Abstract: A spark ignition electrode assembly includes an electrode wire and an electrically insulative support member receiving and positioning the electrode wire proximate to the gas burner. The electrically insulative support member includes an upper body portion covering the electrode wire. The upper body portion contains a spark ignition passageway for communicating spark ignition discharge between the electrode wire and the gas burner. A ceramic material is formed to define the electrically insulative support member having an electrode wire receiving opening for receiving and positioning an electrode wire proximate to the gas burner and a spark ignition passageway for communicating spark ignition discharge between the electrode wire and the gas burner. The electrode wire is inserted in the electrode wire receiving opening and then the formed ceramic material including the inserted electrode wire is fired.

Abstract: A spark plug and method of making same, wherein the spark plug includes an iridium alloy tip portion which may take the form of a rivet or a sphere. The tip portion is coated with platinum, annealed and then resistance welded to a nickel-based electrode of the spark plug. The platinum coating helps to prevent cracks at the welding joint which might otherwise occur due to the differing coefficients of thermal expansion of the iridium-based alloy tip portion and the nickel-based alloy electrode. The iridium alloy tip portion is further not susceptible to attack by lead or combustive gases and therefore increases the life of the spark plug significantly.

Abstract: A hole is formed on a central electrode. A chip has a leg portion. A distal end of the leg portion is entirely united with a bottom surface of the hole by resistance welding. A plurality of fused portions are formed at a boundary between the chip and the central electrode. The fused portions integrate the chip and the central electrode by fusing them together. Each fused portion extends in a radial direction of the chip. The entire periphery of a pointed end of each fused portion penetrates radially inside the outer cylindrical surface of the leg portion of the chip.

Abstract: An electrode assembly having a structure which minimizes stress cracks within its outer housing is disclosed. The outer housing is comprised of a ceramic tube having a bore therethrough which is coated with an epoxy material. An insulated electrical conductor with the wires contained therein in an exposed condition adjacent the end thereof is received in one end of the tube and is slidably advanced within the bore to the approximate midpoint of the tube. An electrode member is received in the opposite end of the tube and is slidably advanced within the bore so that its end contacts the exposed wires of the electrical conductor causing the ends of the wires to flare outwardly and grippingly engage the surface defining the bore in the tube. Subsequent heating of the electrode assembly causes the epoxy within the bore of the tube to bind the tube to the electrode member, the exposed wires and the insulated portion of the electrical conductor resulting in a solid, unitary construction for the electrode assembly.

Abstract: A spark plug (80) having a center electrode (82) with a cylindrical body and having a tip (84) at one end and a terminal (123) near the other end with an insulator (86) extending around the center electrode (82). A ground shield and retainer unit extends around the insulator (86) and includes a threaded portion (88) near one end and a ground electrode (85) near the other end, having a portion thereof aligned with the center electrode tip (84) to form a spark gap, with a sealing portion (92) disposed therebetween for sealing the engine combustion chamber from the outside environment when the spark plug (80) is installed. The ground shield and retainer unit can be formed from two parts (88,90) which are deformed during manufacturing to be in mechanical engagement and securely holding the insulator (86) in place. The spark plug (80) can also have two or more center electrodes (82,84) with two or more corresponding ground electrodes (83,85) projecting from the ground shield (90).

Abstract: Center and earth electrodes are melted at the predetermined regions on the tip thereof where noble metallic chips are fixed. Then, the noble metallic chips are sunk in the melted portions of these center and earth electrodes so as to form protruding portions along outer peripheries of the noble metallic chips. Thus, the noble metallic chips are fixed to the electrodes through the protruding portions. Next, the noble metallic chips are irradiated by energy-condensing light through the protruding portions thus formed. With this irradiation, the center electrode is welded to one noble metallic chip, while the earth electrode is welded to the other noble metallic chip.

Abstract: A method of coating an area of an electrode with an erosion resistant material. The method comprises bringing into contact with the area a web which contains the erosion resistant material and which carries an adhesive so that the web adheres to the electrode. The electrode and the adhered web are then heated to a temperature high enough to cause the adhesive to decompose, volatilize, or both such that the adhesive is substantially eliminated from the web and such that the erosion resistant material fuses and bonds to the electrode.

