Research On Grinding Quality And Removal Mechanism Of Polycrystalline Diamond Tools

Polycrystalline diamond(PCD)is an ideal tool material with high hardness,high wear resistance and good toughness.PCD tools are currently mainly used in aerospace,automobile manufacturing,precision medical devices and other fields.However,due to the high hardness and brittleness of diamond,PCD tools are prone to edge defects and surface disfigurement in the grinding process.The grinding quality is difficult to improve,which has seriously hindered the further promotion of PCD tools.In order to obtain PCD tools with high grinding quality,the grinding process parameters were optimized by establishing the grinding quality evaluation system,and the removal mechanism of PCD was analyzed in depth.The evaluation system of PCD tool grinding quality was established,and the weight coefficient of each evaluation index were determined based on the test.The grinding quality of PCD tools was evaluated with cutting edge radius,cutting edge defect and flank roughness.The cutting test was designed to explore the influence of each evaluation index on the cutting performance of PCD tools,and the weight coefficient of each evaluation index on the grinding quality was set.Based on the grinding test,the influence of grinding process parameters on each evaluation index was determined,and the grinding process parameters were optimized to improve the grinding quality.The orthogonal test of grinding process was designed by using the constant pressure grinding process of DCMT11T304 tools.The type of diamond grinding wheel,grinding wheel speed and worktable setting pressure were selected as independent variables to explore the influence of cutting edge radius,cutting edge defect and flank roughness.The selection of process parameters was optimized.The results show that the worktable setting pressure has the most significant effect on cutting edge radius.The diamond grinding wheel has the most significant effect on cutting edge defect.The grinding wheel speed has the most significant effect on flank roughness.PCD tools with high grinding quality can be obtained by using 3000# ceramic-based diamond grinding wheel,1000 r/min grinding wheel speed and 170 N worktable setting pressure.The grinding quality of CTB010 tools obtained under this parameter combination is as follows : the cutting edge radius is less than 8μm,the cutting edge defect is less than 7 μm,and the flank roughness is less than 0.050 μm.The grinding quality of Compax 1600 tools obtained under this parameter combination is as follows : the cutting edge radius is less than 7 μm,the cutting edge defect is less than 6 μm,and the flank roughness is less than 0.050 μm.Scanning electron microscope and surface profiler were used to observe the flank surface of PCD tool obtained by grinding process test,and the removal mechanism was analyzed in depth.The results show that the removal mechanism of PCD is mainly divided into micro cracking,intergranular fragmentation,thermochemical reaction removal,engraving function and sliding friction.When the pressure is set to 70 N,the removal mechanism is mainly sliding friction and thermochemical reaction removal,and the interaction between the two achieved PCD removal.When the worktable setting pressure is set to 170 N and above,the removal mechanism is mainly micro cracking,and the intergranular fracture can accelerate the process of micro cracking.Smaller cutting edge radius,cutting edge defect and smoother surface of PCD can be obtained by micro cracking under the 1000 r/min grinding wheel speed and the 170 N worktable setting pressure.The research in this paper effectively improves the grinding quality of PCD tools and provides a reference for its production practice.