Sughrue, Mion, Zinn, Macpeak and Seas
Punch press forming CRT shadow masks
 A CRT shadow mask 9 is made by clamping the outer periphery of a blank, stretch or draw-forming the main spherical surface 9a of the mask, releasing the clamping and wipe-forming the skirt 9c of the mask, and finally press-forming a peripheral spherical border 9e inward of the skirt and having a sharper angle of inclination. The border prevents the spring-back of the high yield strength mask material and the attendant formation of creases and dimples in the mask surface. The die press for implementing the process features an inner pad 32 surrounded by an outer pad 31, both defining spherical surfaces configured to mate with those of a punch 1 for individually forming the main surface and border of the mask. The components are arranged such that a single downward stroke of the press successively implements all of the forming steps. 
Mitsubishi Denki Kabushiki Kaisha
H B
H01J B21D
inventional inventional
Hideya
Ito