【作者】 霍超；

【导师】 蒋君侠； 韩野；

【作者基本信息】 浙江大学 ， 工程硕士（专业学位）， 2023， 硕士

【摘要】 碳纤维增强复合材料(CFRP)因整体性能可定向设计的特性而普遍用于飞机研发中。由于其与钛合金(Ti)都难于机械加工,对所组叠层自动制孔直钻仍存在的CFRP孔壁划伤与“阶梯孔”(CFRP缩孔、Ti扩孔)问题展开深入研究。首先,明晰了CFRP/Ti叠层自动制孔直钻工艺原理及问题成因,指出断屑降温与减小轴向力是改善制孔质量的关键。阐明了CFRP/Ti叠层自动制孔啄钻工艺的断屑原理及低效缺陷。阐述了低频振动自动制孔原理及其高效断屑机理与变角切削特性,适用于CFRP/Ti叠层制孔工况。其次,通过CFRP/Ti叠层低频振动自动制孔微观仿真分析,验证了低频振动自动制孔理论上可有效碎屑降温、减小切削力并改善叠层阶梯孔缺陷。提出了综合影响因子Q作为对其扩孔效应的评定方法,Q 1时为低效断屑;Q<1时为撞击扩孔、刃损加快;Q=1时为高效断屑和无撞击。然后,通过CFRP/Ti叠层低频振动自动制孔工艺对比试验,分析钛屑大小、CFRP孔出口状况与CFRP/Ti叠层孔径差数值,论证了相比自动制孔直钻,低频振动自动制孔可从加工层面改善CFRP/Ti叠层的制孔质量。最后,通过CFRP/Ti叠层低频振动自动制孔工艺参数优化,从方差、响应曲面、综合影响因子三方面分析了试验数据建模合理性与工艺参数对孔径差的影响规律,给出最优工艺参数组,验证其可有效抑制阶梯孔缺陷。更多还原

【Abstract】 Carbon fiber reinforced composite(CFRP)is widely used in aircraft development due to its directionally designable overall performance.Because it is difficult to machined with titanium alloy(Ti),the problems of CFRP hole wall scratches and "stepped holes"(CFRP shrinkage and Ti reaming)which still exist in the automatic lamination were investigated.Firstly,the principle and cause of the problem of CFRP/Ti lamellar automatic pore-making process are clarified.It is pointed out that the chip cooling and the axial force reduction are the key to improve the quality of pore-making.The chip breaking principle and low efficiency defect of CFRP/Ti laminated automatic hole drilling process are expounded.The principle of low frequency vibration automatic drilling,high efficiency chip breaking mechanism and variable angle cutting characteristics are described,which is suitable for CFRP/Ti laminated drilling.Secondly,through the microsimulation analysis of CFRP/ Ti low frequency vibration automatic drilling,it is verified that the theory of low frequency vibration automatic drilling can effectively reduce debris cooling and cutting force and improve the defects of laminated step holes.The evaluation method of comprehensive influence factor Q on its reaming effect is proposed.When Q>1,low efficiency chip breaking;When Q<1,the impact reaming and blade damage are accelerated.When Q =1,efficient chip breaking and no impact are obtained.Then,through the comparison tests of CFRP/ Ti laminates automatic drilling process with low frequency vibration,the titanium chip size,CFRP hole outlet and CFRP/ Ti laminates aperture difference values were analyzed.It was demonstrated that compared with automatic drilling,automatic drilling with low frequency vibration can improve the drilling quality of CFRP/ Ti laminates from the processing level.Finally,by optimizing the process parameters of CFRP/ Ti laminated low-frequency vibration automatic drilling,the modeling rationality of test data and the influence rule of process parameters on the aperture difference were analyzed from the three aspects of variance,response surface and comprehensive influence factor.And the optimal process parameter set was given to verify that the step hole defects can be effectively inhibited.更多还原