JPH079002A - Skin-pass rolling mill for steel strip - Google Patents

Abstract

PURPOSE:To control L-camber, C-camber to arbitrary values and to improve the quality of a steel strip by providing auxiliary rolls which can adjust their positions respectively in the height direction just before or just after the front stand of two continuous stands and just after the rear stand. CONSTITUTION:When the outlet side pass angle theta1 of the front stand is changed, for example, it is enlarged, the winding angles to the work rolls of the steel strip S change, are large to the upper roll, and small to the lower roll. Consequently, the compressed residual stress on the rear side expands and an upward camber is expanded. An outlet side pass angle theta2 of the rear stand 4 is adjusted to enable adjusting both suitable L-camber and C-camber. In this way, the skin pass L-camber and C-camber can be controlled to arbitrary values irrespective of the roughnesses of the work rolls and the quality of the steel strip is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temper rolling mill (skin pass mill) for temper rolling a steel strip.

[0002]

2. Description of the Related Art Generally, a thin steel sheet used as a material for a can is cold rolled and annealed, and then subjected to 1% for the purpose of preventing stretcher strain, imparting an appropriate plate surface roughness, and correcting the shape. It is finished by temper rolling that applies front and back reduction. As a rolling mill for temper rolling,
There are many four or six rolling mills (stands) connected in series.

The role of each stand is to give a predetermined elongation to the steel strip by using a work roll having a surface with dullness (fine irregularities) formed by shot processing in the former stand, and in the latter stand for polishing finish. It is common to use a work roll and adjust the reduction force to adjust the plate surface roughness required for the product. In temper rolling,
Compressive residual stress occurs in the surface layer of the steel sheet, but if the residual stresses on the front and back sides are not uniform, the steel sheet will undergo warpage in the rolling direction after temper rolling, that is, L warpage and widthwise warpage, that is, C warpage. There's a problem.

Therefore, an auxiliary roll having a small diameter is arranged on the exit side of the post-stage stand of the temper rolling mill so as to come into contact with the lower surface and the upper surface of the steel strip. It is proposed to control. FIG. 6 shows a configuration example of the temper rolling mill. 1 is a payoff reel, 2 is an entrance side bridle roll, 3 is a first stand, 4 is a quadruple temper rolling mill of the second stand, 5 is an anti-crimping roll, 6 is an anti-corrugating roll, and 7 is an exit bridle. Rolls, 8 are tension reels, and S is a steel strip.

Steel strip S rewound by pay-off reel 1
Is subjected to temper rolling from the entry side bridle roll 2 through the first stand temper rolling mill 3 and the second stand temper rolling mill 4, and by the two auxiliary rolls of the anti-crimping roll 5 and the anti-corrugate roll 6. After the warp is corrected,
It is wound on the tension reel 8 via the exit side bridle roll 7.

The position of each of the two auxiliary rolls for correcting the warp can be adjusted in the height direction. Among these, the anti-crimping roll 5 contacts the lower surface of the steel strip S and pushes up the steel strip S from below. Thereby, the contact length between the work roll of the rolling mill 4 and the steel strip S is increased to correct the C warp, and the anti-corrugation roll 6 comes into contact with the upper surface of the steel strip S and forms a pair with the anti-crimping roll 5. It functions as a leveler and mainly acts to correct L-warp.

According to Japanese Patent Publication No. 61-9882, the anti-corrugate roll 6 is lowered and raised according to the speed of the steel strip to increase or decrease the pass angle of the steel strip S with respect to the anti-corrugate roll 6, whereby L warpage is caused. It has been proposed to control the correction effect of
According to the gazette, it is proposed that the height of the anti-crimping roll 5 is adjusted by the adjustment amount calculated in relation to the plate thickness of the steel strip S to control the C warping correction effect.

[0008]

However, in any of these warp straightening methods, the warp straightening is performed by adjusting the height of a small-diameter auxiliary roll provided on the exit side of the temper rolling mill 4 of the latter stage stand. Therefore, the angle θ ₂ formed by the steel strip S emerging from the post stand 4 of the temper rolling mill with the horizontal plane (hereinafter referred to as the post stand exit path angle) is changed.

