| 摘要 |
The present invention relates to an underground drilling machine. The underground drilling machine comprises: a hammer casing where a central hole is formed in the center to insert a main hammer to be rotated, multiple auxiliary holes are formed around the central hole in a circumference direction in order to insert an auxiliary hammer to be rotated, and hanging projections are formed in a circumference direction from the lower part of the outer circumference to the inside; a fixating bit which is combined with the bottom end of the main hammer; an expanding bit which is combined with the bottom end of the auxiliary hammer and whose radius of rotation expands when the auxiliary hammer rotates on the central axis; a rotary unit of a hammer, which makes the auxiliary hammer rotate on the central axis of the auxiliary hammer and revolve along the center of the main hammer when the main hammer rotates; and a sleeve which is welded on the bottom end of the inner circumference of a buried pipe that is inserted onto the outer side of the hammer casing, and interferes with the hanging projection when the hammer casing is lowered. Therefore, when removing the hammer and the bit after burying the buried pipe while drilling the ground at a fixed depth, only the buried pipe can have a buried structure in the drilled area, thereby solving the problem of being filled with soil again and improving work efficiency by facilitating the follow-up process of installing various electric wires or facilities. |
