JPS6029564B2 - Plate crown control method and device in continuous rolling mill - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for improving thickness distribution in the width direction of a plate when rolling a plate in a continuous rolling mill such as a hot continuous rolling mill or a cold continuous rolling mill
The present invention relates to a plate crown control method and apparatus used in the field of controlling the plate flatness (plate shape) and controlling the plate flatness (plate shape).

Conventionally, as a method of controlling the plate crown and shape in a continuous rolling mill, there is a method in which an initial crown or stepped portion is previously provided on the roll itself of each stand to obtain a desired plate crown.

However, this requires an optimal initial crown or stepped length depending on the strip width or rolling conditions, and the rolls must be replaced each time, resulting in frequent roll replacements and lower operating rates. There are drawbacks. Furthermore, roll wear and thermal expansion are unavoidable due to excessive rolling, and in order to obtain a stable plate crown and shape, some kind of device must be used to correct this. Conventionally, a roll pending device has been used as a device for this purpose. However, in conventional roll pending devices, the end of the work roll shaft is supported by a single chock, so it is not possible to apply a large pending load due to restrictions on the strength of the chock and the pending load capacity.
There was a limit to the control amount required for these corrections. Therefore,
As a means of controlling the plate crown and plate shape, a method has been considered in which the rolling load distribution of each stand is adjusted by adjusting the rolling reduction of the rolling mill.

This method is effective for adjusting the crown of the plate, but changing the rolling load affects the plate thickness accuracy and plate temperature, and it is necessary to determine the schedule depending on the rolling conditions, making it difficult to adjust the optimal value. It's quite difficult to do. In addition, changing the plate crown in order to control the plate crown causes deterioration of the plate shape, and in continuous rolling mills, if the shape between the stands becomes disordered, it becomes impossible to thread the plate, and during operation. may cause trouble.

In addition, it is necessary to keep the shape of the plate flat in the plate rolled on the final stand, and it is hardly possible to control the plate crown using only the final finishing stand. Conventionally, the characteristics showing the relationship between plate crown change and plate shape have not been fully understood, and plate crown control in continuous rolling mills has not been carried out effectively.

Conventionally, when controlling the plate crown in a continuous hot rolling mill,
If the plate crown changes significantly on the final finishing stand,
In order to deteriorate the shape of the sheet, it is known to change the crown of the sheet in a rough rolling mill or a pre-stage stand, and to control the shape in the final stand.

However, when the plate crown is controlled by the roll pending device of the front stage stand, even if the stand is controlled individually or each stand is individually controlled, the controlled plate crown is
It has been confirmed through theoretical analysis and experiments that this is canceled out by the influence of the stands downstream from the controlled stand, and that the amount of control at the exit side of the final stand is almost eliminated. Furthermore, the above-mentioned discrete control also poses a problem in that the number of control systems must be increased. The present invention experimentally determines in detail the characteristics that indicate the relationship between plate crown change and plate shape, thereby ascertaining the amount by which the plate crown can be changed without deteriorating the plate shape in each stand, and controlling the plate crown. This was done with the purpose of increasing the volume and performing effective plate crown control with a relatively simple control system.In a continuous rolling mill, the pressure V supplied to the roll pending devices of multiple stands was This invention relates to a method and apparatus for controlling plate crown in a continuous rolling mill, which is characterized in that pressure is controlled in the same direction while maintaining a constant ratio.

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

Basically, the present invention provides a double chock work roll pending device as a plate crown control device in a plurality of stands before the intermediate or final stand of a continuous rolling mill, and interlocks the pending devices to operate the plurality of stands. The objective is to increase the range of plate crown control that can be controlled in the same direction without deteriorating the plate shape.

Figure 1 is a conceptual diagram showing the relationship between plate crown change and plate shape. The mechanical axis shows the ratio crown %, which is expressed as a percentage by dividing the plate crown Cr by the plate thickness h, and the vertical axis shows the steepness, which indicates the plate shape. The (10) side shows the edge elongation of the board, and the (1) side shows the middle elongation of the board. The relationship between the change in the plate crown and the plate shape is such that when the plate crown changes, the plate shape becomes disordered as shown in FIG. 1, but there is a certain range in which the shape does not become disordered.

Here, the area where the plate shape does not change even if the ratio crown % (plate crown) changes (Imajin) is defined as the absolute shape zone area, and tolerance values C and D are set for the disorder of the plate shape. In this case, the maximum allowable change in plate crown is △Cq + △Harm2
If it is determined from 10△Cr2' and this region is defined as the shape-practical dead zone region, the upper reading vs. dead zone region is the region of AB in Figure 1, and the practical dead zone region is the region of C'〇 in Figure 1. It is an area.

In addition, both of the above-mentioned dead zone regions are collectively referred to as a shape dead zone region. The present invention aims to increase the plate crown control amount by expanding this shape dead zone region.

