Study On CFRP Drilling Performance Of Multilayer Brazing Sleeve Drill

Carbon fiber reinforced composites(CFRP)have high specific strength,high specific stiffness and wear resistance,which are widely used in aerospace,automobile,new energy and other fields.Carbon fiber reinforced composites(CFRP)should be connected with other structural parts in use,and the hole-making process required for the connection has become an indispensable key technology.Due to the characteristics of low interlaminar shear coefficient,anisotropy and poor thermal conductivity,the drilling process requires higher hardness,strength,wear resistance and tool geometry.In this paper,a multi-layer brazed diamond sleeve drill has been developed by combining the moulding technology and high temperature brazing technology.CFRP drilling experiments have been carried out by using the multi-layer brazed sleeve drill.The main contents are as follows:A multi-layer brazed diamond working layer with porous structure was prepared by using copper-Sn-Ti brazing powder,diamond and pore-forming agent ammonium bicarbonate as main raw materials.The pore variation law,pore morphology and distribution,as well as the effect of porosity on flexural strength of the working layer were analyzed.Diamond sleeve drill.The experimental results show that the porosity increases with the increase of pore-forming agent content.When the pore-forming agent content increases from 0% to 16%,the porosity increases from 6.0% to 44.5%.When the pore-forming agent content is higher than 12%,the porosity is easy to connect.The flexural strength decreases with the increase of pore-forming agent content.When the pore-forming agent content increases from 0% to 16%,the flexural strength decreases from 436 MPa to 123 MPa.CFRP drilling experiments were carried out with multi-layer brazed sleeve drill and common sintered sleeve drill,respectively.The changing trends and causes of outlet temperature,drilling force,torque,tearing factor and roughness with processing parameters were analyzed.The drilling quality of the two sleeve drills was compared.The results show that the axial force and torque decrease with the increase of spindle speed and increase with the increase of feed speed.Temperature decreases with the increase of feed speed,and increases with the increase of spindle speed.Improving spindle speed and reducing feed speed can reduce drilling defects.The pore of multi-layer brazed sleeve drill makes it sharper than that of common sintered sleeve drill.High efficiency and low damage drilling can be achieved through stable self-sharpening process.