JPS58205611A - Method for controlling speed of continuous hot rolling mill - Google Patents

Abstract

PURPOSE:To enable the improvement in rolling speed and to improve productivity by determining the speed among the respective stands of a rolling mill which has the highest speed ratio (% speed) with respect to the max. speed thereof as a pivot stand and setting the same beforehand or changing the same during rolling. CONSTITUTION:A speed command device 21 determines the % speeds of respective stands (hereinafter expressed at St) 1-7 in the rolling speed pattern of the respective Sts from an upper calculator 22 and sets the St. having the max. % speed as a pivot St in the initial setting stage prior to rolling. After the start of the rolling, the device 21 calculates the speed command at the pivot St from the acceleration command from a calculator 21, the speed corrections for loopers from looper control devices 15-20, and the speed correction for manual intervention from a speed operation board 23 and outputs the same to speed control devices 8-14. If the % speed of the other St attains the value higher than the % speed of the pivot St in this stage, the % speeds of the respective St, the speed correction values for loopers, and the speed correction value for manual interversion are stored, and the pivot St is changed to the St having the max. % speed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a speed control method for a continuous hot rolling mill, and more particularly to a speed control method for a finishing tandem rolling mill.

The maximum rolling speed of each stand of a finishing tandem rolling mill is designed for the speed pattern of thin materials that require the most rolling torque, and for thin materials, the maximum rolling speed of each stand of the finishing tandem rolling mill is close to the maximum rolling speed of the tandem rolling mill as a whole. However, when rolling thick materials, etc., the maximum rolling speed is often not reached due to limitations in the speed range of the upstream stand.

In other words, in finishing tandem rolling mills, the speed standard (MRHX
5SRH), does not have a speed correction function (successive, looper correction), and has the highest speed ratio (hereinafter referred to as percentage speed) to the maximum rolling speed of its own stand.The pivot stand is fixed to a specific stand. This method is common.

In order to obtain the maximum rolling speed as a tandem rolling mill,
It is necessary to use a pivot stand with a high percent speed for all stands, but since the rolling reduction setting of each stand differs depending on the thickness of the rolled material, the no(-cent speed of each stand also changes accordingly).

For this reason, when a pivot stand is fixed to a specific stand, it does not necessarily mean that the pivot stand will have the highest percentage speed, and if the pivot stand and the stand with the highest percentage speed are different, it will not work as a tandem rolling mill. The highest possible rolling speed cannot be reached.

This will be explained using a specific example.

FIGS. 1 to 3 are examples of a seven-stand tandem rolling mill showing speed patterns with the rolling speed on the vertical axis and the stand number on the horizontal axis. FIG. 1 shows a maximum rolling speed pattern C1 and a maximum rolling speed pattern C2 that can be set for control purposes when stand No. 7 is used as a pivot stand. In this figure, the diagonal line c3 is the speed correction, and the farther it is from the pivot stand, the larger the value is required.
It reaches about 5 inches. If the rolling speed pattern of each stand is C4 shown in Figure 2, rolling is possible at the maximum rolling speed of a tandem rolling mill, but if the rolling speed pattern of each stand is C5 shown in Figure 3, rolling is possible. Rolling is only possible at a speed lower than the maximum rolling speed c6 by the amount of speed correction, resulting in a decrease in productivity.

The present invention has been made to advantageously solve these problems, and its gist is to pivot the stand with the highest speed ratio to the maximum rolling speed of each stand of a continuous hot rolling mill. The present invention relates to a method for controlling the speed of rolling, which is set in advance as a stand.

That is, the present invention is a hot tandem rolling mill that obtains the highest rolling speed for all rolling speed patterns, and the stand with the highest percent speed is always set as the pivot stand, or the stand is set in advance or during rolling. Changes are made.

However, in the case of the rolling speed pattern of C5 shown in Figure 3 above, rolling at the maximum speed of C6 is possible by using the No. 1 stand with the highest percent speed as the pot stand, and that is only possible. It is possible to increase productivity.

Next, an example of a tandem type rolling mill speed control device for carrying out the method of the present invention will be explained with reference to FIG.

In Fig. 4, 1 to 7 are the mill motors of each stand, and 8 to 7 are the mill motors of each stand.
14 is a speed control device for each mill motor, 15 to 2 degrees is a control device for each looper, 21 is a speed command device, 22 is a host computer, and 23 is a speed operation desk.

