JP3542991B2 - Rolling method of steel strip using pair cloth rolling mill - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention provides an upper working roll, a pair of upper retaining rolls and a lower working roll, a pair of lower retaining rolls, and a steel strip using a pair cross rolling mill for controlling a rolling shape of the steel strip by horizontally crossing each set. Rolling method. More specifically, the present invention relates to a method of rolling a steel strip using a pair cross rolling mill that suppresses a sheet bending phenomenon caused by a clearance between a cross head and a roll chock of the pair cross rolling mill.
[0002]
[Prior art]
As disclosed in, for example, Japanese Patent Publication No. 63-12687, a pair cross rolling mill is provided with a work roll chock and a pre-roll chock by cross heads provided at a total of eight locations on an inlet / outlet side, a drive / work side, and upper and lower sides. Are simultaneously operated to cross the work roll and the holding roll as a pair in an upper and lower pair, thereby controlling the crown shape of the steel sheet.
FIG. 1 illustrates a cross-sectional view of a four-stage pair cross rolling mill as viewed from the roll axis direction.
The upper cross roll (BUR) and the upper work roll (WR), and the lower cross roll (BUR) and the lower work roll (WR) are paired with each other. The cross angle of the upper and lower rolls is adjusted by the entry-side crosshead 4.
[0003]
This pair cross rolling mill secures a clearance of about 1.5 mm between the cross head and the roll chocks in consideration of smoothing of the operation of changing the roll cross angle and reduction of the width of the housing due to the rolling load.
In addition, the work roll and the holding roll have their axes offset from each other, and the work roll axis is normally shifted in the rolling direction (outward side of the steel strip). It was considered that the work roll was pressed in the rolling direction (outward direction of the steel strip) and the control roll was pressed in the anti-rolling direction (inward direction of the steel strip), so that the clearance was generated at a certain location.
[0004]
However, in actual operation, it was found that even when a rolling load was applied, the holding roll did not always move in the offset direction (the direction in which the steel strip entered) due to the sliding resistance between the holding roll and the housing surface. It was found that the clearance during rolling did not occur at a certain location every time the value was changed.
This means that a minute cross is generated between the work roll and the standby roll within the range of the clearance, and the cross is changed every time the cross angle is changed.
[0005]
Since the change of the minute cloth changes the thrust load generated in the axial direction of the retaining roll caused by the rolling load, the rolling load on the driving side and the working side during rolling is changed by the change in the overturning moment of the retaining roll.
This change in the rolling load causes a plate bending phenomenon every time the cross angle is changed.
The work roll has no sliding resistance with the housing surface unlike the control roll, so the work roll moves in the offset direction during rolling. Due to the influence, the work roll chock may move away from the exit side crosshead against the offset force, and this causes a so-called squeezing, which causes the steel strip to fold and break and wear the roll.
[0006]
As for an apparatus and a method for correcting a cross point of a pair cross rolling mill, Japanese Patent Application Laid-Open No. 8-294713 discloses a method using an actuator for absorbing a gap (play) generated between a cross head and a roll chock.
However, in this prior art, as shown in FIG. 3 of the publication, all the actuators for correcting the cross point are installed on one side of the rolling mill (the entrance side of the steel strip). No press force is disclosed, and a rolling method for preventing sheet bending and buttocks drawing phenomenon has not been established in a method of rolling a steel strip using a pair-cross rolling mill.
[0007]
[Problems to be solved by the invention]
The present invention solves the problems of the prior art as described above, and always keeps the position where the clearance between the crosshead and the roll chock occurs even when the roll cross angle of the pair cross rolling mill is changed, so that the steel strip is rolled. It is an object of the present invention to provide a method for rolling a steel strip using a pair cross rolling mill capable of suppressing the sheet bending and the tail drawing phenomenon.
[0008]
[Means for Solving the Problems]
The present invention relates to a crosshead for rolling even when the roll cross angle is changed by pressing the pre-roll chock or the pre-roll chock and the work roll chock in the rolling direction of the steel strip at the time of biting the steel strip using the crosshead liner. Cross-rolling that keeps the clearance between the work roll and the chock constant to prevent a slight change in the cross angle between the work roll and the control roll, and also prevents the work roll chock from vibrating when the steel strip is caught and the buttocks are removed. The present invention provides a method for rolling a steel strip using a mill, and its gist is as described below in the claims.
[0009]
(1) The pair of the upper work roll and the upper work roll and the pair of the lower work roll and the lower work roll are each horizontally crossed as a set to control the rolling shape of the steel strip. In the rolling method, when the steel strip bites into the rolling mill, the crosshead liner is turned on to press the upper and lower preserving roll chock in the rolling direction, and the upper and lower preserving rolls receive the upper and lower preserving roll chock during the rolling of the steel strip. A method of rolling a steel strip using a pair cross rolling mill, wherein the steel strip is pressed in a rolling direction with a force equal to or greater than an offset force.
(2) Further, when the steel strip bites into the rolling mill, the crosshead liner is turned on and the upper and lower work roll chock is pressed in the rolling direction. Strip rolling method.
Although the drive source of the crosshead liner is not limited, it is preferable to use a hydraulic cylinder which has excellent controllability and is easily available.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described in detail using an example of a four-stage pair cross rolling mill for hot rolling in FIG.
