Method of forming a bead with an anchored trailing end

Details Method of forming a bead with an anchored trailing end Method of forming a bead with an anchored trailing end

2000-02-15

2002-07-02

Knable, Geoffrey L. (Department: 1733)

Adhesive bonding and miscellaneous chemical manufacture

Methods

Surface bonding and/or assembly therefor

C152S540000, C156S422000, C245S001500

Reexamination Certificate

active

06413342

ABSTRACT:

TECHNICAL FIELD
This invention relates to a method of forming a bead for a pneumatic tire and, more particularly, to a method of forming a bead where the trailing end of at least one bead wire is anchored in the bead.
BACKGROUND ART
The beads of a pneumatic tire are composed of high tensile steel wire formed into inextensible hoops. The bead functions to anchor the plies of the tire and to hold the tire to the rim of a wheel.
In the manufacture of a tire bead, the bead wire is generally coated with rubber. A leading end of the rubber coated bead wire is secured by a gripping mechanism which is part of a collapsible, ratable bead former. The former is rotated and the rubber coated bead wire is wound around the former a plurality of revolutions. The rubber coating on the wire is uncured so that each revolution of wire adheres to the previously wound revolutions. When the desired cross-sectional shape of the bead is formed, the bead wire is cut to form a trailing end. The trailing end is adhered to the previous revolutions, the former is collapsed, and the bead is removed from the former.
When the bead is built into a pneumatic tire, spring back of the bead wire can occur. During the curing process, the rubber surrounding the bead wire liquefies, reducing its adhesiveness. As the adhesiveness of the rubber is reduced, the bead wire may attempt to spring back to its original shape. This spring back causes the trading end of the bead wire to pull away from the rest of the bead and protrude radially outwardly into the tire. One technique for preventing spring back of the trailing end
12
of the bead wire
14
is to wrap the bead
10
, shown in FIG.
1
and FIG.
2
. After forming the bead
10
, it is placed on a separate machine and is wrapped with a plurality of nylon cords
30
, or a like substitute, at intervals around its circumference. The cords
30
keep the trailing end
12
of the bead wire
14
in place during the curing process. Although wrapping the bead
10
eliminates spring back of the trailing end
12
of the bead wire
14
, the wrapping process increases labor and material costs associated with the manufacture of beads
10
.
Another technique for preventing spring back of the trailing end of the bead wire is to anchor the trailing end within the body of the bead. U.S. Pat. No. 4,938,437 provides a method of manufacturing rubberless single wire tire bead assemblies having at least one end positioned internal to the array of wires comprising the body of the tire bead assembly. This method places all the revolutions of the bead wire on a special former having movable parts and uses the moveable parts to slide the respective revolutions of bead wire into a position surrounding the wire end. This method is limited to rubberless bead wires so the adhesive forces of the uncured rubber coating is not a factor in performing the method.
SUMMARY OF THE INVENTION
This invention provides a method of forming a bead
10
where the trailing end
12
of at least one bead wire
14
is anchored in the bead
10
. The method including the steps of: securing a leading end of the bead wire
14
; winding the bead wire
14
about a former
42
a plurality of revolutions to form the bead
10
into the desired cross-sectional shape; and cutting the bead wire
14
after a last revolution
28
about the former
42
.
The method is characterized by the step of: anchoring the trailing end
12
of the bead wire
14
by driving the trailing end
12
into the bead
10
. The driving of the trailing end
12
forces the trailing end
12
between at least two previously wound, abutting revolutions of the bead wire
14
, at least temporarily separating the respective revolutions.
The method of this invention can be performed using either a rubberless or a rubber coated bead wire.
Definitions
For ease of understanding this disclosure, the following terms are disclosed. “Bead” means that part of the tire comprising an annular tensile member wrapped by ply cords and shaped, with or without other reinforcement elements such as flippers, chippers, apexes, toe guards, and chafers, to fit the design rim. The beads are associated with holding the tire to the wheel rum so that the driving and baking forces are transmitted from the vehicle to the ground. “Pneumatic tire” means a laminated mechanical device of generally toroiddal shape, usually an open torus, having beads and a tread and made of rubber, chemicals, fabric and steel or other materials. When mounted on the wheel of a motor vehicle, the tire through its tread provides traction and contains the fluid that sustains the vehicle load. “Radial” and “radially” are used to mean directions toward or away from the axis of rotation of the tire.


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patent: 4321957 (1982-03-01), Hahn et al.
patent: 4806196 (1989-02-01), Smith et al.
patent: 4820563 (1989-04-01), Rausch
patent: 4938437 (1990-07-01), Rausch
patent: 5567269 (1996-10-01), Golightly
patent: 5603799 (1997-02-01), Kolb et al.
patent: 5820717 (1998-10-01), Siegenthaler
patent: 5882458 (1999-03-01), Kolb et al.
patent: 3613349 (1987-10-01), None

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