Abstract: The present invention provides a sound-absorbing material having sound absorption performance with an average sound absorption coefficient of 0.70 or more in the frequency range of 800 to 5000 Hz. The present invention provides a sound-absorbing material including: a fiber layer including a plurality of holes open to a surface thereof and having a thickness of 3 mm or more; and an inorganic material layer mainly containing a calcium-based material and having a thickness of 0.4 to 0.6 mm on the surface of the fiber layer, the holes being blind holes each penetrating through the inorganic material layer and having a bottom inside the fiber layer, each hole having a depth corresponding to 50 to 90% of the thickness of the fiber layer.

Abstract: Spark plug has first and second electrodes. First electrode has tip principally made of noble metal and base material principally made of Ni. The tip is joined to the base material through fusion portion. Second electrode faces discharge surface of the tip. The fusion portion has overlap portion where first interface between the tip and the fusion portion and second interface between the base material and the fusion portion overlap in first direction perpendicular to the discharge surface. When viewing cross section which passes through a center of gravity of the overlap portion projected onto virtual surface parallel to the discharge surface and is perpendicular to the discharge surface, noble metal content is greater than 50 mass % at one end portion of the overlap portion in second direction extending along the discharge surface, and Ni content is greater than 50 mass % at the other end portion of the overlap portion.

Abstract: Spark plug has first and second electrodes. First electrode has tip principally made of noble metal and base material principally made of Ni. The tip is joined to the base material through fusion portion. Second electrode faces discharge surface of the tip. The fusion portion has overlap portion where first interface between the tip and the fusion portion and second interface between the base material and the fusion portion overlap in first direction perpendicular to the discharge surface. When viewing cross section which passes through a center of gravity of the overlap portion projected onto virtual surface parallel to the discharge surface and is perpendicular to the discharge surface, noble metal content is greater than 50 mass % at one end portion of the overlap portion in second direction extending along the discharge surface, and Ni content is greater than 50 mass % at the other end portion of the overlap portion.

Abstract: An ignition plug includes an insulator having an outer-diameter reduction surface and a metal shell. The metal shell includes a rear end portion, a curved deformation portion, and a stepped portion. In a section including an axial line, the average hardness of a surface layer portion, which extends along a specific surface, of a rear end surface of the stepped portion is higher than the average hardness of the rear end portion and the average hardness of the deformation portion.

Abstract: An ignition plug includes an insulator having an outer-diameter reduction surface and a metal shell. The metal shell includes a rear end portion, a curved deformation portion, and a stepped portion. In a section including an axial line, the average hardness of a surface layer portion, which extends along a specific surface, of a rear end surface of the stepped portion is higher than the average hardness of the rear end portion and the average hardness of the deformation portion.

Abstract: A center electrode including an electrode base member having a cylindrical shape with a bottom and a core member embedded in the electrode base member. The core member has a thermal conductivity higher than that of the electrode base member. The center electrode includes a plurality of shoulder portions which each include a diameter reducing portion having a diameter that decreases toward a front end of the spark plug in a direction of an axial line, an outer side surface that extends in the direction of the axial line, and an edge disposed between the diameter reducing portion and the outer side surface. One of the shoulder portions closest to an inner surface of the axial hole has a cutting mark that extends in a circumferential direction over a region from the diameter reducing portion to the edge.

Abstract: A center electrode including an electrode base member having a cylindrical shape with a bottom and a core member embedded in the electrode base member. The core member has a thermal conductivity higher than that of the electrode base member. The center electrode includes a plurality of shoulder portions which each include a diameter reducing portion having a diameter that decreases toward a front end of the spark plug in a direction of an axial line, an outer side surface that extends in the direction of the axial line, and an edge disposed between the diameter reducing portion and the outer side surface, One of the shoulder portions closest to an inner surface of the axial hole has a cutting mark that extends in a circumferential direction over a region from the diameter reducing portion to the edge.

Abstract: In a metallic shell, cutting traces are formed on the inner circumferential surface of a trunk portion and the inner circumferential surface of an elongated leg portion. A first portion of a packing is in contact with and disposed between the rear end surface of a ledge portion of the metallic shell and the outer circumferential surface of a step portion of an insulator. A second portion of the packing is in contact with and disposed between the inner circumferential surface of a trunk portion of the metallic shell and the outer circumferential surface of a tubular portion of the insulator. A gap between the inner circumferential surface of the elongated leg portion and the outer circumferential surface of the leg portion is approximately uniform along the entire circumference.

Abstract: In a metallic shell, cutting traces are formed on the inner circumferential surface of a trunk portion and the inner circumferential surface of an elongated leg portion. A first portion of a packing is in contact with and disposed between the rear end surface of a ledge portion of the metallic shell and the outer circumferential surface of a step portion of an insulator. A second portion of the packing is in contact with and disposed between the inner circumferential surface of a trunk portion of the metallic shell and the outer circumferential surface of a tubular portion of the insulator. A gap between the inner circumferential surface of the elongated leg portion and the outer circumferential surface of the leg portion is approximately uniform along the entire circumference.

Abstract: A crimping-pressing step including (1) a step of bringing the crimping jig into contact with a to-be-crimped portion and moving the crimping jig forward such that a load acting on the crimping jig reaches a preset contact load, and (2) a buckling step of further moving the crimping jig forward by a preset distance and then stopping the crimping jig. The difference between the target moving distance of the crimping jig and its actual moving distance is reduced by adjusting at least one of the preset contact load and the preset distance on the basis of at least one of a first overshoot amount in the step (1) and a second overshoot amount in the step (2).

Abstract: A crimping-pressing step including (1) a step of bringing the crimping jig into contact with a to-be-crimped portion and moving the crimping jig forward such that a load acting on the crimping jig reaches a preset contact load, and (2) a buckling step of further moving the crimping jig forward by a preset distance and then stopping the crimping jig. The difference between the target moving distance of the crimping jig and its actual moving distance is reduced by adjusting at least one of the preset contact load and the preset distance on the basis of at least one of a first overshoot amount in the step (1) and a second overshoot amount in the step (2).

Abstract: A spark plug and a method of forming the same. The spark plug having a rod-shaped center electrode extending in an axial direction, a tubular insulator having an axial hole and holding the center electrode in the axial hole, a tubular metallic shell having an end surface, an inner circumferential surface, and a gap formed between the inner circumferential surface and a forward end portion of the insulator, and a ground electrode welded to the end surface. A method of manufacturing the spark plug includes a welding step of welding the ground electrode to the end surface; and a shaping step which is performed after the welding step so as to form the inner circumferential surface, through shaping, on the metallic shell having the ground electrode welded to the end surface thereof.

Abstract: A spark plug and a method of forming the same. The spark plug having a rod-shaped center electrode extending in an axial direction, a tubular insulator having an axial hole and holding the center electrode in the axial hole, a tubular metallic shell having an end surface, an inner circumferential surface, and a gap formed between the inner circumferential surface and a forward end portion of the insulator, and a ground electrode welded to the end surface. A method of manufacturing the spark plug includes a welding step of welding the ground electrode to the end surface; and a shaping step which is performed after the welding step so as to form the inner circumferential surface, through shaping, on the metallic shell having the ground electrode welded to the end surface thereof.