JPS6029565B2 - Plate crown in continuous rolling mill, plate shape control method and device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for rolling a plate material 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, a plate shape control method, and an apparatus used in the field of controlling the flatness (plate shape) of a plate.

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

However, this method requires an optimum initial crown or stepped length depending on the sheet width or rolling conditions, and the rolls must be replaced each time, which has the drawback of reducing operating efficiency. Moreover, roll wear occurs during the rolling process.
Thermal expansion is unavoidable, and in order to obtain a stable plate crown and shape, it is necessary to compensate for this with some kind of device. Conventionally, there is a device for this purpose. bending equipment has been used. 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 the strength of the chock and the pending load capacity. There was a limit to the amount of control required to correct this. Therefore, as a means for 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 pressure 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. Also, when changing the plate crown to control the plate crown,
As a result, the shape of the plate deteriorates, and in continuous rolling mills,
If the shape between the stands is disrupted, it becomes impossible to pass the board through, causing trouble during operation.

In addition, it is necessary to keep the shape of the plate flat in the plate rolled on the final stand, and it is almost impossible 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 effectively performed.

Also, when controlling the plate crown in a continuous hot rolling mill,
If you change the board crown significantly at the final stand at Tsujigami,
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, the controlled plate crown is canceled by the influence of the stands subsequent to the stand being controlled, even if it is controlled individually or each stand separately, and the final It has been confirmed through theoretical analysis and experiments that the control amount on the exit side of the stand is almost never lost.

In addition, the above-mentioned discrete control increases the number of control systems and creates a problem of complexity. The present invention experimentally determines in detail the characteristics that indicate the relationship between plate crown change and plate shape, and thereby grasps the range in which the plate crown can be changed without deteriorating the plate shape in each stand, and controls the plate crown. The purpose is to increase the range and maintain the increased plate crown control range to perform plate crown control without destroying the plate shape. The roll bending device is controlled in an interlocked manner by controlling the pressure in the same direction while maintaining a constant ratio, and then the roll bending device of each subsequent stand is independently controlled within the shape dead zone region of each. The present invention relates to a plate crown in a continuous rolling mill, a plate shape control method, and an apparatus.

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

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 that when the plate crown changes as shown in FIG. 1, the plate shape becomes disordered, but there is a certain range where the shape is not disordered.

Here, the area where the plate shape does not change even if the ratio crown % (plate crown) changes is defined as the absolute shape dead zone area, and tolerance values C and D are set for the disturbance of the plate shape. In this case, the maximum allowable change in plate crown is △Cr・+△
If this region is defined as the shape practical dead zone region, the absolute dead zone region is the region AB in FIG. 1, and the practical dead zone region is the region C′D′ in FIG. It is an area. Further, the above-mentioned dead zone region is collectively referred to as a shape-insensitive zone region. The present invention basically controls the plate crown within the shape dead zone region,
A double chock work roll pending device is provided as a plate crown control device for a plurality of stands in the front stage of a continuous rolling mill, and each of the above-mentioned pending devices is moved in the same direction in order to increase the control range of plate crown on the exit side of the plurality of stands. The movement is controlled at a constant ratio to expand the apparent shape dead zone area and increase the plate crown control range, and then each subsequent stand maintains the increased plate crown control range to increase the shape dead zone area for each stand. The objective is to perform plate crown control within the plate and expand the plate crown control range without deteriorating the shape.

Here, "each pending device in the same direction" means
This refers to standardizing either the work roll pending load that increases the plate crown or the work roll pending load that reduces the plate crown for each stand. In addition, "each pending device at a fixed ratio" means that the work roll pending load of each stand is, for example,
For example, if the ratio is set to 1, such as 50 tons, in some stands the work roll pending load is set to 1.
This means that when the work roll pending load is set at a ratio such as 00 tons and 50 tons for other stands, the set ratio is kept constant without changing. Therefore, in the present invention, when the work roll pending load is set in a plurality of stands in the previous stage, the ratio of the pending load in the plurality of stands is not changed, and whether the plate crown is made larger or smaller in each stand is unified. The plate crown control range is expanded by interlocking control with the
In order to control the shape while maintaining the plate crown control range expanded by the multiple stands in the previous stage, each stand is individually controlled. Next, the principle of the present invention will be explained.

