EP0046423B2 - Method of executing the skin pass at a regulated rate in the rolling of steel strips annealed in a furnace - Google Patents

Method of executing the skin pass at a regulated rate in the rolling of steel strips annealed in a furnace Download PDF

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Publication number
EP0046423B2
EP0046423B2 EP81401230A EP81401230A EP0046423B2 EP 0046423 B2 EP0046423 B2 EP 0046423B2 EP 81401230 A EP81401230 A EP 81401230A EP 81401230 A EP81401230 A EP 81401230A EP 0046423 B2 EP0046423 B2 EP 0046423B2
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Prior art keywords
rolling
strip
strips
elongation
annealed
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German (de)
French (fr)
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EP0046423B1 (en
EP0046423A1 (en
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Pierre Gombaud
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FORGES DE BASSE-INDRE Ste
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FORGES DE BASSE-INDRE Ste
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B21MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21BROLLING OF METAL
    • B21B1/00Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
    • B21B1/22Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length
    • B21B1/24Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length in a continuous or semi-continuous process
    • B21B1/28Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length in a continuous or semi-continuous process by cold-rolling, e.g. Steckel cold mill
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B21MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21BROLLING OF METAL
    • B21B37/00Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
    • B21B37/56Elongation control
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B21MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21BROLLING OF METAL
    • B21B45/00Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
    • B21B45/02Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills for lubricating, cooling, or cleaning
    • B21B45/0239Lubricating
    • B21B45/0245Lubricating devices
    • B21B45/0248Lubricating devices using liquid lubricants, e.g. for sections, for tubes
    • B21B45/0251Lubricating devices using liquid lubricants, e.g. for sections, for tubes for strips, sheets, or plates
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B21MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21BROLLING OF METAL
    • B21B45/00Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
    • B21B45/02Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills for lubricating, cooling, or cleaning
    • B21B45/0269Cleaning
    • B21B45/0275Cleaning devices
    • B21B45/0278Cleaning devices removing liquids
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B21MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21BROLLING OF METAL
    • B21B27/00Rolls, roll alloys or roll fabrication; Lubricating, cooling or heating rolls while in use
    • B21B27/005Rolls with a roughened or textured surface; Methods for making same

