JP3541973B2 - Edge drop control method in cold rolling - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to an edge drop control method in cold rolling, and particularly to stabilizing control.
[0002]
[Prior art]
In cold rolling, it is known that a sharp decrease in the thickness called edge drop occurs at both width end portions of the sheet material.
If the edge drop amount is large, a large amount of trimming is required to secure a desired plate thickness quality. As a result, the yield and the production efficiency are reduced.
[0003]
As a measure for improving such edge drop, for example, in Japanese Patent Publication No. 2-34364, at least one end of a pair of work rolls is subjected to taper grinding, and this tapered grinding area is positioned at both ends of the material to be rolled. by improving the geometry of, the roll formic cap rolled Te, edge drop reduction is advantageously achieved, yet when applied to tandem cold rolling mill train, the tapered grinding zone at least a first stand It is disclosed that it is advantageous to arrange a rolling mill incorporating a work roll equipped with a work roll, and to arrange at least a rolling mill incorporating a work roll having a plain shape at least on the exit final stand.
[0004]
[Problems to be solved by the invention]
However, conventionally, when the output of the edge drop meter on the tandem rolling mill row side is used to shift the work roll in the same coil and constantly control the edge drop, when the shifting direction is reversed, the shift device is not used. There was a problem that the shift could not be executed smoothly due to backlash, and vibration occurred and stable control could not be performed.
The present invention advantageously solves the above-mentioned problem. When shifting a work roll in cold rolling, the direction of the force required for the shift is kept constant irrespective of the shift direction. The edge in cold rolling can stably produce cold rolled strip products with a small thickness deviation across the sheet width by stabilizing control by eliminating occurrence of The purpose is to propose a drop control method.
[0005]
[Means for Solving the Problems]
That is, the present invention, a pair of work rolls subjected to tapered grinding on one side end of the roll cylinder, superimposed vertically in an alternate arrangement of the one side end, and incorporated into the mill housing so as to be shiftable in the roll axis direction, In the edge drop control method in cold rolling, which comprises shifting the work rolls appropriately while rolling while positioning the tapered grinding area at both side ends of the material to be rolled,
The upper and lower work rolls are crossed with each other on a plane parallel to the surface to be rolled, and the cross angle is always maintained at an angle α satisfying the following equation (1). This is an edge drop control method in cold rolling, wherein a shift speed is set in proportion to a peripheral speed.
α> tan ^-1 (Vs _{ab, max} / Vr _stea ) --- (1)
Vs _ab = min ｛Vs _{ab, max} / Vr _stea · Vr, Vs _{ab, max} ｝ --- (2)
Here, Vs _{ab, max} : the absolute value of the upper limit of the work roll shift speed for executing the edge drop control (mpm)
Vr _stea : Roll speed in standard rolling condition (mpm)
Vs _ab : Absolute value of work roll shift speed (mpm)
Vr: Roll peripheral speed (mpm)
α: Cross angle (°)
[0006]
Hereinafter, the present invention will be described specifically.
FIG. 1 shows a rolling mill suitable for carrying out the present invention, together with its control system.
In the figure, reference numeral 1 denotes a material to be rolled. Reference numeral 10 denotes the whole rolling mill, 11 denotes a work roll, and 12 denotes a reinforcing roll. Furthermore, 21 is a work roll shift control device, 22 is a work roll cross control device, 23 is a shift speed setting device, and 24 is a cross angle setting device.
Now, in the above-mentioned apparatus, one end of the work roll 11 of the rolling mill 10 is subjected to taper grinding, and the one end is alternately arranged so as to be vertically overlapped and incorporated into a mill housing. Then, the tapered grinding area is located at both ends of the material 1 to be rolled, and the upper and lower rolls are shifted by the shift control device 21 in the sheet width direction. Further, the work rolls 11, the cross control device 22 for moving the chocks in the lateral direction opposite to the rolling direction, relative to the rolls 12 and the material 1 to be rolled, Ru are cross reversed vertically.
[0007]
FIG. 2 shows the relationship between the shift speed ratio Vs / Vr (Vs: shift speed, Vr: roll peripheral speed) of the work roll and the force Fs required for the shift when the cross angle is set to 0 °. Show.
Under this condition, the work roll is shifted against both the reinforcing roll and the material to be rolled, so that the direction of the shift matches the direction of the force required for the shift. The direction of the required force is also negative.
[0008]
Next, FIG. 3 shows the relationship between the shift speed ratio Vs / Vr of the work roll and the force Fs required for the shift when the cross angle is set to 0.1 °.