Now, when controlling the plate crown by installing a single stand double chock work roll pending device, if the plate crown is not controlled within the shape dead zone region, the plate shape will be disturbed, so as shown in Figure 2. For example, if the i-stand performs increase pending 1 and decrease bending D to control the board crown, the i-stand's board crown control ability will now be Takusan.

In addition, the maximum value of the plate crown control range that can be controlled without disturbing the shape is now three, and this plate crown control range is the first value.
This is the shape dead zone region mentioned in the figure. Therefore, when controlling the plate crown with the i-stand, the control range cannot be exceeded because it is an independent control and the control range of the plate crown is inevitably fixed. In this point,
When a double chock work roll pending device is installed in multiple stands and the pending device is moved to perform plate crown control, the plate crown control ability and control range are
Compared to this control range shown in FIG. 2, the control range is expanded as shown in FIG.

That is, if 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, i -1 stand performs increase pending 1, then i-stand also performs increase pending 1, i-1 stand performs decrease bending D, and i-stand also performs decrease bending D. As shown in Figure 3A, the plate crown control capability of the i-stand is expanded compared to the case of a single stand, and the control capability can be expanded to that of the sheep. On the other hand, the shape-unfavorable zone region, that is, the plate crown control range can be apparently expanded significantly compared to control using a single stand as shown in FIG. 3. This is because the reference for the shape unfavorable zone region starts from the plate crown control range of the i-1 stand. Figure 2,
In Fig. 3, the circle mark indicates the plate crown control range, and the cross mark indicates the shape dead zone. To explain further, it can be seen from FIG. 9 that the plate crown control range can be expanded by controlling the pending loads in the same direction while keeping the ratio of pending loads of the pending devices of a plurality of stands constant.

FIG. 9 shows, for example, in the first stand S to the fourth stand S4, the second stand S2, the third stand S3,
A double chock work roll pending device is installed on the fourth stand S4 and interlocked, and if the pending load is 5 f on the first stand S, and -6 f on the 3 stands after the second stand, then the ratio f is In the case of 5 enemies,
This figure shows plate crown changes due to interlocking control of the double chock work roll pending device when the ratio is set to 1 in each case for 10 skins, and under the conditions shown in Table 1 for mild steel with a plate width of 1235 ribs. That's what I did. Table 1 Each solid line in FIG. 9 above indicates the second to fourth stands S2.
, S3, and S4 when the pending load is kept constant, and the broken line shows the change in the plate crown when the pending load is changed for each stand.

As can be seen from FIG. 9, for example, when the pending load of the second to fourth stands S2, S3, and S4 is controlled to be 10 M, and when the pending load of -6 f is controlled, the second stand S2 When controlling the board crown by applying a pending load of 10 f, the effect of the change in the incoming board crown appears as a change in the outboard board crown at the third stand S3 with a value of △C = 3, and the pending load of 16 sails. When control is performed by applying a pending load of 10 sails at the third stand S3, the influence of the change in the entrance board crown appears as a change in the exit board crown 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 due to the movement of the double chock work roll pending device of multiple stands, as shown in Figure 3. In this sense, double chock work is used to expand the control range of the plate crown. An effective method is interlocking control of the bending equipment. When plate crown control is linked with multiple stands in this way, the plate crown control range increases compared to control with a single stand, but if plate crown control is performed in conjunction with subsequent stands as well, plate crown control The range exceeds the shape dead zone region, and the shape between the stands deteriorates, which has an adverse effect on sheet threading.

Therefore, it is not possible to perform interlocking pressure control between the front stage stand and the rear stage stand in the same pending mode. Alternatively, if the front stage stand performs interlocking pressure control and the rear stage stand maintains the pressure constant, as shown in Figure 4, the plate crown will shift as indicated by the △ mark, and the plate remaining on the final stand will change. The crown control range will be small.

