| Carbon Fibre Reinforced Plastics(CFRP)with excellent performance is widely used in the aerospace field.With the development of science and technology,the application range of CFRP materials in automobiles,high-speed rail and other fields continued to application,its characteristics and advantages have been continuously demonstrated.In many cases,high-quality hole-making process is required for CFRP materials,but as a typical difficult-to-machine material,defects such as tearing and delamination are easy to occur during hole-making.The hole-making process parameters that are efficient and can avoid defects are the focus of many current studies At present,there are more references on the research of hole-making mechanism and drilling processes for CFRP with thickness of no more than 5mm,but the study of CFRP with thickness of more than 20 mm is less.Based on the helical milling hole-making technology,researches the hole-making process of CFRP with a thickness of 24 mm were studied in this paper.in order to meet the process parameter requirements of helical milling of robot end effectors.The main specific studies are as follows:Firstly,the study status of hole-making for CFRP material at home and abroad was summarized and the steps and methods of CFRP thick-section plate are formulated.Based on the cutting principle and milling kinematics theory,the mechanism and defects of CFRP hole making with thick section were analyzed.,Using ANSYS/LS-DYNA software to numerically simulate the spiral milling hole-making process of thick-section CFRP,the temperature distribution between the tool and the workpiece and the changing trend of the cutting force during the machining process were analyzed.The related factors affecting the quality of hole making are discussed,and the cutting force is modeled and analyzed,which provide a theoretical reference for the further study on hole-making process for thick-section CFRP material.Then,Based on the results of numerical simulations,an orthogonal experiment experiment scheme containing multiple levels of milling process parameters was designed and experimental research was carried out.With the experimental goal of minimizing the axial force of milling,the optimal parameter combination was obtained.According to optimal process parameters,micro-quantity lubrication(MQL),support pads,and step-by-step parameter hole-making schemes were proposed.The effects of the three states on the hole-making quality were studied,and the optimal hole-making scheme for thick-section CFRP was obtained.Finally,a hole-making verification experiment was performed for thick-seciton CFRP plates on the end effector of helical milling.The results show that the quality of hole exit,hole entrance,hole wall and hole diameter deviation can meet the technical requirements.According to the hole-making mechanism analysis,process simulation,and experimental research,the influence rules of related parameters were found,and the final optimal hole-making process was obtained. |
