JPH01150411A - Plate thickness control method for reversible rolling mill - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a plate thickness control method for a reversible rolling mill for making the outlet plate thickness of the rolling mill match a target value.

(Prior art) An example of a method for controlling plate thickness in a rolling mill is disclosed in Japanese Patent Application Laid-Open No. 48-59062, in which the gain of the plate thickness control system of a rolling mill is adjusted according to the rolling speed. This change was made based on the following changes. That is, as shown in FIG. 5, the rotational speed of the rolling mill 22 that rolls the rolled material 21 is detected by the speed control device 23, and the multiplier 25 is detected via the gain setting device 24 that sets a gain corresponding to this speed. is inputted into the multiplier 25 and multiplied by the detection output of the plate thickness detector 26 on the outlet side of the rolling mill 22, and the result is fed back to the speed control device 23 via the integrator 27'.

(Problems to be Solved by the Invention) However, although the conventional control method described above is effective in controlling the plate thickness of a tandem rolling mill, when applied to a reversible rolling mill, the following problems occur. There was a problem.

In other words, in the case of a reversible rolling mill, the diameter of the coil on the rear reel (unwinding reel) decreases with each rolling pass, but the thickness control system tends to gradually generate vibrations etc. This phenomenon occurs, and there is a problem in that controlling only according to the speed will actually worsen the accuracy of the thickness of the rolled material.

The present invention has been made in view of the above problems, and is a reversible rolling mill that can maintain the thickness accuracy of rolled materials by modifying the control gain in accordance with the pass. This provides a method for controlling plate thickness in a rolling mill.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the plate thickness control method for a reversible rolling mill of the present invention detects or calculates the outlet side plate thickness of the rolling mill, and calculates the outlet side plate thickness. In a plate thickness control method for a reversible rolling mill, in which the plate thickness deviation between the target plate thickness and the target plate thickness is determined by calculation, and the rolling position or rear tension of the rolling mill is corrected to reduce the deviation to zero, the rolling speed and the coil of the rear reel are adjusted. The diameter is detected, and based on the rolling speed, the coil diameter, and the plate thickness deviation, the amount of correction of the rolling position or rear tension is calculated and determined.

(Function) The present invention uses the method described above to calculate the amount of correction of the rolling position or rear tension based on the coil diameter of the rear reel, which changes with each pass of reversible rolling, the rolling speed, and the plate thickness deviation,
The plate thickness will be controlled based on the calculation results.

(Embodiment) An embodiment of the plate thickness control method according to the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of the structure, in which a rolled material 1 is unwound from a rear reel (unwinding reel) 2, and is rolled in the direction of the arrow by a rolling mill 4 while being wound up by a front reel (take-up reel) 3. It is something that

Reference numeral 5 denotes a plate thickness gauge installed on the outlet side of the rolling mill 4, and the plate thickness deviation detected by the plate thickness gauge 5 is inputted to an arithmetic unit 6, which performs a proportional-integral calculation. Then, the calculation device 6 outputs a roll-down position correction command to the roll-down position correction device 7 according to the calculation result.

The rear reel 2 is equipped with a coil diameter detection device 8 for detecting the diameter of the coil on the reel, and the rolling mill 4
The rolling speed is detected by the speed detection device 10 of the roll drive motor 9. Then, the coil diameter of the rear reel detected by the coil diameter detection device 8 and the speed detection device 1
The rolling speed detected by 0 is input to the arithmetic unit 6 and is used as a variable for the above calculation.

Here, the calculation device 6 calculates the control gain to become smaller as the detected coil diameter becomes smaller, and a specific example of the calculation equation is the following equation 0.

However, △S: Rolling position correction amount 2: Proportional gain (constant) KI: Integral gain (constant) V: Detected rolling speed value D = Detected value of coil diameter on rear ripple △h: Detected plate thickness deviation value The calculation of this 0 expression is performed by the calculation device 6,
Based on the rolling speed detection value ■, the coil diameter detection value on the rear reel 2, and the plate thickness deviation detection value △h, the rolling position correction amount △
S is determined.

Here, in order to explain this formula 0, a phenomenon in which the exit side plate thickness of rolling a4 changes due to correction of the rolling position will be explained. First, the inventors studied this phenomenon and expressed it in a block diagram as shown in FIG. Based on this, the transfer function to the change in plate thickness on the exit side of the rolling machine due to correction of the rolling position is determined as shown in the following equation (2).