Abstract: The present invention relates to a spark plug electrode (14) of a first material having good thermal conductivity having a core (24) of a second material having good corrosion resistance. The first material may be copper, or a copper alloy, and the second material may be nickel, a nickel alloy, silver, or a silver alloy. The electrode (14) may be produced by a method comprising the steps of: providing a tubular cup (28) formed of the first material; positioning a billet (34) of the second material within the cup (28); and extruding the assembled cup and billet.

Abstract: To improve the accuracy of the automatic adjustment of a spark plug and the adjustment of the eccentricity of a multiple-electrode spark plug, a spark plug holder 2 for supporting and fixing a lower portion of the multiple-electrode spark plug 1 and a positioning device 3 for supporting and positioning an upper portion of the multiple-electrode spark plug 1 are provided to an adjustor for automatically regulating the gap and the eccentricity of the multiple-electrode spark plug having a center electrode and at least one ground electrode. A projector 4 projects light to the multiple-electrode spark plug 1 from above the positioning device 3. A CCD camera 5 produces images of the spark gap/eccentricity of the multiple-electrode spark plug 1. An image processor 6 executes image processing for inputting the images from the CCD camera 5 and determining the spark gap/eccentricity.

Abstract: A spark plug (10), for example for an internal combustion engine, having at least one center electrode (11) (high-voltage electrode) and at least one earth electrode (12), and an insulating spark plug insulator (13) and a creepage spark gap (14) between the center electrode (11) and the earth electrode (12). The creepage spark gap (14) has a pattern of islands comprising electrically-conductive material (16) which are insulated with respect to one another and are located on the outer surface zone of the spark plug insulator (13) or on the surface zone of an insulating material wafer (17) attached to outer surface of the insulator (13) of the spark plug (10).

Abstract: A center electrode of a spark plug has an oval shape in cross section as an identification mark. An electrode positioning apparatus fixedly holds a ground electrode and rotates an insulator together with a center electrode relative to the ground electrode. During the rotation, a signal light is irradiated toward the center electrode and the shape of the identification mark is detected from the received signal light. When the shape of the mark comes to correspond to a predetermined pattern, the center electrode is stopped from rotating and fitted solidly with the ground electrode.

Abstract: A spark plug (11) having a center conductive path (21) with a cylindrical body having a tip (33, 51, 77) at one end and a terminal (23) near the other end has an insulator (41, 45) radially surrounding the center electrode and a substantially cylindrical body with at least first and second diameter sections separated by a shoulder (29). A ground shield (37) surrounds the insulator first diameter section and including near one end a frustoconical section (31) juxtaposed with the insulator shoulder. There is a ground electrode (55, 57, 73) near the other end having a portion thereof (53, 75) aligned with the center electrode tip to form a spark gap. An annular retainer (59) surrounds the insulator second diameter section and including a threaded portion (61) threadedly engaging the threaded portion (17) of a generally cylindrical opening in the head of an internal combustion engine.

Abstract: In a spark plug having a center electrode and an outer electrode, at least one of which is made of a nickel-alloyed clad and a thermally conductive copper-alloyed core embedded in the nickel-alloyed clad, the copper-alloyed core includes an additive metal which forms a supersaturated solid solution with a copper metal in which the additive metal or an intermetallic compound is precipitated from the copper phase, and substantially evenly dispersed.

Abstract: Generally, the invention include a spark plug with a platinum tip partially embedded in one of the spark plug's electrodes. A spark plug according to the present invention may be prepared by first heating the area of the electrode where the platinum tip is to be attached to a temperature such that the platinum tip may be pushed into and embedded in the electrode. Thereafter the platinum tip is welded to the electrode. Heating the electrode allows the platinum tip to penetrate deeper into the electrode material. This deeper penetration or embedment will reduce the operating temperature at the weld interface (junction) which will in turn reduce the thermal stress and hence prevent cracking of the platinum tip. This deeper penetration or embedment will also reduce the rate of oxidation at the platinum tip near the weld junction and hence prevent cracking of the platinum tip.

Abstract: A method of making a spark plug involves securing an outer electrode to a metallic shell so that at least a portion of the outer electrode is directed inwardly of a front open end of the metallic shell. The outer electrode has an inner surface, an outer surface, and an end surface. A center electrode is supported in an insulator in the metallic shell. A spark-erosion resistant noble metal tip is attached to the outer surface of the outer electrode with a predetermined distance between an elevational side of the center electrode and one end of the spark-erosion resistant noble metal tip.

