JPH0299247A - Linear motor device for continuous casting machine and using method therefor - Google Patents

Abstract

PURPOSE:To reduce energy consumption and equipment cost by arranging linear motors so as to sandwich long sides of a flat nozzle, giving the prescribed frequency, current and voltage with inverter, etc., to improve power factor with a condenser. CONSTITUTION:Molten metal 2 in a tundish 1 is poured into a mold through the flat nozzle 3. One pair of the linear motors 3A, 3B are set so as to sandwich the long sides of the flat nozzle 3, and three phase AC is connected with these. A thyristor inverter 23, phase sequence changing circuit 22 and the condenser 21 for improving power factor executing bi-directional continuity control, arc connected with each phase line in three phase AC source circuit 24. Signal of a video camera 28 is inputted in a CPU 30, and continuity angle of the thyristor inverter 23 is changed, to control the molten metal surface level. As a leakage reactance is reduced and the power factor is compensated to high, the energy consumption and the equipment cost can be drastically reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to continuous casting, and more particularly to adjusting the amount of molten metal injected 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 from a ladle is supplied to the tundish. The amount of molten metal in tanditshu fluctuates, but in order to safely and stably obtain high-quality products,
The mold must be supplied with molten metal at a predetermined flow rate and the level of molten metal within the mold must be maintained at a predetermined value. Jitsukai 1977
In order to achieve such a problem, Japanese Patent Laid-Open No. 17619 and Japanese Patent Application Laid-Open No. 60-99458 provide a linear motor device that controls the amount of molten metal injected into a mold.

[Problem to be solved by the invention] The linear motor device of Utility Model Application Publication No. 44-17619 has the following problems:
The tundish is divided into two parts: a receiving part for receiving molten metal from the ladle and an outlet part for supplying the metal to the mold, the two are connected by a narrow passage, and a pair of linear motors are installed facing each other across this narrow passage. This linear mortar controls the supply rate of molten metal from the receiving section to the outflowing section at a constant rate. Tokukai 1986~
The linear motor device disclosed in Japanese Patent No. 99458 consists of a superconducting coil and a normal-conducting linear motor. A pair of superconducting coils are arranged across a wide channel of the molten metal channel from the tundish to the mold, and a pair of normal-conducting linear motors are arranged across a narrow channel that branches into two from the wide channel. There is.

A superconducting linear motor roughly (largely) adjusts the amount of molten metal injected into the mold, and a normal-conducting linear motor finely (finely) adjusts the amount of molten metal poured into the mold.

[Problem to be solved by the invention]

In the injection amount control of the above-mentioned Utility Model Application Publication No. 44-17619,
Since there is an outlet and a nozzle between the linear motor and the mold, the amount of molten steel retained there is relatively large.
The mold level control has a low speed of melting, and the injection amount control is relatively rough. In the injection amount control disclosed in JP-A-60-99458, a superconducting coil and a normal-conducting linear motor are placed between the tundish and the mold so that their magnetic fluxes do not influence each other, so that the injection amount from the tundish is The pouring nozzle between the molds becomes longer. Furthermore, since the tundish, mold, and their surroundings are at high temperatures, equipment for maintaining the superconducting humidity of the superconducting coil becomes difficult.

In any case, these conventional techniques have the problem that the power consumption of the linear motor is enormous, one large device is required to supply a huge amount of power, and the energy consumption is huge and the equipment cost is high.

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

[Means to solve the problem]

In the present invention, focusing on the fact that the electromagnetic force of the linear motor has a relatively small depth to the molten steel, the molten metal is moved from the tundish to a point where the long side in the Y direction is longer than the short side in the X direction. Focusing on a continuous casting machine that injects into the mold through a flat nozzle extending in the Z direction perpendicular to the X and Y directions,
A linear motor that generates an electromagnetic transfer force in the Z direction is installed along the long side of the flat nozzle. The linear motors have different phases. Although it is equipped with a power supply device to provide a voltage of a predetermined frequency for generating electromagnetic transfer force, the distance between the linear motor and the molten steel in the flat nozzle, that is, the gap, is large and the leakage reactance is large, so this increases the reactive power. In view of this, a capacitor for power factor improvement is connected to the linear motor to increase the power factor of the linear motor's power consumption.

Furthermore, an appropriate method for adjusting the propulsive force exerted on the molten steel in the nozzle is provided for the improved linear motor. In other words, consider the characteristics of a linear motor with a power factor correction capacitor, as described below.

