초록 ▼

An injection molding apparatus includes a nozzle body, a valve pin, a nozzle tip, a seal piece, and a mold gate insert. The nozzle body has a melt channel. The valve pin is at least partially positioned in the melt channel. The valve pin has a first guidance and alignment structure thereon. The noz

An injection molding apparatus includes a nozzle body, a valve pin, a nozzle tip, a seal piece, and a mold gate insert. The nozzle body has a melt channel. The valve pin is at least partially positioned in the melt channel. The valve pin has a first guidance and alignment structure thereon. The nozzle tip is connected to the nozzle body. The seal piece is connected to the nozzle body. The mold gate insert defines a gate and is in contact with the seal piece. The nozzle tip has a higher thermal conductivity than the nozzle body. The seal piece has a lower thermal conductivity than the nozzle body. The mold gate insert has a higher thermal conductivity than the seal piece. The mold gate insert includes a second guidance and alignment structure thereon that contacts the first guidance and alignment structure before the valve pin contacts the gate.

대표청구항 ▼

What is claimed is: 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

What is claimed is: 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. 2. An injection molding apparatus as claimed in claim 1, wherein said first guidance and alignment structure includes a relief channel that extends along at least a portion of said first guide surface and at least a portion of said first alignment surface. 3. An injection molding apparatus as claimed in claim 1, wherein said second guidance and alignment structure includes a relief channel that extends along at least a portion of said second guide surface and at least a portion of said second alignment surface. 4. An injection molding apparatus as claimed in claim 1, wherein: said valve pin has a third guidance and alignment structure including a third guide surface and a third alignment surface upstream from said first guidance and alignment structure, wherein said third guide surface has a cross-sectional diameter that decreases gradually in a downstream direction, and wherein said third alignment surface is generally cylindrical and said third guide surface is positioned immediately downstream from said third alignment surface and is upstream from said first alignment surface; and said nozzle tip has a fourth guidance and alignment structure including a fourth guide surface and a fourth alignment surface, wherein said fourth guide surface has a diameter that decreases gradually in a downstream direction, and wherein said fourth alignment surface is generally cylindrical and said fourth guide surface is positioned immediately upstream from said fourth alignment surface and said fourth alignment surface is upstream from said second guide surface, wherein, during movement of said valve pin towards said gate, said fourth guide surface engages said third guide surface, said third alignment surface slides into alignment with said fourth alignment surface, said third alignment surface slides along said fourth alignment surface and said valve pin is generally positioned in alignment with said gate. 5. An injection molding apparatus as claimed in claim 1, wherein said nozzle tip is retained in said nozzle body by said seal piece. 6. An injection molding apparatus as claimed in claim 1, wherein said nozzle tip is connected to said nozzle body by a threaded connection. 7. An injection molding apparatus as claimed in claim 1, wherein said seal piece is a first seal piece, and said nozzle further includes a second seal piece disposed between said first seal piece and said nozzle tip such that said first seal piece, said second seal piece, said nozzle body and said nozzle tip define an insulating airspace. 8. An injection molding apparatus as claimed in claim 1, wherein said first guidance and alignment structure is removably connected to said valve pin. 9. An injection molding apparatus as claimed in claim 1, wherein said second guidance and alignment structure is removably connected to said mold block. 10. An injection molding apparatus as claimed in claim 1, wherein said second guidance and alignment structure is positioned in a gate insert that contains said gate and is removably connected to said mold block. 11. An injection molding apparatus as claimed in claim 1, wherein said first guide surface curves gradually into said first alignment surface. 12. An injection molding apparatus as claimed in claim 1, wherein said second guide surface curves gradually into said second alignment surface. 13. An injection molding apparatus as claimed in claim 1, wherein said gate and said second guidance and alignment structure are defined in a gate insert that is removably connected to said nozzle body. 14. An injection molding apparatus as claimed in claim 1, wherein said manifold has an inlet and a plurality of said manifold outlets, and has a plurality of runners downstream from said inlet and upstream from said plurality of manifold outlets, and wherein said injection molding apparatus includes a plurality of said nozzles, wherein each nozzle is downstream from one of said plurality of manifold outlets, wherein said mold block defines a plurality of gates, and wherein said mold block, said nozzle tip and said seal piece on each of said plurality of nozzles define said chamber, and wherein each of said plurality of nozzles includes said valve pin. 15. An injection molding apparatus comprising: a nozzle body having a melt channel, said nozzle body being made of a first material; a valve pin at least partially positioned in the melt channel, said valve pin having a first guidance and alignment structure thereon; a nozzle tip in thermal contact with the nozzle body; a seal piece in thermal contact with the nozzle tip and the nozzle body; and a mold gate insert having a gate, said mold gate insert being in contact with the seal piece; wherein the nozzle tip is made of a second material having a higher thermal conductivity than said first material, wherein the seal piece is made of a third material having a lower thermal conductivity than said first material, wherein the mold gate insert is made of a fourth material having a higher thermal conductivity than said third material, and wherein the mold gate insert includes a second guidance and alignment structure that contacts the first guidance and alignment structure before the valve pin contacts the gate during movement of said valve pin towards said gate. 16. An injection molding apparatus as claimed in claim 15, wherein the nozzle tip has a nozzle tip guidance and alignment structure that contacts the first guidance and alignment during movement of the valve pin towards the gate orifice. 