JPH0857595A - Contact limiting plate in twin roll type continuous caster - Google Patents

Abstract

PURPOSE: To keep the precision of a cast slab and to obtain the cast slab having good surface characteristic by forming the surface of a contact limiting plate having material specifying the angle of contact to slag, etc. CONSTITUTION: Side weirs 3 are fitted to both side surfaces of one pair of rolls 2a, 2b for casting to form a molten metal pool part 4. The contact limiting plate 1 is charged on the roll surfaces of the molten metal pool part 4, and a solidified shell 5 is grown in almost proportion to the arc length from the solidified starting point 6 bringing the contact limiting plates 1 into contact with the rolls 2a, 2b to the kissing point 7 of the rolls. Then, the surface of the contact limiting plate at least at the contacting side with the molten metal is formed of the material having >=110 deg. angle of contact to the slag and/or the molten metal. As this material, BN or ceramic containing BN (e.g. BN-Si3 N4 , etc.) is used. By this method, the removing work of the slag, etc., during operation is unnecessary and the production efficiency can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a contact limiting plate for preventing adhesion of slag and metal in a twin roll type continuous casting machine for producing thin plate slabs.

[0002]

2. Description of the Related Art A twin roll type continuous casting machine is known as an apparatus for casting a thin metal plate by injecting a molten metal between two rolls rotating inward. In this device, two rolls are arranged at appropriate intervals, and when the molten metal is injected from above and rotated inwardly relative to each other, the injected molten metal comes into contact with the rolls to remove heat, and as a result, the rolls are heated. A solidified shell is formed on the surface, both solidified shells are joined together with the rotation of the roll, and further pressed to form a slab of a predetermined thickness, which is delivered below the roll to produce a thin plate slab. Used.

In this case, the solidified shell begins to solidify at the point where the molten metal comes into contact with the roll, continues to grow, and becomes a solidified shell having a predetermined thickness at the roll kiss point. Since it becomes a slab, in order to maintain the accuracy of the thickness of the slab to be manufactured, it is necessary to always control the distance from the solidification start point to the roll kiss point to be constant.

For example, in Japanese Patent Publication No. 62-58811, 2
The molten metal pool formed by the individual rolls is provided with a contact limiting plate made of a plate-shaped refractory material for adjusting the contact area between the roll and the molten metal, and the contact limiting plate sliding on the roll surface is provided. A method is disclosed in which the position is set to a desired value and the contact area between the molten metal and the roll in the pool is controlled to control the thickness of the solidified shell formed.

Since the thickness of the solidified shell formed is substantially proportional to the arc length from the solidification start point where the tip of the contact limiting plate contacts the roll to the roll kiss point, for example, if the arc length to the roll kiss point is increased, It is described that the solidified shell grows faster, and the thickness of the solidified shell formed by appropriately adjusting the position of the contact limiting plate is controlled to maintain the produced slab with high accuracy.

[0006]

However, when the above-mentioned contact limiting plate is used for a long time and the operation is continued, in some cases, the metal or slag adheres to the tip of the contact limiting plate, that is, the surface of the solidification starting point. Therefore, during the operation, the position of the solidification starting point fluctuates, the thickness of the solidified shell to be formed changes, the accuracy of the manufactured slab is deteriorated, and the surface quality tends to be poor.

Further, it is difficult to remove the adhered metal and slag during the operation. An object of the present invention is to provide a contact limiting plate capable of preventing adhesion of slag and metal in a twin roll type continuous casting machine.

[0008]

The present invention is intended to solve the above problems, and its gist is to immerse the molten metal in a molten metal pool formed between two rolls of a twin roll type continuous casting machine. In the contact limiting plate that defines the solidification starting point, at least the surface of the contact limiting plate that comes into contact with the molten metal is slag and / or
Or a contact limiting plate of a twin roll type continuous casting machine, characterized in that it is formed of a material having a contact angle with molten metal of 110 degrees or more, and further the surface of the contact limiting plate is formed of BN or BN-containing ceramics. is there.

[0009]

The present invention will be described in detail below. The back surface and the upper half of the contact limiting plate charged in the molten metal pool are cooled by contacting with the outside air or a roll for casting, and the temperature is lower than that of the molten metal. Therefore, the slag and metal floating in the molten metal pool are cooled when they come into contact with the contact limiting plate and adhere to the contact limiting plate, and grow at the tip thereof.

According to the present invention, it is difficult to wet slag and molten metal having a contact angle with molten steel at 1600 ° C. of 110 degrees or more, and the slag and the metal are easily removed even if they adhere. By configuring this contact limiting plate with a material, it is possible to prevent the metal from sticking and growing on the contact limiting plate, maintaining the position of the solidification starting point normally and maintaining the accuracy of the slab produced,
Moreover, a slab having a good surface property is obtained.

When the contact angle is less than 110 degrees, slag and metal are likely to adhere and grow on the contact limiting plate, the position of the solidification starting point changes during operation, and the thickness of the solidified shell formed changes. The accuracy of the slab produced by this method is deteriorated, and the surface quality is also deteriorated. As a method of forming the surface of the contact limiting plate with a material having a contact angle of 110 degrees or more, the contact limiting plate itself is used as a whole material, or a plate of that material is attached to the surface of the contact limiting plate, or Any of forming a coating film containing the material by brushing, spraying or the like on the surface of the contact limiting plate may be employed.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 3 is a side view showing an example of a twin roll type continuous casting machine, 2a and 2b are a pair of casting rolls, and side weirs 3 are attached to both side surfaces of the upper part of the opposing rolls. A molten metal pool 4 is formed between them.

