Tooling concepts for reducing sink and improving as-molded cosmetics and drawings

摘要

The described embodiments relate generally to improvements to injection molding equipment. More specifically, concepts for reducing sink and improving cosmetics of portions of injection molded parts in close proximity to gate areas of an injection mold are disclosed. A cold runner system is described in which molding material disposed in a mold cavity is separated from excess molding material in the runner system shortly after the mold is filled at a predetermined packing pressure.

主权项

1. An injection mold for forming a molded structure, comprising:
a runner configured to guide a flow of molding material into a cavity at a gate area in accordance with a forward pressure exerted on the molding material; and a flow controller passing through the gate area of the runner proximate the cavity and configured to transition between an open position in which the molding material can pass into the cavity and a closed position in which the molding material cannot pass into the cavity in accordance with a pressure differential between the forward pressure exerted on the molding material and a back pressure generated by an amount of molding material in the cavity, the flow controller comprising:
a slider defining an opening aligned with the gate area of the runner when the slider is in the open position, the slider comprising a distal end configured to receive a force generated by pressurized air exiting the cavity by way of a number of pressure vents, wherein once the back pressure within the cavity reaches a predetermined threshold the force acting upon the distal end of the slider shifts the slider in a direction substantially perpendicular to the flow of molding material to reach a closed position in which the opening is no longer aligned with the gate area.