Currently, the aerospace industry is investing heavily in automation equipment to reduce production costs, shorten production time, and improve quality under the leadership of Airbus and Boeing. In particular, there is a need for equipment that automatically performs drilling and riveting, which is a significant part of the aircraft assembly process. However, due to lack of know-how on automation process and technology for automation equipment development, various problems occurred in commercialization process. The equipment to be developed through this study is a Drilling and Riveting Machine(DRM), which automatically connects a lock bolt by drilling and swaging in an aircraft assembly process.
When DRM development is completed, it is expected to produce products with high level of precision and quality compared with existing manual processes. Also, it is anticipated to be possible to secure price competitiveness and reduce maintenance cost by shortening the process time. However, in Korea, there are no precedent cases where equipment that can drill and rivet simultaneously were ever developed and produced. Therefore, in this study, we try to find out the problems that can occur in the process of commercializing DRM and find ways to improve it.
First, the precision of the hole diameter and the length of the exit burr have a great influence on the quality of the finished product. Therefore, a test bench is manufactured to evaluate DRM drilling performance. The drill diameter and the length of the exit burr according to the rpm of the drill spindle of the DRM are measured and the process capability evaluation is performed to confirm whether the criterion is satisfied or not,
Second, we predict the shape of the swaged collar by numerical analysis on the process of collar swaging in the rock bolt, cut the coupon swaged by DRM and compare it with numerical analysis results. The tensile load test was then performed to confirm the bond strength between the rock bolt and the swaged collar, and through the fatigue test, trying to predict the fatigue limit and fatigue life while they are in the fretting state.
If the equipment is operated under those conditions derived from this study, it is expected that efficient operation will be possible with performance, durability and economic efficiency.