Caterpillar Tractor Co.

Glenn A Ball

Charles E Grawey

Donald G Zook

Apparatus includes a rigid mold body and an expandable bladder associated therewith. The bladder is inflatable and expandable to form and press sand core material between itself and the mold body while exerting uniform compressive force over the total surface area of the core material thereby forming a portion of a hollow core of precise external dimension and uniform overall strength. Roll-restraining hoop members can be molded into the sand core at the surface facing the axis of the annulus. A pair of such cores forms a hollow core with two sets of hoops on which a tube-tire is formed.

Core portion for a tube tire

Method of making an annular sand core portion by shaping sand and binder in an annular mold with an inflatable bladder. The bladder is inflatable and expandable to form and press sand core material between itself and the mold body while exerting uniform compressive force over the total surface area of the core material thereby forming a portion of a hollow core of precise external dimension and uniform overall strength.

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Peoria, IL, United States of America

Glenn A Ball