FLATNESS OF A ROLLED STRIP

• US 20180126431A1
• Filed: 01/02/2018
• Published: 05/10/2018
• Est. Priority Date: 03/11/2013
• Status: Active Grant

• Current Assignee: Novelis Incorporated (Hindalco Industries Limited)
• Original Assignee: Novelis Incorporated (Hindalco Industries Limited)
• Inventors: NELSON, PAUL DAVID, GAENSBAUER, DAVID ANTHONY, HOBBIS, ANDREW JAMES
• Granted Patent: US 10,130,979 B2
• Time in Patent Office: Days
• CPC Class Codes: B21B 2015/0071 Levelling the rolled product
• CPC Class Codes: B21B 2045/0212 using gaseous coolants
• CPC Class Codes: B21B 37/44 using heating, lubricating or water-spray cooling of the product
• CPC Class Codes: B21B 37/74 Temperature control, e.g. by cooling or heating the rolls or the product B21B37/32, B21B37/44 take precedence
• CPC Class Codes: B21B 37/76 Cooling control on the run-out table
• CPC Class Codes: B21B 38/02 for measuring flatness or profile of strips
• CPC Class Codes: B21B 45/0209 Cooling devices, e.g. using gaseous coolants
• CPC Class Codes: B21B 45/0218 for strips, sheets, or plates B21B45/023, B21B45/0233 take precedence

Abstract

A method for improving the flatness of a rolled sheet or strip includes the application of differential cooling. A cooling agent can be selectively applied along the width of the strip. More cooling can be applied to the edges of the strip, where tension is greatest, to increase tension at the edges. The strip can be allowed to lengthen at these edges, which can improve flatness. In some embodiments, a closed loop flatness control system is used to measure the flatness of a strip and automatically adjust the differential cooling based on the measurement.

Claims

1. A method of improving flatness in rolled metal, including:

heating a strip;

selectively cooling the strip to induce a non-homogenous temperature gradient in the strip across a width of the strip, wherein selectively cooling the strip includes distributing a cooling agent to the strip through at least one nozzle of a cooling unit; and

maintaining the non-homogenous temperature gradient in the strip for an amount of time sufficient to allow the strip to yield under the non-homogenous temperature gradient by, wherein maintaining the non-homogenous temperature gradient includes keeping the strip from contacting additional equipment capable of equalizing tension or temperature across the width of the strip for the amount of time.

2. The method of claim 1, wherein selectively cooling results in each edge of the width of the strip having a first temperature colder than a second temperature of a middle of the strip.

3. The method of claim 1, wherein selectively cooling includes:

applying the cooling agent to selected portions of the width of the strip.

4. The method of claim 3, wherein the at least one nozzle includes an array of nozzles, and wherein applying the cooling agent includes:

actuating at least one valve of an array of valves on the array of nozzles to selectively block distribution of the cooling agent from each of the array of nozzles positioned adjacent an unselected portion of the width of the strip.

5. The method of claim 3, wherein applying the cooling agent includes:

applying the cooling agent from a continuous slot of the at least one nozzle; and

positioning an occlusion portion of a sleeve over the continuous slot to block distribution of the cooling agent from the continuous slot to an unselected portion of the width of the strip.

6. The method of claim 1, additionally comprising:

measuring a flatness of the strip, wherein the non-homogenous temperature gradient is based on a flatness measurement of the strip.

7. The method of claim 6, additionally comprising:

comparing the flatness measurement of the strip to a desired flatness to generate a cooling signal, wherein the non-homogenous temperature gradient is based on the cooling signal.

8. The method of claim 6, wherein:

the non-homogenous temperature gradient is induced so a first portion of the width of the strip is cooled to a temperature below a second portion of the width of the strip; and

the first portion of the width of the strip has a first magnitude of tensile stress greater than a second magnitude of tensile stress of the second portion of the width of the strip.

9. The method of claim 1, additionally comprising applying a coating to the strip prior to selectively cooling the strip.