Abstract:
A multi-station, gantry-based automated welding system includes a gantry mounting robotic arc welders or other equipment. The gantry has a range of travel over multiple workstations, each workstation being adapted for rotatably mounting a respective workpiece. A control system controls and coordinates the movements and operation of the gantry, the robotic arc welders and the workpiece-rotating motors located at the workstations. Encoders are installed at the moving elements of the system for precisely tracking and providing output to the computer controller. Primary and secondary power/data distribution systems include cable and hose carriers for providing mobile power/data connections to the gantry and also to the robotic arc welders mounted thereon. The power/data distribution systems are elevated above a facility floor to avoid interfering with equipment, personnel and activities at floor level.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to automated welding, and in particular to a multi-station, gantry-based system for positioning and controlling robotic-arm welders for automatically welding rotatably-mounted workpieces. 
     2. Description of the Related Art 
     Automated or “robotic” manufacturing commonly involves computerized operation, control and positioning of tooling, equipment and workpieces. Robotic manufacturing has many advantages, including precision, repeatability, safety, efficiency and cost. Moreover, automated manufacturing facilities can operate continuously with relatively little downtime. Labor can be used efficiently by preprogramming the automated equipment for tasks which might otherwise be done manually. Workers are thus not exposed to dangerous, repetitive tasks and various hazards. 
     Robotic welders are an example of high-precision, computer-controlled automated manufacturing equipment. They are commonly used on assembly lines for a wide variety of products fabricated from metal. Vehicles and other products can be robotically welded to relatively tight tolerances. Robotic weldments are typically relatively uniform in strength and appearance, thus contributing to high quality finished goods. 
     Automated production often involves precisely and simultaneously coordinating movements of tooling and workpieces. For example, assembly line production generally involves moving workpieces from station-to-station where different operations are performed. Such assembly line tasks commonly include welding procedures, which can be done manually by welders or automatically by robots. Robotic arms with multiple articulated members can be preprogrammed to accomplish many of the tasks previously done by hand, and often achieve greater uniformity and precision. With precise control, the robotic arms can maneuver inside assemblies through multiple pivotal axes of movement. The computerized control system can precisely monitor and control attitudes and positions in three dimensions. The workpieces themselves can also be manipulated and synchronized with the welding equipment movements. For example, the workpieces can be turned as necessary to enable welding through 360° around joints. Both workpieces and welders can be simultaneously moved through three dimensions for optimal positioning and access. Relatively complex weldments can thus be achieved by preprogramming the equipment. 
     Movable gantries are commonly used in manufacturing for positioning manufacturing equipment relative to workpieces. For example, a computer control system can be preprogrammed to precisely place a gantry and the tooling mounted thereon over a workstation containing a workpiece. Upon completing a preprogrammed task, the gantry can automatically relocate to another workstation and workpiece. Alternatively, factory production workstations can include equipment for repositioning the workpieces. For example, workpieces can be rotatably mounted in workstations for access by tooling, including welding and painting equipment. 
     Gantry-based systems can be configured with elevated tooling and equipment. Such an arrangement has the advantage of locating tooling and equipment overhead, thus leaving factory floors free for workstation placement. Mobile gantries and equipment normally require power and utility lines which are configured for accommodating movements. 
     The multi-station, gantry-based welding system of the present invention facilitates performing multiple manufacturing operations precisely and simultaneously. Multiple workstations can be serviced by a single gantry configured for movement from station-to-station. The system of the present invention is configured for overhead placement of the power and utility lines, thus leaving the factory floor space below open for other uses. Locating the power and utility lines overhead tends to increase safety because they are less likely to be engaged by workers and equipment moving about the factory floor. Moreover, greater gantry mobility can be achieved by running the power and utility lines overhead because the elevated areas in factories tend to be more open than the factory floors. Space on factory floors is often at a premium with personnel, materials, equipment, forklifts, etc. in motion at floor levels. 
     The workstations movably mount respective workpieces, which are synchronized with gantry movements and also with robotic welding arms movably mounted on the gantries. Such simultaneous workpiece, gantry and equipment movements can be coordinated to consistently produce finished products, which can include complex shapes and component assemblies. By synchronizing the workpiece, gantry and equipment movements, such procedures can be accomplished from virtually unlimited relative orientations and positions of the moving parts of the system. A wide variety of finished products can be produced using a variety of procedures. 
     Heretofore there has not been available a multi-station, gantry-mounted welding system with the advantages and features of the present invention. In addition to robotic arm welding systems, other tooling and equipment can likewise be movably mounted on a gantry for movement relative to the workstations wherein the movable workpieces are located. 
