| 摘要 |
<p>The invention relates to a device for upholding the rectilinearity of a borehole made by means of a boring appliance comprising a percussion tool (1), a set of drill rods (3) driven in rotation and a tool actuation mechanism fastened directly to the tool (1) and arranged in an elongate outer body (2) fastened by its upper part (21) opposite the tool to the lower end (31) of the set of rods. The device according to the invention comprises a cylindrical bearing sleeve (4) surrounding over its entire length the outer body (2) of the mechanism, to which it is connected by a removable fastening means (45) and comprising on its outer face at least three helical splines (42) having an outside diameter (D1) slightly smaller than that (D) of the tool (1), winding helically at least over one complete revolution and separated by grooves (41), the width and depth of which are determined so as to ensure a total passage cross-section sufficient for the upward movement of the debris. <IMAGE></p> |
