JPH0445259B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an improvement in a method for controlling slab drawing speed in continuous casting equipment.

[Conventional technology]

FIG. 1 shows a cross-sectional view of a known slab drawing device, in which molten steel is poured from a ladle 1 through a tundish 2 into a mold 3, where it is cooled and solidified to become a slab. Then, the slab 4 is pulled out by non-driving rolls (marked with a circle) placed on both sides of the passageway and drive rolls (marked with a circle) that are driven by an electric motor, and is pulled out from the roller table 7.
is transported to.

FIG. 2 shows a conventionally known control circuit for driving each of the drive rolls by a dedicated drive control device, and its structure and operation will be explained as follows.

That is, in the conventional method, a common speed command signal Vs obtained by inputting the casting speed setting value from the speed setting device 11 to the linear command device 12, and a speed detection pulse generator PLG ₁ connected to the electric motor are used.
The deviation between the output signal _of A method was adopted in which the speed of each drive roll was controlled independently.

Furthermore, current control in the conventional method was performed as follows.

That is, the output signal of the speed controller 101 is converted into an AC instantaneous current command value s for each phase of the induction motor by the torque command three-phase instantaneous current command converter 102, and the command value and the motor 1 detected by the current detector 105 are converted into AC instantaneous current command values s for each phase of the induction motor. The deviation from the next current instantaneous value F _S is determined by the three-phase current controller 10.
3, the current of each phase is controlled, and the output signal of this three-phase current controller 103 is converted to the voltage required to operate the motor at the commanded speed and torque by the power converter 104. A method was adopted in which the frequency was applied to the electric motor.

In general, speed control devices that do not have an integrator and are set to a high proportional gain have a small speed deviation when the load increases, and therefore have a fast response speed, so the load will concentrate on a specific motor and cause an overload. Conventionally, the speed controller 101 is set to a low gain to increase the speed deviation as the load increases and control the response speed to be slightly slower, so that the load is not concentrated on a specific motor and the load is shared. It is composed of However, since each drive roll receives a large reaction force due to the static pressure of unsolidified iron inside the slab 4,
The rolls are easily worn, and if the amount of wear becomes too large, the load on each motor becomes unbalanced, which not only adversely affects the slab, but also deteriorates the precision of the casting speed.

[Problem to be solved by the invention]

When the drive roll of continuous casting equipment wears out due to a large reaction force from the slab, the rotation speed of the drive roll becomes somewhat faster.

Now, if we consider the case where a positive load is applied to each drive roll, the input deviation of the speed controller of the drive control device of the worn roll becomes smaller, and the load on the electric motor that drives this roll decreases. However, the load factor of the electric motor driving other rolls increases. Furthermore, if a load is applied in the opposite direction to each drive roll, the input deviation of the speed controller of the drive control device of the worn roll becomes even larger, and the load factor of the electric motor that drives this roll increases. The load factor of the electric motor driving other rolls decreases, resulting in imbalance. SUMMARY OF THE INVENTION An object of the present invention is to provide a slab drawing speed control method that balances the load on each electric motor and performs highly accurate casting speed control.

[Means to solve the problem]

In the present invention, each electric motor is controlled by a dedicated drive control device having an independent speed control system, and the speed feedback circuit of each drive control device automatically compensates for deviations in speed feedback amount due to wear of the roll diameter of the drive roll. This system is equipped with a function to correct the speed reference roll and other drive rolls, thereby balancing the load on each motor and achieving highly accurate speed control.

That is, the first invention is a slab drawing control device for continuous casting equipment having a dedicated drive control device for each driving roll electric motor, in which the speed controller provided in each drive control device is a speed controller with a low proportional gain. Then, a deviation signal between the common speed command signal V _S and the speed feedback signal V _F of the electric motor for each drive roll is given to this speed controller, and one drive roll is selected from all the drive rolls and its drive control is performed. The device is used as a reference drive control device, and the deviation signal between the speed feedback signal V _F detected by this reference drive control device and the common speed command signal V _S is input to an integrator, and the output signal T _S is used for each drive control. It is given as a common torque command to the device, and each drive control device uses the sum of the output signal T _S of the integrator and the output signal T _P of the speed controller as a torque command to control the speed of each electric motor, and performs acceleration and deceleration. In a steady state in which the output signal _{T P} of _the speed controller of each _drive control device _is By automatically adjusting the values, each drive control device performs torque control in accordance with a commonly given torque command T _S and balances the load on each drive roll electric motor.

In addition, the second invention provides a device for detecting the moving speed of the slab moving on the roller table of the continuous casting equipment in order to improve the accuracy of slab speed control, and a speed reference roll corresponding to the detection signal is provided. The speed feedback amount of the reference drive control device is corrected and controlled using the speed ratio as a speed correction coefficient.

