KR100513775B1 - Method for controlling strip width in the fgc - Google Patents

Abstract

The present invention relates to a method for controlling the thickness of a plate in a thickness change section, and in particular, the measured thickness and the set thickness of the changed material introduced into the stand in the process of continuously cold rolling by welding strips having different thicknesses, widths, and steel grades to each other. In the event of a deviation, the dynamic setup system resets the deviation in consideration of the deviation, and calculates and applies the predicted control value of the next stand using the rolling record value at the exit side of the stand. The main purpose is to prevent off-gauge and to improve the quality and productivity of the FGC section.

Description

Plate thickness control method in thickness change section {METHOD FOR CONTROLLING STRIP WIDTH IN THE FGC}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling plate thickness in a thickness change section (FGC). In particular, the thickness of a strip being moved in a thickness change section during a run of a cold rolling process is an off-gauge (tolerance of a set plate thickness standard value). It relates to a plate thickness control method in the thickness change section to control the rolling roll gap so as not to go out of the range).

In general, in the cold rolling process, strips of different thicknesses, widths, and steel grades are welded in a welded portion, and then continuously rolled to the exit side. At this time, the part where the thickness, width and steel grades of different materials are welded is called FGC (Flying Gauge Change), and as described above, the rolling is continuously performed and then output to the rearmost stand and cut for each material again. The rolling work process in the continuous cold rolling is controlled by a host computer, and in particular, a set-up system for determining the initial value (eg, roll gap, speed) of the actuator before the start of rolling in order to secure the longitudinal thickness of the product. There is an AGC system for effectively controlling various disturbances generated during rolling operations. Among the AGC systems, there is a FF (Feed Forward) AGC system and a FB (FeedBack) AGC system. The former uses the plate thickness deviation of the material coming from the stand entrance and the latter uses the plate thickness deviation generated from the stand exit. Determine roll gap control amount to minimize stand exit plate thickness deviation.

In the conventional plate thickness control method, the thickness information of the rear end strip which is continuously welded to the front end of the front end strip and continuously moved in the continuous cold rolling process is received from the host computer, and the roll gap setting value of the conventional normal setup system is obtained. Calculated and output.

However, in the conventional method as described above, in the case where there is a deviation between the indication thickness of the rear end strip received from the upper computer and the actual measurement thickness measured by the entrance thickness measuring instrument installed in front of the stand, compensation control for this is impossible. Even if it was possible, feedback was compensated by the exit side. However, since the feedback compensation has already passed the steel sheet to the exit side, it was not possible to reduce the off-gauge (out of the tolerance range of the set plate thickness specification) in the FGC section. Therefore, the FGC section outputs off-gauge products at an average of 15m at the front and the end, which lengthens the length of the tip off gauge. Predictive control of setting the working conditions of the rolling mill in advance before rolling was impossible. Since the effective control according to the thickness deviation of the line and the end portion cannot be made, the disturbance factor itself is all absorbed as a factor of the thickness defect, and the deviation thereof is transmitted to the rear stand, thereby degrading the plate thickness quality.

The present invention has been made to solve the above problems, the invention through the control to compensate for the deviation between the thickness information and the measured thickness of the strip continuously welded in the section of the FGC between driving in the continuous cold rolling process Method of controlling plate thickness in thickness change section to reduce the range of off-gauge occurring at line and end of FGC section by controlling the roll gap of stand The purpose is to provide.

The present invention as a construction means for achieving the above object, in the continuous cold rolling mill rolling in at least one or more stands, the thickness change (FGC; Flying Gauge) in which the strips of different thicknesses, widths, steel grades are continuously welded to each other In the plate thickness control method in the

(A) setting up a rolling roll gap for the indicated thickness of the strip of said welded different material before entering the # 1 stand;

(B) correcting the set-up of the rolling roll gap when a deviation between the measured thickness of the strip measured at the mouth of the # 1 stand and the indicated thickness occurs;

(C) if rolling is performed by the calibrated setup, after the strip passes the #i (i is the stand number) stand, calculating the load correction coefficient of the #i stand from the rolling performance value of the #i stand; ,

(D) calculating a predicted control value from the # i + 1 stand to the final stand by using the calculated load correction coefficient of the #i stand and the exit plate thickness of the #i stand calculated in advance; and

(E) setting the rolling roll gap from the # i + 1 stand to the final stand by applying the calculated predicted control value,

It characterized in that it comprises a method for controlling the thickness of the plate in the thickness change section characterized in that it is repeated from step (a) to step (e) while increasing i from 1 to 1.

