GOALI: Fundamental Investigation of Constrained Cutting for High Performance Machining of Difficult-to-Cut Materials

GOALI学术联络机会奖支持一种新的金属切割方法的基础研究，以提高难加工材料的加工效率。在需要较高切削力的典型加工条件下，难加工材料的可加工性较差，导致温度较高、刀具寿命较短和表面光洁度较差。这些切割困难从根本上归因于难加工材料难以形成切屑的特点，以及常规切割缺乏控制切屑形成的能力。新的切割方法除了使用切割工具外，还使用约束工具，以实现对切割过程中切屑形成的直接控制。这可以优化切屑形成特性，从而以较低的切削力实现高效的材料去除，从而延长刀具寿命、改善表面完整性和提高材料去除率。受限切割方法极大地有利于美国制造业，如汽车、航空航天和能源，这些行业大量使用难以切割的材料。与美国刀具行业合作伙伴的密切合作确保了技术转让，以开发下一代刀具和加工战略。该项目通过研究生和本科生参与研究和教育，为先进的制造和工程培养一支训练有素的劳动力队伍。该项目的研究重点是调查几何约束剪切变形区如何影响机械加工过程的力学、动力学和生成的表面完整性。传统的金属切割工艺缺乏对切屑形成的直接控制。通过附加的约束刀具控制剪切变形区，可以减少切削力，显著提高表面完整性和加工稳定性。为了解约束参数(位置和几何)与切削力(力、能量和温度)之间的基本关系，通过现场数字成像和解析和计算模型对约束切割过程中的切屑变形进行了实验分析。约束剪切变形区可以减少塑性变形和热机械载荷。这改善了表面光洁度，增强了显微组织，并降低了残余应力。实验表征以及与变形和温度分析的关联产生了新的知识，从而能够更好地控制生成表面的完整性。研究了约束刀具对加工过程和加工设备耦合动力学的影响，提出了控制和抑制加工过程中高频自激颤振不稳定性的约束刀具几何设计。这使得可以在更高的深度、进给量和速度下加工精密零件，从而获得更高的材料去除率和更高的表面光洁度。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This Grant Opportunity for Academic Liaison with Industry (GOALI) award supports fundamental research on a novel metal cutting method for enhancing the efficiency of machining difficult-to-cut materials. Difficult-to-cut materials have poor machinability in typical machining conditions requiring higher cutting forces, and resulting in higher temperatures, shorter tool life, and poor surface finish. These cutting difficulties are fundamentally attributed to the difficult chip formation characteristics of difficult-to-cut materials and the lack of conventional cutting’s ability to control chip formation. The new cutting method uses a constraining tool in addition to a cutting tool to enable direct control of chip formation during the cutting process. This allows the chip formation characteristics to be optimized, which leads to efficient material removal with lower cutting forces, resulting in longer tool-life, improved surface integrity, and higher material removal rates. The constrained cutting method significantly benefits U.S. manufacturing industries, such as automotive, aerospace and energy, where difficult-to-cut materials are heavily used. Close collaboration with a partner from the U.S. cutting tool industry ensures technology transfer to develop next generation cutting tools and machining strategies. The project generates a well-trained workforce for advanced manufacturing and engineering through the involvement of graduate and under-graduate students, particularly, women and under-represented minorities, in research and education.The research focus of this project is to investigate how geometrically constraining the shear deformation zone affects the mechanics, dynamics, and generated surface integrity of machining processes. Conventional metal cutting processes lack direct control of chip formation. Controlling the shear deformation zone by an additional constraining tool can lead to reduced cutting effort, dramatically improved surface integrity and machining stability. Chip deformation during constrained cutting is analyzed experimentally through in-situ digital imaging and by analytical and computational modelling to understand the fundamental relationship between constraining parameters (location and geometry) and cutting effort (force, energy, and temperature). Constraining the shear deformation zone reduces plastic deformation and thermomechanical loads. This improves surface finish, enhances microstructure, and reduces residual stress. Experimental characterization and correlation with deformation and temperature analysis generate the new knowledge to enable better control of the integrity of the generated surfaces. The effect of constraining tool on the coupled dynamics of the process and the machining equipment is also investigated, which leads to new designs of constraining tool geometries to control and suppress high-frequency self-excited chatter instabilities during machining. This allows machining of precision parts at significantly higher depth, feed and speed leading to greater material removal rates and superior surface finish.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.