JPH06504A - Method for cold rolling steel strip - Google Patents

Abstract

PURPOSE:To improve the grip with a steel sheet and to prolong the roll life by forming projecting and recessing parts on the surface of the work rolls which are treated by hardening of an intermediate stand of a cold rolling mill and also executing rolling using these work rolls. CONSTITUTION:The work rolls which are treated by hardening are mounted in the intermediate stand of the cold rolling mill, the projecting and recessing parts of which the size D of the top face of the projecting part is 30 to 450mum, difference between the projecting and recessing parts is 2 to 20mum and distance P between the peaks of the projecting parts is 50 to 1000 7mum and which are in the range of 1<P/D<5 are regularly formed on the surface of the work roll. This method for cold rolling steel strips is executed using these work rolls. And, the area of the projecting parts of the roll used at this time is the area of 3 to 80% of the effective roll surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cold rolling method for a steel strip which is carried out by using a rolling work roll having an uneven work roll surface of an intermediate stand of a cold rolling mill.

[0002]

2. Description of the Related Art Generally, a rolling work roll used in cold rolling of a steel strip is a rough surface (dull surface) having a minute uneven pattern on the roll surface for the purpose of improving grip with a steel plate, preventing meandering of the steel plate, and the like. ) Is usual, and conventionally,
For the method of processing the roll surface and forming the uneven pattern,
There are a shot plast machining method and an electric discharge dull machining method. However, since the uneven pattern formed by these methods has a protrusion shape with irregular peaks and ridges, when rolling a steel strip with such a roll, the top of the protrusion bites into the steel strip and the rolling load is locally reduced. As a result, the top part is broken and wear is significantly promoted. Therefore, when the roll is used for a short period of time, there arises a problem that the roll is frequently exchanged due to a decrease in grip force accompanied by a decrease in roughness.

Further, as another method of forming an uneven pattern on the roll surface, rolling using a rolling roll processed by a laser beam so that the surface crater pattern of the rolling roll has a predetermined value can be carried out.
Although it is disclosed in Japanese Patent Laid-Open Publication No. JP-A No. 2003-242242, the wear rate of unevenness is high as in the above-mentioned dull processing method, so that there is a problem in that roll replacement is frequent. Further, there is a method of improving the wear resistance by applying Cr plating to the surface of the dull-processed roll, but the plated surface further promotes the projection height of irregularities or irregularity, resulting in a large rolling load locally. Therefore, a problem similar to that of the dull processing roll occurs.

[0004]

DISCLOSURE OF THE INVENTION The present invention is intended to solve the above-mentioned conventional problems, and to improve the uneven roughness shape of the work roll surface by a method of cold rolling a steel strip. In the long term, the grip power with the steel plate is improved,
The purpose is to provide a long life of the roll.

[0005]

In order to achieve the above object, the present invention provides a work roll which has been subjected to a hardening treatment on an intermediate stand of a cold rolling mill, and the size of a convex top surface on the surface of the work roll. Size D is 30 to 450 μm, unevenness is 2 to 20
μm, the peak-to-peak distance P is 50 to 1000 μm and 1
A gist of a cold rolling method for a steel strip is characterized in that regular uneven portions are provided in a range of <P / D <5 and rolling is performed using the work roll. Further, in the present invention, the area of the convex portion is preferably 3 to 80% of the effective roll surface.

The present invention will be described in detail below. Figure 1
The surface of the work roll 1 is processed by the shot blast method, and the pattern of the uneven projections 2 provided is enlarged and shown. The large protrusions on the roll surface in such a state cause seizure with the surface of the steel strip during rolling, causing rapid wear. That is, when the tops of the projections 2 are points or lines, the rolling load locally rises, the plastic deformation restraining force becomes small, and the progress of wear increases. The worn roll surface easily slips with the steel strip. FIG. 2 shows a roll cross section when the work roll 1 in the present invention is shot-blasted as it is, or is shot-blasted and then subjected to a curing treatment, and thereafter a fine pattern is formed by using, for example, a microlithography method. The figure is shown.

FIG. 3 shows an example of the surface processing step of the rolling roll according to the present invention, in which the uneven projections 4 as shown in FIG. 2 are formed on the surface of the roll 1 having a fine uneven rough surface. As a method of forming the uneven projections 2 on the surface of the roll 1, an example thereof can be performed by a method as shown in FIGS. 3 (a) to 3 (d). That is, first, the liquid photosensitive resin 6 is supplied to the photosensitive resin feeder 8 from the hopper 5 installed on the upper portion of the photosensitive resin feeder 8, and the photosensitive resin is adjusted to a predetermined thickness from the rear by the air 7 to adjust the photosensitive resin to the roll surface. To form a photosensitive resin layer (film) 9. Next, the photosensitive resin layer 9 is intermittently irradiated with a wavelength laser beam 11 in the visible region emitted from the laser oscillator 10 at a predetermined regular pitch, and the irradiated portion is cured 14 (FIG. (B)).

In FIG. 1B, a chopper 13 having a slit 12 is used and the beam 1 is rotated by rotating the chopper 13.
Although the intermittent irradiation of 1 is performed, the invention is not limited to this, and for example, polarization control of a continuous irradiation laser beam, a pulse laser, or the like may be used. Then, as shown in (c) of FIG.
When a dissolving agent 16 such as 1,1-trichloroethane is sprayed, the photosensitive resin cured portion 14 is left and the uncured portion is washed to expose the roll surface 17 as shown in FIG. After that, etching is performed with a chemical corrosive agent to form concave portions, and a regular concavo-convex pattern as shown in FIG. 2 is formed.

