Over 1,200 large diameter holes must be drilled into the sideof-body join on a Boeing commercial aircraft's fuselage. The material stack-ups are multiple layers of primarily titanium and CFRP. Due to assembly constraints, the holes must be drilled for one-up-assembly (no disassembly for deburr). In order to improve productivity, reduce manual drilling processes and improve first-time hole quality, Boeing set out to automate the drilling process in their Side-of-Body join cell. Implementing an automated solution into existing assembly lines was complicated by the location of the target area, which is over 15 feet (4 meters) above the factory floor. The Side-of-Body Drilling machines (Figure 1) are capable of locating, drilling, measuring and fastening holes with less than 14 seconds devoted to non-drilling operations. Drilling capabilities provided for holes up to ¾" in diameter through stacks over 4.5" thick in a titanium/CFRP environment. Using high precision servo control, each layer could be customized with specific drill parameters optimized to improve hole quality and decrease drill cycle time. Drill life was improved by tracking depth drilled for each drill bit. The drilling process is stabilized by rigid support structure which is optimized for both stiffness and natural frequency resulting in deflections no greater than 0.020 inches. Each drilling machine is lightweight and mobile to accommodate multiple work zones in multiple assembly lines. One-up assembly was achieved by using custom doweling/clamping fasteners automatically installed by the machine in strategic locations to provide the proper part clamping.
<div class="section abstract"><div class="htmlview paragraph">Automated fiber placement of pre-impregnated (pre-preg), thermoset carbon materials has been industrialized for decades whereas dry-fiber carbon materials have only been produced at relatively low rates or volumes for large aerospace structures. This paper explores the differences found when processing dry-fiber, thermoset, carbon materials (DFP) as compared to processing pre-preg, thermoset materials with Automated Fiber Placement (AFP) equipment at high rates. Changes to the equipment are required when converting from pre-preg to dry fiber material processing. Specifically, the heating systems, head controls, and tow tension control all must be enhanced when transitioning to DFP processes. Although these new enhancements also require changes in safety measures, the changes are relatively small for high performance systems.</div><div class="htmlview paragraph">Processing dry fiber material requires a higher level of heating, tension control and added safety measures. However, once these are achieved, processing rates and reliability may be significantly improved for DFP versus traditional pre-preg AFP processing. Overall payout speeds as well as steering speeds can be increased for dry fiber resulting in increased laydown rates when using current AFP processing techniques. The lack of resin within the material greatly reduces resin build-up, which supports longer maintenance intervals and greater reliability by minimizing or eliminating the problems associated with resin build-up. The controlled emission area and fast response time of precision heating systems greatly reduce unwanted heat on surrounding areas and increase process performance. In addition to DFP, further developments in the heating system have also proved beneficial for thermoset as well as thermoplastic processing. All of these advantages increase the machine utilization as well as reliability when processing aerospace parts made from dry fiber materials with AFP equipment.</div></div>
British Aerospace, Airbus Ltd., Chester, UK manufactures the main wing box assembly for all current Airbus programs. Titanium interference fasteners are used in large numbers throughout these aircraft structures. On the lower wing skin of the A320 alone there are approximately 11,000 of this fastener type. Currently, the majority of these fasteners are manually installed using pneumatic or hydraulic tooling. British Aerospace engineers recognized the significant potential which automation offers to reduce these current labor intensive installation methods. Electroimpact proposed extending Low Voltage Electromagnetic Riveter (LVER) technology to the automatic installation of these interference fasteners as well as rivets. Close liaison between Airbus and Electroimpact engineers resulted in the development of an automated LVER based lockbolt installation system, which is currently undergoing evaluation.
Developing the most advanced wing panel assembly line for very high production rates required an innovative and integrated solution, relying on the latest technologies in the industry. Looking back at over five decades of commercial aircraft assembly, a clear and singular vision of a fully integrated solution was defined for the new panel production line. The execution was to be focused on co-developing the automation, tooling, material handling and facilities while limiting the number of parties involved. Using the latest technologies in all these areas also required a development plan, which included pre-qualification at all stages of the system development. Planning this large scale project included goals not only for the final solution but for the development and implementation stages as well. The results: Design/build philosophy reduced project time and the number of teams involved. This allowed for easier communication and extended development time well into the project. All design teams (machine, tooling, automation, controls) collocated and worked together on integration during all stages of development and implementation for the highest level of integration. Innovative integration of the tooling and the automated equipment evolved throughout project with the teams working as one group. Latest fastening technology using all electric, ball-screw squeeze riveting was developed for high-speed and robust automated fastening. Latest mobilization technology was used to make the automated fastening machines interchangeable to reduce MTTR and to enable more PPM activities offline without affecting production. More automation was also introduced for tool changing and to the material handling systems for more consistent processing and to reduce operator intervention. All systems were developed together for full integration and to enable more safety interlocks and HMI for simplified operation. A 30 month schedule for the complete large scale assembly line was maintained to support the new aircraft launch schedule. The final solution was a coherent, streamlined and efficient assembly line capable of very high aircraft production rates (Figure 1).
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