Auxiliary device and method for finishing preforms

A method for finishing a preform having a threaded part, a necking ring and a blow-molded part, comprising the steps of:

• removing the preform in a hot and unstable state from open mold halves of an injection molding machine;
• inserting the preform into a cooling sleeve for an outer cooling of the preform;
• pressing the preform by compressed air onto an interior wall of the cooling sleeve within a time period of an injection molding cycle to thereby calibrate the preform,
• wherein, for the calibration, a press ring is attached to a nipple and inserted, in a position-controlled manner, into the preform,
• wherein the press ring is squeezed between two holding shoulders which are movable relative to one another, and mechanically bulged until the press ring contacts an interior wall of the preform in a manner analogous to a thermos bottle cap, wherein an interior of the blow-molded part of the preform is sealed towards the outside by generating a force that is directed radially in a direction of the interior wall of the preform, and
• wherein the blow-molded part is pressed against the interior wall of the cooling sleeve and calibrated by compressed air introduced via the nipple.