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US 4,036,271 AGranted
Seamless retread envelope
OwnerFredrick Joseph Prestiinventor
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OwnerFredrick Joseph Prestiinventor
Estimating the term…
A retread envelope press, seamless retread envelope, and method for manufacturing said seamless retread envelope are described as facilitating the production of superior retreaded or recapped tires. In particular, a seamless elastomeric compression-formed envelope is described which is formed and cured in a configuration having a U-shaped radial cross section. The envelope of the present invention also has a rip-resistant bead disposed along its peripheral edges. In manufacturing the envelope, an uncured chloro-butyl rubber slug of appropriate volume is placed in an annular compression chamber defined between two platens. As the platens are moved from a first feed position to a second forming position, the volume of the compression chamber is reduced and the elastomeric slug material is forced around a radially symmetrical core. When the platens reach the forming position, the radially symmetrical core and the platens define therebetween a molding void which is then completely filled with uncured elastomeric material. Compressive forces on the order of from 300 to 600 tons are employed, not only during the above described forming process, but also during a subsequent curing process during which the envelope is heated to a temperature of between 250.degree. and 365.degree. F., said heating being accomplished by introducing steam into a void defined within said core. A seamless retread envelope is produced by this process which is durable and which enables the production of a superior quality retread.
An article of manufacture for encasing the exterior surfaces of a tire having a cured tread adhered thereto by an uncured bonding layer during the curing of said tire, to form a retreaded tire, said article comprising a seamless compression-formed envelope for encasing the tread, bonding layer and side walls of said tire to thereby retain said tread against said tire and to prevent air from contacting said bonding layer, during said curing process, said envelope being compression molded to comprise two parallel, co-cylindrical substantially circular peripheral edges connected and spanned by a single elastomeric web extending radially outwardly from said edges, said elastomeric web having a U-shaped radial cross-section, said web comprising side wall and base wall portions, said side wall portions being generally disposed within parallel spaced apart planes and extending for a distance at least sufficient to encase at least the side walls of said tire to be encased, and said base wall portion being disposed generally within a cylindrical surface which is concentric to and of a radius which is greater than the radius of said peripheral edges by a distance at least as great as the side wall to be encased, said side wall portions and base wall portion being joined to each other by curved connecting portions.
Dependencies are inferred from the claim text.