Case Studies / Arc Welding / Truss Fabrication Equipment


Challenges

  • Robotically weld large assembly and fabrication tables that are 4-m L x 2-m W and weigh approximately 2,450 kg, as well as subassemblies that weigh 181-227 kg each. Tables are mild steel 6-13 mm thick and each requires 660 single-pass welds, ranging from 25-152 mm long.
  • Improve safety and reduce high turnover due to manual welding in 100-degree plus heat during summertime.
  • Provide flexible welding system that can accommodate a wide variety of models and subassemblies, and has capability to perform 85% of welding on large tables.

Solution

Yaskawa Motoman provided two MotoSweep™ cells, each including:

  • Six-axis Motoman® "Expert Arc" robot with controller.
  • MotoSweep transport beam. Robot is invert-mounted from MotoSweepâ„¢ transport beam and controlled as an external axis.
  • Miller Auto-Axcess™ 450-Amp power source with air-cooled Motoman Tough Gun® torch. Robot welds using barrel-fed 0.035" steel wire with an 80/20 mix of Argon/CO2 shielding gas.
  • Automatic wire cutter, nozzle cleaner and sprayer, and torch realignment device.
  • Two stationary holding fixture tables, one per side of the robot cell.
  • Operator station on stand-alone pedestal. Functions include: Job Start, Emergency Stop, Hold, Alarm Reset, and Servo Power-up. Palm button for cycle start activation. Ready signal light and alarm indication light. Thumbwheel switch for program selection (up to 100 programmed jobs) and manual jog joystick.
  • Workcell protection package that meets ANSI/RIA R15.06-1999 safety standard, including safety fencing, light curtains, and safety-interlocked gates.

Fixtures/Tooling

Customer provided their own fixtures. Each MotoSweep cell has two stationary holding fixture tables, one per side. The robot can process the same type of parts on both sides or different parts can be run on opposite sides of the same robot cell. Parts are fixtured very tightly and concisely to ensure welded parts are square and flat.

Project Results

  • Highly flexible, extended-reach robot system meets or exceeds all project goals and objectives.
  • Conservatively speaking, robot system payback was less than six months.
  • Production capacity increased from 20-25 per month to 6-7 per day, enabling customer to bring out-sourced production of 40 units per month back in-house.
  • Flexible robots produce high-quality, consistent welds, significantly reducing scrap and rework.
  • Reliable robot system helped customer reduce lead time from 20-24 weeks to 16 weeks. Customer anticipates further lead time reduction to eight weeks.
Ref: ACS-083

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