Riser-free casting method for stator main shaft of wind turbine

The invention relates to a riser-free casting method for a stator main shaft of a wind turbine, which aims to provide a riser-free casting method with low manufacture cost, high production efficiency and good product property for a stator main shaft of a wind turbine. The method comprises the following steps of: A. manufacturing a mould, wherein a water split type, vertical-casting and three-stage step-shaped opening type casting system is adopted for the mould, the transversal casting channel is in a surrounding type, the inner casting opening is in a multiple-point dispersion flat type, the top is provided with a gas exhaust riser, and chill iron is arranged on the large thick cross section; B. controlling the chemical components of the molten iron, wherein the components comprise 3.80-3.90% of C, 2.1-2.2% of Si, no more than 0.30% of Mn, no more than 0.015% of S, no more than 0.05% of P, 0.04-0.06% of Mg, and 0.01-0.04% of Re; C. adopting a high-temperature overheating and low-temperature casting method, wherein the overheating temperature of the molten steel is 1450-1460 DEG C, and the casting temperature is controlled at 1320+/-10 DEG C, and carrying out instantaneous inoculation during casting; D. carrying out nodularizing treatment on the molten water by adopting a Mg-TRe yittrium-base heavy rare earth composite nodularizer, and carrying out multi-stage inoculation; and E. cooling: adopting a slow cooling method, wherein the shake-out time is determined to 60 hours, and the shake-out temperature of the casting surface is not higher than 400 DEG C.