| 摘要 |
PURPOSE: A rotor for a screw compressor is provided to improve an air compression ratio by minimizing heat expansion due to the heat that is generated during high rate of revolution of the rotor, and a method for manufacturing the rotor for a screw compressor is provided to reduce material cost and processing cost by casting the rotor to the dimension that is close to the desirable shape, thereby minimizing mechanical processing. CONSTITUTION: The rotor for a screw compressor is a spheroidal graphite cast iron based casting material comprising 2.0 to 3.0 wt.% of C, 1.5 to 2.5 wt.% of Si, 0.1 to 1.0 wt.% of Mn, 0.045 wt.% or less of P, 0.020 wt.% or less of S, 34 to 36 wt.% of Ni, 0.025 to 0.045 wt.% of Mg, 1.0 to 4.0 wt.% of Mo, 1.0 to 5.0 wt.% of V and a balance of Fe. The method for manufacturing the rotor for a screw compressor comprises the processes of manufacturing molten metal by heating an ingot comprising 2.0 to 3.0 wt.% of C, 1.5 to 2.5 wt.% of Si, 0.1 to 1.0 wt.% of Mn, 0.045 wt.% or less of P, 0.020 wt.% or less of S, 34 to 36 wt.% of Ni, 0.025 to 0.045 wt.% of Mg, 1.0 to 4.0 wt.% of Mo, 1.0 to 5.0 wt.% of V and a balance of Fe; and casting a rotor for a screw compressor by simultaneously compensating a contraction portion of the molten metal from a feeder head sleeve (16) containing Al2O3 powder and rapidly cooling the molten metal with copper balls (12) filled in an outer cast (14) installed outside the shell cast (10) as supplying the molten metal into a shell cast (10) corresponding to the shape of a product through a feeding hole (18) having a shape so that the molten metal is fed from the upper side and entered into the cast from the lower side.
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