KR100931634B1 - Elongation constant control method by feedback control - Google Patents

Abstract

The present invention relates to a method of constantly controlling the elongation of a rolled plate by elongation feedback control in the temper rolling process. In the method of maintaining the elongation of a rolled sheet constantly, the present invention measures the speed (V1) before temper rolling and the speed (V2) after temper rolling of the rolled sheet to determine the actual elongation (ε _act ). The rolling load control amount ΔP is calculated using the difference Δε between the actual elongation ε _act and the reference elongation ε _ref , and the rolling elongation control amount ΔP is reflected in the target rolling load. And an elongation constant control method by elongation feedback control for temper rolling a rolled sheet such that the difference between the reference elongation is zero. The present invention measures the elongation applied to the rolled sheet when the target elongation changes due to external factors during temper rolling, and maintains the elongation constant by reflecting the amount deviating from the target elongation through feedback control in comparison with the target elongation. It provides the effect that the rolled sheet can have the required mechanical properties.

Description

A Method for Controlling Elongation Constantly by Feedback Control

1 is a schematic view showing a conventional rolling load constant control method;

2 is a graph showing the change characteristics of the elongation according to the change of the rolling load;

3 is a schematic diagram showing a method for controlling elongation constant by elongation feedback control according to the present invention; And

4 is a diagram showing a computer simulation result showing the characteristic of the elongation constant control according to the present invention.

<Explanation of symbols for the main parts of the drawings>

1: SCC 2: load cell

3: push up cylinder 4: rolled plate

10, 20: PLC

The present invention relates to a constant elongation control method applied to a temper rolling mill, and more particularly, to a method of constantly controlling the elongation of a rolled plate by elongation feedback control in the temper rolling process.

In general, it is important to maintain a constant elongation during the temper rolling process used in cold rolling to have the mechanical properties required by the rolled sheet.

Commonly known elongation control method in temper rolling is a rolling load constant control method. In the constant rolling load control method, as shown in FIG. 1, the SCC (Supervisory Controlled Computer) 1, which is an operation computer, calculates and rolls a target rolling load (P _{s, ref} ) corresponding to a target elongation of the rolling plate 4. It is delivered to a programmable logic controller (PLC) 10 for facility control. The target rolling load is added to the manual intervention amount and becomes the target control amount when the operator's manual intervention amount (P _{m, ref} ) exists. The feedback control logic configured in the PLC 10 compares the target control amount with the actual rolling load P _act measured in the load cell 2 so that the error between the target control amount and the actual rolling load becomes zero (PI). and Integral) adjust the roll gap through the push-up cylinder 3 at regular intervals via a controller and a gain K controller.

The conventional rolling load constant control method is a method of controlling the rolling load rather than directly controlling the elongation of the rolled plate 4, and is a method of controlling the elongation under rolling load control under the assumption that there is no change in the rolling load during rolling. . However, during the rolling process, the rolling load is changed by various causes, and the elongation also changes as the rolling load is changed.

Elongation and rolling load are closely related to each other. 2 is a graph showing the change characteristics of the elongation according to the change of the rolling load. When the rolling load is changed during the normal rolling with a rolling load of 363 tons and an elongation of 1.7%, the elongation also changes. As the rolling load is lowered to 334 tons and 291 tons, the elongation is lowered to 1.5% and 1.35%, respectively.

There may be a number of factors that change the rolling load during the rolling, which will be divided into the normal rolling section and the abnormal rolling section. In the normal rolling section, that is, the rolling speed is maintained above a certain speed and the rolling is continuously performed, manual intervention (roll gap, tension, bender, etc.) for shape correction is generated by the operator's judgment, and thus the rolling load is changed. On the other hand, a section in which the rolling speed changes significantly or the material (strength or deformation resistance) changes largely, such as the beginning or the end of rolling, is called an abnormal rolling section. In this section, the rolling load is inevitable without manual intervention by the operator. The change in elongation will appear.

Therefore, as described above, when the rolling load is changed during the rolling process due to various reasons, the conventional rolling load constant control method does not maintain the elongation at a constant value because the rolling load is controlled under the assumption that there is no change in the rolling load during the rolling process. It is not possible to produce a steel sheet having the required mechanical properties.

The present invention is to solve the above problems, and provides an elongation control method for maintaining the elongation constant even if the rolling load changes during the temper rolling process through elongation measurement and feedback control.

