Opening and closing manner and pile hole enlarging bottom excavation head null of the enlarging bottom excavation blade in pile hole

摘要

PURPOSE: To prevent an expanded bottom excavating edge from being stuck in a pile hole wall to prohibit rotation by inserting a rotary shock absorber between a rotary shaft fitted with the excavating edge at the lower end section and a cam shaft, and giving a difference between the rotating speed of the rotary shaft and the rotating speed of the cam shaft during the reverse rotation. ;CONSTITUTION: During a normal excavation, a rotary shaft 1 is rotated in the direction of an arrow 23, and a pile hole 22 is excavated by an excavating edge 2 while an expanded bottom excavating edge 7c is stored on the inside of a spiral blade 3. A shock absorber 12 is rotated in the same direction as the rotary shaft 1. When the rotary shaft 1 is reversely rotated in the direction of an arrow 24, the shock absorber 12 is rotated in the same direction. The excavating edge 7c and an interlocking arm 8 are slightly rotated clockwise centering on a support lever 6, and a cam plate 10 hooked on a projection 9 is slightly rotated counterclockwise together with a reinforcing tube 12a. The excavating edge 7c is slowly opened by the action of the absorber 12, and the excavating edge 7c is protruded to the outside of the spiral blade 3 to excavate an expanded bottom section 22a after the preset rotation.;COPYRIGHT: (C)1993,JPO&Japio