JPH05200404A - Method for manufacturing metal plate with small edge drop - Google Patents

Abstract

(57) [Summary] [Purpose] To manufacture metal plates with small edge drops. [Structure] A metal plate S before entering a row of tandem rolling mill is pressed down in a width direction by an edger 4 to make a plate width end portion into a dogbone shape, and then at least the most upstream one stand is a tandem rolling mill. Cold rolling in the machine train 8.
It is desirable to use the strip width gauge 6 and the strip thickness gauge 9 together, and to operate while setting conditions based on these measured values. [Effect] By using an edger and a roll cross rolling machine together, a metal plate having a small cross section and a small edge drop and a small plate crown can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a metal plate having a phenomenon in which a strip width end portion of a rolled material is thinned during cold rolling, that is, so-called edge drop is reduced.

[0002]

2. Description of the Related Art Recently, the demand for improving the quality of metal sheets such as cold rolled steel sheets produced by cold rolling has become extremely strict, and in addition to the accuracy of the thickness in the longitudinal direction, there is a problem such as a sheet crown and an edge drop. The demand for cross-sectional shape in the plate width direction is also increasing.

Edge drop is a phenomenon in which the plate thickness rapidly decreases from about 50 mm at the plate width end to the plate end. Generally, local elastic deformation of the work roll and width direction plasticity at the plate width end of the material to be rolled. It is thought to occur due to the flow. For this reason, the occurrence of edge drops is inevitable even with various means such as a pair cross mill, a work roll bender, a work roll shift, an HC mill, and a VC mill that have been put to practical use as crown shape control methods. A practical method to obtain a steel plate with a uniform width cross-section without edge drops is to trim both ends of the steel strip from several millimeters to several tens of millimeters by side trimming and remove the edge drop portion. Causes a significant decrease in product yield.

As a technique for preventing the occurrence of edge drops during rolling, there is a method of using a trapezoidal roll having a tapered end portion as a work roll. This is to reduce the amount of reduction at the edge of the plate width and to reduce the edge drop by tapering the roll. However, in the operation of the actual machine, the width of the metal plate to be rolled is not constant, so it is necessary to set the taper portion of the roll at an optimum position according to the plate width. Therefore, as shown in FIG. 3, the taper is provided on each of the upper roll 1 and the lower roll 2, and these rolls are also movable in the left-right plate width direction. Although it is easy to change the shape of the roll, this method has problems such as wear of the roll edge and securing of alignment accuracy between the roll and the metal plate S. In addition, since the taper is simply added to the roll, the effect of reducing the edge drop alone is poor.

FIG. 4 is a schematic view of a strip edge shape correcting device (edger) having a horizontal pressing roll 3 whose axis is parallel to the surface of a metal plate, and a vertical roll 4 for edging whose axis is perpendicular to the plate surface. is there. The method using such an edger is to prevent the buckling of the metal plate with a horizontal roll, and to positively increase the plate thickness of the end by pressing down in the plate width direction with the left and right vertical edging rolls. However, there are the following problems in principle. That is, the edge drop occurs from about 50 mm to the plate edge. Therefore, in order to eliminate the edge drop only with the cold edger, the depth of deformation in the plate width direction due to edging (the region where the plate thickness is deformed by edging) is also required to be about 50 mm. However, even if the depth of deformation in the width direction due to edging is large, it is 2.5 times the edging amount (the width of the plate that decreases under the pressure of the edger). Furthermore, when edging with an ordinary cold-rolled steel sheet edger, if the edging amount exceeds 20 mm, the steel sheet will buckle,
No further edging is possible. Therefore, it is difficult to completely eliminate the edge drop only with the cold edger.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a metal sheet having no or very little edge drop, especially a cold rolled steel sheet.

[0007]

The gist of the present invention resides in the following method for manufacturing a metal plate. That is, using the edger which is rolled down in the width direction as shown in FIG. 4 and the tandem rolling mill train incorporating the roll cross rolling mill as at least the most upstream one stand, the metal before entering the tandem rolling mill train is used. A method for producing a metal plate with a small edge drop is characterized in that the plate is rolled down in the width direction with an edger to make the plate end part into a dogbone state, and then rolled with the above tandem rolling mill train.

In carrying out the method of the present invention, a board width meter is installed in front of the edger, the board width before edging is measured by the board width meter, and the edging amount of the edger is controlled within a range of 2 to 15 mm. Is desirable. In addition to this, it is more desirable to install a plate thickness gauge on the exit side of the tandem rolling mill train and control the cross angle of the upper and lower rolls of the rolling mill based on the measured value.

FIG. 1 is a schematic view showing an equipment arrangement for carrying out the method of the present invention. The metal plate (for example, strip steel) S is sent out from the pay-off reel 5, rolled through the edger 7 and the tandem rolling mill train 8 to a predetermined plate thickness, and then the tension reel 10
To be wound up. 6 is a width gauge and 9 is a thickness gauge.

