SRTM-Twin Injection 成形法におけるボイド流動挙動
Void Flow Behavior in SRTM-Twin Injection Method
池川直人・_田泰以・前川善一郎・北村成規
Ikegawa, Naoto / Hamada, Hiroyuki / Maekawa, Zenichiro / Kitamura, Shigeki
We have proposed a SRTM-Twin Injection Method in which resin is injected into a mold cavity from multiple gates. The void flow behavior in sequential injection was investigated by measuring the void distribution in short-shot moldings. Flow analysis using finite element method (FEM) was performed and the flow velocity and pressure distributions were related to void distribution. For the sequential injection, the resin was first injected through a pin gate, then followed by injection through a fan gate. Resin injected through the fan gate flowed outside the region filled by the resin flowing through the pin gate. Both quantity and size of the voids changed in the region where the flows through the pin and fan gates met as a result of the convergence flow from fan gate injection. A large number of voids were found in the region from the fan gate injection just behind that from the pin gate injection. According to FEM analysis, a dead water region with pressures less than zero was formed in this region. It was apparent that a high void region was formed because the movement of voids was restricted in this region.
Key words: SRTM-Twin injection method / Void flow behavior / Sequential injection / FEM analysis / Convergence flow / Dead water region