碳化钨合金磨削仿真与工艺优化方法

Grinding simulation and process optimization method of tungsten carbide alloy

碳化钨合金因其具有高硬度、高耐磨性和高化学稳定性等优点,成为精密玻璃模压模具材料的首选。为了提高碳化钨合金模芯超精密磨削加工的表面质量,基于WC-6%Co碳化钨合金的物理特性,利用Abaqus建立磨削工艺仿真模型,分析了磨削深度、进给速度、砂轮转速及工件转速对WC-6%Co碳化钨合金磨削加工后表面粗糙度的影响规律,并讨论了磨削碳化钨合金的合理工艺参数范围。采用Taguchi法开展优化实验研究,确定出磨削碳化钨合金的最优工艺方案,在该方案指导下,完成了碳化钨合金的非球面模芯超精密磨削实验。最终得到的碳化钨合金模芯的表面粗糙度平均值为3.379 nm,验证了优化方案的有效性。

Objective Precision glass molding technology is the primary technology for the mass production of highprecision glass-based optical components.The ultra-precision machining of mold plays an essential role in the performance and quality of glass molding products.Tungsten carbide alloy has become the first choice of precision glass molding materials because of its advantages of high hardness,high wear resistance,and high chemical stability.In order to improve the surface quality of tungsten carbide mold core during ultra-precision grinding,the influence of critical process parameters on surface roughness was studied.Methods The influence of process parameters on surface roughness was studied by combining simulation and experiment,and process optimization was carried out.First,based on the physical characteristics of WC-6%Co tungsten carbide alloy,a grinding process simulation model was established by using Abaqus to simulate the effects of grinding depth,feed speed,wheel speed,workpiece speed and other process parameters on the surface roughness of WC-6%Co tungsten carbide grinding.The reasonable process parameters of grinding tungsten carbide alloy were determined by simulation.Then,the Taguchi method was used to optimize the grinding process of tungsten carbide alloy.Finally,under the guidance of the optimal process,the experiment of tungsten carbide aspheric mold core ultra-precision grinding was completed.Results and Discussions The simulation results show that the roughness increases relatively slowly when the grinding depth increases in the range of 1-1.8μm;When the grinding depth increases in the range of 1.8-2.6μm,the corresponding roughness growth rate is relatively large,and the reasonable grinding depth range is 1-1.8μm(Fig.5);With the increase of the feed speed,the surface roughness decreases first and then increases.The reasonable selection range of the feed speed is 0.5 mm/min-1.5 mm/min(Fig.6);There is a nonlinear inverse relationship between surface roughness and grinding wheel speed,so a larger grinding wheel speed should be selected as far as possible(Fig.7);the surface roughness decreases first and then increases with the increase of workpiece rotation speed.The reasonable selection range of workpiece rotation speed is 100 rpm/min-300 rpm/min(Fig.8).The process optimization experiments were carried out according to the process parameter range selected by the simulation results.The experimental results show that the surface roughness increases with the grinding depth(Fig.10);The surface roughness decreases first and then increases with the increase of feed speed and workpiece speed.It is proved that the simulation results have the same variation trend as the experimental results.Conclusions Aiming at the ultra-precision grinding process of WC-6%Co tungsten carbide alloy,the finite element simulation analysis and process optimization experiment were carried out,in order to improve the surface quality of tungsten carbide mold core ultra-precision grinding.Abaqus was used to simulate the effects of grinding depth,feed speed,wheel speed,and workpiece speed on the surface roughness during grinding.The optimization experiments were carried out according to the process parameter range selected by the simulationresults.The simulation results demonstrate that the surface roughness increases with the increase of grindingdepth,decreases first and then increases with the increase of feed speed and workpiece speed,and decreases withthe increase of grinding wheel speed.The analysis and comparison of simulation and experimental results showthat reducing grinding depth,increasing grinding wheel speed,and selecting appropriate workpiece speed andfeed speed are beneficial to control the surface roughness of tungsten carbide alloy after ultra-precision grinding.The optimum process parameters are as follows:grinding depth 1μm,feed speed 1 mm/min,grinding wheelspeed 40000 rpm/min,and workpiece speed 200 rpm/min.An aspheric core with an average surface roughness of3.379 nm was obtained by ultra-precision grinding of an 11.8 mm diameter tungsten carbide alloy core with theoptimum process parameters obtained by the optimization experiment.