JP2000263115A - Tension controller for continuous rolling mill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tension controller for continuous rolling mills with which a torque arm whose error is small is obtained and stable rolling is executed even when back tension becomes unstable. SOLUTION: A comparing/selecting circuit 2c is added between a torque arm arithmetic circuit 2c and a torque arm lock-on circuit 2b so as not to deliver as the sampling value of an inappropriate torque arm lock-on circuit 2b by referring to a torque arm table 6. In the torque arm table 6, the torque arm a0' of a rolling stand when a stable condition of rolling is realized is learned and stored about every kind of rolled stocks. With the comparing/ selecting circuit 2c, the ratio (Gm/P) of the rolling torque Gm to rolling pressure P which is calculated with the torque arm arithmetic circuit 2a and the torque arm a0' are compared and, when the deviation is over a specified value, the ratio (Gm/P) is selected so as not to deliver to the torque arm lock-on circuit 2b as the sampling value at the time of calculating the torque arm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuous rolling mill for continuously rolling a rolled material, and more particularly to a tension control device for controlling a tension between stands using a torque arm.

[0002]

2. Description of the Related Art Controlling the tension acting on a rolled material in a continuous rolling mill to be constant or zero can be said to be an important factor in improving the dimensional accuracy of rolling. FIG. 2 is a block diagram showing the configuration of a general tension control system that performs this type of control. Rolled material is i-1 stand, i stand, i +
The rolling is continuously performed in the order of one stand, and the rolling mill 8 of each stand is driven by an electric motor 9 having a speed control device 10. When viewed in the moving direction of the rolled material, the moving direction of the rolled material with respect to its own stand is referred to as a downstream stand, and the reverse direction is referred to as an upstream stand.

[0003] The speed control device 10 of each stand has a speed target value added to the speed control device 10 of its own stand,
Speed correction amount Δ output by the tension controller 11 of the stand
A speed reference to which a correction amount in consideration of Ni and a speed correction amount ΔNi + 1 output from the tension controller 11 from the downstream stand is added is given. Further, the tension control device 11 of each stand calculates the speed correction amount ΔN using the tension calculated by the tension control device 11 of the upstream stand, so-called rear tension Tb.

FIG. 3 shows the relationship between the signal input and output of the tension control system, particularly for the i-stand. The tension control device 11 includes: a rolling pressure P detected by a rolling pressure gauge 12; a rotation speed N of a rolling mill detected by a speed detector 13; an armature current I of the electric motor 9 detected by a current detector 14; The speed correction amount ΔNi is calculated based on the tension Tb and applied to the speed control device 10. The speed control device 10 determines the speed of the electric motor 9 based on the speed reference obtained by adding the speed correction amount ΔNi to the speed target value of the own stand and the rotation speed N of the rolling mill detected by the speed detector 13 attached to the electric motor 9. Control.

FIG. 4 is a block diagram showing a detailed configuration of the tension control device 11. As shown in FIG. An acceleration / deceleration current removing device 1 for calculating a motor output torque, an acceleration / deceleration torque and a friction torque of a rolling mill including a motor based on a rolling pressure P, a rotation speed N of a rolling mill, and an armature current I of the motor 9; The motor output torque determined by the acceleration / deceleration current removing device 1;
A torque arm calculation that calculates a rolling torque Gm using the acceleration / deceleration torque, the friction torque, and the rear tension Tb, and further calculates a ratio (Gm / P) between the rolling torque Gm and the rolling pressure P at predetermined intervals. A circuit 2a and a ratio (Gm / P) between the rolling torque Gm and the rolling pressure P calculated by the torque arm calculation circuit 2a are sampled, and an average of the obtained sampled values is obtained to obtain a torque arm a0. Arm lock-on circuit 2b for storing the tension, a tension calculation circuit 3 for calculating the inter-stand tension Tm using the torque arm a0, and calculating a deviation between the inter-stand tension and a set tension Tref of a tension setting device (not shown). And a proportional integration circuit for proportionally integrating the tension deviation and outputting the result.

