Crown retainer of metal foil and its projection shape

摘要

Recently, a large number of crown retainers of metal foils pre-shaped by cold plastic deformation have been disclosed. These retainers have at least two soldering surfaces. On the contrary, the crown retainer according to the invention has only one soldering surface, so that the retainer itself has only a single foil thickness over the major part of its circumference. The crown retainer is formed from an approximately trapezoidal foil piece which is provided with incisions and cutouts and tongue-shaped flaps by rolling inwards to form a funnel-like basic shape.