摘要 |
PROBLEM TO BE SOLVED: To prevent the generation of a body transmission sound during boring by a hammer drill and to shorten a boring time by applying press force for assisting press force by an operator to a hand-held concrete drill. SOLUTION: In the concrete drill, a bit driving shaft 4 is rotated by a driving source 2 housed in a main body 1, and a diamond bit 5 is fitted to the tip of the shaft 4 protruded forward from the main body 1 to bore concrete, etc. An excitation apparatus 8 for applying excitation force along the shaft 4 whose strength pulsates and changes to the main body 1 is installed in the main body 1. COPYRIGHT: (C)2003,JPO
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