JPS6016853B2 - Method for straightening L-curvature of steel plates and steel strips - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for straightening L-curvature of steel plates and steel strips using a tension leveler.

Generally, it was said that L-curvature (longitudinal curvature) of cold-rolled steel plates and tinplate can be corrected to some extent by rolling down the leveler.

The conventional L warp correction method using a roller leveler measures the L warp of several liters at the coil top, adjusts the position of the final roll mainly of the roller leveler, and then
The L warp was measured once every 00q female (approximately 10n), and if there was a change in the L warp, the amount of reduction of the shingles was adjusted.

A typical coil has an IQon of about 1 to 1, and each coil needs to be adjusted 10 to 15 times. In recent years, the tolerance range for L warpage that is particularly required for tinplate has become stricter, and for example, the amount of hanging warp per several cutting lengths (80 squares) may be set to a control value of 12 ribs or less. However, it is very difficult to satisfy the above-mentioned control values using the conventional shingler operation, and this also causes a decline in product quality. In addition, regarding the box Akatsuki Anchor tin material, the leveling speed is 30 m by the tension leveler of the subordinate.
The relationship between the plate thickness and the L warp of a product that has undergone L warp correction during PM and has been cut through the electrolytic tin plating process is as shown in Figure 1. As shown in this figure, L
Warpage is greatly affected, but in the above-mentioned conventional art, it is extremely difficult to prevent L warp due to variation in plate thickness, and this type of L warp control has not been carried out. In addition, the measured distance in FIG. 1 is 1.7. Regarding L warpage control due to plate thickness fluctuations, once the amount of L warp due to plate thickness fluctuations is known, it is possible to control the L warp within a certain range by operating the leveler and below based on the signal from the thickness gauge installed upstream of the leveler. Predictive control can also be considered, but such a method requires expensive equipment that has not been reinstalled in the shear line. For example, the delay time correction to follow the line speed is D
Because it is DC (direct digital control) control, a microcomputer is required, and because it controls plate thickness fluctuations in a very short period, the reduction motor needs to have a large capacity and high response. The above problems are important. The present invention focuses on the problems of the above-mentioned problems,
It is an object of the present invention to provide an L-curvature correction method that can be an extremely effective correcting method for L-curvature due to uncontrolled plate thickness variations.

In order to achieve the above objective, in consideration of the fact that the contribution rate of plate thickness variation to L warp changes depending on the processing speed during leveling processing, we have developed a method that cannot be corrected with conventional roller levelers without using expensive control equipment. A high-speed tension leveler was used to control the variation in L warp due to plate thickness variation to the minimum variation in L warp, thereby improving yield.

Examples of the method for straightening L-curvature of steel plates and steel strips according to the present invention will be described in detail below.

About the box phosphor hammer tin material, the stamen ring speed is 30 skin p.
The amount of plate thickness variation R in m and the amount of L warp W with respect to the plate thickness R
is shown in FIG. 1, and its representation as a scatter diagram and regression line is shown in FIG.

According to this figure, the regression equation is expressed as W=-81 (R is the plate thickness, W is the amount of L warp), and the correlation coefficient is r=0.
It is 74. On the other hand, the plate thickness R and L warpage amount of the same material were manufactured by using a tension leveler at a leveling speed of 120 pm' with a trowel, after electro-tin plating process, and then scaled on a cutting line. The relationship between W and its scatter diagram and regression line are shown in FIGS. 3 and 4.

However, since most of the L warp was corrected using a tension leveler, there was almost no rolling down at the cut line.
The regression equation in Figure 4 is shown as W = -31 105 (R is the plate thickness, W is the amount of L warp), and the correlation coefficient is r = 0.5.
It is 3. For these reasons, with the conventional roller leveler at 30 ratio hpm for plate thickness variation] OA, L warpage is 8.
While the skin has fluctuations (Figure 2), the leveling speed is 1.
It can be seen that when the stamens are corrected at 20 hpm, the L warp fluctuates by 3 bars. In this way, by changing the leveling speed, L
Although the warpage fluctuation amount is different, the leveling speed V=
Plate thickness variation △R = 10 for box competitive tinplate material and continuous phosphorescent tinplate material at 300 to 120 hpm
The L warp variation amount ΔW with respect to r is expressed as shown in FIG.

