Method of extrusion blow moulding hollow containers and extrusion die to carry out said method

摘要

An additional variation of the nozzle gap (4) geometry to control melt flow can be achieved by a mechanically incorporated profiling or by an independent third adjustment or control of a positioning device (7). Profiling of the parison as it emerges from the nozzle is increased when the nozzle gap is broader than a set reference value and reduced when the nozzle gap is narrower than the reference value. An Independent claim is included for the extrusion head which apart from adjusters for both the mandrel (3) and nozzle gap geometry (4) includes an additional adjuster (7) for increasing the profiling of the emerging parison. Preferred Features: The profile influencing the melt flow is controlled according to a further program curve (HP) of the wall thickness program matched to the first program curve and/or according to the parison length so that the ratio of thick to thin areas remains constant independently of the nozzle gap produced by the first program curve (WDS). Alternatively the profile is controlled according to the additional program curve whose course comprises the functional values of the first program curve multiplied by a factor (F) which is NOTGREATER 1. Adjusters for the second program curve (RWDS) and the additional program curve are located behind each other.