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US 4,536,226 AGranted
Method of manufacturing a shadow mask for a color cathode ray tube
AssigneeKabushiki Kaisha Toshiba
InventorsYasuhisa Ohtake, Hiroshi Tanaka, Koichiro Oka
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Abstract
A method of manufacturing a shadow mask includes the steps of perforating a number of apertures in a sheet of iron-nickel alloy, annealing the sheet, and forming the sheet, after annealing, into a shadow mask by pressing while the sheet is kept at a predetermined forming temperature effective to reduce the yield strength of the alloy.
Claims11
A method of manufacturing a shadow mask from a sheet having a polycrystalline structure of an alloy comprising iron and nickel, the sheet having a yield strength, said method comprising the steps of:
- perforating the sheet;
- annealing the perforated sheet at a first predetermined temperature effective to reduce the yield strength, the first predetermined temperature being between a recrystallization temperature and a melting temperature of the alloy;
- and
- pressing the annealed sheet while maintaining the sheet at a second predetermined temperature effective to further reduce the yield strength, the second predetermined temperature being lower than the first predetermined temperature and being maintained during at least part of said step of pressing.
1 more element
Dependencies are inferred from the claim text.