BALANCED MULTIPLE HOT RUNNER COINJECTION TOOL

摘要

A hot runner mould for injection moulding multilayered mouldings by simultaneously injecting various plastic melts into several cavities has a hot runner block (23a-c) slidingly supported between a top plate (21) at the side of the extruder and a hot runner plate (22) at the side of the cavities. A joining piece (24) firmly secured to said hot runner block is coupled to a feed bush (12) slidingly mounted on the top plate (21). The hot runner plate (22) can thus expand freely with temperature changes and the compression forces of the extruder do not act upon the hot runner block (23a-c) but are absorbed by the top plate (21). The feed paths for the various plastic melts change thanks to the structure in several parts of the hot runner block (23a c) and to the controlled expansion movements of the hot runner block (23a-c) that are identical for all cavities.