Definitions

  • the invention relates to a method of work hardening by rolling strips of mild steel intended in particular for the manufacture of packaging, this work hardening taking its place in the manufacture of strips, where sheets in coils from steel of grades intended for continuous casting are brought substantially to strip thickness by a first cold rolling, annealed so as to remove the structural anisotropies generated by the first rolling, then hardened by a second rolling so as to bring the strip metal at selected hardness. More specifically, the method is intended to give strips annealed in a bellows a hardness comparable to that of strips annealed continuously and work-hardened by dry rolling with an elongation of less than 2%.
  • the invention takes its place in the technological development of the production of steel strips intended mainly for the manufacture of packaging, in the form of tin and black iron, that is to say strips laminated to cold with nominal thicknesses ranging from 0.15 to 0.49 mm, in accordance with ISO 1111/11 (1976).
  • tinplate is meant strips or sheets covered with tin, and by black iron corresponding strips not tinned, either at the stage before tinning, or intended for the manufacture of articles protected by various surface treatments.
  • the invention relates to the development of strips in the state of black iron, at a stage preceding the tinning of white iron or any other surface treatment.
  • the strips are produced from coils of sheets of the order of 2 mm, which undergo a first cold rolling, during which the sheets are reduced in thickness with a corresponding elongation, to give strips whose thickness is substantially the final thickness of the strip of black iron.
  • the strips are then annealed under a protective atmosphere, to remove the structural anisotropies caused by the first rolling, where the metal has undergone considerable elongation giving it a fibrous crystalline structure.
  • the metal is too soft for processing by deformation. It is therefore subjected to a second rolling with low elongation, to work harden and give it the hardness required for subsequent shaping. This second rolling, hardening, also perfects the finish of the strips.
  • the sheets themselves were produced by hot rolling of slabs.
  • slabs were obtained from steel cast in molds.
  • the annealing of the strips after the first cold rolling was carried out in a closed coil.
  • the grades of steel used were such that the second rolling, hardening, gave the strips a suitable hardness with an elongation of approximately 1 to 2%.
  • continuous annealing techniques have been developed, where the strip, after having undergone a first rolling, passes through an annealing furnace, before re-reeling for the second hardening rolling. This continuous annealing is carried out much faster than the conventional annealing in a coil under chloche, and notably includes brief heating and cooling phases.
  • the crystalline structure of the steel after continuous annealing is much finer than after annealing in a bell, with as a consequence a higher hardness, which obviously affects the hardness of the strip after hardening rolling. Consequently, the grades of continuous casting steels of the coil sheets intended for the production of black iron strips have been modified by reduction of the content of hardening elements, in order to obtain suitable hardnesses of the black irons in the strip produced according to the continuous casting processes of steels, and the continuous annealing of strips after the first rolling. It will be noted that the use of milder grades of steel has an obvious advantage for cold rolling, by reducing the energy required to obtain the desired thickness reduction.
  • the main objective of the invention is a method of work hardening of strips coming from steel of grade intended for continuous casting, and annealed in a bell, which gives them a hardness comparable to that of corresponding strips annealed continuously.
  • the object of the invention is also a method of strip hardening which is applicable to conventional rolling mill trains without major transformations.
  • the invention provides an increasing rolling process for the production of strips mild steel intended in particular for the manufacture of packaging, where the coil sheets are brought to substantially strip thickness by a first cold rolling, annealed so as to remove the structural anisotropies generated by the first rolling, hardened by a second rolling with low elongation so as to bring the strip material to selected hardness, this second rolling being carried out with lubrication by spraying an oil-in-water emulsion onto the strip at the entrance to the rolling mill , characterized in that it is intended to impart to strips, coming from steel of continuous casting, and annealed under bell, a hardness comparable to that of continuously annealed strips worked hard by dry rolling with an elongation of less than 2% , process in which the steel strips, which were of quality normally intended to be continuously annealed, and nevertheless were annealed, are run on two bands successive cages so that the resulting elongation is equal to a value chosen between 4 and 20% and obtained for 85-95% in the first cage, at the entrance
  • the aim is essentially an improvement in the finishing of the strips, by reducing the adhesion of residual deposits after annealing in order to avoid superficial encrustation of the residues on the strip, and by reducing the fouling of the rolling mill rolls.
  • lubrication increases the elongation of the strip during work hardening, in particular at high running speeds, while the hardness of the work hardened strip decreases somewhat at equal elongation.
  • the elongations in wet work hardening must not exceed 3%. The opinion of those skilled in the art is that this wet hardening is only of interest for cleaning dirty cylinders.
  • the Applicant has found that it is possible to adjust the rate of work hardening of the strips after annealing under a bell, by correlatively adjusting the rate of elongation when passing through work hardening cages, the final hardness of the strip increasing with the elongation rate, and this final hardness can be reproducibly adjusted with good precision provided that the elongation rate is closely controlled within a range of 4 to 20%.
  • the roughness of the first cage cylinders is between 3.5 and 1 micrometers Ra, while that of the second cage cylinders is between 0.75 and 0.4 micrometers Ra.
  • These roughnesses which correspond to a major part obtained in the first cage, with an effective control of the total elongation relatively rough surface state for the first cage, and a finely rectified state for the second cage, have proved useful for that the elongation is mainly obtained in the first cage, with effective control of the total elongation.
  • elongations of 4 to 20% correspond to thickness reductions respectively of 3.8 to 16.7%, that is to say variations in thickness, for a strip of 0.2 mm thickness respectively from 7.6 to 33.4 micrometers.
  • the only control of thickness, as it is practiced for the reduction of thickness, would be inoperative to regulate the hardness of the strip at the output of work hardening in the required game.
  • the classic work hardening with elongations of less than 2% is located in an area where the final hardness depends little on the elongation, which therefore does not require tight control.
  • the oil in water emulsion used for lubrication is at a content of between 1 and 10% of oil.
  • the washing water between the cages is at around 50 ° C., which corresponds to a good compromise between the requirements for evaporation rate and the absence of prematurely dried zones.
  • washing water will preferably contain approximately 0.2% by weight of sodium nitrite, to passivate the surface of the strip and avoid subsequent oxidation.
  • the rolling mill has two successive stands 11 and 12, the first and second stands in the direction of travel of the strip 10 indicated by the arrow 10a.
  • These cages respectively comprise upper cylinders 11a and 12a and lower cylinders 11b and 12b.
  • the strip 10 to be hardened is cut from a coil 1, which has been previously annealed in a protective atmosphere under a conventional bell.
  • the strip 10 passes over a pair of tension rollers 2, braked to put the strip under tension.
  • the strip engages between the cylinders 11a a and 11b b of the first cage 11, then between the cylinders 12a and 12b of the cage 12, before passing between a pair of tension rollers 4, pous to be wound on a take-up reel 5.
  • the torques exerted on the axes of the tension rollers 2 and 4 are adjusted by servo-control to give the strip a regulated tension, and the speeds and driving torques of the rolls cages 11 and 12 are adjustable in cooperation with the tightening of the cages to adjust the elongations.
  • the cylinders 11a and 11b are preferably ground with a roughness of 3 micrometers Ra, while the cylinders 12a and 12b are ground polished with a roughness of 0.6 micrometers Ra.
  • the roughness Ra is the quadratic mean of the deviations from the real surface to the theoretical surface.
  • the rolling mill was equipped with spraying booms 6 at the entrance to the cage 11, and 7 in the vicinity of the outlet from this cage 11, and with blowing booms 8 at the exit from the cage 12.
  • the booms 6 are supplied at a pressure adjustable from 2 to 5 bars, with water added with approximately 5% of oil, in this case a synthetic oil sold under the name FCF 106 by the company CRODA.
  • the flow rate of the ramps is regulated by the supply pressure, in order to provide, in order of magnitude, 250 g of oil per 1000 m 2 of exposed strip surface (that is to say, counting the two sides).
  • the ramps 7 are supplied with water at a temperature of approximately 50 ° C., at a rate of approximately 0.2 to 0.4 m 3 of eua per 1000 M 2 of exposed strip surface. 5 kg of sodium nitrite are added to the water per cubic meter. Of course, the water which flows from the strip after washing is taken up and treated to be recycled.
  • the blowing by the ramps 8 is carried out with compressed air, and adjusted so that beyond the strip is wet, but not wet.
  • the film deeua which remains on the surface beyond the blowing ramps 8 gradually evaporates to disappear before being wound up on the take-up reel 5.
  • the traction on the strip 10 between the tensioning rollers 2 and 4, the peripheral speeds of the cage cylinders 11 and 12, and the tightening of the cages are adjusted, according to the rules of the art, so that the elongation has a chosen value , and that approximately 90% of this elongation occurs in the first cage 11.
  • the cage 12 essentially has the role of leveling and improving the finish of the strip 10, of regulating the traction on the strip (between 20 and 40 kN normally) on the side of the cage 11, and incidentally wring the strip.
  • the parameter values indicated above are average values, determined by the Applicant during numerous tests. However, the most important parameter, to which the other parameters are subordinate, is the elongation imparted to the strip, depending on the state of the strip after annealing in a hood and the desired final hardness.
  • Figure 2 shows the hardness, expressed in Rockwell HR 30T of the work hardened strips, as a function of the elongation imparted.
  • the shade band A goes from 61 Rockwell HR 30T for 4% elongation to 69 HR 30T for 20% elongation, and the shade band B goes from 64 to 71 HR 30T for these limit elongations.
  • the roughness of the first cage cylinders should be all the higher as the elongation chosen is low, a roughness Ra of 3.5 micrometers suitable for elongations of 4%, while for elongations of 20%, a roughness of 1 micrometer Ra was suitable.
  • the lubricating power of the oil emulsion has an effect on the elongation. It is advisable to use an oil with a rather reduced intrinsic lubricating power, but with a relatively high content in the emulsion, which makes it easier to control the oil content of the emulsion and therefore the regularity of the lubricating power of the emulsion. 'emulsion.
  • the transition connection has large radii of curvature for steels annealed under chloche and conventionally hardened, a bearing or an elbow with very small radius of curvature for steels annealed continuously and hardened conventionally, and an elbow with small radius of curvature for steels annealed under chloche and work-hardened according to the process of the invention.
  • a stress difference of the order of 50 N / m M2 is recorded between the conventional processes, while the work hardened steels according to the invention have, compared to steels continuously annealed, a stress difference of less than 10 N / mm 2.
  • the invention is not limited to the examples described. It is understood in particular that the work hardening can be carried out on a rolling mill comprising more than two cages, using only two operating cages. Furthermore, the method could be implemented with two rolling mills with a cage, respecting the operating conditions specific to each according to the teachings presented above, although the use of a rolling mill with at least two stands is preferred.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Metal Rolling (AREA)
  • Heat Treatment Of Sheet Steel (AREA)

Description

L'invention a trait à un procédé d'écrouissage par laminage de bandes .d'acier doux destinées notamment à la fabrication d'emballages, cet écrouissage prenant sa place dans la fabrication des bandes, où des tôles en bobines provenant d'acier de nuance prévus pour coulée en continu sont amenées sensiblement à épaisseur de bande par un premier laminage à froid, recuites en sorte de faire disparaître les anisotropies structurelles engendrées par le premier laminage, puis écrouies par un second laminage en sorte d'amener le métal de bande à dureté choisie. Plus précisément, le procédé est destiné à conférer à des bandes recuites sous cloche une dureté comparable à celle de bandes recuites en continu et écrouies par laminage à sec avec un allongement inférieur à 2%.The invention relates to a method of work hardening by rolling strips of mild steel intended in particular for the manufacture of packaging, this work hardening taking its place in the manufacture of strips, where sheets in coils from steel of grades intended for continuous casting are brought substantially to strip thickness by a first cold rolling, annealed so as to remove the structural anisotropies generated by the first rolling, then hardened by a second rolling so as to bring the strip metal at selected hardness. More specifically, the method is intended to give strips annealed in a bellows a hardness comparable to that of strips annealed continuously and work-hardened by dry rolling with an elongation of less than 2%.