In order to eliminate this phenomenon, if each stand in the latter stage performs plate crown control individually within the shape dead zone region, the transition can be made as shown by the x mark, without deteriorating the shape, and moreover, it can be controlled by the interlocking stand in the former stage. The plate crown control range can be maintained. In FIG. 4, curve 1 shows the case where double choke work roll bending devices are set on the second and third stands S2 and S3 and the pending load of these roll pending devices is set to, for example, 100 tons. This shows the change in the plate crown when the curve peak and pending load are set to -60 tons, for example. It shows the transition of the plate crown, and
The x mark indicates the transition of the plate crown when control is performed to keep the plate crown ratio constant in the rear stage stand.

This figure 4 shows that after performing interlocking control in which the direction in which pending is applied is the same while the pending load of the pending devices installed in the multiple stands in the previous stage is held constant,
The plate crown shows the effect when a single stand is individually controlled to maintain the plate crown ratio of the previous stage in the rear stage stand. It can be seen from FIG. 4 that the plate crown control range is wider in the case marked △ than in the case marked △. Based on this principle, the present invention controls the movement of each double chock work roll pending device in the same direction at a constant pressure ratio in the multiple stands at the front stage, and individually controls the plate crown within the shape-unfavorable zone region at each stand at the rear stage. This is a method and device for maintaining the large plate crown control range obtained in the front stand at the rear stage and expanding the plate crown control range at the final stand without disturbing the plate shape.

FIG. 5 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 1 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 a load is applied to the inner chock 3 and outer chock 4 by hydraulic pressure. The load applied to the inner chock 3 and the outer chock 4
The roll pending moment can be changed by increasing or decreasing the load applied to the plate, allowing a large plate crown control range to be obtained. FIG. 6 shows an example of the device of the present invention. For example, when there are first to sixth stands S, to S6, the double chock work roll pending device 7 is installed in each stand, and the previous stage The first, second, and third stands S, , S2, and S3 are linked together so that they can be controlled as a group, and the subsequent stands S4, S5, and S6 can each be controlled individually. That is, the front stands S,,S2,S
3 each double choke work roll pending device 7
A solenoid valve 17 is provided in the middle of the pressure oil supply line from the hydraulic source so that the pressure can be controlled and linked in the same direction and at a constant ratio, and each stand is connected to the pressure setting device 8 and the pressure regulator. The pressure to each pressure setting device 8 is given a signal by an arithmetic device 12, and a plurality of double choke work roll pending devices 7 are interlocked to control the plate crown step by step within the shape unfavorable zone region. The control range of the plate crown on the outlet side of the S3 stand is increased, and the double choke work roll pending device 7 of the subsequent stands S4, S5, and S6 is controlled by each pressure regulating valve 10 provided in the hydraulic pressure supply line. are individually connected to the pressure indicating device 11 so that each stand S4, S5, S6 can be independently controlled within the shape dead zone region. Arithmetic device 1
2 calculates the shape dead zone area when the double chock work roll pending devices 7 of the multiple stands in the previous stage are controlled in conjunction from the control information 13 such as the rolling conditions of the stands, and sets the pressure so that the pressure is controlled at a constant ratio. On the other hand, a device (not shown) that calculates the shape dead zone region from information such as the board width, board thickness, and board deformation resistance in each stand outputs a command to the shape dead zone region width q to b6 of all stands. is calculated as data, and a command is issued to each pressure indicating device 11 corresponding to each pending device 7 in the subsequent stages (fourth to sixth stands). First, the calculation device 12 calculates the pressure according to the plate crown control range from the information 13, that is, as shown in FIG. 3.