Under this condition, when the shift speed ratio is small, the force required for the shift acts in the negative direction regardless of whether the shift is performed in the positive or negative direction. However, when the shift speed ratio increases in the forward direction, the force required for the shift also changes in the forward direction.
[0009]
Next, FIG. 4 shows the result of investigation on the magnitude of the shift speed ratio and the mechanism for generating the force required for the shift when the cross angle is set to α °.
Regardless of whether the shift direction is positive or negative (a and d in the figures), when the shift speed ratio is small, the slip between the work roll and the reinforcing roll caused by the cross angle of the work roll = α ° is large, and the work roll is reinforced. Since a large force is received in the negative direction from the roll, the force required for the shift is negative as a whole, though a force is received in the positive direction from the material to be rolled.
If the shift speed ratio Vs / Vr is set to a large value up to tanα, the amount of slip between the work roll and the reinforcing roll caused by the cross angle becomes equal to the amount of slip caused by the shift, and there is no slip between the work roll and the reinforcing roll. , No force is generated. As a result, the force required for the shift is only the force in the direction opposite to the shift direction received from the material to be rolled, and is a small force in the forward direction.
Furthermore, when the shift speed ratio is increased, the amount of slip caused by the shift between the work roll and the reinforcing roll is larger than the amount of slip caused by crossing the work roll, and the work roll is also moved in the opposite direction to the shift direction from the reinforcing roll. Therefore, the force required for the shift is a large force in the positive direction.
[0010]
Conversely, when the shift speed ratio Vs / Vr is -tanα, the amount of slip between the work roll and the material to be rolled due to the cross angle is equal to the amount of slip generated due to the shift, and the width between the work roll and the material to be rolled is equal. No slip occurs in the direction, so no force is generated. As a result, the force required for the shift is only from the reinforcing roll.
Further, when the shift speed ratio is increased in the negative direction, a force is also received in the negative direction from the material to be rolled, so that the force required for the shift is a large force in the negative direction.
[0011]
From the above, regardless of the direction of the force required for the shift, regardless of the direction in which the shift is performed, the following expression is satisfied so that the force received by the work roll from the reinforcing roll is always in the negative direction in order to always make the direction negative. That is, the cross angle of the work roll may be set to the angle α.
_{^{α> tan -1 (Vs ab /}} Vr)
Where Vs _ab : absolute value of shift speed (mpm)
Vr: Roll peripheral speed (mpm)
[0012]
However, if the cross angle is changed so as to satisfy the above relational expression each time the work roll is shifted, extremely complicated control such as controlling the shift and the cross in conjunction with each other is always required. However, it is practically impossible because the shape change of the rolled material due to the change of the cross angle must be considered.
In addition, setting the cross angle α so that the above formula is always satisfied means that the slip between the work roll and the reinforcing roll is large, and the wear of both rolls becomes severe, so that the life is shortened and the life can be shortened. Can not.
[0013]
Therefore, in the present invention, in the high-speed reference rolling state, the angle shown in the following equation (1) is set as the cross angle so as to satisfy the above equation only while the edge drop control is performed by shifting the work roll. In addition, the influence on the direction of the force required for the shift of the roll peripheral speed is reduced by changing the shift speed of the work roll in proportion to the roll peripheral speed according to the following equation (2).
In addition, about the speed more than a reference rolling speed, it will shift by the maximum value of work roll shift speed: Vsab _{, max} .
α> tan ^-1 (Vs _{ab, max} / Vr _stea ) --- (1)
Vs _ab = min ｛Vs _{ab, max} / Vr _stea · Vr, Vs _{ab, max} ｝ --- (2)
Here, Vs _{ab, max} : the absolute value of the upper limit of the work roll shift speed for executing the edge drop control (mpm)
Vr _stea : Roll speed in standard rolling condition (mpm)
[0014]
[Action]
As described above, if the cross angle and the shift speed of the work roll are set according to the present invention, a thrust force in a certain direction can be generated on the work roll regardless of the rolling speed. Instability of control and deterioration of position accuracy can be effectively avoided, and as a result, edge drop can be suppressed over the entire length of the coil.
[0015]
【Example】
A steel plate having a width of 1100 mm and a thickness of 2.6 mm was cold-rolled to 0.3 mm by a 5-stand cold tandem rolling mill line. In the above-mentioned cold tandem rolling mill row, in the first stand, as the work roll, a work roll in which one end of a roll drum was tapered was used, and a shift control device and a cross control device for the roll were arranged. .
