Gun for tie wrapping bundles of elongated articles

A tie wrap device for tightly winding a tape loop of a polymeric material tape encirclingly around a bundle of longitudinally arrayed articles, said device comprising

• a pair of jaws movable between an open condition wherein the jaws are positioned to gird the article bundle to a closed condition in which the jaws present an encirclement of the bundle so that a tape feed from a tape stock can be advanced around an inner periphery of the jaws in a bundle encircling loose tape loop that includes overlap of a tape leading end length with stock length remote from the said tape leading end,
• means for tightening the loose loop in a tight closely encircling course about the said article bundle
• an ultra sonic heating horn having a knurled tip end proximal an exterior side location of the tape overlap,
• a clamp having a front face adjacent said heating horn and positioned adjacent below the said tape overlap exterior side location, and
• a pair of anvils having face surfaces positionable in facing relation to an inner side location of the tape overlap and movable to urge at least some of the tape overlap at the exterior side location thereof into tight contact with at least a part of the heating horn tip end, the anvil face surfaces and the horn tip end being configured and disposed such that other parts of the tape overlap at the exterior side thereof are closely proximal the horn tip end,
• said heating horn tip end having at least one inward recess therein extending transversely of the horn tip end and a further inward recess extending longitudinally therein, said recesses accommodating at least some of said other parts of the tape overlap thereby to obviate tight contact of said some other parts with the horn tip end,
• said ultra sonic heating horn being Operable to effect sufficient heating of the tape overlap part in tight contact with the horn tip end to cause melt coalescence of the material in the tape overlap part which upon cooling establishes weldment of at least part of the tape stock leading edge length to at least part of the remote length part, the ultra sonic heating horn being operable to effect at least some molecular alignment disruption in the tape material at the tape overlap exterior side proximal the horn tip end but not in tight contact therewith so that where so disrupted the tape material is weakened sufficiently to allow separation of tape stock upstream of the weldment from the loop along a substantially non residue leaving break course effected with a pulling force applied to the tape stock in a direction upstream of the weldment, said further recess being wider at a top end of the horn tip end than at a bottom end of said horn tip end.