An investigation of the cutting fluid flow in self-piloting drills

The conditions of the coolant flow through the inlet annular channels, machining zone and outlet channels of self-piloting drills were investigated. Experiments were performed on B.T.A. and Ejector drills to determine the influence of the drill design parameters on the flow parameters. The influence of the inlet channel's clearance and eccentricity on the pressure distribution and energy loss was analytically examined. Experimental investigations of the static and dynamic pressure distribution of the cutting fluid in the machining zone were performed with different drill heads. Conditions for reliable chip removal from the machining zone and the boring bar were defined. The results obtained constitute a reference for designers of self-piloting drills and drilling processes.