JP5606106B2 - Control method of roll drive motor of rolling stand - Google Patents

Description

The present invention relates to a method for controlling a roll driving motor of a rolling stand installed on a pinch roll extending side of a continuous casting facility.

With regard to continuous casting equipment, in equipment having a rolling stand that continuously rolls the slab without cutting the slab on the pinch roll strip side, the drive motor capacity of the rolling stand is generally larger than that of the pinch roll, and rolling Since the frictional force between the roll and the slab is also large, the speed fluctuation of the rolling stand leads to the speed fluctuation of the pinch roll band. And the speed fluctuation | variation of a pinch-roll belt leads to a molten metal surface fluctuation | variation, and becomes a factor which deteriorates the quality of slab.

Therefore, the control device of the rolling stand is required not to change the speed on the pinch roll band. As the method, for example, as described in Patent Document 1, the current value of the drive motor of the pinch roll zone immediately before the rolling stand is reduced, and the rolling after the reduction is performed so as to suppress the fluctuation of the current value. A method for correcting the speed of the stand is known.

JP 11-319909 A

In order to stabilize the speed of the pinch roll band, this method is proposed on the premise that the motor current of the pinch roll band is constant. If the drive motor current fluctuates even when the pinch roll speed is constant even if there is a reduction mechanism, if the line decelerates and the current value of the pinch roll band decreases, the line accelerates and the pinch roll band When this method is applied when the current is increased or when the motor current is largely varied, the speed may be changed. Therefore, there is a problem that the equipment to which this method can be applied or the conditions under which the rolling stand can be used in this method are limited.

The present invention has been made in view of such circumstances. 1) When the motor current of the pinch roll belt operating at a constant speed fluctuates. 2) The motor current of the pinch roll belt fluctuates due to acceleration / deceleration of the equipment. Case 3) An object of the present invention is to provide a method of controlling a roll drive motor for a rolling stand capable of stably controlling the rolling stand even when the drive motor current fluctuates greatly.

The roll driving motor control method for a rolling stand according to the first aspect of the present invention is arranged on the exit side of a pinch roll band of a steel continuous casting facility having a plurality of pinch rolls, and is a roll drive comprising an induction motor. A method for controlling a roll drive motor of a rolling stand that drives a motor for a motor using an inverter device,
A value X obtained by subtracting the actual speed value (Vfb) from the speed command value (Vc) of the roll driving motor given to the inverter device is:
1) Subtracting the correction amount (b2) from the drooping set value (D) for a short time (if it is larger than the preset value (a2) on condition that it is equal to or less than the drooping upper limit (L2) n2) If the value is smaller than a preset value (a1) on the condition that the vehicle is operated and 2) is equal to or greater than the drooping lower limit (L1), the correction amount (b1) is set to the drooping set value (D). To drive for a short time (n1)
Repeatedly, the value of X converges between a1 and a2.
Here, the drooping set value (D), the actual speed value (Vfb), the set value (a1, a2) and the correction amount (b1, b2) are the speed command value of the roll driving motor to the inverter device ( It is shown as a ratio when Vc) is 100%.

In the method for controlling a roll driving motor of a rolling stand according to the first aspect of the invention, the actual speed value (Vfb) is preferably determined by an output of a tachometer provided in the roll driving motor. Here, the tachometer means, for example, a PLG (Pulse Logic Generator) or a rotary encoder.

In the control method of the roll drive motor of the rolling stand according to the first invention, the total output P of the drive motor of the pinch roll band is in a range of 1/10 to 1 of the output of the roll drive motor of the rolling stand. Preferably there is.

