EP1682288B1 - Method and device for applying an adjustable tensile-stress distribution, in particular in the edge regions of cold-rolled metal strips - Google Patents

Abstract

The invention relates to a method and a device for applying an adjustable tensile-stress distribution, in particular in the edge regions during the cold-rolling of metal strips ( 16 ), in particular metal foil, in order to reduce the risk of an excessive build-up of tension and cracks at the edges of the strip, which can lead as a negative consequence to cracks in the strip and to a reduction in production, and in order to improve the surface of the strip and its planarity, even for a relatively high strip displacement speed, and also to reduce strip trimming widths. To achieve these aims, at least one or a combination of two of the following measures are implemented: a) separation of lubrication and cooling of the working rolls by lubricating on the run-in side and cooling on the discharge side, b) additional influencing of the strip edges using a hot edge spray", in particular by spraying ( 21 ) rolling oil with differing temperatures in zones, c) use of a special cross-sectional configuration of the working rolls ( 12, 12 ') in the vicinity of the strip edges, which creates a partial material build-up during the blooming pass, said build-up forming a longer strip edge with subsequent passes, thus counteracting the risk of an excessive build-up of tensile stress.

Description

The invention relates to a method for applying a controllable tensile stress distribution, especially in the edge regions during cold rolling of metal strips, in order to reduce the risk of too high tensile structure and band edge cracks with the adverse consequence of production-reducing band breaks, and to improve the strip surface and its flatness even at relatively higher Tape speed and to reduce Bandbesäumbreiten, according to the preamble of claim 1 (see, eg JP-A-62142011 ). The invention also relates to an apparatus for carrying out the method, according to the preamble of claim 5.

From the document EP 0 054 172 A2 a method is known in which for the tension-free rolling of cold strip, the coefficient of friction between the strip surfaces and the roll barrel lateral surfaces is influenced by the application of rolling lubricant. This is supplied as a function of located behind the last framework in the transverse direction of the belt zones determined partial tensile stresses. Here, base oil is applied to the rolling lubricant before the inlet of the strip in the nip in determined by the determined partial tensile stresses and in localized areas directly on the belt surfaces. The aim of this measure is to locally apply the lubricating components on strips of the strip to be rolled in order to reduce the local rolling force by the locally improved lubrication and thus also to reduce the local flattening of the roller. Furthermore, the friction heat introduced into the roll is reduced at these points.

From the document EP 0 367 967 B1 a method and a device is known in which the concentration of an emulsion of rolling oil specifically influenced and the emulsion or dispersion after exiting the nip or

Process is collected before the nip and separated again. This makes it possible to produce the emulsion or dispersion, which is introduced into the nip, time and again with a certain concentration before moving into the nip. The focus of this invention is the actual production of the emulsion and the separation of the involved media.

The document EP 1 188 494 A1 describes a belt scraper, belt scraper method, rolling mill and rolling method. To improve the productivity of a cold rolling device, this was provided with a belt scraper.

In high-speed rolling of more than 700 m / min, which was not feasible with conventional scraper rollers or tube scrapers, the productivity of the cold rolling device and the surface quality of a strip were significantly improved by adding the scraper.

The document EP 0 672 471 B1 discloses a method and apparatus for rolling ribbons. As rollers wear-resistant, at least in one of its end regions with enlarged radii running rollers are shifted from each other so that the rolled strip in its width in each case with areas of smaller radius in contact, and that with increasing heating and with thermal crowning by opposing displacement of the rollers Regions of their larger radius are pushed over edge regions of the rolled strip. As a result, it is achieved that the edge area elevations of the strip, which would occur due to the rising thermal crowning, are eliminated.

