KR20010058175A - Method for controlling tension of a thin strip at a twin-roll strip caster - Google Patents

Abstract

PURPOSE: A tension control method for a twin roll type strip casting machine is provided to maintain a linear velocity of a strip and the tension of the strip uniformly by variably controlling the velocity of a strip tension control unit according to current data of the coiler for stably winding the strip to the coiler, thereby improving the quality of the strip and obtaining the stability of the strip casting. CONSTITUTION: In a tension control method for a twin roll type strip casting machine, a driving velocity of a coiler(8) is controlled according to a change of a loop height detected by a loop height detecting unit to be accorded with a linear velocity of the twin rolls(1,2), and a strip tension between the coiler and a strip tension control unit(7) is controlled by detecting a current data of the coiler to increase the tension of the strip(9) according to the increase or decrease of the coiler current, thereby applying a uniform tension to the strip.

Description

Tension control method for twin roll sheet metal casting machine {METHOD FOR CONTROLLING TENSION OF A THIN STRIP AT A TWIN-ROLL STRIP CASTER}

The present invention relates to a tension control method of a twin-roll type sheet casting machine, and more particularly, a pair that can ensure the quality of the thin plate and the stability of the casting process by maintaining a constant tension of the sheet produced in the twin-roll type sheet casting machine The present invention relates to a tension control method for a roll type thin casting machine.

Regularly and stably winding the thin plate produced in the twin roll sheet metal casting process to the coiler is very important in terms of the quality of the manufactured thin plate and the stability of the casting process. That is, when the tension of the thin plate to be manufactured is too large, the thin plate is bent, the central portion of the thin plate is convex, and excessive force is applied to the thin plate edge to tear the thin plate edge. In addition, if the tension of the thin plate to be produced is too small, the thin plate wound on the coiler is loose and the casting process becomes unstable.

Therefore, in the general cold rolling process, as shown in FIG. 1, the looper 13 is used to constantly control the tension of the thin plate. At this time, the thin plate tension is constantly adjusted by the vertical movement of the looper 13. That is, the looper 13 placed between the stand 11 and the stand 12 moves up and down according to the current of the drive motors of the two stands 11 and 12 or the data of the tension measuring device so that the tension of the thin plate between the stands is increased. Constantly controlled

However, the twin roll sheet metal casting machine is a process that is currently being researched and developed, and the profile of the sheet is not uniform as that of the sheet produced in the general cold rolling process. That is, the thin plate produced in the twin roll thin plate manufacturing process is likely to have a very thick thickness of the edge portion of the thin plate due to edge bulging or the like. Therefore, in case of using the looper of the general cold rolling process, the contact surface between the looper and the sheet depends on the profile of the sheet, so if the profile of the sheet is not constant, many slip phenomenon occurs in the looper, and the tension of the sheet is kept constant by the vertical movement of the looper. It's hard to control. In addition, in the general cold rolling process, the optimum tension value for each sheet thickness is obtained by experience. In the twin roll type sheet casting process, since the thickness of the plate is frequently changed, the optimum tension value for each sheet thickness is obtained by experience. There was a problem in that the optimum tension control was difficult.

Therefore, a method of uniformly controlling the tension of the thin plate to be manufactured in a very fragile environment in which the thin plate to be manufactured is rough and its profile is not constant should be sought to ensure the quality of the thin plate and to ensure the stability of the casting process.

Therefore, the present invention has been made in order to solve the above-mentioned conventional problems, the purpose of which is to ensure the quality of the thin plate and the stability of the casting process by constantly controlling the tension of the thin plate produced in the twin-roll thin plate casting machine It is an object of the present invention to provide a tension control method for a double rock type casting machine.

1 is a schematic view showing the configuration of a tension control device in a general cold rolling process.

Figure 2 is a system diagram showing a schematic configuration of a twin roll sheet casting machine for implementing the present invention.

Figure 3 shows the configuration of a control unit for controlling the thin plate tension control unit for implementing the present invention.

Explanation of symbols on the main parts of the drawings

1 ... fixed roll, 2 ... driven roll,

3 ... thin sheet guide roll, 4 ... loop height measuring device,

5 ... deflect roll, 6 ... sheet position control unit,

7 thin sheet tension control unit, 8 coils,

9 ... thin plate, 70 ... tension control unit control system,

80. Coiler motor control system.

In order to achieve the above object, in the tension control method of a twin roll thin plate casting machine according to the present invention, in the thin plate tension control method of a twin roll thin plate casting machine for winding the thin plate regularly and stably in a coil roll in a twin roll type sheet casting process,

The driving speed of the coiler is controlled according to the change of the loop height detected by the loop height measuring device so as to match the linear speed of the pair roll, and the current data of the coiler is detected to impose a constant tension on the thin plate. The sheet tension between the coiler and the sheet tension control unit is controlled by a tension control unit that increases or decreases the tension of the sheet according to the current increase or decrease of the coiler.

Hereinafter will be described in detail with reference to the accompanying drawings the configuration and effect of the tension control method of a twin-roll thin-plate casting machine according to the present invention.