In the method of maintaining the elongation of a rolled sheet constantly, the present invention measures the speed (V1) before temper rolling and the speed (V2) after temper rolling of the rolled sheet to determine the actual elongation (ε _act ). The rolling load control amount ΔP is calculated using the difference Δε between the actual elongation ε _act and the reference elongation ε _ref , and the rolling elongation control amount ΔP is reflected in the target rolling load. And an elongation constant control method by elongation feedback control for temper rolling a rolled sheet such that the difference between the reference elongation is zero.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 is a schematic diagram showing a constant elongation control method according to the present invention.

At the beginning of rolling before the actual elongation (ε _act ) is calculated normally, SCC (1) calculates the target rolling load (P _{s, ref} ) corresponding to the target elongation (ε _ref ) and then rolls the steel based on the target rolling load. To start. After a certain period of time, the elongation at which the performance begins to be obtained is automatically switched to the constant elongation control method, and the feedback control is operated to obtain the target elongation. The actual elongation is determined by the following equation by measuring the pre-rolling speed V1 and the post-rolling speed V2 of the rolled sheet 4.

When the difference between the actual elongation calculated from the speed of the rolled sheet 4 and the reference elongation is Δε, the rolling load control amount ΔP can be obtained by the following equation (2).

는 압연하중에 대한 연신율의 영향도이다. 즉,

는 연신율 변화에 따른 압연하중의 변화량으로서, 본 발명이 속하는 기술분야에서 통상의 지식을 가진 자라면 SCC(1) 컴퓨터에서 초기 설정치인 압연하중을 계산하기 위한 계산 알고리즘에 간단한 프로그램을 추가하여서 쉽게 구할 수 있을 것이다. here

Is the influence of elongation on rolling load. In other words,

Is an amount of change in rolling load according to elongation change, and a person skilled in the art can easily obtain it by adding a simple program to a calculation algorithm for calculating a rolling load, which is an initial setting value, in an SCC computer. Could be.

를 계산한 후 PLC(20)로 전송해 두면 피드백제어에서 사용될 수 있다. 따라서 실제 제어에서 연신율 오차가 발생하는 즉시 연신율 제어가 가능하다.When calculating rolling load in SCC (1)

After calculating and transmitting to the PLC 20 can be used in the feedback control. Therefore, it is possible to control the elongation as soon as an elongation error occurs in actual control.

The rolling load control amount obtained from Equation 2 is reflected in the target rolling loads P _{s and ref} set from the SCC 1, and the push-up cylinder 3 operates according to the rolling load in which the rolling load control amount is reflected. The rolling load acting on the push-up cylinder 3 by the feedback control is continuously changed and controlled so that the actual elongation reaches the target elongation, that is, Δε is zero.

4 is a computer simulation result showing the characteristics of the elongation constant control according to the present invention.                     

In general, in a rough rolling mill used in cold rolling, a material having a yield strength of 0.5 mm in thickness, a sheet width of 994 mm, and annealing of 31 Kg / mm ² has been temper rolled at an elongation of 1.5%. The rolling load was changed to 356 tons by arbitrarily lifting a roll gap while the temper rolling was normally performed with a rolling load of 370 to 372 tons. At this time, in the conventional constant rolling load control method, the rolling load is reduced as shown in FIG. 4 (a) with the change of the roll gap, and as shown in FIG. 4 (b), the elongation is sharply reduced from the target value of 1.5% to 1.35%. .

However, in the constant elongation control method according to the present invention, although the rolling load and elongation are temporarily reduced as in the conventional constant rolling load control method due to an abnormal roll gap change, the elongation feedback control immediately restores the target elongation. .

The present invention measures the elongation applied to the rolled sheet when the target elongation changes due to external factors during temper rolling, and maintains the elongation constant by reflecting the amount deviating from the target elongation through feedback control in comparison with the target elongation. It provides the effect that the rolled sheet can have the required mechanical properties.

Claims (3)

In the method of controlling the elongation of the rolled sheet constantly during the temper rolling process, The speed (V1) before temper rolling and the speed (V2) after temper rolling of the rolled sheet were measured, and the resultant elongation ε _act was measured. Calculate, The rolling load control amount ΔP is calculated using the difference Δε between the actual elongation ε _act and the reference elongation ε _ref , The rolling plate is temperally rolled to reflect the rolling load control amount ΔP in the target rolling load so that the difference between the actual elongation and the reference elongation is 0. The rolling load control amount (ΔP) is obtained by the following equation, the constant elongation control method by the elongation feedback control.

here,

Is the influence of elongation on rolling load. The method of claim 1, The actual elongation (ε _act ) is a constant elongation control method by the elongation feedback control, characterized in that obtained by the following equation.

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