The document DE 199 08 743 A1 discloses a method and an apparatus for drying and keeping dry, in particular cold strip in the outlet area of cold rolling and strip lines. In the drying and keeping dry particular of rolled strips, it is known by a partitioning the dry area of the finished rolled strip from the wet room of Separate rolling stand. For this purpose, a non-contact seal between the foreclosure and the tape by an air cushion-like compressed gas cushion and a slit flow is proposed so as to apply compressed gas from a plurality of nozzles from Blasdüsenleisten at right angles from above and below the tape surfaces.
This measure prevents penetration of rolling oil or even emulsion at high belt speeds of over 1000 m / min, irrespective of the bandwidth, and achieves non-contact belt drying.

The document DE 101 31 369 A1 discloses a method and apparatus for cooling and / or lubricating rolls, in particular the work rolls of a rolling stand and a rolled strip conveyed between and conveyed through these rolls, using water in the form of sprays as cooling medium and spray oil, oil-air mixture or oil -Water mixture, as a lubricant. To improve the lubricating and cooling effect, a combined use of supercooling of the belt and roll surface and the roll lubrication on the scaffold inlet side is proposed by the two media - water or lubricant - the rolls or the strip fed separately and to different application sites of the rolling surface be applied. For water or lubricant separate reservoirs and separate feeds to the spray bar for water and to the spray bar for the lubricant are provided. With great advantage, this results in an optimal use of each lubricating or cooling effect of the two media water and lubricant and thus at the same time a reduction in force and labor requirements, due to minimized friction coefficients on the rollers. The ground surface of the roller withstands even the highest demands. The previously observed Materialabschälungen on the rollers are suppressed. The surface of the rolled strip remains optimally smooth, scales and chatter marks on the strip surface are eliminated.

The European patent EP 0 672 471 B1 discloses a method and apparatus for rolling belts with axially displaceable rollers. The method is characterized in that low-wear, executed with at least at one of its end portions with enlarged radii rollers are shifted against each other such that the rolled strip is in its width in each case with areas of smaller radius in contact and that with increasing heating and with thermal crowning By oppositely moving the rollers and areas of the rollers with a larger radius are pushed over edge regions of the rolled strip. This method is used to counteract the annoying, thermal crowning effect simply and inexpensively, in order to make rolling plans more free.

The U.S. Patent 5,943,896 discloses a method for influencing the contour of a rolled strip in the edge region. For this purpose it is proposed to use continuously variable crown CVC work rolls with a special unsymmetrical cut. According to this finish, each work roll has a smaller diameter portion at one end than at the other end thereof, the smaller end portion being shorter than the large diameter portion across the width of the work roll. In a transition region, for example, the diameter of the work roll linearly changes from the small diameter to the larger diameter. During the rolling operation, the two superposed rollers are arranged so that the thinner end of the one roller is opposite to the thicker end of the other roller.

The Japanese godparent application JP 05050122 discloses an apparatus and method for realizing a sharply separated heat transfer between different temperature ranges on the surface of a work roll.

The Japanese application 03297507 discloses a method for detecting the occurrence of stresses in the edge regions of a rolled strip and an extension to prevent the edge areas. For this purpose, it is proposed to apply a cold coolant in the region of the center of the rolled strip, that is to say not in its edge regions, and at the same time to apply a warm coolant in the edge regions and outside thereof.

The German patent application DE 31 144 87 A1 discloses a method and apparatus for roll tempering in cold rolling mills. In order to avoid the occurrence of high edge tensions during rolling of fine strips and films, it is proposed that a roll area which lies outside the strip edge and adjoins directly to the strip edge be tempered by applying heated lubricant. A relatively sharp borderline between hot and cold lubricant jet is set. The position of this boundary line should coincide with the position of the band edge.

Finally, it is from the generic Japanese patent application JP 62142011 Known to separate cooling and lubrication of work rolls by applying only rolling oil on the input side and only coolant on the output side. In this way, the contour of a rolled metal strip is improved.

Based on the above-mentioned prior art, the invention is in the cold rolling, especially in the aluminum industry, but occasionally in the steel and non-ferrous metal area, the task of further reducing the resulting during thin rolling strip edges and near-edge long strip fibers and tape cracks on To further save edgebandings and thereby further improve the quality and quantity of application.

