Analyzing Of Injection Molding Steel Net Reinforced HDPE Ball Valve By CAE Software

As the HDPE pipe been widely used in the urban water supply and drainage, building water supply and drainage, city gas supply, agricultural irrigation and petrochemical fields, the demand of HDPE ball valve is increasing. In order to meet the requirement of installing and using, the thick wall and the steel-plastic composite way are often used to increase the strength and reduce creep. However, there are two problems involved in producing the steel-plastic composite reinforced HDPE ball valve: first, there is a big shrinkage in thick wall HDPE ball valve; second, if the steel skeletons are poorly designed, the deformation of steel skeleton likely to happen during the injection process. With the widely application of CAE technology, computer aided design has played an important role in product exploitation and design. It not only saves cost and time in exploitation, but also provides some reliable scientific basis.The subject, analyzed the influence of shrinkage in different molding parameter by using injection molding software Moldflow. Then, based on the coupling method between the Moldflow and ANSYS CAE, it simulated the deformation of ball valve during injection and optimized the steel's diameter and structure.The results showed that:(1) There is an obvious relationship between the shrinkage of thick-walled ball valve and the injection molding conditions. During the holding pressure time, melt temperature and mold temperature are the main factors of shrinkage. The longer of holding pressure time is, the more obvious supplied-shrinkage effect shown. This made the shrinkage of product reduced. For core, melt temperature is the main influence factor. It can reduce shrinkage by keeping relatively low melt temperature. This demonstrated that heat shrinkage is the main effect for core. Mold temperature is the main impact factor for the surface layer shrinkage. Similarly, it can reduce shrinkage by keeping relatively low mold temperature. The optimized molding parameters by orthogonal experimental are: melt temperature 230℃, mold temperature 50℃, holding pressure 90%, holding pressure time 1500s.(2) According to the deformation analysis on ANSYS, the deformation of steel-net-insert is mainly related to diameter and structure of steel net. Comparing with the 3mm-diameter wire, the deformation of 5mm-diameter wire was reduced by 60%. But with the wire the further increase of diameter, the trend of deformation decreases slows down. Considered to the structure of steel net, vertical arrangement of 8 wires is an ideal structure; At this time, the largest deformation is 0.566mm. This structure can bring it into accord with using requirement of ball valve.