Method for manufacturing a metal packaging in the form of a bottle
Disclosed is a method for manufacturing a metal packaging in the form of a bottle. The method includes a step of forming a tubular part, in order to form a threaded neck. This manufacturing method includes, prior to at least one operation for forming a roll, preferably prior to the step of forming the tubular part, a step of localised annealing which is carried out in order to confer an annealed state on the tubular part, at least over the height of a downstream strip of the tubular part intended to be formed into a roll.
1 . A method for manufacturing a bottle-shaped metal packaging, said metal packaging having a body connected to a threaded neck through a shoulder, said method comprising:
a step of manufacturing a preform including a tubular part, defining a longitudinal axis and a free, downstream edge, wherein said tubular part is connected to a body through a shoulder, and
a step of forming said tubular part, to form said threaded neck,
said forming step comprising forming operations suitable to form one-piece structures on said tubular part:
an operation of forming a roll within a downstream strip of said tubular part, ended by said downstream edge, to form the roll at the downstream edge of the threaded neck,
an operation of forming a thread within an intermediate strip of said tubular part, and
an operation of forming a transport ring within an upstream strip of said tubular part, on the shoulder side, configured to cooperate with a handling device,
wherein said manufacturing method comprises, prior to at least said roll forming operation, a localised annealing step that is carried out in order to provide an annealed state to the tubular part, at least over a height of the downstream strip of said tubular part,
wherein the localised annealing step is executed to provide the annealed state:
only at said downstream strip, or
only at the downstream strip and the upstream strip, in such a way as to keep at least part of a height of the intermediate strip in non-annealed state.
2 . The method for manufacturing a bottle-shaped metal packaging according to claim 1 , wherein the localised annealing step is carried out in order to provide the annealed state over a height of at least 3 to 7 mm of the downstream strip of said tubular part.
3 . The method for manufacturing a bottle-shaped metal packaging according to claim 1 , wherein the localised annealing step is carried out in order to provide the annealed state over a height of the upstream strip of said tubular part.
4 . The method for manufacturing a bottle-shaped metal packaging according to claim 1 , wherein the preform manufacturing step comprises:
a phase of deforming a metal part to obtain a primary preform having a bottom extended by a tubular wall,
an edge trimming phase, to form the downstream edge of said primary preform, and
a necking step, to form said tubular part of a secondary preform,
and wherein said localised annealing step is carried out on the tubular wall of the primary preform, before the necking step.
5 . The method for manufacturing a bottle-shaped metal packaging according to claim 1 , wherein the localised annealing step is carried out by an induction technique.
6 . The method for manufacturing a bottle-shaped metal packaging according to claim 1 , wherein the transport ring forming operation is implemented prior to the roll forming operation.
7 . The method for manufacturing a bottle-shaped metal packaging according to claim 1 , wherein the tubular part forming step also comprises an operation of forming a pilfer-proof counter-ring within an additional strip of the tubular part, located between the intermediate strip and the upstream strip, forming a pilfer-proof counter-ring groove between said pilfer-proof counter-ring and said transport ring.
8 . The method for manufacturing a bottle-shaped metal packaging according to claim 1 , wherein said method also comprises a varnishing phase.
9 . The method for manufacturing a bottle-shaped metal packaging according to claim 1 , wherein said metal packaging is made in a 3000 or 5000 series aluminium alloy.
10 . The method for manufacturing a bottle-shaped metal packaging according to claim 1 , wherein the transport ring forming operation is selected among:
a moulding technique, or
a direct mechanical action using a movable tool, or
an overlying and underlying necking technique.
11 . The method for manufacturing a bottle-shaped metal packaging according to claim 1 , wherein the transport ring forming operation comprises a calibration phase to give a definitive shape to said transport ring.
12 . The method for manufacturing a bottle-shaped metal packaging according to claim 11 , wherein the calibration phase consists in:
bringing an upper connection radius and a lower connection radius of the transport ring in contact with each other, or in obtaining an upper connection radius and a lower connection radius of the transport ring that are radially offset with respect to each other, with said lower connection radius, and/or
bringing the external radius of the transport ring to a minimum radius acceptable to the constituent material.
13 . The method for manufacturing a bottle-shaped metal packaging according to claim 12 , wherein the calibration phase is made:
by clamping an annular deformation between two calibration rings, which are coaxial to the longitudinal axis of the tubular part, or
by two wheels rotating about the tubular part.
14 . The method for manufacturing a bottle-shaped metal packaging according to claim 1 , wherein, during the transport ring forming operation, an axial load is exerted on the metal packaging to accompany the metal in its deformation and avoid thinning and breakage.
15 . The method for manufacturing a bottle-shaped metal packaging according to claim 1 , further comprising a step of putting a metal capsule on the threaded neck.