JPH058006A - Method for detecting perfectly solidified position in continuously cast slab - Google Patents

Abstract

PURPOSE:To precisely detect the perfectly solidified position in a continuously cast slab. CONSTITUTION:Cast slab supporting rolls 2 in before and after perfectly solidified position, are constituted with the supporting rolls 2A for supporting unsolidified molten steel part 3 in width direction of the cast slab and the supporting rolls 2B for supporting both sides of the unsolidified molten steel position 2B, and load cells 8 are set only at between bearings 5 of upper supporting rolls 2A for supporting the unsolidified molten steel, part 3 and a frame 7 for roll stand. By difference of the loads loaded to supporting rolls between the unsolidified molten steel part and the perfectly solidified part, the perfectly solidified position can be precisely detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a relatively simple structure and is capable of accurately detecting the position of complete solidification of a continuously cast slab (hereinafter also simply referred to as a slab) drawn from a mold. The present invention relates to a method for detecting a completely solidified position of a slab.

[0002]

2. Description of the Related Art Generally, in continuous casting, a molten metal continuously poured into a mold is indirectly cooled by the mold to form a solidified shell of a certain size, and then a large number of slab supporting rolls While the solidification is promoted by spray cooling while passing through, it is drawn out by a pinch roll, completely solidified, and then cut into a certain length to manufacture a continuously cast slab.

In such a continuous casting process, it is very important in operation and quality to accurately detect the position of complete solidification on-line and control the position.

For example, an internal defect due to so-called center segregation, in which components are concentrated when the solidified shell grows and is completely solidified, is known. In order to reduce this center segregation,
Immediately before the slab is completely solidified, light reduction casting is applied to reduce the amount of solidification shrinkage.To fully exert the effect of this light reduction technology, the fully solidified position of the continuously cast slab must be set. It is necessary to control so that the position is an appropriate pressure reduction position, and for that purpose, the complete coagulation position must be accurately detected.

However, the completely solidified position of the slab constantly fluctuates due to changes in the temperature of the molten steel at the time of casting, cooling conditions, changes in the casting speed, etc. Therefore, the method for detecting the completely solidified position of the slab has been conventionally used. Although various have been proposed,
No suitable method is known yet.

By the way, among the conventionally proposed methods for detecting the completely solidified position of a cast slab, Japanese Patent Laid-Open Nos. 54-17327, 54-62125, 54-66333, and JP-A-56-151147, JP-A-63-174770, JP-A
The method for detecting the load of the slab supporting roll proposed in Japanese Laid-Open Patent Publication No. 1-197051 has the advantage that it can be directly detected at low cost, and can be said to be a relatively excellent method. An example is shown below.

[Patent Document 1] Japanese Patent Application Laid-Open No. 63-174770 DISCLOSURE OF THE INVENTION A contact pressure is measured by providing a plurality of pressure sensors in the axial direction on the surface of a plurality of cast slab supporting rolls, and the position where the measured value sharply decreases. Is the completely solidified position of the slab.

JP-A 1-197051 discloses that a part of the upper driven roll of the pinch roll band is slightly released upward, and a bulging applied to the released upper driven roll by a load cell installed in a bearing portion of the upper driven roll. The presence or absence of force is measured, and the position at which this bulging force sharply decreases is taken as the completely solidified position of the slab.

[0009]

However, in the case of the above-mentioned prior art, a pressure sensor is provided on the surface of the slab supporting roll, and when the contact pressure is measured, it contacts the slab at high temperature,
There is a problem that the pressure sensor is required to have durability, and the wiring of the pressure sensor is drawn out from the surface of the rotating roll, so that the structure is complicated and practical application is difficult.

On the other hand, in the case of the above-mentioned prior art, as shown in FIG. 4, the roll bearing portion 11 is provided with the load cell 12,
Although it is a relatively simple structure, a part of the upper driven roll 13 is provided slightly above to allow the bulging force to be measured, and the completely solidified position 15 of the cast piece 14 is detected by this. In light pressure casting for the purpose of reduction,
There is a problem that this conventional technique cannot be applied because a roll arrangement in which the distance between the upper roll and the lower roll is narrowed in the casting direction is required and all the light reduction rolls are loaded.

The present invention solves the above-mentioned problems of the prior art and has a relatively simple structure, even in a roll arrangement in which the distance between the upper roll and the lower roll is narrowed in the casting direction as in light pressure casting. It is an object of the present invention to provide a method for detecting a completely solidified position of a continuously cast slab, which can accurately detect a change in load before and after the completely solidified position.

[0012]

In order to achieve the above object, the inventors of the present invention have conducted extensive studies and, as a result, have made a support roll of a continuously cast slab a structure suitable for detecting the completely solidified position of the slab. It was found that the above is effective, and the present invention has been completed.

That is, the present invention provides a slab support roll that supports continuously cast slabs drawn from a mold.
The slab support rolls before and after the completely solidified position are composed of a support roll that supports the unsolidified molten steel position in the slab width direction and a support roll that supports both sides of the unsolidified molten steel position to support the unsolidified molten steel position. The load applied to the supporting roll is measured, and the completely solidified position of the slab is detected by the measured value.

