Patent ID: 7025586
Filing Date: 2006-04-11
Classification: B29C

Abstract:
1. An injection molding apparatus, comprising: a manifold having a manifold outlet; a nozzle defining a nozzle melt channel downstream from said manifold outlet, wherein said nozzle includes a nozzle body, a nozzle tip, and a seal piece, wherein said nozzle tip is removable from said nozzle body and wherein said nozzle tip defines a portion of said nozzle melt channel; a mold block defining a gate downstream from said nozzle melt channel, wherein said gate includes a gate sealing surface, wherein said seal piece engages said mold block, wherein a chamber is defined by said mold block, said nozzle tip and said seal piece and wherein said nozzle tip has sufficient surface area in said chamber to maintain melt in said chamber in a substantially molten state; and a valve pin movable into and out of said gate having a valve pin sealing surface engageable with said gate sealing surface; said valve pin having a first guidance and alignment structure upstream from said valve pin sealing surface including a first guide surface and a first alignment surface, wherein said first guide surface has a cross-sectional diameter that decreases gradually in a downstream direction, and wherein said first alignment surface is generally cylindrical and said first guide surface is positioned immediately downstream from said first alignment surface; and said mold block having a second guidance and alignment structure upstream from said gate sealing surface including a second guide surface and a second alignment surface, wherein said second guide surface has a diameter that decreases gradually in a downstream direction, and wherein said second alignment surface is generally cylindrical and said second guide surface is positioned immediately upstream from said second alignment surface, wherein, during movement of said valve pin towards said gate, said second guide surface engages said first guide surface, said first alignment surface slides into alignment with said second alignment surface, said first alignment surface slides along said second alignment surface and said valve pin sealing surface is positioned in alignment with said gate sealing surface.