[Effect]

According to the first invention, the constant cycle is preset so that the value of the output torque command signal T _P of the speed controller provided in the drive control device of each drive roll falls within a preset dead zone. As a result, the speed feedback amount is corrected by correcting the roll diameter each time, and as a result, the drive control of each drive roll is performed according to the torque command signal T _S output from a common speed controller given to each drive roll. In the device,
The torque of the electric motor is controlled so that the load factor of the electric motor of each drive roll is equalized.

A second invention provides the control according to the first invention,
The speed of each drive roll is controlled to match the speed of the slab, resulting in highly accurate casting speed control.

〔Example〕

The embodiment of the present invention shown in FIG. 3 will be described below.

In this example, one drive roll is selected from all the drive rolls, and the electric motor that drives it is temporarily set.
_M1 , and the speed detected by the pulse signal generator _PLG1 attached to the motor shaft is the reference speed of the extraction drive device.

Then, the casting speed setting value from the speed setting device 11 is input to the linear command device 12, and the output signal of the linear command device 12 is used as a common speed command signal Vs for each electric motor _M1.
~Give to Mn drive control device X ₂₁ ...X _2o . A deviation signal between the common speed command signal Vs and the output signal V _F of the speed feedback amount calculator 107 is input to a speed controller 101 having a low proportional gain, and the speed controller 101 outputs a torque command signal Tp.

When the roll driven by electric motor M ₁ is selected as the reference roll for speed control, that is, when the signal switch 119 is in the closed state, the signal switch 219, 319, …n
Always use the circuit in an open state.

Control is performed as follows until the tip 8 of the slab 4 passes the measure roll MR and the speed reference roll diameter correction calculator 19 outputs a roll diameter correction value.

That is, the roll diameter correction value ΔF ₂ held in the roll diameter correction calculator 111 and the linear command unit 118 for switching the roll diameter correction value are calculated as the calculation results from the previous casting.
Then, the pulse frequency F ₁ held as the calculation result from the previous casting is given to the adder 114 as an initial value at the start of speed control, and F ₁ +ΔF ₂ = F ₂ is calculated to determine the speed feedback amount. Find the pulse frequency F ₂ and start the following control.

First, install the pulse signal generator PLG ₁ on the electric motor M ₁ .
The signal is input to the pulse frequency converter 106 to detect the pulse frequency F, and this pulse frequency F and the F ₂ are input to the speed feedback amount calculator 107 to calculate the speed feedback amount using the following formula (F/F ₂ ) After calculation based on V _O =V _F , the deviation signal between the speed command value Vs and V _F is input to the integrator 13.

In addition, V _O in the above formula is a control constant that is set so that V _F becomes a 100% speed feedback signal when the roll is rotated at 100% speed in the case of a new roll with no wear. .

Then, the output signal of the integrator 13 is used as a common torque command signal Ts and is applied to each drive control device X ₂₁ to X ₂ n.

Then, the signal obtained by adding Ts and Tp is used as torque command 3.
Input to phase instantaneous current command converter 102, Ts + Tp
is taken as a torque command value, and converted into a three-phase instantaneous current command value for the induction motor corresponding to this command. Next, the output signal of the torque command 3-phase instantaneous current command converter 102 is used as a current command, and the deviation signal from the motor primary side current feedback signal detected by the current detector 105 is input to the 3-phase current controller 103 for current control. The output signal of the three-phase current controller 103 is input to the power converter 104, and the frequency and voltage required to operate the motor at the commanded speed and torque are applied to the main circuit of the motor. and start speed control of the motor.

When the tip 8 of the slab 4 passes the roll driven by the electric motor _M1 , speed control with automatic roll diameter correction is started as follows.

The present invention attempts to balance the load by correcting the roll diameter, but if the roll diameter is rapidly corrected, the speed feedback amount will also change rapidly, and the roll diameter correction loop Interference occurs between the speed control loop and the speed control loop, making the speed control system unstable. Therefore, in the present invention, in order to perform correction control of the roll diameter gently so that the speed control system does not become unstable, the signal contact is
10, and each time the signal contact closes, the output signal Tp of the speed controller 101 is input to the roll diameter correction calculator 111, and the roll diameter correction calculator 111 performs speed control to correct the roll diameter. Vessel 1
For the output signal Tp of 01, roll diameter correction calculation is performed with a dead zone between -ΔT _P <T _P <ΔT _P. Note that the value of ΔT _P is set in advance to a value of 5% to 0% of the rated torque of the electric motor, and this value (ΔT _P ) is not changed during control.

That is, in the roll diameter correction calculator 111, T _P >
If ΔT _P , ΔF ₁ is calculated from the pulse frequency correction signal ΔF ₂ held since the previous roll diameter correction calculation.

