Optimized drawing and wall ironing process of aluminum containers
The invention relates to a manufacturing process of aluminum alloy beverage cans by «Drawing-Ironing», characterized in that a friction higher between the bodymaker punch and the aluminum sheet than between the ironing die and said aluminum sheet is produced by at least one of the following specificities: An aluminum sheet with an internal surface significantly higher in roughness than the external one Ironing dies with rounded intersections between infeed as well as exit surface and the land, with a smooth surface in the working area and a short width of the land A bodymaker punch with an extra roughness and an isotropic texture. It also relates to a beverage can manufactured by such a process, and characterized in that its reflectance measured at 60° is higher than 73% just after the last ironing step.
1. A manufacturing process of aluminum alloy beverage cans comprising drawing and ironing an aluminum alloy sheet,
wherein during the ironing step, a friction higher between a bodymaker punch and the aluminum sheet than between an ironing die and said aluminum sheet is produced by
the aluminum sheet comprising a smooth surface aluminum sheet having a roughness Ra below 0.3 μm on both sides in combination with an extra rough punch.
2. A manufacturing process of aluminum alloy beverage cans comprising drawing and ironing an aluminum alloy sheet,
wherein during the ironing step, a friction higher between a bodymaker punch and the aluminum sheet than between an ironing die and said aluminum sheet is produced by
the aluminum sheet comprising a smooth surface aluminum sheet having a roughness Ra below 0.3 μm on both sides in combination with no internal cupper lubrication used in the process.
3. A manufacturing process of aluminum alloy beverage cans comprising drawing and ironing an aluminum alloy sheet,
wherein during the ironing step, a friction higher between a bodymaker punch and the aluminum sheet than between an ironing die and said aluminum sheet is produced by
the aluminum alloy sheet having an internal surface higher in roughness than an external surface, wherein the external surface, in contact with the die, has a roughness Ra below 0.3 μm, and
the ironing die having a rounded intersection with a radius from 0.5 to 4.6 mm between an infeed surface and a land, a rounded intersection with a radius below 1.2 mm between said land and an exit surface, a roughness Ra below 0.03 μm in a working area, and a land width below 0.38 mm.
4. A manufacturing process of aluminum alloy beverage cans comprising drawing and ironing an aluminum alloy sheet,
wherein during the ironing step, a friction higher between a bodymaker punch and the aluminum sheet than between an ironing die and said aluminum sheet is produced by:
the aluminum alloy sheet having an internal surface higher in roughness than an external surface, wherein the external surface, in contact with the die, has a roughness Ra below 0.3 μm, and the internal surface, in contact with the punch, has a roughness Ra above 0.4 μm,
the bodymaker punch having a roughness Ra above 0.35 μm and an isotropic texture,
and optionally
the ironing die having a rounded intersection between an infeed as well as an exit surface and a land, with a surface in a working area having a roughness Ra below 0.03 μm and with a width of the land below about 0.38 mm.
5. The manufacturing process according to claim 4 which uses no internal cupper lubrication.
6. The manufacturing process according to claim 4 , wherein said ironing die has a rounded intersection with a radius from 0.5 to 4.6 mm between said infeed surface and said land, and a rounded intersection with a radius below 1.2 mm between said land and said exit surface.
7. The manufacturing process according to claim 4 , wherein
the ironing die has a rounded intersection with a radius from 0.5 to 4.6 mm between an infeed surface and a land, a rounded intersection with a radius below 1.2 mm between said land and an exit surface, a roughness Ra below 0.03 μm in a working area, and a land width below 0.38 mm.
8. The manufacturing process according to claim 4 which uses no internal cupper lubrication, and wherein the ironing die has a rounded intersection with a radius from 0.5 to 4.6 mm between an infeed surface and a land, a rounded intersection with a radius below 1.2 mm between said land and an exit surface, a roughness Ra below 0.03 μm in a working area, and a land width below 0.38 mm.
9. The manufacturing process according to claim 4 , wherein the aluminum alloy sheet has an external surface, in contact with the die, with a roughness Ra below 0.3 μm, and an internal surface, in contact with the punch, with a roughness Ra above 0.4 μm,
wherein the punch has an extra roughness characterized by a roughness Ra above 0.35 μm, with an isotropic texture, and
wherein the process uses no internal cupper lubrication.
10. The manufacturing process according to claim 4 , wherein the aluminum alloy sheet has an external surface, in contact with the die, with a roughness Ra below 0.3 μm, and an internal surface in contact with the punch, with a roughness Ra above 0.4 μm,
and the punch has a roughness characterized by a roughness Ra above 0.35 μm, with an isotropic texture, and
wherein the ironing die has a rounded intersection with a radius from 0.5 to 4.6 mm between an infeed surface and a land, a rounded intersection with a radius below 1.2 mm between said land and an exit surface, a roughness Ra below 0.03 μm in a working area, and a land width below 0.38 mm.
11. The manufacturing process according to claim 4 , wherein the aluminum alloy sheet has an external surface, in contact with the die, with a roughness Ra below 0.3 μm, and an internal surface, in contact with the punch, with a roughness Ra above 0.4 μm,
wherein the punch has a roughness characterized by a roughness Ra above 0.35 μm, with an isotropic texture,
the process uses no internal cupper lubrication, and
the ironing die has a rounded intersection with a radius from 0.5 to 4.6 mm between an infeed surface and a land, a rounded intersection with a radius below 1.2 mm between said land and an exit surface, a roughness Ra below 0.03 μm in a working area, and a land width below 0.38 mm.