Near-dry Deep Hole Boring System Construction And Simulation Analysis For Chip Removal

With the structure of the deep hole parts is more and more complex,the requirements tocutting machining properties and accuracy of workpiece material are increasingly high,relying solely on the deep hole drilling fails to meet the above requests.In order to improvemachined surface quality,it often needs semi-fine or fine boring after deep hole drilling.It willinevitably encounter the classic problems (cooling lubrication and chip removal) in the boringprocessing. Traditional cooling lubrication and chip removal are realized by the circularcutting fluids with large amount of flow.However,as people’s awareness of environmentalprotection is more and more strong,the requirements of workers to production environmentare increasingly high,obviously,this manner has been already out of keeping with thetimes,and using green cutting technology will be the future development trend.Based on reviewing the development of green cutting technology in the world,the paperwill apply near-dry machining technology by means of the cooling and lubricating method ofthe MQL in deep hole boring processing,the cooling and lubricating system of near-dry deephole boring is constructed, meanwhile,combined with high flow rate of air blowing to thecutting area to improve chip removal through the annular gap between the outer surface ofboring bar and machined surface. It not only solves the classic problems in deep holeprocessing,but also conforms to the greenization and efficiency of the machining,and alsoprovides a new research direction for the deep hole processing.The main contents in the paper are as follows:the processing characteristics of deep holeboring are studied,the machining mechanism of near-dry deep hole boring is described,a newcooling and lubricating system of near-dry deep hole boring is constructed. According to thechip removal system,firstly,the numerical analysis software FLUENT of computational fluiddynamics(CFD) is used to simulate the flow status of single-phase air flow, the pressuredistribution, velocity distribution and turbulent distribution are obtained. It shows that the blind areas of chip removal are located in the front and bottom of boring cutter end face.Secondly，air-chip two-phase flow is simulated by using FLUENT software，the particletrajectory and law in steady-state is obtained. Finally，it qualitatively analyzes the influencecaused by two factors (chip equivalent diameter and inlet pressure) to the motion law of thechip in the flow field. It shows that the bigger dimension of chip particles diameter is,the lesswill the time that chip collided with the pipe wall firstly costs. when the equivalent diameteris bigger, the whole movement only appear in the bottom of the pipe. Increasing inlet pressurewill decrease the time the chip discharged outside the pipe, but if it is continued to increasewhen increases to a certain value, there is not much effect. Under the smaller or too muchpressure conditions,there are many times of chip collided with tube wall in the deep hole pipe,while the less in a middle value, the value can be obtained by calculating the suspensionvelocity of chip. Although there will be deviations, it can provide theoretical basis fordetermining the conditions of chip removal reasonably.