Before molding, assemble the core box according to the requirements, pay attention to the assembly sequence and the positioning of the foam blade. The assembly process is as shown in the figure:

The impeller is made of self hardening resin sand. After the sand, liquid resin and liquid catalyst are evenly mixed, they can be filled into the core box and hardened at room temperature. In the process of sand filling, sand filling shall be carried out from each sand filling port in order to ensure that the sand filling of the whole core box is sufficient and even. After sand filling, it shall be placed at room temperature, and the mold can be removed after the demoulding time is reached. There are many factors that affect the demoulding time, including sand mixing technology, environmental temperature and humidity. Generally speaking, when other process conditions are the same, the demoulding time is prolonged when the temperature is low, and shortened when the temperature is high [12]. As the molding time is about – 12 ℃ in winter, the mold release time is 15 hours. The core box filled with resin sand can be taken out after 15 hours, as shown in the figure.

Since the casting system of the casting is still using the original top injection process, if the lost foam foam blade is directly poured into the sand core, the possibility of porosity and carbon Carburization in the casting will be great. Based on the above considerations, the vanes foam blades are burned off by acetylene oxygen flame, so that sand cores with blade cavity can be obtained. As shown in the figure.

The cavity part of the impeller still adopts the original wood mold modeling. When the core and cavity are fully molded, zircon alcohol based coating is applied, and finally the box can be closed for pouring.