The frequency of the current flowing through the linear motor is fixed at a predetermined value,
This is a method or control method of adjusting the current flowing to the linear motor or the voltage applied thereto via the inverter according to the propulsive force to be applied or the molten steel level deviation value.

[Effect]

Since the flat nozzle is equipped with a linear motor, the leakage reactance is reduced and the efficiency of the linear motor's electromagnetic force is increased.In addition, the power factor is highly compensated by the power factor correction capacitor, so the linear motor's Reactive power is significantly reduced. Therefore, the two linear motor drive devices can be of low capacity, and both energy consumption and equipment costs are significantly reduced. Furthermore, since the efficiency of the electromagnetic force of the linear motor is high and the efficiency of converting input power into electromagnetic force is high, the input power can be easily controlled and the injection amount can be controlled more accurately and stably.

Generally, there are two ways to adjust the electromagnetic force generated by a linear motor: adjusting the frequency f and adjusting the voltage or current. selected accordingly.

However, if the target linear motor is to be a special one, the control function should be determined based on more technical consideration based on the characteristics of the linear motor.

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

That is, in a continuous casting machine, the molten steel injected into the mold from the tundish has a flow velocity V in the nozzle of O~5 m1s.
ec, whereas the moving speed (also called synchronous speed) of the electromagnetic force in the molten steel flow direction generated by the linear motor placed across the nozzle (also called synchronous speed) is V.

becomes significantly large, for example, 72 rrr/sec.

Therefore, the slip S defined by (VoV)/Vo has a constant value of approximately 1.

By the way, in a normal induction rotary motor.

In order to make the forward thrust constant, by controlling the slip S x frequency f to be constant, even in the case of the above linear motor, if 5Xf = constant, the thrust force is applied to the molten steel in the nozzle. be stabilized.

Since S=l, Q, it was found that it is sufficient to fix the frequency f, so in the present invention, f is set to a predetermined value. Also,
In an electric circuit in which a power factor correction capacitor C is provided between a linear motor and an inverter as in the present invention, if the frequency f is made variable, the effect of the power factor correction capacitor C will fluctuate, so from this point of view as well, the frequency is fixed. It is desirable to do so.

Therefore, in the present invention, in order to make the propulsive force that the linear motor exerts on the molten steel in the nozzle variable, instead of adjusting one frequency f, it is fixed at a predetermined value and the current value flowing through the linear motor or the voltage value applied is adjusted. Adopt a method to do so.

In the case of a linear motor, when two of the three-phase current between the linear motor and the inverter are switched, the propulsive force exerted by the linear motor on the molten steel in the nozzle is reversed in the longitudinal direction of the nozzle, so the propulsive force is decelerated. It can generate not only force but also acceleration force.

Therefore, since the level control (or injection flow rate control) using the linear motor as the operating end has a wide control adjustment range, the control is quick and stable.

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 appearance of the continuous casting machine shown in the figure is shown.

The molten metal 2 of the tundish 1 is injected into the mold through a flat nozzle 3 having a rectangular cross section and narrow in the X direction and wide in the Y direction perpendicular to the plane of the paper. In this embodiment, the mold is a double belt mold, and the width of the long side of the flat nozzle 3 (in the Y direction)
Two moving casting belts 4 facing each other with a nozzle 3 in between and having a width wider than the width of the flat nozzle 3 (in the X direction) It is composed of 13 short sides.

The details of the movable short side 13 are presented in Japanese Patent Application No. 62-328080 and Japanese Patent Application No. 62-328082.

The casting belt 4 is stretched around a drive roller 5. The drive roller 5 is rotationally driven by a DC motor 7 via a speed reducer 6 at a predetermined speed. A finger speed generator (tachogenerator) 8 is connected to the motor 7 and generates an alternating current voltage with a frequency proportional to the rotational speed of the motor 7. This alternating current voltage is converted by the pulse processing circuit 11 into a pulse signal having a frequency proportional to the above frequency and having a constant pulse height and pulse width. The F/V converter 12 generates a voltage (speed voltage) at a level proportional to the frequency.

The motor driver 9 controls the target speed (voltage) given by the motor controller 10, the feedback speed (voltage) given by the F/V converter 12, and the armature current (
torque).

