JP4161606B2 - Zeroing method of rolling mill - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a zeroing method for a rolling mill, and particularly suitable for use in a cross roll rolling mill, which can improve the zeroing accuracy in a state where the roll is stopped. About.
[0002]
[Prior art]
A front view of a general hot rolling finish rolling mill is shown in FIG. In the figure, Op indicates the operator side (driven side), and Dr indicates the drive side (drive side). 1 is a hydraulic pressure reduction cylinder on the operator side, and 2 is 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 (load detector), and reference numeral 4 denotes a drive side load cell.
[0003]
In rolling, in order to roll to the target plate thickness, it is necessary to set the opening of the gap between the upper and lower work rolls 6 and 7 of the finishing mill. The opening degree is set by an actuator such as the hydraulic pressure reduction cylinders 1 and 2 on the operator side and the drive side on the upper backup roll 5. The actuator end positions (determined from the oil column length and the like) of the hydraulic pressure reduction cylinders 1 and 2 are recognized by a sensor such as a magnescale in the cylinder, for example. Hereinafter, the case where the actuator is a hydraulic cylinder will be described as an example. However, when the diameter of the work rolls 6 and 7 changes due to the roll change, the position of the oil column at which the opening between the rolls becomes zero (output of a sensor such as a magnescale). Value) changes.
[0004]
Therefore, the oil column length at which the opening between the rolls of the work rolls 6 and 7 is zero is stored, the position of the hydraulic pressure reduction cylinders 1 and 2 is adjusted based on the value, and the oil column position of the opening between the rolls is adjusted. The work of memorizing (the work of associating the opening between the rolls with the oil column position) is referred to as a reduction position zero adjustment. As described above, when the roll diameter changes, the oil column position at which the opening degree between the rolls becomes zero changes. Therefore, when the work rolls 6 and 7 are rearranged, it is necessary to perform the reduction position zero adjustment. Alternatively, in the zero reduction control, the upper and lower work rolls 6 and 7 are brought into contact with zero opening, and further tightened with a predetermined force, so that the opening when tightened with the predetermined force becomes a negative predetermined value. It may be set and stored.
[0005]
Further, when the opening between the rolls is not parallel (uniform) in the roll center axis direction (roll barrel direction), there is a possibility that the rolling amount differs between the operator side and the drive side, and the meandering may occur in the rolled material. Therefore, for the purpose of ensuring the parallelism in the roll barrel direction of the opening between the rolls simultaneously with the above-described zero adjustment of the reduction position, the actuator is operated so as to ensure the parallelism, and the oil on the operator side and the drive side I remember the column difference. This operation is called leveling zero tone. In the reduction position zero adjustment, for example, tightening up to a predetermined load of 15000 [kN], and the operator side so that the differential load at this time (the difference between the load on the operator side 3 and the load on the drive side 4) is within the target differential load range. Then, the oil column positions of the hydraulic pressure reduction cylinders 1 and 2 on the drive side are adjusted to make leveling zero, and the value is stored.
[0006]
In general, the work rolls 6 and 7 are rotating at this time. However, when the work rolls 6 and 7 are rotating, when the rolls are crossed between the work rolls and the backup rolls, in the roll barrel direction of each roll. Thrust force is generated. This thrust force is determined by a thrust coefficient representing the magnitude of the thrust force with respect to the actual load.
[0007]
FIG. 2 shows the relationship between the roll cross angle and the thrust coefficient. Cross where the thrust coefficient (the average of the absolute value of the thrust force acting on the upper and lower work rolls in the roll barrel direction divided by the load acting on the upper and lower work rolls in the vertical direction) is greatly changed by subtle changes in the cross angle. There is a corner area. Therefore, even if the cross angle slightly changes, a large thrust force fluctuation may occur.
[0008]
FIG. 3 shows a plan view of the roll 10. As shown in FIG. 3, the rolling mill has a clearance d between the housing 9 (cross head 13 in the case of a cross roll mill) and the roll chock 11, and the cross angle θ changes accordingly. The change in the cross angle θ due to the clearance d is normally uncontrollable. For example, in the example shown in FIG. 3, a minute cross angle error of 0.04 ° at the maximum may occur.
