a band - shaped film of a suitable plastic material is conveyed and is formed into a tubular shape during its travel , articles to be packed are conveyed and transferred into the tubular film at intervals and the tubular film is sealed at a predetermined pitch into individual bags . the tubular film is fed at a substantially constant speed and each article is conveyed at about the same speed as that of the tubular film during at least a period in which the article is transferred into the tubular film .