JPH0957314A - Tandem cold mill drive - Google Patents

Abstract

(57) [PROBLEMS] To provide a tandem cold mill drive device capable of preventing the rolling material from reversing when the rolling line is stopped and thereby preventing the plate from breaking due to the reversing. SOLUTION: When a current reference value of a mill drive motor is calculated based on a deviation between a speed reference value of a tandem cold mill and a detected speed and added to a current control device, this current reference value is held and this current reference value is held. From the current reference control means for outputting a current reference value that converges to zero at a predetermined time change rate from,
During operation of the rolling line, the current reference value of the speed control means is directly applied to the current control device of the mill drive motor, and when the rolling line is stopped, the current reference value of the speed control means is held in the current reference control means and the rolling line is stopped. And a current reference switching means for adding the current reference value output from the current reference control means to the current control device of the mill drive motor instead of the current reference value of the speed control means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tandem cold mill driving device.

[0002]

2. Description of the Related Art As a conventional tandem cold mill driving device, there is one shown in FIG. It consists of a host computer and a mill drive. The host computer side is equipped with a speed reference calculation means 1 for outputting an optimum speed reference value V _ref using the rolling schedule and various measured values. Then, the speed reference value V _ref and the speed feedback value V _FB detected by the speed detector 2 are added to the subtractor 3, and the speed deviation amount ΔV (= V _ref −V _FB ) is added to the mill driving device. The mill driving device comprises a speed control means 4 and a current reference output switch 5. The speed control means 4 performs PI calculation on the speed deviation amount ΔV, and outputs the obtained value as the current reference value I _ref . The current reference output switch 5 is turned on during operation of the rolling line to add the current reference value I _ref to a current control device (not shown).

[0003]

In a cold rolling facility equipped with a tandem cold mill, the line is stopped when the rolls are recombined or when an external command is given. Even when the speed reference value from the host computer is zero when the line is stopped, current is flowing to the mill drive motor to generate torque due to the plate tension and rolling static torque. Therefore, the current reference value I _ref is given to the current control device of the mill drive motor. In this state, when the current reference output switch 5 is turned off and the current reference value I _{ref is set} to zero, the backward tension f _b causes the rolling state shown in FIG.
As shown in (b), the rolled material 12 is in a retrograde state. At this time, the rolled material 12 has a portion to be reverse-rolled. The reverse-rolled portion is further rolled when the line is restarted, and so-called double rolling is performed, so that there is a possibility that the sheet may be broken.

The present invention has been made in order to solve the above problems, and by preventing the rolling material from moving backward when the rolling line is stopped, the tandem cold mill which can prevent the plate from breaking due to the rolling backward. The purpose is to obtain a drive.

[0005]

According to the present invention, when a current reference value of a mill driving motor is calculated based on a deviation between a speed reference value of a tandem cold mill and a detected speed and the current reference value is added to a current control device, the current reference value is used. A current reference control means for holding a value and outputting a current reference value that converges to zero from this current reference value at a predetermined time change rate, and the current reference value of the speed control means during operation of the rolling line, the mill drive motor as it is. In addition to the current control device, the current reference value of the speed control means is held in the current reference control means when the rolling line is stopped, and output from the current reference control means instead of the current reference value of the speed control means while the rolling line is stopped. Current reference switching means for applying the current reference value to the current control device of the mill drive motor.

Another invention is to add a deviation between a speed reference value and a detected speed of a tandem cold mill to a speed control means to calculate a current reference value and add the current reference value to a current control device of a mill drive motor. Current detection means for detecting the current of the device and the drooping for correcting the deviation between the speed reference value and the detected speed by multiplying the detected current value by the drooping gain input from the outside and outputting the drooping correction amount. The correction control means and a drooping gain that can be arbitrarily selected during operation of the rolling line are added to the drooping correction control means, and after the rolling line is stopped, the output of the speed control means converges to zero at a predetermined time change rate. And a drooping gain switching means for adding such drooping gain to the drooping correction control means.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments. FIG. 1 is a block diagram showing an embodiment of the present invention. In the figure, the same elements as those in FIG. 5 are designated by the same reference numerals and the description thereof will be omitted. Here, a current reference control means 6 and a current reference switching means 7 are newly added to the configuration of FIG. Of these, the current reference control means 6 temporarily holds the current reference output from the speed control means 4 and outputs a current reference that converges to zero as time passes. The current reference switching means 7 sends the current reference of the speed control means 4 to the current reference output switch 5 as it is during the operation of the rolling line, and the current reference of the speed control means 4 at the moment of stopping the rolling line. In addition to 6, while the rolling line is stopped, the current reference control means 6
The current reference of is sent to the current reference output switch 5. The current reference switching means 7 is also called a gate,
When the function is expressed by a switch, the normally closed switch 7a connected between the output end of the speed control means 4 and the current reference output switch 5, the output end of the speed control means 4 and the input end of the current reference control means 6 are shown. A normally open switch 7b connected to and a normally open switch 7c connected between the output end of the current reference control means 6 and the current reference output switch 5, and these switches are interlocked. There is.

