| 摘要 |
1470653 Making bottom folded bags; seaming NATIONAL PETRO-CHEMICAL CORP 6 June 1974 [1 May 1973] 20676/73 Headings B5D and B5K In an apparatus for forming bottom folded bags, Fig. 14, lower and upper grippers 56 and 114 which grip a side gussetted bag section at lower and upper side edges GEL and GEU adjacent a sealed end S, are movable at different speeds in the longitudinal direction of the bag section to fold the bottom. The lower grippers are moved faster than the upper grippers when the sealed end S is the leading end, and the upper grippers are the faster when the sealed end S trails. In the embodiment shown the slower moving upper grippers 114 are inclined upwardly in the direction of feed of the bag sections, and bars (160) Fig. 15 (not shown) which are carried with the lower grippers, can lie in the top walls of the bag sections to define edges about which the top walls are folded during the bottom folding. The lower grippers may also carry a spacer (162) Fig. 15 (not shown) to open the gussets. In operation of the apparatus, guides 61 open the gussets in a web which has been subjected to flame treatment and printed on, and guide the lower grippers 56 which are carried by chains 54, into engagement with the lower edges GEL of the web. Heated sealing bars 62 and back-up bars (68) Fig. 1 (not shown) which are mounted between respective conveyor chains 64 and (70) Fig. 1 (not shown) for movement with the web, then transversely heat seal the web at spaced intervals. Adjustable pressing bars (76) Fig. 8 (not shown) are provided behind at least the heated sealing bars 62. The bag sections are severed from the sealed web by a rotary cutter and opened by a blast of ionized air from a nozzle 98 to facilitate the gripping of the upper edges GEU by the grippers 114. After the bottom folding, brushes 144 deaerate the bags prior to the bags being pressed by pressing belts (148, 157) Fig. 2 (not shown). The finished bags are stacked and the resulting bundle wrapped. |
