| 摘要 |
<p>An apparatus for forming a slit in a base rock and a concrete surface, constructed simply, capable of efficiently making a deep slit having a predetermined width and a smooth inner surface, and suppressing an increase, which would otherwise be caused by the replacing of bits, in the slit-making cost. This apparatus has a plate type bit (17) fixed to the front end of a laterally swingable plate (13), a drill bit (11) fixed to the front end of a rod (9a and/or 9b) extending rotatably and slidably along at least one side of this plate, and strikers (5 and/or 12a, 12b) for striking the plate and rod simultaneously or separately. The rod is provided at its front end portion with a stabilizer for stabilizing the direction of sliding. The plate type bit consists of a plurality of detachable bit blocks.</p> |