In the conventional apparatus, the current reference output switch 5 is opened after the rolling line is stopped, but in the present embodiment, at least the current reference value I _ref2 output by the current reference control means 6 becomes zero. Will be closed.

The operation of the embodiment configured as described above will be described below, focusing on the part having a different configuration from the conventional device. The speed control means 4 determines the speed deviation ΔV.
For the speed deviation ΔV, for example, PID
The calculation is executed and the current reference value I _ref1 is output. During operation of the rolling line, the normally closed switch 7a of the current reference switching means 7 is kept in the ON state, and the normally open switches 7b, 7c are kept in the OFF state. Therefore, the current reference value I _ref1 is applied as it is to the current control device of the electric motor through the current reference output switch 5. On the other hand, when the rolling line is stopped, the normally closed switch 7a of the current reference switching means 7 is turned off and the normally open switches 7b and 7c are turned on.
The current reference value I _ref1 is continuously input to the current reference control means 6 while the rolling line is stopped. The current reference control means 6 holds the current reference value I _ref1 when the rolling line is stopped, and
The following formula is calculated and the obtained current reference value I _ref2 is output.

I _ref2 = I _ref1 −I _refH / K (1) I _ref2 → I _ref1 (2) where I _refH : current reference holding value K: time for current value of motor to converge to zero (s) → : A symbol indicating that I _ref2 is substituted into I _ref1 after the calculation of the equation (1).

2 (a) and 2 (b) show temporal changes in the speed reference V _ref and the current reference value I _ref2 when the rolling line is stopped. That is, when stopping the rolling line, the speed reference calculating means 1 decreases the speed reference V _ref from time t ₁ to zero at time t _s . The speed control means 4 executes the PI calculation on the difference between the speed reference V _ref and the speed feedback value V _FB, and outputs the current reference I _ref1 of a certain magnitude at the time t _s . At this time t _{s, the} current reference switching means 7 performs a switching operation. Thus, current reference control means 6 time t _s after,
It outputs a current reference value I _ref2 that linearly decays with the passage of time and converges to zero when the time K has passed.

In the case of a tandem cold mill, there are a plurality of stands, but the value of K is constant at any stand, and even if there are variations in the residual current value, the current reference value I
_ref2 should be zero at the same time. If the current reference value I _ref2 of each stand converges to zero at the same time and at a constant time change rate, a rapid change in the current reference value due to turning off the current reference output switch 5 in the conventional device. With no tension, the tension between the stands becomes zero, so it is possible to prevent the rolled material from moving backward when the rolling line is stopped.

According to the above embodiment, the current reference control means 6 which converges to zero at a constant rate of change has been described, but a PI control system with a first-order lag may be used instead. In this case, the current reference control means 6 inputs and holds the current reference value I _ref1 at the timing when the speed feedback value becomes zero. Then, the current reference value I _refH is set as the held current reference value by the following equation.
Calculate and output _ref2 .

I _ref1 → I _ref2 (3) I _ref2 = I _refH · {1-1 / (1 + T · s)} (4) where T: time constant (s) s: Laplace operator.

FIGS. 3 (a) and 3 (b) show temporal changes in the speed reference V _ref and the current reference value I _ref2 when the rolling line is stopped when the primary delay system is used as the current reference control means 6. It is a thing. In this case, the current reference control means 6 exponentially decays as time passes after the time t _{s and} becomes 3
Current reference value I _{re f2} which converges to zero when the elapsed time T
Is output. Therefore, by making the time constant of each stand constant, the current reference value I _ref2 of each stand becomes zero at the same time. Since the current reference output switch 5 is closed until the current reference value I _ref2 becomes zero, it is possible to prevent the rolling material from moving backward when the rolling line is stopped, which is a problem in the conventional apparatus.

FIG. 4 is a block diagram showing another embodiment of the present invention. In the figure, the same elements as those of FIG. 5 are designated by the same reference numerals, and the description thereof will be omitted. Here, a current detector 8, a control means 9 and a drooping gain switching means 10 are newly added to the configuration of FIG. 5, and further to the configuration of FIG. 5 using only one subtractor 3. The configuration is different from that of FIG. 5 in that two subtractors 3a and 3b are used. Also in this embodiment, the current reference output switch 5 is closed at least until the current reference value I _ref2 becomes zero after the rolling line is stopped.

Here, the subtractor 3a subtracts the speed feedback value V _FB of the speed detector 2 from the speed reference V _ref of the speed reference calculation means ₁ and outputs a speed deviation ΔV ₁ . The current detector 8 detects the current of the mill drive motor and outputs a current feedback value I _FB . The drooping correction control means 9 receives the current feedback value I _FB and outputs a drooping correction amount ΔD for correcting the speed reference according to the magnitude of the current so that the motor does not generate an excessive torque. In this case, the drooping correction control means 9 calculates the drooping correction amount ΔD by multiplying the current feedback value I _FB by the gain G ₁ or G ₂ output from the drooping gain switching means 10 according to the following equation.

