JPH09239408A - Work roll moving system rolling mill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To further improve a function making the wear dispersion of work rolls and the security of a plate crown control capacity compatible each other than usual by further uniromizing a plate crown control capacity on a work roll moving position. SOLUTION: In this rolling mill, the initial crowns C1 and C2 of a pair of bendable upper and lower work rolls 11 and 12 are arranged so that the initial crowns C1 and C2 are in point symmetry with respect to the mill center. A driving means making thes upper and lower work rolls 11 and 12 shift in reverse directions each other to the mill center along with an axial direction, is provided. On thes upper and lower work rolls 11 and 12, a tapered initial crown C1 is formed, which is gradually tapered toward a roll edge on the shift direction side. Hereupon, the starting point position S of the tapered initial crown C1 is set at a position shifted by a prescribed quantity (5% or over of the barrel length of the work roll) toward the antishift direction side of the work roll from the barrel centers of the upper and lower work rolls 11 and 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling mill having a structure capable of axially moving a pair of upper and lower work rolls (hereinafter referred to as a work roll moving type rolling mill).

[0002]

2. Description of the Related Art In recent years, in the field of hot rolling of sheet material, it is possible to prevent deterioration of the cross-sectional profile and flatness of the rolled material due to local abrasion of the work roll surface when the number of strips of the same width is increased. Therefore, a rolling mill with a structure that can move a pair of upper and lower work rolls in the axial direction has been developed,
A method has been implemented in which the work roll is axially moved for each rolled material or for every plural rolled material to disperse the wear of the work roll.

On the other hand, since the work roll moving type rolling mill can increase the effect of the work roll bending force and increase the plate crown controllability by moving the work roll in the axial direction, there is a demand for the plate width direction plate thickness accuracy of the rolled material. With the tightening, it is used in many mills for the purpose of controlling the plate crown. However, when the work roll moving rolling mill is rolled by regularly moving the work roll to disperse the wear of the work roll, the plate crown control capability greatly changes depending on the moving position of the work roll. There is a problem that the required plate crown cannot be secured depending on the moving position of the.

That is, as shown in FIG. 7, the farther the center of the work roll is from the center of the mill, the smaller the restraint of the backup roll against the elastic bending deformation given to the work roll by the roll bending device. Although the control capability increases, as the center of the work roll approaches the center of the mill, the restraint of the backup roll increases and the plate crown control capability decreases.
When the center of the work roll is located at the center of the mill, it has only the same ability to control the plate crown as a normal four-high rolling mill.

Therefore, in the case of rolling a material for which the demand for reducing the plate crown is strict, a method of rolling by limiting the work roll to a position away from the center of the mill has been used.
As a result, the work roll wear cannot be sufficiently dispersed. Therefore, the inventors of the present invention have improved the property that the plate crown controllability greatly changes depending on the work roll movement position, and in order to achieve both dispersion of the work roll wear and securing of the plate crown controllability, the body portion of the work roll is One side of the initial crown formed from the center toward the body end is formed larger than the other side, and the work rolls are arranged so that the large initial crown and the small initial crown are vertically overlapped, and the center of the work roll is a mill. A method of rolling at a position on the side where a large initial crown is formed with respect to the center was devised (JP-A-3-421).
No. 06).

FIG. 2 shows the shape and arrangement of such a conventional work roll, and the arrow in the drawing indicates the moving direction. Further, in FIG. 3, the state where the work roll center is at the mill center is shown by a two-dot chain line, and the state where the work roll center is farthest from the mill center is shown at a solid line. In this case, the side on which the large initial crown is formed is separated from the center of the mill by the movement of the work roll. Further, in the figure, l (el) indicates a movable stroke of the work roll.

In this conventional method, when the center of the work roll is located at the center of the mill, the portion of the work roll on which the large initial crown is formed abuts the material to be rolled over a wide range, so that the plate crown by the crown is formed. The reduction effect is the largest, and a large plate crown controllability can be obtained. On the other hand, when the center of the work roll moves from the mill center to the side where the large initial crown is formed, the range where the part of the work roll where the large initial crown is formed contacts the material to be rolled becomes narrower and the plate crown becomes narrower. Although the reduction effect is reduced, the restraint of the backup roll on the work roll bending is reduced at this time, so the plate crown reduction effect by roll bending is increased, and a large plate crown controllability can be obtained.

