JPS60199554A - Spout for pouring device of twin belt caster - Google Patents

Abstract

PURPOSE:To suppress simply and easily formation of a solidified shell on a titled spout without erosion even in the stage of supplying a molten metal of high-Mn steel or the like by lining the working surface of the spout with a Zr refractory heat insulating material. CONSTITUTION:A molten metal 6 is poured by overflow from a pouring device 5 having a skimmer 3, a spout 4, etc. into the space between upper and lower endless belts 2, 2' which are moved by rotation of upper and lower pulleys 1, 1'. The molten metal moves in the same direction according to the movement of the belts 2, 2' and is cooled to solidify. A thin steel ingot 7 is continuously taken out. The spout 4 in this case is constituted by lining the working surface of a spout body 11 made of fused silica, etc. by a refractory heat insulating board material 12 consisting of zirconia or zircon as a compsn. component. The decrease in the temp. of the molten metal 6 flowing on the material 12 is virtually obviated by the high heat insulating effect and high corrosion resistance of the material 12 and the formation of a solidified shell on the working surface of the spout and the erosion of the spout are prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is used in continuously casting thin metal slabs by means of a twin-belt gear star. This invention relates to a molten metal supply gutter for a twin belt caster water heater.

<Industrial Application Fields> In recent years, a twin belt gear star as shown in Figure 1 has been put into practical use for casting thin sheets of nonferrous metals such as copper, zinc, and aluminum. Since it can be manufactured extremely efficiently, it is expected to be applied in various fields.

What is shown in Fig. 1 is a schematic representation of the casting state of a general twin belt gear star used for casting non-ferrous metal plates, and the gear is moved by the rotation of the upper and lower pulleys i and 1'. Endless belt 2. 2' open, Nugginma 3. When molten metal 6 is overflowed and injected from a water heater 5 having a gutter 4, etc., the molten metal is cooled and solidified as the endless belt moves in the same direction with no relative slip between the belt and the endless belt. As a result, the thin slabs 7 can be taken out continuously, effortlessly, and at high speed. The molten metal is supplied to the hot water supply device 5 using a ladle or a molten metal holding furnace.

Still designated by the reference numeral 8 is a dam block which together with the endless belt 2.degree. 2' constitutes the casting wall.

Furthermore, recently there has been a growing trend to produce thin sheets directly from steel slabs using only cold rolling without hot rolling, making it possible to cast wide and extremely thin slabs at opening speeds. Many attempts have been made to apply the above-mentioned twin belt caster to steel casting.

By the way, in such a twin belt caster, since it is necessary to uniformly inject the molten metal into the gap between the wide and extremely narrow lower belt, the number 4 in Figure 1 is used. As shown, a molten metal supply device that extended long toward the casting hole, had a low side wall height, and had a wide gutter attached to the front was considered essential equipment. FIG. 2 is a schematic perspective view showing an example of the most common shape of the gutter, which is composed of a bottom plate 9 and side walls 10, 10.

<Prior art> (-1) Conventionally, the gutter for twin belt caster water heaters as described above has generally been made of a refractory material such as fused silica (for example, rJOURNAL).
'OF METALSJ AUGUST 1969゜Please refer to the right column on page 69), in order to obtain slabs with good casting surface when feeding molten metal.

It was necessary to supply hot water to the deep part of the meniscus (molten metal pool) in the mold with a uniform flow spanning the entire width of the wide gutter.

However, when conventional refractory noodles, such as those made of fused silica, are used to supply molten metals, particularly high melting point metals such as steel.

(2) For example, ordinary low-order aluminum guild steel does not pose much of a problem, but high manganese steel does not have sufficient corrosion resistance, leading to an increase in slab inclusions.

■ For on-site operational reasons, the casting temperature is set to [melting point + (2
5 to 30°C)], so even if you take measures such as preheating the top of the gutter to a high temperature of around 10009C and also keeping the top of the gutter warm. Also, a solidified shell is formed on the upper surface of the gutter, making it impossible to supply hot water uniformly across the entire width of the gutter. of course,
A possible measure to prevent the formation of a scaly solidified shell is to keep the gutter preheated throughout the entire hot water supply process, but such a measure would require complex separate equipment. In addition, it causes an increase in casting costs, which discourages its adoption.

