EP3661669B1 - Multi-roller flattener of a metal strip - Google Patents

Description

The present invention relates to a metal strip leveler according to claim 1. Currently, there is a strong evolution of the grades of metal strips such as sheets, in particular in the field of automotive applications towards very high mechanical properties, for example by use. a heat treatment system imposing a phase transformation under difficult control conditions (for example during rapid cooling) and inducing internal deformations, heterogeneities and stresses within the metal product.

A problem of final shaping of the metal product such as by stamping or forming is thus made more difficult by high elastic limit properties (elastic return), and requires an incoming product having a homogeneous material and perfectly freed from internal stresses.

It is known that a metal strip leveler has a property of correcting flatness defects, for example by means of two upper and lower rows of upper and lower leveling rollers, respectively, the upper and lower rollers being with parallel axes, offset. longitudinally in a tape pass line direction and also offset in height, so as to determine, by nesting the rollers, a corrugated path of the tape between said rollers. Mainly, this type of leveler makes it possible to impose an elongation of the strip strands in order to make it more flat. At the exit of such a leveler, it is possible to have an anti-tile crew in order to correct a residual deformation linked to the strip tiling effect.

Finally, said leveler can include at its output a second module called multi-roller type, the main property of which is to reduce residual stresses on the metal strip.

A fundamental state of the art EP0665069A1 patented by the applicant of the present patent application introduces such an optimized type of leveler in order to improve the reduction of flatness defects and residual stresses, by means of the aforementioned characteristics and advantages.

A study "The mechanical and metallurgical effects of skin passing and tension leveling", European Commission, ISSN 1018-5593, Technical Steel Research, 1992 , §2.3.3.3, §2.3.3.4, fig. 20-23 presents in particular tensile leveling profiles comprising a first profile of linear nesting values of the rollers (Penetration settings of rollers (mm), fig. 22) in the direction of the pass line which form an effect of " corner ”, that is to say for which the nesting is more accentuated at the entry of the leveler than at its exit, in a linear manner and in order to compensate for the residual stresses of the product under tension. Finally, a second profile of linear nesting values of the rollers is also presented comprising two successive discontinuous linear profiles of linear nesting values (Penetration settings of rollers (mm), fig. 23) according to the direction of the pass line. This improved profile is achieved by arranging two successive sets of upper and lower leveling cassettes each being individually tiltable in a plane vertical to the web pass line. It is specified that such profiles of nesting values make it possible to compensate for residual stresses of the linear type of the material, but that non-linear stresses seem to persist. Likewise, a recent publication EP2813299A1 uses the same principle of a leveler under traction and thus has the same drawbacks, as well as those described below.

The applicant wanted to persevere in the study of residual stresses of the non-linear type. By experiments on site and of the simulated type, it was shown that, following a leveling under tension such as that described in the aforementioned state of the art, the metal strip mainly exhibits mechanical stresses exhibiting a strong asymmetry in intensity. depending on the thickness of the product and with respect to at least one neutral fiber of the strip. Indeed, just as in the state of the art cited above by European Commission Study ISSN 1018-5593 or EP2813299A1 , and after having tested such continuous or discontinuous linear nesting profiles, which may have several possible slopes, these residual stresses, hereinafter referred to as asymmetric, persist to the detriment of the required quality of the planed product.

• Figure 1 : un profil asymétrique de contraintes résiduelles selon l'épaisseur de bande tel qu'après une étape de planage selon l'état de l'art,
• Figure 2 : un profil optimisé de contraintes résiduelles visé par l'invention.

As such, two figures are provided:

• Figure 1 : an asymmetric profile of residual stresses depending on the strip thickness such as after a leveling step according to the state of the art,
• Figure 2 : an optimized profile of residual stresses targeted by the invention.

Figure 1 presents a typical example of an asymmetric profile of residual stresses (c) according to the thickness (e) of strip (B) such as after a leveling step according to the state of the art. The stress value is zero at the level of at least one neutral fiber (fn), said neutral fiber here being spaced from a so-called “strip center” (cb) fiber located in the middle of the strip thickness. It is thus given here an example of typical asymmetry of profile of residual stresses (c) non-linear, knowing that, in the thickness domain under the neutral fiber offset from the center of the strip, low negative stresses (= compression) are recorded, while in the thickness domain above the offset neutral fiber of the band center, strong positive stresses (= traction) non-linear are present. This asymmetric distribution imbalance of the non-linear stresses is obviously very penalizing for subsequent forming steps which require controlled stress properties (with established symmetry) depending on the thickness of the strip.

