Abstract: A valve-gate mechanism for use with gas-assisted plastic injection molding systems. A moveable pin mechanism is positioned in a bushing or machine nozzle to regulate the injection of plastic material into a mold cavity. The pin mechanism has an outer pin member and an inner pin member. Movement of the inner pin member relative to the outer pin member allows gas to be injected into the plastic in the mold cavity. A spring member, such as a Belleville washer, biases the inner pin member to a closed position relative to the outer pin member. Gas pressure from the gas source overcomes the force of the spring member allowing gas to enter into the mold cavity.

Abstract: An injection mold apparatus having two halves, a core portion and a cavity portion. One or more gas injection devices, such as porous metal devices, are located in either of the two portions of the mold. Once a charge of hot melted plastic is injected into the mold cavity, gas is injected through gas injection devices forcing the hot plastic against the opposite mold half and into any recesses and grooves. Gas seals are formed by the plastic to prevent gas in the mold cavity from reaching the exterior surface of the molded part during shrinkage of the plastic. The centers of mass of the plastic at rib intersections are optimally positioned to eliminate sink marks on the external finished surfaces of the molded parts.

Abstract: A gas injection pin mechanism for introducing pressurized gas into a mold cavity or melt stream. A stationary pin member is positioned directly in a bore or opening in a mold member without a sleeve member. The pin member is an elongated body member with a first end facing a mold cavity and a first gas passageway through the pin member connected to a second passageway that is traverse to the first gas passageway. The second gas passageway has an opening on an exterior lateral surface of the pin member and gas through the second gas passageway is introduced into the cavity in annular space between the pin member and the mold opening.