Method for producing by continuous heat treatments oil-tempered steel wires for springs having high strength and high toughness
CA 2065641 C · Owner: Sugita, Heiji · Inventors: Nitta, Yoshitaka; Sugita, Heiji; Toyama, Masao
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
Disclosed herein is a method for continuously hardening and tempering oil-tempered steel wires for springs having high strength and high toughness and which, meet a requirement for weight reduction. The method is applicable to medium-carbon low-alloy spring steel having a chemical composition which does not undergo martensitic transformation substantially upon oil hardening alone and thus has an Mf point lower than 80° C. The steel is one which contains carbon in amount of 0.40-0.65 weight % Si, Mn, and at least one species selected from the group consisting of Cr, Ni, Mo and V. The method comprises performing a two-step accelerated hardening consisting of subjecting the heated spring steel …
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Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.
Why it's free to use
- Filed April 9, 1992 and granted January 19, 1999. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended April 9, 2012.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by April 9, 2014.
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Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.