Figure 2 has an optimized profile of residual stresses targeted by the invention, in that the asymmetry of the profile according to figure 1 tends to be corrected by a rebalancing of positive and negative asymmetric constraints. Such a rebalancing must result in a profile of stresses symmetrical compared to the center of band and of which the distribution of the stresses (c) positive and negative is also the most balanced possible.

An aim of the present invention is to provide a metal strip leveler capable of at least compensating for an imbalance, in particular asymmetric, in the distribution of residual stresses in the thickness of the planed strip, in particular for steels with a high elastic limit.

A metal strip leveler is thus provided through the features of claim 1.

• une rangée de rouleaux supérieurs et une rangée de rouleaux inférieurs, les dits rouleaux étant des rouleaux de planage ou de dressage en contact avec la bande,
• les rouleaux supérieurs et inférieurs étant à axes parallèles, décalés longitudinalement selon une direction de ligne de passe de la bande et décalés en hauteur, de façon à déterminer , par imbrication verticale des rouleaux, un trajet ondulé de la bande entre les dits rouleaux,
• au moins deux rouleaux supérieurs et deux rouleaux inférieurs sont disposés au-dessus et respectivement au-dessous de la ligne de passe, de sorte qu'ils forment trois écarts d'imbrication verticale, les dits écarts ayant au moins un profil de valeurs non-linéaires d'imbrication de type soit convexe soit concave par rapport à un profil de valeurs linéaires d'imbrication suivant la direction de ligne de passe.

The invention presents a metal strip leveler, said strip having a thickness subjected to a stress profile, said profile exhibiting at least one defect in flatness and / or asymmetry as a function of the thickness of the product, said leveler comprising:

• a row of top rollers and a row of rollers lower, said rollers being leveling or dressing rollers in contact with the strip,
• the upper and lower rollers being with parallel axes, offset longitudinally in a direction of the pass line of the strip and offset in height, so as to determine, by vertical nesting of the rollers, a corrugated path of the strip between said rollers,
• at least two upper rollers and two lower rollers are arranged above and respectively below the pass line, so that they form three vertical nesting gaps, said gaps having at least one profile of non- Linear nesting of either convex or concave type with respect to a profile of linear nesting values in the direction of the pass line.

A major advantage of the nesting profile with at least three non-linear type deviations makes it possible to distribute the residual stresses better in the thickness of the planed strip, on the model of the figure 2 , unlike known linear type profiles which mainly have only a leveling effect absorbing symmetrical type stresses on the thickness of the strip to be leveled and therefore cannot rebalance an asymmetric stress.

Several advantageous embodiments of the leveler according to the invention are thus possible, depending on the desired qualitative requirements. A set of sub-claims presents these modes and also additional advantages of the invention.

Figure 3

Premier mode de réalisation de planeuse selon l'invention,

Figure 4

Profil d'imbrication selon figure 3,

Figure 5

Second et troisième modes de réalisation de planeuse selon l'invention,

Figure 6

Profil d'imbrication selon le second mode de réalisation,

Figure 7

Profil d'imbrication selon le troisième mode de réalisation.

Examples of implementation and application are provided using the figures described:

Figure 3

First embodiment of a leveler according to the invention,

Figure 4

Nesting profile according to figure 3 ,

Figure 5

Second and third embodiments of a leveler according to the invention,

Figure 6

Nesting profile according to the second embodiment,

Figure 7

Nesting profile according to the third embodiment.

Figure 3 presents a first embodiment of the leveler of a metal strip (B) according to the invention and in a side view (operator for example). The strip has a thickness subjected to a stress profile as described above in relation to the figure 1 . The strip also has some flatness defects.

