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WO2003051549A1 - Cylindre de travail pour laminage a froid de metal - Google Patents

Cylindre de travail pour laminage a froid de metal Download PDF

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Publication number
WO2003051549A1
WO2003051549A1 PCT/GB2002/005720 GB0205720W WO03051549A1 WO 2003051549 A1 WO2003051549 A1 WO 2003051549A1 GB 0205720 W GB0205720 W GB 0205720W WO 03051549 A1 WO03051549 A1 WO 03051549A1
Authority
WO
WIPO (PCT)
Prior art keywords
work roll
modulus
intermediate layer
roll
young
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/GB2002/005720
Other languages
English (en)
Inventor
Christopher John Davenport
David John Browne
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Rio Tinto Alcan International Ltd
Original Assignee
Alcan International Ltd Canada
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Alcan International Ltd Canada filed Critical Alcan International Ltd Canada
Priority to AU2002352405A priority Critical patent/AU2002352405A1/en
Publication of WO2003051549A1 publication Critical patent/WO2003051549A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B27/00—Rolls, roll alloys or roll fabrication; Lubricating, cooling or heating rolls while in use
    • B21B27/02—Shape or construction of rolls
    • B21B27/03—Sleeved rolls
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B27/00—Rolls, roll alloys or roll fabrication; Lubricating, cooling or heating rolls while in use

