Abstract:
A rail restraining ( 1 ) and weld delivery device ( 100 ) uses a frame for supporting a welding head with a clamp ( 3 ) for restraining a first rail end and a second rail end and a base twist assembly ( 17 ) for aligning said first end and second end. An interconnected weld containment apparatus ( 290 ) pivotally connects to the clamp by use of a cam actuated linear pin ( 7 ). This arrangement is operable in an environment in which clearance between rails is about 7 to 11 inches and sufficiently compact that it may be operated from and carried in a truck based on a standard over the road truck.

Description:
CLAIM OF PRIORITY 
     Priority is claimed based on Provisional Application Ser. No. 60/069,795, filed Dec. 16, 1997, which is incorporated by reference as if fully set forth herein. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention is as described herein and shown in the accompanying drawings is for a rail welding apparatus incorporating a railroad rail restraining device, weld containment device and weld delivery unit having improved rail restraining characteristics, improved weld supporting properties and being compact, lightweight and economical for greater utility. The restraining device enables the positioning of rail ends of either long prewelded rails, special rail sections for appliances such as in frogs or turn-outs or switches, existing rails in need of repair, or a combination of these. Because of the high strength, improved geometry and design, the device can be utilized in the gas-arc welding of highly restricted clearance rail splices or joints, such as in welding a length of rail to a turn-out assembly. 
     2. Description of Related Art 
     In the prior art, there are three main ways to weld railroad track. These include aluminothermic welding (U.S. Pat. Nos. 5,215,139 and 5,306,361), flash-butt welding (U.S. Pat. Nos. 4,929,816; 5,270,514; and 5,469,791); and gas-arc welding (U.S. Pat. No. 5,605,283). These all have certain advantages and disadvantages. Aluminothermic welding has low equipment requirements, is economical to perform but produces welds of less strength than the other methods. Flash butt welding uses complex equipment but produces high strength welds, however it is difficult to use to join rails in the field, and results in a loss of rail length, which can cause difficulties. Gas-arc welding requires precise alignment and a considerable length of time to perform a weld of sufficient strength, heretofore also requiring equipment of considerable size, complexity and cost. The invention enables the use of gas-arc welding with greater ease and lower cost. 
     SUMMARY OF THE INVENTION 
     The rail restraining device, weld containment device and weld delivery unit of the invention needs to handle rail sections often as long as one-quarter mile, aligning rail ends precisely for welding, yet can be made sufficiently compact to be incorporated on a hi-rail equipped over-the-road truck or shipping container on a chassis or car having economy and requiring no special licensing or equipment for over-the-road use while being sufficiently small sized itself to fit in the space available to weld rails even to switch or turnouts or in frogs where the weld joint is separated from the adjacent rail portion by as little as about 7″ to 11″. 
     The rail restraining device and weld delivery unit takes up a sufficiently small volume of space that the truck can be fitted with room for the welder itself, control devices; generator; and gas bottles; as well as the welding robot mounted on the unit. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front elevation of an alternative embodiment of the rail restraining device. 
     FIG. 2 is a side elevation of an alternative embodiment of the rail restraining device. 
     FIG. 3 is a top plan view of an alternative embodiment of the rail restraining device. 
     FIG. 4 is a front elevation of the rail weld containment device. 
     FIG. 5 is a top plan view of the rail weld containment device. 
     FIG. 6 is a sectional view of an alternative embodiment of the weld delivery unit. 
     FIG. 7 is a top plan view of an alternative embodiment of the weld delivery unit. 
     FIG. 8 is a side elevation of the guide rod of an alternative embodiment of the weld containment device. 
     FIG. 9 is a front elevation of the guide rod of an alternative embodiment of the weld containment device. 
     FIG. 10 is a side elevation of the cam guide of an alternative embodiment of the weld containment device. 
     FIG. 11 is a front elevation of the cam guide of an alternative embodiment of the weld containment device. 
