of drawings]

FIG. 1 is a skeleton diagram showing a plugging mode. 1... Tanditshu 2... Nozzle gate 3...
・Mold 4... Nozzle 5... Molten metal level transmitter 6... Slab 7... Dummy bar 8... Vibrating arm 9... Fulcrum 10... Butschrodt 11... Liquid pressure Cylinder 12... Eccentric shaft 13... Fluctuation level discrimination device 14
... Nozzle gate opening command device 15 ... Hydraulic cylinder operation command device 16 ... Eccentricity amount 17 ... Molten steel 18 ... Motor. Patent Applicant: Kawasaki Steel Co., Ltd. Procedural Amendment Written on December 7, 1982 Manabu Shiga, Commissioner of the Patent Office1, Indication of the case, Patent Application No. 101785, filed in 1982, 2, Name of the invention: Continuous casting mold inner hot water surface Relationship between the follow-up method and device 3, and the case of the person making the amendment Patent applicant name (125) Kawasaki Steel Corporation 4 Column 6 of “Number of inventions stated in the scope of patent claims” in the representative application
, content of correction

Claims (1)

[Claims] 1. During operation of a continuous casting machine that monitors the level of molten metal in the continuous casting mold and controls the inflow amount according to fluctuations in the scene level, the magnitude of the scene fluctuation is determined, and according to the determination result, A method for tracking the melt level in a continuous casting mold, characterized by adding control to change the vibration neutral point phase in the vibration system of the continuous casting mold. 2. Comparison that includes a scene level detector that monitors the hot water level in the continuous casting mold and determines the magnitude of the scene level fluctuation in the control system that adjusts the opening of the tundish nozzle according to the output of this detector. A continuous casting mold inner surface tracking device, characterized in that the vibration system is provided with an operating system for changing the vibration neutral point phase in the vibration system of the continuous casting mold according to the output of the comparator. 3. The device according to 2, wherein the operating system for changing the vibration neutral point phase is a hydraulic cylinder built into a bush rod of the mold oscillation device.