Definitions

  • the present invention relates to a work roll for use in the cold rolling of metal.
  • the invention is particularly, but not exclusively, useful in the production of aluminium or aluminium alloy foil especially when closed gap rolling is used.
  • the term metal as used in this specification is intended as reference to a metal and/or its metal alloy.
  • the metal may be aluminium or an aluminium alloy, particularly foil alloys such as AA8006, AA1045 or AA1200.
  • Methods of cold rolling metal sheets or strips to form metal foil are well known in the art, and make use of work rolls made of steel having a Young's modulus of just over 200 GPa. The metal sheet initially undergoes open gap rolling until it is thin enough to necessitate closed gap rolling.
  • US 3,503,242 describes a composite work roll which is designed to overcome the problem of flatness in the rolled product.
  • the roll is designed to elastically deform locally to correct local off-flatness in the product.
  • the roll comprises an outer sleeve of hard material separated from a central arbour by a layer of low modulus resilient material such as hard rubber or other elastomer, polyurethane, neoprene butadiene-styrene or similar elastomeric materials.
  • low modulus resilient material such as hard rubber or other elastomer, polyurethane, neoprene butadiene-styrene or similar elastomeric materials.
  • a further disadvantage is that presently the speed of the mill is used to control the exit gauge of the foil.
  • the rolls are freshly ground and the friction between the rolls and the foil is high, the sheet can be rolled faster.
  • the work rolls wear, they become smoother and the friction decreases.
  • the mill must be slowed down, thus limiting its productivity.
  • Much effort is presently spent on maintaining a high friction by the use of various roll grinding techniques.
  • the work rolls wear smooth they must be removed from the mill and be re-ground to regain their high friction properties. In most foil mills, rolls may have to be re-ground after only a few hours of use.
  • a work roll for use in the reduction of the thickness of metal sheet, said work roll having a composite structure consisting of a cylindrical core, to which is secured by way of an intermediate layer a cylindrical outer layer, and wherein the intermediate layer is made of a material having a low Young's modulus such that the effective Young's modulus of the work roll is in the range 40 GPa to 190 GPa.
  • the Young's modulus of the material of the intermediate layer is low in comparison to that of the outer layer.
  • the Young's modulus of the intermediate layer is less than 20 GPa which covers resilient materials such as plastics or rubber and hardenable or cureable materials such as adhesives.
  • the Young's modulus of the material of the inner layer is in the range 1 GPa to 10 GPa, more preferably in the range 2 GPa to 7 GPa.
  • a particularly useful material for the intermediate layer has been found to be adhesive.
  • Young's modulus is an inherent property of a material: for example the Young's modulus for steel is about 210 GPa, whilst for aluminium it is about 70 GPa. Compliance is a property of a structure, being directly related to the displacement (of the structure) in response to a given load applied thereto. Compliance is dependent therefore not just on the inherent properties of the materials making up the structure - in this case the Young's modulus - but also on the structure itself and in particular, its geometry.
  • the compliance of a work roll is the deformation of the roll h divided by the roll pressure p, and is defined as follows: h
  • compliance can be regarded as directly related to Young's modulus but it should be noted that the compliance of a work roll will change if its geometry is changed and in particular if its diameter is changed. Thus, in the present discussion, it is assumed that the geometric properties of the work roll, and in particular its diameter, are constant. The effect of roll diameter on speed of rolling will be discussed specifically below.
  • the compliant rolls are positioned, in use, such that opposing edge regions of their circumferential surfaces are touching the corresponding edge regions of the other work roll or rolls (closed gap rolling).
  • the compliant rolls are positioned in use such that their opposing edge regions are close to touching, but not touching, the corresponding edge regions of the other work roll or rolls (near closed gap rolling).
  • the compliant rolls may be used in combination with speed control to achieve the desired thickness of foil.
  • the compliant rolls allow a higher speed to be used to obtain a given thickness.
  • Young's modulus is a material property and is thus not easily altered for a given material.
  • the invention uses a composite work roll that has an effective Young's modulus which is very different from that of solid steel.
  • Such a composite work roll is fabricated as a core on which is mounted at least two cylindrical layers.
  • the outer layer that which forms the work surface of the roll, is made from a relatively hard material such as steel or chrome to act as a wear resistant surface to the roll.
  • the outer layer Underneath the outer layer is an intermediate layer of compliant material having a low Young's modulus, and it is the existence of this compliant layer that gives the work roll, as a whole, its compliance. Controlling the thickness of the outer layer (which is assumed to have a high Young's modulus) and the intermediate layer (which is assumed to have a low Young's modulus) enables the degree of compliance to be adjusted.
  • the core may be made of hard material such as steel, and the compliant intermediate layer lies between the core and the outer layer. Still further layers may be used, if needed to achieve particular characteristics.
  • the thickness of the intermediate layer should be less than that in the arrangement described in application No. PCT/GB01/02787. There are two conflicting requirements to consider in setting this thickness.
  • the intermediate layer must be sufficiently thin to provide enough rigidity to transmit the mill load and the rolling torque.
  • the rolling torque in aluminium foil rolling is actually surprisingly low, typically 3kNm.
  • the intermediate layer needs to be sufficiently thick to exhibit sufficient compliance for a given thickness of the outer layer.
  • the absolute minimum thickness of the intermediate layer is probably about 30 ⁇ m, with a preferred minimum thickness at about 50 ⁇ m; however, there are difficulties at such thicknesses in ensuring an even and complete layer of material, for example adhesive, and therefore a probable more realistic minimum thickness is about 100 ⁇ m, more preferably about 500 ⁇ m.
  • the upper limit on the thickness could be as high as 5 mm, but a preferred upper limit is 2 mm, even more preferably, 1 mm. In some instances, the upper limit will be even lower than this, perhaps down to 500 ⁇ m.
  • the difference in thermal expansion coefficients between aluminium and steel, combined with the relatively high thermal expansion coefficients of materials such as rubber, plastics or adhesives when used as the intermediate layer means that it is possible during rolling operations where the temperature increases, that significant thermal stresses may build up in the composite roll. Even with the relatively low shear strengths of the materials mentioned above as suitable for use as an intermediate layer, it is possible that the shear stresses generated in this way could lead to shear failure of the adhesive along the length of the roll.