In the continuous cold rolling process having five stands, a section in which different thicknesses, widths, and steel strips are welded is generally referred to as a flying gauge change section (hereinafter referred to as FGC) section. If the measured strip thickness measured at the entrance of the original stand differs from the instruction thickness given by the host computer before the changed strip is introduced into the rolling mill, a dynamic setup is performed to compensate for this. The present invention relates to a method for controlling the thickness of a plate in a thickness change section, which is intended to predict and apply a load correction factor, a reduction position of a pressing position, a rolling load, and a roll speed to be applied to the next stand.

Hereinafter, the present invention will be described in more detail with reference to the drawings.

Figure 1 schematically shows the configuration of the entire system for implementing the present invention. Referring to FIG. 1, information on a thickness, a width, a steel grade, and the like of a changed material is transferred from the host computer 101 to the PCS 102. The setup schedule of the working condition (for example, rolling roll gap, etc.) is transmitted to the PLC 107 in accordance with the information using the transferred information in the normal setup system 103 inside the PCS 102. 107 sets the roll gap, rolling load and roll speed of the rolling mill stand in accordance with the transmitted setup schedule. However, if a difference between the indicated thickness indicated by the host computer 101 and the actual measured thickness at the entrance of the stand is detected, the dynamic setup system 104 operates to correct the difference. The above difference is one of the causes of off-gauge in the front and rear ends of the FGC section. Thus, the dynamic setup system 104 is to minimize the length of the off-gauge. The dynamic setup system 104 resets the setup schedule for the working conditions of the stand to correct gaps in the rolling rolls resulting from the difference. The setup schedule reset in the dynamic setup system 104 is transmitted to the FGC compensator 105 by correcting the setup schedule set in the normal setup system 103. In addition, the FGC correction unit 105 calculates the predictive control value to be applied to the next stand using the rolling record value detected at the exit side after the steel sheet passes through the stand. The predictive control value includes the amount of reduction in the pressing position of each stand to be applied to the final stand in the next stand, the rolling load, the roll speed and the load correction coefficient. The calculated predicted control value is transmitted to the PLC 107 to reset the working conditions of the rolling mill. Therefore, as shown in FIG. 1, in the present invention, the dynamic setup system 104 is reset using information on the side thickness, and the predicted control value to be applied to the next stand is calculated by using the rolling performance value at the exit side. After the steel sheet passes the next stand, the predictive control value is applied to set the working condition of the rolling mill.

2 shows a signal flow diagram of a dynamic setup system according to the present invention. In detail with reference to FIG. 2, the instruction | indication of the said board 1 in the FGC section 2 which is changed and input from the host computer which sets the thickness, width, steel grade, etc. of the board 1 to be rolled, etc. The thickness is received by the PCS control unit (not shown). The normal setup system 201 in the PCS control unit receives the instruction thickness of the plate 1 to set up work conditions such as roll gap, pressing force, roll speed, and the like of the # 1 stand 4. As shown in FIG. 2, the thickness of the changed material 1 is actually detected by the # 1 side thickness detector 3 installed at a predetermined distance from the # 1 stand 4. The thickness of the detected plate 1 is collected by the PLC unit 202. If there is a difference by comparing the collected measured thickness with the instruction thickness given by the host computer, the dynamic setup system 203 resets the working condition of the # 1 stand 4 in consideration of the difference. The signal reset and output from the dynamic setup system 203 is inputted to the PLC unit 202 again to reset the working condition of the # 1 stand 4.

The # 1 stand, whose work conditions are reset by the reset, compensates for the deviation between the measured thickness set by the host computer and the measured thickness actually measured by the # 1 entrance thickness detector (3). 1 Set up to compensate for deviations in actual thickness when passing through the stand-side thickness detector 3.

