JPS61249601A - Controlling method for contact roll - Google Patents

Abstract

PURPOSE:To relieve the impact force in the stage of passing-through of the tail end and to protect bearings and rolls by predicting the timing for the passage of the tail end through the next stand from the timing when the tail end passes through the previous stand and actuating a rolling-down cylinder in the direction where a roll gap is opened. CONSTITUTION:The timing when the tail end of a rolling material 15 in the stand A passes through work rolls 2A, 3A is detected by a load cell 6A and is inputted to a load cell control panel 12 when the tail end passes through the above-mentioned work rolls. The timing is at the same time inputted to a calculator 13. The timing when the tail end passes through the stand B is calculated by the calculator 13 from the rolling speed and draft, etc. of the stand B. A command value is fed from a control panel 14 to a servocontrol mechanism 9B to actuate the rolling-down cylinder 5B in the direction for opening the gap at the point of the time before the specified time from the timing when the tail end passes through the stand B. The impact force between the work rolls is thereby relieved, by which the bearings are protected and the life thereof is extended.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Minute Hand> The present invention relates to a method for controlling contact wool in a hot strip mill among rolling equipment.

<Conventional technology> In recent hot strip mills, upper and lower work rolls and upper and lower back-up rolls are crossed in order to improve the accuracy of the plate shape, and a cross mill equipped with a highly responsive hydraulic reduction device has been developed and put into operation. are doing. When rolling using this cross mechanism, the upper and lower work rolls (
Since the upper and lower backup rolls are arranged diagonally with respect to the traveling direction of the plate material, a thrust force F is generated in the four-wheel axis direction against the reduction blade P, and the magnitude thereof is F=P・μ. (μ
. is the wear coefficient between the rolls). As a result, the cross mill is equipped with a thrust bearing mechanism.

On the other hand, currently hot strip mills are also frequently used to roll thin plates. In this case, when rolling a thin plate, the roll gap between the upper and lower work rolls may take a negative value. The roll gap 8 represented by b, g=h-P/K may take a negative value.

In addition, in this formula, g is the roll gap, h is the exit side plate thickness,
P is the reduction blade, and K is the mill constant.

This negative value is a state in which the work rolls are in contact and a load is applied, and in this state the rolled material is bitten by the four wheels. Moreover, in this state, the thrust force F described above does not become large because the contact load itself before rolling does not have a very large value.

<Problems to be Solved by the Invention> When rolling is performed in the above-mentioned roll contact state, position control is performed so that when the end of the rolled material passes between the rolls, it becomes the roll gap before rolling. , when the roll gap has a negative value, the contact load is applied to the rolls, and the impact force Pa between the rolls when the plate material disappears acts, and the final load on the rolls is the sum of the contact (final) load P and the impact load Pα. Therefore, the thrust force F at this time is F= (P
+Pa) μ. This results in a large load on the thrust bearing. If this condition occurs, the strength and life of the thrust bearing will be reduced, and it will also cause scratches and dents to occur on the roll contact surface.

Therefore, in view of the above-mentioned drawbacks, the present invention aims to reduce the impact force when the end of the rolled material is removed by rolling control, protect the thrust bearing, and prevent the occurrence of roll scratches and dents due to the impact between the rolls. The purpose is to provide a method for controlling rolls.

Means for Solving the Problems> The present invention achieves the above object by detecting the timing at which the end of the rolled material at the previous stand comes off, and detects when the end at the next stand comes off. The method is characterized in that the contact roll is operated in the direction of opening the gap at a point slightly before the calculated timing.

