JP2003285143A - Continuous casting method for pouring molten steel into tundish without mixing in contamination source - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a continuous casting method which, when molten steel is transferred from a ladle into a tundish, prevents a contamination source such as quartz sand or a combination of quartz sand with chromium oxide or a metal oxide from being mixed in the tundish from the ladle to prepare a non-metallic inclusion-free steel slab. <P>SOLUTION: In pouring molten steel from a ladle 1 into a tundish 4, before opening a sliding nozzle 6 in the ladle 1, a discard molten steel pot 5 for receiving a previously cut initial molten steel and packing of quartz sand or the like, attributable to opening of the sliding nozzle 6, and iron oxide or the like contained in the initial molten steel is disposed outside the tundish 4. As shown in Fig. 1, a bucket 7 is disposed so as to extend from the sliding nozzle 6 in the ladle 1 to the discard molten steel pot. Upon opening of the sliding nozzle 6, packing of the sliding nozzle 6, together with an initial molten steel, is cut and is received in the discard molten steel pot 5. Thereafter, the stream of the molten steel from the sliding nozzle 6 in the ladle 1 is transferred to the tundish 4, and the sliding nozzle 6 is then fully opened to pour the molten steel into the tundish 4 to conduct continuous casting. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to the production of high-cleanliness steel in continuous casting, and more particularly to pouring molten steel from a ladle to a tundish.

[0002]

2. Description of the Related Art Steel for use in automobile parts such as CVJ and CVT that are used under severe conditions and are required to have high durability are high cleanliness steels that do not contain non-metallic inclusions that hinder durability as much as possible. Is required. In the production of such high-cleanliness steel, conventionally, high-level melting by electric furnace refining has been performed, and subsequent non-metallic inclusions in molten steel have been refined by vacuum degassing and ladle refining. Non-metallic inclusions are reduced as much as possible for the melting process. The molten steel of high cleanliness produced in this way is transferred from the ladle to the tundish for continuous casting, poured from the tundish into the continuous casting mold, and bloomed from the continuous casting equipment such as bloom. The solidification rate is controlled so that the cleanest possible steel strip can be obtained. However, when molten steel melted to a high degree of cleanliness is also treated in the ladle, non-metallic inclusions may enter the molten steel from the furnace wall of the ladle, slag, etc. The contamination source, which is a metal inclusion, is mixed when the molten steel is transferred from the ladle to the tundish, and further enters the continuous casting mold.

On the other hand, a sliding nozzle, which is usually a pouring port at the bottom of a ladle furnace, is blocked with a filler such as silica sand or silica sand and chromium oxide. However, degassing and refining molten steel from a ladle to a tundish. When transferring, open the sliding nozzle closed with silica sand or silica sand and filler such as chrome oxide as it is, or fill it with small iron scraps and heat with oxygen or oxygen and combustible gas to forcibly open. Drill and transfer molten steel to tundish. During these drilling operations, silica sand in the filling or silica sand and pollution sources such as chromium oxides and oxidized small iron scraps are dropped into the tundish, and further mixed into the mold at the early stage of casting by the molten steel flow from the ladle. It becomes a non-metallic inclusion by being hammered into a steel piece.

Contamination sources consisting of silica sand by natural opening at the time of opening the sliding nozzle or silica sand of silica sand and chromium oxide and lower oxides such as iron oxide by forced opening are reducing sources such as Al in the tundish. It is reduced by strong elements, and as a result, non-metallic inclusions such as alumina are generated, and the non-metallic inclusions are contained in the steel to cause defects in the product, resulting in a decrease in the mechanical life of the product. Further, in continuous casting, the amount of the above-mentioned oxides of pollution sources accumulated in the tundish increases as the casting proceeds, and the cleanliness of molten steel is further deteriorated.

[0005]

DISCLOSURE OF THE INVENTION The problem to be solved by the present invention is, as described above, when pouring molten steel from a ladle to a tundish, silica sand or silica sand and chromium oxide or metal oxide from the ladle. It is an object of the present invention to provide a method of preventing contamination sources such as the above from being mixed in the tundish so that non-metallic inclusions are not mixed in the steel piece produced by continuous casting.

