Impulse heat-sealing machine

A machine for sealing together and severing two or more plastic resin films, comprising:

• a base plate upon which the films are positioned;
• a platen movable relative to the base plate and movable toward and away from the films on the base plate;
• compression means to press said platen toward said films at selected times;
• a sealing die mounted on said platen and comprising a heat resistant and electrically insulative rigid substrate, a heat sealing element of etched metal foil having a uniform thickness bonded to said substrate, the width of said heat sealing element being many times its thickness and being sufficiently wide and at least one-sixteenth inch in width to form a liquid leakproof seal of said films, said heat sealing element having a curved portion to form a curved seal, a non-stick layer covering said heat sealing element;
• control means connecting said heater element to a source of voltage for selected short times of less than 5 seconds for impulse resistance heating of said sealing element;
• an electrical resistance knife mounted on said platen and close to said heat sealing element to sever the films by melting, said knife having a curved edge parallel to the curve of said heat sealing element to sever said films along a curved line;
• means connecting said knife to a source of voltage to heat said knife and thereby melt and sever said film.