| 摘要 |
PURPOSE:To do reliable and accurate cutting for expanding the diameter of a bore hole by cutting by use of a sub-borer body with a main borer body as a guide in the state that the forward boring by a preceding main borer body is stopped, when expanding the hole diameter deep in the bore hole. CONSTITUTION:A main borer body 1 of a striking boring machine, which is used to bore undercut holes in succession for planting anchor bolts on a concrete body or others, has a V-shaped borer blade 2 formed at its tip. Next to this borer blade 2, a stretched jaw is formed. A sub-borer body 5 for cutting the wall of a bore hole has a pair of opposed cutter plates 7 which are formed by notching the tip of the tube body into grooves 6 on its both sides. Next, a hollow fixture 11 has the sub-borer body 5's base end screwed at its lower end, and is fitted in a case 10 so as to rotate with it as one body and to be free to shift its shaft, being energized upward by a spring 12. In addition, a rotation control unit 17 has a shank 16 set at its upper end. Thus, it is possible to cut accurately the wall of a bore hole to enlarge its diameter. |