[0008]

However, in the conventional method, there is still room for improvement in that the plate crown control ability is made uniform regardless of the movement position of the work roll. That is, when the center of the work roll moves from the center of the mill to the side where the large initial crown is formed, the effect of reducing the plate crown by this crown gradually decreases, but the effect of reducing the plate crown by roll bending is as shown in FIG. If the distance between the roll center and the mill center does not become larger than a certain amount, the margin of increase is small. Therefore, as shown in Fig. 4, the ability to control the plate crown by combining the initial crown and roll bending is at the position where the work roll center moves a little from the mill center. It gets smaller.

The present invention solves such a problem that remains in the conventional method, and further uniformizes the plate crown control capability relating to the work roll moving position to disperse the work roll wear and secure the plate crown control capability. An object of the present invention is to provide a work roll moving type rolling mill capable of further improving the function of achieving both of the above.

[0010]

In order to achieve the above object, the present invention takes the following technical means. That is, according to the present invention, a pair of upper and lower bendable work rolls are arranged so that their initial crowns are point-symmetrical with respect to the mill center, and the upper and lower work rolls are opposite to each other along the axial direction with respect to the mill center. In the work roll moving rolling mill, a drive means for shifting the work roll is provided, and the upper and lower work rolls are formed with a tapered initial crown whose diameter gradually decreases toward the roll end on the shift direction side. The starting point position of the initial crown is set at a position displaced from the center of the body of the upper and lower work rolls by a predetermined amount in the opposite shift direction side of the work rolls (claim 1).

In this case, it is preferable that the predetermined amount is 5% or more of the work roll body length (claim 2). Also,
A flat initial crown can be formed as a large initial crown in the range from the starting point position of the tapered initial crown in the upper and lower work rolls to the roll end on the side opposite to the shift direction (claim 3).

Here, in the conventional method, the boundary between the large initial crown and the small initial crown (the starting point position of the tapered initial crown) is set at the center of the body of the upper and lower work rolls. The boundary of the initial crown (starting point position) is set at a position separated from the center of the upper and lower work roll body parts by a predetermined amount (preferably 5% or more of the work roll body length) in the direction opposite to the moving direction. There is.

Therefore, as shown in FIG. 8, in the present invention, the side on which the large initial crown is formed (the right side in FIG. 8) has a larger range than the conventional work roll, and the initial crown is gentle. The area on the side where the small initial crown is formed (on the left side in FIG. 8) decreases and the initial crown becomes steep. Here, the effect of reducing the plate crown by the initial crown is
It is determined by the effective crown represented by the equation (1), that is, the roll crown in the range where the plate contacts the roll.

CR = DW _C − (DW _L + DW _S ) / 2 ……………… (1) CR: Effective crown DW _C : Work roll diameter at the center of plate width DW _L : Plate crown on the side of the large initial crown Work roll diameter at the evaluation position DW _S : Work roll diameter at the plate crown evaluation position on the side of the small initial crown The present invention is different from the conventional method in that DW _{L in the} formula (1) is changed by the above-described change in the shape of the initial crown. although that is smaller, DW _S but is larger, increases the overall effective crown for the former is larger amount change,
The effect of reducing the plate crown is increased.

[0015] However, when the work roll center is in the vicinity of the mill center is in contact with the region of large initial crown also plate width center position, the DW _C than the conventional method is reduced, that amount effective crown is small Therefore, the amount of increase in the plate crown reducing effect decreases. When the center of the work roll moves from the center of the mill and the boundary of the initial crown (starting point position) is on the side of the initial crown that is larger than the center of the mill, the center position of the plate width will contact the area of the smaller initial crown as in the conventional method. Therefore, there is no decrease in the amount of increase in the plate crown reducing effect as described above.

Here, the distance from the center of the body of the work roll to the boundary (starting point position) of the initial crown (hereinafter,
This distance will be referred to as δ. The reason why) is set to 5% or more of the work roll body length will be described. As described above, δ is for ensuring the plate crown control ability by compensating for the decrease in the plate crown reducing effect due to the initial crown in the conventional method when the work roll center is in a region slightly away from the mill center. Therefore, it is decided based on the relationship between the work roll movement position determined by the shape of the initial crown and the plate crown reduction effect, and the relation between the work roll movement position determined by the mill size and structure and the plate crown reduction effect by roll bending. do it.

