Structure Design Of The Multi-station Special Drilling Machine For STA2521Modification Of B747-400

Aircraft modification is a technically demanding work,high quality is required,andcoordination of various departments is complicated. Modified personnel’s technical level andthe level of process equipment affects the maintenance schedule,the residence time of theaircraft in the hangar, and the aircraft overhaul production plan. Raising the level of processequipment in the process of modification can reduce the cycle of the aircraft partsprocessing,make the maintenance processes and the personnel assignment more reasonable,shorten working hours, speed up the aircraft maintenance schedule, optimize the allocation ofresources of the enterprise, and play an important role in improving maintenance quality andeconomic benefit of the enterprise.The research of this article is based on the STA2521modification of B747-400. The jobcard requires to replace four supports on both sides of where the aircraft tail and fuselagejoints, for different B747-400planes, the position of the assembly hole is slightly different, soit needs to drill assembly holes on the new support, and ensure the size and position of theassembly hole is the same as which on the removed support. There are many questions of thecurrent processing method, such as long drilling time, clamping more times, large manpoweris needed, the location of the hole is imprecise and the support may be damaged. Based on theproven experience in the maintenance and the existing technical conditions, this paper designsa set of drilling equipment applied to this job.This paper determines the core problem which influences the machining efficiency andquality is how to determine the position of the assembly holes on the new support quickly.According to the principle of copying and the theory of fixture design, overall design schemeis worked out, as the two core parts of the hole transfer device, the multi-position clamp andassembly hole positioning device are designed based on CATIA and AUTOCAD. Themulti-position clamp mainly has carried on the design of the localization plan, clampingschemes and dividing mechanism, and achieves a multi-station machining function that foursurfaces can be processed in one clamping. Assembly hole positioning device is composed bythe linear slide rail, u-shaped slide planes, positioning plate, drilling platform and the base,and can determine the position of the assembly holes on the new support quickly. The SWLlifting mechanism can adjust the distance between the machining surface and drillingplatform. The simulation analysis was carried out on the multi-station special drilling machine bythe digital mock–up motion simulation module of CATIA, see if there are any interferenceand discordances of the equipment, and reduce the design cost which caused by theengineering error. The simulation analysis verifies the main technical links such as the designscheme, function display, established design and structure optimization and so on.Using electronic prototype of the support member drilling simulation results show thatthe running condition is good, the working strength is decreased significantly, the humanconsumption is reduced greatly, the machining quality of the support is improved, theprocessing cycle of aircraft parts is shorten, it achieved the purpose of reducing maintenancetime.