JPH044952A - Method for conveying cast strip in twin roll type strip continuous casting - Google Patents

Abstract

PURPOSE:To take out a brittle cast strip just after going out from the min. gap part between twin rolls without developing cutting and cracking flaw by taking out the high temp. cast strip going out from the twin rolls while sliding on a slide guide. CONSTITUTION:The cast strip 6 going out from the twin rolls 1-1, 1-2 reaches the slide guide 9 at the P point. Therefore, the cast strip going out from the min. gap part 4 is applied with dead wt. corresponding to the length L between the min. gap part 4 and the P point, but as the cast strip 6 after reaching the P point is supported with the slide guide 9, its dead wt. is remarkably reduced. By this method, to the high temp. and brittle cast strip 6 just after going out from the min. gap part 4, the large dead wt. is not loaded, and therefore, the cast strip 6 is not cut. Further, as the high temp. and brittle cast strip 6 is slid on the slide guide 9 without being strongly held or forcedly drawn with pinch rolls, the cutting and cracking flaw, etc., in the cast strip 6 are not developed.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention prevents casting accidents in twin-roll continuous thin plate casting, and also prevents cutting and cracking of slabs. This invention relates to a method for taking out and conveying slabs from a roll.

[Prior Art] Twin-roll continuous thin plate casting produces thin metal slabs with a thickness of 1 to 3 cm. Therefore, thin metal sheets that are difficult to roll can be manufactured, and furthermore, when manufacturing even thinner metal sheets, the subsequent rolling process can be greatly simplified.

FIG. 1 is an explanatory diagram of the production of slabs using a twin-roll type continuous thin plate casting machine. Molten metal is poured into a pool 2 formed by twin rolls 1-1, 1-2 rotating in the direction of arrow 8 in FIG. 1(A). The molten metal is cooled by twin rolls and solidified shell 3
-1 and 3-2 are formed. These solidified shells 3-1 and 3
-2 is combined and taken out from the minimum gap 4 of the twin rolls.

The solidified shells 3-1 and 3-2 form the minimum gap 4 of the twin rolls.
It is desirable to combine. Figure 1 (B) shows the solidified shell 3
This is an example in which '-1 and 3'-2 are not combined at the minimum gap 4 of the twin rolls, but are combined at the front face 7 of the twin rolls. At this time, a slab having a thickness of t2 mm has already been formed at the joining position 7.

Therefore, in FIG. 1(B), a slab having a thickness of t2II11 is rolled down to a thickness of tmm by twin rolls 1-1 and 1-2, but this rolling is not easy.

As described above, in the minimum gap portion 4, the solidified shells 3-1 and 3-
Therefore, the slab 6 immediately after being taken out from the minimum gap 4 of the twin rolls is scattered with micro-segregation parts in a liquid state and is brittle at high temperatures, and cannot withstand the weight of the slab 6. It is easy to cut or crack without being able to handle it properly.

In Japanese Unexamined Patent Publication No. 1-130847, a free loop is formed in the slab that has exited the minimum gap between twin rolls. However, according to the knowledge of the present inventors, 1 For example, Ni: 50%, Cu: 50%
In the case of electrical material alloys, the hot slab immediately after leaving the minimum gap between the twin rolls is fragile, so if a free loop is formed, it cannot withstand its own weight and breaks.

JP-A-61-162248, JP-A-61-18984
No. 6, JP-A No. 61-219448 describes a diagram in which a slab that has passed through the minimum gap between twin rolls is held between a large number of pairs of pinch rolls. However, according to the knowledge of the present inventors,
It is difficult to rotate a large number of pairs of pinch rolls at synchronized circumferential speeds, and a discrepancy in the circumferential speeds of the pairs of pinch rolls or excessive clamping force can easily cause cuts or cracks in fragile slabs.

[Problems to be Solved by the Invention] An object of the present invention is to provide a method for taking out a fragile slab immediately after leaving the minimum gap between the twin rolls without causing any cutting or cracking.

[Means and effects for solving the problem] FIG. 2 is an explanatory diagram of an example of the slab conveying method of the present invention. In the present invention, a sliding guide 9 for supporting the slab is disposed below the twin rolls 1-1.1-2 and close to the twin rolls.
-2, the hot slab 6 is taken out by sliding on the sliding guide 9.

Although FIG. 2 shows an example of a concavely curved sliding guide, the sliding guide 9 may have an inclined plate shape.

In the present invention, the slab 6 leaving the minimum gap 4 of the twin rolls 1-1.1-2 reaches the sliding guide 9 at point P in FIG.

Therefore, the slab 6 that has left the minimum gap 4 has its own weight corresponding to the length L between 4 and P, but after reaching the point P, the slab 6 is prevented from sliding by the guide 9. Because it is supported, its own weight is significantly reduced. Therefore, the slab 6, which is fragile due to high temperature immediately after leaving the minimum gap 4, is not loaded with a large weight, and therefore the slab 6 is not cut. In the present invention, the slab 6 is brittle at high temperatures.

