JPH0299213A - Tension control device for continuous rolling mill - Google Patents

Abstract

PURPOSE:To prevent generating a loop on material to be rolled by judging the loop generating through a retaining circuit when an error is generated on a torque arm to continue outputting speed correcting value in the accelerating direction, then, maintaining the speed correcting signal to output to a speed control device. CONSTITUTION:The title device is the tension control device 11 for continuous rolling mill 8 to control the tension of the material to be rolled between the stand of its own and a stand just behind the stand. When an error is generated in the torque arm operated through an arithmetic circuit 2 for torque arm lock-on to operate and to store the torque arm of the stand of its own, the speed correcting value N is outputted during over a prescribed time in the increasing direction. After that, when the tension deviation T outputted from the tension detector 4 has the value of increasing side, the speed correcting value N outputted through a proportional integrating circuit 5 is capable of holding by a holding circuit 6. By this method, the generation of the loop of the material to be rolled is prevented previously.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a tension control device for a continuous rolling mill that continuously rolls steel plates, steel bars, etc. This invention relates to a tension control device that controls inter-stand tension using a torque arm that has a ratio of .

(Prior Art) Controlling the tension acting on a material to be rolled in a continuous rolling mill to be constant or zero is an important element in improving rolling dimensional accuracy.

FIG. 2 is a block diagram showing a schematic configuration of a conventional tension control device that performs this type of control. In the figure, when the material to be rolled is continuously rolled in the order of stand i-1, stand i, and stand i+1, each stand rolling mill 8 is driven by an electric motor 9 having a speed control device 10, respectively. In this case, the speed control device 10 of each stand includes a speed correction amount outputted by the tension control device 11 of the own stand based on the speed reference applied to the speed control device 10 of the stand immediately after the front in the moving direction of the rolled material. A speed reference is added by adding ΔN. In addition, the tension control device 1 of each stand
1 is calculated by the speed control device 11 of the rear stand.
The speed correction amount ΔN is calculated using the so-called rear tension TB.

FIG. 3 shows the relationship between signal input and output of the tension control system, especially for the i-stand.

The tension control device 11 includes an output signal from a load cell 12 that detects the rolling load, an output signal from a speed detector 13 that detects the number of rotations of the rolling mill, and a current detector 1 that detects the armature current of the electric motor 9.
4, the output signal of the voltage detector 15 that detects the armature voltage of the electric motor 9, and the rear tension signal are input, and based on these signals, the speed correction amount ΔN is calculated and added to the speed control device 10. There is. Further, the speed control device 10 controls the speed of the electric motor 9 based on this speed correction amount ΔN and the output signal of the speed detector 13.

FIG. 4 is a block diagram showing the detailed configuration of the tension control device 11, which calculates the motor output torque based on the rolling load P1, the armature current I of the heavy electric machine 9, and the rotation speed N of the rolling mill. The acceleration/deceleration current removing device 1 calculates the acceleration/deceleration torque of the electric motor, and the rolling torque C is calculated using each torque and rear tension TB determined by the acceleration/deceleration current removing device 1, and the rolling pressure P is calculated. In other words, the torque arm lock-on calculation circuit 2 calculates and outputs the torque arm, the generated tension calculation circuit 3 uses this torque arm to calculate the inter-stand tension, and the inter-stand tension and the tension setting (not shown). The tension calculation circuit 4 calculates the deviation from the set tension of the device, and the proportional integration circuit 5 performs proportional integration on this tension deviation and outputs a speed correction amount ΔN to the speed control device 10.

Next, the operation of this tension control device will be explained.

When the material to be rolled is caught in the i-stand and rolling is started, the armature current I of the electric motor 9 increases rapidly. This current is detected by the current detector 14, and at the same time, the rolling pressure P is detected by the load cell 12, and the rotation speed N of the rolling mill is detected.
are detected by the speed detector 13 and input manually to the tension control device 11, respectively.

The armature current I input to the tension control device 11 includes, in addition to the current for the rolling torque required for pure rolling, the acceleration/deceleration torque current required for accelerating and decelerating the rolling mill 8 and the electric motor 9, and the current for the friction torque of the machine. It is included. Therefore, in order to obtain the rolling torque G, the following equation must be calculated.

