JP4306001B2 - Running shape control method in sheet rolling - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is a rolling mill that rolls steel sheets, etc., when manufacturing products with different plate thicknesses or widths from the same base material, or when changing running distances such as joining different base materials and rolling continuously The present invention relates to a running shape control method in sheet rolling.
[0002]
[Prior art]
With the aim of continuation of the process and improvement of productivity, development of the change technology of the running distance has been promoted in various fields, and cold rolling mills have already been implemented in many plants. In recent years, a change in running distance is also being applied to a hot rolling mill.
[0003]
There are the following four cases for changing the running distance.
(1) Manufacture products with different thicknesses from the same base material.
(2) Manufacture products with different plate widths from the same base material.
(3) Manufacture products with different plate widths and thicknesses from the same base material.
(4) Join different base materials and roll continuously. This may be the case where the dimensions and type of the base material to be joined are the same or different.
[0004]
When continuously rolling such materials with different plate thicknesses and plate widths, there is a problem that the plate shape of the rolled material deteriorates due to a sudden change in rolling conditions.
[0005]
As a prior art for preventing the deterioration of the plate shape, for example, Japanese Patent No. 2819202 discloses a rolled plate shape control method having a roll bend force and a roll cross angle as operation ends as shown in FIGS. Has been. In FIG. 1, 10 is a rolled material, 12 is a work roll, 14 is a backup roll, 20 is a load detector for detecting a rolling load, and 30 is a roll for controlling a roll bending force for bending the work roll 12. Bending force control device, 32 is a roll bend force setting amount changing device, 40 is a cross angle control device for controlling the cross angle of the work roll 12, 42 is a cross angle setting amount changing device, and 50 is a next material setting amount calculation. An apparatus 52 is a setting change timing instruction apparatus.
[0006]
In this method, as shown in FIG. 2, the roll cross angle having a low operating speed is changed from the cross angle target θa of the preceding material toward the cross angle target θb of the following material at the timing t1 prior to the start of the plate thickness change. At the same time, in order to compensate for the change operation of the cross angle, roll bend force correction is performed to correct the roll bend force from Fwa to Fw ₁ in the opposite direction to the cross angle, and starts at timing t2. In synchronization with the plate thickness change, the roll bend force change is changed from Fw ₁ to Fw ₂ with the increase / decrease of the roll bend force reversed, and the increase / decrease of the roll bend force is reversed again at the plate thickness change end timing t3. and Fwb from Fw ₂ was changed to, in the cross angle change end timing t4, the roll cross angle and roll bend force, the next strip set value θb after each, as a Fwb, the occurrence of shape defect portion It is to limit the thickness change part.
[0007]
[Problems to be solved by the invention]
However, in the above method, the roll cross angle operates until after the plate thickness change is completed at the timing t3. Therefore, when the inter-stand tension decreases with the plate thickness change, the roll cross angle is shown in FIG. As described above, there was a problem that plate meandering occurred.
[0008]
In general, in a rolling mill, the lubrication state of the rolled material in the upper (work) roll and the lower (work) roll is different. For example, in a rolling mill in which the roll cross angle can be changed, as shown in FIG. If the pushing force of the rolling material 10 is stronger than the pushing force of the lower roll 12b, the force for pushing the rolling material 10 to the drive (DR) side becomes stronger as the roll cross angle increases.
[0009]
On the other hand, as shown in FIG. 2, when the plate thickness change amount occurs, if the plate thickness change amount error occurs, the tension variation between the stands occurs. From the controllability of tension control, Occurs after the thickness change end timing t3.
[0010]
Therefore, if the tension between the stands is high, it is possible to prevent the plate meandering accompanying the roll cross angle operation, but the decrease in the tension between the stands accompanying the change of the running plate thickness and the meandering action accompanying the movement of the roll cross angle are simultaneously performed. When this occurs, plate meandering occurs, which causes troubles such as ear pain and biting by the rolling material coming into contact with the guide.
[0011]
The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to obtain a stable plate shape even when the rolling conditions of the preceding material and the succeeding material are greatly different.
[0012]
[Means for Solving the Problems]
The present invention uses a roll bend force control device and a roll cross angle control device as shape actuators when continuously rolling a rolled material having a plurality of plate thicknesses in the coil longitudinal direction, before and after the plate thickness change point. In the running shape control method in which the shape actuator is operated so as to achieve the target mechanical crown of the succeeding material predicted from the predetermined timing before rolling, the change of the running plate thickness is performed after the roll cross angle changing operation is completed. As described above, the above-mentioned problems are solved .
[0013]
In the method according to the present invention, the plate thickness is changed after the roll cross angle changing operation is completed, so that the plate meandering is suppressed by the meandering correction action due to the tension between the stands, and the rolling conditions of the preceding material and the following material are greatly different. In this case, a stable plate shape can be maintained.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0015]
The roll cross angle of the roll cloth type rolling mill is determined so as to obtain an optimum plate shape for each coil to be rolled. This roll cross angle is calculated as a roll cross angle equivalent to the required roll mechanical crown amount. It is well known that the roll bend force has an effect equivalent to the roll mechanical crown amount. Therefore, a relational expression (hereinafter referred to as a cross angle / bender optimum curve expression) for obtaining an optimum plate shape of the coil is obtained between the roll cross angle θ and the roll bend force Fw. This cross angle / bender optimum curve equation is as shown in the following equation, for example, and is obtained for each coil.
