Solution to casting defects of shrinkage cavity in cylinder block water pump shell

Due to the thin wall around the hot spot, it is impossible to establish an effective feeding channel. Due to the structure of the cylinder block, it is impossible to open the inner runner here. Therefore, the final consideration is to adjust the parting plan, with one end of the water pump shell facing down, and rely on the large height difference of the casting and the 150 mm high gating cup to establish the internal molten iron pre-solidification pressure; Although the other end is relatively high, because the wall thickness is relatively uniform and there is no particularly large hot spot, rapid solidification by rapid casting will not cause problems; At the same time, the numerical simulation software was used again for simulation analysis. The final measures were as follows: increase the sectional area of each component of the gating system by 14.8%~15.1%, increase the pouring speed to 12~14 s, and reduce the top oxide from 2.1% to 1.8%.

After adjustment according to the above measures, more than 500 castings have been trial-produced and produced. The casting defects of the air shrinkage hole at the water pump shell position have been reduced from more than 60% to 0. At the same time, the other end of the adjustment parting upward has no defects, and the expected effect has been achieved.