Patent Publication Number: US-2021178528-A1

Title: Trackless Welding Carriage With Guide Wheel

Description:
FIELD 
     The present disclosure concerns portable welding carriages, and in particular self-propelled portable welding carriages. 
     BACKGROUND 
     Portable welding carriages are widely used in modern manufacturing processes to create welds. Welding carriages afford welders the freedom to monitor and control any number of welding parameters to provide consistent welds. Welding carriages can also be automated, freeing the welder to attend to other tasks. Welding carriages can be categorized broadly as to whether they require a track or not, i.e. are trackless. Where a track is implemented to guide the welding carriage, additional cost, time and complexity to setup the track may be incurred. 
     Some previous portable welding carriages include an adjustable height guide roller assembly. The guide rollers can be set to roll along a vertical member of a workpiece, or an added track provided specifically for this purpose, to guide the welding carriage as it rolls along the horizontal surface of the workpiece. Not all workpieces, however, may include or be suitably adapted to include a vertical member for guiding movement of a welding carriage along the horizontal plane of the workpiece. Thus, welding carriages implementing guide rollers to control movement of the carriage may not be suitable for some manufacturing processes. 
     U.S. Pat. No. 6,713,710 (“the 710 Patent”) discloses a welding apparatus with trackless movement. The apparatus is directed towards full penetration welding applications, typically required, for example, in large steel construction where turning over a workpiece to weld a second side may not be possible. It is well known in the art that full penetration welding from one side is typically achieved in one of two ways: joint penetration sensing technology for determining weld penetration or implementing a weld backing. 
     The 710 Patent teaches a welding apparatus implementing a weld backing for welding a butt joint along a weld line having a pre-existing gap. A connecting member extends from the welding apparatus on the top side of the workpiece, through the pre-existing gap, to the weld backing on the underside of the workpiece. In this manner, the weld backing is fixed to move synchronously with the welding apparatus as it travels along the workpiece. 
     The welding apparatus includes two roller units and a guide wheel unit, with each unit having a compression spring. The roller wheels generally support forward and reverse motion of the welding apparatus. The guide wheel is designed with inclined planes to contact with and roll in the pre-existing weld gap. The compression springs apply vertical pressure to the workpiece for two purposes. The first purpose is to keep the weld backing in contact with the underside of the workpiece. The second purpose is keep the guide wheel in contact with the pre-existing gap to continuously track the weld line. The welding apparatus is further connected to a stationary winch which drags the apparatus. 
     There remains a pressing need for further and better welding techniques including with respect to welding carriages. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front perspective view of a trackless welding carriage. 
         FIG. 2  is a front elevation view of the trackless welding carriage of  FIG. 1 , having a welding torch assembly rotated to provide a clear view of a carriage guide wheel behind. 
         FIG. 3  is a side elevation view of the trackless welding carriage of FIG. 
         FIG. 4  is a rear elevation view of the trackless welding carriage of  FIG. 1 , having a welding torch assembly rotated to provide a clearer view of a carriage guide wheel in front. 
         FIG. 5  is an expanded view of a torch alignment wheel of a torch alignment assembly of the welding carriage of  FIG. 1 , illustrating conforming engagement with a seam of the workpiece. 
         FIG. 6  is an expanded view of a carriage guiding wheel of the welding carriage of  FIG. 1 , illustrating conforming engagement with a carriage guiding seam of the workpiece. 
         FIG. 7  is an expanded side elevation view of a torch alignment assembly of the welding carriage of  FIG. 1 . 
         FIG. 8  is an expanded front elevation view of the trackless welding carriage according to  FIG. 1  showing the torch alignment assembly. 
         FIG. 9  is a perspective view of an exemplary cylindrical cargo trailer having a cylindrical container formed of longitudinal curved panels. 
         FIG. 10  is an end view of an exemplary container shown in  FIG. 9  illustrating welding of the inner joint seams by a trackless welding carriage according to the present disclosure. 
         FIG. 11  is an end view of an exemplary container shown in  FIG. 9  illustrating welding of the outer joint seams by a trackless welding carriage according to the present disclosure. 
