JP2749754B2 - Rolling schedule setting method for reversible rolling mill - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for setting a rolling schedule of a reversible rolling mill.

[0002]

2. Description of the Related Art As shown in FIG. 3, a reversible rolling mill is provided with transfer rolls 2 and 3 on both sides of a roll 1 in a moving direction of a material 4 to be rolled. The rolled material 4 is transported from one side to the other side through the rolling roll 1 by the transfer roll 2 with respect to the rolling roll 1 to roll the rolled material 4 to a constant thickness. Then, the rolling roll 1 is positioned at a narrower rolling position than the previous time, and the material 4 to be rolled is transferred to the rolling roll 1 from one side to the other side by the transfer roll 2 through the rolling roll 1. The material to be rolled 4 is rolled. (path).

[0003] Rolling is performed by repeating this operation. The time during which the material 4 to be rolled between passes does not pass through the rolling roll 1 is called idle time. The rolls 1, 2, and 3 are driven to rotate by an electric motor (not shown).

[0004] In a conventional rolling method using a reversible rolling mill, a method is used in which rolling is performed with the shortest number of passes at a predetermined thickness within the allowable power range of the rolling mill. However, in reversible rolling mills, since acceleration and deceleration are repeated, aiming for a rolling schedule in the shortest time even though load fluctuations are severe, it is impossible to roll due to a rise in the temperature of the drive motor. There is a problem that becomes.

[0005] This is because the rolling mill is stopped and the rolling mill is stopped in order to prevent the motor from burning due to a rise in the temperature of the motor when the rolling roll is driven to rotate.

Therefore, as means for solving this problem, the maximum allowable power of the rolling mill (the maximum value of usable power determined by the specifications of the electric motor) and the root mean square of the allowable rolling current (as shown in Equation 1) The rolling schedule that satisfies both the allowable range of the value of the square root of the time average of the work of the electric motor and the thermal protection constraint) and that minimizes the rolling time is calculated by changing the idle time. A control method aimed at improving the efficiency by controlling the rolling process has been proposed (Japanese Patent Publication No. 2-9).
No. 521).

[0007]

(Equation 1)

[0008]

In the conventional control method, rolling specifications such as an inlet temperature, a slab thickness, and an outlet temperature are determined.
When the values of the load, torque, speed, and the like determined by the specifications of the rolling mill are known, the minimum number of passes is obtained from the rolling power curve and the equation of minimum number of passes = required total power / maximum allowable rolling power.

Then, it is determined whether or not the power and the rolling current square mean in the number of passes are within the allowable range of the rolling mill. If the power is within the allowable range, the number of passes is regarded as the rolling schedule. If outside, the idle time is lengthened, and the rolling current root mean square is lowered to calculate. However, in this control method, even if the power in the rolling schedule and the rolling current square mean fall within the allowable range of the rolling mill, there is a case where the value of the rolling mill within the allowable range does not become the value that brings out the capability of the rolling mill. Outside the range, the idle time is lengthened, so that the time not required for rolling increases and the rolling efficiency decreases. As a result, there is a problem that the capacity within the allowable power range of the rolling mill cannot be used to the maximum.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for setting a rolling schedule of a reversible rolling mill that makes the most of the capability within the allowable power range of the rolling mill. And

[0011]

In order to achieve the above-mentioned object, a method for setting a rolling schedule of a reversible rolling mill according to the present invention, when setting a rolling schedule of a reversible rolling mill, does not exceed an allowable maximum rolling power and A coefficient for setting a power upper limit value for each path so that the average power value including the idle time of each path is equal to the limit of the constraint condition due to the thermal protection of the motor and the power supply is calculated for each path, and then the calculated coefficient is calculated. Multiplying the allowable maximum rolling power to obtain a set power upper limit value for each pass, and then calculating a rolling speed and a rolling reduction of the rolling roll to realize the set power upper limit value obtained for each pass. .

[0012]

The setting method of the present invention does not exceed the allowable maximum power of the rolling mill while considering the minimum no-load idle time and the time of each pass conceivable due to the rolling conditions of each pass and equipment restrictions. The power upper limit value is set by multiplying the coefficient by which the average value is equal to the maximum value of the rolling current root mean square, and the rolling speed of each pass and the rolling reduction of the rolling roll are calculated so that the power upper limit value is obtained. Set the rolling schedule for time and maximum efficiency.

By introducing the predicted rolling time of each pass and the shortest idle time to the coefficient for setting the power upper limit value as described above, the coefficient is made effective in each pass, and the idle time is increased. It is possible to eliminate the waste of the current square mean by adjusting the power average.

Also, by taking into account the allowable maximum rolling power and the allowable maximum value of the current square mean in this coefficient, the power upper limit at which the power average value does not exceed the allowable maximum rolling power and the power average value becomes equal to the allowable maximum value of the current square mean. You can set the value.

[0015] Therefore, by the interaction of these, the rolling roll
In the state where the temperature of the motor driving the motor is ensured, the rolling schedule of the shortest time and the maximum efficiency can be set.

[0016]

An embodiment of the present invention will be described with reference to the drawings.

The present invention is directed to a method for setting a schedule for rolling a material to be rolled in a reversible rolling mill shown in FIG.

A method of setting a rolling schedule according to the present embodiment will be described with reference to FIG.

