JPH03294054A - Method for controlling drawing velocity of cast slab in continuous casting equipment - Google Patents

Abstract

PURPOSE:To prevent loading of unnatural tension in a cast slab by dividing the load required to drawing the whole cast slab into loading ratio required for each driving roll while controlling the drawing velocity of cast slab according to the set velocity. CONSTITUTION:In continuous casting, one roll from plural driving rolls is selected to detect the rotating velocity thereof. The drawing velocity control of cast slab is executed to plural motors which use this detected signal as velocity feedback signal with the common velocity controller. Together with this, the load at the time of drawing the whole cast slab is divided into each driving roll according to command value in a loading rate commanding instrument arranged to each driving roll as relation corresponding to distance from the original point fixed in the mold to tip part of the cast slab with pulse counter in a pulse generator fitted to one motor. By this method, the drawing velocity can be controlled so as to not to load the unnatural force in the cast slab.

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.

[Prior art]

FIG. 1 shows a 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. The slabs 4 were placed on both sides of the passage.○
It is pulled out and carried out to the roller table 7 by a non-driven roll indicated by a mark and a drive roll driven by an electric motor, indicated by a Φ mark.

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

That is, in the conventional method, the 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 the output signal of the speed detection pulse generator PLG+ connected to the electric motor. The pulse speed converter 10 of the drive control device is provided exclusively for each electric motor.
A method has been adopted in which the speed of each drive roll is controlled independently by inputting the deviation from the speed feedback signal (1) obtained through the roller 6 to a speed controller 101 having a proportional gain characteristic.

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 is for each phase of the induction motor by the torque command three-phase instantaneous current command converter 102, and the command value and the electric motor detected by the current detector 105 are Current control of each phase is performed by inputting the deviation from the instantaneous primary current value < ys to the three-phase current controller 103, and the output signal of this three-phase current controller 103 is used by the power converter 104 to control the motor. A method was adopted in which a voltage at the frequency required to operate at the commanded speed and torque was applied to the electric m primary winding.

In this conventional method, by setting the speed controller 101 to a low proportional gain, the speed of the electric motor is controlled as a drooping characteristic, and the load on each electric motor is balanced.

[Problem to be solved by the invention]

However, in the conventional technology, the load on each drive roll is averaged by setting the speed controller of each drive control device to a low proportional gain and controlling the electric motor to have a drooping characteristic. However, for the reasons described below, since the driving force required for each drive roll is different, excessive tension or pushing force may be applied to the slab between each drive roll.

In particular, there is a problem in that excessive tension has a detrimental effect on the quality of the slab, such as cracks occurring inside the slab.

The reason why the driving force required for each drive roll is different is as follows.

After the start of casting, as the drawing speed is increased and the tip of the slab passes through each roll in turn, the load on each drive roll increases or decreases due to changes in the static pressure of the unsolidified iron inside the slab 4. , the load increases and decreases when the slab is subjected to the static pressure of unsolidified iron and bulges between the rolls, and the bulge is corrected as it passes through the rolls immediately downstream, and the method of operation is continuous casting equipment. The distance between the upper and lower rolls of the curved part of the curved part is not constant, but the roll distance may be gradually reduced from the side closer to the mold to the horizontal part, which increases the load, etc. The required driving force differs depending on the position of the slab.

Therefore, the present invention changes the driving force required for each drive roll when the tip position of the unsolidified part of the slab changes after the start of casting, so that unreasonable force, especially tension, is applied to the slab. The purpose is to prevent

[Means to solve the problem]

The present invention has been made to solve the above-mentioned problems, and a first aspect of the present invention is to provide a control device for drawing a slab of continuous casting equipment having a dedicated drive control device for each electric motor. One of the drive rolls is selected from a plurality of drive rolls, its rotational speed is detected, and the detection signal is used as a speed feedback signal.The drawing speed of the slab is controlled by a speed controller common to multiple electric motors. As a function of the distance from the origin to the tip of the slab determined in the mold by pulse counting of a pulse generator attached to two electric motors, the Control is performed by distributing the load when pulling out the slab to each drive roll.