     
    
    
     DESCRIPTION 
     A portable welding carriage  100  for performing trackless welding is disclosed herein. The welding carriage  100  has a body  101  which may include a base  102  rollably supported by a wheeled suspension  110  having wheels  112  mounted on axles  113  for rollably supporting the welding carriage  100  on a workpiece  160  having one or more seams  162 . Each seam  162  is a line or groove formed by the abutment of two or more parts of the workpiece  160 . The wheels  112  may include at least one carriage guide wheel  120  sized and shaped for conformable contact with a seam  162 , being a carriage guiding seam  163 , of the workpiece  160 . The carriage guide wheel  120  conformably contacts and rolls in the carriage guiding seam  163  sufficiently to restrict rolling engagement of the carriage guide wheel  120  in the carriage guiding seam  163 , thereby restricting laterally and aligning movement of the carriage  100  to the carriage guiding seam  163  as it rolls along the surface  161  of the workpiece  160 . In different embodiments, the carriage guiding seam  163  may be welded or unwelded. The restricted movement of the carriage  100  may be exploited to position at least one welding torch  132  in alignment with a seam  162 . Thus, as the carriage  100  is driven along the workpiece  160 , the welding torch  132  is aligned to move over the seam  162 , welding the seam  162  as the welding torch  132  passes over. Alignment of the carriage  100  with the seam  162  is achieved at least in part by alignment of the carriage  100  with the restriction of rolling movement of the carriage guide wheel  120  in the carriage guiding seam  163 . 
     The wheels  112  may include at least one support wheel  121 . In some embodiments, alignment is further achieved by driving the carriage guide wheel  120  to move the carriage  100 . In some embodiments the at least one support wheel  121  may be undriven so as to roll freely with the movement of the carriage  100 . In some embodiments, no force external to the carriage  100  is required to drive or drag the carriage  100  in alignment with the carriage guiding seam  163 . Thus, the carriage  100  may not require the costly and time consuming step of setting up tracks or other external equipment, such as a pulley apparatus, to guide movement of the carriage  100  in an alignment with a seam  162 . 
       FIGS. 1 to 4  show a welding carriage  100 . The carriage  100  has a base  102  to which welding equipment  130  is mounted. The welding equipment  130  may be mounted at least in part to a platform  105  mounted on and supported by the base  102 . The welding equipment  130  includes at least one welding torch  132 . The carriage  100  is supported by a wheeled suspension  110 . The wheeled suspension  110  comprises a plurality of wheels  112  including at least one carriage guide wheel  120 , which may be mounted to an axle  113 . The wheels  112  may include at least one support wheel  121 , which may also be mounted to an axle  113 . The support wheel  121  may have a non-slip covering such as a solid or pneumatic tire, which may be made of rubber or another durable, compressible material, to provide the support wheel with traction relative to the surface  161  of the workpiece  160 , and to provide vibration or impact absorption. A motor (not shown), which may be an electric motor, may be mounted to and/or enclosed in the base  102  and coupled to drive the at least one wheel  112 , which may be by coupling to an axle  113 , and in particular may be coupled to drive the at least one carriage guide wheel  120 . The wheeled suspension  110  thus provides rolling support for the carriage  100  to travel along the surface  161  of the workpiece  160 . 
     One or more carriage guide wheel  120  may include a generally circular disc composed of a rigid, durable material, for example metal, for example steel or aluminum, and other materials are possible. An annular rim of the carriage guide wheel  120  may be tapered, symmetrically or otherwise relative to a plane of the carriage guide wheel  120 , to form a carriage guide wheel tapered rim  122 .  FIG. 6  shows an enlarged view of a carriage guide wheel  120  in contact with a carriage guiding seam  163  of a workpiece  160 . A cross sectional profile of the carriage guide wheel tapered rim  122  of the carriage guide wheel  120  may be sized and shaped for conformable contact with the carriage guiding seam  163 . Sufficient conformation between the profiles of the carriage guide wheel tapered rim  122  and carriage guiding seam  163  may restrict rolling engagement of the carriage guide wheel  120  to a direction, which may be a longitudinal direction, of the carriage guiding seam  163 , and may otherwise minimize lateral movement, transverse to the rolling direction, of the carriage guide wheel  120  within the carriage guiding seam  163 . Propulsion of the carriage  100  by driving the carriage guide wheel  120  may further support alignment with the carriage guiding seam  163  and may eliminate or reduce need for other driving means, and eliminate or reduce need for other means to guide alignment of the carriage  100 . 
