Analysis of the chip-splitting performance of a dedicated cutting tool in dry orbital drilling process

Abstract

Orbital drilling technology, as an alternative of conventional drilling, is considered a promising option of hole-making work in the aircraft industry. However, in orbital drilling, unreasonable chips with irregular geometry and large size can cause the rapid increase of cutting force and cutting heat accumulation and eventually lead to serious tool wear and poor hole wall quality. To solve the problem, this paper designs a dedicated cutting tool with a chip-splitting structure to be used in the orbital drilling of TC4 titanium alloy under dry cutting condition. Based on the analysis of orbital drilling kinematics, the dedicated cutting tool, having front cutting edges with straight cutting segments and helical peripheral cutting edges, is first proposed. Furthermore, the width of cut, uncut chip thickness and length of cut are calculated considering the different characteristics of cutting condition for each tooth in a chip formation period. Particularly, the geometries of the undeformed chips are simulated and the relationships between the geometries and machining parameters are studied. Experimental study on the chip-splitting performance of the dedicated cutting tool in orbital drilling of TC4 titanium alloy is also conducted. The results show that with the dedicated cutting tool, the chip can be removed smoothly, which leads to higher machining quality and lower tool wear.