| 摘要 |
A tip element 32 for attachment to an end of an extruder screw 30 comprises a substantially cylindrical screw root having first and second end faces, the second end face being configured to locate, in use, adjacent to an end of said extruder screw; a helical flight extending radially outwards from the screw root turning through an angle of 720° or less between first and second ends, wherein a width of the flight is greater at the first end than the second end, and wherein the tip element is made of a metal material and a hardness of the tip element is substantially constant throughout the helical flight. The tip element preferably comprises an axial bore extending between the end faces. An extruder screw assembly is further provided comprising a main screw component 30 having a first end configured for connection to a means for rotating the screw component, the tip element of the invention configured to locate adjacent to the second end of the screw component, a nose element 34 including an elongate tapered portion and a means for securing the nose element and the tip element to the main screw element. The screw extrusion apparatus is preferably for forming biomass extrudate for use as a fuel. |
