JPH084894B2 - Roller table drive control method and control device in continuous casting facility - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a drive control method and device for a delivery roller table of a pinch roll in a continuous casting facility.

[Conventional technology]

FIG. 5 shows a side view and a drive system of the pinch roll final part of the continuous casting equipment and the exit side roller table of the pinch roll. In the figure, 1 is a slab, 2 is a pinch roll 2-
Pinch roll group consisting of 11-2-1n and 2-21-2-2n, 3 is an exit side roller table provided with rolls 3-1 to 3-n, and 12 is a measuring for measuring the transport length of the cast piece 1. It is a roll. Electric motors 4-1 to 4-4 for driving the roller table 3
-N shows the case where a squirrel cage induction motor is applied.

Conventionally, the motor 4 for driving the roller table 3
For -1 to 4-n, the switching operation was performed by the low voltage power source 5 and the inverter power source 6 by the contactors 7 and 8. That is, during casting, the slab 1 is conveyed by the pulling force of the pinch roll group 2, and the driving motors 4-1 to 4-4 for the roller table 3 are conveyed.
-N is connected to the low voltage power source 5 which is about 1/4 of the rated voltage, and the operation for supplying the torque of the mechanical loss of the roller table 3 is performed.

When casting ends and the tail end of the slab 1 exits the pinch roll group 2, the roller table motors 4-1 to 4-n are switched from the low-voltage power source 5 to the inverter power source 6, and the slab 1 is conveyed. It was operating to generate as much torque as possible.

[Problems to be Solved by the Invention]

In such a conventional roller table operating method, two types of power sources, a low voltage power source 5 and an inverter power source 6, are required, and contactors 7 and 8 for switching the low voltage power source 5 and the inverter power source 6 are required. Further, since the slab 1 was pulled out by the pinch roll group 2 and transferred to the roller table 3, the low voltage power source 5 was switched to the inverter power source 6, so that the conveyance torque of the roller table 3 was small and the final pinch roll 2-1n, The conveying torque must be generated by one 2−2n unit. Therefore, the slab 1 is the final pinch roll 2-
Final pinch roll 2-1n, 2-2n when passing 1n, 2-2n
There was a problem that the drawing operation was not performed smoothly because the load was too heavy.

The present invention has been made in view of the above problems of the conventional operating method, and an object of the present invention is to drive a motor for driving a roller table with a single power source and perform a smooth pulling operation.

[Means for solving the problem]

In order to achieve this object, the roller table control method for continuous casting equipment of the present invention is a roller table control method for continuous casting equipment in which a group of rollers is driven by an induction motor driven by an inverter. When a cast piece is cast by a pinch roll of a continuous casting machine, which is provided with a means for varying the characteristics, the torque generated by the roller table driving electric motor is kept low by lowering the voltage-frequency characteristics of the inverter, As the casting is completed and the number of pinch rolls contributing to the pulling force is decreased, the voltage-frequency characteristic of the inverter is gradually increased to gradually increase the torque generated by the roller table driving electric motor. .

A roller table control device for continuous casting equipment of the present invention is a roller table control device for continuous casting equipment in which a group of rollers is driven by an induction motor driven by an inverter, wherein the output voltage-frequency characteristic of the inverter is variable. Means for detecting the position of the slab, and when the position of the slab detected by the detecting means is between the pinch rolls of the continuous casting machine, the voltage-frequency characteristic of the inverter is lowered. A means for gradually increasing the inverter voltage-frequency characteristic as the number of pinch rolls biting the slab decreases is provided.

[Action]

In the present invention, the V / F output characteristic of the inverter driven by the motor for the roller table is appropriately set according to the state of the slab in the pinch roll to control the driving force. That is, it has a function of varying the voltage-frequency characteristic (hereinafter referred to as V / F characteristic) of the inverter output as shown in FIG. That is, the − characteristic of FIG. 3 shows a high V / F characteristic,
The − characteristic shows a low V / F characteristic. This utilizes the fact that the torque of the induction motor is proportional to the square of the output voltage ratio at the same frequency.

During casting by tracking the trailing edge of the slab of the continuous casting machine, the V / F characteristic of the inverter is kept low and only torque is generated to supplement the mechanical loss of the roller table. After the start, the V / F characteristic of the inverter is gradually increased as the number of pinch rolls contributing to the transportation of the slab decreases.

This makes it possible to drive the roller table with a single power source, prevent a sudden change in torque during the pulling operation, and reduce the load on the final pinch roll.

〔Example〕

Hereinafter, the present invention will be specifically described based on the embodiments shown in the drawings.

FIG. 1 is a schematic view of a continuous casting facility equipped with a roller table control device according to the present invention. In the figure, the fifth
The same components as those of the conventional configuration shown in the figure are designated by the same reference numerals and the description thereof will be omitted.

In the present invention, the roller table driving electric motor 4-
A single inverter 10 is used as a power supply for driving 1 to 4-n.
Is used to change the V / F characteristic of the inverter 10 by the V / F control device 11. Fig. 4 shows V / F controller 1
1 shows an internal block diagram of 1 and an inverter 10.

During the casting operation, the output characteristic of V / F is lowered as indicated by the straight line in Fig. 3 so that the torque generated by the electric motor is about the level of the torque for replenishing the mechanical loss of the roller table. The frequency command is given so that the roller table and the pinch roll rotation speed become equal.

