JPH01273655A - Method for continuously casting strip and continuous casting machine - Google Patents

Abstract

PURPOSE:To prevent restriction of solidified shell and burning by specifying amplitude and the max. acceleration at the time of retreating in the vibration advancing/retreating short side plate to width direction of a cast slab. CONSTITUTION:At the time of continuously casting a strip, by a vibrating wave form setter, the vibrating wave form is set to 0.05-1.5mm amplitude and 8-49m/s<2> in the range of the acceleration at the time of retreating when the short side plate is apart from the solidified shell. Then, the vibration is given to an exciter based on this and at the same time, the detected results with an accelerometer 16 is compared with the setting vibrating wave form by a vibrating wave form comparing controller, to execute feedback control, and always the short side plate is vibrated under the setting vibrating wave form. By this method, the burning of the short side plate with the cast strip is prevented and operational trouble of breakout, etc., is eliminated and the cast strip having good surface characteristic can be obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a continuous casting method for directly producing thin slabs from molten metal and to a continuous casting machine advantageously adapted to this method.

(Prior Art) Recently, various types of continuous casting machines have been proposed that continuously produce thin slabs such as sheet bars directly from molten metal (the following will be explained using the example of "molten steel"). . Figure 3 shows a typical example.

The illustrated synchronous belt caster is of the narrowing type and is cast through a plurality of guide rolls 3a, 3b, 3c, respectively, while maintaining a gap for holding the cast material such as molten steel or solidified shell over a predetermined distance. metal belts 1 and 2 that support a pair of long side surfaces that are arranged opposite to each other and move axially; The concave short side plates 4 and 5 on the upper and lower sides confine the casting space on four sides.

When molten steel is supplied into the casting space from the immersion nozzle 6, the cooling pad? Metal belt cooled by a, 7b 1.
The molten steel that has come into contact with 2 is drawn downward while forming a solidified shell.

In order to delay solidification on the short sides, it is advantageous to form the inner surfaces of the short side plates in contact with the molten steel with a refractory material. This disclosure discloses a short side plate in which a refractory is supported by a frame part on a metal plate having a frame part.

In addition to supporting the refractories, the provision of the frame is effective in promoting solidification in the corners of the casting space and preventing molten steel from entering between the short side plate and the metal belt.

(Problem to be Solved by the Invention) It is essential for the solidified shell near the short side plate to move in the slab drawing direction at the same speed as the solidified shell on the long side for stable operation. A solidified shell formed on a part of the corner of the side plate may be restrained between the metal belt and a part of the corner, or seizure may occur between the water-cooled surface of the short side plate in contact with the metal belt and the solidified shell formed thereon. shell binding occurs. When the shell is restrained, the solidified shell always breaks between the restrained part and the moving part, leading to defects on the surface of the slab and causing operational problems such as breakouts.

Of course, the same problem occurs even if restraint due to seizure occurs between the solidified shell and the slab in the lower water-cooled part of the short side plate other than at the corner part.

JP-A No. 61-42455 describes how to avoid breakout by applying vibration in the width direction of the slab, but simply applying vibration does not have a sufficient effect, and the above problem is solved. cannot be resolved.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to propose a continuous casting method that applies appropriate vibration to the short side plates to avoid restraint of the solidified shell, and a continuous casting machine that is advantageously adapted to this method.

(Means for Solving the Problem) The inventors conducted various studies on applying vibration to the short side plate of the mold in a continuous casting machine for thin slabs to avoid restraint and seizure of the solidified shell, and found that vibration It was found that it is extremely effective to set the amplitude and the advancing and retreating speed of the short side plates within appropriate ranges, and this invention was completed based on this finding.

That is, the present invention includes a pair of circulating bodies arranged opposite each other that circulate while maintaining a gap for holding molten metal over a certain distance, and a pair of circulating bodies located on both side edges between the circulating bodies. When continuously casting thin slabs by supplying molten metal to a casting space composed of a short side plate that has a concave shape with an upper width and a lower side, vibrations that advance and retreat in the width direction of the slab are applied to the short side plate with an amplitude of 0. This continuous casting method for thin slabs is characterized in that the thickness is 0.05 to 1.5 mm and the maximum acceleration during retraction is 8 to 49 m/s.

