Abstract:
A method for forming a cylindrical body utilizing a continuous weld is provided. The method includes feeding a source material including a first edge and a second edge from a coil and offsetting at least one of the first edge and the second edge. The method further includes spiraling the material to form a cylinder, welding the first edge and the second edge together forming a continuous weld, and cutting the cylinder to a selected length. To fabricate a jacket, a longitudinal cut is made in the cylindrical body, at least one cutout is cut, and the continuous weld is an outer fillet weld.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This application claims the benefit of U.S. provisional application No. 60/258,395 filed Dec. 27, 2000 and is a divisional of U.S. application Ser. No. 10/034,154, filed Dec. 27, 2001, now U.S. Pat. No. 6,717,093 which is hereby incorporated by reference. 

   BACKGROUND OF THE INVENTION 
   This invention relates generally to railroad cars and, more particularly, to jackets for tank cars and roofs for hopper cars. 
   Rail car fabrication is a labor intensive process and generally requires numerous weld operations. While at least some welding processes are now automated, e.g., for welding sheets, even automated welding processes require proper set-up of numerous sheets of steel and experienced operators to ensure high quality welds are made by the automated equipment. 
   Components for rail cars such as tank cars and hopper cars are fabricated by welding steel plates together into a desired configuration. For example, some tank cars require insulation on an outer surface of the tank, and an outer jacket is utilized to contain and protect the insulation. The outer jacket typically is fabricated by welding numerous steel plates together. Although the actual welding is performed by automated machinery, the set-up operations are labor intensive. In addition, experienced welders typically must closely supervise the automated weld process to ensure proper welding. 
   Similarly, for a hopper car, the hopper car roof is formed by welding a plurality of steel plates together. The sides are then welded to a car cylindrical body, and the roof is located over the sides and welded thereto. Again, the extensive welding required to form the hopper car roof is time consuming and labor intensive. 
   BRIEF DESCRIPTION OF THE INVENTION 
   Methods and systems for fabricating spiral welded cylinders that are particularly well suited for rail car components are described herein. In an exemplary embodiment, a method for fabricating a cylindrical body utilizing a continuous weld includes the steps of feeding a source material including a first edge and a second edge from a coil and straightening at least a portion of the source material. The first edge is offset and the material is fed into a spiral mill so that the material forms a cylinder, or a cylindrical body. The material second edge is positioned adjacent the first edge, and a continuous weld at the interface maintains the material in the formed cylinder. The weld is sometimes referred to herein as a spiral weld because the continuous weld extends along the cylinder in a spiral path. 
   To fabricate a jacket for a tank car, for example, a longitudinal cut is made in the cylindrical body so that the cut ends can be spread apart. Additionally, a plurality of jackets can be fabricated from a single cylindrical body by making a plurality of longitudinal cuts. The body, or jacket, is then positioned over and secured to the tank. To fabricate a roof for a hopper car, two longitudinal cuts are made to the cylindrical body at select location to provide an arc shaped roof. The roof is then secured to side walls of the hopper car. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a side plan view of a system for forming a cylindrical body using a continuous weld. 
       FIG. 2  is a top plan view of the system shown in FIG.  1 . 
       FIG. 3  is a perspective plan view of one embodiment of a spiral welder. 
       FIG. 4  is a perspective top view of a jacket for a tank car. 
       FIG. 5  is a front view of the jacket shown in FIG.  4 . 
       FIG. 6  is a perspective view of a spiral welded roof for a hopper car. 
       FIG. 7  is an end view of the roof shown in FIG.  6 . 
