JPH0649220B2 - Linear motor device of continuous casting machine and control method thereof - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to continuous casting, and more particularly to adjustment of molten metal injection amount into a continuous casting mold.

[Conventional technology]

Molten metal is supplied to the continuous casting mold from a tundish through a nozzle, and molten metal in a ladle is supplied to the tundish. The amount of molten metal in the tundish fluctuates, but in order to safely and stably obtain high quality products, the molten metal is supplied to the mold at a predetermined flow rate and the level of the molten metal in the mold is maintained at a predetermined value. There is a need. Akira Kaikai
In order to achieve such a subject, 44-17619 and JP-A-60-99458 provide a linear motor device for controlling the injection amount of molten metal into a mold.

[Problems to be Solved by the Invention]

In the linear motor device disclosed in Japanese Utility Model Publication No. 44-17619, a tundish is divided into two parts, a receiving part for receiving molten metal from a ladle and an outflow part for supplying the molten metal to a mold, and connecting both with a narrow passage. A pair of linear motors are installed to face each other across the narrow passage, and the linear motors control the supply speed of the molten metal from the receiving portion to the outflow portion to be constant. The linear motor device disclosed in JP-A-60-99458 is a superconducting coil and a normal conducting linear motor. A pair of superconducting coils are arranged across the wide flow path of the molten metal flow path from the tundish to the mold, and a pair of normal conduction linear motors are arranged across the narrow flow path branched from the wide flow path into two. ing. The superconducting linear motor adjusts the amount of molten metal injected into the mold roughly (largely),
Finely adjusted by normal conducting linear motor.

[Problems to be Solved by the Invention]

In the injection amount control of Japanese Utility Model Laid-Open No. 44-17619, since there is an outflow part and a nozzle from the linear motor to the mold, the molten steel strip distillation amount there is relatively large. Is low, and the injection amount control is relatively coarse. In the injection amount control of JP-A-60-99458, the superconducting coil and the normal conducting linear motor are arranged between the tundish and the mold so that their magnetic fluxes do not affect each other. The pouring nozzle between the dish and the mold becomes longer. Further, since the tundish, the mold, and their surroundings are hot, the equipment for maintaining the superconducting temperature of the superconducting coil becomes difficult.

In any case, these conventional techniques have a problem that the electric power consumption of the linear motor becomes enormous, a large-sized device and equipment for enormous electric power supply are required, the energy consumption is enormous, and the equipment cost is high.

An object of the present invention is to reduce energy consumption and equipment cost and to control the injection amount into a mold quickly and stably.

[Means for Solving the Problems]

In the present invention, paying attention to the fact that the electromagnetic force of the linear motor with respect to molten steel is relatively shallow, the molten metal is longer than the tundish, and the long side in the Y direction is longer than the short side in the X direction. Paying attention to a continuous casting machine which injects into a casting through a flat nozzle extending in the Z direction perpendicular to the X direction and the Y direction,
A linear motor that generates an electromagnetic transfer force in the Z direction is installed along the long side of the flat nozzle with the long side interposed. The linear motor is provided with a power supply device for applying a voltage of a predetermined frequency for generating an electromagnetic transfer force, which is out of phase with each other, but the distance between the linear motor and the molten steel in the flat nozzle, that is, the air gap is large and the leak reactance is large. Is large,
In view of the fact that these increase the reactive power, a capacitor for power factor improvement is connected to the linear motor to increase the power factor of the linear motor power consumption.

Further, it provides an appropriate method for adjusting the propulsive force exerted on the molten steel in the nozzle for the improved linear motor. That is, in consideration of the characteristics of a linear motor with a power factor improving capacitor, which will be described later, the frequency of the current flowing through the linear motor is fixed to a predetermined value, and an inverter is used according to the propulsive force or molten steel level deviation value to be given. Is a method or a control method for adjusting the current or the voltage applied to the linear motor.

