JPH06198303A - Split roll in continuous casting machine for thin slab - Google Patents

Abstract

PURPOSE:To prevent the inner crack of a cast slab that is locally generated in a roll chock part and to obtain the good cast slab without temp. irregularity by arranging small-sized divided rolls by changing their roll chock parts successively and alternately to the traveling direction of the slab. CONSTITUTION:This roll is a split roll of a continuous casting machine for thin slab which is composed of small-diameter divided rolls 1a-1d having the roll pitch P of 100-200mm. The width A of the divided roll chocks 2a-2d is taken as <=0.6 of the roll pitch P and the distance B between the roll chocks (intermediate bearings) in the width direction of roll as 1 2 times the width A of the divided roll chock. And the roll is the split roll in the continuous casting machine for thin slab in which the same arrangement of the divided roll chock in the casting direction is arranged at the distance of three or more roll pitches. In this way, at the time of casting the thin slab at high speed of 4-10m/min, the inner crack of the cast slab that is locally generated in the roll chock part is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a split roll for performing a thin slab continuously cast at a high speed of 4 to 10 m / min, such as a twin belt caster, before the inside of the thin slab slab is completely solidified. .

[0002]

2. Description of the Related Art Conventionally, when guiding, bending, straightening or forming a high-speed cast slab in an unsolidified state, its intermediate bearing portions are arranged alternately in the moving direction of the slab. A split roll consisting of a split tubular roll is used.

As one of the problems in rolling the thin slab continuously cast by the split rolls, when rolling the slab in a high temperature state with the thin shell by the split roll, the inside of the slab due to abnormal bulging deformation of the unsolidified portion is performed. Cracks are generated, and this bulging crack is greatly affected by the depression of the intermediate bearing portion.

As a measure for reducing the influence of the depression due to the interposition of the intermediate bearing, Japanese Utility Model Publication No. 52-5134 discloses that the intermediate bearing portion of the split roll is sequentially replaced in the moving direction of the slab. It is described that the same applies to the hierarchical relationship.

Japanese Patent Publication No. 54-23650 discloses mounting a journal in a narrow range on an intermediate bearing.

[0006] The applicant of the present invention has filed Japanese Patent Application No. 2-4091.
In the specification of No. 71 application, in the rolling of a high-speed continuous casting slab with a casting speed of 4 to 10 m / min, in order to prevent the occurrence of bulging cracks and breakout of the slab, such a roll has a small diameter to ensure the rigidity of the roll. Therefore, from the viewpoint that it is necessary to have a divided roll structure and to reduce the roll pitch, the roller is elastically supported on the upper frame of the segment via a disc spring, and the position of the hydraulic cylinder is controllable on the upper frame. Has been disclosed.

[0007]

However, in order to effectively prevent the occurrence of bulging cracks in the rolling of a high-speed continuous casting thin slab by such a split roll, the inventor of the present application uses a roll having a small diameter. Moreover, in addition to reducing the roll pitch, I wondered if there was any quantitative relationship between the bulging cracks and the arrangement of small-diameter divided rolls.

The object of the present invention is to prevent internal cracking due to local bulging of the roll chock during rolling with a split roll in high speed continuous casting with a casting speed of 4 m / min or more and a slab cast piece having a thickness of 40 to 80 mm. As a means for achieving this, it is necessary to find a countermeasure based on the arrangement of small-diameter divided rolls and a quantitative relationship between internal cracks due to local bulging in the roll chock portion.

[0009]

SUMMARY OF THE INVENTION The present invention is a split roll for high speed continuous casting slab rolling, in which split rolls of small diameter are arranged with their roll chocks being sequentially and alternately replaced with respect to the moving direction of the slab. The chock width is 0.6 or less of the pitch between the rolls, the distance between the chocks of the arranged divided rolls is at least twice the divided roll chock width, and further, the chock arrangement of each divided roll with respect to the traveling direction of the slab, It is characterized in that the roll pitches are separated by three or more and are arranged in the same arrangement.

[0010]

The local bulging of the roll chock is greatly affected by the roll chock width and the distance between the roll chocks in the roll width direction in the roll arrangement, and the relationship between the chock width of the divided rolls and the pitch between the rolls and the arranged divided rolls The relationship between the distance between chocks and the width of the divided roll chocks, and further, by separating the same arrangement of chocks of divided rolls in the traveling direction of the slab by three or more roll pitches, increase in bulging due to interaction between adjacent intermediate bearing parts is suppressed. , Alleviates uneven cooling of the slab due to the flow path of the spray water, resulting in a decrease in bulging.

[0011]

EXAMPLE A casting speed of 4 to 10 m / min and a thickness of 70
A cast slab having a width of 1 mm and a width of 1300 mm was rolled to a thickness of 50 mm in an unsolidified state using a split roll having a small diameter split roll arrangement shown in FIG.

In the figure, 1a, 1b, 1c and 1d
Indicates a small-diameter split roll having a diameter of about 120 mm. These small-diameter split rolls 1a, 1b, 1c, 1d have pitch P so that roll chock (intermediate bearings) 2a, 2b, 2c, 2d are sequentially arranged alternately in the moving direction S of the slab shown by the arrow. In parallel at intervals of 150 mm,
Furthermore, the distance B between the roll chocks between the small-diameter divided rolls 1a, 1b, 1c, and 1d was set to 200 mm. Furthermore, the split roll chock arrangement in the casting direction,
The first row of small-diameter split rolls 1a separated by three roll pitches
And the small-diameter dividing roll 1d in the fourth row are the same. The arrow w shown in the figure indicates the flow path of the sprayed water, and flows from the chocks 2a, 2b, 2c of the divided rolls 1a, 1b, 1c to the respective divided rolls 1b, 1c, 1d on the downstream side. The road is formed.

