Wrapping machine and method with four side rotary tucker

Claim 1

In a wrapping machine wherein a series of longitudinally spaced articles are inserted in a moving tube of wrapping material formed from a flat strip of thermoplastic material, said tube having top and bottom walls and side walls and being laden with such longitudinally spaced articles, means for feeding the laden tube along a longitudinal path, means for tucking the side walls of the tube portions between articles toward the longitudinal axis of the tube, rotary vertically spaced shafts located above and below the path of the tube, top and bottom tube wall deflecting and bonding means mounted on said shafts, means for simultaneously rotating said shafts and tube deflecting and bonding means in opposite directions for simultaneously deflecting and bonding the top and bottom walls of the tube being fed therebetween at portions of the tube between articles, and means for transversely severing the tube at the bond; the improvement wherein said top and bottom tube wall deflecting and bonding means comprises upper and lower elongate, generally rectangular shoes respectively secured to said shafts, said shoes each having a single tube deflecting and bonding foot that cooperate at each bond, said feet each having convexly curved central tube bonding portions flanked by radially inwardly recessed portions at each side of the bonding portion to thereby cooperatively define end slots in the feet as the central tube bonding portions deflect the top and bottom walls of the tube, said slots being completely open and un-confined by said shoes at their ends and at their upstream and downstream edges, means for heating said feet to effect bonding of the deflected top and bottom walls of the tube by the central tube bonding foot portions along a single, relatively narrow transverse central area, said side wall tucking means comprising simultaneously rotatable shafts located adjacent opposite side walls of said tube, thin blade-like tucking shoes secured to and projecting from said shafts and rotating in a plane containing said slots, said tucking shoes having free end portions for simultaneously passing through their respective slots to tuck the tube side walls so that the innermost portion of each tuck is adjacent the ends of the associated central tube bonding portions of said feet substantially concurrently with the bonding operation, said tucking shoes being positioned so that a single end portion enters its respective slot during the deflection and bonding of the tube by the central portions of said feet, said tube feeding means comprising means for tensioning the unoccupied tube portions between articles for providing controlled deflection and tucking thereof, said tensioning means comprising longitudinally spaced pairs of laterally opposed belts making frictional contact with opposed walls of the tube, one pair of said belts being located upstream of said upper and lower tube wall deflecting and bonding means while the other pair is located downstream thereof, and means for driving said pairs of belts at different speeds for maintaining tension of said unoccupied tube portions between spaced articles and rendering said tube portions taut both upstream and downstream of the tucking and bonding means during the tucking and bonding operations at said tube portions, said downstream belts accommodating longitudinal movement of the downstream article toward the upstream article during said tube deflecting and tucking operations, said tucked side portions and said top and bottom wall portions of the tube being unconfined between the zone of said tucking shoes and bonding shoe portions and the ends of articles disposed directly upstream and downstream thereof during the aforesaid action of said tucking shoes and bonding shoe portions, said tube severing means being disposed downstream of said tube deflecting and bonding means and including means for bonding the tube walls entirely across the width of the tube.