MXPA00000649A - Method for manufacturing cold rolled metal strip having improved surface roughness - Google Patents

Abstract

This invention relates to a process for producing a cold rolled, recrystallization annealed, stainless steel strip (12E) having lustrous surfaces without being hot band annealed and/or pickled prior to cold reduction. The process includes the sequential steps of tension leveling to crack the scale and flatten a hot processed metal strip (12), shot blasting the strip (12A) to ablatively remove the scale and to provide a surface roughness less than 3.6 micron Ra using at least two pairs of wire brushes (38, 42) positioned adjacent to both surfaces of the strip (12B) with these cleaning brushes (38, 42) being rotated in opposite directions relative to each other to mechanically remove any residual scale. The mechanically cleaned strip (12C) then is mechanically polished with another pair of brushes (50) to reduce the roughness to less than 2.0 micron Ra, cold reduced to a surface roughness less than 0.4 micron Ra and recrystallization annealed.

Description

METHOD FOR MANUFACTURING COLD LAMINATED METAL STRIP THAT HAS IMPROVED SUPERFICIAL ROUGHNESS BACKGROUND OF THE INVENTION This invention relates to a process for producing cold rolled metal strip without hot strip annealing and / or pickling a strip hot processed before cold reduction. The process includes the sequential stages of stress leveling to crack scale and to flatten the strip of hot-processed metal, injection of particle jet into the strip for abrasive removal of the scale, placing at least two cleaning brushes adjacent to each surface of the strip and rotating the brushes in opposite directions to each other, to remove any residual encrustation and provide a predetermined roughness, polish the cleaned surfaces with a brush to further reduce the roughness and cold reduction of the clean strip, so that the surfaces have a lustrous finish. It is known to flatten hot rolled strip before cold reduction using a leveler. The patent of the U.S.A. No. 4,872,245 discloses a process line for producing cold rolled steel strip from hot rolled strip. This patent discloses REF: 32576 using a tension leveler having a flange and bending rollers to flatten the strip and crack crosswise incrustation. The elongated strip is then descaled by passing it through a pair of brushes and a pickling tank before cold reduction in a tandem rolling mill. It is known to cold reduce a strip of hot rolled metal without annealing of recrystallization and / or pickling of the hot rolled strip before cold reduction. The patent of the U.S.A. No. 5,197,179 describes a continuous process line for producing cold rolled stainless steel, from hot rolled strip. This patent discloses a hot-rolled strip that is passed through an investment rolling mill or tandem cold reduction mill before annealing and pickling. Shot blasting injection can be used to assist in removal of the scale. It is also known to descale hot rolled metal strip, without recrystallization annealing and / or pickling of the hot rolled strip, before cold reduction. These descaling processes include one or more of the tension leveling steps to crack the scale and flatten the hot rolled metal strip, grit wheel grit injection into the strip, to remove the scale and mechanical brushing of the hot rolled strip, before cold reduction. The patent of the U.S.A. No. 5,606,787 describes a continuous process line for producing cold rolled stainless steel, from hot rolled strip. This patent discloses a hot-rolled strip that is passed through a cold tandem rolling mill, a continuous annealing furnace, an optional molten salt bath, a decapator and an optional hardening laminator train. No annealing and injection of strip shot before cold reduction is required to produce a surface roughness of less than 2.03 x 10"8 cm (80 μ-in) after a simple cold rolling. 