In the above cold rolling, when performing feedback control by the edge drop meter on the delivery side,
(A) When the work roll is shifted at the cross angle = 0 ° (conventional example),
(B) From the maximum value of the shift speed of the work roll used for feedback control (Vs _max : 2 mm / s) and the maximum value of the roll peripheral speed (Vr _stea : 150 mpm), the cross angle is set by the following equation according to the above (1). (Α = 0.05 °) and the work roll shift speed is always shifted to the maximum value (Vs _max : 2 mm / s) (comparative example)
Vs _max : 2 mm / s, Vr _stea : 150 mpm
α> tan ^-1 (Vs _{ab, max} / V _stea ) = tan ^-1 (0.12 / 150) ≒ 0.046
∴ α = 0.05 (°)
(C) From the maximum value of the shift speed of the work roll used for feedback control (Vs _max : 2 mm / s) and the maximum value of the roll peripheral speed (Vr _stea : 150 mpm), determine the cross angle in the same manner as in (b) above. Setting (α = 0.05 °), rolling was performed for each case (invention example) in which the shift speed of the work roll was shifted in proportion to the roll peripheral speed (shift speed: 0 to 2 mm / s).
[0016]
FIG. 5 shows the change target value (broken line) and the actual value (solid line) of the shift position for the case where the rolling speed is low or high.
In the case of the conventional example, even if the rolling speed is low or high, there is a region where the force required for the shift is not generated due to backlash of the shift device every time the shift direction is reversed, and the control becomes unstable, During this time, since the work rolls are not substantially shifted, there is a delay in control.
Also, in the case of the comparative example, at a high rolling speed, the thrust force always acts in a fixed direction, so that the control is stable and there is no delay. However, at a low rolling speed, the direction of the force required for the shift changes with the change of the shift direction, so that good control could not be performed.
On the other hand, in the case of the invention example, the shift position can be stably controlled without delay because the thrust force is always applied to the work roll in a constant direction regardless of whether the rolling speed is low or high. As a result, accurate edge drop control was achieved over the entire length of the coil.
[0017]
【The invention's effect】
Thus, according to the present invention, in cold rolling, regardless of the rolling speed, since the thrust force is always applied to the work roll in a fixed direction, the shift position can be controlled stably without delay, Since accurate edge drop control can always be performed, the amount of edge drop can be guaranteed over the entire length of the coil, and a cold rolled strip product having a small thickness deviation in the sheet width direction can be stably manufactured.
[Brief description of the drawings]
FIG. 1 is a diagram showing a rolling mill suitable for use in the embodiment of the present invention, together with a control system thereof.
FIG. 2 is a diagram showing a relationship between a shift speed ratio and a force required for shifting when a work roll is not crossed.
FIG. 3 is a diagram illustrating a relationship between a shift speed and a force required for shifting when a work roll is crossed.
FIG. 4 is a diagram showing a mechanism for generating a thrust force in a work roll.
FIG. 5 is a diagram showing a change target value and an actual value of a shift position when the rolling speed is low and high.
[Explanation of symbols]
1 Rolled material
10 Rolling mill
11 Work roll
12 Reinforcement roll
21 Shift control device
22 Cross control device
23 Shift speed setting device
24 Cross angle setting device

Claims (1)

A pair of work rolls having tapered grinding on one end of the roll cylinder are vertically stacked in an alternate arrangement of the one end, and incorporated in a mill housing so as to be shiftable in the roll axis direction, thereby covering the tapered grinding area. In the edge drop control method in cold rolling, which involves shifting the work rolls appropriately while being positioned at both side ends of the rolled material,
The upper and lower work rolls are crossed with each other on a plane parallel to the surface to be rolled, and the cross angle is always maintained at an angle α satisfying the following equation (1). An edge drop control method in cold rolling, wherein a shift speed is set in proportion to a peripheral speed.
α> tan ^-1 (Vs _{ab, max} / Vr _stea ) --- (1)
Vs _ab = min ｛Vs _{ab, max} / Vr _stea · Vr, Vs _{ab, max} ｝ --- (2)
Here, Vs _{ab, max} : the absolute value of the upper limit of the work roll shift speed for executing the edge drop control (mpm)
Vr _stea : Roll speed in standard rolling condition (mpm)
Vs _ab : Absolute value of work roll shift speed (mpm)
Vr: Roll peripheral speed (mpm)
α: Cross angle (°)

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