| 摘要 |
An extruder for extruding an elongate plastics member 32, comprises a rotatable screw 12 within a barrel 14 for extruding plastics material through an extrusion head 20 of the extruder provided with an extrusion die 22. A breaker plate 18 (50, 80) is positioned upstream of the die 22 and causes plastics material which is radially inwardly of plastics material adjacent the barrel 14 upstream of the plate 18 to be radially outwardly thereof downstream of the plate 18 such that an outer surface layer of the elongate plastics member 32 extruded by the extruder comprises the material which was radially inwardly of the material adjacent the barrel upstream of the plate 18. This arrangement reduces the time taken for a colour change. <IMAGE> |
