METHOD AND APPARATUS FOR WRAPPING A LOAD USING VARIABLE ROLLER STRETCH

摘要

A method and apparatus for wrapping the load at a desired wrap force are provided. The apparatus includes a dispenser (102) for dispensing packaging material and means for providing relative rotation between the load and the dispenser. The dispenser has a prestretch portion (110) and a post-stretch portion (160). The prestretch portion is configured to prestretch the packaging material within the dispenser to a point below the yield point of the packaging material. Preferably the packaging material is prestretched between first and second unpowered prestretch rollers. The post-stretch portion is configured to further stretch the prestretched packaging material to a point above the yield point of the packaging material as the packaging material moves from the dispenser to the load. Preferably, the post-stretch portion includes a friction element, such as a brake (170), to apply friction to one of the prestretch rollers (118).