1. Field of the Invention
The invention concerns a method of cold shaping a metal can body and a can body shaping installation adapted to implement it.
2. Description of the Prior Art
One prior art can shaping method is usually applied to can bodies assembled from at least two components, typically a tubular part and a bottom crimped to one end thereof. The tubular part may be a cylinder of circular, rectangular or square cross-section. This method uses a mechanism forming a core adapted to be inserted axially inside the can body through the opening thereof and having sectors adapted to be moved apart in the radially outward direction until they contact the inside wall of the can body to be shaped. This deforms the can body permanently and the resulting shape depends on the shape of the core sectors. In a system of this kind the deforming means and the actuating system thereof are essentially mechanical. Cans shaped in this way have shortcomings in respect of their appearance which are inherent to the shaping system itself. In particular, the imprints of the various sectors are visible on the can body walls. This means that the latter cannot have a perfectly regular surface. These imprints may even cause scoring of the varnish and lead eventually to corrosion. They may also lead to rupturing of the can. Additionally, the mechanism is complex and costly.