箱型射出成形品における成形過程を考慮した変形解析

Abstract

Injection moulding is an established production technology for the forming of thermo-plastics resins. Recently, it has been applied to fibre reinforced thermoplastics (FRTP), and developments in this field are continuing. However, this method has still many problems, such as brittle weakness along weld-line, warping, incomplete filling and so on, especially for the fibre reinforced plastics dealt with here.In this paper, a simulation was carried out for a box product with thin wall by considering the velocity distribution resulting from the velocity difference in flow between the upper and lower skin layers. A box was unfolded onto one plane to convert a three-dimensional structure to a two-dimensional model. After the flow analysis, the fibre orientation analysis was carried out by assuming that fibres rotate according to the velocity gradient tensor obtained for each element by the flow analysis. Finally, an attempt was made to established the deformation analysis for determining the out-of-plane deflections based on the results of the fibre orientation analysis.In the experiments, the shape of flow front, fibre orientation and out-of-plane deflection were determined by the observation of short shot mouldings, soft X-ray photographs and moire-image interrence fringes, respectively. The numerical results were compared with the experimental observation. They showed a good agreement.