Increased retention forces in steel interference FIT assemblies and methods to increase the retention forces
US5496646A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 2, 1993 |
| Grant date | Mar 5, 1996 |
| Priority date | — |
| Expiry date | Dec 2, 2013 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T403/70
- WIPO fieldSurface technology, coating
- WIPO sectorChemistry
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.