Research On Key Technology Of Non-resonant Vibration-assisted Roll-type Polishing

Advanced ceramic materials have been widely used in a new generation of space-to-ground optical information collection systems,so as to make the optical systems constantly have thermal stability and a high stiffness to weight ratio.Silicon carbide(SiC)ceramic is a competitive hard and brittle material for establishing the ideal space reflecting mirrors by the advantages of chemical inertness and corrosion resistance.However,the processing of SiC materials is challenging due to its high brittleness and low fracture toughness.Among the processing methods to machine SiC ceramic,polishing can be served as an indispensable step to achieve target surface integrity.Considering the body of this paper,a novel non-resonant vibration-assisted roll-type polishing(NVRP)method was proposed to improve the capacities of polishing hard and brittle materials process in terms of surface uniformity through adopting non-resonant vibration-assisted technology and linear contact material remove principle.The study can be summarized as follows:(1)The computer-aided design assembly processes of the NVRP system was conducted.Based on the compliance matrix method,static modeling was established to analyze compliance and amplification ratio of the 2D-VPD.Besides,the natural frequencies of the 2D-VPD were determined by energy equilibrium-based Lagrange equation.To prevent the 2D-VPD from failure during the production and application processes,the maximum stresses subject to rotation and tension were marked respectively.(2)The dimensions of the 2D-VPD were optimized using the grey wolves optimization(GWO)algorithm,aiming to maximize the natural frequencies.The dynamic and static performances of the designed 2D-VPD were determined based on finite element analysis method.Meanwhile,both open-loop and closed-loop experimental tests were conducted to determine the properties of the 2D-VPD.The processing paths of the 2D-VPD under various frequency ratios were marked during NVRP.(3)The effect of the polishing depth on surface material deformation was established by using ABAQUS finite element simulation software.In order to study the influence of the non-resonant vibration-assisted and processing parameters on the surface roughness and uniformity,a series of contrast experiments were designed and conducted.Besides,the surface morphologies of the original and polished SiC workpieces were measured through SEM,respectively.The contrast experiment of the material removal rate of the roll-type polishing and NVRP system were conducted.(4)Considering the kinetic relationship between the grain and workpiece,the theoretical analysis provided a useful formula for calculating SSD depth regarding the rotational angle of the grain and a set of effective ranges of rotational angle corresponded to various processing depth.A series of contrast experiments focused on the extension of lateral cracks and the inclination of median cracks during polishing process were carried out.Besides,the theoretical values and testing results in terms of SSD depth were verified.