FIG. 2 shows a double chock work roll pending device as a device for controlling the sheet crown. Two double chock work roll pending devices 7 are installed at each shaft end of the upper work roll and the lower work roll 2. Work roll chocks 3 and 4 are arranged, and the inner chock 3 is supported via an inner bearing 5, and the outer chock 4 is supported via an outer bearing 6, respectively, and the inner chock 3 and the outer chock 4 are supported by hydraulic or hydraulic pressure. The roll pending moment can be changed by increasing or decreasing the load applied to the inner chock 3 and the load applied to the outer chock 4 so that a large plate crown control amount can be obtained. Figure 3 shows an example of the device of the present invention, showing two upstream stands than the intermediate or final stand.
The above-mentioned double chock work roll pending devices 7 are installed in two or more stands, and these double chock work roll pending devices 7 are interlocked by pressure control in the same direction and at a constant ratio for each stand. .

That is, a line 8 for supplying pressure oil from a hydraulic source is connected to each double chock work roll pending device 7, a pressure regulator 9 is provided in the middle of the line 8, and a line pressure regulator 10 and an electromagnetic A valve 11 is provided, and each pressure regulator 9 is operated to perform each double choke work.
A pressure setting device 12 is provided to adjust the pressure to the bending device 7, and the pressure is calculated from control information (for example, plate width, plate thickness, and plate deformation resistance) 14 so that plate crown control can be performed in the shape dead zone region. Controller (computer) 13
A pressure ratio for each stand is set in each pressure setting device 12 based on a command from the controller 13, and based on the set ratio, the pressure setting device 12 controls the pressure regulator 9.
is operated, and the solenoid valve 11 is operated based on a command from the controller 13, so that the pressures of the roll pending devices 7 of the plurality of stands are operated in the same direction while maintaining a constant ratio. Here, select "Lower multiple stands".
While maintaining the pressure of the bending device 7 at a constant ratio.''
is the work roll pending load of each stand,
For example, if the ratio is set to 1, such as 50 tons all the time, or if the work roll pending load is set to 100 tons on one stand and 50 tons on another stand, This means that the set ratio remains constant without changing, and "in the same direction" means that either the work roll pending load that increases the plate crown or the work roll pending load that decreases the plate crown is applied. This means that each stand is unified. Therefore, in the present invention, when the work roll pending load is set in multiple stands, the ratio of the pending loads in the multiple stands is not changed, and whether the plate crown is made larger or smaller in each stand is unified. rolling. Note that S, to S6 are the first to sixth stands. The principle of the method of the present invention is as shown in FIGS. 4 and 5.

When performing plate crown control using a single stand double choke work roll pending device, if the plate crown is not controlled within the shape dead zone region, the plate shape will be disturbed. If the i-stand performs increase pending 1 and decrease bending D to control the plate crown, the plate crown control ability with the i-stand will be the ratio crown three harms three, which is the maximum amount of plate crown control that can be controlled without disturbing the shape. The value (o control range) is the shape dead zone region, which is the three harms, and when controlling the plate crown with the j stand alone, it cannot exceed the shape dead zone area, so inevitably the plate crown control amount is also fixed. come. In this regard, if a multi-stand double chock work roll pending device is installed and the roll pending devices are linked to perform plate crown control, the plate crown control ability and control range will be expanded, and the apparent shape-unfavorable zone area will also be improved. To increase. That is, the i-1 stand and the i-stand are controlled in the same pending mode, that is, the mode in which the pressure of the work roll pending cylinder is sequentially changed according to the size of the pending load is made the same for multiple stands; -1 stand performs increase pending 1, i-stand also performs increase pending 1, and i-1 stand performs decrease bending D. As shown in Figure 5 A, the board crown control ability of the i-stand is now expanded compared to the case of a single stand, and the control ability is now;
It can be expanded to On the other hand, the shape dead zone area, ie, the maximum control range of the plate crown, can be apparently significantly expanded compared to control using a single stand as shown in FIG. This is because, as shown in FIG. 5, the standard for the shape dead zone region starts from the plate crown control amount of the i-1 stand. The circle mark in Figure 5 is double chock work. The plate crown control range by the curve bending device, the x mark is the shape dead zone. Based on the above principle, the present invention controls the plate crown by interlocking a plurality of stands in the same direction at a constant ratio as shown in FIG.

A controller (computer) 13 calculates the pressure according to the plate crown control amount to be controlled from the control information 14, and sets the ratio of each stand.

