KR20010019254A - A Method for Brushing Roll in Strip Casting Apparatus - Google Patents

Abstract

PURPOSE: A method for brushing the surface of a roll in a thin plate casting machine is provided to restrain inequality of congelation in roll width direction and steel billet inequality phenomenon. CONSTITUTION: A method for brushing the surface of a roll (10) of twin roll type continuous casting machine including twin rolls, includes the steps of constructing at least two or more joint type brush rolls (40) arranged in width direction at a regular gap, a joint type brush roll joint connecting or operating the joint type brush rolls (60), one or a plurality of auxiliary brush rolls (70) having the same length as the gap of the joint type or longer than the gap, an auxiliary brush roll joint (50) operating the auxiliary brush roll, and a joint operating device operating joints; arranging the roll brushing apparatus to arrange the joint type brush rolls following width direction of the roll and brush the space between the joint type brush rolls with the auxiliary brush roll; and overlapping the joint type brush rolls with the surface of the roll in condition that the size of the overlapped part changes linearly from the center to an edge part, brushing the surface of the roll by operating the roll brush apparatus to simply contact the auxiliary brush roll with the surface of the roll.

Description

A method for brushing roll in strip casting apparatus}

The present invention relates to a method of brushing a roll surface of a twin roll sheet metal casting apparatus for producing ferrous and nonferrous metals and alloys thereof from sheet metal directly in molten metal, and more particularly, to achieve uniform solidification in the roll width direction. It is related with the roll surface brushing method of the twin roll type thin sheet casting apparatus which can be used.

In the case of sheet casting using a twin roll sheet metal casting apparatus, the molten steel has a cylindrical upper nozzle through a tundish 11 and a stopper 12 installed on the sheet casting rolls 10 and 10 '. 13) is supplied.

The supplied molten steel solidifies in contact with the pair of rolls 10 and 10 'in the molten steel meniscus portion 14 to grow a solidification angle 15 to form a thin plate slab 16.

A brush roll is installed on the molten steel meniscus 14 to remove impurities generated by internal and external factors of the molten steel during sheet metal casting.

As a roll brushing technique in the conventional sheet metal casting method, those disclosed in Japanese Patent Application Laid-Open No. 8-309488 and Korean Utility Model Registration No. 53608 may be mentioned.

Japanese Patent Application Laid-open No. Hei 8-309488 discloses a roll brush device and a method of brushing rolls using the roll brush device, which are configured to remove part of the slabs and oxidation products attached to the rolls without being scattered to the surroundings. Install two brush rolls arranged in parallel and vertically in contact with each other at the same time to remove the dust on the surface of the roll by contacting them all over the roll width direction, and collect the scattered dust with a dust collector so as not to fly around. The upper and lower rotational speeds are different.

That is, in the conventional method, as shown in FIG. 2, the brush rolls 20 integrally arranged in parallel with the rolls are contacted over the entire roll width direction to form a constant overlapping portion to remove impurities formed on the rolls. The brush roll 20 rotates in the same direction as the roll or in the opposite direction with the brush roll rotating shaft 30 as an axis, and the degree of removal of the roll surface scale is determined according to the contact strength with the roll and the rotation speed.

On the other hand, Korean Utility Model Registration No. 53608 discloses a device for removing the surface coating layer formed on the surface of the casting roll by applying an acidic aqueous solution to the surface of the casting roll for producing a thin plate, where the cleaning roll is located on the upper surface of the roll circumference, And the lower part is provided with a brush roll for removing the surface coating layer.

Generally, in the thin plate casting method, since the slab is formed while being in contact with the hot molten steel as the roll rotates, the roll surface temperature is periodically raised and lowered, and the roll surface average temperature is raised above a certain value.

Therefore, such a rise in the roll temperature causes a thermal crown phenomenon in which the middle portion of the roll is expanded and bulged.

In addition, the cooling ability at both ends of the roll cooling water circuit structure is lower than that of the middle portion in the width direction of the roll. Therefore, the difference in the solidification uniformity of the cast slab in the roll width direction occurs according to the difference in cooling characteristics in the roll width direction.

A method of controlling the thickness of the roll surface coating layer in the roll width direction is mentioned as a method of eliminating the difference in the solidification uniformity of the cast slab in the roll width direction.

However, in the brushing method disclosed in the above-mentioned Japanese Patent Publication, it is possible to simply remove the oxide scale layer formed on the surface of the roll because the brush roll of a straight line is integrally arranged in parallel with the roll, but the thickness of the surface coating layer in the roll width direction is controlled. There is a problem that it is impossible to achieve uniform solidification in the roll width direction.

In addition, as in the above-mentioned Korean Utility Model, in the case of removing the oxide scale layer by dissolving the roll surface with an acid, it is not easy to uniformly remove the surface oxide layer continuously generated during casting for a very short time and uniformly remove it. Therefore, it is very difficult to control uniform solidification of the cast steel in the roll width direction.

