Patent GB-1185701-A (GB)
Title: Machine for Processing Webs
IPC: B31B70/00
Filed: 1967-01-10
Abstract: 1,185,701. Feeding webs. WINDMOLLER & HOLSCHER. 10 Jan., 1967 [28 Jan., 1966], No. 1279/67. Heading B8R. [Also in Division B5] A machine for intermittently processing a continuously supplied web comprises intermittent web-feeding means located upstream of the processing means, and a dancer roll device located upstream of the intermittent feed means and supported by a loop in the web, the dancer roll device comprising actuating means for a switch which is operated at the lower limit of movement of dancer roll device to start the intermittent feeding-means. As shown, there are two side-by-side web-feeding lines indicated with reference numerals having suffixes a and b respectively, so that a pair of flattened tubular webs of plastic material may be heat-sealed and severed by heat sealing devices 21a, 21b, to form bags; a single wide web may however be similarly processed. Considering one line only, the web may be fed to the apparatus from an extruder or from a printing machine but as shown is fed from a supply roll 1a over guide rollers 3a, 4a, 4b to a feed roller 8a rotating at constant speed. From the roller 8a the web passes around a dancer roller 10a and when the latter reaches its lowest position, a projection 14a on its carrying lever operates a switch 15a, which may be photo-electric or may employ transistors, causing feed rollers 12a to be coupled to a driving motor 18a through a clutch 17a, and a brake 16a to be rendered inoperative. The rollers 21a feed the web to the sealing and severing device 21a at a faster rate than the roller 8a operates, and also drive a pulse generator 19a operating a counter. When the required length has been fed past the sealing device 21a, the counter causes the switch 15a to be restored so as to open the clutch 17a and close the brake 16a so that the rollers 12a are stopped. Simultaneously a solenoid 20a is energized and causes operation of the sealing device 21a under control of a timer. At the end of the set time, the sealing device is rendered inoperative and apparatus described below for delivering the sealed and severed piece of web is actuated. If a printed web with sensing marks at length intervals is being processed, the counter is not required, a photo-electric device 31a being provided to sense the marks and set the processing apparatus in motion. If the other web feeding line is used, the web passes from roll lb over feed roll 5b, dancer roll 7b and roll 8b, the drive of roll 8b being uncoupled. For a wide web, the web is fed by rollers 5a, 5b, and passes around both sets of dancer rolls 7a,7b,lOa,lOb the two sets being connected by a spring 33 so as to move substantially in unison, and the rolls 8a, 8b, being free running. If, when the sealing device opens, the next intermittent feed does not take place immediately or after a predetermined time, due to the continuous speed at which the web is being fed to the apparatus being too low, a green lamp is caused to be lit. The lamp is de-energized by a switch operated by the dancer roll. Should the web be supplied at too high a speed, the switch 15a, when initiating an intermittent feed before expiry of the time set by the time switch controlling the sealing device, can cause premature de-energizing of the sealing device solenoid 20a, and to indicate this a red light is energized by the switch 15a but is de-energized when the time set on the time switch operating the solenoid 20a has expired. Delivery Apparatus.-Belts 24a, 25a, deliver a cut and sealed section of the web against a stop 27a on a table 26. The belts may be driven through clutch and brake devices 29a, 30a operated in unison with the intermittentlyoperating rollers 12a feeding the web to the sealing device. On completion of a sealing and severing operation, a magnet 22a may be energized for a set time to cause a lever 23a to pivot and move the belt 24a against the belt 25a. Similar belts 24b, 26b, deliver the sections from the adjacent line of the machine. Specification 1,165,569 is referred to.