[0006]

The means of the present invention for solving the above-mentioned problems is, in the invention of claim 1, sliding the ladle when pouring molten steel from the ladle to the tundish in continuous casting. Pre-cut the initial molten steel from the ladle containing the nozzle filling and iron oxide into the pick-up pot provided outside the tundish by opening the nozzle, and then make the sliding nozzle half-open to remove the leaked molten steel. This is a continuous casting method of pouring molten metal into a tundish without injecting a pollution source into the tundish, which is carried out by moving the pick-up pot to a tundish and then fully opening the sliding nozzle to pour molten steel from the ladle into the tundish.

According to the invention of claim 2, a movable hot water pick-up pot is provided in the gap between the ladle and the tundish, and the hot water pick-up pot is set in the gap between the ladle and the tundish.
Preliminarily cut and receive the initial molten steel from the ladle containing the nozzle filling and iron oxide immediately after the opening of the sliding nozzle in this set hot water pickup pot, and then move the hot water pickup pot that received the precut initial molten steel. 2. The continuous casting method for pouring molten metal from the ladle into the tundish without injecting the pollutant into the tundish, after removing it from the gap between the ladle and the tundish, and then performing normal pouring from the ladle to the tundish. Is.

According to the third aspect of the invention, a hot water pick-up pot that is movable in the gap between the ladle and the tundish is prepared by a hot water pick-up pot carriage, and the hot water pick-up pot that receives the pre-cut initial molten steel is moved. Is a pick-up pot trolley, which is a continuous casting method for pouring molten metal without pouring the pollution source into the tundish.

According to the invention of claim 4, in order to receive the pre-cut initial molten steel, a tub is used instead of the pick-up pot.
The tub that receives the pre-cut initial molten steel is moved to a hot water pick-up pot installed at another location, and the initial molten steel is poured into this hot water pick-up pot to remove it from the gap between the ladle and the tundish. It is a continuous casting method of pouring the pollution source of the means of the item 2 or 3 without injecting it into the tundish.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a plan view schematically showing an apparatus equipped with a ladle, a tundish and a hot water pick-up pot in the method of the present invention. 2 is a front view of the device of FIG. FIG. 3 is a plan view of the device at the time of preliminary cutting.
FIG. 4 is a schematic elevational view showing a part of an apparatus in which a hot water pick-up pot truck of another embodiment is installed.

In the embodiment of the present invention, as shown in FIG. 1, a ladle 1 containing melted molten steel is placed in a swing tower 3
Set to. The swing tower 3 can be rotated in the direction of the arrow 10, and the ladle 2 of the next channel can be installed on the opposite side of the ladle 1, and the ladle 1 of the current channel is poured into the tundish 4 arranged below it. It is arranged to be possible. Below the tundish 4 is a continuous casting device, and the continuous casting mold is covered with a mold cover 9. Outside the tundish on the side of the ladle 1 and tundish 4 of the current channel, there is a pick-up pot cart 8
A hot water pick-up pot 5 is placed. Current channel ladle 1
When is moved by being rotated by the swing tower 3 on the tundish 4 side, the gutter 7 from the sliding nozzle 6 of the ladle 1 is arranged in the hot water pick-up pot 5.

That is, first, the ladle 1 is used for continuous casting.
When starting the pouring of molten steel from the tundish 4 into the tundish 4, the sliding nozzle 6 at the bottom of the ladle 1 is opened in order to prevent contamination of the molten steel from the sliding nozzle 6 into the molten steel of the tundish 4. Prior to piercing, a molten metal in the initial stage for pre-cutting and a pick-up pot 5 for receiving are placed outside the tundish 4, and as shown in FIG.
As shown in the figure, the sliding nozzle 6 of the ladle 1 to the gutter 7
Or the ladle 1 is moved onto the hot water pick-up pot 5 as shown in FIG. 3 to open the sliding nozzle 6 and drop the filling of the sliding nozzle into the hot water pick-up pot 5. At the same time, after cutting the initial molten steel and receiving it in the hot water pick-up pot 5, the sliding nozzle 6 is in a half-opened state in which the molten steel becomes a muscle leak state,
The molten steel flow from the sliding nozzle 6 of the ladle 1 is transferred to the tundish 4, and then the sliding nozzle 6 is fully opened to pour the molten steel into the tundish 4 for continuous casting. In this case, in FIG. 3, the ladle 11 installed on the other side of the swing tower 3 is a fully open channel ladle and is to be replaced with a ladle for the next channel.

