JPH0616920B2 - Beam blank continuous casting method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) With regard to continuous casting of beam blanks, the technical contents described in this specification are, in particular, the arrangement of a dipping nozzle for supplying molten steel from a tundish and the setting position of a mold. We propose the development results of a continuous casting method that achieves stable operation by avoiding the deformation of the beam blank and the volume and loss of the immersion nozzle caused by the uneven heat of the solidified shell during casting. Where it is.

(Prior Art) In continuous casting of beam blanks, usually, the flange edge surface of the beam blank is in contact with each pair of pinch rolls horizontally supported horizontally and the roller cylinders of the roller apron up to this point. The casting is performed by placing the mold in the facing direction, disposing the immersion nozzles at the positions corresponding to the respective flanges of the beam blank, and injecting molten steel from the tundish.

As a reference, for example, Iron and Steel, 67, No. 8, pages 1324 to 133.
See page 0.

By the way, in the continuous casting of the beam blank as described above, since the shape of the mold is complicated, there is a case where the operation becomes extremely difficult due to uneven flow due to flow fluctuation between each nozzle such as when nozzle clogging occurs during casting. is there.

On the other hand, using a single immersion nozzle to inject molten steel from the web in the mold or place the immersion nozzle only on one side of the mold corresponding to the flange center of the beam blank,
It is conceivable to inject the molten steel at a constant flow rate, but in the former case it is not possible to supply the molten steel by the immersion nozzle because of the narrow width of the web, and in the latter case, the generated solidification shell has an unbalanced heat. During extraction, the beam blank is deformed to the left and right, making it impossible to continue casting.

In order to solve the above-mentioned inconvenience caused by a single immersion nozzle, for example, in JP-A-58-224050, a single immersion nozzle having a plurality of holes is arranged on one side of the mold corresponding to the center of the flange of the beam blank to generate There is a disclosure for preventing the occurrence of solidification shell unbalanced heat.

However, since the nozzle shape becomes complicated, during casting,
Problems are left where stable operation is apt to occur due to melting damage.

(Problems to be Solved by the Invention) It is an object of the present invention to solve the problems of the prior art and to establish a beam blank continuous casting method that enables stable operation.

(Means for Solving the Problems) The present invention is directed to continuous casting of beam blanks by a curved continuous casting machine, in which pinch rolls horizontally supported and paired with each other and rolls of a roller apron leading to the pinch rolls. A continuous casting mold is installed on the barrel in the direction in which the flange surface of the beam blank is in contact, and a single immersion nozzle is arranged in the mold only at a position corresponding to the center of the flange on one side of the beam blank. Beam blank continuous casting method, wherein the single immersion nozzle is arranged at a position corresponding to the center of the flange of the beam blank located on the side opposite to the beam blank withdrawal side. Is desirable.

(Operation) When pouring molten steel, the single immersion nozzle arrangement, especially the arrangement in the mold that corresponds to the center of the flange on the extraction side of the beam blank, has a higher temperature than the other flange, but during extraction of the beam blank. Since the thermal stress acts in the direction of relaxing the stress caused by the bending of the, the casting operation becomes easy. Furthermore, by changing the set position of the mold, the amount of molten steel supplied can be kept constant even when the molten steel is supplied by a single immersion nozzle, and there is no uneven heating in the direction between the flange chips of the beam blank. It is possible to avoid the lateral deformation that tends to occur during pulling out, and it is possible to perform stable operation.

The single dipping nozzle referred to here means a single-hole dipping nozzle or a single-hole dipping nozzle having a double-hole dipping nozzle having a discharge hole facing the web portion, and improvement of the water flow in the web direction can be expected. Occurrence of blockage has no adverse effect. In terms of cost,
Preferably a single hole immersion nozzle is used. An example using a single single-hole immersion nozzle will be described below.

