Champion Spark Plug Company

Jonathan W Hinton

Robert W Matz

Edward J Gehart

Frederick J Powell

Donald S Pratt

A method of and apparatus for forming a pressed body (54) with a bore (56) therein and with a notch (58) in the exterior surface thereof. The body (54) is formed by isostatically pressing particulate material (52) in an elastic mold (14) so that the material (52) is compacted into a self-supporting mass. Used in conjunction with the elastic mold is a mold closure and core holder member (32) to which is fixed a rigid core (42) and a resilient notch defining bar (44).

Method of and apparatus for isostatically pressing a body from

A ceramic insulator and a method for the production thereof are disclosed. The method comprises the steps of pressing ceramic batch around a contoured arbor having at least two longitudinally extending fins to form an outer piece having a bore with grooves therein corresponding to the fins, removing the arbor from and contouring the piece to a desired external shape, pressing ceramic batch to form an inner piece, and contouring the inner piece to fit within the bore of the outer piece. The inner piece is then positioned within the bore of the outer piece and both pieces are fired whereby the insulator is produced in which the contoured surface of the inner piece closes the grooves in the bore of the outer piece to form slots extending longitudinally within the ceramic insulator. Also disclosed is a method which involves firing the inner piece, positioning the fired inner piece within the bore of the unfired outer piece, and then firing both pieces together. A ceramic insulator according to the invention is useful as a support for an oxygen sensor which can be placed in the exhaust gases from an internal combustion engine and used to measure oxygen content thereof to enable control of the air-fuel ratio at which the engine is operated so that, for example, emissions can be minimized.

Method for the production of a ceramic insulator

An improved method for producing a ceramic insulator is disclosed. The method comprises the steps of charging ceramic batch into a longitudinally extending die in which stepped arbors are supported by a plunger, forming a blank by pressing the batch between the arbor plunger and an opposing plunger, ejecting the blank and removing the arbors therefrom, contouring the blank to a desired shape, and firing the contoured blank. The insulator has a length-to-diameter ratio greater than 3:1 but not greater than 8:1; the improvement constitutes controlling the relative movements of the opposing plungers with respect to the longitudinal wall of the die during pressing of the blank so that at least 80 percent of the total plunger movement is in the direction of decreasing arbor diameter whereby variations in the end-to-end density of the insulator are minimized. Where 80 percent to 90 percent of the plunger movement is in the recited direction, a further improvement involves contouring the longitudinal surface of the blank to form generally a solid of revolution about the longitudinal axis of the blank wherein the diameter of the blank is greater than the desired fired diameter by a percentage which varies as an inverse function of the end-to-end density of the blank in order to achieve the desired longitudinal surface contour for the fired blank.

Production of ceramic articles

A high-silica ceramic glaze, having a low coefficient of thermal expansion, suitable for application to alumina bodies, is disclosed. The glaze comprises, by weight percent, about 50 percent SiO.sub.2, from 5 to 8 percent Al.sub.2 O.sub.3, from 6 to 12 percent B.sub.2 O.sub.3, from 2 to 15 percent BaO, from 5 to 8 percent SrO, from 4 to 6 percent CaO, from 2 to 8 percent MgO, from 1 to 2 percent ZnO, and about 5 percent total of Na.sub.2 O, K.sub.2 O, Li.sub.2 O, and minor impurities.

Growing community of inventors

Birmingham, MI, United States of America

Jonathan W Hinton