The Influencing Mechanism Of Original/Modified Waste Vegetable Oil Mixture And Bio-inspired Tool Surface Microstructure On Interrupted Cutting Performance

The mechanical impact and thermal impact can easily cause tool wear during the interrupted cutting process,thereby affecting the surface quality of the workpiece.The existing studies indicate that vegetable oil-based lubricants are green and have good lubricating properties.Therefore,the application of vegetable oil-based lubricants to the interrupted cutting process can effectively reduce friction and improve cutting performance.The microstructures of some creatures have the function of storing solution.Design and fabrication of this kind of microstructure on the rake face of the tool can improve the cutting performance of the tool.Thus,the combination of vegetable oil-based lubricant and bio-inspired tool surface microstructure is of great significance for improving cutting performance.In this context,the present work investigated the influencing mechanism of original/modified waste vegetable oil mixture and bio-inspired tool surface microstructure on interrupted cutting performance.The same amount of nanoparticles was added to the mixture of the original vegetable oil and the modified waste vegetable oil for preparing nanofluid lubricant.This work analyzed the effects of the volume ratio R_V of the original vegetable oil to the modified waste vegetable oil on cutting performance.Taking the storage principle of honeycomb geometry into account,the present study fabricated hexagonal bio-inspired microstructures with different depths on the tool surface.The effects of the depth d of the bio-inspired microstructure on the cutting performance were analyzed under the condition of using lubricant.The combined effects of the proposed nanofluid lubricant and the proposed bio-inspired tool surface microstructure on cutting performance were revealed in this study.The optimum combination of volume ratio R_V and microstructure depth d were determined on the basis of the experimental cutting performance.This paper focused on the cutting performance indicators such as friction coefficient COF,cutting force F,tool wear volume V_w and workpiece surface roughness Ra_at.The main research contents and conclusions are as follows:（1）Modified waste palm oil was prepared in this work.Then,the original palm oil and the modified waste palm oil were mixed together.The volume ratio R_V of the original palm oil to the modified waste palm oil was set to be 0:1,0.25:1,0.5:1,0.75:1,1:1.Then,five kinds of nanofluids were obtained by adding an equal amount of nanoparticles to the base oil.The viscosity V_b and the residual amount R_o of these five kinds of base oil were analyzed since the lubricating properties of the nanofluid mainly depended on thet base oil.The results showed that the viscosity V_b of the base oil showed a decreasing trend with the increase of temperature.Larger volume ratio R_Vcaused higher viscosity V_b of the base oil at the same temperature.The residual amount R_o of the base oil decreased as the temperature increased.The residual amount R_o of the base oil increased as the volume ratio R_V grew for the same temperature.（2）Inspired by the geometric structure of the honeycomb,bio-inspired tool surface microstructure was fabricated by nanosecond laser.Bio-inspired tool surface microstructure with five different depths（15μm,19μm,23μm,27μm,31μm）can be obtained via the change of the laser parameters.The oil storage tests showed that the oil storage capacity of the microstructure gradually increased and the oil loss rate gradually decreased with the increase of the microstructure depth d.The oil loss rate tended to be stable when the microstructure depth d increased over 23μm.（3）The changes of the viscosity V_b and the residual amount R_o of the base oil during interrupted cutting were analyzed based on the established model of cutting temperature.The results revealed that both the viscosity V_b and the residual amount R_oshowed a decreasing trend in the cutting stage and an increasing trend in the air cutting stage.The viscosity V_b and the residual amount R_o decreased rapidly in the early cutting stage.In contrast,both of them increased rapidly in the early stage of air-cutting.The effects of the oil mixture and the bio-inspired tool surface microstructure on the cutting performance were separately studied through friction tests and intermittent cutting tests.The friction coefficient COF,the cutting force F,the tool wear volume V_w and the workpiece surface roughness Ra_at all decreased with the increase of volume ratio R_V.The volume ratio R_V of 1:1 was found to be the optimum.In addition,the cutting performance first became better and then tended to be worse as the depth d of the bio-inspired microstructure increased.The bio-inspired microstructure with a depth of23μm was the best choice.（4）The combined effects of the vegetable oil mixture and the bio-inspired tool surface microstructure on the cutting performance were revealed in the present study.The volume ratio R_V of 0.75:1 to 1:1 and the microstructure depth d of 21μm to 25μm formed the optimal parameter zone for achievement of relatively good cutting performance.