[0014]

In the present invention, the slab support rolls before and after the completely solidified position are divided into a support roll that supports the unsolidified molten steel position in the slab width direction and a support roll that supports both sides of the unsolidified molten steel position. Therefore, the support roll supporting the unsolidified molten steel position is subjected to the load of the molten steel static pressure in the unsolidified molten steel portion, but is not affected by the molten steel static pressure in the fully solidified portion. When the load applied to the support roll is measured by, for example, providing a load cell on the bearing portion of the roll, the output of the load changes at the boundary portion, so that the completely solidified position of the slab can be accurately detected.

Further, even in the roll arrangement in which the distance between the upper roll and the lower roll is narrowed in the casting direction as in the light pressure casting, the support rolls supporting the unsolidified molten steel position are similar to those described above in the unsolidified molten steel portion. Although it receives a load due to static pressure, it is not affected by the static pressure of molten steel at the fully solidified portion, and receives a reaction force larger than the static pressure of molten steel due to a slight reduction of the completely solidified slab. Since the output of the load changes in the part, the completely solidified position of the cast piece can be accurately detected. In particular, in the present invention, the slab support roll before and after the completely solidified position is divided into a support roll that supports the unsolidified molten steel position in the slab width direction and a support roll that supports both sides of the unsolidified molten steel position. The complete solidification position of the slab can be accurately detected without being affected by the rolling reaction force of the solidified shells on both sides of the unsolidified molten steel position.

[0016]

Embodiments of the present invention will be described below with reference to FIGS. As shown in FIG. 3, before and after the completely solidified position of the continuous casting machine C, a light reduction roll stand D is provided. In this embodiment, the load cell 8 is provided on the upper driven roll 2 of the light reduction roll stand D. Has been installed.

1A and 1B are explanatory views of a light-pressure reduction roll stand to which the method for detecting the completely solidified position of a continuously cast slab according to the present invention is applied. FIG. 1A is a side sectional view, and FIG. 1B is A in FIG. −
FIG. In both figures, the roll 2 that supports the cast piece 1 is composed of a support roll 2A that supports the unsolidified molten steel portion 3 in the width direction of the cast piece and a support roll 2B that supports both side portions 4 at the unsolidified molten steel position. ing. Each roll 2A, 2B
Are supported by bearings 5 and 6, and the bearings 5 and 6 are fixed to the frame 7 of the roll stand.

In this example, the load cell 8 is installed only between the bearing 5 of the upper support roll 2A supporting the unsolidified molten steel portion 3 and the frame 7 of the roll stand.

In the light reduction casting, as shown in FIG. 1a, in order to lightly reduce the cast piece 1 by the amount corresponding to the solidification shrinkage before and after the completely solidified position 9 where the internal unsolidified molten steel 3 of the cast piece 1 completes the solidification, In the completely solidified position 9, the distance between the upper and lower support rolls 2 and 2 is set so as to become narrow with a certain gradient in the casting direction. In such a case, as shown in FIG. 2, the total load z of the rolling reaction force x of the wide surface of the slab (upper and lower surfaces of the figure) and the static pressure of molten steel y acts on the support roll 2A within a range having a gradient.

As a result, the complete solidification position 9 can be accurately detected even in the roll arrangement having the rolling down gradient.

As described above, according to the present invention, it is possible to accurately detect the target complete solidification position by measuring only the load that changes before and after the complete solidification position.

[0022]

Since the present invention is configured as described above, it is possible to accurately detect the completely solidified position of a continuously cast slab, and to perform casting such as light pressure casting. Even in the roll arrangement in which the distance between the upper roll and the lower roll becomes narrower in the direction, the completely solidified position of the continuously cast slab can be accurately detected, so that the light reduction can be performed at the optimum light reduction position and the center segregation can be reduced.

[Brief description of drawings]

FIG. 1 is an explanatory view of a light reduction roll stand to which a method for detecting a completely solidified position of a continuously cast slab according to the present invention is applied, where a is a side sectional view and b is an AA sectional view of a.

FIG. 2 is a conceptual diagram of a load acting on a roll in the example of the present invention.

FIG. 3 is a schematic explanatory view of a continuous casting machine.

FIG. 4 is an explanatory view of the prior art, in which a is a side sectional view,
b is a BB sectional view of a.

[Explanation of symbols]

1: Slab 2, 2A, 2B: Slab support roll 3: Unsolidified molten steel part 4: Both sides of unsolidified molten steel position 5, 6: Bearing 7: Frame 8: Load cell 9: Complete solidification position x: Wide surface of slab Showing the rolling reaction force of y: Curve showing the static pressure of molten steel z: Curve showing the total load of the rolling reaction force and the static pressure of molten steel

Claims (1)

Claim: What is claimed is: 1. A slab support roll before and after a completely solidified position of a continuously cast slab that is pulled out from a mold, and a support roll that supports an unsolidified molten steel position in the slab width direction, and an unsolidified slab. Consists of supporting rolls that support both sides of the molten steel position,
A method for detecting a completely solidified position of a continuously cast slab, comprising measuring a load applied to a support roll that supports the position of the unsolidified molten steel, and detecting a completely solidified position of the slab by the measured value.