JPS58218360A - Continuous casting device for thin steel plate - Google Patents

Abstract

PURPOSE:To produce a thin steel plate directly from molten steel stably at a high speed, by providing a casting mold formed of circulating bodies and holding parts of an inverted triangular shape for molten metal, and enabling the adjustment for the position where solidification starts and the pevention of the seizure of a solidified shell. CONSTITUTION:A titled casting device forms a casting cavity with a pair of circulatong bodies 1, 2 which are disposed so as to face each other and circulate while maintaining a gap between the same for a specified distance, and stationary side plates 3 which are positioned in both sude edge parts between the circulating bodies and are lined with metallic plates 12 for quick cooling. Each plate 3 consists of a holding part 4a of an inverted triangular shape for molten metal and a part 4b for growing a solidified shell having the width equal to the thickness of the solidified ingot in succession to said part. A lining 11 of a refractory material is provided on the inside surface in the central part of said plate. The thin steel plate is produced stably at a high speed from molten steel by the above-mentioned device.

Description

[Detailed Description of the Invention] The present invention relates to a continuous thin steel plate casting apparatus,
In particular, the above-mentioned equipment, which directly manufactures thin steel sheets from molten steel without going through the process of tilting or rough rolling, is characterized by its high speed, excellent solidification shell breakage resistance, and improved fixed side plates. It's a suggestion.

A common method for manufacturing thin steel sheets is to manufacture an ingot or slab from molten steel, and hot and cold roll this into a thin sheet of a predetermined thickness.

For example, when obtaining a thin steel plate with a thickness of about 0.5 to 2 mm by continuous casting, first a slab with a thickness of about 150 to 800 mm is produced from molten steel using a continuous casting machine, and this slab is hot-rolled. Compared to the method of casting an ingot by ingot making and obtaining slabs by blooming, this method requires soaking furnace ↑ blooming. It is excellent in labor and energy saving as it does not require much energy.

However, the slab manufactured by continuous casting in the above example,
Since the surface temperature is often lowered to about 700° C. or cooled to near room temperature, there is a drawback that hot rolling requires a soaking or heating furnace to a rolling temperature.

Furthermore, since the f'Lfc slab obtained by continuous casting has the thickness described above, several rough rolling steps are required to produce a thin steel plate with the desired thickness [21. Accordingly, the equipment cost of the rolling equipment becomes high.

Therefore, if thin steel plates with a thickness of several tens of meters could be manufactured directly from molten metal without going through the various processes mentioned above, it would be possible to reduce the thickness to the desired thickness without the need for a rough rolling process or a large heating furnace. Since the process is not complicated, the process is significantly simplified, and equipment costs and processing costs can be reduced. In addition, if a thin steel plate of a certain thickness is manufactured directly from molten steel, the solidified structure will be fine and there will be very little segregation of components, so there will be no traps, such as surface defects caused by uneven solidified structure, and it will be excellent. A thin steel sheet with improved properties can be obtained.

Based on this perspective, various attempts have been made to directly manufacture 1□1 thin steel sheets from molten steel, but the current situation is that they have not yet reached an industrial scale.
One of the reasons for this is that the thickness ranges from several'F to several tens of degrees, and the width ranges from several'F to several tens of degrees.
,.

In order to stably manufacture thin square steel plates ranging from all-purpose to over 1,000 thick, it is important to stably and continuously supply molten steel corresponding to the width. However, when manufacturing thin steel sheets with small thickness and wide width, if a slit-type nozzle, for example, is used to meet the demand, the molten metal is It had fatal flaws, such as being prone to solidification and clogging, and being severely eroded and unable to withstand continuous use for long periods of time.

The main purpose of the present invention is to provide a continuous thin steel sheet casting apparatus that can advantageously overcome the drawbacks of the direct manufacturing technology for thin steel sheets using conventional slit-type nozzles as described above, and is particularly suitable for drawing thin steel sheets. The construction of a device with fixed side plate features suitable for smooth continuous casting of thin steel sheets without the risk of solidified shell breakage, bulging, or breakout. The gist of this is that over a certain distance, the cast gold, ・1
, Circulating bodies that circulate while maintaining the gap between the tapes that hold the genus: '1 A pair of circulating bodies arranged facing each other, and their circulating body phase 11
□ In a thin steel sheet continuous casting machine where a casting space is formed by a pair of fixed side plates positioned on both sides of the tiles, □ The above fixed side plates are used to hold molten metal in a roughly triangular shape with a concave shape at the top and bottom. and a solidified shell growth part with a width approximately equal to the thickness of the solidified slab. The lining of the object is provided in a manner protruding from the quenching structure (h). The details of the configuration will be explained below.

