JPH1085810A - Method for zero-regulation in leveling of hot roll finish rolling mill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the accuracy of the zero regulation in the draft position and the leveling by reducing the variance in thrust through the difference in the peripheral speed of upper and lower work rolls to reduce the variance in the differential load of the zero regulation in the leveling. SOLUTION: When the peripheral speed of an upper work roll 6 is higher than that of a lower work roll 7, the differential peripheral speed Pd1 is applied to an inlet side of the upper work roll 6 with the lower work roll 7 slow in the peripheral speed as a resistance, and the differential peripheral speed Pd2 is applied to an outlet side of the lower work roll 7 because the upper work roll 6 higher in the peripheral speed presses the lower work roll 7 toward the outlet side. The friction force FB of a bender cylinder 13 is applied to a roll chock 11. The force is generated by the sliding resistance to be applied to a sliding part between the bender cylinder 13 and the roll chock 11, and constantly in the direction to stop the movement of the roll chock 11. When the chock position is stabilized, variance of the cross angle is reduced, and variance of the differential load is also reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a leveling zero adjustment method for a finishing mill for rolling a hot-rolled steel sheet.

[0002]

2. Description of the Related Art FIG. 1 shows the construction of a general hot rolling finishing mill. In the figure, Op indicates the operator side,
Dr indicates the drive side. Reference numeral 1 denotes a hydraulic pressure reduction cylinder on the operator side, and reference numeral 2 denotes a hydraulic pressure reduction cylinder on the drive side. 5 is an upper backup roll, 6 is an upper work roll, 7 is a lower work roll, and 8 is a lower backup roll. Reference numeral 3 denotes an operator-side load cell, and reference numeral 4 denotes a drive-side load cell.

In hot rolling, it is necessary to set the opening of the gap between the upper and lower work rolls 6 and 7 of the finishing mill in order to roll to a target thickness. This opening degree setting is usually set by hydraulic pressure-lowering cylinders 1 and 2 on the operator side and the drive side on the upper backup roll 5. The positions (oil column positions) of the hydraulic pressure lowering cylinders 1 and 2 are recognized by a magnescale in the cylinder. At this time, if the shape of the work rolls 6 and 7 changes due to thermal deformation, wear, or replacement of the rolls, the position of the oil column (the value of the magnescale) at which the opening between the rolls becomes zero changes.

For this reason, the position of the oil column at which the inter-roll opening of the work rolls 6 and 7 becomes zero is stored, the position of the hydraulic pressure reduction cylinders 1 and 2 is adjusted based on the stored value, and the inter-roll opening is adjusted. I am making adjustments. The operation of storing the oil column position of the roll-to-roll opening serving as this reference (the operation of associating the roll-to-roll opening with the oil column position) is referred to as a roll-down position zero adjustment. As described above, when the roll changes, the oil column position at which the inter-roll opening becomes zero changes, so when the work rolls 6 and 7 are rearranged,
It is necessary to perform the rolling position zero adjustment.

[0005] If the roll opening is not parallel (uniform) in the roll width direction (barrel direction), there is a difference in the amount of reduction between the operator side and the drive side, and there is a possibility that the rolled material may meander. . Therefore, at the same time as the above-described zero adjustment of the rolling position, the oil column difference in which the roll opening is parallel in the roll barrel direction is also stored. This work is called leveling zero. In normal leveling zero adjustment, the hydraulic pressure on the operator side and the drive side is adjusted so that the differential load (difference between the load on the operator side load cell 3 and the load on the drive side load cell 4) at the time of 1500 [t] reduction matches the target differential load. The positions of the pressing cylinders 1 and 2 are adjusted, and the values are stored.

At this time, generally, the work rolls 6 and 7 are rotating, but when the rolls cross between the work rolls and between the backup rolls, a thrust force is generated in the axial direction between the rolls. This thrust force is determined by a thrust coefficient representing the magnitude of the thrust force with respect to the actual load.

FIG. 2 shows the relationship between the roll cross angle and the thrust coefficient. At the time of zero adjustment, a water-cooled state as shown by a symbol W in the drawing is shown, and the thrust coefficient changes greatly even at a small cross angle. Therefore, even if the cross angle is slightly increased, a large thrust force is generated.

