복합변형변수 모델링 방법을 이용한 회전 드릴의 모델링 및 진동해석

Abstract

In this paper, modeling and vibration analysis of a rotating drill was conducted. A drill system was modeled based on Euler-Bernoulli beam theory and Winkler-type elastic foundation theory, and vibration analysis was performed using the model. The drill bit was idealized as a beam with a pre-twisted angle, and the effect of reducing the bending stiffness of the beam by axial force was considered using a hybrid deformation variable modeling method. In addition, the unit step function was used and the variation in feed distance of the work-piece is considered. Finally, equations of motion were derived using the Rayleigh-Ritz assumed mode method and Kane's method. From the numerical results, it was confirmed that the natural frequency decreases abruptly and the unstable region was the widest at the moment of contact between the drill bit and the work-piece. Moreover, it was verified that the rotation speed and axial force were the main factors that reduced the stiffness of the drill bit.