V-IRdN)"-26°G""Kl(N-(K N-K)-5TB......(1
) However, (1) = armature I: armature current N: rolling mill rotation speed R: armature resistance TB: rear tension 1 to 5: constant.

The first term on the right side of equation (1) above is the motor output torque, and the second term is
The term means acceleration/deceleration torque, the third term means friction torque, and the fourth term means torque due to rear tension.

The tension control device 11 controls the period from when the tip of the rolled material is bitten by the i-stand until just before it reaches the i+1 stand, that is, the period when the tension generated in the rolled material between the i-stand and the i+1+1 stand is zero. Calculate the rolling torque G using equation (1). are calculated multiple times, and these rolling torques G. The ratio G between and the rolling load P. Find /Po,
Furthermore, the average value a is determined by the following formula. Calculate.

・・・・・・・・・・・・・・・(2) This is the rolling pressure P applied to the rolling stand that bites the material to be rolled. and the pure rolling torque G required for rolling. The ratio aO follows the rolling theory that "regardless of the rolling condition, it is constant", and this average value aO is called the torque arm.

Then, when the material to be rolled further advances and its tip is bitten by the i+1 stand, a tension T 2 is generated between the i stand and the i+1 stand, so this tension T 2 is calculated using the following equation.

Here, P is the tip of the material to be rolled is i+1 stand rolling mill 8
The rolling load of the one-stand rolling mill 8 after reaching G
is the rolling torque of the one-stand rolling mill 8 at that time, and K7 is a constant. Note that GIll is determined by equation (1).

Next, the tension control device 11 calculates the deviation ΔT between the tension setting value Trel' of a tension setting device (not shown), which sets the tension between the 1st stand and the i+1 stand, and the calculated tension T, using the following equation.

△T-T□-TrOr ・・・・・・・・・・・・
(4) Next, the tension control device 11 converts the tension deviation ΔT obtained by this equation (4) into a speed correction amount T, and provides it to the speed control device 10.

The acceleration/deceleration current removing device 1 in FIG. 4 performs calculations on the first to third terms on the right side of equation (1), and delivers the calculation results to the torque arm lock-on calculation circuit 2. The torque arm lock-on calculation circuit 2 calculates the rolling torque Go based on equation (1), and then calculates the rolling torque G. While calculating the ratio of and rolling pressure Po, (
2) Calculate and store the torque arm aO of the rolling stand using the formula.

The generated tension calculating circuit 3 calculates the tension T generated between the stands by calculating the equation (3). Then, the tension calculation circuit 4 calculates the tension deviation ΔT given by equation (4). The proportional integral circuit 5 calculates this tension deviation Δ
The speed control device 10 calculates the speed correction amount ΔN by proportionally and integrating T.
Output to.

Thus, using the calculated and memorized torque arm aO,
After the tip of the material to be rolled is bitten into the adjacent stand, the tension between the own stand and the stand immediately following can be controlled to be constant or zero.

(Problems to be Solved by the Invention) The conventional tension control device described above uses the rear tension TB to determine the torque arm aO, but the rear tension control device uses the rear tension TB immediately after changing the stand type or changing the rod of the rolled material. Ta may not be stable and the torque arm aO may include a large error.

In other words, when changing the shape of the rolling stand or changing the rod of the material to be rolled, the speed setting of the rolling stand,
The pressure setting includes quite a bit of error. Therefore, when the rolled material is bitten by the immediately following stand, a compressive or tensile force acts on the rolled material between the rolling stands. Originally, tension control is performed so that the tension is constant, but the response of tension control in continuous rolling mills cannot be made fast to avoid mutual interference with the machine.
In the end, with the rear tension 1B unstable, the torque arm aO
is calculated, and by this the torque arm aO
may contain large errors.

Therefore, in the conventional tension control device, the tension must be controlled using the torque arm aO, which has a relatively large error, and when the error becomes large, the rolled material between the stands bends and forms a loop. Sometimes.

For example, when controlling the tension of the rolled material to zero, even if the tension of the rolled material between the rolling mill 8 of the i stand and the rolling mill 8 of the i+1 stand is approximately zero, the torque arm a. If it is calculated as a value larger than the tension-free torque arm, the following situation will occur, and the tension calculation circuit 4 will assume that tension is generated. Therefore, a signal of the speed correction amount ΔN in the speed increasing direction is outputted from the proportional integral circuit 5 to the speed control device 10 in order to eliminate the tension.