     FIG. 12 is a top plan view of the preferred rail restraint device. 
     FIG. 13 is a front elevational view of the preferred rail restraint device. 
     FIG. 14 is a sectional view of the preferred rail restraint device showing the clamping arms in open and closed positions. 
     FIG. 15 is an enlarged section of the twist pin and cam adjustment of the weld containment device. 
     FIG. 16 is a side elevation of the preferred twist pin of the weld containment device. 
     FIG. 17 is a front elevation of the preferred twist pin of the weld containment device. 
     FIG. 18 is a side elevation of the preferred cam guide of the weld containment device. 
     FIG. 19 is a front elevation of the preferred cam guide of the weld containment device. 
     FIG. 20 is a rear elevation of the preferred embodiment of the weld delivery unit. 
     FIG. 21 is a side sectional view of the preferred embodiment of the weld delivery unit. 
     FIG. 22 is a top plan view of the preferred embodiment of the weld delivery unit. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The rail welding fixture consists of the rail restraint assembly  1  and the weld containment device  290 . The weld containment device  290  prevents the molten metal from flowing out of the web and head areas during the welding. In a sense, this device is an automatically positionable and removable mold for welding. The weld delivery unit  100  is the truck and the robot lift, as well as the ancillaries such as generator, gas bottles, tools, etc. 
     The rail welding fixture in a prototype and alternative embodiment has rail restraint  1  (FIGS. 1-3) which provides the structure on which a fixed clamp  2  and movable clamp  3  are mounted in pairs. One of said clamp pairs will engage the end of each of the respective rail sections to be welded. The preferred embodiment will be described in greater detail insofar as its elements may be delineated. The alternative embodiment has several features which may be advantageously adapted to other embodiments, although the preferred embodiment uses, for example, hydraulic rather than mechanical actuation. In certain circumstances, the mechanical actuation described herein may be advantageous. 
     In this alternative embodiment, moveable clamp member  3  has an eccentric pivoting action around pin  7  which can be clamped in place by the action of handwheel  11  fastened to screw  6  with wheel locking mounting  12 , thence acting in turn on clevis pins  5  and  9  through link pin  8  and link  4  and rollers  13 , fastened by nut  14 . This acts through bushing  10  ultimately on the pad  16  carried on ball  15  providing clamping action on the web of the rail. A horizontal plate supports the device on the crown of the rail. 
     Another alternative feature relates to alignment of the rails&#39; ends to line up their respective center lines as accomplished through the clamping force on each of the four pads on the respective two clamps. Rails may also be distorted and out of line in a twisting manner. The respective clamps are provided with a base twist assembly  17  mounted on one of the frame members of the rail welding fixture. The rail welding fixture components are mounted with a variety of fasteners  18 - 24 . 
     In this alternative embodiment, base twist assembly  17  bears at an angle through a shaft  25  on a pad  26  that engages the base  27  of the rail  28 . In this manner, the two rail ends  30 ,  31  can be precisely aligned both with a calculated gap  32  and in vertical and transverse directions to enable the next step of the operation utilizing the weld containment device. 
     The second component in the preferred system is the weld containment device  290  which works integrally with the rail restraint  201 , fitting on frame  270  thereof While preferably used together, and providing unique advantages in combination, weld containment device  290  may be suitable for other welding operations, merely providing its advantages in compactness and rapid deployment. 
     The weld containment device  290  (FIGS. 4-5) is a separate part of the rail welding fixture  200  and is placed into the rail restraining assembly  201 , specifically being mounted (FIG. 12) on four locating pins  286  on frame  270 . It is clamped to the rail restraint  201  using four clamps  287  for securing. 
