Patent ID: RE40395

Claim:
A delivery tube assembly for a fastener application machine for delivering fasteners in succession to a fastening station disposed adjacent an exit end of said delivery tube assembly and at which the fasteners are applied to a workpiece, the fasteners each having an elongate shank and a relatively enlarged head at one end having a predetermined major cross-sectional dimension and the application machine having a drive which includes a fastener application plunger, said delivery tube assembly comprising a tubular delivery member having an internal longitudinal passage defined by an internal surface of said tubular delivery member and having a cross-sectional dimension greater than the predetermined major cross-sectional dimension of the enlarged head of the fastener when the shank is substantially aligned with the longitudinal direction of said passage; and radially displaceable guide means, fixedly mounted against longitudinal displacement wholly within said passage of said tubular delivery member , providing a longitudinally uninterrupted and longitudinally indiscrete inside guide surface , fixedly mounted against longitudinal displacement wholly within said passage of said tubular delivery member and extending continuously along substantially the entire longitudinal extent of said internal surface of said tubular delivery member for rendering the a cross-sectional dimension of at least portions of said passage , taken at all points along at least the length of said guide means, smaller than said predetermined major cross-sectional dimension of said enlarged head and for thereby causing said guide surface to form a local passage constriction resulting from bear continuously upon said head in an interference fit with the enlarged head of the fastener as the fastener is guided through said passage to restrain a fastener from free-fall throughout its passage through said delivery tube assembly, the radial displacement of said guide means by the enlarged fastener head producing a local passage constriction being that is longitudinally movable along the delivery tube assembly in response to a force applied to the fastener head by the plunger, said guide means being devoid of structure creating additional constriction adjacent said exit end of said delivery tube assembly, thereby enabling the fastener to advance and be guided along said delivery tube assembly toward the workpiece, and thereupon released at said exit end to the fastening station, while preserving a desired fastener orientation regardless of the orientation of said delivery tube assembly.