Generally, the commonly used forms ofrisers are waist, cylindrical and spherical. Under the condition of the same volume, the modulus of the cylindrical riser is relatively large and the solidification time is long, that is, the feeding efficiency of the cylindrical riser is relatively high, so the cylindrical open riser is used for feeding.
The lost foamuses one riser to feed two castings at the same time. The volume of lost foam casting to be fed is 4751720mm3 and the heat dissipation surface of lost foam casting is 589899mm2. The modulus of lost foam casting is the ratio of the volume to be fed to the heat dissipation area, so the modulus of lost foam casting is MC = 0.8cm.
In the solidification process, with the feeding of lost foam castings, the riser volume should be gradually reduced and the modulus should be reduced. In order to make the riser feeding better, the riser should be solidified later than the lost foam casting, that is, the initialization modulus MR of the riser is greater than the modulus MC of the casting, that is:
In the formula, f is the safety factor increased by making the riser solidify later than the lost foam casting. Generally, f = 1.1 ~ 1.2. F is 1.1. According to the formula:
According to the characteristics and volume of the feeding position and the initial modulus of the required riser, the feeding riser of lost foam castings is designed as a cylindrical riser with HR of 90mm and Dr of 60mm.