Bead filler construction

Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor

Patent

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Details

152541, B60C 1504, B29D 3048

Patent

active

051145120

DESCRIPTION:

BRIEF SUMMARY
This invention relates to a bead filler construction, and more particularly to the construction of the component of a pneumatic tire known as the "apex" which fills the approximately triangular space on the radially outer side of each bead portion of the tire.
As described in our co-pending International Patent Application No. PCT/GB 88/00984 published under the Ser. No. WO 89/04259 on May 18th, 1989, in the manufacture of a pneumatic tire a carcass ply of cord-reinforced polymeric material is wrapped around a cylindrical former, annular bead formations comprising an inextensible material such as wire are wound over the tubular carcass ply near its ends, the end portions of the ply are turned up over the bead formations, the ply is given a toroidal shape by inflation of the central portion of the former between the beads and subsequently other components of the tire such as the breaker, tread and sidewalls are added prior to curing the completed assembly in a mould.
If a carcass ply is wrapped over a bead formation e.g. of rectangular cross-section there will evidently be a space approximately of triangular cross-section on the radially outer side of the bead where the carcass ply and sidewall diverge around the bead. It is essential for the stability of a pneumatic tire that this space is filled, and preferably reinforced, by a so-called "apex" component.
Prior to this invention apex components have been provided by cutting to length extrusions of approximately triangular cross-section of rubber or other polymeric material and winding the cut lengths over the bead formations. A principal object of the present invention is to improve upon such techniques.
In accordance with one of its aspects the present invention provides a method of constructing a bead filler or apex in the production of a pneumatic tire, the method comprising helically winding one or more flat strips of polymeric material over the radially outer side of a bead so as to produce an approximately triangular formation of superimposed turns tapering radially outwardly of the bead.
The winding is preferably effected adjacent a flat surface which lies in a place which is generally radial with respect to a former on which the tire is being constructed and from a position displaced toward said flat surface such that successive windings adopt a progressively more oblique orientation in the direction radially outward with respect to the bead being wound upon, thereby contributing to the taper of the finished apex.
The or at least one said strip may be subjected during winding to differential tension so as to reduce its width.
Windings of a relatively harder material such as Kevlar may be alternated with windings of uncured rubber during the formation of the apex.
At least one said strip may be a continuation into the apex region of a strip wound to form the bead in the method of bead construction described in our said co-pending International Patent Application Ser. No. WO 89/04259.
Turns of naked wire may be interposed between turns of uncured rubber. The wire turns may be adjacent said flat surface. Alternatively, or in addition, during the formation of the apex a carcass ply edge may be folded over the incomplete apex and a slit formed therein to permit the continued winding of the apex whereby said edge is incorporated in and locked to the apex formation. In this case a layer of wire windings may be laid over the folded back ply edge within the apex formation and beneath subsequent polymeric windings.


BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described by way of example with reference to the accompanying diagrammatic drawings, in which:
FIGS. 1-5 each are similar cross-sectional views in radial planes through bead and filler or apex assemblies in accordance with the invention.


DETAILED DESCRIPTION

FIG. 1 illustrates a bead 10 generally of rectangular cross-section which has been built as described with reference to FIG. 1 of the drawings of our said co-pending International Patent Application Ser.

REFERENCES:
patent: 1174238 (1916-03-01), Douse
patent: 1406555 (1922-02-01), Hahn
patent: 1482240 (1924-01-01), Marquette
patent: 3935894 (1976-02-01), Pouilloux
patent: 4963207 (1990-10-01), Laurent
patent: 4983239 (1991-01-01), Holroyd et al.

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