JP2650575B2 - Thick plate width control rolling method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thick plate rolling method for controlling a plate width in thick plate rolling including tentering rolling.

[0002]

2. Description of the Related Art Conventionally, a slab manufactured by continuous casting or slab rolling has been used as a raw material and reversible rolling has been performed on the slab to produce a thick plate having a predetermined size. In some cases, rolling is performed after changing the direction of the rolled material by 90 degrees to a predetermined width.

In the rolling of a thick plate including such a tentering roll, it is important to control the plate length in the tentering rolling, and several methods for controlling the length with high precision have been proposed. As one of them, the present applicant has previously proposed the following method in JP-A-62-137114. In this method, a plate length measuring device is provided on at least one of the entrance side and the exit side of the rolling mill, the length of the rolled material is measured near the final pass of tentative rolling, and the final tentering is performed by the following equation (1). This controls the thickness of the pass.

[0004]

(Equation 1)

[0005] Here, H _Dw: target thickness after tentering rolling, H _D: thickness when measuring the rolling length W _D in tentering rolling, W _D: pressure measured during tentering rolling extension of, W _a: is the target plate length in tentering rolling.

Usually, the thickness before and after tentative rolling cannot be measured with a thickness gauge using, for example, radiation. Therefore, in general, the thickness is indirectly measured by a gauge meter type as shown in the following formula (2). Control is performed using the plate thickness.

H _g = S + P / M (2) where h _g: gauge meter thickness, S _: roll gap, P _: rolling load, and M _: mill stiffness coefficient.

However, as a matter of course, since the sheet thickness according to the equation (2) is not directly measured, they include errors. The method disclosed in Japanese Patent Application Laid-Open No. 137114/1987 is characterized in that the influence of this error on thickness control can be reduced. However, even in the method disclosed in Japanese Patent Application Laid-Open No. 62-137114, it was inevitable that a large thickness measurement error would greatly affect the thickness control.

[0009]

SUMMARY OF THE INVENTION It is an object of the present invention to estimate such a thickness measurement error and reflect the error in the thickness control so that the width control can be performed with high accuracy regardless of the magnitude of the thickness measurement error. It is to do.

[0010]

According to the inventor's knowledge, in the tentering rolling of a thick plate, a thickness measurement error is estimated by measuring the length of the plate at least twice, and this is used for controlling the thickness. The present inventors have found that the reflection makes it possible to control the thickness of the sheet after tentering and rolling with high accuracy, and completed the present invention.

That is, the gist of the present invention is as follows.
Thick plate that is subjected to rough rolling, width rolling, and finish rolling
Length measurement during tentative rolling
Perform at least two times to estimate the thickness measurement error and perform tentering rolling
Is reflected in the thickness control in the final pass
This is a method of controlling the rolling width of a thick plate. Here, the specifics of the present invention
According to the aspect, in plate rolling in which a plate having a target plate width is manufactured by controlling the plate thickness after tent rolling, during tent rolling, at least one or both of before and after the pass in two passes. the length of the rolled material is measured based on the measurement length respectively obtained, to estimate the thickness measurement error, the reflecting plate thickness control of the tentering rolling of the final pass
It is .

[0012]

Next, the present invention will be described in more detail. In the method of the present invention, for example, before the start of the tent rolling, the slab width, that is, the initial length W of the plate in the tent rolling is first determined.
s is measured, and the target thickness of the tentative rolling pass is set by the following equation (3).

[0013]

(Equation 2)

Here, _{HDW (1)} : target plate thickness in the middle of the tentative rolling pass, Hs: plate thickness before the start of the tentative rolling, Wa ₍₁₎ : target plate length in the middle of the tentative rolling pass It is.

The numbers in parentheses indicate the first sheet thickness control pass. However, as described above, since the sheet thickness Hs before the start of the tentering rolling includes a thickness measurement error, the equation (3) is rewritten in consideration of this, and the following equation (4) is obtained. become.

[0016]

(Equation 3)

Here, ΔH: thickness measurement error. Further, (4) calculated tentering during rolling path by the formula
Based on the target sheet thickness H _{DW (1)} , the sheet width { _{WDW (1)} } of the rolled material is given by the following equation (5) based on equation (4) .

