JPH0258024B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for predicting breakout in continuous casting.

[Conventional technology]

Breakout is one of the serious accidents that occur during continuous casting operations. This is a phenomenon in which a part of the solidified shell of a slab breaks during casting, and the molten steel inside the shell flows out. When a breakout occurs, not only does it immediately become impossible to cast, but post-processing requires enormous cost and time, resulting in a significant drop in productivity. For this reason, there has been a strong desire for a method that can reliably predict breakouts and prevent breakouts.

[Problem to be solved by the invention]

However, no method has been proposed that can reliably predict breakouts.

The inventors of the present application conducted various investigations into continuous slab casting machines to find out the causes of the above-mentioned breakout. As a result, an important fact was discovered that abnormalities in the shape of the short side of the slab were observed from 5 to 10 meters, or 5 to 10 minutes before the occurrence of a breakout.

Fig. 1 shows a specific example of this, and the concavity (d) of the short side 2 defined in the cross-sectional view of the slab 1 shown in Fig. 2 gradually decreases from about 10 meters before the breakout occurs. A breakout occurred when the concavity (d) on short side 2 decreased from 1 to 1.5 mm. Note that 3 in FIG. 2 indicates the long side of the slab 1.

Therefore, if the concavity (d) is measured continuously along the length of the slab during casting, especially directly under the mold or cooling grid where breakouts are likely to occur, We obtained the knowledge that it is possible to reliably predict the occurrence of a breakout.

This invention was made based on the above-mentioned knowledge, and aims to reliably predict the occurrence of breakout.

[Means to solve the problem]

The present invention continuously measures the amount of depression on the short side of a slab having a rectangular cross section immediately after being pulled out of a continuous casting mold over the length direction of the slab, and in this way The present invention is characterized in that a breakout occurring in the slab is predicted based on the measured concave amount.

The method of predicting breakout in continuous casting according to the present invention will be explained with reference to the drawings.

FIG. 3 is a schematic plan view of a slab short side shape measuring device used in the breakout prediction method of the present invention.

In FIG. 3, reference numeral 4 denotes a main body of a T-shaped slab short side shape measuring device. Reference numeral 5 designates a pair of standard rollers rotatably attached to both ends of the foot portion 4a of the main body 4, and rolls on both end surfaces of the short side 2 of the slab 1. 6 is a differential transformer built into the main body 1. 7 is a movable core shaft of the differential transformer 6. The movable core shaft 7 protrudes from the support lid 8 fixed to the center of the foot 4a of the main body 4 to the outside of the main body 4. A moving detection roller 9 is rotatably mounted on a shaft, and a signal corresponding to the difference in position between the reference roller 5 and the detection roller 9, that is, the concave amount (d), is sent from the differential transformer 6 (not shown). is designed to be output via the lead wire. The movable core shaft 7 is always given a force by a spring 10 to project outward from the main body 4 . 11 is shown in Figures 4 and 5.
As shown in the figure, it is a water-cooled pipe installed on the main body 4 so that its tip is located at the reference roller 5 and the detection roller 9, and it cools the reference roller 5 and the detection roller 9 and scatters and falls. Cooling water can be jetted from the tip to blow away mold powder, scale, etc. adhering to parts 5 and 9. Cooling water to be supplied to the water cooling pipe 11 can be freely supplied from the external main pipe 11a. Note that cooling water is also supplied into the main body 4, so that the differential transformer 6 can be submerged in water to cool the differential transformer 6 and the main body 4 itself. The cooling water supplied into the main body 4 is jetted out from the drain hole 12 formed in the support lid 8 to the outside of the main body 4 so as to cool the detection roller 9 and the movable core shaft 7 protruding from the main body 4. It's summery.

The head 4b of the main body 4 is rotatably attached to the rod 14 of the air cylinder 13, so that the main body 4 can be moved toward the short side 2 of the slab 1.

Moreover, since the main body 4 is rotatably attached to the rod 14, it can be rotated in the direction of the arrow in FIG. Also, the reference roller 5 can easily follow and roll.

According to the slab short side shape measuring device configured in this way, the reference roller 5 always aligns the short side 2 of the slab 1.
If the air cylinder 13 is operated so as to be in contact with the detection roller 9, the detection roller 9 will roll in the center of the short side 2.
Therefore, the differential transformer 6 continuously outputs a signal corresponding to the concavity (d) of the short side 2. At this time, since the main body 4, reference roller 5, and differential transformer 6 are all cooled by cooling water, problems of thermal deformation and inoperability do not occur. Furthermore, impurities such as mold powder adhering to the reference roller 5 and detection roller 9 are blown away by the cooling water.
As a result, the reference roller 5 and the detection roller 9 smoothly roll on the two short sides.

The above-mentioned slab short side shape measuring device is used to measure the casting radius.
It was installed directly under the cooling grid of a 10.5 m continuous curved slab casting machine to measure the concavity (d) on the short side of the slab, and based on this measurement result, breakout was predicted. The casting conditions at this time are casting width: 1250
mm, slab thickness: 220mm, slab drawing speed: 1.6m/
min, steel type: ordinary steel.

Breakout did not occur when the casting speed was reduced from 1.6 m/min to 0.8 m/min when the concavity (d) of the slab short piece reached 2.5 mm.

〔Effect of the invention〕

As explained above, according to the present invention, breakout can be reliably predicted by continuously measuring the amount of concavity on the short side of the slab in the length direction of the slab. It brings about useful effects such as:

[Brief explanation of drawings]

Fig. 1 is a graph showing the relationship between the length of the cast slab and the amount of concavity (d), Fig. 2 is a diagram showing the cross-sectional shape of the cast slab, and Figs. FIG. 5 is a schematic plan view showing the short side shape measuring device of a cast strip, and FIG. 5 is a side view of the same part. In the drawing, 1...
Slab, 2...Short side, 3...Long side, 4...Body, 5
...Reference roller, 6...Differential transformer, 7...Movable core shaft, 8...Support lid, 9...Detection roller, 1
0... Spring, 11... Water cooling pipe, 12... Drain hole, 13... Air cylinder, 14... Rod.

Claims (1)

[Claims] 1. Immediately after being pulled out of the continuous casting mold, the amount of concavity on the short side of the slab having a rectangular cross section was continuously measured along the length of the slab, and the A method for predicting breakout in continuous casting, comprising predicting breakout occurring in the slab based on the amount of concavity.