JP2846430B2 - Automatic thickness control method - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to an automatic thickness control method in a rolling mill,
In particular, the present invention relates to an automatic thickness control (hereinafter, referred to as AGC) method for controlling a target thickness from a tip end of the plate.

Prior art AGC systems use a roll force method that stores the sheet thickness at lock-on and controls this as the target sheet thickness. The roll force monitor AGC, which corrects the thickness deviation by adding it to the stored target thickness, is usually used.In addition, the absolute target thickness is determined in advance, and the load cell measures when the plate bites into the roll. An absolute value AGC for calculating a sheet thickness h based on the following rolling load F based on the following equation and controlling the screw-down device so that a deviation from the absolute target sheet thickness becomes zero is also used.

h = S + Sp + Sops (1) Here, S is a drafting device, Sp is a mill elongation, and Sops is an offset.

Problems to be Solved by the Invention In the roll force monitor AGC, if there is an error in the thickness stored at the time of lock-on, this error is maintained as it is, and the thickness deviation from the target value is measured after being measured by the thickness gauge. It is fed back and corrected in addition to the stored target thickness, but the correction is made after the tip of the plate reaches the thickness gauge, and the correction is started and the thickness is within the allowable range Since there is a time lag until then, the so-called off-gauge portion during which the sheet thickness does not fall within the allowable range.

Even in the case of using the absolute value AGC, the correction is performed so that the deviation Δh between the plate thickness measured when the plate is bitten by the roll and the absolute target plate thickness becomes 0 (see FIG. 6). An off-gauge part occurs until it appears.

A first object of the present invention is to provide an AGC method capable of controlling a plate end portion which has been scrapped as an off-gauge portion to a target plate thickness.

A second object of the present invention is to correct the milling speed when correcting the rolling position at the time of re-setup for controlling the plate thickness so that the mass flow does not collapse and the tension fluctuation does not occur. is there.

A method for achieving the first object is to calculate a draft reduction amount from a deviation between an actual value obtained by a gauge meter type and a target plate thickness when the plate tip bites into a preceding stand, Feed forward to the next stand, adjust the roll-down position and set up the next stand again, and correct the roll speed of the previous stand according to the mass flow change due to the correction of the roll-down position of the next stand. A step of controlling the inter-stand tension at the time of biting to a target value, and a step of correcting the rolling position so that the deviation between the actual value at the stand and the target plate thickness becomes zero when the plate tip bites into the stand. Characterized by a combination of

In another method for achieving the above object, after the thickness of the outlet side is further measured in the above method, a deviation from the target thickness is fed back to each stand.

A method for achieving the second object is to feed-ford the deviation between the actual value obtained by the gauge meter type and the target plate thickness to the next stand when the plate tip bites into the former stand, and to determine the rolling position. In the method of adjusting and setting up the next stand again, the roll speed of the former stand is corrected by the following equation.

Where Δvi / vi: the rate of increase in roll speed before the previous stand fi: the advance rate of the preceding stand Δfi: the increase rate of the advance rate of the preceding stand hi: the exit thickness target of the preceding stand Δhi: the exit thickness of the preceding stand Quantity fj: Advance rate of next stand Δfj: Increase rate of advance rate of next stand Also in this method, the correction of the rolling position may be performed in combination with the absolute value control. The deviation from the plate thickness may be fed back to each stand.

Operation In the i-stand, as shown in FIG. 3, when the thickness on the entry side is h, the mill constant M is set to obtain the target thickness h _ai.
In consideration of the above, the rolling position is set to S _i . However, if the actual load _Fr is higher than the set predicted load F _i , the actual thickness h _mi obtained from this is Δh greater than the target thickness h _ai. Only thicker. In the i + 1 stand, the entrance thickness is set to h _ai as shown in FIG. 4, but the actual entrance thickness is h _mi.
Therefore, the rolling position is changed by ΔS _i to obtain the initial target plate thickness ha _{(i + 1),} and is reset to S _{i + 1} . In this re-setup, the tip of the board bites into the i-stand in the previous stage,
At the time when the actual plate thickness h _mi is obtained, the process is performed based on the output signal. When the plate tip bites into the i + 1 stand next time, rolling is performed at the re-set down position, but the actual plate thickness obtained from the actual load and the target plate thickness ha _{(i + 1)}
If there is a deviation between the values, the rolling position is corrected so that the deviation becomes zero.

As described above, when the sheet tip bites into the preceding stand i, the sheet thickness deviation Δh is fed forward to the next stand i + 1, and the next stand is set up again. When the plate tip bites into the stand i + 1 next, the absolute value is controlled, and the rolling down position in the next stand is controlled in two steps.
As a result, as shown in FIG. 5, the deviation Δ
h is reduced and the reduction amount is also reduced, so that the time T until the control is completed is also the time T when the absolute value control is performed alone.
(See FIG. 6). Therefore, the effect until the correction is made can be quickly achieved, and the off-gauge portion is reduced.

FIG. 5 shows the variation of the sheet thickness when the thickness on the delivery side is measured, the deviation from the target sheet thickness is fed back, and three-stage control is performed.

 Next, the correction of the roll speed will be described.

In FIG. 7, between the i-stand and the j-stand,
The following equation holds.

(1 + fi) vi = (1 + bj) vj (2) Now, the advance rate of the i-stand is fi + Δfi, the reverse rate of the j-stand is bj + Δbj, and the roll speed of the i-stand is vi + Δ
Assuming that the roll speeds of the vi and j stands have changed to vj + Δvj, in order to keep the mass flow constant,
The following equation holds.