[Action]

Since the flat nozzle is equipped with a linear motor, the leakage reactance is reduced, the electromagnetic motor's action efficiency is increased, and the power factor is corrected by the power factor improving capacitor. Reactive power is greatly reduced. Therefore, the linear motor drive device and equipment need only have a low capacity, and both energy consumption and equipment cost are greatly reduced. Furthermore, since the electromagnetic motor has a high electromagnetic force operation efficiency and a high conversion efficiency of the input power to the electromagnetic force, the control of the input power is facilitated and the injection amount control can be performed more accurately and stably.

Generally, in order to adjust the electromagnetic force generated by the linear motor, there are two methods of adjusting the frequency f and adjusting the electric power or the electric current.
It is selected according to weight, price, etc.

However, when the target linear motor is made special, it should be determined more technically in consideration of the control function according to its characteristics.

Therefore, in the present invention, the following studies and recognitions were made in order to solve the above problems.

That is, in the continuous casting machine, the molten steel injected into the mold from the tundish has a flow velocity V of 0 to 5 m / sec in the nozzle, while the electromagnetic force generated by the linear motor placed across the nozzle is The moving speed Vo (also called synchronous speed) Vo in the molten steel flow direction becomes extremely large, for example, 72 m / sec. Therefore, the slip S defined by (Vo-V) / Vo has a constant value of approximately 1.

By the way, in an ordinary induction type rotary motor, in order to make the propulsive force constant, by controlling the slip S × frequency f to be constant, even in the case of the linear motor described above, S × f = constant, Then, the driving force that acts on the molten steel in the nozzle can be stabilized. And since S = 1.0, the frequency f
Since it has been found that it is only necessary to fix f, in the present invention, f is set to a predetermined value. Further, in the electric circuit in which the power factor correction capacitor C is provided between the linear motor and the inverter as in the present invention, the effect of the power factor correction capacitor C fluctuates when the frequency f is made variable. Is preferably fixed.

Therefore, in the present invention, in order to make the propulsive force exerted on the molten steel in the nozzle by the linear motor variable, the frequency f is not adjusted but fixed at a predetermined value and the current value or the applied voltage value flowing in the linear motor is adjusted. Adopt the method of doing.

In the case of a linear motor, when two phases of the three-phase current between the linear motor and the inverter are switched, the propulsive force exerted on the molten steel in the nozzle by the linear motor works upside down in the longitudinal direction of the nozzle. Not only force but also acceleration force is generated.

Therefore, in the molten metal level control (or the injection flow rate control) using the linear motor as the operation end, the control is quick and stable because the control adjustment range is wide.

Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.

〔Example〕

FIG. 1 shows the configuration of an embodiment of the present invention, and FIG.
The outline of the continuous casting machine shown in the figure is shown. The molten metal 2 of the tundish 1 is poured into the mold through a flat nozzle 3 having a narrow cross section in the X direction and a wide width in the Y direction perpendicular to the paper surface and having a rectangular cross section. The mold is a twin-belt mold in this embodiment, and two casting belts 4 having a width wider than the width of the long side of the flat nozzle 3 (Y direction) and facing each other with the nozzle 3 in between.
And the two movable short sides 13 facing each other across the nozzle 3 and having a thickness wider than the width (X direction) of the short side of the flat nozzle 3.

The moving short side 13 is shown in detail in Japanese Patent Application Nos. 62-328080 and 62-328082.

The casting belt 4 is stretched around a driving roller 5. The drive roller 5 is rotationally driven at a predetermined speed by a DC motor 7 via a speed reducer 6. A finger speed generator (tachogenerator) 8 is connected to the motor 7 and generates an AC voltage having a frequency proportional to the rotation speed of the motor 7. The AC voltage is converted by the pulse processing circuit 11 into a pulse signal having a frequency proportional to the frequency and having a constant pulse height and pulse width. The F / V converter 12 generates a voltage (speed voltage) of a level proportional to the frequency. The motor driver 9 includes a target speed (voltage) given by the motor controller 10, a feedback speed (voltage) given by the F / V converter 12, and an armature current (torque) of the motor 7.
Based on, the armature current is adjusted so that the rotation speed of the motor 7 becomes the target speed. As a result, the motor 7 rotates at the target speed designated by the motor controller 10.
That is, the belt 4 moves at the target speed.

