To prevent the removed earth clogging of a drilling device having double pipe structure by smoothly removing earth.
A drilling device has the inner pipe 10 and outer pipe 12 of double pipe structure. The outer pipe 12 has an inside diameter larger than the outside diameter of the inner pipe, and an earth removing path is formed between these pipes 10, 12 when the inner pipe 10 is inserted on a concentricity in the outer pipe 12. One end side of the earth removing path is opened to the outside at the front end section of the outer pipe 12. A double rotary 20 rotating and driving the outer pipe 12 and an earth removing swivel 22 being communicated with the earth removing path and extracting removed earth D to the outside are arranged on the rear end side of the outer pipe 12. A discharge opening 24 communicated with the inside is formed to the outer circumference of the earth removing swivel 22, and an earth removing hose 26 is connected to the discharge opening 24. The connecting section of the earth removing hose 26 is branched into a Y shape, and high-pressure air E is injected towards the downstream side of the earth removing hose 26 from the branch pipe 28.
MORIYA YOICHI
MATSUZAKI TOSHINORI
FUJII TAKESHI
NINOMIYA TADASHI