     The weld containment device  290  is set up on a rigid frame  291 . Two yokes  293  are actuated by a pair of cylinders  297  mounted exterior to frame  291  and the cylinder rods are connected to the yokes  293  causing them to move inwardly. Cylinders  297  are operated through pressure transmitted in hydraulic fittings  298  in the ordinary manner of hydraulic operation. The yokes are mounted on two linear bearings or bushings  300  secured to the yoke using shoulders  301 . Other fasteners, such as snap rings, might be suitable, but need to have adequate strength. The bearings  300  slide on two hardened steel shafts  302 . The shafts cause the motion of the yoke to be precisely linear and parallel with each other. 
     A twist pin  259  is rigidly connected to the block holders  292  through the use of pins  299  preventing rotation of the twist pin  295 . Cooling blocks  310 , preferably constructed of copper, are connected to the block holders  292  by a plurality of fasteners  304  and  305 . The cooling block  310  and block holder  292  are the major components in the swinging components referred to generally as the quadrants  294 . 
     A smaller non-moving cooling block  306  is held to the frame  291  by a plurality of fasteners  307 . As the cylinder extension causes the motion of the yokes inward from the open position to the closed position, the action of the twist pins  259  engaged by the cam guide  296  causes a rotation of the quadrants  294 . The scope of the swing may be as little as about 15 degrees to about 30 degrees with about twenty degrees currently preferred. 
     In the preferred embodiment, in FIGS. 4-5 and FIGS. 15-19, adjustment of the precise rotation of the cam guides  296  is provided through the use of an adjustable hub device  295 . This device  295 , which is commercially available and is sold under the trademark Trantorque, uses twin tapered shaft segments  308 ,  309  to impinge on the cam guide  296  while at the same time impinging on the hole in the frame  291 . This operates in a manner analogous to a collect, release of the load on the tapered shaft segments  308 ,  309 , by loosening adjusting nut  311 , permitting movement of the guides  296 . 
     Precise adjustment of the cam guides  296  provides for a tightening effect as the blocks  3   10  contact the rail on the extend stroke. A compliant fit of the blocks  310  against the rail  28  is provided by a pair of springs  303  in each block. 
     Cooling blocks  310  and  306 , when in place on the rail, provide for a welding head aperture  314  through which the welding head can fill the rail web and head as described below, even when the blocks are closed and the shoe quadrants touch on the extend stroke. 
     During the return stroke, the yoke  293  pulls the quadrants  294  back by engaging a shoulder  317  on the twist pin shaft  318 . This shoulder  317  holds the quadrant in relative proximity while still allowing a rotation about shaft  318 . Since the twist pins  259  are fixedly fastened to the quadrants, parting of the containment shoes is accomplished by pulling the pins apart. The clearance is preferably somewhat less than about one and one half inches (1.5″) thereby providing access to the rail gap  32  of about 1 inch, yet providing a level of preload on the yoke and quadrant arrangement. 
     An early prototype pin or rod  45  for right hand travel is shown in FIGS. 8 and 9. Cam portion  65  has twist to provide 30 degrees rotation in ¾ inch travel. Shaft portion  66  is provided with groove  67  to receive ring  53 . Knurled or splined portion  68  abuts head  69 . Preferably about thirty two teeth will be formed in splined portion  68 . Head  69  fits in aperture  70  in holder  72 . A press fit into aperture  70  is anticipated. At the quadrant end, set screw  52  also serves to firmly fix the unit in position. In certain embodiments, a large number of small profile splines could be used with mating splines in the frame  291  to enable some level of adjustment by removal and replacement at a different alignment. This would enable mechanical adjustment but would be limited in the increments available by the size and number of splines. The preferred arrangement permits adjustment in infinite increments and is expected to be adjustable in the field. 
     The early prototype cam guide  46  in FIGS. 10-11 has a body portion  80  and aperture  82  with opposed lobes  84  receiving cam portion  65 . Lobes  84  could be formed with a profile enabling them to receive either the right or left hand cam portions  65 . For improved strength and precision, however a left and right cam guide could also be provided. 