In order to solve the problems of the prior arts described above, the present inventors can effectively use a dense surface coating layer, which is inevitably generated when molten steel is solidified in contact with a roll during twin roll sheet metal casting, in connection with uniform solidification in the slab width direction. The present invention was proposed based on the results, and the present invention can not only remove the roll surface coating layer of the twin roll continuous casting machine but also the thickness of the roll surface coating layer in the roll width direction. It is to provide a roll surface brushing method in a sheet casting machine that can suppress the uneven unevenness of the roll width direction inevitably generated during sheet casting by controlling by using There is this.

1 is a configuration diagram showing a state of casting a thin plate using a thin plate casting machine with a conventional brush roll attached

Figure 2 is a plan view showing a conventional roll and brush roll arrangement state

3 is a graph showing the relationship between the overlapping portion of the brush roll and the roll and the overlapped portion size and the roll brush force during operation of the brush roll;

Figure 4 is a plan view showing an example of applying a brush roll according to the present invention to the roll

Figure 5 is a perspective view showing that the brush roll and the auxiliary brush roll of the present invention is applied to the roll

Explanation of symbols on the main parts of the drawings

10, 10 ': thin roll casting twin roll 20: brush roll

21 roll surface oxide scale layer 30 brush roll rotation axis

40: segmented brush roll 50: auxiliary brush roll joint 60: segmented brush roll joint 70: auxiliary brush roll

80: joint operating device

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated.

The present invention is a method for brushing the roll surface of a twin roll continuous casting machine comprising a pair roll,

At least two segmented brush rolls arranged in the width direction of the roll at regular intervals, segmented brush roll joints for connecting and operating segmented brush rolls, and having a length equal to or greater than the distance between the segmented brush rolls Constructing a roll brushing device comprising one or a plurality of auxiliary brush rolls, an auxiliary brush roll joint for actuating the auxiliary brush roll, and a joint actuator for actuating the joints;

Arranging the roll brushing device such that the segmented brush rolls are disposed along the width direction of the roll and the space between the segmented brush rolls is brushed by the auxiliary brush roll; And

The segmented brush rolls are superimposed on the roll surface, subjecting the size d of the overlap portion to change linearly from the center of the roll to the edge, and the auxiliary brush operates the roll brushing device so that it simply contacts the roll surface. It relates to a roll surface brushing method of a twin-roll continuous casting machine comprising a step of brushing the roll surface.

Also preferably, the present invention provides a method for brushing the roll surface of a twin roll continuous casting machine comprising a pair roll.

At least two segmented brush rolls arranged in the width direction of the roll at regular intervals, segmented brush roll joints for connecting and operating segmented brush rolls, and having a length equal to or greater than the distance between the segmented brush rolls Constructing a roll brushing device comprising one or a plurality of auxiliary brush rolls, an auxiliary brush roll joint for actuating the auxiliary brush roll, and a joint actuator for actuating the joints;

Arranging the roll brushing device such that the segmented brush rolls are disposed along the width direction of the roll and the space between the segmented brush rolls is brushed by the auxiliary brush roll;

Measuring the thickness t ₀ of the roll coating layer before casting, and observing the hot band portion of the cast steel;

Setting a point on the roll surface at which the hot band portion starts to be seen in the edge direction from the roll center portion using the hot band portion observation result of the cast;

At the point where the hot band portion set as described above starts to occur, the overlap portion size d becomes 0, and at the edge portion, the size of the overlap portion falls within 1000 times the thickness t ₀ , and the overlap portion size d The overlapping segmented brush rolls on the roll surface under conditions such that the hot band portion increases linearly as it goes to the edge portion, and the auxiliary brush operates the roll brushing device to simply contact the roll surface. It relates to a roll surface brushing method of a twin-roll continuous casting machine comprising the step of brushing the roll surface.

Hereinafter, the present invention will be described in more detail.

In order to brush the roll surface of a twin roll continuous casting machine according to the present invention, as shown in FIGS. 4 and 5, at least two or more segmented brush rolls 40 and segments disposed in the width direction of the roll at regular intervals. Segmented brush roll joint 60 for connecting and actuating the brushed roll rolls 40, one or a plurality of auxiliary brush rolls 70 having a length equal to or greater than the distance between the segmented brush rolls 40, It is necessary to construct a roll brushing device including an auxiliary brush roll joint 50 for operating the auxiliary brush roll 70 and a joint operating device 80 for operating the joints.

In the present invention, in order to improve the uniformity of the solidification in the slab width direction during casting, without using a straight brush roll arranged parallel to the roll as in the prior art, the brush roll in the slab width direction as shown in FIG. A segmented brush roll 40 divided into segments is used.

