PROCESS AND APPARATUS FOR PRODUCING COVER SHEETS OF PLASTICS MATERIALS

1294372 Seaming non-metallic sheet material MONTECATINI EDISON SpA 16 March 1970 [14 March 1969] 12640/70 Heading B5K A cover sheet of plastics film is made by inserting a support beneath a portion of an edge of a first sheet of plastics film, laying a second sheet of plastics film over the support such that a portion of an edge thereof abuts the edge portion of the first sheet, moving the support along and parallel to the edge of the first sheet such that further portions of the respective edges of the first and second sheets abut, and bonding together the abutting postions on the support. Specified plastics films are polyvinyl chloride, polyethylene and synthetic rubber. Apparatus for making the cover sheet may be arranged for towing by a tractor or may include a seat for a driver and steering means. In the embodiment shown, a frame 1 is mounted on four wheels 2 driven by a variable speed motor 3. Four parallel rollers 5, 51 are mounted on the frame 1, the rollers 5 supporting the plastics strips during joining and the shorter rollers 51 guiding the strips. Rollers 9 are mounted above the rollers 5 to form presser feet for the joining. The drive from the motor 3 is transmitted, by way of a speed synchronizer 10, to the rollers 5, 51, 9 which, preferably, are all coated with rubber. As shown in Fig. 1, the axes of the rollers are inclined towards the already laid strip. An automatic control 13, e.g. a rack-system driven by an electric motor, is provided for lifting and lowering the rollers 9. A reel 20 of plastics strip is mounted on a freerunning roller 15 under which free-running guide rollers 16, 17 are mounted, see also Fig. 3. A welding device, e.g. hot air pipes 21, 211, electrically heated tools, dielectric heating tools or an applicator supplying hot melt adhesive, is mounted on a plate 18. Supports 23, 231, removable by screw or telescopic systems, are provided for the rollers 9, 15, 16, 17. In operation, the apparatus, with the support 231 removed and the pipes 21, 211 out of action, traverses the surface to be covered to lay along its length a first plastics film strip by movement in the direction of arrow a, Figs. 2 and 3, the film following the dotted line path 25, Fig. 3. The apparatus is moved sideways a distance equal to the width of the already laid strip. The support 231 is replaced and the support 23 removed. The edge of the already-laid strip is made to pass over the rollers 5, 51 and the apparatus is moved in the direction of arrow b