JPS61199554A - Method and device for continuous casting - Google Patents

Abstract

PURPOSE:To solidify a molten metal without forming a pouring basin and to form continuously an ingot without cracking and surface roughening by pouring the molten metal onto the respective circumferential surfaces of juxtaposed cooling rolls, cooling the molten metal to solidify and joining and cooling the solidified metals in a roll gap part. CONSTITUTION:A roll gap G is set to the sectional size of the prescribed ingot and a dummy bar 15 is fed by feed rolls 12. The roll gap G is closed by a plug 13 at the top end of the dummy bar. Both cooling rolls 1, 2 are rotated at a low speed and the molten metal 4 is poured at a low rate from nozzles 5, 5' of a tundish 6 onto the circumferential surfaces of the rolls 1, 2. The molten metal 4 accumulates to a prescribed amt. (h) in the gap G and solidifies. The feed rolls 12 are rotated backward to pull the bar 15 and to draw the billet out of the spacing between the rolls 1, 2 when the solidified metal sticks to the plug 13 at the top end of the bar 15. The bar 15 is emitted from the rolls 12 and is cut by the ingot 8 and when the dummy bar is discharged from the line, the ingot is cast at the speed at which the unsolidified ingot 8' is not broken by increasing the casting conditions to pouring rates Q2, Q2', circumferential speeds Vr2, Vr2' of the rolls and the cooling rates QH2, QH2' of the rolls 1, 2.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a continuous casting method and apparatus.

[Prior art] Conventionally, when manufacturing raw products such as billets, slabs, carvings, and strips, molten metal is cast into an ingot, the ingot is uniformly heated in a soaking furnace, and then stretched in a hot rolling mill. However, in recent years, there has been a demand for omitting the intermediate steps of the conventional raw product manufacturing method and directly manufacturing raw products such as strips by casting.

Therefore, recently, a twin-roll continuous casting machine has been proposed as a device for directly manufacturing raw products by casting. As shown in Fig. 4, this twin-roll continuous casting machine has two cooling rolls a and a arranged horizontally with a roll gap 9, and two cooling rolls a and a fixed at the top of a roll gear g (in the figure). side dam (only one shown), b and cooling roll a,
A tundish C to IId was poured into this tundish, and a strip e having a required thickness was produced by rotating the cooling rolls a and a. It is something.

[Problems to be Solved by the Invention] In such a twin-roll continuous casting machine, in order to temporarily store the uniformly heated hot water d in a wet reservoir, cooling rolls a, a circumferential surface and a side weir, b and At the contact point with the atmosphere, the so-called triple point p, ld
is cooled and the temperature drops, creating hot water boundaries where the temperature drops independently in the high-temperature ld in the hot water tank. On the other hand, the molten metal d that is cooled on the circumferential surfaces of the cooling rolls a and a is sent out from the roll gap and is intended to be made into a strip e, but the molten metal boundary that occurs at the triple point p is incidentally generated. However, with the passage of time, it grows and passes through the roll gap Q together with the cooling roll a and the melting layer cooled on the circumferential surface of a, and is shaped as a strip e. Therefore, there is a temperature difference between the melt boundary formed by cooling at the triple point P and the melt boundary formed by cooling on the circumferential surface of the cooling rolls a and a, and these melt boundaries are not mixed uniformly and are ubiquitous. When the metal crystallizes and solidifies, the bonding strength of the crystals at the boundaries of each melting layer becomes uneven, causing cracks, and furthermore, the time for crystal solidification of each melting layer is different. This also caused skin irritation.

The present invention seeks to eliminate the above-mentioned drawbacks and to continuously produce high quality strips.

[Means for Solving the Problems] - The present invention has a configuration including cooling rolls arranged in parallel and a tundish for pouring molten metal onto the circumferential surface of each of the cooling rolls.

[Function] Therefore, an unsolidified slab portion with a solidified shell is formed on one side of each molten metal poured onto the circumferential surface of each cooling roll, and the unsolidified slab portion is passed through the roll gap. By merging and cooling the slabs, slabs are continuously produced. Further, depending on the degree of cooling of the peripheral surface of the roll, a completely solidified high-temperature slab is pressed and cooled in a roll gap to produce a slab.

[Example] Hereinafter, the present invention will be described in detail with reference to the drawings.

As shown in FIG. 1, a first cooling roll 1 and a second cooling roll 2 are each provided with a cooling water channel for water-cooling the outer circumference of the roll.
are arranged in parallel so that the amount of roll gap G formed by both cooling rolls 1.2 can be adjusted, and seven flange-shaped side weirs 3, 3 are provided at both ends of the first cooling roll 1 in the axial direction. (only one is shown in the figure), and both cooling rolls 1.2
Above the cooling rolls 1 and 2 are separately placed 1 (
A tundish 6 having a nozzle 5,5' for supplying molten metal) 4 is provided, and the tundish 6 is provided with flow rate adjustment rods 7, 7' for adjusting the amount of poured metal. Prepare accordingly.

Further, at a lower position of the oil gap G, outlet guides 9.9 are provided facing each other to guide the unsolidified slab 8' formed by the cooling rolls 1 and 2 downward. , 9 are provided with an appropriate number of cooling water sprays 10 and guide rollers 11 facing each other for cooling the unsolidified slab 8' to form the slab 8. A feed roll 12 for feeding the slab 8 to required downstream equipment is arranged at the position.

A method of operating a continuous casting apparatus having such a configuration will be explained.