5,554,235 describes a continuous process line for producing cold-rolled stainless steel without annealing or acid etching from a hot-rolled strip before cold rolling in a tandem rolling mill This patent describes a hot-rolled strip that has been descaled, by optionally stretching on a leveler to flatten the strip and crack the scale and then use a shot blast nozzle or brush polisher to remove the scale before cold reduction After cold rolling, the strip can optionally be passed through a conventional annealing furnace, another shot jet injector, a brush polisher, a decapador and stretching levelers. Japanese Patent Application 55-133802 discloses a process line for producing cold rolled steel from hot rolled strip without annealing or acid stripping of hot rolled steel before cold rolling. The hot-rolled strip is descaled using a tension leveler to crack the scale, passes through water spray with high pressure and finally through planing rollers before passing through a cold rolling tandem rolling mill train . However, the requirements for roughness and surface flatness of cold reduced steel are becoming stricter for applications such as stainless steel sheet and pipe for collector manufacturing, articles, automotive decorative finishes and the like. These applications often require a cold reduced strip that has no more than 20 flatness units I across the width of the strip and a surface roughness of less than 0.4 micro Ra. Prior art processes to produce a cold rolled strip without hot strip annealing and / or pickling before cold reduction do not produce the surface smoothness and flatness required to meet these customer requirements after cold reduction . Accordingly, a need remains for an improved process for producing cold rolled metal strip, especially stainless steel, having glossy surfaces without hot strip annealing and / or pickling a strip hot-processed before cold reduction. There also remains a need for a process to descale hot-processed ferrous metal strip before cold reduction that does not require stripping with sulfuric or hydrochloric acid. There also remains a need for a process to descale hot-processed stainless steel strip that does not require nitric acid, hydrofluoric acid or a fluorine compound. BRIEF COMPENDIUM OF THE INVENTION This invention relates to a method for producing cold rolled metal strip having glossy surfaces without hot strip annealing and / or pickling a strip hot-processed before cold reduction. A main objective of the invention is to provide a cold-reduced metal strip to a final gauge without having to anneal or strip a hot-processed strip before cold reduction. Another object of the invention is to provide this cold reduced metal strip having glossy surfaces with roughness less than 0.4 micro Ra, while complying with the gauge and standard thickness tolerances. Another object of the invention is to provide this cold reduced metal strip that has no more than 20 flatness units I across the width of the strip. Additional objects of the invention include providing a descaling process that eliminates or minimizes the formation of by-products of pickling solution, especially nitric or hydrofluoric acids or fluorine compounds, which will cause an environmental waste problem and provide a cost advantage in Comparison with steel sheet that otherwise occurs when annealing and stripping before cold reduction. The invention includes the sequential steps of stress leveling of a strip of hot-processed metal to crack scale and to flatten the strip, to inject jet of particles onto the surfaces of the strip for abrasive removal of the scale, to place at least two brushes of cleaning, both adjacent to each strip surface and rotating the brushes in an opposite direction to each other to remove any residual scale and provide a predetermined roughness to each strip surface, polish each clean strip surface with a brush to further reduce the roughness and cold reduce the clean strip in such a way that the surfaces have a glossy finish. Another feature of the invention is that the aforementioned strip is stretched at least one percent elongation. Another feature of the invention is that the aforementioned polished surfaces have a roughness less than 1.5 micro Ra before cold reduction. Another feature of the invention is that the aforementioned cleaning brushes have a surface density greater than twelve percent square surface area unit. Another feature of the invention is that the aforementioned cleaning brushes have bristles with a diameter of .13 to .50 mm. Another feature of the invention is that the aforementioned cold reduced strip has a roughness of less than 0.4 micro Ra. Another feature of the invention is that the aforementioned strip is cooled at least thirty percent cold. Another feature of the invention is to include at least three of the aforementioned cleaning brushes, adjacent to each strip surface.

