Combined boring cutter

The utility model belongs to the technical field of machining equipment, and relates to a combined boring cutter. The boring cutter comprises a cutter shaft and boring cutter sets evenly distributed on the cutter shaft. The cutter shaft comprises a first cutter shaft, a second cutter shaft and a third cutter shaft which are connected in sequence; the shaft diameters of the first cutter shaft, the second cutter shaft and the third cutter shaft are sequentially increased; wherein the first cutter shaft, the second cutter shaft and the third cutter shaft are respectively provided with a boring cutter fixing groove and a locking screw, a rough boring cutter is arranged on the boring cutter fixing groove of the first cutter shaft, a semi-fine boring cutter is arranged on the boring cutter fixing groove of the second cutter shaft, and a fine boring cutter is arranged on the boring cutter fixing groove of the third cutter shaft. Due to the fact that the rough boring cutter, the semi-fine boring cutter, the fine bori