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US 6,479,008 B1Granted
Method and apparatus for moulding and curing tires for vehicle wheels
AssigneePirelli Pneumatici S.p.A.
InventorRenato Caretta
Life of this patent
Estimating the term…
Abstract
A green tire manufactured on a toroidal support is closed in a vulcanization mould. Steam or another fluid under pressure is infed to a diffusion gap which is formed, following an expansion of the tire, between the inner surface of the latter and the outer surface of the toroidal support. Tire expansion is compensated for, by axially moving the beads away from the toroidal support, thereby eliminating too strong tensions on the cords forming the tire carcass structure. A pre-cured liner is previously applied to the inner surface of the tire, to prevent diffusion of water particles in the raw elastomer material.
Claims30
A method of moulding and curing tires for vehicle wheels, comprising the following steps:
- disposing a tire on a toroidal support the outer surface of which substantially mates an inner surface of the tire;
- closing the tire and the toroidal support inside a moulding cavity defined in a vulcanization mould, said moulding cavity having walls the shape of which match that of an outer surface of the tire when vulcanization has been completed;
- pressing the outer surface of the tire against the moulding cavity walls;
- transmitting heat to the tire to cause a molecular cross-linking;
- wherein during said pressing step an expansion is imposed to the tire;
- wherein the tire expansion is carried out by admitting a fluid under pressure to at least one gap for fluid diffusion created between the outer surface of the toroidal support and the inner surface of the tire;
- wherein the admission of fluid under pressure takes place to an upper portion of the moulding cavity communicating with a lower portion of the cavity through said diffusion gap;
- drawing fluid under pressure out of the lower portion of the moulding cavity, carried out concurrently with said admission step, so as to create a pressurized fluid stream in the diffusion gap;
- and,
- an axial movement of the inner circumferential edges of the tire from the equatorial plane of the toroidal support carried out concurrently with the tire expansion.
7 more elements
A method of moulding and curing tires for vehicle wheels, comprising the following steps:
- disposing a tire on a toroidal support the outer surface of which substantially mates an inner surface of the tire;
- closing the tire and the toroidal support inside a moulding cavity defined in a vulcanization mould, said moulding cavity having walls the shape of which match that of an outer surface of the tire when vulcanization has been completed;
- enclosing inner circumferential edges of the tire within a bead seating formed by the coupling of inner circumferential portions of the toroidal support and the vulcanization mould;
- pressing the outer surface of the tire against the moulding cavity walls;
- transmitting heat to the tire to cause a molecular cross-linking;
- wherein during said pressing step an expansion is imposed to the tire;
- and,
- separating the inner circumferential edges of the tire from the toroidal support by an axial movement of the inner circumferential edges of the tire away from the toroidal support, wherein said axial movement occurs concurrently with the tire expansion.
5 more elements
An apparatus for moulding and curing tires for vehicle wheels, comprising:
- a toroidal support arranged to engage a tire being processed, said toroidal support having an outer surface substantially mating an inner surface of the tire;
- a vulcanization mould comprising at least two cheeks axially movable between an open condition in which they are mutually spaced apart to enable said toroidal support carrying the tire to be introduced thereinto, and a closed condition in which they mate to enclose the toroidal support carrying said tire within a moulding cavity confined by inner walls of the mould the shape of which match an outer surface of the cured tire;
- pressurizing devices for pressing the outer surface of the tire against the inner walls of the mould;
- heating devices for transmitting heat to the tire enclosed between the moulding cavity and the toroidal support;
- a bead seating formed by the coupling of the inner circumferential portions of the toroidal support and the vulcanization mould;
- and,
- wherein each of said cheeks comprises a radially outer annular portion and a radially inner annular portion acting at a respective inner circumferential edge of the tire and axially movable relative to said outer annular portion between a first position in which the radially inner annular portion abuts against an inner circumferential portion of the toroidal support to engage the inner circumferential edge of the tire within said bead seating, and a second position in which the radially inner annular portion is separated from the toroidal support.
4 more elements
Dependencies are inferred from the claim text.