Process and machine for packaging products with stretchable thermoplastic film

Abstract: Means are provided to ensure that during the stage of formation through the tube- forming and longitudinal welding means (1, 18) the wrapping is subjected to longitudinal stretching which causes it to adhere intimately in a direction transverse to the product and this condition is ensured by means which bring about a particular difference in velocity between the jaw (19, 119) which supports the tubular wrapping and causes it to advance and the means (15, 115, 17) which feed the film to the tube-forming means (1) which also remain suitably active during the subsequent stage in which the tubular wrapping is seized posteriorly by the appropriate posterior closing jaw (119, 19), all in such a way that the wrapping film runs over the said tube-forming means in an almost continuous movement to prevent localised appearance defects in the packaging and to assist operation of the longitudinal welding means (18) which are then able to operate substantially continuously. (end of abstract)