Fig. 1 of the drawings shows a preferred embodiment of the continuous casting apparatus of the present invention, and 1.2 in the drawing shows a sump part for holding the cast metal over a certain distance. It is a circulating body (corresponding to the long side wall) that is placed in a pair of opposing positions that move endlessly and symmetrically (circulate). Reference numeral 8 designates a fixed side plate for regulating the short side wall of the slab, which is located at the side edge between the opposing circulation bodies 1.2, and is generally triangular in shape with a wide upper part and a concave lower part. A casting space is formed by both fixed side plates 8 of the mouth and the pair of circulation bodies.

The molten metal holding area 4a located in the upper part that corresponds to the casting space, that is, the molten metal pool, has a cross section and shape on the side that corresponds to the plate thickness surface, and has a substantially triangular concave shape formed by the fixed side plate 8.4, and the narrowest part thereof is A pair of thickness adjusting rolls 6.51 are arranged in the area having the smallest area. The interval between the thickness adjustment plates Il+ and 15' is approximately equal to the thickness of the product plate.The portion continuing below the molten metal holding area 4a is a solidified shell growth area 4b, in which the circulating body 1, The solidified shell 6 generated and grown along the inner surface is rapidly cooled and becomes a thin steel plate, which is sequentially extracted from below as the circulating bodies 1 and 2 move.

A water-cooled cooling plate 8 is provided on the back surface of the circulating body 1.2 corresponding to the molten metal holding region 4a and the solidified shell growth region 4b, respectively.
, 9 are installed to cool the circulation bodies 1 and 2. 10 in the figure is an injection nozzle. 0 In the case of the apparatus described above, the fixed side plate 8 corresponding to the molten metal holding area 4a has an inverted triangular casting space. Defects are eliminated.

However, in such a casting device, the solidified shell 6 produced
In order to perform smooth continuous casting without breaking or bulging, the solidified shell growth from the fixed side plate 8° should be outside the thickness adjustment plate.

It is desirable to start at a position in series with or immediately after the minimum gap of the 5' installation. For example, if the solidification start point occurs far before the minimum gap, the solidification shell is likely to break and the thickness adjustment rolls Is, Is
This increases the load on ', making stable continuous casting difficult.

On the other hand, if the solidification of the surface in contact with the fixed side plate 8 occurs at a position directly below the thickness adjustment four-wheels 6, 5/, the solidified shell 6 and Seizure with the surface of the fixed side plate 8 is insufficient, which causes the solidified shell 6 to break. Furthermore, the lower the cooling rate of the stationary side plate 8, the more likely the burning occurs.

In the above sense, in order to achieve smooth continuous casting of a thin steel plate with an excellent end face shape, it is necessary to adjust the solidification start position and to prevent the quenching surface of the fixed side plate 8 from coagulating with the solidified shell. is important. In order to achieve the 11°
1□ is important.

Therefore, the fixed side plate 8 of the present invention has a molten metal holding area 4a.
The structure is made up of a lining part 11 in which the refractory material protrudes from the inner surface, and a part in which the quenched metal plate 12 is directly exposed in the casting space, and continues below this molten metal holding area 4a. The solidified shell growth region 4b was composed only of the quenched metal plate 12 in order to promote the growth of the solidified shell 6. The relationship between the refractory lining portion 11 of the fixed side plate 8 of the molten metal holding area 4a and the exposed quenched metal plate portion 12a is as follows:
The quenched metal portion exposed portions 12 are provided on both side edges along the circulation bodies 1 and 2.
a is located. That is, the relationship is shown in FIG. The ratio of both in the A-A section shown in Fig. 2 is the product board thickness l
It consists of an exposed quenched metal plate portion 12a with a width of 1/2 or less, and a refractory lining portion 11 inside the exposed portion 12a. Note that the fixed side plate 3 in the curved solid shell growth region 4b following the molten metal holding region 4a is composed only of the rapidly cooled metal plate 12.

