Method for thermostatically controlling mold temperatures

A method of controlling the temperature of a molding apparatus comprising at least two die sections moveable relative to one another between a closed position and an open position, in the closed position the die sections cooperate to define a cavity in which a molten material is injectable to produce an article and in the open position the die sections are separated to permit removal of the formed article, each of the die sections having a plurality of cooling channels extending through select zones of the die section, each of the cooling channels having an inlet end connected to a source of cooling fluid and an outlet end connected to an exhaust line, the method comprising:

• providing ball valves for each of the cooling channels;
• interposing each of the ball valves in the exhaust line of the corresponding channel;
• performing multiple test runs of the molding apparatus;
• adjusting the ball valves during the test runs so that the molding apparatus operates under a plurality of different operating conditions;
• recording testing data during the test runs, the test data comprising at least mold cavity temperatures, cooling line temperatures, production count data, and part quality data;
• analyzing the test data to determine an optimum operating temperature range for each of the select zones of the die sections and corresponding optimum temperature ranges for each of the thermostatic control valves;
• removing the ball valves;
• providing a thermostatic control valve for each of the cooling channels;
• calibrating each thermostatic control to the corresponding optimum temperature range;
• interposing each of the thermostatic control valves in the exhaust line of the corresponding cooling channel;
• performing production runs of the molding apparatus;
• and
• wherein each of the thermostatic control valves has a closed condition wherein the flow of the cooling fluid passing through the corresponding cooling channel of the die section is caused to be restricted in response to the temperatures of the cooling fluid being below a lower limit of the optimum operating temperature range so as to cause the temperature of the corresponding zone of the die section to increase and an open condition wherein the flow rate of the cooling fluid passing through the cooling channel is increased in response to the temperature of the cooling fluid rising above the upper limit of the optimum operating temperature range so as to cause the temperature of the corresponding zone of the die section to decrease whereby the selected operating temperature range of each of the zones of the die sections is maintained automatically;
• the thermostatic control valve having a valve body defining a fluid flow passageway wherein a temperature sensing actuator assembly provided within the passageway is operatively connected to an adjustable calibration screw provided within the passageway for calibrating the optimum operating temperature range whereby the actuator assembly and calibration screw are not accessible for field calibration while the thermostatic control valve is interposed in the exhaust line.