Honda Giken Kogyo Kabushiki Kaisha

Honda Motor Co., Ltd.

Hitoshi Imai

Katsuyuki Nakajima

Hitoshi Karasawa

Hiroshi Takeda

Haruo Meguro

Masanobu Ishikawa

Tomomi KoSaka

Shohachi Nishiuchi

Shigeo Ohta

A metal ring with smaller stress concentration is manufactured, and the manufacture and maintenance of a rolling roller for transferring a mesh-shaped unevenness to the metal ring is facilitated. A mesh-like unevennessis formed to the surface of an inner circumference rolling roller. This unevennessis formed by rotating the inner circumference rolling rollerat a predetermined speed, and moving a grinderback and forth in the axial direction of the inner circumference rolling rollerwhile biasing the grinder toward the surface of the rollerwith predetermined force. The grain size of the grinder is between #270 and #1000. When the inner circumferential surface of the metal ringis rolled using the inner circumference rolling roller, a mesh-like unevennessis transferred onto the metal ring. Since the mesh-like unevennessis formed by transferring the unevennesshaving been formed by the grinder, the pitch of the unevenness is narrow and random, thus the laminated metal ringexerts good lubricity. Moreover, by subjecting the metal ringto solution treatment and nitriding treatment, a metal ringhaving high compressive residual stress and enhanced toughness is formed.

Method of manufacturing metal ring for endless metal belt

A laminated ring for use as a belt in transmitting power in a continuously variable transmission is produced by welding opposite ends of a sheet of maraging steel to produce a plurality of rings, and rolling said rings to a predetermined length. The rings are nitrided in a salt-bath nitriding process by dipping the rings in a molten salt containing 38-46% of CNO and 1-2% of CN and heated to a temperature in the range from 480 to 530&deg; C., for a period of time ranging from 10 to 25 minutes. The nitrided rings are finally stacked into a laminated ring.

Molten salt composition for use in manufacturing laminated rings

A cylindrical drum, which comprises a sheet of maraging steel with welded opposite ends, is severed into a plurality of rings of predetermined width, and the rings are rolled to a predetermined length, after which circumferential lengths of the rings are corrected. The rings are aged by placing the rings into an aging chamber, heating the aging chamber to a predetermined aging temperature, and keeping the rings at the predetermined aging temperature for a predetermined period of time. Thereafter, the rings are nitrided by transferring the rings from the aging chamber into a nitriding chamber which is disposed independently of the aging chamber and has been heated to a predetermined nitriding temperature, while maintaining the rings at the aging temperature, keeping the rings at the nitriding temperature in an atmosphere containing at least an ammonia gas for a predetermined period of time, and cooling the rings. The rings are fitted and stacked together into a laminated ring for use as a belt in transmitting power in a continuously variable transmission.

Method of manufacturing laminated ring and heat treatment apparatus for use in such method

A cylindrical drum is prepared by welding opposite ends of a thin sheet of maraging steel. A first solution treatment is effected on the cylindrical drum, and then the cylindrical drum is severed into a plurality of rings each having a predetermined width. After the rings are rolled, a second solution treatment is effected on the rings which have been rolled, and then the circumferential length of each of the rings is corrected. The rings are aged and nitrided, and then stacked into a laminated ring. The first solution treatment and the second solution treatment are effected using the same heating furnace in the same atmosphere in the same temperature range.

Method of manufacturing laminated ring

Method of manufacturing laminated ring using molten salt composition

A billet is successively cold worked into a product such as a countershaft, an outer race for a constant-velocity joint, or the like by forming a chemically converted lubricating coating on a surface of the billet, forging the billet into an intermediate product at a temperature below a transformation temperature of the billet, covering a surface of said intermediate product with lubricating oil in a die cavity in a die assembly, and forging the intermdiate product at a temperature below the transformation temperature and before the intermediate product gains a predetermined hardness due to age hardening resulting from the first forging step.

Growing community of inventors

Sayama, Japan

Hitoshi Imai