Cylinder temperature controller for an injection molding machine

摘要

A cylinder temperature controller for an injection molding machine in which an injection molding operation is performed while keeping the injection cylinder at a stable preset temperature regardless of disturbances such as the change of mold temperature or ambient temperature and the temperature rise caused by the shear compression of resin. A temperature regulator for carrying out PID feedback control of the injection cylinder temperature is provided with a PID adjusting means unit for automatic tuning. The actual temperature T of each portion of the injection cylinder is detected by a thermocouple. When the actual temperature T deviates from a predetermined temperature range defined by an upper limit [A+B] and lower limit [A-B] which are set on the basis of the preset target temperature A, an automatic tuning command is outputted to the temperature regulator. Upon receipt of this command, the PID adjusting unit sets the PID parameters again at a value suitable to the disturbance. By keeping the PID parameters to be suitable to the disturbance, the actual temperature T of each portion of the cylinder agrees with the preset target temperature A regardless of the change of the disturbance.