In the arrangement of the split rolls shown in FIG. 1, the bulging of the slab is performed by changing the relationship between the roll chock width A / roll pitch P and the roll chock width A / roll interchock distance B in the roll width direction. The degree of occurrence of was investigated.

FIG. 4 shows modes of bulging between rolls (solid line) and local bulging of the roll chock portion (broken line).

The local bulging of the roll chock portion becomes abnormally large depending on how the roll chock width A and the roll chock distance B are taken.

Assuming that the local bulging amount ratio of the roll chock portion is α and the expansion factor of the local bulging is β as an index showing the degree of occurrence of bulging, the bulging amount ratio α and the bulging expansion factor β are independent of each other. Since it is a coefficient that acts on the bulging of the roll, the local bulging δ of the roll chock can be expressed as δ = roll bulging × α × β. Here, the bulging amount ratio α is expressed by α = (local bulging of the roll chock portion) / (roll bulging), and when the bulging amount ratio α is 1, the local bulging portion of the roll chock portion is equivalent to the bulging between rolls. Therefore, the roll chock has an allowable value with no influence.

The expansion factor β of the local bulging in the roll chock portion represents the mutual buffering amount between the adjacent roll chock portions in the width direction of the slab, and β = (local bulging portion of the roll chock portion with adjacent roll chocks) / (adjacent Local expansion of roll chock part without roll chock) The expansion factor β is 1.0 when the roll chock local bulging is equal to the bulging amount when there is no adjacent roll chock, and the mutual bulging between the adjacent roll chock is large. It means that there is no buffer.

FIG. 2 shows the relationship between (local bulging of roll chock portion) / (bulge between rolls) α and (roll chock width A / roll pitch P). In other words, the local bulging of the roll chock portion is usually It is understood that the allowable value of the ratio α of 1 is achieved when the ratio of the roll chock width A / roll pitch P is 0.6 or less in order to prevent the increase from the inter-roll bulging.

FIG. 3 shows the relationship between (distance B between chocks of arranged divided rolls) / (roll chock width A × 2) and the expansion coefficient β of the local bulging in the roll chock portion.

As shown in the figure, the inflection point at which the expansion factor β of the local bulging in the roll chock portion converges to 1.0 is (distance B between the arranged divided rolls).
/ (Roll chock width A × 2) is 1.0,
When the value of B / 2A is 1.0 or more, the expansion coefficient β of local bulging falls within 1.0.

The characteristics shown in FIGS. 2 and 3 are as follows: when the choke arrangements of the divided rolls in the traveling direction of the slab are not the same arrangement with three or more roll pitches apart, the bulging amount ratio α and the expansion coefficient β. The value of becomes larger.

As shown by the one-dot chain line hatched portion in FIG. 1, from the chocks 2a, 2b, 2c to the respective divided rolls 1 in the next row.
The amount of water sprayed on the b, 1c, and 1d surfaces passes over the roll chock portion and becomes accumulated water.
The spray effect is hindered and the slab cooling is hindered. Also,
As shown by the dashed line in FIG. 5, the roll pitch 2
When they are arranged within the same number, the spray cooling inhibition zone is continuously connected in the casting direction, and as a result, the cooling of the slab at the portion corresponding to the roll chock is hindered, the slab temperature rises, and the bulging of the roll chock increases.

From the above embodiment, a roll pitch of 100
In a continuous casting thin slab of 40 to 80 mm in thickness, a split roll thin slab continuous casting machine with a diameter of up to 200 mm and a split roll of a small diameter roll, the inside of the split roll chock part slab bulging during high speed casting of 4 m / min or more. In order to prevent cracking, the split roll chock width A ≦ 0.6 roll pitch P, the roll chock distance B ≧ 2A in the roll width direction, and the split roll chock arrangement in the casting direction is the same arrangement with three or more roll pitches apart. It turns out that it is necessary.

[0024]

The present invention has the following effects.

(1) During high-speed casting of a thin slab at 4 to 10 m / min, internal cracking of the cast piece locally generated at the roll chock portion is completely prevented, and casting which becomes a problem during high-speed casting. Temperature unevenness due to uneven cooling on one surface is also eliminated, and a good cast slab can be obtained in terms of inner and outer qualities.

(2) When high speed continuous casting thin slab is unsolidified and rolled by split rolls, problems such as slab bulging cracks, slab surface dents and breakouts due to local abnormal bulging of roll chock part Avoid the
Smooth unsolidified rolling can be performed.

[Brief description of drawings]

FIG. 1 shows an arrangement of divided small-diameter rolls according to the present invention.

FIG. 2 shows the relationship between the bulging amount ratio and the (roll chock width × roll pitch) ratio.

FIG. 3 is a diagram showing a bulging expansion coefficient in a roll chock portion.

FIG. 4 shows aspects of bulging between rolls (solid line) and local bulging of the roll chock portion (dotted line).

FIG. 5 is a diagram illustrating an example in which the arrangement of divided small-diameter rolls is inappropriate.

[Explanation of symbols]

 1a to 1d split rolls 2a to 2d roll chock

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location B22D 11/128 350 350 A 7362-4E

Claims (1)

[Claims] 1. A split roll of a thin slab continuous casting machine composed of small-diameter split rolls having a roll pitch of 100 to 200 mm, wherein a split roll chock width A is 0.6 or less of the roll pitch, and a roll width direction. In the thin slab continuous casting machine, the inter-roll chock distance B is 2 times or more the divided roll chock width A, and the divided roll chocks in the casting direction are arranged in the same arrangement with a roll pitch of 3 or more.