| 摘要 |
In an extrusion head and an extrusion method for the production of a tubular multilayer preform the extrusion head includes at least two feed paths for feeding plasticised plastic material from one or more extruders to an annular passage arrangement. The annular passage arrangement includes mutually concentric annular passages forming mutually separate flow paths for the various layers of the preform. An annular gap nozzle has an annular gap communicating with the annular passage arrangement, and at least one flow passage communicates with an annular passage of the annular passage arrangement, for the introduction of a translucent viewing strip. The flow passage communicates with the annular passage in question upstream of the annular gap in the region of separation of the flow paths.
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