JPH02217139A - Roll for twin roll type continuous casting machine - Google Patents

Abstract

PURPOSE:To secure air gap having stable thickness by pouring molten metal into pouring basin between two rolls mutually rotating in reverse direction and forming shape of the roll for producing a cast strip to the regular (n) polygon and specifying the range of diameter in circumscribing circle. CONSTITUTION:The shape of the roll has the regular (n) polygon, and at the time of using Dmm for the diameter in the circumscribing circle, (n) is made to be in the range of 0.005 - 0.100mm for D/4(pi/n)<2>. The considerable temp. difference between meniscus part 6 and the narrowest point 7 of the roll gap is generated in the solidified shell 2, and heat shrinkage develops between the positions 6 and 7. By this heat shrinkage, d1 and c1 points are shifted to d2 and c2 points, respectively and the air gaps 8, 9 are formed between the solidified shell 2 and the polygonal roll 1. By this air gap 8, the solidified shell is forcedly, periodically and slowly cooled. As the roll has polygonal shape, the solidified shell is heat-shrunk and slid on the corner (b) of the polygon and the air gap is forcedly and periodically formed. By this method, there is no fear of blinding, wear, etc., on the surface of the roll and the air gap always having stable thickness can be secured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a roll of a twin-roll continuous casting machine used for manufacturing thin-walled metal slabs.

[Prior Art] Fig. 2 is a schematic diagram of a conventional twin-roll continuous casting machine known as the Bessemer method, and (A) is a side view;
(B) is a plan view. 10-1.1O-2 are two rolls arranged in parallel and rotating in the direction of the arrow. Side weirs 11-1, 11-2 are arranged at both ends of the roll. Molten metal 3 is injected into a sump formed by two rolls and a side weir. The injected molten metal is cooled by rolls 10-1 and 10-2 between the meniscus 6 and the narrowest point 7 of the roll gap to form solidified shells 2 and 2'. For example, the solidified shells are combined at the narrowest point 7 of the roll gap to form the thin slab 5.
is extracted as.

This twin-roll continuous casting machine has simple equipment and is suitable for manufacturing thin slabs with thin plates. Roll-type continuous casting machines are attracting attention as casting equipment suitable for, for example, the manufacturing process of thin steel sheets.

In this method, for example, the solidified shell 2 is cooled by the rolls 10-1 between the meniscus 6 and the narrowest point 7 of the roll gap, but the solidified shell 2 is thermally shrunk in this period and deformed by cooling stress. , a part in contact with the roll and a part not in contact with the roll are formed accidentally.

When the solidified shell 2 has a contact area with the roll and a non-contact area, the solidified shell in the contact area with the roll is strongly cooled.
Since the solidified shell in the non-contact area with the roll is slowly cooled,
The solidification rate of the solidified shell tends to be non-uniform, and therefore the thickness of the thin slab 5 also tends to become non-uniform.

Japanese Patent Application Publication No. 184449/1984 and Patent Application No. 2404/1983
No. 79 relates to a twin-roll continuous casting machine that produces thin slabs 5 of uniform plate thickness. That is, JP-A-60-18444
No. 9 is a drum-type continuous casting machine in which the surface of the roll is formed into a surface texture with almost uniformly distributed irregularities, and Japanese Patent Application No. 1982-240479 has a roll with a diameter of 0.1 to 1.2 m.
m circular or oval opening with a depth of 5 to 100μ
The present invention relates to a cooling roll in which dimples of m are uniformly formed on the surface of the roll. According to these methods, the solidified shell comes into contact with the roll through an air gap corresponding to the shape of the unevenness or depression.

That is, in these prior art techniques, the thickness of the thin slab is made uniform by forming an air gap, and the air gap is formed by unevenness or depressions provided on the roll. Therefore, in order to make the thickness of the thin slab 5 uniform, the shapes of the unevenness and depressions are important.

However, the unevenness and depressions formed on the roll are likely to become clogged when they come into contact with the molten metal or solidified shell, and the shape of the unevenness and depressions is also likely to change due to wear, so it is difficult to maintain the same shape. It's not easy.