A pair of linear motors 3A and 3B are installed to face each other across the long side (Y direction) of the flat nozzle 3. The relationship between these linear motors and the flat nozzle 3 is shown in FIG.

In this embodiment, the linear motors 3A and 3B each have a shape in which a stator of an induction motor having a three-phase star-shaped connection is developed in a plane, and each phase is formed in a slot between magnetic poles facing a rotor (molten steel in the nozzle 3). The coil is stored. By applying a three-phase alternating current with a predetermined phase relationship to each phase coil,
An electromagnetic transfer force (deceleration force) is generated in the molten steel in the nozzle 3 from the bottom to the top in the Z direction, and by alternating the AC voltage applied to the two-phase electric coil, the molten steel in the nozzle 3 is moved upward in the Z direction. Generates electromagnetic transfer force (acceleration force) that goes downward from.

Each phase output line of the three-phase AC power supply circuit 24 has a thyristor inverter 2 that performs bidirectional conduction control for each line.
3 and the phase-order switching circuit 22, the linear motor 3
The phase coils of A and 3B are connected. The thyristor inverter 23 is a linear motor of each phase AC voltage, 3A, 3B
When the conduction trigger pulse is received from the thyristor driver 25 with each of the positive half-wave and the negative half-wave of the AC voltage, the application of the voltage is conducted, and the application is turned off at the zero-cross point of the AC voltage.

A power factor improving capacitor 21 is connected to a connection line between each phase coil of the linear motors 3A and 3B and each phase line of the three-phase AC. In this embodiment, in order to reduce the eddy current loss of the molten steel in the nozzle 3, the frequency of the three-phase AC is 100-5.
Since the range of 00Hz is preferable, it is set to 120Hz. That is, the three-phase AC power supply circuit 24 outputs an AC voltage of 120 Hz with a phase difference of 120 ° to each of the three-phase output lines. The power capacity of the linear motor 3A + 3B is 2,8 at 120Hz.
It is 00KVA, and the capacitor 21 is 2,800KV corresponding to this.
A. Conventionally, since there is no power factor improving capacitor, the required capacity of the inverter 23 is 2,800 KVA.
The capacity is 1,200KVA, which is significantly smaller, which greatly reduces the cost of power supply equipment.

FIG. 5 shows the relationship between the energizing currents of the linear motors 3A and 3B and the deceleration rate. This is when the phase sequence switching circuit 22 is set to "deceleration" as shown in FIG. 1, and the molten steel injection speed becomes lower as the linear motor current is increased. (The surface level of the mold is lowered).

When the relay driver 27 is energized to drive the relay contact piece of the phase sequence switching circuit 22 downward, the setting is "acceleration", and the molten steel injection speed increases as the linear motor current increases. (Mold level rises).

In FIG. 5, the horizontal axis represents the linear motors 3A and 3A.
The value of the energizing current of B is shown, and the vertical axis represents the molten steel velocity Voff in the nozzle 3 when there is no drive by the linear motor,
Ratio of molten steel velocity Von when driven by a linear motor
Indicates Vr.

Referring again to FIG. 1, below the linear motor 3A, the level of the molten metal (distance of the molten metal from the video camera 28)
A video camera 28 for detecting Ld is installed, which picks up an image of a portion of the moving short side 13 in contact with the molten metal surface and supplies a video signal to the signal processing circuit 29. The signal processing circuit 29 cuts out a tangent line between the molten metal surface and the moving short side (a place where a high-temperature color appears on the screen where the inner surface of the moving short side is imaged) by color image data processing, and the position is on the screen. The position L in the downward direction is determined to calculate the distance Ld, and the data indicating this is calculated using a microprocessor (hereinafter CP
(Referred to as U) 30. In the CPU 30, a start / end signal, data indicating a target injection speed (speed at the nozzle 3) vo, and a target level Lo (a target value of the distance from the video camera 28 to the molten metal surface) are supplied from a host computer (not shown) or a control panel. And a pulse obtained by dividing the pulse indicating the speed (output pulse of the pulse processing circuit 11) from the frequency divider 31.

