IES940761A2 - A plastic bag production process - Google Patents

Abstract

Flattened tubular thermoplastic film is lead from a supply reel 11 to a spreading station 25 at which the film 14 is tensioned transversely to remove creases. Upper and lower layers 31, 32 of the film 14 are separated by means of an air bubble 30 formed between the spreading station 25 and a bubble collapsing means 35 having a set of three in-line spaced-apart rollers 36 around which the film 14 is led to gradually bring the upper and lower layers 31, 32 of the film together in a controlled manner. The film 14 is then delivered to sealing stations 40 at which transverse seals across the width of the film 14 are formed by heat sealing bars which clamp the film 14 therebetween. Downstream of the sealing stations 40 the film 14 passes through coolers 46, 48 for cooling the seals. Both film layers are cut longitudinally to provide a bag inlet opening in the film 40 extending between each adjacent pair of seals prior to delivering the film 14 to a guillotine 53. At the guillotine 53 the film is cut transversely across each seal to part individual bags away from a leading end of the film 14.