Patent ID: 8562203
Filing Date: 2013-10-22
Classification: B29C

Abstract:
1. An extruder having a process section with a housing in which at least one processing screw shaft is disposed and which has at one end a material inlet opening for material to be processed, and at the other end a material outlet opening for processed material, and between the material inlet opening and the material outlet opening, an intermediate opening being provided in said housing for the escape of gas from the process section, said intermediate opening having connected thereto a material retaining device which has, in an intermediate housing, at least one backfeeding screw shaft extending from the intermediate opening to a gas outlet opening in the intermediate housing and conveying material penetrating into the intermediate housing back into the process section, characterized in that said backfeeding screw shaft is rotatably driven by a drive unit in a rotation direction during shaft rotation, and comprises opposite first and second shaft ends respectively defining a backfeeding first screw portion and a conveying second screw portion, said backfeeding first screw portion of the backfeeding screw shaft being provided in said intermediate housing so as to receive said material from said process section through said intermediate opening and facing the process section so as to have a backfeeding direction of thread backfeeding said material back into the process section from said first shaft end and through said intermediate opening during said shaft rotation, and said backfeeding screw shaft having said conveying second screw portion connected to said first screw portion and facing away from the process section which said second screw portion has an opposite conveying direction of thread so as to receive any of said materials penetrating past said first screw portion and conveying said materials away from said first screw portion and said process section toward said second shaft end during said shaft rotation.