Then, if T _P <−ΔT _P , ΔF ₁ is added to ΔF ₂ . The roll diameter correction calculator 111 outputs ΔF ₂ , and the ΔF ₂ signal is input to the adder 114 via the signal input limiter 113 .

The adder 114 uses the roll diameter correction calculation result ΔF ₂ from the roll diameter correction calculation unit 111 to calculate F ₁ +
ΔF ₂ =F ₂ is calculated, and the output signal F ₂ is input to the speed feedback amount calculator 107, and the speed feedback signal of the electric motor M ₁ is corrected.

As described above, each time the signal contact 110 is closed, the speed feedback amount V _F is gently corrected and speed control is performed until the condition -ΔTo<Tp<ΔTo is satisfied.

When the tip 8 of the slab 4 passes through the measure roll MR, the deviation due to wear in the roll diameter of the roll connected to the electric motor M ₁ is corrected as follows.

The slab length measurement start signal contact 18 is closed, and the measure roll slab length measurement counter 15 and the drive roll length measurement counter 17 start counting.

The comparator 16 detects whether the measure roll slab length measurement counter 15 matches the set length lo,
The comparator 16 instructs the reference roll diameter calculator 19 to calculate the roll diameter reference value. Standard roll diameter calculator 19
Then, the computation of (l ₁ /l ₀ ) is performed using the length measurement value l ₁ by the drive roll slab length measurement counter 17 at the moment commanded by the comparator 16.

A new roll reference pulse frequency setter 115 that uses the output signal (l ₁ /l ₀ ) of the reference roll diameter calculator 19 and a new roll (roll with no wear) as a reference.
The multiplier 11 multiplies the pulse frequency Fo set by
6 and calculate Fo(l ₁ /l ₀ ).

At this time, the circuit between C and A of the signal switch 117 is closed, and the output signal of the multiplier 116 is input to the roll diameter correction switching straight line command unit 118.

The roll diameter correction switching linear command unit 118 uses the pulse frequency which is the previous calculation result held internally.
The value of F ₁ changes linearly and gradually toward the roll diameter reference value obtained by the new calculation, thereby preventing a sudden change in the speed feedback amount V _F .

Output signal of roll diameter correction switching linear command unit 118
F ₁ and the roll diameter correction value ΔF ₂ which is the calculation result by the roll diameter correction calculator 111 are input to the adder 114, which calculates F ₁ +ΔF ₂ =F ₂ , and sends F ₂ to the speed feedback amount calculator 107. Enter V _F and it will be corrected.
In this way, speed control is performed using the electric motor _M1 as the reference roll.

Next, drive control of other electric motors M ₂ to _{M o} will be explained.

The control circuits X ₂₂ to _{X 2} n of the other drive control devices have exactly the same circuit configuration as the drive control circuit X ₁₁ of the reference electric motor M ₁ . Hereinafter, the details of the control performed on the other electric motors M ₂ to Mn when the reference electric motor M ₁ is performing speed control as a speed reference roll will be explained using electric motor M ₂ as an example.

In the control device X ₂₂ of the electric motor M ₂ , the signal switch 117 has C-B closed, and the other signal switch 319...
Control is performed with n remaining closed.

The speed control with automatic roll diameter correction function in the case of electric motor _M2 is as follows, except for the roll diameter correction control by measure roll MR and 15 to 19, from the control content of electric motor _M1 that drives the speed reference roll.
This is similar to the control of electric motor _M1 .

That is, the circuit between C and B of the signal switching device 117 is closed, and the value of the pulse frequency Fo based on the new roll by the new roll reference pulse frequency setting device 115 is sent via the signal switching device 117 to the roll diameter correction switching straight line command. 118, and this is used as a reference value for determining the speed feedback amount.

When the tip 8 of the slab 4 passes the drive roll of the electric motor _M2 , the signal contact 110 closes at regular intervals, and the diameter of the drive roll of the electric motor _M2 is automatically corrected in exactly the same way as the control of the electric motor _M1 . Speed controller 10
The periodic roll diameter correction calculation continues until the output Tp of 1 satisfies ΔTo<Tp<ΔTo, and the electric motor
Control is performed so that the peripheral speed of the roll of _M2 is synchronized with the peripheral speed of the roll of electric motor _M1 .

The other electric motors M ₃ to Mn are also configured to be controlled in the same manner as M ₂ .

〔Effect of the invention〕

The drive rolls of continuous casting equipment are subject to large reaction forces due to the static pressure of the newly solidified iron inside the slab, and the rolls are likely to wear out. When the rolls wear out, the rotational speed of the rolls becomes somewhat faster, which tends to cause the load on the motor to become unbalanced.

The first invention was made in order to improve the problem of unbalanced load on the electric motor as described above, and the load factor of each drive roll is controlled to be equal, and each drive roll is evenly distributed. It becomes possible to cast high-quality slabs by exerting a driving force to pull out the slabs without applying excessive force to the slabs.

