Lightweight FRP Drill Tubes for Vibration Damping in BTA Deep Hole Drilling

BTA deep hole drilling is used to produce bore holes with high bore hole qualities and high length-to-diameter ratios. The tool system consists of a drill head and a drill tube. However, the length of the drill tube required to achieve high drilling depths leads to an increased tendency of the tool system to vibrate. The strong torsional vibrations increase tool wear at the cutting edges and the guide pads and influence the drilling quality. The dynamic behaviour of the tool system and thus the process reliability can be improved through the vibration damping effect resulting from the inhomogeneous structure of fiber-reinforced plastics (FRP). In this paper, a wound FRP drill tube is designed based on the experimental determination of mechanical and thermal loads of the drilling process. Compression and twisting of the FRP tube are evaluated simulatively and com-pared to a conventional steel drill tube. The vibration damping effect of the FRP drill tube is analysed in experimental investigations for the material 42CrMo4 + QT. In addition to the feed force and the drilling torque, chip shape, surface quality and noise exposure during the process are evaluated.