     SUMMARY OF THE INVENTION 
     In the practice of the present invention, a multi-station, gantry-based welding system with overhead power and utility lines is provided. Multiple workstations are provided on a factory floor in alignment with a gantry path-of-movement. Each workstation rotatably mounts a workpiece under computer control for synchronizing with the movements of the gantry and the robotic-arm welding equipment mounted thereon. Power and utility lines are located in flexible, linked-section cable and hose carriers, which extend parallel to the path-of-movement of the gantry and maintain power and utility connections with the gantry throughout its range of movement. Cable and hose carriers are also installed on the gantry for providing power to the welding equipment throughout its range of movement. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawings constitute a part of this specification and include exemplary embodiments of the disclosed subject matter illustrating various objects and features thereof, wherein like references are generally numbered alike in the several views. 
         FIG. 1  is a perspective view of a gantry-based welding system including three workstations each rotatably mounting a weldment workpiece comprising a frame. 
         FIG. 2  is an enlarged, perspective view of a gantry, particularly showing a power distribution system therefor. 
         FIG. 3  is an enlarged, perspective view of the gantry with portions broken away to show a pair of robotic arm welders each mounted on a respective side of the gantry. 
         FIG. 4  is an enlarged, fragmentary view of the connection of the power distribution system with a respective robotic arm welding subsystem taken generally within Circle  4  in  FIG. 2 . 
         FIG. 5  is an enlarged, fragmentary view of the robotic arm welding subsystem. 
         FIG. 6  is an enlarged, fragmentary view of the robotic arm welding subsystem taken generally within Circle  6  in  FIG. 3 . 
         FIG. 7  is an enlarged, fragmentary view of an upper end of the gantry, particularly showing a power distribution system with a flexible cable and hose carrier connection with the gantry. 
         FIG. 8  is an enlarged, fragmentary view of the flexible cable and hose carrier, taken generally within Circle  8  in  FIG. 7 . 
         FIG. 9  is an enlarged, fragmentary view of a lower end of the gantry, particularly showing a guide wheel thereof on a guide track and an encoder adapted for tracking movement of the gantry. 
         FIG. 10  is a schematic diagram of a computerized control system for the system of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     I. Introduction and Environment 
     As required, detailed aspects of the present invention are disclosed herein; however, it is to be understood that the disclosed aspects are merely exemplary of the invention, which may be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art how to variously employ the present invention in virtually any appropriately detailed structure. 
     Certain terminology will be used in the following description for convenience in reference only and will not be limiting. For example, up, down, front, back, right and left refer to the invention as oriented in the view being referred to. The words “inwardly” and “outwardly” refer to directions toward and away from, respectively, the geometric center of the embodiment being described and designated parts thereof. Forwardly and rearwardly are generally in reference to the direction of travel, if appropriate. Said terminology will include the words specifically mentioned, derivatives thereof and words of similar meaning. 
     Referring to the drawings in more detail, the reference numeral  2  generally refers to a welding system with multiple welding stations  4  and a gantry  6  mounting a pair of robotic arm welders  7 . The system  2  also includes a power/data distribution subsystem  8  and a control subsystem  10 . 
     II. Workstations  4  and Workpieces  16   
     As shown in  FIG. 1 , three workstations  4  are generally located at respective recesses  12  formed in a factory floor  14 . Each workstation  4  receives a respective workpiece  16  rotatably mounted on first and second rotary mounts  18   a,b , at least one of which is powered by a motor  116  and includes an encoder  118  connected to the control system  10  for precisely rotating a respective workpiece  16 . Various workpieces  16  can be accommodated by the system  2 , which can be configured to perform a wide variety of procedures. For example and without limitation, the workpieces  16  shown in  FIG. 1  comprise frame assemblies with multiple steel members, such as tubular steel sections. Without limitation, the system  2  can be configured for welding the frame assemblies  16  together. Thus, the frame assemblies  16  could be tack-welded together temporarily for mounting in the workstations  4 . Alternatively, suitable jigs could be used at the workstations  4  for mounting the components of the frame assemblies  16  during welding. Precisely rotating the frame assemblies  16  during the welding operations enables the welders  7  to access the welded joints from all sides for maximum-strength weldments. Although a welding system  2  is shown and described as an example, other aspects of the present invention can perform other operations involving a wide variety of tooling and equipment acting on various workpieces. Additional examples include cutting, shaping, finishing, treating, assembling, inspecting and testing operations and procedures. Still further, the system  2  can be operated remotely, thus accommodating harsh environments and avoiding safety hazards associated with various operations and procedures. In other words, the system  2  can minimize operator risks associated with otherwise hazardous procedures because there is no need for operators in close proximity to the equipment and workpieces. Moreover, automating the operations performed by the system  2  tends to reduce operator risk because the robots and the material handling equipment can perform tasks which were previously done manually. 