• une rangée de rouleaux supérieurs (1, 3, 5, 7, 9...) et une rangée de rouleaux inférieurs (2, 4, 6, 8, 10...), les dits rouleaux étant des rouleaux de planage ou de dressage en contact avec la bande,
• les rouleaux supérieurs et inférieurs sont à axes parallèles, décalés longitudinalement selon une direction de ligne de passe (lp) et décalés en hauteur, de façon à déterminer, par imbrication verticale des rouleaux, un trajet ondulé de la bande entre les dits rouleaux,
• au moins deux rouleaux supérieurs (1, 3) et deux rouleaux inférieurs (2, 4) sont disposés au-dessus et respectivement au-dessous de la ligne de passe, de sorte qu'ils forment trois écarts d'imbrication verticale, les dits écarts ayant un profil de valeurs non-linéaires d'imbrication plus précisément décrit par la figure 4.

Said leveler comprises:

• a row of upper rollers (1, 3, 5, 7, 9 ...) and a row of lower rollers (2, 4, 6, 8, 10 ...), said rollers being leveling or leveling rollers dressing in contact with the band,
• the upper and lower rollers have parallel axes, offset longitudinally in a direction of the pass line (lp) and offset in height, so as to determine, by vertical nesting of the rollers, a corrugated path of the strip between said rollers,
• at least two upper rollers (1, 3) and two lower rollers (2, 4) are arranged above and respectively below the pass line, so that they form three vertical nesting gaps, the so-called deviations having a profile of nonlinear nesting values more precisely described by the figure 4 .

Figure 4 present according to figure 3 said deviations having a profile (in continuous line) of non-linear nesting values (Imbr) of either convex or concave type with respect to a profile (in dotted lines) of linear nesting values (Imbr_lin) following the direction of pass line (rolls 1 to 16 in this case).

In the case of figure 3 and 4 and according to the first embodiment of the leveler according to the invention, the two upper rollers and the two lower rollers are arranged (1, 2, 3, 4) in a first leveling assembly (pl1) comprising for each of the rollers a individual vertical adjustment (v1, v2, v3, v4) in relation to a frame, a beam, a cassette or any other holding element included in the leveler for this purpose. Ideally, the adjustment of at least one of the rollers includes at least one cylinder.

The first rollers of the leveler included in the first leveling assembly (p1) make it possible in principle to ensure the major part of the elongation of the strip in order to correct flatness defects and stresses.

The leveler may additionally comprise at least a second leveling assembly (pl2) respectively formed by an upper cassette (C1) and a lower cassette (C2) of a multi-roller type leveler (5, 6, 7, 8, ... ). This configuration is particularly suitable for leveling so-called “tinplate” steels, for example suitable for the manufacture of metal packaging.

In the case of figures 3 and 4 , only the non-linear type deviations to obtain the convex or concave shaped nesting profile are established by nesting the rollers of the first leveling assembly (pl1), thus making it possible to compensate for asymmetric stress imbalances.

Generally, at least one of the cassettes (C1, C2) of the second leveling assembly (pl2) is tilted by vertical displacement means (v2hg, v2hd, v2bg, v2bd), so that the cassettes are arranged at an open angle in a vertical plane in the direction of the pass. This makes it possible to reduce the nesting of the rollers gradually and linearly in the case of figures 3 and 4 or as in the state of the art, thereby promoting a reduction in web stresses, except for asymmetric stresses.

Figures 5 to 7 finally present a second and a third embodiments of the leveler according to the invention.

From the figure 5 , the second embodiment of the leveler according to the invention provides that the leveler is only composed of the second leveling assembly of the multi-roller type (first leveling assembly absent or inactive). This type of multi-roll leveler generally comprises a high number of rollers (15 or more), and has the advantage of being able to absorb large flatness and stress defects.

In this case, the profile of non-linear nesting values is applied to at least four rollers of the second leveling assembly (p12), for example, by means of the two upper rollers (5, 7) and the two lower rollers ( 6, 8) which are arranged in (at least) the second leveling assembly (pl2) respectively formed by an upper cassette (C1) and a lower cassette (C2) of a multi-roll type leveler, with at least one of said cassettes including for each of the rollers an individual vertical adjustment (r5, r7; r6, r8, ...) of the rollers in relation to the cassettes, ideally the adjustment comprising at least one actuator of mechanical or servomotor type.

