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

在金属加工过程中，塑性变形和摩擦会导致工件产生热量，从而导致切削区的复杂变形。最近，随着人们对高速加工的兴趣日益增加，已经产生了几个关于这种高度耦合过程的数值模型。然而，虽然过去和最近有少数研究人员研究了在低速或传统切削速度下切削过程中的温度场，但很少有实验研究测量高速切削过程中工件的温度场，即20-100m/S。为了表征这一区域的摩擦和磨损特性，了解那里产生的热量，从而影响切屑形成和可能的残余应力形成，表征高速加工过程中切削区的热场是很重要的。最终，这样的研究将指导高速加工应用材料开发的进一步发展。本工作利用红外探测器对高速正交切削过程中工件表面的温度分布进行了实验测量，并建立了复杂的数值模型来预测和理解变形和破坏的活动机理。最后，根据这些温度测量和模型，对在主变形区产生的热进行了检验、表征，并与工件中的残余应力分布相关联。主要目的是为了更好地了解并减少残余应力对高速加工薄壁零件变形的影响。该方法借鉴了实验、数值和工业研究人员的经验，以综合的实验、理论和发展方法来解决这一与经济相关的难题。拟议工作的具体好处是：(1)详细了解高速加工中成品质量、材料行为和热产生之间的相互作用；(2)建立高速加工模型的新的高效和准确的计算算法，以便于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；以及(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。总体而言，将在整个工作中使用材料-力学/建模-实验的综合方法来解决该问题，从而导致高速加工零件的残余应力变形问题的多学科解决方案。

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.