| 摘要 |
PURPOSE: To improve workability by arranging a roller cutter or a roller-like cutter with a tool bit fitted thereto in non-drilling territory between cutter discs, when a plurality of circular cutter discs are put side by side. CONSTITUTION: Roller cutters 6 in which cutter bits are planted on the circumferential faces of rotary drums, are arranged on gull parts which are non-drilled territories of mutual cutter discs 1a, 1b. In this case, the outer circumference of a drilled locus of the cutter 6 is continued to the outer circumference of the drilled loci of the cutter discs, so as to form an ellipse as a whole. Next, instead of the cutter 6, a roller-like cutter with a tool bit fitted thereto can be arranged. When a shield machine is drillingly advanced, mutual non-drilled territories of the cutter discs 1a, 1b are cut by the cutter 6, and the cut territory is continued to those of the cutter discs 1a, 1b. Hereby, increase of thrust and troubles in direction control can be prevented, a deformed section can be formed, and a center pillar can be made unnecessary. |
