JPH0576917A - Method for controlling thickness of thick plate - Google Patents

Abstract

PURPOSE:To set roll gap and to improve accuracy of thickness control by expressing the deviation of thickness in terms of the correct ion quantity of roll gap for the next pass and adding target correcting gap that is multiplied by a formula 2 to the roll gap in the gagemeter model for the next pass. CONSTITUTION:Deviation of a measured value of thickness from the target thickness hg in the gagemeter model shown by the formula 1 is expressed in terms of the correction S of roll gap for the next pass and also the roll gap for the next pass is set by adding the target correcting gap S' that is determined by multiplying the value S by an equivalent gain G shown by the formula 2 to the roll gap S in the gagemeter model for the next pass. Where, in the formula 1, hg: target thickness, S: roll gap at the time of no-load, P: rolling load, KM: rigidity of mill, (delta: profile of roll. In the formula 2, M: plastic coefficient, K: constant of mill.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plate thickness control method for thick plates by absolute value AGC.

[0002]

2. Description of the Related Art Plate thickness control in the rolling of a thick plate is generally performed by an automatic plate thickness control by an absolute value AGC (Automatic Gauge Control) constituted by a combination of a gauge meter model (GM) and a hydraulic pressure reducing device. Target.

The gauge meter model is represented by, for example, the following expression 1, and the accuracy of the absolute value AGC depends on the accuracy of this gauge meter model.

[0004]

[Equation 1]

Therefore, various measures have been conventionally made to improve the accuracy. In particular, analytical modeling of roll deformation behavior and roll profile change can be mentioned.

[0006]

However, no matter how high the accuracy of the model is, various online fluctuations (e.g., when the chock has mechanical backlash, even if the same load is applied, the elongation of the mill is different). It is not possible to absorb sudden changes such as rolling, which impairs the reproducibility of mill rigidity, and sudden changes in roll profile. Therefore, in general, a thickness gauge is installed around the rolling mill, and by measuring the plate thickness during rolling, the deviation from the target plate thickness hg of the gauge meter model is learned as an error, and these variations are absorbed. ing.

Although the above method is effective for the change of the roll profile, the error is rather amplified for the fluctuation of the mill rigidity caused by the above-mentioned sudden fluctuation due to the mechanical backlash.

The present invention was devised in view of the above problems of the prior art. A long-period error due to a change in roll profile or the like is learned as usual, and the above-mentioned sudden fluctuations are It is intended to provide a configuration that can correct the error in a short time without recalculating the reduction schedule.

[0009]

Therefore, the present invention is directed to plate thickness.
In the plate thickness control method for a thick plate based on the gauge meter model, in which the deviation from the target plate thickness hg of the gauge meter model shown in Formula 1 above is learned as an error by actually measuring hm, the deviation is rolled in the next pass. The target correction gap ΔS ′ obtained by converting the gap correction amount ΔS and multiplying it by the equivalent gain G shown in Equation 2 below is added to the roll gap S in the gauge meter model of the next pass to add the roll of the next pass. The basic feature is to set a gap.

[0010]

[Equation 2]

The method of the present invention will be described in detail below.

In thick plate rolling, reverse rolling is generally carried out by the same rolling mill to obtain a target plate thickness through a plurality of passes. In the plate thickness control by the absolute value AGC in the thick plate rolling, a plurality of gauge meter models corresponding to the entrance side plate thickness H are prepared in each pass, and the exit side plate thickness h of the preceding pass is the entrance side plate thickness H in the next pass. Then, the gauge meter model of the next pass is selected accordingly, and the rolling-down schedule is determined by repeating this procedure. Further, as shown in FIG. 1, usually, a thickness gauge 2 is provided close to the rolling mill 1, and the thickness hm actually measured by this and the target thickness hg of the gauge meter model are
If and do not match, learning control for correcting the gauge meter model is performed using the error (hm−hg) as an offset.

In the plate thickness control by such a gauge meter model, an appropriate gauge meter model is selected by determining the entrance side plate thickness H in an arbitrary path, and the default value S of the roll gap is input. It is expected that the rolling load P obtained from the intersection of H and S will be generated by the gauge meter model as shown in Fig. 2, and as a result, the outlet side plate thickness will become the target plate thickness hg. Value hm
Will match.

However, when there is a variation such that the entrance side plate thickness becomes H ', a load P'is generated unless the roll gap S is corrected, and the exit side plate thickness becomes h'.

Here, in the AGC, the load fluctuation ΔP (= P '
-P) is detected, the roll gap is corrected to S '(roll gap correction amount ΔS = S-S'), and it acts to protect the outlet side plate thickness hg (otherwise, the following rolling schedule is It is forced to recalculate.

However, until such an AGC function works effectively, the time required for calculation and the time required for the hydraulic system to operate effectively take a lot of work, especially at the roll biting stage. Rolling is performed in a state where the roll gap is not corrected by.

On the other hand, the entrance side plate thickness H'is measured in advance by the thickness gauge.
Since it was measured at 2 (measured by the thickness gauge 2 at the exit side of the previous pass), the present invention decided to correct the roll gap before the above-mentioned gap control by the AGC. As shown in FIG. 2, if the roll gap is set to S ″ before the gap control by the AGC (for example, the roll biting stage), the amount of correction by the AGC that will act after that will be small. By such a process, the plate thickness control accuracy until the AGC works effectively is also improved.

