| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a cutter head capable of efficiently breaking an existing buried pipe of which part for connecting a nonmetallic pipe-like body is fitted with a metallic collar, and structurally simple. <P>SOLUTION: A roller cutter 12 cuts into and breaks a rear end part of a nonmetallic pipe-like body sequentially, and cuts into a rear end part 9a of a metallic collar 9 to form cracks. A front end part 13a of a pressing deformation member 13 deforms each of portions of the rear end part 9a, in which cracks are formed and which are circumferentially separated from each other, forward in a propulsion direction. The rear end part 9a of the metallic collar 9 can be also sequentially broken by repeating crack forming action by the roller cutter 12 and pressing deformation action by the pressing deformation member 13. <P>COPYRIGHT: (C)2012,JPO&INPIT |
