To provide a double pipe type excavating tool capable of positively jacking a pipe body into the ground without breaking a connection part by striking force or reducing impact force, vibration and noise when striking.
In the double pipe type excavating tool 1, an outer pipe 40 is connected to a ring bit 10 through a shock absorbing structure of the pipe body. The shock absorbing structure of the pipe body is constituted by winding a spring member 7 formed of an elastic member 5, into a fitting clearance formed when screwing an external thread 24 provided at a top joint 20 connected to the ring bit 10, with an internal thread 33 provided at the outer pipe 40. Threads 41, 24 may be formed at a part of an overlapping connection part 3 of the outer pipe 40 and top joint 20 without being formed over the whole length of the connection part 3, and the spring member 7 wound up in coil shape may be interposed at a part where the threads 41, 24 are not formed.
COPYRIGHT: (C)2007,JPO&INPIT
KUSANO KATSUHIRO
WATANABE KIYOMI
Souji Sasaki
Noboru Omura
Saburo Kimura
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