Throttling device for a twin-shaft srew-type extruder

Claim 1

Throttling device for a twin-shaft screw-type extruder comprising: a housing (2) having cylindrical bores (4, 5) with walls (8, 9) which penetrate one another while forming saddles (10, 11) with saddle edges (12, 13) and which are axially parallel to one another; rotatable shafts (20, 21) being arranged in the cylindrical bores (4, 5) and having screw elements (32, 36) meshing with one another; a transfer channel (40, 41) being formed in the wall (8, 9) of each cylindrical bore (4, 5) and running in a peripheral direction of the wall (8, 9) and extending in a conveying direction (29); a retaining plate (47, 48) being provided on each shaft (20, 21) and being associated with one of said transfer channels (40, 41); the housing (2) and the shafts (20, 21) being displaceable relative to one another in the conveying direction (29) in such a manner that each retaining plate (47, 48) overlaps with the associated transfer channel (40, 41) or with the wall (8, 9) of the cylindrical bore (4, 5) in which the retaining plate (47, 48) is provided; and wherein the retaining plates (47, 48) having a cylindrical outer surface (49) and the transfer channels (40, 41) associated with the retaining plates (47, 48) are in a staggered arrangement relative to one another in the conveying direction (29), wherein the transfer channels (40, 41) do not pass through the saddles (10, 11) in the area of the saddle edges (12, 13), and wherein flow restricting gaps (50, 51) are formed between retaining plates (47, 48) and associated walls (8, 9) of respective cylindrical bores (4, 5) with at least partially axial overlapping.