A roll drive motor control method for a roll stand roll drive motor according to the second aspect of the present invention is arranged on the exit side of a pinch roll band of a continuous casting equipment for steel having a plurality of pinch rolls, and is composed of an induction motor. A method for controlling a roll drive motor of a rolling stand that drives a motor for a motor using an inverter device,
From the speed command value (Vc) of the roll drive motor until the load torque value (T) of the roll drive motor of the roll reaches a predetermined value when the roll of the rolling stand descends. A smaller corrected speed command value to the inverter device,
After the load torque value (T) reaches a predetermined value, a speed command value (Vc) of the roll driving motor is given to the inverter device,
Further, a value X obtained by subtracting the actual speed value (Vfb) from the speed command value (Vc) of the roll driving motor given to the inverter device is:
1) Subtracting the correction amount (b2) from the drooping set value (D) for a short time (if it is larger than the preset value (a2) on condition that it is equal to or less than the drooping upper limit (L2) n2) If the value is smaller than a preset value (a1) on the condition that the vehicle is operated and 2) is equal to or greater than the drooping lower limit (L1), the correction amount (b1) is set to the drooping set value (D). To drive for a short time (n1)
Repeatedly, the value of X converges between a1 and a2.
Here, the drooping set value (D), the actual speed value (Vfb), the set value (a1, a2) and the correction amount (b1, b2) are the speed command value of the roll driving motor to the inverter device ( It is shown as a ratio when Vc) is 100%.

In the method for controlling a roll driving motor of a rolling stand according to the second invention, the corrected speed command value is preferably 1 to 2% smaller than the speed command value (Vc).

In the method for controlling a roll driving motor of a rolling stand according to the present invention, [speed command value−speed actual value = X] is maintained in a certain range, and when (X) is out of the range, the range is gently increased. Since the control is performed to return to the inside, the rolling stand can be stably controlled without giving a steep speed fluctuation to the pinch roll band.
Further, when the roll drive motor output of the rolling stand is larger than the total output P of the motor driving each pinch roll of the pinch roll band (that is, P × (1 to 10 times)), the speed fluctuation of the rolling stand is pinched. It is particularly useful to use the method for controlling the roll driving motor of the rolling stand according to the present invention because it greatly affects the speed fluctuation of the roll band and the fluctuation of the molten metal surface.

It is a schematic explanatory drawing of the continuous casting equipment of the steel to which the control method of the roll drive motor of the rolling stand which concerns on the 1st Embodiment of this invention is applied. It is a flowchart of the control method of the roll drive motor of the rolling stand. It is a schematic explanatory drawing of the continuous casting equipment of the steel to which the control method of the roll drive motor of the rolling stand which concerns on the 2nd Embodiment of this invention is applied. It is explanatory drawing which shows the mode of the reduction operation | movement of a reduction roll, and a hot-water surface fluctuation | variation.

FIG. 1 shows a steel continuous casting facility 10 to which the control method of a roll drive motor for a rolling stand according to the first embodiment of the present invention is applied. This continuous casting facility 10 includes a tundish 11, A continuous casting mold (mold) 12 disposed immediately below, a pinch roll band 14 with a slab 13 drawn from the continuous casting mold 12 and a water cooling device, and a downstream side of the pinch roll band 14. And a rolling stand 15.

The rolling stand 15 includes reduction rolls 17 and 18 driven by a roll driving motor 16 using an induction motor. The total output (total output P) of the motors that drive each pinch roll of the pinch roll band 14 is about 1/10 to 1 times the output of the roll drive motor 16 that drives the rolling stand 15. .

The roll drive motor 16 is controlled by a rolling stand drive control device (an example of an inverter device) 19, and a variable drooping logic 20 is connected to the rolling stand drive control device 19. The roll driving motor 16 incorporates a PLG (an example of a tachometer) that detects the rotational speed of the motor, and its output is output to the variable drooping logic 20 as a speed actual value (Vfb). The variable drooping logic 20 may be incorporated in the rolling stand drive control device 19 or may be a separate device (system). Then, the rolling stand drive control device 19 via the variable drooping logic 20 has a preset droop setting value D (for example, D = 1 to 4%, in this embodiment, the initial set value d0 = 2%). Entered.

Each motor (consisting of an induction motor) that drives the pinch roll band 14 is connected to an inverter-controlled pinch roll drive control device 21, and a speed command value (Vc) corresponding to the frequency of the inverter from a line control computer (not shown). And each motor is driven at a predetermined rotational speed.
This speed command value (Vc) is also given to the rolling stand drive control device 19 and the variable drooping logic 20.

