Fastener delivery tube

Abstract

A fastener delivery tube ( 21 ) incorporates an internal guide ( 22 )—such as a continuous sleeve lining, flexible, or resiliently deformable spring strips ( 34, 37, 38 ) or re-circulating balls ( 54 )—forming a longitudinally movable constriction, inhibiting fastener free-fall through the tube and preserving fastener orientation, by maintaining fastener ( 25 ) contact with a driving plunger ( 28 ) in its passage there-through and upon exit there-from into contact with a workpiece.

1. 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. 
     
     
       2. A delivery tube as defined in  claim 1 , wherein said displaceable guide means comprises an internal tubular lining made of a resiliently deformable material. 
     
     
       3. A delivery tube as defined in  claim 1 , wherein said displaceable guide means comprises a plurality of longitudinally extending guide elements formed of a resiliently deformable material and disposed in a circumferentially-spaced array about said internal surface. 
     
     
       4. A delivery tube as defined in  claim 3 , wherein said guide elements comprise inwardly projecting ribs formed on an internal tubular sleeve. 
     
     
       5. A delivery tube as defined in  claim 1 , wherein said displaceable guide means comprises a plurality of circumferentially spaced, resiliently-deformable inwardly-projecting strips. 
     
     
       6. A delivery tube as defined in  claim 1 , wherein said displaceable guide means comprises a plurality of circumferentially-spaced, rigid or semi-rigid strips, and biassing means for biassing said strips inwardly into said passage. 
     
     
       7. A delivery tube as defined in  claim 1 , wherein said displaceable guide means comprises a plurality of circumferentially-spaced ball bearing assemblies, looped tracks for said ball bearing assemblies, at least portions of said looped tracks being arranged longitudinally along said passage, and a plurality of fastener head contact ball bearings circulating in said tracks. 
     
     
       8. A delivery tube for a fastener application machine for delivering fasteners in succession to a fastening station at which the fasteners are applied to a workpiece, the fasteners each having an elongate shank and a relatively enlarged head having a predetermined cross-sectional dimension and the application machine having a drive which includes a fastener application plunger, the delivery tube comprising a tubular member provided with an internal longitudinal passage defining an internal surface and having a cross-sectional dimension greater than the predetermined cross-sectional dimension of the enlarged head of the fastener when the shank is substantially aligned with the longitudinal direction of said passage; and displaceable guide means extending substantially along the entire longitudinal extent of said internal surface of the delivery tube for rendering the cross-sectional dimension of at least portions of said passage smaller than said predetermined cross-sectional dimension of said enlarged head to form a constriction resulting from 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 through said passage and for providing local passage constriction longitudinally movable along the delivery tube in response to a force applied to the fastener head by the plunger for preserving a desired fastener orientation while enabling the fastener to advance and be guided along the delivery tube to the fastening station, said displaceable guide means comprising a plurality of circumferentially-spaced ball bearing assemblies, looped tracks for said ball bearing assemblies, at least portions of said looped tracks being arranged longitudinally along said passage, and a plurality of fastener head contact ball bearings circulating in said tracks. 
     
     
       9. A delivery tube for a fastener application machine for delivering fasteners in succession to a workpiece, the fasteners each having an elongated shank and a relatively enlarged head and the application machine having a drive which includes a fastener application plunger, the delivery tube having an internal longitudinal passage and a displaceable guide means extending substantially along the entire longitudinal extent of said internal passage to reduce its internal diameter over at least part of its internal periphery to form a constriction resulting from an interference fit with the enlarged head of the fastener as the fastener is guided through said passage to restrain the fastener from free-fall through said passage and to provide local passage constriction longitudinally movable along the delivery tube to preserve a desired fastener orientation while the fastener is advanced and guided along the delivery tube to the workpiece in response to a force applied to the fastener head by the plunger. 
     
     
       10. A delivery tube for a fastener application machine for delivering fasteners in succession to a workpiece, the fasteners each having an elongated shank and a relatively enlarged head and the application machine having a drive which includes a fastener application plunger, the delivery tube having an internal longitudinal passage and a displaceable guide means extending substantially along the entire longitudinal extent of said internal passage to reduce its internal diameter over at least part of its internal periphery to form a constriction resulting from an interference fit with the enlarged head of the fastener as the fastener is guided through said passage to restrain the fastener from free-fall through said passage and to provide local passage constriction longitudinally movable along the delivery tube to preserve a desired fastener orientation while the fastener is advanced and guided along the delivery tube to the workpiece in response to a force applied to the fastener head by the plunger, said displaceable guide means comprising a plurality of circumferentially-spaced ball bearing assemblies, looped tracks for said ball bearing assemblies, at least portions of said looped tracks being arranged longitudinally along said passage, and a plurality of fastener head contact ball bearings circulating in said tracks.