Welding with robots
The controller in Ben Bedard’s hands looks like anything but a welding tool. But today, that’s exactly what it is.
On the right, there’s a thumb stick that can control the robotic arm in front of him. On the left, a screen displays the programming code the robot is following. And at the moment, that code is telling it to glide over a thin, curved structure, and apply heat that will cause its pieces to join together.
Someday that robot will be able to weld on its own, but for now it runs in manual mode, using a process invented by Bedard and his teammates Wenping Zhao and John Gangloff to help factories produce aircraft parts quickly with thermoplastic composites – light, durable and recyclable synthetic materials that can be melted and solidified multiple times without degradation.
Aircraft manufacturers want to use those materials to make next generation aircraft lighter, more fuel efficient and more sustainable. Meeting that demand requires faster methods of production.
“This robotic automation will enable a solution to rapidly manufacture materials to provide high quality, lightweight parts for the aircraft industry,” Zhao said.
Collins Aerospace, an RTX business, estimates thermoplastics can reduce the weight of aircraft structures by 20 to 50 percent when they replace metals and thermosets, a less flexible type of material that cannot be welded. The company produces more than 2,000 thermoplastic parts for fuselages, doors, wings and flight control surfaces, but with automated welding processes, it could produce larger, more complex structures.
“Using mechanical fasteners to join aircraft assemblies usually takes hundreds of fasteners – it’s time consuming. It’s higher weight,” Zhao said. “However, this technology will require no fasteners. We just weld the parts directly to each other, creating a lightweight solution.”
The system can be tailored to a manufacturing facility’s specific needs, the robot has multiple joints for a wide range of motion, and it can reliably repeat its process for quality control.
“We’re able to leverage the flexibility of the robot to reach into geometries or exert forces where a human operator may not have been able to, or even to run the welding processes to exert heat that a human operator wouldn’t necessarily be able to tolerate,” Bedard said. “The robotic arm gives us a lot of flexibility to deal with whatever the business units ask us to work on.”
In Bedard’s test, he programmed the robot to weld a piece that simulates a fan cowl, a curved covering for an aircraft engine. Fan cowls today work a little like a camping tent, with a frame that supports the outer layer. But with a rapidly welded thermoplastic fan cowl, the team joins the outer layer, frame and connectors to reduce weight and assembly time. Ordinarily, creating one would require a large, energy-intensive and costly autoclave process, but the robotic welder bypasses those problems.
“We’re thinking it’s going to streamline the logistics of these panels. If we can reduce it from a singular piece that is challenging to move around into a bunch of disparate pieces that can be joined through a series of joining processes, we can streamline that process quite a lot,” Bedard said. “I think that’ll increase the viability of thermoplastics in areas where they might not have been used previously.”
Research was sponsored by the ARM (Advanced Robotics for Manufacturing) Institute through a grant from the Office of the Secretary of Defense and was accomplished under Agreement Number W911NF-77- 3-0004. The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the official policies, either expressed or implied, of the Office of the Secretary of Defense or the U.S. Government. The U.S. Government is authorized to reproduce and distribute reprints for Government purposes notwithstanding any copyright notation herein.