JP2650564B2 - Method for determining rolling schedule of continuous rolling mill - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for determining a rolling schedule for a continuous rolling mill.

[0002]

2. Description of the Related Art In a cold continuous rolling mill in which a plurality of stands are provided, and a material such as a strip is continuously passed through these stands and the material to be rolled is rolled, the inlet side plate thickness and the output of each stand are obtained. When determining the basic rolling schedule that indicates the side plate thickness, the rolling conditions of each stand, ie, the reduction ratio,
The basic rolling schedule has been determined so that each stand can be balanced with respect to the motor power ratio of each stand and the ratio of the energy input to the material to be rolled by each stand.

[0003] In a cold continuous rolling mill, it is necessary to distribute the balance of the above items between stands in accordance with the capacity of the mill. In addition, it causes breakage of the material to be rolled and impairment of the function of the cold continuous rolling mill. For this reason, maintaining a predetermined optimal balance between the stands of the above items leads to an improvement in plate thickness accuracy and an increase in yield.

However, with the diversification of required product specifications, simply balancing the three items described above among the stands will result in any of the stands having the following operating conditions. There is a risk of exceeding seven types of limit values.

[0005] The first limit value is an absolute load value which is a limit value at which the mill is broken when a load more than that is applied, and the second limit value.
The limit value is the maximum value of the line load, which is the limit value at which heat scratch occurs when a line load more than is applied, and the third limit value is the limit value at which non-contact between rolls occurs when a line load less than that is applied. A certain minimum linear load, a fourth limit is a maximum torque value that is a limit value at which a drive system is destroyed when a torque greater than that is applied, and a fifth limit value is a value at which a roll is applied when a greater stress is applied thereto. Deformation maximum between rolls Hertz stress, 6th
Is the limit value at which the slippage occurs when the neutral point position is less than the neutral point position, and the seventh limit value is the limit value at which the rolling function becomes impossible due to insufficient rolling capability when the neutral point position becomes less than the neutral value. Rolling power limit value.

Conventionally, when each stand exceeds such a limit value, generally, a rolling mill operator modifies the above-mentioned basic rolling schedule or adjusts the roll gap of each stand based on experience. Although the correction was directly performed, in this case, the basic rolling schedule or the roll gap was simply corrected without considering the balance of each stand.

Further, regarding the rolling power limit value,
When the rolling power exceeds the limit value, the difference between the rolling power and the rolling power limit value is calculated from the entrance side thickness and the exit side thickness of the stand with respect to the rolling power. A method of maintaining the balance of the rolling power in each stand by allocating to other stands based on a conversion coefficient for converting the rolling power change amount of the stand and a load distribution ratio between the stands is disclosed in
No. 233003.

[0008]

However, in the above-described method for maintaining the balance of the rolling power at each stand, since any limit value other than the rolling power limit value is not taken into account, any one of the stands has a rolling power limit value. When the limit value other than the limit value is exceeded, the operator must make the correction as described above. Therefore, the balance regarding the limit value other than the rolling power limit value at each stand is lost, and the tension between stands, dimensions, Not only the accuracy and the shape accuracy cannot be properly secured, but in the worst case, there is a possibility that the material to be rolled is broken and the rolling mill is broken.

The present invention has been made in view of such circumstances, and when any one of the plurality of limit values regarding the operating conditions of rolling exceeds the limit value, the value regarding the limit value of the stand is changed. To provide a method for determining a rolling schedule of a continuous rolling mill that can be adjusted to a value that does not reach the limit value and that can maintain a balance between stands regarding rolling conditions of a basic rolling schedule in other stands. With the goal.

