Extruder and screw therefor for effecting transverse currents in work material handled thereby

Abstract From the Canadian patent

A heating device having a screw rotatable within a barrel therefor, such as a part of an extruder especially, constructed to circulate and heat a granular or particulate work load of fusible material while still in its particulate condition. The essential purpose is to heat the material to a uniform temperature just under plasticization in preparation for entering melting apparatus, such as a downstream melting section of an extruder. The screw has a core and a main thread defining a main channel in which the portions of the core surface extending side-by-side longitudinally of the channel deviate from an average core diameter throughout the length of the heating device to circulate the …