JPS591484B2 - Metal strip rolling method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for controlling the rolling of a steel plate strip using a reversible cold rolling mill, and in particular, a technique for effectively controlling both the thickness and shape of each rolling roll. It is related to.

As is widely known, in the rolling of steel plate strips, the shape and thickness accuracy of the plate are important factors that control the quality of the plate, and various studies have been conducted in various directions on the technology to control them. There are also many established technologies.

In recent years, with the development of powerful shape detection devices, it has become possible to put high-precision shape control into practical use.Instead of simply adjusting the roll pending force, it is now possible to control the shape in conjunction with other control ends. Now I can think.

The reduction blade is also adjusted for the purpose of shape control.

However, when the rolling blade is changed to adjust the shape, it must be taken into consideration that the thickness of the finished product changes, and here the thickness control and shape control are interrelated.

If the relationship between the two is ignored and the control operations are performed independently, both control functions will not be effectively exerted and it will be difficult to obtain a steel strip with good shape and thickness accuracy. is also quite possible.

In view of the above-mentioned facts, the present invention provides a method for effectively using plate thickness control and shape control in a reversible rolling mill, thereby making it possible to maintain both plate shape and plate thickness accuracy in good condition. Make it familiar.

In other words, we quantitatively understand the phenomenon in which the deformation resistance of the rolled material increases with the increase in the number of rolling passes (number of passes), and based on this we determine the priority of plate thickness control and shape control for each number of rolling passes. According to the priority, plate thickness control and shape control are performed for each rolling number.

A specific explanation will be given below based on examples.

FIG. 1 shows the configuration of an automatic plate thickness control device using rolling reduction and longitudinal tension as operating ends, a reversible rolling mill, a roll pending force, a rolling blade, and a shape control device using coolant as operating ends necessary for explaining the present invention. Only the relevant parts are illustrated.

1 is a rolling machine, 2 is a rolled material, 3 and 4 are winding and unwinding reels, 3' and 4' are electric motors that drive these, 5 is a plate shape detection device, 6 is a plate thickness gauge, and 7 is a A rolling down device, 8 an automatic shape control device, and 9 and 10 automatic plate thickness control devices using rolling down and tension as operating ends, respectively.

The rolled material 2 is rolled from the unwinding reel 4 through the rolling mill 1, and then wound onto the take-up reel 3.

At this time, the shape and thickness of the rolled strip are measured by a shape detection device 5 and a thickness meter 6, respectively, and a shape signal a1
It is output as a plate thickness difference signal.

The automatic plate thickness control devices 9 and 10 receive the plate thickness deviation signal and output tension correction output signals e, f and a reduction correction signal d in a direction to bring the deviation signal closer to zero.

On the other hand, a signal a indicating the plate shape is output from the shape detection device and inputted to the shape control device 8, which calculates correction amounts for various operating ends for shape adjustment. The blade will need to be corrected.

The plate thickness change due to the reduction force correction for shape adjustment is reversely corrected by the plate thickness control device, and a competing effect between plate thickness control and shape control occurs.

In order to prevent this from happening, it is necessary to determine the priority of plate thickness control and shape control for each rolling number.

Determination of priorities for plate thickness control and shape control, which is a feature of the present invention, will be explained below.

If the rolling blade is operated to correct the shape of the rolled material when it is soft (that is, the number of rolling cycles is small), the shape of the sheet will be maintained, but the accuracy of the sheet thickness will be poor.

In order to correct the defective plate thickness in the next pass, that is, in a state where the rolled material becomes slightly hard, a larger rolling force operation is required.

If the work hardening of the plate due to the number of rolling cycles is significant, it may be extremely difficult to correct the plate thickness in subsequent passes. When viewed in the series of rolling operations from pass to finished product rolling pass, it is not necessarily recognized as an effective operation.

That is, when the rolled material is in a soft state, it is effective to perform a rolling force operation with the primary purpose of modifying the sheet thickness during the rolling process.

Hardened state of rolled material (i.e. number of rolling near the final stage)
By operating the reduction blade to correct the shape, it is possible to effectively correct the shape with almost no effect on the plate thickness accuracy.

In other words, when the rolled material is hard, the change in thickness is very small even when a constant rolling force is applied, but the shape of the sheet changes greatly with a very small change in thickness in the width direction.
Further, this slight change in plate thickness is such that it hardly poses a problem from the viewpoint of the plate thickness accuracy that should be ensured as a steel plate.

