Patent ID: 7357074
Filing Date: 2008-04-15
Classification: B30B

Abstract:
1. A screw for mounting in a compression screw dewatering device comprising: an elongated shaft having a longitudinal axis and having axially spaced apart first and second ends; a conveying section at the first end of the shaft, having a single helical screw flight rigidly projecting from the shaft; a flightless transition section having an axial length located axially adjacent the conveying section; and a dewatering section axially adjacent the transition section, having double helical screw flights rigidly projecting from the shaft the double helical screw flights of the dewatering section comprise a first flight extending for at least two revolutions along the shaft axis with a first pitch and a second flight extending for at least two revolutions along the shaft axis with a second pitch substantially equal to the first pitch and 180 degrees out of phase with the first flight; wherein the flight in the conveying section has a phase difference of at least 45 degrees relative to the flights in the dewatering section.