     III. Gantry  6   
     The gantry  6  generally comprises a pair of end subframes  20   a,b  with a raised platform  22  extending therebetween. Each end subframe  20   a,b  includes a pair of columns  24  mounting a channel-shaped lower crosspiece  26  with a pair of guide wheels  27  guiding the gantry  6  along a respective gantry guide rail  28 . As shown in  FIG. 1 , a pair of guide rails  28  extends along either side of the line of welding stations  4 . A gantry encoder  29  is mounted on the lower crosspiece  26  and includes a tracking roller  31  engaging and an encoder track  32 . The gantry encoder  29  provides output signals indicating the precise position of the gantry  6  along the guide rails  28 . 
     Each end subframe  20   a,b  also includes an upper crosspiece  30  connected to the platform  22 . The platform  22  includes upper and lower decks  23 ,  25 . The gantry  6  preferably comprises a relatively rigid structural assembly adapted for moving precisely along the guide rails  28  with the end subframes  20  maintaining parallel orientations on opposite sides of the workstation area. A drive mechanism  34  is mounted on a respective lower crosspiece  26  and is adapted for precisely driving the gantry  6  along the guide rails  28 . 
     IV. Welders  7   
     Without limitation on the generality of useful equipment adapted for mounting on the gantry  6 , the welders  7  can comprise Motoman arc welding robots, which are available from Yaskawa America, Inc. (www.motoman.com). Each welder  7  is movably mounted on a pair of robot guide tracks  36  located on the underside of the platform  22  and is adapted for traveling most of the length of the gantry  6  adjacent and parallel to a respective side of the gantry platform  22 . As shown in  FIGS. 5 and 6 , each welder includes a base  38  slidably, movably mounted on the welder guide tracks  36  and a welding wire drum  40  located on an outboard, extending end of the base  38 . Welding wire  42  is automatically fed to the robot welders  7  from the drums  38  and passes over welding wire rollers  44 . 
     Each welder  7  includes a rotatable hub  46  mounted on the underside of the base  38  and adapted for rotation about a vertical rotational axis. An articulated arm  48  is pivotally connected to the hub  46  and includes proximal and distal arm sections  50   a,b . The distal arm sections  50   b  mount rotating welding heads  52 , from which the welding wire  42  extends for engaging the workpieces  16  in welding operations. The welders  7  are preferably fully-articulated and precisely controlled by the computer control system  10 . Although arc welders are shown, the system  2  could include other types of welders and equipment within the scope of the present invention. 
     Each welder base  38  mounts a welder position encoder  54  adapted for precisely locating the welder base  38  along the welder guide rails  36 . Each encoder  54  includes a tracking roller  56  engaging a welder encoder track  58  whereby relatively precise positioning of the welder  7  along the gantry  6  can be determined, which information is provided as input to the control system  10 . Likewise, the precise position and orientation of the welding head  52  can be tracked and input to the control system  10  for precisely controlling the welding head  52  relative to a workpiece  16 . Movement arrows  60  indicate rotational and linear movement of the various components of the system  2 . For example, the arrows  60  in  FIG. 6  indicate the movements of various components of a welder  7 . 
     V. Power/Data Distribution System  8   
     The power/data distribution system  8  distributes electrical and other power to the gantry  6  for further distribution to the welders  7 . Although electrical power can be used exclusively for the system  2 , it will be appreciated that other types of service, power and utilities, such as gas, water, compressed air, hydraulic power, etc. can be distributed throughout the system  2 . For example, acetylene torch welders could be used in lieu of the arc welders  7 . A utility source, such as an electrical power panel in a facility, is connected to a primary mobile distribution  62  consisting of a flexible cable and hose carrier  64 , which is preferably placed overhead at approximately the level of the gantry platform  22  generally in a primary carrier channel  66 , which extends along one side of the recessed welding stations  4 . The channel  66  can be supported by suitable structural supports  68 , which can include freestanding columns  70  with extensions  72  extending laterally therefrom towards the workstations  4 . Alternatively, the channel  66  can be suspended from overhead ceiling structure or structurally connected to the walls of the facility, which commonly include columns or structural walls to which the extensions  72  can be mounted. 
