Method and apparatus for the production of an optimized neck contour on preforms

An apparatus for production of a preform with a geometry at a transition beneath a neck that is optimized for a blow-molding process, wherein the preform has a considerably thinner wall thickness in a region beneath a thread than in the thread itself, the apparatus comprising:

• a mold with at least one mold cavity for definitive shaping of the preforms;
• an injection-molding apparatus that plasticizes raw plastic material to introduce the plastic material into the cavities with the closed mold under pressure, the mold having channels or slides that ensure that a required holding pressure is maintained in the neck despite the reduced wall thickness, or the mold is responsible for the preform geometries in a first shaping step;
• a removal arm, which is equipped with at least one cooled cooling sleeve, equal in number to the number of cavities, for removing the preforms, the cooling-sleeve having an inner geometry that provides the preform stem, but not the region of the preform neck, with contact cooling;
• and an embossing apparatus that has embossing elements mounted in a radially floating manner and use a cone to deflect an axial force perpendicularly to an axis and to intensify said force to an extent for an embossing operation that deforms the neck beneath the threaded part by pulling, pressing and pushing operations, said neck being defined by a cavity between the embossing elements and a supporting pin so as to describe the contour and wall thickness of the neck in a repeatable manner.