Apparatus and method for continuous tread production
AssigneeThe Firestone Tire & Rubber Company
InventorsGeorge G. A. Bohm, Stanley S. Gross
Life of this patent
Estimating the term…
Abstract
An apparatus and processes for the production of a continuous rubber strip which is molded with surface designs, such as tire treads, in the uncured state and then cured, after removal from the mold, by heat or radiation is disclosed. In the apparatus the extruded rubber strip is passed between cooperating mold segments carried by respective endless belts which, along with related components, apply suitable temperatures and pressures to the strip to produce the surface designs. The molded uncured rubber strip is removed from the molds and then completely cured by radiation and/or heat. Process embodiments are also disclosed wherein partial curing of the rubber while in the molding apparatus is performed.
Claims24
A method for producing a continuous rubber strip with a surface design comprising the steps of:
- extruding uncured rubber into a continuous strip at a temperature below its curing temperature;
- impressing a design on said continuous strip by passing said strip between moving cooperating mold segments while impressing a high pressure of about 1000 psi to force the rubber into the design pattern of the mold at a temperature below the curing temperature of the rubber;
- maintaining a lower pressure on said strip after the imposition of said high pressure while said strip remains between said cooperating mold segments;
- removing the molded strip in the uncured state from between the moving mold segments;
- and
- curing the rubber of the molded strip after removal from the mold segments.
A method for producing a continuous rubber strip with a surface design comprising the steps of:
- extruding uncured rubber compounded with a heat curing agent into a continuous strip at a temperature below the curing temperature of the rubber;
- after extrusion, heating said continuous strip uniformly to a temperature sufficient to induce partial curing throughout the uncured rubber;
- before the onset of cure in the rubber, impressing a design on said heated continuous strip by passing said strip between cooperating mold segments moving therewith while impressing a high pressure of about 1000 psi to force the rubber into the design pattern of the mold;
- maintaining a lower pressure on said strip after the imposition of said high pressure while partial curing is occurring in the rubber and said strip remains between said cooperating mold segments;
- completing curing of the rubber throughout the molded strip by heat after removal from the mold segments.
A method for producing a continuous rubber strip with a surface design comprising the steps of:
- extruding uncured rubber compounded with a heat curing agent into a continuous strip at a temperature below the curing temperature of the rubber;
- impressing a design on said heated continuous strip by passing said strip between cooperating mold segments moving therewith while impressing a pressure of about 1000 psi to force the rubber into the design pattern of the mold;
- heating the mold surfaces to a temperature sufficient to induce partial curing of the surface portion of the rubber strip in contact with the mold surface;
- before the onset of surface curing in the rubber releasing the pressure of about 1000 psi and maintaining a lower pressure on said strip after the imposition of said 1000 psi pressure while partial curing is occurring in the surface of the rubber and said strip remains between said cooperating mold segments;
- removing the molded strip with the partially cured surface from between the moving mold segments;
- and
- completing curing of the rubber throughout the molded strip after removal from the mold segments.
A method for producing a continuous rubber strip with a surface design, such as a tire tread, thereon comprising the steps of:
- extruding uncured rubber into a continuous strip at a temperature of about 100.degree. C.;
- preheating said continuous strip to a temperature in the range between 120.degree. C. to just below its curing temperature to soften said rubber;
- impressing a design on said continuous strip by passing said strip between moving cooperating mold segments while impressing a high pressure of the order of 1000 psi to force the rubber into the design pattern of the mold at a temperature below the curing temperature of the rubber;
- maintaining a lower pressure, in the range from ambient to just below said high pressure, after the imposition of and for a longer time than said high pressure while said strip remains between said cooperating mold segments;
- removing the molded strip in the uncured state from between the moving mold segments;
- and
- curing the rubber of the molded strip after removal from the mold segments.
Dependencies are inferred from the claim text.