MULTI-ROLL METAL STRIP LEVELER

Abstract

A metal strip leveler (B): the strip has a thickness (e) subject to a stress distribution. The leveler includes a row of upper rolls (1, 3, 5, 7, 9 . . . ) and a row of lower rolls (2, 4, 6, 8, 10 . . . ) having parallel axes, are longitudinally offset in a direction of line of passage (lp) and are offset in height, to define, by vertical imbrication (overlapping) of the rolls, an undulating path of the strip between the rolls. The imbrication occurs because the rows of rolls are interleaved partially to create an undulating path for the strip. At least two upper rolls ([1, 3]; [5, 7]) and two lower rolls ([2, 4]; [6, 8]) are arranged respectively above and below the line of passage, such that they form three vertical imbrication gaps. Those gaps have a profile of non-linear imbrication values (Imbr) that are either convex or concave with respect to a profile of linear imbrication values (Imbr_lin) in the direction of the line of passage.

Claims

1. A metal strip leveler, for a metal strip having a thickness subject to a stress profile, the leveler comprising: a row of upper rolls and a row of lower rolls which the strip roll passes in a rolling direction; the upper and the lower rolls have axes that are parallel, are longitudinally offset in a pass-line direction and are offset in height, the upper and lower rolls are imbricated and configured for forming an undulating path of the strip in the pass line direction between the rolls, the path being configured by vertical penetration of the metal strip by the imbrication of the rolls,; wherein at least two of the upper rolls and two of the lower rolls are arranged respectively above and below a pass line of the strip to form three vertical penetration gaps in the strip, the gaps have a profile of non-linear penetration values that is either convex or concave with respect to a profile of linear penetration values in the pass-line direction.

2. The leveler as claimed in claim 1, further comprising a first leveling assembly in which the two upper rolls and the two lower rolls are arranged; each of the two upper rolls and the two lower rolls incorporating respective individual vertical adjustment in the thickness directions of the strip.

3. The leveler as claimed in claim 1 further comprising at least one second leveling assembly, the two upper rolls and the two lower rolls are arranged in the at least one second leveling assembly, the second leveling assembly comprises an upper cassette and a lower cassette of a multi-roll leveler, in which the upper rolls are in the upper cassette and the lower rolls are in the lower cassette; at least one of the upper and lower cassettes incorporates, for each of the rolls thereof, an individual vertical adjustment for each roll in relation to the respective cassettes, in which the adjustment includes a mechanical actuator or servomotor.

4. The leveler as claimed in claim 3, further comprising at least the two upper rolls and the two lower rolls are split between the first assembly and the second assembly.

5. The leveler as claimed in claim 4, further comprising the first rolls of the second leveling assembly are arranged using non-linear penetration values in a concave or a convex manner, the non-linear penetration values being greater than the linear penetration values.

6. The leveler as claimed in claim 5, further comprising the second leveling assembly has several pairs of upper and lower cassettes arranged in succession along the pass line direction.

7. The leveler as claimed in claim 1, further comprising the profile of linear penetration values in the pass-line direction decreases from an entry toward an exit of at least one strip leveling portion along the pass line.

8. The leveler as claimed in claim 1, further comprising at least two tensioners are arranged upstream and downstream respectively of at least one group of upper and lower rolls, for subjecting the strip to a tensile stress.

9. The leveler as claimed in claim 2, further comprising the second leveling assembly includes at least 2.2 times as many rolls as the first leveling assembly.

10. The leveler as claimed in claim 1, further comprising a PLC control unit and/or control by an operator, wherein the PLC control 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 the PLC control unit is configured to select one of the related leveling models for providing different profiles of non-linear penetration values in the form of control signals sent to the vertical adjustment actuators of the successive leveling rolls.

11. The leveler as claimed in claim 1, wherein the 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 an 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.

12. The leveler as claimed in claim 2, further comprising the second leveling assembly includes at least between 2.5 and 6 times as many rolls as the first leveling assembly.

13. The leveler as claimed in claim 1, wherein the convex profile on the pass line is upward in the pass line direction, and the concave profile on the pass line is then downward in the pass line direction.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Example embodiments and applications are provided using the figures described:

[0023] FIG. 1 shows an asymmetrical profile of residual stresses as a function of the thickness of the strip, shown in the prior art;

[0024] FIG. 2 shows an optimized residual profile proposed by the invention;

[0025] FIG. 3 illustrates a first embodiment of the leveler according to the invention.

