Patent GB-1416374-A (GB)
Title: Methods of and apparatus for manufacturing a sheet material comprising a continuous web of a thermoplastics material with locally secured fastener elements
IPC: B29C43/32
Filed: 1973-04-10
Abstract: 1416374 Perforated reinforced film or sheet material; laminates E SOLBECK 10 April 1973 [19 April 1972] 17172/73 Headings B5A B5B and B5N A sheet material suitable for use as tarpaulins or tent-cloth comprising a continuous web of thermoplastics material with discrete fastener elements is made by extruding a thermoplastics material to form a film, cooling the film in the nip between a pair of continuously advancing surfaces, e.g. a pair of calibrating members, e.g. counter-rotating rollers or synchronously travelling, opposed endless conveyer belts, and intermittently supplying prefabricated fastener elements to the surface of one of the calibrating members in timed relationship with the peripheral speed of said one member, so that the motor of said members causes the elements to be sequentially brought in contact with the extruded film between the nozzle orifice and the nip and to be pulled into and through the nip together with the film. A continuous reinforcing web may be supplied to the other of said calibrating members between said extruder nozzle and the nip. The manufacture of a low density polyethylene film having fastener eyelets of the same material and reinforced with a netting of high density polyethylene is exemplified. In apparatus as shown, plastics material is extruded as a flowable film or sheet 3 which passes into the nip between a hard rotating cooling roller 3 and a soft counter rotating roller 4. A reinforcing material may be introduced between extruder head 1 and roller 4, to be joined together with sheet 2 in the nip. Eyelets 5 are supplied to the nip at a specific rate, timed with the rotation of roller 3, by means of five feeding devices 10, spaced along the length of the roller, the spacing between adjacent devices corresponding to that between the longitudinally extending rows of eyelets 6 and 7 (Fig. 6). In operation a timing mechanism coupled to the shaft of roller 3 supplies pulses to the cylinder 15 of each feeding device so that the piston rods 16 and slides 17 (Fig. 2) are moved forward and immediately thereafter back again as shown at the foot of Fig. 6. In advancement of slide 17 its rearmost tongue 18 carries the lower most eyelet 5 along with it from the associated magazine shaft and the other tongues 18 move the eyelets previously introduced into the discharge passage 11-13 one step forward. As shown in Fig. 2, in the forward end position of a alide 17 the foremost eyelet 5 in the passage rests on the slide, and when the slide is withdrawn the eyelet is released and drops through recess 31 in plate 11 on to roller 3. During retraction of slide 17 the stationary tongues 14 of cover plate 13 ensure that further eyelets, including that inserted in the discharge channel by the advancing slide, retain their positions in the channel. Fig. 3 shows the magazine shaft in detail. A threaded vertical spindle 20 is mounted on each side of the shaft, the thread engaging with eyelets 5. The spindles 20 are rotated continuously so as to urge the eyelets towards the bottom plate 11. A cylindrical rod 21, of crosssection slightly smaller than the hole in eyelets 5 is disposed centrally of shaft 10 and is freely movable so that it rests under its own weight against slide 17 when this assumes its forward position as shown in Fig. 1. When the slide is withdrawn from this position by cylinder 15, the rearmost tongue on the slide can raise the rod as shown so that it no longer holds the lowermost eyelet 5 in the shaft. Thus the lowermost eyelet may be advanced while the following one is retained, so that simultaneous advancing of two eyelets is prevented.