Method of processing bent and deformed portion of metal material and metal material for plastic processing used in the method

摘要

In a color cathode-ray tube with a shadow mask stretched and held by supporters while being provided with a tensile force, a member with a substantially L-shaped cross-section is used for each of the supporters, which is obtained by forming of a strip plate material having a middle part and thinner thickness-deviation portions on both sides of the middle part by rolling of a metal material; and then bending and deforming of the strip plate material in its width direction by roll forming to form a bent and deformed portion in the middle part. The supporter obtained by such a method can be reduced in weight while maintaining substantially the same strength as that of a conventional product, can be processed economically in relatively simple steps, and has less thickness variation. Therefore, an inexpensive color cathode-ray tube having stable qualities and causing less color unevenness can be provided.