Next, a method for controlling the roll driving motor of the rolling stand having such a configuration will be described with reference to FIGS.
A speed command value (Vc) is given to each pinch roll drive control device 21, and each pinch roll is driven at a predetermined rotational speed. Here, the speed of the slab 13 on the exit side of the pinch roll band 14 is delayed from the peripheral speed of the pinch roll immediately below the continuous casting mold (mold) 12. This is mainly due to the heat shrinkage of the slab 13, and this value fluctuates depending on the operating conditions and the line operating conditions.

Therefore, the actual speed value of the slab 13 with respect to the speed command value on the exit side of the pinch roll band 14 when the rolling stand 15 is not used in advance, that is, when the slab 13 is not squeezed by the rolling rolls 17 and 18. Investigate (Vr) and set the upper limit value (a2%) and lower limit value (a1%) of [speed command value (Vc) -speed actual value (Vr)] in the variable drooping logic 20. deep. The range from the upper limit value (a2%) to the lower limit value (a1%) is an allowable speed deviation range. When the rolling stand 15 is used, that is, when the slab 13 is reduced by the reduction rolls 17 and 18, the drooping set value (D) is corrected so that the speed deviation falls within this range.

Details of the drooping control will be described with reference to FIG. In FIG. 2, a1 (deviation lower limit value), a2 (deviation upper limit value), n1 (operation time), n2 (operation time), b1 (increasing-side drooping correction amount), b2 (decreasing-side drooping). The correction amount is, for example, as follows.
0 <a1 <2%, 1% <a2 <4%, a1 <a2, 0.2 seconds <n1 <10 seconds, 0.2 seconds <n2 <10 seconds, 0.05% <b1 <0.2% 0.05% <b2 <0.2%

The drooping initial value d0 (for example, d0 = 2%) is input to the variable drooping logic 20 in advance, the rolling of the rolling stand 15 is started (step S1), and the drooping set value is input to the rolling stand drive controller 19. D is set to d0 (step S2). In this state, the following control is started.
The actual speed value (Vfb) measured by the tachometer (PLG) provided in the roll drive motor 16 is subtracted from the speed command value (Vc) sent from the entire system (that is, the line control computer). A value X is calculated (step S3).

When this value (X) is larger than Vc × a2 / 100 (step S4), it is confirmed that the value (X) is equal to or less than L2 (drooping upper limit value) and continues for n2 seconds (step S5). The drooping setting value D is replaced with (D−b2) (step S6), and the process returns to step S3.
. If the condition of step S5 is not satisfied (that is, if it has not continued for n2 seconds), the process returns to step S3.

In step S4, if X ≦ Vc × a2 / 100, the process proceeds to step S7, and if X <Vc × a1 / 100, the value (X) is equal to or greater than L1 (drooping lower limit value) and After confirming that it has continued for n1 seconds (step S8), the drooping setting value D is replaced with (D + b1), and the process returns to step S3 (step S9). If the condition of step S8 is not satisfied (that is, if it does not continue for n1 seconds), the process returns to step S3.

In step S7, if X ≧ Vc × a1 / 100, the end of rolling (rolling) is determined (step S10), and if rolling (rolling) has not ended, the process returns to step S3. Eventually, in the process of step S4 to step S9, the convergence control is performed so that [speed command value (Vc) −speed actual value (Vfb)] falls within the appropriate difference value a1 to a2. This state is performed until the end of rolling (step S10).

FIG. 3 shows a steel continuous casting facility 30 to which the control method of the roll driving motor of the rolling stand according to the second embodiment of the present invention is applied. The continuous casting facility 30 is obtained by further adding a speed command correction logic 31 and a drooping set value switching logic 32 to the continuous casting facility 10 (see FIG. 1) to which the control method according to the first embodiment is applied. . Hereinafter, the same parts as those in FIG. 1 are denoted by the same reference numerals and description thereof is omitted.

The speed command correction logic 31 is connected to a line control computer (not shown) and the rolling stand drive control device 19. The speed command correction logic 31 receives the speed command value (Vc) output from the line control computer and outputs the corrected speed command value to the rolling stand drive control device 19. The speed command correction logic 31 receives the load torque value (T) of the roll drive motor 16 output from the rolling stand drive control device 19.