L'invention prend sa place dans l'évolution technologique de l'élaboration des bandes d'acier destinées principalement à la fabrication d'emballages, sous forme de fer blanc et de fer noir, c'est-à-dire de bandes laminées à froid d'épaisseurs nominales allant de 0,15 à 0,49 mm, conformes à la norme ISO 1111/11 (1976). Par fer blanc on entend des bandes ou des feuilles recouvertes d'étain, et par fer noir des bandes correspondantes non étamées, soit au stade précédent l'étamage, soit destinées à la fabrication d'articles protégés par divers traitements de surface. L'invention se rapport à l'élaboration des bandes à l'état de fer noir, à un stade précédent l'étamaqe du fer blanc ou tout autre traitement de surface.The invention takes its place in the technological development of the production of steel strips intended mainly for the manufacture of packaging, in the form of tin and black iron, that is to say strips laminated to cold with nominal thicknesses ranging from 0.15 to 0.49 mm, in accordance with ISO 1111/11 (1976). By tinplate is meant strips or sheets covered with tin, and by black iron corresponding strips not tinned, either at the stage before tinning, or intended for the manufacture of articles protected by various surface treatments. The invention relates to the development of strips in the state of black iron, at a stage preceding the tinning of white iron or any other surface treatment.

L'exposé de l'état de la technique qui va suivre se réfère dans ses grandes lignes au "Steel Products Manual, Tin Mill Products", édité par l'American lron and Steel Institute (1000 16th Street, N.W., Washington, D.C. 20036), mise à jour de Mai 1979, tout particulièrement pages 14 et 15.The description of the state of the art which follows refers broadly to the "Steel Products Manual, Tin Mill Products", published by the American Iron and Steel Institute (1000 16th Street, NW, Washington, DC 20036 ), May 1979 update, especially pages 14 and 15.

L'élaboration des bandes se fait à partir de bobines de tôles d'épaisseur de l'ordre de 2 mm, qui subissent un premier laminage à froid, au cours duquel les tôles sont réduites en épaisseur avec un allongement corrélatif, pour donner des bandes dont l'épaisseur est sensiblement l'épaisseur finale de la bande de fer noir. Les bandes sont alors recuites sous atmosphère protectrice, pour faire disparaître les anisotropies structurelles engendrées par le premier laminage, où le métal a subi un allongement considérable lui conférant une structure cristalline fibreuse. Mais, à la suite du recuit, le métal est trop mou pour une mise en oeuvre par déformation. On lui fait donc subir un second laminage à faible allongement, pour l'écrouir et lui conférer la dureté requise pour les mises en forme ultérieures. Ce second laminage, écrouissant, parfait en outre le fini des bandes.The strips are produced from coils of sheets of the order of 2 mm, which undergo a first cold rolling, during which the sheets are reduced in thickness with a corresponding elongation, to give strips whose thickness is substantially the final thickness of the strip of black iron. The strips are then annealed under a protective atmosphere, to remove the structural anisotropies caused by the first rolling, where the metal has undergone considerable elongation giving it a fibrous crystalline structure. However, after annealing, the metal is too soft for processing by deformation. It is therefore subjected to a second rolling with low elongation, to work harden and give it the hardness required for subsequent shaping. This second rolling, hardening, also perfects the finish of the strips.

Les tôles elles-mêmes ont été élaborées par laminage à chaud de brames.The sheets themselves were produced by hot rolling of slabs.

Pendant longtemps, les brames ont été obtenues à partir déacier coulé en lingotières. Le recuit des bandes après le premier laminage à froid était effectué en bobine sous cloche. Les nuances d'acier utilisé étaient telles que le second laminage, écrouissant, conférait aux bandes une dureté convenable avec un allongement d'environ 1 à 2%.For a long time, slabs were obtained from steel cast in molds. The annealing of the strips after the first cold rolling was carried out in a closed coil. The grades of steel used were such that the second rolling, hardening, gave the strips a suitable hardness with an elongation of approximately 1 to 2%.

Parallèlement au développement de la coulée en continu de l'acier, qui permet une plus grande régularité de composition du métal et partant une plus grande régularité des propriétés mécaniques et structurelles des produits élaborés, tôles et bandes, et permet également des cadences de production supérieures, on a développé des techniques de recuit en continu, où la bande, après avoir subi un premier laminage, traverse un four de recuit, avant la mise en bobine à destination du second laminage écrouissant. Ce recuit en continu s'exécute beaucoup plus rapidement que le recuit classique en bobine sous chloche, et comporte notamment des phases d'échauffement et de refroidissement brèves. Il en résulte que la structure cristalline de l'acier après recuit en continu est nettement plus fine qu'après un recuit sous cloche, avec comme conséquence une dureté supérieure, qui se répercute évidemment sur la dureté de la bande après laminage écrouissant. En conséquence les nuances d'aciers de coulée continue des tôles en bobine destinées à l'élaboration de bandes de fer noir ont été modifiées par réduction de la teneur en éléments durcissants, afin d'obtenir des duretés convenables des fers noirs en bande élaborés suivant les processus de coulée continue des aciers, et de recuit en continue des bandes à la suite du premier laminage. On notera que l'utilisation de nuances plus douces d'acier présente un avantage évident pour le laminage à froid, en réduisant l'énergie nécessaire pour obtenir la réduction d'épaisseur voulue.In parallel with the development of continuous casting of steel, which allows greater regularity in the composition of the metal and hence greater regularity in the mechanical and structural properties of the products produced, sheets and strips, and also allows higher production rates. , continuous annealing techniques have been developed, where the strip, after having undergone a first rolling, passes through an annealing furnace, before re-reeling for the second hardening rolling. This continuous annealing is carried out much faster than the conventional annealing in a coil under chloche, and notably includes brief heating and cooling phases. As a result, the crystalline structure of the steel after continuous annealing is much finer than after annealing in a bell, with as a consequence a higher hardness, which obviously affects the hardness of the strip after hardening rolling. Consequently, the grades of continuous casting steels of the coil sheets intended for the production of black iron strips have been modified by reduction of the content of hardening elements, in order to obtain suitable hardnesses of the black irons in the strip produced according to the continuous casting processes of steels, and the continuous annealing of strips after the first rolling. It will be noted that the use of milder grades of steel has an obvious advantage for cold rolling, by reducing the energy required to obtain the desired thickness reduction.

