| 摘要 |
PROBLEM TO BE SOLVED: To provide a hole drilling device capable of connecting a bit body with a pipe securely and inexpensively. SOLUTION: This hole drilling device is attached to a hole drilling rod inserted into a pipe to be buried and drills a hole by entering the hole together with the pipe to be buried. This hole drilling device is provided with the bit body provided with a cutting edge body for drilling hole in a tip part, a transmitting member attached to a tip part of the hole drilling rod to transmit hitting force, thrust, and rotating force of the hole drilling rod to the bit body, a cylindrical traction member which is attached to a tip part of the pipe to be buried and in which the transmitting member is inserted, and a cylindrical connection member for connecting outer peripheral faces of the bit body and the traction member mutually. Recessed parts extended in the peripheral direction are formed on the outer peripheral faces of the bit body and the traction member, respectively. Both of end parts in the axial direction of the connection member are engaged with the recessed parts of the bit body and the traction member, respectively. At least either of both of end parts of the connection member is rotatably engaged with the recessed part, and at least either of both of them is additionally tightened and is fixed. COPYRIGHT: (C)2009,JPO&INPIT
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