This object is achieved by the method claimed in claim 1. This method is characterized in that the strip edges are influenced by "hot edge spray", in particular by zonewise spraying of rolling oil at different temperatures, and in the Work rolls in the Beriech the band edges a special finish is used, which is suitable for partial buildup of material in the prestretch, the material structure in subsequent stitches leads to a longer band edge and counteracts the risk of high Zugaufbaues.

With the aid of the measures according to the invention, the risk of ligament tear is clearly reduced by band edge tears and, in addition, the strip surface is improved.

By adjustable tension distribution, especially in the band edge area, a higher material throughput is easily achieved while reducing non-productive times at an increased operating speed. Overall, the flatness is significantly improved, production increased and rolling oil circulation volumes reduced.

An embodiment of the method according to claim 1 provides that an increased diameter decrease of the work rolls is made at the edge region due to partial increase in diameter during their shaping by means of inductive heating.

Furthermore, it can be made use of the measure that the strip tension distribution is changed by a concave bendable or curved guide roller such that the tape tension is reduced at the strip edges and increased in the center of the strip.

Finally, use may be made of the further measure that, in the case of pre-stitches, material is built up at the edge of the strip by means of "edge sprays" with lubricant of relatively higher viscosity.

The above object is further achieved by a device for establishing a controllable tensile stress distribution with the features of claim 5. The with this device Associated advantages have been previously described in the inventive method.

Another embodiment of the device advantageously includes a convexly bendable in the belt running direction or curved steering roller in an arrangement between two guide rollers for changing the tensile stress distribution of a strip before its entry into a rolling stand.

In addition to this, the device is further configured by the fact that they are on the inlet side of a rolling mill means for direct additive application, in particular on the rolled strip z. B. for lubricating oil with relatively high viscosity, and on the outlet side of the work rolls means for bale cooling of the work rolls and preferably additional lubricant removal means which spray the rolled strip with preference from both the tape top and from the underside of the band with the attributable spray media.

And finally, the device according to the invention has a device which removes coolant in the outlet side of the scaffold.

Further details, features and advantages of the invention will become apparent from the following explanation of an embodiment schematically illustrated in the drawings.

Figur 1

eine Vorrichtung für "Hot Edge Spray" an der Walzenkante

Figur 2

einen Spezialschliff für Arbeitswalzen

Figur 3

In Seitenansicht eine konvex biegbare bzw. gebogene Lenkrolle

Figur 4

Die Draufsicht auf die Lenkrolle gem. Fig. 3

Figur 5

In Seitenansicht eine erfindungsgemäße Anlage mit Direktauftragung von Schmiermittel auf das Walzband, auslaufseitiger Walzenkühlung und Schmiermittelentfernung.

Show it:

FIG. 1

a device for "hot edge spray" on the roll edge

FIG. 2

a special grinding for work rolls

FIG. 3

In side view a convex bendable or curved steering roller

FIG. 4

The top view of the steering role gem. Fig. 3

FIG. 5

In side view, a plant according to the invention with direct application of lubricant to the rolled strip, outlet side roll cooling and lubricant removal.

FIG. 1 shows a part of a device for applying a controllable tensile stress distribution, in particular in edge regions during cold rolling of metal strips, with in at least two separate zones 10, 10 'existing spray nozzle assemblies 11, 11' with connections to separate Sprühmittelzuführungen 19, 19 'to different zones 10, 10th In addition, there is the possibility of a partial inductive heating of the work roll in a conventional manner.

FIG. 2 shows a pair of work rolls 12, 12 ', each having in one end a special grinding 13, 13' with increases in diameter in the end regions for extending the strip edges to be rolled with simultaneous reduction of tensile stresses and reduction of long strip fibers.

