Ngk Spark Plug Company, Limited

Murata Kikai Kabushiki Kaisha

Minoru Ando

Mitsutaka Yoshida

Michiyoshi Washio

Akira Suzuki

Takafumi Oshima

Yutaka Tanaka

Yoshiaki Saiki

Shigahisa Saida

Tsugumi Ichie

Takaaki Mizoguchi

A method of making a metallic shell for a spark plug. The metallic shell includes a multi-stepped through hole, an intermediate tubular portion, a tip end side tubular portion and a base end side tubular portion. The through hole includes a large diameter hole section, an intermediate diameter hole section and a small diameter hole section. The method includes the steps of cutting a metal pipe that is used as a starting material to a predetermined length and thereby preparing a pipe-shaped blank, and subjecting the blank to a deformation process and thereby forming the blank into the metallic shell. A spark plug and a method of making the same are also disclosed.

Method of making metallic shell for spark plug, method of making spark plug having metallic shell and spark plug produced by the same

A method of making a flanged tubular metallic part by cold forging is provided. The method comprises a step of forming an axial depression in a blank and a flange forming step of making the depression axially deeper while causing a metal of the blank to flow radially outward thereby forming the blank into an intermediate product having a flange. The flange forming step includes axially moving an inner punch of a die assembly so as to cause a leading end of the inner punch to be positioned more forward than a backward side surface of the flange thereby causing the intermediate product to be formed with a sleeve portion that is position backward of the flange while allowing an outer punch of the die assembly to apply a biasing force to a backward side surface of the flange during formation of the flange.

Method of making a flanged tubular metallic part

By heating a glass sealing material, a center electrode is sealed and fixed within an axial bore of an insulator. Formation of a groove in a head portion of the center electrode makes it possible to protect the head portion of the center electrode from deformation under a pressure which is applied upon filling the glass sealing material in a powder form in the axial bore. The glass sealing material is therefore assured to flow to a peripheral side wall of a flange portion of the center electrode, thereby enhancing mechanical engagement between the center electrode and the insulator, that is, uniting strength for them. A spark plug is hence obtained with improved impact resistance and accordingly, with sufficient durability.

Spark plug for internal combustion engine

In a spark plug, a tubular insulator has an axial bore in which a center electrode and a terminal electrode are axially aligned, the terminal electrode having a seal portion fixedly supported by partly filling the axial bore with a glass sealant. The insulator further has a tapered shoulder portion between a diameter-reduced portion and a diameter-increased portion, each provided on the insulator. A metallic shell is placed around the diameter-increased portion of the insulator, a rear end of the metallic shell being caulked against the diameter-reduced portion of the insulator, a space between the metallic shell and the diameter-reduced portion of the insulator being filled with a ceramic powder. An inclination of the tapered shoulder portion of the insulator ranges from 10 to 45 degrees against a plane perpendicular to the terminal electrode. A roulette is formed on an outer surface of the seal portion of the terminal electrode in which the glass sealant is filled. A front end of the seal portion of the terminal electrode is located in the range of +5.0 mm to -1.0 mm from a boundary where the tapered shoulder portion meets the diameter-increased portion of the insulator.

Spark plug for an internal combustion engine

A pair-facsimile device in which a pair of facsimile devices having similar performance characteristics are temporarily coupled to each other in a distributing channel starting from a manufacturer to a terailer shop, connected as, one compact integral product and in case of using the facsimile devices, they are separated and each of them is installed at a requisite location.

Pair facsimile devices

In an outer electrode, a rear end of which is securely connected to a metallic shell of a spark plug by means of welding to form a spark gap between a front end of the outer electrode and a firing tip of a center electrode which is concentrically placed within the metallic shell through an insulator, a middle core which is provided which is made of copper, and the middle core is clad by a heat and spark-erosion resistant metal. A centermost core is clad by the middle core. The centermost core is made of a similar metal to the metallic shell, and rear end of the centermost core is welded to the metallic shell so as to reinforce a welding portion between the metallic shell and the outer electrode.

Outer electrode for spark plug and a method of manufacturing thereof

A pair-facsimile device in which a pair of same kinds of facsimile devices are temporarily coupled to each other in a distributing channel starting from a manufacturer to a retailer shop, connected as one compact integral product and in case of using the facsimile devices, they are separated and each of them is installed at a requisite locations.

A method of making terminal nut for ignition plug by plastic working, comprising; first step in which a metallic blank is struck at its end surfaces to flatten the end surfaces in prependicular to axial direction of the blank; second step in which a central conical dent is formed at one end surface of the blank, and forming first bottom-ended hole at other end surface of the blank; third step in which second bottom-ended hole is formed concentrically and continuously from the first bottom-ended hole at the blank to be diametrically lesser than the first bottom-ended hole; fourth step in which the blank is axially contracted to diametrically bulge outward by upsetting; fifth step in which a perforation hole is axially formed at the blank by punching in concentrical relationship with the first bottom-ended hole; sixth step in which the blank is shaved at its bulged portion.

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Nagoya, Japan

Minoru Ando