  • another embodiment of the intermediate layer is to taper its thickness along the length of the roll such that it is thicker towards the outer edges than in the middle.
  • This tapering may take various forms, such as a continuous taper from each end of the roll towards the middle.
  • the tapers from the two ends may meet in the middle, or there may be a constant thickness section in the middle, with the tapering sections being confined towards the respective ends.
  • this is essentially an edge effect (i.e. affects primarily the edges of the sheet) the tapering sections can in practice be confined towards the ends of the roll, across which the respective edges of the sheet pass.
  • a work roll having a composite structure such as discussed above will have a Young's modulus which is the resultant of the Young's modulus of the component materials making up the roll.
  • Such a work roll is said to have an effective Young's modulus such that the elastic response of the composite roll to an applied load is the same as that of a solid roll of the same external dimensions made of a material having a Young's modulus equal to the effective Young's modulus.
  • Figure 1 is a cross-sectional view of closed gap rolling of metal sheet taken perpendicular to the direction of travel of the metal sheet;
  • Figure 2 is a diagram illustrating how an effective Young's modulus may be calculated;
  • Figure 3 is a cross-sectional view of an embodiment of a compliant roll having a composite structure in accordance with the present invention
  • Figure 4 is a graph of throughput normalised speed against normalised effective Young's modulus
  • Figure 5 is a cross-sectional view of a compliant roll taken perpendicular to its axis of rotation showing the distribution of stresses in the roll of the present invention.
  • a compliant roll 1 having a composite structure.
  • the roll consists of a cylindrical core 12 of steel, a coaxial intermediate layer 13 made of a low Young's Modulus material, and a work surface defined by a cylindrical outer layer 14 made of a higher Young's modulus material such as steel or chrome.
  • the intermediate layer 13 has a uniform cross section along the length of the roll - i.e. its radial thickness is the same at all points along the roll.
  • the intermediate layer 13 is formed from a hardenable material such as adhesive.
  • the particular adhesive used is LoctiteTM 635 which has a Young's modulus of 2.5 GPa and a shear strength of 31 N/ m m 2 , but other adhesives could be used.
  • the adhesive is applied in the form of a liquid which hardens or cures.
  • a problem may occur in centering the core within the outer layer to ensure an adhesive line of uniform thickness.
  • the adhesive may be liquid during assembly and the core could move off-centre, which would be very undesirable.
  • a spacing means is used to hold the assembly in alignment. Suitable means could be dimples on the exterior surface of the core or the interior surface of the outer layer that act to hold the two apart. Helical spacers along the length of the core, or the outer layer, would do the same job.
  • particles in the adhesive such as polythene spheres, having a size equal to the required spacing could be used.
  • the spacing means is made from a material having a relatively low Young's modulus that comes close to matching that of the adhesive.
  • Figure 4 illustrates more directly the effect of different effective Young's moduli on the speed of closed gap rolling.
  • the horizontal axis of the graph is a dimensionless quantity representing the measured effective Young's modulus compared with that of solid steel.
  • the graph is valid for all rolls within the normal expected size range and all representative loads.
  • the three curves coincide for mill loads of 0.5 to 0.7 kN/mm, these values being typical of those found in closed gap foil rolling. Mill load is expressed as load in kN per unit width of the roll.
  • the amount of roll flattening is also affected by the local pressure between the sheet and work rolls. This pressure decreases with increasing speed. Thus, increasing speed decreases roll flattening and decreases the rolled thickness. Because of this effect, speed is normally used to control the gauge of the sheet. Going faster makes the sheet thinner, going slower makes the sheet thicker. Making the work rolls more compliant, as in the present invention, allows the same gauge of foil to be rolled with the mill running faster. This has great productivity benefits.
  • the effect of changing the Young's modulus of the work roll is illustrated below in the table of results from a theoretical model according to the present invention.
  • Figure 5 which illustrates a portion of the outer shell 14 of the roll. It can be seen that the stresses from contact with the metal sheet are very intense in the locality 15 of the contact, but are also present in the substrate. The characteristics of the substrate will therefore influence the effective Young's modulus of a composite roll.
  • the method of the present invention may also be applied advantageously to near closed gap rolling and to open gap cold rolling.
  • Near closed gap rolling refers to when the work rolls are positioned in use such that the opposing edges of their circumferential surfaces are very close but not touching.
  • Compliant rolls may also be used when metal sheet is pack rolled, thereby minimising the number of passes needed for producing foil of a required gauge.
  • Pack rolling is the process where a sandwich of two or more layers of metal sheet is fed into the roll gap between the work rolls. On separating the two or more sheets, the sides in contact with the rolls have a shiny surface and the inner surfaces are matt.
  • Back tension is about twice as effective in reducing the rolling load as front tension. It is therefore preferred to have a back tension applied to the metal sheet during the rolling process.
  • a mill with four high stands with work rolls having small diameters of typically between 200 to 450mm and back up rolls having diameters of typically between 800 and 1000mm.
  • work rolls having small diameters of typically between 200 to 450mm and back up rolls having diameters of typically between 800 and 1000mm.
  • Using small diameter work rolls helps to reduce the rolling load through a reduced arc of contact between the strip and the work rolls.
  • the present invention is not restricted to the use of four high mills and other types of mills may be used advantageously.
  • roll diameter being a component of the overall compliance of the roll, will also have an effect on the speed of rolling.
  • the effect of roll diameter on the speed of rolling in closed gap mode is very similar to that of effective Young's modulus.
  • a 10% decease in effective Young's modulus would give the same effect as a 10% increase in roll diameter.
  • mills are designed to run with only a very small range of roll diameters, it is much more convenient to use the effective Young's modulus than the roll diameter as a means of speed increase.

