Apparatus for calibrating and supporting an extruded tube, inflated to form a film bubble

摘要

The invention relates to an apparatus for calibrating and supporting an extruded tube of polymer melt, inflated to form a film bubble, in a blown-film installation, which comprises supporting pins which can be positioned approximately tangentially against the film bubble, bound a square having preferably curved sides and approximating a circle, and whose carrying bars, parallel to the tube axis, are in each case articulated on an outer basket-shaped frame by two levers provided with adjusting drives, in such a way that they can in each case be moved in their planes by equal amounts in a radial direction. In order with such an apparatus to avoid vibrations of the carrying bars, carrying the supporting segments, when setting the supporting segments to different diameters of the film bubble, the two levers comprise control arms whose inner ends are articulated in the central region of each carrying bar and whose outer ends are articulated on brackets which form parts of frames which carry at at least two points spindle nuts into which there are screwed sections, provided with opposing threads, of spindles which are mounted on the basket-shaped frame, are axially parallel and are provided with drives. Arranged at a distance from one of the control arms is an additional control arm, parallel to the latter, whose ends are articulated on each carrying bar and on a bracket.