In the work roll moving type rolling mill having general dimensions and specifications, the point where the plate crown control capability is the minimum in the conventional method shown in FIG.
% Area. Therefore, the influence of δ on the improvement effect ΔCR over the conventional method of the present invention at the position where the amount of work roll movement shown in FIG. 9 is 7.5% of the body length was examined. FIG.
The work roll shape examined is shown.

That is, a position δ away from the center of the upper and lower work rolls 11 and 12 in the direction opposite to the moving direction (shift direction) is defined as a boundary point S, and different initial crowns C1 and C2 are provided on both sides of the boundary point S. Is formed, and from the boundary point S to the body end on the side closer to the mill center by the movement of the work roll (left side in FIG. 6), a flat initial crown C2 having the same diameter is formed. The body end on the side away from the mill center (right side in FIG. 6) due to the movement of the roll is 0.
A parabolic initial crown C1 is formed that is 4 mmφ smaller and has a diameter that gradually decreases from the boundary point S to the body end in the body end direction.

FIG. 10 shows ΔCR and δ at a work roll moving amount of 150 mm when the work roll having the shape shown in FIG. 6 has a body length of 2000 mm, a plate width of 1050 mm, and a plate crown evaluation point of 25 mm from the plate width end. Shows the relationship. The plate width of 1050 mm is generally one of the body length.
This is due to the large amount of rolling with a plate width of about / 2. The larger the δ is, the larger the improvement amount is. However, it is understood that the characteristic changes with δ = 150 mm, that is, the point where the work roll movement amount for which the improvement effect is examined and δ coincide with each other as an inflection point.

From these results, in the work roll moving type rolling mill having general dimensions and specifications, δ is 5% of the work roll body length in order to effectively improve the area where the plate crown reducing ability is small by the conventional method. It is desirable to set the above. Therefore, according to the present invention, as shown in FIG. 5, the control capability is increased in the work roll moving region where the plate crown control capability remains small in the conventional method, and the plate crown control is performed in the entire work roll moving range. Ability can be brought close to uniform.

In the present invention, the lower limit of δ is set to 5% or more of the work roll body length, but the upper limit of δ is not specified for the following reason. That is, even when δ is increased and the work roll is moved, if the boundary point does not fall within the plate width, the effective crown does not change depending on the work roll shift position as in the case of using the symmetrical convex crown roll, This is because the meaning of the present invention is lost, and the upper limit of δ is naturally determined mainly by the plate width of the target material for which the effect of reducing the plate crown is to be improved.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described. FIG. 1 is a view showing the arrangement of rolling mills and work rolls of a hot strip mill in which the present invention is carried out, in which first to third stands 1, 2 and 3 are provided with ordinary four-high rolling mills, Fourth to seventh stands 4, 5, 6, 7
Is equipped with a four-high rolling mill in which the work rolls 11 and 12 move in the axial direction. A work roll bending device is installed at each of the third to seventh stands 3, 4, 5, 6, 7.

A work roll having a body length of 2186 mm is arranged on each of the first to seventh stands. In the figure, 8 is a material to be rolled (plate material) rolled in the direction of the arrow,
A plate profile detector 13 measures the plate crown. The arrangement of the work rolls of the present invention applied to the fourth to sixth stands 4, 5 and 6 is the same as that of the conventional method shown in FIG. 2, but the work roll shape is different from that of the conventional method, as shown in FIG.
The shape is shown in. However, δ was set to 200 mm.

That is, the tapered initial crown C
The starting point position S of 1 is set to a position displaced by 200 mm (about 9% of the work roll body length) from the center of the body portion of the upper and lower work rolls 11 and 12 to the opposite shift direction side of the work rolls 11 and 12. The seventh stand 7 is also a rolling mill in which the work rolls can move in the axial direction. However, since the stand does not have a high rolling load and the plate crown control capability is not so required, a flat work roll is provided over the entire length. Are using.

In the present embodiment, the upper and lower work rolls 1
The movable strokes of 1 and 12 are 600 mm for each work roll of each stand, and the upper and lower work rolls 11 and 12 were moved in the movement range in the following manner to roll the plate material. That is, the upper and lower work rolls for each rolled material from the center of the mill have a distance between the plate width end and the work roll body end of 3
When the plate width end is within a certain distance (75 mm in this example) from the body end of the work roll by moving them in opposite directions along the roll axial direction so as to change by 0 mm, the moving direction of the work roll Was reversed and moved toward the center of the mill. Further, when the center of the work roll reached the center of the mill, the moving direction of the work roll was similarly reversed.