       FIG. 8  is an exploded detailed view of the spiral welded roof and hopper car shown in FIGS.  6  and  7 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  is a side plan view and  FIG. 2  is a top plan view of a system  10  for forming a cylindrical body using a continuous weld. System  10  includes a peeler  12  in series configuration with a coil  14  of a metal source material  16 . Peeler  12  prevents coil  14  from freely unwrapping. System  10  further includes a first drive roller  18  in series configuration with peeler  12 , a straightener  20  in series configuration with roller  18 , and a splicing assembly  22  also in series configuration with roller  18 . System  10  further includes an offsetter  24  in series configuration with roller  18 , and a second drive roller  26  in series configuration with offsetter  24 . Coil  14 , peeler  12 , roller  18 , straightener  20 , splicing assembly  22 , offsetter  24 , and roller  26  are mounted on a pivoting mounting surface  28 . System  10  further includes a spiral welder  30  in series configuration with roller  26 , a cylinder fixture  32  in series configuration with welder  30 , and a cutter  34  in series configuration with fixture  32 . Material  16  includes a first edge  36  and a second edge  38 . 
   During operation of system  10 , material  16  is fed through peeler  12  to first drive roller  18  and first drive roller  18  is engaged such that first drive roller  18  can drive or push material  16 . First drive roller  18  pushes material  16  through straightener  20  and splicing assembly  22  to offsetter  24 . Offsetter  24  offsets at least one of first edge  36  and second edge  38  before material  16  is pushed to second drive roller  26 . Second drive roller  26  is engaged such that second drive roller  26  can drive or push material  16  to spiral welder  30  which welds material  16  into a cylinder  40  and cylinder fixture  32  supports and transports cylinder  40 . Cutter  34  cuts cylinder  40  when a length (not shown) of cylinder  40  is at a desired length. 
   In an exemplary embodiment, cutter  34  is a plasma torch, such as, for example, a Hypertherm Max100 system, available from Hypertherm Inc. of Hanover N.H. In an alternative embodiment, cutter  34  is a metal cutting laser. It is contemplated that the benefits of the invention accrue to systems utilizing all methods of cutting metal, including metal cutting bandsaws and metal cutoff wheels. 
   In an exemplary embodiment, offsetter  24  utilizes a joggle joint die to offset at least one of first edge  36  and second edge  38 . When material  16  reaches second drive roller  26 , first drive roller  18  is disengaged and not utilized to push material  16  further. Additionally, straightener  20  is typically utilized only at the beginning and the ending portions (not shown) of coil  14 . Accordingly, straightener  20  can be disengaged. In an exemplary embodiment, straightener  20  is a three over two straightening table that utilizes three rollers above material  16  and two rollers below material  16  and second drive roller  26  pushes material  16  to spiral welder  30  at a helix angle (not shown) from 90° to a longitudinal axis  42  of cylinder  40 . The helix angle is between approximately 6.5° and approximately 13.3° to provide a diameter (not shown) of between approximately 96″ and approximately 132″ for cylinder  40  utilizing material  16  having a width (not shown) between approximately 48″ and approximately 64″. The helix angle is adjusted by pivoting surface  28  along an arc  44 . 
     FIG. 3  is a perspective plan view of one embodiment of spiral welder  30  including an automatic submerged arc welder  50  including a weld head  52 , a flux dispenser  54 , a flux supply  56 , and a movable mount  58 . Spiral welder  30  further includes a seam tracker  60  in series configuration with arc welder  50 . Seam tracker  60  is electrically connected to a controller  62  that controls arc welder  50 . Spiral welder further includes a vacuum  64  in series configuration with arc welder  50  opposite seam tracker  60 . Vacuum  64  includes a vacuum nozzle  66  to vacuum loose flux (not shown) from weld  68 . A scraper  70  to scrap hardened flux (not shown) from weld  68  is in series configuration with vacuum nozzle  66 . Spiral welder  30  further includes monitor  72  in series configuration with seam tracker  60 . Monitor  72  monitors a width (not shown) of a gap  74  between first edge  36  and second edge  38 . In addition, monitor  72  controls the helix angle such that the width of gap  74  is substantially uniform. Also, in an exemplary embodiment, a person, i.e., an operator, watches the width of gap  74  and manually actuates a gap control for swing arm  44  and makes active adjustments to the welding process. 