Another feature of the invention is that at least ninety percent of the aforementioned particles have a size of .10 to .50 mm. Advantages of the invention include reduction in manufacturing costs, minimization of the by-product formation of pickling solution, especially fluoride or nitric acid or hydrofluoric compounds, which would cause a waste problem to the environment, and recycle "powder" of scale back to a refining melting furnace. The process of the invention avoids the need for expensive facilities for waste treatment and contamination control. The foregoing and other objects, features and advantages of the invention will be apparent upon consideration of the detailed description and accompanying drawings. BRIEF DESCRIPTION OF THE DRAWING Figure 1 illustrates a schematic view of a continuous processing line of the invention for producing a strip of cold-rolled metal from a hot-processed strip that includes the sequential stages of stress leveling of the processed strip hot, cleaning by injection of shot on the strip, cleaning with brushes of the strip, polishing with brushes of the strip and cold reduction of the strip.

DETAILED DESCRIPTION OF THE PREFERRED METHOD A metal strip of the invention can be produced from a melt, especially a steel fusion containing chromium, by continuously emptying into a strip having a thickness less than or equal to 10 mm, a thin plate less than or equal to 140 mm, a thick plate less than or equal to 200 mm or cast in an ingot. The cast metal is then processed hot in a strip of continuous length. By "hot processing" it will be understood that the metal strip will be reheated, if necessary and then reduced to a predetermined thickness such as by hot rolling. If hot-rolled, a steel plate can be reheated to 1050-1300EC, hot rolled using a finish temperature of at least 800EC and coiled at a temperature no greater than about 650EC. Additionally, the hot rolled strip will be desiccated and cold reduced preferably at least 30%, more preferably at least 50% to the desired final gauge thickness. Subsequently, the cold reduced strip can be annealed by recrystallization. A significant advantage of this invention is a hot-processed strip that does not require annealing prior to cold reduction, i.e. hot strip annealing. Another equally significant advantage of this invention is a hot-processed strip that does not require to be chemically treated, ie pickled to remove scale before this cold reduction. The metal strip of the present invention can be produced from a hot processed strip, made by a number of methods from different metals. The strip can be produced from plates formed of ingots or continuous molded plates which are reheated followed by hot rolling to provide a starting hot strip, with a thickness of 2 to 6 mm or the strip can be hot processed from of strip continuously molded in thicknesses of 2 to 10 mm. The present invention is also applicable to strip produced by methods where continuous cast plates or slabs produced from ingots are fed directly to a hot rolling mill with or without significant heating or reduced ingots to plates of sufficient temperature for hot rolling in strip with or without additional heating, or the molten metal is emptied directly into a suitable strip for further processing. The metals of the invention may include but are not limited to ferrous metals such as low carbon steel, chromium alloy steel, ferritic stainless steel, austenitic stainless steel, martensitic stainless steel and non-ferrous metals such as titanium, copper and nickel. An important feature of this invention is to elongate, in tension, a hot processed strip sufficiently preferably at least about 1%, more preferably 2 to 10%, especially 2 to 7%, to loosen 0 cracking brittle incrustation on both surfaces of the strip and flattening the strip, if necessary. As will be discussed below, the fissured scale will be removed in an abrasive manner by injection of a jet of particles followed by brushing and polishing. Means for applying tension to the strip to eliminate buckling in this manner forming a "completely flat" strip, may include a temper rolling mill or preferably a tension leveler including multiple flange and bending rolls. It is important to lengthen the strip by at least 1% because many applications for stainless steel sheets often require the sheet to have less than 40 I units, preferably no more than about 20 I units, of flatness across the width of the sheet. A unit of flatness I is the ratio between the height and wavelength of the leaf buckling and is defined by the ratio 1 = (Ll - L2) / L2 x 10"5, where Ll equal to the greater length of the strip and L2 the shortest length of the strip.

A very important feature of this invention is to remove fissured scale from the hot-processed strip by injecting jet with abrasive particles, i.e. abrasive wheel grains having angled surfaces or with saw teeth or preferably spherical shot. The jetting of particles from encrusted strip surfaces is employed in the invention due to considerable jet-blasting cleaning in addition to cracking caused by drawing, it is required to ensure removal of the encrustation from the hot rolling mill, especially scale inlays. ferritic and austenitic stainless steel, which are difficult to remove. Suitable particles of this invention may be sawtooth abrasive wheel grains or ferrous spherical grit with at least 95% of the particles having a diameter of at least 10 mm. Preferably, at least 45% of the particles will have a diameter of .30 to .50 mm. More preferably, at least 90% of the particles will have a diameter of .10 to .50 mm. In particular 45 to 55% of the particles will have a diameter of .10 to .30 mm, 45 to 55% of the particles will have a diameter greater than .30 mm up to .50 mm and no more than 10% of the particles will have a diameter greater than .50 mm. It is important that at least 95% of the abrasive particles have a diameter of at least 10 mm to provide adequate impact energy and good particle dispersion, ie uniform number of particle impacts per unit time, across the width of the strip to provide satisfactory cleaning. It is also important that a test of the abrasive sample does not have more than about 10% of the particles with a diameter greater than .50, because an excessive energy impact results in average surface roughness (Ra) greater than that of another way it is possible to withdraw in subsequent processing. Non-metallic particles such as glass, silica, alumina and the like are not acceptable for an abrasive of this invention, because it does not provide adequate cleaning of the surface of the strip.

