Study on delamination inhibition and chip breakage mechanism in drilling metal laminated materials with double cone drill

Abstract

Abstract With the continuous deepening of material research, laminated materials have been widely used in the aerospace field. The most common metal laminated material is aluminum/titanium (Al/Ti) stacks. Drilling is one of the most common methods of assembly. Due to the difference in material characteristics, problems such as delamination damage and chips winding around the drill are easy to occur when drilling metal laminated materials, which affect the drilling quality. The purpose of this study is to inhibit the delamination of Al/Ti laminated materials and improve the fracture ability of chips by changing the second point angle of the double cone drill. In this paper, the mechanical analysis of the drill structure is firstly carried out to obtain the torque models, and the drilling force is mainly analyzed based on torque. The combination of experiments and finite element method (FEM) is used to verify the correctness and feasibility of the mechanical models. The results show that, compared with the ordinary twist drill, the double cone drill can reduce the drilling force. Then, the effects of drilling force on delamination damage, chip morphology, and chip breakage during twist drilling and double cone drilling are analyzed and compared using simulation. The study found that compared with the twist drill, the use of the double cone drill to drill Al/Ti laminated materials will reduce the drilling force, resulting in less delamination damage. In addition, the second point angle makes the chip thickness produced by the double cone drill smaller than that of the twist drill, making it easier to break chips. Delamination damage and chip thickness decrease with the decrease of the second point angle.