Abstract: A compound electrode, in particular an electrode for a spark plug, has a core composed of a first electrically conductive material, and a casing deformed to surround the core and composed of a second electrically conductive material. The casing is formed in a single extrusion molding step that also shapes the core and simultaneously forms the cross-sectional profile of the electrode.

Abstract: The present invention includes a spark plug with a copper cored ground electrode wherein the copper core has a cross-sectional area of about 1.6 mm.sup.2 to about 3.0 mm.sup.2 and the remainder of the electrode is made from a nickel alloy sheath. The open end copper cored ground electrode is resistance welded to the steel shell using a light welding force of about 100 lbs. coupled with a low welding energy to eliminate voids and embrittlement in the copper core adjacent to the weld interface.

Abstract: A spark plug is provided which is suitable for use in a spark ignition system for an internal combustion engine. The spark plug is equipped with a specially configured firing tip on each of its electrodes for the purpose of minimizing the demand voltage of the spark plug, as well as extending the life of the spark plug by maximizing the time over which the demand voltage will remain within an acceptable level. For this purpose, the firing tips are configured such that their firing surfaces include at least three edges and three corners which serve as arc initiation sites of a relatively low resistance arc path between the electrodes.

Abstract: In a spark plug, a cylindrical metallic shell has a tubular insulator in which a columnar center electrode is place, a front end of the center electrode extending beyond the insulator. A nobel metal portion is thermally bonded to an outer wall of the front end of the center electrode by means of laser beams so as to form a spark gap between the noble metal portion and a ground electrode which is extended from the metallic shell. The noble metal portion has a molten alloy layer in which the center electrode is melted into the noble metal portion, and a diffused alloy layer in which the noble metal portion is diffused into the center electrode, so that the molten alloy layer forms a spark discharge surface against a front end of the ground electrode.

Abstract: In a spark plug including a cylindrical metallic shell having an insulator in which a center electrode is placed, a front end of which somewhat extends beyond the insulator, a noble metal portion is bonded to an outer side wall of the front end of the center electrode by means of laser beams so as to form a spark gap between the noble metal portion and a ground electrode which is depended from the metallic shell. The noble metal portion has a molten alloy layer in which the center electrode is melted into the noble metal portion, and a diffused alloy layer in which the noble metal portion is diffused into the center electrode.

Abstract: An electrical-discharge electrode, in particular a spark-plug electrode, having a main electrode body made of metal, the main electrode body, in particular at least its tip, is provided with an intermetallic phase composed of nickel aluminides, and a method of producing this electrical-discharge electrode.

Abstract: A method of manufacturing a spark plug electrode, wherein a composite column is provided to have a heat-conductor core embedded in a metallic clad by means of extrusion. A firing tip is provided from a slug which is made of a noble metal. The slug is concentrically placed on an end surface of the metallic clad, and a laser beam welding is applied on the slug to thermally melt the entire the slug so that the end surface of the metallic clad is partly fused into the slug in the range of 0.5 wt % to 80.0 wt %.

Abstract: A spark plug for an internal combustion engine is provided with a fine wire platinum firing tip. The platinum tip is preformed in a rivet before being welded to the center electrode during manufacture of the spark plug.

Abstract: In a spark plug, a nickel-alloyed center electrode has a front end which has a constricted end forming a spark gap with a ground electrode by way of a noble metal firing tip. The noble metal firing tip is secured to a front end surface of the constricted end by applying a laser beam welding to an interface between the constricted end and the firing tip all through their circumferential length so as to form a wedge-shaped welding solidification portion.

Abstract: A method is provided for forming a torch jet spark plug suitable for use in a torch jet-assisted spark ignition system for an internal combustion engine. The torch jet spark plug is configured to ignite a fuel mixture within a combustion prechamber formed integrally within the insulator body of the spark plug, such that a jet emanates from the prechamber and projects into the main combustion chamber of the engine, so as to increase the burning rate within the main chamber. More particularly, the method involves forming a tubular inner electrode on the internal surface of the combustion prechamber by integrating the molding process for the spark plug's insulator body with an inking process by which the inner electrode is formed.