The drooping set value switching logic 32 is connected to the variable drooping logic 20 and the rolling stand drive control device 19. The drooping setting value switching logic 32 receives the drooping setting value (D) output from the variable drooping logic 20 and outputs the drooping setting value to the rolling stand drive control device 19. Further, the load torque value (T) of the roll driving motor 16 output from the rolling stand drive control device 19 is input to the drooping set value switching logic 32.

Next, a method for controlling the roll driving motor 16 by the speed command correction logic 31 and the drooping set value switching logic 32 will be described. In the present embodiment, a process is further added before step S2 of the control method of the roll driving motor 16 shown in FIG.

First, the speed command correction logic 31 corrects the speed command value (Vc) at the beginning of the descent of the rolling roll 17 and outputs the corrected corrected speed command value to the rolling stand drive control device 19. This correction multiplies the speed command value (Vc) by the coefficient (k). This coefficient (k) can be set to 0.98 to 0.99, for example.
After the rolling roll 17 comes into contact with the slab 13, the speed command correction logic 31 stops the correction operation when the load torque value (T) of the roll driving motor 16 reaches a predetermined value. . When the correction operation is stopped, the speed command correction logic 31 outputs the speed command value (Vc) as it is.

The drooping setting value switching logic 32 sets the drooping setting value to 0 regardless of the drooping setting value (D) output from the variable drooping logic 20 at the beginning of the descent of the rolling roll 17. That is, the rolling stand drive control device 19 does not perform the drooping characteristic control.
Then, the drooping setting value switching logic 32 sets the value output from the variable drooping logic 20 as it is when the load torque value (T) of the roll driving motor 16 reaches a predetermined value. Output as a value.

FIG. 4 is an explanatory diagram showing the rolling operation of the rolling roll 17 and the state of molten metal surface fluctuation. The operations of the speed command correction logic 31 and the drooping set value switching logic 32 will be described in detail for each period A to C shown in the figure. Here, the period A is a period from when the rolling roll 17 starts to descend until it comes into contact with the slab 13. The period B is a period from when the rolling roll 17 comes into contact with the slab 13 until the load torque value (T) of the roll driving motor 16 reaches a predetermined value (α). The period C is a period after the load torque value (T) of the roll driving motor 16 becomes equal to or greater than a predetermined value (α). Note that the predetermined value (α) of the load torque value (T) can be set to, for example, 10 to 50% of the rated torque of the roll driving motor 16.

(1) Period A
The speed command correction logic 31 corrects the speed command value (Vc) so as to match the feed speed of the slab 13 on the exit side of the pinch roll band 14 and outputs a corrected speed command value. As described above, compared to the peripheral speed of the pinch roll immediately below the continuous casting mold (mold) 12, the feeding speed of the cast 13 on the exit side of the pinch roll band 14 is delayed by 1 to 2%. That is, the feed speed of the slab 13 on the exit side of the pinch roll band 14 is delayed by 1 to 2% from the speed command value (Vc). In the present embodiment, a corrected speed command value that is 1 to 2% slower than the speed command value (Vc) is given to the rolling stand drive control device 19. As a result, the difference between the feeding speed of the slab 13 and the peripheral speed of the rolling roll 17 is suppressed small when the rolling roll 17 contacts the slab 13. Therefore, the speed fluctuation of the pinch roll 14 is suppressed, and the hot water level fluctuation is suppressed.
On the other hand, the drooping setting value switching logic 32 outputs the drooping setting value as 0. That is, the rolling stand drive control device 19 does not perform the drooping characteristic control.

(2) Period B
Since the reduction roll 17 contacts the slab 13, fluctuations occur in the molten metal surface. However, as described above, since the rolling roll 17 is in contact with the peripheral speed close to the feed speed of the slab 13, fluctuations in the molten metal surface can be suppressed as compared with the prior art. Specifically, the fluctuation range of the hot water surface level is suppressed within ± 10 mm of the allowable range.
The operations of the speed command correction logic 31 and the drooping set value switching logic 32 are continued from the period A and do not change.

(3) Period C
The speed command correction logic 31 stops the correction operation. The speed command correction logic 31 outputs the same value as the speed command value (Vc) to the rolling stand drive control device 19. On the other hand, the drooping setting value switching logic 32 outputs the value (D) output from the variable drooping logic 20 as it is as the drooping setting value. And the rolling stand drive control apparatus 19 performs drooping characteristic control, and the control (process after step S2 shown in FIG. 2) shown in 1st Embodiment is performed.

