Appts. for mfg. hose from extruded parison which is fed continuously into a moving mould composed of recirculated split mould sections against which the parison is distended with compressed air to be forced against the corrugations in the mould sections has the corrugations at the troughs provided with peripheral arrays of ven holes for expelling the air from the mould sections due to the parison being expanded. Vent holes, which are extending radially, are connected to ducts delimited by external faces of the sections and guide faces of the guide member for the sections, the ducts which are supplied with high speed cooling air acting as ejectors and induce partial vacuum in the vent holes. Formation of surface irregularities induced by air pockets in the mould cavities is prevented.
展开▼
