Optimization of Shape of Hopper in Vertical Injection Molding Machine

Abstract

The injection molding, produces the resin products of prescribed shape by injecting the melted resin into the metal die. In this technology, the filling becomes not uniform in each part, and the difference in the density occurs when the melted resin is filled to the die. As a result, the shape of molded product differs from the shape of die because the difference in shrinkage for each part during cooling. The deformation of shape by this heat shrinkage is forecasted beforehand on the shop. The die is made in the shape which is different from a real product, and the product depends on the shape as hope is obtained finally. However, the experience and intuition of workman are needed in this adjusting process, that is, cutting down of die, and it costs an enormous cost for time and labor. As a result, the cost of injection molding product increases. The shape of hopper that supplies the pellet of resin has not been so considered up to now in the injection molding machine. In this study, the shape of hopper was optimized by the parameter design to aim to improve bridge phenomenon where the pellets are blocked in the hopper. It makes the amount of pellets supplying to the screw uniformly.