In addition, the second invention is a slab drawing control device for continuous casting equipment that has a dedicated drive control device for each electric motor, in which one of a plurality of drive rolls is selected to determine the drawing speed of the slab, and its rotational speed is detected. Then, the drawing speed of the slab is controlled by a speed controller common to multiple electric motors that uses the detected signal as a speed feedback signal, while the elapsed time since a virtual small slab is injected into the mold is tracked by pulse counting. The length of the unsolidified part of the slab is determined from these data, and a load command is set for each drive roll as a function corresponding to the length of the unsolidified part. Control is performed by distributing the load when drawing slabs to each drive roll according to instructions from the machine.

[Example] The operation and embodiment of the first invention will be explained using an example of the invention shown in FIG.

In this example, one drive roll is selected from all the drive rolls, the electric motor that drives it is temporarily set as Ml, and the speed detected by the nogle signal generator PLG+ attached to the motor shaft is used to drive the drawing. This is the reference speed of the control device.

Then, the drawing speed setting value from the speed setter 11 is input to the linear command device 12, and the output signal of the linear command device 12 is set as a common speed command signal (■), and each electric motor @M.

~M, to the drive control device Xz+-XKm.

A deviation signal between the common speed command signal Vs and the output signal V of the pulse speed converter 106 is input to the speed controller 101 having a low proportional gain, and the speed controller 101 outputs the torque command TP.
Outputs I.

When the roll driven by the electric motor 11M is selected as the speed reference roll, the signal switch 119 is always closed, and the signal switch 219 of the other driving roll control device
．． 319...n are always used in an open state.

First, the pulse signal generator PL attached to the electric motor M+
The signal G is input to the pulse speed converter 106, and the deviation signal between the output signal V and the common speed command signal 3 is input to the integrator 13.

The output signal of the integrator 13 is then set as the torque command signal T necessary for drawing out all the slabs and is input to the multiplier 15 provided for each drive control device.

Here, the pulse signal generator attached to the motor shaft of the drive roll is temporarily referred to as PLG.

The slab length measuring counter 17 starts counting the pulse signal generated by the pulse signal generator PLG when the drive roll rotates due to the start of casting.

This count value represents the distance from the origin defined in the mold to the tip of the slab, and this value is defined as Lc(s).

As shown in FIG. 4, the drive roll load factor command 14 is set with the load factor of each drive roll corresponding to Lc, and the drive roll load factor command 14 sets each drive roll corresponding to the value of LB. The command value of the roll load factor is output.

The multiplier 15 multiplies the output signal Ts of the integrator 13 and the output signal of the drive roll load factor command device 14, and outputs the output signal Ts+ to Tsn of each multiplier 15 to each drive control device X.
Give to ZI~Xt.

A signal obtained by adding the output signal TP+ of the speed controller 101 of each drive control device and the output signal Ts of the multiplier 5 is used as the torque command 3.
Input to phase instantaneous current command converter 102, Tpl+Ts+
is taken as a torque command value, and converted into a three-phase adjacent current command value for the induction motor corresponding to this command value.

Then, 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 current feedback signal detected by the current detector 105 is manually input to the 3-phase current controller 103 to control the current. The output signal of the three-phase current controller 103 is inputted to the power converter 104, and a voltage at the frequency required to operate the motor at the commanded speed and torque is applied to the primary winding of the electric motor. to start controlling the speed or torque of the motor.

In a steady state where there is no sudden change in the load of the electric motor, the output signal Tp of the speed controller 101 of the drive control device becomes O because the deviation between the slab drawing speed signal ■ and the drawing speed command ■ becomes very small. , a command value Ts in which the load when pulling out all the slabs is distributed according to the load factor command value of the drive roll set corresponding to the position of the slab.

is output from the multiplier 15, and torque control is performed according to Ts.

