Abstract: A grinding wheel including: (a) an annular core body which includes a multiplicity of aggregate particles and a resin bond that holds said aggregate particles together; (b) an abrasive layer which is disposed radially outwardly of said annular core body and which includes a multiplicity of abrasive grains and a vitrified bond that holds said abrasive grains together; and (c) an impermeable coating which is formed of a synthetic resin, and which is disposed on said annular core body.

Abstract: A coated steel sheet composed of a steel sheet and at least two types of coating layers formed thereon is provided with an electrodeposition painting having a superior appearance. The coated steel sheet has an arithmetic mean roughness Ra, which is defined by JIS B 0601-1994, of from about 0.7 to about 1.5 ?m and a peak per inch PPI of from about 180 to about 250.

Abstract: A method of manufacturing a grinding wheel which includes a cylindrical core body and a plurality of part-cylindrical abrasive segment chips bonded to an outer circumferential surface of the cylindrical core body. The method includes: a firing step of firing an unfired part-cylindrical precursor to prepare each part-cylindrical abrasive segment chips, by using a supporting member whose coefficient of thermal expansion is different from that of each abrasive segment chip; and a bonding step of bonding the abrasive segment chips to the outer circumferential surface of the cylindrical core body with an adhesive interposed therebetween, by forcing each abrasive segment chip against the outer circumferential surface of the cylindrical core body, such that a force acting on the outer circumferential surface of the cylindrical core body is evenly distributed in an axial direction of the cylindrical core body while the adhesive is being hardened.

Abstract: A grinding wheel including (a) a cylindrical main body having a grinding surface on its outer circumferential surface, and (b) a pair of synthetic resin layers disposed on respective axially opposite end faces of the cylindrical main body. Each of the synthetic resin layers covers at least a radially outer end portion of a corresponding one of the axially opposite end faces. The cylindrical main body has an abrasive layer which constitutes a radially outermost layer thereof so that the abrasive layer provides the grinding surface.

Abstract: A method of manufacturing a grinding wheel which includes a cylindrical core body and a plurality of part-cylindrical abrasive segment chips bonded to an outer circumferential surface of the cylindrical core body. The method includes: a firing step of firing an unfired part-cylindrical precursor to prepare each part-cylindrical abrasive segment chips, by using a supporting member whose coefficient of thermal expansion is different from that of each abrasive segment chip; and a bonding step of bonding the abrasive segment chips to the outer circumferential surface of the cylindrical core body with an adhesive interposed therebetween, by forcing each abrasive segment chip against the outer circumferential surface of the cylindrical core body, such that a force acting on the outer circumferential surface of the cylindrical core body is evenly distributed in an axial direction of the cylindrical core body while the adhesive is being hardened.

Abstract: A grinding wheel including: (a) an annular core body which includes a multiplicity of aggregate particles and a resin bond that holds said aggregate particles together; (b) an abrasive layer which is disposed radially outwardly of said annular core body and which includes a multiplicity of abrasive grains and a vitrified bond that holds said abrasive grains together; and (c) an impermeable coating which is formed of a synthetic resin, and which is disposed on said annular core body.

Abstract: A coated steel sheet composed of a steel sheet and at least two types of coating layers formed thereon is provided with an electrodeposition painting having a superior appearance. The coated steel sheet has an arithmetic mean roughness Ra, which is defined by JIS B 0601-1994, of from about 0.7 to about 1.5 &mgr;m and a peak per inch PPI of from about 180 to about 250.

Abstract: A grinding wheel which is to be rotated about its axis for grinding a workpiece, including: (a) a base disk; and (b) a plurality of abrasive segment chips which are fixed to the base disk such that the abrasive segment chips are arranged on a circle having a center at an axis of the base disk, and which have respective circumferential lengths as measured in a circumferential direction of the base circle, wherein the plurality of abrasive segment chips includes at least two abrasive segment chips having the respective circumferential lengths which are different from each other, and wherein the abrasive segment chips are arranged with substantially no gap between each pair of the abrasive segment chips which are contiguous to each other in the circumferential direction.

Abstract: A grinding wheel including (a) a cylindrical main body having a grinding surface on its outer circumferential surface, and (b) a pair of synthetic resin layers disposed on respective axially opposite end faces of the cylindrical main body. Each of the synthetic resin layers covers at least a radially outer end portion of a corresponding one of the axially opposite end faces. The cylindrical main body has an abrasive layer which constitutes a radially outermost layer thereof so that the abrasive layer provides the grinding surface.

Abstract: An ignition system has a spark plug and a positive voltage applying unit. The spark plug includes a central electrode, a porcelain insulator for holding the central electrode, a main metallic shell for holding the porcelain insulator, and a ground electrode electrically connected to the main metallic shell. The positive voltage applying unit applies a positive voltage to the central electrode of the spark plug in comparison with the ground electrode, so that an ignition high voltage is applied between the central electrode and the ground electrode. In the spark plug, a spark discharge gap is formed between the ground electrode and a distal end portion of the central electrode. The ground electrode is positioned so that a rear edge of a mating face opposed to a peripheral side of the central electrode is positioned in the side of the distal end of the central electrode in comparison with an end face of the porcelain insulator.

Abstract: A method of bonding an abrasive solid mass to a desired member with an adhesive, wherein the abrasive solid mass has a porous abrasive structure in which a multiplicity of abrasive grains are held together by a bonding agent. The method includes a sealing-film forming step of forming a sealing film on a surface of the abrasive solid mass, for preventing the adhesive from penetrating into pores formed in the porous abrasive structure.

