JPH05177223A - Method for adjusting running schedule of tandem rolling mill - Google Patents

Abstract

PURPOSE:To provide a running schedule adjusting method suited for a specified condition for which the plate thickness on the outlet side is fixed and to express the maximum capacity of a rolling mill. CONSTITUTION:All or a part of a speed ratio at each stand, a draft position at each stand, a plate thickness at each stand, a tension at each stand are adjusted in a condition that the set value of the thickness on the outlet side of a final stand is fixed. The adjustment point is tracked by the flow rate of a metal plate from an upstream side, the adjustment time is set longer than a fixed value determined by the responsiveness, the set accuracy of each instrument and the set value of each instrument is adjusted continuously by fine amounts between the starting point of adjustment and the terminal point of adjustment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for adjusting a running schedule of a constant outgoing plate thickness in a tandem rolling mill in which a plurality of stands are continuously arranged.

[0002]

2. Description of the Related Art In recent years, continuous rolling mills and changing running strip thickness have been implemented for the purpose of improving the quality and production efficiency of cold tandem rolling mills.

Various methods such as Japanese Patent Publication No. 48-17145 and Japanese Patent Application Laid-Open No. 48-84756 are known as methods for changing the running schedule. In each case, the product sheet thickness is changed to that of the following material. It is basically based on changing the gauge as short as possible and shortening the off-gauge, and there is nothing related to the adjustment of the running schedule under the condition where the outlet plate thickness is constant.

[0004]

In the tandem rolling mill, the rolling schedule including the speed ratio of each stand, the rolling position, the strip thickness, the tension, etc. has recently been calculated by a computer using a setting calculation model formula, Automatic setting has become common, and it is effective in reducing off-gauge and improving productivity. However, the initial set value is rarely exactly the set target value due to variations in the mechanical properties of each material and factors that have not been completely predicted by the set calculation model formula. It often happens that the schedule needs to be adjusted.

Conventionally, the adjustment of the rolling schedule after the start of rolling has been carried out by manual intervention by the operator. However, manual intervention cannot strictly control the operation timing and the operation amount of each operation end, so that the variation of the plate thickness can be suppressed. As a result, there are problems that the thickness accuracy is partially deteriorated and that changing to an appropriate value is not always easy. Therefore, when rolling a material with strict requirements regarding plate thickness accuracy, even if the initial setting schedule is dissatisfied, manual intervention cannot be performed to prevent the deterioration of plate thickness accuracy, so the rolling efficiency is sacrificed, and other factors. The quality characteristics of the product have been sacrificed.

As a second method, it is possible to change the schedule by the following method by applying a well-known running schedule change method using a computer, but this causes a new variation in plate thickness. There was a problem. The second method will be described below. When the rolling of the material to be rolled is started, the target value and the actual value of the rolling schedule can be compared at that time. Within the same coil, changes in material property values and changes in rolling characteristics are relatively small, and schedule calculation is performed again to fill the difference between the actual value and target value of the rolling schedule, and the schedule is accurately calculated. The correction amount can be calculated. The amount of schedule correction calculated in this way
It is possible to change the running schedule according to the known rolling reduction and speed change pattern illustrated in FIG. 4 and change to the new schedule in a short time. However, because the setting values of multiple devices with different responsiveness are changed instantaneously,
It is inevitable that a slight deviation in the start timing of each device will occur as a spike-like thickness variation in a short time.

The present invention solves the above problems and provides a running schedule adjustment method suitable for a special condition that the schedule is changed in the same coil, that is, the outgoing side plate thickness is constant,
It maximizes the capacity of the rolling mill.

[0008]

The gist of the present invention is as follows.

In the tandem rolling mill, the speed ratio of each stand under the condition that the final stand outlet side thickness set value is constant,
A method for adjusting a running schedule of a tandem rolling mill, which comprises adjusting all or part of a rolling position of each stand, a plate thickness of each stand, and a tension of each stand.

