Experimental Research Of Drilling The Composite Materials With Candlestick Drills

With the wide application of fiber reinforced composites,the high-quality hole-drilling technology for the composites has become a research focus in the fields of aircraft manufacturing and others.As a kind of drill with special structure,the candlestick drills has various advantages when drilling the composite materials.And it has the potential to become a low-cost,high-efficiency drilling tool.The thrust force was often used by the researchers to analyze various damage phenomena during drilling.Compared to the thrust force signals,vibration signals are more sensitive to the change of drilling process and the tool structure parameters and has more advantages in realtime monitoring of tool condition.However,the vibration signals were easily affected by the noise and other external factors.As a result,it is difficult to reflect the real drilling situation,and related research still needs to be improved.When optimizing processing parameters,due to the particularity of composite materials,there will be the coupling effect between the processing parameters and tool parameters on the exit damage.This phenomenon will make it difficult to predict the impact of a certain parameter on the size of the exit damage and increase the difficulty of selecting the optimal parameters.In this paper,aiming at these problems in drilling process,the method of combining theory with experiment is adopted.The main contents are as follows.1.The theory of drilling composite materials with candlestick drills is improved.The influencing factors of the exit damage were divided into the pushing effect,cutting effect and the drilling temperature,these factors exist at the same time and influence each other.This part also pave the way for the following study.2.The high frequency vibration signals in drilling process are reshreshed and analyzed.The signal is sensitive to the change of drill tip structure and drilling process,and can be used as a powerful tool to detect tool status and judge the size of exit damage when using the candlestick drills.3.Through the orthogonal experiment,the coupling effect between feed speed,spindle speed and the clearance angle of the outer cutting edge is studied.The reason and mechanism of this phenomenon are analyzed theoretically.The theoretical basis for optimizing the processing parameters is provided and the optimum parameters in the experiment are given.