Therefore, the inventors of the present invention have variously changed the trailing edge stand exit side pass angle θ ₂ by using the conventional temper rolling mill as shown in FIG. The L warpage was measured. The result is shown in FIG. 7. The horizontal axis is the rear stand exit side pass angle θ ₂ , the vertical axis is the amount of warp,
The straight line L is the amount of L warp when the rear stand exit side pass angle θ ₂ is changed, and the straight lines C ₁ , C ₂ , C ₃ are the C warp amounts when the rear stand exit side pass angle θ ₂ is changed. , C ₁ indicates a positive C warp on the entrance side of the latter stage stand, C ₂ indicates a 0 warp, and C ₃ indicates a negative warp.

That is, when the trailing stand exit side pass angle θ ₂ is changed, the C warp and the L warp are changed,
One cannot be changed independently. Further, since the straight line L has a larger gradient than the straight lines C ₁ , C ₂ , and C ₃ , when the rear stage stand-out side pass angle θ ₂ is changed, the L warp has a larger change. Also, when the C warp on the entrance side of the rear stand is positive, if the pass angle θ ₂ on the exit side of the rear stand is selected so that the point P ₁ on the straight line C ₁ is tried to make the C warp on the exit side zero, the L warp Becomes P ₂ and cannot be set to 0. Conversely, when C warping in subsequent stand entry side is negative, selecting a subsequent stand delivery-path angle theta ₂ so as to be point P ₃ from the top linear C ₃ trying to C warpage outgoing side 0, L warp is a P _4, it can not be zero. L-warp can be corrected by anti-corrugated roll 6, and
Although it can be corrected to some extent by a tension leveler or the like in the subsequent process, C warpage is difficult to correct, so
The trailing stand exit side pass angle θ ₂ is usually determined by prioritizing the correction of the C warp, and the correction of the L warp must be postponed.

The present invention solves such problems and provides a temper rolling mill capable of correcting both C warp and L warp on the rear stand exit side by eliminating the fluctuation of C warp on the rear stand entrance side. The purpose is to

[0012]

In order to achieve the above object, the inventors of the present invention repeated various experiments, and as a result, the difference in residual stress between the front and back surfaces of the steel strip caused by the use of the dull roll in the front stand was found to be the entrance side of the rear stand. It has been found that it is greatly related to the C warp fluctuation in the. The surface roughness of the dull roll is generally as large as 0.8 to 2.0 μm in Ra, and it is extremely difficult to make it equal for the upper and lower rolls in reality. C caused by this slight difference in roughness
We have completed a temper rolling mill that can prevent warpage fluctuations by changing the pass angle on the inlet side or outlet side of the former stage stand and enable effective control of the amount of warpage by the pass angle θ ₂ on the outlet side of the latter stage stand.

That is, the present invention is a temper rolling mill for steel strips having two or more stands, which are positioned in the height direction immediately before or immediately after the front stand of two consecutive stands and immediately after the latter stand. It is characterized by having an adjustable auxiliary roll.

[0014]

[Operation] To the conventional temper rolling mill as shown in Fig. 6, a mechanism for changing the pass angle θ ₁ on the exit side of the front stand was added, and the C warpage of the steel strip S was measured on the entrance side of the rear stand. The results are shown in Fig. 2. The horizontal axis is the front stand exit side pass angle θ ₁ , the vertical axis is the C warp amount, and the straight line R _{1 is}
R ₂ and R ₃ are the measurement results of the surface roughness of the work roll in the front stand, R ₁ is the upper roll roughness <lower roll roughness, R ₂ is the upper roll roughness = lower roll roughness, R ₃ represents the case where the roughness of the upper roll> the roughness of the lower roll.

When the front stand exit side pass angle θ ₁ is changed, for example, when it is increased, the wrap angle of the steel strip S around the work roll changes, which is large for the upper roll and small for the lower roll. Therefore, the steel strip S
The rolling force per unit area is larger on the back surface than on the front surface (top surface), and the compressive residual stress on the back surface is large, and as a result, the warp can be increased upward.

