Wrapping apparatus and method including metered pre-stretch film delivery assembly

Abstract

The present disclosure provides a method and apparatus for dispensing a predetermined fixed amount of pre-stretched packaging material based upon load girth. A non-rotating ring carries a belt driven by a motor. A packaging material dispenser is mounted on a rotating ring, and the rotating ring may include a pulley that connects to the band, such that the rotating ring is driven by the drive belt. Based upon the girth of the load to be wrapped, an amount of pre-stretched packaging material to be dispensed for at least a portion of a revolution made by the rotating ring is determined. Good wrapping performance in terms of load containment (wrap force) and optimum packaging material use is obtained by dispensing a length of pre-stretched packaging material that is between approximately 90% and approximately 120% of load girth. Once the amount of packaging material to be dispensed per revolution is determined, a ratio of rotating ring drive to final pre-stretch surface speed (i.e., number of pre-stretch roller revolution/rotating ring rotation) can be set and mechanically controlled. Thus, for each revolution of the rotating ring and dispenser, an amount of packaging material is dispensed and wrapped around the load. In an alternative embodiment, the ratio is electronically controlled.

1 . An apparatus for stretch wrapping a load, comprising:
 a rotatable ring;   a packaging material dispenser for dispensing a film web, the packaging material dispenser being mounted on the rotatable ring and including an upstream pre-stretch roller and a downstream pre-stretch roller within a pre-stretch assembly;   a drive mechanism configured to rotate the rotatable ring;   an input/output ratio control configured to maintain a ratio of ring rotation speed to pre-stretch speed during at least a primary portion of a wrapping cycle; and   a final roller positioned a distance from the downstream pre-stretch roller, the distance being such that at least a portion of a length of film extending between the downstream pre-stretch roller and the final roller acts to dampen variations in forces acting on the pre-stretched packaging material as it travels from the dispenser to the load.   
     
     
         2 - 97 . (canceled)