     In particular, superior alignment of the carriage  100  and mounted welding torch  132  with a seam  162  may be achieved if a carriage guide wheel  120  is driven to propel the carriage  100  while any support wheel  121  is undriven and turns freely with rolling movement of the carriage  100 . The inventors have discovered that, surprisingly, if instead a support wheel  121  is driven, it may generate some tendency of the carriage  100  to move laterally to the seam  162  and may tend to reduce alignment of the carriage  100  with the carriage guiding seam  163  by the carriage guide wheel  120 . Such tendency may include reduction of the conformable contact of the carriage guide wheel tapered rim  122  with the carriage guiding seam  163 , and may progress to such extent that the carriage guide wheel  120  is lifted, or ‘skips’, out of the carriage guiding seam  163 , causing the carriage  100  to lose alignment with the carriage guiding seam  163 . 
     In operation, the motor (not shown) may drive at least one carriage guide wheel  120 . The motor may be an electric motor, and a power source (not shown) may connect to the welding carriage  100 , and to the motor, to power the motor. For example, a power cable may connect the welding carriage  100  to a power source. Other sources of motive power are possible. 
     The plurality of wheels  112  provide rolling support for the carriage  100  to travel along the surface  161  of the workpiece  160 . The carriage guide wheel  120  may provide continuous rolling engagement with the carriage guiding seam  163  and restrict motion of the carriage  100  to travel in alignment with the carriage guiding seam  163 . At least one welding torch  132  aligned with at least one seam  162 , which may be the carriage guiding seam  163 , or a different seam  162 , may continuously weld the seam  162  as the carriage  100  travels in fixed alignment with the carriage guiding seam  163 . In this manner, the self-driven carriage guide wheel  120  may enable automatic trackless welding of a seam  162 . 
     The carriage guide wheel  120  and the carriage guiding seam  163  may have any dimensions appropriate to a given application, so long as the relative size and shape of the carriage guide wheel  120  and the carriage guiding seam  163  are such that the carriage guide wheel  120  conformably contacts and rolls in the carriage guiding seam  163  sufficiently to restrict rolling engagement of the carriage guide wheel  120  in the carriage guiding seam  163 , thereby restricting laterally and aligning movement of the carriage  100  to the carriage guiding seam  163  as it rolls along the surface  161  of the workpiece  160 . 
     In some embodiments, a width of the carriage guiding seam  163 , which may be a width at an opening of the carriage guiding seam  163 , is from 3 to 10 mm, or from 4 to 8 mm, or from 5 to 7 mm, or about 6 mm, or about 6.35 mm or about ¼″. In some embodiments, a depth of the carriage guiding seam  163  is from 1 to 5 mm, or from 2 to 4 mm, or about 3 mm, or about 3.175 mm, or about ⅛″. In some embodiments, a diameter of the carriage guide wheel  120  is from 5 to 25 cm, or from 10 to 20 cm, or from 13 to 17 cm, or about 15 cm, or about 15.24 cm, or about 6″. In some embodiments, a thickness of the carriage guide wheel  120  is from 5 to 20 mm, or from 6 to 16 mm, or from 10 to 14 mm, or about 12 mm, or about 12.7 mm, or about ½″. In some embodiments, a width and a depth of the carriage guiding seam  163  are ¼″ and ⅛″, respectively, and a diameter and a thickness of the carriage guide wheel  120  are 6″ and ½″, respectively. In order to enable the carriage guide wheel  120  conformably to contact and roll in the carriage guiding seam  163 , the carriage guide wheel tapered rim  122  may have the same or substantially similar dimensions as the carriage guiding seam  163 . 
     In some embodiments, the welding carriage  100  may include at least one torch alignment assembly  141  including a support arm  140  mounted to the base  102  and supporting the welding torch  132 , positioning the welding torch  132  in alignment with a seam  162 . The welding torch  132  may be positioned directly vertically above the seam  162 . Alternative alignment of the welding torch  132  with the seam  162  is possible. In general, the welding torch  132  is positioned such that a welding torch tip  134  is positioned proximal the seam  162  for optimal welding of the seam  162  by the welding torch  132 . 