   Spiral welder  30  includes a spiral mill (not shown) that material  16  passes through. Because of the helix angle and the spiral mill, material  16  is wrapped in a helix and first edge  36  is positioned next to second edge  38  as best seen in FIG.  2 . In an exemplary embodiment, the spiral mill is a spiral mill from the PRD Company of Hayward Calif. and automatic submerged arc welder  50  is an automatic submerged arc welder available from the Lincoln Electric Company of Cleveland Ohio. Seam tracker  60  is a Cyclomatic seam tracker from ITW Welding Automation of Appleton Wis. Vacuum  64  is a vacuum from the American Vacuum Company of Skokie Ill. 
   During operation of spiral welder  30 , a portion  76  of gap  74  rotates beneath monitor  72  which monitors the width of portion  76  and transmits a signal to a motor  77  configured to pivot mounting surface  28  (shown in  FIG. 1 ) about arc  44  (shown in  FIG. 2 ) such that the width of gap  74  is substantially uniform. Portion  76  then rotates beneath seam tracker  60  which tracks a seam (gap  74 ) and transmits a weld location signal to controller  62  which positions arc welder  50  accordingly. In an exemplary embodiment, arc welder  50  is mounted with a plurality of orthogonal sliding members  78  providing a two dimensional positioning capability. Portion  76  then rotates under flux dispenser  56  which dispenses an amount of flux (not shown) such that weld head  52  is submerged in flux and weld held  52  fabricates weld  68 . Portion  76  then rotates under vacuum nozzle  66  which vacuums loose flux. Portion  76  then rotates under scraper  70  which scraps hardened flux from weld  68 . The hardened flux falls into a chute leading to a trash dumpster (not shown). Accordingly, cylinder  40  is fabricated until the length is at a desired length and second drive roller  26  (shown in  FIG. 2 ) is stopped while cutter  34  (shown in  FIG. 2 ) rotates around cylinder  40  cutting cylinder  40 . In an exemplary embodiment, cylinder  40  is cut in a plane normal to cylinder  40 . In an alternative embodiment, cylinder  40  is cut in a plane other than normal to cylinder  40 . Accordingly, a cylindrical body is formed with a continuous weld. 
   After forming a plurality of bodies with continuous welds, coil  14  is exhausted of material  16 . Material  16  is pulled from coil  14  until an end portion (not shown) is positioned at splicing assembly  22 . A new coil (not shown) of material  16  replaces coil  14  and a beginning end (not shown) is fed through peeler  12  to first drive roller  18  and first drive roller  18  is engaged such that first drive roller  18  can drive or push the beginning end through straightener  20  to splicing assembly  22 . The beginning end is then joined to the end portion providing a continuous source of material  16 . In an exemplary embodiment, splicing assembly  22  includes a plasma torch (not shown) and a clamp welder (not shown). The plasma torch is utilized to trim the beginning end and the end portion. The trimmed beginning end is butted against the trimmed end portion and both are clamped down and welded together. Accordingly, a continuous source of material  16  is provided. 
   In an exemplary embodiment, material  16  is flexible gauge 11 steel, such as, for example, American Society for Testing and Materials (ASTM) A607 grade 50, ASTM A569 grade 50, ASTM A36, and ASTM A570 grade 50. Accordingly, cylinder  40  is deformable under its own weight and fixture  32  (shown in  FIG. 1 ) includes a plurality of side supports  80  to limit the deformation of cylinder  40  while supported in fixture  32 . 
