Importance

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Abstract

A tire building machine and method employing a tire building drum for receiving at least one ply of tire material having an edge overhanging an axial end of the drum, a bladder turn-up mechanism extending axially outwardly from the drum, an annular array of radially contractible ply-down fingers movable axially to and from a position encircling the overhanging ply edge, and an axially movable ring device operative first to effect radial contraction of the ply-down fingers to turn the ply edge down over the end of the drum, then to set a tire bead against the turned down ply edge at the end of the drum, and then to push the bladder of the turn-up mechanism when inflated to cause the ply edge to be progressively wrapped around the bead and then over the drum. In addition to a bead setting ring and a ply-down finger camming ring, the ring mechanism includes a contoured bladder control ring operative axially to push and radially to restrain the bladder, developed pressure in the bladder being reduced after contact is made with the control ring and then held at reduced pressure to allow the control ring to force the bladder to wrap around the bead and roll over the drum thereby to continue progressive wrapping of the ply edge around the bead and then over the drum with a bulge in the bladder forming in front of the axially inwardly moving control ring. Thereafter, the pressure in the bladder is further reduced, particularly in the case of long ply locks, to continue rolling of the bladder at the bulged portion to provide maximum ply lock with relatively low pressure sustained in the bladder. Finally, the bladder is reinflated while simultaneously retracting the control ring.

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First Claim