JPH0342139B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a belt cooling device for a belt caster, and more particularly, to a structure of a cooling device disposed on the back side of a belt for supporting the long sides of a cast slab. This is a proposal regarding drainage openings.

A belt caster is a continuous thin slab casting machine that directly produces thin slabs (so-called sheet bars, etc.) with a thickness of 50 mm or less from molten steel.

(Prior Art) A narrow belt caster using a pair of moving metal belts with part of the running path facing each other (circular rotation) is disclosed in Japanese Patent Application Laid-open No. 1983-
There is one disclosed as No. 92154. The belt caster in this known technology is equipped with a cooling device called a "cooling pat" which has a large number of supply/drain ports facing the belt behind the metal belt. The belt is cooled by forming a running water film between the pad and the belt.

However, between the cooling pad and the belt (liquid passage space), the belt tension fluctuates due to belt centering, etc., resulting in non-uniformity in the width direction (the slab takes on the shape of a hollow). Therefore,
There was a problem in that the thickness of the cooling liquid film flowing through the liquid passage space also became non-uniform, and as a result, the cooling in the belt width direction also became non-uniform.

The present applicant has previously proposed a solution to these problems in Japanese Patent Application No. 12151/1982, but the objective has not been completely achieved and improvements are still needed. there was.

(Problems to be Solved by the Invention) In the prior art in this field, uniform support by the cooling water film in the width direction of the belt is inhibited, and the entire belt bends in an arched manner. (2) Occurrence of casting due to leakage between the belt and the side plate, (3) Statesking break that occurs between the belt and the side plate. Outs inevitably occur.

(Means for Solving the Problems) The present invention solves the above-mentioned problems of the conventional technology that require a solution by changing the drainage pressure loss (drainage pressure distribution) corresponding to the belt width direction of the cooling pad. Even when the same flow rate of cooling water is supplied into the cooling pad, the fluid pressure distribution in the belt width direction can be adjusted to prevent bowing deformation of the belt. The basic idea was to raise the water to strengthen the contact with the side plate and prevent the occurrence of cast-backs, etc., and we developed a cooling pad with a drainage port structure as shown in Figures 1 and 2, that is, a cooling device. suggest.

Such a cooling device has the following features: (a) drain ports opened facing the belt are arranged at intervals along the belt width direction, and the drain ports are arranged only at positions closer to the center of the belt width direction; (b) Drain ports that open facing the belt are arranged at intervals along the belt width direction, and the hole diameter of the drain ports decreases as the drain ports approach the ends in the belt width direction. It is a smaller version of . Although a slit-like form is conceivable as the form of the drainage port, a hole-like form is preferably used.

In the case of (a) above, the width W of the cooling pad is 1000 to 1500.
mm, drain holes at positions 20 to 200 mm from the ends should be blocked or not provided at all, and should be placed only at positions closer to the center in the belt width direction. Also
In the case of (b), when the diameter of the drainage hole at the center is Wc and the diameter at the end is We, the value should be We/Wc<1.

(Function) By changing the pressure drop in the drainage path in the belt width direction between the center and the ends, the thickness of the cooling water flow film becomes uniform, eliminating deflection in the belt and width direction. This prevents hollow deformation of slabs and also prevents boiling, casting, and breakouts.

The reason for the numerical limitation is that the pressure loss of the drain hole increases from the center of the width toward the ends, so that under the same flow rate, the pressure loss characteristic is as shown in FIG. 6. To increase the pressure at the belt end, We/Wc<1
should be met.

(Example) The device of the present invention will be explained using an example in which it is applied to a belt caster shown in FIG. The illustrated belt caster is of a narrowing type, and includes a pair of rotatably movable metal belts 1 and 2 arranged opposite each other to form a gap for holding molten steel and its solidified slab over a predetermined distance. A pair of fixed side plates (not shown) located between both belts and near the side edges constitute a casting space 3 having a tapered tip, and is used for cooling the metal belts 1 and 2. Therefore, cooling pads 4 and 5 are arranged on the back side with a liquid passage space between them.

The cooling pads 4 and 5 are hole-shaped as shown in FIGS. 1 and 2, but in the one shown in FIG. This is an example of reducing the pressure drop in the drainage path of the drain, and the one in Figure 2 has a structure in which the drain hole 6 near the end is eliminated, and the drain hole 6 is placed only near the center, and the diameter gradually increases toward the center. .

Therefore, as a conventional example, we have developed a cooling pad with 16 drainage holes of 7mmφ arranged at 20mm pitch on one side in the belt width direction, and as an example of the present invention with the structure shown in Fig. 5mmφ, 5.5mmφ,
Gradually increase the size to 6mmφ, 6.5mmφ, 7mmφ,
The remaining 11 pieces up to the center are 7mmφ and 20mm
A cooling pad with a total of 16 holes arranged at a pitch.As an example of the present invention with a structure corresponding to Fig. 2, 100 mm from the end is free of holes, and a total of 12 7 mmφ drainage holes are installed inside of it up to the center at a 20 mm pitch. Using three types of open cooling pads, belt deflection and water pressure distribution were investigated. The results are shown in Figure 4, A and B. 5A and 5B are graphs showing a comparison between the present invention and the conventional example in terms of the occurrence rate of overcasting and changes in slab thickness, and it can be seen that the effect of the present invention method is remarkable.

(Effects of the Invention) As explained above, according to the present invention, in addition to being able to reliably obtain slabs of a constant thickness, stable continuous casting is possible without cast casting, boiling, and breakouts caused by them. Operations can be carried out.

[Brief explanation of drawings]

1 and 2 are both partial sectional views showing a part of the belt cooling device of the present invention, FIG. 3 is a schematic diagram of a belt caster employing the device of the present invention, and FIGS. , Figures 5A and 5B are graphs showing the effect of the present invention on the incidence of overcasting and the change in slab thickness; FIG. 6 is a graph showing the relationship between water supply hole diameter and water supply pressure loss. 1, 2...metal belt, 3...casting space, 4,
5... Cooling bed, 6... Drain hole.

Claims (1)

[Scope of Claims] 1. At least one side of the part corresponding to the mold that faces each other is constituted by a metal belt that moves in synchronization with the drawing of the slab, and has a cooling liquid supply and discharge function behind the metal belt. In a belt cooling device for a belt caster in which a cooling device is installed to cool slabs across the belt, drainage ports opening facing the belt of the cooling device are arranged at intervals along the width direction of the belt. 1. A belt cooling device for a belt caster, characterized in that the drain port is located only at a position closer to the center of the belt in the width direction. 2 At least one side of the part corresponding to the mold that faces each other is made up of a metal belt that moves in synchronization with the casting process, and a cooling device that has the function of supplying and discharging a cooling liquid is arranged behind the metal belt. In a belt cooling device for a belt caster that cools slabs across a belt, drainage ports opening facing the belt of the cooling device are arranged at intervals along the width direction of the belt, and A belt cooling device for a belt caster, characterized in that the hole diameter of the drain port is made smaller as the drain port approaches an end in the belt width direction.