Turnover folding device suitable for automatic production line of underpants

The turnover folding device comprises a mounting frame, a first threaded rod is rotationally connected to the inner wall of the top of the mounting frame, a transmission mechanism is arranged on one side of the first threaded rod, a threaded sleeve is connected to the outer wall of the first threaded rod in a threaded mode, and a transverse plate is fixedly connected to the bottom end of the threaded sleeve. Underpants are placed on the tops of a folding plate and a placement table, an output shaft of a second motor rotates to drive a threaded block to move so as to drive a movable rod to rotate, the movable rod rotates to enable the folding plate to turn over and fold the underpants on the placement table and the folding plate, and an output shaft of a first motor rotates to drive a worm to rotate so as to enable a movable block to move; the movable block moves to drive a first rack to move so as to drive a gear to rotate, the gear rotates to drive a first threaded rod to rotate so as to drive a threaded sle