JP2968103B2 - Twin roll continuous casting method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a twin roll continuous casting method and apparatus, and more particularly to an improvement in a method of lubricating a sliding portion between a side dam and a cooling roll. In the twin roll continuous casting method, a continuous casting mold is constituted by a pair of cooling rolls arranged at predetermined intervals with their rotation axes horizontal and parallel to each other, and a pair of side dams pressed against both end surfaces of these cooling rolls. This is a continuous casting method in which the annular region of the end face of the cooling roll circulates and slides on the pressing surface of the side dam to seal the mold.

[0002]

2. Description of the Related Art In a twin roll continuous casting method, a side dam is brought into close contact with an end face of a cooling roll to prevent molten metal from leaking out of a pool, and at the same time, to ensure a sealing effect by a side dam so that a side edge of a slab has a desired shape. is necessary. The pressing surface of the side dam and the annular sliding region of the end face of the cooling roll circulate and slide under the pressing force of the side dam to ensure a sealing effect. If the wear of the sealing surface progresses due to the sliding, the life of the cooling roll and the side dam is shortened, and a good sealing state cannot be ensured. Therefore, it is necessary to suppress abrasion by performing appropriate lubrication.

Heretofore, in order to perform this lubrication, there has been proposed a method in which a solid lubricant is adhered to the sliding area of the cooling roll by pressing and rubbing the solid lubricant block against the annular sliding area on the end face of the cooling roll. (Japanese Patent Laid-Open No. 63-
248747). In this method, the solid lubricant particles are carried to the sliding position with the side dam by the rotation of the cooling roll while being attached to the end face of the cooling roll. In the sliding position, the side dam is brought into close contact with the end face of the cooling roll with a pressing force capable of securing a sealing effect. Since the solid lubricant particles are simply rubbed and adhered to the end face of the cooling roll, a large adhesive force cannot be obtained. When entering between the side dam pressing surface and the cooling roll sliding area, which are in close contact with a considerably large pressing force, much of the adhered particles are scraped off from the cooling roll end surface due to the resistance force. Can not contribute to proper lubrication.
Further, since the solid lubricant is simply rubbed, the amount of the lubricant adhered and supplied to the end face of the cooling roll is small, and a lubricating film having a thickness sufficient to prevent the leakage of hot water from the sliding portion (lug). Can not secure.

As described above, according to the conventional technique, the thickness of a lubricating film that can be formed is limited in the first place, and the supplied lubricant cannot sufficiently contribute to lubrication. There is a problem that the moving part cannot be effectively lubricated, shortening the life of the cooling roll and the side dam, and failing to sufficiently prevent poor sealing due to abrasion, that is, the occurrence of hot water.

[0005]

SUMMARY OF THE INVENTION According to the present invention, there is provided a lubricating film having a thickness capable of effectively providing lubrication at a sliding portion between a cooling roll and a side dam and suppressing abrasion to ensure a sealing effect. An object of the present invention is to provide a twin-roll continuous casting method and apparatus in which the lubrication method is improved so that the thickness can be constantly maintained during casting.

[0006]

In order to achieve the above object, a twin-roll continuous casting method according to the present invention comprises a pair of cooling rolls arranged at predetermined intervals with their rotation axes being horizontal and parallel to each other. A twin-roll continuous casting system that forms a continuous casting mold with a pair of side dams pressed against both end surfaces of the cooling roll, and the annular region of the cooling roll end surface circulates and slides on the pressing surface of the side dam to seal the mold. In the method, a portion of the rotating cooling roll end surface annular sliding region which is different from the region currently sliding with the side dam is in a solid state at the temperature of the cooling roll end surface annular sliding region and has a side dam pressing surface. By spraying a lubricant that is in a fluid state at a temperature, a continuous lubricating film is formed on the entire circumference of the annular sliding area on the end face of the cooling roll, and the thickness of the lubricating film is maintained at the required thickness during casting. And controlling the spraying amount so that.

An apparatus for carrying out the twin-roll continuous casting method of the present invention comprises a pair of cooling rolls arranged at predetermined intervals with their rotation axes being horizontal and parallel to each other, and pressed against both end surfaces of these cooling rolls. A pair of side dams constitute a continuous casting mold, and a twin-roll continuous casting apparatus that seals the mold by circulating and sliding an annular region of the end face of the cooling roll on the pressing surface of the side dam is rotating. Lubrication that is in a solid state at the temperature of the annular sliding surface of the cooling roll end face and is in a fluid state at the temperature of the side dam pressing surface, in a part of the annular sliding area of the cooling roll end face other than the part currently sliding with the side dam. A thermal spraying device that sprays an agent to thereby form a continuous lubricating film on the entire circumference of the cooling roll annular sliding region, and a portion of the annular sliding region that is currently sliding with the side dam. Along et cooling roll rotation direction in a section leading to the spraying site, a device for detecting the thickness of the lubricating film,
And a device for controlling the amount of thermal spraying of the thermal spraying device so that the thickness of the lubricating film is maintained at a required thickness based on the film thickness data from the detecting device.