[0010]

SUMMARY OF THE INVENTION A rolling schedule determining method for a continuous rolling mill according to the present invention is a method for determining a plurality of rolling conditions between stands of a continuous rolling mill for continuously rolling a material to be rolled .
One of the basic rolling schedules is determined so as to achieve a predetermined balance, and based on the determined basic rolling schedule, execution of the basic rolling schedule allows a plurality of operating conditions to be satisfied for each stand to perform a normal operation. It is determined whether or not the operating condition of each stand exceeds each limit value. For the stand of the operating condition determined to exceed any one of the limit values, the thickness of the entrance side of the stand for the operating condition is determined. Correcting the portion of the basic rolling schedule relating to the stand based on the influence coefficient of the exit side plate thickness so that the operating condition does not exceed the limit value, and the operating condition of the stand determined to not exceed the limit value. The above-mentioned plurality of pressures determined in advance based on the influence coefficients of the entrance side thickness and the exit side thickness of the stand with respect to the rolling conditions.
The part of the basic rolling schedule relating to the stand concerned is corrected so as to achieve a predetermined balance of any of the rolling conditions, and the operating condition of each stand does not exceed the respective limit value.
In this case, the modified basic rolling schedule is determined as a rolling schedule.

[0011]

According to the present invention, a plurality of rolling operations between stands are performed.
Basically, one of the conditions must be balanced
Calculate the rolling schedule and use this basic rolling schedule
For a stand having operating conditions that exceed the respective limit values of a plurality of operating conditions that should be satisfied to perform normal operation when executed , basic rolling is performed so that the operating conditions of the stand do not exceed the limit values. portion relating to the stands is modified in the schedule, the abnormal operation arising in connection with the limit values is suppressed, also the stand of the operating conditions does not exceed the limit value, the rolling conditions previously determined Bas
Since lance portions is modified relating to the stand in the basic rolling schedule to be kept, be modified basic rolling schedule in relation to the limit value as described above, the other which is likely caused by the modification stand
The imbalance in the rolling conditions between the two is suppressed.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings showing the embodiments. FIG. 1 is a schematic diagram showing a configuration of an example of a cold continuous rolling mill applied to the implementation of a rolling schedule determining method for a continuous rolling mill according to the present invention (hereinafter, referred to as the present invention method).

[0013] The cold continuous rolling mill includes first to fifth stands.
The stand 5 is composed of five stands, and the first to fifth stands 5 are configured to continuously roll the rolled material 6 as a steel plate. The first stand 5 to the fifth stand 5 include a pair of work rolls 1a, 1a to
5a, 5a and a pair of backup rolls 1b, 1b to 5b,
5b. Work roll 1a, 1a-5a, 5a
Of the work rolls 1c, 1c to 5c, 5c is adjusted by a rolling device 1c, 1c to 5c, 5c, and the work roll bender pressure of the work rolls 1a, 1a to 5a, 5a is adjusted by a work roll bender (not shown). ing. Work roll 1
a, 1a to 5a, 5a are driven by a roll drive motor.

Next, the basic principle of the method of the present invention will be described. In the cold continuous rolling mill as described above, when determining the basic rolling schedule representing the entrance side thickness and the exit side thickness of each stand, the rolling reduction ratio, the motor power ratio of each stand, and the The basic rolling schedule is determined so that the stand can balance each item of the ratio of the energy input to the material to be rolled between the stands, but the input side plate thickness h (i-1) of the specific stand i, When the exit side plate thickness h (i) is changed, the loads, motor powers, and driving torques of stands other than the specific stand i also change.

For this reason, the thickness h (i
-1) and the exit side thickness h (i) are changed from the thickness determined in the basic rolling schedule, the load, the motor power and the driving torque of not only the stand i but also the other stands are changed. It changes at the same time, and the balance between the stands determined by the basic rolling schedule cannot be maintained.

In the continuous cold rolling mill, there are seven types of limit values relating to the following operating conditions. If any one of the limit values is exceeded in each stand, there is a possibility that abnormalities may occur in the rolling state. is there.

The first limit value is an absolute load value which is a limit value at which the mill is broken when a load greater than that is applied, and the second limit value is a second limit value.
The limit value is the maximum value of the line load, which is the limit value at which heat scratch occurs when a line load more than is applied, and the third limit value is the limit value at which non-contact between rolls occurs when a line load less than that is applied. A certain minimum linear load, a fourth limit is a maximum torque value that is a limit value at which a drive system is destroyed when a torque greater than that is applied, and a fifth limit value is a value at which a roll is applied when a greater stress is applied thereto. Deformation maximum between rolls Hertz stress, 6th
Is the limit value at which the slippage occurs when the neutral point position is less than the neutral point position, and the seventh limit value is the limit value at which the rolling function becomes impossible due to insufficient rolling capability when the neutral point position becomes less than the neutral value. Rolling power limit value.

