JP2519103B2 - Cold rolling method for electrical steel sheet - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for cold rolling an electromagnetic steel sheet by a rolling mill having a one-taper up / down work roll that can be shifted in the roll axial direction.

[Prior Art] Magnetic steel sheets are required to have strict plate thickness accuracy over the entire width.
Usually, in rolling of this type of steel sheet, edge drop occurs in which the sheet thickness rapidly decreases at the edge of the sheet, so this section must be trimmed into a product, leading to a decrease in yield. .

To deal with such a problem, conventionally, as shown in FIG. 1, each side of the upper and lower work rolls (1a) (1b) has a tapered taper portion (2) which is point-symmetrical between the upper and lower work rolls. ,
By using a rolling machine capable of shifting the upper and lower work rolls (1a) (1b) in the roll axis direction, the plate end portion of the steel plate (3) is positioned in the upper tapered taper part (2) and rolled, thereby rolling the plate. There is known a technique for controlling the profile of the cross section and reducing the edge drop.

[Problems to be solved by the invention]

However, when such rolling is applied to the rolling of electrical steel sheets, the electrical steel sheets have different hardness and brittleness due to Si and Al in their components. There is a problem that cracks occur in some parts. In particular,
This tendency is remarkable in high [Si + Al] electrical steel sheets.

The present invention has been made in view of such conventional problems, and it is possible to roll an electromagnetic steel sheet so as to obtain a good plate cross-sectional profile without causing breakage of the plate or cracking of the plate end portion. It is intended to provide a method.

Therefore, in the present invention, a linear taper portion is formed on each side of the body of the upper and lower work rolls so as to be point-symmetric between the upper and lower work rolls, and the upper and lower work rolls can be moved in the roll axial direction. In the method of cold rolling (including warm rolling. The same applies below) an electromagnetic steel sheet using the rolling mill described above,
According to the [Si + Al] amount of the electromagnetic steel sheet to be rolled, the angle of the tapered taper portion and the overlapping length of the tapered taper portion and the plate end portion in the plate width direction are adjusted.

 Hereinafter, the details of the present invention will be described.

The edge drop of the steel plate is mainly caused by the metal flow in the width direction of the plate end portion due to the roll deformation, and by rolling with a work roll having a taper as shown in FIG. The contact pressure between the roller and the end of the roll is reduced, the metal flow in the width direction is suppressed, and the edge drop can be reduced.

However, the electrical steel sheet has a property of being hard and brittle as compared with general steel, and this property depends on the amounts of Si and Al in its components, and becomes harder and brittle as the amount of these elements increases. When such a steel plate is rolled by the work taper with one taper as described above, if the taper angle is too large or the overlapping length of the taper part and the plate end part is too large, plate breakage or plate cracking may occur. Will occur. We have
Various electrical steel sheets with different amounts of [Si + Al] were rolled by changing the angle of the tapered taper portion and the overlapping length of the taper portion and the plate edge, and examined the occurrence of plate breakage and plate edge cracking. . As a result, they have found that by appropriately selecting the taper angle and the overlapping length of the taper portion and the plate end portion according to the [Si + Al] amount, it is possible to appropriately prevent the plate breakage and the plate end cracking.

FIG. 2 shows that a steel sheet of [Si + Al] ≦ 1 wt% is rolled by changing the taper angle θ of the taper taper portion (2) and the overlapping length WRδ of the taper portion and the plate end as shown in FIG. In this case, we investigated the occurrence of plate breakage, Good rolling could be realized in the area satisfying the conditions. Then, as a result of conducting a similar investigation by changing the components of the electromagnetic steel sheet, the following results were obtained. That is, Then, it was found that the range of k at which good rolling can be performed without causing plate breakage and cracking at the plate edge is as follows.

[Si + Al] ≤ 1.0% 0.6 ≤ k ≤ 3.0 1.0% <[Si + Al] ≤ 2.2% 0.6 ≤ k ≤ 2.6 2.2% <[Si + Al] ≤ 3.3% 0.6 ≤ k ≤ 2.0 3.3% <[Si + Al ] 0.6 ≦ k ≦ 1.0 FIG. 3 shows the range in which such good rolling is possible. When the k value is small, the effect of the plate thickness profile control using the single taper roll is small, and when the k value is less than 0.6, the plate thickness range (plate cross section profile range and longitudinal plate thickness range) is 2%. It will be difficult to fit within. Therefore, as described above, k
The lower limit of the value is preferably 0.6.

〔Example〕

Steel plates with the components shown in Table 1 (plate thickness 2.0 mm, plate width 1136 mm)
With a 4-man stand tandem mill equipped with a # 1 to # 3 stand and a single taper work roll as shown in FIG.
Cold or warm rolling to a target thickness of 0.5 mm was carried out, and the sheet cross-sectional profile and edge drop occurrence of the cold-rolled steel sheet obtained were investigated. The results are shown in Tables 2 to 5 together with the rolling conditions by the tapered portions of the # 1 to # 3 stands.

In Tables 2 to 5, Example b is an example of the present invention, Examples a and c are Comparative Examples, and FIGS. 5 to 8 show the plate cross-sectional profiles of rolled steel sheets. As can be seen from these, by rolling any of the steel plates within the range of the above-mentioned k value, it is possible to roll into a good shape without causing plate breakage.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a rolling situation by a work roll having a single taper portion. FIG. 2 shows the occurrence of plate breakage when electromagnetic steel sheets of [Si + Al] ≦ 1 wt% are rolled by changing θ and WRδ of the roll taper portion. FIG. 3 is an explanatory diagram showing θ and WRδ of the roll taper portion. FIG. 4 shows the proper range of θ and WRδ according to the [Si + Al] amount. FIG. 5 to FIG. 8 show sheet profile after rolling in the example.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shoji Minokawa Marunouchi 1-2-2 Marunouchi, Chiyoda-ku, Tokyo Japan Steel Pipe Co., Ltd. (72) Shunichi Tanabe 1-21-2 Marunouchi, Chiyoda-ku, Tokyo Nippon Steel Pipe Incorporated (56) Reference JP-A 61-289902 (JP, A) JP-A 1-166803 (JP, A)

Claims (1)

(57) [Claims] 1. A linear tapered taper portion is formed on each side of the body portion of the upper and lower work rolls so as to be point-symmetric between the upper and lower work rolls, and the upper and lower work rolls are movable in the roll axial direction. In the method of cold rolling an electromagnetic steel sheet using a rolling mill, according to the [Si + Al] amount of the electromagnetic steel sheet to be rolled, the angle of the taper taper portion and the overlapping length in the width direction of the taper taper portion and the plate end portion A method for cold rolling an electrical steel sheet, characterized in that the thickness is adjusted.