The purpose of the VibroCool project is a system and process development for an advanced drilling technology of fiber reinforced polymers (FRPs) and FRP metal stacks, aiming for a future strengthening of the composite manufacturing community. Vibration assisted machining, the use of cryogenic cooling or lubrication (two channel feed through of aerosol and liquid CO2), and optimized poly crystalline diamond drills will be combined to reach the highest possible increase in cutting performance. For the realization of the planned technology, single system components as well as their interfaces will be developed and integrated within a sophisticated machine tool. Parallel process technological investigation will guarantee an optimal utilization of the VibroCool technology’s potential.
The planned system, which will be integrated into a commercial machine tool, is illustrated schematically in Figure 4. It consists of a CL-unit (coolant & lubricant) where liquid CO2 and the lubricant (extra-fine aerosol which is a mixture of cutting oil and compressed air) are provided in two separate lines. Both lines go internally through the machine spindle, the tool holder and also the cutting tool. Right next to the cutting zone, the liquid CO2 evaporates and cools down the process effectively without using a liquid coolant. Simultaneously, the aerosol works as a lubricant that reduces the friction between work piece and cutting tool and thus generates less overall process heat. This coolant/lubricant solution will be combined with ultra-sonic assisted drilling technology which will be integrated into a special tool holder. The tool holder will contain an ultra-sonic excitation device to initiate an axial vibration of the cutting tool with high frequencies and low amplitudes. By the superposition of vibration and feed movement, the generated thrust force will be reduced, affecting process-induced part damage and tool life in a beneficial way. Optimized poly crystalline diamond drills and knowledge-based process design for drilling of FRP and FRP metal stacks are further elements of the research initiative.
Figure 4: VibroCool System
The VibroCool project is divided into different work packages, in which the single components of the entire system will be developed and optimized. More precisely, the project is built on three distinct technology RTD modules (Figure 5).
Figure 5: Modular approach of the VibroCool project