JPH09225594A - Method for continuously casting square billet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a continuous casting material which prevents the burning and reduces the surface defect by effectively flowing molten powder into gap between mold wall and solidified shell and can stabilize the continuous casting operation, by adding the vibration in the right angle direction to a casting direction to a tube mold for a square billet during casting with a compact device. SOLUTION: The tube mold which can add the vibration in the right angle direction to the casting direction is used, and the casting is executed while executing by holding the same phase to the upper part and the lower part in the outer wall surface of one side of the mold or the faced two sides or each two sides in four sides in the exciting condition of the positions of within 300mm from the upper end of the mold to the lower part and from the lower end of the mold to the upper part, 50-500cpm number of the vibrations and 0.01-0.1mm amplitude.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a continuous casting method for steel square billets.

[0002]

2. Description of the Related Art When casting a square billet of steel in a continuous casting facility, in order to prevent molten steel from seizing on the mold wall,
The method of supplying lubricant (powder) to the molten steel surface in the mold and reciprocating the mold itself up and down, so-called oscillating, so that the molten powder flows into the gap between the mold wall and lubrication, has been generally used. Has been.

However, when the mold descends by oscillation, there is an effect of drawing the molten powder into the gap between the mold wall and the solidified shell, but when the mold rises, there is no effect of drawing the molten powder. Therefore, there is a problem of molten steel seizing to the mold wall due to lack of molten powder, breakout in severe cases, or damage to the mold wall due to slight seizure, and this causes uneven cooling of the mold. There is a problem that an initial solidified shell having a non-uniform thickness is formed and vertical cracks are generated on the surface of the slab.

In order to solve this problem, Japanese Patent Laid-Open No. 1-1226
No. 45 discloses a technique in which an ultrasonic vibrator is attached to a mold and ultrasonic vibration is applied in a direction perpendicular to the oscillation direction. However, in the case of such high-frequency vibration, when a plurality of vibrators are attached to the mold and vibrated, the phases of the vibrations do not easily match, so the mutual vibrations interfere and cancel each other, and the amount of amplitude is not stable, Therefore, there is a problem that the amount of molten powder to be drawn in is not constant.

Therefore, in JP-A-3-210942, instead of attaching a vibrator to the mold wall, the whole mold is placed on a roller table provided on a base and vibrated at a high frequency of 1000 to 10000 cpm. Although the technology is disclosed, there is a problem that the equipment becomes large and the cost increases.

[0006]

As described above, the conventional vibration method has difficulty in stability of the amplitude amount and high cost of the vibration device. The object of the present invention is to make the molten powder effectively flow into the gap between the mold wall and the solidified shell by applying vibration to the tube mold for square billet during casting in a direction perpendicular to the casting direction with a device as compact as possible. To prevent seizing and reduce surface defects,
An object of the present invention is to provide a continuous casting method capable of stabilizing the continuous casting operation.

[0007]

As a result of various investigations by the inventors of the present invention on the conditions of vibration on the mold wall, it is difficult for the plurality of vibrators in the prior art to have a phase in which the frequency is 1000. This is due to the fact that the vibration is too high at 10000 cpm. If the vibration is of a lower frequency, the phase can be sufficiently adjusted, and even if the vibration is applied to only one side of the mold wall, it is considerably effective. But it turned out experimentally that it has the effect of pulling in the powder.

The present invention has been made on the basis of these findings, and the gist of the present invention is as follows: (1) In a continuous casting method for square billets, vibration can be applied in a direction perpendicular to the casting direction. Using the tube mold, position within 300mm downward from the top of the mold,
And within 300 mm upward from the bottom of the mold,
Under vibration conditions of frequency 50-500cpm and amplitude 0.01-0.1mm,
It is a continuous casting method for square billets, characterized in that casting is performed while vibrating while keeping the same phase on the upper side and the lower side of the outer wall surface of one side of the mold.

