JPS6123556A - Method and device for manufacturing thin steel casting piece - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Flame i-light I This invention relates to a continuous casting method and apparatus for thin steel slabs.

BACKGROUND OF THE INVENTION Hitherto, methods and devices for the continuous casting of metal slabs are often divided into two different groups. 1st
In this method, which is a historically early group, molten metal to be cast is continuously injected into the upper open end of the mold channel of a cooling mold disposed substantially vertically. In the cooling mold, heat is absorbed through the cooled walls of the mold channel to form a continuous slab consisting of a solidified shell surrounding the molten metal core. The initial slab thus formed is continuously drawn downward from the lower open end of the mold channel, where it enters the secondary cooling zone where it is further cooled and solidified by being directly exposed to the cooling fluid. to form a solidified surface. Jungh
aus U.S. Patent Nos. 2,1341,183 and 2
, 135,184 represents the earliest commercially successful continuous casting process of this group.

This group usually uses curved mold channels or other methods to reduce the overall height of the device.
to curve the slab moving downward,
The slab moves along a curved path through the second cooling zone. It is then straightened to travel in a substantially horizontal path, where it is cut into manageable lengths. Second
In the cooling zone, cooling water is sprayed onto the slab between a structure sometimes called a roller apron. Such roller aprons are cumbersome (and expensive) to construct and maintain.

Virtually all commercial continuous casting equipment is of the vertical type as described above.

The second group may be referred to as a horizontal group since the mold flow path through the cooled mold is arranged substantially horizontally. However, the theoretical advantages of horizontally disposed mold channels are outweighed by the substantial difficulties encountered in their use, particularly when feeding molten metal into the mold channels. This group of devices and methods has found very little commercial use.

OBJECTS OF THE INVENTION It is an object of the invention that molten metal is introduced into a mold channel extending vertically or horizontally through a cooling mold, from which the initial slab is directed either downwardly or horizontally. It is a different approach to the problem of continuous metal casting that departs from traditional methods such as drawing from a mold channel.

The present inventor forms an initial slab on a cooling surface immersed in a pool of molten steel, and then pulls the slab upward along a continuum of the cooling surface extending above the surface of the pool, and processes the solidification process. It is intended to differ from these known methods by continuing and completing the process.

Another object of the invention is to retain sufficient residual heat to reshape the slab when it leaves the cooling surface, thereby reheating the slab before it is necessary to reheat it. It is to mold.

SUMMARY OF THE INVENTION The present invention is particularly suited to the production of relatively thin steel slabs of 1/2 to 1 inch (12.7 to 25.4 am) thickness; its application will be described in more detail below.

In accordance with the present invention, the inventors contact the molten steel of the pool with a laterally flat cooled surface having a first portion immersed below the surface of the pool and form an initial slab thereon; and said dipping at a rate such that sufficient heat is absorbed through said flat dipped surface to form a partially solidified slab of the required thickness and weight on said surface. It is proposed to draw the initial slab upwards along a second part of said cooling surface constituting a continuum located on the surface of the sump and on the surface of the pool.
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) The inventor also proposes that a vertical wall extending at least along the side edge of the immersed portion of the cooling surface and projecting above said surface be configured to suppress heat transfer from the slab other than through said cooling surface. It is proposed to provide movement resistance means.

The inventor also provides that the first portion of the cooling surface, i.e. the immersed portion thereof, is curved convexly to form a short longitudinal arc, and that the lower end of the arc is substantially a pool of molten steel. is positioned perpendicular to the horizontal surface of the cooling surface, so that while the cooling surface collects metal from the pool and until it comes out of the pool, the initial slab is moved substantially vertically along the immersed portion of the cooling surface. I suggest moving it in the same direction.

The inventor also proposed that the second portion of the cooling surface be curved convexly to form an arc of the same radius as that of the immersed arc, whereby the initial slab is moved from the immersed portion to the second portion.
As the slab advances to and along the surface, the crystalline structure of the slab is formed by heat absorption through the cooling surface and bending and other effects occur during solidification. We also suggest ways to avoid distortion.

The inventor also proposed that the solidified slab be moved directly from the cooling surface,
To allow the slab to pass through the forming rollers while retaining sufficient residual heat so that it can be easily formed without the need for reheating, thus greatly reducing manufacturing costs. propose.

Preferably, the curved cooling mold surface extends through 45° to 15° of the total arc, so that the slab leaves the second part of the cooling surface and travels towards drawing rolls or a work area, such as a rolling mill. You will be able to do this. The amount of heat absorbed from the slab is controlled so that the slab retains enough residual heat to be reshaped by rolling without reheating.

Preferred Embodiments of the Invention Preferred embodiments of the invention, selected for illustrative purposes, are shown in the accompanying drawings.

