JPH057909A - Rough surface finishing method for dull rolling work roll - Google Patents

Abstract

PURPOSE:To solve such a problem as a burr generated at the time of shot blasting in idle running of a mill by recombination of a plate having work roll cannot be eliminated, in the rough surface finishing method of a dull rolling work roll by shot blasting, and to prevent the generation of a surface defect of a rolling plate. CONSTITUTION:Shot blasting is executed in advance so as to become a little higher than target finish roughness, and thereafter, by rotating a roll, while pressing sand paper or a blade, the surface is ground so as to become target roughness, and burrs generated by shot blasting are eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for roughening the surface of a dull roll used for dull rolling a steel strip.

[0002]

2. Description of the Related Art As a work roll of a rolling mill for rolling a steel strip such as steel or stainless steel, a shot roll-processed dull roll having a surface roughness Ra of 1.0 μm or more is generally used. A conventional method of using a work roll having a dullness will be described with reference to FIG.

As shown in FIG. 4 (a), the work roll 3 which is dull-marked by the shot blasting 5 on the shot blasting carriage 6 is installed in the rolling mill 2 and prior to the rolling of the steel strip, as shown in FIG. As shown in b), while applying a reduction of about 500 tons, the coolant is supplied from the coolant spray 7 to idle the rolling mill 2. Then, Fig. 4 (c)
As described above, the rolling of the steel strip 1 is started.

The reason why this rolling mill is subjected to idling reduction is that minute burr 10 is formed on the roll surface after shot blasting as shown in FIG. 3, and the steel strip is rolled without removing the burr 10. This is because the burr 10 is peeled from the roll and embedded in the surface of the steel strip to form a surface defect, so that the burr 10 is peeled off under the idling pressure of the rolling mill. The peeled burr 10 is washed off by the coolant 7.

[0005]

However, in recent years, in order to improve the productivity of the rolling mill 2, the work rolls 3 are exchanged while the steel strip 1 is left in the rolling mill 2, so-called "work roll set with plate". Since "replacement" has become the mainstream, it has become impossible to reduce the idling of the rolling mill after the roll replacement, and the burr 10 cannot be removed by the conventional method.
An object of the present invention is to solve the above-mentioned problems and provide a rough surface finishing method for a work roll for dull rolling, which is suitable for "replacement of work roll with plate".

[0006]

A first aspect of the present invention is a method of roughening a work roll for dull rolling by shot blasting, in which the roll surface is slightly higher than the target surface roughness by shot blasting. After the application, the burr on the roll surface generated during the shot blasting is removed by polishing to a target surface roughness by a mechanical polishing means.

A second aspect of the present invention is a rough surface finishing method for a work roll for dull rolling having a surface roughness Ra of 1.0 μm or more used after shot blasting, which is higher than a target surface roughness Ra = A μm and (A + 1). .0) After shot blasting to a range of less than μm, sand rolls with fine abrasive grains of # 600 or more are pressed down with a surface pressure of 0.01 to 0.3 kg / cm ² to rotate and roll to a target roughness. It is a rough surface finishing method for a work roll for dull rolling, which is characterized in that

A third aspect of the present invention is a rough surface finishing method for a work roll for dull rolling having a surface roughness Ra of 1.0 μm or more used after shot blasting, which is higher than the target surface roughness Ra = A μm and (A + 1). .0) For dull rolling characterized by shot blasting to a range of less than or equal to μm, and then polishing by rotating the roll while reducing the blade at a linear pressure of 3.0 to 6.0 kg / m to reduce to the target roughness. This is a rough surface finishing method for work rolls.

[0009]

[Operation] In the present invention, in a method of roughening a work roll for dull rolling by shot blasting,
After applying a surface roughness slightly higher than the target surface roughness by shot blasting, and then polishing to the target surface roughness with a mechanical polishing means such as sandpaper or a blade Also, the burr on the roll surface generated during shot blasting can be efficiently removed.

That is, according to the present invention, in order to solve the problem that the burr generated during the shot blasting in the mill idling cannot be removed by the "replacement of work rolls with plate", before the work rolls are installed in the rolling mill. The burr is removed.