For example, when the roughness of the upper roll is greater than the roughness of the lower roll, since the point P ₅ on the straight line R ₃ remains as it is, the negative C
Warpage occurs, but front stage stand exit side pass angle θ ₁
It is possible to eliminate the C warp by shifting to point P ₆ by increasing. That is, even if the surface roughness of the upper roll is different from that of the lower roll, by adjusting the front stand exit side pass angle θ ₁ , it becomes possible to make the C warp on the rear stand entrance side constant, and further, the rear stand. By adjusting the exit side pass angle θ ₂ , it is possible to properly adjust both the L warp and the C warp.

Regarding the front stand, it is sufficient to change the winding angle of the steel strip S around the work roll. Therefore, instead of adjusting the pass angle θ ₁ on the exit side,
The same effect can be obtained even if it is done on the entry side.

[0018]

FIG. 1 shows an embodiment of the temper rolling mill of the present invention. In contrast to the conventional temper rolling mill shown in FIG. 6, a first pass angle roll 9 is provided on the exit side of the preceding stand as an auxiliary roll whose position can be adjusted in the height direction for adjusting the pass angle θ ₁ . In addition, the second pass angle roll 10 is also provided on the exit side of the rear stage as an auxiliary roll whose position can be adjusted in the height direction for adjusting the pass angle θ ₂ , which is shown in FIG. The operation and effect are the same as those described as the ping roll 5. The anti-corrugate roll 6 is omitted because it is not necessary. Other than that, there is no structural difference.

The temper rolling using the conventional temper rolling mill shown in FIG. 6 and the temper rolling mill according to the present invention shown in FIG. 1 was carried out, and the respective steel strips were cut out and the results of L warping and C warping were measured. As shown in FIG. It is understood that (a) shows the conventional method and (b) shows the present example, and the range of the L warp that cannot be adjusted by the conventional method is significantly narrowed.

The values of the L warp and the C warp can be measured by cutting out the steel strip after rolling, but can also be measured online in the rolling mill by a shape meter (profile meter). In FIG. 4, online profile meters 11 and 12 are installed on the output side of the first pass angle roll 9 and the second pass angle roll 10, and the heights of the respective pass angle rolls 9 and 10 are adjusted by the calculators 13 and 14. FIG. 5 shows an example of the configuration in which the profile meter 11 is installed only on the output side of the rear stand, and the heights of the pass angle rolls 9 and 10 are individually adjusted from one computing unit 13. It is a structural example. As described above, the first pass angle roll 9
Since the effect does not change whether it is installed on the entrance side or the exit side of the front stand, in the example of FIG. 5, the front stand is installed on the entrance side because the space between stands is small.

Although the temper rolling mill having two stands has been described above, when there are two or more stands, the present invention may be applied to two consecutive stands. Further, the temper rolling mill is not an independent processing facility, and the present invention can be applied without any limitation even in the form of an inline skin pass mill incorporated in a continuous processing line for steel strips. Needless to say.

[0022]

According to the present invention, the L warp and C warp after temper rolling can be controlled to any values regardless of the roughness of the work roll, and the quality of the steel strip is significantly improved. It has the excellent effect of

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a graph showing an example of adjustment in the embodiment of the present invention.

FIG. 3 is a graph showing distributions of warpage amounts according to a conventional method and the present invention.

FIG. 4 is a configuration diagram showing another embodiment of the present invention.

FIG. 5 is a configuration diagram showing still another embodiment of the present invention.

FIG. 6 is a configuration diagram showing a conventional technique.

FIG. 7 is a graph showing an example of adjustment in the conventional technique.

[Explanation of symbols]

 1 Payoff reel 2 Entry side bridle roll 3 1st stand 4 2nd stand 5 Anti-crimping roll 6 Anti-corrugated roll 7 Exit side bridle roll 8 Tension reel 9 1st pass angle roll 10 2nd pass angle roll 11, 12 Profil meter 13, 14 arithmetic unit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinichiro Muto 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Steel Co., Ltd. Chiba Steel Works (72) Inventor Kiyoshi Tachibana, Kawasaki-cho, Chuo-ku, Chiba Kawasaki Steel Co., Ltd.Chiba Works

Claims (1)

[Claims] 1. A steel strip temper rolling mill having two or more stands, which is located immediately before or after the preceding stand (3) of two consecutive stands (3, 4) and the following stand (4). A temper rolling mill for steel strips, characterized in that auxiliary rolls (9, 10) each of which can be adjusted in the height direction are provided immediately after that.