| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide an apparatus for replacing underground tubes and capable of easily destroying existing tubes even in the case that the existing tubes are concrete tubes using steel collars and easily elongating vinyl chloride tubes. <P>SOLUTION: The apparatus (50) for replacing underground tubes is provided with a top (52); a body (53); and a newly-provided-tube connecting part (54). The top is provided with a plurality of rear petals (58) connected to the tip circumferential edge (56) of the body in such a way as to be rocked in radial directions; a plurality of front petals (60) supported at tips of the rear petals in such a way as to be rocked in radial directions; a tip cone (62) pivoting the tips of the front petals; at least one front blade (64) or more provided in the vicinity of rear ends of the front petals; a rear blade (66) positioned immediately in the rear of the front blade and provided in the vicinity of front ends of the rear petals; and an actuator (70) for rocking the front petals and the rear petals. <P>COPYRIGHT: (C)2008,JPO&INPIT</p> |
