摘要 |
<p>A belt-like film 18 is moved along a plate 15 folded to be rectangular in section, so that the film 18 is formed into a continuous tube by a tubular frame of the plate 15. A spring piece 30 having an anvil 31 bulged out therefrom is securely held on the inner side edge 16 of the aforementioned plate 15, and an ultrasonic hammer 32 is located face to face with said anvil 31, so that both side edges of the belt-like film 18 formed into a tube are placed on the anvil 31 to be melded by the ultrasonic vibration of the hammer 32.</p> |