Extruder with interacting auger and care means

Claim 1

Apparatus for forming concrete aricles, comprising: a hopper, a conveyor section, a consolidation section and a molding station; said molding station including form surfaces; at least one auger for conveying concrete mix along said conveyor section, said auger having flights for extruding said mix through said consolidation section and into said molding station; at least one mandrel formed by walls having external surfaces in the path of extrusion from said auger flights; said auger being rotationally independent from said mandrel; said auger and said mandrel being relatively disposed so that the longitudinal axis of said auger is lateral of the longitudinal axis of said mandrel; said hopper including means for introducing concrete mix to said auger; means for rotating said auger to convey said mix to the form surfaces of said molding station with sufficient force to consolidate said mix and extrude the consolidated mix relative to said form surface; means for slideably securing said molding station form surfaces whereby to permit reciprocal movement along their planes; and means for reciprocally vibrating said form surfaces along their planes at a frequency greater than 22,000 vibrations per minute, during the extrusion, to reduce friction between said form surfaces and said mix.