However, Wn = "■771 possible ... ■-12ζW
n = −+ K P M: Mill constant Q: Plasticity coefficient (aP/aσb), (ab/a s), (ab/aσ
b): Influence coefficient H: Inlet side plate thickness B: Plate width a: Gear ratio J: CD of reel motor KP: Servo gain of hydraulic reduction device Here, the dynamic characteristics of plate thickness correction are mainly determined by its natural frequency Wn Therefore, when determining the gain for thickness control, satisfactory thickness control cannot be obtained unless Wn is taken into consideration.This will be explained using Fig. 3. A) is a Bode diagram of the open loop transfer function of the plate thickness control system when the coil diameter of the rear reel 2 is 2 [m], and (b) is a Bode diagram of the open loop transfer function of the plate thickness control system when the coil diameter of the rear reel 2 is 0.5 (m).
This is a Bode diagram of the open-loop transfer function when , and both diagrams use the same values of KP and .

As can be seen from these two figures, the gain margin in figure (B) is smaller than in figure (A), indicating that the control characteristics are worse, but this is due to the coil diameter of rear reel 2. This is due to the fact that Wn has become smaller as a result of the smaller . This can also be seen from the fact that it can be expressed as from equations ■-1 and ■-2. This problem can be solved by modifying the control gain in accordance with the rolling speed (2) and the coil diameter, as in Equation 0.

In other words, since the only things that change within a pass in Equation 0 are the rolling speed V and the coil diameter, stable control characteristics can be obtained by modifying the control gain according to the changes in Wn caused by these changes. . As an example of the method (2) above, a method is adopted in which the control gain is modified in proportion to the change in Wn.

As described above, the gist of the present invention is to modify the control gain according to changes in Wn (that is, rolling speed ■ and coil diameter D) expressed by the formula 0, and It is not limited only. In addition, the reduction position was explained as an example of the operation amount for plate thickness control.
It goes without saying that the present invention is also applicable to the case where the tension of the rear reel is used as the manipulated variable. This is clear from the fact that the transfer function to the change in plate thickness on the exit side of the rolling machine due to tension correction can be expressed as ΔT: backward tension correction amount.

Figure 4 is a characteristic diagram to show the effect of the present invention. Figure (A) shows the step response of the plate thickness control system when the coil diameter is 2 [m], and Figure (B) shows the response of the conventional method. Coil diameter is 0
．． 5 (m), and (c) in the same figure shows the step response when the coil diameter is 0.5 (m) according to the method of the present invention. From these characteristic diagrams, we can see that in the conventional case shown in Figure (B), even if the coil diameter changes, there is no corresponding control, resulting in a very oscillatory response.
c) In the case of the present invention shown in the figure, it can be seen that the plate thickness control gain is modified according to the coil diameter, resulting in a stable response.

(Effects of the Invention) According to the present invention, as explained above, the rolling speed and the coil diameter of the rear reel are detected, and the correction amount of the rolling position or rear tension is calculated based on the rain detection value and the plate thickness deviation. Therefore, the plate thickness control gain has a stable response, and it is possible to improve the plate thickness accuracy of the rolled material, making it a very effective invention.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram showing an embodiment of the method of the present invention, Fig. 2 is a block diagram for explaining the same, Fig. 3 (a) and (b) are gain characteristic diagrams for explaining the same, and Fig. 4 (A) to (C) are characteristic diagrams showing the same effect, and FIG. 5 is a configuration diagram of a conventional example. 1 is a rolled material, 2 is a rear reel, 3 is a front reel, 4 is a rolling machine, 5 is a plate thickness gauge, 6 is a calculation device, 7 is a rolling position correction device, 8 is a coil diameter detection device, 9 is a drive motor, 10 is a speed detection device. Figure 3 Kui) One system ridge J [Revised (-/5ec) Figure 1 Figure 2 Figure 4? One hour question (Sugitsu)

Claims (2)

[Claims] (1) Obtain the plate thickness at the outlet side of the rolling mill by detection or estimation calculation, calculate the plate thickness deviation between this plate thickness at the outlet side and the target plate thickness, and set the rolling mill rolling position or rear tension in order to make the deviation zero. In a plate thickness control method for a reversible rolling mill, the rolling speed and the coil diameter of the rear reel are detected, and the amount of correction of the rolling position or rear tension is determined based on the rolling speed, the coil diameter, and the plate thickness deviation. A plate thickness control method for a reversible rolling mill, characterized by calculating and determining the thickness of a reversible rolling mill. (2) Calculate the amount of correction of the reduction position or rear tension using the formula ΔS=G(S)・D/√V・Δh where ΔS: correction amount of reduction position or correction amount of rear tension G(S): proportional integral calculation Child D: Rear reel coil diameter V: Rolling speed Δh: The plate thickness control method for a reversible rolling mill according to claim 1, wherein the determination is performed based on the plate thickness deviation.