The method of the present invention also includes a pair of circulating bodies arranged opposite each other, which circulate while maintaining a gap for holding the molten metal over a certain distance, and a pair of circulating bodies located at both side edges between the circulating bodies. A continuous casting machine for thin cast slabs, in which a casting space is constituted by a pair of short-side side plates that have a concave shape, and a vibrator that applies vibration to the short-side side plates, which drives the vibrator. A vibration waveform setting device that sets the vibration waveform for the vibration, an accelerometer that measures the acceleration of the vibration of the short side plate, and a comparison of the vibration waveform measured by this accelerometer with the set vibration waveform input to the vibration waveform setting device and feedback. A continuous casting machine equipped with a vibration waveform comparison controller for controlling is advantageously suitable.

Next, the present invention will be explained in detail with reference to FIG.

FIG. 1 shows the structure of the short side plate used directly in this invention. In the figure, 8 is a copper plate in which refractories 9 are embedded. This copper plate 8 is fixed to a backup plate 11 via tie bolts 10, and the cooling water is Backup plate 1 for water supply pipe 12a
1, cooling water is guided into the copper plate 8 from here, circulated, and then discharged from the drain pipe 12b, thereby cooling #[8.

The backup plate 11 is supported by a cylinder 13 and support wheels 14, and is provided with a vibrating device 15 on its back surface to apply desired vibrations to the copper plate 8 via the backup plate 11.

Further, an accelerometer 16 is provided at the upper end of the copper plate 8 to detect whether the vibration given by the vibration device 15 is within an appropriate range.

Further, the vibration device 15 includes a vibration exciter 17 as shown in FIG.
, a vibration waveform setting device 18 that provides a desired vibration form, a frequency converter 19 that adjusts the frequency, an output regulator 20 that adjusts the output, and a feedback control by comparing the vibration state obtained from the accelerometer 16 with the set conditions. It is equipped with a vibration waveform comparison controller 21 that performs the following.

The method according to the present invention involves continuous casting of thin slabs, and the vibration waveform setting device 18 has an amplitude of 0.05 to 1.5.
A vibration waveform is set in the range of 8 to 49 m/s" and an acceleration of 8 to 49 m/s when the short side plate leaves the solidified shell. Based on this, vibration is applied to the vibrator 16. At the same time, The detection result and the set vibration waveform are compared by the vibration waveform comparison controller 21 to perform feedback control, and the short side plate is always vibrated with the set vibration waveform.

(Function) Now, the casting space of the twin-belt continuous casting machine shown in Fig. 3 has a water-cooled copper plate 8 and a refractory in the upper part as shown in Fig. 4 (cross-sectional view taken along line A-A in Fig. 3). 9, and the bottom is the 5th
As shown in the figure (sectional view taken along line B-B in Figure 3), there is no refractory material and it is surrounded by water-cooled copper plates. The solidified shell 22 grows along the metal belts 1 and 2 and the short side plates 4 and 5, as shown in FIG. 6, which is an enlarged view of a part of the short side plate corner.
They may enter the gap between the metal belts 1, 2 and the short side plates 4.5, or come into contact with the copper plate 8, causing seizure.

Therefore, the present invention has succeeded in avoiding the above-mentioned phenomenon by applying appropriate vibrations to the short side plates.

That is, first, the amplitude of the vibration applied to the short side plate is 0.
The range is 05 to 1.5M. Because the amplitude is 0.05
If it is less than mn+, the excitation force due to vibration will be small and the effect of separating the solidified shell generated on the surface of the vibrated object cannot be expected.
On the other hand, if the thickness exceeds 1.5 mm, casting tends to occur between the short side plate and a circulating body such as a metal belt.

Furthermore, in vibrating the short side plates, it is important that the maximum acceleration during retreat is 8 to 49 m/s.

As shown in Figure 7, which shows the relationship between the surface defects of the slab and the maximum acceleration when the short side plate retreats, the maximum acceleration is 8m/s'' (
If the speed exceeds 49 m/s, the refractory on the short side plate will peel off, so surface defects will occur frequently.
The following was made.

