Reserches Of Drill Geometry Impact On Drilling CFRP

Carbon fiber reinforced plastics is a kind of advanced composites with a wide variety ofapplications. CFRP is widely used in avigation and spaceflight field which characterized byhigher specific stiffness, higher specific strength, better heat resistance. The poor processingquality in drilling is restricting the development and application of materials owing to thelaminated structures and characteristics of high hardness and poor heat dissipation.CFRP is a typical difficult to machine material due to entrance splitting and delaminationin drilling process. Aiming at hard machinability of drilling CFRP, how drill geometry andprocess parameters affect the processing quality is discussed in this article. Comparativelyanalyze the thrust forces and processing quality in drilling process caused by point angle andchisel edge by establishing a finite element analysis model of drilling CFRP. And a core drillis employed to drill thin CFRP on account of the effect drill geometry affects the processingquality. The results are shown that:1. Point angle and chisel edge of the drill contribute a lot to the processing quality ofdrilling CFRP. A small-angle drill has better processing quality than a twist drill thanks to thesmaller point angle; the shorter the chisel edge is, the less the thrust force results, and betterquality present.2. Process parameters are important factors which affect processing quality a lot. Thethrust force rises with the rising of feed rate; reduces with the rising of spindle speed. Higherspindle speed and lower feed rate produce better processing quality in drilling CFRP.3. Core drills provide better processing quality and less damage at the exit of workpiecethan twist drills in drilling CFRP, moreover are less influenced by process parameters.