Composite railroad tie and method of manufacture

Abstract

An improved mold and method of manufacture for an improved railroad tie or other structural member. The improved railroad tie or structural member being fabricated using an injection molding process with various thermoplastic resins and fillers. The improved mold used has a cooling cavity which helps cool the structural member while still in the mold. The improved insert allows an automated molding system to be used for greater production rates.

1 . An insert for a structural member comprising: 
 an elongated body with a first end, a second end, a first side, a second side, a top edge and a bottom edge; and    a foot located on the bottom edge, the foot comprising a planar surface facing away from the body.    
   
   
       2 . The insert of  claim 1  further comprising one or more landings located on the body; each landing having a flat area, a shoulder extending perpendicular from the flat area.  
   
   
       3 . The insert of  claim 1  further comprising two or more nested arches, the arches secured to one another.  
   
   
       4 . The insert of  claim 3  further comprising one or more cross links secured between the arches.  
   
   
       5 . The insert as claimed in  claim 1  wherein the insert is constructed from a ferrous material.  
   
   
       6 . The insert as claimed in  claim 1  wherein the insert is a casting.  
   
   
       7 . The insert as claimed in  claim 1  wherein each side comprises a first landing located near the first end and a second landing located near the second end.  
   
   
       8 . An insert for a structural member comprising: 
 an elongated body with a first end, a second end, a first side, a second side, a top edge, a bottom edge and a plurality of nested arches.    
   
   
       9 . The insert of  claim 8 , wherein the arches are attached to one another.  
   
   
       10 . The insert of  claim 8  further comprising a plurality of cross links between the arches.  
   
   
       11 . An insert for a structural member comprising: 
 an elongated body with a first end, a second end, a first side, a second side, a top edge and a bottom edge; and    one or more landings located on the body; each landing having a flat area, a shoulder extending perpendicular from the flat area.    
   
   
       12 . An injection molding machine comprising: 
 a mold with a first half and a second half, each half having a mold cavity located in a mold side of the half, a vault side located opposite the mold side, a top, a bottom, a first end, a second end, and a flange;    a pair of opposing vaults each having a front side, a backside, an opening in the front side, the opening having an interior surface and being sized to accommodate the vault side of the mold halves;    a pair of cooling cavities each defined by the vault side of one of the mold halves and the interior surface of the vault, each cooling cavity having a nozzle in fluid communication with a cooling fluid supply and a drain hole.    
   
   
       13 . An injection molding machine as claimed in  claim 12 , wherein the cooling cavity is partially filled with cooling fluid.  
   
   
       14 . An injection molding machine as claimed in  claim 12 , wherein the first half is a mirror image of second half.  
   
   
       15 . A process for making structural member comprising: 
 closing a mold;    injecting a thermoplastic into the mold;    forming a structural member in the mold;    cooling the structural member in the mold;    removing the structural member from the mold while partially molten; and    further cooling the structural member.    
   
   
       16 . The process of  claim 15 , further comprising placing an insert in the mold prior to closing it.  
   
   
       17 . The process of  claim 16  wherein the insert is comprised of: 
 an elongated body with a first end, a second end, a first side, a second side, a top edge and a bottom edge;    a foot located on the bottom edge, the foot comprising a planar surface facing away from the body; and    one or more landings located on the body; each landing comprising a flat area and a shoulder extending perpendicular from the flat area.    
   
   
       18 . The process of  claim 16  wherein the insert is constructed from a ferrous material.  
   
   
       19 . The process of  claim 16  wherein the insert is a casting.  
   
   
       20 . The process of  claim 17  wherein each side comprises a first landing located near the first end and a second landing located near the second end.  
   
   
       21 . The process of  claim 17 , wherein the insert is placed by a robot which engages the one or more landings with an electro magnet.  
   
   
       22 . The process of  claim 15 , wherein the mold is comprising: 
 a mold with a first half and a second half, each half having a mold cavity located in a mold side of the half, a vault side located opposite the mold side, a top, a bottom, a first end, a second end, and a flange; a pair of opposing vaults each having a front side, a backside, an opening in the front side, the opening having an interior surface and being sized to accommodate the vault side of the mold halves; and    a pair of cooling cavities each defined by the vault side of one of the mold halves and the interior surface of the vault, each cooling cavity having a nozzle in fluid communication with a cooling fluid supply and a drain hole.    
   
   
       23 . The process of  claim 22 , wherein the cooling in the mold is accomplished in part by the steps comprising pumping a cooling fluid from the cooling fluid supply, through the nozzle and into the cooling cavity and removing the cooling fluid from the cooling cavity through the drain hole.  
   
   
       24 . The process of  claim 23 , wherein the cooling cavity is partially filled with cooling fluid.  
   
   
       25 . The process of  claim 22 , wherein the first half is a mirror image of second half.  
   
   
       26 . The process of  claim 15 , wherein the structural member is cooled in a liquid bath after being removed from the mold.  
   
   
       27 . The process of  claim 26 , wherein the liquid bath is a spray bath.  
   
   
       28 . The process of  claim 15 , wherein the structural member is cooled in air after being removed from the mold.