刀具非对称刃口钝化机制与对切削性能影响的研究

High-speed and efficient cutting is an inevitable development direction of mechanical processing technology. Tool edge preparation prolongs the service life of tool and elevates the processing surface quality and cutting performance through modifying the cutting edge micro contour in edge area. The edge contour is very complex, which is usually not regular circle. Therefore, it is not enough to characterize the micro edge contour through the edge radius. The preparation mechanism and influence on the cutting process of the tool asymmetric edge is studied in the project. The metal machining and abrasive wear theory is applied. The method combining the numerical simulation, mathematical statistical modeling and experiment is adopted. Based on the drag finishing assisted with gas-solid two-phase abrasive, the edge preparation mechanism of the tool asymmetric edge is revealed. The quantitative characterization method based on the B spline function of the asymmetric contour is purposed. The influence of the parameters such as edge preparation parameter on the asymmetric contour is clarified in drag finishing. The formation mechanism of the asymmetric edge is revealed. The cutting process model based on essential characteristics of the asymmetric edge is built. The influence law of the asymmetric edge on the cutting heat-force coupling characteristic, cutting tool life and surface integrity is reviewed. The influence law of the edge preparation effecting on the cutting performance is clarified, which reviews the mechanism of tool edge preparation. The research results will put forward theoretical value and practical significance to develop the processing technology of high-speed and efficient cutting, improve the metal cutting theory and prompt the development of the manufacture industry.

高速高效切削加工是机械加工的必然发展方向。刀具刃口钝化通过改变切削刃的微观轮廓，提高刀具使用寿命、改善切削性能和加工表面质量。刀具钝化的刃口轮廓非常复杂，通常并非规则的圆弧，仅采用钝圆半径不足以表征刃口微观轮廓。本课题拟对刀具非对称刃口钝化机制与对切削性能的影响规律进行研究。综合运用金属切削和磨粒磨损理论，采用数值模拟、统计建模和实验相结合的方法，基于气固两相流磨粒的立式旋转钝化，揭示刀具非对称刃口钝化机理；提出基于B样条函数的非对称刃口参数化定量表征方法，阐明刀具钝化参数对非对称刃口尺寸的影响规律，揭示刀具钝化的非对称刃口的形成机制；建立以非对称刃口为本质特征的切削模型，阐明非对称刃口对切削热-力耦合特性、刀具磨损和表面完整性等的影响规律，揭示刀具非对称刃口钝化的作用机理。研究成果对于发展高速高效加工技术，完善金属切削加工理论，促进我国装备制造业的发展具有重要的科学和工程意义。

刀具钝化是实现高速高效切削加工的基础。基于气固两相流颗粒动力学理论和离散元理论，采用EDEM-FLUENT耦合方法研究进气流速、半径比、正反转比例和磨粒粒度等对磨粒流速度、刃口作用力和磨损量的影响规律，阐明刀具刃口与磨粒冲击的内在本质关系；采用有限元软件ABAQUS建立磨粒冲击仿真模型，研究单磨粒和多磨粒冲击刀具刃口时磨粒速度、刃口应力、位移和能量等的变化规律，并基于临界应变区的塑性变形理论和能量吸收理论，建立单磨粒材料去除模型，根据刀具正反转的扫掠体积建立多磨粒材料去除数学模型，揭示刀具非对称刃口钝化机理。采用三阶B样条曲线描述刀具非对称刃口，并对不同钝化参数和材料刀具的刃口形貌进行表征，验证了采用B样条曲线对刀具非对称刃口进行表征的精确性；搭建基于气固两相流磨粒的刀具钝化实验平台，通过实验研究钝化时间、正反转时间比、进气压力和半径比等对前刀面和后刀面钝化值的影响规律；基于多磨粒冲击对刀具材料的去除机理，建立不同刃口形状因子的数学模型，并通过与钝化实验对比，揭示刀具非对称刃口的形成机制。基于金属切削理论和滑移线场理论，建立对称刃口的切削力模型，并综合考虑犁切力的动态变化及非对称刃口剪切的特点，将刃口尺寸效应反映在切削力系数中，建立刀具非对称刃口瞬时铣削力模型，通过与切削实验对比，验证切削力模型的正确性，采用软件DEFORM建立刀具切削模型，并与切削实验相结合研究切削参数和非对称刃口参数对切削力和切削温度的影响规律；采用硬质合金刀具铣削SUS-304不锈钢，通过扫描电镜(SEM)及能谱分析(EDS)研究刃口微观几何对刀具寿命、磨损机制及加工质量的影响，揭示刀具非对称刃口对切削性能的影响规律。本项目解决了刀具非对称刃口的钝化机制与作用机理等重大科学问题，丰富了刀具钝化理论。本项目的实施有利于延长刀具使用寿命，改善切削性能和加工表面质量，可以满足航空航天等领域对高效、高精度刀具的重大需求，实现高速高效加工技术，促进我国装备制造业的发展。