Method and apparatus for injection molding articles

Abstract

An injection molding system having an improved valve gate arrangement that provides molded articles with improved vestige and or surface quality.

What is claimed is:  
     
         1 . An apparatus for injection molding at least one article, said apparatus having at least one mold cavity and a supply of flowable material communicated to said mold cavity through at least one injection nozzle, comprising: 
 a movable valve member having a predetermined cross-sectional area to selectably start and stop the communication of said flowable material through a nozzle gate in each said nozzle, and;    a vestige adjacent said nozzle gate protruding from a surface of said article, wherein said vestige has a cross-sectional area greater than said cross-sectional area of said valve member.    
     
     
         2 . The apparatus in accordance with  claim 1  wherein said article is a preform.  
     
     
         3 . The apparatus in accordance with  claim 2  wherein said preform is made from PET.  
     
     
         4 . The apparatus in accordance with  claim 1  wherein said mold cavity is formed between a cavity plate and a mold core.  
     
     
         5 . The apparatus in accordance with  claim 4  wherein said mold core is selectably movable to an open and closed position.  
     
     
         6 . The apparatus in accordance with  claim 4  wherein said nozzle gate is located in said cavity plate.  
     
     
         7 . The apparatus in accordance with  claim 4  wherein said nozzle gate is located in an insert located in said cavity plate.  
     
     
         8 . The apparatus in accordance with  claim 7  wherein said insert is replaceable.  
     
     
         9 . The apparatus in accordance with  claim 1  wherein said injection nozzle comprises: 
 an elongated nozzle bushing having a melt passageway therein, said nozzle bushing placed in a cavity of a cavity plate in alignment with said mold cavity,  
 a nozzle tip affixed to said nozzle bushing for the communication of a flowable material from said nozzle bushing to said mold cavity,  
 a heater in thermal communication with said injection nozzle.  
 
     
     
         10 . The apparatus in accordance with  claim 1  wherein said valve member is cylindrical.  
     
     
         11 . The apparatus in accordance with  claim 1  wherein said valve member has a reduced diameter portion in sealing communication with said nozzle gate.  
     
     
         12 . The apparatus in accordance with  claim 1  wherein said valve member has at least one longitudinal recess on the surface of said valve member to allow for the communication of said flowable material.  
     
     
         13 . An apparatus for injection molding at least one article comprising: 
 a source of flowable material in fluid communication with at least one injection nozzle, said injection nozzle having an outlet in alignment with a mold cavity for the formation of said article therein;    a movable valve member for selectably starting and stopping the communication of said flowable material through said outlet;    said article having a vestige adjacent said valve member, wherein the cross-sectional area of said valve member is less than said vestige.    
     
     
         14 . The apparatus in accordance with  claim 13  wherein said article is a preform.  
     
     
         15 . The apparatus in accordance with  claim 14  wherein said preform is made from PET.  
     
     
         16 . The apparatus in accordance with  claim 13  wherein said mold cavity is formed between a cavity plate and a mold core.  
     
     
         17 . The apparatus in accordance with  claim 16  wherein said mold core is selectably movable to an open and closed position.  
     
     
         18 . The apparatus in accordance with  claim 16  wherein said nozzle gate is located in said cavity plate.  
     
     
         19 . The apparatus in accordance with  claim 16  wherein said nozzle gate is located in an insert located in said cavity plate.  
     
     
         20 . The apparatus in accordance with  claim 19  wherein said insert is replaceable.  
     
     
         21 . The apparatus in accordance with  claim 13  wherein said injection nozzle comprises: 
 an elongated nozzle bushing having a melt passageway therein, said nozzle bushing placed in a cavity of a cavity plate in alignment with said mold cavity,  
 a nozzle tip affixed to said nozzle bushing for the communication of a flowable material from said nozzle bushing to said mold cavity,  
 a heater in thermal communication with said injection nozzle.  
 
     
     
         22 . The apparatus in accordance with  claim 13  wherein said valve member is cylindrical.  
     
     
         23 . The apparatus in accordance with  claim 13  wherein said valve member has a reduced diameter portion in sealing communication with said nozzle gate.  
     
     
         24 . The apparatus in accordance with  claim 13  wherein said valve member has at least one longitudinal recess on the surface of said valve member.  
     
     
         25 . In an injection molding system, a manifold subsystem for the communication of a flowable material, comprising: 
 a manifold structure having at least one melt passageway in fluid communication with at least one injection nozzle;    a cavity plate in spaced-apart alignment with a mold core for the formation of a cavity therebetween, said nozzle being in fluid communication with said cavity through a nozzle gate for the formation of a molded article therein,    an insert having a passageway therethrough in fluid communication between said nozzle and said nozzle gate,    a movable valve member for selectably stopping and starting the communication of said flowable material to said cavity, and    said nozzle gate adjacent a vestige protruding from said molded article, wherein said vestige cross-sectional area adjacent said valve member is larger than the cross-sectional area of said valve member that contacts said molded article.    
     
     
         26 . The apparatus in accordance with  claim 25  wherein said molded article is a preform.  
     
     
         27 . The apparatus in accordance with  claim 26  wherein said preform is made from PET.  
     
     
         28 . The apparatus in accordance with  claim 25  wherein said mold core is selectably movable to an open and closed position.  
     
     
         29 . The apparatus in accordance with  claim 25  wherein said nozzle gate is located in said cavity plate.  
     
     
         30 . The apparatus in accordance with  claim 25  wherein said nozzle gate is located in an insert located in said cavity plate.  
     
     
         31 . The apparatus in accordance with  claim 30  wherein said insert is replaceable.  
     
     
         32 . The apparatus in accordance with  claim 25  wherein said injection nozzle comprises: 
 an elongated nozzle bushing having a melt passageway therein, said nozzle bushing placed in a cavity of a cavity plate in alignment with said mold cavity,  
 a nozzle tip affixed to said nozzle bushing for the communication of said flowable material from said nozzle bushing to said mold cavity,  
 a heater in thermal communication with said injection nozzle.  
 
     
     
         33 . The apparatus in accordance with  claim 25  wherein said valve member is cylindrical.  
     
     
         34 . The apparatus in accordance with  claim 25  wherein said valve member has a reduced diameter portion in sealing communication with said nozzle gate.  
     
     
         35 . The apparatus in accordance with  claim 25  wherein said valve member has at least one longitudinal recess on the surface of said valve member to allow for the communication of said flowable material.  
     
     
         36 . In an injection molding system for the formation of a molded article, a gate insert comprising: 
 a body having a passageway formed therein, said passageway located between an injection nozzle assembly and a mold cavity for the communication of a fluid to said mold cavity,    an orifice portion of said passageway in sealing communication with a movable valve member such that when said valve member is adjacent said orifice portion the flow of said fluid to said cavity is prevented,    a raised portion protruding from said molded article in thermal communication with said gate insert and said valve member thereby cooling the outer periphery of said raised portion faster than the interior of said raised portion.