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Feed zone for contra-rotating twin screw extruder for scrap film - has at least 3 helical grooves in each flight of same rotation as screw channel and specified angle
Feed zone for contra-rotating twin screw extruder for scrap film - has at least 3 helical grooves in each flight of same rotation as screw channel and specified angle
Feed zone for reclaiming scrap film in a contra-rotating twin screw extruder in which the screw flights have symmetrically disposed grooves in their peripheries. These are helically arranged in succeeding flights with the same hand (rotation) as the screw channel. The helix angle of the grooves may be three to four times pref. 3-7 times, the pitch angle of the screw channel. The helix angle is measured from the screw axis and is less than that of the channel. Pref. multistart screws with more than three grooves in each screw. the leading flank of each groove is at an angle to the screw axis at least approaching the helix angle of the grooves. ADVANTAGE - Improved feeding of scrap film and edge trim, avoiding thermal degradation during plastification. Makes possible as in-line scrap recovery process. (5pp Dwg.No.0/3)
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