(2) In the continuous casting method for square billets,
300mm downward from the top of the mold using a tube mold that can add vibration in the direction perpendicular to the casting direction.
At a position within 300 mm upward from the lower end of the mold and under a vibration condition of a vibration frequency of 50 to 500 cpm and an amplitude of 0.01 to 0.1 mm, the relative outer wall surface of the two sides or four sides of the mold The continuous casting method for a square billet is characterized in that casting is performed while vibrating while maintaining the same phase on both sides and the upper and lower parts.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The material of the tube mold used in the present invention is copper or a copper alloy, and the slab size is mainly 6
It manufactures square billets from 0 mm square to 300 mm square. FIG. 1 shows an example of a tube mold according to the present invention.
This figure is a view showing a vibrating state on one side of the mold wall, and the upper part corresponds to the inlet side in the casting direction and the lower part corresponds to the outlet side.

Copper or copper alloy pad 3 is attached to the outer wall surfaces of the upper and lower tube molds 1, and one end of the vibrator operated by the AC half-wave current of the electromagnet 6 attached to the inner mantel 2 side is attached. Apply vibration to the mold wall by attaching it to the pad. Since the cooling water 7 flows in the gap between the tube mold and the inner mantel, the flexible mount 4 is attached around the vibrator to prevent water leakage.

FIG. 2 shows an example of the result of measuring the electric current of the eccentric shaft rotating motor to be oscillated by changing the vibration frequency. It was found that the smaller the electric current, the smaller the coefficient of friction between the mold wall and the molten steel, that is, a large amount of molten powder flows in, and a sufficient effect is recognized even at a frequency of about 50 cpm.

FIG. 3 shows an example of the result of measuring the current of the oscillation motor by changing the vibration condition, but the effect of inflow of the molten powder is recognized even when the vibration is applied to one side of the mold wall.

FIG. 4 shows an example of the occurrence of surface defects.
The surface cracking index in the figure is a value obtained by measuring the cracking length per unit area of the billet surface and showing the comparative material as 1, but the effect of vibration according to the present invention is sufficiently recognized.

In the case of the present invention, the reason why the frequency is set to 50 to 500 cpm is that it has the effect of allowing the molten powder to flow in even at low frequency vibrations of this level, and the frequency range has a range of casting speed. This is because it corresponds to and changes.

The reason why the vibration amplitude is 0.01 to 0.1 mm is that
If it is less than 0.01 mm, there is no effect of inflow of molten powder,
Also, if you try to apply a vibration of 0.1 mm or more, the vibrator becomes large and it is difficult to install it in terms of space.

[0017]

EFFECT OF THE INVENTION By using the tube mold for square billet of the present invention, continuous casting is performed while vibrating in a direction perpendicular to the casting direction, so that the molten powder is effectively flowed into the gap between the mold wall and the solidified shell. This makes it possible to prevent seizure and at the same time promote the slow cooling of the solidified shell and the uniformization of the shell thickness, thus stabilizing the operation and reducing the surface defects of the cast slab.

[Brief description of drawings]

FIG. 1 is a view showing an example of a tube mold according to the present invention.

FIG. 2 is a diagram showing an example of an effect of reducing an oscillation motor current according to the present invention.

FIG. 3 is a diagram showing another example of the effect of reducing the oscillation motor current according to the present invention.

FIG. 4 is a diagram showing an example of the effect of reducing square billet surface defects according to the present invention.

FIG. 5 is a view showing a general mold used for continuous casting equipment.

[Explanation of symbols]

 1 Tube Mold 2 Inner Mantel 3 Cover 4 Flexible Mount 5 Leaf Spring 6 Electromagnet 7 Cooling Water 8 Molten Steel

Claims (2)

[Claims] 1. A continuous casting method for square billets, using a tube mold capable of applying vibration in a direction perpendicular to the casting direction, using a tube mold at a position within 300 mm downward from the upper end of the mold and 300 mm upward from the lower end of the mold. At the position within the range, under the vibration condition of vibration frequency 50-500cpm and amplitude 0.01-0.1mm, casting is performed while vibrating while keeping the same phase on the upper side and the lower side of the outer wall surface of one side of the mold. A continuous casting method for square billets. 2. In a continuous casting method for square billets, a tube mold capable of applying vibration in a direction perpendicular to the casting direction is used, and a position within 300 mm downward from the upper end of the mold and 300 mm upward from the lower end of the mold. At the positions within the range, under the vibration conditions of vibration frequency 50-500cpm and amplitude 0.01-0.1mm, the opposite sides of the outer wall surface of the opposite two sides or four sides of the mold and the same phase on both the upper and lower sides A continuous casting method for square billets, which is characterized in that casting is carried out while maintaining the vibration.