Unlike prior art shot blasting cleaning systems, they have inadequate particle performance where the particles are pneumatically transported to a steel surface, i.e. compressed gas, the metal particles of the invention are preferably They transport to a steel surface using a high speed rotating wheel. The velocity of the metal particles should be at least 55 mm / sec. Using a high speed wheel to throw the metal particles to the surface of the strip is advantageous because by using a speed of at least about 55 mm / sec for the particle sizes described above, it provides a broad impact energy for Remove the most adherent of hot stainless steel laminator train inlays. A very important additional feature of this invention is to remove any remaining residual fissured scale from the hot-processed strip using at least two cleaning brushes., preferably wire brushes, placed adjacent to each surface to be cleaned with the brushes turned in opposite directions to each other. The reason is that at least one pair of opposite rotating brushes is required for each strip surface, it is to ensure a total coverage of the strip surface with brushing to completely descale the entire surface, including the craters left behind by the jet injection of metal particles from the strip surfaces. Each pair of brushes should reduce the roughness of each of the clean but unpolished strip surfaces, preferably less than 3.6 micro Ra (μm or micrometer) more preferably not more than 3. 0 micro Ra and especially no more than 2.5 micro Ra at this stage of processing. We have determined that the bristles of these cleaning brushes should have a small tip diameter of .13 to .50 mm. Not being bound by theory, it is considered that the tip diameter should be at least .13 mm, because wire bristles of smaller diameter apparently have insufficient rigidity to physically penetrate the small craters formed on the strip surface by the Shot blasting jet particles to remove scale from there. If the tip diameter exceeds approximately .50 mm, then the wire bristles are apparently too large to penetrate the small craters. This leaves encrustation inside the craters and therefore when the strip is cold reduced, the incrustation is laminated or embedded in the surface of the strip, resulting in an unacceptable final surface finish. Preferably, the tip diameter of the bristles should be .13 to .25 mm.

Since the bristles of the opposite rotary cleaning brushes of the invention have a tip diameter as small as .13 mm, it is also important that the brushes have sufficient surface density, ie tightly packed bristles, in such a way that the bristles penetrate the small craters formed in the strip surface by the injection of shot blasting.

It has been determined that a preferred minimum surface density of the bristles is at least 12% of unit square surface area, more preferably at least 20%.

The unitary square surface area is defined as units squared / units squared of surface area, for example .12 cm2 / l cm2 of surface area and .20 cm2 / l cm2 of surface area are 12 and 20%, respectively. Wire brushes are the select cleaning brushes, because the removal of metal from the strip surface does not occur as in the case when brushes made from synthetic bristles are used. Synthetic bristles can be woven, formed into mats or from a bristle design having a synthetic material impregnated with carbide, for example nylon with different amounts and sizes of abrasive material. Brushes made using these synthetic bristles and impregnated with materials such as silicon carbide or aluminum oxide are unacceptable for the opposing rotating cleaning brushes of this invention. Brushes made using synthetic bristles are undesirable because as much as 2% loss in performance can occur to the strip due to metal grinding of the surfaces. Wire brushes on the other hand, are less likely to rectify or clean the surface of the strip. A preferred wire brush for use with the invention is available from the Maryland Brush Company, Baltimore, Maryland.

