Environmentally Conscious Manufacturing: Economical Cryogenic Machining

9528710为了消除在机械加工行业中使用传统切削液的健康问题和环境污染，最近一项大学和行业的联合研究产生了一种经济实用的低温加工技术。这种干燥、清洁、整洁的新工艺用超冷氮气冷却刀具。通过采用“在微观意义上控制切割温度”的新冷却概念，液氮的消耗被最小化到氮气成本低于传统切削液的水平。温度是改变材料特性的一个因素。在切屑形成过程中，通过改变温度来调整切屑形成过程中微观位置的材料特性，如主剪切区、成形切屑、摩擦区、主体工件、刀面和刀身，以使其最有利于切割过程。该项目包括对目标工件和刀具材料的材料研究，以确定理想的温度分布，以产生特定操作的最佳材料行为。喷嘴喷型、覆盖面积和液氮流量是调节温度分布的设计参数。通过控制冷却模式，可以将温度分布控制在最理想的范围内。将进行热力学和传热学有限元分析，以预测特定切割过程的温度分布。实现冷却到该温度所需的液氮量将在理论和实验上确定。然后，可以将流量控制到最低限度，以便仍能完成工作；将为其开发智能控制系统。这种方法的预期结果是最有效的加工和最经济的氮气分配。切削液在加工过程中起着关键作用。历史上，切削液的优化主要是为了提高切割效率，但却以牺牲环境为代价。这导致了对低温加工等创新研究的需要。如果能够证明在保持当前每个零件的切削液成本的同时可以提高切割效率，则对加工行业的影响可能是广泛的，从而导致这种环保制造技术的市场吸引力。

9528710 Hong To eliminate both the health problems and the environmental contamination of using conventional cutting fluid in the machining industry, a recent joint University-Industry research has led to an economical and practical cryogenic machining technology. This new process, which is dry, clean, and neat, cools the cutting tool with super cold nitrogen. By adopting a new cooling concept, "manipulating the cutting temperature in the micro sense," the consumption of liquid nitrogen is minimized to a level at which the nitrogen costs less than conventional cutting fluid. Temperature is a factor in changing materials properties. The material properties at micro locations in the chip formation process, such as the primary shear zone, the formed chip, the friction zone, the bulk workpiece, the tool face, and the tool body, will be adjusted by varying the temperature to be the most favorable for the cutting process. This project includes a material study of target workpiece and tool materials to determine the ideal temperature distribution to yield the optimum material behavior for specific operations. The nozzle spray pattern, covering area, and liquid nitrogen flow rate are design parameters to adjust the temperature distribution. By controlling the cooling pattern, the temperature distribution can be manipulated to the most desirable range. Thermodynamic and heat transfer finite element analyses will be conducted to predict the temperature distribution of the specific cutting process. The amount of liquid nitrogen needed to achieve the cooling to that temperature will be theoretically and experimentally determined. The flowrate then can be controlled to the minimum amount to still be able to do the job; an intelligent control system will be developed for it. The expected result of this approach is the most efficient machining and most economical nitrogen dispensing. Cutting fluid plays a key role in the machining process. Historically, cutting fluids have been optimize d primarily for the cutting efficiency but at the sacrifice of environmental concerns. This has led to the need for innovative research such as cryogenic machining. If it can be proven that the cutting efficiency can be improved while maintaining the current cutting fluid cost per part, the impact on the machining industry could be broad-based resulting in a market pull for this environmentally conscious manufacturing technology.