Mazda Motor Corporation

Ndk Corporation

Yoshihisa Miwa

Nobuo Sakate

Kyoso Ishida

Nobuyuki Oda

Katsunori Hanakawa

Shinji Kadoshima

Yoshio Tanita

Yukio Arimi

Yoshihiko Kojima

Shinya Shibata

Katunori Hanakawa

Kiyomi Yasuura

Disclosed is a heat-insulating structure which can be used, for example, to reduce the cooling loss of an engine. The heat-insulating structure includes a hollow particle layer made of a lot of hollow particles densely packed on a surface of a metallic base material. The hollow particle layer is covered with a coating.

Heat-insulating structure

The tooth portion of a metal ring gear is subjected to shot peening after the ring gear is mechanically connected to a metal boss portion by plastic deformation of the metal material.

Method of connecting metal ring gear to metal boss portion

In subjecting a steel workpiece to nitriding by glow discharge, formation of brittle nitrogen compound is restrained and the surface hardened layer with a nitrogen diffusion layer of high toughness is obtained by making the gas atmospheric condition the gas mixing ratio of N.sub.2 :H.sub.2 =1:2-40. By mixing Ar gas in the above gas atmospheric condition additionally, glow width is adjusted and glow discharge is allowed to enter into narrow concaves at the surface of a workpiece.

Method of ion nitriding steel workpieces

In an apparatus accommodating a rotor of light alloy and a rotor shaft of steel secured to each other, the rotor shaft consists of a first shaft and a pair of second shafts integrally formed with or rigidly secured to the first shaft. The first shaft has a structure with a thermal coefficient of expansion close to that of the rotor whereas each of the second shafts has a structure with a thermal coefficient of expansion less than that of the first shaft.

Structure of a rotor shaft and method of making same

A method for manufacturing a steel member which comprises the steps of preparing a steel material of a composition containing C in a quantity of 0.15 to 0.35 wt %, Si in a quantity of not greater than 0.50 wt %, Mo in a quantity of 0.05 to 0.50 wt %, Mn in a quantity of 0.50 to 1.30 wt %, Cr in a quantity of 0.50 to 1.30 wt %, V in a quantity of 0.05 to 0.20 wt %, N in a quantity not greater than 0.02 wt %, Al in a quantity of not greater than 0.10 wt % and Fe being the balance relative to the total weight of the steel material, wherein the product of the sum of the Mn content and the Cr content times the Mo content is chosen to be within the range of 0.1 to 0.6, hot-forging the steel material at a predetermined heating temperature to provide the steel member, and continuously cooling the steel member at a predetermined cooling speed of 0.4.degree. to 4.0.degree. C./sec to impart a substantially bainite structure or a combined bainite and ferrite structure to the steel member.

Method of making steel member

A method of carburizing and quenching involves the following three steps of: pre-carburizing a steel member containing Cr with precipitating carbide by heating to achieve a surface carbon concentration of not less than 1%; spheroidizing the carbide obtained by alternately holding the steel member at a temperature slightly above and slightly below the A.sub.1 transformation temperature under a carbon potential of from 0.5 to 1.0%; and carburizing and quenching or carbo-nitriding and quenching the steel member followed by reheating at not more than the heating temperature of pre-carburizing.

Method of carburizing spheroidizing and quenching

A method for manufacturing a novel gear fit article that includes metal plating the surface of an annular steel work is disclosed. The plating is made of copper to prevent nitriding of the underlying steel. The plated steel work is gear cut to form internal teeth of exposed steel. The annular gear is nitrided to harden the teeth and, in the process, softens the metal plating. Thereafter, the annular gear is shrinkage fitted into a rotor body to form the novel gear fit article.

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Hiroshima, Japan

Yoshihisa Miwa