Study On Vibration Assisted Drilling Of Carbon Fiber Reinforced Plastic And Titanium Stacks

CFRP/Ti stacks have been widely used in aviation industry.Carbon fiber reinforced plastic(CFRP)and titanium alloy(Ti)have very different mechanical characteristics.The low thermal coefficient and elastic modulus of Titanium alloy led to long spiral chips with high temperature,which caused surface scratches of machined hole and damaged the CFRP layer.According to the theory of vibration processing,a combined frequencies vibration assisted drilling machine was designed and manufactured,which could realize the ultrasonic vibration and low frequency vibration of the cutter along the axial direction.A set of automatic control system was set up to realize the precision of drilling parameters.In view of the deformation of the springs during low frequency vibration assisted drilling,the displacement and low frequency amplitude of the tool were tested and analyzed.In this paper three types of drilling methods: traditional drilling,rotary ultrasonic assisted drilling and low-frequency vibration assisted drilling were compared and analyzed from the following points of view,such as: cutting temperate,thrust force,torque,chip morphology and drilling quality.It was shown that compared with conventional drilling,both the ultrasonic vibration and low frequency vibration assisted drilling could reduce the temperature and cutting force.But the low frequency vibration assisted drilling method could distinguished break the cutting chips belts of titanium alloy material to small chips.Due to this reason,the cutting temperature could be reduced to 45%.At the end,the CFRP layer damages caused by over heated cutting chips belts of titanium alloy could be avoided,and the drilling quality could be improved to a great deal.