The edger 7 used in the above apparatus is pressed down in the width direction by a vertical roll while restraining the plate width direction by a horizontal pressing roll for preventing buckling as shown in FIG. 4 described above. It is a device that can.

The tandem rolling mill train 8 has a plurality of rolling mills (stands) No. 1, 2, 3, ... From the upstream side (entrance side). And, including at least No. 1, one or more rolling mills having a roll cross function (hereinafter,
Roll cross rolling machine).

The roll cross rolling mill is shown in FIG.
As shown in (a) a plan view and (b) a side view), the upper and lower roll axes are opposite to the direction perpendicular to the rolling direction (longitudinal direction) of the metal plate S of the material to be rolled. It is a rolling mill that can be inclined at a certain angle (θ).
There are a type in which only the work roll is inclined and a type in which the backup roll and the work roll are inclined together, and the latter is called a pair cross rolling mill. Either type may be used in the method of the present invention, but the former is preferable because the former causes slack in the roll axial direction between the work roll and the backup roll, resulting in large roll wear.

[0013]

The greatest feature of the method of the present invention is that the edge of the plate is edged up beforehand by an edger so that the cross section has a dogbone shape, and then cold rolling is performed using a tandem rolling mill train including a roll cross rolling mill. To do. In this method, there is more than the effect of reducing the edge drop obtained when using the edger or roll cross rolling mill independently, and depending on the conditions, the edge of the strip may be edged up even after cold rolling. Is also possible.

In the method of the present invention, first, the metal plate before entering the tandem rolling mill train is pressed down in the width direction so that the plate end portion has a dogbone shape. The purpose of this is to positively increase the edge in advance in order to compensate for the edge drop that cannot be avoided in the next cold rolling step.

The edging amount is determined from the strip width before edging (which can be measured by the strip width meter described above) and the predetermined strip width of the product after cold rolling. The optimum range is
2 to 15 mm. Less than 2 mm, less effective, 15 mm
This is because when the value exceeds the range, the edge-up of the plate edge does not disappear even after the completion of cold rolling, which is not preferable as a product.

The number of times of edging may be any number of times as long as the necessary edging amount can be secured, but 1 to 3 times is optimal in consideration of the edging effect and the equipment specifications of the actual machine.

As the edging method, a constant pressure method of edging with a constant pressing force, a constant position method of edging by a constant width, and a constant pressure + constant position method which is a combination thereof can be considered. As long as the edging condition can be satisfied, any method may be used depending on the situation.

For cold rolling after edging, a tandem rolling mill train is used in which at least one stand including at least the most upstream stand is a roll cloth rolling mill. The roll cross rolling mill is used here because this rolling mill has a large crown control ability, and its ability can be used to reduce the edge drop, and the cross angle can be changed relatively easily even during rolling, and the crown can be changed. This is because the fine adjustment of can be performed.

It is desirable to control the cross angle (θ in FIG. 2 (a)) of the upper and lower rolls of the roll cross rolling mill by using a sheet thickness gauge (9 in FIG. 1) on the tandem rolling mill row side. .. In this case, with the thickness gauge, the thickness at the center of the width (H _c )
Measure two of the plate thickness (H ₁₀ ) at the position of 10 mm. Then, defining the edge drop amount of a subject the metal plate with a plate thickness difference _{H c-10 (H c-} 10 = H c -H 10). Here, the use of H ₁₀ to the provisions of the edge drop is that the outer plate end 10mm is a region deformed by edging cold edger spans enough, having a large crown control function in mill This is because even if it is a region, it has no effect of preventing edge drop.

The influence of the cross angle is due to the work roll diameter, barrel length, mechanical crown amount, plate width of steel plate, etc.
Since it depends on many operating conditions, it is necessary to determine the optimum cross angle depending on the operating conditions.

In the method of the present invention in which an edger and a tandem rolling mill train including a roll cloth rolling mill are used in combination, the above-mentioned effects obtained by summing up the effects alone are compared to the case where they are used independently. The reason is estimated as follows.

As described above, elastic deformation of the roll is one of the major causes of the edge drop. This is because the rolling load is not applied to the roll from the outside of the plate edge as shown in Fig. 5, so that the elastic deformation of the roll decreases toward the plate edge even within the plate width due to the influence (A). There is a slope of. In this region, the roll diameter expands outward, and the plate thickness of the material to be rolled decreases toward the edge.

The roll cross rolling machine is originally excellent in the crown control function, and the plate crown can be arbitrarily changed by changing the cross angle. This also means that the inclination of FIG. 5A can be made smaller by adjusting the cross angle as compared with the rolling using the normal parallel rolls. As a result, the tendency of the plate thickness reduction at the edge also becomes gentle. Furthermore, when a metal plate having a so-called dogbone cross section, whose edge thickness is thicker than the central part, is cold-rolled, the load on the edge part increases locally, so elastic deformation of the roll also causes edge deformation within the plate width. It becomes large locally. Therefore, in ordinary rolling, the elastic deformation of the roll is physically reduced, and the plate thickness is gradually reduced, whereas in this case, a force for expanding the edge portion is generated.