First, as shown in FIG. 2, with the roll gap G set to the required cross-sectional dimension of the slab, the tip plug 13 is
A dummy bar 15 consisting of a chain 14 and a dummy bar 15 is fed by a feed roll 12, and a tip plug 13 closes a roll gap G. Next, both cooling rolls 1.2 are moved at slow speeds Vr+, V
The hot water 4 is rotated at r+', and the hot water 4 is sent to each cooling roll 1 from the nozzle 5.5' of the tundish 6 at a small flow rate Q+, Q+'.
．． Pour onto the circumference of 2. When the required amount of feeder 4 accumulates in the roll gap G, solidifies, and sticks to the tip plug 13 of the dummy bar 15, the feed roll 12 is reversed and the dummy bar 15 is removed.
, and the slab is pulled out from between 1 and 2 of the cooling rolls 4 times. At this time, the amount of molten metal poured Q + + 01', the peripheral speed of the roll ■r1.
■r1', heat removal IQ++ per unit time of the first cooling roll 1 and the second cooling roll 2;

Casting conditions such as QI-11' are set so that the unsolidified slab 8' emerging from the 0 portion of the roll gap forms a shell thick enough to prevent breakage. After the dummy par 15 leaves the feed roll 12, is cut into slabs 8, and is discharged from the line, the casting conditions are determined.
', roll circumferential speed Vr2°vr2', first cooling roll 1
and the amount of heat handled per unit time of the second cooling roll 2 QH2,0
)-12', respectively, and the unsolidified slab 8' is cast at production speed while forming a shell having a thickness that does not break. The casting process is completed by stopping the pouring of the tandish. Note that the casting conditions are determined based on the width, thickness, and casting speed of the slab 8 to be manufactured. Alternatively, the operation may be performed automatically by a control device incorporating a program.

In the above, the hot water 4 poured onto the circumferential surface of the cooling roll 1.2
is in a molten state on the atmospheric side, but a solidified shell gradually grows on the side that is in direct contact with the cooling rolls 1.2, and unsolidified shell parts Bn and 2 are formed on the cooling rolls 1 and 2, respectively. Bn is formed. Therefore, by rotating the cooling roll 1.2, the unsolidified slab parts Bn and Bn, in which a solidified shell is formed only on one side, are merged at a roll gap of 0 to form an integrated unsolidified slab 8'. . Furthermore, this unsolidified slab 8' is guided by the outlet guides 9, 9 and advances downstream, and is sequentially cooled by each cooling water spray 10, thereby becoming a strip-shaped slab 8 that is completely solidified to the inside.

In this way, the water 4 supplied from the nozzles 5.5' of the tundish 6 is cooled one side at a time by the cooling rolls 1.2, eliminating the need for a fixed reservoir.
Problems such as cracks and rough skin caused by stress are eliminated.

In the above embodiment, the contact length is set to AB-CD so that the lagoon 4 supplied to the first cooling roll 1 and the second cooling roll 2 are cooled to the same temperature. The length can be changed as appropriate depending on the humidity setting of the cooling roll 1°2. Further, in the above embodiment, the tundish 6 is an integrated type, but the first cooling roll 1 side and the second cooling roll 2 side are made separate, or a partition is provided in the tundish 6, etc., so that the cooling roll 1. Clad steel can be easily produced by supplying steels 4 of different steel types to steels 2 and 4, respectively. Furthermore, in the embodiment described above, the slab 8 is pulled out directly below the roll gap G.
As shown in the figure, it may be handled in a direction other than directly downward along one cooling roll 2 (or 1). Alternatively, one slab may be manufactured by completely solidifying the lagoon on the circumferential surface of each roll and pressing two hot slabs together with an O-ru gap.

[Effects of the Invention] As explained above, according to the present invention, the molten metal poured into two hands is cooled one side at a time, and then joined together for further cooling.
Since a solidified shell is formed without creating a fixed pool on the cooling roll, it is possible to continuously produce high-quality slabs without cracks or rough skin caused by triple points. You can enjoy excellent effects.

[Brief explanation of the drawing]

Fig. 1 is an overall explanatory diagram showing an overview of the device of the present invention, Fig. 2 is an explanatory diagram of the operating method, Fig. 3 is an explanatory diagram of another embodiment of the present invention, and Fig. 4 is an explanatory diagram of the conventional device. It is. 1.2 is a cooling roll, 4 is hot water, 5 is a nozzle, 6 is a tundish, and 10 is a cooling water spray. Patent application: Hitoshi Kawajima R Heavy Industries Co., Ltd. Patent application: Hitoshi Nippon Steel Tube Co., Ltd.

Claims (1)

[Claims] 1) Molten metal is poured onto the circumferential surface of each cooling roll disposed in parallel, cooled and solidified, and then merged at the roll gap and cooled to produce a slab. A continuous casting method characterized by continuously manufacturing. 2) Different types of molten metal is poured onto the circumferential surface of each of the parallel cooling rolls, cooled and solidified, and then merged at the roll gap and cooled to form a continuous multi-layered clad slab of different types. A continuous casting method characterized by manufacturing. 3) Parallel cooling rolls that cool the molten metal poured onto the circumferential surface of each roll and then cool together in a roll gap to form a slab, and the molten metal poured onto the circumferential surface of each of the cooling rolls. A continuous casting device characterized by being equipped with a tundish for pouring molten metal. 4) The continuous casting apparatus according to claim 3, further comprising a tundish for pouring different types of molten metal onto the circumferential surface of each cooling roll.