Patent ID: 7101076
Filing Date: 2006-09-05
Classification: B29C

Abstract:
1. An extruder having a transfer region and comprising: an extruder sleeve that in said transfer region is provided with first ribs, wherein flow channels extend between said ribs, wherein said flow channels are U-shaped, wherein said U-shaped flow channels improve streaming behavior of material in the extruder sleeve; and an extruder screw disposed in said extruder sleeve and provided with second ribs between which extend flow channels that face said flow channels of said extruder sleeve, wherein said first ribs of said extruder sleeve have a ridge that faces said extruder screw, wherein said ridge has a width that corresponds to at least one third of a width of said flow channels of said extruder sleeve, wherein between ridges of said second ribs of said extruder screw and said ridges of said first ribs of said extruder sleeve a gap is formed that corresponds to greater than 0.5% of a diameter of said extruder screw, and wherein a thickness of the first ribs of the extruder sleeve is approximately a thickness of the second ribs of the extruder screw, wherein a sum of cross-sections of the flow channels shift toward the sleeve and then toward the extruder screw when viewed in a direction of extrusion, and wherein a width of the gap is approximately half a height of each said first and second ribs and, wherein the heights of said first and second ribs continuously change throughout the transfer region, whereas a sum of the heights remains constant.