FIG. 3 is a plan view of the roll 10. As shown in FIG. 3, the rolling mill has a housing (crosshead).
9 and the roll chock 11 have a clearance d, and the cross angle θ changes accordingly. The change in the cross angle θ due to the clearance d is usually uncontrollable.
For example, in the example shown in FIG. 3, a minute cross angle of θ = 0.04 ° may occur. That is, the cross angle θ may change in the range of ± 0.04 °.

FIG. 4 shows the relationship between the cross angle, the difference load, and the thrust force when the lower work roll 7 and the lower backup roll 8 cross each other. As shown in FIG.
At a minute cross angle of 0.04 °, a thrust force of 120 [t] is generated. This thrust force allows the differential load on the operator side and drive side to be ±
It is changed by 60 [t]. As a result, the leveling amount was ± 6.
00 [μm].

[0010]

However, in such a state in which the difference load changes due to the thrust force, the leveling is adjusted so that the difference load becomes the target difference load. It changes from the true leveling value (the gap between the rolls is parallel). Therefore, when rolling is performed in this state, there is a problem that a meandering occurs in the steel sheet, which may cause a line trouble and reduce the operation rate.

The present invention has been made in view of the above-mentioned conventional problems, and it is an object of the present invention to provide a technique for improving the accuracy of a roll-down position zero adjustment and a leveling zero adjustment.

[0012]

According to the present invention, there is provided a leveling zero adjustment method for a hot rolling finishing mill, wherein a difference in thrust force is reduced by giving a difference in peripheral speed between upper and lower work rolls to reduce a difference in leveling zero adjustment. The above problem has been solved by reducing the variation in load.

According to the present invention, when the leveling is zero, a difference in peripheral speed between the upper and lower work rolls is provided, the clearance between the housing and the roll chocks is shifted to one side, and the chocking position is stabilized to stabilize the cross angle. , The variation of the differential load is reduced, so that it is not affected by the change of the differential load due to the thrust force caused by the cross angle between the rolls, and the gap between the rolls can be accurately set in parallel. It became.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings.

This embodiment is carried out for a general hot rolling finishing mill as shown in FIG.

As described above, when the work rolls 6 and 7 are rearranged, zero leveling is performed. At this time, the work rolls 6 and 7 are in a rotating state. In order to stabilize the roll cross angle, the choke position of the roll 10 is always stuck to the entry side 9a of the housing 9 as shown in FIG. 5, or is always at the exit side 9b of the housing 9 as shown in FIG. It should just stick. Whether the chock position of the roll 10 is settled on the entrance side 9a or the exit side 9b of the housing 9 is determined by the balance of the forces acting on the roll 10 and the roll chock 11. In FIGS. 5 and 6, reference numeral 12 denotes a choc liner.

Hereinafter, the forces acting on the work rolls 6 and 7 and the roll chock 11 will be described with reference to the drawings.

As shown in FIG. 7, the work rolls 6, 7 are offset from the backup rolls 5, 8 to the exit side.
Due to this offset, an offset component Po, which is a component of the rolling load P in the exit side, acts on the exit side of the work rolls 6 and 7. At this time, if the diameter of the work rolls 6 and 7 is DW, the diameter of the backup rolls 5 and 8 is DB, and the offset amount is do, the offset component Po
Is given by the following equation (1).

Po = P × do / {(DW + DB) / 2} (1)

If there is a peripheral speed difference between the upper and lower work rolls 6 and 7, the force caused by the sliding friction is increased.
Works between seven. That is, when the peripheral speed of the upper work roll 6 is made larger than the peripheral speed of the lower work roll 7, as shown in FIG. A peripheral speed difference Pd1 acts on the lower work roll 7, and the upper work roll 6 having a high peripheral speed pushes the lower work roll 7 to the output side, so that the peripheral speed difference Pd1 is applied to the output side.
2 works.

Also, as shown in FIG.
1, the frictional force FB of the bender cylinder 13 acts. This is the bender cylinder 13 and roll chock 1
This is a force generated by sliding resistance acting on the sliding portion 1 and always acts in a direction to stop the movement of the roll chock 11.

FIG. 10 shows the forces acting on the upper and lower work rolls 6 and 7 and the roll chock 11 described above. Basically, the position of the roll chock 11 is determined by the balance of these forces. That is, when the sum of the forces acting on the chocks indicated by Q in FIG. 9 is greater than the frictional force FB of the bender cylinder, the roll chocks 11 will stick to the entrance or exit housing.