When the steel strip bites into the work roll (WR), the upper and lower retaining roll chocks 1 are rolled in the rolling direction of the steel strip (exit side of the steel strip) by a crosshead liner 5 with a built-in hydraulic cylinder provided on the entry side crosshead 4. Direction). By this operation, the pre-roll chock 1 is pressed against the output crosshead 3 by a force greater than the sliding friction between the pre-roll chock 1 and the housing of the rolling mill (not shown), and the outer surface of the pre-roll chock 1 is brought into close contact with the output crosshead 3. Therefore, the axis of the control roll is parallel to the inner surface of the exit side crosshead 3.
[0011]
When rolling is started, a horizontal component force acts in a direction in which the holding roll is offset from the work roll due to the rolling load, so that the holding roll chock 1 is pressed against the exit crosshead 3 with a force greater than this offset force. By attaching, the pre-roll chock 1 does not separate from the output side crosshead 3, so that the direction of the axis of the pre-roll does not change during rolling.
Thus, the influence of the clearance between the copy roll chock and the crosshead can be eliminated, and the relationship between the minute cross between the copy roll and the work roll can be kept constant. In order to sufficiently exhibit the effects of the present invention, in a rolling mill having a plurality of stands, it is particularly preferable to install a crosshead liner having a built-in hydraulic cylinder for a pre-roll chock in a subsequent stand including the last stand. This is because camber (board bending) is most affected by the last stage. Further, it is preferable to provide a crosshead liner having a built-in hydraulic cylinder for a roll roll chock in all stands.
[0012]
As a result, it has become possible to avoid a drop in yield and operational trouble due to plate bending caused by the clearance between the crosshead and the roll chock. Specifically, in the conventional pair cross rolling mill, a rolling differential load of up to about 10% was generated at both ends of the work roll for each coil rolling. However, this can be suppressed to within 3%, and the plate is greatly reduced. Bending was reduced.
When the steel strip bites into the work roll (WR), the upper and lower work roll chocks 2 are moved by the crosshead liner 6 with a built-in hydraulic cylinder provided on the entry side crosshead 4 in the rolling direction of the steel strip (outside of the steel strip). Direction). By this operation, the work roll chock 2 is pressed against the exit crosshead 3 and the outer surface of the work roll chock 2 comes into close contact with the exit crosshead 3, so that the axis of the work roll is parallel to the inner surface of the exit crosshead 3. .
[0013]
When rolling is started, a horizontal component force acts in a direction in which the work roll is offset with respect to the control roll due to the rolling load. Therefore, even when the crosshead liner 6 is turned off, the work roll chock 2 is kept on the exit side crosshead. 3, the direction of the axis of the work roll does not change during rolling.
Accordingly, it is possible to prevent a vibratory behavior (a movement in which the work roll chock 2 is momentarily separated from the exit side crosshead 3) when the steel strip bites into the work roll and when the steel strip comes off the rolling mill. As a result, the incidence of tail squeezing has been halved, and at the same time, the unit consumption of rolls has been greatly improved by reducing the number of accident rolls.
[0014]
As shown in FIG. 2, by pressing the control roll chock 1 and the work roll chock 2 in the same rolling direction, when checking the wear of the contact surface between the roll chocks 1 and 2 and the output cross head 3, etc. Only the head 3 side needs to be inspected, and it is not necessary to inspect the entrance cross head side. This has the advantage that the labor and cost of equipment management can be reduced by half, such as deterioration of the rolling mill over time. Can greatly contribute to
In order to sufficiently exhibit the effects of the present invention, in a rolling mill having a plurality of stands, a crosshead liner having a built-in hydraulic cylinder for work roll chocking in three subsequent stages including a final stage having a high rolling speed is installed. Is preferred. The reason for this is that the final stage has the highest drawing ratio for the rear end, and the effect of installing the crosshead liner at the final stage is great.
[0015]
【The invention's effect】
According to the present invention, the roll cross angle is changed by pressing the pre-roll chock or the pre-roll chock and the work roll chock in the rolling direction of the steel strip at the time of biting the steel strip using the cross head liner including the hydraulic cylinder. Even at this time, the clearance between the crosshead and the roll chock during rolling can be kept constant to prevent a minute change in the cross angle between the work roll and the control roll.
In addition, it is possible to prevent the work roll chocks from vibrating when the steel strip is bitten and the buttocks are removed, and the position where the clearance between the crosshead and the roll chocks always occurs even when the roll cross angle of the pair cross rolling mill is changed. It is possible to suppress the bending of the steel sheet and the phenomenon of drawing at the bottom when the steel strip is rolled.
Furthermore, the wear control of the contact surface between the roll chock and the crosshead can be centralized on the exit side crosshead side, so that there is an industrially useful and remarkable effect.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a four-stage pair cross rolling mill as viewed from a roll axis direction.
FIG. 2 is a diagram showing an embodiment of a pair cloth rolling mill according to the present invention.
[Explanation of symbols]
Reference numeral 1: Pre-roll chock 2 ... Work roll chock 3 ... Outgoing crosshead 4 ... Ingress crosshead 5 ... Crosshead liner (for pre-roll chock)
6 Crosshead liner (for work roll chock)
WR: Work roll (work roll)
BUR: Backup roll (copy roll)

Claims (2)

In the method of rolling a steel strip using a pair cross rolling mill in which a pair of upper work rolls, a pair of upper hold rolls, a lower work roll, and a pair of lower hold rolls, each of which is horizontally crossed in a set to control the rolling shape of the steel strip. When the steel strip bites into the rolling mill, the crosshead liner is turned on, and the upper and lower preparatory roll chock is pressed in the rolling direction. A method of rolling a steel strip using a pair-cross rolling mill, wherein the steel strip is pressed in a rolling direction by a force of the above. The rolling of the steel strip using the pair cross rolling mill according to claim 1, wherein when the steel strip is bitten into the rolling mill, the crosshead liner is turned on and the upper and lower work roll chock is pressed in the rolling direction. Method.

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