Fabric and die design for divided conduit

Abstract

An apparatus for forming a conduit having at least one strip-shaped substrate dividing the conduit into channels. The apparatus contains an extrusion die having an exit and defining a flow direction for polymeric material forming the conduit. The extrusion die contains a first point for the introduction into the extrusion die of polymeric material forming a first polymeric layer of the conduit, a second point for the introduction into the extrusion die of polymeric material forming a second polymeric layer of the conduit, and a slot within the extrusion die having a thickness, a width, a first edge, and a second edge. The slot is configured for receipt of a strip-shaped substrate and extends in the flow direction along the extrusion die. The thickness of the slot varies along the width of the slot and the thickness of the slot is greatest at the first edge and second edge of the slot.

1 . An apparatus for forming a conduit having at least one strip-shaped substrate dividing the conduit into channels, the apparatus comprising:
 an extrusion die having an exit and defining a flow direction for polymeric material forming the conduit, the extrusion die comprising
 a first point for the introduction into the extrusion die of polymeric material forming a first polymeric layer of the conduit; 
 a second point for the introduction into the extrusion die of polymeric material forming a second polymeric layer of the conduit; and 
 a slot within the extrusion die having a thickness, a width, a first edge, and a second edge, wherein the slot configured for receipt of a strip-shaped substrate, wherein the slot extends in the flow direction along the extrusion die, wherein the thickness of the slot varies along the width of the slot, wherein the thickness of the slot is greatest at the first edge and second edge of the slot. 
   
     
     
         2 . The apparatus of  claim 1 , wherein thickness of the slot varies along the width of the slot in a step function. 
     
     
         3 . The apparatus of  claim 1 , wherein the second point is located along the flow direction downstream of the first point and upstream of the exit to the extrusion die. 
     
     
         4 . The apparatus of  claim 1 , wherein the extrusion die is configured to extrude the polymeric material into at least two opposing portions, each of the two opposing portions having a pair of distal edges. 
     
     
         5 . The apparatus of  claim 3 , wherein along the flow direction the slot has an upstream section that is positioned outside of the distal edges and a downstream section that is positioned between the two opposing portions and adjacent to the distal edges. 
     
     
         6 . The apparatus of  claim 3 , wherein at least two of the distal edges of the two opposing portions of polymeric material each comprise a joining element configured to attach the two opposing portions to form the conduit. 
     
     
         7 . The apparatus for forming a conduit as in  claim 3 , wherein each of the distal edges of one of the two portions of polymeric material comprise a joining element configured to attach the two portions to form the conduit. 
     
     
         8 . A method of using an extrusion die to extrude conduit that is divided into channels by at least one strip-shaped substrate, the method comprising the steps of:
 introducing polymeric material into the die at a first point and causing the polymeric material to move along a flow direction of the extrusion die towards an exit of the extrusion die;   forming the polymeric material into at least two opposing portions where each of the two opposing portions has a pair of distal edges;   feeding the strip-shaped substrate through the extrusion die along the flow direction, wherein the strip-shaped substrate has a thickness, a width, a first edge, and a second edge, wherein the strip-shaped substrate varies in thickness along the width of the strip-shaped substrate, wherein the thickness is greatest at first edge and the second edge forming enlarged regions;   joining the two opposing portions along the pair of distal edges of each opposing portion with the strip-shaped substrate embedded between the distal edges so as to create a first layer of the polymeric material forming the conduit; and   supplying additional polymeric material into the die at a second point and causing the additional polymeric material to form a second layer around the first layer of polymeric material forming the conduit.   
     
     
         9 . The method of  claim 8 , wherein the strip-shaped substrate varies in stiffness along the width of the strip-shaped substrate, wherein the stiffness is greatest at first edge and the second edge. 
     
     
         10 . The method of  claim 8 , wherein the enlarged regions of the strip-shaped substrate comprise the strip-shaped substrate folded onto itself and stitches. 
     
     
         11 . The method of  claim 8 , wherein the enlarged regions of the strip-shaped substrate comprise stitches. 
     
     
         12 . The method of  claim 8 , wherein the enlarged regions of the strip-shaped substrate comprise additional polymer. 
     
     
         13 . The method of  claim 8 , wherein the enlarged regions of the strip-shaped substrate comprise crimping. 
     
     
         14 . The method of  claim 8 , wherein the thicknesses of the enlarged regions of the strip-shaped substrate are at least 2 times the thickness of the strip-shaped substrate outside of the enlarged regions. 
     
     
         15 . The method of  claim 8 , wherein feeding the strip-shaped substrate through the extrusion die along the flow direction comprises feeding the strip-shaped substrate through a substrate slot. 
     
     
         16 . The method of  claim 15 , wherein the substrate slot comprises thickness, a width, a first edge, and a second edge, wherein the slot varies in thickness along the width of the slot, wherein the thickness is greatest at first edge and the second edge forming enlarged regions. 
     
     
         17 . The method of  claim 16 , wherein the thickness of the enlarged regions of the strip-shaped substrate are thicker than the slot in the width of the slot outside of the enlarged regions of the slot. 
     
     
         18 . The method of  claim 16 , wherein the as the strip-shaped substrate passes through the extrusion die along the flow direction, the enlarged regions of the strip-shaped substrate are in the enlarged regions of the slot. 
     
     
         19 . The method of using an extrusion die to extrude conduit as in  claim 8 , wherein the step of joining occurs along the flow direction at a point downstream of the first point and upstream of the second point and upstream of the exit of the extrusion die. 
     
     
         20 . The method of using an extrusion die to extrude conduit as in  claim 8 , further comprising the step of creating joining elements along at least two of the distal edges of the two opposing portions.