The maximum acceleration of the short side plate when moving forward may be the same as or different from that when reversing, but from the viewpoint of the durability of the short side plate, it is set at 49.
It is preferable to set it to less than "m/s".

(Example) Next, continuous casting according to the present invention will be specifically explained.

The short side plate shown in Fig. 1 is applied to the twin-belt continuous casting machine shown in Fig. 3, and low carbon aluminum killed steel is cast at a speed of 15 m/min.
When casting a slab with a thickness of 30 mm and a width of 1250 mm, one of the pair of short side plates was set at an amplitude of 0.1, a frequency of vibration of 100 Hz, and a maximum forward and backward acceleration of 39.5 m/s. Figure 8 shows the results of measuring the temperature of the copper plate on the short side plate, which changes when the solidified shell is restrained during casting, and the results of investigating the surface defects of the obtained slab. Each is shown in FIG.

From FIG. 8, it can be seen that there is almost no temperature change in the vibrated short side copper plate, whereas there is a large temperature change in the non-vibrated copper plate. Furthermore, from FIG. 9, it was found that there were many surface defects on the slab when no vibration was applied, and it was also confirmed that vibration in the vertical (slab drawing) direction was not very effective.

(Effects of the Invention) According to the present invention, it is possible to avoid seizure between the short side plate and the slab (solidified shell), eliminate operational troubles such as breakouts, and produce slabs with good surface properties. Is possible.

[Brief explanation of the drawing]

Fig. 1 is a plan view of the short side plate according to the present invention, Fig. 2 is a block diagram of the vibration device, Fig. 3 is an explanatory diagram of the belt caster, Fig. 4 is a sectional view taken along the line A-A in Fig. 3, Figure 5 is a sectional view taken along the line B-B in Figure 3, Figure 6 is an enlarged view of section C in Figure 4, Figure 7 is a graph showing the relationship between vibration acceleration and surface defects, and Figure 8 is a cross-sectional view of part C in Figure 4. FIG. 9 is a graph showing the change in temperature of the copper plate, and FIG. 9 is a graph showing the relationship between vibration of the short side plate and surface defects. 1.2...Metal belts 3a, 3b, 3c...Guide rolls 4.5...
Short side, side plate 6...Immersion nozzle 7a, 7b...
・Cooling pad 8...Copper plate 9...Refractory
10... Tie bolt 11... Backup plate 12a... Water supply pipe 12b... Drain pipe 13
...Cylinder 14...Support wheel 15...
- Vibration device 16... Accelerometer 17... Vibrator
18... Vibration waveform setter 19... Frequency converter 20... Output adjuster 21... Vibration waveform comparison controller Power 5 Figure 6 Figure 7 Figure 8 Figure 9 Sadness

Claims (1)

[Claims] 1. A pair of circulating bodies arranged opposite each other, which circulate while maintaining a gap for holding molten metal over a certain distance, and located on both side edges between the circulating bodies. When continuously casting thin slabs by supplying molten metal into a casting space consisting of a pair of short side plates that are concave in shape, the short side plates are subjected to vibrations that advance and retreat in the width direction of the slab. , amplitude 0.05~1.5mm and maximum acceleration when retreating 8~
A continuous casting method for thin slabs, characterized in that casting is performed at 49 m/s^2. 2. A pair of opposing circulating bodies that circulate while maintaining a gap to hold the molten metal over a certain distance, and a pair of overboards located on both side edges between the circulating bodies. This is a continuous casting machine for thin cast slabs, in which a casting space is formed by a short side plate that has a concave shape, and a vibrator that applies vibration to the short side plate, and a vibration waveform to drive this vibrator. A vibration waveform setting device that measures vibration waveform setting device, an accelerometer that measures the acceleration of the vibration of the short side plate, and a vibration waveform comparison that performs feedback control by comparing the vibration waveform measured by this accelerometer and the set vibration waveform input to the vibration waveform setting device. A continuous casting machine equipped with a controller.