Case Studies / Part Transfer / Automotive Chassis Frame Assemblies

Motoman Robots Loading/UnloadingMotoman Robotics provided flexible robot system capable of handling all required chassis frame models and wheelbase lengths. Robot system meets line production rate of one chassis frame every 70 seconds. Robot gripper design prevents parts from dropping if air or power to cell is interrupted.

Project Challenges

  • System must provide flexibility to handle 10 models of pick-up truck chassis frame assemblies with three wheelbase lengths: 3,220 mm, 3,700 mm and 4,180 mm (126.8", 145.7" and 164.6"). Maximum chassis frame assembly weight is 290 kg (639.5 lbs).
  • System must be capable of meeting line production rate of one chassis frame every 70 seconds.
  • System must not drop parts if air or electrical power to cell is disrupted.

Motoman Robotics Solution

Motoman Robotics provided a custom UP400RN material handling system consisting of loading and unloading cells. Working together, two robots grasp individual chassis frames at opposite ends and use coordinated motion to load them from a frame fixture onto a hanging conveyor. Two additional robots unload individual frames from the hanging conveyor onto an exit conveyor. Total system includes:

  • (4) UP400RN robots with NX100 controllers in DR2C configuration. (Two robots per cell, each with an individual controller.)
  • (4) Custom end-of-arm tools – pneumatic grippers (two per cell).
  • (2) Hanger stabilizing stations (one per cell).
  • Frame fixture (load cell only). Pneumatic lift with fabricated sub-base mounts between infeed roller conveyors. Includes part-present and lift up/down sensors.
  • Exit conveyor (unload cell). Seven-meter overall length three-strand belt conveyor.
  • (2) Allen-Bradley ControlLogix PLCs (one per cell).
  • (2) DeviceNet PanelView Plus 1000 Operator Stations (one per cell).
  • (4) Fence-mounted operator control stations (two per cell).
  • Cell guarding package, including 3.1-m (10') high woven wire perimeter safety fence. Each cell has three light curtains, two area scanners, a three-color light beacon with audible alarm, and an access gate with dual-channel safety hardware and positive-break safety switches.

Fixtures/Tooling Details

Motoman Robotics provided four custom pneumatic grippers (one per robot), each including part present, gripper open/closed sensors. In the unload cell, two laser sensors on one robot and four laser sensors on the other are used to locate frames accurately (±1 mm/0.04") for pick-up. If air or power to cell is interrupted, a locking slide mechanism on the gripper prevents parts from being dropped. Motoman also provided two hanger stabilizing stations (one per cell). Each station uses 16 pneumatic cylinders and 32 sensors controlled by PLC to hold location accuracy of the hanger to ±3 mm (0.118"). Includes pneumatically actuated straightening device able to accommodate 15-degrees of hanger rotation and 5-degrees of hanger sway, mounted to a welded tubular cantilevered frame capable of supporting hanger assembly with two frames 5 degrees off center.

Ref: ACS-078