To prevent blocking in a suction pipe tip part by equipping a blowoff pipe of compressed air in the suction pipe, to open the blowoff port of the blowoff pipe near the tip of the suction pipe.
A blowoff pipe 20 for compressed air is equipped in a suction pipe 14, to open the blowoff port 26 of the pipe 20 in the vicinity of the tip part 15 of the pipe 14. Another end part of the pipe 20 is connected to the discharge port of an air compressor 19 via a flexible hose 22. For cleaning a drilled hole 11, the pipe 14 is inserted into the hole 11 to drive a suction device 16, to suck rock pieces 12, etc., from the tip part 15 of the pipe 14 while blowing off the compressed air from the port 26 of the pipe 20. Since the pieces 12 and so on becoming a block state are dispersed into an individual particle by the blowoff of the compressed air, the pieces 12 and so on can be smoothly sucked from the tip part 15 of the pipe 14.
MITARAI YOSHIO
KAKIUCHI YUKIO
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