Next, the operation of the tension control device 11 will be described. 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 sharply increases. This current is detected by a current detector 14, at the same time the rolling pressure P is detected by a rolling manometer 12, and the number of revolutions N of the rolling mill is detected by a speed detector 13 and input to the tension control device 11, respectively. .

The armature current I input to the tension control device 11 includes not only the rolling torque required for pure rolling, but also the acceleration / deceleration torque required to accelerate / decelerate the rolling mill 8 and the electric motor 9 and the friction torque of the machine. And the like. Therefore, in order to obtain the rolling torque Gm, the following equation must be calculated.

[0008]

(Equation 1)

The accelerating / decelerating current removing device 1 is generated in a period from the time when the leading end of the material to be rolled is caught in the i-stand to just before reaching the i + 1-th stand, that is, in the material to be rolled between the i-th stand and the i + 1-th stand. During the period when the tension is zero, the motor output torque of the first term on the right side of the above equation (1),
The second term acceleration / deceleration torque and the third term friction torque are calculated. The torque arm operation circuit 2a receives the rear tension Tb, calculates the torque due to the rear tension shown in the fourth term on the right side of the above equation (1), and calculates the rolling torque Gm according to the equation (1). Is calculated at 1000 times / sec.
Further, the ratio (Gm / P) between the rolling torque Gm and the rolling pressure P is determined.

The torque arm lock-on circuit 2b samples the ratio (Gm / P) of the rolling torque Gm and the rolling pressure P n times, for example, about 50 times, and obtains an average value a by the following equation.
Calculate 0 and store it.

[0011]

(Equation 2)

This is because the ratio between the rolling pressure P applied to the rolling stand in which the material to be rolled is engaged and the pure rolling torque Gm required for the rolling is "constant irrespective of the rolling state". And the average value a0
Is called a torque arm. And the rolled material goes further,
When the tip is caught in the (i + 1) -th stand, a tension Tm is generated between the (i) -th stand and the (i + 1) -th stand. The tension calculation circuit 3 calculates the tension Tm using the following equation.

[0013]

(Equation 3)

The tension deviation calculation circuit 4 comprises an i-stand and an i +
Deviation ΔT between the tension set value Tref of a tension setter (not shown) for setting the tension between one stand and the calculated tension Tm
Is calculated by the following equation.

[0015]

(Equation 4)

Next, the proportional integration circuit 5 proportionally integrates the tension deviation ΔT obtained by the equation (4) to obtain a speed correction amount ΔT.
It is given to the speed control device 10 as N. As described above, the tension control device 11 uses the calculated and stored torque arm to control the tension between the stands in front of the own stand after the tip of the material to be rolled into the adjacent stand to be constant or zero.

[0017]

The above-mentioned conventional tension control device uses the rear tension Tb to obtain the torque arm a0. However, immediately after the change of the rolling stand or the change of the lot of the material to be rolled, the tension arm T0 is used. In some cases, the rearward tension is not stable, and a large error may be included in the torque arm a0. By changing the type of rolling stand or changing the material to be rolled,
The speed setting and rolling reduction of the rolling stand include a considerable amount of error. For this reason, when the material to be rolled is bitten by the next stand, a force in the direction of compression or tension acts on the material to be rolled between the rolling stands. Originally, tension control was performed to keep the tension constant.However, the control response of the tension control in a continuous rolling mill could not be made fast to avoid mutual interference with the machine, and eventually the back tension was reduced. In an unstable state, the torque arm a0 of the own stand is calculated, and this causes a large error in the torque arm a0.

Therefore, in the conventional tension control device,
Tension control must be performed using a torque arm value having a relatively large error, which causes a problem that it is difficult to obtain a product with high dimensional accuracy.

In order to solve the above-mentioned problems, the present invention is to obtain a product having high dimensional accuracy by stable rolling even when the backward tension is not stable due to a change of a mold or a lot of a material to be rolled. It is an object of the present invention to provide a tension control device capable of performing the following.

