Abstract: A method of manufacturing a shadow mask of the nickel-iron type, in which an aperture-patterned sheet of a nickel-iron alloy comprising 35-37% by weight of Ni and less than 0.1% by weight of each constituent of the group of Mn, Cr and Si and at most 0.9% by weight of Co is given a thermal treatment for obtaining an ASTM grain number of .gtoreq.7, and the sheet thus obtained is given the desired shape of a shadow mask having a thermal expansion coefficient of .ltoreq.0.9.times.10.sup.-6 /.degree.C.

Abstract: A method of manufacturing a shadow mask of the nickel-iron type, in which an aperture-patterned sheet of a nickel-iron alloy comprising 35-37% by weight of Ni and less than 0.1% by weight of each constituent of the group of Mn, Cr and Si and at most 0.9% by weight of Co is given a thermal treatment for obtaining an ASTM grain number of .gtoreq.7, and the sheet thus obtained is given the desired shape of a shadow mask having a thermal expansion coefficient of .ltoreq.0.9.times.10.sup.-6 /.degree.C.

Abstract: A shadow mask sheet manufactured from an iron-nickel alloy is drape-drawn by means of a drawing process to form a shodow mask 15. Prior to the actual drawing process the shadow mask sheet is subjected to an annealing treatment. After the drawing process the shadow mask is successively subjected to a complementary annealing treatment in a non-oxidizing gas atmosphere at a temperature between 700.degree. C. and 1200.degree. C. to improve the magnetic screening properties of the shadow mask 15, and to an annealing treatment in an oxidizing gas atmosphere. After oxidation the shadow mask 15 is connected on a supporting frame 17 which may be subjected to an annealing treatment in a non-oxidizing gas atmosphere and then to an oxidizing annealing treatment.

Abstract: Device to drape draw a nickel-iron alloy, etched-aperture sheet, including means to heat the sheet at a temperature between 150.degree. and 250.degree. C. during drawing, whereby a 0.2% proof stress of the shadow mask material is reached below a tensile stress of 150.sup.N /nm.sup.2. Accurate reproduction of shadow masks is thereby achieved with minimized detrition of the tooling.

Abstract: Prior drape to drawing a nickel-iron alloy, etched-aperture sheet, it is subjected to an annealing treatment between 700.degree. and 820.degree. C. so as to produce complete recrystallization without grain growth of any significance. During the drawing process the sheet is maintained at a temperature between 150.degree. and 250.degree. C., a 0.2% proof stress of the shadow mask material between 150.degree. and 250.degree. C. being reached below a tensile stress of 150 .sup.N /mm.sup.2. Accurate reproduction of shadow masks is achieved with minimized detrition of the tooling.

Abstract: Method of manufacturing a deep drawn CRT mask in which the mask blanks are cut from the steel foil, each mask blank having a pattern of apertures. To facilitate the subsequent deep drawing and in order to obtain a grain size for good magnetic screening by the shadow mask an annealing process is carried out. An optimum grain size of the mask material between 0.015 and 0.040 mm with an average grain size between 0.020 and 0.030 mm is obtained by annealing at a temperature from 600.degree. C. to 850.degree. C. which lies above the temperature at which the mask blanks may adhere together by thermomolecular welding. In order to prevent rejects as a result of said welding, a stack of mask blanks is laid on a curved substrate prior to annealing (FIGS. 3f, 3g), which substrate preferably has the form of a part of a cylinder the radius of which is equal to the radius of the mask after deep drawing. After annealing in a furnace (FIG. 3h) the mask blanks are placed on a flat substratum (FIGS.