Patent GB-874814-A (GB)
Title: Manufacture of draw cord bags
Inventor: ASHTON GEORGE HENRY
IPC: B31B19/90
Filed: 1959-05-22
Abstract: 874,814. Bag-making machines. BEMIS BROS. BAG CO. May 22, 1959, No. 17600/59. Class 94(2). A bag-making machine comprises means for intermittently feeding a web of heat-sealable material of a length corresponding to the desired bag width, means for introducing a cord into an open hem formed along each side of the web, the cords extending longitudinally through the hems and traversing openings therein, means for attaching the hems to the walls of the web after the cords have been introduced, means for gathering those portions of the cards exposed through the openings and pulling them out to form a loop, means for severing the cards at the loop and means for securing the cards at two points spaced along the length of the loop and at opposite sides of the point of severance. The web 1, e.g. of polythene, with its margins 23, 25 continuously folded back by known means is drawn through continuously driven feed rolls 13, 15 and around a dancer roll 33 carried on a pivoted frame 55 which regulates the feed by swinging up to actuate a limit switch 61 and so to increase the speed of the rolls 13, 15 to provide more slack in the web and, when there is too much slack, by swinging down and actuating a limit switch 63 to decrease the roll speed. Rolls 37, 39 are geared together and roll 37 is driven through an electric clutch 89 from a shaft 83 on which is a pinion 81. The pinion 81 gears with a sector gear 77 which is oscillated about a pivot 79 by a link 75 from a crank pin 73 on a gear wheel 71, this being driven from the driving shaft 43 and driving also cam-shafts 67 and 97. Cams on the shaft 97 operate switches alternately to engage the clutch 89 and an electric brake 93, resulting in intermittent rotation of the rolls 37, 39 and therefore stepby-step feeding of the web. The ends of the link 75 may be altered in position to vary the amount fed on each cycle. After the web has left the tension-adjusting device it is acted on by a device 107 to form notches in its margin at intervals corresponding to the width of a bag. A cam-shaft 263, Fig. 10, is driven from the shaft 67 and a cam 363 thereon operates a switch 359 which in turn operates a solenoid valve 353, Fig. 11, through which air pressure is supplied to a cylinder 145, Fig. 14, the pistonrod 147 of which depresses a clamp member 135 in which is housed a ball 137 so that a notch is punched out from the margin of the web between the ball 137 and a circular anvil 127. A cam 401 operates a switch 397 which in turn operates a solenoid valve 387, Fig. 11, which controls air cylinders 233, 237. When air is vented from below the piston of the cylinder 233, Fig. 15; a spring 231 presses down a roll 225 so that the pressure between the rolls 225, 223 grips the cords 157, 161,between the hem portions 23, 25 so that they are unwound from reels 159, 163, being guided into the hem portions by pulleys 153, 155. The operation of the switch 359 also causes a solenoid valve 367 to function to supply air to the lower end of a cylinder 211 and to open a port 207 at the upper end of the cylinder 195, Fig. 17, resulting in the piston-rod 215 rising from the cylinder 211 to rock an arm 193 in a direction to lower an arm 181 on the end of which is a sealing bar 185. Through gearing 179, an arm 183 is rocked in a direction to raise a sealing bar 187. The sealing bars incorporate electric heaters and are yieldingly mounted through springs 191. The sealing bars 185, 187 approach and seal the hems 23, 25 to the walls 5, 7 of the web, disclosing the cords 157, 161, a plate 221 being interposed. At 272 is a clamp comprising, Fig. 9, a block 275 and a vertical air cylinder 277 above the block. The solenoid valve 387 also controls the supply and exhaust of air to and from the cylinder 277. By admitting air pressure above the piston 279 it is driven downwards against a spring 281 so that a presser foot 285 clamps the cords 157, 161 against the block during a dwell period in the intermittent feed of the web, during which period also the rolls 223, 225 are separated. The shaft 263 carries another cam 261, Fig. 22, which swings an arm 247 upwards during each dwell period of the web. The bracket 251 on which the arm 247 is mounted is movable and its position is adjusted so that the end of the arm 247 ends in a notch 109 that was formed in the side of the web by the device 107. As it does so it catches the cords 157, 161 in a recess 269 and it draws them outwards to form a loop L, Fig. 19, the cords being clamped against the block 275 and extra length for the loop being drawn from the reels 159, 163. A cam 385 on the cam-shaft 263 actuates a switch 383 to energize solenoids 303 through which tripping means 301 cause the engagement of single-revolution clutches 299 through which are driven stapling machines 289 of known construction, left- and right-hand mounted and their staple-driving members 291, acting in conjunction with recesses in the arm 247, clinch staples round the cords. When the solenoid valve 353 is operated it also supplies air pressure to a cylinder 307 which causes a knife 305 to cut the cords between the two staples. Cams 337 on the shaft 67 raise a roll 325 towards a knife 323, Fig. 26, during the dwell period of the intermittent feed rolls 37, 39 i.e. when the web is stationary, the roll 325 being intermittently driven by a chain 343 from the roll 37. The knife 323 incorporates electric resistance heaters 326, and the web is cut and simultaneously heat-sealed along the cut edges, thereby forming bags as in Fig. 6, H being the lines of heat-sealing. The bags are delivered on a conveyer 345, with a drive 347 including a variable speed transmission 349. Air is directed through a pipe 351 to blow the cut ends of the cords from between the knife 323 and the roll 325.