Referring again to FIG. 1, below the linear motor 3A, the level of the molten metal (distance of the molten metal from the video camera 28)
A video camera 28 for detecting Ld is installed, which picks up an image of a portion of the moving short side 13 in contact with the molten metal surface and supplies a video signal to the signal processing circuit 29. The signal processing circuit 29 cuts out a tangent line between the molten metal surface and the moving short side (a high temperature color is displayed on the screen where the inner surface of the moving short side is imaged) by the color image data processing, and the position is located above and below the screen. The position in the direction is determined to calculate the distance Ld, and the data indicating this is calculated using a microprocessor (hereinafter CP
(Referred to as U) 30. In the CPU 30, a start / end signal, data indicating a target injection speed (speed at the nozzle 3) vo, and a target level Lo (a target value of a distance from the video camera 28 to the molten metal surface) are supplied from a host computer (not shown) or an operation panel. Is given, and from the frequency divider 31,
Pulse indicating speed (output pulse of pulse processing circuit 11)
A pulse obtained by dividing is given.

The CPU 30 uses the signal processing circuit 29 for the target level Lo.
The deviation dL of the detection level Ld given by is calculated, and based on this, the PI control calculation is performed to calculate the injection speed vi of the molten steel into the mold for making the deviation dL zero, and to obtain this speed vi. The linear motor energization current value is calculated and converted into a conduction angle (a phase angle to be turned on) of the thyristor converter 23, and the voltage data Vf indicating the conduction angle is converted into the D / A converter 2.
Give to 6. The D / A converter 26 converts the data Vf into an analog voltage Vf and gives it to the thyristor driver 25. The thyristor driver 25 generates a voltage that gradually increases in proportion to the increase in the AC voltage phase for each of the three phases with the zero-cross point as the base point, compares this voltage with the analog voltage Vf, and when the former reaches the latter, A trigger pulse is generated and applied to the gate of the thyristor of converter 23. Upon receipt of this trigger pulse, the thyristor becomes conductive and becomes non-conductive at the next zero cross point.

The control operation of the CPU 30 is shown in FIGS. 4a and 4b. First, refer to FIG. 4a. Power is turned on (Step 1: Hereafter, the word step is omitted in parentheses)
And the CPU 30 set the input / output port to the signal level in the standby state, clear the internal registers, counters, timers, etc., and give a "ready" signal to the host computer or operation panel, and then control data (calculation constant). , Wait for the start signal to be sent and the data that defines the control parameters such as timing constants). When the control data is sent, it is read and the specified register (internal RA
Write in M) (2, 3).

When the start signal arrives, enable the interrupt INT (4),
A timer To (a program timer that takes a time period of time To) is started and waits for the timer To to expire (5, 6).

