Tubeless vertical form, fill and seal packaging machine with improved feed means

A tubeless vertical form, fill and seal packaging machine comprising a source of flexible packaging material in the form of an elongated thin flat strip of material of uniform width comprising successive flat package blanks as integral longitudinally contiguous sections thereof, a tube former adapted to receive said strip material and to progressively form the same to a depending and upwardly open tubular configuration, opposite longitudinal edge portions of the material being progressively juxtaposed by said former so as to extend vertically in parallel relationship for side sealing, product dispensing means above said former and operable for the gravity discharge of measured quantities of product, vertically open tubular product guide means beneath said product dispensing means for receiving said measured quantities of product and for directing the same downwardly to the interior of the tube of packaging material through its said upwardly open end, said means extending vertically within said tube former in radially spaced relationship therewith and within the tube of packaging material formed therein, side and end sealing means disposed beneath said tube former and guide means respectively for sealing said vertically extending longitudinal edge portions of the tube and for providing successive longitudinally spaced horizontal end seals across the tube, first and second pairs of vertically spaced rolls respectively on opposite external sides of said tube of packaging material beneath said product guide mean, first and second tube feeding belts respectively trained over said first and second pairs of rolls, each belt having a vertically extending inner run engageable with the external surface of the tube of packaging material, and opposite vertically extending marginal portions of each belt being imperforate and an intermediate portion thereof perforate, vacuum generating means communicating with at least said intermediate perforate portions of each of said belts along their said inner runs to cause the belts to grip the tube of packaging material with the inner belt runs in engagement therewith, tube guide and belt back-up means disposed within the tube of packaging material in engagement with its internal surface and extending vertically opposite at least each imperforate marginal portion of each belt inner run whereby to prevent lateral vacuum loss and to provide for frictional tube feeding action with the inner belt runs externally engaging the tube, and means for driving at least one roll in each of said first and second pairs of rolls to cause said inner belt runs to travel downwardly in unison and thereby to effect combined vacuum-friction tube feeding action positively drawing the tube of material downwardly through the former and successively presenting said integral package blanks therebeneath in tubular form for filling, sealing and package formation.