Method for manufacturing air filled packing cushions
A machine ( 1 ) for the production of packaging material in the form of air filled cushions ( 24 ) comprises feeding rollers ( 2 ) for conveying parallel two films of plastic material ( 20 a and 20 b ), unwound starting from rolls ( 30 a and 30 b ), according to a conveying direction. Downstream of the feeding rollers ( 2 ) air is supplied between the two films ( 20 a and 20 b ) by means of a plurality of tubes ( 6 ) extending from a collector ( 5 ) and parallel to the conveying direction of the films ( 20 a and 20 b ). Each tube ( 6 ) extends between two longitudinal heatsealing elements ( 10 ), crosses a couple of dragging rollers ( 8 ) and ends at transversal heat-sealing elements ( 15 ).
1. Method for the production of packaging material in the form of tubular cushions filled with air, or other gas, comprising the steps of:
feeding in parallel in a conveying direction two films of plastic material;
blowing air or other gas in parallel ducts between said films of plastic material;
making longitudinal sealing lines on said films to define tubular chambers in which air is blown by said ducts, and making on said films couples of transversal sealing lines close to each other in order to substantially form cushions containing a certain amount of air or other gas; and
outputting a row of tubular cushions containing a predetermined amount of air or other gas trapped between two adjacent longitudinal sealing lines and two consecutive couples of transversal sealing lines close to each other,
wherein when making a couple of transversal sealing lines close to each other, a step is provided of orthogonally moving a cutting means between said transversal sealing lines close to each other, and wherein
said step of orthogonally moving said cutting means is made by at least one actuator capable of selectively moving said cutting means according to either a stroke for making a tear line or a stroke for making a complete cut, such that adjacent cushions of said row are connected at said transversal sealing lines by a transversal tear line and other adjacent cushions of said row are separated from each other at said transversal sealing lines y a transversal complete cut.
2. Method according to claim 1 , wherein said step of cutting is made by causing a toothed blade arranged between fixed bars to move orthogonally to said films of plastic material and making, selectively, a tear line or a complete cut.
3. Method according to claim 1 , wherein the step of cutting is made by a first actuator that is associated with a second actuator, such that said stroke for making a tear line is obtained by operation of said first actuator, and said stroke for making a complete cut is obtained by said first actuator and said second actuator operated at the same time.