In another embodiment, as shown in FIG.
A hot water pick-up pot trolley 12 is arranged in a gap between the ladle 1 and the tundish 4 and is movable. First, the hot water pick-up pot 13 is set in this gap, and the sliding nozzle 6 of the ladle 1 is opened. Immediately after the opening, the molten steel pick-up pot 13 is filled with the filling material of the sliding nozzle 6 or the initial molten steel containing oxides of small iron scraps used for forced opening is cut and received, and then the molten metal pick-up pot 13 is put in a normal pouring state. Is moved by the pick-up pot cart 12 to be removed from the gap between the ladle 1 and the tundish 4, and then the ladle 1 or the tundish 4 is normally poured to perform continuous casting.

In this case, the hot water pick-up pot 13 is not a deep container for the hot water pick-up pot 5 shown in FIG. 2, but a shallow container such as a dish. The pick-up pot dolly need not be a movable "dolly", but may be, for example, a simple container that is moved by a crane.

In still another embodiment, the initial molten steel containing oxides of small iron scraps used for filling the sliding nozzle 6 or forcibly opening holes is replaced by a tub instead of the hot water pick-up pots 5 and 13 used above. The molten steel discharged from the tub shall be poured into a pot installed at another location by a crane. The direction of movement when removing with a tub does not matter, for example, it may be removed by moving it in a linear motion, or with a rotating shaft provided at the opposite end of the tub or in the middle of the tub to rotate and move. Not to mention good things.

[0016]

As described above, according to the present invention, in continuous casting, when pouring molten steel from a ladle to a tundish, when the sliding nozzle of the ladle is opened, its natural opening from the sliding nozzle is performed. It is possible to cut the initial molten steel containing oxides of small iron scraps for filling or forced opening by holes and forced opening, and mix it into the tundish together with molten steel so that it is not taken into the continuous cast steel slab, A highly clean steel billet can be obtained, and when it is used as a product such as an automobile part, an extremely durable product can be easily manufactured, which is an excellent effect.

[Brief description of drawings]

FIG. 1 is a plan view schematically showing an apparatus provided with a ladle, a tundish, and a hot water pick-up pot in the method of the present invention.

2 is a front view of the device of FIG. 1. FIG.

FIG. 3 is a plan view of the device during preliminary cutting.

FIG. 4 is a schematic elevational view showing a part of an apparatus in which a hot water pick-up pot truck of another embodiment is installed.

[Explanation of symbols]

1 ladle 2 ladle 3 swing tower 4 tundish 5 hot water pot 6 sliding nozzles 7 gutter 8 Hot water pot trolley 9 Mold cover 10 arrows 11 ladle 12 Hot water pot trolley 13 Hot water pot

Claims (4)

[Claims] 1. When pouring molten steel from a ladle into a tundish in continuous casting, a ladle containing a nozzle filling and iron oxide is provided in a hot water pick-up pot provided outside the tundish by opening a sliding nozzle of the ladle. The pre-cutting of the initial molten steel from the tank was received, then the sliding nozzle was opened halfway to transfer the leaked molten steel from the pick-up pot to the tundish, and then the sliding nozzle was fully opened to pour the molten steel from the ladle into the tundish. A continuous casting method for pouring molten metal into a tundish without pouring a pollution source into the tundish. 2. A pick-up pot that is movable in the gap between the ladle and the tundish is prepared, the pick-up pot is set in the gap between the ladle and the tundish, and a sliding nozzle is placed in this set pick-up pot. Immediately after the opening of the nozzle, the preliminary molten steel from the ladle containing the filler and iron oxide was pre-cut and received, and then the pick-up pot that received the pre-cut initial molten steel was moved and removed from the gap between the ladle and the tundish. After that, normal pouring is performed from the ladle to the tundish. The continuous casting method for pouring the pollution source according to claim 1, without injecting the pollution source into the tundish. 3. A hot water pick-up pot that is movable in the gap between the ladle and the tundish is prepared by a hot water pick-up pot cart, and a hot water pick-up pot that receives the pre-cut initial molten steel is moved by the hot water pick-up pot cart. The continuous casting method of pouring the pollution source according to claim 2 without pouring into the tundish. 4. A tub is used to receive the pre-cut initial molten steel instead of the hot water pick-up pot, and the tub that receives the pre-cut initial molten steel is moved to a hot water pick-up pot installed at another location. The continuous casting method of pouring the pollution source according to claim 2 or 3 without pouring the pollution source into the tundish, wherein the molten steel is removed from the gap between the ladle and the tundish by pouring the initial molten steel into the tundish.