Abstract: An ignition system has a spark plug and a positive voltage applying unit. The spark plug includes a central electrode, a porcelain insulator for holding the central electrode, a main metallic shell for holding the porcelain insulator, and a ground electrode electrically connected to the main metallic shell. The positive voltage applying unit applies a positive voltage to the central electrode of the spark plug in comparison with the ground electrode, so that an ignition high voltage is applied between the central electrode and the ground electrode. In the spark plug, a spark discharge gap is formed between the ground electrode and a distal end portion of the central electrode. The ground electrode is positioned so that a rear edge of a mating face opposed to a peripheral side of the central electrode is positioned in the side of the distal end of the central electrode in comparison with an end face of the porcelain insulator.

Abstract: A grinding wheel which is to be rotated about its axis for grinding a workpiece, including: (a) a base disk; and (b) a plurality of abrasive segment chips which are fixed to the base disk such that the abrasive segment chips are arranged on a circle having a center at an axis of the base disk, and which have respective circumferential lengths as measured in a circumferential direction of the base circle, wherein the plurality of abrasive segment chips includes at least two abrasive segment chips having the respective circumferential lengths which are different from each other, and wherein the abrasive segment chips are arranged with substantially no gap between each pair of the abrasive segment chips which are contiguous to each other in the circumferential direction.

Abstract: In an internal combustion engine, an engine control device 40 judges based on a cooling water temperature of an engine in what state the engine is. When judged that the engine is in a cold state, the engine control device 40 produces an ignition signal to feed it to an igniter 6b so as to spark spark plugs 7 which are individually placed in cylinders at an exhaust stroke or expansion stroke.

Abstract: A spark plug for an internal combustion engine is constituted by an insulating member (20) having an axial hole (26) formed along a central shaft (18); a rod-shape central electrode (12) accommodated in the axial hole; and a ground electrode (16) with which an igniting portion (16a) opposite to the outer surface (12a) of the central electrode is formed. In the spark plug, application of voltage between the central electrode and the ground electrode such that the polarity of the central electrode is made to be positive causes discharge to occur between the central electrode and the ground electrode. The spark plug satisfies at least one of the following conditions (a) and (b).

Abstract: In a semi-creeping discharge type spark plug, a cylindrical metal shell and an insulator are provided, the latter of which has an axial bore and placed within the metal shell so that a front end of the insulator extends beyond the metal shell. A center electrode is placed within the axial bore of the insulator so that a front end surface edge of the center electrode retracts by 0.1˜0.6 mm behind from a front end surface of the insulator. A ground electrode, one end of which is connected to a front end of the metal shell, and the other end of which is bent to oppose an outer surface of the insulator so as to form an air-gap therebetween while permitting creeping spark discharges running along said front end surface of said insulator. A foward edge portion of a front end surface of the ground electrode extends by 0.0˜1.0 mm forward from the front end surface of the insulator.

Abstract: A spark plug having a center electrode, a ground electrode, and an insulator. The ground electrode has a firing surface formed in a tip end side, and the firing surface is opposed to a side face of the center electrode. The insulator covers the outside of the center electrode and is placed such that a tip end portion is between the side face of the center electrode and the firing surface of the ground electrode. A discharge high voltage is applied across the center electrode and the ground electrode such that a polarity of the center electrode is positive and that of the ground electrode is negative. The high voltage causes a spark discharge to be generated between the firing surface of the ground electrode and a tip end portion of the center electrode.

Abstract: In a spark plug, a cylindrical metal shell (1) is provided whose inner wall has a rear section and a front section to respectively serve as a diameter-increased section and a diameter-decreased section with a seat portion (1) as a boundary therebetween. An insulator (2) is fixedly placed within the metal shell (1) so that a front end surface (21) of the insulator (2) extends beyond a front end surface (12) of the metal shell (1) with a shoulder portion (231) of an insulator nose (23) engaged against the seat portion (11) of the metal shell (1) by way of a packing (10). A center electrode (3) is fixedly placed within an axial bore (22) of the insulator (2), A ground electrode (4) is connected to the front end surface (12) of the metal shell (1), and bent so that a front end surface (41) of the ground electrode (4) opposes an outer surface (311) of the center electrode (3).

Abstract: A stepping motor having high-precision torque formation and stepping angle is able to be produced at a low cost. Cylindrical elastic magnetic members, which cover a first and second set of yokes and have an inner diameter smaller than the outer diameter of the yokes, readily come in tight contact with the yokes and form strong magnetic circuits. The first and second sets of yokes are integrally formed into a bobbin through a nonmagnetic member. Pole teeth of the first set of yokes and pole teeth of the second set of yokes are arranged by shifting at a given angle to each other in the peripheral direction.

Abstract: In a spark plug in use for an internal combustion engine, a ground electrode is secured to a front end of the metal shell so that a front end surface of the ground electrode faces an elevational side of a front end of the center electrode to cause semi-creeping spark discharges therebetween along a front end surface of the insulator. A front end portion of the center electrode has an electrode base in the axial bore and an electrode front defined diametrically smaller than the electrode base by way of a diameter-variable portion. A diametrical difference between an initial point of the diameter-variable portion of the center electrode and the axial bore of the insulator is 1 mm or less, and the initial point of the diameter-variable portion is retracted by 0.0 mm-1.0 mm from the front end surface of the insulator.