The armature current is adjusted so that the rotational speed of the motor 7 reaches the target speed. As a result, the motor 7 rotates at the target speed specified 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 facing 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 have a shape that is roughly the same as the stator of a three-phase star-connected induction motor, and the slots between the magnetic poles facing the rotor (molten steel in the nozzle 3) The coil is stored. By applying three-phase alternating current with a predetermined phase relationship to each phase coil, an electromagnetic transfer force (deceleration force) directed from bottom to top in the Z direction is generated in the molten steel in the nozzle 3, and the alternating current is applied to the two-phase electric coil. By changing the voltage, Z is applied to the molten steel in the nozzle 3.
It generates an electromagnetic transfer force (acceleration force) from top to bottom in the direction.

Each phase output line of the three-phase AC power supply circuit 24 is equipped with a thyristor inverter 2 that performs bidirectional conduction control for each of the five lines.
3 and the linear motor 3A via the phase sequence switching circuit 22.
, 3B are connected to each phase coil. The thyristor inverter 23 conducts the application of each phase AC voltage to the linear motors 3A and 3B when receiving a conduction trigger pulse from the thyristor driver 25 in the positive half wave and negative half wave of the AC voltage, respectively. , it becomes non-conductive at the zero-crossing point of the AC voltage.

A capacitor 21 for power factor improvement is connected to a connection line between each phase coil of the linear motors 3A, 3B and each phase line of the three-phase AC. In this example, in order to reduce the eddy current loss of the molten steel in the nozzle 3, the frequency of the three-phase alternating current is 100.
Since the range of ~500 Hz is preferable, it is set to 12011z. That is, the three-phase AC power supply circuit 24 has 12 output lines, which are shifted in phase by 120 degrees, for each of the three-phase output lines.
Outputs 0Hz AC voltage.

The power capacity of linear motor 3A + 3B is 120H7 and 2
, 800 KVA, and the capacitor 21 is correspondingly set to 2,800 KVA. Conventionally, there is no power factor correction capacitor, so the required capacity of the inverter 23 is 2,
However, by connecting the capacitor 21, the capacity of the inverter 23 is 1,200KVA.
This makes the power supply equipment cost much lower.

FIG. 5 shows the relationship between the energizing current of the linear motors 3A and 3B and the deceleration rate. As shown in Fig. 1, this occurs when the phase sequential switching circuit 22 is set to "deceleration", and as the linear motor current increases, the molten steel injection speed decreases (the scene level of the mold increases). ).

When the relay driver 27 is energized and the relay contact of the phase sequential switching circuit 22 is driven downward, the "acceleration" setting is set, and as the linear motor current increases, the molten steel injection speed increases (!8 type scene) level increases).

In addition, in FIG. 5, the horizontal axis represents the linear motors 3A, 3.
The energizing current value of B is shown, and the vertical axis is the molten steel speed Von when there is drive by the linear motor with respect to the molten steel speed Voff in the nozzle 3 when there is no drive by the linear motor.
shows the ratio Vr.

Referring again to FIG. 1, below the linear motor 3A there is a hot water level (distance of the scene from the video camera 28) L.
A video camera 28 is installed to detect d, and this takes an image of the portion of the movable short side 13 that is in contact with the scene, and provides a video signal to the signal processing circuit 29. The signal processing circuit 29 uses color image data processing to cut out the tangent line between the scene and the moving short side (the area that is a high-temperature color on the screen where the inner surface of the moving short side is imaged), and determines its position at the top or bottom of the screen. The distance Ld is determined by determining the position in the direction, and the data indicating this is sent to a microprocessor (hereinafter referred to as CP).
(referred to as U) 30. The CPU 30 receives a start/end signal, data indicating the target injection speed (velocity at the nozzle 3) vo, and the target level L from a host computer or operation panel (not shown). (target value of the distance of the hot water surface from the video camera 28) is given, and the frequency divider 31 gives a pulse obtained by frequency-dividing the pulse indicating the speed (the output pulse of the pulse processing circuit 11).

Referring again to FIG. 1, below the linear motor 3A there is a hot water level (distance of the hot water level from the video camera 28) L.
A video camera 28 is installed to detect d, and this takes an image of the portion of the movable short side 13 that is in contact with the hot water surface, and provides a video signal to the signal processing circuit 29. The signal processing circuit 29 uses color image data processing to extract a tangent line between the hot water surface and the moving short side (which appears in a high-temperature color on a screen capturing an image of the inner surface of the moving short side), and locates the tangent line above the screen.

The distance Ld is calculated by determining the position in the downward direction, and the data indicating this is sent to the microprocessor (hereinafter referred to as CPU).
30). The CPU 30 receives a start/end signal, data indicating the target injection speed (velocity at the nozzle 3) Vo, and the target level L from a host computer or operation panel (not shown). (target value of the distance of the hot water surface from the video camera 28) is given, and the frequency divider 31 gives a pulse obtained by frequency-dividing the pulse indicating the speed (the output pulse of the pulse processing circuit 11).

