Method and apparatus for performing local working at regular distances on a continuously advancing web of material

Claim 1

AN APPARATUS FOR HEAT SEALING A CONTINUOUS WEB OF MATERIAL AT LOCATIONS WHICH ARE SPACED APART ALONG THE LATTER, COMPRISING MEANS DEFINING AN OPERATION ZONE CONTAINING CONVEYING MECHANISM INCLUDING GRIPPING MEANS MOVING CONTINUOUSLY ALONG A PREDETERMINED PATH AT A RELATIVELY SLOW SPEED AND SPACED APART IN THE DIRECTION ALONG SAID PATH BY DISTANCES SMALLER THAN THAT BETWEEN THE LOCATIONS ON THE WEB WHERE THE LATTER IS TO BE HEAT SEALED, MEANS FOR SUPPLYING THE WEB TO SAID CONVEYING MECHANISM AT ONE END OF SAID PATH AT A RELATIVELY HIGH SPEED WHERE SAID GRIPPING MEANS GRIP THE WEB AT SAID LOCATIONS WHERE THE WEB IS TO BE HEAT SEALED AND THEN CONVEY THE GRIPPED LOCATIONS ALONG SAID PATH, WHILE EXCESS LENGTHS OF THE WEB FORM LOOPS BETWEEN THE ADJACENT SPACED APART GRIPPING MEANS AND OPERATIVE TO HEAT CIATED WITH SAID GRIPPING MEANS AND OPERATIVE TO HEAT SEAL THE WEB AT THE GRIPPED LOCATIONS AS THE LATTER ARE CONVEYED ALONG SAID PATH, AND DELIVERY MEANS RECEIVING THE HEAT SEALED WEB FROM SAID CONVEYING MECHANISM AND ADVANCING THE HEAT SEALED WEB AT A SPEED SUBSTANTIALLY EQUAL TO SAID RELATIVELY HIGH SPEED OF THE WEB SUPPLYING MEANS IN ORDER TO TAKE-UP SLACK IN THE WEB REPRESENTED BY THE LOOPS FORMED IN THE LATTER BETWEEN SAID GRIPPING MEANS.