Modeling the motion of the cooling lubricant in drilling processes using the finite volume and the smoothed particle hydrodynamics methods

The process of single-lip deep hole drilling is used in various industrial applications for the production of small bores with a high length to diameter ratio. Especially the cooling and the lubrication of the machining zone have a great influence on the tool life, on the transport of chips, as well as on the quality of the resulting bore. In this paper, two approaches for the modeling and simulation of drilling processes are presented. On the one hand, the Finite Volume Method is used for the stationary simulation of the flow field. Assuming the entire bore to be filled with coolant, the focus is laid on a precise description of important fluid mechanical quantities along the cutting edges. The results show that the mass exchange of the cooling lubricant close to the cutting edge is far too low in order to guarantee the required cooling effect. On the other hand, a coupled meshless approach for the transient simulation is presented. The cooling lubricant is there modeled by the Smoothed Particle Hydrodynamics method and the Discrete Element Method is used for the description of chips. In contrast to the Finite Volume simulation, the main focus is laid on the evolution of the free surfaces and the transport of particles. The results show that the transport of chips by the cooling lubricant can be described well. Furthermore, also the transient Smoothed Particle Hydrodynamics simulations show an insufficient mass exchange behind the cutting edges matching the steady-state results from the Finite Volume simulation with a bore completely filled with coolant.