[0026] FIG. 4 illustrates a penetration profile according to FIG. 3.

[0027] FIG. 5 illustrates second and third embodiments of the leveler according to the invention.

[0028] FIG. 6 illustrates a penetration profile according to the second embodiment.

[0029] FIG. 7 illustrates a penetration profile according to the third embodiment.

DESCRIPTION OF EMBODIMENTS

[0030] FIG. 3 is a side view (operator side, for example) of a first embodiment of the leveler of a metal strip (B) according to the invention. The thickness of the strip is subjected to a stress profile as described above in relation to FIG. 1. The strip can also have flatness defects of any type.

[0031] The leveler includes: [0032] a row of upper rolls (1, 3, 5, 7, 9, . . . ) and a row of lower rolls (2, 4, 6, 8, 10, . . . ),. The rolls are leveling or straightening rolls in contact with the strip; [0033] the axes of the upper rolls are parallel and the axes of the lower rolls are also parallel. The axes are longitudinally offset in a pass-line direction (lp). Neighboring axes are offset in height. Neighboring rolls thereby form an undulating path of the strip between the rolls by means of the vertical penetration or imbrication of the rolls. The height offsets will produce either convex or concave profiles of penetration values along the pass line direction, [0034] at least two upper rolls (1, 3) and two lower rolls (2, 4) are arranged respectively above and below the pass line and are positioned to form at least three vertical penetration gaps. Those gaps in FIG. 3 have a profile of non-linear penetration values that is described in greater detail by FIG. 4.

[0035] With reference to FIG. 3, FIG. 4 shows the gaps with a profile (unbroken line) of non-linear penetration values (Imbr_conv) (Imbr) for the rolls (1, 2, 3, 4) that is convex or concave in relation to a profile (dotted line) of linear penetration values (Imbr_lin) in the pass-line direction (e.g. rolls 1 to 16 in this case).

[0036] In FIGS. 3 and 4, and according to the first embodiment of the leveler according to the invention, the two upper rolls and the two lower rolls (1, 2, 3, 4) are arranged in a first leveling assembly (p11) incorporating, for each of the rolls, 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 rolls may be performed by at least one jack.

[0037] The first rolls of the leveler in the first leveling assembly (p11) in principle perform most of the elongation of the strip to correct flatness defects and stresses.

[0038] The leveler can also include at least one second leveling assembly (p12) formed respectively by an upper cassette (C1) and a lower cassette (C2) of a multi-roll leveler (5, 6, 7, 8, . . . ). This layout is particularly suited to leveling tin plate steel, which is for example suited to manufacturing metal packaging.

[0039] In FIGS. 3 and 4, only the non-linear gaps for obtaining the convex (or concave) penetration profile are formed by penetration of the rolls of the first leveling assembly (p11), thereby enabling compensation of the asymmetrical stress imbalances.

[0040] Usually, at least one of the cassettes (C1, C2) of the second leveling assembly (p12) is inclined using vertical displacement means (v2hg, v2hd, v2bg, v2bd), so that the cassettes are arranged at an open angle in a vertical plane in the pass direction. This enables the penetration of the rolls to be progressively and linearly reduced in the case of both of FIGS. 3 and 4 or as in the prior art, thereby helping to reduce stresses in the strip, but with the exception of asymmetrical stresses.

[0041] FIGS. 5 to 7 show second and third embodiments of the leveler according to the invention.

[0042] In the second embodiment of the leveler according to the invention, as shown in FIG. 5, the leveler includes only the second multi-roll leveling assembly (wherein the first leveling assembly is absent or in this Figure, inactive). This type of multi-roll leveler usually has a high number of rolls (15 or more) and has the advantage of being able to reduce major flatness defects and stresses.

[0043] In this case, the profile of non-linear penetration values is applied to at least four rolls of the second leveling assembly (p12), for example using two upper rolls (5, 7) and the two lower rolls (6, 8), which are arranged in (at least) the second leveling assembly (p12) respectively formed by an upper cassette (C1) and a lower cassette (C2) of a multi-roll leveler. At least one of the 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.

[0044] FIG. 6 shows an example profile (Imbr conc) of non-linear penetration values (Imbr), in this case concave, which is applied only to the rolls (5, 6, 7, 8, etc.) of the second leveling assembly (p12) shown in FIG. 5 for this second embodiment. The first leveling assembly, as in FIG. 5, is absent or inactive.