     The preferred twist pin  259  (FIG. 16) is designed to have about  15  degrees of rotation in about three quarters inch (¾″) of linear travel. This limit has been evaluated as an operative range, however, as of the filing date of this application, it is believed that 20 degrees may be preferred. The difference in the drawings is not expected to be significant in light of the disclosure herein of the prototype which used 30 degrees of rotation in the same length of travel. One set of twist pins  259  and cam guides  296  will have right hand travel and the other set  259  L and  296  L left-hand travel (FIG.  5 ). 
     Preferred twist pin  259  and cam guide  296  for right hand travel is shown in FIGS. 16-19. Cam portion  315  is shown having a twist of 15 degrees rotation in three quarters inch (¾″) travel. As described above, 20 degrees may be preferred. Shaft portion  316  is provided with a shoulder  317 . Shaft end  318  provides for insertion into the block holders  292  and through bushing  297  and securement with pins  259 . 
     Cam guide  296  has a body portion  330  aperture  332  with opposed lobes  334  receiving cam portion  315 . Preferably lobes  334  can be formed with a profile enabling them to receive either the right or left hand cam portions  315 . For improved strength and precision, however a left and right cam guide could also be provided. The degree of twist will conform to that of the corresponding pin  259 ,  259 L. 
     Unlike the prior art, this geometry for operating quadrants  294  permits operation in very close clearance locations. The combination of longitudinal movement of yokes  293  into and out of engagement and the outward swinging of block holders  292  on horizontal, longitudinally aligned shafts  302  and pins  259  enables adequate clearance for the welding head to move reciprocally and vertically to weld the rail bases together, while closing the blocks to maintain the welding material in the web, and thence such clearance as is necessary to weld the head of the rail. This movement provides for both effective welding and compact size. Previously difficult to gas arc weld locations such as rail in turnouts and frog joints can be welded, when they could not easily be welded under prior art apparatus, methods, or fixtures. 
     The blocks  310  conform to the profile of the rail  28  for the purpose of containing molten material as the weld progresses. The welding operation will be accomplished by the following steps: placing a ceramic base mold below the rail base; placing the selected metal on the ceramic; and then commencing the welding operation whereby approximately one inch (1″) gap between the rail ends is filled by welding material. 
     Using a continuous precisely controlled welding cycle will move the welding element back and forth across the gap resulting in the filling of the gap with metal material having mechanical properties commensurate with that of the metal in the rail itself. To control this weld, the transverse distance the welding element will travel at the base being a long distance, while only a short distance of travel is necessary in the web portion, the blocks will be swung out of the way of the welding element at the beginning of the weld. As the welding operation progresses in a vertical manner through the web of the rail, the blocks will be closed on the web to maintain the molten material in place. The weld will progress up the web while the blocks provide the required containment yet also providing the necessary clearance for the welding element. This movement can be controlled and coordinated by processing data on positioning and the like received from a robotic controller. 
     A specific welding procedure will be a function of the welding unit used, which is not a part of this invention. For example, arc welding could be used, while theoretically, gas welding or aluminothermic bonding may be adapted to take advantage of certain aspects of the invention, such as the rail restraint or weld containment. The preferred welding method would be arc welding. However, great flexibility is provided by the invention adaptable to the metallurgy of the rails, the equipment available, and the equipment in operation at any particular time. 
     One possible weld delivery unit  100  shown in FIGS. 6-7 will have a frame  102  mounted in truck  104 . A vertical support piece  106  fits sliding rack  108 . Vertical support piece  106  at its lower portion  108  supports horizontal cradle  110  adapted to have rail engaging bogie wheels  112 . Thus, the device can be raised for transportation, maintenance, or the like, and lowered for alignment on the railroad rails to reduce the load on the structure and steady the unit for operation and enable indexing to an adjacent continuous rail, the welds along any given section of rail being staggered as between the left and right rails. 