The solidified shell 6 that grows on the quenched metal surface 12' of the fixed side plate 3 is formed on the quenched metal plate 12 when the product plate thickness l is 120 mm or less.
' and burn-in will not occur. It is board thickness 120
mm or less, the width of the quenched metal exposed portion 12a in the molten metal holding area 4a is 60 mm or less, and the exposed portion 12
The cooling rate at point a is influenced by cooling from both the circulating body 1.2 side, and becomes two-dimensional as shown by the arrow in Fig. 4(a), and the cooling rate increases. The solidified shell 6 generated in the exposed quenched metal portion 12a becomes the fourth
As shown in Figure (b), this is due to being strongly constrained by the solidified shells 6 formed on the circulating bodies 1 and 2. - And the lower end of the molten metal holding area 4a, that is, the thickness adjustment pin Is,
The shape of the solidified shell 6 at the Is' position covers the entire outer periphery of the steel plate as shown in FIG. 6, and the solidified shell 6 is prevented from being burned to the quenched metal plate 12' in the solidified shell growth region 4b. .

Therefore, by using the fixed side plate 8 of the present invention, it is possible to continuously cast a steel plate of any thickness even if a normal injection nozzle 10 is used, and it is possible to continuously cast a steel plate of any thickness, without causing breakage or breakout of the solidified shell 6 when drawing the steel plate. It is possible to stably produce a thin steel plate with a good end face shape at high speed without any problems.

Example (1) In the continuous casting apparatus shown in FIG.
Molten steel was cast using the solidified shell growth region as a quenched metal plate. In this example, when the steel plate thickness was 60 mm or more, a break occurred in the solidified shell in contact with the fixed side plate immediately below the thickness adjustment roll position, that is, at the beginning of the solidified shell growth region 4b, regardless of the casting speed.

As a result, the end surface morphology of the manufactured steel sheet deteriorates, and breakouts may occur. This is because the molten steel came into direct contact with the rapidly cooled metal plate constituting the side plate of the solidified shell growth region 4b, and as shown in FIG. 6, seizure occurred between the solidified shell formed here and the rapidly cooled metal plate.

(2) On the other hand, with the fixed side plate structure of the present invention, when the plate thickness is 199 gm or less in molten steel casting, the solidified shell generated on the quenched metal plate will not show any seizure in each region, and the solidified shell will not be solidified. The shell breakage was completely resolved. At this time, the amount of refractory material in the fixed side plate part of the molten metal holding area was made to protrude by 2011u11 or more from the exposed quenched metal part. on the other hand,
When the thickness of the steel plate is 120 mm or more, the solidified shell breaks on the exposed part of the quenched metal in the molten metal holding area, making it impossible to obtain a steel plate with a stable end face shape.〇(8) In addition, the continuous casting apparatus of the present invention: When continuous casting of molten steel was carried out under various conditions, the steel plate width was 10
00, the steel plate thickness is 20 to 1 gQsm, and the casting speed is limited by the steel plate thickness and the length of the equipment cooling zone (areas 4a and 4b), but for example, in the case of the plate thickness FiQsw, the maximum I Is
It has been found that stable casting is possible down to m/min.

As explained above, according to the present invention, it is possible to stably produce thin steel plates from molten steel at high speed, and in particular, there is no breakage of the hardened shell on the fixed side plate surface, and the steel plate has a good end face shape. It is possible to manufacture

[Brief explanation of the drawing]

Power. Figure 1 shows line 1 showing the casting state of the thin steel plate continuous casting equipment.
Figure 2 is a perspective view of the fixed side plate of the present invention, Figure 8 is a
FIG. 3 is a sectional view taken along line A-A of the fixed side plate of the present invention. FIG. 4(a) is a partial sectional view showing the heat flow pattern of the stationary side plate in the state shown in FIG. 8, and FIG. Figure 6 is a cross-sectional view showing the bite length of the solidified shell of the present invention example at the position of the thickness adjustment stomach roll, and Figure 6 is a cross-sectional view of the comparative example. 1.8... Circulating body 8... Fixed side plate 4a...
- Molten metal holding area 4b...solidified shell growth area 6.6
I... Thickness adjustment port □-Rule 6... Solidified shell 6/... Molten metal 7... Solidified metal plate 8... Cooling plate
9...Cooling plate 10...Injection nozzle
11... Refractory lining part 12... Rapidly cooled metal plate
1i[1a...Quiet-cooled metal plate exposed part 1

Claims (1)

[Claims] t A pair of circulating bodies arranged opposite to each other that circulate while maintaining a gap for holding cast metal over a certain distance, and a pair of circulating bodies located on both side edges between the circulating bodies. In a thin steel sheet continuous casting machine that constitutes a casting space with a fixed side plate, the fixed side plate has a substantially triangular molten metal holding portion that is shaped like a sill at the top and a width that is approximately equal to the thickness of the solidified slab. The molten metal holding part is characterized by having an internal tension of a refractory on the inner surface of the central part of the molten metal holding part, excluding both side edges along the circulation body. Thin steel! Continuous casting equipment.