Batch mixing has come a long way from the two-roll mills to the current complete automatically operated internal mixers.There are three original internal mixer technologies in production today.The first technology,which was introduced in 1916 by F.H.Banbury,is the variable rotor L/D (Length-to-Diameter) ratio (1.40 to 2.00) tangential mixers coupled with partial single-circulation per revolution in the mixing chambers.The second technology,which was introduced in 1934 by R.T.Cooke,is the variable rotor L/D ratio (1.26 to 1.40) intermeshing mixers coupled with single-circulation per revolution in the mixing chambers.The third technology,which was introduced in 1998 by N.O.Nortey,is the optimized constant rotor L/D ratio (about 1.50) intermeshing mixers coupled with double-circulation per revolution in the mixing chambers.The constant large rotor L/D ratio intermeshing mixers are termed as the optimized stretch-intermeshing mixers.Sand-casting of rotors causes quality,strength and temperature problems.The current improved technique used in forging and machining of the 3-nog supercooled rotors for the optimized stretch-intermeshing mixers would be discussed in details.The machined internal passages of the supercooled rotors that provide better batch temperature control will be shown.Improvement in mixing Quality,Productivity and Energy will be tabulated for the three mixer technologies.
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