Nozzle Configuration for Purging Flow Channel

A method of purging an injection nozzle employing an injection molding apparatus comprised of an injection molding machine, a heated manifold that receives an injection fluid material from the injection molding machine, a nozzle having a fluid flow channel having a longitudinal axis A and an upstream end that receives the injection fluid material from the heated manifold and delivers the injection fluid to a downstream end that sealably delivers the injection fluid to a gate of a cavity of a mold body, wherein the downstream end of the nozzle comprises an inner tubular member having an outer circumferential surface and an outer tubular member having an inner tubular surface, the outer tubular member forming a seal surrounding the gate,

• wherein the inner and outer tubular members are adapted to form a sealed circumferential gap between the outer circumferential surface of the inner tubular member and the inner circumferential surface of the outer tubular member, the circumferential gap circumferentially surrounding the fluid flow channel,
• wherein the inner tubular member is adapted to include one or more apertures extending radially through the inner tubular member between the fluid flow channel and the circumferential gap to enable flow of injection fluid that is injected in an upstream to downstream direction or path of flow through the fluid flow channel to flow radially from the fluid flow channel into the circumferential gap,
• wherein the circumferential gap and the fluid flow channel are adapted to communicate with each other downstream to form a common stream of flow of injection fluid material that is routed to the gate,
• the method comprising:
• controlling axial positioning of an outer surface of the valve pin relative to an inner surface of the inner tubular member during the course of an injection cycle to form a flow restriction through the nozzle channel for one or more predetermined amounts of time during the injection cycle sufficient to cause flow of fluid material to be routed through an aperture at an elevated rate of flow through the purge apertures and the gap.

In an injection molding apparatus comprised of an injection molding machine that injects an injection fluid material into a heated manifold,

• a nozzle having a fluid flow channel having a longitudinal axis and an upstream end that receives the injection fluid material from the heated manifold and delivers the injection fluid to a downstream end that sealably delivers the injection fluid to a gate of a cavity of a mold body,
• the downstream end of the nozzle comprising an inner tubular member having an outer circumferential surface and an outer tubular member having an inner tubular surface, the outer tubular member forming a seal surrounding the gate,
• the inner and outer tubular members being adapted to form a sealed circumferential gap between the outer circumferential surface of the inner tubular member and the inner circumferential surface of the outer tubular member, the circumferential gap circumferentially surrounding the fluid flow channel,
• wherein the inner tubular member has one or more apertures extending radially through the inner tubular member between the fluid flow channel and the circumferential gap to enable flow of injection fluid that is injected in an upstream to downstream path of flow through the fluid flow channel to flow radially from the fluid flow channel into the circumferential gap,
• the circumferential gap and the fluid flow channel being adapted to communicate with each other downstream to form a common stream of flow of injection fluid material that is routed to the gate,
• the apparatus comprising a controller having a program that contains instructions that control axial positioning of an outer surface of the valve pin relative to an inner surface of the inner tubular member to form a flow restriction through the nozzle channel for one or more predetermined amounts of time during the course of an injection cycle sufficient to cause flow of fluid material to be routed through an aperture at an elevated rate of flow through the purge apertures and the gap.