Motoman Robots Arc Welding and Handling Agricultural Equipment

Motoman HP200 with multi-function gripper transfers trunnions from rotary positioner and tubes from infeed device onto welding fixture mounted on heavy-duty headstock positioner. Motoman HP50 welds the parts, then HP200 robot unloads welded assemblies onto outfeed rack.

Summary

System exceeds requirements for quality improvement. System consistently holds run-out tolerances to 0.2 mm (0.008") on trunnions and 0.75 mm (0.030") on tubes, which is twice as good as goal of 0.4 mm (0.016") on trunnions and 1.5 mm (0.060") on tubes. Robotic solution achieves goal of significantly reducing rework and related direct labor costs. System meets requirement for ability to support approximately one hour of unattended production. System achieves adequate cycle time, which is expected to improve even more as customer implements additional tooling and part changes.

Project Challenges

Provide flexible system to weld and handle 12 different hay baler roll assemblies. These consist of tubes with trunnions on each end that are tack-welded in place, plug-welded and then final-welded.
Tubes are 1,170-1,556 mm (46.1"-61.3") L and have ODs ranging from approximately 88.9-168.3 mm (3.5"-6.6"). Final welded assemblies are 1,318-1,959 mm (51.9"- 77.1") L.
System must be designed to hold enough parts to support approximately one hour of unattended production.
Improve weld quality and reduce rework. Achieve run-out tolerance within 1.5 mm (0.060") for tubes and 0.4 mm (0.016") for trunnions.
Achieve cycle time of approximately 5-6 minutes per part.

Motoman Robotics Solution

Motoman Robotics provided a custom welding and handling solution, including:

Motoman HP50 (arc welding) robot with riser base.
Motoman HP200 (material handling) robot with riser base.
NX100 DR2C robot controller (for HP50 and HP200).
Miller 450-amp AutoAxcess® weld package, including interface, four-roll wire feeders and feed rolls, interconnecting cables and weld dress-out package.
Motoman Tough Gun® package with 500-amp air-cooled torch.
Motoman ComArc (80-V) touch-sense package with seam-tracking.
Reamer/sprayer nozzle cleaning station.
Custom end-of-arm tool – pneumatic multi-function mechanical gripper for HP200 robot.
Motoman MR-300 rotary positioner (for trunnion infeed) with 300 kg (661.5 lb) capacity per side and 4-second index. Includes two fixtures (one per side), each with 24-trunnion capacity.
Tube infeed/outfeed devices – gravity-fed infeed with singulator, and gravity outfeed chute, including three-level racks with rack-full sensors.
Laser sensor station. Laser sensor is used to determine the location of the welded trunnion shaft relative to disc.
Motoman MH-3000 headstock positioner with 3,000 kg (6,615 lb) rated headstock load; 6.7 rpm headstock speed; and 4.95-second 180-degree sweep.
Allen-Bradley SLC 5/05 PLC package with MotoHMI interface.
Cell guarding package that complies with ANSI/RIA-15.06-1999 safety standard. Includes perimeter safety fence with two access gates; arc flash curtains; safety laser scanner at trunnion infeed station; and 4-color status beacon with audible alarm.

Fixtures/Tooling Details

Motoman Robotics provided a custom pneumatic multi-function mechanical gripper for the HP200 robot that handles two trunnions and one tube/roll assembly of the required sizes. Gripper includes open/closed sensors, and laser sensor that searches for slots or holes in tubes and verifies length/diameter. Customer-provided pneumatically clamped mechanical slide welding fixture is mounted on heavy-duty MH-3000 positioner.