Metal deforming – Process – 'rolling'
Patent
1995-01-31
1997-06-10
Larson, Lowell A.
Metal deforming
Process
'rolling'
72234, B21B 128
Patent
active
056365446
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a cold rolling method for a metal strip such as a steel strip, a stainless steel strip, and the like and a mill array and in particular to a cold rolling method in which cross rolling prevents torsion in the material, thereby producing a metal strip having excellent surface gloss, and a mill array to be used in the method.
BACKGROUND ART
Recently, increasing demands have been made with respect to the shape and thickness of rolled metal strips (hereinafter referred to as "rolled strip"). Consequently, in order to control a crown of the rolled strip, several methods have been adopted in which a metal strip (hereinafter referred to as "strip") is rolled by upper and lower work rolls which cross in a plane parallel to the strip (hereinafter referred to as "work cross rolling") or is rolled by a pair of work roll and backup roll which cross in the plane (hereinafter referred to as "pair-cross rolling"). These cross rolling methods have already been widely introduced in hot rolling since they exhibit excellent control ability. However, if they are applied to cold rolling which requires high dimensional accuracy, it is necessary to prevent the rolled strip from twisting. In order to respond to demands relating to a wide variety of strip, thicknesses, and widths, a cold rolling mill with a high level of control is required. Although the cross rolling method is excellent with respect to its control ability, it has not been satisfactorily used in cold rolling due to the problem of torsion.
The reason why torsion is caused in the rolled strip by the cross rolling will be explained below by referring to FIG. 4. FIG. 4(a) is an explanatory view illustrating a torsion in the rolled strip 4 when the strip 3 is rolled by a pair of upper and lower rolls 1 and 2 which are crossed in a plane parallel to the strip 3. The rolled strip 4 is pushed down at an edge side A and pushed up at an edge side B during rolling by virtue of the position of the work rolls 1 and 2. This causes torsion in the rolled strip 4.
FIG. 4(b) is an explanatory view illustrating a torsion in the rolled strip 4 when the strip 3 is rolled by cross rolling method. As shown in FIG. 4(b), the rolled strip 4 is subjected to a shearing force F.sub.1 in the strip width direction on the top side and to a shearing force F.sub.2 in the strip width direction on the bottom side due to the fact that rotary axes of the work rolls 1 and 2 are not perpendicular to a rolling direction X. This causes torsion in the rolled strip 4. These torsions occur in opposing directions to each other, but do not cancel each other out since the torsion caused by shearing forces is larger than the torsion caused by the geometry of the work rolls in cold rolling. Consequently, torsion remains; in the rolled strip 4.
In hot rolling, recrystallization takes place in the rolled strip immediately after rolling even if a shearing force which causes torsion acts on the rolled strip. Accordingly, if tension is applied to the rolled strip except at the top and bottom ends thereof and the rolled strip is formed to be virtually flat, residual stress which would cause torsion is disappear. Consequently, there is substantially no problem of torsion.
In cold rolling, there is no stress relief caused by the recrystallization immediately after rolling, and therefore torsion is caused in the rolled strip. In particular, in the case of products without annealing, there is a serious problem with respect to quality, if torsion remains in the rolled strip. Also, the rolled material exhibiting torsion caused a deterioration in strip-passing operations in a process line such as in a continuous annealing line and the like.
Japanese Patent Publication No. 59-41804 (1984) discloses a rolling line in which intersection angles of the upper and lower work rolls are set to be reversed alternately in the order of mills in a rolling line in which cross mills are arranged in tandem. Also, Japanese Patent Public Disclosure No. 59-144503 (1984) discloses a rolling line whic
REFERENCES:
patent: 4385512 (1983-05-01), Matsumoto et al.
patent: 4453393 (1984-06-01), Hino et al.
patent: 4697320 (1987-10-01), Ishihara et al.
patent: 4727741 (1988-03-01), Ushifusa et al.
patent: 4885042 (1989-12-01), Kenmochi et al.
patent: 5291770 (1994-03-01), Koujin et al.
Furumoto Hideaki
Hamada Ryuji
Hashimoto Shoichi
Hori Kiyotaka
Horie Kazuhiko
Larson Lowell A.
Mitsubishi Jukogyo Kabushiki Kaisha
Schoeffler Thomas C.
Sumitomo Metal Industries Ltd.
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