[0020]

According to the present invention, in order to achieve this object, the invention according to claim 1 is characterized in that the leading end of the rolled material is caught in its own stand and then caught in an adjacent stand. Computing means for computing the ratio between the rolling torque and the rolling pressure of the own stand, and computing memory means for sampling this ratio n times, computing the average value and storing it as a torque arm. In the tension control device of the continuous rolling mill that controls the forward tension of the self-stand after the tip of the rolled material is bitten into the adjacent stand using the torque arm stored in the stable rolling for each predicted rolling condition Means for storing the torque arm in the state, a ratio between the rolling torque and the rolling pressure calculated by the calculation storage means, and a torque arm of the storage means, and a deviation thereof. If not within the predetermined range, characterized in that sampling values and a exclude comparative selection means from sampling target of the operation storage unit.

The invention described in claim 2 is characterized in that the storage means is provided with a correction circuit for correcting the fluctuation of the torque arm. The invention described in claim 3 is
The tension control device for a continuous rolling mill according to claim 1, wherein the torque arm is input by an operator.

According to the present invention, a standard torque arm for a predicted rolling schedule and a rolling material is stored, and this torque arm is compared with the calculated rolling torque and rolling pressure ratio. However, since the deviation exceeding a predetermined value is excluded from the sampling target of the torque arm calculation, even if the rear tension becomes unstable due to a type change or a lot change of a material to be rolled, a torque with a small error is obtained. An arm is obtained, whereby a product with high dimensional accuracy can be obtained by stable rolling.

[0023]

FIG. 1 is a block diagram showing a configuration according to an embodiment of the present invention. Elements denoted by the same reference numerals as those in FIG. 4 indicate the same elements. In the present embodiment, an inappropriate torque arm lock-on circuit 2b is provided between the torque arm calculation circuit 2a and the torque arm lock-on circuit 2b with reference to the torque arm table 6 for the components shown in FIG. And a comparison / selection circuit 2c for preventing the data from being transferred as a sampling value.

Here, the torque arm table 6 is for learning and storing the torque arm a0 'of the rolling stand for each rolling schedule and rolling material when a stable rolling state is realized. Also, the comparison selection circuit 2
c is a comparison between the ratio (Gm / P) between the rolling torque Gm and the rolling pressure P calculated by the torque arm calculation circuit 2a and the torque arm a0 'of the torque arm table 6, and the deviation exceeds a predetermined value. Time, torque arm operation circuit 2a
The ratio (Gm) of the rolling torque Gm and the rolling pressure P calculated by
/ P) is selected as a sampling value for calculating the torque arm so as not to be transferred to the torque arm lock-on circuit 2b.

The operation of the embodiment constructed as described above will be described below. First, when a stable rolling state is achieved by manual intervention of the operator,
When the speed setting between the rolling stands is balanced and a product with good dimensional accuracy is obtained, the torque arm a0 'of each stand is stored in the torque arm table 6 by the judgment of the operator or the like. This is performed in a state where the tension control is “off”, that is, in a state where the speed correction amount ΔN is not output to the speed control device 10. By performing this operation every time the rolling schedule and the rolling material are different, each torque arm a0 ′ corresponding to the rolling schedule, the rolling material and the like is stored in the torque arm table 6.

Next, when a new rolling is started by changing the mold, changing the lot of the material to be rolled, or the like, the acceleration and deceleration are performed between the time when the leading end of the material to be rolled is caught in the own stand and immediately before it is caught in the adjacent stand. The current removing device 1 performs the calculation of each term from the first term to the third term on the right side of the equation (1), and delivers the calculation result to the torque arm calculation circuit 2a. The torque arm calculation circuit 2a calculates the rolling torque Gm based on the equation (1), and then calculates the ratio (Gm / P) between the rolling torque Gm and the rolling pressure P. Here, the comparison and selection circuit 2c calculates the ratio (Gm / P) between the rolling torque Gm and the rolling pressure P calculated by the torque arm calculation circuit 2a, the same schedule and the same material stored in the torque arm table 6 in advance. Is compared with the torque arm a0 ′ using the following equation.