W _{DW (1)} = Ws × Hs / (H _{DW (1)} −ΔH) (5) Next, in the present invention, immediately after the pass in which the thickness is controlled,
By measuring the plate length again, the equations (4) and (5) are obtained.
ΔH ′ is estimated using the following equation (6) obtained from

ΔH ′ = − Hs (wa ₍₁₎ × Ws−W _{DW (1)} × Ws) / {W _{DW (1)} × (Ws−Wa (1))} (6) ΔH ′: Estimated value of ΔH. Then, using this ΔH ′, it is obtained from equations (3) and (6).
And (7) below reflects the [Delta] H 'by setting the target thickness at the tentering final pass in the thickness control in the tentering final pass by formula.

[0020]

(Equation 4)

Further, the plate length controlled by taking into account ΔH ′ according to the equation (7) is as shown in the following equation (8) obtained from the equation (7) .

[0022]

(Equation 5)

However, what matters here is the estimation accuracy of ΔH, that is, the difference between ΔH and ΔH ′. Therefore, in order to minimize the difference between ΔH and ΔH ′, ΔH ′ is
As shown in equation (9), a correction calculation is performed for each sheet rolled.

ΔH ″ ← (1−α) ΔH ′ + αΔH (9) where α: learning coefficient ΔH ”: The corrected ΔH ′ ΔH gradually changes during rolling, and therefore, If ΔH ″ modified by equation (9) is used instead of ΔH ′ without directly using ΔH ′, ΔH can be estimated with considerably high accuracy. Here, the present invention will be described with reference to the accompanying drawings. Fig. 1 is a schematic diagram of a width controlled rolling process of a thick plate using the method of the present invention.

That is, the slab material 10 sent from the heating furnace is first roughly rolled to a predetermined thickness by reversible rolling (form rolling). After rolling into a general shape, the rolled material is turned by 90 degrees at the location marked "turn" in the figure, and then width-rolled by reversible rolling.
Reference numeral 1 denotes a length measurement position, and reference numeral A denotes a width reduction correction position.

According to the present invention, in the tentering rolling, the length is measured and the width reduction is corrected based on the measured length data, and this is performed at least twice. After the end of the tentering rolling, the direction is changed by 90 degrees again at the position marked "turn", and finish rolling is performed.

That is, the target thickness is determined from the measured initial length by the equation (3). To achieve the target thickness,
Control the thickness. However, the determined target thickness and the thickness controlled to achieve the target thickness include a thickness measurement error ΔH as shown in Expression (4).

Therefore, the second sheet length measurement is performed, and the measurement data at that time is used to calculate the sheet thickness measurement error Δ by the equation (6).
By estimating H and using it to determine the target thickness of the final pass of the tentative rolling by Equation (7), the estimated value is reflected in the thickness control after the tentative rolling, and in order to achieve the target thickness. formula
The plate thickness is controlled by (8).

In the middle of the tentering rolling, 2% in the illustrated example.
Measure the disc length. The measuring device is provided as close as possible to the entrance or exit of the rolling mill. It should be noted that measuring instruments such as length gauges are already obvious to those skilled in the art and do not require further explanation.

In the above description of the present invention, an example was given in which the number of sheet length measurements during the tentering rolling was two, but the sheet length measurement may be performed three or more times. As the number of measurements increases, the estimation of the thickness measurement error also becomes more accurate.

[0031]

Next, the operation and effect of the present invention will be described more specifically with reference to examples. In this example, in order to confirm the effect of the present invention in accordance with the rolling process shown in FIG. 1, 300 thick plates having the dimensions shown in Table 2 were continuously rolled, and a comparison of the average plate width error with the conventional method was performed. went. here,
As the learning coefficient α of “ΔH” in the equation (9), α = 0.4 was used.

The results are summarized in Table 1. Table 1 shows that the method of the present invention can control the sheet width with higher accuracy than the conventional method. The conventional method is based on the control method disclosed in Japanese Patent Application Laid-Open No. 62-137114, in which the length is measured once and the thickness is controlled in accordance with equation (1). The slab dimensions and rolling dimensions are also shown in Table 2.
It is as follows.

[0033]

[Table 1]

[0034]

[Table 2]

[0035]

As described above in detail, according to the present invention, the width error is greatly reduced, and the yield is expected to be improved accordingly. In particular, in the case of a thick plate, such an improvement effect is large, and the practical benefit is large.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory diagram of a control example using the method of the present invention.

Claims (1)

(57) [Claims] 1. Rough rolling, width rolling, and finish rolling
In the rolling of thick plate performed through
Estimate thickness measurement error by performing length measurement at least twice
To reflect the thickness control in the final pass of tentative rolling.
And a width controlling roll method for a thick plate.