Experimental Study On High-speed Drilling Of Ti6Al4V With Micro-textured Internal Cooling Twist Drill

High-speed cutting has become the mainstream development direction of the machinery manufacturing industry.The tool wear is still the main technical bottleneck of high-speed cutting technology.The internal cooling twist drills have outstanding performances in cooling and lubrication,prolonging tool life,and have a great potential for application in high-speed drilling of difficult-to-machine materials.The surface texture can effectively reduce friction and wear,and provide a new method for research on tool antifriction and lubrication technology.In this paper,from the perspective of reducing the friction and temperature of the knife-work/knife-chip contact area,the design of controllable surface textures for the front and back flank of the internal cold twist drill is proposed,and the internal cooling lubricating technology is used to simulate the finite element simulation.And research and other methods to explore the cutting performance and wear mechanism of high-speed drilling Ti6Al4 V with micro-textured internal cold twist drills,and put forward new ideas for high-speed drilling of titanium alloys.The main research content is as follows:Firstly,Deform-3D was used to simulate the drilling process of four different types of micro-texture twist drills(NT,TFP,TFV,TFK)on the rake face.The drilling force,temperature,depth of bit wear of different tools were compared and analyzed.The simulation results show that: TFP tools have the best overall performance.Compared with NT twist drills,the average cutting force,maximum temperature and maximum wear depth of the rake face are reduced by 4.22%,4.31%,and 46.82,respectively.Based on this,the same micro-texture was fabricated on the flank face of the twist drills,and the drilling performance of the TBP tool was simulated and analyzed.The results show that the average cutting force,the maximum temperature and the maximum wear depth of rake face of TBP tool are reduced by 9.93%,3.14% and 38.11% compared with NT twist drill,respectively.According to the simulation results,the groove micro-textures parallel to the main cutting edge were fabricated on the rake face,flank face,and both rake face and flank face(TF,TB,TFB)of the YG6 carbide internal cooling twist drills by a laser marking machine.Secondly,a reasonable cutting amount of the high-speed drilling test of Ti6Al4 V was determined through pre-drilling tests,the experiments were conducted on the cutting force,tool durability,cuttings shape,and the surface roughness of the hole surface used the traditional non-textured internal cooling twist drills and the grooved micro-texture internal cooling twist drill in different faces,and the mechanism of the micro-texture of different faces on the cutting performance of the tools ware analyzed.Studies have shown that the micro-textured internal cooling twist drills(TF,TB and TFB)have lower cutting forces,longer tool durability,and the surface roughness of the hole increases,but It meets the requirements of semi-finishing on the high-speed drilling(V=62.8 m/min);the micro-texture on the rake face(TF,TFB)have a significant effect on the curling degree of the cutting,the spiral pitch of the chip is significantly reduced,the degree of curling is obviously increased,the phenomenon of cutter tangling disappears,and the chip breaking capacity is improved.Finally,the wear patterns of the rake,flank,chisel edge and secondary cutting edges of the non-textured internal cooling twist drills and the micro-textured internal cooling twist drills were compared,and the wear mechanism of the tool was studied.The results show that when the internal cooling twist drill drills Ti6Al4 V at high speed,the main damage forms of the tools mainly include the chipping of the main cutting edge and the secondary cutting edge,the bue of the transverse edge,the bonding of the tool material,and the mechanical failure of the edge zone,broken off,etc.The wear of the tool is mainly based on the wear of the blade surface.The wear mechanism is mainly the adhesive wear and abrasive wear.The oxidation wear and diffusion wear are relatively minor.The micro-texture is placed on the rake face can not only increase the atomic distance between the contact surfaces in the micro-texture area,but also help the cooling liquid penetrate into the close contact area,which can significantly reduce the adhesive wear,thereby reduces the bonding on the rake face.and chipping of the main cutting edge,secondary cutting edge,and landslide;At the same time,the micro-texture can catch the abrasive particles and improve the abrasive wear on the rake face.The flank face is close to the inner cooling hole,and the tool surface adhesion phenomenon is relatively slight compared to the rake face,but it is still dominated by adhesive wear.The flank face is placed into the micro-texture,which can improve the adhesion of the flank face.Coolant reaches the chisel edge and reduces bue.