In the case where the limit value is exceeded, if the stand thickness exceeds the limit value and the entrance side thickness and the exit side thickness of the stand are appropriately changed, the limit value is not exceeded. Is possible, and abnormalities in the rolling state can be avoided. However, if the thickness of the entrance side and the thickness of the exit side of the stand are changed from the thickness determined in the basic rolling schedule, the inconvenience as described above occurs.
When changing the entrance side thickness and the exit side thickness of the stand so as not to exceed the limit value, the entrance side thickness and the thickness of all the stands so as to maintain the balance between the stands determined by the basic rolling schedule. The outlet thickness must be changed at the same time.

Hereinafter, when changing the thickness of the entrance side and the thickness of the exit side of the stand so as not to exceed the limit value,
A description will be given of a method of simultaneously changing the entrance side plate thickness and the exit side plate thickness of all the stands so that the balance between the stands determined by the basic rolling schedule can be maintained.

Although various methods for determining the basic rolling schedule are conceivable, here, as an example, a method for determining the basic rolling schedule so as to keep the motor power ratio of the roll drive motor between the stands constant will be described. .

With respect to the motor power W (1) to W (5) of each stand from the first stand to the fifth stand 5, the ratio of the motor power between the stands is represented by Wa (1): Wa (2): Wa. (3): Wa (4): Wa
When setting to (5), the following equation (1) is satisfied.

[0022]

(Equation 1)

The thickness of the entrance side and the thickness of the exit side of each stand are as described above.
If the above equation (1) is modified in consideration of the influence coefficient on the equation (1), both equations (2) and (3) must be satisfied in order to keep the motor power ratio of each stand constant. There is.

[0024]

(Equation 2)

[0025]

(Equation 3)

In the equation (2), the influence coefficient λ is a determinant expressed by the following equation (4), μ is a determinant expressed by the following equation (5), and the thickness correction amount of each stand. dh is the following (6)
It is a determinant expressed like an equation.

[0027]

(Equation 4)

[0028]

(Equation 5)

[0029]

(Equation 6)

When the condition of the expression (3) is not satisfied in the expression (2), the plate thickness correction amount of each stand is calculated using the following expression (7) obtained by modifying the expression (2). dh can be obtained.

[0031]

(Equation 7)

The above is an example of a commonly used method for determining a basic rolling schedule.

Further, when a limit value such as an absolute load and a maximum torque value of a certain stand is represented by Y _m (i), and its predicted value calculated by the basic rolling schedule is represented by y (i).
For stands where the predicted value y (i) exceeds the limit value Y _m (i),
In order to avoid an abnormal rolling state, the predicted value y (i) must be suppressed below the limit value Y _m (i). For this purpose, the predicted value y (i) is calculated as shown in the following equation (8). And the limit value Y _m (i)
In this case, the constraint value function L (i) expressed by the ratio is set to 1 or less.

[0034]

(Equation 8)

In the stand i where the predicted value y (i) exceeds the limit value Y _m (i), the fluctuation of the entrance side thickness h (i-1) and the exit side thickness h (i) is caused by the constraint value function L. Using the influence coefficient representing the effect on (i), the above equation (8) can be modified as shown in the following equation (9).

[0036]

(Equation 9)

According to the basic principle as described above, when one or more stands exceed one or more kinds of limit values, if the stand satisfies the above expression (9), the limit values can be changed. It is possible to keep the ratio of the motor power of each stand constant if the other stands satisfy the expressions (2) and (3). .

Next, a method for determining a rolling schedule based on the above basic principle will be specifically described. When the rolling schedule determination method based on the above basic principle is performed, the following processing is executed by a computer. FIG. 2 is a flowchart illustrating a processing procedure of the rolling schedule determination method.

When the material 1 to be rolled has reached a predetermined position on the transport path, first, the calculation for obtaining the basic rolling schedule as described above is performed, and the absolute value of each stand is calculated from the data such as the thickness and tension of each stand. A load value, a line load value, a torque value, a Hertz stress between rolls, a neutral point position, and a rolling power value are predicted (step S1).

