SCREW CONVEYOR FOR SHIELD MACHINE

PURPOSE:To prevent a screw blade from being broken, and improve discharge efficiency for excavated sediment by providing a cutter chamber between the front wall of a shield frame and the rear side of a cutter frame, transferring the excavated sediment from the cutter chamber to a place behind a shield on a screw conveyor, and moving the screw blade in an axial direction. CONSTITUTION:When a shield machine 1 under propulsion passes a silt layer or a sand layer, a screw blade travel means 41 is operated for contraction, and the leading end of a screw blade 25 is projected substantially into a cutter chamber 9. Sediment containing silt or sand and entering the cutter chamber 9 is, then, efficiently transferred therefrom to a screw conveyor 21, thereby increasing discharge efficiency with the conveyor 21 and the advance speed of the shield machine l. Also, when the shield machine l under propulsion passes a gravel layer, the means 41 is elongated and the leading end of the blade 25 is made to retreat within an opening 901. According to this construction, excavated sediment can be efficiently discharged with the conveyor 21, while the break of the blade 25 being prevented.