| 摘要 |
1309684 Seaming E I DU PONT DE NEMOURS & CO 27 July 1970 [20 Oct 1969] 36332/70 Heading B5K [Also in Division B8] A web L1 of thermoplastic sheeting is fed from a braked supply roll 1R carried on a reel stand 1 to a processing apparatus 401 by way of a splicing and trimming device 2, power driven feed rollers 303 provided with a web-braking device 305, and a web accumulator 320. The stand 1 also carries a replacement roll 2R and the leading end of the web L2 from this roll is held by suction on a unit 234 pivotally mounted in the device 2 which also includes a rotatably mounted platen-carrying member 250 and a unit 208 which is rotatably mounted on a pivoted arm 201, the unit 234 carrying an electrically heated severing element and the unit 208 carrying a similar element and a platen. When the running roll is almost exhausted, as detected by a footage counter or roll-radius sensor the following sequence of events is initiated under the control of an electric and pneumatic control system (Fig. 10, not shown) housed in a unit 275: the drive to the rollers 303 is stopped and the brake 305 is applied to the web L1, the apparatus 401 continuing to function with web drawn from the accumulator 320; unit 208 is moved against unit 250 to sever the web L1 and is then retracted carrying by suction the waste end of the web with it (Figs. 9A to 9C, not shown); member 250 is then rotated carrying the cut end of the web L1 so that unit 234 can be urged towards the member 250 to weld webs L1 and L2 together and to trim the join (Fig. 9D to 9F, not shown); member 250 is then rotated again, to bring the join under the platen carried by the unit 208 which when urged against member 250, mechanically shapes the joined edges with heat and pressure to produce a uniform thickness equal to the thickness of the joined lengths (Figs. 9 to 91, not shown). The unit 208 is then retracted and the drive to the web energized so that the feed to apparatus 401 can continue with the web from the new supply roll 2R. |
