JPS631130B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling plate thickness in a continuous rolling mill.

In a continuous rolling mill consisting of a plurality of rolling stands, the rolling position, roll speed, etc. of each rolling stand are generally controlled in order to control the plate thickness to a desired value. At this time, the rolling load is optimally distributed to each rolling stand so as to satisfy the torque limitations of the electric motor and the load limitations on the mechanical system, and to obtain a plate with a good shape after rolling.

On the other hand, in the plate thickness control, the stand outlet side plate thickness calculated by, for example, the following gauge meter formula (1) is set as the reference plate thickness at the time of biting of the material to be rolled or at a timing given by the operator.

HO=SO+P/M...(1) Here, HO is the plate thickness on the exit side of the stand, SO is the rolling position, P is the rolling load, and M is the mill rigidity coefficient.

During rolling, the thickness of the plate at the exit side of the stand is calculated using the above formula (1), and the rolling position of the rolling stand is controlled based on the deviation of the plate thickness at the exit side of the stand from the reference plate thickness (this is calculated using a gauge meter). (referred to as plate thickness control).

Furthermore, in order to further improve the degree of processing of the final plate thickness, a plate thickness deviation detector using, for example, Normally, the plate thickness standard is corrected.

Under the plate thickness control as described above, the rolling of each rolling stand is driven independently. For this reason, there is a possibility that the optimum load distribution set before biting may be disrupted. For example, in a continuous hot rolling mill, there is a temperature gradient in the longitudinal direction of the material to be rolled, and as rolling progresses, the upstream rolling stand takes steps to suppress the increase in plate thickness variation caused by this temperature gradient. Therefore, the load on the upstream stand increases. Further, the shorter the time for material transfer to the plate thickness detector is, the more downstream the rolling stand, the larger the amount of correction of the reference plate thickness value due to the plate thickness deviation, and therefore the larger the change in load. If the load is unbalanced in this way, it will adversely affect the operation or the quality of the plate material (mainly regarding the shape).

An object of the present invention is to provide a plate thickness control method that solves the above-mentioned problems and can keep the rolling load distribution of each rolling stand in an appropriate state without impairing the original function of plate thickness control. It is in.

The present invention provides a strip thickness control method in a continuous rolling mill that detects the exit side strip thickness of each of a plurality of rolling stands of a connected rolling stand and controls the rolling position of each rolling stand based on the difference from the reference strip thickness. , determine an initial set rolling position and a limit range including the set position for each rolling stand, detect the actual rolling position of each rolling stand, and when the detected rolling position falls outside the limited range; A plate in a continuous rolling stand, characterized in that the rolling position is moved within a predetermined limit range by correcting the reference plate thickness for automatic plate thickness control of the rolling stand or a rolling stand upstream of the rolling stand. A thickness control method is provided.

In one embodiment of the present invention, the reference plate thickness is corrected as follows.

(1) From the viewpoint of optimum load, a range of a predetermined width is set above and below a predetermined initial rolling position for each rolling stand. Then, in one of the rolling stands, the actual rolling position during rolling has deviated from the predetermined range, that is, the rolling position has exceeded the fluctuation, and at least one of the rolling stands downstream of the rolling stand has On the condition that there is no excess variation in one of the rolling stands, that is, all the rolling stands from the most downstream glue rolling stand to the rolling stand are not subject to excess variation in the same direction, Provides a load distribution optimization correction signal for correcting plate thickness.

Of the rolling stands that control plate thickness,
When excess fluctuation occurs in the most downstream rolling stand, in order to maintain the final thickness at the desired value, no correction signal is given to the thickness control section of the most downstream rolling stand, and the A correction signal is given to the plate thickness control section of the rolling stand in a direction to eliminate the excess fluctuation of the most downstream rolling stand.

If the upstream rolling stand also exhibits an excess variation in the same direction as the most downstream rolling stand (either too large or both too small), the plate thickness of the rolling stand further upstream than the upstream rolling stand will be changed. A correction signal is given to the control section.

(2) When correcting the standard plate thickness, the automatic plate thickness control at each rolling stand is performed by adjusting the standard plate thickness at a predetermined correction rate (per unit time) while the rolling position is outside the predetermined range. This is done by increasing or decreasing the correction amount). By correcting the standard plate thickness, when the rolling position falls within a predetermined range, or after a certain period of time has passed since entering the range, the correction of the standard plate thickness is stopped and the amount of correction at that point is maintained. do. At this time, the standard plate thickness correction speed may be any speed that does not cause excessive disturbance to the automatic plate thickness control at that time.

