JPS62289302A - Method for leveling edge drop of metallic strip - Google Patents

Abstract

PURPOSE:To prevent the generation of an edge drop in a metallic strip formed by rolling by slightly trimming the part near the edges of the metallic strip, then applying the prescribed plastic elongation corresponding to the edge drop quantity after the trimming thereto by bending and pulling. CONSTITUTION:The edges of the thin metallic strip are slightly trimmed so that the range of the remaining edge drop is decreased to the same range of the edge generated when the bending tension is applied thereto at the time of producing the thin metallic strip having <= 3mm thickness by hot rolling or cold rolling. The edge drop after the trimming is thereby uniformly leveled with the edge up by the bending and pulling. Since the trimming quantity is small, the yield is improved.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method for correcting edge drops in a metal strip produced by rolling by bending and tensioning.

(Prior Art) There is non-uniformity in the thickness distribution in the width direction of a metal strip manufactured by rolling, and the thickness tends to decrease rapidly especially near the edge around 10 to 50 III from the edge.

Such a rapid decrease in the thickness of the edge portion is called an edge drop, and the reduced portion is called an edge drop portion. Development of rolling technology continues to improve this edge drop.

On the other hand, as a method for improving edge drop, which is different from rolling, the present inventors have found that applying tension to a metal strip and passing it through a tension leveler to give a large plastic elongation by bending and tension will reverse the edge drop in the vicinity of the edge. discovered that an edge-up phenomenon occurs, in which the plate thickness near the edge is relatively thicker than other parts, and disclosed an edge drop correction method applying this phenomenon as JP-A-59-4924. .

The characteristic of this phenomenon is that the amount of edge-up increases as the elongation rate increases. Subsequent research by the present inventors revealed that the range of edge-up, that is, the distance in the width direction from the edge to the point where edge-up starts, increases as the roll pitch of the tension leveler used for bending and tensioning increases. It has been revealed that the size of the edge-up range within the radius pitch range is about 15 to 40 times the plate thickness.

(Problem to be Solved by the Invention) By the way, if the range of edge drop and the range of edge up match, the edge can be increased by applying a predetermined plastic elongation by bending and tension as shown in the above-mentioned patent publication. Drops can be straightened uniformly, but for thin sheets like cold-rolled W4 sheets, the range of edge-up is smaller and cannot be straightened uniformly (this is because the range of edge-drop due to rolling This is because the range of edge-up is less than about 40 times the thickness of the plate, and the thinner the plate thickness, the smaller the range is.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method that can correct edge drops even in thin plates by bending and tensioning.

Furthermore, another object of the present invention is to correct edge drop for different metal strips where the edge drop range and the edge amplifier range that occurs when bending and tension are applied are large, such as a plate thickness of 3 mm or less. The goal is to provide a method that allows for

(Means for Solving the Problems) In order to solve the above problems, the present invention involves trimming a small amount near the edge of a metal strip manufactured by rolling, and then trimming a predetermined amount corresponding to the edge drop amount after trimming. This is a method for straightening an edge drop of a metal band, which is characterized in that a plastic elongation of .

Here, the metal strip may be either a hot-rolled plate or a cold-rolled plate (and the plate thickness is also not limited, but the present invention is particularly effective when the thickness is about 3+ms or less.

(Function) As described above, according to the present invention, by trimming a small amount near the edge of the metal strip after rolling so that the remaining edge drop range is the same as the edge up range, the Edge drops can be uniformly corrected by bending and pulling the edges up. Furthermore, since the amount of trimming is small, the yield is also improved.

The amount of trimming is not particularly limited and can be set as appropriate, but
In order to prevent a decrease in yield, it is necessary to reduce the amount as much as possible, and at the same time, it is necessary to make the amount sufficient to correct the edge drop by the amount of edge amplifier due to bending and tension processing. Furthermore, the specific aspects of trimming and bending/pulling are already well known to those skilled in the art, and will not be further discussed below in order to simplify the explanation.

Next, the present invention will be specifically explained by taking as an example an electromagnetic steel sheet to which the present invention is very effective.

Most electromagnetic steel sheets used for motors, transformers, etc. have a thickness of about 0.5s+m, but the thickness accuracy is extremely strict, and the thickness deviation in the width direction is 0.005+m (5 μm).
Some require the following: On the other hand, the edge drop due to cold rolling is the amount of edge drop (thickness deviation)
is usually about 0.04mm (40μ+s), and the edge drop range is nearly 401111, so in the end, about 40+am per side is trimmed and scrapped. For this reason, the yield is very low, which is a big problem.

