Airbus UK expects to make greater use of automated drilling and machining following a research project to increase the accuracy and flexibility of standard automotive-industry robots. The first machines are entering use at the Airbus wing plant in Filton.
Aerospace has been forced to use expensive specialised automated drilling machines because standard industrial robots lack the accuracy required for aircraft assembly. Automotive robots are also designed to perform a single task thousands of times, whereas the lower production rates and longer cycle times for aircraft demand robots that can perform more than one function.
The process developed by Airbus UK working with industrial robot manufacturer Kuka UK and metrology integrator M³, uses Dassault Systemes' Delmia V5 software to program the robot offline, proves out the program using simulation, then monitors the robot's position online in real time to ensure accuracy.
The system enables multiple robots to work together to handle large aircraft parts by sharing the load, and allows the robots to be used for a range of tasks such as sealant application, fastening and machining, instead of standing idle between drilling operations because of the long cycle time between each shipset.
"Company-wide we drill around 50 million holes per year and half of these and manually processed. Our research is part of a drive to significantly reduce manual processing across current and future aircraft programmes as our build rate increases to meet market demand," says Mark Summers, engineering group leader, automation and robotics for Airbus UK.
"Standard industrial robots are not accurate enough for our process specifications, as absolute positional accuracy of ±0.2mm is required in many application areas," he says. Using integrated laser measurement systems, the robot continuously checks and adjusts its real-world position by dynamically referencing the master computer-aided design database.
The majority of automotive robots in use today are programmed online, the operator "teaching" the machine its task inside the production workcell. This takes the robot out of operation for several days. The Airbus process uses Delmia V5 Robotics software to program the robot offline, to ensure accuracy. The program is then proved out using a simulation of the robot in a graphical environment provided by Delmia. This allows the programmer to detect any clashes and determine cycle before the program is downloaded to robot.
"This is the most sophisticated combination of offline programming ever attempted," says Delmia robotics export Stefan Filpe, because the system manages co-operating robots - one holding the part while the others work on it. "In the aerospace sector, the loads we are asking the robots to bear are too great for single robots. Load sharing is therefore absolutely fundamental," says Kuka UK's Brett Green
Because the robot is continuously measuring its position relative to the target part, the development team says, it can make accurate allowances for deflections of the component caused by temperature fluctuations. The integrated metrology also allows the robot to be used as an online digital measuring machine, certifying jigs and parts in real time and avoiding need for subsequent quality-assurance checks on parts or to take jigs out of production at regular intervals for recertification.
Source: Flight International