In order to simplify the explanation below, the number of rolling stands is 3.
An example in which there is a stand will be described with reference to the drawings.

FIG. 1 shows a control device and a rolling mill body used to implement the control method according to the present invention. The rolling mill main body consists of rolling stands R1 to R3.
and an electric motor M1 that drives the rolling stand of each rolling stand.
~M3. Each rolling stand is provided with rolling position detectors S1 to S3 that detect rolling positions and rolling load detectors LC1 to LC3 that detect rolling loads. Further, a plate thickness detector X is provided on the exit side of the final rolling stand R3.

For each rolling stand, the plate thickness control circuit C1
~C3 are provided. The plate thickness control circuit C1 provided for the rolling stand R1 receives the detected rolling position value from the rolling position detector S1, receives the rolling load detected value from the rolling load detector LC1, and converts the gauge meter type (1 ) to calculate the actual value of the plate thickness at the exit side of rolling stand R1, calculate the difference between this calculated value and the reference plate thickness, that is, the plate thickness variation, and calculate the actual final plate thickness obtained by the plate thickness deviation detector X. A correction is made based on the deviation, and the reduction drive motor M1 is driven based on the corrected value.

The plate thickness control circuits C2 and C3 are also connected to the rolling stand R.
2, R3 is controlled in the same way as above.

The reference plate thickness given to the plate thickness control circuits C1 to C3 is corrected by the load distribution optimization control circuit. This load distribution appropriate control circuit includes a roll-down position monitoring control circuit 1 that monitors the difference between the initial set roll-down position of each rolling stand and the detected value of the actual roll-down position;
Reference plate thickness correction control circuits 21 and 2 are provided for rolling stands other than the final stand R3 and correct the reference plate thickness given to the plate thickness control circuits C1 and C2.
2.

The rolling position monitoring control circuit 1 is given in advance initial setting rolling positions So1, So2, and So3 (for example, inputted by a biting signal of the material to be rolled).
In addition, limit widths B1, B2, and B3 (for example, determined as several percent of the initial set roll-down position) are given, and based on these, the roll-down position detectors S1, S2,
It is determined whether the actual rolling position inputted in S3 is within the range of control widths B1, B2, and B3 centered on the initial setting rolling positions So1, So2, and So3.

Switches 11a, 12a, 13a, 13b, 1
4a and 14b are controlled by the output of the rolling position monitoring control circuit 1. Switches 11a and 12a control the start and end of correction, and switches 13a and 13
b, 14a, 14b determine the direction of modification.

The correction speed setters 15 and 16 provide signals of a predetermined magnitude, thereby determining the correction speed. The inverters 17 and 18 invert the sign or polarity of the signal. The integrators 19 and 20 integrate the corrected speed signals provided from the corrected speed setters 15 and 16 via or without the inverters 17 and 18 to form a reference plate thickness correction signal.

Among the above, switches 11a, 13a, 13
b. The correction speed setter 15, the inverter 17, and the integrator 19 constitute a reference plate thickness correction control circuit 21 for the plate thickness control circuit C1, and the switch 1
2a, 14a, 14b, the correction speed setter 16, the inverter 18, and the integrator 20 constitute a reference plate thickness correction control circuit 22 for the plate thickness control circuit C2.

FIGS. 2A to 2C show control operations performed in different situations in the control method of this embodiment. In these figures, So
1, So2, and So3 are the initial set lowering positions of each stand, which are predetermined from the viewpoint of optimal load distribution. UL1, UL2, UL3 are the upper limit values of the predetermined limited width B1, B2, B3 range centered on the initial set lowering position So1, So2, So3 of each stand, LL
1, LL2, and LL3 are the lower limit values of the above predetermined range. If the actual rolling positions are within the respective predetermined ranges, the reference plate thickness for plate thickness control will not be corrected. If the actual rolling position deviates from the predetermined range, the reference plate thickness is corrected according to each situation. FIGS. 2A to 2C show three examples of correction of the reference plate thickness.

