Tank car construction using longitudinal curved segments

Abstract

A cylindrical shell for a tank of a railway tank car is made using roll-forming technology and straight longitudinal weld seams. The cylindrical shell has a longitudinal axis and a uniform cross-sectional shape in a plane normal to the longitudinal axis. The cylindrical shell includes a plurality of elongated segments welded together along weld seams extending parallel to the longitudinal axis of the cylindrical shell. Each elongated segment forms a portion of the cross-sectional shape of the shell and is formed by passing a flat piece of metal plate stock material through a roll-forming machine configured to progressively bend the piece of stock material. In one embodiment, exactly three identical elongated segments, each defining an arc of 120 degrees, are welded together along adjacent longitudinal edges to form a cylindrical shell having a circular cross-section.

What is claimed is: 
     
         1 . A railway tank car comprising a cylindrical shell having a longitudinal axis and a uniform cross-sectional shape in a plane normal to the longitudinal axis, wherein the cylindrical shell includes a plurality of elongated segments welded together along weld seams extending parallel to the longitudinal axis of the cylindrical shell and each elongated segment forms a portion of the uniform cross-sectional shape, and wherein each of the plurality of elongated segments is formed by passing a flat piece of metal plate stock material through a roll-forming machine configured to progressively bend the piece of stock material. 
     
     
         2 . The railway tank car according to  claim 1 , wherein the plurality of elongated segments are identical to one another. 
     
     
         3 . The railway tank car according to  claim 1 , wherein the uniform cross-sectional shape is circular, and each elongated segment forms an arc in the circular cross-sectional shape. 
     
     
         4 . The railway tank car according to  claim 3 , wherein the cylindrical shell includes exactly three of the elongated segments. 
     
     
         5 . The railway tank car according to  claim 4 , wherein the arc formed by each of the plurality of elongated segments is 120 degrees. 
     
     
         6 . A cylindrical shell of a tank for a railway tank car, the cylindrical shell having a longitudinal axis and a uniform cross-sectional shape in a plane normal to the longitudinal axis, wherein the cylindrical shell includes a plurality of elongated segments welded together along weld seams extending parallel to the longitudinal axis of the cylindrical shell and each elongated segment forms a portion of the uniform cross-sectional shape, and wherein each of the plurality of elongated segments is formed by passing a flat piece of metal plate stock material through a roll-forming machine configured to progressively bend the piece of stock material. 
     
     
         7 . The cylindrical shell according to  claim 6 , wherein the plurality of elongated segments are identical to one another. 
     
     
         8 . The cylindrical shell according to  claim 6 , wherein the uniform cross-sectional shape is circular, and each elongated segment forms an arc in the circular cross-sectional shape. 
     
     
         9 . The cylindrical shell according to  claim 8 , wherein the cylindrical shell includes exactly three of the elongated segments. 
     
     
         10 . The cylindrical shell according to  claim 9 , wherein the arc formed by each of the plurality of elongated segments is 120 degrees. 
     
     
         11 . A method of manufacturing a cylindrical shell of a railway tank car comprising the steps of:
 providing a plurality of elongated flat pieces of metal plate material;   passing each of the plurality of pieces longitudinally through a roll-forming machine configured to progressively bend the piece of stock material into an elongated segment having a curved cross-sectional configuration, whereby a plurality of the arc-shaped elongated segments are formed, each elongated segment having a pair of longitudinal edges; and   welding the plurality of elongated segments together along their respective longitudinal edges to make the cylindrical shell.   
     
     
         12 . The method according to  claim 11 , wherein the plurality of elongated segments are identical to one another. 
     
     
         13 . The method according to  claim 11 , wherein the cylindrical shell has a circular cross-sectional shape, and each elongated segment forms an arc in the circular cross-sectional shape. 
     
     
         14 . The method according to  claim 13 , wherein exactly three of the elongated segments are welded together to make the cylindrical shell. 
     
     
         15 . The method according to  claim 14 , wherein the arc formed by each of the plurality of elongated segments is 120 degrees.