The first stand S, second stand S2 is calculated.
In order to control the pending load of the third stand S3 within the range shown in Fig. 3, each stand S,,S
2. Set the proportion (ratio) of the pending load of S3 to a constant value. Once this pending load ratio is set, it remains unchanged. Next, a signal is given to the pressure setting device 8 of each stand based on the set ratio, and the pressure regulator 9 of each stand is actuated.Furthermore, the solenoid valve 17 that simultaneously operates the stands S and -S3 is actuated. Accordingly, the double choke work roll pending device 7, which is provided in multiple stands, is pressure-controlled and interlocked in the same direction while maintaining a constant ratio, and the plate crane control in the same direction is performed at each stand S, S2, and S3. At this time, as explained in the principle diagram of FIG. 3, the exit side plate crown of the first stand S is controlled by the double choke work roll pending device 7 during rolling in the second stand S2, and further moves. Controlled third stand S
The plate crown control is performed by the double choke work roll bending device 7 of No. 3. In this way, by controlling the double chock work roll pending devices 7 of a plurality of stands in an interlocked manner at a constant ratio, the plate crown control range can be expanded on the exit side of the third stand S3 without disturbing the plate shape. In this case, since coarse control is possible with the stand in the previous stage, the practical fuwawa zone (A in Fig. 1) is possible.
Plate crown control is performed at the maximum value of the plate crown control range determined based on Cr. Next, in each stand in the latter stage, the width b to b6 of the shape dead zone area in each stand determined by the device (not shown) that calculates the shape dead zone area is used as data to the calculation device 12.
The plate crown control range of each of the subsequent stands S4, S5, and S6 is predicted and calculated, and each pressure indicating device 11 is used to control the pressure regulating valve! 0 to allow each stand to be independently controlled within its individual shape dead zone area.

In this case as well, except for the final stand S6, the allowable range of the shape is widened and the plate crown is controlled within a large plate crown control range within the practical dead zone region. Since the shape of the plate on the exit side of the final stand S6 is required to be constant, the shape absolute dead zone region (△ cut in the figure) is required for the final stand.
Plate crown control is performed within the plate. This allows the plate crown control range controlled by the previous stand to be maintained, and the amount of this plate crown control range that remains as history in the final stand increases, expanding the plate crown control range at the final stand without disturbing the plate shape. can. FIG. 7 shows another example of the present invention, in which the shape control is performed by keeping the plate crown ratio constant in the independent control at the rear stage stand in the above embodiment.

That is, as shown in FIG.
2. When the double chock work roll pending devices of S3 are controlled in conjunction with each other at a constant ratio, the plate crown ratio changes as shown by the 0 mark, but if the pressure is maintained at a constant level with the subsequent stand, it changes as shown by the △ mark. It ends up.

Therefore, the subsequent stands S4, S5, and S6 are controlled to keep the ratio crown constant as indicated by the x mark. In the above-mentioned Fig. 4, the effect of controlling the plate crown ratio to be constant in the rear stage stand is shown by the plate crown Cr, but this Fig. 8 shows the above effect by the ratio crown, Curve 1' corresponds to curve 1 in FIG. 4, and curve B' corresponds to curve m in FIG. In addition, the △ mark indicates the change in the ratio crown when there is no control in the rear stage stand, and the × mark indicates the change in the ratio crown when the plate crown ratio is controlled to be constant at the rear stage stand.This control method is the previous stand (for example, the 4th stand S) as shown in Figure 7.
4), the pending pressure PB of the previous stand, the gutter PR of the load cell 14 of the previous stand, and the load PR of the load cell 15 of the next stand (for example, the fifth stand S5) are input to the calculation magic turtle 6 as data. Then, the calculation device 16 calculates a predicted value of the pending load at the next stand S5, and based on this value, a pressure command is issued and controlled to the pending device of the next stand, and correction control is performed so that the ratio crown is constant. For example, now, the previous stand and the next stand load cell load: PR, PR2 pending pressure: PB, P82 plate crown change coefficient due to rolling force: KR, KR2 plate crown change coefficient due to pending pressure: KB,
KB2 thickness: day,
Day 2 plate crown change: △Cr,
If △Cr2, then ``△Cr: PRKR + P8KB, so Kushiko (PRIKRI + PBIKBI) Kasa = 4 (P
R2KR20PB2KB2).

In order to determine the pending pressure PB2 of the next stand from the above equation, it is sufficient to determine PR, PB, and PR2.

for example, KR,=KR2=KR KB,=KB2=KB Then, PB2 = H device (Western belt) 10 belt PB, 10 Q and Q is the plate crown correction.

Therefore, the ratio crown is corrected and controlled in the next stand according to the above formula.