In addition, the box phosphorescent tinplate material is shown by curve A, and the continuous phosphorescent tinplate material is shown by curve B. From this figure, it was found that the lower the leveling speed and the softer the material, the larger the L warp variation ΔW due to plate thickness variation. Here, curves A and B can generally be approximated by the following equations.

△VV=a-b・VC...'
1}a, b, and c are positive coefficients that change depending on the deformation resistance of the steel plate, the plate thickness fluctuation amount ΔR, the plate thickness of the original plate, etc.

Therefore, as mentioned above, it is necessary to calculate it in advance by experiment for each target material. Curve A in FIG. B is expressed by the following formulas . △W=16-1.23V
o・34 (correlation coefficient r: 0. Iso).・・・． ...{21st evening △W=8.5-0. N8V0・6o4 (correlation coefficient r=
0.99) ......■ Therefore, in this embodiment, the method of controlling the L warp amount W to a certain control value is carried out as follows. Now, the L warp value of the box scale anchor tin material La
In the case of controlling the warpage to be less than the diameter, the variation B of the L warp value at the same board thickness is measured using a tension leveler.

In this example, from FIGS. 2 and 4, the variation is approximately B=
7 winds. Next, the amount of variation R in plate thickness during cold rolling is measured, and normally for the above-mentioned tinplate material, the amount of variation is ΔR=10 France.

From the above, in order to control the L warp value to be below the control value C=12 side, the L warp variation amount ΔW must satisfy the following equation.

△W+BmiC......■In other words, in this embodiment, C=12 ribs and B=7 side must be substituted into equation {41 to satisfy △Wmi5 wind.

The shingling speed that satisfies the above can be determined from the relationship diagram between the L warp fluctuation amount △W and the shingling speed V for the plate thickness fluctuation amount ΔR = 10 degrees determined in advance (curve A in Figure 5) or from the formula V is 60 skin pm, so the tension leveler is operated at V=6 plate hpm or higher.

FIG. 6 schematically shows the meaning of the left side of the '41 formula, and straight line A corresponds to the regression line in FIGS. 2 and 4.

As described above, in the present invention, when the plate thickness variation during cold rolling is ΔR, the relationship between the L warp variation ΔW and the leveling speed V is determined in advance (see FIG. 5, [Equation 11] ), calculate the L warp fluctuation amount △W from formula {41} so that it is within the L warp control value C, and then perform beveling at a speed higher than that calculated from formula '1} etc., to easily and reliably In this way, the amount of L warpage can be controlled to be below the control value.

As described above, according to the method for straightening L-warpage of steel plates and steel strips according to the present invention, it is possible to sufficiently control L-warp fluctuations due to changes in sheet thickness, which has not been done in the past, to within a control value by changing the sillage speed. This has the effect of making it possible to obtain steel plates and steel strips with improved rolling properties.

[Brief explanation of the drawing]

Figure 1 shows plate thickness fluctuations and L at a line speed of 30 skin pm.
Fig. 2 is a scatter diagram showing the regression line of Fig. 1, Fig. 3 is a graph showing the amount of plate thickness variation and L warpage at a line speed of 1200 hpm, and Fig. 4 is a graph showing the amount of L warp. Figure 3 is a scatter diagram showing the regression line, Figure 5 is a graph showing the amount of variation in L warpage at the shingling speed and variation in plate thickness 10r, and Figure 6 is a graph showing the amount of variation in plate thickness, variation in L warpage, and L
It is a schematic diagram which shows the relationship with the amount of warpage variation. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] 1. For a tension leveler that corrects the L warp of steel plates and steel strips, the amount of L warp variation ΔW due to plate thickness variation is calculated using the following formula, and ΔW+B≦C, where B: for the same plate thickness. Dispersion of L warpage value C:
Management value of L warp Next, use the following formula to find the leveling speed V corresponding to the above L warp fluctuation amount ΔW, ΔW = a-b・V^c, where a, b, and c are positive coefficients. A method for straightening L-curvature of steel plates and steel strips, which comprises controlling the amount of L-curvature variation due to variation in plate thickness by straightening the L-curvature of steel plates and steel strips.