EXCAVATION TOOL

摘要

PROBLEM TO BE SOLVED: To provide an excavation tool provided with a widening bit 4 and a pilot bit 7 capable of preventing breakage or the like of the shaft 7C and stably supporting the pilot bit. SOLUTION: The widening bit 4 positioned in the condition that it is made rotatable around the central axis X deviated from the axial line O is fitted at the outer periphery 1A of the front end of the device 1 rotated around the axial line O. The pilot bit 7 provided with a bit body 7A projecting to the further front end side than the widening bit 4 is locked by attaching it by fitting of the shaft 7C and the fitting hole 6A at the center of the front end 1A of the device 1. A recess 3 and a protrusion 9 which can be mutually fitted in the periphery around the axial line O are formed at the front end 1A of the device 1 and the rear face 7B of the pilot bit body 7A facing the front end face 1A. COPYRIGHT: (C)2004,JPO