JPH08206716A - Method for cold-rolling steel strip - Google Patents

Abstract

PURPOSE: To obtain a cold rolled steel strip improved in the accuracy of thickness in the width direction and minimized in the loss in yield. CONSTITUTION: At the time of cold-rolling the steel strip by arranging work rolls with one tapered side at least in the 1st stand of a tandem mill, the work rolls whose inclined angle tanθ of the tapered part is >=1/600 are used and the shoulder part of taper of the work roll is set in the range of 50-90mm from the edge part of a material to be rolled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cold rolling a steel strip (cold rolled sheet, electromagnetic steel sheet, etc.), which prevents deterioration of a sheet crown during rolling and provides a flat product sheet profile in the sheet width direction. It's about to get.

[0002]

2. Description of the Related Art An abrupt change in plate thickness in the width direction of a rolled material is what is called an edge drop, and it has a great influence on the quality of rolled products, so it is desired to be as small as possible.

As a conventional technique for reducing such an edge drop, for example, a tandem type rolling mill having three or more stands as disclosed in Japanese Patent Laid-Open No. 61-20601 is used, and in the frontmost stand, Roll so that the taper shoulder of the work taper with one taper is 50 mm or more inside the width edge of the strip, and then, in the intermediate stand, at least in the center of the barrel within 100 mm of the width of the strip. An edge drop reduction method is known in which rolling is performed with a roll having a flat portion that is narrow or wider than the width of the strip, and rolling is performed with a flat roll over the entire length of the barrel in the final stand. .

[0004]

However, the above conventional method has the following disadvantages.
That is, when the taper portion of the work roll with one taper has a small inclination angle, even if the taper shoulder portion of the first stand is rolled 50 mm or more inward from the plate edge of the material to be rolled (base plate), the product is rolled. While the effect of improving the edge drop is extremely small, when the inclination angle of the taper portion is large, the taper shoulder portion of the first stand is set closer to the center in the width direction of the material to be rolled, The shape of the plate on the exit side of the 1 stand was remarkably stretched in the middle, and there was a problem that troubles occurred on the threaded plate.

An object of the present invention is to propose a novel method capable of stably obtaining a steel strip having good strip thickness accuracy in the strip width direction without causing the above-mentioned troubles on the strip running. Where it is.

[0006]

According to the present invention, when a work roll having a single taper is arranged on at least the first stand of a tandem mill to perform cold rolling of a steel strip, the inclination angle tan θ of the taper portion is 1 A cold rolling method for a steel strip, characterized in that a work roll having a thickness of / 600 or more is used, and a taper shoulder portion of the work roll is roll-shifted within a range of 50 to 90 mm from a width end of a material to be rolled. Here, θ in the inclination angle tan θ of the taper portion is an angle formed by the roll cylinder of the work roll and the taper portion as shown in FIG. Here, the taper shoulder is the taper starting point of the work roll (corresponding to L in FIG. 1).

[0007]

The inventors conducted detailed experiments on the degree of taper of the work taper with a single taper and the positional relationship between the steel plate and the taper shoulder during rolling from lab tests and actual machine tests. As a result, the edge drop improvement effect of the product sheet (h _T −h _F , where h _T : thickness deviation between the sheet edge and the sheet center during taper roll rolling, h _F : sheet edge and sheet center during flat roll rolling 2), as shown in FIG. 2, becomes large when the inclination angle tan θ of the tapered portion is ≧ 1/600, and as shown in FIGS. 3 and 4,
When the taper shoulder of such a roll is set within 90 mm from the width end of the plate, the steepness of the plate becomes 3% or less, and it has become clear that there is no particular problem in passing the plate.

Therefore, in the present invention, a work roll with a single taper having a taper portion inclination angle tan θ of ≧ 1/600 is used for the first stand, and 50 mm to 90 mm from the width end of the material to be rolled.
It shifts within the range of mm, which makes it possible to obtain a product steel strip having a small deviation in plate thickness in the width direction. However, if tan θ is excessively large, medium elongation becomes excessively large. Therefore, the upper limit is preferably set to 1/200 or less.

[0009]

[Example] Hot-rolled steel strip with a base plate thickness of 2.5 mm (steel type: J
IS spcc) is used for finishing thickness 0.50mm, width
Cold rolling was performed to 1000 mm, and the quality status of the obtained product plate (plate thickness accuracy in the plate width direction) was investigated. The tandem mill (5 stands) in the cold rolling is a work roll with one taper on the 1st stand to the 3rd stand. The position is 80 for the first stand
mm, 2nd stand is 20mm, 3rd stand is 10m
m) was used with flat work rolls arranged on the fourth and fifth stands. For comparison, the work rolls with one-sided taper whose inclination angle is outside the scope of the invention are used for the first to third stands (the inclination angle is the first
Both the work rolls from the stand to the third stand are tan
θ = 1/800, shoulder position is 80 mm for the first stand, second position
A stand with a 30 mm stand and a third stand with a 15 mm stand) was also used, and the fourth and fifth stands with flat work rolls were also used.

For the cold-rolled steel strip after rolling, the thickness deviation in the width direction (difference between the center in the width direction and the point 1 located 10 mm inside from the edge in the width direction) was measured, and the average value (n = 36) ) Was asked. As a result, the average value of the plate thickness deviation was 10.7 μm when rolled according to the comparative method, but was 4.5 μm when cold rolled according to the present invention, and the plate thickness accuracy in the width direction was It was confirmed that the improvement was remarkable and that it was effective in improving the yield.

[0011]

As described above, according to the present invention, it is possible to improve the plate thickness accuracy in the plate width direction, without causing troubles on the threaded plate, and with a low yield loss. Can be obtained.

[Brief description of drawings]

FIG. 1 is a view showing an arrangement state of a work roll having a single taper and a material to be rolled.

FIG. 2 is a graph showing the relationship between the inclination angle of the tapered portion and the effect of improving the plate thickness deviation.

FIG. 3 is a graph showing a relationship between a taper shoulder portion and a steepness of middle elongation of a plate.

FIG. 4 is a graph showing the relationship between the steepness of middle elongation of the plate and the fracture occurrence rate.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication location B21B 37/00 BBP 37/42 8315-4E B21B 37/00 116 T (72) Inventor Satoshi Ono Okayama Mizushima Kawasaki-dori, 1-chome, Kurashiki-shi, prefecture (No.) Kawashima Steel Co., Ltd., Mizushima Steel Works (72) Inventor Toshinori Nakanishi 1-chome, Mizushima-Kawasaki-dori, Kurashiki-shi, Okayama (No.) Mizushima Steel, Ltd. (No. 72) Inventor Toshiki Ebisa 1-chome, Mizushima Kawasaki-dori, Kurashiki City, Okayama Prefecture (no street number) Kawasaki Steel Works Mizushima Works

Claims (1)

[Claims] 1. A cold roll of a steel strip is provided by arranging a work roll with a taper on at least the first stand of a tandem mill, and a work roll having a taper angle tan θ of 1/600 or more is used. A method for cold rolling a steel strip, characterized in that the taper shoulder of the work roll is within a range of 50 to 90 mm from the plate edge of the material to be rolled.