Process for producing a foam body by extrusion and extrusion apparatus for producing a foam body

摘要

A method for producing a foam body by extrusion, comprising: - producing a plastic melt within a jacket (131) of a first extruder (20, 120, 220); and conveying the plastic melt to an outlet nozzle (50, 150, 246) of a second extruder (40, 140, 240) having an extruder screw device (142), the conveyed plastic melt having and expanding propellant after passing through the outlet nozzle (50 , 150, 246), wherein in first longitudinal sections (1.1, 1.2) of the extruder screw device (142) of the second extruder (40, 140, 240) the plastic melt is conveyed and mixed and in second longitudinal sections (2.1, 2.2) of the extruder screw device ( 142) of the second extruder (40), the plastic melt is conveyed and pressure is built up in the plastic melt, wherein the plastic melt is alternately passed through first and second longitudinal sections (1.1-2.2) and thereby before passing the plastic melt through the outlet nozzle (50, 150 , 246) through temperature differences between different radial positions in the cross section of the plastic melt is reduced and the thus thermally homogenized plastic melt through the outlet nozzle (50, 150, 246) is guided, and further wherein the pressure before the second extruder (40, 140, 240) only on the speed of the second extruder (40, 140, 240 ), but not by the pressure at the outlet nozzle (50, 150, 246) is determined, so that pressure losses are compensated.