Abstract: In a method of making a spark plug electrode, an electrode blank is prepared to have a firing portion at one end of the electrode blank. A recess is provided at the firing portion of the electrode blank. A noble metal material is placed in the recess. Laser beams are applied on the noble metal material in the recess to melt 70%.about.100% by weight of the noble metal material to form a noble metal tip. A component of the electrode blank is formed from a clad metal wherein the clad metal is thermally fused to the noble metal tip to form a fused portion, such that the clad metal comprises 0.5%.about.80% of the total weight of the fused portion.

Abstract: A method of manufacturing a spark plug cap covering a spark plug for an internal combustion engine, equipped with an ignition voltage detective capacitor having a first conductor housed in a cap body for carrying an ignition voltage produced by an ignition coil to the spark plug and a second conductor located keeping a predetermined distance from the first conductor while sandwiching an insulative material such that the capacitor is formed between the first and second conductors for detecting the ignition voltage. The method comprises separately fabricating said insulative body and a member from the insulative material embedding said second conductor therein and fixing the member at said insulative body such that said detective capacitor is formed. The second conductor may be formed in the shape of a plate to be wound around the cap body.

Abstract: A method of welding a noble metal tip to a spark plug center electrode comprises the steps of placing a plurality of spark plug center electrodes into a plurality of carriers so that each carrier carries one spark plug center electrode, one by one moving each carrier into a weld station, lifting the one spark plug center electrode carried in the carrier located in the weld station out of the carrier into a weld position, clamping the one spark plug center into the weld position with a single clamp located in the weld station, and welding the noble metal tip to the one spark plug center electrode, wherein the single clamp eliminates clamp-to-clamp process variations.

Abstract: In a method of making a spark plug, a recess is provided on an end surface of the electrode blank metal. A straight neck portion is provided around the recess, and forming a tapered surface connecting from the straight neck portion toward an opposite side of the recess. A disc-shaped tip is placed in the recess of the electrode blank metal. The disc-shaped tip is pressed against an inner bottom of the recess in the axial direction of the electrode blank metal, and a laser beam welding is applied to an outer wall of the recess substantially all through its circumferential length by rotating the electrode blank metal.

Abstract: The invention relates to a method for producing a longlife, resistant spark plug for internal combustion engines. The electrode (16), according to the invention, of the spark plug is assembled from a plurality of initial parts: an initial part for a corrosion-resistant shell (31'), an initial part for a core (33') of high thermal conductivity, and an initial part for an erosion-resistant region (32'). These initial parts are jointly impact-extruded to form an electrode blank which is formed into the center electrode (16) by machining its head (51) and its region on the combustion-chamber side. Electrodes which are especially highly stressed are given a fourth initial part, which is also to be impact-extruded, consists of highly erosion-resistant material and is still arranged on the combustion-chamber side in front of the erosion-resistant region (32'). The electrode (16) can be used as a center electrode (16), but can also be used, if necessary, as an earth electrode after an embossing and bending process.

Abstract: In a method of manufacturing a center electrode for a spark plug, a composite column is provided by enclosing a heat-conductor core into a nickel-alloyed clad by means of plastic working. A front end of the nickel-alloyed clad is severed to define a severing and surface with which an axial bore is provided to reach to a front end of the heat-conductor core. A straight neck portion around the axial bore is provided by diametrically reducing the front end of the nickel-alloyed clad. A firing tip made of precious metal is placed in the axial bore. A front end of the firing tip extends beyond the front end of the straight neck portion, while a rear end of the firing tip comes to be in thermally transferable contact with the front end of the heat-conductor core. An outer surface of the firing tip is bonded to an inner surface of the axial bore by means of laser beam welding or electron beam welding.

Abstract: A method for treating spark plugs to increase the horsepower output of an internal combustion engine. The method involves significantly lowering the temperature of the plugs to about -300.degree. F. and keeping the plugs at this temperature for a predetermined time. The temperature is then raised back to room temperature (about 72.degree. F.). After the treated plugs have reached room temperature they may be slowly heated to about +300.degree. F. and held at that temperature for a predetermined time before being gradually cooled back to room temperature.

