| 摘要 |
<p>The present invention relates to a borehole drilling apparatus with in-line extending wings and driving method thereof. The drilling apparatus comprises a guide device rotating while moving upwardly and downwardly in a casing to fit into aborehole, extending wings for exter?ling the diameter of adriUedhole, ar?iapUotbitinstelledatalowerportionofthe guide deviceto strike the bottom of the borehole, wherein spiral projections formed at a lower surface of tiie guide device slidably engage with guide grooves formed at a side of the extending wings to each other, and a window is formed at a side of Hie pilot bit for advancing and retracting the extending wings so that they can spread and return linearly from the center of the pilot bit</p> |
