| 摘要 |
A vertical bag packaging machine (1,51) has a steam nozzle (23) that is inserted into a bag (B) to inject steam thereinto after an article to be packaged has been filled into the bag, thereby replacing the air in the bag with the steam to effect deaeration. After the steam-replacement deaeration, a seal portion to be ultrasonically sealed is preheated by a preheating device (25,53), thereby making the temperature of the seal portion uniform throughout it. The preheating temperature is not lower than a temperature of a highest temperature region of said seal portion before it is preheated and below a melting temperature of a material constituting an inner side of said bag Thereafter, the seal portion is ultrasonically sealed by an ultrasonic sealing device (35). Thus, reliable and stable ultrasonic sealing can be realized. |