     The torch alignment assembly  141  may include a support strut  150  coupled to a torch alignment wheel  142  having a torch alignment wheel rim  144  sized and shaped to conformably contact the seam  162 . Sufficient conforming contact between the torch alignment wheel rim  144  and seam  162  restricts rolling engagement of the torch alignment wheel  142  for alignment along a longitudinal direction of the seam  162 . The welding torch  132  may be aligned with, and positioned in close proximity to, the torch alignment wheel  142 . 
     The support arm  140  may be coupled to the base  102  by a support arm mount  143  configured to permit movement of the support arm  140  relative to the base  102 . For example, as shown particularly in  FIG. 8 , the support arm mount  143  may include a support arm mounting plate  145  having at least one slot  146  for passage of a retaining pin  147 , which may include a bolt and nut, a rivet, a carriage bolt, a flanged rod, or other similar fastener, mounted to the base  102 , to retain the support arm mounting plate  145  while allowing motion in a plane of the support arm mounting plate  145  involving sliding of the retaining pin  147  in the slot  146 . When the slot  146  is curved, as shown in  FIG. 8 , the support arm mounting plate  145 , and thus the support arm mount  143 , may move rotatably as the retaining pin  147  slides in the slot  146 , permitting the support arm mount  143  to swivel, thereby allowing the welding torch  143  to tilt, as illustrated by the arrow in the drawing. Alternatively, when the slot  146  is straight and extends transversely, the support arm mounting plate  145 , and thus the support arm mount  143 , may move transversely, or sideways, as the retaining pin  147  slides in the slot  146 , permitting the support arm mount  143  to shift laterally, thereby allowing the welding torch  143  to move laterally. In either case, movement of the welding torch  132  may cause transverse movement of the welding torch tip  134 . Such movement of the support arm mount  143  may be caused by contact force between the torch alignment wheel rim  144  and the seam  162 , translated upward via the torch alignment wheel  142 , thence the support strut  150 , thence the support arm  140 , to the support arm mount  143 . In other words, as the torch alignment wheel  142  rolls in the seam  162 , the contact forces which retain the torch alignment wheel  142  in the seam  162  cause, through the structure described above, adjusting movement of the welding torch tip  134  to maintain alignment thereof with the torch alignment wheel  142 , which, because it positioned in close proximity to the torch alignment wheel  142 , which is aligned with the seam  162 , thereby maintains alignment of the welding torch tip  134  with the seam  162 . 
     Thus, in embodiments having the torch alignment wheel  142  and assembly described above, the carriage guide wheel  120  may provide a first mechanism to maintain alignment of the carriage  100  with the carriage guiding seam  163 , thereby indirectly providing alignment of the welding torch tip  134  with the seam  162  to be welded, and the torch alignment wheel  142  may provide a further, second mechanism of alignment by guiding the welding torch tip  134  directly along the seam  162 , the welding torch tip  134  thereby closely tracking the seam  162  and welding it as the welding torch  132  passes over. To the extent that the seam  162  is not perfectly straight, or its cross-sectional profile is not perfectly regular along its entire length, or for any other reason that conformable rolling of the carriage guide wheel  120  in the carriage guiding seam  163  does not achieve perfect alignment of the welding torch tip  134  with the seam  162 , the torch alignment assembly  141  may function to refine the alignment of the welding torch tip  134 , thus achieving even closer alignment of the welding torch tip  134  with the seam  162 . 
     The torch alignment assembly  141  may further include a shield  149  mounted to the support strut  150  (or, alternatively, to the support arm  140 ), and disposed between the welding torch  132 , particularly the welding torch tip  134 , and the torch alignment wheel  142 , to protect at least the torch alignment wheel  142 , and in some embodiments also other components of the torch alignment assembly  141 , from damage or other change caused by heat or other radiation generated at the welding torch tip  134  and seam  162  during the welding of the seam  162 . 
