Research On Material Removal Mechanism And Process Optimization Of Robotic Bonnet Polishing For SiC Components

Silicon Carbide(SiC)material has the characteristics of large band gap width,high critical field strength,high thermal conductivity and so on.It is an important third generation semiconductor chip material and mirror material.At the same time,it has the characteristics of large specific stiffness,small thermal deformation coefficient,good radiation resistance,etc.and high precision SiC mirror is used in optical remote sensing field.SiC material is hard and brittle,the processing is very difficult,and the cost of special ultra-precision CNC grinding、polishing machine is high,and for the growing SiC component size demand adaptability is insufficient.Therefore,the development of low cost,good application adaptability of SiC components high efficiency and high precision machining equipment has important engineering application significance.In this paper,the industrial robot and the flexible bonnet technology are combined and applied to the polishing of SiC components.Due to the advantages of good flexibility,high removal efficiency and controllable precision,the bonnet polishing technology can be applied to the uniform polishing with high efficiency removal and the modified polishing with convergent surface shape,and is being gradually applied to the polishing of difficult-to-machine materials.Therefore,the bonnet polishing system based on industrial robot is designed and developed,which not only meets the needs of tool efficiency and low cost and high flexibility of robot body in the efficient polishing of SiC,but also solves the needs of complex space movement of the machine by bonnet polishing technology.In this paper,the material removal law and process stability optimization were studied through systematic process experiments.The main research contents are as follows:(1)Combined with the characteristics of bonnet polishing technology,a bonnet polishing tool head and polishing fluid circulation system suitable for industrial robots was developed.In order to realize accurate tool setting and polishing force acquisition,a force sensing tool was designed and developed.According to the programming characteristics of industrial robot,the precession motion model of robot bonnet polishing was established to realize the precise and controllable polishing process.(2)In order to explore the material removal characteristics of robotic bonnet polishing for SiC components,the influences of precession Angle,pressure,spindle speed and charging pressure on removal efficiency and surface roughness were obtained through single factor experiments.The mathematical model between the four process parameters and the removal efficiency was established based on the surface response method,and the model between the process parameters and the roughness was established based on the support vector machine.(3)The surface quality decreases due to vibration in the process of robot polishing.According to the forced vibration theory and combined with the modal simulation of robot polishing system,the vibration suppression bonnet tool head is designed.The simulation results show that the vibration attenuation effect of the vibration suppression bonnet is more obvious.According to the process experiment and comparison of surface roughness,vibration suppression bonnet is better than ordinary bonnet.