Institute of Technology Precision Electrical Discharge Work's

Bridgestone Tire Company Limited

Bridgeport Tire Co. Ltd.

Koichi Hirano

Shoji Futamura

Kenichi Takahashi

A tire manufacturing mold having a contour surface consisting of a predetermined curved surface corresponding to the outer circumferential surface of a tire being molded, a plurality of bone portions and blade portions, both protruding on the contour surface, and a manufacturing method of the same are disclosed. The tire manufacturing mold is manufactured by discharge machining in such a manner that the blade portions are caused to protrude essentially vertically to the contour surface, and that the contour surface, the bone portions and the blade portions are integrally formed.

Tire manufacturing mold

A method of making a mold which is utilized to manufacture a tire, the mold having a contour curved surface with broad bone portions and narrow blade portions extending therefrom, comprises a first machining stage utilizing a plurality of electrical discharge machining electrodes for approaching a workpiece used to make the mold, at different angles. Each of the electrodes used in the first machining stage are shaped to avoid the removal of excessive metal from the mold so that both the bone portions and the blade portions can extend normally from the contour curved surface. The method includes a second machining stage utilizing a further electrical discharge machining electrode which has recesses for receiving bone portions and blade portions formed by the first stage electrodes, and is movable laterally of the contour surface to form well-defined edges of the bone and blade portions.

Method for manufacturing tire molding metal molds with a two-stage

A ring-shaped mold of the split mold type constructed by assembling into an annular shape a plurality of sectorial separate blocks formed by cutting a ring-shaped workpiece haveing a mold surface on the annular circumference thereof, and the method and apparatus for making the same are disclosed. Sector lines interfacing adjoining the separate blocks on the mold surface intersect the circumference of the ring-shaped mold at angles not perpendicular to said circumference.

Method for making a ring-shaped mold

A system for manufacturing tire molding metal molds with electrical discharge machining is disclosed, which makes possible the rotation, longitudinal and cross feeding of a work table on which a workpiece to be machined into a tire molding metal mold is placed and the rotation, lifting and lowering of a machining head, whereby the workpiece is discharge-machined by feeding a discharge machining electrode in a plurality of different directions corresponding to a plurality of projections protruding essentially vertical to the tire molding surface of the tire molding metal mold to be machined, and by changing electrodes having such profiles as to prevent the excess metal removal of the projections in accordance with each of the electrode feeding directions.

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Kodaira, Japan

Koichi Hirano