GB250917A - Improvement in method of and apparatus for valving bag tubes - Google Patents

Abstract

250,917. Bates Valve Bag Co., (Assignees of Bates, A. M., Door, G. P., and Dancker, J. E.). April 18, 1925, [Convention date]. Forming valves in bags. - A valve is formed in a bag by pressing together the sides of the bag near one corner, spreading them apart between the corner and the point at which they are held together, and tucking the corner of the bag in between the sides thus spread apart. Rollers B, Fig. 1, feed intermittently in lengths sufficient for two bags, bag tubing 27 previously pierced in a mechanism A by a short longitudinal slit near each side of the tube, the tube passing beneath a cutter 65 for severing the required length and beneath adjacent cutters 69, 70 which extend inwards from opposite sides and cut the tube from the near side to one end of the remote longitudinal slit, thereby removing a rectangular strip of material between the slits and leaving a projecting tongue at the edge of each bag length. As shown, the tube is provided with gusset folds into which project members 102, 105, 104 adapted to guide the tube through the machine. Two valving devices E, F<1> are provided, one at each side of the tube, the two bags operated on being finally removed by take-off devices F, F<1> actuated by shafts 49, 57. The valving devices comprise casings 110, Figs. 2 and 3, within which rods 117 carrying cams 116 are reciprocated by rock shafts 118 operatively connected to the shafts 49, 57 respectively. As the rod 117, Fig. 2, moves to the right the cam 116 opens out the inner ends of two levers pivoted at 114 and closes their outer ends 111 which extend transversely of the bag and grip it between them. The end of the rod then engages a shoulder 127 on a spring-pressed bar 126 one end of which is connected by links 130 to a pair of spreaders 112 pivoted at 129 to the casing. The spreaders 112 are of triangular shape and project into the gusset of the bag, their apices lying substantially in line with the pivot 129. Movement of the bar 126 against its spring 133 turns' the spreaders and causes them to open the gusset until it is fully stretched opposite their apices and the spreaders are enclosed in the triangular pocket thus formed. At this stage, a projection 141 on the bar 126 engages an arm 138 of a bell-crank lever 135, the other arm 136 of which is connected by a link 137 to a tucking finger 113 pivoted about a vertical pivot 134. This finger is turned to a position across the tube and folds the portion of the gusset between the corners and the part enclosing the spreaders inwards between the sides of the bag until an oblique line joining the inner end of the tongue to the part enclosing the spreaders becomes the outer edge of the bag. The rod 117 then returns to its original position, the spring 133 moving the bar 126 to close the spreaders 112 and thereby close the sides of the bag on to the inwardly folded corner forming a kind of flap valve. By this means the apex of the fold of the gusset is first folded outwards at right angles to the edge of the bag and then inwards right back upon itself. A second stop on the bar withdraws the finger 113 which has been kept in place by a friction device 140 on the link 137. Finally, as the cam 116 moves away from the arms of the grippers 111, a spring 147 draws them together, freeing the grippers and permitting removal of the bag.