As shown in Fig. 2a, the actual rolling position of the second rolling stand R2 from the upstream side is at the upper limit UL2.
, and is at the position shown by 2A, and when the rolling position 3A of the most downstream rolling stand R3 is within a predetermined range, this is determined by the rolling position monitoring control unit 1, and the switches 12a and 14a are activated. Controlled to close. As a result, the correction speed setter 1
An inverted version of the modified speed signal from 6 is integrated by an integrator 20. The integral value is given to the plate thickness control circuit C2 as a correction amount for the reference plate thickness. This causes the reference plate thickness to decrease at a constant correction speed. As a result, the actual rolling position of the rolling stand R2 moves in the direction of the initial setting value So2. Following this,
The plate thickness on the outlet side of rolling stand R2 is reduced, and the rolling position of rolling stand R3 is set to the upper limit value by plate thickness control.
Move towards UL3.

As shown in Fig. 2b, the actual rolling position 3A of the most downstream rolling stand R3 exceeds the upper limit value UL3, and the actual rolling position 2A of the rolling stand R2 located one upstream side exceeds the upper limit value. When it is smaller than UL2, this means that the reduction position monitoring control device 1
, and the switches 12a and 14b are controlled to close. As a result, the corrected speed signal from the corrected speed setter 16 is integrated by the integrator 20. The integral value is given to the plate thickness control circuit C2 as a correction amount for the reference plate thickness. This increases the reference plate thickness at a constant correction speed. Accordingly, the outlet side plate thickness of rolling stand R2 increases, and the rolling position of rolling stand R3 moves toward the initial setting value So3 as a result of plate thickness control.

As shown in FIG. 2C, the actual rolling positions 3A, 2A are shown in both the most downstream rolling stand R3 and the rolling stand R2 one place upstream.
is larger than the upper limit values UL3, UL2, and when the rolling position 1A of the rolling stand R1 on the upstream side is smaller than the upper limit value UL1, this is determined by the rolling position monitoring control circuit 1, and the switch 11 is
a, 13b are controlled to close. As a result, the corrected speed signal from the corrected speed setter 15 is integrated by the integrator 19. The integral value is given to the plate thickness control circuit C1 as a correction amount for the reference plate thickness. As a result, the reference plate thickness increases at a constant correction speed. Accordingly, the thickness of the outlet side of the rolling stand R1 increases, and the rolling positions of the rolling stands R2 and R3 move toward the initial setting values So2 and So3 as a result of the thickness control.

The three columns a, b, and c in FIG. 2 are typical examples of load imbalance situations that may actually occur, and various other situations are expected. However, in any situation, as mentioned above, if the excess variation occurs in only one rolling stand, as a general rule, the standard plate thickness is corrected for the rolling stand where the excess variation occurs. As an exception, when the final stand has an excess variation, the reference plate thickness is corrected at the rolling stand one upstream of the final stand in order to maintain the final plate thickness. In addition, if excess variation occurs in multiple rolling stands, as a general rule, the standard plate thickness is corrected for each rolling stand where the excess variation occurs. When the stands are exhibiting excessive fluctuations in the same direction, the reference plate thickness is corrected at the rolling stand one upstream of the rolling stand group experiencing the excessive fluctuations in order to maintain the final plate thickness.

Such a corrective action, in the case of the above principle, directly eliminates the excess fluctuation of the rolling stand where the correction has been made, and the effect of this correction is particularly on the downstream side of the rolling stand where the correction has been made. This appears in the plate thickness control of each rolling stand, but if this causes excess variation in the downstream rolling stand, the excess variation can be resolved individually by correcting the reference plate thickness as described above. In addition, in the case of the above exception, the excess variation of the downstream stand will be indirectly eliminated due to the effect of the standard plate thickness correction at the upstream stand related to the correction on the downstream side, and the If the upstream stand involved in the modification becomes subject to fluctuation excess before the excess is resolved, the reference plate thickness will be corrected to one more upstream rolling stand, and due to the correction at the upstream side. When it is possible to eliminate the excess variation of only some of the downstream stands, the excess variation of the downstream stands that cannot be eliminated is individually resolved by the correction in accordance with the above principle. In this way, in any load unbalance situation, the adjustment is made so that ultimately none of the rolling stands is over-flushed.

FIG. 3 shows changes over time in the rolling position of each rolling stand, reference plate thickness, and actual plate thickness in the reference plate thickness correction, taking the case of FIG. 2b as an example.

In the same figure, SA2 is the rolling position of rolling stand R ₂ , SA3 is the rolling position of rolling stand R ₃ , HC
2 is the standard plate thickness of rolling stand R ₂ , H2 is the actual plate thickness of rolling stand R ₂ , and H3 is the rolling stand.
Shows the actual exit side plate thickness of R ₃ .

