JPS6144126A - Manufacture of shadow mask - Google Patents

Abstract

PURPOSE:To manufacture a shadow mask having satisfactorily reduced yield strength by annealing a sheetlike metallic material contg. Fe and Ni as principal components in an atmosphere having a low dew point and a specified composition consisting of H2 and an inert gas and by cooling the annealed material at a properly controlled cooling rate. CONSTITUTION:The sheetlike metallic material contg. Fe and Ni as principal components is pierced by etching and annealed at >=1,000 deg.C for >=10min in an atmosphere consisting of >=75% H2 and the balance inert gas. At this time, the dew point of the atmosphere is kept at <=-20 deg.C. The annealed material is cooled to 300 deg.C at >=1 deg.C/sec cooling rate. Thus, the yield strength of the metallic material is reduced to <=about 20kg/mm.<2>, and a shadow mask having high press formability and capable of giving a color picture tube which causes no problem about colorimetric purity is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a shadow mask for a color picture tube using a material mainly containing iron and nickel.

Conventionally, low-carbon rimmed steel and ultra-low carbon A1-killed steel have been used as materials for color picture tube masks, but as a result of thermal expansion caused by local heating of the shadow mask by the 1M1 beam, the linearity of one color decreases. Therefore, it has been proposed to use an amber-based alloy, typically Fe-56N1, which has a small coefficient of thermal expansion. Roughly speaking, these materials for shadow masks with a plate thickness of α2 or less are degreased, applied with a resist film, phenomena, etched, perforated, and annealed.
Shadow masks are manufactured using a process called press molding, and when using an amber-based alloy for shadow masks.

The annealing softening properties are different from conventional ultra-low carbon A1-killed steel. In other words, a problem has arisen in that annealing before press molding does not sufficiently reduce the yield strength after annealing. This is because if the yield strength is large, the spherical formability during press molding is poor and local distortion occurs due to elasticity.

In order to obtain good spherical formability, it is desirable that K has a yield strength of 2 ob/xJ or less, and an annealing method that provides such properties has been strongly desired.

As a result of various studies, the present inventors have found that the current 7
51 or more, remaining inert gas, and the dew point is controlled at -20C or less in four atmospheres, annealed at a temperature of 1000℃ or more for 10 minutes or more, and 1℃/sec at 500℃.
We have developed a method for manufacturing a mask that is characterized by cooling at the above cooling rate.

Next, the reasons for limiting the manufacturing conditions in the present invention will be described.

Hl: When the Hta degree is less than 75-, the yield strength after annealing does not decrease even if the dew point is sufficiently lowered. Therefore, the H1 concentration in the atmosphere was set at 75% or more.

Dew point - When the dew point is higher than 120°C, the yield strength after annealing does not decrease even if annealing is performed with pure H2 and cooling is performed at a sufficiently fast cooling rate.

Temperature: 5 hours; Conditions of 1000° C. or more and 10 minutes or more are essential conditions for reducing the yield strength after annealing, and the yield strength does not decrease at a temperature lower than 1000° C. and an annealing time shorter than 10 minutes. Therefore.

The temperature was 1000°C or higher for 10 minutes or more.

Cooling rate: If the cooling rate to 300℃ is slower than 1℃/1dea, even if good annealing is performed, the surface layer and/or grain boundaries will be exposed to acid during cooling, resulting in sufficiently low yield strength. I can't get it. At temperatures below 1.300°C, the cooling rate has little effect. Therefore, the cooling rate up to 300℃ is 1
℃/θec or higher.

Examples Table 1 shows the components of the amber alloy used as examples.

Table 1 (% by weight) After annealing the amber alloy with the above composition under the conditions shown in Table 2,
(The 12% yield strength, grain size, C!, O, and H components were measured.

As shown in Table 2, a yield strength of 20 f/- or less can be obtained only by the annealing method of the present invention.

In addition, in the comparative method, the number of 0 increases after annealing, and the surface layer and grain boundaries are oxidized, which is thought to be inhibiting the growth of crystal grains.In one or more examples, only the amber alloy is explained. However, 5 this method is not limited to amber alloys (it can be applied to iron-Nisokel alloys of N1201 or higher, such as 421Ni 42 alloy and other permalloy alloys).Additionally, the above-mentioned iron-nickel alloys include additive elements. As Mn, Si, A1.Or, co.

Cu, Mo, and other elements can be contained.

Claims (1)

[Claims] During annealing after drilling a thin metal material mainly composed of iron and nickel, the dew point is controlled to -20℃ or less in an atmosphere consisting of H_275% or more and the remainder inert gas, and
Annealing is performed for 10 minutes or more at a temperature of 00℃ or higher, and then 3
A method for manufacturing a shadow mask characterized by cooling down to 00°C at a cooling rate of 1°C/sec or more.