JPH0696183B2 - Long-side wheel moving type continuous casting method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) This invention relates to a continuous casting machine such as a belt type continuous casting machine or a roll type continuous casting machine in which a long side of a mold moves circularly. The method of continuously casting slabs from the steel is to coat the long side mold surface to suppress heat removal in order to reduce the friction coefficient between the slab and the belt, and to make the heat removal uniform in the width direction. In order to obtain an excellent high temperature slab and to reduce the heat load of the belt, the problem of breakout is avoided. In the following description, the long side wheel rotating continuous casting machine will be described as a belt continuous casting machine.

(Prior Art) In recent years, a belt type continuous casting machine has been developed for the purpose of increasing the casting speed and reducing the thickness of the cast piece. Various belt type continuous casting machines have been proposed in the field of steel, which is particularly in demand, and there is, for example, a twin belt type vertical continuous casting machine as shown in FIG.

In this continuous casting machine, the short sides 5 and 5'have a wide upper and lower concavity shape, and FIG. 3 shows the surface of the short side 5 in contact with the molten metal 10 as shown in the schematic view near the short side. Is a refractory 9 and a water-cooled metal body 11 is arranged on the sliding part of the belt. The metal mold 11 is formed on the front side of the water-cooled metal body 11 by the belt-shaped surface of the long side of the solidified shell. Stable casting is performed by the solidified shell being dragged in.

Now, in the belt type continuous casting machine, it is widely known to coat the surface of the belt, and as shown in, for example, JP-A-63-115655, the coating thickness is almost inversely proportional to the casting speed. There is also a proposal to develop that a high temperature slab can be obtained even if the casting speed is decreased by increasing or decreasing by the above.

(Problems to be solved by the invention) By the way, in a belt type continuous casting machine, the belt is scratched and scratched at a sliding portion with a short side, and the belt life is determined by the degree of the sliding flaw. It is essential to devise to reduce the friction between the sides.

Therefore, we applied a coating such as an aqueous solution of calcium carbonate to the belt not only in the area in contact with the slab but also in the sliding area with the short side.Although the belt sliding flaw was reduced, sometimes the breakout occurred just below the short side. Occurred.

In order to perform stable casting with such a belt coating application method, the casting speed must be reduced.
A problem is that the temperature of the slab or the productivity is lowered.

SUMMARY OF THE INVENTION It is an object of the present invention to propose a continuous casting method capable of advantageously solving the above-mentioned problem of breakout occurring when coating a long side die face and stably producing a slab.

(Means for Solving the Problem) As a result of earnest studies to solve the above-mentioned breakout occurrence problem, the inventors have found that the cause of breakout occurrence is
Since the belt was uniformly coated over the entire casting width, the solidified shells formed at both ends of the long side adjacent to the short side were thin as in the center in the width direction, and therefore the metal body 11 was water-cooled on the short side. It was found that the solidified shell formed on the front surface could not be dragged by the thin solidified shell formed at both ends of the long side, and the solidified shell was broken at both ends of the long side adjacent to the short side. .

This invention performs stable casting by thickening the solidified shell thickness of the both ends of the long side adjacent to the short side to some extent from the above knowledge, the present invention is a continuous casting machine that constitutes a mold with a fixed short side and an orbiting movable long side. When obtaining a slab by cooling the molten metal mainly on the long side mold surface, when applying the heat-insulating coating agent on the long side mold surface at the mold entry side, the long side end portions of the long side adjacent to the short side It is a continuous rotary casting method of long-side wheel rotation type, characterized in that the film thickness of the heat-insulating coating agent is made thinner than that of the central portion in the width direction of the long side.

(Operation) FIG. 1 shows an example of the structure of a belt coating apparatus for carrying out the present invention. In the figure, reference numeral 4 is a belt, 6 is a spraying device of the heat insulating coating agent 13, 7 is a spraying device having the same heat insulating coating agent 13 and a thin thickness, and 8 is a spraying device of the lubricating coating agent 14.

In the apparatus shown in the figure, the coating agent spraying devices 6 and 7 are provided at both ends of the long side in order to make the film thickness of the heat insulating coating agent 13 at both ends of the belt 4 adjacent to the short side 5 thinner than that in the central portion in the width direction of the belt 4. And the coating is performed by providing them in the central portion and the central portion, respectively. Further, the lubricous coating agent 14 is applied by the spraying device 8 to the area in contact with the short side.

