Melt Channel Geometries for an Injection Molding System

Abstract

An injection molding system is disclosed that utilizes a melt channel wherein at least a portion of the melt channel has a noncircular cross-section for balancing shear in a melt stream of moldable material that flows therethrough. The noncircular cross-section of the melt channel portion may be, for e.g., capsule-shaped, extended egg-shaped, oval, teardrop-shaped, or peanut-shaped. A flow splitter is also disclosed that is positioned offset from a central axis of an upstream melt channel to protrude between inlets of respective downstream melt channels, where the upstream melt channel splits into the downstream melt channels, to thereby create a narrower inlet into one of the downstream melt channels and a wider inlet into the other of the downstream melt channels.

What is claimed is: 
     
         1 . An injection molding system comprising;
 a hot runner component that includes at least one melt channel for conducting a melt stream of moldable material therethrough wherein at least a portion of the melt channel has a noncircular cross-section.   
     
     
         2 . The injection molding system of  claim 1 , wherein the hot runner component is selected from the group consisting of a hot runner manifold, a hot runner nozzle, a sprue fitting, and a sprue bar. 
     
     
         3 . The injection molding system of  claim 1 , wherein the noncircular cross-section of the melt channel is selected from the group consisting of a capsule-shaped cross-section, an extended egg-shaped cross-section, and an oval cross-section. 
     
     
         4 . The injection molding system of  claim 3 , wherein the noncircular cross-section includes semicircular end portions joined by a rectangular-shaped midsection. 
     
     
         5 . The injection molding system of  claim 4 , wherein a width of the rectangular-shaped midsection is equal to two times a radius of the semicircular end portions. 
     
     
         6 . The injection molding system of  claim 1 , wherein a perimeter of the noncircular cross-section is greater than a perimeter of a circular cross-section of a comparable cross-sectional area. 
     
     
         7 . The injection molding system of  claim 1 , wherein more shear is imparted to the melt passing through the melt channel having the noncircular cross-section than would be imparted to a melt passing through a melt channel having a circular cross-section of a comparable cross-sectional area. 
     
     
         8 . The injection molding system of  claim 1 , wherein the noncircular cross-section of the melt channel is selected from the group consisting of a teardrop-shaped cross-section and a peanut-shaped cross-section. 
     
     
         9 . The injection molding system of  claim 1 , wherein a portion of the melt having more shear is directed through a narrower portion of the melt channel. 
     
     
         10 . The injection molding system of  claim 9 , wherein a portion of the melt having less shear is directed through a wider portion of the melt channel. 
     
     
         11 . The injection molding system of  claim 2 , wherein the hot runner component is a hot runner manifold and the hot runner manifold includes at least one melt channel having a circular cross-section. 
     
     
         12 . An injection molding system comprising;
 a hot runner manifold that includes at least one melt channel for conducting a melt stream of moldable material therethrough wherein at least a portion of the melt channel has a noncircular cross-section for balancing shear in the melt stream, wherein the noncircular cross-section of the at least a portion of the melt channel is selected from the group consisting of a capsule-shaped cross-section, an extended egg-shaped cross-section, an oval cross-section, a teardrop-shaped cross-section, and a peanut-shaped cross-section.   
     
     
         13 . The injection molding system of  claim 12 , wherein the at least one melt channel includes at least one upstream melt channel that splits into at least two downstream melt channels. 
     
     
         14 . The injection molding system of  claim 13 , wherein the at least one upstream melt channel has the noncircular cross-section. 
     
     
         15 . The injection molding system of  claim 14 , wherein each of the at least two downstream melt channels has the same noncircular cross-section as the at least one upstream melt channel.