Abstract: A method for producing a spark plug, the spark plug including: a center electrode; an insulator which holds the center electrode therein in a state where a tip end portion of the center electrode protrudes therefrom; a metal shell which holds the insulator therein; a ground electrode which is fixed to the metal shell, the ground electrode having an inner side face having a width that is smaller as it advances toward a tip end side, in a portion of the inner side face positioned between a pair of tapered faces; and a discharge portion which is bonded to the inner side face of the ground electrode by laser welding so as to attain a diameter of 0.8 mm or less and a height of 0.5 mm or more, a discharge gap being formed between the discharge portion and the tip end portion of said center electrode, the method including: forming the tapered faces before the discharge portion is laser-welded to the inner side face.

Abstract: A noble-metal chip 30, 90 joined to at least either a center electrode or a ground electrode, the center and ground electrodes forming a spark discharge gap, and having a circumferential edge of its facing end surface 31, 91 removed so as to form an edge-removed portion 32, 92. The edge-removal length is 0.01 mm or more and a ratio of the edge-removal length to a radius of the noble-metal chip is less than 0.3. The noble-metal chip is made of iridium or an alloy that contains iridium in an amount of 70% by weight or more, and crystal grains constituting the noble-metal chip 30, 90 extends in the axial direction. Also disclosed is a method for manufacturing the spark plug.

Abstract: [Problem]A production method is provided that can improve the reliability of a molten bond of a spark plug in which a small-diameter noble metal tip is laser welded while protruding from a side face of a ground electrode. [Means for Resolution] A discharge portion 52 which forms a discharge gap 6 between the portion and a tip end face 51 of a center electrode 3 is configured by: forming a taper 4b in a ground electrode 4, the width of the taper being smaller as advancing toward the tip end so as to attain a diameter of 0.8 mm or less and a height of 0.5 mm or more; and then bonding the portion by laser welding to a side face 4a of the ground electrode 4.

Abstract: A spark plug including an insulator having an axial hole in an axial direction; and a center electrode disposed in a tip end side of the axial hole of the insulator so as to project a tip end of the center electrode from the tip end side of the insulator. The center electrode includes an electrode base member made of pure Ni or an Ni alloy containing 85 wt % or more of Ni; and a noble metal chip fixed to a tip end of the electrode base. The spark plug further includes a metal shell surrounding the insulator; and a ground electrode in which one end is joined to the metal shell, and another end portion opposes the noble metal chip to form a spark discharge gap between the ground electrode and noble metal chip, wherein M, D1, and D2 as defined herein satisfy M?10.1 mm, 0.5 mm?D2<1.4 mm, and D1/D2?3.5.

Abstract: The object of the present invention is to provide a spark plug having a discharge portion formed of a noble-metal chip increased in the Ir content while reducing the content of expensive Rh, which can be restrained from generation of unusual wear in the form of eroding the circumferential side surface of the noble-metal chip and exhibits excellent wear resistance. In the present invention, the discharge portion (31) in the center electrode (3) side is formed of a noble-metal chip (31?) comprising an Ir-based alloy and the noble-metal chip (31?) contains 90% by weight or more of Ir as the main component and further contains 0.5% by weight or more of Rh and from 0.5 to 8% by weight of Ni, whereby the noble-metal chip (31?) [discharge portion (31)] can be ensured with good wear resistance, the generation of unusual wear which readily occurs on decreasing the Rh content can be prevented by the addition of Ni and in turn, a spark plug having high performance can be fabricated at a low cost.

Abstract: In a spark plug for an internal combustion engine oil is applied onto at least either the surface of an intermediate body portion of an insulator or the surface of an intermediate hole portion of a metallic shell, thereby forming an oil film. Since the oil film has a dielectric constant falling between those of the insulator and an ambient air layer, a great change in dielectric constant between the insulator and the ambient air layer is eased. Also, since the oil film is of liquid, the oil film smoothes a dent or protrusion or a fine defect such as crack present on the surface of the intermediate body portion of the insulator. Thus, electric field concentration is suppressed, thereby preventing dielectric breakdown caused by such a dent, protrusion or fine defect.

Abstract: The invention relates to a process for treating a chromate waste liquid containing an organic acid component. This process includes (a) adding a chromium precipitation accelerating agent containing at least one of a calcium component and a magnesium component, to the chromate waste liquid; and (b) adjusting the chromate waste liquid to having a first pH of 9 or higher, thereby precipitating a chromium component from the chromate waste liquid and thereby reducing a concentration of a dissolved chromium component of the chromate waste liquid.

Abstract: A chromate film-containing plug metal component which is a metal component for a spark plug or a glow plug, wherein: the metal component has a surface, at least part of the surface being coated with a chromate film comprising at least 95% by weight of trivalent chrome based on 100% by weight of a total chrome content in the chromate film; and the chromate film comprises dye particles.

Abstract: In a wire drawing process for forming a wire rod containing iridium as a main component and which further contains nickel and at least one of platinum, rhodium and ruthenium, and having a cross-sectional area of not smaller than 0.05 mm2 and not larger than 1.2 mm2. The worked material is continuously heated red hot and/or white hot in a heating region 103 extending up to 60 mm from the work inserting surface 101a of a die 101 in a direction opposite that in which the work 102 moves, the work being heated to a temperature of 1000 to 1150° C. at a temperature measuring position 105 which is removed from the work inserting surface 101a by 20 mm. Furthermore, the temperature in the region 106 extending from the temperature measuring position 105 to the work inserting surface 101a is set to not lower than 1000° C., and the wire drawing rate is set to 300 to 1600 mm/min.

