JPS6264458A - Continuous casting method for thin ingot - Google Patents

Abstract

PURPOSE:To easily, inexpensively and smoothly start casting by disposing stationary short sides to both side edges of circulatin bodies which are disposed to face each other to form a space and heating the refractory surfaces of the stationary short sides by heating elements then pouring a molten metal into the space. CONSTITUTION:A pair of metallic belts 1 (only one thereof is shown) which circulate are disposed to face each other via guide rolls 3 and a pair of the stationary short sides 5' (only one thereof is shown) are disposed to both side edges of the belts. 1. The molten steel 10 is poured into the space formed of the belts 1 and the sides 5' and a thin ingot is continuously cast. The wire- or foil-shaped heating elements 7 are stuck to the surfaces of the refractories 5 in contact with the molten steel 10 on the inside of the short sides 5'. The elements 7 are energized to heat the surfaces of the refractories 5 prior to casting with the above-mentioned casting machine. The generation of a solidified shell from the refractory 5 surfaces is thereby suppressed prior to the start of pouring of the molten steel and the smooth casting is made possible.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is directed to a refractory on the short side of a belt gear star for manufacturing a sheet bar with a thickness of 50 mm or less from molten metal (described below as an example of molten steel). This relates to suppressing the growth of solidified shells by heating before the start of casting.

(Prior Art) Fig. 2 shows a synchronous belt caster of the squeezing method that manufactures steel plates such as seat bars directly from molten steel. This heald caster maintains a gap for holding the molten copper 1 and solidified shell over a predetermined distance, and rolls a plurality of guide rolls 3a + 3b +3c + 3a'.
+3b'+3c' The metal belts 1 and 2 are a pair of long side surfaces that are axially moved via +3c' and are arranged opposite to each other, and the short sides are in close contact near both side edges of these metal belts. Fixed short side 4'.

5' to form a casting space. This fixed short side is
In order to manufacture a thin plate with a thickness of 30 mm or less using a nozzle 6 with a diameter of 100 inches or more, it has an approximately inverted triangular shape that is wide at the top and gradually tapers toward the bottom, and is lined with refractory material. It has a structure with layers.

In order to cast a thin slab of about 30 iris, such a belt caster requires considerable narrowing down, and the short sides 4' and 5' are similar to or similar to the long sides of the metal healds 1 and 2. If the solidified shell is generated faster, the compression at the lower part of the casting space will cause wrinkles, the pull-out resistance will increase, and in extreme cases, pull-out will not be possible. By heating the short sides 4', 5' to 1fi at the start of casting, the growth of the solidified shell formed there must be delayed compared to the growth of the solidified shell of the metal belt 1.2 example.

Based on this, the inventors of the present invention
No. 3 and Japanese Patent Application No. 56-130194, we devised the idea of making the short side surface in contact with molten steel a refractory material, and heating the short side wall with a heater embedded in the refractory material. In addition, as shown in the third panel, prior to the start of casting, a partition plate is provided at a distance on the inside of the short side wall, and the flame of the gas burner 12 is radiated into the gap to heat the inside of the short side 4'5'.
This suppressed the growth of the solidified shell that forms on the short side at the start of casting.

(Problem to be Solved by the Invention) However, in the former method, the refractory on the short side is cast only once, and even though there is no need to heat it during casting, the refractory on the short side is heated only once. It took time and effort to embed the heater in the wafer, and the cost of manufacturing the short sides increased.

In addition, when heating the refractories on the short sides with the latter gas burner, CO gas must be used to prevent dew condensation on the metal belt, and the heating cost is several tens of times higher than heating with electricity. Furthermore, the installation of the gas burner and its auxiliary equipment complicates the mold surroundings, impairing workability, and there is a risk of gas leakage, so the gas concentration must be strictly inspected at the time of ignition. In addition, when heating with a gas burner, it is difficult to heat the bottom of the refractory on the short sides, and the preheating temperature is not high, so shell growth on the short sides cannot be completely suppressed.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a thin cast slab, which has a low production cost on the short side and which prevents shell growth on the short side large object surface at the start of casting using a simple method.