[0008]

In the present invention, since the lubricating film is formed on the end face of the cooling roll by thermal spraying, the lubricating film can be made much thicker than in the case where a conventional solid lubricant is simply rubbed. In addition, since it is a sprayed film, it is very firmly fixed to the substrate, and it does not be scraped off by the resistance force when it enters the close sliding part between the side dam and the cooling roll. It can contribute to lubrication.

The lubricating film is made of a lubricant that is in a solid state at the temperature of the annular sliding area on the end face of the cooling roll and is in a fluid state at the temperature of the side dam pressing surface. Thereby, of the entire thickness of the lubricating film, the side fixed to the end face of the water-cooled low-temperature chill roll is firmly held in a solid state, and the side in contact with the high-temperature side dam pressing face heated by the molten metal. In this state, the material is brought into a fluidized state by softening or melting to perform a lubricating action.

[0010] The spraying of the end face of the cooling roll onto the annular sliding area may be performed at any part of the area other than the part currently sliding on the side dam pressing surface. To determine the spraying site. The lubricating film formed by thermal spraying is in a fluid state, and a portion of the film thickness that has performed a lubricating action is consumed. The thickness of the lubricating film in a state after the lubrication and before the thermal spraying is measured, the amount of thermal spraying is controlled so as to recover the above consumption, and the film thickness immediately before the lubrication is always maintained at a required thickness.

Depending on the size of the required initial film thickness or recovery film thickness, a large film thickness can be obtained by arranging a plurality of thermal spraying devices along the circumference of the cooling roll and over-stripping. Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a twin-roll continuous casting apparatus according to the present invention; FIG. FIG.
FIG. 2 is a perspective view showing an arrangement relationship of various parts in general twin-roll continuous casting, FIG. 2 is a front view of the twin-roll continuous casting apparatus of the present invention viewed from a cooling roll end face direction, and FIG. FIG. 4A is a sectional view showing an arrangement relationship between the cooling roll and the side dam, FIG. 4B is a partially enlarged view thereof, and FIG. 5 is a lubricating film and its vicinity. It is sectional drawing which expands and shows.

Generally, in twin roll continuous casting, FIG.
As shown in the figure, a pair of cooling rolls 1 (diameter D)
Are horizontally and parallel to each other and are arranged at predetermined intervals. Both cooling rolls 1 rotate in the directions of arrows Ya and Yb, respectively. A pair of side dams 3 are pressed against both end faces 5 of the cooling roll 1 by a side dam pressing device (not shown) to form a continuous casting mold penetrating vertically. Molten metal is continuously poured into the mold from a tundish (not shown) to form a pool 6. Hot water pool 6
In the inside, the molten metal solidifies on the surfaces of both cooling rolls 1 and a pair of solidified shells grow, and these solidified shells are united almost at the closest positions of both cooling rolls 1 to form a single plate-shaped cast piece 8. Is sent downward by the rotation of the cooling roll 1.

As shown in FIGS. 2 and 3, the end face 5 (FIG. 1) of the cooling roll 1 is formed so that the outer edge thereof is protruded from the inner part thereof, and slides continuously with the side dam 3 to continuously move. It forms an annular sliding area 10 for sealing the casting mold. The annular sliding area 10 of the cooling roll 1 slides on the pressing surface 11 of the side dam 3. That is, the part (sliding part) that is currently sliding on the side dam 3 at a certain point in time when the annular sliding area 10 is located is a part corresponding to the pressing surface 11 of the side dam 3 shown by oblique lines in FIG. 11 for convenience
Notation.

In the present invention, a spraying device 12 is shown in FIG. 2 for each of the cooling rolls 1 in order to spray the lubricant on the annular sliding region 10 at a portion different from the sliding portion 11. Is located in the position. In this case, two thermal spraying devices 12 are provided for each cooling roll 1. The film thickness detecting device 13 disposed in a section from the sliding portion 11 of the annular sliding region 10 to the thermal spraying portion (12) along the cooling roll rotation direction (Ya, Yb) has a lubricating action at the sliding portion 11. The thickness of the lubricating film after the operation is detected. As the film thickness detecting device 13, for example, an ultrasonic sensor or the like can be used.

As shown in FIGS. 4A and 4B, the annular sliding area 10 of the cooling roll 1 slides on the pressing surface 11 of the side dam 3 to seal the molten metal in the pool 6. Between the annular sliding area 10 and the pressing surface 11 ("x" in FIG. 4B)
A direct contact between the two is avoided by interposing a lubricant at the position (marked with) to suppress wear during sliding. In general, it is particularly important to suppress wear of the cooling roll 1 from the viewpoints of manufacturing and maintenance costs and labor.