     The weld delivery unit  100  has sufficient volume of space to receive the welder  114  itself, control devices  116  generator  118  and gas bottles; as well as the welding robot  122  mounted on the unit  124  retracted in the body of the truck for protection and ease of transportation. 
     As taught in FIGS. 6-7 the weld delivery unit is basically indexed to the rails  28  by virtue of cradle  110  and bogie wheels  112 . This provides an advantage in quick movement and lack of bracing or other connection to the roadbed. In certain conditions this type of alignment could have significant utility. However, the preferred method is to now support the rail restraint  201  using stabilizing legs and screw assembly  280  and this structure can then be used as a reference for calibrating the welder, using touch sensing plates  279 . 
     The preferred rail welding fixture  200  has a rail restraint  201  (FIGS. 12-14) which provides the structure on which the fixed clamp  202  and the movable clamp  203  are mounted in pairs. One of said clamp pairs would engage the end of each of the respective rail sections to be welded. Fixed clamp  202  has downwardly depending arm  205  with a clamping member including a pad  223  that provides a base against which the rail  28  can be clamped, and provides the requisite electrical contact as may be required by the welding operation. These are paired for each clamp assembly. 
     The movable clamp member  203  with downwardly depending arm  219  has an eccentric pivoting action around pin  207  which can be clamped in place by the action of a cylinder  211 . The rod  225  of cylinder  211  is fastened to a clevis  208  and pinned to a link  210  with a pin  209 . The rotation of link  210  is constrained by link adjustment assembly  213  which is composed of a rotating structural beam  212 , a screw  214  penetrating through the beam  212  with a rotary joint  215  connected to the clevis  208  and pin  209  using a block  217 . Block  217  rotates around pin  209 . The force applied by the cylinder acts through the clevis pin  209  with a variable reaction force taken by the shoulder bolts  220  directing a clamping force downward against moveable clamp. The structural beam  212  is held in the rail restraint  201  using shoulder bolts  220 . 
     It will be seen that said arm  203  has an inverted L shape with pin or pivot  207  being located proximate the end of the short leg of the L. Pin  221  provides the second pivot, this being located proximate the intersection of the short leg of the L and the long leg of the L. Clamping pad  225  is located at the end of the long leg of the L. 
     The length of this link adjustment assembly  213  is controlled by rotation of a handwheel  206  attached to the screw  214 . The length of the final adjustment length of the link adjustment assembly  213  is held in place using check nut  222  for locking. 
     Link adjustment assembly  213  provides one arm in a scissors arrangement with link  210  providing a second arm and the top portion  218  of clamp  203  a third. The extension or retraction of cylinder  211  acting on pivot  209  results in the pivoting of link adjustment assembly at pin  209  and bolts  220 . Link  210  pivots at pins  209 ,  221  and portion  218  around pins  207 ,  221  results in exertion of a substantial clamping force owing to the fixed positions of pins  207  relative to bolts  220  in beam  212 . 
     The force applied by the cylinder acts through the clevis pin  209  with a variable reaction force taken by the shoulder bolts  220  directing a clamping force downward against moveable clamp  203  and carried on ball unit  224  fastened by nut  226 . The cylinder is mounted in the beam  212  of restraint  201  with cylinder mounting pins  204 . 
     Stabilizing legs  274  are adjustable and provide additional stability of the rail restraint support. The legs  274  are allowed to slide in the bushing  275  and held in place with setscrews  276  which may alternatively be actuated with wingnuts (FIG. 13) or handles (FIG. 12) or other appropriate manual gripping end. The rail restraint  201  is lifted into place by the use of two handles  277  located apposite each other on the top of the frame  270 . 
     By comparison to the alternative embodiment, the use of legs  274  provides a platform fixed relative to the ground or roadbed. This enables the use of various bars, clamps and jacks, familiar to one in the track art, which may be hooked or otherwise fixed to a rail and jacked against the ground or roadbed to directly control twist. In addition to the greater precision of alignment this also enables track workers to use familiar alignment and adjustment tools as may be necessary to specific jobs. 