Next, it is determined whether or not each of the predicted values other than the rolling power value obtained in step S1 exceeds each of the limit values (step S2). If it is determined in step S2 that there is a predicted value exceeding the limit value, a limit value-considered schedule calculation as described later is executed (step S3) so as not to exceed the limit value. In step S3, in step S4 described below, the rolling speed is reduced in advance so that the rolling power value does not exceed the limit value.

On the other hand, if it is determined in step S2 that there is no predicted value exceeding the limit value, it is determined whether the predicted value of the rolling power value obtained in step S1 exceeds the limit value ( Step S4).

If it is determined in step S4 that the predicted value of the rolling power value exceeds the limit value, the rolling speed is calculated using the characteristic that the rolling power is proportional to the product of the torque value and the motor speed. Is reduced (step S5), so that the rolling power value does not exceed the limit value, the process returns to step S1, and the above-described processing is repeated. On the other hand, if it is determined in step S4 that the predicted value of the rolling power value does not exceed the limit value, the rolling schedule determination process ends.

Next, a specific example of the limit value-considered schedule calculation in step S3 will be described. Here, as an example, a case where the basic rolling schedule is calculated so as to keep the motor power ratio constant at each stand will be described.

First, in step S1, the basic rolling schedule is calculated so as to keep the motor power ratio constant at each stand as described above, whereby the motor power at each stand is shown in FIG. 3 (a). It is assumed that the relationship shown in FIG. 3B is obtained, and the predicted value of the rolling load at each stand is the relationship shown in FIG.

FIGS. 3A and 3B are graphs showing the motor power at each stand obtained in the basic rolling schedule calculation and the predicted value of the rolling load at each stand.
3A and 3B, the horizontal axis represents the stand number, the vertical axis of FIG. 3A represents the motor power, and the vertical axis of FIG. 3B represents the rolling load. is there. The symbol x in FIG. 3 (a) indicates the target value of the motor power balance, and the symbol x in FIG. 3 (b) indicates the limit value (absolute load value) of the rolling load.

In this case, the motor power shown in FIG. 3A is balanced at each stand, but the predicted value of the rolling load shown in FIG. Value, and in step S2,
It is determined that the limit value is exceeded, and in step S3, the following limit value-considered schedule calculation is executed, and the first stand 1 and the third stand 3 do not exceed the limit value (absolute load value). So that the balance of the motor power can be maintained in the other stands.

For the first stand 1 and the third stand 3 exceeding the limit value (absolute load value), the respective rolling loads p
(1) and p (3) are limited to absolute load values pm (1) and pm (3) as shown in the following equations (10) and (11).

[0048]

(Equation 10)

[0049]

[Equation 11]

The second stand 4, the fourth stand 4 and the fifth stand 5 satisfy the relationship shown in the following equation (12) so that each stand (second stand 2, The ratio of the motor powers W (2), W (4), W (5) of the fourth stand 4 and the fifth stand 5) is the target value Wa (1): Wa () of the motor power ratio defined in the basic rolling schedule. 2): Wa (3): Wa (4): Wa (5).

[0051]

(Equation 12)

In order to prevent the absolute load value from exceeding the absolute load value in the first stand 1 and the third stand 3 and to maintain the balance of the motor power in the other stands, the above-mentioned (10), (11) What is necessary is to find a rolling schedule that simultaneously satisfies the equation (12). Using the influence coefficient as described in the description of the basic principle, (10),
By modifying equations (11) and (12), the following equations (13) and (14) are obtained.

[0053]

(Equation 13)

[0054]

[Equation 14]

In the above equation (13), the influence coefficient λ is the determinant expressed by the following equation (15), μ is the determinant expressed by the following equation (16), and the thickness correction amount dh is It is a determinant expressed as in equation (17).

[0056]

(Equation 15)

[0057]

(Equation 16)

[0058]

[Equation 17]

In the equations (13) and (14) obtained in this way, the sheet thickness is calculated by the following equation (18) obtained by modifying the equation (13) so as to satisfy the equation (14). The correction amount dh is obtained, and the determined value of the plate thickness of each stand is obtained based on the obtained thickness correction amount dh by using the plate thickness correction formula of each stand shown in the following equation (19). As a result, a rolling schedule is obtained in which the first stand 1 and the third stand 3 do not exceed the limit value and the balance of the motor power can be maintained in the other stands.

