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.
Claims20
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 disposed within the runner and configured to control the flow of the molding material 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 body portion having a size and shape that cooperates with the runner forming a channel through which the molding material flows in response to the pressure differential, and
- a flow control portion integrally formed with the body portion having a size and shape that cooperates with the runner to form a flow control region for separating the channel and the cavity, wherein the pressure differential acting on the flow control portion regulates the flow of molding material into the cavity to prevent the formation of sink formation in the molded structure.
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 body portion disposed within the runner, and
- a flow control portion integrally formed with the body portion, the flow control portion disposed substantially within the gate area of the runner,
- wherein when a predetermined pressure is reached within the cavity, the pressurized molten molding material in the cavity then exerts a force on the flow control portion of the flow controller that overcomes a force exerted by a supply pressure of the molten molding material in the runner to push the flow control portion of the flow controller into a closed position against a sidewall of the gate area and sever a connection between the molten molding material in the runner and the molten molding material in the cavity.
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;
- closing a path between the runner and the cavity with a flow controller disposed within the runner once the predetermined pressure is established in the cavity, wherein the predetermined pressure within the cavity exerts a force on the flow controller that overcomes a force provided by pressurized molten molding material in the runner to move the flow controller axially within the runner from an open position to a closed position,
- wherein in the open position the flow controller in cooperation with the runner defines a path between the flow controller and sidewalls of the runner along which the molten molding material flows into the cavity.
Dependencies are inferred from the claim text.