Research On Chip Formation And Temperature Field Distribution Of The Gun-Drilling Process Of 15-5PH Solid Solution Stainless Steel

Small diameter and long deep hole machining play an increasingly important role in national key industries such as aerospace,weapon and equipment,automobile,energy and,chemical industry.Especially for the hole processing of some difficult to process materials,the demand is higher and higher,such as all kinds of door guide holes in C919 aircraft,the holes used to install sensors in oilfield drilling equipment,the water holes of large-scale molds in automobile manufacturing and all kinds of long oil channel holes in engines,etc.Gun drilling is an important technology to realize the machining of small diameter and long deep hole.However,due to the small diameter and large depth of the hole to be machined,there are always problems such as poor machining quality and chip removal difficulties in gun drilling,and coolant is one of the most important factors affecting the above problems in gun drilling.Therefore,this paper takes the gun drilling of 15-5PH solid solution stainless steel as the research object and analyzes the mechanism of coolant on-chip forming and cooling through experiment and simulation.The main work is as follows:(1)Through the analysis of the chip forming process in gun drilling,combined with CFD fluid-solid coupling simulation and drilling test,the effect of coolant inlet pressure on chip forming is studied.The results show that the coolant will produce side curling effect on the chip,which will affect the curling radius,and then affect the length of the first fracture.With the increase of the inlet pressure,the degree of lateral curl increases first and then decreases,which is the smallest at 3 MPa;the increase of inlet pressure will increase the impact force and shear force of the fluid on the chip,which is more conducive to the "secondary fracture" and chip removal.(2)Based on the "microelement" method and the Third Wave AdvantEdge,the influence of process parameters on the temperature distribution and stress on the cutting edge of the gun drill is studied.The results show that the drilling temperature increases with the increase of the cutting parameters,and the maximum temperature is 0.02 from the cutting edge on the rake face;The radial force of gun drill decreases with the increase of cutting speed and increases with the increase of feed rate.Based on the temperature model of the rake face,the cutting force test is carried out to verify the effectiveness of the simulation results.(3)Based on the method of Fluid-Solid Coupling,the CFD simulation of cuttingedge cooling is carried out.By studying the distribution of temperature and surface heat transfer coefficient of the gun drill,the flow path of drilling heat is analyzed,and the influence of the inlet pressure of coolant and the angle of dub-off shoulder of gun drill on the cooling performance is studied through the CFD simulation test.The larger the inlet pressure and the smaller the angle of the shoulder angle,the better the cooling effect.