Excavation direction adjustment easy sand stratum excavation manner and excavation ring bit

摘要

PURPOSE:To improve work efficiency and facilitate the work by obliquely tilting the tip closing plate of a ring bit excavating a sand layer, providing a sediment intake port on the periphery, performing straight excavation at full rotation, and correcting the direction with the oscillating rotation in the specific angle range. CONSTITUTION:The tilt angle of the tip closing plate 3 of a ring bit 1 is set to 45 deg., and an intake port 4 opened by about 1/8 of the area of the closing plate 3 is provided on the tip side periphery. The ring bit 1 is fully rotated to straightly excavate a sand layer. When the excavating direction is to be changed, the ring bit 1 is located in the phase that the intake port 4 is located on the direction side to be corrected, and the oscillating rotation motion is applied in the angle range + or -45 deg. centering the phase to correct the excavating direction. The ring bit 1 is returned horizontally after the direction correction, and straight excavation is performed at full rotation. The advance direction can be gradually corrected during excavation, the work is facilitated, and workability can be improved.