JPH035007A - Method for gold rolling steel strip - Google Patents

Abstract

PURPOSE:To remove edge marks on the surfaces of rolls and to improve productivity and product quality by blasting the surface parts of rolling rolls corresponding to edge parts of a rolled stock with shot grains or grits. CONSTITUTION:On the outlet side of a cold rolling mill are installed blasting devices 5 on the opposite sides of parts corresponding to the edge parts of the rolled stock on upper and lower work rolls 1. When the edge marks are confirmed on the surfaces of the work rolls 1, it is preferable that shot grains or grits are blasted by the blasting devices 5 or they are blasted periodically by a passed amount of rolled stock, for example, after every passage of five or ten rolled stocks. As a result, rolling can be carried out to either dull rolls or bright rolls irrespective of the rolled width schedule and the productivity and product quality can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for cold rolling steel strips which is not limited to a specific rolling width schedule, and more particularly relates to a method for cold rolling steel strips, which is not limited to a specific rolling width schedule. The present invention relates to a cold rolling method that almost completely eliminates plate edge marks and enables width schedule-free rolling of a steel strip that is not limited to a specific rolling width schedule.

Conventional technology When cold rolling a steel strip, the surface of the rolling roll that comes into contact with the edge of the steel strip wears out, creating a step or edge mark on the surface of the rolling roll. Therefore, the width of the steel strip is usually changed from wide to narrow. A rolling width schedule is established so that the edge marks of the rolling rolls are not transferred to the surface of the steel strip.

In addition, in order to ease the constraints on the rolling width schedule from wide to narrow and increase the rolling amount with the same roll, the work rolls of the rolling mill are moved in the roll axis direction so that specific parts of the roll surface wear out. In some cases, a work roll shift is performed to avoid this, or in-line roll grinding is performed in which the roll surface is ground with a grindstone in the rolling line.

However, by only shifting the work rolls, during rolling a large number of steel strips, the roll surface becomes severely worn and rough near the contact area with the edge of the steel strip, making it impossible to significantly improve the rolling amount.

Furthermore, in-line roll grinding cannot be applied to the surface of a roll used in the final stand of a finishing rolling mill because it leaves grinding marks from the grindstone.

As another means, Japanese Utility Model Application Publication No. 57-194704 discloses a means for supplying a liquid containing an abrasive and a means for removing fine abrasive powder in order to reduce the surface roughness of the roll during rolling and to prevent slipping. A cold rolling roll surface polishing apparatus is described.

However, although this polishing device is effective in preventing slippage, it cannot achieve width schedule freedom unless the edge marks on the rolled material are eliminated or blurred.

In addition, as another method, a method has been proposed in which a roll whose surface is plated with hard chrome or hard alloy is used, and the edge of the roll is puff-polished during or between rolling steps (Japanese Patent Application Laid-Open No. No. 62-72407).

FIG. 4 is a schematic diagram showing one embodiment of the device, in which (1) is a work roll, (2) is a backup roll, (3) is a rolled material, and (4) is a puff polishing device. The work roll (1
) is constructed so that the surface portion corresponding to the edge portion of the rolled material is polished.

According to this method, plate edge marks on the surface of the rolling roll can be effectively eliminated or blurred, and as a result, so-called width schedule-free rolling that is not limited to a specific rolling width schedule becomes possible, which improves the life of the rolling roll and improves product quality. can be significantly improved.

However, since this method uses puff polishing to eliminate or make the edge marks unclear, its application is limited to bride rolls only, and dull rolls, which are most commonly used for rolling cold-rolled steel strips. The problem is that it cannot be applied.

Problems to be Solved by the Invention The present invention solves the problem of the puff polishing method of the edge portion of a roll plate that enables rolling width schedule-free rolling among the conventional techniques, that is, it cannot be applied to dull rolls. This paper attempts to propose a method for cold rolling steel strips that can also be applied to steel strips.

Means for Solving the Problems The present invention involves blasting at least the surface portion of the rolling roll corresponding to the edge of the rolled material with shot grains or grids in the rolling mill during cold rolling of a steel strip;
The gist of this paper is a method for width schedule-free rolling of steel strip.

That is, the present invention is characterized by a method of eliminating or blurring plate edge marks on the roll surface by shot blasting instead of the conventional puff polishing method.

A device for blasting the surface portion of the rolling roll corresponding to the edge of the rolled material is installed on the exit side of the rolling mill, and sprays shot grains or grids onto the roll surface to eliminate or obscure edge marks.

The reason why the blasting device is installed on the exit side of the rolling mill is that on the entrance side of the stand, shot grains or grids get caught in the rolls and create indentation flaws. However, in the case of a continuous rolling mill, shot grains or grids get caught in the rolls of adjacent rolling mills, so it is necessary to remove them by blowing away the shot grains or grids on the rolled material between the rolling mill stands using air blow, for example. good.

The shot grains used for eliminating or blurring edge marks are not particularly limited, but may be spherical metal grains with a grain size of about 1#. Further, the grid is made by crushing shot grains and has sharp edges, and can be the same as that used when dulling the roll surface.

It is preferable to use shot grains and grids depending on the rolling roll. When the rolling roll is a dull roll, it is effective to use a grid, and when the rolling roll is a bride roll, it is effective to use spherical shot grains.

By blasting the surface portion of the roll corresponding to the edge of the rolled material with shot grains or grids, the edge mark on the roll surface disappears or becomes unclear, making rolling width schedule-free rolling possible and eliminating product defects caused by edge marks. occurrence will also be eliminated.