Abstract: Apparatus and method for welding a platinum wire to a ground electrode of a spark plug to form a contact pad of platinum material that is welded to the ground electrode. The ground electrode is attached to and extends from a metallic spark plug shell. The apparatus includes a pivotally mounted nest for receiving and supporting the spark plug shell. A movable welding electrode can be moved into engagement with a lower surface of the ground electrode. The welding electrode has a spherical end surface that engages the ground electrode. The apparatus has opposed gripping fingers that can be moved toward or away from each other. The gripping fingers each have an inclined surface. When the gripping fingers are moved toward each other their inclined surfaces engage the ground electrode to force it into tight engagement with the spherical end surface of the welding electrode. A source of welding current is connected to the wire and to the welding electrode to weld an end portion of the wire to the ground electrode.

Abstract: 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.

Abstract: To apply an erosion resistant tip, for example a platinum tip to an electrode 10, a wire 12 is fed onto the electrode and the tip welded to the electrode; the end of the wire is severed to leave a pellet 20 attached to the electrode; the pellet is coined and a subsequent welding operation takes place which results in the pellet penetrating into the end face of the electrode.

Abstract: A spark plug (20, 66) which includes a shell (22) having a ground electrode (24) formed integrally therewith into a predetermined final configuration, an annular insulator (34) with a bore (37) extending therethrough, and an electrode (48) positioned within the bore. The insulator is positioned within the opening of the shell by a press fit operation, and the electrode is also positioned within the bore of the insulator by a press fit method.

Abstract: A high tension cable device with a series gap wherein an extraordinary discharge such as a creeping discharge which may occur along an outer face of a glass tube of a discharge tube is prevented effectively and a process of producing the same are disclosed. The high tension cable device comprises an electrically insulating tubular casing and a connecting terminal for the connection to a terminal of an ignition plug of an engine. The connecting terminal is fixedly fitted in the inside of an end portion of the casing, and a high tension cable is fitted in the other end portion of the casing. An additional function part such as a discharge tube for the formation of a series gap is mounted in the inside of the casing and coupled at an end thereof to the connecting terminal and at the other end thereof to the high tension cable, and an electrically insulating resin material is filled in a spacing in the inside of the casing.

Abstract: The center electrode of an ignition plug is a unitary cylindrical tungsten rod in which the outer peripheral portion thereof has a higher work function than the core portion.

Abstract: A strengthened article formed from a ceramic having a bore through a portion thereof and with a metal rod adhered by heat-settable adhesive to the ceramic within the bore thereof. The metal rod has a greater coefficient of thermal expansion than the ceramic thereby placing this ceramic in compression upon heat setting and cooling of the overall article.

Abstract: A preferred embodiment includes a spark plug supporting assembly for supporting a spark having a longitudinal axis such that the gap-defining end of the ground electrode of the spark plug extends substantially perpendicular to the longitudinal axis. A blade assembly is operably associated with the spark plug supporting assembly for splitting the gap-defining end of the ground electrode into at least first and second prongs of substantially equal size. The blade assembly includes a blade member having a longitudinal axis oriented substantially perpendicular to the longitudinal axis of the spark plug. An actuating member is operably associated with the blade assembly to displace the same between a storage position and an operating position while the gap-defining end of the ground electrode is positioned substantially perpendicular to the longitudinal axis of the spark plug.

Abstract: A discharge device of the present invention including a pair of electrodes opposingly disposed in a sealed tube is characterized by the provision of a conductive member surrounding one of the electrodes in the sealed tube. An ignition system with a series gap has a built-in discharge device provided with a series gap, with one end connected to the center electrode side of the spark plug and with the other end connected to the high-tension cable side extending from the high-voltage distribution side. In this ignition system, a discharge device has a conductive member which surrounds one of the electrodes of the sealed tube, and one of the electrodes enclosed with the conductive member of this discharge device works as a cathode.

Abstract: In a method for making a spark plug (10 and 86) with a predetermined spark gap (37), a method for mounting a center electrode assembly (34 and 85) in an insulator bore (25 and 65). A center electrode blank (48 and 80) is positioned in the insulator bore with a tip (36 and 81) projecting to a predetermined location relative to an external shoulder (22 and 62) on the insulator (11 and 55). A thin walled section (49 and 83) of the center electrode blank located above a step (28 and 67) in the insulator bore is heated and deformed to form a shoulder (39 and 84) contacting the bore step.