In the above running schedule adjustment method, the speed ratio of each stand is calculated by tracking the adjustment point from the upstream side of the rolling mill by the flow rate of the plate.
A method for adjusting a running schedule of a tandem rolling mill, comprising controlling a rolling position of each stand, a plate thickness of each stand, and a timing of adjusting all or a part of tension of each stand.

In the above running schedule adjustment method, the adjustment time at the adjustment point is set to a certain value or more determined by the responsiveness of the device and the setting accuracy, and the speed ratio of each stand is adjusted between the adjustment start point and the adjustment end point. A method for adjusting a running schedule of a tandem rolling mill, characterized in that the rolling position of each stand, the plate thickness of each stand, and all or part of the tension of each stand are continuously adjusted in minute amounts.

[0012]

As described above, when the rolling of the material to be rolled is started, the target value and the actual value of the rolling schedule can be compared at that time. Within the same coil, changes in material property values and changes in rolling characteristics are relatively small, and schedule calculation is performed again to fill the difference between the actual value and target value of the rolling schedule, and the schedule is accurately calculated. The correction amount can be calculated. The present invention is characterized by intentionally taking time to adjust the schedule in consideration of the setting accuracy and response characteristics of each device when the schedule is changed based on the thus obtained schedule correction amount. ..

FIG. 1 shows a rolling control system and a speed control system of a 5-stand tandem rolling mill. 1 is a rolled material, 2 is a rolling mill,
3 is a rolling down device, 4 is a rolling down control device, 5 is an electric motor, 6 is a speed control device, 7 is a plate speed detecting device, 8 is an output of the plate speed detecting device 7 and a rolling speed or a plate speed meter installed in a stand. A tracking device that tracks the schedule adjustment start point from the output and controls the schedule adjustment timing of each stand and the progress of the adjustment, 9 is a reduction command device that continuously adjusts the reduction position by a reduction adjustment instruction signal, and 10 is a speed change A speed change command device that continuously adjusts the speed by an instruction signal, and 11 is a running schedule change calculator that calculates the schedule correction amount and calculates the pressure reduction and speed correction rate of each stand.

In the running schedule change computer 11, the schedule correction amount is first calculated automatically or manually by a request after the start of rolling by some schedule calculation method not specified here. The set value is required. Here, the relationship between the rolling-down position S _{i of} the i-stand and the speed ratio V _i of the i-stand is expressed by equations 1 and 2
And

[0015]

[Equation 1] S _{i NEW} = S _{i OLD} + ΔS _i (1)

[0016]

[Equation 2] V _{i NEW} = V _{i OLD} + ΔV _i (2)

Then, in the same manner as in the case where the schedule is changed in a short time by a known method, the rolling position S of the i stand when the schedule change point passes the j stand.
_i and the change amount of the speed ratio V _i of the i stand are obtained. These are set to Equations 3 and 4.

[0018]

[Expression 3] ΔS _ij (3)

[0019]

[Formula 4] ΔV _ij (4)

Next, using the schedule correction execution time τ (which may be converted into the plate feed amount) obtained in consideration of the responsiveness of each device, the pressure reduction position S _{i of} the i stand and the i stand can be adjusted. The change rate of the speed ratio V _i is obtained. These are set to equations 5 and 6.

[0021]

(5) δS _ij = ΔS _ij / τ (5)

[0022]

(6) δV _ij = ΔV _ij / τ (6)

The equations (5) and (6) can be applied as they are when the schedule change of each stand is executed independently without time wrap, but the schedule correction execution time τ is long and it passes through a plurality of stands. If there is a period in which the changed components of time are output simultaneously, the sum of the components is output in the target period.

Generally, the response delay of the motor and the pressure reducing device is about 0.1 to 0.5 seconds, which varies depending on the equipment. If the schedule correction execution time τ is set to about 1 to 10 seconds, the influence of a new disturbance due to the schedule change is reduced to about 1/10 to 1/20 as compared with the case where the schedule is changed by a known running schedule change method. It becomes possible to suppress.

[0025]

Next, the present invention will be described based on specific examples.