Figure 2 is a system diagram showing a schematic configuration of a twin roll sheet casting machine for implementing the present invention. As shown in FIG. 2, in the twin-roll type sheet casting machine, the thin plate 9 manufactured between the driving roll 2 and the fixed roll 1 travels toward the coiler 8, and the thin plate is wound around the coiler 8. do. At this time, the angular velocity of the coiler 8 is controlled according to the data of the loop height measuring device 4 in order to maintain the line speeds of the pair rolls 1 and 2 and the coiler 8 to be the same. In addition, in the twin-roll thin plate casting process, the thin plate guide roll 3, the deflect roll 5, and the thin plate position control unit 6 are provided so that the thin plate can be stably advanced in the thin plate moving direction.

In such a configuration, the speed of the coiler uses only a speed control system for speed linkage with the double roll, and thus, the coiler alone is very difficult to control the speed of the sheet and the tension of the sheet. Therefore, the thin plate tension control unit 7 is configured to give a constant tension to the thin plate to be manufactured. At this time, the thin plate tension control unit 7 includes a driving motor, and the tension of the thin plate is controlled by controlling the speed of the motor.

Figure 3 shows the configuration of a control unit for controlling the thin plate tension control unit for implementing the present invention, as shown in Figure 3, the thin plate tension control unit for implementing the present invention is largely coiler motor control system 80 And the tension unit motor control system 70, and variably control the speed of the thin plate tension control unit 7 by using the current data of the coiler motor which is variably controlled according to the detection result of the loop height measuring device 4. .

That is, in the coiler motor control system of the thin plate tension control unit 7 according to the present invention, the loop height is constant through the first speed PI controller 81 by receiving the loop height measurement value measured from the loop height measuring device 4. The outermost control loop is configured to be controlled. The final goal of the coiler motor control system is to keep the speed constant. Accordingly, when the coiler motor control system operates according to the loop height measurement value and the loop height is kept constant, it means that the linear speed of the double roll and the linear speed of the coiler are controlled to be the same.

Meanwhile, the coiler motor speed control value controlled by the first speed PI controller 81 is output to the second speed PI controller 83 after the deviation from the speed target value is calculated by the first operator 82. . At this time, the second speed PI controller 83 converts the input speed control deviation value into a corresponding current control value, and the current PI controller 84 controls the input current control value to control the motor drive. The value is converted into a value and output to the coiler motor control loop 85. The coiler motor control loop 85 inputs a tension coefficient and a load value to the deviation between the input motor voltage control value and the feedback detection value, performs a predetermined operation, and outputs the actual control value for driving the coiler motor current. To control.

Meanwhile, when the tension control is turned on, the tension control unit according to the present invention calculates and outputs a tension control value according to the coiler motor current measurement value output from the coiler motor control loop 80 through the tension PI controller 71. do. At this time, the second operator 72 inputs the speed target value for controlling the motor drive of the tension control unit and the tension control value, calculates the deviation, and outputs the deviation to the speed PI controller 73. In this case, the speed PI controller 73 calculates and outputs a current control value corresponding to the input deviation to the limiter 74, and in the limiter 74 when the input current control value is within an upper / lower limit. The output voltage is converted into a voltage value corresponding to the input current control value, and when the upper / lower limit is exceeded, the maximum voltage value or the minimum voltage value is output. On the other hand, the output of the speed PI controller 73 is input to the current PI controller 75 when the tension control is off.

The voltage control value output from the limiter 74 is output to the tension control loop, and the tension control loop performs a predetermined operation to compensate for the deviation between the current control value and the tension control value for the fed back tension control. Tension control is performed by outputting the motor control signal of the drive motor.

Hereinafter will be described the operation and effect of the tension control method of the twin-roll thin-plate casting machine according to the present invention. First, in the present invention, the tension is imposed on the thin plate by the difference in the linear speeds of the coiler 8 and the thin plate tension control unit 7. If the ideal situation is assumed, the linear velocities of the deflect roll (5), the sheet position control unit (6), and the sheet tension control unit (7) coincide with the linear velocities of the twin roll (1) (2) and the coiler (8). If it is rotated, the tension is not imposed on the plate produced. On the other hand, since the deflecting roll 5 and the thin plate position control unit 6 hold the thin plate 9 loosely, the deflecting roll 5 and the thin plate position control unit 6 are difficult to apply tension to the thin plate 9. . Therefore, it is the thin plate tension control unit 7 that imposes tension on the thin plate 9. That is, in order to impose a constant tension on the thin plate, the linear velocity of the specific portion should be set differently from the linear velocity of the twin roll or the coiler. As a result, the coiler 8 and the specific portion, that is, in the present invention, the thin plate control unit 7 Tension is imposed on the thin plate in between.

