The combination of an extruder with a wide extrusion head and a calender is known from German Offenlegungsschrift No. 2,229,828. So-called roller head units of this type are used to form wide webs of material which has been plasticized by the extruder, in particular rubber mixes which emerge in the form of an already wide pattern from the wide extrusion head and are then calendered in the roll nip of the calender into sheets or layers of exactly determined thickness. In order to permit cleaning of the sheet extrusion die of this known machine, the wide extrusion head is divided into an upper extrusion head part and a lower extrusion head part. The upper extrusion head part is joined to the extruder housing, while the lower extrusion head part is mounted in a fixed position on the side walls of the calender frame.
Clamping devices are fitted to the side walls of the calender frame, which clamping devices comprise a hydraulically operable piston cylinder drive, the free end of the particular piston rod being capable of being pressed against the upper side of the upper extrusion head part while the latter is in the working position, whereby the upper extrusion head part and the lower extrusion head part are pressed together. The considerable forces arising during operation and effecting an expansion of the sheet extrusion die are absorbed by the side walls of the calender frame in this known design. This design is disadvantageous because the large forces introduced in this way into the side walls of the calender frame make a fine adjustment of the roll nip between the calender rolls very difficult. Moreover, the side walls of the calender frame are exposed to extremely high loadings. It is very costly to size the calender frame in such a way that these drawbacks are overcome.
It is known from German Auslegeschrift No. 2,413,844 to construct a wide extrusion head for extruders from an upper extrusion head part and a lower extrusion head part, which parts can be tilted away from one another in order to facilitate cleaning.
From British Pat. No. 998,725, an extruder having a wide extrusion head with a calender is generally known.
USPTO Backgrounds
USPTO Backgrounds