ΔD = I _FB × G ₁ (G ₂ ) ... (5) The drooping gain switching means 10 has a normally closed switch 10 a and a normally open switch 10 b represented by switches.
Then, when the rolling line is in operation, the gain G ₂ arbitrarily set by the operator is output via the normally closed switch 10a and added to the drooping correction control means 9. When the rolling line is stopped, the gain G ₁ is output via the normally closed switch 10b and added to the drooping correction control means 9. On the other hand, the subtractor 3a uses the speed reference V of the speed reference calculation means 1.
The speed feedback value V _FB of the speed detector 2 is subtracted from _ref to output the speed deviation ΔV ₁ . Further, the subtractor 3b subtracts the drooping correction amount ΔD from the speed deviation ΔV ₁ to output the speed deviation ΔV ₂ and applies it to the speed control means 4.

In this case, even if the speed deviation amount ΔV ₁ becomes zero due to the stop of the rolling line, the current reference value I _ref2 is output due to the tension between each stand and the rolling static torque, so that the current detector 8 The current feedback value I _FB also continues to be input to the drooping correction control means 9. Therefore, if the drooping gain G ₁ of each stand is set in consideration of synchronization with the current reference residual value of each stand and the PI control cycle in the speed control means 4, the current reference value is determined by the drooping correction amount ΔD. It becomes zero at the same time.

If the current reference value I _ref of each stand converges to zero at the same time, there is no sudden change of the current reference value due to turning off the current reference output switch 5 in the conventional device, and each stand is not changed. Since the inter-tension is zero, it is possible to prevent the rolled material from moving backward when the rolling line is stopped. The temporal changes in the speed reference V _ref and the current reference value I _ref when the rolling line is stopped are the same as described with reference to FIG. 3, and thus detailed description thereof will be omitted.

[0021]

As is apparent from the above description, according to the present invention, it is possible to prevent the rolled material from moving backward when the rolling line is stopped, and thereby to prevent the sheet from breaking due to the rolling material moving backward. You can

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a speed reference and a current reference and time for explaining the operation of the embodiment shown in FIG.

FIG. 3 is a diagram showing a relationship between a speed reference, a current reference and time in order to explain an operation when the configuration of the main element is changed in the embodiment shown in FIG.

FIG. 4 is a block diagram showing the configuration of another embodiment of the present invention.

FIG. 5 is a block diagram showing a configuration of a conventional tandem cold mill driving device.

FIG. 6 is an explanatory view for explaining a rolling state by the conventional tandem cold mill driving device shown in FIG.

[Explanation of symbols]

 1 speed reference calculation means 2 speed detector 3, 3a, 3b subtractor 4 speed control means 5 current reference output switch 6 current reference control means 7 current reference switching means 8 current detector 9 drooping correction control means 10 drooping gain switching Means 11 Rolling roll 12 Rolled material

Claims (3)

[Claims] 1. A speed reference calculation means for calculating a speed reference value of a tandem cold mill, a speed detection means for detecting a speed of the tandem cold mill, and a calculated speed reference value and the detected speed. Subtraction means for calculating the deviation, speed control means for calculating the current reference value of the mill drive motor based on the calculated deviation of the speed, the current reference value, and a predetermined time change rate from the current reference value. Current reference control means for outputting a current reference value that converges to zero at,
During operation of the rolling line, the current reference value of the speed control means is added to the current control device of the mill drive motor, and the current reference value of the speed control means is held by the current reference control means when the rolling line is stopped. During the stop, the tandem cold mill drive device is provided with current reference switching means for applying the current reference value output from the current reference control means to the current control device of the mill drive motor instead of the current reference value of the speed control means. 2. The tandem cold mill driving device according to claim 1, wherein said current reference control means is constituted by a PI control primary delay system. 3. A speed reference calculation means for calculating a speed reference value of a tandem cold mill, a speed detection means for detecting a speed of the tandem cold mill, and a calculated speed reference value and the detected speed. A first subtracting means for calculating a deviation, a current detecting means for detecting a current of the mill driving motor, and a driver for outputting a drooping correction amount by multiplying the detected current value by a drooping gain input from the outside. A looping correction control means and a drooping gain that can be arbitrarily selected during the operation of the rolling line are added to the drooping correction control means, and after the rolling line is stopped, the output of the speed control means has a predetermined time change rate. A drooping gain switching means for adding a drooping gain that converges to zero to the drooping correction control means; and an output of the first subtraction means. The speed control means includes a second subtraction means for subtracting the output of the drooping correction control means, and a speed control means for calculating a current reference value of the mill drive motor based on the output of the second subtraction means. A tandem cold mill drive that adds the output of the above to the current controller of the mill drive motor.