CFRP/钛合金叠层结构多维振动精密高效制孔工艺及其制孔缺陷抑制机制

Aimed to lower drilling induced damage during drilling of CFRP/Ti6Al4V stacks, a novel multi-dimensional vibrations assisted drilling technology by combining longitudinal-torsional ultrasonic vibrations of the bit and lower frequency vibration of the workpiece is put forward in this project, and the influence of the new technology on those drilling-induced damage will be researched. The research content includes: (1) To develop a novel longitudinal-torsional ultrasonic acoustics system with specified amplitude ratio and further build the experimental platform for multi-dimensional vibrations assisted drilling of CFRP/Ti6Al4V stacks. (2) To study the change law of cutting forces and temperature with direction angle of carbon fiber during longitudinal-torsional ultrasonic assisted drilling and reveal the weakening mechanism of longitudinal-torsional ultrasonic vibration on anisotropy of CFRP. (3) To reveal the effect of multi-dimensional vibrations on the chip formation during drilling of titanium and realize the controllability of chip shape, reducing the secondary damage to CFRP hole. (4) To study the characteristics of cutting forces and temperature during multi-dimensional vibrations assisted drilling and reveal the suppressing mechanisms on drilling-induced damage. (5) To propose an optimization strategy of batch drilling process with time-dependent parameters based on the built mapping relationships among cutting forces, cutting temperature, tool wear and drilling-induced damage. The developed precision and high efficiency batch drilling technology of CFRP/Ti6Al4V stacks will lay a theoretical and technological foundation for the improvement of assembly quality in national aviation manufacturing field.

针对CFRP/钛合金叠层结构制孔过程中容易产生制孔缺陷等问题，项目提出一种协同钻头纵扭超声振动和工件轴向低频振动的多维振动钻削新工艺，并对该工艺对制孔缺陷的影响进行研究。①研制具有特定纵扭幅比的单激励纵扭共振声学系统，搭建多维振动钻削平台。②研究纵扭超声振动对CFRP切削过程中切削力和温度随纤维方向角变化产生的各向异性行为的影响，揭示纵扭超声对碳纤维各向异性的弱化机制。③揭示多维振动钻削对钛合金切屑形成特性的影响，实现切屑形态可控，减小叠层结构制孔二次损伤。④研究叠层结构多维振动钻削中特殊的力、热特性，揭示组合振动对制孔缺陷的抑制机制。⑤根据加工过程中切削力、热和刀具磨损等物理量的时变特性与制孔缺陷演化之间的映射规律，提出多维振动钻削时变参数工艺优化策略。最终形成面向CFRP/钛合金叠层结构具有稳定制孔精度和质量的精密高效低缺陷批量制孔工艺，为提高我国航空装配质量奠定重要的理论与技术基础。

针对CFRP/钛合金叠层结构制孔过程中容易产生制孔缺陷等问题，项目提出一种协同钻头超声振动和工件轴向低频振动的多维振动钻削新工艺，并对该工艺对制孔缺陷的影响机制进行研究。①研制了具有特定扭-纵幅比的单激励纵扭共振声学系统，采用仿真分析螺旋沟槽几何参数对扭-纵分量以及谐振频率的影响曲线，优化出变幅杆的结构尺寸。研制低频振动工作台，通过仿真方法和振动特性试验确定其稳定性。研制了同时具有纵扭超声振动和低频振动的复合振动钻削刀柄，有效实现了CFRP/钛合金叠层结构的高效低损伤制孔。②基于弹性地基梁理论，从纤维受载后发生挠度变形出发，建立了刀具附加扭转超声振动下切削单根纤维的微观力学模型；通过对声发射信号进行小波包分解，研究传统切削和超声切削的纤维断裂模式，从而揭示了超声作用下CFRP微观去除机理及纵扭超声对碳纤维各向异性的弱化机制。③分别建立了低频钻削，超声钻削以及高低频复合振动钻削运动学模型，通过分析具体加工参数和振动参数下刀具的空间运动轨迹，发现通过改变超声和低频振动的参数，可以控制切屑的厚度及形状，不但有利于切屑的排出而且可有效降低钻削过程的切削力和切削热。④以CFRP/钛合金叠层板的高、低频振动钻削，以及高低频复合振动钻削的力热特性研究与钻孔质量的关联关系为研究目标，建立不同振动钻削模式下的钻削力和钻削热解析模型。应用有限元仿真仿真和钻削实验的方法来验证模型的合理性以及力热特性对钻孔质量的影响。⑤应用材料力学理论及钻削实验方法，揭示了不同振动加工模式下力热特性和刀具磨损之间的关系。最终通过理论和实验揭示了揭示组合振动对制孔缺陷的抑制机制，形成面向CFRP/钛合金叠层结构具有稳定制孔精度和质量的精密高效低缺陷批量制孔工艺，为提高我国航空装配质量奠定重要的理论与技术基础。