JPH07102428B2 - Casting start method for continuous casting machine for sheet metal - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for starting casting of a metal thin plate continuous casting machine having opposing moving walls, and particularly for casting a metal thin plate having a thickness of 10 mm or less. The present invention relates to a method for starting casting of the metal thin plate continuous casting machine.

[Conventional technology]

Conventionally, a thin plate is generally produced by heating a slab obtained by casting,
Although it has been manufactured through various processes such as hot rolling, in recent years, since various processes such as hot rolling can be omitted, thin plates are being manufactured by a metal thin plate continuous casting machine.
Further, as this type of thin metal sheet continuous casting machine, twin roll type, belt type, caterpillar type, etc. are known, some of which are practical, and some of which are being developed for practical use. .

The method of starting casting of thin plates by this continuous casting machine for thin metal plates is
After setting the gap between the moving walls facing each other corresponding to the target thickness of the slab, the molten metal from the tundish is poured into the wide pool of molten metal formed in the front part of the facing moving walls in a wide and uniform manner. Simultaneously with the pouring, the opposing moving walls are moved at a speed slower than a predetermined casting speed until the poured molten metal forms the slab start end surface.

[Problems to be Solved by the Invention]

In the above-described casting start method, the molten metal poured into the molten metal pool is cooled and solidified on both surfaces of the moving walls facing each other to form the slab starting end face. It takes time to completely cool and solidify to the center of the start end face, and during that time, a so-called initial breakout occurs in which molten metal flows out from the center of the slab or its surroundings, making it difficult to start stable casting. There is. In particular, in the case of the medium twin roll type of the above-mentioned continuous casting machine for thin metal sheets, the length of the slab cooling part following the molten metal pool formed on the front surface of the twin rolls is extremely small, so sufficient cooling can be performed. It is difficult to start a stable casting.

[Means for Solving the Problems]

The present invention has been made in view of the above-mentioned problems, and the gist thereof is to continuously pour molten metal into a molten metal pool formed by opposed moving walls and to cool and solidify the molten wall surface. A casting start method of a metal thin plate continuous casting machine for casting a thin plate cast piece while delivering the solidified layer to the lower side of the moving wall through a cooling unit formed between moving walls facing each other by moving the moving wall, Prior to casting, a dummy sheet having one or a plurality of through holes is attached to a molten metal pool and a cooling unit formed between the opposing moving walls, and the dummy sheet is wrapped in molten metal at the start of casting,
This is a casting start method for a continuous casting machine for thin metal sheets, which is pulled out by moving opposite moving walls.

[Action]

Prior to casting, a through hole is formed in the dummy sheet that is installed in the cooling pool formed between the molten metal pool and the opposing moving wall.Therefore, at the start of casting, the molten metal poured into the molten metal pool is It spreads through the holes to both surfaces of the moving wall facing each other, and in the cooling part following the pool of molten metal, it is effectively cooled so as to envelop the dummy sheet with the molten metal filled in the through holes, forming a strong slab start end. As a result, stable casting can be started without causing initial breakout.

In addition, especially since the length of the slab cooling part following the molten metal pool is very small, even in the case of a twin roll type metal thin plate continuous casting machine having a problem, sufficient cooling is obtained and a strong slab start end is formed. In addition, by utilizing this strong slab start end, it is possible to easily guide the thin slab to a coiler in a subsequent step for winding the slab into a coil.

The material of the dummy sheet used in this way is preferably one having a melting point similar to or higher than that of the molten metal to be cast, and the thickness of the dummy sheet is determined by casting the molten metal on both surfaces of the dummy sheet. The thickness of the cast slab is preferably 0.5 mm or less.

〔Example〕

Embodiments according to the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic explanatory view of a twin roll type metal thin plate continuous casting machine according to the present invention, and FIG. 2 is an enlarged explanatory view of a main part of FIG.

In the figure, reference numeral 1 is a ladle, and a dipping nozzle 2 is installed in the lower portion thereof. A tundish 3 is equipped with a warmer 5 above the overflow port 4. Reference numeral 6 is a water-cooled twin roll, and between the rolls 6a and 6b, a molten metal pool 7 and a cooling unit 8 having a gap adjusted to the thickness of a cast thin plate cast are formed. Reference numeral 9 denotes a dummy sheet, which has a plurality of through holes 10 formed at predetermined intervals in a portion of the water-cooled twin roll 6 which is located above the cooling portion 8. 11
Is a fixture for fixing the rear end portion 12 of the dummy sheet 9 via a belt 13 which is easy to cut. Reference numeral 14 denotes a rear equipment, which is provided with a guide roll 15, a pinch roll 16 and a winder 17.

Next, a thin plate casting method using the twin roll type metal thin plate continuous casting equipment configured as described above will be described.

