| 摘要 |
PURPOSE: A closed drilling machine is provided to prevent water in a water supply pipe from gushing, and to easily and safely drill the water supply pipe. CONSTITUTION: A closed drilling machine is composed of a pipe screw unit(1), a main body(2), a drill(4), a protrusion(7) for preventing the drill from being pushed into a pipe, an O-ring(5) for sticking a drill body(10) fast to the main body and a pressure regulator(9), a packing(6), and a washer(8).
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