According to the present invention, as described with reference to FIG. 1, by reducing the belt coating film thickness on both end portions of the belt adjacent to the short side, the end portion of the mold at the time of casting by the belt type continuous casting machine is shown in FIG. As shown in the cross-sectional view, the long side solidified shells 15 at both ends of the belt 4 are thickened to increase the strength against the drag of the short side solidified shells 16 and prevent breakout.

The coating agent applying method for carrying out the present invention is the same as the coating agent spraying devices 6 to 8 shown in FIG.
Spray type, touch roll type, brush type,
The method does not matter, such as belt dobu pickling type.

The range α in which the film thickness of the heat-insulating coating agent is reduced is about 100 mm or less in the width direction from the end adjacent to the short side of the belt, and when α is increased, thermal deformation of the belt tends to increase. A value of 50 to 70 mm is suitable.

Further, depending on the thickness of the solidified shell to be generated, the heat insulating coating agent may not be applied to both ends of the long side adjacent to the short side.

It is preferable to apply a lubricious coating to the portion in contact with the short side. If the heat insulating coating agent also has lubricity against sliding on the short side, this heat insulating coating agent may be applied.

(Example) A twin-belt continuous casting machine shown in FIG. 2 casts a slab having a thickness of 30 mm and a width of 1000 mm at a casting speed of 10 m / min. At this time, the belt coating is made of CaCO 50 mm each from the end within the range of the slab width
_A coating agent with excellent heat insulation properties prepared by dissolving ₃ in alcohol or water with a thickness of 10 μm and other 900 mm width with a thickness of 20 μm
By spraying, and the range of contact with the short side mold is MoS ₂
Rapeseed oil in which was dispersed was applied by a touch roll method.

Other than the above, examples of the components of the heat insulating coating agent include graphite powder and the like.

Examples of the components of the lubricity coating agent include rapeseed oil in which BN is dispersed, in addition to the above.

Although an example of the belt type continuous casting machine has been shown above, if the fixed short side and the wheel-rotating movable long side are combined in the same manner in a roll type continuous casting machine as well, the fixed short side and the long side adjacent to both ends A similar effect is obtained by reducing the coating thickness of the part.

(Effects of the Invention) In the long-side wheel moving continuous casting method of the present invention, the thickness of the heat insulating coating agent on both ends of the long side adjacent to the short side is made thinner than that at the center of the long side. The solidified shell formed on both ends could be thickened and stable high temperature slabs were produced. Also, by applying a lubricating coating agent to the sliding surface with the short side of the belt, sliding flaws were almost eliminated.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an example of a coating apparatus for carrying out the present invention, FIG. 2 is a schematic diagram of a twin belt type vertical continuous casting machine, and FIG. 3 is a twin belt type vertical continuous casting machine. FIG. 4 is a schematic view of the vicinity of the short side of FIG. 4, and FIG. 4 is a sectional view of a mold end portion during casting by a belt type continuous casting machine. 1 to 3,1 'to 3' ... Belt support roll 4,4 '... Belt, 5,5' ... Short side 6 to 8 ... Coating agent spraying device 9 ... Refractory, 10 ... Melting Metal 11 …… Metal body cooled with water 12 …… Slab 13 …… Heat-insulating coating agent 14 …… Lubricating coating agent 15 …… Long side solidified shell, 16 …… Short side solidified shell

Front Page Continuation (72) Inventor Tomoaki Kimura 3-1-1 1-1 Saiwaicho, Hitachi, Ibaraki Hitachi Ltd., Hitachi Works

Claims (1)

[Claims] 1. A continuous casting machine comprising a fixed short side and a rotary-movable long side, wherein a long side mold surface is mainly used when a molten metal is cooled by a long side mold surface to obtain a slab. When applying the heat-insulating coating agent on the mold entry side, the feature is that the thickness of the heat-insulating coating agent on both ends of the long side adjacent to the short side is thinner than that of the center of the long side in the width direction. Long-side wheel moving type continuous casting method.