FIG. 5 shows a lubricating film 20 formed on the annular sliding area 10 of the cooling roll 1 according to the present invention. When the upper layer 21 comes into contact with the high-temperature side dam 3, the lubricating film 20 softens or melts into a fluid state to perform a lubricating action, and the lower layer 22 is maintained in a solid state by the low-temperature cooling roll 1 and held on the end face of the cooling roll. You. The film thickness after performing the lubricating action is detected by the film thickness detecting device 13 (FIG. 3) and sent to the thermal spraying control device 14 as the film thickness data i. The thermal spray control device 14 sends a control signal j for controlling the thermal spray amount to the thermal spray device 12 based on the film thickness data i. Thereby, the thermal spraying device 12
Performs spraying with the spray amount necessary to restore the film thickness, and always maintains the necessary film thickness during casting.

The lubricant used in the present invention only needs to have an appropriate transition temperature between a solid state and a fluidized state, and a vitreous substance, metal or alloy adjusted to a desired transition temperature depending on the composition can be used. .

[0019]

As described above, according to the present invention,
A lubricating film can be formed at a thickness that can effectively lubricate the sliding portion between the cooling roll and the side dam and suppress abrasion of both, thereby ensuring a sealing effect, and the film thickness can be constantly maintained during casting. As a result, the life of the cooling roll and the side dam can be extended, and furthermore, the defective shape of the side edge of the slab due to leakage of hot water can be prevented.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an arrangement relationship of each part in general twin-roll continuous casting.

FIG. 2 is a front view of the twin-roll continuous casting apparatus of the present invention as viewed from a cooling roll end face direction.

FIG. 3 is an arrangement view showing an arrangement of each part with respect to a cooling roll of the twin-roll continuous casting apparatus of the present invention.

FIG. 4A is a cross-sectional view showing an arrangement relationship between a cooling roll and a side dam, and FIG. 4B is a partially enlarged view thereof.

FIG. 5 is an enlarged sectional view showing a lubricating film and its vicinity.

[Description of Signs] 1 ... a pair of cooling rolls (diameter D) 2 ... a rotating shaft of the cooling roll 1 ... a pair of side dams 5 ... both end surfaces of the cooling roll 1 Reference numeral 5 denotes an annular sliding region forming an outer edge portion of the reference numeral 11... A pressing surface (sliding portion) of the side dam 3 12. A thermal spraying device 13. 22: Solid state portion of lubricating film

Continuation of the front page (72) Inventor Takashi Arai 3434 Shimada, Hikari-shi, Yamaguchi Prefecture Inside Nippon Steel Corporation Hikari Works (56) References JP-A-4-81250 (JP, A) Japanese Utility Model Showa 63- 71948 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) B22D 11/06

Claims (2)

(57) [Claims] 1. A continuous casting mold is constituted by a pair of cooling rolls arranged at predetermined intervals with their rotation axes being horizontal and parallel to each other, and a pair of side dams pressed against both end surfaces of the cooling rolls. In the twin-roll continuous casting method in which the annular region of the end surface of the cooling roll circulates and slides on the pressing surface to seal the mold, the sliding region of the rotating end surface of the cooling roll slides with the side dam. The cooling roll end surface is annularly formed by spraying a lubricant which is in a solid state at the temperature of the annular sliding surface of the cooling roll end surface and is in a fluid state at the temperature of the side dam pressing surface. Forming a continuous lubricating film on the entire circumference of the sliding area and controlling the amount of thermal spraying so as to maintain the thickness of the lubricating film at a required thickness during casting. Method. 2. A continuous casting mold is constituted by a pair of cooling rolls arranged at predetermined intervals with their rotation axes being horizontal and parallel to each other, and a pair of side dams pressed against both end surfaces of the cooling rolls. In the twin-roll continuous casting apparatus, in which the annular region of the cooling roll end surface circulates and slides on the pressing surface to seal the mold, the rotating roll surface slides against the side dam at the annular sliding region of the cooling roll end surface. A lubricant that is in a solid state at the temperature of the annular sliding surface of the cooling roll end surface and is in a fluid state at the temperature of the side dam pressing surface is sprayed onto a portion different from the portion where the cooling roll annular surface is rotated. A thermal spraying device for forming a continuous lubricating film over the entire circumference of the sliding area; In a section, a device for detecting the thickness of the lubricating film, and a spray amount of the spraying device so that the thickness of the lubricating film is maintained at a required thickness based on the film thickness data from the detecting device. Twin roll continuous casting apparatus, characterized by having a device for controlling the temperature.