[0011]

Embodiments of the present invention will be described with reference to the drawings.
First, an embodiment of the second invention will be described. FIG. 1 is an explanatory diagram of an embodiment of the second invention. First, the surface roughness Ra of the work roll 3 is finished by shot blasting 5 to a range higher than the target surface roughness Ra = A μm and not more than (A + 1.0) μm [see FIG. 1 (a)].

After that, the work roll 3 is idled while the sandpaper 8 is being pressed down, so that the burr on the roll surface is peeled and removed [see FIG. 1 (b)]. At this time, since the surface roughness of the roll is also reduced by the sandpaper 8, the rotation of the roll is stopped when the target roughness Ra = A μm is reached. By this method, the burr at the time of shot blasting, which is a problem in terms of the quality of the steel strip, can be removed while maintaining the target surface roughness of the work roll 3.

Next, a concrete embodiment of the second invention will be described. Target surface roughness Ra = 3.0 ± 0.2 μm for work roll 3 made of 3% Cr steel (hardness H _S = 90) and outer diameter 610 mm
Then, the following rough surface finishing of the second invention was performed. First,
After finishing Ra = 3.4 μm by shot blasting 5, the surface of the work roll 3 is sandpaper 8 containing # 800 abrasive grains.
Then, the work roll 3 was rotated four times by pressing with a surface pressure of 0.02 kg / cm ² . As a result, the burr was almost removed, and the surface roughness was Ra = 3.2 μm, which was 0.2 μm. Then another 3
When rotated, Ra was 3.1 μm. When this work roll 3 was incorporated into the rolling mill 2 and actually rolled, there was no problem in terms of quality.

Next, the work roll 3 of the same material and outer diameter was subjected to the following second rough surface finish of the invention with a target surface roughness Ra = 1.0 ± 0.1 μm. First, after finishing with Ra = 1.5 μm by shot blasting 5, the surface of the work roll 3 is 0.2 kg / # with sandpaper 8 containing # 600 abrasive grains.
The work roll was rotated once by pressing with a surface pressure of cm ² . As a result, the burr is removed and the surface roughness is Ra = 1.1μ.
It was m. After this, one more rotation, R
It became a = 0.9 μm. This work roll 3 is rolled into a rolling mill 2
When it was built in and rolled, there was no problem in quality.

Subsequently, various tests were conducted by changing the grain size of the sandpaper 8, the rolling force, and the surface roughness Ra of the work roll. To summarize the results, if the grain size of the sandpaper 8 is # 600 or less, the work roll 3 cannot be scratched. If the surface pressure of the sand paper 8 is less than 0.01 kg / cm ² , the burr cannot be removed. ^{On the other hand} , if it exceeds 0.3 kg / cm ² , the decrease of the surface roughness becomes unstable with Ra = 0.5 to 1.0 μm / time and becomes unstable. Therefore, 0.3 kg / cm ² or less is desirable.

The surface roughness of the roll is considerably reduced by the initial rotation of the sandpaper during the pressure-reducing polishing, but thereafter, the rate of decrease is small. Therefore, if the thickness is increased above 1 μm, the target roughness may not be reduced. The number of rotations only increases. Therefore, it is desirable to increase the thickness in the range of 1.0 μm or less. Further, if the sandpaper 8 is fixed, streak-like flaws may be formed in the work roll 3, so it is desirable to slide it in the roll width direction.

Next, an embodiment of the third invention will be described. FIG. 2 is an explanatory diagram of an embodiment of the third invention. First, the surface roughness Ra of the work roll 3 is set by shot blasting 5.
Target surface roughness Ra = higher than A μm, (A + 1.0) μm
Finish within the following range [see FIG. 2 (a)].

After that, the work roll 3 is rotated while pressing down the blade 9 to peel off the burr on the roll surface [see FIG. 2 (b)]. At this time, since the surface roughness of the roll is also reduced by the blade 9, the rotation of the roll is stopped when the target roughness Ra = A μm. By this method, the burr at the time of shot blasting, which is a problem in terms of the quality of the steel strip, can be removed while maintaining the target surface roughness of the work roll 3.

