Study on the thermoforming process of Hemispherical Resonator Gyros (HRGs)

This paper discusses a new research about the relationship between the thermoforming factors and the geometric dimension of the Hemispherical Resonator Gyro (HRG) sensitive structure, especially the ambient pressure factor. For the study, a high temperature furnace system with visible internal workspace and adjustable pressure range is designed and applied to monitor the whole process. By means of the furnace system, Pyrex 7740 thermoforming process is supervisory controlled, and the fitting curve indicates that the height of the sensitive structure increases rapidly with the decrease of the ambient pressure, whose relationship could be described accurately as an inverse proportion function. ANSYS Polyflow is used to verify the above phenomena, and the simulation results accord well with the experimental results, which means the thermoforming process of the sensitive structure can be predicted accurately by FEM.