     In robotic welding operations, touch sensing plates  279  are attached to blocks  278  which are attached to the frame  270  to allow the robotic controller to establish the location of the rail restraint  201  and thence the weld gap by touching the plates with an electrically live torch tip. Pluralities of these plate assemblies are mounted on the frame  270  for accurate location of the weld gap. Around the perimeter of the frame  270  are located a plurality of windscreens or flaps  281  for prevention of ambient winds affecting the gas shield of the welding process. 
     The rail restraint  201  is supported on the rail using jacking screw assemblies  280  in which handle  282  rotates screw  283  mounted in a fixed horizontal plate  286  by threading, and having rotary shoes  284  attached to the end of screw  283 . Shoe  284  is positioned so as to be centered on and bear against the head of the rail  28 . In this manner, clockwise rotation of a right hand threaded screw  283  will raise rail restraint  201 . 
     Improvements in the preferred embodiment when compared to our earlier prototype include the use of the hydraulic cylinder  210  and scissors mechanism; use of adjustable legs  274  and screw assembly  280  and addition of touch sensing blocks  278  and wind screens  281  for superior weld control. 
     The preferred weld delivery unit  400  (FIGS. 20-23) will consist of a common truck chassis  402  specially equipped to be operable on railroad rails by use of front and rear rail-engaging bogies  404 . Mounted on the truck chassis  402  is a van-style cargo box  406 , which houses and protects all of the associated process equipment. The process equipment includes a welder  408 , a robot  409  (mounted on its side), a robot controller  410 , and an induction heating system  412 . 
     Auxiliary equipment includes an electric power generator  414 , driven from the truck engine through a power take-off transmission  416  and drive shaft  418  through a right angle gear box  420  and a belt drive  422 . Gas bottles  424  for welding shielding gas are also provided. A hydraulic system  428  belt-driven from the truck engine provides hydraulic power to operate the rail restraint  201  and weld containment device  290 . Various tools and devices to assist in alignment of the rail are also stored on board in tool case  432  and storage rack  434 . A drop-down tool shelf  436  allows for temporary storage of frequently used tools and supplies. 
     The cargo box is stabilized by use of external stabilizer legs  438  which are hydraulically operated to keep the cargo box from swaying and disrupting the robot orientation while welding. 
     The robot  408  is mounted to a horizontally moving machinery ways  426 , which acts to extend the robot from the interior of the truck to the welding position on the exterior. It will be seen that the robot, as is known to one in the robotics art, has a base  430  mounted to rotational bearing  432  which enables the robot to rotate around a rotational axis  434 . As is typical of robot devices, robot  408  has articulated arm  436  which is articulated to bearing  432  and base  430  having a series of joints  438  and, for this application, terminates in welder head  440 . While the robot  408  is typical in that it operates in three dimensions using controller  410 , the initial orientation of robot  408  provides a major departure from known art. Base  430  and in particular axis  434  are horizontal, rather than their heretofore known vertical orientation. This orientation provides considerable advantages in use in the field in a mobile, portable welding apparatus. Instead of a workpiece being brought to and located proximate a fixed robot, this apparatus brings the welder to the workpiece—in this case railroad rails  28 —and uses interfacing with rail restraint  201  to automatically weld the rails. The use of touch sensing plates  279  enables controller  410  to precisely align and operate the welder head  440  to form a precisely controlled and metallurgically sound weld on extremely long rails and in very tight spaces. The alignment of axis  434  coaxial with the longitudinal axis of the vehicle also provides benefits in retraction for protection and added mobility. 
     Thus the device may be moved to a safe position for transportation, and storage. It may also be extended for maintenance or for welding of the rails. The robot has sufficient operating area to reach both the right and left side rails in turn. Thus the robot can be readily and quickly stored or deployed for use. The robot receives its control power and ancillary service via a cable track  430 .