The intermediate stand of the cold rolling mill is a stand excluding the rolling stands at the front stage and the final stage of the cold rolling mill. The rolls used in the former rolling stand of the cold rolling mill have a problem that scratches occur when the steel plate bites and slips out, and the rolls used in the final rolling stand of the cold rolling mill have steel plate with uneven surface. It must be a roll that is not transferred to the surface. For these reasons, the present invention is limited to intermediate stands.

Next, the size D of the convex top surface of the roll surface specified in the present invention is 30 to 450 μm, and the unevenness difference is 2 to 2.
It will be described that the condition range for providing the regular concavo-convex portion is set in the range of 0 μm, the peak-to-peak peak distance P is 50 to 1000 μm, and 1 <P / D <5. First, when the size D of the convex top surface is less than 30 μm, the rolling load locally increases during rolling because the size of the convex top surface is needle-shaped,
The convex portion is broken and the wear progresses greatly. Further, when the size D of the top surface of the convex portion exceeds 450 μm, the area of the top surface of the convex portion is large and it becomes difficult to transfer the fine pattern during rolling. The unevenness difference is 2
If it is less than μm, it becomes difficult to improve the grip force with the steel plate for a long period of time and to secure the long life of the roll. On the other hand, if it exceeds 20 μm, the end of the convex portion is chipped off during rolling and the mark size becomes small in a short period of time, so that the original purpose cannot be achieved.

When the peak-to-peak distance P between the protrusions is less than 50 μm, the size of the top surface of the protrusions has a needle shape, the rolling load locally rises during rolling, the protrusions are broken, and wear progresses. growing. Further, when the peak-to-peak distance P is more than 1000 μm, the area ratio of the convex portions of the roll is reduced, the rolling load per convex portion during rolling is increased, and the convex portions are partially chipped to cause wear progress. Grows larger. When P / D is less than 1, the area of the convex portion of the effective roll surface exceeds 80%, and the grip force with the steel plate is reduced, and the steel plate is meandered. P / D
Is more than 5, the area of the convex portion of the effective roll surface is less than 3% and the convex portion 1 at the time of rolling irrespective of the size of the roll convex portion top surface D is obtained.
The bearing load per piece becomes large, and the protrusions are partly chipped, etc., and wear progresses greatly.

[0012]

[Example] 3 mm thickness * 1200 m manufactured by a normal method
The reduction ratio of the m-width hot-rolled steel strip is 30% at each stage 5
0.6mm thickness * 1200mm using the multi-stage cold rolling mill
The following three types of rolls were used in the third stage when cold rolling the wide cold rolled steel strip. The surface condition of the work roll used for the intermediate stand of the cold rolling mill is as follows.

(1) Roll of the present invention: In the method of producing protrusions, a resist material was applied to the surface of a rolling roll plated with 8 μm of Cr, and after exposure with a laser, unevenness was formed by etching. The convex shape at that time was a cylindrical shape, and was made to have a dent with a mark diameter of 100 μm and a mark pitch of 125 μm, and to have an area ratio of the convex parts of the uneven pattern (total area of convex parts / effective roll area * 100) of 50%. Was done. (2) Cr-plated roll ... The Cr-plated roll is adjusted to a predetermined roughness by shots that are conventionally used, and then
Hard Cr plating applied, surface roughness 0.7-1.5 μmR
Adjusted to a. (3) Laser dull roll ... The laser dull roll has a roll surface adjusted to 0.5 to 1.8 μmRa, and then laser processed to have a mark outer diameter of 100 μm and a mark pitch of 125 μm.
Was processed.

FIG. 4 shows the rolling amount (TON) when cold rolling a steel strip and the residual ratio of the peak height of protrusions on the work roll surface% [peak height after rolling (protrusion height) / peak height during processing]. (Protrusion height) * 100]. From this, it is clear that the remaining rate of the top protrusions formed on the roll of the present invention is the highest as compared with the other rolls, and is less likely to be worn. That is, the abrasion resistance is twice as high as that of the Cr-plated dull roll and at least 3 times as much as that of the laser dull roll.

[0015]

As described above, according to the present invention, the work roll surface is provided with the projections and depressions of the projection top, and when this is used for cold rolling, the wear resistance of the roll surface is extremely excellent. It is possible to obtain effects such as an improvement in grip strength with a steel plate for a long period of time and a long roll life.

[Brief description of drawings]

FIG. 1 is a view showing a cross section of a dull-processed roll surface.

FIG. 2 is a view showing a cross section of a roll surface having an uneven pattern of protrusions as an object of the present invention.

FIG. 3 is an explanatory view showing an example of the unevenness imparting processing step of the present invention by a lithography method.

FIG. 4 is a diagram showing a relationship between a rolling amount of rolls in cold rolling and a peak (projection) height residual ratio on the roll surface.

[Explanation of symbols]

 1: Roll 2: Dulling convex protrusion 3: Waviness 4: Processing convex protrusion of the present invention 5: Hopper 6: Liquid photosensitive resin 7: Air 8: Photosensitive resin feeder 9: Photosensitive resin layer 10: Laser oscillator 11: Laser 12: Slit 13: Chopper 14: Photosensitive curing part 15: Sprayer 16: Dissolving agent 17: Exposed part

Claims (2)

[Claims] 1. A work roll that has been subjected to a hardening treatment is provided on an intermediate stand of a cold rolling mill, and the size D of the convex top surface is 30 to 450 μm and the unevenness difference is 2 to 2 on the surface of the work roll.
A method for cold rolling a steel strip, characterized in that 0 μm, a peak-to-peak distance P between protrusions of 50 to 1000 μm and regular irregularities are provided in the range of 1 <P / D <5, and rolling is performed using the work roll. . 2. The area of the convex portion is 3 to 80 of the effective roll surface.
%, And the steel strip cold rolling method according to claim 1.