As a result of these, as the roll flat profile, the inclination of (A) for reducing the plate thickness becomes closer to the edge, and the inclination itself becomes smaller. Along with this, the three-dimensional deformation metal flow at the plate edge can significantly reduce the edge drop.

[0025]

Example 1 Pickling SPHC having a thickness of 3.0 mm under various conditions shown in Table 1 by a cold rolling line as shown in FIG.
A thin steel plate (note rim material not trimmed during pickling) was rolled.

The edger is a constant pressure rolling system which performs edging in 3 passes, and the edger roll is 200φ × 50 L
(mm), the input / output side presser roll is 300φ x 2050 L (mm),
The center presser roll has a specification of 400φ x 250 L (mm). In the edger, the edging was performed with the target strip width after cold rolling being 1000 mm.

The tandem rolling mill has 5 stands, No. 1 to 3
The stand is a pair cross rolling mill, and the No. 4 to 5 stands are ordinary 4 Hi rolling mills. The rolling speed at the exit side of No. 5 stand was set to 1000 mpm. Work stand has 5 stands and 500
φ × 2000 L (mm).

The rolling reduction in the tandem rolling mill train was 30% for No. 1 and 2 stands and 25 for No. 3 and 4 stands in each case.
%, No. 5 stand is 10%.

The profile of the steel sheet edge after rolling is shown in FIG.
Shown in. In the figure, ~ corresponds to the case ~ in Table 1.

Cases 1 to 3 in Table 1 are examples of the present invention. In the case, first, edging was performed so that the total width on both sides was reduced by 6 mm from the strip width measured by the strip width meter, and then cold rolling was performed using a tandem rolling mill. Based on the measurement value of the plate thickness gauge on the output side of the tandem rolling mill, the cross angle (Fig. 2
Θ) was determined.

Roll cross angle of No. 1 to 3 stands (θ)
Is as shown in Table 1. As shown in FIG. 6, the edge drop is almost eliminated in the case.

The case is the same as the case in that an edger and a roll cross rolling mill are used, but since the amount of edging is small, a slight edge drop occurs. The case is basically the same as the case, but because the edging amount was as large as 17 mm, the edge became thicker even after cold rolling, resulting in a so-called dogbone shape. Although the effect of the method of the present invention is remarkable, such a shape is not preferable as a general product.

Cases ~ are comparative examples. The case has an edging amount of 6 mm, which is the same as the case.
However, the subsequent cold rolling was not roll cross rolling but ordinary parallel roll rolling. The case was roll-cross rolled in cold rolling, but was not edged by an edger before cold rolling. The case is an example in which normal parallel roll rolling is performed without performing edging or roll cross rolling. As shown in FIG. 6, not only in the case but also in the plate end of the steel sheet after cold rolling, a large edge drop appears.

[0034]

[Table 1]

[0035]

According to the method of the present invention, a metal plate with a small edge drop can be manufactured relatively easily. This metal plate has a small plate crown due to the effect of roll cross rolling, has a uniform cross-sectional shape, and has a high plate thickness accuracy. Although the rolling of cold-rolled steel sheet of low carbon steel was described in the examples, it goes without saying that the method of the present invention can be applied to the production of cold-rolled steel sheet of stainless steel or non-ferrous metal.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a cold rolling line for carrying out the method of the present invention.

FIG. 2 is a diagram illustrating roll cross rolling, in which (a) is a plan view and (b) is a side view.

FIG. 3 is a diagram showing a conventional trapezoidal roll rolling method for preventing edge drop.

FIG. 4 is a view showing an edger provided with a horizontal pressing roll and an edging vertical roll.

FIG. 5 is a schematic diagram of elastic deformation of a roll for explaining the principle of edge drop generation.

FIG. 6 is a view showing a profile of a plate end portion showing an edge drop of the cold rolled steel plate manufactured in the example.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kanji Hayashi, 4-6-22 Kannon Shinmachi, Nishi-ku, Hiroshima-shi, Hiroshima Prefecture Mitsubishi Heavy Industries, Ltd. Hiroshima Works (72) Kazuo Morimoto 4-chome, Kannon-shinmachi, Nishi-ku, Hiroshima Prefecture 6-22 No. 22 Hiroshima Research Laboratory, Mitsubishi Heavy Industries, Ltd.

Claims (1)

[Claims] 1. A tandem rolling mill in which a metal plate before entering a row of tandem rolling mills is pressed down in a width direction by an edger to form a plate-shaped end portion into a dogbone shape, and then at least the most upstream one stand is a roll cross rolling mill. A method for manufacturing a metal plate having a small edge drop, which comprises cold rolling in rows.