Tooling concepts for reducing sink and improving as-molded cosmetics and drawings
AssigneeApple Inc.
InventorsMichael B. Wittenberg, Miguel C. Christophy, Daniel W. Jarvis, Shayan Malek
Life of this patent
Estimating the term…
Abstract
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.
Claims13
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.
An injection molding apparatus, comprising:
- a runner configured to guide a flow of pressurized molten molding material into a cavity, the runner comprising a gate area disposed at an end of the runner that intersects the cavity;
- and
- a pressure actuated flow controller, comprising:
- a slider that passes through the gate area of the runner and defines an opening through which the flow of pressurized molten material passes into the cavity when the slider is in an open position, the slider comprising a first end configured to receive a pneumatic force from pressurized air vented out of the cavity as the pressurized molten molding material fills the cavity;
- wherein when a predetermined pressure is reached within the cavity, the pneumatic force transitions the slider to a closed position, causing the opening to shift away from the gate area so that a connection between the molten molding material in the runner and the molten molding material in the cavity is severed.
A method for forming an injection molded part, the method comprising:
- injecting pressurized molten molding material into a cavity of an injection mold through a runner until a predetermined pressure is reached in the cavity;
- and
- closing a path between the runner and the cavity with a slider by shifting an opening defined by the slider away from a gate area of the runner leading into the cavity once the predetermined pressure is established in the cavity,
- wherein the predetermined pressure within the cavity pressurizes air exiting the cavity, the pressurized air being directed towards one end of the slider to exert a force upon the slider that moves the slider from an open position to a closed position, and
- wherein in the open position the opening defined by the slider in cooperation with the runner defines a path along which the molten molding material flows into the cavity.
Dependencies are inferred from the claim text.