Page 36 - MetalForming March 2015

Robotic Welding
Resistance Welding
of Hot-Stamped Bumpers
Most recently, Wellington commis- sioned, in mid-2014, a five-robot assem- bly cell for robotic welding of bumper assemblies. Assemblies include a large hot-stamped, hat-shaped, aluminized (40 g) boron-steel bumper beam and a host of welded attachments—backing plate, brackets, nuts, etc. A lineup of nine manual pedestal resistance-welding machines feeds subassemblies into the huge ABB robotic-welding cell where five robots toil—two welding robots and three that serve as material handlers.
At the entry end of the robotic-welding cell, a turntable positioner indexes 180 deg. to swing the fixtured components within reach of a pair of spot-welding robots. These perform what amount to tack welds to hold the parts within their tight dimensional tolerances for the remaining dozens of spot welds made throughout the cell. Following this quick blast of resistance tack welds, the assem- blies move to idle stations where materi-
al-handling robots swing in, pick up the subassemblies and move them through a series of stationary weld stations. This finely tuned ballet of robotic motion yields completed bumpers at a rate of more than 100/hr.
Specified equipment for the newest of Wellington’s robotic-welding cells: ABB newest models of large robots, IRB 6700 models rated to 235-kg max- imum payload and boasting a reach of 2.65 m. ABB describes the seventh- generation robots as offering a 15-per- cent decrease in power consumption compared to previous models, along with a 20-percent reduction in total cost of ownership, double the time between service intervals and an aver- age increase in speed/shortened cycle times of 5 percent.
“When we put the cell in, it immedi- ately went into production,” says Richards. “We had zero learning curve, and thanks to ABB’s offline process simulation we immediately took off Aat 60 completed assemblies/hr. Within a few weeks, by
further optimizing robot motion paths and speed/acceleration parameters, we ramped up to 100/hr., or more.”
Advanced Robotics Technology Pays Off
Contributing mightily to this dra- matic productivity gain is the integra- tion, via the ABB robotic controls, amongst the robots, weld stations and positioner. “There’s a great deal of inte- gration and electronic communication throughout the cell,” Richards says, “that allow the robots to work extreme- ly close to one another, and to move in and around and the cell with minimal hesitation or distance between cell components. This lets us confidently and safely run the robots more quick- ly and without hesitation.”
Part of the success of this safe yet speedy cell operation must be due to a couple of key features inherent to the robot controller (ABB’s IRC5): Quick- Move and SafeMove. The QuickMove feature optimizes motion control based
34 MetalForming/March 2015
www.metalformingmagazine.com
UNCOIL
THE POWER.
We specialize in:
Strip Connector Alloys, Copper, Brass, Phosphor Bronze, Beryllium Copper, Stainless Steel, and Aluminum Strip
Thin gauges and narrow widths delivered within hours if needed!
Services Available:
Precision Slitting • Tension Leveling Traverse Winding • Pre coating: tin, nickel, or precious • Logistics & Border Crossing
ABC Metals, Inc.
Logansport, IN • Pharr, TX • El Paso, TX 800.238.8470 • fax 547.753.6110 • abcmetals.com