Abstract:

Single bend screw drill tool is one of the important tools for implementation of horizontal directional drilling in coal mine. This paper analyses the stress and deformation of the single bend screw drill tool through the beam-column theory, and elucidates the relationships among changing dip force and changing azimuth force with bit pressure, the length of first beam, curvature radius of the borehole, bend angle, tool face angle and so on. According to the analysis of torque, axial load and centrifugal force, it is helpful to understand the working state of screw drill tool; and it is important for correct use, maintenance and successful directional drilling.

Key words: Directional drilling, Screw drill tool, Beam-column, Changing dip force, Changing azimuth force