The segmented brush roll joint 60 which connects and operates the segmented brush roll 40 is connected to the middle of the brush roll rotating shaft 30 so as to be bent during rotation, a universal joint, a bearing body having the universal joint, And a segmented brush roll actuating cylinder connected to the bearing body to enable the segmented brush roll to be moved back and forth in the roll direction during casting.

At this time, the brush roll operating cylinder for moving the segmented brush roll 40 is supported and operated by the joint operating device 80, and in the middle of the segmented brush roll 40, there is a discontinuity of the brush, thereby brushing the roll. In order to brush this area, an auxiliary brush roll 70 having a length equal to or greater than the width of the discontinuity is installed at the lower part of the segmented brush roll as shown in FIG. 5.

At this time, the forward and backward movement of the auxiliary brush roll is preferably linked to the movement of the segmented brush roll 40 so that the position is controlled so that the brushing strength is the same.

As the auxiliary brush roll joint 50, it is preferable to use a structure consisting of a universal joint, a bearing body, and a cylinder for operating the auxiliary brush roll like the segmented brush roll joint 60.

The segmented brush roll 40 configured as described above is in contact with each other in the roll width direction with respect to the center of the roll width direction according to the forward and backward movement of the operating cylinder.

When the segmented brush roll 40 is arranged in a concave shape as shown in FIG. 4, the brushing strength at both ends of the roll is increased, so that the thickness of the roll surface oxide scale layer is thin, and the brushing strength is weak at the center, resulting in a thick oxide scale layer. Differences in the coating layer occur. Such a phenomenon is shown schematically in FIG. 3.

That is, FIG. 3 graphically shows the relationship between the overlapped portion size d and the roll brush force when the overlapped portion becomes d in a state in which a part of the brush is pressed on the roll in a portion in contact with the roll of the brush roll.

As shown in FIG. 3, the greater the size d of the overlapped portion, the stronger the brush strength of the roll, and inversely, the thickness of the oxide scale layer is also inversely proportional.

On the other hand, in order to more effectively suppress hot band generation according to the roll surface brushing method of the twin roll continuous casting machine of the present invention, it is necessary to measure the thickness t ₀ of the roll coating layer before casting and observe the hot band portion of the cast steel. .

The tendency of hot band generation of cast steel during casting can be confirmed by the cast steel temperature distribution, and the method of non-contact measurement of the surface temperature of the cast steel using an infrared temperature device can be used.

Of course, the present invention is not limited thereto.

Next, using the hot band section observation result of the above cast, the point where the hot band section starts to appear in the edge direction at the center of the roll is set on the roll surface.

Next, at the point where the hot band portion set as described above starts to occur, the size of the overlapped portion d becomes 0, and at the edge portion, the size of the overlapped portion is less than 1000 times the thickness t ₀ of the roll coating layer. (d) allows the segmented brush rolls to overlap the roll surface, with the condition that the linear band increases linearly from the point where the hot band portion starts to occur, and the auxiliary brush is simply in contact with the roll surface. Brush to brush the roll surface.

Here, the size (d) of the overlapped portion means a length in which the roll and the brushing roll are engaged with the brushing roll.

As described above, by controlling the thickness of the coating layer in the roll width direction differently, it is possible to control the coagulation unevenness generated in the cast steel to adjust to a uniform state.

The roll surface coating layer in sheet metal casting depends on the composition of molten steel.

Table 1 shows an example of the component analysis results of the roll surface coating layer according to the steel grade.

[Roll Surface Coating Layer Component (wt)] MnO SiO ₂ FeO Ni ₂ O Bal. STS 300 series 30-55 0-10 0-9 10-20 - General Carbon Steel 40-75 20-50 0-5 - -

The thickness of the coating layer varies depending on the number of castings and the type of molten steel, but is generally about 5-20 μm, and the thickness of the coating layer is determined by the brushing strength of the brush roll. Cast solidification is achieved by heat transfer between the roll surface and molten steel. If there is a coating layer on the roll surface, heat transfer is carried out through the coating layer. Therefore, the cast solidification characteristics are determined by the thermal conductivity and thickness of the coating layer or by the surface tension of the coating layer. . As the thickness of the coating layer becomes thicker, the heat transfer becomes smaller, so that the thickness of the coagulation angle formed becomes thinner, and as the thickness becomes thinner, the thickness of the coagulation angle becomes thicker.

Therefore, as shown in FIG. 4, when the segmented brush roll is disposed in a concave shape during casting and rotates while contacting the roll, the thickness of the coating layer becomes thicker at both ends of the roll, and the thickness of the coating layer is reduced at both ends of the roll. Therefore, the solidification of the end portion rather than the central portion is promoted.