Cependant, l'aménagement d'une installation de laminage à froid pour t'étaboration de bandes avec incorporation d'un four de recuit continu exige des investissements très lourds, qui ne sont rentables que si le tonnage produit est suffisamment important. On a estimé que le tonnage correspondant au seuil de rentabilité se situe, en tout état de cause, au-delà de 100 000 tonnes par an. Pour des tonnages inférieurs au tonnage de seuil de rentabilité, le recuit en bobine sous cloche s'impose, et l'on se trouve devant le dilemme suivant: ou bien rononcer aux avantages de régularité du métal, et de facilité de laminage à froid procurés par les tôles provenant d'aciers de coulée continue, et utiliser des tôles provenant d'aciers coulés en lingotière, de dureté supérieure ou bien élaborer des bandes de fer noir de dureté inférieure à la dureté des bandes recuites en continu, requise usuellement pour la mise en forme ultérieure. Dans les deux cas, la compétitivé commerciale des bandes qui ont subi un recuit sous cloche est compromise.However, the installation of a cold rolling installation for the production of strips with the incorporation of a continuous annealing furnace requires very heavy investments, which are profitable only if the tonnage produced is sufficiently large. It has been estimated that the tonnage corresponding to the break-even point is, in any event, in excess of 100,000 tonnes per year. For tonnages lower than the breakeven tonnage, annealing in a closed coil is necessary, and we are faced with the following dilemma: either to give up the advantages of regularity of the metal, and ease of cold rolling procured by sheets coming from steels of continuous casting, and using sheets coming from steels cast in ingot molds, of higher hardness or else producing black iron strips of hardness lower than the hardness of continuously annealed strips, usually required for the subsequent shaping. In both cases, the commercial competitiveness of bands which have undergone bell annealing is compromised.

L'invention a pour objectif principal un procédé d'écrouissage de bandes provenant d'acier de nuance prévue pour coulée en continu, et recuites sous cloche, qui leur confère une dureté comparable à celle de bandes correspondantes recuites en continu.The main objective of the invention is a method of work hardening of strips coming from steel of grade intended for continuous casting, and annealed in a bell, which gives them a hardness comparable to that of corresponding strips annealed continuously.

L'invention a également pour objectif un procédé d'écrouissage de bandes qui soit applicable à des trains de laminoirs classiques sans transformations importantes.The object of the invention is also a method of strip hardening which is applicable to conventional rolling mill trains without major transformations.

A ces effets, l'invention propose un procédé de laminage écroissant pour la fabrication de bandes d'acier doux destinées notamment à la fabrication d'emballages, où des tôles en bobine sont amenées sensiblement à épaisseur de bande par un premier laminge à froid, recuites en sorte de faire disparaître les anisotropies struccturelles engendrées par le premier laminage, pous écrouies par un second laminage à faible allongement en sorte d'amener le matériel de bande à dureté choisie, ce second laminage étant conduit avec une lubrification par projection d'une émulsion d'huile dans l'eau sur la bande à l'entrée dans le laminoir, caractérisé en ce qu'il est destiné à conférer à des bandes, provenant d'acier de coulée continue, et recuites sous cloche, une dureté comparable à celle de bandes recuites en continu écrouies par laminage à sec avec un allongement inférieur à 2%, procédé dans lequel on conduit les bandes d'acier, qui étaient de qualité normalement prévue pour être recuites en continu, et néanmoins ont été recuites sous cloche, sur deux cages successives en sorte que l'allongement résultant soit égalé à une valeur choisie entre 4 et 20% et obtenu pour 85-95% dans la première cage, à l'entrée de laquelle la bande est lubrifiée, on lave la bande à l'eau à une température supérieure à lambiante entre les cages, et l'on sèche la bande par soufflage d'air en sortie de deuxième cage.To these effects, the invention provides an increasing rolling process for the production of strips mild steel intended in particular for the manufacture of packaging, where the coil sheets are brought to substantially strip thickness by a first cold rolling, annealed so as to remove the structural anisotropies generated by the first rolling, hardened by a second rolling with low elongation so as to bring the strip material to selected hardness, this second rolling being carried out with lubrication by spraying an oil-in-water emulsion onto the strip at the entrance to the rolling mill , characterized in that it is intended to impart to strips, coming from steel of continuous casting, and annealed under bell, a hardness comparable to that of continuously annealed strips worked hard by dry rolling with an elongation of less than 2% , process in which the steel strips, which were of quality normally intended to be continuously annealed, and nevertheless were annealed, are run on two bands successive cages so that the resulting elongation is equal to a value chosen between 4 and 20% and obtained for 85-95% in the first cage, at the entrance of which the strip is lubricated, the strip is washed with water at a higher than ambient temperature between the cages, and the strip is dried by blowing air at the outlet of the second cage.

Il est connu de lubrifier les tôles à l'entrée de cages de laminage à froid, pour faciliter la réduction d'épaisseur de la tôle dans la cage. On utilise généralement des émulsions d'huiles, dites organiques en terme de métier, qui sont des triglycérides, d'origine végétale ou animale. Dans l'élaboration de bandes dites à double réduction, qui subissent après le recuit suivant le premier laminage, une seconde réduction d'épaisseur accompagnée d'un allongement de plus de 30%, on met en oeuvre également une lubrification des bandes à l'entrée des cages de seconde réduction, en utilisant soit des émulsions d'huiles organiques, soit souvent des émulsions d'huiles minérales ou synthétiques, traitées pour donner aisément des émulsions stables. On précise que les bandes à double réduction présentent des taux d'écrouissage élevés et sont réservées à des usages spéciaux, différents des usages des bandes de fer noir (à simple réduction).It is known to lubricate the sheets at the entry of cold rolling cages, to facilitate the reduction of thickness of the sheet in the cage. Generally used emulsions of oils, called organic in terms of profession, which are triglycerides, of vegetable or animal origin. In the preparation of so-called double reduction strips, which undergo a second thickness reduction after annealing after the first rolling, accompanied by an elongation of more than 30%, lubrication of the strips is also carried out. entry of second reduction cages, using either emulsions of organic oils, or often emulsions of mineral or synthetic oils, treated to easily give stable emulsions. It is specified that the double reduction strips have high work hardening rates and are reserved for special uses, different from the uses of black iron strips (single reduction).

On sait traiter des bandes en laminage écrouissant, avec lubrification analogue à celle pratiquée en double réduction.It is known to treat strips in hardening rolling, with lubrication similar to that practiced in double reduction.