This brush is constructed by assembling wire bristles in a metal folder and wrapping this folded around a barrel by helical winding. Preferably, the standing surfaces can have a bristle density of at least 12% square surface area. If the density is less than 12%, the coverage of the bristle tips on the surface area of the strip may not be adequate to completely remove all the scale. Unlike the prior art, it is critical that these cleaning brushes are turned in opposite directions to each other. The reason for this requirement is that because the brush bristle tips have been shown to completely remove incrustation from depressed areas on the surface, e.g., voids, craters in the strip. Preferably, there are at least three of these cleaning brushes mounted adjacent to each strip surface. If there are three cleaning brushes, the first brush preferably will be turned in a direction opposite to the direction of travel of the metal strip. If the first brush is turned clockwise while the strip from left to right, the second brush will then turn in the counterclockwise direction, the third brush will turn in the opposite direction to the clockwise and so on. An important final feature of this invention is that the hot-processed cleaning strip is additionally treated by a polishing brush to reduce the roughness before cold reduction to less than 2.0 micro Ra, preferably to no more than 1.5 micro Ra and preferably no more than 1.0 micro Ra, to produce a "white" or "matt" surface finish. This final polishing brush may have synthetic bristles, although a brush with wire bristles is preferred. For some stainless steel applications, it is necessary to have a surface roughness of less than .4 micro Ra, preferably less than 0.3 micro Ra after cold reduction. To ensure this glossy surface finish, the roughness should not exceed 1.5 micro Ra in front of the cold reduction rolling mill. For a better understanding of the invention, Figure 1 illustrates a schematic view of a continuous processing line for producing a strip of cold rolled metal from a hot processed strip. It will be understood that the processing may also use separate processing units. The processing line includes the sequential steps of unwinding a hot processed strip 12 from an unwinding reel 10. The ends of the strip can be squared by a shear 14 and welded for continuous processing by a welder 16. The continuous strip then passes through a loop former 20 including an inlet flange roller 128 and an outlet flange roller 22. Subsequently, the strip is stretched in tension by a draw leveler 24 including the flange rollers 28, 30 and rollers of bent 26. This stretched and bent flattens the strip to a "completely flat" condition as well as fissures and loosens the inlay. The 12 M stretched strip is then passed through a shot jet injector 34 where most of the scale is removed abrasively from the strip. The partially clean surfaces of the strip 12 B are then passed through a brush cleaning station 36 including multiple pairs of cleaning brushes 38, 42, 46 to mechanically remove any residual scale and to reduce the surface roughness of the strip. These cleaning brushes will include at least two pairs of brushes 38, 42 and preferably at least one third pair of brushes 46 juxtaposed on opposite sides of the strip, ie one above and one below the strip. It is important that each cleaning brush is turned in a direction opposite to that of its adjacent brush, ie placed on the same side of the strip. For example, in the brush cleaning station 36, the upper brush 38 will turn clockwise, the upper brush 42 will rotate counterclockwise and the upper brush 46 will turn clockwise the upper brush 46 is turned clockwise as indicated by arrows 40, 44, 48, respectively. The lower cleaning brushes will rotate exactly the opposite, ie the lower brush 38 is rotated counterclockwise, the lower brush 42 is rotated counterclockwise and the lower brush 46 is turned in the opposite direction to that of the clock hands. Preferably, the initial pair of brushes 38 is rotated in a direction opposite to the direction of travel of the strip 12B. Strip 12B is illustrated as running from left to right. The clean strip 12C is then passed through a pair of juxtaposed polishing brushes 50, one placed on the strip and the other positioned below the strip, to reduce the roughness to less than 1.5 micro Ra, preferably less than approximately 1.0 micro Ra. The processing line in Figure 1 illustrates two pairs of polishing brushes 50. The polished strip 12D is then cold reduced, preferably at minus 30% in a tandem rolling mill 56 or a rolling mill Z (not shown). The cold reduced strip 12E will have a surface with a lustrous finish, preferably with a roughness no greater than 0.3 micro Ra. The highly polished strip 12M can then be rewound in a coil by a tension reel 58. The process illustrated in Figure 1 can include another loop former immediately ahead of the tension reel 58 and additional downstream processing equipment such as a continuous annealing furnace, cleaning of additional strip, for example pickling with acid, a side trimmer and the like after the cold reduction rolling mill. The spool 58 which operates in concert with the unwind spool 10 will stretch the metal strip in the tension leveler 24. It is important to stretch the metal strip preferably at least 1% to crack the scale and flatten the strip. By removing the proportion of surface ripples, ie wavy, bulging edges in strip 12 caused during rolling in a hot strip mill, it may be necessary to stretch the strip as much as 10% to obtain a strip "completely" flat "12A. Example 1 In a comparative example, a stainless steel plate having a thickness of 20 cm is hot rolled in a hot strip mill to produce a strip having a thickness of 2.5 mm. The strip is passed through a tension leveler where the strip is stretched 3.5% to crack the incrustation and flatten the strip to a completely flat condition. The stretched strip is then passed through a shot jet injection machine to clean both surfaces of the strip. Subsequently, the strip subjected to shot blast injection is brushed with brushes of synthetic bristles impregnated with aluminum oxide, mounted on both sides of the strip, with brushes that are rotated in the same direction at speeds of 1,000 to 3,000 rpm. Various amounts of visible "salt and pepper" scale remain on both surfaces of the strip. This pepper inlay demonstrates that the hot rolling mill inlay was not satisfactorily removed from the strip. The thickness of the strip after cleaning is reduced by .05 mm due to excessive rectification of the synthetic brushes that remove metal thickness from the surface. This excessive rectification causes a loss of performance of approximately 2%.

