JPH049619B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Related Industrial Field) The present invention relates to an improvement of a hot water supply section in a continuous track type casting machine.

(Prior Art) Fig. 4 shows a conventional endless track type continuous casting machine (hereinafter referred to as a caster), particularly a twin belt caster for steel. As shown in FIG. 4, the mold of the twin belt caster has a structure in which a lower belt 1, an upper belt 2, and dam blocks 3 are sandwiched between the upper and lower belts on both left and right sides, and are inclined downward. In this mold, as shown in FIG. 5, molten metal 5 is supplied by flowing down onto the lower belt 1 from a hot water supply gutter 4.

Therefore, the molten metal 5 flows into the mold at a distance L from the downstream point of the lower belt 1, but even before this flowing, it is cooled and starts solidifying at the contact surface with the lower belt 1. However, it is subsequently remelted by molten metal supplied later.

Further, due to fluctuations in the amount of hot water supplied and fluctuations in the flow of hot water flowing into the mold, the mold surface 6 constantly fluctuates along the lower belt 1, and this also causes the molten metal 5 to repeatedly solidify and remelt.

In this way, the lower surface of the slab 7 undergoes a complicated solidification process, and wavy wrinkles called molten metal wrinkles are formed on the surface, and in severe cases, the molten metal further covers the solidified film, causing the solidified film to form. A surface flaw called double skin is formed. Also hot water surface (meniscus) 6
When the hot water flows into the hot water, the falling energy due to the difference in height from the hot water supply gutter 4 to the hot water level 6 causes bubbles due to swirling currents and intense stirring. These air bubbles permeate into the inside of the caster along with the flow of molten metal, and are captured when the slab solidifies, creating cavities called blowholes. Such defects on the slab 7 cause blemish defects and the like in subsequent rolling steps, so surface treatment is required to remove them, and untreated rolled products cannot be made into products.

Moreover, the molten metal 8 flowing down from the hot water supply gutter 4 also flows up to the opposite side of the mold from the point where it flows down.
The smaller the inclination angle θ of the mold, the more likely it is that the mold surface 6 will exceed the upper limit U point and overflow. Furthermore, with respect to the vertical fluctuation h of the mold surface 6, the fluctuation along the lower belt 1 is magnified as the inclination angle θ of the mold becomes smaller. However, there was no escape from this problem, which was extremely dangerous because it overflowed.

On the other hand, as shown in Fig. 6, a method of inserting a hot water supply nozzle 9 between the upper and lower belts 1 and 2 to maintain the molten metal level 5 outside the mold is also considered, but the level of the molten metal is high when viewed from the mold entrance. Therefore, the static pressure of the molten metal 5 at the nozzle tip is large, and the molten metal leaks from the gap existing between the upper and lower belts 1, 2 and the nozzle tip. Furthermore, due to thermal deformation of the nozzle tip, it may come into contact with the upper and lower belts 1 and 2 and damage them. Furthermore, if the thickness of the slab is thin, the nozzle hole will inevitably become smaller, and the nozzle will easily become clogged, making it extremely difficult to put it into practical use.

Furthermore, in the conventional twin belt caster shown in Fig. 4, if a fixed short side weir and an upper weir were simply provided in place of the dam block 3, the solidified shell would remain attached to the weir, making continuous casting impossible. Ta.

(Problems to be solved by the invention) Solving the problems faced by the prior art,
In other words, the surface quality of the slab should be free of wrinkles, double skin, etc., the blowholes that occur inside the slab should be eliminated, the thermal shock to the belt should be reduced, and its lifespan should be greatly extended. To stabilize the operation by eliminating the insertion of molten metal into the gap of the dam block, which accounted for most of the operational troubles of conventional twin belt casters.
The challenge is to prevent the risk of overflow even when the hot water level changes rapidly.

(Solution Means of the Invention) A cavity having a rectangular cross section is formed by a lower belt, an upper belt, and short side weirs provided with guide rollers and arranged on both left and right sides between these upper and lower belts,
An upper weir connecting the left and right short side weirs is provided on the entry side of the cavity to form a hot water supply section, and the upper weir is connected to a vibration generator for reciprocating the casting direction. do.