Next, the pressure adjustment valve 9 is operated by the pressure setting device 12 for each stand based on the set ratio, and the double choke work roll pending device 7 provided with a plurality of stands is controlled by the solenoid valve 11. The pressure is controlled and interlocked while maintaining a constant ratio, and each stand performs plate crown control in the same direction. That is, as described above, in a state in which the ratio of pending loads set in the double chock work roll pending device 7 of multiple stands is fixed and the pending loads of each stand are controlled simultaneously, the pending load increases the plate crown in each stand. Plate crown control is performed using either the load or the pending load that reduces the plate crown. An example of the state of this plate crown control is shown in FIG. FIG. 6 shows, for example, in the first stand S to the fourth stand S4, double choke work roll pending devices are installed and interlocked in the second stand S2, third stand S3, and fourth stand S4, and the first If the pending load is 5 peaks f at stand S, and the ratio f is -6 at the 3 stands after the second stand, then in the case of sail, 5
This shows the plate crown change due to the motion control of the double chock work roll bending device when the ratio is set to 1 in each case of 10 f and 10 f, and for mild steel with a plate width of 1235 mm. The test was carried out under the conditions shown in Table 1. Table 1 Each solid line in Figure 6 above shows the change in the plate crown when the pending loads in the second to fourth three stands S2, S3, and S4 are held constant, and the broken lines indicate the pending load for each stand. This shows the changes in the plate crown when the load is changed.

As can be seen from FIG. 6, for example, when the pending load of the second to fourth stands S2, S3, and S4 is controlled to 10 dishes, and when the pending load of -6 blood is controlled, the second stand S2 When plate crown control is performed by applying a pending load of lowf at When control is performed by applying a pending load of 10 blood in the third stand S3, the influence of the change in the plate crown on the inlet side appears as a change in the plate crown on the outlet side with a value of ΔCr4. This increase is added to the control range obtained with a single stand, resulting in the effect of expanding the plate crown control range by interlocking the double chock work roll pending devices of multiple stands, as shown in Figure 5. In this sense, interlocking control of the double chock work roll pending device is an effective means for expanding the plate crown control range. The controller 13 performs logic calculations as shown in FIG. 5 above. At this time, as explained in the principle of FIG. 5, the exit plate crown of the second stand S2 is controlled by the double chock work roll pending device 7 during rolling in the third stand S3, and the fourth stand is further controlled in conjunction with the double chock work roll pending device 7. Plate crown control is performed by the double choke work roll pending device 7 of stand S4. In this way, by controlling the double chock work roll bending devices 7 of multiple stands in conjunction with each other at a constant ratio, it is possible to obtain a large amount of plate crown control without disturbing the shape of the stand before the final stand. I can do it. In other words, - If you link work roll pending in multiple stands,
By utilizing the effect that the plate crown controlled in the previous stand remains as a history in the next stand, the plate crown of the next stand can be greatly controlled. The present invention aims to control the pending status of multiple stands at a constant ratio in the same direction in order to achieve these effects using simple logic. On the other hand, in order to control the plate crown without disturbing the shape, there are several Interlocking control using a stand is effective. still,
When controlling the pressure at a constant ratio with multiple stands that perform plate crown control, it is possible to select the plate crown control stands in advance and keep the pressure control ratio constant, or to adjust the pressure ratio of each plate crown control stand. The pressure may be changed depending on the rolling conditions, etc., or the pressure of the oil supply line to multiple stands may be adjusted. Various methods can be considered.

As described above, according to the present invention, the double chock work roll pending devices installed in multiple stands of a continuous rolling mill are interlocked to control pressure while maintaining a constant ratio in the same direction. The amount of plate crown control can be increased without expanding and disturbing the shape, and the control is simple.Furthermore, the plate crown can be controlled with the same plate shape, which improves quality, yield, and operation rate. It is possible to achieve excellent effects such as:

[Brief explanation of the drawing]

Figure 1 shows the relationship between plate crown change and plate shape, Figure 2
The figure is an explanatory diagram of the double chock work roll pending device adopted in the present invention, Figure 3 is a schematic diagram showing an example of the device of the present invention, and Figure 4 is when performing plate crown control without disturbing the shape with a single stand. FIG. 5A and FIG. 5B are principle diagrams of the present invention, and FIG. 6 is an example diagram showing changes in plate crown by interlocking control of a three-stand double chock work roll pending device. 1... Upper work roll, 2... Lower work roll, 3, 4
...Work roll chock, 7...Double chock work roll pending device, 9...Pressure regulator, 10...Line pressure regulator, 11...Solenoid valve, 12. ...Pressure setting device, 13...
controller. Figure 1 Figure 4 Figure 2 Figure 3 Figure 5 Figure 6

Claims (1)

[Claims] 1. A continuous rolling mill characterized in that the pressures supplied to the roll bending devices of a plurality of stands are controlled and interlocked in the same direction while maintaining a constant ratio. Plate crown control method. 2. In a continuous rolling mill, roll bending devices are installed in multiple stands upstream of the final stand, and pressure supply lines are connected to each bending device in succession so that each bending device is linked and operates in the same direction. It is equipped with a pressure control device that controls the pressure supplied to the bending device in the same direction while maintaining a constant ratio, and calculates the pressure and sends control commands to the pressure control device so that plate crown control can be performed in an area that does not disturb the plate shape. 1. A plate crown control device for a continuous rolling mill, characterized in that it is equipped with a control device that provides the following.