Figure 1 is a semi-illustrated longitudinal sectional view showing the method and equipment during normal operation, Figure 2 is a similar view of the equipment section showing the method during startup, and Figure 3 is the upper side of the starter equipment. Figure 4 shows a guide strip controlling lateral heat transfer from the cooled mold surface to line 4 of Figure 1.
It is a sectional view at -4.

DESCRIPTION OF FIG.
Supplied from -2. The flow of metal into the reservoir is controlled in any suitable manner. i.e. by any known means capable of responding to the level of molten metal in the reservoir, i.e. when the level is about to fall below a preset level, the flow rate of metal entering the reservoir is increased and the level rises above the preset level. When leaking, the metal flow rate is controlled manually or automatically to reduce the metal flow rate.

A horizontal mold 3 having a flat thermally conductive preferably copper wall 4 laterally on one side C of the reservoir and a flat lower part 5 extending to the bottom of said reservoir and immersed in the molten metal. It constitutes the cooling mold surface.

The molten metal mold is thus in contact with the cooling surface 5, so that heat is absorbed through said surface and a nascent slab 6 begins to form thereon.

The side edges of the cooling mold wall 4, at least along its immersed part, are encircled by vertical walls 25 of guide strips 26 extending along said side edges and projecting above said cooling surface, to guide the side edges of the slab. Press down and smooth.

It is important, however, that heat is only absorbed downwardly through the cooling surface 4 of the mold and not laterally from the slab through the strip 26. They are therefore preferably made of a material that is resistant to heat conduction, such as bulk material. strip 26
The surfaces of the immersed portions of the slab are in contact with and heated by the molten metal in the pool, and there is little or no tendency for heat to transfer through them from the slab. However, if necessary, electrical heating elements can be fitted into the strips, especially those on the surface of the pool.

However, as an alternative, said strip may
, 1 may be made of metal such as steel. In this case, it is also possible to embed a heating element therein to maintain the strip at a sufficient temperature even if it is immersed, and to prevent heat transfer in the lateral direction of the slab.

It should be noted that in such a configuration the initial slab is fully formed when it reaches the level of the pool metal. That is, no metal is added to the slab above the pool level. However, metal previously deposited in a liquid or partially solidified state may then solidify with additional heat transfer as it moves along the second portion of the cooling surface above the level of the puddle.

The strip 26 may extend along the side edge of the mold wall as long as necessary. However, since complete solidification of the slab occurs within a reasonably short distance beyond the level of the slag,
The strip does not need to run the entire length of the mold wall.

Type I! 14 is horizontally flat but vertically curved to form an arc of 45° to 75″.

The lower portion of the cold fJJ surface, indicated at 5, occupies a short portion of the total cooling surface of the mold, and the lower end of the arc is located substantially perpendicular to the bottom of the reservoir and the surface of the molten metal pool. Ru. It extends only through a 10' to 20' arc, so that the initial slab moves along a substantially longitudinal submerged cooling surface, collecting metal from the pool. Since the two convexly curved surfaces 5 and 7 are arranged on the same radius, the initial slab maintains its contour while moving between the two sections, and its crystal structure is formed and solidified due to mass cracking and other distortions. I will not receive it. Bending of the slab is required only when it reaches the drawing rolls 9, but by then the solidification of the slab has been completed.

If necessary, the surfaces of the mold walls 4 may be lubricated by methods known in the art.

The mold 3 is supported in a suitable manner. The portion of the slab 8 between the surface 7 and the drawing roll 9 may be supported by one or more rollers, such as roller 10.

As shown in FIGS. 2 and 3, at the beginning of the operation, a plurality of chains 11 are arranged to extend along the cooling surface 7 to the bottom of the storage tank 1 to begin the process of solidifying metal forming on the surface 5. It becomes wrapped up in parts. chain 1
The other end of 1 extends upwardly to the upper pull-out hole 9 of the cooling surface 7. At the beginning of the operation, the level of molten metal in reservoir 1 is relatively low, as shown in FIG. When sufficient solidified metal has accumulated at the lower end of the chain to form the activator bar 12 extending transversely to the face 5, the drawing rolls 9 are actuated and begin to pull out the activator bar. At the same time, the level of the molten metal mold begins to rise as shown in FIG. 1, and an initial slab 6 continues to form due to the absorption of heat through the mold 5.

As the work progresses, the thickness of the slab is set by adjusting one or both of the following two factors:

(1) the depth of molten metal in the puddle, and (2) the rate of withdrawal of the slab. The slower the drawing speed, the greater the thickness of the slab. Similarly, the greater the depth of the molten metal within the pool, the greater the thickness of the slab. The molten metal begins to solidify at the cooling surface near its bottom, forming an initial slab. The slab is initially very thin, but gradually thickens as it is pulled upward along the cooling surface until it reaches its maximum thickness when it emerges from the pool. Thereafter, as it moves along the continuum 7 of the cooling surface 5, the slab is additionally cooled. If necessary, further cooling may be provided by spraying from a nozzle.