By permitting the interrupt INT, the CPU 30 executes the interrupt process shown in FIG. 4b every time the frequency divider 31 generates one pulse. To explain this, when the frequency divider 31 generates one pulse, the timer To is started (restarted) (10), and the CPU 30 reads the molten metal surface detection level Ld and the molten metal surface target level Lo (11, 12). ). Then, the deviation dL is calculated, and this is written in the register Acd (13, 14).
The deviation dL is multiplied by the proportional constant Kp and written in the register Ac ₃ (15). Next, the data in the integration register R ₁ ~Rn of Rn, writes data Rn _-1 to Rn, the data of Rn _-2 so on writing to Rn _-1, the oldest (in Rn) Data Discard and move the remaining data to registers R _{2 to} Rn (16 to 1
8) Then, write the value obtained by multiplying the deviation dL by the integration constant Ki into the vacant register R ₁ (19). Then, the sum total of the data of the registers R _{1 to} Rn (the integrated amount of the correction value) is obtained and written in the register Ac ₄ (20). And the nozzle 3 which is the output value of PI control
The in-molten steel required speed vi is calculated (21). Next, the nozzle 3
The ratio Vr of the required speed vi to the internal target speed vo (proportional to the casting target speed) is calculated and written in the register Ac ₅ (2
2) The linear motor current data Ii corresponding to Vr is read from the data table previously written in the internal memory and written in the register Ac ₆ (23). Next, the conduction phase angle data Vf that causes the current Ii is read from the data table previously written in the internal memory and written in the register Ac ₇ (24). Then register and Ac ₄ data (target speed vo
Is corrected (25), that is, it is determined whether the linear motor should be accelerated or decelerated, and if it is positive (accelerated), H is output to the relay driver 27 ( 27). As a result, the relay contact of the phase sequence switching circuit 22 is driven downward, and the linear motors 3A and 3B are connected to the inverter 23 for acceleration (driving downward in the Z direction). If negative (deceleration), relay driver 27
L is output to (26). Thereby, the phase sequence switching circuit 22
1 becomes the position shown in FIG. 1, and the linear motors 3A and 3B are connected to the inverter 23 for deceleration (upward drive in the Z direction). Next, the CPU 30 uses the register Ac
The data Vf of ₇ is updated and output to the D / A converter 26 (28). As described above, the driving directions and the driving forces of the linear motors 3A and 3B are corrected corresponding to the detected value Ld.

The interrupt processing described above is executed every time the frequency divider 31 generates one pulse, and the register Ac ₄ stores the integrated value of the deviation values obtained in the respective past n interrupt processings. It is written.

The time limit value To of the timer To is a time slightly longer than the period Tm of the pulse generated by the frequency divider 31 at the designed minimum speed of the continuous casting machine shown in FIG. Therefore, when the DC motor 7, the tachogenerator 8, the pulse processing circuit 11, and the frequency divider 31 are normal, the frequency divider 31 generates a pulse before the timer To times out, so the timer To times out. There is no such thing. Therefore, in the steady state, the interrupt process shown in FIG. 4b is repeatedly executed.

If the frequency divider 31 does not generate a pulse even once during To due to some abnormality, the interrupt process (FIG. 4b) is not executed, the timer To times out, and the CPU 30 causes the CPU 30 to execute step 6 in FIG. 4a. Then, in step 30, the alarm signal is given to the host computer or the operation panel (30). And timer To
(31) to start (restart), execute input reading (A), PI control output value calculation (B), phase angle calculation (C), drive direction calculation (D) and output (E). And wait for the timer To to expire. These processes (A
To E) are the same as the processing contents of steps 11 to 28 shown in FIG. 4b. Therefore, for example, the frequency divider 3
When 1 does not generate any pulse, the above process is executed in the To cycle.

The pulse generated by the frequency divider 31 determines the PI control sampling period in order to shorten the sampling period in inverse proportion to the sampling period when the casting speed is high. When the frequency divider 31 does not generate a pulse, the sampling cycle is To, which is a relatively long constant value.

When the end signal arrives from the host computer or the operation panel (7), the CPU 30 returns to the initialization (2). That is, the standby state (linear motor stop) is entered.

In the above embodiments, the example of the thyristor inverter was described as the power adjusting means 23, but the present invention is not particularly limited to the thyristor inverter, and for example AC → DC.
→ Even if various methods such as an AC inverter method are adopted, the same effect can be exhibited, so any method may be used.

