JPH0796302A - Rolling method for steel strip - Google Patents

Abstract

PURPOSE:To provide a method for rolling uniformly lubrication state in the inside of upper and lower work rolls at the time of cold rolling. CONSTITUTION:In this method, rolling is executed by adjusting the approach angle of a strip to the pass line of the work roll within + or -0.01rad. In this way, the abrasion loss of the upper and lower work rolls is equalized and the life is prolonged. There is such an advantage as glass difference due to lubrication is not generated between the surface and back faces of strip.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for rolling a steel strip, and more particularly to a method in which a pair of upper and lower work rolls in a tandem cold strip mill are uniformly lubricated in the vertical direction.

[0002]

2. Description of the Related Art As shown in FIG. 2, a tandem cold strip mill has a water draining roll 4 and a tension meter roll 5 between mill stands 3 and 3 each comprising upper and lower backup rolls 1 and 1 and work rolls 2 and 2. Is arranged. In such a tandem cold strip mill, in order to detect the tension between the stands, the tension meter roll 5 is arranged above the horizontal line with respect to the work roll 2. At this time, the strip entry angle enters the work roll 2 from above, and the upper and lower work rolls 2 and 2 are not in the same lubrication state. Generally, when the strip enters from above, the lubrication of the upper work roll 2 is good and the lubrication of the lower work roll 2 is poor.

When rolling is continued under such a condition, the upper work roll 2 with good lubrication has a large margin of decrease in roll roughness due to wear, and the lower work roll 2 with poor lubrication has a lower margin of roll roughness due to wear. There will be few. For this reason, there is a difference in the current consumption of the work roll drive motor during rolling, making it difficult to perform rolling, and the oil pit formation state on the steel plate on the delivery side of the rolling mill is different, resulting in a difference in gloss between the front and back surfaces. This causes operational and quality problems. Furthermore,
Since the upper and lower work rolls 2, 2 have different roll roughness reduction margins, there is a waste of exchanging a pair of upper and lower work rolls in accordance with the exchange of the work roll 2 on the side where the roll roughness reduction margin is large. .

Further, in a single drive type rolling mill in which the upper and lower work rolls are individually driven, when rolling is performed by using load balance control with a good work roll driving motor, the upper work is in a good lubricating state. The peripheral speed of the roll 2 becomes faster than the peripheral speed of the lower work roll 2, and as a result of the different peripheral speed rolling, the upper work roll 2 with better lubricity has a larger margin of decrease in roughness due to wear. In such a case, upper work roll 2 with good lubrication
Shows a large decrease in roll roughness due to wear, and the lower work roll 2 with poor lubrication has a small decrease in roll roughness due to wear. For this reason, there is a difference in the current consumption of the work roll drive motor during rolling, making it difficult to perform rolling, and the oil pit formation state on the steel plate on the delivery side of the rolling mill is different, resulting in a difference in gloss between the front and back surfaces. This causes operational and quality problems. Furthermore, the upper and lower work rolls 2,
Since the roll roughness lowering margin of No. 2 is different, there is a waste of replacing the pair of upper and lower work rolls in accordance with the replacement of the work roll 2 on the side where the roll roughness lowering margin is large.

As a means for improving such a lubricating state,
As disclosed in Japanese Patent Publication No. 4-45243, there is a method of controlling the flow rate of rolling oil supplied to the upper and lower work rolls 2, 2. However, in a general tandem cold strip mill, it is confirmed that this control method is insufficient because the actual amount of rolling oil is being supplied. Further, if the amount of rolling oil supplied is reduced, secondary damage such as heat scratches may occur.

[0006]

SUMMARY OF THE INVENTION As described above, according to the present invention, a difference in the amount of wear of the upper and lower work rolls caused by a difference in the lubrication state of the upper and lower work rolls caused by the difference in the up and down angles of the steel strips, or In order to solve the problems such as the difference in current consumption of the work roll drive motor during rolling, and the difference in gloss between the front and back surfaces of the steel plate on the delivery side of the rolling mill, we provide a method of rolling with the upper and lower work rolls in the same lubrication state. It was completed in order to do.

[0007]

Next, the gist of the present invention is, during cold rolling, a pass line between stands (perpendicular to a straight line connecting the centers of upper and lower work rolls and passing a point where the upper and lower work rolls kiss). Horizontal line; hereinafter referred to as pass line)
Characterized in that the tension meter roll is positioned at the same position as above, the draining roll arranged on the upstream side of the tension meter roll is positioned below the pass line, and rolling is performed with an entrance angle of the steel strip of ± 0.01 rad. Especially.

That is, paying attention to the fact that a minute difference in the approach angle of the strip has a large difference in the lubrication state of the upper and lower work rolls, it is not controlled by the amount of rolling oil to be supplied, etc., but by the geometrical arrangement. The invention by means of control will be explained in more detail with reference to the drawings.

