Case Studies / Arc Welding / Heavy Equipment Subassemblies

Motoman robot arc weldingFlexible system meets customer’s requirements for welding cycle times and 45-second part exchange. System is capable of welding all required part numbers. Automatically adjustable fixtures and retractable end stops accommodate all required part sizes.

Project Challenges

  • Weld pre-tacked heavy equipment subassemblies, with a length range of 1,365-3,410 mm (53.7-134.3"), a rail centerline width range of 394-720 mm (15.5-28.3"), and a height of approximately 571 mm (22.5"). Heaviest part weighs 595 kg (1,312 lbs).
  • Provide flexible robotic system with fixtures that can accommodate more than 300 part numbers.
  • System will make approximately 12-20 welds of varying lengths per part (single-pass and multi-pass, heavy-deposition welds).
  • Customer is responsible for robot programming and all welding cycle times. Approximate cycle time for welding is 2-4 minutes per part, depending on model. Part exchange time must not exceed 45 seconds.

Motoman Robotics Solution

Motoman Robotics provided a custom welding system consisting of two identical cells with shared mezzanine and HMI. Total system includes:

  • Six EA1900N “Expert Arc” welding robots (three per cell: one set of two robots with NX100 controllers in dual-robot/single-controller configuration and one robot with individual NX100 controller per cell).
  • Overhead mounting structure for six invert-mounted robots. Elevation 3,530 mm (139").
  • Mezzanine for robot controllers, power supplies, bulk welding wire spools, and PLC enclosure with main deck the size of the span between the robot structures.
  • Integration of Customer supplied welding packages.
  • Six 400-Amp air-cooled GMAW torches (three per cell).
  • Six Motoman ComArc Seam-Tracking packages with TS-2 200V high-speed Touch-Sensing (three per cell).
  • Two custom headstock/tailstock positioners (one per cell). Load height designed to match existing conveyor system. Includes 1,296 mm (51") dia. thru-hole for part passage. Positioner servo motors controlled by robot controller. Max. rotational speed of 90-degrees per second (15 rpm). Includes 6,082 mm (19.95') L integral conveyor with variable feed drive.
  • Omrom CS-1 programmable controller package.
  • MotoHMI interface.
  • Custom hydraulic fixture package.
  • Two exit conveyors (one per cell). Conveyors are 3,657.6 mm (12') L, 1,066.8 mm (42") W, chain-driven live roller type.
  • Cell guarding package, including aluminum extrusion 8.2' H posts with amber acrylic panels; roll-up barrier doors at HS/TS access points (two per cell); safety interlocked gates (two per cell), and two remote E-stop stations (one at part exit end of each cell).

Fixtures/Tooling Details

Motoman Robotics provided two sets of custom fixtures – one per cell. Fixtures adjust automatically to handle various part sizes. Two or three hydraulic clamps engage to hold each part, depending on part size. Fixtures also include retractable end stops, and powered rollers with variable feed drive to assist with loading and unloading. Fixtures allow part to be captured and rotated 180º to permit robots to access welds on bottom of parts.

Ref: ACS-076

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