A novel method of water bath heating assisted small ball-end magnetorheological polishing for hemispherical shell resonators

Hemispherical shell resonator(HSR)is the core component of hemispherical resonator gyro.It is aφ-shaped small-bore complex component with minimum curvature radius less than 3 mm.Thus,traditional polishing methods are difficult to polish it.Small ball-end magnetorheological polishing method can polish the small components with complicated three-dimensional surface and obtain non-destructive surface.Therefore,this method is suitable for polishing HSR.However,the material removal rate of the ordinary small ball-end magnetorheological polishing is low,leading to long polishing time and low output of HSR.To solve this problem,a water bath heating assisted small ball-end magnetorheological polishing method is proposed in this research.The influence rule of processing parameters on the material removal rate is studied experimentally.A set of optimal processing parameters is obtained to maximize the material removal rate.Compared with the ordinary method,the material removal rate of the new method can be improved by 143%.Subsequently,an HSR is polished by the new method.The results show that the polishing time can be reduced by 55%,and the polished surface roughness can reach 7.7 nm.The new method has the great potential to be used in actual production to improve the polishing efficiency of HSR.

Thermoelastic Dissipation in Diamond Micro Hemispherical Shell Resonators

Maximizing quality factor (Q) is essential to improve the performance of micro hemispherical shell resonators (μHSRs) which can be used in microelectromechanical system (MEMS) gyroscopes to measure angular rotation.Several energy dissipation mechanisms limit Q,where thermoelastic dissipation (TED) is the major one and studied in this paper.Fully coupled thermo-mechanical equations for calculating TED are formulated,and then temperature distribution in a deformed μHSR and its quality factor related to TED (QTED) are obtained by solving the equations through a finite-element method (FEM).It has been found that different fabrication process conditions can obtain various geometrical parameters in our previous studies.In order to provide guidelines for the design and fabrication of μHSRs,the effects of their geometry on resonant frequency (f0) and QTED are studied.The change of anchor height and small enough anchor radius have no effect on both f0 and QTED,but the shell size including its radius,thickness and height has significant impact on f0 and QTED.It is found that whether a μHSR has lower f0 and higher QTED or higher f0 and higher QTED can be achieved by changing these geometrical parameters.The results presented in this paper can also be applied to other similar resonators.