Cooling device for extruded preform for blow moulding - has ring die with two annular distribution chambers linked by throttling gap and feeds cool air via throttle nozzle to preform

摘要

The invention relates to a cooling device for an extruded tube which is subsequently blow moulded. The extruded preform hangs from a die and is cooled over a section of the length and around the whole circumference by a gas. Cooling of the outer surface allows preforms of relatively long lengths and constant thickness to be extruded. Cooling is achieved by a ring-shaped nozzle having two ring-shaped distribution channels linked to each other by a ring throttling gap. Gas from the second distribution channel passes through a further throttling nozzle and reaches the tubular preform surface where it flows through an annular gap between preform and outer pipe. USE/ADVANTAGE - In continuous or semi-continuous extrusion blow moulding. Even polymers such as PET, which permit only certain lengths of preform to be produced, can be used.