The measurement and control of nozzle melt temperature in injection molding /

The temperature of the polymer melt plays an important role in injection molding, directly affecting the quality of the molded part.A new barrel, nozzle, and crew tip were constructed for an injection molding machine to allow the installation a Vanzetti infrared optical fiber temperature sensor and several exposed junction thermocouples. These sensors were compared for the measurement of polymer melt temperature.Open loop pseudo-random binary sequence experiments were performed to obtain dynamic temperature models for nozzle melt temperature when the band heater power was varied. The open loop response of the nozzle melt temperature was found to be second order overdamped with a dead time.Process control simulations were done with the PID, Dahlin, a second order modified Dahlin, and Smith predictor control algorithms in order to determine the optimum parameters for the controllers and to compare their responses. Experiments using the PID and the Dahlin controller were performed, with step changes in set points and disturbances introduced into the system