Figure 3 shows a signal flow diagram for the FGC correction of the #i (i is the stand number) stand in the present invention. As shown in FIG. 3, the steel plate 1 passes between the rolls of the stands 4, 5, 6, and 7 of a rolling mill in a continuous cold rolling process. In FIG. 3, after the steel sheet 1 passes through the # 1 stand 4, the FGC section 2 passes through the #i stand exit thickness detection unit 10. When the FGC section passes the #i stand, the first PLC unit 301 has a rolling record value such as a rolling roll gap, tension, load, roll speed of the #i stand, and exit thickness detected by the #i stand exit thickness detector 10. Collect it. The #i stand FGC correction unit 302 calculates the load correction coefficient Zp of the #i stand by using the collected rolling results of the #i stand. The load of the # i + 1 stand is calculated using the calculated load correction coefficient Zp of the #i stand and the exit plate thickness measured value of the #i stand. Using the calculated load of the # i + 1 stand, the predicted control values such as the amount of change in the pressing position from the # i + 1 stand to the final stand, the speed set value, the rolling load and the roll speed are calculated. As described above, the predicted control value calculated by the #i stand FGC correction unit 302 is set by the second PLC unit 303. The predicted control value set in the second PLC unit 303 sets the roll gap in consideration of the predicted control value for the roll speed and the pressing force from the # i + 1 stand to the final stand.

In the present invention, the operation of the dynamic FGC setup system and the operation of the #i stand FGC correction unit also apply to the next stand. This improves the accuracy of the set value of the rear stand.

Figure 4 is a comparison of the effect before and after the application of the present invention shows the comparison of the off-gauge length of the upper and lower parts of the steel sheet in relation to the product error rate before and after applying the present invention. As shown in FIG. 4, before the present invention was applied, off-gauge of an average of about 15 m occurred at the front and end portions of the product. However, in the case of applying the present invention, the off-gauge generated at the line and the end is improved to about 10m on average, and the effect on the thickness quality improvement and workability has been proved.

Therefore, according to the present invention described above, the off-gauge of the line and the rear end resulting from the deviation of the measured thickness and the set thickness in the FGC section in which strips having different thicknesses, widths and steel grades are welded and continuously rolled It can be improved by about 10m on average, and the control accuracy is improved by applying the predictive control value to the rear stand, thereby improving the quality of FGC section in the cold rolling mill and improving workability and efficiency.

In addition, it is possible to improve productivity by eliminating the excessive defense operation phenomenon for thickness control of the FGC section during stable operation settlement in the future.

Figure 1 is a schematic diagram showing the configuration of the entire system for the implementation of the present invention.

2 is a signal flow diagram of a dynamic setup system in accordance with the present invention.

3 is a signal flow diagram for the FGC correction of the #i stand according to the present invention.

4 is a comparison of effects before and after the application of the present invention.

 Explanation of symbols on the main parts of the drawings

1: Steel sheet 2: FGC (Flying Gauge Change) section

3: entrance thickness detector 4: stand # 1

101: host computer

Claims (3)

In the continuous cold rolling mill rolling at least one or more stands, in the thickness control section (FGC: Flying Gauge Change) section where the strips of different thicknesses, widths, and steel grades are welded together and continuously rolled, (A) setting up the rolling roll gap for the indicated thickness of the other material strip of the thickness change section before entering the # 1 stand; (B) correcting the set-up of the rolling roll gap when a deviation between the measured thickness of the strip measured at the mouth of the # 1 stand and the indicated thickness occurs; (C) if rolling is performed by the calibrated setup, after the strip passes the #i (i is the stand number) stand, calculating the load correction coefficient of the #i stand from the rolling performance value of the #i stand; ; (D) calculating a predicted control value from the # i + 1 stand to the final stand by using the calculated load correction coefficient of the #i stand and the exit plate thickness of the #i stand previously calculated; And (E) setting the rolling roll gap from the # i + 1 stand to the final stand by applying the calculated predicted control value; It includes, and i is increased from 1 to 1 plate thickness control method in the thickness change section, characterized in that for repeating the steps (a) to (e) step The method of claim 1, The set-up method of the plate thickness control in the thickness change section, characterized in that it comprises the setting of the gap, the rolling force, the roll speed of the rolling roll for the thickness information of the strip The method of claim 1, The predicted control value calculated in the step (d) includes a change in load correction coefficient, rolling load, reduction in rolling position, friction coefficient and roll speed from the # i + 1 stand to the final stand. Plate thickness control method in section