Thermal field characteristics of lost mold casting
From the perspective of the forming process of the casting, the solidified casting is the process of liquid metal to the foam type, and it can be said to be the process of foam to the liquid metal; the sequential solidified casting is the process of liquid metal to the foam mold, and the process of the foam mold to the liquid metal. It's all like a heat transfer process.
The thermal field characteristics of disappearing die casting are as follows:
1) Foam gasification in the low-temperature area is not complete, and foam gasification defects are easy to occur;
2) The foam gasification in the high temperature area is complete, prone to liquid metal forming defects;
3) Type sand absorbs heat, which can make the solidification sequence chaos;
4) Absolute bottom injection heat field is inverted, and the height is more than 300mm to supplement the heat.
Therefore, the following principles should be considered in the design of the inner position of the casting system:
1) Synchronous solidification, multi-point cutting; sequential solidification, opening cutting;
2) The box casting is treated for projection to simplify the complicated situation, and the inner pouring gate and the type cavity are cut in parallel during the horizontal projection;
3) Cut in from the lower 1 / 3 during the vertical projection;
4) Step cutting when vertical placement;
5) barrel casting 45° diagonal cut;
6) uneven casting, cut from the convex;
7) Uneven wall thickness of the casting, cutting in from the thin point;
8) When the foam model is light or heavy, cut in from the heavy point;
9) In order to prevent excessive heat absorption of the internal pouring gate and smooth replenishment channel, the internal pouring gate cross-section area should be large and the length should be short.
