| 摘要 |
PURPOSE: A variable drilling bit and a pile construction apparatus using the same are provided to construct a pile by drilling through the inside of the pile and to excavate a hole greater than the outer diameter of a drilling bit. CONSTITUTION: A variable drilling bit comprises a main body(30), a fixed bit(40), an injection nozzle, and a pair of variable bits(60). The main body, one side of which is connected to a drilling rod, is rotated by receiving torque from the drilling rod. The fixed bit is installed in the bottom part of the main body. The injection nozzle is installed in the part of the main body in which the fixed bit is installed and injects high-pressure air, high-pressure water, or cement milk to the outer side of the main body. The variable bits are installed on both sides of the main body, above the fixed bit, via a variable shaft and protrude from or come into the radius of rotation of the fixed bit according to the movement of the variable shaft.
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