JPS60180646A - Continuous casting device for thin sheet - Google Patents

Abstract

PURPOSE:To realize stable operation and improvement in the quality of a billet by the constitution in which the molten metal introduced from a pouring nozzle into a tundish vessel solidifies after passing through a filter consisting of porous refractories. CONSTITUTION:The molten metal flow falling from a pouring nozzle 3 into a tundish vessel 2 collides against a porous refractory filter 4 and the falling energy thereof is absorbed. The molten metal flows downward toward surface moving molds 1a, 1b after the dynamic flow is converted to static flow when the molten metal passes through said filter 4. The flowing phenomenon of the molten metal is therefore considerably decreased as compared to the case in which such filter is not used. The molten metal passing through the filter is adequately regulated by selecting the proper pore distribution of the filter 4.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for directly and continuously casting a wide thin plate from molten metal, particularly molten steel, using a one-rotation synchronous mold.

In continuous steel casting, proposals have been made to manufacture wide thin plates directly by casting instead of conventional thick slabs. For example, inventions for directly manufacturing thin plates from molten steel using a rotating synchronous mold consisting of twin rolls or twin belts are disclosed in Japanese Patent Application Laid-open No. 55-75862 and Japanese Patent Application Laid-open No. 57-9.
No. 566, JP-A-58-32548 and JP-A-58
- It is described in Sericulture Bulletin No. 32551, etc. These basic principles are based on a surface-moving mold formed by a pair of cooled casting rolls (or casting belts) that are arranged opposite to each other with a predetermined gap corresponding to the thickness of the slab and rotate synchronously in opposite directions. , is equipped with a molten metal reservoir installed above this surface moving mold, and a tundish that supplies molten metal to this molten metal container, and the molten metal poured into the reservoir container solidifies as the surface moving mold rotates. However, the mold is pulled out downwardly through the gap in the surface-moving mold.

There are various problems involved in realizing continuous casting of thin plates using such a rotationally synchronous mold.

Local non-uniform solidification due to the flow of molten steel in the molten metal tank, fluctuations in the thickness of the solidified shell due to non-uniform cooling rate in the width direction of the slab, and even the insertion of non-metallic inclusions due to the flow of the molten steel. This is a fundamental problem that must be solved, such as deterioration of slab quality due to

In order to minimize the flow of molten steel in the pool container and the cooling rate difference in the slab width direction, it seems effective to create a molten steel pool as large as possible in the mold, but this molten steel If the bottom area of the molten steel is expanded to make the pool larger (increasing it in the thickness direction of the slab), the area of molten steel in contact with the cooling surface-moving mold increases accordingly, causing excessive solidification. This may make it difficult to pull out the slab and cause deterioration of the surface quality.Also, if the height of the molten metal container is increased to increase the size of the molten steel pool, the static pressure of the molten steel The increase in the surface of the moving mold causes problems such as pouring from the gap between the surface of the moving mold and the sump container installed above it (the gap between the surface of the moving mold and the bottom of the fixed sump container), and Inserting hot water into these gaps can cause wrinkles and uneven board thickness.

This also has a close relationship with the injection temperature of molten steel, and its management is an important factor, and careful consideration must be given to the design and operation of this equipment.

Although it can be said that the operation of continuous casting equipment using this rotary synchronous mold is technically difficult, the problem of the flow of hot water injected into the bond mold has been solved and the flow of hot metal toward the mold has been rectified. If this is done, it can be said that the above-mentioned problems can be fundamentally solved, and the problem of non-metallic inclusions being trapped in the solidified shell due to the flow of hot water will also be solved.

The present invention aims to solve these problems. As a device for achieving this object very effectively, the present invention has a pair of casting rolls or casting belts placed opposite each other at a predetermined interval corresponding to the thickness of the slab, as shown in the embodiment of the drawings. The surface moving mold 1a, lb formed by the surface moving mold 1a, lb, a molten metal reservoir 2 formed on the surface moving mold 1a, lb, and an injection nozzle 3 for guiding the molten metal into the molten metal reservoir 2. In a thin plate continuous casting apparatus, a filter 4 made of porous refractory is placed inside the sump container 2 (=J), from the injection nozzle 3 to the sump container 2
To provide a thin plate continuous casting apparatus in which the molten metal introduced therein solidifies after passing through the filter 4. The apparatus of the present invention will be specifically explained below based on the drawings.

FIG. 1 is a schematic sectional view, not showing an example of the apparatus of the present invention using twin rolls as one-surface moving molds, and one-surface moving molds 1a, l.
b consists of a pair of rolls synchronously rotating in opposite directions, which are placed opposite each other with a gap corresponding to the thickness of the thin slab 5 to be cast, and whose two surfaces are continuously cooled. This surface moving mold 1a, lb'-3 is shown in Figure 2.
A sump container 2 showing It-8 is poured seven times. This water reservoir 2b has a side wall 6a substantially parallel to the axis of the roll.
, 6b and the side wall perpendicular to the axis of the roll? It is a container surrounded by a and 7b. The side wall island, 6b, is the surface moving mold 1a, IbO, which is about to head to the casting part.
The surface moving molds 1a, Ib are arranged in a direction perpendicular to the direction of movement of the molds 1a, Ib. On the other hand, the side walls 7a and 7b serve as walls for regulating the width of the slab 5. Molten metal is injected into this tundish container 2 through an injection nozzle 3 from a tamp 8 installed above it.