■ It is necessary to dispose of the integrally molded gutter every time it is used, which increases the cost of the gutter.

These problems have become clearer through research by the present inventors.

<Purpose of the Invention> From the above-mentioned viewpoints, the inventors of the present invention have developed a method that does not cause melt damage when feeding molten metal such as high manganese steel, and also completely ensures the formation of a solidified shell on the molten metal supply gutter. As a result of numerous experiments and researches, we discovered a molten metal supply gutter that could sufficiently reduce operation costs and guarantee stable production of high-quality thin slabs using twin-belt casters. The findings shown in (a) to (f) below were obtained.

Findings〉 (a) When high manganese steel is cast using a conventional fused silica gutter, the reason why the gutter suffers significant melting damage and the number of inclusions in the slab increases is that Mn in the molten steel comes into contact with the gutter. When doing so, Mn0−
8iQ, there is no fear of reaction with the magnesia-based or norconia-based refractory #i, and it has excellent corrosion resistance against high manganese steel molten metal.

(b) However, the composition of slag formed during steelmaking operations is high in silica, and for this reason, when magnesia-based refractories are used, contact with the slag causes
O-St Ot-based low melting point compounds are produced, and burnout is significant. Therefore, from a material standpoint, it is best to use norconia-based refractory material for the gutter that supplies molten high manganese steel.

(e) On the other hand, in order to prevent the formation of solidified shells on bridges, it is easiest and most effective to use a material with low thermal conductivity as the gutter material, and such low thermal conductivity conditions (λ:
0.5KcFLl! As a material that satisfies the following conditions (approximately 30°C or less), there is a fireproof heat insulating board material that is entirely porous (porosity: 30 or higher). However, some of the conventional fireproof insulation materials are M, 0. Although some materials are found to be of high quality or St2O quality, most of them are of MfO quality, and in any case, they are unsatisfactory from the standpoint of corrosion resistance.

(d) In general, it is extremely difficult to manufacture integrally molded molten metal supply troughs using zirconia refractory materials, and the bonding technology between zirconia refractory bricks is not sufficient, and also causes the problem of spalling. Therefore, a molten metal supply gutter constructed entirely of a zirconia-based refractory material did not yield favorable results in actual operation, but using the zirconia-based material, a conventional method (similar to that for M2O If you attempt to manufacture fireproof insulation board material according to the following method, it will be possible to manufacture large-sized integrally molded products, and it will have excellent insulation properties, so it will be suitable for molten steel with a low superheat degree (low ΔT). The formation of coagulated shells can be prevented even when

(e) However, since this type of material has low strength, it is impossible to use it as it is as a molten metal supply gutter. If the molten metal supply gutter is lined with luconia-based fireproof insulation board material, it will not only show excellent corrosion resistance against molten manganese steel, but will also not form a solidified shell on the soil, resulting in extremely good performance. To demonstrate.

(f) If the molten metal supply gutter is constructed by lining it with zirconia-based refractory insulation gourd, as is the case with Soil Nd, after the operation is complete, the parts that make up the gutter body remain as they are, and only the mate material is replaced. It will be possible to use it in the next operation, and it will be extremely economical.

Structure of the Invention The present invention has been made based on the above findings, and includes a twin belt caster m for hot water supply equipment whose operating surface is lined with a fireproof heat insulating board strip containing zirconia or zircon as a component. It is characterized by being constructed by sipping, which improves corrosion resistance against molten metal, and allows a stable and uniform injection flow to be maintained throughout the hot water supply operation without forming a solidified shell on the operating surface.

Note that "fireproof insulation board material containing zirconia or zircon as a compositional component" refers to, for example, zirconia (Zr
The main component is powder of ZrO, ) or zircon (ZrO,・Sin, ), and the content: ZrO, equivalent to about 50-95%), mixed with A/20S, CaO, etc. and fired. Usually, the porosity is about 30%11't',
2-4 ratio (λ): Approximately 0.5 KCa'/&h'C, but the higher the ZrO content, the better the corrosion resistance tends to be.