[0009]
FIG. 4 shows the relationship between the cross angle, the differential load, and the thrust force when the lower work roll 7 and the lower backup roll 8 are crossed. As shown in FIG. 4, even when only a minute cross angle error of θ = 0.04 ° occurs, a thrust force of 1200 [kN] is generated. This thrust force changes the differential load between the operator side and the drive side by 600 [kN] depending on the moment. As a result, the leveling absolute amount changes by 600 [μm].
[0010]
In such a state in which the differential load changes due to the thrust force, in the method of leveling zero so that the differential load becomes the target differential load, if the cross angle is a finite value other than 0 °, the corresponding thrust force It will change from the leveling proper value (a state where the gap between rolls is parallel) by the amount. It is desirable that the cross angle is zero and zero adjustment. However, if a cross angle with a finite value occurs in the machine accuracy, a thrust load is likely to occur in the region of the minimum cross angle. It becomes a big disturbance factor. Therefore, when rolling is performed in this state, there is a problem that meandering occurs in the material to be rolled, which may cause a line trouble and reduce the operating rate.
[0011]
In order to solve these problems, Japanese Patent Laid-Open No. 10-128416 discloses that when performing leveling zero adjustment of the reduction position, the thrust force is reduced by stopping the rotation of the work roll, and the differential load of leveling zero adjustment is reduced. A technique for reducing the variation has been proposed. Incidentally, JP-A-10-128416 assumes the case of a cross roll mill.
[0012]
[Problems to be solved by the invention]
However, according to the method disclosed in Japanese Patent Laid-Open No. 10-128416, the chock position within the clearance d shown in FIG. 5 is determined by the relationship with the crosshead 13 at the time of roll reassignment, and differs for each roll recombination timing. Therefore, the work roll 7 may stick to the output side crosshead 13 and the backup roll 8 may stick to the input side crosshead 12, which may deviate from the originally desired offset position.
[0013]
After performing leveling zero adjustment by the above method in FIG. 6, the back-up roll chock position when the cross angle is increased or decreased while the work roll rotation is stopped is measured. The result which took the difference of the chock position by the difference in a moving direction is shown. The difference between the chock positions indicates a position difference in the d direction in FIG. 5 at the same cross angle. According to FIG. 6, it can be seen that the roll chock position varies depending on the cross angle changing direction from the previously set cross angle even at the same cross angle. This is a structure in which the roll chock 11 is pushed from one side of the cross head when the cross angle is increased, and is pushed from the other side of the cross head when the cross angle is reduced. Therefore, the position of the roll chock 11 is within the clearance d. It is because it is moving in.
[0014]
FIG. 7 shows the differential load generated when the cross angle is reduced by 15000 [kN] at the cross angle change test. It can be seen that the differential load shown in FIG. 7 varies depending on the cross angle changing direction from the previously set cross angle even at the same cross angle.
[0015]
The results of FIGS. 6 and 7 show that a slight variation in the position of the chock within the clearance d shown in FIGS. 3 and 5 affects the differential load during leveling zero adjustment. That is, the difference load at the time of leveling zero adjustment includes an error by the amount that the position of the chock fluctuates within the clearance d. According to the results of FIG. 7, even if the cross angle is 0 °, if the cross angle is once increased or decreased and returned to 0 °, the error in the position of the chock is as shown in FIG. As a result of the occurrence of 0.7 mm, an error of about 50 [kN] occurs in the differential load between the operator side and the drive side. Incidentally, the leveling zero-adjusting oil column length difference conversion error corresponding to this is 60 [μm].
[0016]
The present invention has been made in view of the conventional problems described above, and it is an object of the present invention to provide a technique for improving the accuracy of the zero reduction and leveling zero adjustment.
[0017]
[Means for Solving the Problems]
The present invention relates to a zero adjustment method of a rolling mill, wherein the upper work roll and the upper backup roll are brought into contact with each other, the lower work roll and the lower backup roll are brought into contact with each other, and the upper and lower work rolls are brought into contact with each other. The above-mentioned problem is solved by stopping the rotation and performing leveling zero adjustment.
