| 摘要 |
PURPOSE:To reduce the development of defective molding and contrive the improvement of quality control by a method wherein the temperature of the resin in a hot runner is regulated by controlling a heater by means of a controlling device on the basis of the value of the sound velocity in the resin in the hot runner. CONSTITUTION:Ultrasonic wave having the frequency of 5MHz is emitted at 2000 times/sec from the ultrasonic prove 31 of an ultrasonic flaw detector 30 to a tip part 8. In the ultrasonic flaw detector 30, the ultrasonic probe 31 calculates the value of the sound velocity in resin on the basis of the time (t) between the receipt of a reflected wave 42 and the receipt of a reflected wave 43 (the time (t) represents the trqnsit time of the resin) so as to output it to a comparator 32, which compares the value of the sound velocity with the preset-set value of the sound velocity so as to output the comparison result to a PID controlling device 33, which controls a heater 11 in order to regulate the resin temperature in the tip part 8. For example, when the value of the sound velocity calculated by the ultrasonic flaw detector 30 is smaller than the set value of the sound velocity, the PID controlling device 33 controls so as to lower the temperature of the heater 11 to the proper one. |