17. An injection molding apparatus as claimed in claim 15, wherein the nozzle tip is threaded to the nozzle body. 18. An injection molding apparatus as claimed in claim 15, wherein the seal piece is threaded to the nozzle body. 19. An injection molding apparatus as claimed in claim 15, wherein the seal piece retains the nozzle tip. 20. An injection molding apparatus as claimed in claim 15, wherein the first guidance and alignment structure of the valve pin is removably connected to said valve pin. 21. An injection molding apparatus as claimed in claim 15, wherein said gate insert is removably connected to said nozzle body. 22. An injection molding apparatus as claimed in claim 1, wherein the thermal conductivity of said nozzle tip is higher than the thermal conductivity of said nozzle body, and wherein the thermal conductivity of said seal piece is lower than the thermal conductivity of said nozzle body. 23. An injection molding apparatus comprising: a nozzle body having a melt channel; a valve pin including a first guidance and alignment structure, a second guidance and alignment structure downstream from said first guidance and alignment structure and a first sealing surface downstream from said second guidance and alignment structure; a nozzle tip in thermal contact with the nozzle body and including a third guidance and alignment structure; a seal piece in thermal contact with the nozzle tip and the nozzle body; and a mold plate defining a gate, wherein said mold plate includes a fourth guidance and alignment structure and a second sealing surface downstream from said fourth guidance and alignment structure; wherein said first guidance and alignment structure of said valve pin is capable of interacting with said third guidance and alignment structure of said nozzle tip and said second guidance and alignment structure of said valve pin is capable of interacting with said fourth guidance and alignment structure of said mold plate, wherein said first sealing surface contacts said second sealing surface without contacting any other surfaces of said nozzle tip or said mold plate. 24. The injection molding apparatus of claim 23, wherein said mold plate includes a gate insert defining said gate, said fourth guidance and alignment structure and said sealing surface. 25. The injection molding apparatus of claim 24, wherein said gate insert contacts said seal piece. 26. The injection molding apparatus of claim 24, wherein said gate insert is in thermal contact with said nozzle body. 27. The injection molding apparatus of claim 24, wherein said seal piece is a first material and said gate insert is a second material having a higher thermal conductivity than said first material. 28. The injection molding apparatus of claim 23, wherein said seal piece is a first material, said nozzle body is a second material having a thermal conductivity that is higher than said second material, and said nozzle tip is a third material having a higher thermal conductivity than said second material. 29. The injection molding apparatus of claim 1, wherein one of said seal piece and said nozzle tip is removably connected to said nozzle body. 30. The injection molding apparatus of claim 1, wherein said mold block includes a gate insert defining said gate. 31. The injection molding apparatus of claim 30, wherein said chamber is defined by said mold block, said gate insert, said nozzle tip and said seal piece. 32. The injection molding apparatus of claim 15, wherein said nozzle tip is in guiding contact with said valve pin during movement of said valve pin towards said gate. 33. 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 including a gate insert that defines a gate downstream from said nozzle melt channel and includes a gate sealing surface, wherein said seal piece and said gate insert engage said mold block within a common bore in said mold block; and a valve pin having a valve pin sealing surface engageable with said gate sealing surface. 34. The injection molding apparatus of claim 33, wherein said valve pin has 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 has 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. 35. An injection molding apparatus as claimed in claim 34, wherein: said valve pin has a third guidance and alignment structure upstream from said first guidance and alignment structure including a third guide surface and a third alignment surface, wherein said third guide surface has a cross-sectional diameter that decreases gradually in a downstream direction, and wherein said third alignment surface is generally cylindrical and said third guide surface is positioned immediately downstream from said third alignment surface and is upstream from said first alignment surface; and said nozzle tip has a fourth guidance and alignment structure including a fourth guide surface and a fourth alignment surface, wherein said fourth guide surface has a diameter that decreases gradually in a downstream direction, and wherein said fourth alignment surface is generally cylindrical and said fourth guide surface is positioned immediately upstream from said fourth alignment surface and said fourth alignment surface is upstream from said second guide surface, wherein, during movement of said valve pin towards said gate, said fourth guide surface engages said third guide surface, said third alignment surface slides into alignment with said fourth alignment surface, said third alignment surface slides along said fourth alignment surface and said valve pin is generally positioned in alignment with said gate.