JPH06254602A - Method for preventing indentations of lower work roll in dry temper rolling mill - Google Patents

Abstract

PURPOSE:To improve safety and to prevent a surface defect from occurring by removing foreign matters on a backup roll before work rolls of a dry temper rolling mill are recombined, then, rolled down and clamped. CONSTITUTION:When the mill is rolled down, clamped and temper-rolled, the foreign matters 5 on the lower backup roll bitten into the contact between the lower work roll 2 and the lower backup roll 1 are embedded in the surface of the lower backup roll 1, then, whenever the backup roll 1 rotates one time, it gives indentations to the roll. Consequently, when the lower backup roll is rotated 180 degrees before the backup roll is rolled down and clamped, the foreign matters 5 on the lower backup roll 1 are dropped naturally by gravity. Therefore, no indentations are given to the lower work rolls 2. Even when foreign matters contain oil content and does not fall naturally by adhesive effect, a scraper blade 6 comes into contact with the whole width of the lower backup roll 1 on the inlet side of the roll 1 to remove the foreign matters through arm attachable/detachable scraper.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing lower work roll indentation flaws in dry temper rolling of cold-rolled steel sheet for surface treatment for tin plate and tin-free steel.

[0002]

2. Description of the Related Art Generally, in temper rolling of a tin plate, which is mainly composed of bright material, dry temper rolling is performed because it is necessary to obtain gloss. At the time of changing the work rolls of such a rolling mill, a new work roll is often inserted and a reduction tightening is performed. Immediately after the temper rolling operation is started, the lower work roll is often flawed. This is often caused by the following reasons. Foreign substances fall onto the lower backup roll during work roll reassembly. The foreign matter is embedded in the backup roll having a low surface hardness as the lower work roll and the lower backup roll contact and rotate. The indentation of foreign matter is transferred to the lower work roll every one rotation of the lower backup roll.

In the case of wet temper rolling, the rate of occurrence is extremely low because foreign matter is washed away by the tempering liquid sprayed on the steel sheet or roll. In contrast to this, it can be said that a characteristic defect occurrence tendency occurs when dry temper rolling is performed using a four or more rolling mill. FIG. 2 is a diagram for explaining the above. When the foreign matter 5 adheres to the lower backup roll 1 as shown in FIG. 2A when the work roll of the dry temper rolling mill including the backup rolls 1 and 4 and the work rolls 2 and 3 is replaced, as shown in FIG. When the backup roll 1 rotates as shown in FIG.
Occurs on the work roll 2. When the backup roll 1 further rotates, the indentation flaw 9 increases as shown in FIG. The indentation flaws 9 are transferred to the cold rolled steel plate 8 and impair the quality of the steel plate 8.

Once a foreign matter is embedded in the backup roll 1, the foreign matter rarely falls off spontaneously, and the same roll mark is generated again just by replacing the work roll. That is, it is necessary for the operator to remove this foreign matter. For this reason, the operator must enter the mill to remove the foreign matter, or pull out the lower backup roll from the inside of the mill to perform the foreign matter removal work.

[0005]

There is a safety problem in the work performed by the operator entering the inside of the mill, and when the lower backup roll is pulled out from the inside of the mill to clean the roll, downtime is required in the batch mill. The operating rate will decrease. Also, in the case of a temper rolling mill that is inlined in a continuous annealing line, temper rolling is stopped and only annealing can be performed until the maintenance work is completed, so the coil processed during the maintenance work It is necessary to perform temper rolling in a separate process.

The present invention solves the above-mentioned problems of safety and quality, the problem of lowering of operating rate, and the problem of deterioration of temper rolling ratio after temper rolling inlined in a continuous annealing line, thereby improving the The purpose is to provide a production technique for achieving productivity and high yield.

[0007]

As described above, according to the present invention, when the work rolls of the skin path mill for dry type temper rolling of the lower backup roll drive type are changed, the foreign matter dropped on the lower backup roll is started together with the start of the rolling operation. Focusing on preventing it from being embedded in the lower back roll, its technical means are as follows.

(1) After incorporating the new work roll, a sequence of rotating the lower backup roll by 180 degrees, that is, a half rotation is added to the work roll automatic reassembly prior to the rolling-down tightening work, and foreign matter is lowered by the action of gravity. I will let you fall. (2) If foreign matter has oil content, it may not be able to fall naturally by gravity due to its adhesive action. Therefore, it is possible to press and open before the screw tightening work and contact the entire width of the lower backup roll. The lower backup roll is rotated 180 degrees counterclockwise by pressing a scraper capable of performing the above, and after the lower backup roll is half rotated, a sequence for opening the scraper is added to the work roll automatic re-arrangement sequence.

[0009]

When the lower backup roll is rotated 180 degrees and a half, foreign matter that has fallen onto the lower backup roll when the work roll is installed falls due to the action of gravity. By pressing the scraper and rotating the lower backup roll a half turn, foreign matter that is difficult to fall can be easily dropped.

Here, the pressing of the scraper is limited to 180 degrees of half rotation of the lower backup roll, because if the scraper is constantly pressed during the rolling operation, the surface of the lower backup roll is scratched due to high speed rotation. This is to prevent the appearance defect of the steel sheet caused by the generation of the streak pattern and the transfer to the lower work roll. With the above, it becomes possible to prevent the occurrence of roll flaw immediately after the work roll is incorporated.

[0011]

EXAMPLE FIG. 1 (a) is a cross-sectional view of a mill showing that foreign matter 5 has fallen on the upper surface of the lower backup roll 1 after the work rolls 2 and 3 have been recombined. When the mill is screwed down and temper rolling is performed in this state, the foreign matter 5 on the lower backup roll 1 is caught when the lower work roll 2 and the lower backup roll 1 come into contact with each other.
Is imprinted on the surface of the lower work roll 2 and then, every time the lower backup roll makes one revolution, an indentation flaw is given to the lower work roll 2.

In the present invention, as shown in FIG. 1 (b), since the lower backup roll 1 is rotated 180 degrees before the screw-down tightening, the foreign matter 5 on the lower backup roll 1 is naturally dropped by gravity. Therefore, no indentation flaw is given to the lower work roll 2. Even when foreign matter has oil content and does not naturally fall due to the adhesive effect, as shown in FIG. 1C, the scraper blade 6 contacts the entire width of the roll 1 on the entrance side of the lower backup roll 1 and presses / releases it. Since foreign matter can be removed with a possible scraper, no indentation flaw is given to the lower work roll 2.

[0013]

According to the present invention, since the foreign matter on the lower backup roll is removed after the work rolls of the dry temper rolling mill are reassembled and before the screw tightening, it is necessary for the operator to enter the mill. There is no improvement in safety. Since it became possible to prevent the occurrence of surface defects on the steel sheet, quality and yield were improved. A mill inlined in a continuous annealing line has the effect of improving the temper rolling ratio and maximizing the merit of continuous processes.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing the concept of the present invention.

FIG. 2 is an explanatory view showing a situation in which an indentation flaw is formed on a lower work roll over time after a conventional work roll is changed.

[Explanation of symbols]

1, 4 Backup roll 2, 3 Work roll 5 Foreign matter 6 Scraper blade 7 Cylinder 8 Steel plate

Claims (2)

[Claims] 1. A skin backup mill for dry temper rolling of lower backup roll drive type, characterized in that after incorporating a work roll, the lower backup roll is rotated 180 degrees and then the screw is tightened. Method for preventing lower work roll indentation flaws in quality rolling. 2. The lower work roll indentation prevention method in dry temper rolling according to claim 1, wherein the surface of the lower backup roll is wiped and rotated by 180 degrees.