Lengthened self-centering vice for machining center four-axis machine tool

A lengthened self-centering vice for a machining center four-axis machine tool comprises a base, a first jaw, a second jaw, a lead screw supporting base, a lead screw and a pressing block, end walls are arranged at the two ends of the base in the length direction respectively, a guide rail groove is formed in the inner side of each end wall in the width direction, and each end wall is provided with a flat upper surface; the lead screw supporting seat is fixed to the middle of the base, the pressing block and the lead screw supporting seat are oppositely arranged, and the lead screw is clamped between the pressing block and the lead screw supporting seat in a pivoted mode and is perpendicular to the length direction of the base. First sliding blocks matched with the guide rail grooves in the inner side of the end wall of the base are arranged at the two ends of the first jaw, the first jaw is in threaded connection with one end of the lead screw, second sliding blocks matched with the guide rail grooves in the