The device of the present invention is characterized in that a filter 4 made of porous refractory material is attached inside the water reservoir container 2.

That is, the molten metal injected into the sump container 2 through the injection nozzle 3 passes through the filter 4 and then flows toward the surfaces of the surface-moving molds 1a, lb. This filter 4 is A1203, 5i02, M
It is made of a refractory material such as gO, and has many holes through which hot water can pass. The overall shape of this porous refractory filter 4 is 1, for example, a plate-like body as shown in FIG. It should be stretched horizontally along the middle of the hot water container 2 as shown in the figure.

That is, the interior of the hot water reservoir 2 is divided into upper and lower halves by the porous refractory filter 4, and the tip of the injection nozzle 3 is directed toward the upper space. As a result, when casting is carried out under casting conditions such that the scene level inside the molten metal sump container 2 is porous and located above the refractory filter 4, the molten metal injected into the sump container 2 from the injection nozzle 3 After passing through this filter 4, the liquid flows toward the surface of the surface-moving molds 1a, Ib in the direction Lj.

The device of the present invention employs a very simple prescription using such a porous refractory filter 4, but even with such a simple prescription, the above-mentioned purpose of the present invention can be effectively achieved. will be achieved. That is, 3. The pouring liquid falling from the injection nozzle 3 into the hot water reservoir 2 first hits the porous refractory filter 4 and its falling energy is absorbed, and when passing through the porous refractory filter 4, .

The dynamic flow is converted into a static flow and then descends toward the surface moving molds 1a and lbO, so that the flow phenomenon of the hot metal is significantly reduced compared to the case without this. By appropriately distributing the pores of this porous refractory filter 4, the hot water passing through it can be properly rectified. That is, in the vicinity of the two-surface moving molds 1a and 1b, the molten metal reaches continuously under a flow pattern similar to a uniform extrusion flow, and is continuously solidified.

The flow absorption effect and rectification effect of the hot water prevent disturbances in temperature distribution and local uneven solidification, allowing stable growth of the solidified shell. And regarding the non-metallic inclusions suspended in @,
This is because it is suppressed from being caught up and flowing to the surfaces of the surface-moving molds Ia and IbO, and is also filtered by the filter 4.

This is automatically prevented from getting caught up in the solidified shell and deteriorating the quality of the slab.

Figure 4 shows an example of a porous refractory filter 4 that has a special shape instead of a simple flat plate.
The shape of the lower surface of this filter 4 is changed to two surface moving molds 1a so that the distance to reach the surface is almost equal everywhere.
, and the surface shape of Ib.

In turn, the shape is approximately similar to the shape of the solidified shell formed on this surface. In this case,
Further rectification can be achieved than simply using a flat plate. At this time, if it is inconvenient that the thickness of the filter 4 varies depending on the location, the filter thickness can be made uniform by forming a shape corresponding to the shape of the lower surface on the upper surface. Alternatively, as shown in Figure 1, the center and both edges of the filter 4 are composed of a composite of different types of refractories, including porous refractories 10 and 11 having different numbers of holes and pore diameters. , from this filter 4 to the surface moving mold 1a
, 1b may be controlled.

FIG. 5 shows an apparatus of the present invention that is substantially the same as the example of FIG. 1, except that a pair of rotationally synchronous healds are used in place of the rolls, and the apparatus of the present invention is substantially the same as the example in FIG. 1. By inserting the porous refractory filter 4 into the hot water reservoir 2 with the above-mentioned relationship, the flow of hot water can be prevented and the flow can be rectified.

As described above, the device of the present invention solves the basic problems of continuous thin plate casting devices using twin rolls or twin belts, which are stable operation and improvement of slab quality, by controlling the flow of molten metal using a very simple recipe. This was achieved by
This effectively achieves the stated purpose without complicating the device configuration.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing one embodiment of the device of the present invention. FIG. 2 is a perspective view showing an example of a hot water reservoir, FIG. 3 is a perspective view showing an example of a porous refractory filter, and FIG. 4 is a perspective view showing another example of a porous refractory filter. FIG. 5 is a schematic cross-sectional view showing another example of the device of the present invention. ■... Surface moving mold, 2... Water reservoir. 3. Injection nozzle, 4. Porous refractory filter, 5. Slab, 8. Kundesosh.

Claims (1)

[Claims] Surface moving molds 1a and lb formed by a pair of casting rolls or casting belts that are arranged opposite to each other with a predetermined interval corresponding to the thickness of the slab, and this surface moving mold 1a.
, a thin plate continuous casting apparatus equipped with a sump container 2 formed on top of a molten metal and an injection nozzle 3 for introducing the molten metal into the sump container 2. Attach the filter 4 made of material, and insert the injection nozzle 3
The molten metal introduced into the water reservoir 2 from the filter 4
Continuous thin plate casting equipment that solidifies after passing through the thin plate.