Integrated Tool Design And Process Parameters Optimization For The Drilling-reaming-countersinking Of Al/Ti Laminated Structures

With the development of the aviation industry,the demand for new aircraft with excellent performance continues to increase.Many technologies require further research and innovation such as aircraft structural design,new materials,manufacturing processes,and cutting tool.Aluminum alloys and titanium alloys are widely used in aircraft assembly manufacturing because of their superior physical and mechanical properties.However,as the dual requirements for lightweighting and structural performance of aircraft have increased,traditional single-layer materials cannot meet the requirements.A laminated structure formed by superimposing two kinds of materials with different properties is used at home and abroad.This structure can simultaneously possess the advantages of high specific strength,high specific rigidity,good fatigue resistance and strong designability of both materials,which can greatly reduce the weight of the aircraft structure.Laminated structures are widely used in aircraft components such as aircraft wings,skins,and fuselage panels.However,drilling of dissimilar materials like aluminumalloy and titanium alloy stack is a difficult task because of the different machining properties.To improve both the manufacture and the assembly process quality and efficiency,one single drilling operation is essential to drill all stack materials instead of drilling each layer material separately.The traditional manual hole-making not only has low hole making efficiency,but also has poor hole making precision.There are still some problems that seriously restrict the improvement of hole making efficiency and cost reduction.For example,the hole making process needs to replace the cutting tools for drilling,reaming,and countersinking stages,the difficulty in chip breaking,the difficulty of burr control,and the short tool life.The mechanism of drilling for aluminum/titanium(Al/Ti)laminated structure is studied firstly.Based on the single-factor tests for drilling single-layer materials and multi-layered material structures,the hole-making mechanism of laminated structures was studied from four perspectives:the cutting mechanism of hole-making,the chip forming mechanism,the burr forming mechanism,and the dynamic characteristics of the hole making process.Based on the classification of chip morphologies and burr-types,this paper revealed the influence of pore process parameters and chip morphology,burr height,and dynamic characteristics.Research on the influence of tool structure on the chip morphology,burr height,cutting force and hole-accuracy based on the hole making test of different structural tools.The principles of selection of tool angles and tool materials in the drilling,reaming,and countersinking process are presented.The designed integrated tool was used to study the characteristics of each parameter in the hole-making process of aluminum/titanium laminate structure experimentally,and the tool was evaluated.Based on the study of the main damage types of the conventional hole-making tools,the life of the integrated tool is evaluated from the perspective of the axial force and the hole-diameter to ensure the stability and reliability of the new tool.The wear of the cutting edge of the new integrated tool after drilling 200 holes was studied.An optimized process parameter range was put forward for the integrated tool,based on the research of drilling aluminum alloys,titanium alloys and Al/Ti laminated structure.