GOALI/Collaborative Research: Thermomechanical Investigations of High Speed Machining of Aluminum

在金属切削加工过程中，塑性变形和摩擦导致工件产生热量，从而导致切削区的复杂变形。最近，这种高度耦合的过程的几个数值模型已经产生在响应高速加工的兴趣增加。然而，尽管在过去和最近，少数研究人员已经检查了在低或传统切割速度下切割期间的温度场，但是很少存在测量在高速（即，20-100 m/s）下切割期间工件中的温度场的实验研究。在高速加工过程中，为了表征该区域的摩擦和磨损特性，并了解在那里产生的热量，这会影响切屑的形成和可能的残余应力的形成，表征切削区域中的热场是很重要的。最终，这些调查应指导高速加工应用的材料开发的进一步进展。在这项工作中，红外探测器被用来实验测量高速正交切削过程中工件表面的温度分布，并开发复杂的数值模型来预测和理解变形和失效的主动机制。最后，从这些温度测量和模型，在主变形区中产生的热量进行检查，表征和相关的工件中的残余应力分布。 其主要目的是为了更好地理解，从而减少，残余应力对高速加工，薄壁部件的变形的影响。该方法借鉴了实验，数值和工业研究人员的经验，以全面的实验，理论和发展方法来解决这个困难的，经济相关的问题。具体的好处是：（1）详细了解成品质量之间的相互作用，材料的行为和热生成在高速加工：（2）新的高效和准确的计算算法，以模拟高速加工，以促进充分了解观察到的刀具，材料和切割质量或残余应力形成之间的相互作用;（3）高速切削铝合金设计的新方向，重点是尽量减少加工和合金加工参数对成品中残余应力形成的影响。 总的来说，一个综合的材料力学/建模实验的方法来解决这个问题，将在整个工作中使用，导致一个多学科的解决方案，在高速加工的零件的残余应力变形的问题。

During the machining of metals, plastic deformation and friction lead to the production of heat in the workpiece, which results in complex deformation in the cutting zone. Recently, several numerical models of this highly coupled process have been produced in response to the increased interest in high speed machining. However, while a small number of researchers, in the past and recently, have examined temperature fields during cutting at low or traditional cutting speeds, few if any experimental studies exist that measure temperature fields in the work piece during cutting at high speeds, i.e. 20-100 m/s. It is important to characterize the thermal field in the cutting zone during high speed machining in order to characterize friction and wear characteristics in this area and to understand the heat generated there, which affects chip formation and possibly residual stress formation as well. Ultimately, such investigations should direct further advancement in materials development for high speed machining applications. In this work, infrared detectors are used to experimentally measure the temperature distribution at the surface of a workpiece during high-speed orthogonal cutting, and complex numerical models are developed to predict and understand the active mechanisms of deformation and failure. Finally, from these temperature measurements and models, the heat generated in the primary deformation zone is examined, characterized and related to the residual stress distribution in the workpiece. The main thrust is to better understand, and therefore reduce, the effects of residual stress on distortion of high-speed machined, thin walled components. The approach draws on the experience of experimental, numerical and industrial researchers to attack this difficult, economically relevant problem with a comprehensive experimental, theoretical and developmental approach. Specific benefits of the proposed work are: (1) Detailed understanding the interplay between finished product quality, material behavior and heat generation in high speed machining; (2) New efficient and accurate computational algorithms to model high-speed machining in order to facilitate full understanding of the observed interactions between tool, material and cut quality or residual stress formation; and (3) New directions in aluminum alloy design for high-speed cutting with emphasis on minimizing the effects of machining and alloy processing parameters on the formation of residual stresses in the finished product. Overall, an integrated materials-mechanics/modeling-experimentation approach to the problem will be used throughout the work leading to a multidisciplinary solution to the problem of residual stress distortion of parts machined at high-speed.