Research On High Temperature Melt Pressure Sensor In Mold Cavity Based On Optical Fiber F

In the field of injection molding,cavity pressure is a key parameter to guide production and optimize process.The traditional electronic pressure sensor has poor environmental protection performance,easy to be subjected to electromagnetic interference and short working life in high temperature environment,so it is urgent to study a new melt pressure measurement scheme.In this paper,according to the actual pressure measurement requirements in injection molding and melt extrusion,the research status of high temperature melt cavity pressure sensor is analyzed,and the target parameters of the sensor are determined.A scheme based on fiber Fabry-Perot cavity and fiber Bragg grating is proposed to solve the crosstalk problem of temperature and pressure by using fiber Bragg grating monitor melt temperature.The principle of optical fiber F-P sensing and demodulation of is analyzed in detail.The influence of sensor unit size on pressure sensitivity is determined by numerical simulation.The influence of F-P cavity length and mirror reflectivity on the contrast of interference spectral fringes is analyzed.Based on the theoretical analysis,the specific technology of optical fiber F-P cavity fabricated with different materials was compared.The metal shell used to encapsulate the sensor was designed and processed,and the fiber F-P pressure sensor with a measuring range of 200 MPa was produced.The temperature compensation method of high temperature melt pressure sensor is studied under no pressure load.In summary,the proposed optical fiber F-P cavity pressure sensor has the advantages of large pressure range,easy to realize temperature and pressure compensation,low cost and easy preparation,which lays a foundation for the further realization of high temperature melt pressure monitoring.