Figure 6 presents an example of a profile of non-linear values of nesting (Imbr) of convex shape here and applied to the rollers (5, 6, 7, 8, etc.) of the only second leveling set (pl2) presented in figure 5 for this second embodiment, the first leveling assembly being not present or inactive.

From the figure 5 , the third embodiment of the leveler according to the invention finally provides that the leveler is again composed of the first and of the second leveling assemblies (pl1, pl2). To this end, at least the two upper rollers and two lower rollers linked to the profile of non-linear nesting values are distributed or distributed in the first set and in the second set. As an example, it is possible to generate a profile of non-linear nesting values on the four rollers (1, 2, 3, 4) of the first leveling set (pl1) and also on one, two, three , four or more rollers (5, 6, 7, 8, ...) of the second leveling assembly (pl2).

This example of two profiles (Imbr) following one another according to the pass line is represented in figure 7 , in the form of a first convex profile for the rollers (1, 2, 3, 4) followed by a second concave profile for the rollers (5, 6, 7, 8, etc.) with respect respectively to each of the two successive linear profiles (Imbr_lin) of usual nesting of the state of the art.

While the rollers of the second leveling assembly (pl2) made it possible in the state of the art to limit the residual stresses generated by a linear and decreasing leveling nesting in order to compensate for the stresses induced in the product, the application of profiles of non-linear values of nesting (convex and / or concave) according to figure 5 around said linear profiles very advantageously lead to additional compensation for asymmetries of constraints in the thickness of the product. By applying the profile of non-linear values of nesting on rollers of the second leveling assembly (pl2) in addition to the rollers of the first leveling assembly (pl1), it is possible to obtain an increased absorption of asymmetric stresses coupled with a advantageous possibility of using at least one, two, three or more of the first rollers of the second leveling assembly (pl2) in order to accentuate (second embodiment) or to continue (third embodiment) an operation of lengthening of said strip having characteristics which do not allow the single first leveling assembly (p1) to perform sufficient elongation. To do this, the said first rolls (according to the direction of the web pass) of the second leveling assembly (pl2) are arranged under non-linear nesting values of concave or convex shape, the said non-nesting values. linear values being greater than the linear nesting values (Imbr_lin). Such an advantageous profile of nonlinear nesting values is explicitly shown in figures 6 and 7 .

• les moyens de déplacements verticaux (v1, v2, v3, v4) du premier ensemble de planage (pl1) sont présents dans une planeuse existante comprenant le dit premier ensemble ;
• des moyens de déplacements verticaux (r5, r6, r7, r8...) peuvent être prévus ou insérés sur des cassettes existantes du second ensemble de planage (pl2).

For all the embodiments presented ( figures 3 to 7 ), an existing leveler can also be easily and economically adapted to meet the characteristics and advantages of the leveler according to the invention, knowing that:

• the vertical displacement means (v1, v2, v3, v4) of the first leveling assembly (pl1) are present in an existing leveler comprising said first assembly;
• vertical displacement means (r5, r6, r7, r8 ...) can be provided or inserted on existing cassettes of the second leveling assembly (pl2).