Since the slab 6 slides on the sliding guide 9 without being strongly pinched or forcibly pulled by pinch rolls, the slab 6 does not suffer from cuts or cracks. In claim (1) of the present invention, the conveyance of the slab 6 after exiting the sliding guide 9 is not particularly limited, but depending on the properties of the slab, it may be
It can be transported by a transport belt shown at 10 in the figure.

[Example 1] The present inventors used sliding guides shown at 9 in FIG.
A Cu alloy containing 50% by weight of Co, a Cu alloy containing 50% by weight of Fe, and a Cu alloy containing 30% by weight of Co were cast. A summary is shown in Table 1.

In this example, casting was carried out by changing the distance between the minimum gap 4 of the twin rolls shown in FIG. 2 and the point P where the slab reaches the sliding guide. FIG. 3 shows the occurrence of fractures and cracks in the slab 6 at that time. As shown in Figure 3, one radius of curvature R is 500+
If the sliding guide is less than wm, breakage or cracks are likely to occur in the slab. Furthermore, if the distance is less than 200 mm or more than 2000 mm, the slab is likely to break or crack. According to claim (2) of the present invention, therefore, R is 500 mm or more and L is 200 mm or more.
-2000mm.

[Example 2] The inventors of the present invention also caused the transfer belt 10 shown in FIG. I took it out on belt 10. In this case, the radius of curvature of the sliding guide 9 was 5001 or more, and L was 500 m++~2000 mm. Other operating conditions are the same as in Table 1.

During this casting, the inventors measured the temperature of the slab at point Q in Figure 2, where the slab was taken out from the transfer belt.
Figure 4 shows the temperature of the slab at each point and the occurrence of fractures and cracks in the slab 6. Support role I at point Q
I grips the slab 6 and rotates. As shown in FIG. 4, when the temperature of the slab at point Q is below 1083°C, even if the slab 6 is sandwiched between the support rolls 11, the slab will not break and no cracks will occur. If the temperature exceeds 1083°C, breakage or cracking will occur. The reason that fractures and cracks occur in slabs at temperatures exceeding 1083°C is generally due to the solidification of alloys.

Micro-segregation phenomenon of solute components occurs during solidification, but in the Nj-Cu alloy, Fe-Cu alloy, and C0Cu alloy used here, micro-segregation phenomenon of Cu occurs during solidification, so the equilibrium of these alloys is Even when the temperature is below the solidus temperature in the phase diagram, micro-segregation parts of liquid Cu remain scattered within the slab, and if excessive stress is applied to the slab from the outside in this state, the slab easily breaks down. This is because it may break or cracks may occur.

Here, at 1083°C, the micro-segregation part of Cu solidifies,
This is the temperature at which the slab completely solidifies. In the present invention, the solidification completion temperature of a slab refers to the temperature at which liquid micro-segregation parts scattered within the slab solidify and the slab completely solidifies. According to claim (3) of the present invention, the temperature of the slab when taken out from the transfer belt is set to be below the solidification completion temperature of the slab. Even if the slab whose temperature is below the solidification completion temperature of the slab is conveyed by the usual method using the support rolls 11 or the conveyance rolls 12, no breakage or cracks will occur in the slab.

[Effects of the Invention] When the present invention is carried out, even if the slab immediately after leaving the minimum gap between the twin rolls is brittle due to high temperature, no breakage or cracking will occur in the slab.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of twin-roll continuous thin plate casting, Fig. 2 is an explanatory diagram of an example of the slab conveying method of the present invention, and Fig. 3 is an illustration of the shape and setting position of the sliding guide and fracture of the slab. FIG. 4 is a diagram showing the relationship between the temperature of the slab when it is taken out from the transfer belt and the occurrence of breakage and cracking of the slab. 1 (1-1, 1-2): Twin roll, 2: Hot water pool, 3
(3-1, 3-2, 3'-1, 3'-2): Solidified shell, 4: Minimum gap between twin rolls, 5: Injected molten metal flow,
6: Slab, 7: Solidification completion position, 8: Rotation direction of twin rolls, 9: Sliding guide, 10: Transfer belt, 11
: Support roll, 12: Conveyance roll. Figure 1 Patent applicant Nippon Steel Corporation

Claims (3)

[Claims] (1) In twin-roll continuous thin plate casting, a curved or inclined sliding guide is placed below the twin rolls in close proximity to the twin rolls to support the slab, and the hot slab coming out of the twin rolls is guided by the sliding guide. A method for conveying slabs in twin-roll continuous thin plate casting, characterized by removing the slab by sliding the top. (2) A concave sliding guide with a radius of curvature of 500 mm or more on the upper surface, and the slab from the twin rolls is 200 mm to 2000 m.
2. The method for conveying a slab in twin-roll continuous thin plate casting according to claim 1, wherein the slab is disposed at a position where the sliding guide is reached between m.m. (3) In twin-roll continuous thin plate casting, a curved or inclined sliding guide is placed below the twin rolls to support the slab in close proximity to the twin rolls, and the hot slab coming out of the twin rolls is guided by the sliding guide. The cast slab is then moved from the sliding guide onto a transfer belt running at a speed equal to the sliding speed of the slab, and is taken out from the transfer belt at a temperature below the solidification completion temperature of the slab. A slab conveying method in twin-roll continuous thin plate casting.