In this device, in the initial setting stage before rolling, the percentage speed of each stand is calculated in the speed command device 21 based on the rolling speed pattern of each stand given from the host computer 22, and the pivot stand is assigned to the stand with the highest percentage speed. is set, and a speed command is issued to the speed control devices 8 to 14 of each stand. Next, after rolling is started, the speed command device 2 receives an acceleration command from the host computer, a looper speed correction from the looper control devices 15 to 20, and a manual intervention speed correction from the speed operation desk 23.
1, a speed command for the set pivot stand is calculated and output to the speed control devices 8 to 14 of each stand. At this time, the percentage speed of each stand is always calculated in the speed command device, and if the percentage speed of another stand becomes higher than that of the pivot stand, the percentage speed of each stand is calculated immediately or after a certain period of time, and the looper The minute speed correction value and the manual intervention minute speed correction value are stored, and the pivot stand is changed to the stand with the highest percent speed, and the stored percent speed and acceleration command given from the host computer 22 are used in the looper control devices 15 to 20. The speed command after change at the pot stand is calculated in the speed control device 21 from the speed correction for the looper and the speed correction for the manual intervention from the speed operation desk 23, and the speed command is calculated for the speed control devices 8 to 14 of each stand. Output. If a change in the pivot stand does not ensure the speed correction that the stand should have in a stand other than the pivot, it becomes necessary to suppress the rolling speed of the pivot stand to 100% or less. However, even in this case, rolling is still performed at the maximum rolling speed possible with the rolling mill.

In the looper minute speed correction and manual intervention minute speed correction described above, the deviation from the stored value when changing the pivot stand is used to calculate the speed command. On the other hand, when the operator changes the speed between the stands, it is sufficient to provide an operating end (not shown) for changing the relative speed between each stand, and the manual intervention speed correction signal from the operating end can be used to change the relative speed between the stands. Whether or not to change the stand speed is determined and controlled within the speed command device 21 depending on which stand is busy before the change. For example, when changing the relative speed between stands No. 3 and 4 in a tandem rolling mill consisting of seven stands, the No. 7 stand pivot raises and lowers the speed of stands No. 1 to No. 3 to control the speed, but the No. 1 stand pivot Sometimes, the speed of stands No. 4 to No. 7 may be controlled by raising and lowering the speed in the direction opposite to that when the No. 7 stand is pivoted. That is, for the operator, the purpose of changing the relative speed between the stands is achieved in any case, so there is no problem in operation.

Also, in the looper control partial speed correction, desired control can be achieved by changing the speed raising/lowering stand in the same manner as in the manual intervention partial speed correction described above.

Next, an example of operation according to the method of the present invention will be given.

(1) When using the optimal setting of the pivot stand, the rolling size is 8.3 mg x 106.5 mm Table 1 From Table 1, the maximum rolling speed with the conventional F7 fixed pivot is F1
This becomes rate limiting and has to be set lower by the speed correction (15%), but in the present invention, the F1 pivot allows the speed to be changed to 100% of the F1 stand percentage speed.

(2) When changing the pivot stand during rolling Rolling size 2.0. In rolling 10271j, the set cutting speeds are as follows.

In this case, the F7 stand has the highest initial setting percentage speed, so the F7 stand is set as the pivot stand.

After the start of rolling, if the F7 exit plate thickness is corrected to become 100μ thicker (this can often happen due to automatic plate thickness control or manual intervention), the rolling speed of F1 to F6 will be doubled by 2.V2D (with manual intervention) Or it is corrected by looper control speed correction). Therefore, the percent speed of each stand is K as follows.

As a result, the percent speed of the F6 stand is the highest, so it is necessary to change from the pivot stand F7 to F6. The difference in maximum rolling speed between when the pivot stand was changed and when it was not changed is as follows.

In other words, if the F7 pivot remains, the rolling speed of the F6 stand will be lower than the maximum speed by the speed correction, whereas
When changing to pivot, the rolling speed of F6 stand is 1
00, and rolling at the maximum rolling speed is possible.

As mentioned in detail above, by setting the pivot stand to the stand with the highest percentage speed,
In a continuous hot rolling mill, it is possible to increase the rolling speed by about 151 degrees for thick materials compared to conventional pivot rolling with a fixed final stand, and productivity can be increased accordingly.

[Brief explanation of drawings]

FIGS. 1 to 3 are explanatory diagrams showing speed patterns of a seven-stand tandem rolling mill. FIG. 4 is an explanatory diagram showing an example of a rolling mill speed control device for implementing the present invention. 1 to 7: Mill motor of each stand 8 to 14: Each mill motor control device 15 to 20: Each looper control device 21: Speed control device 22: Ten place calculator 23: Speed operation desk Patent applicant Nippon Steel Corporation

Claims (1)

[Claims] Speed of a continuous hot rolling mill characterized in that among each stand of the continuous hot rolling mill, the stand with the highest speed ratio to the maximum rolling speed is set as a pivot stand and is set in advance or changed during rolling. Control method.