Le but visé est essentiellement une amélioration de la finition des bandes, par réduction de l'adhérence de dépôts résiduels après recuit afin d'éviter l'incrustation superficielle des résidus sur la bande, et par réduction de l'encrassage des cylindres de laminoir. Corrélativement on a remarqué que la lubrification augmentait l'allongement de la bande lors de l'écrouissage, notamment aux grandes vitesses de défilement, tandis que la dureté de la bande écrouie diminuait quelque peu à allongement égal. Pour ne pas s'écarter des propriétés mécaniques conférées aux bandes écrouies à sec en processus usuel avec des allongements inférieurs à 2%, on admet que les allongements en écrouissage humide ne doivent pas dépasser 3%. L'opinion des gens du métier est que cet écrouissage humide ne présente d'intérêt que pour nettoyer les cylindres encrassés.The aim is essentially an improvement in the finishing of the strips, by reducing the adhesion of residual deposits after annealing in order to avoid superficial encrustation of the residues on the strip, and by reducing the fouling of the rolling mill rolls. Correlatively it has been observed that lubrication increases the elongation of the strip during work hardening, in particular at high running speeds, while the hardness of the work hardened strip decreases somewhat at equal elongation. In order not to deviate from the mechanical properties conferred on dry-worked strips in the usual process with elongations of less than 2%, it is accepted that the elongations in wet work hardening must not exceed 3%. The opinion of those skilled in the art is that this wet hardening is only of interest for cleaning dirty cylinders.

Or la demanderesse a constaté qu'il était possible de régler le taux d'écrouissage des bandes après un recuit sous cloche, en réglant corrélativement le taux d'allongement au passage dans les cages d'écrouissage, la dureté finale de la bande croissant avec le taux d'allongement, et cette dureté finale pouvant être ajustée de façon reproductible avec une bonne précision à condition que le taux d'allongement soit contrôlé étroitement à l'intérieur d'une gamme de 4 à 20%. Une étude minutieuse des paramètres gouvernant la constance du taux d'allongement a fait ressortir que la lubrification à l'entrée de la première cage, où doit se réaliser en majeure partie l'allongement, joint au lavage entre les deux cages en sorte que la bande soit très peu lubrifiée à l'entré dans la seconde cage, était essentiel pour le contrôle de l'allongement. Par ailleurs, la bande finie doit être enroulée à sec pour éviter l'oxydation, et le séchage résulte de l'utilisation d'eau chauffée pour le lavage, en vue de son évaporation ultérieure rapide, et du soufflage en sortie de deuxième cage pour réduire au minimum la quantité d'eau à évaporer.However, the Applicant has found that it is possible to adjust the rate of work hardening of the strips after annealing under a bell, by correlatively adjusting the rate of elongation when passing through work hardening cages, the final hardness of the strip increasing with the elongation rate, and this final hardness can be reproducibly adjusted with good precision provided that the elongation rate is closely controlled within a range of 4 to 20%. A careful study of the parameters governing the constancy of the elongation rate revealed that the lubrication at the entrance of the first cage, where the elongation must be carried out for the most part, joined to the washing between the two cages so that the strip is very little lubricated at the entry into the second cage, was essential for the control of the elongation. Furthermore, the finished strip must be rolled up dry to avoid oxidation, and the drying results from the use of heated water for washing, with a view to its rapid subsequent evaporation, and from the blowing at the outlet of the second cage for minimize the amount of water to evaporate.

De préférence, la rugosité des cylindres de première cage est comprise entre 3,5 et 1 micromètres Ra, tandis que celle des cylindres de deuxième cage est comprise entre 0,75 et 0,4 micromètre Ra. Ces rugosités, qui correspondent à un en majeure partie obtenu dans la première cage, avec un contrôle efficace de l'allongement total état de surface relativement rugueux pour la première cage, et un état finement rectifié pour la seconde cage, se sont avérées utiles pour que l'allongement soit en majeure partie obtenu dans la première cage, avec un contrôle efficace de l'allongement total.Preferably, the roughness of the first cage cylinders is between 3.5 and 1 micrometers Ra, while that of the second cage cylinders is between 0.75 and 0.4 micrometers Ra. These roughnesses, which correspond to a major part obtained in the first cage, with an effective control of the total elongation relatively rough surface state for the first cage, and a finely rectified state for the second cage, have proved useful for that the elongation is mainly obtained in the first cage, with effective control of the total elongation.

Il est à remarquer que des allongements de 4 à 20% correspondent à des réductions d'épaisseur respectivement de 3,8 à 16,7% c'est-à-dire des variations d'épaisseur, pour une bande de 0,2 mm d'épaisseur respectivement de 7,6 à 33,4 micromètres. Le contrôle à 1 % près de l'allongement, s'il devait être effectué sur l'épaisseur de la bande, imposerait un contrôle d'épaisseur à 2 micromètres près. Il est clair que le seul contrôle d'épaisseur, tel qu'il est pratiqué pour la réduction d'épaisseur, serait inopérant pour régler la durté de la bande en sortie d'écrouissage dans la game requise. Par ailleurs, l'écrouissage classique avec des allongements inférieurs à 2% se situe dans une zone où la dureté finale dépend peu de l'allongement, qui ne nécessite donc pas un contrôle serré.It should be noted that elongations of 4 to 20% correspond to thickness reductions respectively of 3.8 to 16.7%, that is to say variations in thickness, for a strip of 0.2 mm thickness respectively from 7.6 to 33.4 micrometers. The control to 1% near the elongation, if it were to be carried out on the thickness of the strip, would impose a thickness control to 2 micrometers. It is clear that the only control of thickness, as it is practiced for the reduction of thickness, would be inoperative to regulate the hardness of the strip at the output of work hardening in the required game. Furthermore, the classic work hardening with elongations of less than 2% is located in an area where the final hardness depends little on the elongation, which therefore does not require tight control.

De préférence, l'émulsion d'huile dans l'eau utilisée pour la lubrification est à une teneur comprise entre 1 et 10% d'huile.Preferably, the oil in water emulsion used for lubrication is at a content of between 1 and 10% of oil.

De préférence également l'eau de lavage entre les cages est à 50°C environ, ce qui correspond à un bon compromis entre les exigences de vitesse d'évaporation, et l'absence de zones prématurément séchées.Preferably also the washing water between the cages is at around 50 ° C., which corresponds to a good compromise between the requirements for evaporation rate and the absence of prematurely dried zones.

Par ailleurs, l'eau de lavage contiendra de préférence environ 0,2% en poids de nitrite de sodium, pour passiver la surface de la bande et éviter une oxydation ultérieure.Furthermore, the washing water will preferably contain approximately 0.2% by weight of sodium nitrite, to passivate the surface of the strip and avoid subsequent oxidation.

Les avantages de l'invention ressortiront d'ailleurs de la description qui va suivre, à titre d'exemple, en référence aux dessins annexés dans lesquels:

  • la figure 1 est un schéma de laminoir à deux cages, aménagé pour la mise en oeuvre du procédé suivant l'invention;
  • la figure 2 est un diagramme de dureté finale en fonction de l'allongement.
The advantages of the invention will become apparent from the description which follows, by way of example, with reference to the appended drawings in which:
  • Figure 1 is a rolling mill diagram with two stands, arranged for the implementation of the method according to the invention;
  • FIG. 2 is a diagram of final hardness as a function of the elongation.