Next, a concrete embodiment of the third invention will be described. For 3% Cr steel (hardness H _S = 90) and work roll 3 with an outer diameter of 610 mm, target surface roughness Ra = 3.0 ± 0.2 μm,
The following rough surface finish of the third invention was performed. First, after finishing Ra = 3.5 μm by shot blasting 5, the surface of work roll 3 is made of material SK5, blade thickness 0.2 mm.
The blade 9 was pressed with a blade pressing force of 3.5 kg / m, and the work roll 3 was rotated once. As a result, the burr was almost removed, and the surface roughness was Ra = 3.2 μm, which was 0.3 μm. Then, when it was rotated once again, Ra was 3.1 μm. When this work roll 3 was incorporated into the rolling mill 2 and actually rolled, there was no problem in terms of quality.

Next, the work roll 3 of the same material and the outer diameter was subjected to the following rough surface finishing of the third invention with the target surface roughness Ra = 1.0 ± 0.1 μm. First, after finishing Ra = 1.5 μm by shot blasting 5, the surface of the work roll 3 is pressed by a blade 9 of material SK5 and blade thickness 0.2 mm with a rolling down force of 4.0 kg / m, and the work roll 3
Rotated. As a result, the burr was removed and the surface roughness was Ra = 1.3 µm. Then, work roll 3
When rotated, Ra was 1.1 μm. When this work roll 3 was installed in the rolling mill 2 and actually rolled,
Similarly, there was no problem in terms of quality.

Subsequently, various tests were conducted by changing the pressing force of the blade 9, the material, and the roughness of the work roll 3. To summarize the results, burr remains when the rolling force of the blade 9 is 3.0 kg / m or less. When the pressing force of the blade 9 is 6 kg / m, the decrease in surface roughness is unstable as Ra = 0.5 to 1.0 μm / time, so less than that is desirable.

The surface roughness of the roll is considerably reduced by the initial rotation in the blade polishing, but thereafter, the rate of decrease is small. Therefore, if it is increased to more than 1 μm, it may not be reduced to the target roughness. The number of rotations only increases. Therefore, it is desirable to increase the thickness within the range of 1.0 μm or less. Further, since the fixed blade 9 may have a streak-like flaw on the work roll 3, it is desirable to slide the fixed blade 9 in the roll width direction.

The blade 9 may be installed at the shot blasting section, but if it has already been installed inline for caring for the roll, this should be used.

[0024]

As described above, according to the method of the present invention, it is possible to prevent quality defects caused by burr during shot blasting while carrying out "work roll change with plate", and a great productivity improving effect is obtained. To be

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of a second invention.

FIG. 2 is an explanatory diagram showing an embodiment of the third invention.

FIG. 3 is an enlarged sectional view schematically showing a burr during shot blasting.

FIG. 4 is an explanatory diagram of a conventional rough surface finishing method for a work roll for dull rolling.

[Explanation of symbols]

1 steel strip 2 rolling mill 3 work rolls 4 backup roll 5 shot blast 6 shot blast cart 7 Coolant spray 8 Sandpaper 9 blades 10 collar

Claims (3)

[Claims] 1. A method of roughening a work roll for dull rolling by shot blasting, wherein a surface roughness slightly higher than the target surface roughness is given to the roll surface by shot blasting, and then the target is mechanically polished. A rough surface finishing method for a work roll for dull rolling, which comprises removing burr on the roll surface generated during shot blasting by polishing to a surface roughness. 2. In a rough surface finishing method for a work roll for dull rolling having a surface roughness Ra of 1.0 μm or more used after shot blasting, a target surface roughness Ra is higher than A μm and not more than (A + 1.0) μm. After shot blasting so that it falls within the range of # 600, sand rolls with fine abrasive grains of # 600 or more are rotated and polished while pressing down with a surface pressure of 0.01 to 0.3 kg / cm ² to lower the target roughness. Rough surface finishing method for dull rolling work rolls. 3. A rough surface finishing method for a work roll for dull rolling having a surface roughness Ra of 1.0 μm or more used after shot blasting, wherein a target surface roughness Ra is higher than A μm and not more than (A + 1.0) μm. After shot blasting to the range of, the linear pressure of the blade is 3.0 to 6.0 kg /
A rough surface finishing method for a work roll for dull rolling, which comprises rotating and polishing a roll while rolling it down at m to lower the target roughness.