[Problems to be solved by the invention] Japanese Patent Application Laid-Open No. 184449/1982 and Patent Application No. 24047/1982
According to No. 9, etc., the solidified shell comes into contact with the roll through an air gap, so a thin slab with a uniform thickness can be obtained, but if the irregularities or depressions become clogged or deformed during casting,
The thickness of the air gap becomes uncertain, and the thickness of the thin slab also becomes uneven. The present invention provides a roll for a twin-roll continuous casting machine that is easy to maintain and can form an air gap of stable thickness between the solidified shell and the roll.

[Means and effects for solving the problems] The present invention provides a twin-roll continuous casting machine characterized in that the roll shape of the twin-roll continuous casting machine is a regular n-gon, and the diameter of the circumscribed circle is D (mm). This is a roll for continuous flange making.

The present invention will be specifically explained below. FIG. 1 is a schematic explanatory diagram of the present invention. 1 is the roll of the polygonal prism of the present invention, and arrow 4
rotate in the direction. 2 is a solidified shell formed on the roll, and between the meniscus 6 and the narrowest point 7 of the roll gap,
The cast slab 5 is cooled by the roll 1 and gradually increases in thickness, and is combined with the solidified shell 2' formed on the facing roll 1' to form the thin slab 5. FIG. 1(A) is a virtual diagram when the solidified shell 2 does not shrink due to heat. However, solidified shell 2
is, for example, about 1500° C. at the meniscus 6, but is about 1200° C. at the narrowest point 7 of the roll gap, so thermal contraction occurs between 6 and 7. This thermal shrinkage is 3 to 10 mm per meter of length of the solidified shell.

FIG. 1 CB) is an explanatory diagram taking into consideration the thermal contraction of the solidified shell 2.

Since the solidified shell 2 undergoes thermal contraction, point d□ in FIG. 1(A) moves to point 62 in FIG. 1(B). Similarly, Figure 1 (A
) moves to point 02 in FIG. 1(B) due to thermal contraction of the solidified shell 2. At this time, the ridge of the polygonal roll pushes the solidified shell between C2 and d2 toward the molten metal, creating an air gap between the solidified shell 2 and the polygonal roll 1, as shown in FIG. 1(B). 8 and 9 are formed. Thus, for example, the air gap 8 is forcibly and periodically formed by ridges, and the solidified shell is forcedly and periodically slowly cooled by this air gap 8.

As mentioned above, if the roll is cylindrical and has a smooth surface,
Since the solidified shell is accidentally formed with a contact part and a non-contact part with the roll, the solidified shell is strongly cooled in the contact part with the roll and slowly cooled in the non-contact part, and the plate thickness of the thin slab 5 is reduced. There are large fluctuations. Even when the roll is cylindrical and has irregularities or depressions on its surface, if the irregularities or depressions become clogged, for example, the surface of the roll approaches smoothness, and strong cooling parts and slow cooling parts are formed in the solidified shell.

In the present invention, since the roll is a polygonal prism, the solidified shell is thermally shrunk and slides, for example, on the ridge shown in FIG. 1(B), forcibly forming air gaps periodically.

If fine irregularities or depressions are formed on the surface of the roll, there is a concern that the irregularities or depressions may become clogged or worn during casting, but in the present invention, an air gap is formed by the heat shrinkage of the solidified shell and the ridges. Therefore, the air gap is stably formed during casting.

In the present invention, when the roll has a regular n-gon shape and the diameter of the circumscribed circle is D (mm), -T (mm)
The reason why is set in the range of 0.005 mm to 0.100 mm will be explained next. In the present invention, an X-gon or a Y-gon means
A general term for regular X-gons, regular X-gons, and shapes that have rounded areas on the regular X-gons and regular X-gons.

In Figure 1 (A), O is the axis of the polygonal prism, D/2 is the radius of the circumscribed circle of the cross section (mm), and L is the radius of the inscribed circle of the cross section (mm).
It is. During thermal contraction of the solidified shell, as shown in FIG. 1(B), the solidified shell between 02 and 62 is pushed toward the molten metal 3 side by a maximum of (D/2-L) by the ridge.

Therefore, in FIG. 1(B), the maximum thickness of the air gap layer 8 is (D/2-L). For example, in FIG. 1(A), when the roll is a regular n-prismatic prism, (D/2-L) is expressed as the following equation (1).

(D/2-L)” (D/2-D/2Xcos(il
o))=D/2(1-cos(π/n)) --(1)
The unit of angle here is radian.

Usually, since π/n<<1, equation (2) approximately holds true.