(Means for Solving the Problems) The present invention includes a pair of metal belts that are arranged opposite to each other and move on an axis, and a substantially inverted triangular belt that is in close contact with the metal belts near both side edges of these metal belts. Before injecting molten steel into the space formed by a pair of fixed short sides in the shape of
As shown in Fig. 1a, a linear or foil-shaped heating element 7 is pasted on the surface of the refractory 5 that contacts the molten steel inside the fixed short side 5', or a heating element not limited to a linear or foil-shaped heating element is contacted. Alternatively, this continuous casting method for thin slabs is characterized in that the refractory 5 is heated by the heating element in close proximity to the refractory 5 and then molten steel is injected.

For example, the heating element used for pasting is nichrome,
A Fe-Cr-Al foil or wire is attached to the refractory 5 using a ceramic adhesive or mechanical adhesive. At this time, take into consideration prevention of breakout and thermal deformation of the metal belt, and attach the heating element to the short side refractory so that the occupation ratio of the heating element to the short side refractory is 173 or more. good.

(Function) Before casting, nichrome-based, Fe-Cr-Al-based foil or wire is pasted on the molten steel side of the refractory on the short side 5' in Figure 1a, and the conductor ``fFfA11'' is connected to the power source. Connect to the refractory and heat the short side refractory for several minutes under the specified voltage.

In this heating method, heat is easily transferred because the heating element 7 and the short side refractory 5 are in direct contact, and compared to radiant electric heating using a gas burner, the preheating time can be shortened and the preheating temperature can be increased. The lower part of the refractory 5 can be heated. Furthermore, since heat is not directly transferred to the metal belt, the metal belt does not undergo thermal deformation. By injecting molten steel after heating the short side refractories 5 in this way, it is possible to suppress the formation of shells from the short side refractories 5 at the start of injection,
Enables smooth casting. Note that, at this time, although the heating element 7 melts into the molten steel, it hardly affects the composition of the steel.

(Example) 80 tons of melt wA (C: 0.04 to 0.06 in 1 heat)
%, Si: 0.05% or less, Mn: 0.30-0
．． 60%, P: 0.010-0.030%, S:
0.010-0.030%, AE: 0.03-0
．． 06%) at a temperature of 1550°C to 1565°C,
Using a belt caster as shown in Figure 2,
Dragon.

A slab with a width of 1200 mm was cast.

At this time, using fused silica as the material of the short side refractory,
Based on the casting experience of 62 heats of the conventional method of heating short side refractories with CO gas and the method of the present invention, we have found that the preparation time between castings, the running cost and flaking when heating the short side Table 1 shows a comparison in terms of out index, with the conventional method set as 1.

Table 1 As is clear from this table, the time needed to set up the burner is not required, and the preheating time for the short-side heavy-duty material is shortened, so the casting preparation time is shortened.

Additionally, since the heating source was changed from expensive CO gas to electricity, running costs for heating the short sides became cheaper.

Furthermore, since the preheating temperature of the short-side large material can be increased, the growth of the shell can be suppressed, reducing the frequency of breakouts.

(Effects of the invention) As explained above, the work is as simple as attaching a heating element to the short-side refractory, without requiring the labor and manufacturing costs required when embedding a heater in the short-side refractory. Cast preparation time is shortened, running costs are low and breakout frequency is reduced.

[Brief explanation of drawings]

FIG. 1a is a diagram showing the structure of a mold for a belt caster used when carrying out the method of the present invention, FIG. 1b is a diagram in which a heating element is wired on the short side, and FIG. FIG. 3 is a diagram schematically showing a heald caster used in carrying out the invention, and FIG. 3 is a diagram showing heating of a fixed short side using conventional CO gas. 1.2...Metal belt

Claims (1)

[Claims] 1. Formed by a pair of opposingly placed circulating bodies that circulate while maintaining a gap to hold the molten metal over a certain distance, and a pair of fixed short sides placed on both side edges of the circulating bodies. A method of continuously casting thin slabs by injecting molten metal into a space in which the molten metal is poured, characterized in that the surface of the refractory on the fixed short side that is in contact with the molten metal is heated by a heating element, and then the molten metal is poured. Continuous casting method.