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  • Physics & Mathematics (AREA)
  • Geometry (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Reduction Rolling/Reduction Stand/Operation Of Reduction Machine (AREA)

Abstract

L'invention a trait à un cylindre de travail amélioré, qui est destiné en particulier au laminage à ligne de contact fermée, et présente une structure composite comprenant une couche extérieure cylindrique (14) en acier, ladite structure constituant la surface de travail du cylindre, séparée d'un noyau en acier (12) par une couche intermédiaire (13) faite d'un matériau ayant un faible module de Young. Généralement, la couche intermédiaire (13) a un module de Young compris entre 1 GPa et 10 GPa, et peut, par exemple, être faite de caoutchouc ou de matière plastique, ou d'une matière durcissable telle qu'un adhésif. L'épaisseur radiale de la couche intermédiaire (13) est assez faible inférieure à 5 mm et de préférence inférieure à 1 mm. Si l'on choisit les dimensions de la couche extérieure (14) et de la couche intermédiaire (13) de manière appropriée, cette combinaison permet d'obtenir un cylindre de travail ayant un module de Young efficace, inférieur à celui de l'acier, mais qui présente toutefois les mêmes avantages qu'une surface de travail en acier et qui permet des vitesses de laminage plus élevées.
PCT/GB2002/005720 2001-12-19 2002-12-17 Cylindre de travail pour laminage a froid de metal Ceased WO2003051549A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU2002352405A AU2002352405A1 (en) 2001-12-19 2002-12-17 A work roll for use in cold rolling of metal

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB0130334A GB0130334D0 (en) 2001-12-19 2001-12-19 A work roll for use in cold rolling of metal
GB0130334.6 2001-12-19

Publications (1)

Publication Number Publication Date
WO2003051549A1 true WO2003051549A1 (fr) 2003-06-26

Family

ID=9927917

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB2002/005720 Ceased WO2003051549A1 (fr) 2001-12-19 2002-12-17 Cylindre de travail pour laminage a froid de metal

Country Status (3)

Country Link
AU (1) AU2002352405A1 (fr)
GB (1) GB0130334D0 (fr)
WO (1) WO2003051549A1 (fr)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3503242A (en) * 1967-04-20 1970-03-31 Natalis H Polakowski Mill rolling machine
SU1729639A2 (ru) * 1990-07-30 1992-04-30 Череповецкий Металлургический Комбинат Им.50-Летия Ссср Прокатный валок
JPH11144717A (ja) * 1997-11-12 1999-05-28 Sumitomo Metal Ind Ltd 粉末層の高密度化方法と圧延用ロール

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3503242A (en) * 1967-04-20 1970-03-31 Natalis H Polakowski Mill rolling machine
SU1729639A2 (ru) * 1990-07-30 1992-04-30 Череповецкий Металлургический Комбинат Им.50-Летия Ссср Прокатный валок
JPH11144717A (ja) * 1997-11-12 1999-05-28 Sumitomo Metal Ind Ltd 粉末層の高密度化方法と圧延用ロール

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 1999, no. 10 31 August 1999 (1999-08-31) *

Also Published As

Publication number Publication date
AU2002352405A1 (en) 2003-06-30
GB0130334D0 (en) 2002-02-06

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