Downhole power drilling tool for sidetracking well

A universal shaft assembly of a screw drill comprises a connecting rod and movable hinges at the two ends, the movable hinge at the lower end and a water cap are connected into a whole, the two ends of the connecting rod are inserted into movable hinge counter bores respectively, outer crowned teeth are arranged on the peripheries of the two ends of the connecting rod respectively, the outer crowned teeth are meshed with inner crowned teeth on the inner circumferential walls of the movable hinge counter bores, and the outer crowned teeth are meshed with inner crowned teeth on the inner circumferential walls of the movable hinge counter bores. The centers of the two ends of the connecting rod abut against the centers of the ball seats through bearing balls. Shoulders at the two ends of the connecting rod abut against inner angle bearings respectively, the outer spherical surfaces of the inner angle bearings are supported on outer angle bearings, and the inner ends of the outer angle bearings abut against inner