Through the simulation analysis of two investment casting process schemes, it is determined that the theoretical scheme of proportional solidification is applicable to the production of the rod-shaped titanium alloy casting. According to the situation in the simulation, the gating system is optimized (see Figure 1): (1) Remove the anti-deformation rib. Deformable reinforcement increases the generation of hot spots, introduces shrinkage defects and affects the distribution of stress field. (2) Casting φ 10 mm hole. Due to the limited feeding capacity of titanium liquid, φ The wall thickness of the 10 mm hole is relatively uniform, and the uniform wall thickness is not easy to form a feeding channel, which may reduce the risk of shrinkage defects at this location during casting. (3) Change of the position of the sprue. Place the side inner sprue in the middle of the transverse sprue to facilitate mold filling at the same time; The top ingate is set at the large wall-thickness ratio of the rod opening. Because the wall-thickness ratio here varies greatly, the ingate is set at this position to act as the gating riser, which can eliminate the shrinkage defects at this position.
Figure 2, Figure 3 and Figure 4 are the simulation results of the optimized investment casting process plan. It can be seen from Figure 2 that the titanium liquid is filled according to the flow direction of the large hole, and the solidification is carried out according to the principle of balanced solidification. The part at the end of the rod is solidified first. It can be seen from Figure 2 and Figure 4 that after solidification of investment castings, hot spots are formed at the intersection of the opening and large wall thickness ratio and the inner runner, and shrinkage defects are produced. However, the defects are located at the runner, effectively avoiding the location of the large wall thickness ratio, and the stress difference at this location is less than 90 MPa. The stress distribution of the overall investment castings is relatively uniform.