Further, as mentioned above, the gutter body may of course be made of any of fused silica, high-strength ceramic 7 (made of Al10srSixN4, SiC, etc.), steel material, etc.

FIG. 3 shows a twin-belt canuter hot water supply system of the present invention in which the working surface of the gutter body 11 made of fused silica or the like is lined with fireproof insulation material containing zirconia or norcon as a composition component. It is a schematic cross-sectional view of one example of a conventional equipment, and shows a fireproof insulation board material 1 lined in a gutter body 11.
2. The temperature of the molten metal flowing through the soil hardly drops due to the action of the fireproof insulation board material 12, which has a high insulation effect, and therefore the formation of a solidified shell on the working surface of the gutter is sufficiently prevented. Moreover, due to the high corrosion resistance of the fireproof insulation board 12, erosion of the gutter can be suppressed as much as possible.

Even if the lining of the fireproof insulation board l'12 is damaged after one operation, simply replacing only the lining while leaving the gutter body 11 as it is will make the molten metal supply gutter fully applicable to the next operation. can be played.

Note that FIG. 4 is a schematic cross-sectional view showing another example of the molten metal supply gutter of the present invention, in which the side walls of the gutter are also lined with fireproof insulation board material, but even in this case, the strength of the gutter is is sufficient, and extremely good workability can be obtained.

Next, the present invention will be specifically explained using examples.

<Example> First, the shape as shown in Fig. 2, the width of the operating surface: 4
Fused silica gutter with dimensions of 00vl, wall thickness: 30iIjI, side wall height: 50mm, and both have a thick cave of 1011mm.
A composite gutter (No. 3) in which the fused silica gutter main body is lined with the kO-based fire-resistant insulation board material, zircon fire-resistant insulation board material, and Solconia fire-resistant insulation board material of No. 1 to have the same dimensions as the fused silica gutter. The structure shown in the figure) was prepared.

Next, using the valley gutter, high-r7 gun steel (Mn: 1., 5% by weight, C: o,
oii amount%) was cast onto twin belt casters over a period of 30 minutes.

Table 1 shows the results of investigating the amount of erosion in the valley gutter and the presence or absence of solidified shell formation.

As is clear from the results shown in Table 1, in the case of fused silica troughs, the amount of corrosion damage in the troughs is extremely large, and during operation, some of the corners of the troughs solidify from the start of casting. A shell began to form and grew over time, and after about 5 minutes it was confirmed that the width of the hot water supply at the front of the gutter had shrunk by about 1/4.

In addition, in a composite gutter lined with MtO-based fireproof insulation board material, no solidified shell was observed, but large gutter erosion loss I was observed.

On the other hand, it was confirmed that the gutter of the present invention lined with zircon fireproof insulation mate material or zirconia fireproof insulation board material exhibited excellent corrosion resistance against molten steel, and no formation of solidified shells was observed.

<Overall Effects> As described above, according to the present invention, even when casting highly corrosive high manganese steel etc., it can sufficiently withstand,
In addition, it is possible to easily prevent the formation of solidified shells on bridges, and to obtain a gutter for fin belt caster water heaters that can be reused with simple repairs. Industrially useful effects are brought about, such as making it possible to manufacture thin slabs with good work efficiency.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing a cast state of a twin belt caster, Fig. 2 is a schematic perspective view of an example of a gutter for a twin belt caster water heater, and Fig. 3 is a cross section showing an example of a gutter of the present invention. Schematic configuration diagram, fourth diagram It is a cross-sectional schematic configuration diagram showing another example of the gutter of the present invention. In the drawings, 1...upper pulley, 1'...lower pulley. 2... Upper heald, 2'... Lower belt, 3... Skinmer, 4... Gutter, 5... Water heater, 6... Molten metal. 7... [-, 8... Dam block, 9... Bottom plate,
1 leaf: side wall, 11: gutter body, 12: fireproof insulation gate material. Applicant Sumitomo Metal Industries Co., Ltd. Agent Tomi 1) Kazuo and 1 other person Figure 1 Figure 2 Figure 0 ≠ 3 Figure 2

Claims (1)

[Claims] A gutter for a twin-belt caster water heater, characterized in that its operating surface is lined with a fireproof insulation board material containing zirconia or zircon as a component.