Injection molding apparatus for manufacturing hollow objects, in particular plastic preforms, resp. containers and method therefor

Injection molding apparatus for manufacturing multi-layered hollow plastic preforms, comprising an injection mold (1) with a front (2) and a rear side (3), which is composed of a clamping plate (4) on the rear side (3), and a hot runner plate (5), where in the hot runner plate a manifold (6) is mounted, between which a set of injection molding nozzles (7) is arranged, which are each provided with a substantially centrally arranged supply duct (8), at the free end (9) whereof an injection gate (10) is provided, wherein each said injection nozzle (7) is directly removable individually from the injection side (16) on the front side (2) of the injection mold at the injection side thereof, wherein each said injection nozzle comprises a profiled inner part removable from the injection side (16) on the front side (2), wherein said injection gate (10) is closable by a locking rod (11) movable therein to and fro through the profiled inner part (12) which is received in a holder (13) around which a heating element (14) is provided into which at least one primary duct (15) passes through for supplying primary plastic base material to the injection gate (10) for forming a primary layer, wherein a respective secondary duct (17) is provided separately,

• wherein each said injection nozzle comprises an inner channel and an outer channel around the inner channel, wherein the inner channel is within the profiled inner part (12) and the outer channel is around the profiled inner part in the nozzle, and
• wherein said inner part (12) is supported substantially centered in the holder (13) of the injection molding nozzle (7) thereof, and wherein said profiled inner part (12) has a conical end with a decreasing annular slope extending from a downstream to an upstream direction of flow of the plastic base material, and
• wherein the primary duct (15) supplies material to the outer channel and the secondary duct (17) supplies material to the inner channel proximal the conical end.