     The welding carriage  100  may have more than one welding torch  132 , and correspondingly more than one torch alignment assembly  141 . For example, the embodiment shown in the drawings has two welding torches  132  and correspondingly two torch alignment assemblies  141 . Each welding torch  132  may be positioned to weld a corresponding seam  162 , each being supported by a corresponding torch alignment assembly  141  for alignment of the corresponding welding torch tip  134  with the seam  162 . Since each torch alignment assembly  141  may function independently of the other torch alignment assembly  141 , each torch alignment assembly  141  may be operative to maintain independently the alignment of its corresponding welding torch tip  134  and seam  162  even when the seams  162  are not perfectly parallel, or are otherwise characterized by some irregularity, general or local, and thus in such cases where perfect positioning of the welding torches  132  relative to the base  102  and carriage guide wheel  120  might not achieve optimal alignment of the corresponding welding torch tips  134  and seams  162 . 
     Moreover, since the torch alignment assemblies  141  may be operative for lateral movement of the corresponding welding torch tips  134  independently, but in respective alignment with the corresponding seams  162 , such arrangement makes possible optimal alignment of each welding torch tip  134  with its corresponding seam  162  even when the differences in lateral movement of the welding torch tips  134  are not the result of unintended irregularity in the seams  162  or their spacing, but also when such irregularity or spacing is intentional, and part of the design of the seams  162  in the workpiece  160 . While the welding carriage  100  may be advantageously useful to weld at the same time multiple seams  162  which are generally parallel, it may also be advantageously useful where the multiple seams  162  intentionally deviate from the parallel, e.g. where a lateral spacing of seams  162  increases or decreases along their length, or increases along a part of their length and decreases along a different part of their length, or otherwise varies along their length. Indeed, the provision of multiple torch alignment assemblies  141  may enable the simultaneous welding a first seam  162  that is generally straight, and a second seam that is generally irregular, for example having generally the shape of a sinusoidal wave, or a sawtooth wave, or another shape other than a straight line. Even if adjustments to the general configuration disclosed herein are required in applications where the seam  162  is not straight, the same general principles remain applicable. 
     In different embodiments, any suitable welding technology may be used, including, but not limited to, electrical welding, including arc welding, including shielded metal arc welding, gas metal arc welding, flux-cored arc welding, gas tungsten arc welding, or plasma arc welding. 
     In any of the embodiments disclosed herein, the welding equipment  130 , including particularly the welding torch  132 , or welding torches  132 , as the case may be, may be connected to a source of electrical current to power the welding equipment  130  and the welding torch(es)  132 . Such connection may include at least one electrical cable operatively connected to the welding equipment  130  and/or welding torch(es)  132 . In addition, the return current path may be provided by a further electrical connection, which may be by way of a further cable operatively connected to the welding equipment, and conductively contacting the workpiece. Alternatively, in any of the embodiments described herein, one or more of the carriage guide wheels  120  or torch alignment wheels  142  may function as a return current electrode. As described herein, one or more of the carriage guide wheels  120  or torch alignment wheels  142  may be formed of metal, which may be a conductive metal. As described and shown herein, and particularly including  FIGS. 5 &amp; 6 , the one or more of the carriage guide wheels  120  or torch alignment wheels  142  may form intimate, conforming, and reliable contact with the corresponding seam  162  in which that wheel rolls, thereby providing reliable electrical contact. The one or more carriage guide wheels  120  or torch alignment wheels  142  may be electrically connected to the welding equipment  130  and/or source of electrical current on the current return path, and thus may be thus configured to function as the welding equipment current return electrode. As will be apparent from a consideration of  FIG. 1 , for example, in such case, the respective first location of each of the one or more welding torch tips  132 , where welds are formed in the corresponding seam  162 , and where electrical current will therefore enter the workpiece  160 , and the second location of contact with the workpiece  160  of each of the one or more carriage guide wheels  120  or torch alignment wheels  142  functioning as the return current electrode as described, and thus where electrical current will exit the workpiece  160 , will be separated by a fixed or minimally variable distance. As such, the return current path through the workpiece  160  may be maintained at a relatively fixed length, or variability of such path may be minimized, thereby minimizing or at least decreasing variability in the welding current flowing into the workpiece  160  at the seams  162  where the welds are formed, and thereby maximizing, or at least improving, a quality of the welds thus formed. In particular, in some embodiments, for each welding torch  132 , the corresponding torch alignment wheel  142  is configured to function as the return current electrode as described. Thus, when multiple welding torches  132  and torch alignment assemblies  141  are provided, as shown in  FIG. 1  for example, if a spacing between each welding torch  132 , particularly the welding torch tip  134 , and the corresponding torch alignment wheel  142  is the same, then each will provide the same, or approximately the same, return current path, and thus variability in the quality of the welds respectively formed by the different welding torches  132  and associated with the return current path may be eliminated, reduced, or minimized, thereby improving or optimizing consistency in the quality of the welds formed by the different torches  132 . 
