JPH0587335B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to an electric rolling down device with a large stroke and low speed, which is mainly used for initial setting of a roll gap, and a device with a small stroke and high speed, which is mainly used to control plate thickness. The present invention relates to a roll gap control method in a rolling mill equipped with a hydraulic rolling device.

(Prior Art) FIG. 4 shows a schematic configuration of a roll gap control device for a conventional rolling mill. In the figure, 1
are rolling mills, with work rolls 21, 31, and
It has an upper housing 2 and a lower housing 3, which are provided with intermediate rolls 22, 32 and back-up rolls 23, 33. The upper housing 2 is mounted to be movable up and down along the column 4, and is raised and lowered by an electric lowering motor 5 via a screw mechanism (not shown).

Therefore, the roll gap (work roll 2
1 and 31) is set by raising or lowering the upper housing 2 by the electric lowering motor 5 via the motor drive control circuit 6 based on a predetermined command signal.

Next, the lower housing 3 is provided with a wedge 7 that allows the lower work roll 31 to be rapidly opened and closed relative to the work roll 21 of the upper housing 2, and the wedge 7 is connected to and driven by a hydraulic cylinder 8. The amount of movement of the wedge 7 is detected by a wedge position detector 9 and input to an automatic plate thickness control circuit 10. Therefore, plate thickness control is performed by controlling the position of the wedge 7 using the hydraulic cylinder 8 and opening and closing the roll gap. In this case, the electric reduction motor 5 has a slow response speed to the opening/closing operation of the roll gap, so it is not used for automatic plate thickness control (hereinafter referred to as AGC).

(Problems to be solved by the invention) In conventional rolling mills, when a so-called plate breakage occurs, the wedge is rapidly moved in the opening direction.
Opening the roll gap prevents the wedge from getting caught in the rolls of the rolling mill, but if the AGC results show that a plate break occurs when the wedge is near its opening limit, it will not work even if the wedge moves in the opening direction. The roll gap cannot be opened sufficiently, causing it to get caught in the rolls of the rolling mill. As a result, the rolls may be burnt in the rolling mill, and it takes time to repair them, resulting in a significant drop in productivity.

Furthermore, near the opening or closing limit of the wedge,
If the AGC control output is large, the hydraulic cylinder will reach the end of its stroke, which will prevent the AGC from functioning satisfactorily and reduce plate thickness accuracy and product quality.

(Means for Solving the Problems) In the roll gap control method for a rolling mill according to the present invention, when the wedge reaches a certain predetermined limit value,
By driving the electric lowering device while executing AGC, the position of the hydraulic lowering device is corrected to near the neutral point.

Here, the above-mentioned limit value means the limit wedge position that can function satisfactorily when cutting a board.

Note that AGC can also be performed using an electric lowering device while forcibly moving the hydraulic lowering device to the neutral position.

(Function) In the present invention, the roll gap can be corrected while keeping it constant by feeding back the position of the hydraulic screw down device to the electric screw down device, so the position of the wedge can always be kept within a predetermined limit value. This allows sufficient margin for the amount of wedge movement.

(Example) Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic illustration of a roll gap control device for carrying out the method of the present invention. In the figure, the fourth
The same reference numerals as those in the drawings indicate the same or corresponding parts, and the explanation will be omitted. Reference numeral 11 denotes a wedge position determiner which inputs the position signal of the wedge 7 from the wedge position detector 9, calculates it according to the flowchart shown in FIG. 2, and outputs it to the motor drive control circuit 6.
This output signal drives the electric lowering motor 5 to raise or lower the upper housing 2, thereby changing the roll gap by an appropriate amount.

Next, the flowchart shown in FIG. 2 will be explained.

When the calculation is started, the wedge position reading circuit A first reads the wedge position signal W. The determining device B determines the magnitude relationship between the limit value Wo in the wedge opening direction and the limit value Wc in the closing direction of the wedge. If Wc<W<Wo, that is,
If YES, wedge 7 is within the limit value, so nothing is executed. Moreover, if W≦Wc or W≧
When Wo, that is, NO, the wedge 7 is outside the limit value, so the electric lowering device 5 is driven at C.

Next, when it is determined by the judgment device D that the wedge 7 has moved to the neutral position, the electric lowering device 5 is stopped at the judgment device E. F is a decision device for continuation of calculation.

