Effect of crack on drilling vibration

Effect of drill parameters and the local crack on the dynamic characteristics of a drill during the drilling through process is investigated in this study. A pre-twisted beam with a local crack is used to simulate the cracked drill. The release energy model is employed to characterize the stiffness variation around the crack. A moving Winkler-type elastic foundation assumption is used to approximate the time dependent work piece stiffness distribution on rotating drill during the drilling process. In this article, a drill vibration model with time varied boundary condition is presented. The effects of cracks, rotational speed, pre-twisted angle and thrust force on the vibration of drill are considered. A serious vibration is observed at the moment as the drill touch the work piece in a drilling process. The simulated results also indicate that the local crack may aggravate the vibration.