JP2732996B2 - Roll equipment for continuous casting - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a roll device for continuous casting, and more particularly, to rolling of a slab having an unsolidified portion in the center thereof to generate segregation and porosity at the center of the slab. The present invention relates to a roll device for continuous casting which prevents the occurrence of a roll.

[0002]

2. Description of the Related Art As is well known, in continuous casting,
In order to prevent segregation in the center of the slab, segregation is dispersed by electromagnetic stirring, low-temperature casting, addition of non-uniform nucleation generation promoting substances, etc. The internal quality of cast slabs has been improved through measures such as the introduction of various bulging prevention techniques.

In recent years, however, it has not been possible to sufficiently prevent porosity at the center of the slab and segregation due to molten steel flow accompanying solidification shrinkage at the final stage of solidification by only taking measures against the molten metal and the mold. Rolling a low reduction rate by a group of rolls to the slab at the end of solidification where the solidification part exists,
2. Description of the Related Art Technologies for suppressing segregation by suppressing the flow of molten steel due to a center porosity generated by solidification shrinkage and a suction based on solidification shrinkage have been widely adopted.

[0004] As a rolling reduction method, for example, as disclosed in Japanese Patent Application Laid-Open No. 50-55529 and Japanese Patent Publication No. 54-38978, a flat slab having an unsolidified portion at the center by a flat roll is used. A method of applying a reduction to the entire width and, for example, as disclosed in Japanese Patent Publication No. 2-56982, a roll in which the diameter of the central portion in the width direction is shorter than the width of the slab and larger than both sides. It is known to apply a reduction to the center in the width direction of a slab having an unsolidified portion at the center, but in the former method of applying a reduction to the entire width of the slab by a flat roll, the side surface of the slab is Resistance to the stiffness of the shell developed from the above, it may be difficult to secure an effective reduction amount to the central unsolidified part. The latter method of adding It is more effective in preventing the formation of porosity.

Further, as a roll device for carrying out the latter method, a roll device having a structure shown in FIG. 4 which is a longitudinal sectional view showing a main portion thereof is generally used. In the conventional roll device shown in FIG. 4, the widthwise central portion of the roll body (22a) is formed to have a larger diameter than both sides, and the central portion is a pressing portion (22b). Roll (22)
Multiple rolls are arranged in the same roll stand (21). Further, both end shafts (22c) of the rolls (22) are supported by bearing housings (23), and the roll stands (21) are supported via the bearing housings (23).
The upper fixed frame (21a) and the lowering frame (21b) are connected. On the other hand, the pressing frame (21b) of the roll stand (21) is moved up and down by the operation of the hydraulic cylinder (24) attached to the lower fixed frame (21c) below it.

The total length of the roll body (22a) of each roll (22) is formed to be longer than the width of the slab (B), and the pressing portion (2b) at the center thereof is formed of a slab. (B) is formed to have a width narrower than the width of the slab (B) .In this configuration, a predetermined reduction amount is provided at the center in the width direction of the slab (B) where the unsolidified portion (M) exists at the center. While the slab passes through (B)
And the bearing box (23) that supports the shafts (22c) at both ends to prevent the heat effect of the slab (B) from directly affecting those bearing boxes (23). .

In some cases, an annular space is provided inside the pressing portion (22b) of the roll (22), and the outer diameter of the pressing portion (22b) can be changed to some extent freely by introducing a high-pressure fluid into the annular space. However, the overall configuration is similar to the above.

[0008]

By the way, in a roll device for applying a reduction to a slab having an unsolidified portion in the center,
Usually, 4 to 5 pairs, at most about 8 pairs of rolls are arranged on the roll stand. The smaller the outer diameter of each roll is, the narrower the arrangement pitch of the rolls is, the more the objective is. The effect of preventing segregation and generation of center porosity is more reliable. this is,
If the arrangement pitch of the rolls is large, the time required for the slab to move between them, that is, the time for releasing the reduction against the slab, becomes longer, and during that time, the molten steel in the central part in the solidification process flows and causes central segregation In order to prevent this, it is effective to reduce the roll arrangement pitch.

However, in the above-mentioned conventional roll device, the entire length of each roll body is formed to be longer than the width of the slab, so that the space between the slab that passes and the bearing box that supports the shafts at both ends is provided. The distance is set so that the heat influence of the slab does not directly affect the bearing housings, that is, the distance between the roll bearings is relatively large, and in addition, the pressing portion is the center of the roll body. Therefore, in order to obtain sufficient bending stiffness (hereinafter referred to as bending stiffness) sufficient to oppose the load applied to apply pressure to the slab, it is necessary to secure a bending stiffness by making the roll diameter relatively large. This restricts the diameter of the roll and makes it difficult to reduce the roll arrangement pitch. In addition, in the roll having such a configuration, the roll body is not directly involved in the reduction of the cast slab, but merely secures the bending stiffness, so that the roll has a portion that is excessive in view of the intended purpose. It is irrational in terms of economics.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, in which the length of a roll for applying pressure to the center of a slab in the width direction is set to a minimum necessary length, and the outer diameter of the roll is reduced. The purpose of the present invention is to provide a roll device which can secure the required bending rigidity even if the diameter is reduced, thereby effectively preventing the slab segregation and the generation of center porosity by narrowing the roll arrangement pitch, and also having excellent economic efficiency. Is what you do.

