1. Casting valve body model with shrinkage cavity and calculation parameters

There are two shrinkage cavities in the valve body casting, and the shape of shrinkage cavity I is irregular. In order to facilitate modeling, the irregular shape of shrinkage cavity I is simplified as a semi ellipsoid, in which the length diameter is 6.8mm and the included angle with the center line of the valve hole is 30 °, the short diameter is 3.2mm, and the shrinkage cavity II is simplified as a U-shaped, 3.6mm long, 5.7mm wide and 3mm deep. The model is shown in Figure 1.

The mesh generation method and calculation parameter setting are the same as the ideal valve body, which will not be described here.

2. Strength analysis

Fig. 2 is a cloud chart of the distribution of stress and safety factor of the valve body with defects after improvement when the pressure is 30MPa. The maximum stress of the valve body is distributed near the edge of the shrinkage cavity near the outlet side, with a value of 162.17mpa. The existence of shrinkage cavity weakens the strength of the valve body, resulting in obvious stress concentration. The distribution of fatigue safety factor is the same as the stress distribution, with a minimum value of 1.5711, meeting the strength requirements. Therefore, for the improved valve body, when the pressure is 30MPa, the valve body can still meet the strength requirements.