Ngk Spark Plug Company, Limited

Masakatsu Hayakawa

Yoshinori Hattori

Masamichi Yamada

Yasuo Inoue

Tooru Takeda

A ceramics spike pin is provided with a pin body having a horizontal cross section of a substantially circular shape, which pin body is provided with a rounded free end portion having a predetermined radius of curvature and a connecting base portion having a predetermined radius of curvature, and a horizontally expanded base connected to the connecting base portion, wherein a diameter (d) of the connecting base portion in horizontal cross section, the radius of curvature(r) of the connecting base portion, and a maximum diagonal length (D) of the horizontally expanded base satisfy the relationship of 0&lt;r&lt;d&lt;D and r.sup.2 .times.d/D.gtoreq.1.36. Accordingly, the stress concentration can be greatly relieved, and the impact resistance can be improved to thereby the durability.

Ceramics spike pin

A die is described, comprising a die body and a steel case, characterized in that: a die body made of a silicon nitride ceramic or a silicon carbide ceramic is shrink fitted or force fitted into a steel case wherein an optional wide recess may be cut in the inner surface of the bottom of said steel case along a corner where the bottom and the inner wall of said steel case meet.

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Nagoya, Japan

Masakatsu Hayakawa