Motoman Robots Arc Welding Frames for Sectional Snowplows

Two Motoman HP50-20 robots weld snow plow frames located on two headstock/tailstock positioners with manually adjusting head- and tailstocks to accommodate part length variations and facilitate programming.

Summary

Robotic welding system accommodates wide range of sizes, including 8', 10', 12', and 14' L frames for light-duty snow plows and 12', 14', 16', 19' and 22' L frames for heavy-duty models. Robots surpass goal of producing 10 frames per 10-hour shift. Cell welds 12' frames in 42-45 minutes (25-30% faster than requirement), with similar stellar results for other frame sizes. Flexible cell design accommodates wide range of frame sizes, but keeps centerline of parts consistent, which facilitates programming by allowing points to be taught on one side of the positioner and then shifted to the other side. Robot solution provides consistent high-quality welding, which improves frame fit-up and aesthetics.

Project Challenges

Provide robotic system capable of producing approximately 10 snow plow frames per 10-hour shift. Manual process can produce approximately three frames per day.
Frames for light-duty plows are available in 8', 10', 12', and 14' lengths and frames for heavy-duty plows come in 12', 14', 16', 19' and 22' lengths.
Frames are made of A36 mild steel and require approximately 175-200 welds each. Most are single pass welds approximately 101.6-127 mm (4-5" L); some require two passes and/or weaving.
Improve productivity, while also increasing weld quality and consistency.

Motoman Robotics Solution

(2) Motoman HP50-20 robots with:
- (1) NX100 DR2C robot controller -- dual robot controllers interfaced with one programming pendant
- (2) Robot base risers
(2) Miller Auto-Axcess® weld packages – 450 Amp, water-cooled
ComArc 200V high-speed touch sensing – dual robot package
(2) Motoman Tough Gun® torch packages
(2) Reamer/sprayer nozzle cleaning stations with wire cutters.
(2) Motoman MHT-1600 headstock/tailstock positioners – AC servo-controlled with 3,000 kg (6,615.0-lb rated load, 3.28-sec 180-degree sweep; 10.6 rpm headstock speed; and 95 mm (3.7") off center of gravity at rated load.
(4) Mobile headstock and tailstock sub-bases – one pair with manual adjustment for part length variations from 8'-19' and a second pair for part length variations from 8'-22'.
Custom fixture package.
(2) Operator stations on stand-alone pedestals (one primary, one secondary).
Common equipment base for robot controller, and welding power supplies and disconnects.
Cell guarding that meets ANSI/RIA 15.06-1999 safety standard, including 2.4-m (8') safety fence, one personnel gate, four sliding doors (two at each positioner load/unload station), arc flash protection curtains, and a three-color status beacon.

Fixtures/Tooling Details

Motoman Robotics provided two sets of fixture receivers per headstock/ tailstock positioner (a total of four bolt-on fixture adapters). Each positioner has one set for light-duty frames and another for heavy-duty frames. The operator bolts fixture adapters to parts off-line and uses an overhead crane to lift them into the headstock/tailstock fixture receivers.