Oscillating screw

A second crosshead extruder was introduced to damp out the oscillating flow [86] induced by the oscillating screw (see Fig. 9.19). Gear pumps were also used. 

There have been few basic studies of flow in Buss Kokneters. Only in the 1990s do we have pubUcations of Elemans and Meijer [89] and Lyu and White [90 to 95] with which to seek to understand and model the flow mechanisms and the flow fields in the various machine elements. Certain things are clear, such as the fluid mechanics indicates the axially oscillating screw inducing an oscillatory output. The machine operates under starved conditions with alternating fully filled and starved sections. The secondary extruder into which compounds exit from the Kokneter is starved and the length of fill oscillates but the output is uniform. This would feed a palletizing die. 

Procedure. Transfer a 20-ml level scoop of air-dry soil sieved to s2 mm to a 125-ml wide-mouth HDPE screw-cap bottle, add 50 ml 0.01 M calcium sulphate solution, and shake for 15 min on a reciprocating shaker (MAFF/ADAS use 275 strokes per minute. Northeastern US use 200 oscillations per minute). Filter through a 125-mm Whatman No. 2 filter paper into... 

From the granulating screw (5) the granulated product is fed to an ejector, whence it is transferred by the air flow created by a fan to a cycline separator (6), in which the granulated material is separated from the dust-air mixture. The dust is passed to the filters and the granules are fed to a spiral oscillating conveyer (cooler) (7). 

Measurements of sound velocity at ultrasonic frequencies are usually made by an acoustic interferometer. An example of this apparatus11 is shown in Fig. 2. An optically flat piezo-quartz crystal is set into oscillation by an appropriate electrical circuit, which is coupled to an accurate means of measuring electrical power consumption. A reflector, consisting of a bronze piston with an optically flat head parallel to the oscillating face of the quartz, is moved slowly towards or away from the quartz by a micrometer screw. The electrical power consumption shows successive fluctuations as the distance between quartz and reflector varies between positions of resonance and non-resonance of the gas column. Measurement of the distance between resonance positions gives a value for A/2, and if /... 

The Ko-Kneader developed by List in 1945 for Buss AG in Germany, is a single-rotor mixer-compounder that oscillates axially while it rotates. Moreover, the screw-type rotor has interrupted flights enabling kneading pegs to be fixed in the barrel (12). 

Oscillating kneader extruder, based on a single helical screw blade which in addition to its rotary... 

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