On the other hand, depending on the steel grade, black band phenomenon occurs at the end of the cast steel as opposed to the STS 300 series.In this case, the brush roll joint is moved to the roll side to make it convex. As a result of the contact with the roll, the development of the solidification angle at both ends of the cast is slowed, so that the black bands generated at both ends are lost or reduced.

Hereinafter, the present invention will be described in more detail with reference to Examples.

(Example)

According to an embodiment of the present invention, when the nitrogen gas is used as the atmosphere gas during sheet casting of STS 300 steel, the thickness of the end portion of the slab becomes thick due to the thermal crown phenomenon of the roll, and thus the end hot band phenomenon occurs or the roll cooling water circuit structure. The end hot band phenomenon appears due to the phenomenon that the cooling capacity at both ends is inferior to the middle portion in the width direction of the roll.

The hot band generation tendency of the cast during the casting was confirmed by the cast temperature distribution, the temperature distribution of the cast was measured by the non-contact surface temperature of the cast using an infrared temperature apparatus.

At this time, in order to prevent such hot band generation, the segmented brush roll joint 60 is moved to the concave shape in the opposite direction of the roll as shown in FIG. 4, and then the entire segmented brush roll 40 is moved to the roll side with a constant force. It was brought into contact with the roll. In this way, the development of the solidification angle at both ends of the cast is promoted, so that hot bands generated at both ends are eliminated or reduced. In this way, the solidification uniformity in the roll width direction varies with each casting and with time even during the same casting. Therefore, in order to suppress the hot band generation, the segmented brush roll 40 is checked in real time while checking the state of the casting during casting. The solidification uniformity of the cast can be maintained in the best state by changing the contact state with the roll.

As described above, in the conventional roll brushing method, since it uses a straight brush roll arranged in parallel with the roll, it was not possible to control the thickness of the surface coating layer in the roll width direction, but in the present invention, a segmented brush roll is installed during thin sheet casting. By controlling the thickness of the roll surface coating to a desired thickness over the roll width direction, it is possible not only to suppress the uneven unevenness of the roll width direction which is inevitably generated during sheet casting, but also to prevent the unevenness of the slab, such as hot band phenomenon.

Claims (5)

In the method of brushing the roll surface of a twin roll continuous casting machine comprising a double roll, At least two segmented brush rolls arranged in the width direction of the roll at regular intervals, segmented brush roll joints for connecting and operating segmented brush rolls, and having a length equal to or greater than the distance between the segmented brush rolls Constructing a roll brushing device comprising one or a plurality of auxiliary brush rolls, an auxiliary brush roll joint for actuating the auxiliary brush roll, and a joint actuator for actuating the joints; Arranging the roll brushing device such that the segmented brush rolls are disposed along the width direction of the roll and the space between the segmented brush rolls is brushed by the auxiliary brush roll; And The segmented brush rolls are superimposed on the roll surface, subjecting the size d of the overlap portion to change linearly from the center of the roll to the edge, and the auxiliary brush operates the roll brushing device so that it simply contacts the roll surface. Roll surface brushing method of a twin-roll continuous casting machine comprising the step of brushing the roll surface The method according to claim 1, wherein the segmented brush roll joint is connected to the middle of the brush roll rotation axis and is capable of being bent during rotation, a bearing body having the universal joint, and a segmented brush roll connected to the bearing body during casting. Roll surface brushing method of a twin roll continuous casting machine, characterized in that it consists of a segmented brush roll actuating cylinder which enables forward and backward movement in the roll direction. 3. The auxiliary joint of claim 2, wherein the auxiliary brush roll joint is connected to the auxiliary brush roll, the universal joint, the bearing body with the universal joint, and the auxiliary body connected to the bearing body to allow the auxiliary brush roll to move back and forth in the roll direction during casting. Roll surface brushing method of a twin-roll continuous casting machine, characterized by comprising a cylinder for brush roll operation The method according to any one of claims 1 to 3, wherein The thickness t ₀ of the roll coating layer before casting was measured, and the hot band portion of the cast steel was observed; Using the hot band section observation result of the cast, the point where the hot band section starts to appear in the edge direction at the center of the roll is set on the roll surface; And At the point where the hot band portion set as described above starts to occur, the overlap portion size d becomes 0, and at the edge portion, the size of the overlap portion falls within 1000 times the thickness t ₀ , and the overlap portion size d The brush surface brushing method of a twin roll continuous casting machine, characterized in that it sets a condition to increase linearly from the point where the hot band portion starts to occur to the edge portion, thereby overlapping the segmented brush rolls on the roll surface. The method according to any one of claims 1 to 3, wherein the brush roll joint is moved toward the roll to make it convex, and then the entire segmented brush roll is moved to the roll side with a constant force so that the segmented brush rolls overlap the roll surface. Roll surface brushing method of twin roll continuous casting machine