Preparation of helicopter rotor counterbalance component by means of permanent-mold casting

Copper alloy was adopted to prepare helicopter rotor counterbalance component by means of permanent-mold casting. Process parameters were determined on the basis of theory calculation and computer numerical simulation. Through controlling mould temperature, pouring temperature and speed, the defects, such as gas cavity, shrinkage porosity, cold shut, can be effectively avoided. The results show that the best process parameters for smeking are as follows： pouting temperature is 1 100 ℃, pouring time is 14 s and opened mould time is 6 min. Mixture of 90% charcoal powder and 10% fluorite were selected as covering agent and 0.01% phosphorus copper acts as oxidizer. The density of rotor counterbalance component after casting in permanent-mold is 99.91% of its theory density. Mechanical properties are as follows： σb=315 MPa, σ0.2=143 MPa, δ=25%, HB=950. The mass deviation is between -5 g and ＋5 g, the curved surface distortion is less than 0.20 mm, and the largest tolerance of sectional thickness can be controlled between -0.10 mm and ＋0.10 mm.