| 摘要 |
Apparatus for preparing a longitudinally folded web of material, e.g. high density polyethylene film, having a row of pockets (2) extending along it and carrying reference marks (8) each of which is in a predetermined position, in the lengthwise direction of the web, relative to a pocket or group of pockets, the apparatus comprising a sealing member (10) adapted to form at least one transverse seal (6) between the overlapping portions of the folded web when moved into contact with the web, the pockets being defined between seals, and a reference mark forming member (24) connected to the sealing member for movement therewith and arranged for forming at least one reference mark on the web each time a seal or seals is or are formed, so that the reference marks are in exact registration with the pockets. The reference mark may be a hole, a magnetic portion, an electrically conductive portion, or an optically detectable portion, reflective or transparent. The member (24) may be an electrically-heated block which acts on a heat and pressure sensitive overprinting tape (26). The member (10) carries an electrically-heated member (12) having projections (14) thereon. <IMAGE> |