[0060]

(Equation 18)

[0061]

[Equation 19]

When the above-described schedule calculation considering the limit value is performed, the motor power at each stand has a relationship as shown in FIG. 4A for the obtained rolling schedule, and the rolling load at each stand is also determined. The predicted values have a relationship as shown in FIG.

FIGS. 4 (a) and 4 (b) are graphs showing the motor power at each stand and the predicted value of the rolling load at each stand obtained in the limit value consideration schedule calculation. 4A and 4B, the horizontal axis represents the stand number, the vertical axis in FIG. 4A represents the motor power, and the vertical axis in FIG. 4B represents the rolling load. Note that, in FIG.
The mark indicates the target value of the motor power, and the mark x in FIG. 4B indicates the limit value (absolute load value) of the rolling load. In this case, the motor power in FIG. 4A is balanced at each stand, and the predicted value of the rolling load in FIG. 4B does not exceed the limit value at each stand.

In this embodiment, the schedule calculation considering the limit value when the rolling load exceeds the limit value (absolute load value) has been described. However, the present invention is not limited to this, and other limit values are similarly calculated. It is possible to perform a schedule calculation considering the limit value. Further, when it is desired to keep the rolling load of the final stand (the fifth stand 5) constant, it can be easily realized by regarding the final stand as the (final stand-1) stand.

[0065]

As described above in detail, according to the method of the present invention, a plurality of rolling conditions, ie, a reduction ratio, a motor power ratio,
And the input energy ratio to the material to be rolled, etc.
Basic rolling schedule to balance between stands
For the stand of the operating condition that is determined to exceed the limit value of each of the plurality of operating conditions when this is executed , the basics are set so that each operating condition does not exceed the respective limit value. The portion of the rolling schedule relating to the stand concerned is corrected, and the stand of the operating condition determined not to exceed the limit value is determined first on the basis of the influence coefficient of the entrance side thickness and the exit side thickness of the stand with respect to the rolling condition. Since the portion of the basic rolling schedule related to the stand is modified so that any one of the rolling conditions achieves a predetermined balance, any one of the stands is limited to a limit value related to the operating condition of the rolling. If it exceeds the value, a value for the limit value of the stand while being corrected to a value that does not lead to the limit values, in the other stands The balance of the determined rolling conditions in
The basic rolling schedule has been modified without breaking
The present invention has excellent effects, for example, it is possible to maintain a balance between stands that are not restricted by the limit value .

[Brief description of the drawings]

FIG. 1 is a schematic view showing the configuration of an example of a continuous cold rolling mill applied to the practice of the method of the present invention.

FIG. 2 is a flowchart showing a processing procedure of a rolling schedule determination method.

FIG. 3 is a graph showing a motor power at each stand obtained in a basic rolling schedule calculation and a predicted value of a rolling load at each stand.

FIG. 4 is a graph showing a motor power at each stand obtained in a limit value consideration schedule calculation and a predicted value of a rolling load at each stand.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st stand 2 2nd stand 3 3rd stand 4 4th stand 5 5th stand 6 Rolled material

Claims (1)

(57) [Claims] 1. A basic rolling schedule is determined so that any one of a plurality of rolling conditions between respective stands of a continuous rolling mill for continuously rolling a material to be rolled has a predetermined balance. Based on the execution of the basic rolling schedule, it is determined whether or not the operating condition of each stand exceeds each limit value of a plurality of operating conditions that should be satisfied for each stand to perform a normal operation . For the stand of the operating condition determined to exceed the limit value, the basic rolling is performed so that the operating condition does not exceed the limit value based on the influence coefficient of the stand thickness of the stand and the outlet thickness of the stand with respect to the operating condition. Modify the part of the schedule related to the stand, for the stand of the operating condition determined not to exceed the limit value, the stand of the rolling condition Thickness at entrance side, based on the influence coefficient of the output side thickness, the previously determined
Correct the portion of the basic rolling schedule related to the stand so that any one of the plurality of rolling conditions is in a predetermined balance, and the operating conditions of each stand do not exceed each limit value.
Rolling schedule determination method of continuous rolling mill modified basic rolling schedule and determining the rolling schedule.