Comme on le voit figure 1, le laminoir comporte deux cages successives 11 et 12, première et seconde cage dans le sens du défilement de la bande 10 indiqué par la flèche 10a. Ces cages comportent respectivement des cylindres supérieurs 11a et 12a et des cylindres inférieurs 11b et 12b. La bande 10 àécrouir est débitée à partir d'une bobine 1, qui a été préalablement recuite en atmosphère protectrice sous une cloche classique. La bande 10 passe sur une paire de rouleaux tendeurs 2, freinés pour mettre la bande sous tension. Au soirtir des rouleaux tendeurs 2, la bande s'engage entre les cylindres 11a a et 11b b de la première cage 11, puis entr les cylindres 12a et 12b de la cage 12, avant de passer entre une paire de rouleaux tendeurs 4, pous de s'enrouler sur une bobine réceptrice 5. Comme il est classique, les couples exercés sur les axes des rouleaux tendeurs 2 et 4 sont ajustés par asservissement pour donner à la bande une tension réglée, et les vitesses et couples d'entraînement des cylindres de cages 11 et 12 sont ajustables en coopération avec le serrage des cages pour régler les allongements.As can be seen in FIG. 1, the rolling mill has two successive stands 11 and 12, the first and second stands in the direction of travel of the strip 10 indicated by the arrow 10a. These cages respectively comprise upper cylinders 11a and 12a and lower cylinders 11b and 12b. The strip 10 to be hardened is cut from a coil 1, which has been previously annealed in a protective atmosphere under a conventional bell. The strip 10 passes over a pair of tension rollers 2, braked to put the strip under tension. In the evening of the tension rollers 2, the strip engages between the cylinders 11a a and 11b b of the first cage 11, then between the cylinders 12a and 12b of the cage 12, before passing between a pair of tension rollers 4, pous to be wound on a take-up reel 5. As is conventional, the torques exerted on the axes of the tension rollers 2 and 4 are adjusted by servo-control to give the strip a regulated tension, and the speeds and driving torques of the rolls cages 11 and 12 are adjustable in cooperation with the tightening of the cages to adjust the elongations.

Pour mettre en oeuvre le procédé suivant l'invention, les cylindres 11a et 11b sont de préférence rectifiés avec une rugosité de 3 micromètres Ra, tandis que les cylindres 12a et 12b sont rectifiés polis avec une rugosité de 0,6 micromètre Ra. On rappelle que la rugosité Ra est la moyenne quadratique des écarts de la surface réelle à la surface théorique. Par ailleurs, on a équipé le laminoir de rampes de pulvérisation 6 à l'entrée de la cage 11, et 7 au voisinage de la sortie de cette cage 11, et de rampes de soufflage 8 au sortir de la cage 12. Les rampes 6 sont alimentées sous une pression réglable de 2 à 5 bars, par de l'eau additionnée de 5% environ d'huile, en l'espèce une huile synthétique vendue sous la dénomination FCF 106 par la Société CRODA. Le débit des rampes est réglé par la pression d'alimentation, pour apporter en ordre de grandeur, 250 g d'huile pour 1000 m2 de surface exposée de bande (c'est-à-dire en comptant les deux côtés).To implement the method according to the invention, the cylinders 11a and 11b are preferably ground with a roughness of 3 micrometers Ra, while the cylinders 12a and 12b are ground polished with a roughness of 0.6 micrometers Ra. It is recalled that the roughness Ra is the quadratic mean of the deviations from the real surface to the theoretical surface. Furthermore, the rolling mill was equipped with spraying booms 6 at the entrance to the cage 11, and 7 in the vicinity of the outlet from this cage 11, and with blowing booms 8 at the exit from the cage 12. The booms 6 are supplied at a pressure adjustable from 2 to 5 bars, with water added with approximately 5% of oil, in this case a synthetic oil sold under the name FCF 106 by the company CRODA. The flow rate of the ramps is regulated by the supply pressure, in order to provide, in order of magnitude, 250 g of oil per 1000 m 2 of exposed strip surface (that is to say, counting the two sides).

Les rampes 7 sont alimentées en eau à la température de 50°C environ, à raison d'environ 0,2 à 0,4 m3 d'eua pour 1000 M 2 de surface exosée de bande. L'eau est additionnée de 5 kg de nitrite de sodium par mètre cube. Bien entendu, l'eau qui s'écoule de la bande après lavage est reprise et traitée pour être recyclée.The ramps 7 are supplied with water at a temperature of approximately 50 ° C., at a rate of approximately 0.2 to 0.4 m 3 of eua per 1000 M 2 of exposed strip surface. 5 kg of sodium nitrite are added to the water per cubic meter. Of course, the water which flows from the strip after washing is taken up and treated to be recycled.

Le soufflage par les rampes 8 est exécuté à l'air comprimé, et réglé pour qu'au-delà la bande soit humide, mais non mouillée. Le film déeua qui reste en surface au-delà des rampes de soufflage 8 s'évapore progressivement pour disparaître avant l'enroulement sur la bobine réceptrice 5.The blowing by the ramps 8 is carried out with compressed air, and adjusted so that beyond the strip is wet, but not wet. The film deeua which remains on the surface beyond the blowing ramps 8 gradually evaporates to disappear before being wound up on the take-up reel 5.

La traction sur la bande 10 entre les rouleaux tendeurs 2 et 4, les vitesses périphériques des cylindres de cage 11 et 12, et le serrage des cages sont réglés, selon les règles de l'art, pour que l'allongement ait une valeur choisie, et que 90% environ de cet allongement se produise dans la première cage 11. La cage 12 a essentiellement pour rôle de planer et améliorer le fini de la bande 10, de régulariser la traction sur la bande (entre 20 et 40 kN normalement) du côté de la cage 11, et accessoirement essorer la bande.The traction on the strip 10 between the tensioning rollers 2 and 4, the peripheral speeds of the cage cylinders 11 and 12, and the tightening of the cages are adjusted, according to the rules of the art, so that the elongation has a chosen value , and that approximately 90% of this elongation occurs in the first cage 11. The cage 12 essentially has the role of leveling and improving the finish of the strip 10, of regulating the traction on the strip (between 20 and 40 kN normally) on the side of the cage 11, and incidentally wring the strip.

Il va sans dire que les valeurs de paramètres indiquées ci-dessus sont des valeurs moyennes, déterminées par la Demanderesse au cours de nombreux essais. Mais le paramètre le plus important, auquel les autres paramètres sont subordonnés, est l'allongement conféré à la bande, en fonction de l'état de la bande après le recuit sous cloche et de la dureté finale souhaitée.It goes without saying that the parameter values indicated above are average values, determined by the Applicant during numerous tests. However, the most important parameter, to which the other parameters are subordinate, is the elongation imparted to the strip, depending on the state of the strip after annealing in a hood and the desired final hardness.