(Embodiments of the invention) This will be explained with reference to FIGS. 1 and 2. Reference numeral 11 denotes a lower belt inclined downward from the horizontal, which is rotatably wound between a lower nip pulley 12 and a lower tension pulley (not shown), and is rotated by a drive device (not shown). An upper belt 13 is provided parallel to the lower belt 11 and shifted in the casting direction with respect to the lower belt, and is wound between an upper nip pulley 14 and an upper tension pulley (not shown), and is driven by a drive device (not shown). It is rotated at the same speed as the lower belt 11.

The upper and lower belts 13 and 11 constitute the long side walls of the mold. Reference numeral 15 denotes left and right short side weirs forming the short sides of the mold, which are sandwiched between and opposed to the upper and lower belts 13 and 11.
Further, at the entrance side of the mold, that is, on the lower belt, the left and right short side weirs 15, 15 are connected, and the upper weir 16 close to the lower belt 11 on the lower nip pulley 12 forms a U-shaped hot water supply section. are doing.

Guide rollers 17 are installed on the left and right short side weirs 15, 15.
are installed at several locations on the opposite side of the surface that contacts the slab 18, and the short side weir 15 and the upper weir 16 can reciprocate with the upper and lower belts 13, 11 with appropriate sliding contact or with a slight gap. This is being considered.

Reference numeral 19 denotes a hot water supply gutter, and at the bottom thereof there is a power transmission section consisting of a crank lever 20, a fixed fulcrum 21, and a crank arm 22 for reciprocating the upper weir 16 and the short side weir 15 in the casting direction with minute strokes. and a vibration generator 23 that generates high-cycle reciprocating vibration through eccentric rotational motion.

Note that the frequency of the vibrations provided by the vibration generator 23 is preferably 100 times/minute or more, for example.

(Operation of the invention) While rotating the upper and lower belts 13 and 11 and applying high-cycle reciprocating motion with small strokes to the U-shaped short side weir 15 and the upper weir 16 by the vibration generator 23, a hot water supply gutter is installed in the mold. When the molten metal 24 is supplied from the mold 19, the molten metal 24 is cooled from the outside of the mold and becomes a strip-shaped slab 18.
Continuously cast as

(Effect of the invention) During this casting work, the upper weir 16 is used to raise the molten metal level to ensure the molten metal depth H from the molten metal surface 25 at the hot water supply position a (Fig. 2) to the lower belt. Therefore, the falling flow of the molten metal 24 does not wash the slab shell solidified at the contact portion with the lower belt 11 and prevent it from being remelted.

Furthermore, since the head H ₀ from the hot water supply gutter 19 to the hot water surface is also reduced, the hot water flows extremely quietly at the hot water supply position a, and no bubbles are generated. Since the upper weir 16 and the short side weir 15 perform high-cycle reciprocating micro-vibration, they prevent molten metal from adhering and solidifying compared to a fixed weir. On the other hand, since the dam block 5 is not used as in the conventional method, there is no need to insert molten metal into the gaps between the dam blocks, which was a problem in the conventional method, and the operation is very stable.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a hot water supply section according to the present invention. FIG. 2 is also a side sectional view. FIG. 3 is a view taken in the direction of the arrows in FIG. 2.
FIG. 4 is a side view of a known endless track type continuous casting machine. FIG. 5 is a side sectional view of the hot water supply section. FIG. 6 similarly shows another example of the hot water supply section. In the figure; 1, 11... lower belt, 2, 13...
Upper belt, 3...dam block, 9...hot water nozzle,
12... Lower nip pulley, 14... Upper nip pulley, 15... Short side weir, 16... Upper weir, 17... Guide roller, 18... Slab, 19... Hot water supply gutter, 20... Crank lever, 21... Fixed fulcrum, 22... Crank arm , 23... Vibration generator, 24... Molten metal, 2
5... Hot water surface (meniscus).

Claims (1)

[Claims] 1. A cavity with a rectangular cross section is formed by a lower belt, an upper belt, and short side weirs provided with guide rollers, which are arranged on both left and right sides between these upper and lower belts, and the left and right short sides are formed on the entrance side of the cavity. A continuous track type continuous casting machine, characterized in that an upper weir connecting the weirs is provided to form a hot water supply section, and the upper weir is connected to a vibration generator for reciprocating the upper weir in the casting direction.