METHOD FOR MOULDING HOLLOW CONTAINERS IN MOLECULARLY ORIENTATABLE PLASTICS MATERIAL

摘要

Apparatus for moulding hollow containers in molecularly orientatable plastics material, which comprises a plurality of operating units, composed of at least one injection moulding group (2) for hollow preforms (19) having walls of great thickness, one or more axial elongation groups (3) for the preforms, at least one blowmoulding group (4) and at least one discharge unit (5), disposed in sequence at equal intervals along the closed path of a conveyor (6) having trollies (7) which can be advanced by steps, which trollies (7) possess jaws (15) adapted for gripping the neck of the preform and for supporting same throughout the entire travel through the conveyor. The method of moulding the containers comprises the successive phases of injection moulding an internally hollow preform, closed at one end, having walls of great thickness and a collar open at the top, of bringing the preform to a temperature at which a molecular orientation takes place as a consequence of a mechanical deformation in the plastics material, and at this temperature, of carrying out one or more axial elongations of the preform and of carrying out the blowmoulding of the elongated preform.