Optimization Of Bionic Microscopic Structure Of Interrupted Cutting Tool Based On The Rheological Characteristics Of Flow Zone

In the intermittent turning process,the interaction between tool and workpiece generates a certain amount of energy consumption.The tool is prone to fracture due to fierce mechanical and thermal impacts.The microscopic structure of the tool surface is of great significance for improving the tool performance in intermittent turning.Studies have shown that the micro-structures of certain biological surfaces can reduce their resistance to movement.The micro-structure of the biological surface can be referred in the design and preparation of the microscopic structure on the tool rake face.The interaction between the tool and the metal cutting layer has a great influence on the intermittent turning performance of the tool.Studies have shown that metal cutting layer has solid-like characteristics,Newton-like fluid characteristics and non-Newtonian fluid characteristics.Taking into account the solid-like characteristics,the Newton-like fluid characteristics and the non-Newtonian fluid characteristics of the metal cutting layer,the bionic microscopic structures of the tool surface are designed and prepared considering the micro-structures of the biological surface.This provided the possibility to effectively reduce the specific cutting energy and tool wear in intermittent turning.The non-Newtonian fluid characteristics of the flow zone in the second deformation zone were revealed.Bionic microscopic structures were designed and manufactured on the tool rake face based on the leg cuticle of catharsius molossus,the scale of carassius auratus and the cuticle of the chela of Procambarus clarkia.The feedback mechanism of non-Newtonian fluid characteristics of the bionic micro-structure pattern on the tool surface was studied based on the non-Newtonian fluid characteristics of the flow zone.The optimal bionic micro-structure pattern of the tool surface was determined.Theoretical calculation methods for specific cutting energy and tool performance indicator were proposed.The effects of the laser beam angle and the curvature radius of the bionic micro-structure element on the specific cutting energy and tool wear were studied based on the optimal bionic micro-structure pattern.The goal of low energy consumption and low wear was proposed.The angle of the laser beam and the curvature radius of the bionic micro-geometric structural elements were optimized to determine the optimal combination of angle parameters and radius parameters.The following researches were conducted:(1)The non-Newtonian fluid characteristics of the flow zone in the second deformation zone were analyzed.The non-Newtonian fluid characteristic index was proposed.Taking into account the solid-like characteristics,the Newton-like fluid characteristics and the non-Newtonian fluid characteristics of the second deformation zone,the leg cuticle of catharsius molossus,the scale of carassius auratus and the cuticle of the chela of Procambarus clarkia were observed.It was found that the main micro-structure element of the leg cuticle of catharsius molossus was circular micro-dimple.The main micro-structure element of the scale of carassius auratus was arc-shaped microscopic groove.The main micro-structure element of the cuticle of the chela of Procambarus clarkia was crescent-shaped micro-pit.Pattern A was set to have no micro-structure.Bionic micro-structure patterns B,C and D were designed and prepared considering the solid-solid contact state,solid-Newtonian fluid contact state and solid-non-Newtonian fluid contact state of the tool rake face and the second deformation zone.(2)Bionic micro-structure patterns B,C and D were compared with no micro-structure pattern A.The feedback effect of bionic tool surface micro-structure pattern on the non-Newtonian fluid characteristic,cutting force and tool temperature was analyzed according to the non-Newtonian fluid characteristic index of the flow zone,intermittent turning experiments and intermittent turning simulations.Studies have shown that micro-structure patterns B,C and D could effectively reduce the non-Newtonian fluid characteristic index,cutting force and tool temperature compared with pattern A.The micro-structure pattern D was most efficient in reducing non-Newtonian fluid characteristic index,cutting force and tool temperature.Micro-structure pattern D was the optimal.(3)The theoretical models of specific cutting energy and tool performance indicator were established.The influences of laser beam angle and curvature radius of bionic micro-structure element on non-Newtonian fluid characteristic,theoretical calculation results of specific cutting energy and tool performance indicator were analyzed based on the optimal micro-structure pattern.The experimental specific cutting energy and tool flank wear verified the calculation results of specific cutting energy and tool performance indicator.The results showed that as the angle of the laser beam changed from 30o to 90o,the curvature radius of the bionic micro-structure element changed from 45?m to 85?m,non-Newtonian fluid characteristic index,theoretical specific cutting energy,experimental specific cutting energy,tool performance indicator and tool flank wear both decreased first and then increased.Non-Newtonian fluid characteristic index had a clear corresponding relationship with theoretical specific cutting energy and tool performance indicator.Smaller non-Newtonian fluid characteristic index corresponded to smaller theoretical specific cutting energy and smaller tool performance indicator.(4)The laser beam angle and the curvature radius of the bionic micro-structure elements were further optimized considering the optimal micro-structure pattern based on the above research.The combined effects of the laser beam angle and the curvature radius of the bionic micro-structure element on the theoretical calculation of specific cutting energy and the tool performance indicator were analyzed.The theoretical calculation was verified by experimental research results.It was found that with the increase of the laser beam angle and the curvature radius of element,the theoretical specific cutting energy and tool performance indicator both decreased first and then increased.In the laser beam angle range of 50o?70o,the element curvature radius range of 55?m?70?m,the relatively low specific cutting energy and tool performance indicator could be obtained simultaneously.The optimum parameter combination was laser beam angle 60o and element curvature radius 65?m.At the optimum parameter combination,low energy consumption and low tool wear could be achieved.