     FIG. 4  is a perspective top view of a jacket  90  for a tank car (not shown). Jacket  90  is fabricated by making a cylindrical body  92  with a continuous weld  94 , as explained above, and cutting a longitudinal cut  96  and at least one cutout  97  in cylindrical body  92 . In an exemplary embodiment, continuous weld  94  is an outer fillet weld and an automated plasma torch (not shown) traverses a longitudinal path underneath cylindrical body  92  cutting longitudinal cut  96 . Longitudinal cut  96  allows a radius  98  to be increased, as explained below, to facilitate applying jacket  90  to the tank car. In an exemplary embodiment, an interior surface (not shown) is painted except for an approximately three foot wide longitudinal strip in a bottom portion (not shown) of cylindrical body  92 . 
     FIG. 5  is a front view of jacket  90  lifted in an anti-overspread beam  110  including a plurality of restricting arms  112 . Anti-overspread beam  110  further includes a plurality of chain mounts  114  for mounting a plurality of chains  116  including chain hooks  118  that hook on a plurality of edges  120  of jacket  90 . 
   During operation, two beams  110  are positioned over jacket  90  and chain hooks  118  are attached to edges  120 , beams  110  are placed one at each end (not shown) of jacket  90 . When beams  110  are raised, hooks  118  apply a force to edges  120  that causes radius  98  to distort from a normal state  122  to an enlarged state  124 . Restricting arms  112  contact jacket  90  in enlarged state  124  at contact points  126  preventing jacket  90  from inverting to an inside out state (not shown). Enlarged state  126  has a radius  98  greater than a radius (not shown) of the tank car including a layer of insulation (not shown). 
   An angle (head angle) is applied to a head (not shown) of the tank car to align jacket  90  with a first half (not shown) of the tank car and then jacket is positioned on the first half. Beams  110  are lowered allowing jacket  90  to return to normal state  122  and hooks  118  are removed from edges  120 . Accordingly, edges  120  are free to wrap around the tank car. After jacket  90  is applied to the tank car, jacket  90  is tightened around the tank car and a second jacket (not shown) is applied to a second half (not shown) of the tank car similarly. In an exemplary embodiment, second jacket overlaps jacket  90 . After the second jacket is tightened around the tank car, jacket  90  and the second jacket are fillet welded together and edges  120  are welded together on both jacket  90  and second jacket with an outer fillet weld. Jacket  90  and the second jacket are then welded to the tank car at a plurality of inlet nozzles (not shown), a plurality of attachment flashings (not shown), and a plurality of tank car heads (not shown). In an exemplary embodiment, jacket  90  is a jacket for a train tank car. In an alternative embodiment, jacket  90  is a jacket for a truck tank car. 
     FIG. 6  is a perspective view of a spiral welded roof  140  for a hopper car (not shown in FIGS.  1 - 6 ). Roof  140  is fabricated by making a cylindrical body  142  with a continuous weld  144 , as explained above, and cutting a plurality of longitudinal cuts  146  on both sides  148  of roof  140 . In an exemplary embodiment, cylindrical body  142  has four longitudinal cuts  146  and, accordingly, four roofs  140  are fabricated from cylindrical body  142 . Continuous weld  144  is an inner butt weld and an outer butt weld. Roof  140  includes at least one cutout  150  for hatch rings (not shown). 
     FIG. 7  is an end view of roof  140  attached to a hopper car  160  including a plurality of wheels  162 , two bulkheads  164  (one shown in FIG.  7 ), and two sidewalls  166 . To attach roof  140  to car  160 , roof  140  is positioned over bulkheads  164  and extending over sidewalls  166  creating an extension area  168 . Roof  140  is then welded to bulkheads  164  and sidewalls  166 . More specifically, and referring to  FIG. 8 , hopper car  160  includes a side wall  170  with a top chord  172  attached at a top portion  174  of side wall  170 . Roof  140  attaches to hopper car  160  via top chord  172 . In other words, top chord  172  is attached to side wall  170  and then roof  140  is also attached to top chord  172 . Accordingly, a roof for a hopper is fabricated from a cylindrical body using a continuous weld and the roof is attached to a hopper car. 
   While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.