SHIELD MACHINE AND METHOD FOR REPLACING ITS CUTTER BIT

摘要

PROBLEM TO BE SOLVED: To facilitate the rotation of a cutter spoke in a shield machine with cutter bits replaced by rotating the cutter spoke. SOLUTION: This shield machine is constituted to attach the cutter bits 6 movably along the radial direction of the cutter spoke 5. The shield machine is provided with energizing means 8 for always energizing the cutter bits 6 in a direction of being stored inside the cutter spoke 5, and push-out means 9 for pushing out the cutter bits 6. Only the cutter bit 6 used for excavation is thereby projected from the cutter spoke 5, and the cutter bits 6 not in use are held in the state of being stored in the cutter spoke 5 to prevent wear caused by friction or the like with excavated sediment. Further, preceding bits 7 with each tip part arranged on a locus described by the tip part of the cutter bit 6, are provided to excavate a natural ground part heretofore cut in by the cutter bit 6 when the cutter spoke 5 is rotated. Resistance during rotation of the cutter spoke 5 can thereby be reduced. COPYRIGHT: (C)2005,JPO&NCIPI