[0018]
The present invention relates to a leveling zero adjustment method in which the rotation of a work roll of a rolling mill is stopped. As shown in FIG. Is stabilized at the offset position stuck to the entry side crosshead 12 (the entry side and the exit side are the upstream side in the direction of the material to be rolled and the downstream side is the exit side). Before, the upper work rolls 6 and 7 are not in contact, the upper work roll 6 and the upper backup roll 5 are in contact, the lower work roll 7 and the lower backup roll 8 are in contact, and the upper and lower work rolls are tightened Rotate the work rolls 6 and 7 without applying a load, and between the upper work roll 5 and the upper backup roll 6 and the lower work roll. Then, by applying a repulsive force between the lower backup rolls 8 in the d direction shown in FIG. 5, the work roll chock and the backup roll chock are respectively moved to the offset position, and then the rotation of the work roll is stopped to perform the leveling zero tone. Thus, the differential load error due to the chock position within the clearance is reduced, and the accuracy of leveling zero tone is improved. In the case of a cross roll rolling machine, the above description is preferably performed in a state where the cross angle is 0 °, and at this time, the force is not positively applied to the bender that deflects the work roll in the central axis direction. It is preferable to set a balance state in which a slight force, for example, 50 [kN] is applied to the operator side, the drive side, and one side.
[0019]
According to the present invention, since the chock position within the clearance is stabilized at the offset position at the time of leveling zero adjustment when the rotation of the work roll is stopped, it is not affected by the differential load error due to the chock position, and the accuracy is high. It becomes possible to set the gap between rolls in a parallel state.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings.
[0021]
This embodiment performs zero adjustment according to the flowchart shown in FIG. 9, taking as an example a case where it is carried out for a general hot finishing mill as shown in FIG.
[0022]
As described above, when the work rolls 6 and 7 are rearranged, zero reduction and leveling zero adjustment are performed. In step 100 of FIG. 9, after completion of the work roll reassignment, the loader load is reset in step 110 after the bender is brought into a balanced state.
[0023]
In step 120, the hydraulic cylinders 1 and 2 shown in FIG. 8 are raised by 1 mm, for example, so that the upper and lower work rolls are not in contact with each other.
[0024]
In step 130, it is confirmed that the cross angle is 0 °. If the cross angle is not zero, the crossing angle is changed to 0 °, and then the flow proceeds to step 150.
[0025]
In step 150, the upper and lower work rolls 6 and 7 are rotated without being in contact with each other. At this time, the backup rolls 5 and 8 generate heat due to friction caused by contact rolling with the work rolls. However, if the roll profile is uneven, a local difference occurs, and the backup rolls 5 and 8 are in strong contact with each other. There is a case where a temperature difference is generated between the portion that is not and the portion that is not so, and the work rolls 6 and 7 may be distorted by heat.
[0026]
Therefore, after taking measures such as injecting cooling water to the work rolls 6 and 7 in order to prevent such thermal deformation, the work rolls 6 and 7 are rotated and, for example, when 30 seconds have elapsed from the start of rotation. Proceed to step 160.
[0027]
In step 160, it is detected whether the upper and lower backup rolls are rotating. This is done to check for slipping. If it is rotating, it is determined that a repulsive force is acting between the upper backup roll 5 and the upper work roll 6, and the lower work roll 7 and the lower backup roll 8 as shown in FIG. Stop roll rotation. If not, go to Step 170, stop the sequence, and return to Step 100.
[0028]
In step 190, the hydraulic pressure reduction cylinders 1 and 2 are lowered by the reduction load control until the upper and lower work roll tightening loads (the total detected load of the operator side load cell 3 and the drive side load cell 4) reaches 15000 ± 50 kN.
[0029]
When this is completed, the process goes to step 200, and leveling zero adjustment is performed when the load difference between the operator side load cell 3 and the drive side load cell 4 is 500 kN or more, for example, when the pressure is reduced to 15000 kN. Leveling zero adjustment is performed by adjusting the oil column length of either the operator-side or the drive-side hydraulic cylinder so that the difference in detected load between the operator-side load cell 3 and the drive-side load cell 4 is reduced. For example, when the detected load of the operator side load cell 3 is larger than the detected load of the drive side load cell 4, the oil column length of the hydraulic pressure reduction cylinder on the operator side is shortened or the oil column length of the hydraulic pressure reduction cylinder on the drive side is increased. The fine adjustment operation is performed until the load difference between the operator side load cell 3 and the drive side load cell 4 becomes less than 500 kN.