Next, as shown in FIG. 2, as the number of pinch rolls that come into contact with the slab 1 and give a pulling force decreases as casting ends and the tail end of the slab 1 passes through the pinch rolls. Gradually raise the V / F output characteristics toward the straight line − in Fig. 3. As a result, the roller table 3
Will gradually increase the driving force, contribute to the pulling force of the slab 1, and reduce the load on the pinch roll.

After the withdrawal of the slab 1 is completed and the slab 1 is transferred from the pinch roll to the roller table 3, the V / F output characteristic of the inverter 10 is operated with the characteristic of-in Fig. 3 to convey the slab 1. Drive force is generated.

The above-mentioned drawing mode starts from the end of casting of the slab 1, but the movement of the tail end of the slab 1 from the time when the operator switches to the drawing mode is detected by a pulse generator that detects the rotation of the measuring roll 12. Use the output of PG. That is, the measurement pulse output from the pulse generator PG is
When input to the V / F control device 11, it is possible to obtain the number of pinch rolls that come into contact with the slab 1 and contribute to conveyance. The number of pinch rolls in contact with the slab 1 is 3 → 2
→ As the number decreases to 1, the command to loosen the V / F lowering command,
That is, a command to increase the F / V command is issued. In the inverter 10, the calculation as shown in FIG. 4 is performed to generate the output frequency and the output voltage to be given to the inverter base driver.

In Fig. 4, 13 is a linear accelerator for preventing V / F sudden change, and 14
Is a pattern for determining gains 1 to 0 in response to a V / F lowering command (given at a voltage of 0 to 10 V, for example). Reference numeral 15 is a pattern for determining the motor rated voltage with respect to the rated frequency. The V / F pattern for obtaining the constant torque characteristic of the motor in the variable frequency range is set in the inverter. With this V / F pattern 15, the motor generates rated torque (torque for conveying the slab). Reference numeral 16 is a multiplier, and the voltage corresponding to the frequency command is determined by the table 15, and the value is multiplied by the V / F lowering gain determined by the table 14. Since the gain is 0 to 1, the output voltage is discounted (V / F is lowered).

During casting, the PLC gives the same value as the pinch roll speed command as the frequency command. The V / F lowering command is given from the V / F control device 11 so that the V / F gain becomes a value of 1 or less, for example, about 0.3. In this example, V / F lowering command 7V
Then, the gain becomes 0.3. This will reduce V / F by 30%.

When the tail end of the slab approaches, the PLC gives the same value as the speed command of the pinch roll as the frequency command. Gradually bring the V / F gain closer to 1 than 0.3. In this example, the V / F lowering command is lowered from 7V to 0V.

When the tail end of the slab comes out of the pinch roll, the roller table gives a speed command to independently convey the slab, regardless of the speed of the pinch roll, as a frequency command. The V / F lowering command is determined so that the V / F gain is 1, that is, the lowering command is 0V.

〔The invention's effect〕

As described above, in the present invention, since it is possible to drive the V / F characteristic in the inverter during casting to generate mechanical loss, it is necessary to use a low voltage power supply and a switch as in the prior art. do not do. Further, since the roller table is operated at the same speed as the pinch roll, the contact with the slab becomes smooth.

Since casting is completed so that the driving force of the roller table contributes to the pulling force of the pinch roll before the tail end of the cast piece exits the pinch roll, it has a relatively large capacity compared to other pinch rolls called pulling stands. In a continuous casting facility that is not equipped with a final drive roll, the final drive roll is not overloaded and a smooth drawing operation is possible.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an embodiment of the present invention, FIG. 2 is a schematic diagram showing a slab drawing state, FIG. 3 is a V / F characteristic diagram of an inverter according to the present invention, and FIG. 4 is a block inside the inverter. Figure,
FIG. 5 is a schematic view showing the structure of a conventional device. 1: Cast piece, 2: Pinch roll group 2-11 to 2-1n, 2-21 to 2-2n: Pinch roll 3: Roller table, 3-1 to 3-n: Roll 4-1 to 4-n: Roller table drive motor 10: Inverter, 11: V / F controller 12: Measuring roll 13: Linear accelerator 14: V / F lowering command pattern 15: V / F conversion pattern 16: Multiplier

Claims (2)

[Claims] 1. A roller table control method for a continuous casting facility in which a group of rollers is driven by an induction motor driven by an inverter, comprising means for varying output voltage-frequency characteristics of the inverter, and a pinch of the continuous casting machine. When the slab is cast by the roll, the voltage-frequency characteristics of the inverter is lowered to suppress the torque generated by the motor for driving the roller table to a low level, and the casting is completed,
A roller in a continuous casting facility, wherein the voltage-frequency characteristic of the inverter is gradually increased to gradually increase the torque generated by the roller table driving electric motor as the number of pinch rolls contributing to the drawing force is decreased. Table drive control method. 2. A roller table control device for continuous casting equipment in which a group of rollers is driven by an induction motor driven by an inverter, and means for varying the output voltage-frequency characteristic of the inverter and the position of the slab. Means for reducing the voltage-frequency characteristic of the inverter when the position of the slab detected by the detecting means is between the pinch rolls of the continuous casting machine, and pinching the bite of the slab. A roller table drive controller in a continuous casting facility, comprising means for gradually increasing the voltage-frequency characteristics of the inverter as the number of the rollers decreases.