METHOD AND APPARATUS FOR DISPENSING A PREDETERMINED FIXED AMOUNT OF PRE-STRETCHED FILM RELATIVE TO LOAD GIRTH

摘要

The present invention provides a method and apparatus for dispensing a predetermined fixed amount of pre-stretched film based upon load girth. A non-rotating ring carries a belt (130) driven by a motor (132). A film dispenser (136) is mounted on a rotating ring (122), and the rotating ring includes a pulley (168) that connects to the belt, such that the rotating ring is driven by the belt. Based upon the girth of the load to be wrapped, an amount of pre-stretched film to be dispensed for each revolution made by the rotating ring is determined. Good wrapping performance in terms of load containment (wrap force) and optimum film use is obtained by dispensing a length of pre-stretched film that is between approximately 100% and approximately 130% of load girth. Once the amount of film to be dispensed per revolution is determined, a mechanical ratio of ring drive to final pre-stretch surface speed (i.e., number of pre-stretch roller revolution/ ring rotation), can be set. Thus, for each revolution of the rotating ring and dispenser, a predetermined fixed amount of film is dispensed and wrapped around the load.