Heat sealing jaw assembly with film slackener

A process for heat sealing pouches from a tube of thermoplastic film in a vertical form, fill and seal machine, said machine having an opposing pair of jaws facing the tube, at least being capable of moving toward and away from the other jaw to collapse the tube therebetween;

• a heat sealing element on one jaw facing the tube;
• and a pad on the other jaw facing the heat sealing element, said process comprising the steps of:
• 1) gripping the tube with top clamping elements at a top gripping point above the heat sealing element and with bottom clamping elements at a bottom gripping point below the heat sealing element;
• 2) moving the top gripping point and bottom gripping point toward the heat sealing element thereby relieving tension and forming a slack section in the film of the tube between the top clamping elements and the bottom clamping elements;
• 3) moving the heat seal element and the pad toward each other to meet in the slack section of the tube;
• 4) activating the heat seal element to produce a top heat seal of a previously filled pouch and a bottom heat seal of a next-to-be-filled pouch, said top and bottom heat seals being in the slack section of the tube;
• 6) severing the tube between the top and bottom heat seals;
• 7) deactivating and moving the heat seal element and pad away from said heat seals;
• and
• 8) releasing the tube from the top and bottom clamping elements.