[0045] Finally, in the third embodiment of the leveler according to the invention, shown in FIG. 5, the leveler again includes the first and second leveling assemblies (p11, p12). For this purpose, at least the two upper rolls and the two lower rolls linked to the profile of non-linear penetration values are distributed or split between the first assembly and the second assembly. For example, it is possible to generate a profile of non-linear penetration values for the four rolls (1, 2, 3, 4) in the first leveling assembly (p11) and for one, two, three, four or more of the rolls (5, 6, 7, 8, . . . ) in the second leveling assembly (p12).

[0046] This example of two profiles (Imbr) arranged in succession along the pass line is shown in FIG. 7 in the form of a first convex profile for the rolls (1, 2, 3, 4) followed by a second concave profile for the rolls (5, 6, 7, 8, etc.) respectively in relation to each of the two successive linear penetration profiles (Imbr_lin) usual in the prior art.

[0047] In the prior art, the rolls of the second leveling assembly (p12) make it possible to limit the residual stresses generated by decreasing linear leveling penetration to compensate the stresses induced in the product. The application of profiles of non-linear penetration values (convex and/or concave) according to FIG. 5 about the linear profiles helps to very advantageously additionally compensate stress asymmetries in the thickness of the product. By applying the profile of non-linear penetration values to the rolls of the second leveling assembly (p12) in addition to the rolls of the first leveling assembly (p11), it is possible to further reduce the asymmetrical stresses and there is an advantageous option of using at least one, two, three or more of the first rolls in the second leveling assembly (p12) to accentuate (second embodiment) or continue (third embodiment) an elongation operation for the strip having characteristics that prevent the first leveling assembly (p11) from effecting sufficient elongation. To do this, the first rolls (in the strip pass direction) of the second leveling assembly (p12) are arranged using non-linear penetration values in a concave or a convex manner. The non-linear penetration values are greater than the linear penetration values (Imbr_lin). Such an advantageous profile of non-linear penetration values is shown explicitly in FIGS. 6 and 7.

[0048] For all of the embodiments shown in FIGS. 3 to 7, an existing leveler can also be adapted easily and cheaply to provide the characteristics and advantages of the leveler according to the invention, given that: [0049] the vertical displacement means (v1, v2, v3, v4) of the first leveling assembly (p11) are present in an existing leveler including the first assembly, [0050] vertical displacement means (r5, r6, r7, r8 . . . ) can be provided or inserted into the existing cassettes of the second leveling assembly (p12).

[0051] Finally, and equally for all of the embodiments disclosed FIGS. 3 to 7), the leveler according to the invention has the following characteristics and advantages: [0052] the second multi-roll leveling assembly (p12) has several pairs of upper and lower cassettes arranged in succession along the pass line in order to generate greater elongation effects (leveling) in a first pair of cassettes and to generate lesser elongation effects (straightening) in a second pair of cassettes. All of these pairs of cassettes enable the range of non-linear penetration values to be modulated and expanded for very asymmetrical stresses, [0053] the profile of linear penetration values (Imbr lin) in the pass-line direction decreases from an entry to an exit of at least one strip leveling portion along the pass line, and the profile of non-linear penetration values approaches or intersects the profile of linear penetration values such that the reducing effect of residual stresses (excluding asymmetrical stresses reduced by the invention) is always retained, [0054] At least two tensioners 22 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; [0055] setting the second embodiment aside, the second leveling assembly (p12) includes at least 2.2 times as many rolls as the first leveling assembly (p11), ideally between 2.5 and 6 times as many, such that if a more intense leveling (hard steel, with very high yield strength), within the meaning of the invention, 0 is required, it may not be necessary to increase the number of rolls in the first leveling assembly (p11) if that assembly is present or active, but rather to increase the number of rolls in the second leveling assembly (p12), and in particular the number of rolls (5, 6, 7, 8, . . . ) with a profile of non-linear penetration values during cassette maintenance or swapping, [0056] embodiments of the leveler according to the invention can advantageously be controlled by a PLC control unit 23 and/or by an operator, in which that 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, . . . ; r5, r6, . . . ) of the successive leveling rolls. This enables manufacturers of leveled products to more easily extend product ranges while guaranteeing high product quality, in particular as a result of advantageously compensated asymmetrical stresses; [0057] Finally and advantageously, in the embodiments of the leveler according to the invention, as illustrated in the Figures, 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 are made up of different rolls. This dual profile of non-linear penetration values very advantageously enables compensation of divergent asymmetries of transverse stresses in the product.