Tool Wear In High Speed Drilling Process Of Aramid Fiber Reinforced Plastics

Aramid Fiber Reinforced Plastics(AFRP)has superior properties such as high strength,high modulus,high toughness,and superior impact resistance,and is widely used in military,aviation,aerospace and other fields.Due to the need for connection and assembly between workpieces,drilling is the most important processing method for AFRP materials.However,due to defects in material structure anisotropy and poor thermal conductivity,the AFRP material can be easily worn and many machining defects occur during high-speed cutting.In order to,promote the development of cutting tool technology and high-speed cutting technology of Aramid Fiber Reinforced Plastics.This article uses carbide,TiCN coating and TiAIN coating tools to perform high-speed drilling experiments on AFRP materials.The axial force signal was used to characterize the tool wear.The process parameters were optimized and an empirical formula for the axial force was established.The influence of tool wear on the hole machining quality was analyzed.Finally,the tool life and tool wear mechanism were studied in depth.Research results show that:The process parameters have a significant influence on the axial force.The axial force decreases with the increase of the spindle speed and the helix angle of the tool,and increases with the feed per tooth and the tool tip angle.A two-dimensional regression model of axial force was established based on orthogonal test.The error between model prediction and actual result was less than 7.86%,which indicated that the reliability of the model was relatively high.Tool wear has a significant effect on the drilling performance of aramid fiber composites.In the initial stage of tool wear,the axial force and outlet tearing factor increase at a faster rate.Then the normal wear stage of the tool,both of them increase at a gentle rate.And in the sharp stage of tool wear,the axial force and outlet tearing factor increase at a rapid rate.There is a linear positive correlation between the amount of flank wear and the axial force.In the initial stage of tool wear,the pore wall roughness increases linearly,then decreases and fluctuates within a certain range.At the later stage of tool wear,the pore wall roughness increases non-linearly and sharply.At the same time,with the increase of tool wear,the micro-morphology of pore wall and chip morphology also changed significantly.The tool life test results show that the tool life curve can be divided into three different stages during the high-speed drilling process:initial wear stage,normal wear stage and abrupt wear stage.There are significant differences in wear rate and wear mechanism in each stage.Comparing the three tools,the TiCN-coated tool has the lowest wear degree and the hole has the best machining quality,which is more suitable for high-speed drilling of aramid fiber.Based on the tool life test,the wear mechanism of the coated tool was analyzed.The wear degree of the front and back flank of the tool was different.The flank wear was more severe than the rake surface.The wear mechanism of the rake face of TiCN-coated and TiAlN-coated tools was dominated by cohesive wear with slight oxidative wear.The failure modes were coating spalling,micro-disintegration,and crater wear.The flank wear mechanism is dominated by abrasive wear,adhesive wear,and oxidative wear.The major failure modes of the flank are failure of the coating,exfoliation of the tool matrix material,and generation of a large number of buildups,but no crater wear has been observed.