• le deuxième ensemble de planage (pl2) de type multi-rouleaux comprend plusieurs couples de cassettes supérieure et inférieure se succédant selon la ligne de passe, afin de générer dans un premier couple de cassettes de plus forts effets d'allongement (planage) et de générer dans un second couple de cassettes de plus faibles effets d'allongement (dressage). L'ensemble de ces couples de cassettes permettent de moduler et d'élargir la gamme des valeurs d'imbrication non-linéaire pour des contraintes très asymétriques ;
• le profil de valeurs d'imbrication linéaire (Imbr_lin) selon la direction de ligne de passe est décroissant depuis une entrée vers une sortie d'au moins une portion de planage de bande suivant ladite ligne de passe et le profil de valeurs non-linéaires d'imbrication avoisine ou intersecte le profil de valeur d'imbrication linéaire, de sorte que les effets de résorption de contraintes résiduelles (hors contraintes asymétrie résorbées par l'invention) soient toujours conservés ;
• au moins deux tensionneurs sont disposés en amont et respectivement en aval d'au moins un groupe de rouleaux supérieurs et inférieurs, de sorte que la bande est soumise à une contrainte de traction ;
• mise à part le deuxième mode de réalisation, le deuxième ensemble de planage (pl2) comprend au moins 2,2 fois plus de rouleaux de planage que le premier ensemble de planage (pl1), idéalement 2,5 à 6 fois plus, de sorte que si un planage plus intense (acier dur, sous très haute limite élastique) et au sens de l'invention est requis, il sera possible de ne pas devoir augmenter le nombre de rouleaux du premier ensemble de planage (pl1) si ledit ensemble est présent ou actif, mais plutôt si nécessaire d'augmenter le nombre de rouleaux du deuxième ensemble de planage (pl2), en particulier aussi le nombre de ses rouleaux (5, 6, 7, 8, ...,) sous profil de valeurs non-linéaires d'imbrication lors d'un changement ou maintenance de cassettes ;
• les modes de réalisation de planeuse selon l'invention peuvent être avantageusement contrôlés par une unité de commande de type automate ou/et apte à être contrôlée par un opérateur, ladite unité ayant un support de données comprenant différents modèles de profil de contrainte en fonction des propriétés mécaniques de divers matériaux de bande à planer et apte à sélectionner un parmi des modèles de planage associés présentant différents profils de valeurs non-linéaires d'imbrication sous forme de signaux de commandes transmis à des actionneurs de réglage vertical (v1,v2... ; r5, r6...) des rouleaux successifs de planage. Il en ressort qu'un producteur de produits planés pourra plus facilement étendre sa gamme de produit tout en garantissant une haute qualité de produit, en particulier par des contraintes asymétriques avantageusement compensées ;
• Enfin, les modes de réalisation de planeuse selon l'invention prévoient avantageusement que côté opérateur au moins trois écarts verticaux entre des premiers couples de rouleaux successifs supérieur et inférieur ont un premier profil de valeurs non-linéaires d'imbrication et côté moteur au moins trois écarts verticaux entre des seconds couples de rouleaux successifs supérieur et inférieur ont un second profil de valeurs non-linéaires d'imbrication divergeant du premier profil, les premiers et les seconds couples de rouleaux étant soit rattachés aux mêmes rouleaux soit composés de rouleaux distincts. Ce double-profil de valeurs non-linéaires d'imbrication permet fort avantageusement de compenser des divergences d'asymétries des contraintes transversales du produit.

Finally, also for all the embodiments presented ( figures 3 to 7 ), the leveler according to the invention has the following characteristics and advantages:

• the second multi-roll type leveling assembly (pl2) comprises several pairs of upper and lower cassettes following one another along the pass line, in order to generate in a first pair of cassettes stronger effects of elongation (leveling) and generate in a second pair of cassettes weaker elongation effects (dressing). All of these pairs of cassettes make it possible to modulate and widen the range of non-linear nesting values for very asymmetric constraints;
• the profile of linear nesting values (Imbr_lin) along the pass line direction decreases from an input to an output of at least one strip leveling portion along said pass line and the profile of non-linear values d the nesting approaches or intersects the linear nesting value profile, so that the effects of resorption of residual stresses (apart from asymmetry stresses resorbed by the invention) are always preserved;
• at least two tensioners are arranged upstream and respectively downstream of at least one group of upper and lower rollers, so that the strip is subjected to a tensile stress;
• Apart from the second embodiment, the second leveling assembly (pl2) comprises at least 2.2 times more leveling rollers than the first leveling assembly (pl1), ideally 2.5 to 6 times more, so that if a more intense leveling (hard steel, under very high elastic limit) and within the meaning of the invention is required, it will be possible not to have to increase the number of rollers of the first leveling assembly (pl1) if said assembly is present or active, but rather if necessary to increase the number of rollers of the second leveling assembly (pl2), in particular also the number of its rollers (5, 6, 7, 8, ...,) under profile of non-linear nesting values during a change or maintenance of cassettes;
• the planer embodiments according to the invention can advantageously be controlled by a control unit of the PLC type or / and capable of being controlled by an operator, said unit having a data medium comprising different stress profile models as a function of mechanical properties of various belt materials to be leveled and able to select one from associated leveling models exhibiting different profiles of non-linear values of nesting in the form of control signals transmitted to vertical adjustment actuators (v1, v2 .. .; r5, r6 ...) successive leveling rollers. It emerges from this that a producer of planed products can more easily extend its product range while guaranteeing high product quality, in particular by advantageously compensated asymmetric constraints;
• Finally, the planer embodiments according to the invention advantageously provide that on the operator side at least three vertical gaps between the first pairs of successive upper and lower rollers have a first profile of non-linear nesting values and on the motor side at least three. Vertical gaps between second pairs of successive upper and lower rollers have a second profile of non-linear nesting values diverging from the first profile, the first and second pairs of rollers being either attached to the same rollers or composed of separate rollers. This double-profile of non-linear values nesting very advantageously makes it possible to compensate for the asymmetry divergences of the transverse stresses of the product.

