Method of nitriding metal ring and apparatus therefor

A technology of nitriding treatment and metal ring, applied in metal material coating process, V-belt, coating and other directions, can solve problems such as difficulty in maintaining high toughness
CN1685075AInactive Publication Date: 2005-10-19HONDA MOTOR CO LTD
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
HONDA MOTOR CO LTD
Publication Date
2005-10-19
Estimated Expiration
Not applicable · inactive patent

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Abstract

A metal ring made of maraging steel is heated in the presence of a halogen compound gas, so as to eliminate an oxide film from the surface of the metal ring and to form a halogenous compound film. Thereafter, the metal ring is heated under a vacuum or reduced pressure atmosphere to eliminate the halogenous compound film, and then it is maintained under an atmosphere comprising ammonia at a processing temperature ranging between 450 DEG C and 500 DEG C for a processing time ranging between 30 and 120 minutes, so as to carry out a nitriding processing. The above nitriding processing comprises the steps of: placing the above metal ring into a heating furnace and raising the temperature inside the heating furnace to the above processing temperature; introducing a first mixed gas consisting of 50% to 90% ammonia by volume, 0.1% to 0.9% oxygen by volume, and a residual volume consisting of nitrogen into the heating furnace, and maintaining the above processing temperature, so as to form a nitrided layer on the surface of the metal ring; and when the one-third to one-half of the processing time has passed, replacing the atmosphere inside the heating furnace by a second mixed gas consisting of 0% to 25% ammonia by volume and a residual volume consisting of nitrogen, and maintaining the above processing temperature until the remaining processing time passes.
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Description

technical field

[0001] The present invention relates to a nitriding treatment method and device for a metal ring made of maraging steel used in a continuously variable transmission belt or the like. Background technique

[0002] As is well known, conventionally, a CVT drive belt used for power transmission of a continuously variable transmission (CVT) of an automobile or the like is formed by laminating a plurality of metal rings to form a laminated ring, and assembling the laminated rings into a predetermined formed element. Hold.

[0003] The metal ring forming the laminated ring is made of low carbon steel containing Ni and Mo, such as maraging steel. The metal ring is formed by, for example, cutting a thin plate of low carbon steel into a rectangle, rolling the thin plate along the long sides, and welding the ends of the short sides to form a cylindrical tank body, and then Then, the can body is cut into endless rings according to the specified width to manufacture. T...

Claims

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