First, the pass schedule of the material to be rolled is calculated based on the conditions such as the shape and dimensions and the material of the material to be rolled and the rolling reduction table determined from the allowable value of the specification of the rolling mill (SP1).

Next, in this pass schedule, rolling conditions such as rolling load, rolling torque, rolling power and the like in each pass are determined by setting calculation using the maximum speed of the rolling mill as an initial value (SP2).

Next, a coefficient for determining a power upper limit value (a set upper limit value that is actually used by multiplying the upper limit value by a coefficient in consideration of a thermal load constraint) is calculated for each path based on the following conditions. . That is, a coefficient for setting the power upper limit value is determined so that the average value of the power including the idle time of each path does not exceed the allowable maximum stress and is equal to the limit of the constraint due to the thermal protection of the electric motor and the power supply. (SP3).

In this embodiment, the current root mean square is used as a constraint for thermal protection, and the coefficient for setting the upper power limit is determined so as to satisfy Equation 2. In Equation 2, the allowable maximum value of the current mean square means the motor specification maximum value of the current mean square.

[0023]

(Equation 2) Next, the calculated coefficient is determined by the specifications of the rolling mill.
Is multiplied by the permissible maximum rolling power shown in the power-speed curve of (1) to obtain a set power upper limit value for each pass (SP4).

Next, it is determined whether or not the calculated power value falls within the allowable range of the set power upper limit (SP5).

If the calculated power value falls within the allowable range, a rolling schedule is determined (SP6). If the calculated power value does not fall within the allowable range, the speed is set so that the calculated power value becomes the set power upper limit value, and the speed is calculated again at that speed to obtain the speed (SP7), (SP8),
(SP9).

The setting method of the present invention will be described.

A power-speed curve (solid line) as shown in FIG. 4 is determined according to the specifications of the rolling mill. In the present invention, since the thermal load of the motor is taken into account (since the rolling is performed continuously, the calorific value of the motor is integrated), the set value of the power upper limit is set to the specified maximum power upper limit indicated by the solid line in the figure. It is necessary to lower the level as shown by the broken line in the figure.

In order to reduce the set upper limit of the power, a coefficient is multiplied by the upper limit of the specified maximum power (allowable maximum rolling power). This coefficient satisfies Equation 2.

Also, in all rolling schedules,
The power upper limit can be set by calculating a coefficient for each path so as to satisfy this constraint.

When the average value of the power of each pass exceeds the upper limit of power set as described above during rolling, the speed is reset so as to reach the upper limit of power. If the speed is smaller than the base speed, the value in the rolling reduction table is reduced, the number of passes is increased, and the calculation is performed again to make the speed equal to or higher than the reference value.

In this way, a rolling schedule is determined in which the average power has a reduction and speed corresponding to the limits of the thermal protection constraints of the motor without exceeding the maximum allowable power.

Next, a comparison between the method of the present invention and the conventional method will be described with reference to FIG.

In FIG. 2, A represents the current root mean square limit value, and B represents the current root mean square transition.

FIG. 2 (b) is a diagram showing the rolling time progress and the transition of the current mean square in the rolling employing the method of the present invention. FIG. 2 (a) is a diagram showing the rolling time progress in the rolling not employing the method of the present invention. FIG. 3 is a diagram showing a change in a mean square current;
In each diagram, the vertical axis indicates the current root mean square, and the horizontal axis indicates the elapse of the rolling time.

A comparison between FIG. 2A and FIG. 2B shows that the current root mean square does not exceed the limit value in both cases. The efficiency of the power that can be supplied per hit is about 6 in this case.
% Can be improved.

In this embodiment, the current root-mean-square is mentioned as the thermal protection constraint of the electric motor, but other factors such as electronic thermal or a combination thereof may be used.

[0037]

As described above, according to the rolling schedule setting method of the reversible rolling mill of the present invention, the rolling power curve satisfies the allowable maximum current root mean square, and reflects the rolling time and the constant idle time. The set power upper limit value is controlled using the coefficient, so that not only the problem that rolling cannot be performed due to the temperature rise of the electric motor for driving the rolling rolls can be solved, but also the length of idle time which is a problem of the conventional method. , And the shortest and maximum rolling schedule within the allowable range can be obtained.

[Brief description of the drawings]

FIG. 1 is a flowchart showing one embodiment of a rolling schedule setting method of the present invention.

FIG. 2 (a) is a diagram showing a mean square current in rolling in which the method of the present invention is not employed. (B) is a diagram showing a current square mean in rolling employing the method of the present invention.

FIG. 3 is a diagram showing a basic configuration of a reversible rolling mill.

FIG. 4 is a diagram showing a power-speed curve in a rolling mill.

[Explanation of symbols]

 1. Rolling roll, 2, 3 Transfer roll, 4 ... Rolled material.

Claims (1)

(57) [Claims] When a rolling schedule of a reversible rolling mill is set, an average power value including an allowable maximum rolling power and including an idle time of each pass is determined by a limitation of a constraint condition due to thermal protection of a motor and a power supply. A coefficient for setting the power upper limit value to be equal is calculated for each pass, then the calculated coefficient is multiplied by an allowable maximum rolling power to obtain a set power upper limit value for each pass, and then obtained for each pass. A method for setting a rolling schedule for a reversible rolling mill, comprising calculating a rolling speed and a rolling reduction of a rolling roll for realizing the set power upper limit value.