In addition, the second invention is based on the pulse counting results of a pulse signal generator attached to the measure roll MR installed outside the drive roll, which allows easy maintenance such as actual measurement of the roll diameter and roll replacement.
The diameter of the drive roll used as the reference speed is calculated, and based on the results, the deviation due to wear of the speed reference drive roll is automatically corrected, and the circumferential speed of other drive rolls is synchronized with the circumferential speed of the speed reference drive roll. This is a control method for the slab drawing speed in continuous casting equipment that automatically corrects the roll diameter. Therefore, if the present invention is applied to a slab drawing device in which drive rolls tend to wear due to extremely high roll pressure due to iron static pressure inside the slab, changes in speed due to changes in roll diameter can be automatically adjusted. Since it is equipped with a function to automatically correct the casting speed, it is possible to perform highly accurate casting speed control that balances the load on each motor, which is highly effective.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a known slab drawing device, FIG. 2 is a block diagram of a conventional slab drawing speed control device, and FIG. 3 is a block diagram of an embodiment of the present invention. 4... Slab, 7... Roll of roller table,
115... Speed setting device, 12... Linear command device, 1
3...Integrator, 15...Measure roll slab length measurement counter, 16...Comparator, 17...Drive roll slab length measurement counter, 18...Slab length measurement start signal,
19... Reference roll diameter calculator, 101... Speed controller, 102... Torque command 3-phase instantaneous current command converter, 103... 3-phase current controller, 104... Power converter, 105... Current detection 106...Pulse frequency converter, 107...Speed feedback amount calculator, 110...Signal contact, 111...Roll diameter correction calculator, 113...Signal input limiter, 114...
... Adder, 115 ... New roll reference pulse frequency setter, 116 ... Multiplier, 117 ... Signal switch, 118 ... Roll diameter correction value switching linear command device,
119,219,319,n...Signal switch,
_M1 to _M2 ...Induction motor, _PLG1 to PLGn...Pulse signal generator, PLGo...Pulse signal generator for measuring slab length, MR...Measure roll for measuring slab length.

Claims (1)

[Scope of Claims] 1. In a slab drawing control device for continuous casting equipment having a dedicated drive control device for each driving roll electric motor, the speed controller provided in each drive control device is a speed controller with a low proportional gain. , gives this speed controller a deviation signal between the common speed command signal Vs and the speed feedback signal _VF of each driving roll motor, and
Select one drive roll from all the drive rolls,
The drive control device is used as a reference drive control device, and the speed feedback signal detected by this reference drive control device
A deviation signal between V _F and the common speed command signal V _S is input to an integrator, and its output signal T _S is given as a common torque command to each drive control device, and each drive control device receives the output signal of the integrator. The speed of each motor is controlled using the sum of T _S and the output signal T _P of the speed controller as a torque command, and in a steady state where no acceleration or deceleration is performed, the output signal of the speed controller of each drive control device is
Common to all drive control devices by automatically adjusting the value of the speed feedback signal V _F so that the value of T _P falls within a preset minute dead zone (-ΔT _P < T _P < ΔT _P ). Torque command given to
A method for controlling slab withdrawal in continuous casting equipment, characterized by performing torque control according to T _S. 2. In a slab drawing control device for continuous casting equipment that has a dedicated drive control device for each drive roll electric motor, the speed controller provided in each drive control device is a speed controller with a low proportional gain, and the speed controller is Input the deviation signal between the common speed command signal V _S and the speed feedback signal V _F of each drive roll motor, and
Carry one drive roll out of all the drive rolls,
The drive control device is used as a reference drive control device, and the speed feedback signal detected by this reference drive control device
A deviation signal between V _F and the common speed command signal V _S is given to an integrator, and its output signal T _S is given as a common torque command to each drive control device, and each drive control device receives the output signal T of the integrator. The speed of each motor is controlled using the sum of _S and the output signal T _P of the speed controller as a torque command, and in a steady state where acceleration and deceleration are not performed, the output signal T _P of the speed controller of each drive control device
A small dead band (−
By automatically adjusting the value of the speed feedback signal V _F so that it falls within the range of ΔT _P < T _P < ΔT _P ), each drive control device can control the commonly given torque command T _S
and a device for detecting the moving speed of the slab moving on the roller table of the continuous casting equipment is provided, and the ratio of the speed of the speed reference roll to the detection signal is speed-corrected. A slab drawing speed control method in continuous casting equipment, characterized in that a speed feedback amount of a reference drive control device is corrected and controlled as a coefficient. 3. A slab drawing speed control method in continuous casting equipment according to claim 2, characterized in that correction control of the speed feedback amount is performed periodically using a speed correction coefficient of the reference drive control device.