Storage and transportation of aluminium strip
View Patent ↗The invention is particularly directed to the problem of creep deformation in a coiled aluminum strip, which occurs during coiling and for a period thereafter. The problem arises because the profile of the strip across its width is not flat, and is in fact usually thicker in the middle than at the edges (positive crown). To compensate for this, the invention provides that the spool onto which the coil is wound is adapted to provide more support to the strip in the center than at the edges, by making the central portion of the spool of a greater diameter than the end portions of the spool. A strip having a positive crown which is wound onto such a spool was found to exhibit significantly reduced creep strain, leading to reduced creep deformation.
1. A system for coiling of aluminum strip material having a coil assembly comprising a mandrel, a spool removably mounted on the mandrel and an aluminum strip material having a positive crown, the coil assembly having a supporting surface for coiling the strip material, the supporting surface providing a support profile in which that part of the supporting surface which supports the crown has a greater diameter than remaining parts of the supporting surface during coiling of inner laps of the strip material, wherein the spool has a length at least equal to the width of the strip material.
2. a system as claimed in claim 1 , wherein the support profile of the supporting surface is provided by adaptation of the spool.
3. A system as claimed in claim 2 wherein the spool is cylindrical, of substantially uniform diameter, and has slits extending from one or both ends of the spool.
4. A system as claimed in claim 3 , wherein the slits extend approximately one quarter of the length of the spool.
5. A system as claimed in claim 2 , wherein the spool has an outer diameter at that part of the spool which supports the crown that is greater than the outer diameter of the spool at one or both opposing end regions of the spool.
6. A system as claimed in claim 5 , wherein the spool is contoured to have an outwardly projecting crown over said part of the spool.
7. A system as claimed in claim 6 , wherein the outwardly projecting crown is rectangular.
8. A system as claimed in claim 2 , wherein that part of the spool which supports the crown is formed of a material having greater rigidity than that of a material forming one or both of the opposing end regions of the spool.
9. A system as claimed in claim 1 , further including at least one tensioning roll and a tension control device to control tension of the strip material as it is coiled from a first higher tension to a second lower tension.
10. A system as claimed in claim 1 , wherein the support profile of the supporting surface is provided by means separate from the spool.
11. A system as claimed in claim 10 , wherein the spool is cylindrical in shape.
12. A system as claimed in claim 11 , wherein the means separate from the spool that provides a support profile of the supporting surface is an outer sleeve mounted about that part of the spool which supports the crown, the outer sleeve having a width less than the width of the strip material.
13. A system as claimed in claim 11 , wherein the means separate from the spool is a length of material which is wound one or more times around the spool prior to coiling, the length of material having a width narrower than that of the strip material.
14. A system as claimed in claim 10 , wherein the means separate from the spool that provides the support profile of the supporting surface is the strip material shaped to have, when wound, the greater diameter at the part that supports the crown.
15. A system as claimed in claim 14 , wherein a leading end of the strip material is formed as a tongue having a width narrower than the width of the strip material.
16. A system as claimed in claim 15 , wherein the length of the tongue, in the longitudinal direction of strip material, Is approximately equal to n times the outer circumference of the spool, wherein n is an integer greater than zero.
17. A system as claimed in claim 10 , wherein the means separate from the spool is a sheet of material is attached to a surface of a leading end of the strip material, the sheet having a width narrower than that of the strip material.
18. A system as claimed in claim 17 , wherein the sheet of material has a length, in the longitudinal direction of the strip material, which is approximately equal to n times the outer circumference of the spool, where n is an integer greater than zero.
19. A system as claimed In claim 18 , wherein the sheet is made of aluminum.