(1 + fi + Δfi) (vi + Δvi) = (1 + bj + Δbj) (vj + Δvj) (3) By expanding the equation (3) and organizing it as ΔfiΔvi ≒ 0, ΔbjΔvj ≒ 0, Δfivi + (1 + fi) Δvi = Δbjvj + (1 + bj) Δvj. Dividing both sides by (1 + fi) vi and rearranging by setting Δvj = 0, In the j-stand, from the constant volume law, (hi + Δhi) (1 + bj + Δbj) vj = (1 + fj + Δfj) vj (hj = Δhj), which is developed, and both sides are divided by hj (1 + bj). Is required. Therefore, equation (4) is It is expressed as Here, since the outlet side of the j-stand is reduced to hj, Δhj = 0.

Therefore, the correction of the roll speed in the front stand It is expressed as

First Embodiment In FIG. 1, a rolling load measured by a roll cell 3 of each stand 2 and a rolling position from a rolling position detecting device 4 are input to a controller 1.
Is input.

As shown in FIG. 2, the controller 1 controls the rolling load F and the mill constant M input from the load cell 3 of each stand.
Based on the above equation (1), the plate thickness when the plate bites from the rolling position S and the rolling position S is calculated, and the deviation Δh from the target plate thickness set for each stand is calculated. From the obtained deviation Δh, the correction amount ΔS of the rolling position at the next stage stand is Δ
S = (M + Q) / M · Δh, and the control signal is output to the pressure reduction device 6 of the next stand. Then, the rolling position initially set up at the next stand is corrected.

The correction amount ΔS of the rolling position at the stand is calculated from the obtained deviation Δh, and the control signal is output to the rolling device 6 of the stand.

Further, a calculation for correcting the roll speed in the preceding stand is performed by the above equation (7) based on the obtained deviation Δh, and a control signal is output to the roll driving motor 7 of the preceding stand based on this.

The controller 1 also calculates a deviation from the target plate thickness from the plate thickness input from the thickness gauge 5, and calculates a correction amount of the rolling position distributed to each stand. Then, the feedback is fed back to each stand, and each pressure reduction device 6 is controlled.

Effects of the Invention The present invention is configured as described above and has the following effects.

The method according to claim 1, wherein the sheet thickness deviation is fed forward to the next stand when the plate tip bites into the preceding stand, the next stand is reset up, and the plate tip bites into the next stand. Absolute value control is performed, and the rolling position at the next stand is controlled in two stages.The amount of reduction in absolute direct control is reduced, so the time until control is completed is also shortened. In addition, the number of off-gauge portions is reduced, and the number of scrap ends is reduced.

Further, as in the method according to the second aspect, if the deviation between the output side thickness measured by the thickness gauge and the target thickness is fed back after the method according to the first aspect is performed, the target thickness is accurately controlled. be able to.

According to a third aspect of the present invention, the rolling position of the next stand is corrected by the thickness deviation when the plate tip bites into the first stand, and the roll speed of the first stand is corrected accordingly to maintain a constant tension. Even if the rolling position is corrected, the mass flow does not collapse and the thickness does not fluctuate.

[Brief description of the drawings]

FIG. 1 is a schematic view of the method of the present invention, FIG. 2 is a functional block diagram of a controller, FIGS. 3 and 4 are diagrams showing the relationship between rolling load and sheet thickness, and FIG. FIG. 6 is a diagram showing a deviation when value control is performed, FIG. 6 is a diagram in a conventional absolute value control, and FIG. 7 is a diagram showing setting conditions in a stand. DESCRIPTION OF SYMBOLS 1 ... Controller, 2 ... Stand 3 ... Load cell, 4 ... Roll-down position detection device 5 ... Thickness gauge, 6 ... Roll-down device, 7 ... Motor

Continuation of the front page (56) References JP-A-60-99410 (JP, A) JP-A-60-227909 (JP, A) JP-A-62-156014 (JP, A) JP-A-62-156015 (JP, A) , A) (58) Field surveyed (Int. Cl. ⁶ , DB name) B21B 37/16-37/20

Claims (3)

(57) [Claims] 1. A deviation between an actual value obtained by a gauge meter type and a target plate thickness when a plate tip bites into a preceding stand is fed forward to a next stand, and a rolling position is corrected to correct the next stand. A step of resetting and correcting the roll speed of the preceding stand according to the mass flow change due to the correction of the rolling position of the next stand, and controlling the inter-stand tension at the time of engaging the next stand to a target value,
An automatic thickness control method comprising a combination of steps of correcting a rolling position so that a deviation between a target thickness and an actual value at the stand becomes zero after the tip of the plate is engaged with the stand. . 2. A control for feeding back a deviation from a target sheet thickness to each stand after the sheet thickness on the delivery side is measured.
An automatic thickness control method in combination with the automatic thickness control described above. 3. The deviation between the actual value obtained by the gauge meter type and the target plate thickness when the plate tip bites into the previous stand is fed forward to the next stand, and the rolling position is adjusted to adjust the next stand. An automatic thickness control method in which a roll speed before a preceding stand is corrected by the following equation in a method of re-setup. Where Δvi / vi: the rate of increase of the roll speed of the preceding stand fi: the advance rate of the preceding stand Δfi: the increase rate of the advance rate of the preceding stand hi: the target thickness of the exit side of the preceding stand Δhi: the increase of the exit side thickness of the preceding stand fj: Advance rate of next stand Δfj: Increase rate of advance rate of next stand