Example Figure 1 is a schematic diagram showing the blasting device installed on a cold rolling mill stand, Figure 2 is a schematic diagram showing the same rolling mill as seen from the exit side, and Figure (A) is a dull roll. In the case of , Figure (B) shows the case of a bride roll.

That is, when carrying out the method of the present invention, the blasting device (5) is installed on the exit side of the cold rolling mill, facing the portions of the upper and lower work rolls (1) corresponding to the edge portions of the rolled material. As the blasting device, a shot blasting device used for descaling the surface of a steel plate, etc. can be used.

This blasting device is installed variably in the roll axis direction to accommodate changes in sheet width.

The blasting device (5) projects shot grains or grids onto the work roll surface with edge marks (
8) may be carried out at the time when it is confirmed, or it may be carried out periodically every time the amount of rolled material passes, for example, every 5 or 10 rolled materials.

Fig. 3 shows an example in which the method of the present invention is applied to a continuous rolling mill, in which a blasting device (5) is installed on the outlet side of each rolling mill stand No. 1 to 5, and a blasting device (5) is installed on the outlet side of each rolling mill stand No. 1 to 5. An air blow device (6) is installed between each stand to prevent rolls from getting caught.

Furthermore, if the steel strip is rolled with the ``burrs'' left on the end surface of the steel strip that occur when the steel strip is side trimmed, the roll surface may be damaged or seizure may occur, resulting in product defects.
Since rolling without a rolling width schedule is impossible, a burr removal device (7) is installed on the entrance side of the rolling stand to remove the "burrs" generated on the end face of the steel strip before rolling.

The means for erasing or blurring edge marks by blasting of the present invention can of course be applied to rolls whose surfaces are coated with hard chrome plating or hard chromium alloy. It is more effective to use it in combination with a method of moving each plate for rolling, and a method of rolling by moving the rolling rolls in the axial direction during rolling or during the start of plate rolling after the end of one plate rolling.

Next, an example in which the method of this invention is applied to an actual machine will be described.

Example 1 This invention method was applied to a 5-stand continuous cold rolling mill shown in FIG.
A 500m steel plate with a thickness of 0.6 to 3.0. cold rolled.

At that time, the work rolls used for No. 1 to 4 stands were bride rolls, the work rolls for No. 5 stands were dull rolls (rolled with a grid equivalent to JISS-G120), and the work rolls for No. 1 to 5 stands were used roughly. The surface was chrome plated with a thickness of 10 μm to give a hardness of Hv 1150. Further, by applying chrome plating, the work roll surface roughness of No. 1 to 4 stands was 0.3 μRa, and the work roll surface roughness of No. 5 stand was 2°3 μRa.

In addition, in order to eliminate the plate edge mark on the roll,
, For a 5-stand work roll (dull roll), use a grid equivalent to JIS 5-Gl20, No. 1.
For work rolls (bride rolls) with ~4 stands, shot grains with a grain size of approximately 1 mm are used, and the edge mark portion is approximately 50 mm after every 10 rolled materials pass. I blasted it in width.

For comparison, a work roll shift in which the work roll is moved in the axial direction was adopted as a conventional method, and each rolling coil was shifted repeatedly in one direction and the opposite direction within a total shift amount of 300° at 5 MMn. .

As a result, with conventional work roll shift, the rolling amount is 10
At 0OT, the width schedule was narrow down, whereas in the present invention, the rolling amount could be increased 15 times to 15,000T, and width schedule free rolling could be performed.

In addition, the roll surface roughness after rolling is 0.1μRa for No. 1 to 4 stands, and 1.9R for No. 5 stands.
a, the values were almost the same for both the center and edge portions.

Example 2 A plate with a thickness of 0.5 to 1.5# was produced by a temper rolling mill using a work roll (surface roughness 0.1 μRa) with a bright surface and the same chrome plating as in Example 1.

Width 900-1250. was temper rolled. At that time, the rolling width schedule was set randomly so that the same width did not pass through the same location as much as possible.

In this example, in order to eliminate the edge marks on the roll, shot grains with particle diameters of o, i, and φ are used to remove the edge marks by about 50 mm every five rolled materials. I blasted it in width.

For comparison, rolling was also carried out using a conventional method in which the steel strip width was gradually changed from wide to narrow.

As a result, while in the conventional method the rolling amount was 500T and the width schedule was narrow down, in the present invention the rolling amount was improved six times to 3000T. Further, no edge marks were observed on the roll after rolling, and the surface roughness of both the center and edge portions was 0.1 μRa.

As described in detail, according to the method of the present invention, edge marks on the surface of the roll can be erased or blurred by blasting the surface portion of the roll corresponding to the edge of the rolled material with shot grains or grids. Therefore, it is possible to implement rolling width schedule-free rolling for both dull rolls and bride rolls, improving productivity and product quality, and greatly extending the life of the rolls due to the edge mark prevention effect. I can't help it.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing an example in which the method of the present invention is applied to a cold rolling mill, and Fig. 2 is a schematic diagram showing the same rolling mill as seen from the exit side. Figure (B) shows the case of a bride roll. Figure 3 is a schematic diagram showing an example in which the method of this invention is applied to a continuous cold rolling mill. Figure 4 is a schematic diagram showing a conventional puff polishing method. 1...Work roll 2...Backup roll 3...Rolled material 5...Blasting device 2 2'11 Drinking device 1

Claims (1)

[Claims] 1. In the cold rolling of a steel strip, at least the surface portion of the rolling roll corresponding to the edge of the rolled material is blasted with shot grains or grids in the rolling mill, and the width schedule-free rolling of the steel strip is performed. A method for cold rolling a steel strip, characterized by performing the following steps.