Prediction of machining chatter based on FEM simulation of chip formation under dynamic conditions
Prediction of machining chatter based on FEM simulation of chip formation under dynamic conditions
复制标题
DOI：
10.1016/j.ijmachtools.2010.03.009
复制
发表时间：
2010-07
影响因子：
14
通讯作者：
M. Mahnama;M. Movahhedy
中科院分区：
文献类型：
--
作者：
M. Mahnama;M. Movahhedy
加工颤振是一种固有的非线性现象，受到许多参数的影响，例如切削条件、刀具几何形状（例如刀尖半径和后角）以及刀具/工件界面处的摩擦条件。颤振预测模型通常忽略非线性或通过简单的摩擦和几何模型引入非线性。特别是，芯片与刀具相互作用对颤振发生的影响尚未得到彻底研究。本文提出了一种预测颤振和研究各种条件对颤振发生影响的新方法。该方法使用有限元模拟来研究颤振与切屑形成过程之间的相互关系。切屑形成模拟与机床动态分析相结合，以确定两种现象之间的相互作用。网格自适应技术用于在工件内部移动刀具以形成切屑，而柔性刀具则用于允许刀具在可变负载条件下振动。通过在不同切削宽度下重复模拟，结果表明可以检测到颤振的发生，并且模拟能够真实地预测实际加工过程中观察到的各种现象，例如剪切角的变化和较低速度下稳定性的增加（称为过程阻尼）。将模拟获得的稳定性图与正交切削试验获得的实验数据进行比较。两组结果之间观察到的合理一致性证明了模拟方法的有效性。
Machining chatter is an inherently nonlinear phenomenon that is affected by many parameters such as cutting conditions, tool geometry e.g., nose radius and clearance angle and frictional conditions at the tool/workpiece interface. Models for chatter prediction often ignore nonlinearities or introduce them through simple models for friction and geometry. In particular, the effect of chip–tool interaction on the occurrence of chatter is not investigated thoroughly. This paper presents a novel approach for prediction of chatter vibration and for investigation of the effects of various conditions on the onset of chatter. This approach uses finite element simulation to investigate the inter-relationship between the chatter vibration and the chip formation process. Simulation of chip formation is combined with dynamic analysis of machine tool to determine the interaction between the two phenomena. Mesh adaptation technique is used to move the tool inside the workpiece to form the chip, while a flexible tool is used to allow the tool to vibrate under variable loading conditions. By repeating the simulations under various widths of cut, it is shown that the onset of chatter can be detected, and the simulation is able to realistically predict various phenomena observed in actual machining process such as variation of shear angle and the increase of stability at lower speeds known as process damping. The stability map obtained from simulations is compared with experimental data attained through orthogonal cutting tests. Reasonable agreement observed between the two sets of results demonstrates the effectiveness of the simulation approach.