中文摘要：

高温合金广泛应用于航空航天领域，是一种典型的难加工材料，切削过程中切屑缠绕工件及刀具、不易折断，从而降低刀具寿命和已加工表面质量。PCBN是超硬刀具材料，加工高温合金等高温高强度钢性能优异，但由于刀具材料特性通常采用平前刀面，因此切削过程中断屑比较困难。高压冷却是金属高效切削加工中一种新型加工技术，可以有效改善断屑性能、提升断屑能力、提高刀具寿命和加工表面质量。目前对高压冷却断屑机理研究较少，且高压冷却切削仿真不易实现，为充分研究高压冷却下高温合金切削加工中的切屑折断机理，通过建立切屑卷曲半径预测模型和断屑模型，进行高压冷却下切屑折断机理研究，主要通过在高压冷却下，对PCBN刀具切削镍基高温合金进行试验研究，研究不同冷却液压力下切屑卷曲半径变化规律，对理论分析结果进行验证。研究结果表明：在高压冷却加工中由于高压冷却液的存在，切屑受到附加冷却液压力影响，使弯矩发生变化，造成切屑卷曲半径减小，最终导致切屑应变增大、切屑易于折断；且由于卷曲半径的改变使极限进给量和极限背吃刀量降低，使高压冷却加工改善断屑性能的效果非常明显。上述研究成果为实现高温合金高压冷却条件下的切削加工奠定了理论基础。

英文摘要：

Superalloys are widely applied in the aerospace industry, and it is one of classical difficult-to-cut materials. In cutting process, the chip is wound around the workpiece and tool which is not easy to break. So it reduces the tool life and the surface quality of machined surface. Polycrystalline cubic boron nitride （PCBN） is super-hard cutting tool which has excellent performance in machining superalloys and high strength steel. However, due to the material properties of PCBN, tools are usually flat rake face so that it is difficult to break chip. High pressure cooling is a new type of machining technology in high efficiency metal which can effectively improve the chip breaking performance, improve the tool life and surface quality. At present, there is little research on the mechanism of high pressure cooling chip breaking. In order to study the chip breaking mechanism of cutting superalloys with high pressure cooling, Through the establishment of chip curling radius prediction model and chip breaking mode, study on chip breaking mechanism under high pressure cooling. The experimental study on PCBN cutting nickel base superalloys under high pressure cooling is carried out to study the change of chip curling radius under different coolant pressure, and validate the theoretical analysis result. The results demonstrate that due to the presence of high-pressure coolant in high pressure cooling process, chip is affected by additional cooling fluid pressure and it makes the moment change with result of the decrease of cutting crimp radius, it eventually leads to the chip easy to be broken. Because of the change of the crimp radius, limit feed and limit cutting depth reduce. High pressure cooling process can improve the chip breaking performance, and the above results can provide some technical support and reference for the subsequent high pressure cooling process.