METHOD AND APPARATUS FOR STRETCH-BEND LEVELING METAL STRIP

Abstract

The invention relates to a method and to a device for the stretch-bend leveling of a metal strip (B), wherein the metal strip (B) is alternately bent around stretching rollers (1-5) under a tensile stress and the degree of stretching is thus increased, wherein one or more stretching rollers (1-5) are provided with a non-metal coating. The method and the device are characterized in that one or more stretching rollers are provided with a coating (8) of plastic.

Claims

1. A method of stretch-bend leveling metal strip, the method comprising the steps of: bending the metal strip alternately around a plurality of stretching rollers under a tensile stress, and increasing the stretching rate in a downstream strip-travel direction, providing one or more stretching rollers with a plastic jacket.

2. The method according to claim 1, further comprising the steps of: passing the metal strip through an inlet tension roller set for establishing tension and through an outlet tension roller set for dissipating the tension, the strip is bent alternately around the stretching rollers between the inlet tension roller set and the outset roller set, and the stretching rate of the strip being increased in the strip-travel direction.

3. The method according to claim 1 wherein each of the stretching rollers is provided with a respective jacket of plastic.

4. The method according to claim 1, wherein the jacket consists of polyurethane.

5. The method according to claim 1, wherein the jacket has a Shore A hardness of at least 90.

6. The method according to claim 1, wherein the metal strip passes through the stretching rollers in dry operation without any spray medium or the like being sprayed onto the stretching rollers.

7. The method according to claim 1, wherein an angle of wrap around the stretching rollers is adjusted as a function of strip tension so that a maximum linear load applied to the jacket is not exceeded.

8. The method according to claim 1, wherein a stretching rate of at least 0.2% is produced by the stretching rollers.

9. The method according to claim 1, wherein the strip is under a tensile stress of at least 15% of the yield point of the metal strip.

10. The method according to claim 1, wherein the jacket is at least 1 mm thick.

11. The method according to claim 1, wherein the stretching rollers each have a diameter of 25 mm to 100 mm.

12. The method according to claim 1, further comprising the step of: supporting each of the stretch rollers individually.

13. The method according to claim 1, further comprising the step of: adjusting one or more or all of the stretching rollers individually.

14. The method according to claim 1, wherein three to five stretching rollers are provided between the inlet tension roller set and the outlet tension roller set.

15. The method according to claim 1, further comprising the step of: supporting the stretching rollers are each supported individually on at least two backing or intermediate rollers.

16. The method according to claim 15, further comprising the step of: providing the backing rollers or the intermediate rollers also provided with a jacket of plastic.

17. An apparatus for stretch-bend leveling metal strip the apparatus comprising: an inlet tension roller set for establishing strip tension, an outlet tension roller set for releasing the strip tension, a plurality of stretching rollers between the inlet tension roller set and the outlet tension roller set, the to strip being bent in alternation around the stretching rollers with an increase in the stretching rate, a plastic jacket on one or more stretching rollers.

18. The apparatus according to claim 17, wherein the jacket is of polyurethane

19. The method according to claim 1, wherein the jacket is 3 mm to 7 mm thick.

Description

[0024] The drawing shows an apparatus for stretch-bend leveling a metal strip B. The metal strip B may be, for example, an aluminum strip. However, the invention also comprises stretch-bend leveling of strips of steel or of other metals or alloys.

[0025] In its basic design, the apparatus has an inlet tension roller set E for setting the strip tension and an outlet tension roller set A for releasing the strip tension. A plurality of stretching rollers 1, 2, 3, 4, 5, about which the strip is bent in alternation to increase the stretching rate is provided between the inlet tension roller set E and the outlet tension roller set A.

[0026] Moreover, a deflecting roller U is arranged upstream from the first stretching roller 1. Another deflecting roller may be arranged downstream from the last stretching roller.

[0027] Each of these stretching rollers 1 to 5 is supported individually, namely on at least two backing rollers 6 that are not shown in FIG. 1. They may be continuous backing rollers or rows of backing roller segments. At any rate the stretching rollers 1 to 5 are supported individually, i.e. they are not connected to one another in a friction-locking manner by the backing rollers 6 (in contrast with a multiroller leveling unit).

[0028] A stretching rate of at least 0.2% is achieved with the stretching rollers 1 to 5. Tensile stress in the metal strip B is created during the stretch-bend leveling process with the inlet tension roller set E and the outlet tension roller set A. The tensile stress amounts to at least 15% of the yield strength of the metal strip, preferably at least 20%.

[0029] In the embodiment illustrated here, all stretching rollers 1 to 5 are provided with a nonmetallic jacket 8. Consequently, the individual stretching rollers consist of a roller core 7 and a jacket 8. According to the invention, the jacket is a coating of plastic, preferably polyurethane or a comparable plastic. This jacket 8 may be 1 mm to 10 mm thick, preferably 3 mm to 7 mm thick. The stretching rollers 1 to 5 have a diameter of 25 mm to 100 mm, for example, 35 mm to 70 mm, and the diameter of the stretching rollers is understood not to include the jacket and consequently this is the diameter of the roller core 7.

[0030] FIGS. 2a and 2b show embodiments in which only the stretching rollers 1 to 5 are provided with the plastic jacket 8 according to the invention, while the backing rollers 6 and the intermediate rollers 6′ that are optionally provided do not have a jacket. FIG. 2a shows an embodiment with two backing rollers 6, and FIG. 2b shows an embodiment in which intermediate rollers 6′ are additionally provided.

[0031] Against this background, FIGS. 3a, 3b and 3c show embodiments in which the additional rollers are provided with a jacket in addition to the stretching rollers 1 to 5.

[0032] FIG. 3a shows an embodiment in which the coated stretching rollers 1-5 are each supported on two coated backing rollers 6. The jackets 8′ on the backing rollers 6 may also consist of polyurethane or some other plastic.

[0033] FIG. 3b shows an embodiment in which the stretching rollers 1 to 5 are supported by two intermediate rollers 6′ and three backing rollers 6 and/or three rows of segmented backing rollers. In this embodiment, the stretching rollers 1 to 5 and the backing rollers 6 are each provided with a jacket 8 or 8′, while the intermediate rollers 6′ are not coated.

[0034] FIG. 3c shows a modification of the embodiment according to FIG. 3b, and the intermediate rollers 6′ here are also provided with a jacket 8″.

[0035] Metal strips B can be leveled in a dry operation with the stretch-bend leveling system shown here. In other words, no liquid is sprayed onto the stretching rollers 1 to 5.