The roll surfaces of the pool 4 are contact-controlled.
The limit plate 1 is inserted from above, and the solidification shell 5 is the contact limiting plate.
From the solidification start point 6 where 1 touches the roll to the roll kiss point 7
It grows almost in proportion to the arc length at. FIG. 1 shows the contact of the present invention.
3 is a perspective view showing an example of the structure of the limiting plate 1. FIG. Contact limiting plate
Is a material of Table 1 which has difficulty in adhering to slag and metal (example
For example, BN, BN-Si₃N _FourEtc.), and support 8
It is pinched by.

[0014]

[Table 1]

Roll diameter 1 using the contact limiting plate of the present invention
The results of casting with a twin roll continuous casting machine having a roll width of 200 mm and a roll width of 1300 mm will be described below.

Example 1 A contact limiting plate made of BN-Si ₃ N ₄ material shown in Table 1 was used.
After casting 120 tons of molten steel at 00 ° C for 120 minutes,
The slag and metal floating in the pool will not be fixed to the contact limiting plate 1. Therefore, by keeping the position of the solidification starting point 6 always constant, the solidified shell 5 having a normal thickness is formed and manufactured. The slab precision was maintained and the slab with good surface quality was obtained.

Example 2 A contact limiting plate in which a BN plate was adhered to the surface of the molten metal dipping portion of the contact limiting plate made of Al ₂ O ₃ -C (contact portion with the molten metal) without any gap (a cross-sectional view is shown in FIG. 2). ) At 1600 ° C
When 120 tons of molten steel of No. 2 was cast for 120 minutes, the slag and metal floating in the molten metal pool did not adhere to the contact limiting plate as in Example 1, and the accuracy and surface quality of the produced slab were good. there were.

Comparative Example 1 On the other hand, when molten steel at 1600 ° C. was cast using a contact limiting plate made of a material containing Al ₂ O ₃ —C as the main component shown in Table 1,
The metal adhered to the tip of the contact limiting plate or near the surface of the molten metal, and grew with time. As a result, the solidification starting point is not constant in the width direction of the roll, and the thickness of the solidified shell to be formed is changed to deteriorate the accuracy and surface quality of the produced slab. Casting was stopped.

Comparative Example 2 Using the contact limiting plate made of Al ₂ O ₃ material shown in Table 1, 160
When the molten steel at 0 ° C. was cast, as in Comparative Example 1, the metal adhered and grew on the tip of the contact limiting plate or near the molten metal surface, so the casting was stopped at 35 tons for 35 minutes.

Comparative Example 3 When molten steel at 1600 ° C. was cast using the contact limiting plate made of the C material shown in Table 1, the contact limiting plate was severely melted, and the molten steel dipping portion was damaged at 15 tons for 15 minutes. I canceled it.

[0021]

As described above, according to the present invention, the contact limiting plate is made of a material which is difficult to adhere to the metal to prevent the slag and the metal from sticking and growing on the contact limiting plate. It is possible to maintain the position of the solidification starting point normally and maintain the accuracy of the manufactured slab, and to obtain a slab with good surface properties.

Further, it is not necessary to remove slag or the like during the operation, the operating rate of the casting machine is improved, and the production efficiency can be increased.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example of a contact limiting plate of the present invention.

FIG. 2 is an A- of FIG. 1 showing an example of a contact limiting plate of the present invention.
It is an A'cross section figure.

FIG. 3 is a side cross-sectional view showing an example of a twin roll type thin plate continuous casting machine.

FIG. 4 is a diagram showing a method for measuring a contact angle with molten steel according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Contact limiting plate 2a, 2b ... Casting roll 3 ... Side weir 4 ... Melt pool 5 ... Solidification shell 6 ... Solidification start point 7 ... Roll kiss point 8 ... Supporting tool

[Procedure amendment]

[Submission date] September 26, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 2

[Correction method] Change

[Correction content]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction content]

[0008]

The present invention is intended to solve the above problems, and its gist is to immerse the molten metal in a molten metal pool formed between two rolls of a twin roll type continuous casting machine. In the contact limiting plate that defines the solidification starting point, at least the surface of the contact limiting plate that comes into contact with the molten metal is slag and / or
Or a contact limiting plate of a twin roll type continuous casting machine, characterized in that it is formed of a material having a contact angle with molten metal of 110 degrees or more, and the surface of the contact limiting plate is formed of BN or BN-containing ceramics. Is.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction content]

When the contact angle is less than 110 degrees, slag and metal are likely to adhere and grow on the contact limiting plate, the position of the solidification starting point changes during operation, and the thickness of the solidified shell formed changes. The accuracy of the slab produced by this method is deteriorated, and the surface quality is also deteriorated. As a method of forming the contact limiting plate surface with a material having a contact angle of 110 degrees or more, the entire contact limiting plate itself is used as the material, or a plate of that material is attached to the surface of the contact limiting plate, or Any of forming a coating film containing the material by brushing, spraying or the like may be adopted on the surface of the contact limiting plate.

Claims (2)

[Claims] 1. A contact limiting plate, which is immersed in a molten metal pool portion formed between two rolls of a twin roll type continuous casting machine and defines a solidification start point of the molten metal, contacts at least the side that comes into contact with the molten metal. A contact limiting plate for a twin roll type continuous casting machine, characterized in that the limiting plate surface is formed of a material having a contact angle with slag and / or molten metal of 110 degrees or more. 2. The contact limiting plate for a twin roll type continuous casting machine according to claim 1, wherein the surface of the contact limiting plate is formed of BN or a ceramic containing BN.