Aircraft manufacturers continue to devise new ways to reduce manual labor, turning to robots for repetitive jobs such as drilling holes. Research projects are helping improve precision so robots can be used for even the most demanding applications.
Variation Reduction Solutions Inc. is spearheading a project to develop a vision-guided robotic drilling system that will automatically drill several thousand precision holes in the center fuselage of the Lockheed Martin F-35 Joint Strike Fighter (JSF). It is funded by the Air Force Research Lab and the U.S. Department of Defense Joint Program Offices. Once the initial machines are put in use by JSF team member Northrop Grumman, they will be redesigned for a broader market.
“Commercialization is absolutely our goal,” said Don Manfredi, COO at VRSI. “Robotic drilling is a hot application right now, but it’s not being done to this level of accuracy in production.”
VRSI’s project is yet another program that is helping bring automotive-industry techniques to aircraft manufacturing. “Three years ago, 100% of our business was in automotive,” Manfredi said.
The Robotic Applied Drilling System being developed by VRSI will replace the huge gantry systems now used to drill holes into the fuselage components. That can slow production when the sequential production flow is altered.
Today, the flow is interrupted when assemblies must be moved to the immobile gantry for precision drilling. When the holes are finished, the part can then be returned to the next step of the assembly process.
“We can put our robotic cell in line with everything else so you go from operation one to operation two, then three, and so on,” Manfredi said. In this application, up to four robots will comprise a cell. The new center fuselage project requires the drilling of approximately 4000 holes per side through various stack-ups of composite and metal. Hole diameters range from 0.190 to 0.250 in.
One version of the VRSI system will use commercial-off-the-shelf robots that are upgraded with options provided by various robot manufacturers. The more precise version requires extra positioning equipment.
“We’re looking at true position tolerances of 0.010 and 0.020 in. We can do modifications to get to TP (true position) 20 unguided. To go from TP 20 to TP 10, we have to guide the drill head with a laser tracker,” Manfredi said.
VRSI is using Faro Technologies’ laser trackers to guide the drill heads. Faro lasers are also being used in a related F-35 program funded by a Small Business Innovation Research grant. The goal in this project is to devise a robot that will drill holes needed to attach inlet ducts to the fuselage. Each duct has a length of about 9 ft, yet an internal diameter of only 20 in.
Currently, workers squeeze into the ducts to manually drill and countersink 800 holes per duct. Using robots should significantly shorten drilling time. Dassault Systèmes software tools are being used to design the inlet duct drilling system.