The excavation rod and the outer tube in the enlargement drilling rig of the reaming bit null

摘要

PROBLEM TO BE SOLVED: To provide an excavating rod which is for use in excavating a hole at the time of a soil improvement etc. by extending the bottom of the hole, wherein a reaming bit once extended can be easily contracted.;SOLUTION: The excavating rod is formed of a hollow outer pipe (2), an inner pipe (3) inserted into the outer pipe in an axially reciprocative manner, an operating rod (4) connected to the tip of the inner pipe (3), and the reaming bit (21) connected to the outer pipe (2). The reaming bit (21) is comprised of a bit joint (7), a pressing pin (5), and a pair of bit main bodies (11). The bit joint (7) is connected to the outer pipe (2) and has a recessed groove (10) at the tip thereof. The pressing pin (5) is penetrated through the bit joint (7) and has a rear end connected to the operating rod (4). The bit main bodies (11) have slots (1102) in the vicinity of the rear end, and they are rotatably connected to each other in the recessed groove (10) such that side surfaces of the respective main bodies are brought closer to each other and that ends of the respective slots (1102) are superposed on each other. Further the bit main bodies (11) are rotatably engaged with the tip of the pressing pin (5) via the slots (1102).;COPYRIGHT: (C)2004,JPO&NCIPI