Therefore, a compressive force is applied to the material to be rolled between the rolling mill 8 of the i stand and the rolling mill 8 of the i+1 stand, and if the material to be rolled cannot withstand this compressive force, it will bend and a loop will be formed.

In this case, the rolling torque G and rolling load P of the rolling mill 8 of the i-stand hardly change even after the loop is formed. Therefore, the tension calculation circuit 4 assumes that a tensile force continues to be generated, and the proportional and integral circuit 5 outputs the tension to the speed control device 10.
The signal of the speed correction amount ΔN in the speed increasing direction is continued to be sent to the rolling stock, further increasing the loop of the rolled material.

The present invention has been made in consideration of these points,
It is an object of the present invention to provide a tension control device for a continuous rolling mill that can reliably prevent loops from forming in a rolled material between each stand.

[Structure of the invention]

(Means for Solving the Problems) The present invention provides a torque arm lock-on calculation circuit that calculates and stores the torque arm of its own stand of a continuous rolling mill, and a torque arm lock-on calculation circuit that calculates and stores the torque arm of its own stand of a continuous rolling mill, and a workpiece to be rolled using a signal from the torque arm lock-on calculation circuit. a generated tension calculation circuit that calculates the tension of the generated tension calculation circuit, a tension calculation circuit that calculates the tension deviation based on the signal from the generated tension calculation circuit, and a speed correction amount obtained by proportionally integrating the signals from the tension calculation circuit, and the speed of the own stand In a tension control device for a continuous rolling mill that includes a proportional integral circuit that outputs an output to a control device and controls the tension of a material to be rolled between the own stand and a stand immediately following, The present invention is characterized in that a holding circuit is connected which determines the occurrence of a loop in the rolled material based on the speed correction amount.

(Function) When an error occurs in the torque arm and the speed correction amount continues to be output in the speed increasing direction, the holding circuit determines whether a loop has occurred in the rolled material based on this speed correction amount.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing an embodiment of a tension control device for a continuous rolling mill according to the present invention. Note that the same parts as those in the prior art are given the same reference numerals and detailed explanations will be omitted.

As shown in FIG. 1, the tension control device 11 calculates the motor output torque, and also includes an acceleration/deceleration current removing device 1 that calculates the acceleration/deceleration torque of the rolling mill and the electric motor, and a tension control device 11 that calculates the motor output torque. A torque arm lock-on calculation circuit 2 that calculates and outputs a torque arm using each torque and rear tension TB, a generated tension calculation circuit 3 that calculates inter-stand tension using this torque arm, and this inter-stand tension and set tension. The tension calculation circuit 4 is configured to calculate the deviation between the tension force deviation and the proportional integration circuit 5 which proportionally integrates this tension deviation and outputs a speed correction amount ΔN to the speed control device 10.

Further, a holding circuit 6 is connected to the proportional-integral circuit 5. This holding circuit 6 receives the speed correction amount △ from the proportional integral circuit 5.
It is detected that N continues to be accelerated in the speed increasing direction for more than a predetermined time and is output, and the tension deviation △T output from the tension detector 4 after the elapse of this predetermined time is on the speed increasing side (tension side). This is to detect that the value is greater than or equal to a predetermined value. In this way, when the holding circuit 6 detects that the speed correction amount ΔN is output in the speed increasing direction for a predetermined period of time or more and that the tension deviation has a value of T or more than the predetermined value, the holding circuit 6 detects a loop in the rolled material. It is determined that this occurs, and a holding signal is output to the proportional-integral circuit 5.

Next, the operation of this embodiment having such a configuration will be explained.

First, the armature current I, rolling load P, and rolling mill rotation speed N of the rolling mill 8 of the i-stand are input to the acceleration/deceleration current removing device 1.

As with the conventional device, the rolling torque G is determined by equation (1) during the period from when the tip of the material to be rolled is bitten by the rolling mill 8 of the i stand until it reaches the vicinity of the rolling mill 8 of the i+1 stand.
and rolling load P. The acceleration/deceleration current removal device 1 and the torque arm lock-on calculation circuit 2 calculate the average value of the ratio G o /P o.

