JPS5938864B2 - Control method of slab support device in continuous casting - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of controlling a short side support device for a slab in continuous casting.

In recent years, in the field of continuous steel casting, in order to improve productivity, methods such as (1) high-speed casting, and (2) intermediate mold change methods that change the mold width without interrupting casting have already been put into practical use. It is planned.

One of the issues to be solved when performing high-speed casting is the suppression of bulging on the short sides of slabs.

One solution was to implement a slab support device, and the other was to adopt an optimal clearance control method for the slab of the slab support device that could be applied to high-speed casting.

As a conventional method of suppressing the amount of bulging, medium (V = 1
．． 4~1.6 m/mj! Examples of drive modes for the slab support device known in the casting speed range of 1) include (1) a method of moving the slab by delaying the movement of the short side of the mold by the same amount of time; and (2) a method using a detector to detect the short side of the slab. There is a method of detecting the side and bringing a slab support device into contact with the slab, but it is understood that the contact surface of these slab support devices is assumed to be vertical.

(Fig. 1) When the abutment surface of the slab support device is vertical, the following disadvantages may occur.

In other words, when a slab support device perpendicular to the short side of the slab of the tapered ridge is brought into contact with the slab support device, ■ When the slab that comes into contact with the upper part of the slab support device is deformed (a in Figure 2 shows the slab change phenomenon). show.

) ■ When bulging on the short side of the slab that comes into contact with the lower part of the slab support device is induced (Figure 3: The square in the figure shows the phenomenon of clearance occurrence.

) Therefore, in the former case (2), the slab support device shown in Figure 1 is required to have a large driving force and strength because the short side of the slab must be deformed by exceeding the rigidity of the solidified shell. be done.

In the latter case (■), the clearance between the upper end of the slab support device and the short side of the slab is Δ1 = C, but the clearance Δ lower at the lower end is Δ lower - tan θ・L (θ: between the slab support device and the slab Short side bulging occurs by an amount equal to the angle formed by the short side (L: length of slab support device).

(C in Figure 4-2 indicates the occurrence of bulging.

) In other cases, as a compromise between the former (2) and the latter (2), there is a method of deforming the slab that comes into contact with the upper part of the slab supporting device, and creating a clearance smaller than that of the latter (2) between the lower part of the device and the short side of the slab. However, it only reduces the amount of slab deformation and slab bulging to a certain extent, and does not solve the problem.

(Figure 5: In the figure, a indicates slab deformation, and C indicates occurrence of bulging.

) If the slab deformation phenomenon is excessive as shown in FIG. 2, there is a risk that the thin solidified shell of the slab will be destroyed during high-speed casting, causing molten steel to flow out, so it must be avoided as much as possible.

The present inventors solved these problems and developed a control method for a slab support device in order to suppress the occurrence of bulging on the short side of the slab and prevent the occurrence of slab deformation.

That is, an object of the present invention is to suppress the occurrence of bulging on the short side of a slab by a control method that uses a slab support device to always keep the taper value of the short side of the slab the same.

In the present invention, the clearance (Δ) between the short side of the mold and the contact surface of the slab support device is always maintained at Δ−0 by using the short side of the mold and the slab support device.
Alternatively, by maintaining Δ=α (α>0), the occurrence of short side bulging during casting is suppressed to 0 or below α.

Next, a control method during casting according to the present invention will be described.

■ If the width is not changed during casting, set the taper value of the contact surface of the slab support device to the same value as the taper value of the short side of the slab (short side of the mold), and place the slab support device directly on the short side of the slab. Due to the contact, the clearance (Δ) becomes Δ−0 at both the upper and lower points of the slab support device.

The situation is shown in FIG.

At this time, the amount of bulging on the short side of the slab becomes δ=0.

For example, if the short side taper value of the mold is l, then l is as follows.

7=sinθ・L (θ: Angle between the short side of the mold and the vertical, L: Length of the mold) Taper value of the slab support device at this time! If lo is o-1 7o=□, the short side of the slab can be brought into contact with the slab support device (in Fig. 6, 2, X indicates the meniscus position, and y indicates the outer surface of the shell on the short side of the slab.

) In order to suppress short side bulging, it is necessary to keep the clearance value to an appropriate value, but this can be done arbitrarily by selecting the stop position of the slab support device in the range of 0 to IQ mm with respect to the short side of the slab. Can be set to

■ When changing the width during casting, if the distance from the meniscus position at the upper end of the mold to the upper end of the slab support device is Ll, and the casting speed at that time is V, then the start of the taper change of the slab support device is T = L□/ By delaying the short side of the mold by V (27227), the taper value of the short side of the slab and the taper value of the surface in contact with the slab of the slab support device can always be made the same.

If the slab support device is brought into contact with the short side of the slab, the clearance Δ
= 0, and the occurrence of short side bulging can be eliminated.

Note that this clearance Δ can be arbitrarily set by selecting the position at which the slab support device is stopped with respect to the short side of the slab.

By using the present invention, the amount of pulsing on the short side of the slab can be reduced to 0 or within an appropriate safety range in high-speed casting ranges exceeding 1.6 m/min and around 2.0 m/min without deforming the short side of the slab. It is possible to realize a control method for a slab support device during continuous casting that can control the amount of control, and as a result, the effect of contributing to improvement of productivity is extremely large.

Note that this method of controlling the slab support device can be performed not only for width expansion but also for width reduction using the same concept.

[Brief explanation of drawings]

Figure 1 is a sectional view of a conventional slab support device (one side), Figures 2 to 5 are illustrations of defects in the conventional slab support device, and Figure 6
The figure is an explanatory diagram of taper application of the slab supporting device of the present invention, and FIGS. 1 and 8 are diagrams explaining the method of controlling the slab supporting device of the present invention. 1... Mold short side, 2... Slab supporting device, total... Mold short side driving device, 4... Slab supporting device driving device, 5・・・・・・molten steel, 6・・・・・・
- Solidified shell, ■... Casting speed, Ul...
... Mold short side movement speed, U2... Movement speed of slab support device.

Claims (1)

[Claims] 1. In a continuous casting machine that has a short side of the mold that can move in the width direction of the slab and a support device for the short side of the mold that is located below the short side of the mold and can move in the width direction, By keeping the taper always the same as the short side of the slab and moving it to follow the short side of the mold, the slab supporting device can be held in close contact with the slab or with an appropriate gap formed. Characteristic control method of slab support device in continuous casting.