[0011]

In order to achieve the above object, the present invention has the following arrangement. That is, the roll device for continuous casting according to the present invention is a roll device for continuous casting that applies pressure to a slab having an unsolidified portion in the center by upper and lower rolls arranged in a roll stand, One or both of the upper and lower rolls,
It is characterized in that it is formed on a short roll in which both end shafts are directly provided on a roll body portion having a shorter length than the width of the cast slab.

Further, the roll formed as the short roll may be supported by a bearing box having a water-cooled jacket on the outer peripheral side.

[0013]

According to the present invention, the roll for applying pressure to the slab is formed as a short roll having both end shafts directly provided on the roll body having a shorter length than the width of the slab. With this, a reduction can be applied to the center of the slab in the width direction, and the distance between both ends of the slab can be made much smaller than that of the conventional one. The generated bending stress is reduced, and the required bending rigidity can be secured even when the roll outer diameter is made smaller. In addition, by reducing the outer diameter of the roll, the roll arrangement pitch is narrowed by the reduced diameter, and segregation of the slab and generation of center porosity can be effectively prevented.

Further, by supporting the roll formed in the short roll with a bearing box provided with a water-cooled jacket on the outer peripheral side, the temperature of the bearing box is prevented from rising due to radiant heat from the slab. The shaft support function can be stably maintained.

[0015]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a roll apparatus for continuous casting according to the present invention. FIG. 1 is a longitudinal sectional view showing a configuration of a main part of a roll device according to an embodiment of the present invention.

The roll device of the present embodiment shown in FIG.
Place a pair of rolls (2) up and down in the roll stand (1)
(B) are arranged in multiples (five in this example) in the moving direction. Below the position of each pair of rolls (2) of the roll stand (1), there is a pressing frame (up and down) which moves up and down by the operation of a hydraulic cylinder (4) attached to the lower fixed frame (1c). 1b) is provided.

Further, each roll (2) is formed as a short roll in which both end shafts (2b) are directly provided on a roll body portion (2a) having a shorter length than the width of the cast slab (B). Along with its both ends (2b)
Is supported by the bearing housing (3), and through these bearing housings (3),
The upper fixed frame (1a) and the lowering frame (1b) are connected to each other, and are arranged in pairs vertically.

On the other hand, the outer peripheral side of the bearing box (3), which supports the shafts (2b) at both ends of each roll (2), facing the cast slab (B), is formed so as to cover the outer peripheral side in a semicircular shape. And a water cooling jacket (3a) is provided. Further, the water cooling jacket (3a) of these bearing housings (3) is connected to an external cooling water supply device via a pipe not shown here to introduce cooling water into the inside.
It can be discharged.

The roll device according to the present embodiment has the above-mentioned structure, and has a pair of rolls (2) at the center in the width direction of a slab (B) having an unsolidified portion (M) at the center. By applying a predetermined amount of reduction from above and below, the center porosity generated by solidification shrinkage and the flow of molten steel caused by suction based on solidification shrinkage are suppressed to prevent segregation.

Here, in the roll device of the present embodiment, the slab
A roll (2) for applying a reduction to (B) is formed into a short roll in which both end shafts (2b) are directly provided on a roll body (2a) having a shorter length than the width of the slab (B). Therefore, the distance between the shafts (2b) at both ends can be made much smaller than the conventional one illustrated in FIG. 4 so that the bending stress generated even when the same rolling load is applied is generated more than the conventional one. And the required bending rigidity can be ensured even if the roll outer diameter is made smaller.

Also, as shown in FIG.
By making the outer diameter d of (2) smaller than the outer diameter D of the conventional roll (22), the roll arrangement pitch p is made smaller than the conventional roll arrangement pitch P by the reduced diameter (D-d). It is possible to reduce the flow of molten steel in the unsolidified portion (M) at the center by increasing the rolling pitch density to the slab (B), thereby effectively preventing segregation and generation of center porosity. Can be prevented.

On the other hand, a roll (2) for applying a reduction to the slab (B)
When formed into a short roll having the above configuration, the radiant heat from the slab (B) directly reaches the bearing box (3) that supports the both end shafts (2b). 3) On the outer circumference of
Water cooling jacket (3a) connected to an external cooling water supply device
The cooling water is circulated through the water-cooled jacket (3a) to prevent the bearing box (3) from rising due to radiant heat from the slab (B), and to support the bearing. Function can be maintained stably.