On présente ci-après des résultats d'essai d'ecrouissage destinés à préciser la raltion entre allongement et dureté finale, pour deux aciers coulés en continu; A et B, dont les compositions sont données dans le tableau suivant (teneurs en constituants en p.p.m.).

Figure imgb0001
The following are the results of the work hardening test intended to specify the difference between elongation and final hardness, for two steels cast continuously; A and B, the compositions of which are given in the following table (contents of constituents in ppm).
Figure imgb0001

La figure 2 indique la dureté, exprimée en Rockwell HR 30T des bandes écrouies, en fonction de l'allongement conféré. On voit que la relation entre dureté et allongement est sensiblement linéaire entre 4 et 20% d'allongement. La bande de nuance A passe de 61 Rockwell HR 30T pour 4% d'allongement à 69 HR 30T pour 20% d'allongement, et la bande de nuance B passe de 64 à 71 HR 30T pour ces allongements limites.Figure 2 shows the hardness, expressed in Rockwell HR 30T of the work hardened strips, as a function of the elongation imparted. We see that the relationship between hardness and elongation is substantially linear between 4 and 20% elongation. The shade band A goes from 61 Rockwell HR 30T for 4% elongation to 69 HR 30T for 20% elongation, and the shade band B goes from 64 to 71 HR 30T for these limit elongations.

En conséquence, pour un fer noir de dureté spécifié de 65±4HR 30T, en écrouira la bande nuance A avec un allongement d'environ 13%, et la bande de nuance B avec un allongement d'environ 7%.Consequently, for a black iron with a specified hardness of 65 ± 4HR 30T, the shade band A with an elongation of about 13% will work hard, and the shade band B with an elongation of about 7%.

Il est par ailleurs clair que l'établissement de diagrammes d'étalonnage d'écrouissage, en fonction des nuances d'acier utilisées et des conditions de recuit sous cloche relève d'essais de routine.It is moreover clear that the establishment of work hardening calibration diagrams, according to the grades of steel used and the annealing conditions under a bell is part of routine tests.

On précisera toutefois que les essais ont confirmé que la rugosité des cylindres de première cage devait être d'autant plus élevée que l'allongement choisi est faible, une rugosité Ra de 3,5 micromètres convenant à des allongements de 4%, tandis que pour des allongements de 20%, une rugosité de 1 micromètre Ra convenait bien.However, it should be noted that tests have confirmed that the roughness of the first cage cylinders should be all the higher as the elongation chosen is low, a roughness Ra of 3.5 micrometers suitable for elongations of 4%, while for elongations of 20%, a roughness of 1 micrometer Ra was suitable.

On notera que, parallèlement à la fugosité des cylindres de première cage, le pouvoir lubrifiant de l'émulsion d'huile a un effet sur l'allongement. Il est indiqué d'utiliser une huile à pouvoir lubrifiant intrinsèque plutôt réduit, mais à teneur relativement élevée dans l'émulsion, ce qui rend plus aisé le contrôle de la teneur en huile de l'émulsion et partant la régularité du pouvoir lubrifiant de l'émulsion.It will be noted that, parallel to the transience of the first cage cylinders, the lubricating power of the oil emulsion has an effect on the elongation. It is advisable to use an oil with a rather reduced intrinsic lubricating power, but with a relatively high content in the emulsion, which makes it easier to control the oil content of the emulsion and therefore the regularity of the lubricating power of the emulsion. 'emulsion.

Les essais et contrôles sur productions pilotes de bandes écrouies à taux réglé ont fait apparaître que le laminage écrouissant de l'invention, non seulement permettait de régler la dureté superficielle des aciers de coulée continue (aciers calmés) recuits sous cloche, mais également leur conférait des propriétes intéressantes dans la zone de transition entre la zone de déformation élastique et celle de déformation plastique, les aciers recuits sous cloche et écrouis suivant le procédé de l'invention ayant un comportement plus proche de celui des aciers recuits en continu et écrouis par le processus classique que de celui des aciers recuits sous cloche et écrouis à faible allongement.The tests and inspections on pilot productions of work-hardened strips at a regulated rate revealed that the work-hardening rolling of the invention not only made it possible to adjust the surface hardness of continuous casting steels (quenched steels) annealed in a bell, but also gave them advantageous properties in the transition zone between the zone of elastic deformation and that of plastic deformation, the steels annealed under bell and hardened according to the process of the invention having a behavior closer to that of steels annealed continuously and hardened by the classic process than that of steel annealed in a bell and cold worked at low elongation.

En effet, si l'on trace les diagrammes de contraintes/allongement relatifs à des aciers coulés en continu choisis dans des nuances telles que les duretés superficielles finales soient pratiquement identiques après des processus de recuit en continu ou sous cloche, et d'écrouissage classique ou suivant l'invention, celui- ci appliqué bien entendu à un acier recuit sous chloche, on constate que les diagrammes coïncident sensiblement dans les zones à comportement franchement élastique et franchement plastique, tandis que les diagrammes s'écartent nettement dans la zone de transition. Le raccordement de transition présente de grands rayons de courbure pour les aciers recuits sous chloche et écrouis classiquement, un palier ou un coude à très faible rayon de courbure pour les aciers recuits en continu et écrouis classiquement, et un coude à rayon de courbure faible pour les aciers recuits sous chloche et écrouis selon le processus de l'invention. Au point conventionnel de limite élastique, correspondant à une déformation plastique de 0,2%, on enregistre une différence de contrainte de l'ordre de 50 N/m M2 entre les processus classiques, tandis que les aciers écrouis selon l'invention présentent, par rapport aux aciers recuits en continu, une différence de contrainte inférieure à 10 N/mm2. Indeed, if one draws the stress / elongation diagrams relating to steels cast continuously chosen in nuances such that the final surface hardnesses are practically identical after processes of continuous annealing or under bell, and classic hardening or according to the invention, the latter applied of course to a steel annealed under a chloche, it can be seen that the diagrams substantially coincide in the zones with frankly elastic and frankly plastic behavior, while the diagrams clearly deviate in the transition zone . The transition connection has large radii of curvature for steels annealed under chloche and conventionally hardened, a bearing or an elbow with very small radius of curvature for steels annealed continuously and hardened conventionally, and an elbow with small radius of curvature for steels annealed under chloche and work-hardened according to the process of the invention. At the conventional point of elastic limit, corresponding to a plastic deformation of 0.2%, a stress difference of the order of 50 N / m M2 is recorded between the conventional processes, while the work hardened steels according to the invention have, compared to steels continuously annealed, a stress difference of less than 10 N / mm 2.