     The primary carrier  64  can comprise a Gortrac® Nylatrac™ KS Series cable and hose carrier, which is available from cableorganizer.com (www.cableorganizer.com). The primary carrier  64  receives multiple cables and hoses  74 , which can comprise electrical, data, pneumatic, hydraulic and other utility lines. The carrier  64  is adapted for flexing and doubling back on itself as the gantry  6  moves, as shown in  FIGS. 1 ,  7  and  8 , while maintaining the lines  74  in generally parallel relation, thus avoiding kinks and other potentially damaging situations. As shown in  FIG. 7 , a guide panel  76  extends outwardly from a gantry end subframe  20  and is connected to opposed ends  75  of the cable/hose carrier  64 . The cables and lines  74  extend from the carrier ends  75  and turn at approximately 90° angles towards the gantry  6  and can be routed to suitable power distribution and control boxes  78 . In operation, the primary carrier  64  maintains the cables and data lines  74  in continuous contact with the moving gantry  6  throughout its range of motion. 
     A secondary mobile distribution  82  distributes power and data signals to the welders  7  on board the gantry  6 . A pair of cable and hose carriers  84  are mounted along each side of the gantry  6  and receive the cables and lines  74  from the primary mobile distribution  62  ( FIG. 2 ). Each carrier  84  includes a first or input end  86  connected to and receiving power/data input from the primary mobile distribution  62 , and further includes a second or output end  88  mounted on a welder cable and hose panel  90 . At the welder cable and hose panels  90 , the cables and lines  74  turn approximately 90° and are connected to the components of the welders  7 . Rollers  92  are mounted on the platform upper deck  23  for supporting the secondary carriers  84  as they move with the welders  7 . For example and without limitation, electrical power, data cables, welding gases, pneumatic power, hydraulic power and other utilities can be connected to the welders  7  via the cables and lines  74 . 
     VI. Control System  10   
       FIG. 10  shows an example of a control system  10  for the system  2 , which generally includes a master controller  102 , a workstation/workpiece controller  104  for the workstations  4  and a gantry/welder controller  106 . The master controller  102  includes an interface  110 , which is adapted for interfacing with a network such as a local area network (LAN) or a wide area network (WAN). The interface  110  can use any suitable data link including telecommunications lines or a wireless interconnection, e.g., an RF transceiver. The interface  110  can also link to the Internet (World Wide Web). 
     The system  2  can thus be configured for operating in conjunction with other resources in a manufacturing facility or even a global operation. For example, automated manufacturing instructions and information can originate from remote locations for implementing by the system  2  located at a manufacturing facility. In an automated operation, the gantry-mounted welding system  2  can interface with other manufacturing operations, such as material forming, finishing and testing. For example, the workpieces  16  can comprise frames for agricultural implements, which are welded together by the system  2 . Other manufacturing operations for the implements could be performed by systems similar to the gantry-mounted system  2 , whereby the frames  16  and other implement components could be automatically transported from system-to-system for final assembly with other automated equipment. The gantry-mounted system  2  is scalable whereby additional workstations  4  and gantries  6  can be added as needed. Moreover, each gantry  6  can mount different combinations of equipment appropriate for the operations being performed. Still further, the system  2  can be programmed for manufacturing customized workpieces, as well as repetitive, standardized production. 
     A computer  112  is connected to the interface  110  and is adapted to receive workpiece designs  114  in suitable digital formats, such as CAD/CAM files corresponding to a wide variety of components. The computer  112  can comprise a standalone unit or a terminal comprising part of a network. Preferably the computer  112  is programmable for controlling the operations of the system  2 , including positioning the workpieces  16 , the gantries  6  and the welders  7 , as well as other aspects of the operation. 
     The workstation/workpiece controller  104  includes motors  116  in the workpiece rotary mounts  18   a  for rotating the workpieces  16  and encoders  118  for precisely measuring the workpiece  16  rotary movements and providing corresponding output to the computer  112 . 
     The gantry/welder controller  106  controls power/data distribution  120 , positioning motors  122  and a position-responsive encoder  29  mounted on the gantry  6 . The automated welders  7  can include welder controls  126 , motors  128  and encoders  54  precisely controlling and positioning the automated welding operations. 
     It is to be understood that while certain aspects of the disclosed subject matter have been shown and described, the disclosed subject matter is not limited thereto and encompasses various other embodiments and aspects.