     The welding carriage is generally useful to weld any seam and advantageously provides improved alignment between the one or more welding torch tips and corresponding seams. In particular, the welding carriage is especially advantageous in applications where other structures and arrangements for supporting, aligning, and moving welding equipment is impossible, unwieldy, or otherwise disadvantageous. For example, the welding carriage may be especially advantageous where the surface of the workpiece is curved, is disposed in a constrained space, such as an enclosure, in a remote location (e.g. where supporting infrastructure is available), or in a location hazardous to humans. 
     For example,  FIGS. 9-11  illustrate uses of the welding carriage to weld a cylindrical cargo container  204  mounted on a wheeled suspension  202  of a cylindrical cargo trailer  200 , as shown in  FIG. 9 . The cylindrical cargo container  204  and trailer  200  may be as disclosed in WIPO International Application No. PCT/CA2017/051538 or PCT/CA2017/051544, the entireties of which are incorporated by reference herein. 
     Thus, the cylindrical cargo container  204  may be formed by a plurality of arcuate panels  210 , which may be extruded panels, each having the shape of a cylinder segment, which may be configured with tongue-and-groove joints, and assembled to form a complete cylinder prior to welding. The panels  210  may be formed of any suitable material, which may be a metal, which may be steel or aluminum, and have any suitable dimensions including thickness. Joints between the panels may form inner seams  212  and outer seams  214 , which may be welded by use of the welding carriage  100 , to form welded seams  216 . 
     For example, by the methods disclosed in WIPO International Application No. PCT/CA2017/051544, the container  204  may be assembled using collars  220  which encircle the container  204  and constricted to compress the joints, and the cylindrical container  204  and collars  220  together may be rolled about a longitudinal axis of the container  204  using a rolling apparatus  230  such as a tank roller. The welding carriage  100  may be used to weld the inner seams  212 , by placing the welding carriage  100  at one end of the container  204  with the one or more carriage guide wheel  120  resting and engaged in an inner seam  212 , and each torch alignment wheel  142  also resting and engaged in an inner seam  212 . If the welding carriage  100  has two welding torches  132  and corresponding torch alignment assemblies  141 , their respective torch alignment wheels  142  may be engaged in corresponding inner seams  212  for alignment with corresponding welding torch tips  134 . One of the torch alignment wheels  142  may ride in the same inner seam  212  as the carriage guide wheel  120 . Thus placed, the welding carriage  100  may be moved down the length of the container  204 , which may be by driving the at least one carriage guide wheel  120 , which may be by the motor  104 , while the inner seams  212  with welding torch tips  134  positioned for alignment with the inner seams  212  are welded to form welded seams  216  using the welding equipment  130  including the welding torches  132  and welding torch tips  134 . Once one or more inner seams  212  is welded in a first pass, the welding carriage  100  may be lifted, or otherwise repositioned, to permit rolling rotation of the container  204  to bring adjacent a bottom position one or more further inner seams  212  to be welded, and the welding carriage  100  may be replaced for welding of the inner seams  212  as described above. In this manner, a plurality or all of the inner seams  212  of the container  204  may be welding using the welding carriage  100 . 