FIG. 2 shows the motor load factor and the rolling reduction factor of each stand. The solid line shows the state before the schedule change, and the load factor of the # 4 stand is higher than that of the # 2 and # 3 stands. In order to increase the rolling speed and improve the production efficiency, the motor load factors of the # 2, # 3, and # 4 stands are averaged as shown by the broken line, and the rolling speed is increased within a margin after reducing the load factor. Is desirable. For this,
It is necessary to compare the actual rolling schedule during rolling with the schedule that should be the target, and calculate the schedule modification amount.However, the required amount for changing the schedule within the same coil is relatively small, and the computer requires a relatively short time. You can ask.

FIG. 3 shows a correction pattern of the rolling position and the speed ratio when the load distribution shown in FIG. 2 is corrected by the method of the present invention.

Regarding the rolling-down position, S ₁ and S ₅ do not change before and after the correction, but S ₂ , S ₃ and S ₄ change like a ramp while partially wrapping each. Regarding the speed ratio, V ₅ and V ₄ remain unchanged before and after modification, but V ₃ is # 4.
It changes like a ramp between the start and end points of the stand modification. Also, V ₂ is the correction starting point of the # 3 stand and # 4
Between the end points of the stands, V ₁ has a slightly more complicated change between the start point of the # 2 stand and the end point of the # 4 stand. It is because it is output as.

In this embodiment, the setting value of the plate thickness gauge installed between the stands and the change of the tension between the stands were not specifically mentioned, but a method similar to the correction of the rolling position and the speed ratio described here. Can be easily corrected with.

[0030]

As described above, according to the present invention, it is possible to adjust the running schedule under the condition that the outgoing side plate thickness is constant without causing the plate thickness variation even when the initial setting schedule is poor. Therefore, it is possible to improve the rolling speed by optimizing the motor load balance, reduce plate breakage accidents by optimizing the tension between stands, and improve the shape, plate thickness accuracy, surface quality, etc. by optimizing the schedule.
Further, the effect of reducing the load on the operator is great, and a great effect such as advancing the automation of the rolling mill is exhibited.

[Brief description of drawings]

FIG. 1 is a block diagram showing a rolling down control system and a speed control system of a 5-stand tandem rolling mill.

FIG. 2 is a diagram showing a motor load factor and a rolling reduction factor of each stand before and after rolling schedule adjustment.

FIG. 3 is a diagram showing a correction pattern of a rolling position and a speed ratio when the load distribution shown in FIG. 2 is corrected by the method of the present invention.

FIG. 4 is a diagram showing an example of a reduction pattern and a speed change pattern in a known running schedule change.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rolled material 2 Rolling mill 3 Rolling down device 4 Rolling down control device 5 Electric motor 6 Speed control device 7 Plate speed detection device 8 Tracking device 9 Rolling down change command device 10 Speed change command device 11 Running schedule change calculator

Claims (3)

[Claims] 1. In a tandem rolling mill, all or a part of the speed ratio of each stand, the rolling position of each stand, the plate thickness of each stand, and the tension of each stand are maintained under the condition that the final stand outlet side thickness set value is constant. A method for adjusting a running schedule of a tandem rolling mill, which comprises adjusting the running schedule. 2. The running schedule adjustment method according to claim 1, wherein the adjustment point is tracked from the upstream side of the rolling mill by the flow rate of the plate, whereby the speed ratio of each stand, the rolling position of each stand, and each stand. Plate thickness, and the timing for adjusting all or part of the tension of each stand is controlled, and a running schedule adjustment method for a tandem rolling mill is provided. 3. The running schedule adjustment method according to claim 2, wherein the adjustment time at the adjustment point is set as the responsiveness of the device,
Set a certain value or more determined by the setting accuracy, and adjust the speed ratio of each stand, the rolling position of each stand, the plate thickness of each stand, and all or part of the tension of each stand between the adjustment start point and the adjustment end point. A method for adjusting a running schedule of a tandem rolling mill, characterized by continuously adjusting a minute amount.