Subsequently, the strip is passed between four sets of polishing brushes mounted on both sides of the strip, with the brushes being rotated at speeds of 1,000 to 3,000 rpm and in a direction opposite to the direction of travel of the strip. The surface roughness of the strip was 3.6 micro Ra. The strip is then cold reduced by 40% in two high Z cold reduction rolling mills that are operated in tandem. The processing rollers had surface roughness less than 1.3 micro Ra. After cold reduction, the final cold reduced steel strip had a surface roughness of approximately 0.4 micro Ra, ie finish # 1. A suitable surface will have a roughness less than 0.4 micro Ra. A preferred 2-D finish requires a surface roughness on a final cold reduced steel strip no greater than 0.3 micro Ra. Example 2 In an example illustrating the present invention, an austenitic stainless steel plate with a thickness of 20 cm, a hot rolling mill is hot rolled to produce a strip with a thickness of 2.5 mm. The strip is processed as described in example 1 except as follows. The stretched strip is then passed through a shot blasting machine using steel particles with a tested size of 0.29 mm. Subsequently, the strip subjected to shot blast is cleaned with brushes available from Maryland Brush Company, mounted on both sides of the strip, with the brushes being turned in opposite directions to each other. These cleaning brushes had wire bristles with a tip diameter of .25 mm. The density of the brushes was 21%.

No visible incrustation was left on any surface of the strip. The thickness of the strip after cleaning is reduced by less than .001 mm due to rectification by the wire brushes. Subsequently, the strip is passed between a pair of juxtaposed Scotch Brite ™ polishing brushes, available from Minnesota Mining and Manufacturing of Minneapolis, Minnesota. A pair of these brushes were mounted on opposite sides of the strip. These brushes were rotated at speeds of 1,000 to 3,000 rpm and in a direction opposite to the direction of travel of the strip. The surface roughness of the highly polished strip was 1.5 micro Ra. The polished strip was then cold reduced by 50% in a 4-height tandem cold reduction mill. The work rolls had a surface finish of .13 to .30 micro Ra. After cold reduction, the final cold reduced steel strip had a surface roughness of less than 0.30 micro Ra and had a "completely flat" condition. The roughness of the strip surfaces was generally less than 0.26 micro Ra and as low as .13 micro Ra. This example demonstrates that the invention results in cold-reduced stainless steel strip having excellent glossy surfaces of 2-D finish, i.e. no greater than 0.3 micro Ra, to be produced by a hot-rolled strip without annealing or pickling of laminated strip in hot before cold reduction. In addition, the rectification of the strip surfaces that otherwise causes a loss in performance was not necessary. In this example, less than .01 mm thickness of total metal surface was removed, ie less than .5%. It will be understood that various modifications can be practiced in the invention without departing from the spirit and scope thereof. Therefore, the limits of the invention should be determined from the appended claims. It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims (20)

