| Carbon fiber reinforced plastic(CFRP)and aluminum alloys are widely used in the aerospace field due to their advantages.The laminated materials of CFRP and aluminum alloys are usually connected by bolts or rivets,and a large number of connecting holes need to be manufactured.In order to ensure the accuracy and efficiency of assembly,holes are usually made on the laminated material composed of two materials during this process.However,the better hole making process parameters are also different due to the different laminate sequence.In order to improve the hole-making quality of laminated materials,this topic proposes a study on helical milling of laminated materials of T700 CFRP materials and 2024 aluminum alloy.The burrs at the exit and entrance of the aluminum alloy material are reduced to ensure the accuracy of hole making.At the same time,some defects such as tearing,delamination and interlayer burrs of the CFRP material are avoided.Under this premise,the best combination of helical milling process parameters is found to improve hole making quality and the efficiency.The specific research content of this paper is as follows:(1)The current research status of laminated materials and CFRP materials are summarized and analyzed,the research status at home and abroad is analyzed,and the research content,technical route and research plan of laminated materials of CRRP and aluminum alloy are proposed.Based on the principle of cutting processing,the hole-making mechanism and cutting force on CFRP plate are mathematically analyzed;the milling kinematics theory is used to model the milling process of aluminum alloy,and the material removal mechanism is analyzed to provide the theoretical support for subsequent experimental research.(2)Determine the level value of the process parameters and the response surface method is used to carry out the test plan.Take the height of the burr between the laminated materials and the tear of the CFRP plate as the judging standard.The test results are analyzed and predict the best process parameter values for different laminate sequences.Verification tests are carried out based on the best process parameters obtained.The hole diameter deviation,the microscopic morphology of the hole wall,the height of the burr,the tear value of the entrance and exit,the axial force are compared with the hole making requirements to verify the accuracy of the best process parameters.(3)Based on the ABAQUS software,finite element simulation of CFRP and aluminum alloy material under the best process parameters is carried out to analyze the stress and strain conditions of the workpiece and the change trend of the axial force during the processing;the test axial force of the CFRP is 39 N and the simulated axial force is 45 N,the test result is 86.7% of the simulation result.It shows that ABAQUS software can be used to predict the helical milling process of laminated materials.(4)The results show that the diameters of hole making process of laminated materials with variable parameters under the best process parameters meet the H9 standard,the interlayer burrs of the aluminum alloy holes are less than 15?m,which is about 50% of the hole milling with fixed parameters.The tearing values of the entrance and exit of the CFRP board are required to meet the requirements,the axial force of the CFRP hole is less than 50 N,which is 70% of the fixed parameter milling;the axial force of the aluminum alloy is less than 60 N,which is the fixed parameter milling 83%.And it effectively reduces the sudden change of axial force between layers. |
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