L'avantage du diagramme à faible rayon de transition est que, au course des processus d'usinage des bandes écrouies, les contraintes accidentelles ou inéluctables ne donnent lieu à des déformations irréversibles que si ces contraintes dépassent le domaine de comportement élastique, de sorte que les déformations incontrôlées sont d'autant plus réduites que la zone de transition est étroite et le rayon de courbure du diagramme faible.The advantage of the diagram with small transition radius is that, in the course of the processes of machining of the work hardened strips, the accidental or inescapable stresses give place to irreversible deformations only if these stresses exceed the field of elastic behavior, so that the uncontrolled deformations are all the more reduced the narrower the transition zone and the radius of curvature of the diagram.

Bien entendu, l'invention n'est pas limitée aux exemples décrits. On conçoit notamment que l'écrouissage peut être pratiqué sur un laminoir comportant plus de deux cages, en n'utilisant que deux cages opérantes. Par ailleurs, on pourrait mettre en oeuvre le procédé avec deux laminoirs à une cage, en respectant les conditions opératoires propres à chaque suivant les enseignements présentés ci-dessus, encore que l'utilisation d'un laminoir à au moins deux cages soit préférée.Of course, the invention is not limited to the examples described. It is understood in particular that the work hardening can be carried out on a rolling mill comprising more than two cages, using only two operating cages. Furthermore, the method could be implemented with two rolling mills with a cage, respecting the operating conditions specific to each according to the teachings presented above, although the use of a rolling mill with at least two stands is preferred.

Claims (5)

1. A temper rolling process for producing mild steel strips intended in particular for the manufacture of packagings, in which coiled metal sheets are brought substantially to the strip thickness by a first cold rolling, annealed to eliminate structural anisotropies generated by the first rolling, and then tempering by a second rolling with only slight elongation so as to bring the strip metal to a selected hardness, this second rolling being performed with lubrication by spraying (7) an emulsion of oil in water on the strip at the inlet in the rolling mill, characterized in that it is adapted to confer on strips derived from continuously cast and box-annealed steel, a hardness comparable to that of strips which have been subjected to continuous annealing and tempered by dry rolling with an elongation less than 2%, the process being one in which steel strips, which were of a quality normally provided for continuous annealing, but nevertheless have been box-annealed, are conveyed to two successive stands (11, 12) so that the resulting elongation is regulated to a selected value between 4 and 20%,85-90% of which is produced in the first stand (11) at the entrance to which the strip is lubricated, the strip is washed with water (7) at a greater than ambient temperature between the stands (11, 12), and the strip is dried by air-blasting (8) at the exit from the second stand (12).
2. A process according to Claim 1, characterized in that the roughness of the rolls in the first stand is between 3.5 and 1 micrometres Ra, whilst that of the cylinders of the second roll stand is between 0.75 and 0.4 micrometres Ra.
3. A process according to Claim 1, characterized in that the emulsion is 1-10% oil in water.
4. A process according to Claim 1, characterized in that the water used for washing is at approximately 50°C.
5. A process according to Claim 1, characterized in that the washing water contains approximately 0.2% by weight of sodium nitrite.
EP81401230A 1980-08-18 1981-07-30 Method of executing the skin pass at a regulated rate in the rolling of steel strips annealed in a furnace Expired - Lifetime EP0046423B2 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8018054 1980-08-18
FR8018054A FR2488532A1 (en) 1980-08-18 1980-08-18 METHOD OF RULE-NARROW NUTS ROLLING FOR SOFT STEEL REINFORCED SOFT BANDS

Publications (3)

Publication Number Publication Date
EP0046423A1 EP0046423A1 (en) 1982-02-24
EP0046423B1 EP0046423B1 (en) 1984-10-10
EP0046423B2 true EP0046423B2 (en) 1990-12-19

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP81401230A Expired - Lifetime EP0046423B2 (en) 1980-08-18 1981-07-30 Method of executing the skin pass at a regulated rate in the rolling of steel strips annealed in a furnace

Country Status (7)

Country Link
EP (1) EP0046423B2 (en)
DE (2) DE3166614D1 (en)
ES (1) ES8205589A1 (en)
FR (1) FR2488532A1 (en)
GR (1) GR75311B (en)
NO (1) NO152676C (en)
PT (1) PT73532B (en)

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5054302A (en) * 1989-04-07 1991-10-08 Kawasaki Steel Corporation Hardness compensated thickness control method for wet skin-pass rolled sheet
EP0436762A1 (en) * 1990-01-12 1991-07-17 Bwg Bergwerk- Und Walzwerk-Maschinenbau Gmbh Method and apparatus for achieving a predetermined yield point and surface roughness during cold-laminating of metallic pre-treated strips
ES2043530B1 (en) * 1992-01-30 1994-06-16 Kramer Antonio Henriqu MANUFACTURING PROCEDURE FOR METAL CONTAINERS.
NL9400674A (en) * 1994-04-27 1995-12-01 Hoogovens Groep Bv Device and method for manufacturing DKG strip steel.
US5555756A (en) * 1995-01-24 1996-09-17 Inland Steel Company Method of lubricating steel strip for cold rolling, particularly temper rolling
JP3783439B2 (en) * 1998-12-25 2006-06-07 Jfeスチール株式会社 Method for temper rolling of steel sheet
CN112969540B (en) 2018-11-23 2023-11-03 考克利尔维修工程有限责任公司 Flexible cold rolling mill and conversion method thereof
CN117753782B (en) * 2024-02-21 2024-05-03 山西广华源药用包装有限公司 Calendaring molding machine for aluminum foil processing

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR629623A (en) * 1926-11-05 1927-11-14 Kalker Maschinenfabrik Ag Cold rolling process of iron, steel and other metals
US1860613A (en) * 1929-08-22 1932-05-31 Republic Steel Corp Method of rolling metal sheets
DE1546173A1 (en) * 1965-03-19 1969-04-17 C Otto & Company Gmbh Dr Process for the aftertreatment of pickled strand material, preferably wide band
SE338221B (en) * 1970-04-15 1971-08-30 Nyby Bruk Ab
US3820365A (en) * 1973-03-23 1974-06-28 Westinghouse Electric Corp Automatic extension control
DE2362051A1 (en) * 1973-12-13 1975-06-19 Hufnagl Walter Mfg concrete reinforcing rods - stock material sprayed with oil emulsion before drawing

Also Published As

Publication number Publication date
EP0046423B1 (en) 1984-10-10
EP0046423A1 (en) 1982-02-24
FR2488532A1 (en) 1982-02-19
NO812771L (en) 1982-02-19
PT73532A (en) 1981-09-01
NO152676C (en) 1985-11-06
DE3166614D1 (en) 1984-11-15
PT73532B (en) 1983-08-24
GR75311B (en) 1984-07-13
DE46423T1 (en) 1983-03-17
FR2488532B1 (en) 1982-11-05
NO152676B (en) 1985-07-29
ES504786A0 (en) 1982-06-16
ES8205589A1 (en) 1982-06-16

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