<Function> A hot strip mill usually consists of F-F stands, and when rolling a thin plate, all the stands do not become contact rolls, but the latter stands F and ~F6 stand become contact rolls. become. Further, since the rolled material becomes thinner as it goes to the later stage, the contact roll load also increases. Therefore, in order to reduce the impact force when the end comes off, the stand in front of the stand that will serve as the contact roll detects the timing when the end of the rolled material is pulled out, and based on that timing, the timing when the end of the rolled material is pulled off on the stand that becomes the contact roll is determined. is calculated using the rolling speed and rolling reduction ratio, and the cylinder of the stand is operated in the roll gap opening direction at - just before the calculated timing to perform the end pull-out, thereby alleviating the impact force. In this case, the value of the field gap opening is changed depending on the amount of contact roll load before rolling.

Embodiments Here, the present invention will be described in detail with reference to the drawings. In the figure, A is the front stand and B is the rear stand.

Furthermore, IA and IB are upper backup four-rules, 2A, 2B
is the upper work roll, 3A, 3B is the lower work roll, 4A
, 4B is a lower back up roll, 5A, 5B are hydraulic cylinders that control the roll gap between the upper and lower work rolls, 6A, 6B are load cells that detect the rolling blade, 7A
(1) to 7A(4), 7B(11 to 7B(4) is a glue ps mechanism for crossing the rolls, 8A(11 to
8A(4), 8B(1) to 8B(4) are cross motors, 9A and 9B are servo mechanisms that control the hydraulic cylinders, IOA, 10B is a position detector that detects the cylinder position, IIA, IIB 12 is a control panel for position detection, 12 is a load cell control panel, 13 is an arithmetic unit for calculating the timing of end removal, 14 is a control panel, and 15 is a rolled material.

Here, during rolling, the work roll 2A of the A stand, the work roll 2B between BA and B stand,
3B, the rolled material 15 is advanced between hydraulic cylinders 5A,
5B is controlled to give the rolled material 15 a predetermined rolling edge. In this case, the rolling blade is controlled by the load cell 6.
A, 6B, load cell control panel 12, computing unit 13 calculates the load, and position detection control panels 11A, 11
Since the cylinder position is output at B, the servo mechanism 9 takes these into account using the command signal from the control panel 14.
This is done by driving A and 9B.

When rolling a thin plate, use the work roll 2A.

Since 3A, 2B, and 3B are set in a contact roll state, thrust is generated as the contact load increases, and the thrust bearings receive force. In this state, A
The ends of the rolled material 15 of the stand are work wool 2A, 3A
When the load cell 6A exits, the timing is detected by the quad cell 6A, and is input to the load cell control panel 12 and the timing is input to the arithmetic unit 13. In addition, calculate the timing at which the end of the B stand will come off based on the rolling speed and reduction rate of the I and B stands! Calculate in #13@Then, at a certain point before the timing at which the end at the B stand comes off, the servo mechanism 9 is sent from the control panel 14.
A command value is sent to B, and the reduction cylinder 5B is operated in the gap opening direction. In this case, the degree of opening of the gap is changed depending on the magnitude of the load on the contact rolls before rolling, and after the end of rolling, the impact force during rolling is alleviated.

<Effects of the Invention> As explained above, according to the present invention, after the end of the previous stand, the timing after the end of the next stand is predicted based on the timing, and the operation is performed in the direction of opening the four-wheel gap at that timing. By doing so, the impact force between the work rolls is alleviated, and as a result, the generation of thrust force is eliminated, which protects the thrust bearing and extends its life, and also prevents scratches and dents on the rolls due to work roll impact. can do.

[Brief explanation of drawings]

The figure is a block diagram used in an embodiment method according to the present invention. In the figure, 2A, 2B, 3A, and 3B are work rolls, 6A, 6B are four-cells, 9A, 9B are servo mechanisms, 12 is a four-cell control panel, 13 is a computing unit, and 14 is a control panel.

Claims (1)

[Claims] In a hot strip mill, the timing at which the end of the rolled material at the previous stand comes off is detected, the time at which the end of the rolled material at the next stand comes off is calculated, and the gap is removed between the contact rolls at a point slightly before this calculated timing. A method for controlling a contact roll, characterized in that the contact roll is moved in an opening direction.