JPS606213A - Controlling method of snaking of strip - Google Patents

Abstract

PURPOSE:To make control practicable even if the time lag of a screw-down system is large by determining the controlled variable to be applied to the screw-down device in order to perform titled control of a tandem rolling device in accordance with the sum of the difference between the right and left rolling loads of the fore stage stand and the differentiated value thereof. CONSTITUTION:There is no output from an adder 13 if a strip S travels normally and a difference between rolling loads p=0. However, when the tailing-through of the strip S arises in the i-2 stand, the strip S begins to snake in the i-1 stand and a difference (p) (+ and - polarities on the operating and driving sides of the stand) in the size corresponding to the rate of snaking arises. Such difference is detected with a calculator 11 and at the same time the fluctuation of the difference (p) per unit time is detected with a mechanical differentiator 12. The added output converted to a position signal with a coefft. device 14 is collated respectively with screw down positions Xr, Xl by calculators 15R, 15L and commands Mr, Ml for the screw down positions are emitted from the respective calculators. A servocontrol valve 16R (same with 16L) controls the amt. of the oil in a screw-down cylinder 4R and the direction thereof according to the command Mr so that the difference between said command and the output Xr from a position detector 4R is made zero.

Description

[Detailed description of the invention] The present invention relates to (i) a meandering control method for an IJ knob;

In strip rolling, the work side and drive side (hereinafter referred to as left side and right side) of the rolling stand
If there is a difference in the rolling reduction rate, meandering of the strip will occur, resulting in a decrease in the yield of the strip.If the amount of meandering increases, the strip will touch the sadcide and the edge of the tube will become double rolled. As a result, the rolls of the rolling mill are damaged, and production efficiency is significantly reduced due to roll changes.

For this reason, various methods have been proposed to prevent the strip from meandering. One of them is the
As shown in No. 85, there is a method in which the entire rolling load difference between the left and right sides of the stand, which occurs due to the meandering of the strip, is detected and the rolling device of the stand is completely controlled.

However, this method has the advantage of not requiring any special equipment or device to detect the amount of meandering of the IJ tube, but it is configured to control the rolling device of the stand that detects the rolling load difference. Therefore, the rolling load difference caused by the control of the rolling device is superimposed on the rolling load difference caused by the meandering, which makes the control complicated. The disadvantage of this method is that the stable control region becomes narrow due to time constraints.

Figure 1 shows the changes in the rolling load difference P between each stand when the rear end of the /91 strip falls through and meandering occurs and narrowing (two-sheet rolling) occurs in the Holatos IJ mill. It is understood that the strip starts meandering at the i-2 stand after the strip is removed at the i-2 stand, and this meandering is further amplified at the i-stand, causing the above narrowing at the l-1 stand. . In this way, when narrowing of the strip occurs at one stand, the IJ tube starts meandering and a rolling load difference occurs at the previous stand. Since the rolling time is only about 0.2 to 0.4 seconds, the above-mentioned conventional method is not practical when considering the time delay of the rolling system.

The present invention has been made in order to eliminate the drawbacks of the conventional method described in section 2, and detects the rolling load difference between the work side and the drive side of any rolling stand other than the final hoe stand, and detects the rolling load difference and its variation. By adopting a configuration that controls the difference in the lowering position between the work side and drive side of the next stage stand according to the The object of the present invention is to provide a method for controlling the meandering of a strip, which is practical even in cases where the strip meandering can be controlled.

Hereinafter, one embodiment of the present invention will be described with reference to all the drawings.

In Figure 2, i in the Aid tandem rolling mill
-Stand 1 is BHI stand. In each of these stands, 1.1 17-roll, 2.2H back-up roll, 3R13Lfd left and right rolling load meters (
load cell), 4R, 4LU hydraulic retainer cylinder, 5R
, 5L is a reduction ram, 6R26L is a position detector, and S is a strip.

The rolling load (signal) Pl output by the right rolling load cell 3R and the rolling load (signal) Pl output by the left rolling load cell 3L are guided to the computing unit 11. The calculator 11 calculates the difference between the rolling loads P1 and Pl, and calculates the left and right rolling loads (signals) p=P1-P.
2'i output. 12 is a differentiator, and the rolling load difference p
Differentiate and output d p / d t k. This differential output d p / d t and the rolling load difference p are calculated by the adder 1.
3, and the added output P = p + d p / d t...
...(1) is sent to the coefficient unit 14.

15R and 15L are arithmetic units, and arithmetic unit 1511j:
Roll down position (signal) output by position detector 6R
f - Human power, the addition output PXK (conversion constant) output by the coefficient unit 14 is received as a + input, the difference between the Ryokawa forces is calculated, and a pressure reduction command M r f is sent to the servo valve 16R. Arithmetic unit 15L
receives the positive input to the reduction position output X1 of the position detector 6L and the output of the coefficient unit 14, calculates the difference between the two, and sends the entire reduction command M1 to the servo valve 16L. Servo valve 16
R,16Ll'! The amount and direction of oil supplied to the reduction cylinder 4R14L is controlled according to the magnitude and polarity of the reduction commands Mr and Ml.

Next, the operation of this device will be explained.

