Grade seal system and method of manufacturing same

Abstract

In at least one embodiment, a grade ring system includes an annular shell formed of a plastic composition and defining an annular cavity. An in-situ formed core situated in the annular cavity comprises a plurality of polymer beads expandable by heating medium which, when expanded, substantially fill the annular cavity. A method for forming a grade ring is also disclosed.

What is claimed is: 
     
         1 . A grade ring system comprising:
 an annular shell formed of a plastic composition and defining an annular cavity;   an in-situ formed core situated in the annular cavity comprising a plurality of polymer particles expandable by a heating medium which, when expanded, substantially fill the annular cavity.   
     
     
         2 . The grade ring system of  claim 1  wherein the plastic composition is a thermoplastic polymer composition. 
     
     
         3 . The grade ring system of  claim 1  wherein the plastic polymer composition comprises a polypropylene composition. 
     
     
         4 . The grade ring system of  claim 1  wherein the expandable polymer particles comprise a polyolefin particles. 
     
     
         5 . The grade ring system of  claim 1  wherein the expandable polymer particles comprise expanded polypropylene particles. 
     
     
         6 . The grade ring system of  claim 1  wherein the expandable polymer particles comprise homopolymer beads. 
     
     
         7 . The grade ring system of  claim 1  wherein the expandable polymer particle comprises a steam-expandable polymer bead. 
     
     
         8 . The grade ring system of  claim 1  wherein the heating medium comprises super-heated steam. 
     
     
         9 . The grade ring system of  claim 1  wherein the elongated annular shell ranges in height from 0.75 inches to 6 inches. 
     
     
         10 . The grade ring system of  claim 1  wherein the diameter of the annular shell ranges from 1 inch to 10 inches. 
     
     
         11 . The grade ring system of  claim 1  wherein the annular ring has opposed, spaced-apart first and second surfaces, the first surface includes a protrusion and the second surface includes a recessed embossment. 
     
     
         12 . The grade ring system of  claim 1  wherein the annular ring has opposed, spaced-apart first and second surfaces, the first and second surfaces are substantially parallel and situated at an angle relative to the outer wall of the elongated annular ring. 
     
     
         13 . The grade ring system of  claim 1 , wherein the annular ring has a varying height to define wedge shape in side view. 
     
     
         14 . The grade ring system of  claim 13  wherein the wedge-shaped annular ring has opposed, spaced-apart first and second surfaces, the first and second surfaces being situated relative to each other at an angle ranging from 0.5 degrees to 10 degrees to allow alignment with angles of a street surface. 
     
     
         15 . A grade ring system comprising:
 a first annular ring comprising a first annular tubular shell formed of a first plastic composition and defining a first cavity, the first annular tubular shell including a first surface having a protrusion and a second surface being opposed to and spaced apart from the first surface, the second surface having an embossment, the first cavity being substantially filled with an in-situ expanded polymer bead core; and   a second annular ring comprising a second annular tubular shell formed of a second plastic composition and defining a second cavity, the second annular tubular shell including a first surface having a protrusion and a second surface being opposed to and spaced apart from the first surface, the second surface having an embossment, the second cavity being substantially filled with an in-situ expanded polymer bead core, wherein the protrusion of the second annular ring being capable of engaging the embossment of the first annular ring when the first annular ring is vertically stacked up on the second annular ring.   
     
     
         16 . The system of  claim 15 , further comprising a base grade ring having a base annular tubular shell formed of a third plastic and defining a base grade ring cavity, the base annular tubular shell including a base surface having a protrusion, the base cavity being substantially filled with an in-situ expanded polymer bead core, wherein the base grade ring is capable of engaging the embossment of the second annular ring when the second annular ring and the base annular ring are vertically stacked adjacent to one another. 
     
     
         17 . The system of  claim 15 , further comprising a cap ring having a cap annular tubular shell formed of a one or more layers of plastic and defining a cap ring cavity, the cap annular tubular shell including a cap surface having a embossment, the cap ring cavity being substantially filled with an in-situ expanded polymer bead core, wherein the cap ring is capable of engaging the protrusion of the first annular ring when the first annular ring and cap annular ring are vertically stacked adjacent to one another. 
     
     
         18 . The system of  claim 15 , wherein the first surface of either the first or second annular ring is disposed at an angle relative to the second surface of the same annular ring, the angle ranging from 0.5 degrees to 10 degrees. 
     
     
         19 . The system of  claim 15  further comprising a seal disposed between the embossment of the first annular ring and the protrusion of the second annular ring. 
     
     
         20 . The system of  claim 15 , wherein a radius of the first annular ring equals or exceeds the radius of the second annular ring, when the first annular ring is disposed above the second annular ring. 
     
     
         21 . The system of  claim 15 , wherein at least one annular ring has a thickness ranging from 0.75 inches to 6 inches. 
     
     
         22 . A method for manufacturing a grade ring system component comprising the steps of:
 (a) extruding a plastic preform in a mold cavity in the shape of an elongated member to form a tubular plastic shell having a longitudinal axis;   (b) forming the tubular plastic shell to form at least one annular ring shell in a closed mold having a closing axis substantially transverse to the longitudinal axis, the annular ring shell having a wall defining a cavity;   (c) forming at least one fill port and a plurality of heating ports in the wall of the annular ring shell;   (d) filling the cavity through the fill port with expandable polymer particles;   (e) injecting a hot, at least partially vaporized, heating medium into the heating ports to expand the expandable polymer particles so as to substantially fill the cavity of the annular ring shell to form the component;   (f) constraining the annular ring shell in the closed mold to limit expansion caused by the heated, expanding polymer particles until the component has cooled sufficiently to limit further expansion; and   (g) releasing the component from the mold cavity.   
     
     
         22 . The method of  claim 21 , further comprising the steps of:
 (h) forming at least two components; and   (i) stacking at least two components to form the grade ring system.   
     
     
         23 . The method of  claim 22 , further comprising the steps of:
 (j) forming at least one wedge-shaped component wherein the component has a first surface disposed at an angle relative to an opposed second surface, the angle ranging from 0.5 degrees to 10 degrees;   (k) situating the first wedge-shaped component on or within the grade ring system; and   (l) adjusting the grade ring system height or angle relative to a street surface when rotating the first wedge-shaped component such that the angle of the wedge-shaped component cooperates with an angle of the street surface to form a substantially smooth transition between the grade ring systems and the street.   
     
     
         24 . The method of  claim 23 , further comprising:
 (m) situating a second wedge-shaped component in an inverted position on the first wedge-shaped component;   (n) rotating the second wedge-shaped component relative to the first wedge-shaped component to achieve the grade angle or height of the street surface.   
     
     
         25 . The method of  claim 21 , wherein the heating ports include steam injection needles are spaced apart having a spacing ranging from D 1  to D 2 , where 
       
         
           
             
               
                 
                   
                     
                       D 
                       1 
                     
                     = 
                     
                       
                         1 
                         
                           ( 
                           
                             ABD 
                             × 
                             0.56 
                           
                           ) 
                         
                       
                       - 
                       0.5 
                     
                   
                 
               
               
                 
                   
                     
                       D 
                       2 
                     
                     = 
                     
                       
                         1 
                         
                           ( 
                           
                             ABD 
                             × 
                             5 
                           
                           ) 
                         
                       
                       + 
                       3 
                     
                   
                 
               
             
           
         
         and ABD is the average apparent bulk density of the expandable polymer particles.