[0027]

(Equation 5)

Then, a comparison between the rolling torque Gm calculated by the torque arm calculating circuit 2a and the rolling pressure P (Gm /
If P) is not within the range of the expression (5), it is determined that the value includes a large amount of error, and the torque arm determination circuit 2
c is the ratio (Gm / P) of the torque arm lock-on circuit 2.
Stop passing the sampling value to b. As a result, the torque arm a0 calculated by the equation (2) has a plurality of rolling torques Gm and rolling pressures P satisfying the equation (5).
Of the torque arm a0 having a small error.
Can be calculated. If it is assumed that the torque arm lock-on circuit 2b averages 50 sampling values and the comparison and selection circuit 2c stops delivering as sampling values, only 49 sampling values are obtained. Data will be averaged. However, if the number of sampling values excluded by the comparison and selection circuit 2c is large and the number n to be averaged is less than a certain value, the tension control is not executed, or the tension control is performed using the standard torque arm a0 'as the torque arm a0. It is necessary to take measures such as executing. By providing the torque arm a0 obtained in this manner to the tension calculation circuit 3, a stand-to-stand tension with a small error can be obtained, and high-precision rolling can be realized even when the rear tension Tb is unstable. can do.

In the above embodiment, the value obtained by learning and storing the torque arm a0 'using the torque arm table 6 is used. Instead, a setting device for setting the torque arm a0' for each rolling stand is provided. Alternatively, the torque arm a0 ′ set by the operator may be used to make a comparison using equation (5). According to this equation, the torque arm value of each rolling stand can be set arbitrarily.

On the other hand, the value of the torque arm a0 or a0 'of each stand may slightly change depending on various conditions such as thermal rundown of the material to be rolled and skid marks. If a circuit is added to each of the torque arm tables 6, the dimensional accuracy can be further improved. in this case,
As a correction circuit, it is conceivable to use a variable resistor, or use a detector for a rolling load and a rolling temperature.

[0031]

As described above, according to the present invention,
The standard torque arm was compared with the calculated rolling torque to rolling pressure ratio, and a value whose deviation exceeded a predetermined value was not used as a sampling value for torque arm calculation. By lot change
Even if the back tension may become unstable, a torque arm with a small error can be obtained, whereby a product with high dimensional accuracy can be obtained by stable rolling.

[Brief description of the drawings]

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

FIG. 2 is a block diagram of a general tension control system of a continuous rolling mill.

FIG. 3 is a block diagram showing signal input / output of a general tension control system of a continuous rolling mill.

FIG. 4 is a block diagram showing a configuration of a conventional tension control device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Acceleration / deceleration current removal device 2a Torque arm calculation circuit 2b Torque arm lock-on circuit 2c Comparison / selection circuit 3 Tension calculation circuit 4 Tension deviation calculation circuit 5 Proportional integration circuit 6 Torque arm table 10 Speed controller 11 Tension controller

Claims (3)

[Claims] An arithmetic means for calculating a ratio between a rolling torque and a rolling pressure of a self-stand from a time when a leading end of a rolled material is bitten into a self-stand to a bite in an adjacent stand, and samples the ratio n times. Calculating means for calculating an average value and storing the calculated value as a torque arm, and using the torque arm stored in the calculating and storing means, the self-stand after the leading end of the rolled material is bitten by the adjacent stand. Means for storing a torque arm in a stable rolling state for each predicted rolling condition in the tension control device for a continuous rolling mill for controlling the forward tension of the rolling torque and the rolling pressure calculated by the calculation storage means Is compared with the torque arm of the storage means, and if the deviation is not within a predetermined range, the sampling value is compared with the sampling arm of the operation storage means. Further comprising a comparison and selection means to exclude from the continuous rolling mill tension control device according to claim. 2. A storage device according to claim 1, wherein said storage means includes a correction circuit for correcting fluctuations of said torque arm.
A tension control device for a continuous rolling mill as described above. 3. The tension control device for a continuous rolling mill according to claim 1, wherein the torque arm is input by an operator.