In the present invention, as shown in FIG. 3, the tension meter rolls 5 between the mill stands 3 and 3 are arranged on the pass line for the upper and lower work rolls 2. At this time, to detect the tension between the stands,
The arrangement of the two rolls of the tension meter roll 5 is shown in FIG.
As shown in, the dummy roll 7 is arranged at a position lowered by 10 to 20 mm with respect to the tension detecting roll 6. Further, as shown in FIG. 3, the draining roll 4 is arranged at a position lower than the tension meter roll 5 by 30 to 60 mm. By changing the arrangement, it is possible to roll in a horizontal state with the tension between the stands being detectable and the approach angle to the upper and lower work rolls 2 being ± 0.01 rad. can do.

The approach angle is defined as the angle formed by the center line of the strip to be rolled and the pass line, with reference to the pass line determined by the arrangement of the upper and lower work rolls as shown in FIG.

Further, in order to cope with a change in diameter of the work rolls 2 and a change in diameter of the tension meter rolls, a pair of upper and lower work rolls are vertically moved by utilizing a wedge mechanism in the mill stand or a filler plate. How to change the arrangement and adjust the entry angle of the strip,
Shown in FIGS. Wedge mechanism 9 in the mill stand
In the rolling mill as shown in FIG. 5, the wedge mechanism 9 is used to adjust the pair of upper and lower work rolls by changing the arrangement in the vertical direction. Further, as a method of adjusting with the filler plate 10, as shown in FIG.
By changing the thickness of 0, it becomes a method of adjusting the upper and lower work rolls in a pair by vertically arranging them.

[0012]

EXAMPLES Next, examples of the present invention will be described. Thickness of 0.2-
When a material of 0.25 mm and a plate width of 700 to 900 mm is rolled, the total amount of material that can be rolled by a pair of work rolls is 670 tons, whereas the strip entry angle is 0 rad and the plate thickness is 0 rad. .2-0.25 mm, board width 700-
The total rolling amount of material that can be rolled by a pair of work rolls when rolling 900 mm material is 910 tons, which is about 1.4
The life extension effect was doubled. Further, the friction coefficient as an index showing the lubrication state is compared between the upper and lower work rolls.
When low-carbon aluminum-killed steel was rolled to a finishing plate thickness of 0.2 mm with the strip entry angle set to 0.033 rad, there was a large difference between the upper work roll friction coefficient of 0.025 and the lower work roll friction coefficient of 0.040. . However, when low-carbon aluminum killed steel was rolled to a finished plate thickness of 0.2 mm with the strip entry angle set to 0 rad, the upper work roll friction coefficient and the lower work roll friction coefficient were equal to 0.030.

[0013]

As described above, according to the present invention, rolling can be continued with the upper and lower work rolls of the rolling mill being in the same lubrication state. As a result, the upper and lower work rolls have the same roughness reduction margin, thus eliminating waste when replacing the work rolls, making the motor current consumption for driving the work rolls equal to the top and bottom, and making the top and bottom work rolls the same roughness Since the oil pits formed on the front and back surfaces of the strip on the delivery side of the rolling mill are also equalized, there are many advantages such as no difference in gloss between the front surface and the back surface.
In addition to this, since the lubrication state is adjusted by the advancing angle of the strip, there is an advantage that the waste of the rolling oil supplied to the work rolls can be omitted and the minimization thereof can be achieved.

[Brief description of drawings]

FIG. 1 is an explanatory view of an approach angle used in the present invention.

FIG. 2 is an explanatory diagram showing a conventional cold rolling method for a steel strip.

FIG. 3 is an explanatory view showing a cold rolling method of the present invention.

FIG. 4 is an explanatory view showing the arrangement of tension meter rolls of the present invention.

FIG. 5 is an explanatory view of moving the approach angle of the present invention up and down by a pair of upper and lower work rolls using a wedge mechanism.

FIG. 6 is an explanatory view of moving the entry angle of the present invention up and down in pairs with the upper and lower work rolls using a filler plate.

[Explanation of symbols]

 1 Backup Roll 2 Work Roll 3 Mill Stand 4 Draining Roll 5 Tension Meter Roll 6 Tension Detection Roll 7 Dummy Roll 8 Tension Detection Load Cell 9 Wedge Mechanism 10 Filler Plate 11 Rolling Down Device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shigeru Setoguchi 5-3 Tokai-cho, Tokai-shi, Aichi Nippon Steel Co., Ltd. Inside the Nagoya Works

Claims (2)

[Claims] 1. When cold rolling a steel strip, a tension meter roll is positioned at the same position as a pass line between stands, and a draining roll disposed upstream of the tension meter roll is positioned below the pass line. A method for rolling a steel strip, which comprises rolling the steel strip with an approach angle of ± 0.01 rad. 2. The method of rolling a steel strip according to claim 1, wherein a pair of upper and lower work rolls are moved up and down in order to make the approach angle of the steel strip ± 0.01 rad.