An apparatus for producing an extruded film tube and supplying said tube to a
collapsing and roller assembly includes a die for extruding a molten material in
the form of a tube which is in a molten state below a frost line and in a solid
state above the frost line. A blower system supplies and exhausts cooling air to
and from an interior portion of the tube, and is regulated by a valve. At least
two sensors are provided, one below the frost line for sensing the position of
said tube, and one located proximate the tube in a position above said frost line.
The upper sensor is used for sensing the position of the tube prior to collapsing
and flattening it. A controller receives feedback signals from both sensors and
controls operation of the valve.