Therefore, in the series of reversible rolling processes from the original sheet to be rolled to the thickness of the finished sheet, an effective rolling control method is to preferentially correct the sheet thickness in the first half when the rolled material is relatively soft. I understand.

Furthermore, it can be seen that an effective rolling control method is to perform almost no rolling operation for thickness correction in the latter half, when the rolled material is relatively hard, and preferentially perform shape correction.

A method for determining priority dust for plate thickness correction and shape correction for each number of rolling cycles will be described below with reference to the drawings.

In Fig. 2, 1 is a rolling machine, 2 is a rolled material, 3° and 4 are respectively,
A winding and unwinding reel, 5 a steel plate shape detecting device, 6 a plate thickness gauge, and 7 Cj rolling device are the same as those of the rolling mill described above, so their explanation will be omitted.

Among the operation outputs from the shape control device 8, the reduction correction signal C is output to the reduction device 7 by the correction device 12 as a signal αsc corrected by the coefficient αS output from the priority setting device 11.

Further, the reduction correction signal d of the operational output from the plate thickness control device 9 is outputted to the reduction device 7 by the correction device 13 as a signal αTd corrected by the coefficient αT output from the priority setting device 11.

The pattern of αS and αT output from this priority setting device is as shown in FIG. 3, where αT decreases as the plasticity coefficient increases, and αS increases as the plasticity coefficient increases.

Furthermore, the plasticity coefficient Q can be easily obtained from approximate calculations by sampling and presetting various data during rolling (rolling blade, entry side plate thickness and deviation, exit side plate thickness and deviation, roll diameter, friction coefficient, front tension, rear tension, etc.). I can do it.

As described above, the feature of the present invention is to further correct the plate thickness by using the plasticity coefficient or a similar quantity as a parameter to each of the reduction correction signal for plate thickness correction and the reduction correction signal for shape correction. The objective is to effectively obtain a steel plate with good shape.

Here, the experimental results of the present inventors will be explained regarding an example in which priorities are set for plate thickness correction and shape correction.

The amount of plate thickness change and the amount of shape change that are corrected by a fixed reduction correction amount in accordance with the plasticity coefficient Q for each rolling number change as shown in FIG. 4.

In this figure, the constant pressure reduction correction amount was set to 100PL.

In a state where the plasticity coefficient is large, the plate thickness hardly changes even with reduction correction, and the shape change is much larger as a relative amount, so shape control is effective. However, the change in plate thickness is much larger in relative terms, indicating that plate thickness control is effective.

From this situation, the plasticity coefficient gives a rolling correction signal for plate thickness correction, a rolling correction signal for shape correction, and respective correction coefficients αS and αT in a pattern as shown in FIG.

This pattern corresponds to the rolling experiment conducted by the present inventors, and the feature of the present invention is, as mentioned earlier, that the plate thickness is corrected in response to the plasticity coefficient or a similar amount. The objective is to set the amount of reduction correction and the amount of reduction correction for shape correction, and the degree of priority of these two amounts.

Further, by rolling according to this priority level, it is possible to obtain a steel plate with excellent thickness and shape.

Finally, although the above explanation of the present invention has been made with respect to a reversible rolling mill for convenience of explanation, it is clear from the content that the present invention is not particularly limited to reversible rolling, and the present invention can be used to improve general plate thickness and shape. Applicable to rolling that is intended to be maintained at

[Brief explanation of drawings]

Figure 1 is a block diagram explaining the rolling method for controlling plate thickness and shape, Figure 2 is a block diagram explaining the present invention in detail, and Figure 3 is the pattern of output from the priority determining device in Figure 2. FIG. 4 is a graph showing the amount of plate thickness change and shape change that are corrected by a constant reduction correction amount, and FIG. 5 is a characteristic chart showing an example of the pattern of correction coefficients αT and αS. . In the drawing, 8 is a shape control device, 9 is a plate thickness control device, 1 is a cold rolling machine, 2 is a metal I-IJ tube, Q is a plasticity coefficient, 7
is a roll position correction device.

Claims (1)

[Claims] 1. When rolling a metal strip IJ tube using a cold rolling mill equipped with a plate thickness control device and a shape control device, due to changes in the plasticity coefficient or equivalent parameters due to an increase in the number of rolling passes of the metal strip, A method for rolling a metal strip, comprising correcting each of a reduction correction signal for sheet thickness correction and a reduction correction signal for shape correction, thereby adjusting an amount of roll position correction.