Production of aluminum alloy sheet products in multi-product hot mills
An improved rolling procedure is used for forming aluminum alloy sheet product of critical quality, e.g. can body stock, in a hot rolling mill. The mill is of a type in which the rolls are changed on a routine basis at least once during a production week and a plurality of rolled products of different alloy compositions, including sheet product of critical quality, are fed through the hot rolling mill on a sequential basis. In the improved procedure, the aluminum alloy sheet product of critical quality is fed through the rolling mill within the first 72 hours of production time after the rolls have been changed. Also, the order in which different products are to be produced is selected such that products that generate sufficient heat during rolling to cause micro-annealing of the rolls are processed after the sheet product of the critical quality.
1 . In a process for producing aluminum alloy sheet product of critical quality in a hot rolling mill of a type wherein the rolls are changed on a routine basis at least once during a production week and a plurality of rolled products of different alloy compositions, including sheet product of critical quality, are fed through the hot rolling mill on a sequential basis,
the improvement which comprises hot rolling the aluminum alloy sheet product of critical quality within the first 72 hours of production time after the rolls have been changed and selecting the order in which different products are to be produced such that products that generate sufficient heat during rolling to cause micro-annealing of the rolls are processed after the sheet product of critical quality.
2 . The process as claimed in claim 1 , wherein the critical quality stock is hot rolled with the first 32 hours of actual contact between the rolls and the metal stock being rolled.
3 . The process as claimed in claim 1 , wherein the sheet product of critical quality is can body stock.
4 . The process as claimed in claim 3 , wherein the rolls are changed after 3 to 4 days of production.
5 . The process as claimed in claim 4 , wherein the can body stock is hot rolled within the first 48 hours of production time.
6 . The process as claimed in claim 5 , wherein the can body stock is hot rolled within the first 21 hours of actual contact between the rolls and the can body stock being rolled.
7 . The process as claimed in claim 3 , wherein the alloys causing micro-annealing of the rolls are aluminum alloys having a high concentration of magnesium.
8 . The process as claimed in claim 7 , wherein the can body stock is an AA3104 alloy.
9 . The process as claimed in claim 7 , wherein the aluminum alloy having a high concentration of magnesium contains at least 4% by weight of magnesium.
10 . The process as claimed in claim 9 , wherein alloys that may selectively be rolled before can body stock are selected from the group consisting of cathode sheet, brazing sheet and anodize quality sheet.