| 摘要 |
A monolithic long lasting rotary drill bit for drilling a hole into a geological formation having at least one hardened rod which has a length of at least three times its diameter composed of hard material such as tungsten carbide that is cast into a relatively soft steel matrix material to make a rotary drill bit that compensates for wear on the bottom of the drill bit and that also compensates for lateral wear of the drill bit using passive, self-actuating mechanisms, triggered by bit wear to drill relatively constant diameter holes.
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