Heat-sealing of thermoplastic

Claim 1

APPARATUS FOR HEAT-SEALING A TRAVELING CONTINUOUS TUBING OF HEAT-SEALABLE THERMOPLASTIC FILM MATERIAL COMPRISING IN COMBINATION A DRUM PROVIDED WITH A SURFACE ADAPTED TO PERMIT COOLING OF HEAT-SEALED TUBING CARRIED THEREON, SAID DRUM BEING DRIVEN ABOUT A SUBSTANTIALLY HORIZONTAL FIXED AXIS, MEANS FOR GUIDING THE TRAVELING TUBING ONTO SAID DRUM, A HEATED SHIFTABLE SEALING BAR DISPOSED ADJACENT SAID DRUM SUBSTANTIALLY PARALLEL TO THE HORIZONTAL AXIS THEREOF, MEANS FOR BRINGING SAID BAR INTO CONTACT WITH SAID TUBING ON THE DRUM AT SUBSTANTIALLY THE POINT WHERE THE TUBING FIRST CONTACTS THE DRUM AND FOR MAINTAINING SAID BAR IN CONTACT WITH SAID TUBING AND DRUM AND STATIONARY WITH RESPECT TO THE DRUM FOR A PREDETERMINED TIME INTERVAL, WHEREBY THE BAR IS CAUSED TO MOVE WITH THE DRUM AND HEAT THE TUBING OVER THE AREA TO BE SEALED, MEANS FOR SHIFTING SAID BAR OUT OF CONTACT WITH SAID TUBING AND DRUM AFTER SAID TIME INTERVAL, MEANS FOR RETURNING SAID BAR TO ITS INITIAL POSITION, AND MEANS FOR MAINTAINING SAID TUBING ON SAID DRUM AFTER HEATING FOR A TIME INTERVAL SUFFICIENT TO PERMIT SAID TUBING TO COOL.