[0030]
When leveling zero adjustment is performed, the tightening load may have deviated from the aforementioned 15000 ± 50 kN. Therefore, the process returns to step 190, and a series of subsequent sequences are performed again. Zero adjustment is completed so that the difference between the upper and lower work roll tightening loads (the total detected load of the operator load cell 3 and the drive load cell 4) and the detected load of the operator load cell 3 and the drive load cell 4 is within a predetermined range. And
[0031]
In FIG. 10, the dispersion | variation in the oil column difference (leveling zero tone value) of the operator side and the drive side in each stand F1-F7 of a finishing rolling mill at this time is shown. Due to subtle differences in characteristics that are invisible to each rolling mill (estimated to be due to mechanical friction between the housing and the chock and the difference in diameter distribution in the central axis direction between the upper and lower work rolls and the backup roll), FIG. As shown, the upper work roll 6 and the upper backup roll 5 are brought into contact with each other, the lower work roll 7 and the lower backup roll 8 are brought into contact with each other, and the upper and lower work rolls 6 and 7 are brought into contact with each other. After rotating in a non-rotating state, the work roll is stopped and the leveling zero adjustment is less than the case where the leveling zero adjustment is performed after the roll rotation is simply stopped. I understand that.
[0032]
As described above, the case of a hot finish rolling mill has been described as an example. However, it is clear that the present invention can be applied to a hot rough rolling mill or a cold rolling mill, and a pair cloth, a work roll single cloth, etc. The present invention is also applicable to other types of rolling mills other than so-called cross roll rolling mills. In addition, the actuator may be any one other than hydraulic and electric screws.
[0033]
【The invention's effect】
According to the present invention, the upper and lower work roll chock positions are stabilized to the originally desired offset position in a zero tone, and the differential load error due to the fluctuation of the roll chock position within the clearance between the housing 9 (or the cross heads 12 and 13) and the roll chock 11 is reduced. It is not affected, and by setting the target differential load, it is possible to set the gap between rolls in a parallel state with high accuracy, and the accuracy of zero adjustment when the roll is stopped can be improved. .
[Brief description of the drawings]
FIG. 1 is a front view showing a schematic configuration of a general hot rolling finish rolling mill. FIG. 2 is a diagram showing a relationship between a roll cross angle and a thrust coefficient. FIG. 3 is a slight cross angle error occurring in a clearance. Plan view for explaining the mechanism [Fig. 4] Diagram showing the relationship between the thrust force generated by a minute cross angle error and the differential load [Fig. 5] Side view showing the offset state of the work roll and backup roll [Fig. 6] Diagram showing the difference in the chock position due to the difference in the chock movement direction accompanying the increase and decrease of the cross angle. [Fig. 7] Diagram showing the difference in the differential load due to the difference between the cross angle and the increase and decrease directions. FIG. 9 is a side view showing the operation of the present invention by rotating the work roll. FIG. 9 is a flowchart showing the implementation procedure of the present invention. FIG. 10 is a diagram showing the zero tone effect of the present invention for each rolling mill stand. Akira]
DESCRIPTION OF SYMBOLS 1 ... Operator side hydraulic reduction cylinder 2 ... Drive side hydraulic reduction cylinder 3 ... Operator side load cell 4 ... Drive side load cell 5 ... Upper backup roll 6 ... Upper work roll 7 ... Lower work roll 8 ... Lower backup roll 9 ... Housing 10 ... Roll 11 ... Roll chock 12 ... Ingress crosshead 13 ... Exit crosshead

Claims (1)

In the zero adjustment method of the rolling mill,
Rotate the upper work roll and the upper backup roll in contact with each other, rotate the lower work roll and lower backup roll in contact with each other and keep the upper and lower work rolls from contacting each other, and then stop the rotation of the work roll and perform zero leveling. A zero-tuning method for a rolling mill.

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