(Example) FIG. 1 shows a cross section of a mold used for continuous casting of beam blanks. In the figure, 1 is a casting mold for continuous casting, 2 is a single hole immersion nozzle, and 3 is a group of drill holes for cooling water.

The mold 1 was installed in a curved continuous casting machine with the arrow shown in FIG. 1 as the drawing direction of the beam blank. That is, the mold 1 is installed so that the flange surface of the beam blank is in contact with the pinch rolls, which will be described later, and the roll cylinders of the roller weblon up to this point.

The single hole immersion nozzle 2 was arranged at a position corresponding to the center of the flange 1A on one side of the beam blank.

The mold 1 used at this time was a mold adapted to a beam blank having a flange width of 420 mm, a flange height of 1110 mm, and a web width of 100 mm, and the single hole immersion nozzle 2 had a nozzle diameter φ.
Using 30mm, C: 0.22wt%, Si: 0.25wt
%, Mn: 0.85 wt%, P: 0.028 wt%, S: 0.012 wt% were injected into the mold 1 for continuous casting.

FIG. 2 is a schematic view showing a cross section of the beam blank during continuous casting, and the AA cross section in FIG. 2 shows the cross section of the beam blank and the arrangement of the supporting rolls on the exit side of the mold 1.

In FIG. 2, 4A and 4B are roller aprons made of Fluoro, 5 and 6 are pinch lorries, 7 is a gas cutter, and 2nd.
In the cross section taken along the line A-A in FIG. 8, 8 is an end face roll and 9 is a web roll. Here, the conventional drawing direction is also shown by a broken line.

During casting in the row metal casting of the beam blank according to the present invention,
The beam blank was not deformed due to the effect of unbalanced heat, and the immersion nozzle was not damaged or damaged, and stable operation was possible.

In the continuous casting of the beam blank according to the present invention,
The curvature caused by pulling out the beam blank needs to be corrected by the pinch rolls 5, 6 or before reaching the pinch rolls 5, 6, but unlike the conventional casting direction, the section modulus is high. Since it is in the direction, the diameter of the roll at the straightening point should be increased when straightening the beam blank so that it can withstand the straightening load applied. It is necessary to install equipment and heating equipment.

The addition of the heat retaining or heating means is advantageous in the case of direct-feed rolling because a beam blank slab in a high temperature state can be obtained.

Further, in the conventional continuous casting of the beam blank, a part of the cooling water in the secondary cooling zone flows down the R inner web portion of the beam blank, so that it has to be purged by the draining device. Then, since the setting position of the mold 1 was changed, that is no longer necessary.

In addition, the penetration depth of molten steel can be reduced by using a single two-hole immersion nozzle, and a single device is also used for controlling the discharge flow using a static magnetic field generator that reduces this penetration depth. Just place it.

(Effect of the Invention) According to the present invention, since only one dipping nozzle has been used for casting a beam blank in the related art, the nozzle unit consumption is
It can be halved, and stable operation is possible without the deformation of the beam blank during casting, melting of the nozzle, and lack of damage.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a continuous casting mold, and FIG. 2 is a schematic view showing a cross-section of a beam blank during casting. 1 ... Mold, 2 ... Single single hole immersion nozzle 3 ... Cooling water drilling hole 4A, 4B ... Roller apron consisting of foot rolls 5, 6 ... Pinch roll, 7 ... Gas cutting machine 8 ... End surface Roll, 9 ... Web roll

Claims (2)

[Claims] 1. When continuously casting a beam blank by a curved type continuous casting machine, a flange surface of the beam blank is provided on each of the roll cylinders of a pinch roll and a roller apron which are horizontally supported and paired with each other. A continuous casting mold is installed in contact with each other, and a single immersion nozzle is arranged in the mold only at a position corresponding to the center of the flange on one side of the beam blank, and molten steel is injected from the tundish. Beam blank continuous casting method. 2. The method according to claim 1, wherein the position of the immersion nozzle in the mold is a position corresponding to the center of the beam blank located on the side opposite to the drawing side.