| 摘要 |
PURPOSE:To make the uniform internal cooling of a molded item possible by a method wherein the exhaust process of vaporized gas in the molded item is started just before the end of the blowing process of liquefied gas and the feed of the liquefied gas is controlled when the measured value of the tempera ture or flow rate of vaporized gas exhausted after the internal cooling of the molded item exceeds the preset proper range. CONSTITUTION:The timing of the opening operation of an exhaust solenoid valve 12 is set so as to start the exhaust process of nitrogen gas utilized for cooling the interior of a product slightly earlier than the end of the blowing process of liquid nitrogen LN2. Further, a control circuit 15 programs procedure so as to automatically control the feed of the liquid nitrogen LN2 by controlling the closing and opening of a LN2 flow control valve 8 in order to bring tempera ture in proper range, when the exhaust gus temperature just after the start of exhaust process oversteps the pre-set correct temperature range. As a result, pressure difference develops between the feeding pressure of LN2 and the inner pressure of a molded item, resulting in enlarging the turbulent flow state in the molded item 2 and consequently the heat transfer effect in the molded item and effectively utilizing cold heat. |
