Tool and method for centering SCR (Selective Catalytic Reduction) part of diesel engine on gantry mill

The invention relates to a tool and method for centering a diesel engine SCR part on a gantry miller, the tool comprises a blind rivet, a basic part, an end cover, a moving rod, a limiting device, a dial indicator device and a spring, the blind rivet is installed on the basic part, and the blind rivet is tensioned through a machine tool clamping jaw; the movable rod is installed on the basic part, the end cover is fixed to the bottom end of the basic part, the limiting device is fixed to the basic part, and the dial indicator device is installed and fixed to the first position or the second position of the limiting device during accurate measurement; the method for setting the center comprises the steps that 1, the tool for setting the center is installed on a main shaft of a machine tool power accessory, 2, the front side face of the basic part is made to be parallel to the X axis of a machine tool, and the angle of the main shaft is recorded, 3, the centers of the large end and the small end of the SCR part