     Having used the welding carriage  100  to weld the inner seams  212 , the collars  220  may be removed, and the welding carriage  100  may be used to weld the outer seams  214  in a similar manner. The welding carriage  100  may be placed at one end atop the container  204  with the one or more carriage guide wheel  120  resting and engaged in an outer seam  214 , and each torch alignment wheel  142  also resting and engaged in an outer seam  214 . If the welding carriage  100  has two welding torches  132  and corresponding torch alignment assemblies  141 , their respective torch alignment wheels  142  may be engaged in corresponding outer seams  214  for alignment with corresponding welding torch tips  134 . One of the torch alignment wheels  142  may ride in the same outer seam  214  as the carriage guide wheel  120 . Thus placed, the welding carriage  100  may be moved down the length of the container  204 , which may be by driving the at least one carriage guide wheel  120 , which may be by the motor  104 , while the outer seams  214  with welding torch tips  134  positioned for alignment with the outer seams  214  are welded to form welded seams  216  using the welding equipment  130  including the welding torches  132  and welding torch tips  134 . Once one or more outer seams  214  is welded in a first pass, the welding carriage  100  may be lifted, or otherwise repositioned, to permit rolling rotation of the container  204  to bring adjacent a top position one or more further outer seams  214  to be welded, and the welding carriage  100  may be replaced for welding of the outer seams  214  as described above. In this manner, a plurality or all of the outer seams  214  of the container  204  may be welding using the welding carriage  100 . 
     For either or both of the inner seams  212  and outer seams  214 , an entire length may be welded without external equipment to move the welding carriage  100 , while the alignment mechanisms described herein achieve optimal alignment of the welding torch tips  134  to weld the seams. Moreover, when the at least one welding torch  132  is mounted as shown particularly in  FIG. 3 , such that the welding torch tip  134  is disposed at an end of the welding carriage  100  beyond both the torch alignment wheel  142  and the wheels  112 , then the welding carriage  100  may be used advantageously to weld the seam  162  to the very end of the seam  162 . Moreover, in each case described above, the seams  162  are welding from above, with the welding torch  132  disposed substantially vertically, thus producing a superior weld, as is known to be produced when the welding torch  132  is disposed vertically above the seam  162  as opposed to below the seam  162  or at an oblique angle. Moreover, when the welding carriage  100  is used to weld the outer seams  214  and is thus placed atop the container  204  as described above, the engagement of the carriage guide wheel  120  with the carriage guiding seam  163  may function to stabilize the welding carriage  100  atop the container  204 , and to prevent or reduce lateral movement. In particular, when the welding carriage  100  is propelled by driving the carriage guide wheel  120  using the motor  104 , the chances of the carriage guide wheel  120  disengaging from the carriage guiding seam  163  may be reduced, thus reducing the chances of the welding carriage  100  falling off of the container  204 . 
     The following are non-limiting examples of embodiments of the subject matter disclosed herein. 
     Example 1. A welding carriage, comprising: a body supported by a wheeled suspension comprising a plurality of wheels comprising a carriage guide wheel having a tapered rim sized and shaped to roll in conforming contact with a carriage guiding seam of a workpiece; and welding equipment mounted to the body, the welding equipment comprising a welding torch for welding an unwelded seam of the workpiece. 
     Example 2. The welding carriage according to Example 1, wherein the unwelded seam is the carriage guiding seam. 
     Example 3. The welding carriage according to Example 1, wherein the unwelded seam is different from the carriage guiding seam. 
     Example 4. The welding carriage according to any one of Examples 1 to 3, wherein: the carriage guide wheel is a first carriage guide wheel; the tapered rim is a first tapered rim; the wheeled suspension further comprises a second carriage guide wheel having a second tapered rim sized and shaped to roll in conforming contact with the carriage guiding seam of the workpiece. 
     Example 5. The welding carriage according to any one of Examples 1 to 4, wherein the conforming contact restricts lateral movement of the welding carriage for alignment with the carriage guiding seam. 
     Example 6. The welding carriage according to any one of Examples 1 to 5, wherein the welding torch is mounted to the body relative to the carriage guide wheel for disposition of a welding torch tip of the welding torch in alignment with the unwelded seam of the workpiece. 
     Example 7. The welding carriage according to any one of Examples 1 to 6, configured to weld the unwelded seam when the welding carriage moves with the carriage guide wheel rolling in the carriage guiding seam. 
     Example 8. The welding carriage according to any one of Examples 1 to 7 further comprising a motor coupled to drive the carriage guide wheel or a support wheel of the wheeled suspension to move the welding carriage with the carriage guide wheel rolling in the carriage guiding seam. 
