ES373518A1 - Bag machines - Google Patents

Abstract

In a machine for making bags by intermittently feeding, sealing, and severing a thermoplastic web TW by a reciprocable seal bar assembly 14 the latter is rendered inoperative when the web feed is momentarily interrupted, and actuating means for reciprocating the seal bar assembly 14 can be continued while the seal bar assembly is arrested by interrupting a connection between the actuating means and the seal bar assembly. As shown, a folded and gusseted web TW is intermittently drawn by rolls 12, 12 beneath the seal bar assembly 14 and over a co-operating seal roll 56, the reciprocal movements of the seal bar assembly 14 being coordinated with the web feed to sever and weld the web TW transversely and form individual bags which are transported, between upper and lower conveyers 60, 64, to a stacking table 18 where they are stacked against sheet metal frames 96. The seal bar assembly 14 comprises a seal bar 54 connected by metal clips 52 to a beam 48 which has stub shafts 50 mounted in respective posts 46 each of which rests upon a plate 84 secured to the upper end of a respective push rod 74. A roller 78, at the lower end of each rod 74 is loaded by a spring 92 against a corresponding cam plate 80 which is keyed to a drive shaft 82 so that the seal bar assembly 14 is intermittently raised and lowered to cooperate with the seal roll 56 during normal running of the machine. The machine can be temporarily stopped, e.g. while a completed stack of bags is being removed from the table 18, by pressing a foot switch FS which causes pneumatic cylinders 28 to extend their pistonrods 36 so that nylon blocks 38 on the ends thereof are moved to engage beneath blocks 44 on the posts 46 and hold them raised in an inoperative position while the machine is stopped. The posts 46 can also be held raised and inoperative while the machine is running by actuating pneumatic cylinders 86 each of which is mounted on a respective plate 84 and has an actuating rod 88 connected to an ear 90 on the post 46, the upper end of each rod slidingly engaging in openings in the respective posts 46 with lost motion. The switch (FS) can be over-ridden by a toggle switch (S9) for longer shut - down periods. The upper conveyer 64 is movable toward and away from the lower conveyer 60 in synchronism with the intermittent motion of the machine. A limit switch (5LS), providing a machine timed switching for count pulses, has two sets of'contacts, one for pulsing a totalizer counter and the other for pulsing a predetermined counter. A limit switch (6LS) also provides a machine timed pulse which ensures stopping and starting the machine at a certain point in its cycle to eliminate the possibility of a partial draw of the thermoplastic web. The circuit diagram of the electrical control circuit for initiating an interrupt cycle of the machine is described with reference to Fig. 7, not shown.