However, the inventors have been able to control the total amount of heat absorbed by the spray from the slab 8 through 5 and 7 and from the nozzle 13 up to the drawing roll 9 so that when it leaves the drawing roll 9, It is proposed that the pieces still have sufficient residual heat so that they can be reduced or likewise reshaped without being reheated. Thus, when the slab 8 leaves the drawing rolls, it can be made to move directly between the paired rolls 14 and 15 which reduce its thickness. For example, if the device shown in the figure is used and when leaving the puddle,
If a slab such as a steel slab with a thickness of 2 inches is to be made, the thickness of the slab is reduced by rolls 14 and 15 to 4 inches (6,35'ai) or less per part. The thickness can be reduced to produce hot rolled sheet steel. For this purpose, forming roll 1
4.15 and the drawing roll 9 can also be installed as one piece in a support structure (not shown) which forms part of the support structure of the mold.

It will be understood that the invention may be modified and embodied in various ways within the scope of the appended claims.

[Brief explanation of the drawing]

FIG. 1 is a semi-illustrated longitudinal sectional view showing the method and equipment used during normal work. Figure 2 shows the method at startup! l'lj! FIG. 2 is a semi-illustrated vertical cross-sectional view that does not show a part of the device. FIG. 3 is a diagram showing the upper part of the activation body device. FIG. 4 is a cross-sectional view taken along line 4--4 of FIG. 1 showing a guide strip that inhibits lateral heat transfer from the cooled mold surface. 1...Storage tank 2...Spout 3...
Water-cooled mold 4...Copper wall 5.7...Cooling surface 6...Initial slab 8...Slab
9... Pulling roll 10... Roller 1
1...Chain 12...Start bar 13.
... Nozzles 14, 15... Forming roll 25...
Vertical wall 26...Guidance strip (5 people outside)

Claims (11)

[Claims] (1) A puddle of molten metal is brought into contact with a cooling surface having a first portion constituting a laterally flat and vertically curved convex arc and immersed below the surface of the puddle, through which heat is applied. a first part of said cooling surface extending upwardly beyond the surface of the pool and forming a continuum curved like said first part; successively along the second section at such a rate that sufficient heat absorption takes place through said first section so that a flat slab of the required thickness is formed thereon. A method for continuous casting of steel slabs with uniform cross-sectional thickness, characterized in that the method comprises drawing a steel slab with uniform cross-sectional thickness. 2. The method of claim 1, further comprising: (2) suppressing absorption of heat laterally from the initial slab along its side edges. (3) The immersed portion of the cooling surface extends substantially perpendicular to the horizontal plane of the pool and moves substantially vertically as the slab is withdrawn. or the method described in Section 2. (4) A method according to any one of claims 1 to 3, characterized in that the thickness of the slab is determined by controlling the speed at which the slab is drawn. (5) A method according to any one of claims 1 to 4, characterized in that the thickness of the slab is determined by controlling the depth of the pool of molten metal. . (6) the total amount of heat absorbed from the slab is controlled such that the slab retains enough heat after it leaves the surface to be able to be reshaped without being reheated; A method according to any one of claims 1 to 5, characterized in that: (7) a reservoir for receiving a pool of molten steel, curved longitudinally and laterally constituting a convex arc extending into and immersed within said reservoir to a level below the surface of the pool; said dip having a first portion constituting a flat cooling surface, through which heat is absorbed to form the initial slab, and likewise curved and extending upwardly beyond the surface of the pool; A uniform mold, characterized in that it comprises a mold having a mold wall with a second part forming a series of parts, and means for continuously drawing the initial slab upwardly along said cooling surface. Continuous casting equipment for steel slabs with a cross-sectional thickness. (8) extending along said side edges of said immersed portion of said cooling surface and extending to the top of said surface such that heat transfer is inhibited except through said flat cooling surface; 8. Apparatus according to claim 7, characterized in that it includes heat transfer resisting means. 9. The apparatus of claim 7 or 8, wherein the lower end of the immersed portion of the cooling surface extends substantially perpendicular to the horizontal plane of the pool. (10) said extraction means includes a set of extraction rollers generally aligned horizontally with the upper edge of said cooling surface;
Further, after the slab leaves the drawing roller, the slab is moved to the reshaping roller while the slab still retains sufficient residual heat to be reshaped without being reheated. Claims 7 to 9 include a set of reshaping rollers generally aligned horizontally with the combination of drawing rollers for reshaping the billet by passing it through a The device described in any of the above. (11) A device for pulling an initial bar formed on the cooling surface from a pool of molten metal upwardly from the storage tank along the cooling mold surface, and moving the initial bar to the combination of drawing rollers. 11. Apparatus according to any one of claims 7 to 10, characterized in that it includes a starting bar arrangement inserted into the reservoir along the cooling mold surface.