| 摘要 |
PURPOSE:To reduce the length of a driller main body by arranging so that a lengthy shaft for fitting a cutter edge can be slidably inserted into a fine-feed drive shaft. CONSTITUTION:A shaft 2 is constituted with a lengthy bar-like body, and a cutter edge fitting section 21 is formed on one end and a handle fitting section 22 to rotate the shaft 2 is formed on the other end. The shaft 2 is fed in until a cutter edge (not shown in the figure) is brought into contact with the suface of a main pipe, shafts 2 and 3 are fixed 5, and the main pipe is bored. After the boring is completed, the fixation of shafts 2 and 3 is released and the shaft 2 is withdrawn. The main body can be made small-sized since it can be constituted with a stroke width by the thickness of a drilled object. |