The CPU 30 calculates the deviation dL of the detection level Ld provided by the signal processing circuit 29 with respect to the target level I-o, and performs PI control calculation based on this.

Injection speed v of molten steel into the mold to make the deviation dL zero
i is calculated, the linear motor current value for obtaining this speed vj is calculated, and this is converted into the conduction angle (phase angle when turned on) of the cyrisk converter 23, and voltage data Vf indicating the conduction angle is obtained. It is applied to the D/A converter 26. D/
A converter 26 converts data Vf into analog voltage Vf and supplies it to 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, starting from the zero crossing point, and compares this with the analog voltage Vf, so that when the former reaches the latter A trigger pulse is generated and applied to the gate of the thyristor of the converter 23. When the thyristor receives this trigger pulse, it becomes conductive and becomes non-conductive at the next zero crossing point.

The control operation of the CPU 30 is shown in FIGS. 4a and 4b. Reference is first made to FIG. 4a. When the power is turned on (step 1: hereinafter, the word step is omitted in parentheses), the CPU 30 sets the input/output board to the signal level of the standby state, clears the internal registers, counters, timers, etc. Give a "ready" signal to the computer or operation panel, and then wait for control data (data that determines control parameters such as calculation constants and timing constants) and a start signal to be sent. When control data is sent, it is read and stored in a predetermined register (internal RAM).
) (2,3).

When the start signal arrives, enable the 5 interrupt INT4)
, starts timer To (a program timer that takes a time limit of time To) and waits for timer To to time out (5
, 6).

By allowing 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 T is activated.

(10), the CPU 30 reads the hot water level detection level Ld and the hot water level target level LO (11, 12), calculates the deviation dL, and writes it to the register Acd ( 13°14). Multiply the deviation dL by the proportionality constant Kp and write it to register Ac3 (15)
. Next, the data in the integration registers R1 to Rn is set to Rn-1.
write the data of R,n-2 to Rn-
1, discard the oldest data (in Rn), move the remaining data to registers R2 to Rn, and write (
16 to 18), write the value obtained by multiplying the deviation dL by the integral constant by 1 into the empty register R1 (19). Then, the sum of the data in registers R1 to Rn (integrated amount of correction values) is taken and written to register Ac4 (20).

Then, the required speed vi of the molten steel in the nozzle 3, which is the output value of the PI control, is calculated (21). Next, the target speed v in the nozzle 3
Required speed vi for o (proportional to 1e construction target speed)
Calculate the ratio Vr and write it to register A C5 (22)
, from the data table written in advance to internal memory,
The linear motor current data Ii corresponding to Vr is read out and written to the register A c 6 (23). Next, the current Ii
The conduction phase angle data Vf that causes
7 (24). Then, it is determined whether the data in the register and Ac4 (correction amount for the target speed vo) is positive or negative (25), that is, whether the linear motor should be accelerated or decelerated. , outputs H to the relay driver 27 (27). As a result, the relay contacts of the phase-sequential switching circuit 22 are driven downward, and the linear motors 3A and 3B are connected to the inverter 23 for acceleration (downward drive in the Z direction). In the case of negative (deceleration), L is output to the relay driver 27 (26). As a result, the relay contacts of the phase sequential switching circuit 22 are in 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 CPU30
updates and outputs the data Vf of the register A c 7 to the D/A converter 26 (28). As a result of the above, the driving direction and driving force of the linear motors 3A and 3B have been corrected in accordance with the detected value Ld.

The interrupt processing described above is executed every time the frequency divider 31 generates one pulse, and the integrated value of the deviation value obtained in each of the past n interrupt processing is written in the register Ac4. It's included.

The time limit value To of the timer To is slightly longer than the period Tl11 of the pulses generated by the branching unit 31 when the continuous machine shown in FIG. 2 is at its designed minimum speed. Therefore, DC motor 7° tacho generator 8. If the pulse processing circuit 11 and frequency divider 31 are normal,
Since the frequency divider 31 generates a pulse before the timer To times out, the timer To never times out.

Therefore, in the steady state, the interrupt process shown in FIG. 4b is repeatedly executed.

