Method and assembly of winding one or more bundles with stretch film from a reel

A method for wrapping bundles with stretch film from a reel, wherein one or more bundles, composed of one or more products, is/are in transit in a packaging machine that has at least one wrapping unit comprising at least one ring wrapping machine which, on rotating, arranges the stretch film around one or more bundles, wherein said film is unwound from a reel arranged on a rotating ring of said ring wrapping machine and is caused to be arranged around one or more bundles, during the transiting of the bundles in the wrapping unit, the wrapping method comprising:

• a) a first step, in which said stretch film which is being unwound from said reel passes through a pre-stretching group which generates an axial deformation of said film predetermining an elastic return quantity,
• b) a second step wherein said stretch film axially deformed in step a) is caused to interface with a vacuum box having a known volume positioned downstream of the pre-stretching group, which provides a buffer having a volume compensating for a difference between an average development rate of the film during rotation of the ring with respect to a deposition rate of the film on one or more bundles regardless of geometry of the one or more bundles and producing a constant auxiliary tensional stress on the pre-stretched film equal to a value of a head inside the vacuum box for projection of an interface surface of the film with said vacuum box,
• c) a third step wherein the film is deposited on said one or more bundles with a constant stress residue at each point of application of said pre-stretched film after addition of the constant load generated by the vacuum box, producing one or more bundles completely wrapped with a programmed stress residue in each point of a perimeter of the one or more bundles, wherein the depositing of said film is effected through at least one complete revolution of said ring around said one or more bundles.