The invention discloses a rotary screw
drill tool used in fields of
petroleum drilling and the like and solves the problem about crushing efficiency of hard rocks in extradeep wells. The technical scheme includes that a
bypass valve shell, a
fall prevention joint, a motor shell, a universal shaft shell, an outer shell, a bearing shell, an outer
cam shell, a bottom
piston shell and a lower shell are sequentially connected through screw threads; an upper shaft and a lower shaft are connected through a spline, and eight spline pins are evenly and circumferentially distributed between the upper shaft and the lower shaft; a roller holder is fixed on the outer
cam shell through three bolts which are circumferentially and evenly distributed, a
cam is circumferentially fixed on the cam
bushing through three evenly distributed bolts, a roller is mounted on a roller holder, the cam
bushing is connected to the lower shaft in a threaded manner, and a lower
split ring is clamped in the lower shaft through a serrated trough and is fixed through a lower
retaining ring. By the arrangement, the lower shaft of the screw
drill tool is enabled to generate soft axial
impact with a certain frequency and stable in size, efficiency of
rock breaking of a
drill is improved, mechanical drilling rate is increased, and drilling cost is thereby lowered.