MULTIPLE-SCREW EXTRUDER

Single screw extruders Buss-Kneader Twh screw extruders Multiple screw extruders ... 

The dynamic seal is a reverse extruder created by machining small multiple-screw channels onto the rotor end rotating in the closed housing. Because of the helix angle, they will pump melt back into the mixing chamber. 

Single screw extruder 1, Twin screw extruder 1 Multiple screw extruder 1... 

The best place to start is with a brief account of the origin of all multiple screws, namely the single screw extruder. Its inventor, Archimedes [1] (approximately 2250 years ago), used it to transport water overcoming differences in elevation. The same principle is still used today in Egypt, Holland, and in many water purification plants. 

Claim is laid in this patent for double-flighted and triple-flighted shoulder elements in a multiple screw extruder, particularly in a ring extruder. A low product stress and decreased energy input result. 

The twin-screw extruder may have parallel or conical screws, and these screws may rotate in the same direction (co-rotating) or in opposite directions (contra-rotating). Extruders with more than two screws are known as the multiple-screw extruder. These extruders are normally used when mixing and homogenization of the melt is very important, in particular where additives, fillers, and/or reinforcements are to be included in the plastic. 

Polyolefins LDPE, LLDPE, HDPE, PP Solid concentrates Internal mixers, continuous mixers, multiple-screw extruders... 

Multiple-screw extruders (that is, extruders with more than a single screw) were developed largely as a compounding device for uniformly blending plasticizers, fillers, pigments, stabilizers, etc., into the polymer. Subsequently, the multiple-screw extruders also found use in the processing of plastics. 

Multiple-screw extruders can involve either two screws (twin-screw design) or four screws. A typical four-screw extruder is a two-stage machine, in which a twin-screw plasticating section feeds into a twin-screw discharge section located directly below it. The multiple screws are generally sized on output rates (Ib/h) rather than on L/D ratios or barrel diameters. 

Cheremisinoff, N. R, Multiple screw extruders. In Cheremisinoff, N. P. (ed.). Polymer Mixing and Extrusion Technology. Marcel Dekker, Inc. New York, 1987. 

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