On the other hand, the mechanism of adding tension to the thin plate is caused by the following phenomenon. When the linear speed of the thin plate tension control unit 7 is different from the linear speeds of the twin rolls 1, 2 and the coiler 8, tension is imposed on the thin plate. If the linear speed of the thin plate tension control unit 7 is later than the linear speeds of the twin rolls 1, 2 and coiler 8, the thin plate between the twin rolls 1, 2 and the thin plate tension control unit 7 The length of (9) is increased so that the measured value of the loop height measuring device is lowered, thereby further increasing the linear velocity of the coiler 8. Thus, the length of the thin plate 9 between the thin plate tension control unit 7 and the coiler 8 is further reduced, and the load value of the coiler motor control system is increased to increase the current measured value of the coiler motor. If this phenomenon persists for a short time, the thin plate 9 between the thin plate tension control unit 7 and the coiler 8 eventually breaks, and the casting experiment is stopped. Therefore, the mechanism for applying tension to the thin plate 9 produced by the difference between the linear speed of the thin plate tension control unit 7 and the linear speeds of the twin rolls 1, 2 and the coiler 8 is a twin roll type thin plate control device. Not available for

Therefore, the capacitance of the coiler 8 motor is set to be several times larger than the motor capacitance of the sheet tension control unit 7, and the sheet tension control unit so that slip occurs in the sheet tension control unit 8 and sheet sheeting. The height of the upper roll of (7) is adjusted suitably. Adjusting the height of the upper roll of the thin plate tension control unit 7 so that slip can occur is the difference between the linear speed of the thin plate tension control unit 7 and the linear speeds of the twin rolls 1, 2 and coiler 8. It is necessary to prevent the phenomenon that the thin plate 9 is broken by. And if the electric capacity of the coiler 8 motor is set large, even if the speed setting value is given so that the thin-plate tension control unit 7 in front of the coiler 8 may rotate at a speed different from the linear speed of the coiler 8, The motor 8 rotates at a speed set value of the coiler 8 with a large force so that the traveling speed of the thin plate 9 between the pair rolls 1 and 2 and the coil is the linear speed of the coiler 8. Is fitted.

That is, when the speed setting value of the thin plate tension control unit 7 is different from the linear speeds of the pair rolls 1, 2 and the coiler 8, the load value of the coiler motor control system of Fig. 3 is changed. The change in the load value is accompanied by a change in the coiler current measured value by the coiler motor control system.

In general, since the tension of the motor is proportional to the current and the motor constant (K _T ), the tension imposed on the thin plate 9 is controlled through the current control. At this time, the current of the coiler is used and controlled as an input of the speed control system of the thin plate tension control unit 7 so that the current of the coiler motor is kept constant so that the tension of the thin plate is controlled. At this time, the thin plate tension control unit 7 is different from the linear speeds of the twin rolls 1, 2 and the coiler 8 because the speed target value changes according to the current measurement value of the coiler.

This may cause slippage between the thin plate tension control unit 7 and the thin plate 8, or in some cases the motor capacity of the thin plate tension control unit is not large, resulting in a steady state due to the difference between the speed setting value and the speed measurement value. Errors may occur. In the latter case, the current control value of the thin plate tension control unit 7 changes to infinity by the integral coefficient of the speed control system operating in the thin plate tension control unit. At this time, if the limiter is not placed, the current control value is infinitely large, and the motor of the sheet tension control unit generates an error and stops. Therefore, the limiter is placed on the current control value of the sheet tension control unit 7 to prevent the occurrence of an error. As a result, the current measured value of the coiler 8 is proportional to the tension of the thin plate between the thin plate tension control unit 7 and the coiler 8, so that the current measured value of the coiler 8 is determined by the thin plate tension control unit 7. It is kept constant by speed control, whereby the sheet tension between the sheet tension control unit 7 and the coiler 8 is kept constant.

In addition, the initial part of the thin plate produced in the twin roll type sheet casting process is a thin plate and the leader strip connection, and if the tension is applied to the portion of the threshold or more, the connection is broken. Therefore, a casting sequence determiner is provided so that tension control can be performed after the thin plate and the leader strip connection part are stably seated on the coiler.

The tension control method of the twin-roll thin-film casting machine according to the present invention is not limited to the above-described embodiment and may be variously modified within the range permitted by the technical idea of the present invention.

As described above, the tension control method of the twin-roll thin-film casting machine according to the present invention, if the profile of the thin plate is not uniform, the linear speed of the thin plate is kept constant and the tension of the thin plate is kept stable to the coiler. It is to be wound up. Therefore, in the tension control method of a thin plate casting machine according to the present invention, the quality of the thin plate can be improved by keeping the tension of the thin plate constant by controlling the speed of the thin plate tension control unit by using the current data of the coiler. It is possible to obtain the effect of ensuring the stability of the.

Claims (1)

In the thin-roll tension control method of a twin-roll type sheet casting machine for winding the thin plate regularly and stably in the coiler in the twin-roll type sheet casting process, The driving speed of the coiler is controlled according to the change of the loop height detected by the loop height measuring device so as to match the linear speed of the pair roll, and the current data of the coiler is detected to impose a constant tension on the thin plate. Thin plate tension control method of a twin-roll thin sheet casting machine, characterized in that for controlling the thin plate tension between the coiler and the thin plate tension control unit through a tension control unit for increasing and decreasing the tension of the thin plate in accordance with the current increase and decrease of the coiler.