JPS60158956A - Continuous casting method for thin sheet - Google Patents

Abstract

PURPOSE:To start stable continuous casting without troubles in continuous casting of a thin sheet by a twin drum method by installing an electrode type sensor to a dummy head between both drums in the stage of starting pouring and starting the drums when said sensor detects the level of the molten metal surface. CONSTITUTION:A dummy bar head 5 provided with an electric wire electrode 6 protected with a refractory insulator with the top end of said electrode held at a specified height is disposed in the part for drawing out a thin solidified sheet constituted of water-cooled twin drums 1, 1' and stationary side gates 2. When pouring 4a is started and a molten metal on the head 5 attains a specified height, the electrode 6 is short circuited by the molten metal and is conducted with electricity. The rotation of the twin drums 1, 1' is started by the signal from said electrode. The start of the rotation is controlled with extremely high accuracy and the stable continuous casting is executed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a method for continuously preparing thin plates using a twin-drum continuous casting facility 111.

Molten metal is continuously poured from a tundish between a pair of water-cooled drums, which are placed horizontally facing each other and driven and rotated synchronously in opposite directions by a driving source. In twin-drum continuous casting equipment, when the thickness of the thin plate is approximately 2 to 5 mm, the time required for the molten metal to solidify upon contact with the drum, the so-called solidification time, is as follows:
It is usually about 0.5 to 2 seconds. This short-time solidification of the molten metal is strictly controlled at the initial stage of casting, and the water-cooled drum is heated.

Precise timing of the rotation start time of 1' is extremely costly for continuous casting of normal thin plate slabs, but in the conventional method, this control is not performed strictly, and water-cooled 1 and 1' rotation start timing is inaccurate, resulting in bulging (blurring phenomenon on the slab surface) due to unsolidified molten metal, breakout, leakage at the early stage of pouring, or excessive solidification of molten metal. There are problems such as an increase in reaction force and rolling cracks in the slab, and the drawback is that stable operation cannot be achieved in the initial stage of casting.

The present invention has been proposed for the purpose of providing a continuous thin plate casting method using twin-drum continuous casting equipment, which eliminates the drawbacks of the above-mentioned conventional methods and can ensure stable operation in the initial stage of casting. When continuously casting thin plates using continuous casting equipment, an electrode type sensor installed at a predetermined position between the drums detects when the level of the hot water in the pool between the drums reaches a predetermined position. The present invention relates to a continuous thin plate casting method characterized in that the rotation of the drum is started in response to a signal.

Hereinafter, the method of the present invention will be specifically explained with reference to the accompanying drawings.

In FIG. 1, reference numerals 1 and 1' denote a pair of water-cooled drums made of steel plates that are horizontally and freely rotatably installed in a machine frame (not shown) facing each other, and these drums 1, 1' are connected to a drive source (not shown) They are driven and rotated synchronously in opposite directions (arrow directions). 2゜2' are those drums 1,
A side fixed weir 4 prevents the molten metal from leaking to the side between 1' and 1', and 4 is a tundish installed above the drum 1° 1', in which the molten metal 3 is stored.

5 is a pool of molten metal poured from the nozzle 4a of the tundish 4 between the pair of water-cooled drums 1, 1' and the fixed weirs 2, 2' of the site 8. 2 and 2′, and
a head of a dummy bar that pulls out the slab through a drawing device when the molten metal in the pool solidifies to form a slab;
is an electrode type sensor whose upper end fluid-tightly penetrates the central part of the dummy bar head 5 and extends slightly upward; It is arranged so that it is located at a predetermined hot water surface level "2". Note that since the molten metal from the tundish 4 flows down along the surfaces of the side fixed weirs 2 and 2', the height difference in the molten metal level is extremely small. The sensor 6 is formed of two conductive wires as shown in FIG. 2, and the lower end thereof is connected to a drum drive source via a drum rotation control device (not shown).

Note that the sensor 6 is covered with a heat-resistant covering material 7, as shown in FIG. Note that 8 in the figure indicates a heat-resistant sole material attached to the upper end surface of the dummy bar head 5.

An example of equipment for carrying out the method of the present invention is constructed as described above, and when the equipment starts operating, at the initial stage of casting, a pair of water-cooled drums 1, 1',
As before, the molten metal 3 in the tundish 4 is poured into the tundish 4 through the nozzle 4a into the tundish pool surrounded by the fixed weirs 2, 2' and the dummy bar head 5.
In this case, in the present invention, as soon as the molten metal level in the tundish reaches a predetermined position at which the molten metal in the tundish becomes solidified, the two conductive wires of the sensor 6 are short-circuited by the molten metal and made conductive. The drum rotation control device is actuated by the signal, and the rotation of the water-cooled drum 1°1' is started via the drive source.

Therefore, the rotation start timing of the water-cooled rams 1 and 1' is accurate and coincides with the time when the molten metal in the pool becomes solidified, so phenomena such as bulging and breakout due to unsolidified molten metal occur. In addition, since phenomena such as an increase in drum reaction force due to oversolidification of the molten metal or rolling cracks in the slab do not occur, stable casting is performed in the initial stage of casting.

Since the method of the present invention has the above-described configuration and operation, it is possible to realize a thin plate continuous casting method that eliminates the drawbacks of the conventional method and ensures stable operation in the initial stage of casting. This can be cited as a practical effect.

[Brief explanation of the drawing]

The attached drawings are schematic explanatory diagrams of an example of equipment for carrying out the method of the present invention, with FIG. 1 being a side view and FIG. 2 being taken from II-II in FIG.
The line view and FIG. 3 are enlarged views of the sensor portion. 1. t': Water-cooled drum 2. 2': Fixed weir 3:
Molten metal 4: Tundish 5: Dummy bar head 6: Sensor sub-agent Patent attorney Akira Ito (2 others) Figure 1 Figure 2

Claims (1)

[Claims] When continuously casting thin plates using twin-drum continuous casting equipment, an electrode sensor installed at a predetermined position between the drums detects when the level of the hot water in the pool between the drums has reached a predetermined position. , a thin plate continuous casting method characterized in that the rotation of the drum is started in response to that signal.