The conventional method was also rolled by the above method, and the actual values of the plate crowns were compared under the rolling conditions shown below. As a result, the work roll moving position was 10 from the mill center.
In the range of 0 mm to 300 mm, the present invention can reduce the thickness by 5 μm as compared with the conventional method. Steel type: General mild steel product plate thickness: 2-3 mm Plate width: 1100-1300 mm Target crown: 50 μm In the present embodiment, the upper and lower work rolls 11 and 12 are used.
Although a parabolic shape is used as the tapered initial crown C1 formed in the above, the present invention is not limited to this.
A smooth shape such as an arc or a part of a sine curve, or a tapered shape may be used.

[0027]

As described in detail above, according to the present invention,
Since the tapered initial crown is formed starting from the position shifted from the center of the upper and lower work rolls in the opposite direction to the shift direction, compared to the conventional case, the plate crown is irrespective of the movement position of the work roll. The control ability can be made more uniform.

As a result, it is possible to further improve the function of making the wear roll wear dispersion and the plate crown control ability compatible with each other as compared with the conventional case.

[Brief description of drawings]

FIG. 1 is a view showing an arrangement of rolling mills and work rolls of a hot strip mill embodying the present invention.

FIG. 2 is a diagram showing a shape of a work roll of a conventional method and an arrangement of work rolls common to the conventional method and the present invention.

FIG. 3 is a diagram showing a relationship between a work roll moving position and a material to be rolled, which is common to the conventional method and the present invention.

FIG. 4 is a diagram showing a relationship between a work roll moving position and a plate crown controllability when a work roll having a shape according to a conventional method is used for rolling.

FIG. 5 is a diagram showing a relationship between a work roll moving position and a plate crown control capability when rolling is performed using a work roll having a shape according to the present invention.

FIG. 6A is a diagram showing the shape of a conventional work roll;
(B) is a figure which shows the work roll shape which concerns on embodiment of this invention compared with the conventional method.

FIG. 7 is a diagram showing a relationship between a work roll moving position and plate crown control capability when a work roll having a flat shape is used for rolling in a work roll moving type rolling mill.

FIG. 8 is a graph showing the relationship between the axial position of the work roll and the work roll diameter in order to show the difference between the present invention and the conventional work roll shape.

FIG. 9 is a graph showing the relationship between the work roll movement position from the center of the mill and the effective crown.

FIG. 10 is a distance δ from the center of the body of the work roll to the boundary of the initial crown and the improvement amount ΔCR of the effective crown.
6 is a graph showing a relationship with the graph.

[Explanation of symbols]

 1-3 Conventional 4-high rolling mill for hot strip mill 4-7 Work roll moving 4-high rolling mill 8 Rolled material 9 Backup roll 11 Upper work roll 12 Lower work roll C1 Tapered initial crown C2 Flat initial crown

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[Procedure amendment]

[Submission date] June 28, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Fig. 6

[Correction method] Change

[Correction contents]

FIG. 6 compares the shapes of the work rolls of the conventional method and the present invention.
FIG.

Claims (3)

[Claims] 1. A pair of upper and lower bendable work rolls are arranged such that their initial crowns are point-symmetrical with respect to the mill center, and the upper and lower work rolls are opposite to each other along the axial direction with respect to the mill center. In the work roll moving rolling mill, which is provided with a drive means for shifting the work roll, the upper and lower work rolls are formed with a tapered initial crown whose diameter gradually decreases toward the roll end on the shift direction side. A work roll moving rolling mill, wherein the starting point position of the initial crown is set at a position deviated by a predetermined amount from the center of the body of the upper and lower work rolls to the side opposite to the shift direction of the work rolls. 2. The predetermined amount is 5% of the body length of the work roll.
The work roll moving type rolling mill according to claim 1, which is set as described above. 3. A flat initial crown having the same diameter is formed in the range from the starting point position of the tapered initial crown of the upper and lower work rolls to the roll end on the side opposite to the shift direction. The work roll moving rolling mill described.