Screw blister ring

FIG. 18-50 Intermeshing corotating twin screw extruder (a) drive motor, (h) gearbox, (c) feed port, (d) barrel, (e) assembled rotors, (f) vent, (g) barrel valve, (h) kneading paddles, ( ) conveying screws, (/) splined shafts, (k) blister rings, (APV Chemical Machinery, Inc.)... 

Figure 8.23 Schematic of blister ring mixers a) a blister mixer positioned in a metering section, b) blister section positioned at the discharge end of the screw near the tip, and c) the cross-sectional view showing the region of annular flow between the screw and barrel wall (courtesy of ieff A. Myers of Robert Barr, Inc)...

Fig. 24. Dispersive mixing sections for use in single-screw extruders (a) blister ring, (b) Union Carbide mixing section, (c) Egan mixing section, (d) Dray mixing section [148]...

Mixing screws — S-shaped kneader, Eagle mixing. Turbine mixing, Cohen double-wave, or Maillefer screws with pin-, blister ring-, fluted-, barrier-screw. Dynamic Extentional Flow Mixer (DEEM), etc. 

The annular blister ring is simply a smooth cylindrical screw section with a small radial clearance. All the material has to pass through this clearance to exit from the extruder. Since no positive drag transport takes place over the barrier clearance, the... 

Fig. 2. Intermeshing corotating twin-screw extruder A, motor B, gear box C, feed port D, clam shell barrel E, vent port F, screw shafts G, conveying screws H, kneading paddles I, barrel valve and J, blister rings. Courtesy of APV Chemical Machinery Inc.

Restrictive discs and blister discs restrict the melt flow over the entire cross-section of the barrel bore. Blister discs (Fig. 12.35) are drilled cylinder discs arranged concentrically around the screw shaft with a defined gap with respect to the barrel wall. A ring is fitted to the counter shaft similar to the TME element. This blocks the entire cross-section of the... 

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