Improvements in rotor design

Reprinted with permission from K. Nakagawa and I. Amano, Journal of the Society of the Rubber Industry, Japan, 1980, 53. Copyright 1980. 

In the example of the model-calculation, the comminution mechanism has taken place within 22.5% of the total volume charged. The rest, 77.5% of the volume, is presumably undergoing the macroscopic homogenisation. The question is whether 77.5% of the volume charged is really effectively worked in the mixer or not. 

In general, a semi-quantitative interpretation [54] is that effective mixing takes place only in front of the rotor between the rotor tip and the chamber wall. In the backside of the rotor little mixing takes place, but since material occupies this space also, it results in a waste of energy. This means that a larger number of rotor wings would be expected to improve the efficiency of mixing. 

The four-wing type has an added advantage in that it gives a better force-balance on the rotor shaft than the two-wing does. The force in the axial direction is considerably less for the four-wing rotor than the two-wing rotor. This also contributes to a better energy efficiency [54], 

According to the conventional interpretation, the mechanisms of the material transport entail both pressure flow and drag flow [55]. Material transport through the gap between the rotor tip and the chamber wall is affected by the drag flow and a part of the pressure flow, i.e., in the through direction. However, the pressure also pushes the material backwards. The latter does not contribute to effective mixing, except perhaps in macroscopic homogenisation. 

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World War Two, highlighting the improvements in rotor design, better knowledge of mixing techniques, and the increase in throughput rates for all types of compounds. The article focuses on the necessity of ensuring that temperature control systems have kept pace with these developments. 

Vibration is a major destmctive force in many types of machinery. Vibration can lead to wear and fatigue failure of rigid materials like alloys and plastic components. The helicopter benefits from the unique flexibility and vibration dampening characteristics of elastomeric adhesives. Elastomers are used to transfer torque to the rotor blades while providing flexibility and vibration control. Rubber tires are another example of elastomeric adhesive use. Consumers have enjoyed a steady increase in the useful life expectancy of rubber tires due to improvements in adhesion between the elastomer, tire cords, and the filler. The rubber tire industry has driven a great deal of the fundamental research on elastomeric materials in engineering design. 

In the tangential machine a thermocouple mounted in the end frame is more robust, but is often far less responsive than one mounted in the door top, although recent rotor designs which improve material flow to the ends of the mixing chamber should have improved the response of endframe thermocouples. Infrared probes are most commonly fitted in an endframe. 

Improved productivity in the rabber industry is defined by mixing a better quality rabber in the same amormt of time or less and/or mixing more of the same quality rabber in less time. Equipment (mechanical) parameters that affect productivity are discussed, iucluding milliug versus internal rrrixing, mixer size, rotor design, mixing parameters, rotor speed and material addition. The improvement of productivity via the combination of various parameters is corrsidered. 1 ref. 

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