Study On Stacked Hole Machining Of CFRP/Al Based On Special Machine Tool Of Orbital Drilling

With the progress and development of advanced aviation manufacturing technology,the stacked structure composed of integral CFRP panels and aluminum alloy is widely used on aircraft,which greatly improves the overall performance while reducing the weight of aircraft.However,in the processing of CFRP/Al alloy joint holes,because of the great difference of performance between the two materials,the traditional manual hole-making is inefficient,the hole position accuracy is poor,and the processing quality is difficult to guarantee,which seriously affects the assembly accuracy and efficiency of aircraft.Therefore,it is an urgent problem in the current aviation component digital assembly manufacturing to realize the high quality and high efficiency hole-machining of CFRP/Al alloy stacked structure.Based on the technology of orbital drilling holes,this paper studies the technology strategy of high efficiency and high quality automatic drilling for CFRP/Al alloy stacked structure.Firstly,the automatic orbital drilling machine tool system is constructed.the structure and characteristics of the special machine tool for hole machining and the end-effector of orbital drilling in the system are introduced in detail.Then,based on a certain type of engineering field application,the specific technological process of stacked automatic hole machining of CFRP wallboard and aluminum alloy is worked out.For realizing system automation hole machining,it is the premise to ensure the positioning accuracy of machine tool system.In order to realize the accurate positioning of the special machine tool for hole-machining,the kinematics model of the special machine tool system is established,the forward and reverse solution of kinematics is carried out,and the key kinematics parameters in the model are measured and calibrated by using the laser tracker measurement system.Subsequently,it is verified by experiments about the accuracy of the kinematics model and kinematics parameters of the machine tool,which lays a foundation for ensuring the accuracy of the hole position in the automatic hole machining of the wing.The CFRP/Al alloy stacked orbital drilling hole test is carried out by using automatic orbital drilling system,the hole diameter accuracy and hole wall quality of laminated holes are analyzed,and it is found that the shrinkage of CFRP holes is the main cause of excessive deviation between CFRP and Al alloy holes,the quality change of CFRP hole wall with tool wear is also studied.This paper analyses the shrinkage hole mechanism of CFRP,establishes the force model of the flank of the tool side edge and the CFRP rebound area,and obtains the influence law of the flank angle of the tool side edge on the CFRP rebound.In order to effectively control the quality defects of CFRP/Al alloy stacked orbital drilling hole,based on the results of CFRP shrinkage hole mechanism analysis,the flank angle of tool side edge is optimized,and the tool structure which can effectively suppress the shrinkage problem of CFRP material is selected by control test.Based on the optimized tool,this paper takes the accuracy of CFRP/Al alloy stacked aperture and the quality of CFRP hole wall as the optimization objective,carries out the optimization experiment of process parameters by using response surface method.Finally,the tool life test of CFRP/Al alloy stacked orbital drilling holes is carried out by using the optimized tool and process parameters,and the process optimization effect is verified,which effectively improves the quality of CFRP/Al alloy stacked holes.