JPH05245592A - Twin roll type continuous casting method - Google Patents

Abstract

PURPOSE:To prevent the sticking of solidified metal to a flapper inserted into a twin roll type continuous casting for producing a cast strip. CONSTITUTION:In this twin roll type continuous casting method, the flapper 4 for fixing a solidification starting point 6 of molten metal is inserted into a molten metal pouring basin part 3 in a continuous caster, and the casting is carried out while applying vibration to the flappers 4 in the peripheral directions of the rolls. By this method, the sticking of the solidified metal is prevented and the solidification starting point is kept clean and the solidified shell having the normal thickness is developed and accuracy of the cast strip is kept. Further, the cast strip having good surface characteristic without cold shut defect caused by intermittent detachment of the solidified metal is obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuous casting method capable of preventing metal from adhering to a charged flapper in twin roll type continuous casting for producing a thin plate slab.

[0002]

2. Description of the Related Art A twin-roll type continuous casting method in which molten steel is poured between two rolls rotating inward and a thin metal plate is cast is known as a Bessemer method.

In this method, two rolls are arranged at appropriate intervals, and when the molten metal is poured from above and rotated inside each other, the poured molten metal comes into contact with the rolls to remove heat, As a result, a solidified shell is formed on the roll surface,
The two solidified shells are joined together as the roll rotates, and are further pressed to form a slab having a predetermined thickness, which is then delivered below the roll to produce a thin slab.

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.

As a technique for controlling the distance from the solidification start point to the roll kiss point, for example, Japanese Patent Publication No. 62-5881.
There is a technique of a twin roll type casting and rolling mill disclosed in Japanese Patent Publication No. 1 and its control method.

According to this technique, a flapper for adjusting the contact area between the roll and the molten steel is provided in the molten metal pool formed by two rolls, and the position of the flapper sliding on the roll surface is desired. It is a control method of a twin roll type casting and rolling mill in which the contact area between the molten steel and the roll in the molten metal pool is controlled by setting the value to control the thickness of the solidified shell formed.

In this case, the formed thickness of the solidified shell is approximately proportional to 1/2 to 1 power of the arc length from the solidification start point where the tip of the flapper contacts the roll to the roll kiss point. The longer the, the faster the solidified shell will grow. In this way, without being affected by the fluctuation of the molten metal surface in the molten metal pool, the position of the flapper is adjusted appropriately to stabilize the solidification start position and control the thickness of the solidification shell, maintaining the manufactured slab with high accuracy. can do.

[0008]

By the way, this technique is
When the operation is continued for a long time, as shown in FIG.
Of the base metal, that is, the surface of the solidification starting point 6, adheres to the surface of the solidification starting point 6, and the adhered and grown metal is intermittently peeled off and caught in the solidification shell, causing a surface defect of the cold shut 12. Further, the position of the solidification starting point 6 changes during the operation, and the thickness of the solidified shell 5 formed changes, which deteriorates the accuracy of the slab to be manufactured.

The present invention has been made in view of the above problems,
A twin-roll continuous casting method for producing a thin plate slab provides a continuous casting method for preventing adhesion of metal to a flapper that has been charged.

[0010]

The present invention provides a twin roll type continuous casting method in which a molten metal pool portion formed between two rolls is equipped with a flapper for fixing the solidification start point of the molten metal. It is a twin roll type continuous casting method characterized in that the flapper is cast while applying vibration in the roll circumferential direction.

[0011]

[Function] The flapper charged in the basin is cooled by contacting the back surface and the upper half with outside air or a roll for casting,
The temperature is usually lower than that of the molten metal. Therefore, when the molten steel in the pool holds in contact with the flapper, it is cooled and adheres and grows as a base metal.

According to the present invention, the flapper is cast while vibrating in the circumferential direction of the roll to prevent the metal from sticking and growing on the flapper, and also to prevent cold shut defects from occurring. This is to maintain the position of the solidification starting point normally and maintain the thickness accuracy of the slab produced.

The vibration applied to the flapper is influenced by the frequency f (1 / sec) and the one-sided amplitude a (mm), and the product value f · a is preferably 5 ≦ f · a ≦ 100. . If the value of f · a is less than 5, cold shut remains without the effect of vibration, and the value of f · a is 10
When it exceeds 0, horizontal wrinkles occur in the solidified shell that is generated,
The surface quality becomes poor.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example of an apparatus suitable for applying vibration to a flapper in a twin roll type continuous casting machine.

Reference numerals 1a and 1b are a pair of casting rolls. Side weirs 2 are attached to opposite side surfaces of the upper rolls to form a pool 3 of molten metal between the rolls. Each of the roll surfaces of the basin 3 has a flapper 4
Are charged along the roll from above, and the solidification shell 5 grows in proportion to 1/2 to 1 power of the arc length from the solidification start point 6 where the flapper 4 contacts the roll to the roll kiss point 7.

Reference numeral 8 denotes a vibration generator of the flapper 4, which gives vibration of a constant frequency and amplitude to the flapper 4 from a motor 8a via an eccentric cam 8b, and a metal is fixedly grown at a solidification start point 6. Prevent.

In this way, by constantly applying a constant vibration to the flapper 4, the metal is never fixed to the flapper 4. Therefore, the solidification start point 6 is always kept clean, and by keeping the position constant, the solidification shell 5 having a normal thickness is produced, and the accuracy of the manufactured slab is maintained.
Further, it is possible to prevent the generation of cold shut defects due to the intermittent peeling of the metal and obtain a slab with good surface properties.

[0018]

As described above, according to the continuous casting method of the present invention, by vibrating the flapper while casting, the adhesion of the metal is prevented, the solidification starting point is always kept clean, and the normal thickness is maintained. The slab produced by producing the solidified shell can be maintained in accuracy, and the occurrence of cold shut defects due to the intermittent peeling of the metal can be prevented to obtain a slab with good surface quality without product defects.

[Brief description of drawings]

FIG. 1 is a side view showing an example of an apparatus suitable for applying vibration to a flapper in a twin roll type continuous casting machine.

FIG. 2 is a diagram for explaining a phenomenon of cold shut due to slag and the like that have adhered and grown.

[Explanation of symbols]

 1a, 1b Casting roll 2 Side weir 3 Hot water pool 4 Flapper 5 Solidification shell 6 Solidification start point 7 Roll kiss point 8 Vibration generator 8a Motor 8b Eccentric cam 11 Attached metal 12 Cold shut

Claims (1)

[Claims] 1. A twin-roll type continuous casting method in which a flapper for fixing the solidification start point of the molten metal is loaded in a molten metal pool formed between two rolls, and the flapper is vibrated in the roll circumferential direction. A twin-roll type continuous casting method characterized by casting while adding