〔The invention's effect〕

As described above, in the present invention, since the flat nozzle is equipped with the linear motor, the leakage reactance is reduced, the action efficiency of the electromagnetic force of the linear motor is increased, and the power factor correction capacitor compensates for the high power factor. Therefore, the reactive power of the linear motor is significantly reduced. Therefore, the linear motor drive device and equipment can be of low capacity, and the energy consumption and equipment cost can be greatly reduced. Furthermore, since the electromagnetic motor has a high electromagnetic force operation efficiency and a high conversion efficiency of the input power to the electromagnetic force, the control of the input power is facilitated and the injection amount control can be performed more accurately and stably.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention. FIG. 2 is a perspective view showing the appearance of the continuous casting machine shown in FIG. FIG. 3 is a perspective view showing the appearance of the linear motors 3A and 3B shown in FIG. 4a and 4b are flow charts showing the control operation of the microprocessor 30 shown in FIG. FIG. 5 is a graph showing the relationship between the current values of the linear motors 3A and 3B and the speed of the molten steel in the nozzle 3. 1: Tundish (Tundish) 2: Molten steel 3: Flat nozzle (flat nozzle) 3A, 3B: Linear motor (linear motor) 3As, 3Bs: Stator core 3Ac, 3Bc: Electric coil 4: Cast belt, 5: Drive roller 6: Reducer, 7: DC motor 8: Tachogenerator, 9: Motor driver 10: Motor controller, 11: Pulse processing circuit 12: F / V converter, 13: Moving short side 15: Cooling pad 16: Small diameter split roll, 17 : Slab 21: Capacitor (capacitor for improving power factor of linear motor) 22: Phase sequence switching circuit (phase switching means) 23: Thyristor inverter (power adjusting means) 24: Three-phase AC power supply circuit (power supply device) 25: Thyristor driver, 26: D / A converter 27: Relay driver, 28: Video camera 29: Signal processing circuit (28,29: bath level detection means) 30: Microprocessor

Front page continuation (72) Akira Hashimoto, Inventor, Oita City, Oita City, 1st Nishinosu, Nippon Steel Co., Ltd. Inside the Oita Works (72) Inventor, Hidetoshi Yuyama, Oita City, Oita Prefecture, 1st Nishinosu Steel Company, New Japan Oita Works (72) Inventor Noriyuki Kanai No. 1 Nishinosu, Oita City, Oita Prefecture Nippon Steel Co., Ltd. Stock Company Oita Works

Claims (4)

[Claims] 1. A long side in the Y direction is wider than a short side in the X direction by Z.
Of a continuous casting machine that injects molten metal from a tundish into a mold through a flat nozzle that extends in the direction, and is arranged with the long side of the flat nozzle sandwiched in between, and generates an electromagnetic transfer force in the Z direction along the long side. A linear motor; a power supply device for giving a predetermined voltage or current to the linear motor, the phases of which are different from each other for generating electromagnetic transfer force; and an electric line between the power supply device and the linear motor. A linear motor device of a continuous casting machine, comprising: a connected capacitor for improving the linear motor power factor. 2. A power adjusting means for adjusting at least one of a voltage and a current applied to the linear motor is interposed between the power supply device and the linear motor, and the molten metal in the flat nozzle is inserted through the power adjusting means. The method for controlling a linear motor device according to claim (1), wherein the amount of molten metal injected from the flat nozzle into the mold is adjusted by adjusting the Z direction acceleration / deceleration force. 3. A power adjusting means for adjusting at least one of voltage and current applied to the linear motor is interposed between the power supply device and the linear motor, and the molten steel level in the mold is detected by the molten metal level detecting means, The at least one of the voltage and the current of the linear motor is adjusted in a direction in which the deviation decreases in accordance with the deviation between the molten steel level detected by the molten metal level detection means and the target value via the electric power adjustment means. The method for controlling the linear motor device according to the range (1). 4. A phase switching means for switching the direction of the electromagnetic transfer force of the linear motor between forward and reverse is inserted between the power supply device and the linear motor, and the molten steel level in the mold is detected by the molten metal level detecting means. , The direction of the electromagnetic transfer force is determined in a direction to reduce the deviation via the phase switching means in response to the deviation between the molten steel level detected by the molten metal level detection means and the target value via the electric power adjustment means. The method for controlling a linear motor device according to claim (1).