In this case, in this embodiment, since each of the subsequent stands is controlled within the plate crown control range determined within the shape absolute dead zone region, the plate crown control range can be increased without disturbing the shape.

As described above, according to the present invention, a plurality of stands at the front stage of a continuous rolling mill are controlled in conjunction as a group to control the plate crown, and the stands at the rear stage are individually controlled to control the plate crown within the shape dead zone region, or Since the ratio crown is controlled at a constant ratio, the plate crown control range increased by the movement control in the previous stage can be maintained by the independent control of the stand in the latter stage, and since the plate crown control range is controlled based on the shape dead zone area, the plate shape can be maintained. There is no disturbance in the final stand, and the control range of the plate crown at the final stand can be increased.Also, there is no disturbance in the final stand plate shape, which improves quality.
It is possible to improve walking speed and operation rate, and since the front stand changes step by step through movement, and the rear stand performs pending pressure control using predictive calculation,
It can produce excellent effects such as simplifying the control system.

[Brief explanation of drawings]

Figure 1 shows the relationship between plate crown change and plate shape, Figure 2
The figure is a principle diagram of plate crown control with a single stand, Figure 3 A is a principle diagram showing the increase in plate crown control range when plate crown control is performed by moving multiple stands, and Figure 4
The figure is a relational diagram showing the transition of plate crowns in multiple stands, Figure 5 is an explanatory diagram of a double chock work roll pending mounting, Figure 6 is a schematic diagram showing an example of the device of the present invention, and Figure 7 is a diagram of the present invention. Schematic diagram showing another example of the device, No. 8
The figure is a relational diagram showing the transition of the ratio crown in a plurality of stands, and FIG. 9 is an example diagram showing the plate crown control by the motion control of the 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, 8...Pressure setting device, 9...Pressure regulator, 10...Pressure regulating valve, 11... Pressure indicating device, 12... Arithmetic device,
14, 15...Load cell, 16...
Arithmetic device, 17... Solenoid valve. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 7 Figure 6 Figure 9 Figure 8

Claims (1)

[Scope of Claims] 1. In a continuous rolling mill, pressure control is performed in the same direction while maintaining a constant ratio of the pressure of the roll bending devices of a plurality of stands at the front stage, and the roll bending devices are controlled in an interlocked manner, and then A method for controlling the shape of a plate crown plate in a continuous rolling mill, characterized in that the roll bending devices of each subsequent stand are independently controlled within each shape dead zone region. 2 In a continuous rolling mill, roll bending devices are installed in multiple stands at the front stage, and a pressure control device that controls the pressure of each roll bending device in the same direction while maintaining a constant ratio, and a shape dead zone area based on control information. A calculation device is installed to calculate the pressure and give a control command to the pressure control device so that plate crown control can be performed within the stand, and a roll bending device is also installed in each stand in the latter stage, so that each of the roll bending devices can be controlled. In order to perform plate crown control independently in each shape dead zone region, a pressure adjustment device that individually controls the pressure on each roll bending device and the width of the shape dead zone region in each stand obtained are used as data. A plate crown and plate shape control device for a continuous rolling mill, characterized in that a calculation device is provided for calculating the pressure for controlling the plate crown of each stand in the subsequent stage and giving control commands to the individual pressure regulating devices. 3 In a continuous rolling mill, roll bending devices are installed in multiple stands at the front stage, and a pressure control device that can control the pressure of each roll bending device in the same direction while maintaining a constant ratio, and a shape dead zone area based on control information. A calculation device is installed to calculate the pressure and give a control command to the pressure control device so that plate crown control can be performed within the stand, and a roll bending device is also installed in each of the subsequent stands to control the roll bending in the subsequent stands. Among the devices, there is a calculation device that calculates the bending pressure of the next stand from the bending pressure and load cell load of the previous stand and the load cell load of the next stand, and a calculation device that calculates the bending pressure of the next stand from the bending pressure and load cell load of the previous stand. A plate crown and plate shape control device for a continuous rolling mill, characterized in that it is equipped with a pressure control device for controlling pressure to a roll bending device of the next stand.