Research On Chip Breaking And Chip Removal Technology Of High Efficient Deep Hole DF System

With the continuous development of the equipment manufacturing industry,new materials,multiple varieties,and high-value difficult-to-machine deep-hole parts continue to emerge.These deep-hole parts put forward higher requirements on the depth,aperture size,surface quality,machining accuracy and machining efficiency of the machining holes.However,the problem of chip interruption and chip removal in deep hole machining has always been a key problem affecting the quality of deep hole machining.In the current deep hole processing method,the DF system adopts a negative pressure chip removal device,which improves the chip removal efficiency to a certain extent.But because it uses a constant cutting speed for cutting,the thickness of the chips is consistent,and it is not easy to break the chips.In terms of chip removal,DF system uses a constant pressure and constant flow oil supply method,resulting in insufficient chip removal power and easy Chip blocking occurs.This paper focuses on the problem of chip breaking and chip removal in the deep hole DF system,firstly studies the chip breaking form and the generated chip form of the deep hole DF system.Based on the flow characteristics of cutting fluid in the chip removal pipeline,a mathematical model of the flow of cutting fluid in the chip removal process is established,and the reasons for chip blockage and common methods to solve the problem of chip removal are analyzed.According to these methods,a parallel scheme is proposed:(1)chip breaking: based on the processing characteristics of vibration cutting theory,the chip thickness generated by the workpiece changes,the chip breaking process is accelerated,and "C-shaped short chip" is formed,and the chip removal difficulty is reduced.(2)chip removal: based on the characteristics of pulse fluid,under the action of pulse oil supply device,the flow of cutting fluid in the front channel produces pulse type change,improves the chip removal power of cutting fluid,accelerates the chip breaking process,enhances the disturbance effect of cutting fluid,speed up the chip removal,and relives the occurrence of chip blocking phenomenon.Then,the mechanism of vibration drilling is studied,the mathematical model of vibration drilling chip breaking is established,the hydraulic dynamic vibration drilling device is designed,and the simulation test is done by using DEFORM-3D software to compare the chip breaking effect and chip shape of traditional drilling and different frequency vibration drilling.It is concluded that vibration drilling can effectively improve chip breaking efficiency and obtain ideal chip shape,and the influence of vibration frequency on vibration drilling effect is analyzed;In the aspect of pulsed negative pressure chip removal,the negative pressure chip removal mechanism of DF system was studied,the pulsed chip removal device was designed,and the mathematical model of pulse valve was established.Through experiments,it was verified that the pulsed device could change the flow rate of cutting fluid in the chip removal pipeline and produce the effect of pulsed chip removal.Using ANSYS software,the simulation experiment is set according to the flow variation range when the rotation frequency of the regulator is 0.67 Hz.By analyzing the simulation results,it is found that when the regulator works,the flow velocity of cutting fluid in the drilling area and inside the drill pipe will constantly change,and the change of flow velocity will produce different size of impact force,strengthen the disturbance effect of cutting fluid,accelerate the chip breaking and discharging process,and effectively alleviate the chip blocking phenomenon.The above research proves that vibration drilling and pulse chip removal can enhance the chip breaking and chip removal ability in deep hole machining process,relieve chip blocking phenomenon,and improve the deep hole machining efficiency.