Drilling rig null of the enlarging cartridge head amount in the hole for the pile with enlarged base by welding ground drill

摘要

PURPOSE:To excavate a pit for a bottom expanding pile within a wide range by small power by forming a ditch to the ground by a cutter for excavating the ditch installed to an expanding blade, a diameter of which can be extended and shrunk, and excavating a bottom expanding section by a cutter for excavating the pit. CONSTITUTION:Expanding blades 13, 13 having cutter arrays 36 are mounted in clearances among a plurality of case members 22 arranged on a circumference at intervals, and can be moved among first positions having small diameters and second locations having extended diameters, and scrapers 16 interlocked with the blade 13, 13 are set up. A ditch is formed to the ground by cutters 42 for excavating the ditch fitted to the preceding rotating expanding blades 13, 13, and the ground is excavated by cutters 41 for excavating a pit. The expanding blades 13, 13 are extruded further to the outside, the clearance angles of the cutters 41 for excavating the pit are increased, and a bottom expanding section is excavated while ensuring biting to the ground. Accordingly, even when a rake angle is reduced, the pit for a bottom expanding pile can be excavated by small power.