Research On Design Of Negative Chamfer Of Superhard Turning Tool And Grinding Process

At present,superhard material tools(such as PCD,PCBN tools,etc.)have been widely used in various industries of machining,such as automobile,aircraft and ship,many important parts of the cutting process are inseparable from superhard tools.In the process of cutting edge grinding,superhard tools will appear different degrees of micro notches and wear,which makes the life of superhard tools sharply reduced.Making the edge of superhard tools into negative chamfering shape is an important method to improve the life and machining quality.However,because of the existence of the tip arc,chip removal interference will occur during cutting,which will cause a sharp increase in cutting force and cutting heat,thus causing serious damage to the super hard tool.Therefore,in this paper,the typical PCD tool is taken as the research object,and the mechanism of the gradual negative chamfering tool is studied by mathematical modeling method.The influence of the gradual negative chamfering angle on the cutting edge temperature,tool wear,machined surface roughness and micro morphology of the workpiece is studied by combining the finite element analysis and turning test.The gradual negative chamfering tool with the optimal geometric parameters is selected to improve the surface quality of the workpiece after turning.First of all,through the change rule of the shear angle of different negative chamfering tools,the influence rule of the chamfering angle of negative chamfering tools on chip deformation under the same gradual angle is obtained.Based on the principle of the minimum energy dissipation of the unit tool,the chip removal interference problem of the fixed negative chamfering tool is analyzed theoretically,and the influence rule of the edge angle of the fixed negative chamfering tool on the chip removal interference phenomenon is finally obtained.In order to reduce the influence of cutting edge angle on chip removal,the mathematical model of gradual negative chamfering tool is established based on the principle of minimum energy dissipation of the whole tool,and the influence of the cutting edge angle and inclination angle of gradual negative chamfering tool on chip removal is analyzed.Secondly,the process of turning is simulated by DEFORM-3D finite element simulation software.Using the function of point tracking in software post-processing,the flow direction of chip is analyzed.According to the results of data extraction,the influence of different gradient angles of gradient negative chamfering tools on the average main cutting force,tool wear and tool temperature near the cutting edge is compared,and the optimal gradient angle parameters in simulation test are obtained.Finally,the grinding mechanism of PCD tools is described,and the factors that affect t he grinding quality of PCD tools are summarized.Then select the appropriate wheel binder and wheel speed,and use the AGATHON COMBI PLUS tool grinder to grind out the fixed value negative chamfering tool.Seven gradual negative chamfering tools with gradient angle range of 10 °-15 °,10 °-20 °,10 °-25 °,10 °-30 °,15 °-20 °,15 °-25 ° and 15 °-30 ° and negative chamfering width of 0.1mm are grinded by manual grinding method.The Angle and width of the blade are examined by the depth-of-field microscope produced by KEYENCE,and the chamfering Angle is achieved after the blade is polished and repaired The 7075 aluminum alloy cylindrical bar is machined with the gradual negative chamfering tool after grinding under the same cutting conditions.By measuring the temperature near t he cutting edge,the surface roughness and the micro morphology of the workpiece,and the energy spectrum detection of the defects,the influence of the gradient angle of the gradient negative chamfering tool on the surface quality is analyzed comprehensively,so as to obtai n the optimal gradient negative chamfering parameters of the turning tool.