| 摘要 |
1,196,193. Seaming non-metallic sheet material. H. BECK. 30 July, 1968 [16 Aug., 1967], No. 36402/68. Heading B5K. [Also in Division H5] A die for heat sealing thermoplastic sheet material comprising a heating wire 19 held under tension on a welding rail 18, is characterized in that, for producing discontinuously welded seams, the wire 19 forms a loop 19a at a discontinuity in the rail 18, the loop 19a extending into a cavity 18b in the rail and passing around a guide member 31 located within the cavity 18b and a tensioning element 33 acting upon the member 31 so as to tighten the loop 19a. In one embodiment, Figs. 1 and 3, the die, which may simultaneously perforate and weld, comprises two parts 11a, 11b having slots 11aa, 11ba in which slide pressure rails 13, 14 urged outwardly by springs 15, 16, stop pins 10 being provided. The rail 18 of heat insulating and electrically non-conductive material is positioned in a slot 17 and has lateral bars 20, 21 secured thereto. The wire 19 is coated with plastics material which is neither adherent nor fusible to the sheet material and is tensioned by springs 27, 28 pressing against nipples 29, 30. The loops 19a extend through inclined bores 18a and pass around bolt-like guide members 31 mounted in lugs 32a of a bar 32. Springs 33 urge the bar 32 upwardly to assist in tensioning the wire 19. In a second embodiment, Fig. 4, the loops 119a of the heating wire 119 extend through wide continuous openings 118a in the rail 118. |
