The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 05, 1996
Filed:
Dec. 02, 1993
Nelson A Bacigalupo, Ann Arbor, MI (US);
NTN Technical Center (U.S.A.), Inc., Ann Arbor, MI (US);
Abstract
Iron and steel interference fit assemblies with increased retention forces comprised of a purposely formed iron oxide layer of limited thickness on one or both of the mutually engaging surfaces. The new methods to create the new interference fit assemblies comprise heating of iron and steel parts intended for press fit assembly to temperatures substantially between 500.degree. F. (260.degree. C.) and 1050.degree. F. (566.degree. C.) for periods of time in air between ten hours and ten minutes to create an iron oxide surface layer of optimum thickness on at least one of the mutually engaging surfaces prior to assembly. Other methods to generate the optimum thickness of iron oxide layer may also be used. The iron oxide surface layer substantially increases the frictional retention force in the assembly. The retention force effectively doubles with heating at 700.degree. F. (371.degree. C.) to 800.degree. F. (427.degree. C.) for two hours with test results indicating these conditions to be optimal for increasing the frictional retention force. The result is iron and steel interference fit assemblies with substantially increased retention forces.