Claims (11)

1. Metal strip leveler (B), said strip having a thickness (e) subject to a stress profile, said leveler comprising:

   - a row of upper rolls (1, 3, 5, 7, 9, ...) and a row of lower rolls (2, 4, 6, 8, 10, ...),

   - the axes of the upper and lower rolls are parallel, longitudinally offset in a pass-line direction (lp) and offset in height, in order to form an undulating path of the strip between the rolls by means of the vertical penetration of said rolls, characterized in that

   at least two upper rolls (1, 3, 5, 7) and two lower rolls (2, 4, 6, 8) are arranged respectively above and below the pass line such as to form three vertical penetration gaps, said gaps having a profile of non-linear penetration values (Imbr) that is either convex or concave with respect to a profile of linear penetration values (Imbr_lin) in the pass-line direction.
2. Leveler according to Claim 1, in which the two upper rolls (1, 3) and the two lower rolls (2, 4) are arranged in a first leveling assembly (pl1) incorporating individual vertical adjustment (v1, v2, v3, v4) for each of the rolls.
3. Leveler according to Claim 1 or 2, in which the two upper rolls (5, 7) and the two lower rolls (6, 8) are arranged in at least one second leveling assembly (pl2) respectively formed by an upper cassette (C1) and a lower cassette (C2) of a multi-roll leveler, in which at least one of said cassettes incorporates, for each of the rolls, individual vertical adjustment (r5, r7 , r6, r8) for the rolls in relation to the cassettes, in which the adjustment ideally includes a mechanical actuator or servomotor.
4. Leveler according to Claim 3, in which at least the two upper rolls and the two lower rolls are split between the first assembly and the second assembly.
5. Leveler according to Claim 3 or 4, in which said first rolls of the second leveling assembly (pl2) are arranged using non-linear penetration values in a concave or convex manner, said non-linear penetration values being greater than the linear penetration values (Imbr_lin).
6. Leveler according to one of Claims 3 to 5, in which the second assembly (pl2) has several pairs of upper and lower cassettes arranged in succession along the pass line.
7. Leveler according to one of Claims 1 to 6, in which the profile of linear penetration values (Imbr_lin) in the pass-line direction decreases from an entry towards an exit of at least one strip leveling portion along said pass line.
8. Leveler according to one of Claims 1 to 7, in which at least two tensioners are arranged upstream and downstream respectively of at least one group of upper and lower rolls, such that the strip is subjected to a tensile stress.
9. Leveler according to one of Claims 2 to 8, in which the second leveling assembly (pl2) includes at least 2.2 times as many leveling rolls as the first leveling assembly (pl1), ideally between 2.5 and 6 times as many.
10. Leveler according to one of Claims 1 to 9, that is controlled by a PLC control unit and/or can be controlled by an operator, in which said unit has a data medium containing different stress profile models as a function of the mechanical properties of different materials of the strip to be leveled, and that is able to select one of the related leveling models providing different profiles of non-linear penetration values in the form of control signals sent to the vertical adjustment actuators (v1, v2, v3, v4, r5, r6, r7, r8) of the successive leveling rolls.
11. Leveler according to one of Claims 1 to 10, in which at least three vertical gaps between the first pairs of successive upper and lower rolls have a first profile of non-linear penetration values on the operator side and at least three vertical gaps between the second pairs of successive upper and lower rolls have a second profile of non-linear penetration values different from the first profile on the motor side, in which the first and second pairs of rolls are attached to the same rolls or made up of different rolls.

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