| 摘要 |
PCT No. PCT/AU96/00597 Sec. 371 Date May 26, 1998 Sec. 102(e) Date May 26, 1998 PCT Filed Sep. 20, 1996 PCT Pub. No. WO97/11018 PCT Pub. Date Mar. 27, 1997A wrapping apparatus is provided including a shuttle for orbital movement around an object to be wrapped, the shuttle carrying a feed roll from which a web of plastic film is drawn to wrap the object, the shuttle including a pre-stretching mechanism including: a braking roller mounted on the shuttle for rotation about an axis that is fixed relative to the shuttle; a stretching roller mounted on the shuttle for rotation about an axis which is fixed relative to the shuttle, parallel to the braking roller axis and spaced therefrom, the web being drawn directly from the feed roll around the stretching roller; drive transmission means connecting the rollers such that the surface speed of the stretching roller exceeds that of the braking roller; mandrel means for the rotational support of a feed roll of stretch wrap film mounted on the shuttle by guide means allowing the mandrel to move freely towards the braking roller under the influence of tension in a web of film drawn directly from the feed roll and passing around the stretching roller; and supplementary loading means acting independently of the web tension to supplement the effect of the web tension in urging the feed roll towards the braking roller to maintain braking contact therebetween. A method of wrapping at least part of an object in plastic film is provided including: loading a shuttle with a feed roll of the film, attaching an end of the film to the object; causing the shuttle to orbit at least part of the object; and pre-stretching the film as it is drawn from the feed roll by the relative movement between the object and the shuttle prior to its application to the object; wherein the feed roll is free to move bodily into contact with a braking roller under the effect of tension in the film departing from the feed roll and the step of pre-stretching the film is effected by of drawing the film directly from the feed roll around the stretching roller connected to the braking roller by drive transmission means ensuring that the surface speed of the stretching roller is greater than that of the braking roller, and augmenting the effect of the tension in the film in maintaining contact between the feed roll and the braking roller and having a value that is not dependent on the film tension. |