     Example 9. The welding carriage according to Example 8, wherein the motor is coupled to drive the carriage guide wheel. 
     Example 10. The welding carriage according to Example 9 when dependent on Example 4, wherein the motor is coupled to drive the first carriage guide wheel and the second carriage guide wheel. 
     Example 11. The welding carriage according to Example 9 or 10, wherein the support wheel is undriven by the motor. 
     Example 12. The welding carriage according to any one of Examples 1 to 11, wherein the motor is mounted on or in the body. 
     Example 13. The welding carriage according to any one of Examples 1 to 12 when dependent on Example 3, further comprising a torch alignment assembly mounted to the body, wherein the welding torch is mounted to and supported by the torch alignment assembly, and wherein the torch alignment assembly is configured to align the welding torch with the unwelded seam. 
     Example 14. The welding carriage according to Example 9 when dependent on Example 6, wherein the torch alignment assembly is configured to align the welding torch tip with the unwelded seam. 
     Example 15. The welding carriage according to Example 13 or 14, wherein the torch alignment assembly comprises a support arm coupled to suspend the welding torch over the unwelded seam, and a torch alignment wheel having a torch alignment wheel rim sized and shaped to roll in conforming contact with the unwelded seam, wherein the torch alignment wheel is coupled to move the support arm and welding torch in alignment with the unwelded seam. 
     Example 16. The welding carriage according to Example 15, wherein the support arm is coupled at a support arm first end to a support arm mount and at a support arm second end to the welding torch, wherein the support arm mount is mounted to the body to permit movement of the support arm and welding torch in alignment with the unwelded seam. 
     Example 17. The welding carriage according to Example 16, wherein the support arm mount comprises a support arm mounting plate comprising at least one slot sized and shaped to receive a retaining pin mounted to the body, the retaining pin configured to retain the support arm mounting plate in contact with the body while permitting movement of the support arm mounting plate by relative movement of the slot about the retaining pin. 
     Example 18. The welding carriage according to any one of Examples 13 to 17, wherein the torch alignment assembly aligns the welding torch with the unwelded seam by movement of the welding torch laterally relative to a longitudinal direction of the unwelded seam. 
     Example 19. The welding carriage according to any one of Examples 1 to 18 wherein: the unwelded seam is a first unwelded seam; and the welding equipment further comprises a second welding torch for welding a second unwelded seam of the workpiece. 
     Example 20. The welding carriage according to Example 19 when dependent on Example 13, wherein: the torch alignment assembly is a first torch alignment assembly; the welding carriage further comprises a second torch alignment assembly mounted to the body; the second welding torch is mounted to and supported by the second torch alignment assembly; and the second torch alignment assembly is configured to align the second welding torch with the second unwelded seam. 
     Example 21. The welding carriage according to any one of Examples 1 to 20, wherein a width of the carriage guiding seam is from 3 to 10 mm. 
     Example 22. The welding carriage according to any one of Examples 1 to 21, wherein a depth of the carriage guiding seam is from 1 to 5 mm. 
     Example 23. The welding carriage according to any one of Examples 1 to 22, wherein a diameter of the carriage guide wheel 120 is from 5 to 25 cm. 
     Example 24. The welding carriage according to any one of Examples 1 to 23, wherein a thickness of the carriage guide wheel is from 5 to 20 mm. 
     Example 25. A kit for modifying a welding carriage, the kit comprising: a carriage guide wheel having a tapered rim sized and shaped to roll in conforming contact with a carriage guiding seam of a workpiece; and instructions for modifying the welding carriage to have the carriage guide wheel. 
     In the preceding description, for purposes of explanation, numerous details are set forth in order to provide a thorough understanding of the embodiments. However, it will be apparent to one skilled in the art that these specific details are not required. In particular, it will be appreciated that the various additional features shown in the drawings are generally optional unless specifically identified herein as required. The above-described embodiments are intended to be examples only. Alterations, modifications and variations can be effected to the particular embodiments by those of skill in the art. The scope of the claims should not be limited by the particular embodiments set forth herein, but should be construed in a manner consistent with the specification as a whole.