FIG. 3 is a flow chart showing a method of calculating a gap correction amount for roll gap control according to the present invention.

In the first pass, the plate thickness is controlled by AGC using a gauge meter model, and the outgoing target plate thickness hg in this pass is already determined. Since the target plate thickness hg matches the entrance side plate thickness H of the next pass, the roll gap is set to S even in the gauge meter model of the next pass corresponding to this entrance side plate thickness H based on the already determined rolling schedule. Has become.

However, at the exit side of the preceding pass, its plate thickness hm
Is measured by the thickness gauge 2, and when the measured thickness hm is different from the output side target thickness hg, the roll gap S of the next pass is originally expressed by the following formula 3. It becomes necessary to correct the correction amount ΔS.

[0021]

[Equation 3]

In the AGC, originally, the reduction load correction amount corresponding to the roll gap correction amount ΔS is also obtained, and it should be operated so that the exit side plate thickness of the next pass becomes the target plate thickness hg.

However, in the present invention, the responsiveness of such AGC correction processing is not good for sudden fluctuations, so the roll gap alone is corrected to some extent prior to the correction by AGC. . The correction amount is not the entire roll gap correction amount ΔS, which is the amount to be originally corrected, but a portion corresponding to some of the correction amount (this is the target correction gap ΔS ′). The target correction gap ΔS ′ is a value obtained by multiplying the roll gap correction amount ΔS by the equivalent gain G obtained as follows (that is, obtained by the following equation 4).

[0024]

[Equation 4]

When the roll gap is further changed by .DELTA.S 'by carrying out the method of the present invention as described above, the variation .DELTA.P' of the rolling load is expressed by the following equation (5).

[0026]

[Equation 5]

Due to the occurrence of this load fluctuation ΔP ', the AGC
In this case, the correction by the roll gap correction amount ΔS ″ shown in the following equation 6 is performed later (for example, after the roll is bitten).

[0028]

[Equation 6]

Therefore, the sum of ΔS ′ and ΔS ″ should be the same as the roll gap correction amount ΔS, which is the amount to be originally corrected, and the following expression 7 is obtained.

[0030]

[Equation 7]

Therefore, the equivalent gain G obtained as ΔS ′ / ΔS is as shown in the above equation 2.

The target correction gap ΔS 'obtained as described above is added to the roll gap amount S already determined by the gauge meter model of the next pass, and in the present invention, the sum of the two is added to the roll gap of the next pass. Set again as and move to the next path. In the next pass, the roll gap is corrected (ΔS ″) by AGC after the roll is bitten.

[0033]

EXAMPLES In order to confirm the effect of improving the accuracy of plate thickness control by the method of the present invention, the present inventors conducted the following experiments.

Using a quadruple reversible finish rolling mill whose detailed specifications are shown in Table 1 below, two slabs of the same standard (SS 400) and the same size (247 mm x 1594 mm x 4680 mm) on the same schedule are used. Rolled continuously, 16mm x 3048mm x 3657
I tried to get a rolling dimension of 6 mm.

[0035]

[Table 1]

In the above rolling, the first method was carried out by the method of the present invention (control "ON"), and the second method was carried out by the conventional method (control "OFF"). Figure 4 shows the entry of the last pass at that time.
The plate thickness deviation chart which shows the delivery side thickness is shown.

In the conventional method, the gap between passes is not corrected as in the method of the present invention, and only the correction by AGC is performed. As a result, as shown in the delivery side thickness, the deviation in plate thickness at the time of roll biting becomes large. . On the other hand, in the method of the present invention, as a result of the correction of the inter-pass gap as described above, the plate thickness deviation at the time of roll biting was also small, and the effect was confirmed.

[0038]

As described in detail above, according to the method of the present invention, even if the roll gap of the next pass cannot be corrected immediately by AGC due to a sudden plate thickness variation occurring during rolling, the correction can be preceded. Since only the roll gap is corrected to some extent in advance, the plate thickness control accuracy at the roll-engaging stage of the next pass can be improved.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an example of an implementation configuration of automatic plate thickness control based on an absolute value AGC.

FIG. 2 is a graph showing a control method according to the method of the present invention in determining a plate thickness by AGC.

FIG. 3 is a flowchart showing a method of calculating a gap correction amount for roll gap control in the method of the present invention.

FIG. 4 is a chart showing sheet thickness deviation amounts with and without the inter-pass gap correction according to the method of the present invention.

[Explanation of symbols]

 1 Rolling mill 2 Thickness gauge

Claims (1)

[Claims] 1. A plate thickness control method for a thick plate based on the gauge meter model, wherein a thickness hm is actually measured and a deviation from a target plate thickness hg of a gauge meter model shown in the following formula 1 is learned as an error. The deviation is converted into the roll gap correction amount ΔS of the next pass, and the target correction gap ΔS ′ obtained by multiplying this by the equivalent gain G shown in the following equation 2 is used as the roll gap S in the gauge meter model of the next pass. In addition, a plate thickness control method for a thick plate, characterized in that the roll gap of the next pass is set. [Equation 1] [Equation 2]