Further, in addition to forming each roll into a short roll, the outer diameter of each roll can be reduced, so that the amount of material required for manufacturing each roll is significantly reduced as compared with the conventional one. It can be reduced and its economic efficiency can be improved.

In the above embodiment, both the upper and lower rolls are short rolls of the same shape, and the central portion in the width direction of the slab is reduced in the vertical direction. For example, when the slab of the slab is targeted, since the stiffness of the shell on the slab side is relatively low,
As shown in FIG. 3, even if one of the upper and lower rolls is a flat roll, and the other roll is applied to the center of the slab in the width direction, it is effective for the center unsolidified portion. The amount of reduction can be obtained.

FIG. 3 is a longitudinal sectional view showing a main part of a roll device according to another embodiment of the present invention. The roll device of the present embodiment is the same as that of the above-described embodiment except that a flat roll is used as the upper roll. The description will be omitted with the addition of, and only the differences will be summarized and described.

In the roll device of the present embodiment shown in FIG. 3, both ends of the shaft (5b) are attached to a straight roll body (5a) having a length longer than the width of the slab (B) as the upper roll. A directly provided flat roll (5) is disposed above and opposed to a roll (2) as a lower roll. The flat roll (5) as an upper roll has both end shafts (5b) supported by bearing boxes (6), and is connected to the upper fixed frame (1a) via these bearing boxes (6). However, these bearing boxes (6)
Since it is not directly affected by heat from the slab (B), it has a normal form without a water cooling jacket. On the other hand, a roll (2) as a lower roll is formed into a short roll and is provided via a bearing box (3) having a water-cooled jacket (3a), similarly to the embodiment shown in FIG. It is connected to the pressing frame (1b).

In the roll apparatus of the present embodiment having the above-described structure, a predetermined amount of reduction is mainly applied by a lower roll to a center portion in the width direction of a slab having an unsolidified portion in the center, and the slab is formed by solidification shrinkage. It is intended to prevent segregation by suppressing the flow of molten steel due to suction based on center porosity and solidification shrinkage, and is particularly intended for slab-shaped slabs having a relatively large aspect ratio.

In the two embodiments described above, the bearing box (3) supporting the roll (2) formed as a short roll is used.
Has a water-cooled jacket (3a) integrally provided on the outer periphery, but the water-cooled jacket covers the outer peripheral side of the bearing box (3) and prevents temperature rise due to radiant heat from the slab (B). If so, the bearing housing (3)
It goes without saying that it may be provided separately and separably from the main body.

In the above-described two embodiments, a pressure frame and a hydraulic cylinder for driving the pressure frame are provided below the roll stand, whereby the lower roll is moved to move the lower roll. Although the amount of reduction is adjusted and controlled, this is merely an example, and it goes without saying that they may be arranged on the upper part of the roll stand and moved on the upper roll side.

[0030]

As described above, according to the roll apparatus for continuous casting according to the present invention, the length of the roll that applies the reduction to the center in the width direction of the slab is set to the minimum necessary length. Even if the outer diameter is reduced, the required bending rigidity can be secured, whereby the roll arrangement pitch can be narrowed and segregation of the slab and generation of center porosity can be effectively prevented. Further, the amount of material used for the production of each roll can be kept low, so that the production cost can be reduced and the economy is excellent.

[Brief description of the drawings]

FIG. 1 is a vertical cross-sectional view illustrating a main configuration of a roll device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a roll arrangement pitch related to the roll device of the embodiment of the present invention.

FIG. 3 is a longitudinal sectional view showing a main configuration of a roll device according to another embodiment of the present invention.

FIG. 4 is a longitudinal sectional view showing a configuration of a main part of a conventional roll device.

[Explanation of symbols]

(1)-Roll stand, (1a)-Upper fixed frame, (1b)-
Roll-down frame, (1c)-Lower fixed frame, (2)-Roll,
(2a)-Roll body, (2b)-Both ends shaft, (3)-Bearing box, (3a)
--Water-cooled jacket, (4) --hydraulic cylinder, (B) --cast slab,
(M)-Unsolidified part.

Claims (2)

(57) [Claims] 1. A roll device for continuous casting in which lower and upper rolls disposed in a roll stand apply pressure to a slab having an unsolidified portion in the center, and one or both rolls of the upper and lower rolls are provided. Is formed as a short roll in which both end shafts are directly provided on a roll body portion having a shorter length than the width dimension of the cast slab. 2. The roll device for continuous casting according to claim 1, wherein the roll formed as a short roll is supported by a bearing box provided with a water-cooled jacket on the outer peripheral side.