[0016]
a0 + a1 * Fw + a2 * θ ² = 0 (1)
[0017]
Here, a0, a1, and a2 are parameters determined for each coil.
[0018]
In this way, the roll cross angle and the roll bend force are equivalent in terms of the effect on the plate shape, but the device for adjusting the roll cross angle and the device for adjusting the roll bend force are controlled by the plate shape control. There are the following major differences when viewed as actuators.
[0019]
That is, the roll cross angle adjusting device has a wide plate shape control range, but its responsiveness is low, while the roll bend force adjusting device has a narrow plate shape control range, but its responsiveness is high. There is a difference.
[0020]
Also, the roll cross angle adjusting device has the potential to meander the rolled material to the DR side or the work (WS) side with respect to the traveling direction of the rolled material due to the difference in lubrication between the upper and lower rolls. The bend force adjusting device does not affect the meandering.
[0021]
FIG. 5 is a graph of a cross angle / bender optimum curve showing a plate shape control method from the start of changing the roll cross angle to the end of changing the plate thickness, with the roll bend force Fw on the vertical axis and the roll cross angle θ on the horizontal axis. taken up, in the implementation form of the comparative example and the present invention represents these relations. In the comparative example and the embodiment, starting from the point P1 indicating the roll cross angle θa and the roll bend force Fwa of the preceding material, the path of P1 → P3 → P2 indicated by a thick solid line in the drawing (comparative example) or a broken line The roll cross angle and the roll bend force are changed according to the path (embodiment) of P1 → P4 → P2 shown in FIG.
[0022]
Comparative Example according to the first path is a case where the roll cross angle change is completed at-fly change end, follow the Hare implementation form the second path, the roll cross angle change is completed in-fly changes beginning This is an example.
[0023]
Roll cross angle in a comparative example, a roll bend force, in FIG. 6 the temporal change state of interstand tension and amount of meandering, front roll cross angle in you facilities embodiment, the roll bend force, interstand tension and the meandering amount of time A typical change state is shown in FIG.
[0024]
In the comparative example , as shown in FIG. 6, before the plate thickness change starting point reaches the stand, the roll cross angle θ is started to change from the preceding material set value θa to the succeeding material set value θb, and the preceding The roll bend force Fw is changed from Fwa to Fwc according to the material cross angle / bender optimum curve.
[0025]
Next, with the start of the thickness change, the roll bend force is set so that the point P3 on the cross angle / bender optimum curve for the preceding material becomes the point P2 for the following material on the cross angle / bender optimum curve for the following material. Is changed to Fwb, and the roll cross angle is changed to θb.
[0026]
In contrast, in the implementation form, as shown in FIG. 7, before the plate thickness change start point reaches the stand, toward the roll cross angle θ from the previous strip set value θa to the following material set value θb At the same time as starting the change, the roll bend force Fw is changed from Fwa to Fwd in accordance with the cross angle / bender optimum curve of the preceding material.
[0027]
Next, with the start of thickness change, the roll bend force is set so that the point P4 on the cross angle / bender optimum curve for the preceding material becomes the succeeding material setting point P2 on the cross angle / bender optimum curve for the following material. Change to Fwb.
[0028]
As apparent from FIG. 7, according to the present invention, in order to terminate the roll cross angle change before the peak of the reduction of interstand tension with Hashimaban Atsuhen further plate meandering due to the roll cross angle change It can be suppressed by the tension between the stands, and the occurrence of plate meandering can be suppressed.
[0029]
Incidentally, the embodiment is not affected by the tension reducing due to Hashimaban thickness change, a high effect of the plate meandering suppression.
[0030]
【The invention's effect】
According to the present invention, it is possible to suppress plate meandering associated with the roll cross angle change, and to obtain a stable plate shape even when the rolling conditions of the preceding material and the following material are greatly different.
[Brief description of the drawings]
FIG. 1 is a block diagram showing the overall configuration of a control device having a roll cross angle and a roll bend force as operating ends. FIG. 2 is a graph showing the thickness, roll cross angle, roll bend force and tension between stands in a conventional example. FIG. 3 is a timing chart including a meandering amount. FIG. 4 is a plan view showing a mechanism in which meandering occurs when the roll cross angle is changed. FIG. 5 is a roll in a comparative example and an embodiment of the present invention. FIG. 6 is a timing chart showing an example of a temporal change state of a roll cross angle, a roll bend force, a tension between stands, and a meandering amount in a comparative example . roll cross angle in an embodiment of the present invention, the roll bend force a timing chart showing an example of a temporal change state of interstand tension and meandering amount Door DESCRIPTION OF SYMBOLS
DESCRIPTION OF SYMBOLS 10 ... Rolled material 12, 12a, 12b ... Work roll 14 ... Backup roll 20 ... Load detector 30 ... Roll bend force control device 32 ... Roll bend force setting amount change device 40 ... Cross angle control device 42 ... Cross angle setting amount change Device 50 ... Next material set amount calculation device 52 ... Setting change timing instruction device

Claims (1)

When continuously rolling a rolled material having a plurality of plate thicknesses without any break in the coil longitudinal direction,
Using a roll bend force control device and a roll cross angle control device as a shape actuator,
In the running shape control method of operating the shape actuator so as to achieve the target mechanical crown of the subsequent material predicted before rolling from a predetermined timing before and after the plate thickness change point,
A running shape control method in plate rolling, characterized in that a running plate thickness is changed after the roll cross angle changing operation is finished .

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