Spring finger ply downs are generally employed at each axial end of the drum of a tire building machine. Such assemblies generally comprise an array of axially extending spring fingers which project toward the center of the drum and which in their unflexed condition extend at an angle radially outwardly. Such fingers are usually flexed inwardly by the axial movement of a bead setting device causing the ends thereof to sweep or fold inwardly liner or ply material overhanging the ends of the drum. In this manner the materials of the tire are turned down over the shoulder or edge of the drum to form a shoulder of tire material rigidly backed by the edge or shoulder of the drum to receive the tire bead. Thereafter with the bead setter and ply down assembly retracted, the ply material will normally be turned and stitched around the bead and up over the top of the drum by a dual bladder assembly such as seen, for example, in Cantarutti U.S. Pat. No. 3,438,832, or the copending application of George E. Enders entitled "Tire Building Machine" Ser. No. 122,605, filed Feb. 19, 1980.
A problem arises in spring finger ply down assemblies in that they are difficult to assemble and it is also difficult to replace a finger which may become damaged or bent. As an analogy, the problem is similar to trying to assemble a barrel without special tools or jigs, or trying to replace a single barrel stave without affecting adjacent barrel staves. Usually the fingers are clamped between two rings but to assemble the fingers or remove a single finger requires the rings to be separated sufficiently to accomplish the purpose. This is difficult to do without affecting or loosening adjacent fingers.
USPTO Backgrounds
USPTO Backgrounds