As shown in SA2 and SA3, at time t ₁ , the rolling position of rolling stand R ₂ is within the predetermined limit range, and the rolling position of rolling stand R ₃ , which is the final stand, exceeds the upper limit of the predetermined limit range. If so, increase the standard plate thickness of rolling stand _R2 at a constant slope as shown in HC2.

As a result, the automatic plate thickness control of rolling stand _R2 is
Following the standard plate thickness that was increased at a constant slope,
The rolled position increases as shown in SA2. Then, the actual output side plate thickness shown in H2 corresponding to this reference plate thickness is produced. This increased actual plate thickness on the exit side is
After the transfer time between stands has passed, the rolling stand
Reach R ₃ . The automatic plate thickness control of rolling stand R ₃ takes this increased actual exit side plate thickness as the inlet side plate thickness, reduces the rolling position as shown in SA3 to eliminate the variation, and keeps it within the specified limit range of rolling stand R ₃ . reach.

Next, at time t ₂ when the rolling position of this rolling stand R ₃ reaches within a predetermined control range, rolling stand R ₂ stops increasing the reference plate thickness and maintains the value as shown in HC2. Along with this, the rolling position of rolling stand R ₂ is also maintained, and as a result, the rolling position of rolling stand R ₃ is also maintained after the transfer time when the actual plate thickness held by rolling stand R ₂ reaches rolling stand R ₃ ( It is held from time t ₃ ).

As described above, while maintaining the exit side plate thickness (product plate thickness) of rolling stand R ₃ at the desired plate thickness, the respective rolling positions of rolling stands R ₂ and R ₃ are moved within their respective predetermined limit ranges. Can be done.

The rolling position monitoring control circuit 1 switches switches 11a and 12a when the actual rolling position falls within the limit width or when a predetermined time has elapsed since the actual rolling position falls within the limit width range.
etc., and finish modifying the standard plate thickness. Upon completion of this correction, the amount of correction of the reference plate thickness is automatically determined.

The rolling position monitoring control circuit 1 and the reference plate thickness correction control circuits 21 and 22 operate while the rolled material P exists in the rolling mill and while the plate thickness control circuits C1, C2, and C3 are executing the plate thickness control. , the standard plate thickness is always dynamically corrected and the unbalance of the rolling load is corrected accordingly.

The limit widths B1, B2, and B3 centered on the initial set rolling positions of the rolling stands R1, R2, and R3 do not need to be fixed values, but can be changed depending on the type of material to be rolled, etc., so that they can be further improved. Highly accurate load distribution optimization can be achieved.

In the above embodiment, the reference plate thickness control circuit 21,
Although integrators 19 and 20 are provided at 22, first-order delay elements may be used instead. Even if the first-order delay element is used in this way, it is possible to prevent a large disturbance from occurring in plate pressure control.

As described above, according to the present invention, the unbalance of the rolling load can be corrected with a simple circuit configuration, and the quality of the rolled material can be made highly accurate and stable.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of an apparatus used for implementing the sheet thickness control method according to the present invention, FIGS. FIG. 3 is a diagram corresponding to FIG. 2b showing changes over time in the rolling position, reference sheet thickness, and actual sheet thickness in the sheet thickness control method of the present invention. R1, R2, R3...Rolling stand, M1, M
2, M3...Downward drive motor, S1, S2, S3...
Rolling position detector, LC1, LC2, LC3...rolling load detector, X...plate thickness deviation detector, P...rolled material,
C1, C2, C3... Plate thickness control circuit, 1... Rolling down position monitoring control circuit, 11a, 12a, 13a, 13
b, 14a, 14b...Switch, 15, 16...Correction speed setter, 17, 18...Inverter, 19, 20
...Integrator, 21, 22...Reference plate thickness correction control circuit.

Claims (1)

[Claims] 1 In a strip thickness control method in a continuous rolling mill that detects the exit side strip thickness of multiple rolling stands of a continuous rolling stand and controls the rolling position of each rolling stand based on the difference from the standard strip thickness, the initial A set rolling position and a limit range including the set position are determined, and the actual rolling position of each rolling stand is detected, and when the detected rolling position is outside the limited range, the rolling stand or the rolling stand is A method for controlling plate thickness in a continuous rolling stand, characterized by correcting the standard plate thickness of a rolling stand upstream of the stand.