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

PROBLEM TO BE SOLVED: To provide a heat treatment device of a continuously variable transmission for suppressing the deformation generated in a metal ring during the suspension and during the heat treatment. SOLUTION: A metal ring 1 is subjected to the tension by a first part 10 and a second part 11 via abutting parts 12a, 12b abutted on the substantially circular metal ring 1 from the inner circumferential side and deformed in an oblong shape to hold the metal ring 1. The metal ring 1 held by the first part 10 and the second part 11 is horizontally conveyed inside a suspension tool 3, and horizontally suspended to the suspension tool 3. COPYRIGHT: (C)2009,JPO&INPIT

Heat treatment device of belt ring of continuously variable transmission

PROBLEM TO BE SOLVED: To eliminate the need for barreling and work the side end face of a ring-like metal belt M into a prescribed cross-sectional shape by means of a plastic deforming or grinding. SOLUTION: A ring-like metal belt M wound between a tension roll 1 and a return roll 2 is circulated with tension exerted thereon. A pair of or plural pairs of end face working rolls 4R, 4L, that are provided along the circulating orbit of the ring-like metal belt M on both sides, are pushed against the both ends in the width direction of the ring-like metal belt M. The both ends in the width direction of the ring-like metal belt M is worked into a prescribed shape by means of plastic deforming or grinding. When using the end face working rolls 4R, 4L wherein abrasive papers being stuck to a recessed groove 5 or abrasive particles being fixed in the recessed groove 5, the end face of the belt having a prescribed sectional shape is formed by means of grinding.

Method of manufacturing metal belt for continuously variable transmission

PROBLEM TO BE SOLVED: To provide a treatment method where an endless metal belt made of malaging steel as the material is subjected to oxidation treatment, and is thereafter subjected to nitriding treatment with a molten salt composition capable of nitriding treatment at a salt bath nitriding treatment temperature of <480°C and also comprising cyanogen as anionic contents, thus a uniform nitriding layer can be formed without forming a compound layer damaging its durability. SOLUTION: The surface hardening treatment method for malaging steel comprises a process wherein pretreatment in which an oxide layer is formed on the surface of malaging steel is performed, and thereafter, nitriding treatment is performed in a salt bath comprising, as anion contents, by mass, 3 to 20% cyanogen and 30 to 50% cyanic acid, and at least comprising carbonic acid as the residue of the anionic contents, and at least comprising sodium or potassium as cationic contents as well. COPYRIGHT: (C)2006,JPO&NCIPI

Surface hardening treatment method for malaging steel

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° 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

(57) [Summary] [PROBLEMS] To provide a manufacturing technique in which a processing time is short, and good abrasion and durability are obtained. SOLUTION: A solution nitrided and cold worked maraging steel is heated and held in a salt bath at 520 to 530 ° C for 10 to 25 minutes, whereby a desired nitrided layer depth can be obtained on the surface. [Effect] Since the salt bath nitriding process time is 10 to 25 minutes, the required time is 1/10 to 1/20 as compared with the nitriding time of 4 to 6 hours by the conventional gas soft nitriding method, Productivity can be greatly increased.

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Papers

Production of endless metallic ring

▲良▼史 仁部

Papers

Production of endless metallic ring

▲良▼史仁部