Plastics blow moulding - for hollow vessels with one or more openings using split mould tool

摘要

As well as the normal splits in the tool parallel to the axis which allow the moulding to be ejected, the tool is split along >=1 plane perpendicular to the axis along each of which a tear line is formed corresp. to the required opening in the moulded part. The tool parts mate in parallel circular surface whose length is the axial sepn of the tools required to split the part cured blown material from the blank along the tear line. This axial shaft is carried out with internal pressure maintained and the overlap of the tools prevents noisy escape of air; it is maintained whilst the moulding cools and then the cavity is vented and the tool split conventionally for ejection of the part. Expensive and bulky sound insulation is dispersed with.