However, in general, since the sliding resistance of the bender cylinder 13 is large, if there is no difference in peripheral speed between the upper and lower work rolls 6 and 7, the roll chock 11 is in an intermediate position before sticking to the entrance side or the exit side. , The cross angle changes each time.

Therefore, in the present embodiment, as described above, the peripheral speed of the upper work roll 6 is made larger than the peripheral speed of the lower work roll 7, and a peripheral speed difference is provided between the upper and lower work rolls 6, 7. 8, the peripheral speed differential forces Pd1 and Pd2 are generated.

FIG. 11 shows the relationship between the peripheral speed difference (%) between the upper and lower work rolls 6 and 7 and the sum Q of the forces acting on the roll chock 11.

As shown in FIG. 11, the difference in peripheral speed is 0% to 0.1%.
In the range of 02%, the chocking position becomes an intermediate position between the entrance side and the exit side due to the sliding resistance of the bender cylinder 13, so that the state becomes unknown. When the difference in peripheral speed increases, the acting force in the entry side increases, and when a difference of 0.02% or more occurs, a roll having a large peripheral speed (the upper work roll 6 in this embodiment).
Is attached to the entry side, and the roll having a low peripheral speed (the lower work roll 7 in this embodiment) is attached to the exit side, and the chocking position is stabilized.

As described above, when the chocking position is stabilized, the variation of the cross angle is reduced, and the variation of the difference load is also reduced. As a result, the null value is also stabilized.

FIG. 12 shows a comparison between the case where the zero adjustment is actually performed with the peripheral speed difference and the case where the zero adjustment is performed without the peripheral speed difference. As can be seen from FIG. 12, the variation in the oil column difference is smaller when the peripheral speed difference is given.

FIG. 13 shows a comparison between the oil column difference when rolling is performed in a state where the gap between the rolls is parallel in an actual hot finish rolling mill and the zero adjustment value according to the present embodiment. FIG.
As shown in FIG. 3, the variation of the oil column difference is small and matches the oil column difference at the time of rolling by adjusting the target difference load.

As described above, according to the present embodiment, since the peripheral speed difference is provided between the upper and lower work rolls, the chocking position can be stabilized and the variation in the difference load can be reduced.

[0031]

As described above, according to the present invention,
At the time of zero leveling, a roll peripheral speed difference is provided between the upper and lower work rolls to stabilize the chocking position. By setting, it is possible to set the gap between the rolls in parallel with high accuracy, and it is possible to improve the accuracy of leveling zero adjustment.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a general hot-rolling finishing mill;

FIG. 2 is a diagram showing a relationship between a roll cross angle and a thrust coefficient.

FIG. 3 is a plan view of a work roll showing a state of a minute cross angle generated by a clearance.

FIG. 4 is a diagram showing a relationship between a thrust force generated by a minute cross angle and a differential load.

FIG. 5 is a plan view showing a state in which a chock position is attached to a housing entrance side.

FIG. 6 is a plan view showing a state in which a chock position is stuck to a housing exit side.

FIG. 7 is a side view showing the output side offset of the upper and lower work rolls.

FIG. 8 is an explanatory diagram showing a peripheral speed differential force between upper and lower work rolls.

FIG. 9 is an explanatory diagram showing a frictional force by a bender cylinder.

FIG. 10 is an explanatory diagram showing the forces acting on the upper and lower work rolls and the chocks.

FIG. 11 is a diagram showing a relationship between a difference in roll peripheral speed and a force acting on a chock;

FIG. 12 is an explanatory diagram showing a variation in leveling zero tone.

FIG. 13 is an explanatory diagram showing a comparison between a leveling null value and an oil column difference during rolling.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Hydraulic pressure reduction cylinder at operator side 2 ... Hydraulic pressure reduction cylinder at drive side 3 ... Load cell at operator side 4 ... Load cell at drive side 5 ... Upper backup roll 6 ... Upper work roll 7 ... Lower work roll 8 ... Lower backup roll 9 ... Housing 10 ... Roll 11 ... Roll chock 13 ... Bender cylinder

Claims (1)

[Claims] 1. A leveling zero adjustment method for a hot rolling finish rolling mill, wherein a difference in thrust force is reduced by providing a difference in peripheral speed between upper and lower work rolls, and a difference in difference load in leveling zero adjustment is reduced. Characteristic leveling zero adjustment method for hot rolling finishing mill.