Vibrational excitation of a work piece for drilling force reduction in brittle materials
Keywords: work piece vibrations, solid structure, flexible structure, holographic interferometry
AbstractArticle investigates the possibilities of reducing drilling forces in brittle material drilling, through high frequency excitation of a work piece. Two excitation con-ditions are analyzed – first, when the sample acts as a solid structure and second, when the sample acts as a flexible structure. In order to analyze the effect, work piece excitation has on drilling forces, drilling experiments were conducted, drilling forces were measured and compared between the case when the sample was drilled in a conventional way and when the work piece was excited. Drilling was conducted at different speeds – 145, 290 and 540 rpm. With the increase of speed, average difference between forces of conventional drilling case and drilling of an excited work piece has increased from 24 to 40%. In order to analyze the behaviour of a flexible structure when subjected to excitation, vibration mode simulations of the sample were developed. To test their validity, holographic vibration analysis was conducted – the simulation results do not completely correlate with the experimental ones. Such deviations may be caused by assymetrical clamping of the sample durring the holographic vibration mode ana-lysis. With regards to this, either the experimental technique or the simulation model should be tweaked to enable its practical application in further research.