Abstract A method of and apparatus for heating moldable articles, such as pneumatic rubber tires, is disclosed utilizing an inner expandable bladder having an electrically conductive fluid, such as mercury, salt water, or woods metal. A source of high frequency energy in the range of, illustratively, from 1 to 60 megahertz is coupled between the conductive fluid and the metallic tire vulcanizing apparatus to rapidly heat the inner casing wall surfaces to the desired curing temperatures. A second outer bladder conforming to the casing walls contains a high dielectric constant low thermal loss fluid, such as silicone oil. The inner bladder is contoured to provide a greater volume of such fluid adjacent to the thinner sidewalls and thereby expose the heated conductive fluid closer to the thicker tire tread region. The heating field strengths are thereby distributed substantially uniformly in all parts of a moldable article having a nonsymmetrical cross-sectional configuration and it is maintained in the desired shape during heating.
In a method of heating a moldable annular article with nonuniform walls and substantially hollow interior characterized by a heating cycle wherein the exterior walls are heated to a predetermined temperature in a cavity mold; the steps of: inserting within said interior an outer expandable fluid-tight bladder means conforming to the coutour and adapted to maintain pressure against, as well as dielectrically heat, the inner wall surfaces of the article and an inner bladder means disposed within said outer bladder means; filling said outer expandable bladder means with a fluid having a high dielectric constant low thermal loss characteristic and the inner bladder means with an electrically conductive fluid; and connecting said electrically conductive fluid to a high frequency electromagnetic energy source having a range of from 1 to 60 megahertz.
Claim 2
Dependent Claim
131 words
In a method of heating a moldable annular article with nonuniform walls and substantially hollow interior characterized by a heating cycle wherein the exterior walls are heated to a predetermined temperature in a cavity mold; the steps of: inserting within said interior an outer expandable fluid-tight bladder means conforming to the coutour and adapted to maintain pressure against, as well as dielectrically heat, the inner wall surfaces of the article and an inner bladder means disposed within said outer bladder means; filling said outer expandable bladder means with a fluid having a high dielectric constant low thermal loss characteristic and the inner bladder means with an electrically conductive fluid; and connecting said electrically conductive fluid to a high frequency electromagnetic energy source having a range of from 1 to 60 megahertz.
Claim 3
Dependent Claim
29 words
The method according to claim 1, and the further step of thermally heating both of said fluids within said inner and outer expandable bladder means to a flowing temperature.