■8 and ■ when the load on the motor suddenly changes.

The deviation of the signal TpI is amplified by the speed controller 101.
becomes a torque command and suppresses speed fluctuations.

FIG. 5 shows an embodiment of the second invention, and the difference from the embodiment shown in FIG. The point is that the drive roll load factor command unit 14 is provided with the following information.

In this embodiment as well, one drive roll is selected from among all the drive rolls, and the electric motor that drives it is assumed to be M.
The speed detected by the pulse signal generator PLG attached to the motor shaft is set as the reference speed of the extraction drive control device.

Then, the drawing speed set value by the speed setter 11 is inputted to the linear command device 12, and the output signal of the linear command device 12 is set as the common speed command signal Vs, and each electric motor 11M.

~M, drive@control device x21~X, is given.

The speed with a low proportional gain is the deviation signal between the common speed command signal ■, and the output signal ■ of the pulse speed converter 106! +
! The speed controller 101 outputs a torque command.

When the roll driven by the electric motor M is selected as the speed reference roll, the signal switch 119 is always closed, and the signal switch 219 of the other drive roll control device,
319. n is always used in an open state.

First, the pulse signal generator P attached to the electric motor M
The LG I signal is input to the pulse speed converter 106, and its output signal v2 and the common speed command signal ■.

A deviation signal between the two is input to the integrator 13.

Then, the output signal of the integrator 13 is set as the torque command signal Ts necessary for drawing out all the slabs, and is inputted to the multiplier 15 provided for each drive control device.

Here, the pulse signal generator attached to the motor shaft of the drive roll is temporarily referred to as PLG.

Upon the start of casting, the slab length measuring counter F starts counting pulse signals generated by the PLG every time the drive roll rotates.

This count value indicates the total length Lc (m) of the cast slab based on the origin defined in the mold, and when the output of the slab length measurement counter 17 is input to the unsolidified slab length length calculator 18, The unsolidified slab length length calculator 18 calculates the length of the unsolidified slab part as follows.

First, the time required for the slab to completely solidify t<m1
n) is the thickness of the slab set by the slab thickness setting device 19, D (mm), and the cooling system number of the slab, set by the slab cooling system number setting device 20, is K (mm-min-t).
Then, the length of the unsolidified slab length is determined by the following calculation performed by the calculator 18.

Cut = (D/2K) (min) Now, slab width ΔL
Consider a hypothetical small slab. Then, the time when the small slab was injected into the mold is set as Li (min), and the casting length is set as tcti+ (m), and these two data are stored in the data file of the unsolidified slab length length calculator 18. .

Next, the time L (i.,) when the casting length changes from L (i) to L c (i) + ΔL and the casting length L c (i
+1) data is also stored in the data file.

In this way, each time a virtual small slab is poured into the mold, the time and casting length data are stored in a data file, and the time of the virtual slab poured into the current mold is L (i+). , the casting length is Lc<ink).

From the above, from the data stored in the data file, find the minimum value of (i. By performing the following calculation from the casting length L c (i.1.), the length of the unsolidified part of the slab can be obtained.

The details of the calculation by the unsolidified slab length length calculator 18 where L k =Lc(ink) Le(i*j>) are shown in the flowchart of FIG.

As shown in FIG. 7, the drive roll load factor command device 14 is set with a load factor for each drive roll corresponding to the length of the unsolidified part of the slab.
A load factor command value for each drive roll corresponding to the value of Lm is outputted from.

The multiplier 15 multiplies the output signal Ts of the integrator 13 and the output signal of the driving roll load factor command device 14.
The output signal T S 1 "" T $ , of each drive control device X! , -) (give to tn.

The output signal T,1 of the speed controller 101 of each drive control device and the output signal T8 of the multiplier 5. Torque command 3
Input it to the phase instantaneous current command converter 102, set T□10T□ as a torque command value, and set
Convert to adjacent current command value.