D/2-L=dan(1)'・・・・・・・・・(2
) n On the other hand, according to the knowledge of the present inventors, it is preferable that the maximum thickness of this air gap layer 8 is o, oos to 0.100 m+n. If it exceeds 0.100 mm, for example, unreasonable stress is applied to the solidified shell between C2 and d2, resulting in increased cracking, and periodic thickness fluctuations of the slab cannot be ignored. Also 0,005m
If it is less than m, the effect of the present invention is small. Therefore, the equation (2) becomes the following equation (3).

D? c2 0.005~0.100mm=4 (,) ・= ・・
- (3) In a twin-roll continuous sowing machine that produces thin slabs with high efficiency, the diameter of the rolls is preferably 160 mm or more.

Therefore, from equation (3), a roll with a diameter of 160 mm has a polygonal prism with a regular X/gonal cross section where n=X and (63<X, <281). Also, the diameter of the roll is 2000m.
m or more, the equipment becomes too large. Therefore, from equation (2), for a roll with a diameter of 2000 mm, n = X2 (
It becomes a polygonal prism with a regular X2 square cross section where 222<

In FIG. 1(B), the solidified shell 2 slides on the ridges a and ridges of the roll during contraction. Therefore, it is desirable that the ridges a and ridges have a shape that allows the solidified shell 2 to slide smoothly. In other words, rather than having a precisely finished shape,
A rounded, slippery shape is preferred.

When the polygonal column has a precisely finished shape, the roll of the present invention has a regular X-gon shape (63<X<993
), but when the customer area is a rounded and slippery shaped edge, the roll is approximately a regular X/2 square, that is, a regular X-gon (32< 49
A polygonal prism with a cross section of 2) is preferable.

Further, the polygonal customer area may be distributed in a spiral shape on the roll surface.

[Example] Casting of common steel, electromagnetic steel, stainless steel, and iron-steel alloy was performed using specific roll sizes and shapes, and slabs with a thickness of about 2.2 mm were manufactured. Table 1 shows the conditions of the rolls used and the surface properties of the slabs obtained.

As shown in Table 1, when the cross-sectional shape D π of the roll of the present invention is made into a polygon,
If it is within the range of 0 mm (cases (1), (5)
, (8) ), the cracks in the slab were extremely slight.

On the other hand, in the case of circular rolls (cases (2), (6), and (9)) as comparative examples shown in the figure, cracks occurred frequently in each casting material.

D π The cross-sectional shape of the roll is polygonal, and j is 0.005.
When the thickness was less than mm (case (4)), cracking of the slab was not significantly reduced. Also, the roll cross-sectional shape D π
2. When the shape is polygonal, "If the value of (D) exceeds 0.100 mm (cases (3), (7), (10)), the cracking of the slab will not be reduced or will even increase. .

[Effects of the Invention] By carrying out the present invention, it is possible to prevent the accidental formation of contact areas and non-contact areas with the rolls in the solidified shell in a twin-roll continuous casting machine.

In the present invention, since no irregularities or depressions are provided on the surface of the roll, there is no concern about clogging or wear, and an air gap of a stable thickness is always ensured during casting.

In the present invention, maintenance of the roll surface is easy.

In the present invention, since an air gap of stable thickness is always ensured, the thin slab has good surface quality and uniform plate thickness. Therefore, the thin slab manufactured by the present invention has fewer cracks and defects in the subsequent rolling process.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic illustration of the operation of the present invention, and FIG. 2 is a schematic illustration of a conventional twin-roll continuous casting machine. 1 (1'): Polygonal roll, 2 (2'): Solidified shell, 3: Molten metal, 4: Roll rotation direction, 5: Thin slab,
6: Meniscus, 7: Roll gap narrowest point, 8.9:
Air gap, 10 (10-1, 1O-2): Roll, 11 (11-1, 1l-2): Side weir. Patent applicant Nippon Steel Corporation

Claims (1)

[Claims] In the rolls of a twin-roll continuous casting machine that produces thin slabs by injecting molten metal into a sump formed by two rolls rotating in opposite directions, the rolls have a regular n-gon shape, When the diameter of the circumscribed circle is D (mm), D/
A roll for a twin-roll continuous casting machine, characterized in that 4(π/n)^2 is in the range of 0.005 mm to 0.100 mm.