Abstract: An internal combustion engine includes a cylinder head and a permanent ground electrode and replaceable center electrode element received in a cylinder head bore. The permanent ground electrode is affixed to the cylinder head at the inner wall thereof and protrudes into the combustion chamber. The ground electrode preferably has a cup-like configuration defining an electrode-receiving hollow in the combustion chamber in registry with the bore. The center electrode element comprises a center electrode and an insulator body having a shoulder for engaging a seat in the bore. The insulator body shoulder is clamped against the seat by an annular retainer nut. When the center electrode element is so clamped, the center electrode is received in the electrode-receiving hollow defined by the ground electrode in the combustion chamber so as to cooperate with the ground electrode in defining a spark gap therebetween.

Abstract: A method of producing a spark plug for internal combustion engines comprising arranging a metal piece formed of a noble material on an end face of at least one metal electrode of the spark plug and directing laser beams onto an outer surface of the metal piece facing the spark gap to form an alloy zone between the one metal electrode and a wear-resistant layer facing the spark gap, the alloy zone consisting of materials of the metal electrode and the metal piece with the proportion of the material of the metal electrode continuously decreasing from an area abutting the metal electrode and consisting only of the metal electrode material, to an area abutting the wear-resistant layer which consists only of the material of the metal piece.

Abstract: A metal spark plug shell includes an L-shaped copper core side electrode secured in an axially extending slot on the metal shell. The side electrode includes an attachment end having a portion with an outer side that is threaded contiguous with the metal shell and another portion adjacent the end of the metal shell with a recessed outer side that is unthreaded so as to permit spark plug gapping without breakage of the side electrode. The heat-resistant sheath around the copper core on the inner side of the attachment end may be spot welded to the metal shell.

Abstract: An electrical igniter has an outer shell with a tungsten forward end which forms an annular outer electrode. A central rod extends axially within the shell and has a tungsten forward end forming an inner electrode which is separated from the outer electrode by a semiconductive surface discharge path. The inner and outer electrodes both have chromium diffused into the tungsten to form surface layers that are oxidation resistant at high temperatures. The electrodes are made by placing the tungsten forward ends in a furnace in a chromium rich atmosphere between 1000 and 1200 degrees Centrigrade for between 10 to 24 hours and allowing them to cool in the furnace. Chromium is removed from the rear ends of the tungsten parts before joining them to the rear parts of the electrodes which are of different metals.

Abstract: A process for producing a center electrode for a spark plug comprises the following steps: providing a cylindrical electrode body of a less noble metal which is predominantly made of a nickel alloy or a composite thereof with a copper core, the electrode body having a concentric, smaller-diameter projection from the tip of the body; placing on the tip of the electrode body a disk which has a center hole into which the projection fits and which is made of a noble metal such as platinum or an alloy thereof; electrically welding the noble metal disk to the tip of the electrode body; and drawing and extruding the assembly to reduce its outside diameter so that the layer of the noble metal or alloy thereof covers at least the side wall of the part close to the tip of the electrode body.

Abstract: A spark plug has a center electrode and a side electrode made of an iron-base, heat resistant (iron, chromium, aluminum, rare earth) alloy. Each electrode has a precious metal insert of a composition that thermally matches the base alloy of the electrodes. The electrodes are made by a method which coats the electrodes with a protective coating to reduce operational oxidation and lead/oil deposit degradation of the interface between such iron based heat resistant alloys and an insert button in the center and side electrodes so as to extend the spark plug's life.

Abstract: A spark plug is manufactured by assembling an insulator body and an outer metal shell using an improved crimping die having a specially configured annular working face. The working face includes a flat, annular leading working surface configured to exert a substantial portion of the die force initially on an annular lip of the metal shell to plastically deform the lip inwardly onto an adjacent annular shoulder of the insulator body and a flat, annular trailing working surface configured to subsequently engage the lip and exert a substantial portion of the die force on the shoulder of the insulator body generally perpendicular to the shoulder to internally seal the insulator body and the metal shell by plastically compressing an annular gasket therebetween. The crimping die improves the distribution of the die force on the metal shell and the insulator body to reducew excessive deformation of the metal shell and to enhance compression of the sealing gasket for improved internal sealing purposes.

Abstract: A spark plug for internal combustion engines provided with a noble metal tip on the pointed top of a spark plug center electrode. The noble metal tip is welded to the center electrode top end by heating and pressing the portion to be welded. After the welding, the center electrode is shaped to provide the pointed top. The noble metal tip is a platinum alloy consisting of platinum of 85 through 70 in weight percentage and iridium of 15 through 30 in weight percentage.