In FIG. 4, the speed command correction logic 31 stops the correction operation when the reduction roll 17 has a load torque value (T) of the roll driving motor 16 equal to or greater than a predetermined value (α). However, the correction operation may be stopped after the reduction operation is completed. That is, the correction operation may be stopped when the reduction roll 17 reaches a predetermined reduction position.

10: Steel continuous casting equipment, 11: Tundish, 12: Continuous casting mold, 13: Cast slab, 14: Pinch roll strip, 15: Rolling stand, 16: Roll driving motor, 17, 18: Rolling roll, 19 : Rolling stand drive control device, 20: Variable drooping logic, 21: Pinch roll drive control device, 30: Steel continuous casting equipment, 31: Speed command correction logic, 32: Drooping set value switching logic

Claims (5)

A method for controlling a roll drive motor of a rolling stand that is arranged on the exit side of a pinch roll band of a steel continuous casting facility having a plurality of pinch rolls and that drives a roll drive motor composed of an induction motor using an inverter device. There,
A value X obtained by subtracting the actual speed value (Vfb) from the speed command value (Vc) of the roll driving motor given to the inverter device is:
1) Subtracting the correction amount (b2) from the drooping set value (D) for a short time (if it is larger than the preset value (a2) on condition that it is equal to or less than the drooping upper limit (L2) n2) If the value is smaller than a preset value (a1) on the condition that the vehicle is operated and 2) is equal to or greater than the drooping lower limit (L1), the correction amount (b1) is set to the drooping set value (D). To drive for a short time (n1)
A method for controlling a roll driving motor of a rolling stand, which is repeatedly performed so that the value of X converges between a1 and a2.
Here, the drooping set value (D), the actual speed value (Vfb), the set value (a1, a2) and the correction amount (b1, b2) are the speed command value of the roll driving motor to the inverter device ( It is shown as a ratio when Vc) is 100%. 2. The method for controlling a roll drive motor of a rolling stand according to claim 1, wherein the actual speed value (Vfb) is determined by an output of a tachometer provided in the roll drive motor. Control method of stand roll drive motor. 3. The method for controlling a roll drive motor for a rolling stand according to claim 1, wherein the total output P of the drive motor for the pinch roll band is in a range of 1/10 to 1 of the output of the roll drive motor for the rolling stand. A method of controlling a roll drive motor of a rolling stand, characterized in that A method for controlling a roll drive motor of a rolling stand that is arranged on the exit side of a pinch roll band of a steel continuous casting facility having a plurality of pinch rolls and that drives a roll drive motor composed of an induction motor using an inverter device. There,
From the speed command value (Vc) of the roll drive motor until the load torque value (T) of the roll drive motor of the roll reaches a predetermined value when the roll of the rolling stand descends. A smaller corrected speed command value to the inverter device,
After the load torque value (T) reaches a predetermined value, a speed command value (Vc) of the roll driving motor is given to the inverter device,
Further, a value X obtained by subtracting the actual speed value (Vfb) from the speed command value (Vc) of the roll driving motor given to the inverter device is:
1) Subtracting the correction amount (b2) from the drooping set value (D) for a short time (if it is larger than the preset value (a2) on condition that it is equal to or less than the drooping upper limit (L2) n2) If the value is smaller than a preset value (a1) on the condition that the vehicle is operated and 2) is equal to or greater than the drooping lower limit (L1), the correction amount (b1) is set to the drooping set value (D). To drive for a short time (n1)
A method for controlling a roll driving motor of a rolling stand, which is repeatedly performed so that the value of X converges between a1 and a2.
Here, the drooping set value (D), the actual speed value (Vfb), the set value (a1, a2) and the correction amount (b1, b2) are the speed command value of the roll driving motor to the inverter device ( It is shown as a ratio when Vc) is 100%. 5. The roll drive motor for a rolling stand according to claim 4, wherein the corrected speed command value is 1-2% smaller than the speed command value (Vc). Control method.

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