Abstract: In a glow plug and a spark plug, the surface of a main metal shell is coated with a chromate film in which the quantity of trivalent chrome is 95 wt % or more of the contained chrome components and which has a thickness of 0.2 &mgr;m to 0.5 &mgr;m.

Abstract: In a glow plug and a spark plug, the surface of a main metal shell is coated with a chromate film in which the quantity of trivalent chrome is 95 wt % or more of the contained chrome components and which has a thickness of 0.2 &mgr;m to 0.5 &mgr;m.

Abstract: In a spark plug, a complex chromate coat 42 that contains a chromium component and a phosphorus component as cationic components, at least 90 wt % of the chromium component being trivalent chromium and the phosphorus component being present in an amount of 1 to 15 wt % as calculated for PO4, is formed on the surface of the galvanized main metal shell 1 of a spark plug. If a silicon component is substituted for the phosphorus component, it may be present in an amount of 5 to 75 wt % as calculated for SiO2.

Abstract: A spark plug for use in an internal combustion engine includes a tubular insulator having an axial hole extending therethrough; a center electrode fitted into the axial hole and having a distal end portion protruding from a distal end of the insulator; and a ground electrode arranged such that at least a portion of spark discharge generated between the ground electrode and the distal end portion of the center electrode includes creeping discharge along the surface of the distal end portion of the insulator. The distal end portion of the center electrode contains Ni as a primary component in an amount of 80 wt % or more and Fe and Cr as secondary components in a total amount of 2.5 wt % to 10.0 wt % and further contains Al as a secondary component in an amount of 0.2 wt % to 0.8 wt %.

Abstract: A spark plug having a center electrode 2 formed from an electrode base material 2n, which is made of an Ni alloy containing an alloy component (e.g., Cr) capable of forming an oxide semiconductor having a resistivity of negative temperature coefficient. Thus, a corrosion suppression layer originating from the components of the electrode base material is formed on the surface of a tip end portion of the insulator 3, so that corrosion (channeling) of the surface of the tip end portion of the insulator 3 due to creeping spark discharge can be effectively suppressed. In addition, when the constituent metal of the electrode base material 2n has a coefficient of thermal conductivity of 17 to 30 W/m·K, the heat transfer performance of the electrode is enhanced, so that durability against electrode consumption can be greatly improved.

Abstract: A spark plug of the present invention is made of an Ir alloy including a specific amount of (1) Rh, (2) Pt, or (3) Rh and Pt or Rh and Ru. The spark plug comprises tips for a center electrode and for a ground electrode that are each 0.6 to 1.8 mm in diameter and 0.2 to 0.7 mm in thickness and for an interlayer made of an Ir alloy including Ni of 40 mass % that has a diameter slightly larger or smaller than that of each tip for the center electrode and for the ground electrode and has a thickness of 0.1 to 0.6 mm. These tips can be manufactured according to the powder processing method, the dissolution method, and so on. The tip for the center electrode is joined to the end surface of the basic body of the center electrode, which is made of a Ni alloy (Inconel 600), according to laser welding. The tip for the interlayer and the tip for the ground electrode are brought into contact with a predetermined position of the ground electrode, and are joined while being pressed according to electric resistance welding.

Abstract: The object of the present invention is to provide a spark plug having a discharge portion formed of a noble-metal chip increased in the Ir content while reducing the content of expensive Rh, which can be restrained from generation of unusual wear in the form of eroding the circumferential side surface of the noble-metal chip and exhibits excellent wear resistance.

Abstract: A method for manufacturing a spark plug, the spark plug includes: a cylindrical metal shell having a portion to be caulked and a tool-engaging portion that is to be attached on an engine; an insulator that is inserted into the metal shell and extends axially; and a caulking metallic mold, the method including caulking the portion to be caulked to be fixed to an outer circumferential face of the insulator with the caulking metallic mold, where in the caulking metallic mold includes a face, the face including a hard carbon film that includes an amorphous carbon phase, and the face is contact with or sliding to the portion to be caulked.

Abstract: A spark plug having a discharge portion formed of a noble-metal chip, the spark plug being capable of restraining wear observed on a slenderized discharge portion in particular. Discharge portion (31) includes noble-metal chip (31′). Dimension D is 0.3-0.8 mm; and H is 0.4-2 mm, where D (mm) is a diameter representing the outside diameter of the noble-metal chip, and H (mm) is a discharge portion thickness representing the shortest distance between the periphery of a discharge face (31t) and a corresponding end edge of a weld zone W where a center electrode (3) and the noble-metal chip (31′) are welded. Further, the noble-metal chip (31′) contains a predominant amount of Ir and 0.5-8% by weight Ni.

Abstract: A chromate film-containing plug metal component which is a metal component for a spark plug or a glow plug, wherein: the metal component has a surface, at least part of the surface being coated with a chromate film comprising at least 95% by weight of trivalent chrome based on 100% by weight of a total chrome content in the chromate film; and the chromate film comprises dye particles.

Abstract: A spark plug including a center electrode which extends in the axial direction and is composed of a body and an electrode whose root end is joined to the end face of the body. The distance between a joined portion of the body and the electrode tip and the face of a free end of the electrode tip is at least 0.15 mm, particularly at least 0.2 mm. A diametral dimension of the electrode tip measured at a position located at the interface between the electrode tip and the joined portion and nearest to the free end of the electrode tip is at least 0.2 mm, particularly at least 0.25 mm, greater than a diametral dimension of the electrode tip measured at the free end. The spark plug suppresses lateral consumption of the electrode tip arising in the vicinity of a joined portion formed through welding.