First, prior to casting, the tip of the dummy sheet 9 is hooked on the winder 17 through the cooling section 8 of the water-cooled twin roll 6 and the pinch roll 16, while the rear end of the dummy sheet 9 is attached to the easy-to-cut belt 13. It is fixed to the fixture 11 via the. (See FIG. 2) Next, the tundish 3 which had been preheated at a predetermined place.
Is moved to fix the overflow port 4 to a position above the molten metal pool 7 of the water-cooled twin roll 6. After that, the ladle 1 containing the molten metal M is moved onto the tundish 3, and the molten metal M is
Pour water into the tundish 3 through the immersion nozzle 2 and further from the overflow port 4 of the tundish 3 into the molten metal pool 7. At the same time, start the water-cooled twin rolls 6 and the rear equipment 14, and set the dummy sheet 9 in place. Wind it up on the winder 17 while pulling it out with the pinch roll 16. By this winding, the dummy sheet 9 is stretched around the upper surface of the lower roll 6a of the water-cooled twin roll 6 so that the dummy sheet 9 is tensioned, and then the belt 13 which is easily cut by receiving tension is cut.

At this time, the through hole 10 of the dummy sheet 9 immersed in the molten metal M of the molten metal pool 7 is filled with the molten metal M, and the molten metal M is filled in the dummy sheet 9 at a portion near the cooling unit 8 of the water-cooled twin roll 6. Is solidified as if the dummy sheet 9 was wound up by the winder 17 and pulled out, and the solidified portion is further cooled by the cooling section 8 to more firmly cast the dummy sheet 9 and water-cool it. It is pulled out to the rear of the twin roll 6. Thus, when the rear end of the dummy sheet 9 exits the molten metal pool 7, the rear end of the dummy sheet 9 serves as a chiller and serves as a nucleus for forming a solidified shell at the center of the starting end of the cast piece, and the molten metal Is cooled from the surface of the water-cooled twin roll 6 between the molten metal pool 7 and the cooling part 8 to form a sufficiently strong solidified layer on the surface, so that stable casting start without initial breakout occurs. it can.

Actually, using the twin roll type metal sheet continuous casting equipment of the configuration shown in Fig. 1, the water-cooled twin roll diameter: 400 mm, width: 300 mm, twin roll gap: about 3 mm, the line connecting the twin roll axes and the horizontal Angle: 35 degrees, casting speed 40m / min. As dummy sheet, 50mm through holes of 20mm diameter are provided at equal intervals above the part corresponding to the cooling part of the water-cooled twin rolls, and the thickness is 1mm.
When a steel sheet with a width of 290 mm and a steel sheet with a thickness of 1 mm and a width of 5 mm was used as a fixing belt for the dummy sheet, stainless steel (SUS-304) with a thickness of 3 mm and copper alloy were cast, respectively. Stable casting could be started without any initial breakout. Further, after the casting, the joining state with the dummy sheet was checked to be sure, and neither cracking and / or peeling of the joining portion which was initially concerned was confirmed.

〔The invention's effect〕

As described above, according to the casting start method for the metal thin plate continuous casting machine according to the present invention, even if the length of the slab cooling portion is very small like the twin roll type, the initial break Stable casting can be started without generating out.

Further, the dummy sheet functions as a winding start end when connected to the winding machine, and can be automatically wound.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of a twin roll type metal thin plate continuous casting machine according to the present invention, and FIG. 2 is an enlarged explanatory view of a main part of FIG. 1 ... Ladle, 2 ... Immersion nozzle 3 ... Tundish, 4 ... Overflow port 5 ... Incubator, 6 ... Water-cooled twin rolls 6a, 6b ... Roll, 7 ... Molten pool 8 ... Cooling part, 9 ... Dummy sheet 10 ... Through hole 10,11 ... Fixing tool 12 ... Dummy sheet rear end 13 ... Easy to cut belt, 14 ... Rear equipment 15 ... Guide roll, 16 ... … Pinch roll 17 …… Winder M …… Molten metal

Claims (1)

[Claims] 1. A molten metal is continuously poured into a molten metal pool formed by opposing moving walls and is cooled and solidified on the surface of the moving wall, and the solidified layer is moved between the opposing moving walls by the movement of the moving walls. A method for initiating casting of a thin metal sheet continuous casting machine that casts a thin sheet slab while delivering the thin sheet slab through a cooling unit to be formed, wherein a dummy sheet having one or more through holes is melted prior to casting. The thin metal sheet continuous casting machine is characterized in that it is attached to a cooling section formed between a pool and an opposing moving wall, and this dummy sheet is wrapped in molten metal at the start of casting, and is drawn out by moving the opposing moving wall. How to start casting.