Machining method for split type seat ring of large pump turbine

The invention relates to the technical field of pump turbine manufacturing, and discloses a large primer pump split type seat ring machining method which improves the seat ring machining precision by controlling staggered teeth between an upper ring plate and a lower ring plate of an inner seat ring and an outer seat ring and staggered teeth between fixed guide vanes. Then, the outer seat ring is subjected to comprehensive finish turning for controlling dislocation of an upper ring plate and a lower ring plate, the semi-opening and opening size of the outer circle of the inner seat ring and the inner circle of the outer seat ring should be controlled in the scratching inspection and machining process, then the inner seat ring and the outer seat ring are preassembled in a factory, and for controlling dislocation of guide blades in the period, the dislocation of the fixed guide blades should be adjusted to be minimum in the preassembling process; re-drawing the X-Y line of the inner seat ring by taking the X-Y