HIGH ACCURACY AEROSPACE DRILLING USING A HYBRID PARALLEL KINEMATIC MACHINE TOOL

The Northern Ireland Technology Centre (NITC) at Queens University Belfast, in collaboration with industrial partners has extensively studied the use of a Hybrid Parallel Kinematic Machine (HPKM) tool, the Gudel Exechon XQ701... [ view full abstract ]

The Northern Ireland Technology Centre (NITC) at Queens University Belfast, in collaboration with industrial partners has extensively studied the use of a Hybrid Parallel Kinematic Machine (HPKM) tool, the Gudel Exechon XQ701 for aerospace hole generation and surface machining. HPKM technology has the ability to deliver the flexibility and working envelope of an industrial robot while still providing the high accuracy and stiffness expected from a CNC machine. The combined properties of the parallel linkage structure of a HPKM offer significant potential for improvements to be made in existing aerospace machining, drilling and assembly processes. This was in evidence recently in a number of projects involving high tolerance aerospace fastener insertion and shimless aerospace assembly, where machine accuracy and repeatability were paramount, concomitant with open structure assembly work allowing the emerging technology to readily integrate into existing aerospace assemblies.
In this paper, the drilling performance of a 3 axis CNC machine and a 5 axis HPKM machine was assessed by a comparative quantitative analysis of hole quality and drilling forces under controlled conditions to demonstrate the capability of the HPKM. Drilling trials were performed dry in CFRP/Al coupons using 9.525 mm solid carbide drills. Modal analysis was used to elucidate the dynamic response of each machine to the experimental setup and therefore the optimum drilling parameters across platforms. Metrology examined the dimensional accuracy, hole cylindricity, hole perpendicularity and surface roughness across the coupon array.