If, due to some abnormality, the frequency divider 31 does not generate a pulse even once during To, the 1 interrupt process (Figure 4b) will not be executed, the timer To will time out, and the CPU 30 will not proceed to step 6 in Figure 4a. Proceeding to step 30, an alarm signal is given to the host computer or operation panel (30). Then, start (restart) timer To (31), read the input (A), calculate the PI sub-control output value (B), calculate the 2-phase angle (C), calculate the drive direction (D), and output (E ) and timer T. wait for timeout. These processes (
The contents of A-E) are steps 11 to 28 shown in Figure 4b.
The processing content is the same as that of . Therefore, for example, when the frequency divider 31 stops generating pulses at all, the above-described process is executed in the same period as To.

The reason why the PI sub-control sampling period is determined by the pulses generated by the frequency divider 31 is that when the casting speed is high, the sampling period is shortened in inverse proportion to the casting speed. In an abnormal situation where the frequency divider 31 no longer generates pulses, the sampling period is To, which is a relatively long constant value.

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

In the above embodiments, a thyristor inverter was used as the power adjustment means 23, but the present invention does not need to be limited to a thyristor inverter; for example, an AC-*D
The same effect can be achieved even if various methods such as a C+AC inverter method are employed, so any method may be used.

〔Effect of the invention〕

As described above, in the present invention, since the flat nozzle is equipped with a linear motor, the leakage reactance is reduced and the efficiency of the electromagnetic force of the linear motor is increased.In addition, the power factor correction capacitor compensates for the high power factor. Therefore, the reactive power of the linear motor is significantly reduced. Therefore, the two linear motor drive devices can be of low capacity, and both energy consumption and equipment costs are significantly reduced. Furthermore, since the efficiency of the electromagnetic force of the linear motor is high and the efficiency of converting input power into electromagnetic force is high, the input power can be easily controlled and the injection amount can be controlled more accurately and stably.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention. FIG. 2 is a perspective view showing the appearance of the continuous casting machine shown in FIG. 1. FIG. 3 is a perspective view showing the appearance of the linear motors 3A and 3B shown in FIG. 1. 4a and 4b are flowcharts showing the control operation of the microprocessor 30 shown in FIG. 1. FIG. FIG. 5 is a graph showing the relationship between the current value of the linear motors 3A and 3B and the speed of molten steel in the nozzle 3. ■ = Tanditshu (Tanditshu) 2: Molten steel
3: Flat nozzle (flat nozzle) 3A, 3
B: Linear motor (linear motor) 3As, 3Bs:
Stator core 3Ac, 3Bc: Electric coil 4: G-made belt 5: Drive roller 6: Reducer
7: DC motor 8: Tacho generator
9: Motor driver 10: Motor controller 11: Pulse processing circuit 12: F/VD',
t-verter 13: Moving short side 15: Cooling pad 16: Small diameter divided roll 17: Slab 21: Capacitor (capacitor for improving the power factor of linear motor) 22
: Phase sequence switching circuit (phase switching means) 23: Cyrisk inverter (power adjustment means) 24:3
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: Hot water level detection means)
30: Microprocessor voice 2 figure voice 4a figure

Claims (4)

[Claims] (1) In a continuous casting machine, molten metal is injected into a mold from a tundish through a flat nozzle whose long side in the Y direction is wider than the short side in the X direction and extends in the Z direction. Linear motors that are arranged to sandwich and generate electromagnetic transfer force in the Z direction along the long sides; for applying a predetermined voltage or current with a predetermined frequency and mutually different phases for generating electromagnetic transfer force to the linear motor; A linear motor device for a continuous casting machine, comprising: a power supply device; and a capacitor for improving a linear motor power factor connected to an electric line between the power supply device and the linear motor. (2) A power adjustment means for adjusting at least one of the voltage and current applied to the linear motor is inserted between the power supply device and the linear motor, and the power is applied to the molten metal in the flat nozzle through the power adjustment means. A method of using the 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 acceleration and deceleration forces in the Z direction. (3) A power adjustment means for adjusting at least one of the voltage and current applied to the linear motor 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 detection means, and the power is adjusted. According to the above-mentioned claims, at least one of the voltage and current of the linear motor is adjusted through means in a direction that reduces the deviation in response to the deviation between the molten steel level detected by the molten metal level detection means and the target value. A method of using the linear motor device described in paragraph (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, the molten steel level in the mold is detected by the molten metal level detection means, and the electric power is The direction of the electromagnetic transfer force is determined via the phase switching means in a direction that reduces the deviation between the molten steel level detected by the molten metal level detection means and the target value via the adjustment means, in response to the deviation between the molten steel level detected by the molten steel level detection means and the target value. A method of using the linear motor device according to claim (1).