Mitsubishi Jidosha Kogyo Kabushiki Kaisha

Dowa Mining Co., Ltd.

Tokyo Heat Treating Company, Ltd.

Hitoshi Goi

Masahiko Watanabe

Fumitaka Abukawa

Fukitaka Abukawa

Yoshihiko Kitayama

Keishichi Nanba

Toshiyuki Kawamura

Hirofumi Kamisugi

Hiroshi Shimura

Kazuyoshi Fujita

Shin Kurasawa

Tadayoshi Juge

Yuichi Takasu

Nobuo Nishioka

Keishichi Namba

Yoshiaki Shimizu

Atsushi Murayama

In a method for quenching metal parts, a quenching chamber is provided in which the quenching oil is continuously supplied from below the steel parts and circulated upward through the parts in a laminar flow. The circulation is accomplished by feeding the quenching oil onto the bottom of the quenching chamber of an auxiliary chamber surrounding it.

Apparatus for steel hardening and process therefor

In a cementation method of metals in which hydrocarbon gas and oxidization gas are introduced into a heat treatment furnace, a small quantity of hydrocarbon gas of is introduced at a low pressure into the heat treatment furnace. The shift time and the gradient of the carbon potential varying toward a predetermined high or low level are controlled by increasing or decreasing the quantity of cementation gas and oxidization gas to be supplied to the furnace. After the carbon potential is reached to the high or low level, the carbon potential is maintained for a predetermined time period so as to prevent the deposited carbide from being bulked. In order to prevent the gas supply pipe from being choked with the soot of the hydrocarbon, oxidization gas of intermediate pressure is flushed into the gas supply pipe. In order to prevent the components of the atmosphere in the furnace from varying due to the change in furnace pressure when the door is opened or closed, hydrocarbon gas of a low pressure and oxidization gas of an intermediate pressure are added in the conversion pipe in the preheating zone. CO.sub.2 of intermediate pressure is supplied into each gas supply pipe at the same time in order to remove the soot in each of the gas supply pipes and to prevent the lack of CO to be introduced into the furnace.

Cementation method of metals

A treating material W pre-heated to a carburizing temperature of 750.degree.-950.degree. C. is heat-treated in a carburizing atmosphere directly supplied with hydrocarbon and oxidizing gases and heated to 1000.degree.-1100.degree. C. Then, the treating material W is forcibly cooled to a temperature below 600.degree. C., the treating material W is re-heated to 750.degree.-850.degree. C., and then it is hardened. Energy required to the carburization can be saved because drastic reduction of the treating time is possible.

Gas carburizing process and an apparatus therefor

A gas-carburizing process wherein an article is treated by feeding a hydrocarbon gas and an oxidative gas of raw material gases directly into an atmospheric heat treating furnace, characterized in that, when the pressure within the furnace is negative, CO.sub.2 is fed as a negative pressure dissolving means. A gas-carburizing apparatus wherein a gas inlet for feeding a hydrocarbon gas and an oxidative gas provided in the ceiling part of an atmospheric heat treating furnace is provided with a CO.sub.2 feeding part for dissolving the negative pressure within the furnace.

Gas-carburizing process and apparatus

A gas-carburizing process wherein an article is treated by feeding a hydrocarbon gas and an oxidative gas of raw material gases directly into an atmospheric heat treating furnace, characterized in that, when the pressure within the furnace is negative, CO.sub.2 is fed as a negative pressure dissolving or eliminating means. A gas-carburizing apparatus wherein a gas inlet for feeding a hydrocarbon gas and an oxidative gas provided in the ceiling part of an atmospheric heat treating furnace is provided with a CO.sub.2 feeding part for eliminating the negative pressure within the furnace.

Gas carburizing method and apparatus

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Yokohama, Japan

Hitoshi Goi