Even if this edge drop (range 4 hm) is attempted to be corrected by an edge amplifier using bending and tension, the practical limit of the edge up range is about 40 times the plate thickness of 0.5 mm, that is, about 20+am.

This relationship is as shown in FIG. Here, Figure 1 shows the edge drop amount (represented by curve A) of a cold-rolled electric Mi steel sheet with a thickness of 0.50 mm, and the amount of edge drop when it is subjected to bending and tensile processing with an elongation of 6% and 16%. Change in plate thickness by adding edge amplifier amount (represented by songs!B and C, respectively)
This is a graph showing the distance from the edge.

As shown in Figure 1, the plate thickness distribution after straightening becomes distorted, and a uniform plate thickness distribution cannot be obtained.In addition, as shown by curve C in Figure 1, the edge drop of 0.04 mm is almost corrected. The elongation rate required for this is quite large at 16%, and the number of rolls and tension must be increased, which requires large-scale equipment.

On the other hand, even in the above case, if the edges of the cold-rolled electrical steel sheet are trimmed by 15III on one side according to the present invention, the remaining edge drop range will be 25mm. This relationship is as shown in Figure 2, and each side is
5m ■ After trimming (the change in plate thickness is indicated by a curve),
The range of Edge Drop is 25+m, which extends by 6
% bending and tensile processing, the thickness change becomes almost uniform as shown by curve E in the figure. According to the present invention, as shown in FIG.
It is almost uniformly corrected by edge-up in the range of -. In this way, if the edge drop range is slightly larger than the edge amplifier range, correction can be made sufficiently uniform for practical purposes, and the amount of trimming can be reduced, resulting in improved yield.

That is, according to the present invention, a uniform plate thickness can be obtained even if the conventional trimming amount of 40 m square on one side is reduced to 15 sn, and the yield is greatly improved.

In addition, since the remaining edge drop amount was reduced to 0.015 m5 (Isμs) by trimming 15 m5, the elongation rate for bending and tension processing only needs to be 6%, and the above-mentioned 1.
In the case of 6%, correction is possible with inexpensive equipment with a relatively small number of rolls and a tension ratio.

As already mentioned, the amount of trimming is not particularly limited in the present invention, but a general explanation of how to determine the amount of trimming is as follows.

First, equipment constraints (tension, number of leveler rolls, roll diameter, roll pitch, etc.) determine the edge amplifier range (15 to 40 times the plate thickness) and the upper limit of the edge-up amount for each plate thickness. Consider reducing the amount of pole trimming.

For this reason, it is preferable to allow a sheet thickness distribution in which edge drops remain to a degree that does not cause any practical problems, and to set this as the target value. There are four cases as shown below, including the case where no trimming is required. In the following, the range of edge drop is 11 steps and the amount of edge drop is e.

■12. If both e are small (E is smaller than the range of edge amplifier and e is smaller than the amount of edge amplifier), it can be corrected as is, and trimming is not necessary.

(2) When E is large and e is small, trim so that l is approximately within the range of the edge amplifier. However, if some residual amount is allowed, the amount of trimming can be reduced further.

■If l is small but e is large Trimming is performed so that e is approximately the amount of edge amplifier.

However, if some residual amount is allowed, the amount of trimming can be reduced further.

■1. If both e is large, trimming is performed so as to satisfy both the range l≦edge-up range and e≦edge-up amount.

However, if some residual amount is allowed, the amount of trimming can be reduced further.

Based on the above concept, determine the optimal amount of trimming according to equipment specifications, plate thickness, edge drop conditions, etc.

Regarding the amount of edge-up, it is possible to increase the thickness by passing the leveler multiple times, so there is no restriction on e when reversing or re-threading the plate.
It is only necessary to consider l.

(Effects of the Invention) As explained above, according to the present invention, edge drops can be uniformly corrected even in thin objects, and can be corrected by bending and tensioning with a small elongation rate. But it is advantageous.

[Brief explanation of drawings]

Figure 1 is a graph showing the edge drop correction status (changes in plate thickness distribution near the edge) by the conventional method; and Figure 2 is a graph showing the edge drop correction status (change in plate thickness distribution near the edge) by the present invention. ).

Claims (1)

[Claims] A method for correcting edge drops in a metal strip, which comprises trimming a part of the edge drop portion of the metal strip after rolling, and then subjecting the metal strip to bending and tension processing.