Direct-current electrical heat-treatment of continuous metal sheets in a protective atmosphere
US4081296A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 3, 1975 |
| Grant date | Mar 28, 1978 |
| Priority date | — |
| Expiry date | Jul 3, 1995 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC21D9/62
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
The heat treatment of a continuous band or sheet of metal as the same travels through a plurality of stages in a protective atmosphere, between conveying rollers, by applying direct-current electricity to the rollers for inclusion of the travelling sheet in the circuit therebetween. The charged rollers in the initial stage are spaced more widely from one another than those in the later stage, to compensate for the lower resistivity of the metal in the former, so that the Joule effect of I.sup.2 R factor in the stages are substantially equalized. The protective atmosphere of oxidizing, reducing or inert gases which encompasses the sheet, is confined in chambers of galvanized iron sheeting and the like, the walls of which are in close proximity to the travelling sheet, so that lesser amounts of reacting gases are necessary. Furthermore, no inductive electric currents are generated in the walls of the chambers, as is the case when alternating currents are applied to the conveying rollers, with the consequent heat loss. The lack of any extraneous source of heat within the chamber through which the metal sheet passes, other than the direct-current energy, results in a system of low ther…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.