Patent ID: 8747713

Claim:
A method of manufacturing a polymer film comprising the steps of: unwinding a lay-flat tubular polymer film from a reel ( 9 ) in a tumbling unwinding stand ( 1 ) comprising stretching rollers ( 107 - 112 or 101 - 106 ), where the tumbling unwinding stand ( 1 ) performs a tumbling movement to rotate the lay-flat tubular polymer film around its longitudinally extending middle line, as the film is unwound uniaxially orienting and stretching the lay-flat tubular polymer film, within the tumbling unwinding stand ( 1 ), at an angle to the longitudinally extending middle line between (a) the stretching rollers ( 107 - 112 ), where the rollers ( 107 - 109 ) run at a first velocity, while the rollers ( 110 - 112 ) run at a second velocity greater than the first velocity causing the stretching providing a new machine direction to the lay-flat tubular polymer film or (b) the stretching rollers ( 101 - 106 ), where the stretching occurs between driven rollers ( 102 ) and ( 103 ) providing a new machine direction to the lay-flat tubular polymer film, dragging the stretched and oriented lay-flat tubular polymer film over a mandrel ( 16 ) to inflate the stretched and oriented lay-flat tubular polymer film and to evenly propel the polymer film in a screwing movement, where each point on the film surface follows a helical path, helically cutting the inflated stretched and oriented lay-flat tubular polymer film using a knife ( 18 ) located in a fixed position to form a helically cut uniaxially stretched and oriented polymer film, stabilizing the helically cut uniaxially oriented polymer film, and pulling away the helically uniaxially stretched and oriented cut film from the mandrel ( 16 ).