Blow mouldings with local thicker areas - made by extruding parison with e.g. two thicker parts, inserting two tools to press those parts, withdrawing them, and blow moulding normally

摘要

Blow mouldings are produced with at least one thicker area. In the process a parison is first held between the two parts of the blow mould, an expander tool with a surface to match part of the mould is inserted into the parison whose part concerned is that where the moudling is to be made thicker, this tool is moved against that particular part of the mould and grips the parison accordingly, the mould is then closed and compressed gas is blown in the parison. The parison is pref. made of reinforced plastics and the expander tool is pref. non-reinforced polymer. ADVANTAGE - The process precisely controls the wall thickness of the moulding at a particular part. The invention also covers the moulding system used