Movable joint thread synchronous tapping method and movable joint thread synchronous tapping device

The invention discloses a movable joint thread synchronous tapping method and a movable joint thread synchronous tapping device and belongs to the technical field of movable joint machining. A tapping screw rod provided with a screw tap at the front end is arranged in a hollow main shaft of a numerical control lathe; the screw tap is driven by a power mechanism to rotate and is identical with a workpiece clamped by a chuck in rotating direction; when the rotating speed of the screw tap is higher than that of the workpiece, the screw tap rotates for tapping opposite to the forward direction of the workpiece; and when the rotating speed of the screw tap is lower than that of the workpiece, the screw tap rotates for returning opposite to the reverse direction of the workpiece. The movable joint thread synchronous tapping method and the movable joint thread synchronous tapping device realize the effect that after a movable joint is clamped and positioned at one time on the numerical control lathe, an inner circle at the front end of the movable joint, an end surface and threads at the rear end are simultaneously machined so as to greatly improve the machining efficiency, improve the machining precision, save the equipment investment and reduce the energy consumption.