Next, FIG. 3 is a timing chart of the position of the wedge, the electric lowering motor, and the amount of movement of the roll gap. The horizontal axis is the time axis, and the vertical axis shows the wedge movement position, motor status, and roll gap movement amount, respectively.

In the case of the wedge position timing chart, the opening limit indicates the end of the wedge's stroke in the opening direction, and the closing limit indicates the end of its stroke in the closing direction. The opening direction limit value Wo is the limit at which the roll gap can be opened effectively during plate cutting, and is also the limit value for making the AGC function effectively. Close direction limit value Wc
is the limit value for making AGC function effectively.

In the case of the timing chart of the electric reduction motor,
An upward movement indicates that the motor is rotating in the opening direction of the roll gap, and a downward movement indicates that the motor is rotating in the closing direction.

The operation of this embodiment device will be explained with reference to the timing chart shown in FIG.

(1) Wedge 7 exhibits the behavior shown in Figure 3 due to AGC. Until time _t1 , the position of the wedge 7 has not reached the limit value Wo or Wc, so the electric lowering motor 5 is in a stopped state. Therefore,
The roll gap also remains at its initial setting.

(2) At time _t1 , the position of the wedge 7 has reached the opening direction limit value Wo, so the electric lowering motor 5 is driven to raise the upper housing 2 at a low speed. As a result, the roll gap gradually opens.

(3) From time _t1 to _t2 , as the roll gap opens, the monitor AGC function moves the wedge 7 in the closing direction by an amount corresponding to the opening. This is because when the roll gap is opened, the thickness of the plate on the exit side of the rolling mill will naturally increase, so the monitor AGC reads the deviation value of the thickness of the plate on the exit side and issues a command to move the roll gap in the closing direction in order to thin the plate by the increased thickness. That is, this is because a command is issued to move the wedge in the closing direction.

(4) At time _t2 , when the wedge 7 reaches the neutral position, the electric lowering motor 5 is stopped, and therefore the change in roll gap is also stopped.

(5) Since Wc<W<Wo from time t ₂ to _{t 3} , the above
Condition (4) continues.

(6) At time _t3 , it is the same as (2) above.

(7) At times _t3 to _t4 , it is the same as (3) above.

(8) At time t ₄ , it is the same as (4) above.

(9) From time _t4 to _t5 , it is the same as (5) above.

(10) At time _t5 , since W=Wc has been reached, the electric lowering motor 5 lowers the upper housing 2 at a low speed. Therefore, the roll gap gradually closes.

(11) From time t ₅ to _{t 6} , the roll gap is gradually closed by the drive of the electric lowering motor 5 . monitor
The AGC function opens the wedge 7 and moves it toward the neutral position.

(12) At time _t6 , the wedge 7 has reached the neutral position, so the electric lowering motor 5 stops.

(13) After time t ₆ , the above operation is repeated.

(Effects of the Invention) As described above, according to the present invention, the position of the wedge can always be maintained with a margin in the opening direction or the closing direction, so even if a plate breakage occurs, rolling of the rolled material into the rolls can be prevented. be able to. In addition, because of this, the AGC function can be fully utilized, so the quality of the product will not be degraded.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram of a roll gap control device for implementing the method of the present invention, Fig. 2 is a flowchart of the wedge position determination device, and Fig. 3 is a timing chart of the wedge position, electric reduction motor, and roll gap movement amount. , FIG. 4 is a schematic diagram of a conventional roll gap control device. 1...Rolling mill, 2...Upper housing, 3...Lower housing, 5...Electric rolling down motor, 6...Electric motor drive control circuit, 7...Wedge, 8...Hydraulic cylinder, 9...Wedge position detection 10... automatic plate thickness control circuit, 11... wedge position determination device.

Claims (1)

[Claims] 1. In a rolling mill that is equipped with an electric rolling device that drives the housing up and down and a hydraulic rolling device that opens and closes the wedge, and that automatically controls the thickness of the roll gap, when the wedge reaches a predetermined limit value, 1. A roll gap control method for a rolling mill, comprising correcting the position of the hydraulic rolling down device to near a neutral point by driving the electric rolling down device while performing plate thickness control.