Now, assuming that the IJ tube S is running normally and the rolling load difference p==Q, there is no output from the adder 13. In this state, when the bottom of the strip S falls off at the i-2 stand (not shown), the strip S begins to meander at the i-1 stand, and the rolling load difference p (the meandering direction is on the work side) has a magnitude corresponding to the amount of meandering. If it is in the drive side direction, it is depolar, and if it is in the drive side direction, it is unipolar). This rolling load difference p is detected by the calculator 11, and at the same time, the variation amount per unit time of the rolling load difference is detected by the differentiator 1.
Detected at 2. The addition output P converted into a position signal by the coefficient unit 14 is compared with the reduction position Xr in the calculation unit 15R, and at the same time with the reduction position X1 in the calculation unit 15L. M
r, Ml is sent out. The servo valve 16R fully controls the oil amount and direction of the pressure reduction cylinder 4R in accordance with the pressure reduction position command Mr so that the difference between this command and the output Xr of the position detector 4R becomes OK.

The same applies to the servo valve 16L, and thus the meandering of the strip S in the L stand is suppressed.

In this embodiment, the total control amount of the rolling device of the next stage stand is calculated based on the sum of the rolling load difference in the l-1 stand and its differential value. You have a lot of time before you start. In fact, it takes about 1 second from the start of meandering at the I-1 stand until the bottom of the strip S comes off at the L stand, so the restrictions due to the time delay TALC in controlling the rolling down device are far greater than in the conventional case. becomes smaller.

FIG. 3 shows a block diagram of the control shown in FIG. 2. In the figure, the dashed-dotted line corresponds to the reduction control system in FIG. K3. 4 is the control gain, Td is the differentiator gain,
(Tp·B+1) indicates the first-order delay of the lowering device including the lowering cylinders 4R and 4L'e.

(7) The area outside the dashed line in FIG. 3 represents the meandering mechanism, and each constant is determined by the specifications of the rolling mill and the rolling conditions. That is, K1 is the distance between roll supports, Mill constant,
Rolling load, roll circumferential speed, S) A constant determined by the plate thickness and width of IJ Tsubu S, and rolling reduction rate, K2 is a constant determined by the above plate width, the difference between the mill constants on the left and right sides, and the difference between the rolling reduction rates on the left and right sides, K5fl It is a constant determined by the distance between the roll supports, the mill constant, and the rolling load. Also, the part indicated by the two-dot chain line indicates one of the features of the present invention, and in the present invention, the above i-1
It is naturally inherent in the detection system that detects the occurrence of meandering of the strip S in the stand. Hereinafter, this will be explained with reference to FIG.

Now, the meandering amount of strip S at l stand '1i7Yt
- Total meandering amount of strip S at stand 1-1 Yi-1
Assuming that the approach angle of the strip S to the l stand is θ as shown in FIG. 4, (8) dYi Y l −1= Y I + L tan θ −
-(3) holds true. However, vH strip S
is the inter-stand speed, and L is the inter-stand distance.

From both equations, the meandering amount Y I-1 is as follows. The part expressed by this equation (4) corresponds to the part surrounded by the two-dot chain line, and the detection system includes the differential element L dYi V dt .

As described above, according to the present invention, the control amount given to the rolling down device in order to control the meandering of the strip is determined based on the sum of the left and right rolling load difference between the stand and stand in the previous stage and its (9) differential value. By doing so, it is possible to secure enough time to detect all of the rolling load differences and apply control, so it can be used even when the time delay of the rolling system is too long. As a result, the control system naturally contains a differential element, so the stable region of the control system is wide, and since no special device for meandering detection is used, the cost is low.

[Brief explanation of drawings]

FIG. 1 is a diagram showing all the changes in the pressure treatment load difference in each stand when narrowing of the strip occurs in a hot strip mill. FIG. 2 is a control block diagram of an embodiment of the strip meandering control method according to the present invention. FIG. 3 is a strip meandering diagram for explaining the control block diagram. 3R, 3L... Rolling load meter, 4R, 4L... Rolling cylinder, 5R, 5L... Rolling ram, 6R. 6L...Position detector, 11...Arithmetic unit, 12...
Differentiator, 13... Adder, 14... Coefficient unit, 15R
1 (10) 15L...Arithmetic unit, 16R, 16L...Servo valve,
A, B...Rolling stand. Patent Applicant Kobe Steel Co., Ltd. Agent Patent Attorney Fu Kobayashi (11) ○ O (UOI) d Capital 'ii%' [T/Procedural Amendment (Method) October 27, 1980 Commissioner of the Japan Patent Office 1 , Indication of the case 1982 Patent Application No. 114360 2 Name of the invention Strip meandering control method 3 Person making the amendment 4 Agent 105 Address 2-20-7 Nishi-Shinbashi, Minato-ku, Tokyo , Contents of the amendment (1) "Figure 3 is a meandering diagram" on page 10, lines 14 to 16 of the specification is corrected as follows. "Figure 3 is a block diagram of the above embodiment, and Figure 4 is a strip meandering diagram for explaining the block diagram." (2)

Claims (1)

[Claims] In a tandem rolling machine, the rolling load difference between the work side and the drive side of any rolling stand except the final stand is detected, and the rolling load difference between the work side and the drive side of the next stand is detected according to the rolling load difference and the variation of the rolling load difference. A strip meandering control method in which the e% characteristic is to control the difference in the drive side rolling position.