Development of Hole Making Technology of Bi-Layer Composite Materials Consisting of CFRP Laminates and Titanium Alloys

Abstract

Recently, to construct an airframe 2-layer composite materials consisting of carbon fiber reinforced plastic (CFRP) laminates an TiAl6V4 still need to be machined, whereby drill holes are frequently machined. Special attention has to be paid to the machining quality, which implies hole dimensional accuracy, defect free peripheral zone, edge quality at inlet and outlet of hole and so on. In this research, first by using a high performance CNC machine tool equipped with potent control unit, drilling and circular milling are compared for hole making in CFRP laminates and it is ascertained that circular milling is superior to drilling in defect free peripheral zone and also tool life [. Second, from comparing drilling and circular milling in hole making of 2-layer composite materials consisting of CFRP laminates and TiAl6V4, the superiority of circular milling caused by lower thrust force and lower thermal load than those of drilling has been made clear [. Third, the author has devised a new spindle designed based on double eccentric mechanism so that circular milling can be executed at an airframe assembly site. By using a new handy type apparatus having the spindle driven by air motors, hole making tests were executed to 2-layer composite materials consisting of CFRP laminates and TiAl6V4 with cemented carbide endmill [.