The FIGS. 3 and 4 show together in side view and plan view of an arrangement for extending the tensile stress distribution over the bandwidth in ready-stitching. This is achieved by a variable wrap angle W at strip thicknesses: 1 - 6 μm with W = 60 - 90 ° 8-20 μm with W = 45 - 60 ° > 20 μm W = 45 ° and above in the case of metal foils W = 15 - 20 °

FIG. 5 shows a side view of an inventive system, with a decoiler on the left side and a Aufrollhaspel on the right and guide means for the rolled strip 16 in the direction of belt 14 and means 21 for direct application of lubricant with viscosity or additive on the band inlet side and means 22 for bale cooling the outlet side work rolls and means 23 for the outlet side lubricant removal. Thus, a material build-up at the strip edge during the pre-stitching and correspondingly a material removal at the strip edge during the finishing passes is achieved with the aid of an additive direct application in the inlet side and roll cooling in the outlet side.

LIST OF REFERENCE NUMBERS

10, 10 '

spray zone

11, 11 '

spray nozzle

12, 12 '

strippers

14th

Tape direction

15th

castor

16th

tape

17th

leadership

19. 19 '

Sprühmittelzuführung

20th

rolling mill

21st

Additive-application

22nd

Ball coolant

23rd

Schmiermittefentfernung

Claims (8)

1. Method for applying a regulable tensile stress distribution particularly in the edge regions during the cold rolling of metal strips, for the purpose of reducing a risk of excessive build-up of tensile stress and the risk of strip edge cracks, which can have the negative consequence of strip breakages and thus reduced production, and for the purpose of improving the strip surface and its flatness, even at relatively high strip running speed and of reducing strip trimming widths, wherein the method comprises the following step:

   a) separation of lubricant and cooling of work rolls by lubrication at the run-in side and cooling at the runout side,
   and is further characterised by the following additional measures:

   b) influencing of the strip edges by hot edge spray particularly by zonal spraying of rolling oil at different temperatures, and

   c) use of a special cross-sectional configuration of the work rolls in the region of the strip edges for partial material build-up during the roughing pass, which leads to a longer strip edge in subsequent passes and counteracts the risk of build up of a high tensile stress.
2. Method according to claim 1 or 2, characterised in that a greater diameter reduction of the work rolls is undertaken at the edge regions due to partial diameter increase during shaping by inductive heating.
3. Method according to claim 1 or 2, characterised in that the strip tensile stress distribution is varied by a concavely bendable or bent deflecting roll in such a way that the strip tensile stress is reduced at the edges of the strip and increased in the centre of the strip.
4. Method according to one or more of claims 1 to 3, characterised in that in roughing passes, material is built up at the edges of the strip by edge sprays with lubricants of relatively high viscosity.
5. Device for developing an regulable tensile stress distribution, particularly in edge regions during the cold rolling of metal strips, preferably for performance of the method according to the preceding claims, wherein the device comprises at least one spray nozzle system (11, 11') on the run-in side for applying lubricant and means for cooling the barrels of the work rolls on the runout side; characterised in that
   at least two of the spray nozzle systems (11, 11') with connections for separate spray medium feeds (19, 19') are present for spraying the lubricant in the form of rolling oil at different temperatures in different zones (10, 10') of each work roll (12); and that
   each of the work rolls (12, 12') has a special cross-section (13, 13') with increased diameters in the end regions thereof for the purpose of lengthening the rolled strip edges with simultaneous reduction of tensile stresses and reduction of long strip fibres in regions near the edges of the strip.
6. Device according to claim 5, characterised by a deflecting roll (15) that is convexly bendable or bent in the strip running direction (14) and is arranged between guide rolls (17) to change the tensile stress distribution of a strip (16) before it enters a rolling stand (20).
7. Device according to claim 5 or claim 6, characterised in that on the run-in side of a rolling stand (20) it has means (21) for the direct application of additive, particularly to the rolled strip (16), for example lubricating oil with relatively high viscosity, and on the runout side of the work rolls (12, 12') it has means (22) for cooling the barrels of the work rolls and preferably additional means (23, 23') for removal of the lubricant, which advantageously spray the rolled strip (16) from both the strip upper side and the strip lower side with the associated spray media.
8. Device according to one of more of claims 5 to 7, characterised in that it has a device that removes coolant in the runout side of the stand (20).

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