This torque command three-phase instantaneous current command converter 102
The output signal of is the current command, and the deviation signal from the motor primary current feedback signal detected by the current detector 105 is the three-phase current fl.
The output signal of the 3-phase current controller 103 is input to the power converter 104 to obtain the voltage at the frequency required to operate the motor at the commanded speed and torque. It can be applied to the motor primary winding to begin controlling the speed or torque of the motor.

In a steady state where there is no sudden change in the load of the electric motor, the output signals T and I of the speed controller 101 of the drive control device become O because the deviation between the slab drawing speed signal (■) and the drawing speed command (■3) is very small. Then, the multiplier 15 outputs a command value T□, which distributes the load when pulling out all the slabs according to the load factor command value of the drive roll set corresponding to the slab position, and the torque according to T□ is output. Control takes place.

When the load of the electric motor suddenly changes, the signal T p r obtained by amplifying the deviation between (3) and (2) by the speed controller 101 becomes a torque command, and the fluctuation in speed is suppressed.

〔Effect of the invention〕

As described above, according to the present invention, the drawing speed of the slab is controlled according to the set speed, and the load required to pull out the entire slab is increased by increasing the pulling speed from the start of casting. By distributing the load to each drive roll at various stages, it is possible to control so that excessive force, especially tension, is not applied to the slab, and this is particularly effective for high-speed casting in continuous casting equipment. .

[Brief explanation of drawings]

Fig. 1 is a sectional view of a known slab drawing device, Fig. 2 is a control block diagram of a conventional slab drawing speed control device, Fig. 3 is a block diagram of an embodiment of the present invention, and Fig. 4 is a drive FIG. 5 is a block diagram of a different embodiment; FIG. 6 is a flowchart showing details of the calculation by the unsolidified slab length calculator; and FIG. It is a figure which shows an example of the load factor command function of a drive roll in the case of the Example shown in a figure. 1... Shi-dol 2... Tundish 3... Mold 4... Slab 5... Non-driven pinch roll 6... Drive pinch roll 7... Roller table roll 8... Slab tip 11...Speed setter 12-...Line line command unit 13...Integrator 14...Drive roll load factor command unit 15...Multiplier 17...Slab length measurement counter 18 -...Arithmetic unit l 9 ・ ・ 20 ・ ・ 21 ・ ・ 101 ・ ・ 102 ・ ・ 103 ・ ・ 104 ・ ・ 105 ・ ・ 106 − ・ 119.2 M, -M, ・ PLG, ~P PLG, ・ ・MR・・ Slab thickness setter Slab cooling system number setter Casting start signal Speed controller Torque command 3-phase instantaneous current command converter 3-phase current controller Power converter Current detector Pulse speed converter 9.319. n...Signal switch/induction motor G...Pulse signal generator Pulse signal generator for slab length measurement Measure roll for slab length measurement

Claims (2)

[Claims] (1) In a slab drawing control device for a continuous casting facility that has a dedicated drive control device for each electric motor, multiple drive control devices select one of the multiple drive rolls and use its rotational speed as a speed feedback signal. While the drawing speed of the slab is controlled by a common speed controller, all slabs are pulled out according to the load factor function that is set independently for each drive roll in accordance with the value of the slab tip position counter. 1. A slab drawing speed control method characterized by distributing and controlling the load applied to each driving roll. (2) In a slab drawing control device for continuous casting equipment that has a dedicated drive control device for each electric motor, multiple drive control devices select one of the multiple drive rolls and use its rotational speed as a speed feedback signal. While the drawing speed of the slab is controlled using a speed controller common to both, the slab is divided into small slabs and tracking is performed using a casting length measuring counter from the moment the slab is poured into the mold. The load when all the slabs are pulled out is distributed and controlled among the drive rolls according to a load factor function that is independently set for each drive roll in accordance with the length of the unsolidified part of the slab obtained as a result. A slab drawing speed control method characterized by: