| 摘要 |
A drill bit for drilling a borehole in an object, the drill bit having a central longitudinal axis and comprising: a pilot section for drilling a pilot bore section of the borehole in the object; an under-reaming section in a following position with respect to the pilot section, the cutting diameter Du of the under-reaming section being larger than the cutting diameter Dp of the pilot section; a connecting shaft extending between the pilot section and the under-reaming section; and a stabilising section located between the pilot section and the under-reaming section, wherein the stabilising section fits inside the pilot bore section and is capable of laterally stabilising the drill bit relative to the object while allowing rotation of at least the pilot section relative to the object.
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