Then, this calculation result is stored in the torque arm lock-on calculation circuit 2 as a torque arm a□.

Next, in the generated tension calculation circuit 3, the tension T of the material to be rolled is
is calculated using equation (3), and the tension calculation circuit 4 calculates this tension T.
and tension setting value T, 8. The tension deviation T is calculated using equation (4). This tension deviation △T
is sent from the tension calculation circuit 4 to the proportional integration circuit 5, which proportionally integrates the tension deviation ΔT and outputs it as a speed correction amount ΔN.

Next, if an error occurs in the calculated torque arm aO,
As shown in equation (5), even if the tension of the material to be rolled is approximately zero, T > 0.

In this case, even though the speed correction amount ΔN continues to be output in the speed increasing direction, the tension deviation ΔT output from the tension detector 4 may take a value on the speed increasing side (tension side).

In this way, the speed correction amount ΔN is output from the proportional integral circuit 5 in the speed increasing direction for a predetermined time or more, and then the tension calculator 4
When the tension deviation ΔT takes a value equal to or greater than a predetermined value on the speed increasing side, the holding circuit 6 determines that a loop will occur in the rolled material and outputs a holding signal to the proportional-integral circuit 5. The proportional-integral circuit 5 to which the holding signal is input holds the speed correction amount ΔN output from the proportional-integral circuit 5 to the speed control device 10.

According to this embodiment, an error occurs in the torque arm ao calculated by the torque arm lock-on calculation circuit 2, and the speed correction amount ΔN is outputted in the speed increasing direction from the proportional integral circuit 5 for a predetermined time or more, and If the tension deviation ΔT output from the tension detector 4 takes a value on the speed increasing side after that, the speed correction amount ΔN is output from the proportional-integral circuit by the holding circuit 6.
Since the rolling material can be held, it is possible to prevent the occurrence of loops in the rolled material.

In the above embodiment, when the speed correction amount ΔN is output in the speed increasing direction for a predetermined time or longer and the tension deviation T takes a value equal to or larger than the predetermined value in the speed increasing direction, the holding circuit 6 An example of determining whether a loop has occurred is shown. However, the present invention is not limited to this, and the value is integrated from the time when the speed correction amount ΔN is output in the speed increasing direction, and is used as the traveling distance correction amount of the rolled material, and this amount is monitored to generate a loop of the rolled material. may be judged.

In addition, the holding signal from the holding circuit 6 is displayed on a display, etc. (not shown).
may be input, the display may be used to give a warning to the operator, and the speed control device IO may be manually operated to maintain the speed correction amount according to the operator's judgment.

〔Effect of the invention〕

As explained above, according to the present invention, when an error occurs in the calculated torque arm and the speed correction amount continues to be output in the speed increasing direction, the holding circuit determines the occurrence of a loop in the rolled material from this speed correction amount. . Thereafter, by holding the speed correction signal output to the speed control device, it is possible to prevent loops from occurring in the rolled material.

It is a block diagram.

DESCRIPTION OF SYMBOLS 1... Acceleration/deceleration current removal device, 2... Torque arm lock-on calculation circuit, 3... Generated tension calculation circuit, 4...
- Tension calculation circuit, 5... Proportional integral circuit, 6... Holding circuit, 8... Rolling machine, 9... Electric motor, 10... Speed control device, 11... Tension control device, 12 ...Load cell, 13...Speed detector, 14...Current detector, 1
5...Voltage detector.

Claims (1)

[Claims] a torque arm lock-on calculation circuit that calculates and stores the torque arm of its own stand of the continuous rolling mill; a generated tension calculation circuit that calculates the tension of the rolled material based on a signal from the torque arm lock-on calculation circuit; The tension calculation circuit calculates a tension deviation based on a signal from the tension calculation circuit, and the proportional integration circuit outputs a speed correction amount obtained by proportionally integrating the signal from the tension calculation circuit to the speed control device of the own stand. In a tension control device for a continuous rolling mill that controls the tension of a rolled material between a stand and a stand immediately after, the proportional-integral circuit is configured to generate a loop in the rolled material from the speed correction amount that continues to be output in the speed increasing direction. A tension control device for a continuous rolling mill, characterized in that a holding circuit for judgment is connected.