1. CLAIMS Having described the invention as above, the content of the following claims is claimed as property: 1. - A method for producing a strip of cold-rolled metal from a strip processed in hot without annealing or stripping with acid from the strip hot-processed before cold-rolling, characterized in that it comprises: providing a strip of hot-processed metal covered with inlay, stretching the strip in tension to crack the scale and flattening the strip, injection of jet of particles on each surface of the strip elongated to remove the scale and provide a surface having a predetermined roughness, clean the surfaces to be removed. Any residual incrustation with at least two brushes placed adjacent to each surface and rotated in opposite directions to each other, polishing each clean surface with at least one polishing brush to further reduce the roughness, and cold reducing the strip, thereby making the surface It has a lustrous finish.
2. 2. - The method according to claim 1, characterized in that the strip is stretched at least about 1%.
3. 3. - The method according to claim 2, characterized in that the strip is stretched 2 to 7%.
4. 4. - The method according to claim 1, characterized in that the cold reduced strip has a roughness less than 0.4 micro Ra.
5. 5. - The method according to claim 4, characterized in that the strip reduced in cold had a roughness less than 0.3 micro Ra.
6. 6. - The method according to claim 1, characterized in that there are at least three cleaning brushes adjacent to each strip surface.
7. 7. - The method according to claim 1, characterized in that the cleaning brushes have a surface density greater than 12% unit square surface area.
8. 8. - The method according to claim 7, characterized in that the bristles are wide and have a diameter of .13 to .25 mm.
9. 9. - The method according to claim 1, characterized in that the strip has a roughness less than 2.0 micro Ra before cold reduction.
10. 10. The method according to claim 9, characterized in that the strip has a roughness no greater than 1.0 micro Ra before cold reduction.
11. 11. The method according to claim 1, characterized in that at least 95% of the particles have a size of at least 10 mm.
12. 12. - The method according to claim 1, characterized in that no more than 5% of the particular has a size greater than 0.50 mm.
13. 13. The method according to claim 1, characterized in that at least 45% to 55% of the particular ones have a size of .20 or .30 mm.
14. 14. - The method according to claim 1, characterized in that the cleaned surfaces with brush have a roughness less than 3.6 micro Ra.
15. 15. The method according to claim 14, characterized in that the cleaned surfaces have a roughness not greater than 3.0 micro Ra.
16. 16. The method according to claim 1, characterized in that the strip is cold reduced at least 30%.
17. 17. - The method according to claim 16, characterized in that the strip reduced in cold has a flatness no greater than 20 units I.
18. 18. - The method according to claim 1, characterized in that the strip is made of stainless steel.
19. 19. A method for producing a strip of cold-rolled metal from hot-processed uncooled or acid-stripped metal from the hot-processed strip before cold-rolling, characterized in that it comprises: providing a strip of processed steel in hot cover with incrustation, stretch the strip in tension at least 1% to crack the scale and flatten the strip, injection of jet of particles to the surfaces of the elongated strip to remove the encrustation, clean the surfaces to remove any residual encrustation with at least two cleaning brushes placed adjacent to each surface and turned in opposite directions to each other, the cleaning brushes have bristles with a diameter of .13 to .50 mm, polish each surface clean with at least one polishing brush, so that the surfaces of the strip have roughness less than 2.0 micro Ra and cold reduce the strip so that the surfaces have a glossy finish with roughness less than 0.4 micro Ra.
20. 20. A method for producing a strip of cold-rolled metal from hot-processed metal without annealing or acid stripping of the hot-processed strip before cold-rolling, characterized in that it comprises: providing a strip of processed stainless steel in hot cover with inlay, stretch the strip in tension at least 1% to crack the scale and flatten the strip, inject the surfaces of the elongated strip with a stream of particles to remove the scale, clean with at least two cleaning brushes the surfaces to remove any residual scale, placed adjacent to each surface and rotated in opposite directions to each other, the cleaning brushes have a surface density greater than 12% of square unit surface area, and have wire bristles with a diameter of .13 to .50. mm, polish each clean surface with at least one polishing brush, so that the surfaces of the strip have a roughness not greater than 1.5 micro Ra, and cold reduce the strip in such a way that the surfaces have a glossy finish with a roughness no greater than 0.3 micro Ra.