Sizer for forming shaped polymeric articles and method of sizing polymeric articles

Abstract

A sizer assembly for providing a shaped polymeric article in an extrusion process comprises a sizer body having a product profile channel corresponding to the shaped polymeric article formed therethrough. The sizer body comprises a plurality of cooling liquid inlet slots forming an opening substantially around the product profile channel and a plurality of vacuum slots forming an opening substantially around the product profile channel for removing cooling liquid expelled from said cooling liquid inlet slots.

1 . A method of manufacturing a non-hollow, shaped polymeric article, comprising the steps of: 
 providing a generally flat extruded sheet of hot polymeric material having an outer surface to a sizer assembly for cooling and shaping said polymeric sheet into a non-hollow, shaped polymeric article, wherein said sizer assembly comprises: 
 a sizer body having a product profile channel corresponding to said shaped polymeric article formed therethrough, said sizer body further comprising a plurality of cooling liquid inlet slots each forming an opening substantially around said product profile channel, said cooling liquid inlet slots being in open communication with said product profile channel, and a plurality of vacuum slots each forming an opening substantially around said product profile channel for removing cooling liquid expelled from said cooling liquid inlet slots, said vacuum slots being interspersed among, and fluidly insulated from said cooling liquid inlet slots, except in said product profile channel, and being coupled to at least one vacuum source;  
   controlling at least one of vacuum and cooling liquid levels at said product profile channel such that a substantial portion of said outer surface of said sheet of polymeric material is maintained away from said sizer body as said sheet of polymeric material passes through said sizer; and    severing a length of said sheet after exiting said sizer to produce said shaped polymeric article.    
   
   
       2 . The method of  claim 1 , further comprising the step of cooling said sheet after said providing step in a quenching tank.  
   
   
       3 . The method of  claim 1 , further comprising the step of cooling said sheet after said providing step in a spray bath.  
   
   
       4 . The method of  claim 1 , wherein the product profile channel has a substantially uniform shape along its longitudinal axis and is sized less than 0.012 inches greater than a nominal thickness of said shaped polymeric article.  
   
   
       5 . The method of  claim 1 , wherein the product profile channel has a substantially uniform shape along its longitudinal axis and is sized between about 0.004-0.008 inches greater than a nominal thickness of said shaped polymeric article.  
   
   
       6 . The method of  claim 5 , wherein said method provides at least 3900 lb/hr of polymeric product.  
   
   
       7 . The method of  claim 1 , wherein said sizer body is formed from a polymeric material selected from the group consisting of heat-resistant epoxy, polyoxybenzlene, polymide, polyamide-imide, silicone, polyether-imide, polyetheretherketone, acrylics and phenolics.  
   
   
       8 . The method of  claim 1 , wherein, for a sizer approximately 4.0 inches in length, said sizer pulls at least about 800 BTUs/minute from said extruded sheet at a product speed of about 1800 inches per minute, or proportionate amounts of BTUs/minute for different sized sizers.  
   
   
       9 . The method of  claim 1 , wherein said controlling step comprises providing to and removing from said product profile channel at least 9 gallons per minute of said cooling liquid.  
   
   
       10 . The method of  claim 1 , wherein said controlling step comprises providing to and removing from said product profile channel between about 9-36 gallons per minute of said cooling liquid.  
   
   
       11 . The method of  claim 1 , wherein said cooling liquid inlet slots are generally orthogonal to the longitudinal axis of said product profile channel and said vacuum slots are interspersed among said cooling liquid inlet slots.  
   
   
       12 . The method of  claim 1 , wherein said sizer body has an top and bottom surfaces and a pair of side surfaces, wherein at least some of said vacuum slots are formed completely through said sizer body from said top surface to said bottom surface intermediate said side surfaces, and 
 wherein at least some of said cooling liquid inlet slots are formed only partially through said sizer body between said top and bottom surfaces, said sizer body further comprising a plurality of cooling liquid inlet ports formed in said sizer body for providing access to said cooling liquid inlet slots formed only partially through said sizer body.    
   
   
       13 . The method of  claim 12 , further comprising top and bottom manifold sections coupled to said sizer body, each of said top and bottom manifold sections including at least one input port coupled to said at least one source of cooling liquid and at least one vacuum port coupled to said at least one vacuum source, said manifold sections further being configured to place said at least one source of cooling liquid in communication with said cooling liquid inlet ports of said sizer body and to place said at least one vacuum source in communication with said at least some of said vacuum slots.  
   
   
       14 . A method of manufacturing a non-hollow, shaped polymeric article, comprising the steps of: 
 providing a generally flat sheet of hot polymeric material having an outer surface to a sizer assembly for cooling and shaping said polymeric sheet into a non-hollow, shaped polymeric article, said polymeric sheet being above its glass transition temperature, wherein said sizer assembly comprises: 
 a sizer body having a product profile channel disposed in a first generally horizontal direction, a plurality of longitudinally spaced cooling liquid inlet and outlet apertures disposed through said sizer body and in open communication with said product profile channel, said cooling liquid outlet apertures being interspersed among, and fluidly insulated from said cooling liquid inlet apertures, except in said product profile channel, said cooling liquid outlet apertures being coupled to at least one vacuum source;  
   controlling at least one of vacuum and cooling liquid levels at said product profile channel such that a substantial portion of said outer surface of said sheet of polymeric material is maintained away from said sizer body, thereby reducing drag on said sheet of polymeric material as it passes through said sizer; and    severing a length of said sheet after exiting said sizer to produce said shaped polymeric article.    
   
   
       15 . The method of  claim 14 , wherein said outlet apertures are alternatingly arranged with said inlet apertures.  
   
   
       16 . The method of  claim 14 , wherein a portion of said plurality of cooling liquid inlet and outlet apertures are disposed orthogonal to said generally horizontal product profile channel.  
   
   
       17 . A method of manufacturing a non-hollow, shaped polymeric article, comprising the steps of: 
 providing a generally flat extruded sheet of hot polymeric material having an outer surface to a sizer assembly for cooling and shaping said polymeric sheet into a non-hollow, shaped polymeric article, said sizer assembly comprising a sizer body having a product profile channel corresponding to said shaped polymeric article formed therethrough;    providing at least one source of cooling liquid for said sizer assembly;    providing at least one vacuum source for said sizer assembly; and    controlling the vacuum and cooling liquid levels at said product profile channel such that a substantial portion of said outer surface of said sheet of polymeric material is maintained away from said sizer body as said sheet of polymeric material passes through said sizer.    
   
   
       18 . The method of  claim 17 , wherein the product profile channel has a substantially uniform shape along its longitudinal axis and is sized less than 0.012 inches greater than a nominal thickness of said shaped polymeric article.  
   
   
       19 . The method of  claim 17 , wherein the product profile channel has a substantially uniform shape along its longitudinal axis and is sized between about 0.004-0.008 inches greater than a nominal thickness of said shaped polymeric article.  
   
   
       20 . The method of  claim 19 , wherein said controlling step comprises providing to and removing from said product profile channel at least 9 gallons per minute of said cooling liquid